Publications

• [ to appear ]
• [ To appear 2024 ]
• [ 2024 ]
• [ 2023 ]
• [ 2022 ]
• [ 2021 ]
• [ 2020 ]
• [ 2019 ]

• The Shrinking Property for NP and coNP. Glaßer, Christian; Reitwießner, Christian; Selivanov, Victor. In Theoretical Computer Science. to appear.
  • [ BibTeX ]
  @article{ShrinkNPcoNP, author = {Glaßer, Christian and Reitwießner, Christian and Selivanov, Victor}, journal = {Theoretical Computer Science}, keywords = {myown}, title = {The Shrinking Property for NP and coNP}, year = {to appear} }
• Satisfiability of Algebraic Circuits over Sets of Natural Numbers. Glaßer, Christian; Reitwießner, Christian; Travers, Stephen; Waldherr, Matthias. In Discrete Applied Mathematics. to appear.
  • [ BibTeX ]
  @article{SatCirc, author = {Glaßer, Christian and Reitwießner, Christian and Travers, Stephen and Waldherr, Matthias}, journal = {Discrete Applied Mathematics}, keywords = {myown}, title = {Satisfiability of Algebraic Circuits over Sets of Natural Numbers}, year = {to appear} }

• Emerging Technologies and Frameworks for Serious Games. Chetitah, Mounsif; von Mammen, Sebastian; Liarokapis, Fotis. In HUMAN COMPUTER INTERACTION: HCI APPLICATION DOMAINS, Vol. 5, C. Stephanidis, G. Salvendy (eds.). CRC Press, Taylor & Francis Group, To appear 2024.
  • [ BibTeX ]
  @incollection{Chetitah:2023aa, author = {Chetitah, Mounsif and von Mammen, Sebastian and Liarokapis, Fotis}, booktitle = {HUMAN COMPUTER INTERACTION: HCI APPLICATION DOMAINS}, editor = {Stephanidis, Constantine and Salvendy, Gavriel}, keywords = {myown}, publisher = {CRC Press, Taylor & Francis Group}, series = {HUMAN-COMPUTER INTERACTION: FOUNDATIONS, METHODS, TECHNOLOGIES AND APPLICATIONS}, title = {Emerging Technologies and Frameworks for Serious Games}, type = {Publication}, volume = 5, year = {To appear 2024} }

• Investigating Incoherent Depth Perception Features in Virtual Reality using Stereoscopic Impostor-Based Rendering. Waldow, Kristoffer; Decker, Lukas; Mišiak, Martin; Fuhrmann, Arnulph; Roth, Daniel; Latoschik, Marc Erich. In Proceedings of the 31st IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VR ’24). IEEE, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  Depth perception is essential for our daily experiences, aiding in orientation and interaction with our surroundings. Virtual Reality allows us to decouple such depth cues mainly represented through binocular disparity and motion parallax. Dealing with fully mesh-based rendering methods these cues are not problematic as they originate from the object’s underlying geometry. However, manipulating motion parallax, as seen in stereoscopic imposter-based rendering, raises multiple perceptual questions. Therefore, we conducted a user experiment to investigate how varying object sizes affect such visual errors and perceived 3-dimensionality, revealing an interestingly significant negative correlation and new assumptions about visual quality.

  @inproceedings{waldow2024investigating, abstract = {Depth perception is essential for our daily experiences, aiding in orientation and interaction with our surroundings. Virtual Reality allows us to decouple such depth cues mainly represented through binocular disparity and motion parallax. Dealing with fully mesh-based rendering methods these cues are not problematic as they originate from the object’s underlying geometry. However, manipulating motion parallax, as seen in stereoscopic imposter-based rendering, raises multiple perceptual questions. Therefore, we conducted a user experiment to investigate how varying object sizes affect such visual errors and perceived 3-dimensionality, revealing an interestingly significant negative correlation and new assumptions about visual quality.}, author = {Waldow, Kristoffer and Decker, Lukas and Mišiak, Martin and Fuhrmann, Arnulph and Roth, Daniel and Latoschik, Marc Erich}, booktitle = {Proceedings of the 31st IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VR '24)}, keywords = {myown}, note = {Best poster award 🏆}, publisher = {IEEE}, title = {Investigating Incoherent Depth Perception Features in Virtual Reality using Stereoscopic Impostor-Based Rendering}, year = 2024 }
• Approximating Sparsest Cut in Low-Treewidth Graphs via Combinatorial Diameter. Chalermsook, Parinya; Kaul, Matthias; Mnich, Matthias; Spoerhase, Joachim; Uniyal, Sumedha; Vaz, Daniel. In ACM Transactions on Algorithms. 2024.
  • [ BibTeX ]
  • [ URL ]
  @article{chalermsook-etal24:sparsest-cut-tree-width, author = {Chalermsook, Parinya and Kaul, Matthias and Mnich, Matthias and Spoerhase, Joachim and Uniyal, Sumedha and Vaz, Daniel}, journal = {ACM Transactions on Algorithms}, keywords = {key}, note = {to appear}, title = {Approximating Sparsest Cut in Low-Treewidth Graphs via Combinatorial Diameter}, year = 2024 }
• Am I the Odd One? Exploring (In)Congruencies in the Realism of Avatars and Virtual Others in Virtual Reality. Mal, David; Döllinger, Nina; Wolf, Erik; Wenninger, Stephan; Botsch, Mario; Wienrich, Carolin; Latoschik, Marc Erich. In Frontiers in Virtual Reality. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Virtual humans play a pivotal role in social virtual environments, shaping users' VR experiences. The diversity in available options and users' preferences can result in a heterogeneous mix of appearances among a group of virtual humans. The resulting variety in higher-order anthropomorphic and realistic cues introduces multiple (in)congruencies, eventually impacting the plausibility of the experience. In this work, we consider the impact of (in)congruencies in the realism of a group of virtual humans, including co-located others and one's self-avatar. In a 2 x 3 mixed design, participants embodied either (1) a personalized realistic or (2) a customized stylized self-avatar across three consecutive VR exposures in which they were accompanied by a group of virtual others being either (1) all realistic, (2) all stylized, or (3) mixed. Our results indicate groups of virtual others of higher realism, i.e., potentially more congruent with participants' real-world experiences and expectations, were considered more human-like, increasing the feeling of co-presence and the impression of interaction possibilities. (In)congruencies concerning the homogeneity of the group did not cause considerable effects. Furthermore, our results indicate that a self-avatar's congruence with the participant's real-world experiences concerning their own physical body yielded notable benefits for virtual body ownership and self-identification for realistic personalized avatars. Notably, the incongruence between a stylized self-avatar and a group of realistic virtual others resulted in diminished ratings of self-location and self-identification. We conclude on the implications of our findings and discuss our results within current theories of VR experiences, considering (in)congruent visual cues and their impact on the perception of virtual others, self-representation, and spatial presence.

  @article{mal2024oddone, abstract = {Virtual humans play a pivotal role in social virtual environments, shaping users' VR experiences. The diversity in available options and users' preferences can result in a heterogeneous mix of appearances among a group of virtual humans. The resulting variety in higher-order anthropomorphic and realistic cues introduces multiple (in)congruencies, eventually impacting the plausibility of the experience. In this work, we consider the impact of (in)congruencies in the realism of a group of virtual humans, including co-located others and one's self-avatar. In a 2 x 3 mixed design, participants embodied either (1) a personalized realistic or (2) a customized stylized self-avatar across three consecutive VR exposures in which they were accompanied by a group of virtual others being either (1) all realistic, (2) all stylized, or (3) mixed. Our results indicate groups of virtual others of higher realism, i.e., potentially more congruent with participants' real-world experiences and expectations, were considered more human-like, increasing the feeling of co-presence and the impression of interaction possibilities. (In)congruencies concerning the homogeneity of the group did not cause considerable effects. Furthermore, our results indicate that a self-avatar's congruence with the participant's real-world experiences concerning their own physical body yielded notable benefits for virtual body ownership and self-identification for realistic personalized avatars. Notably, the incongruence between a stylized self-avatar and a group of realistic virtual others resulted in diminished ratings of self-location and self-identification. We conclude on the implications of our findings and discuss our results within current theories of VR experiences, considering (in)congruent visual cues and their impact on the perception of virtual others, self-representation, and spatial presence.}, author = {Mal, David and Döllinger, Nina and Wolf, Erik and Wenninger, Stephan and Botsch, Mario and Wienrich, Carolin and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {dmal}, note = {Provisionally accepted}, title = {Am I the Odd One? Exploring (In)Congruencies in the Realism of Avatars and Virtual Others in Virtual Reality}, year = 2024 }
• Exploring Agent-User Personality Similarity and Dissimilarity for Virtual Reality Psychotherapy. Döllinger, Nina; Topel, Jessica; Botsch, Mario; Wienrich, Carolin; Latoschik, Marc Erich; Lugrin, Jean-Luc. In 2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW). 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Imaginary self-encounters are a common approach in psychotherapy. Recent virtual reality advancements enable innovative approaches to enhanced self-encounters using photorealistic personalized Doppelgangers (DG). Yet, next to appearance, similarity in body language could be a great driver of self-identification with a DG or a generic agent. One cost-efficient and time-saving approach could be personality-enhanced animations. We present a pilot study evaluating the effects of personality-enhanced body language in DGs and generic agents. Eleven participants evaluated a Photorealistic DG and a Generic Agent, animated in a seated position to simulate four personality types: Low and High Extraversion and Low and High Emotional Stability. Participants rated the agents' personalities and their self-identification with them. We found an overall positive relationship between a calculated personality similarity score, self-attribution, and perceived behavior-similarity. Perceived appearance-similarity was affected by personality similarity only in generic agents, indicating the potential of body language to provoke a feeling of similarity even in dissimilar-appearing agents.

  @inproceedings{dollinger2024exploring, abstract = {Imaginary self-encounters are a common approach in psychotherapy. Recent virtual reality advancements enable innovative approaches to enhanced self-encounters using photorealistic personalized Doppelgangers (DG). Yet, next to appearance, similarity in body language could be a great driver of self-identification with a DG or a generic agent. One cost-efficient and time-saving approach could be personality-enhanced animations. We present a pilot study evaluating the effects of personality-enhanced body language in DGs and generic agents. Eleven participants evaluated a Photorealistic DG and a Generic Agent, animated in a seated position to simulate four personality types: Low and High Extraversion and Low and High Emotional Stability. Participants rated the agents' personalities and their self-identification with them. We found an overall positive relationship between a calculated personality similarity score, self-attribution, and perceived behavior-similarity. Perceived appearance-similarity was affected by personality similarity only in generic agents, indicating the potential of body language to provoke a feeling of similarity even in dissimilar-appearing agents.}, author = {Döllinger, Nina and Topel, Jessica and Botsch, Mario and Wienrich, Carolin and Latoschik, Marc Erich and Lugrin, Jean-Luc}, booktitle = {2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {c.wienrich}, title = {Exploring Agent-User Personality Similarity and Dissimilarity for Virtual Reality Psychotherapy}, year = 2024 }
• Morphing Graph Drawings in the Presence of Point Obstacles. Firman, Oksana; Hegemann, Tim; Klemz, Boris; Klesen, Felix; Sieper, Marie Diana; Wolff, Alexander; Zink, Johannes. In Proc. 50th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM’24), Vol. 14519 of Lecture Notes in Computer Science, H. Fernau, S. Gaspers, R. Klasing (eds.), pp. 240–254. Springer-Verlag, 2024.
  • [ BibTeX ]
  @inproceedings{fhkkswz-mgdppo-SOFSEM24, author = {Firman, Oksana and Hegemann, Tim and Klemz, Boris and Klesen, Felix and Sieper, Marie Diana and Wolff, Alexander and Zink, Johannes}, booktitle = {Proc. 50th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM'24)}, editor = {Fernau, Henning and Gaspers, Serge and Klasing, Ralf}, keywords = {myown}, pages = {240–254}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Morphing Graph Drawings in the Presence of Point Obstacles}, volume = 14519, year = 2024 }
• Personal Space Invasion to Prevent Cyberbullying: Design, Development, and Evaluation of an Immersive Prevention Measure for Children and Adolescents. Wienrich, Carolin; Horn, Viktoria; Bürger, Arne; Krauss, Jana. In Springer Virtual Reality. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  Previous work on cyberbullying has shown that the number of victims is increasing and the need for prevention is exceptionally high among younger school students (5th-9th grade). Due to the omnipresence of cyberattacks, victims can hardly distance themselves psychologically, thus experience an intrusion in almost all areas of life. The perpetrators, on the other hand, feel the consequences of their actions even less in cyberspace. However, there is a gap between the need and the existence of innovative prevention programs tied to the digital reality of the target group and the treatment of essential aspects of psychological distance. This article explores the design space, feasibility, and effectiveness of a unique VR-based cyberbullying prevention component in a human-centered iterative approach. The central idea is reflected in creating a virtual personal space invasion with virtual objects associated with cyberbullying making the everyday intrusion of victims tangible. A pre-study revealed that harmful speech texts in bright non-removable message boxes best transferred the psychological determinants associated with a personal space invasion to virtual objects contextualized in cyberbullying scenarios. Therefore, these objects were incorporated into a virtual prevention program that was then tested in a laboratory study with 41 participants. The results showed that the intervention could trigger cognitive dissonance and empathy. In the second step, the intervention was evaluated and improved in a focus group with the actual target group of children and adolescents. The improved application was then evaluated in a school workshop for five days with 100 children and adolescents. The children understood the metaphor of virtual space invasion by the harmful text boxes and reported the expected psychological effects. They also showed great interest in VR. In summary, this paper contributes to the innovative and effective prevention of cyberbullying by using the potential of VR. It provides empirical evidence from a laboratory experiment and a field study with a large sample from the target group of children and adolescents and discusses implications for future developments.

  @article{wienrich2024personal, abstract = {Previous work on cyberbullying has shown that the number of victims is increasing and the need for prevention is exceptionally high among younger school students (5th-9th grade). Due to the omnipresence of cyberattacks, victims can hardly distance themselves psychologically, thus experience an intrusion in almost all areas of life. The perpetrators, on the other hand, feel the consequences of their actions even less in cyberspace. However, there is a gap between the need and the existence of innovative prevention programs tied to the digital reality of the target group and the treatment of essential aspects of psychological distance. This article explores the design space, feasibility, and effectiveness of a unique VR-based cyberbullying prevention component in a human-centered iterative approach. The central idea is reflected in creating a virtual personal space invasion with virtual objects associated with cyberbullying making the everyday intrusion of victims tangible. A pre-study revealed that harmful speech texts in bright non-removable message boxes best transferred the psychological determinants associated with a personal space invasion to virtual objects contextualized in cyberbullying scenarios. Therefore, these objects were incorporated into a virtual prevention program that was then tested in a laboratory study with 41 participants. The results showed that the intervention could trigger cognitive dissonance and empathy. In the second step, the intervention was evaluated and improved in a focus group with the actual target group of children and adolescents. The improved application was then evaluated in a school workshop for five days with 100 children and adolescents. The children understood the metaphor of virtual space invasion by the harmful text boxes and reported the expected psychological effects. They also showed great interest in VR. In summary, this paper contributes to the innovative and effective prevention of cyberbullying by using the potential of VR. It provides empirical evidence from a laboratory experiment and a field study with a large sample from the target group of children and adolescents and discusses implications for future developments.}, author = {Wienrich, Carolin and Horn, Viktoria and Bürger, Arne and Krauss, Jana}, journal = {Springer Virtual Reality}, keywords = {jkrauss}, title = {Personal Space Invasion to Prevent Cyberbullying: Design, Development, and Evaluation of an Immersive Prevention Measure for Children and Adolescents}, year = 2024 }
• Handling Interfaces for the Procedural Generation of Complete Buildings. Kutzias, Damian; von Mammen, Sebastian. In Proceedings of ICSE GAS Workshop 2024, Vol. 8th International Workshop on Games and Software Engineering of Emerging Advanced Technologies for Game Engineering. 2024.
  • [ BibTeX ]
  @inproceedings{damian2024handling, author = {Kutzias, Damian and von Mammen, Sebastian}, booktitle = {Proceedings of ICSE GAS Workshop 2024}, keywords = {myown}, series = {Emerging Advanced Technologies for Game Engineering}, title = {Handling Interfaces for the Procedural Generation of Complete Buildings}, volume = {8th International Workshop on Games and Software Engineering}, year = 2024 }
• Handwriting for Text Input and the Impact of XR Displays, Surface Alignments, and Sentence Complexities. Kern, Florian; Tschanter, Jonathan; Latoschik, Marc Erich. In IEEE Transactions on Visualization and Computer Graphics, pp. 1–11. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Text input is desirable across various eXtended Reality (XR) use cases and is particularly crucial for knowledge and office work. This article compares handwriting text input between Virtual Reality (VR) and Video See-Through Augmented Reality (VST AR), facilitated by physically aligned and mid-air surfaces when writing simple and complex sentences. In a 2x2x2 experimental design, 72 participants performed two ten-minute handwriting sessions, each including ten simple and ten complex sentences representing text input in real-world scenarios. Our developed handwriting application supports different XR displays, surface alignments, and handwriting recognition based on digital ink. We evaluated usability, user experience, task load, text input performance, and handwriting style. Our results indicate high usability with a successful transfer of handwriting skills to the virtual domain. XR displays and surface alignments did not impact text input speed and error rate. However, sentence complexities did, with participants achieving higher input speeds and fewer errors for simple sentences (17.85 WPM, 0.51% MSD ER) than complex sentences (15.07 WPM, 1.74% MSD ER). Handwriting on physically aligned surfaces showed higher learnability and lower physical demand, making them more suitable for prolonged handwriting sessions. Handwriting on mid-air surfaces yielded higher novelty and stimulation ratings, which might diminish with more experience. Surface alignments and sentence complexities significantly affected handwriting style, leading to enlarged and more connected cursive writing in both mid-air and for simple sentences. The study also demonstrated the benefits of using XR controllers in a pen-like posture to mimic styluses and pressure-sensitive tips on physical surfaces for input detection. We additionally provide a phrase set of simple and complex sentences as a basis for future text input studies, which can be expanded and adapted.

  @article{10460576, abstract = {Text input is desirable across various eXtended Reality (XR) use cases and is particularly crucial for knowledge and office work. This article compares handwriting text input between Virtual Reality (VR) and Video See-Through Augmented Reality (VST AR), facilitated by physically aligned and mid-air surfaces when writing simple and complex sentences. In a 2x2x2 experimental design, 72 participants performed two ten-minute handwriting sessions, each including ten simple and ten complex sentences representing text input in real-world scenarios. Our developed handwriting application supports different XR displays, surface alignments, and handwriting recognition based on digital ink. We evaluated usability, user experience, task load, text input performance, and handwriting style. Our results indicate high usability with a successful transfer of handwriting skills to the virtual domain. XR displays and surface alignments did not impact text input speed and error rate. However, sentence complexities did, with participants achieving higher input speeds and fewer errors for simple sentences (17.85 WPM, 0.51% MSD ER) than complex sentences (15.07 WPM, 1.74% MSD ER). Handwriting on physically aligned surfaces showed higher learnability and lower physical demand, making them more suitable for prolonged handwriting sessions. Handwriting on mid-air surfaces yielded higher novelty and stimulation ratings, which might diminish with more experience. Surface alignments and sentence complexities significantly affected handwriting style, leading to enlarged and more connected cursive writing in both mid-air and for simple sentences. The study also demonstrated the benefits of using XR controllers in a pen-like posture to mimic styluses and pressure-sensitive tips on physical surfaces for input detection. We additionally provide a phrase set of simple and complex sentences as a basis for future text input studies, which can be expanded and adapted.}, author = {Kern, Florian and Tschanter, Jonathan and Latoschik, Marc Erich}, journal = {IEEE Transactions on Visualization and Computer Graphics}, keywords = {vilearn}, pages = {1-11}, title = {Handwriting for Text Input and the Impact of XR Displays, Surface Alignments, and Sentence Complexities}, year = 2024 }
• Security Analysis of a Decentralized, Revocable and Verifiable Attribute-Based Encryption Scheme. Prantl, Thomas; Lauer, Marco; Horn, Lukas; Engel, Simon; Dingel, David; Kounev, Samuel; Bauer, André; Krupitzer, Christian. In Proceedings of the 19th International Conference on Availability, Reliability and Security, of ARES 2024. ACM, 2024.
  • [ BibTeX ]
  @inproceedings{ARES_2024_ABE, author = {Prantl, Thomas and Lauer, Marco and Horn, Lukas and Engel, Simon and Dingel, David and Kounev, Samuel and Bauer, André and Krupitzer, Christian}, booktitle = {Proceedings of the 19th International Conference on Availability, Reliability and Security}, keywords = {descartes}, publisher = {ACM}, series = {ARES 2024}, title = {Security Analysis of a Decentralized, Revocable and Verifiable Attribute-Based Encryption Scheme}, year = 2024 }
• Marina: Realizing ML-Driven Real-Time Network Traffic Monitoring at Terabit Scale. Seufert, Michael; Dietz, Katharina; Wehner, Nikolas; Geißler, Stefan; Schüler, Joshua; Wolz, Manuel; Hotho, Andreas; Casas, Pedro; Hoßfeld, Tobias; Feldmann, Anja. In IEEE Transactions on Network and Service Management, pp. 1–1. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  Network operators require real-time traffic monitoring insights to provide high performance and security to their customers. It has been shown that artificial intelligence and machine learning (ML) can improve the visibility of telemetry systems, especially with encrypted traffic. However, current solutions cannot cope with high traffic rates and volumes in large-scale networks. To realize the ML-driven network intelligence paradigm at terabit scale, we design Marina, a system that spreads monitoring over a highly efficient data plane, which can extract traffic statistics at line rate, and a powerful ML server, which can run monitoring inference using complex ML models. We apply temporal microaggregation into sub-second time slots and extract moment-based statistics. These allow to flexibly obtain accurate ML-based monitoring decisions during the next time slot. To demonstrate the scalability of our design, we implement and evaluate a Marina data plane prototype on a Barefoot Wedge 100BF-65X P4 switch, which can monitor more than 520,000 concurrent flows at full switching capacity of 6.4 Tbps. We validate the analytics capabilities enabled by our Marina implementation for four ML-driven real-time monitoring tasks with a broad set of standard ML models, achieving comparable or better than state-of-the-art results.

  @article{10480735, abstract = {Network operators require real-time traffic monitoring insights to provide high performance and security to their customers. It has been shown that artificial intelligence and machine learning (ML) can improve the visibility of telemetry systems, especially with encrypted traffic. However, current solutions cannot cope with high traffic rates and volumes in large-scale networks. To realize the ML-driven network intelligence paradigm at terabit scale, we design Marina, a system that spreads monitoring over a highly efficient data plane, which can extract traffic statistics at line rate, and a powerful ML server, which can run monitoring inference using complex ML models. We apply temporal microaggregation into sub-second time slots and extract moment-based statistics. These allow to flexibly obtain accurate ML-based monitoring decisions during the next time slot. To demonstrate the scalability of our design, we implement and evaluate a Marina data plane prototype on a Barefoot Wedge 100BF-65X P4 switch, which can monitor more than 520,000 concurrent flows at full switching capacity of 6.4 Tbps. We validate the analytics capabilities enabled by our Marina implementation for four ML-driven real-time monitoring tasks with a broad set of standard ML models, achieving comparable or better than state-of-the-art results.}, author = {Seufert, Michael and Dietz, Katharina and Wehner, Nikolas and Geißler, Stefan and Schüler, Joshua and Wolz, Manuel and Hotho, Andreas and Casas, Pedro and Hoßfeld, Tobias and Feldmann, Anja}, journal = {IEEE Transactions on Network and Service Management}, keywords = {traffic}, pages = {1-1}, title = {Marina: Realizing ML-Driven Real-Time Network Traffic Monitoring at Terabit Scale}, year = 2024 }
• Simulating Microservice-based Architectures for Resilience Assessment Enriched by Authentic Container Orchestration. Frank, Sebastian; Straesser, Martin; Wagner, Lion; Haas, Patrick; Hakamian, Alireza; Kounev, Samuel; Van Hoorn, André. In Software Engineering 2024. Gesellschaft für Informatik e.V., Bonn, 2024.
  • [ BibTeX ]
  @incollection{Frank2024Simulating, address = {Bonn}, author = {Frank, Sebastian and Straesser, Martin and Wagner, Lion and Haas, Patrick and Hakamian, Alireza and Kounev, Samuel and Van Hoorn, André}, booktitle = {Software Engineering 2024}, keywords = {container_orchestration}, publisher = {Gesellschaft für Informatik e.V.}, title = {Simulating Microservice-based Architectures for Resilience Assessment Enriched by Authentic Container Orchestration}, year = 2024 }
• Autoscaling Rethought: A Continuous, Decentralized Approach. Straesser, Martin. 2024.
  • [ BibTeX ]
  @presentation{straesser2024rethought, author = {Straesser, Martin}, keywords = {microservices}, title = {Autoscaling Rethought: A Continuous, Decentralized Approach}, year = 2024 }
• Eliminating Crossings in Ordered Graphs. Agrawal, Akanksha; Cabello, Sergio; Kaufmann, Michael; Saurabh, Saket; Sharma, Roohani; Uno, Yushi; Wolff, Alexander. In Proc. 19th Scand. Symp. Algorithm Theory (SWAT’24), of LIPIcs, H. Bodlaender (ed.). Schloss Dagstuhl – Leibniz-Institut für Informatik, 2024.
  • [ BibTeX ]
  @inproceedings{ackssuw-ecog-SWAT24, author = {Agrawal, Akanksha and Cabello, Sergio and Kaufmann, Michael and Saurabh, Saket and Sharma, Roohani and Uno, Yushi and Wolff, Alexander}, booktitle = {Proc. 19th Scand. Symp. Algorithm Theory (SWAT'24)}, editor = {Bodlaender, Hans}, keywords = {hitting_set}, note = {To appear.}, publisher = {Schloss Dagstuhl – Leibniz-Institut für Informatik}, series = {LIPIcs}, title = {Eliminating Crossings in Ordered Graphs}, year = 2024 }
• Adjacency Graphs of Polyhedral Surfaces. Arseneva, Elena; Kleist, Linda; Klemz, Boris; Löffler, Maarten; Schulz, André; Vogtenhuber, Birgit; Wolff, Alexander. In Discrete \& Computational Geometry. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  We study whether a given graph can be realized as an adjacency graph of the polygonal cells of a polyhedral surface in~$\mathbb{R}^3$. We show that every graph is realizable as a polyhedral surface with arbitrary polygonal cells, and that this is not true if we require the cells to be convex. In particular, if the given graph contains $K_5$, $K_{5,81}$, or any nonplanar $3$-tree as a subgraph, no such realization exists. On the other hand, all planar graphs, $K_{4,4}$, and $K_{3,5}$ can be realized with convex cells. The same holds for any subdivision of any graph where each edge is subdivided at least once, and, by a result from McMullen et al.~(1983), for any hypercube. \par Our results have implications on the maximum density of graphs describing polyhedral surfaces with convex cells: The realizability of hypercubes shows that the maximum number of edges over all realizable $n$-vertex graphs is in $\Omega(n \log n)$. From the non-realizability of $K_{5,81}$, we obtain that any realizable $n$-vertex graph has $\bigO(n^{9/5})$ edges. As such, these graphs can be considerably denser than planar graphs, but not arbitrarily dense.

  @article{akklsvw-dgps-DCG24, abstract = {We study whether a given graph can be realized as an adjacency graph of the polygonal cells of a polyhedral surface in $\mathbb{R}^3$. We show that every graph is realizable as a polyhedral surface with arbitrary polygonal cells, and that this is not true if we require the cells to be convex. In particular, if the given graph contains $K_5$, $K_{5,81}$, or any nonplanar $3$-tree as a subgraph, no such realization exists. On the other hand, all planar graphs, $K_{4,4}$, and $K_{3,5}$ can be realized with convex cells. The same holds for any subdivision of any graph where each edge is subdivided at least once, and, by a result from McMullen et al. (1983), for any hypercube. \par Our results have implications on the maximum density of graphs describing polyhedral surfaces with convex cells: The realizability of hypercubes shows that the maximum number of edges over all realizable $n$-vertex graphs is in $\Omega(n \log n)$. From the non-realizability of $K_{5,81}$, we obtain that any realizable $n$-vertex graph has $\bigO(n^{9/5})$ edges. As such, these graphs can be considerably denser than planar graphs, but not arbitrarily dense.}, author = {Arseneva, Elena and Kleist, Linda and Klemz, Boris and Löffler, Maarten and Schulz, André and Vogtenhuber, Birgit and Wolff, Alexander}, journal = {Discrete \& Computational Geometry}, keywords = {realizability}, title = {Adjacency Graphs of Polyhedral Surfaces}, year = 2024 }
• Unveiling Temporal Performance Deviation: Leveraging Clustering in Microservices Performance Analysis. Bauer, André; Dittus, Timo; Straesser, Martin; Kamatar, Alok; Baughman, Matt; Beierlieb, Lukas; Hadry, Marius; Grillmeyer, Daniel; Lubas, Yannik; Kounev, Samuel; Foster, Ian; Chard, Kyle. In Companion of the 15th ACM/SPEC International Conference on Performance Engineering, of ICPE ’24 Companion, pp. 72–76. Association for Computing Machinery, New York, NY, USA, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  As the market for cloud computing continues to grow, an increasing number of users are deploying applications as microservices. The shift introduces unique challenges in identifying and addressing performance issues, particularly within large and complex infrastructures. To address this challenge, we propose a methodology that unveils temporal performance deviations in microservices by clustering containers based on their performance characteristics at different time intervals. Showcasing our methodology on the Alibaba dataset, we found both stable and dynamic performance patterns, providing a valuable tool for enhancing overall performance and reliability in modern application landscapes.

  @inproceedings{10.1145/3629527.3651843, abstract = {As the market for cloud computing continues to grow, an increasing number of users are deploying applications as microservices. The shift introduces unique challenges in identifying and addressing performance issues, particularly within large and complex infrastructures. To address this challenge, we propose a methodology that unveils temporal performance deviations in microservices by clustering containers based on their performance characteristics at different time intervals. Showcasing our methodology on the Alibaba dataset, we found both stable and dynamic performance patterns, providing a valuable tool for enhancing overall performance and reliability in modern application landscapes.}, address = {New York, NY, USA}, author = {Bauer, André and Dittus, Timo and Straesser, Martin and Kamatar, Alok and Baughman, Matt and Beierlieb, Lukas and Hadry, Marius and Grillmeyer, Daniel and Lubas, Yannik and Kounev, Samuel and Foster, Ian and Chard, Kyle}, booktitle = {Companion of the 15th ACM/SPEC International Conference on Performance Engineering}, keywords = {descartes}, pages = {72–76}, publisher = {Association for Computing Machinery}, series = {ICPE '24 Companion}, title = {Unveiling Temporal Performance Deviation: Leveraging Clustering in Microservices Performance Analysis}, year = 2024 }
• Effect of Duration and Delay on the Identifiability of VR Motion. Miller, Mark R; Nair, Vivek C; Han, Eugy; DeVeaux, Cyan; Rack, Christian; Wang, Rui; Huang, Brandon; Latoschik, Marc Erich; O’Brien, James F; Bailenson, Jeremy N. In Proceedings of the International Workshop on Privacy and Security in Augmented, Virtual, and eXtended Realities (SEPAR). 2024.
  • [ BibTeX ]
  @inproceedings{miller2024effect, author = {Miller, Mark R and Nair, Vivek C and Han, Eugy and DeVeaux, Cyan and Rack, Christian and Wang, Rui and Huang, Brandon and Latoschik, Marc Erich and O'Brien, James F and Bailenson, Jeremy N}, booktitle = {Proceedings of the International Workshop on Privacy and Security in Augmented, Virtual, and eXtended Realities (SEPAR)}, keywords = {schell}, note = {to be published}, title = {Effect of Duration and Delay on the Identifiability of VR Motion}, year = 2024 }
• Inferring Private Personal Attributes of Virtual Reality Users from Ecologically Valid Head and Hand Motion Data. Nair, Vivek; Rack, Christian; Guo, Wenbo; Wang, Rui; Li, Shuixian; Huang, Brandon; Cull, Atticus; O’Brien, James F.; Latoschik, Marc; Rosenberg, Louis; Song, Dawn. In 2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW), pp. 477–484. 2024.
  • [ BibTeX ]
  @inproceedings{10536245, author = {Nair, Vivek and Rack, Christian and Guo, Wenbo and Wang, Rui and Li, Shuixian and Huang, Brandon and Cull, Atticus and O'Brien, James F. and Latoschik, Marc and Rosenberg, Louis and Song, Dawn}, booktitle = {2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {schell}, pages = {477-484}, title = {Inferring Private Personal Attributes of Virtual Reality Users from Ecologically Valid Head and Hand Motion Data}, year = 2024 }
• Comprehensive Exploration of Synthetic Data Generation: A Survey. Bauer, André; and Trapp, Simon; and Stenger, Michael; and Leppich, Robert; and Kounev, Samuel; and Leznik, Mark; and Chard, Kyle; and Foster, Ian. In arXiv preprint, p. 103. 2024.
  • [ BibTeX ]
  @article{bauer2024comprehensive, author = {Bauer, André and and Trapp, Simon and and Stenger, Michael and and Leppich, Robert and and Kounev, Samuel and and Leznik, Mark and and Chard, Kyle and and Foster, Ian}, journal = {arXiv preprint}, keywords = {t_journalmagazine}, note = {https://doi.org/10.48550/arXiv.2401.02524}, pages = 103, title = {Comprehensive Exploration of Synthetic Data Generation: A Survey}, year = 2024 }
• Individual-, System-, and Application-Related Factors Influencing the Perception of Virtual Humans in Virtual Environments. Technical Report (PhD dissertation), . Wolf, Erik. PhD dissertation. Julius-Maximilians-Universität Würzburg, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  Mixed, augmented, and virtual reality, collectively known as extended reality (XR), allows users to immerse themselves in virtual environments and engage in experiences surpassing reality's boundaries. Virtual humans are ubiquitous in such virtual environments and can be utilized for myriad purposes, offering the potential to greatly impact daily life. Through the embodiment of virtual humans, XR offers the opportunity to influence how we see ourselves and others. In this function, virtual humans serve as a predefined stimulus whose perception is elementary for researchers, application designers, and developers to understand. This dissertation aims to investigate the influence of individual-, system-, and application-related factors on the perception of virtual humans in virtual environments, focusing on their potential use as stimuli in the domain of body perception. Individual-related factors encompass influences based on the user's characteristics, such as appearance, attitudes, and concerns. System-related factors relate to the technical properties of the system that implements the virtual environment, such as the level of immersion. Application-related factors refer to design choices and specific implementations of virtual humans within virtual environments, such as their rendering or animation style. This dissertation provides a contextual framework and reviews the relevant literature on factors influencing the perception of virtual humans. To address identified research gaps, it reports on five empirical studies analyzing quantitative and qualitative data from a total of 165 participants. The studies utilized a custom-developed XR system, enabling users to embody rapidly generated, photorealistically personalized virtual humans that can be realistically altered in body weight and observed using different immersive XR displays. The dissertation's findings showed, for example, that embodiment and personalization of virtual humans serve as self-related cues and moderate the perception of their body weight based on the user's body weight. They also revealed a display bias that significantly influences the perception of virtual humans, with disparities in body weight perception of up to nine percent between different immersive XR displays. Based on all findings, implications for application design were derived, including recommendations regarding reconstruction, animation, body weight modification, and body weight estimation methods for virtual humans, but also for the general user experience. By revealing influences on the perception of virtual humans, this dissertation contributes to understanding the intricate relationship between users and virtual humans. The findings and implications presented have the potential to enhance the design and development of virtual humans, leading to improved user experiences and broader applications beyond the domain of body perception.

  @phdthesis{wolf2024thesis, abstract = {Mixed, augmented, and virtual reality, collectively known as extended reality (XR), allows users to immerse themselves in virtual environments and engage in experiences surpassing reality's boundaries. Virtual humans are ubiquitous in such virtual environments and can be utilized for myriad purposes, offering the potential to greatly impact daily life. Through the embodiment of virtual humans, XR offers the opportunity to influence how we see ourselves and others. In this function, virtual humans serve as a predefined stimulus whose perception is elementary for researchers, application designers, and developers to understand. This dissertation aims to investigate the influence of individual-, system-, and application-related factors on the perception of virtual humans in virtual environments, focusing on their potential use as stimuli in the domain of body perception. Individual-related factors encompass influences based on the user's characteristics, such as appearance, attitudes, and concerns. System-related factors relate to the technical properties of the system that implements the virtual environment, such as the level of immersion. Application-related factors refer to design choices and specific implementations of virtual humans within virtual environments, such as their rendering or animation style. This dissertation provides a contextual framework and reviews the relevant literature on factors influencing the perception of virtual humans. To address identified research gaps, it reports on five empirical studies analyzing quantitative and qualitative data from a total of 165 participants. The studies utilized a custom-developed XR system, enabling users to embody rapidly generated, photorealistically personalized virtual humans that can be realistically altered in body weight and observed using different immersive XR displays. The dissertation's findings showed, for example, that embodiment and personalization of virtual humans serve as self-related cues and moderate the perception of their body weight based on the user's body weight. They also revealed a display bias that significantly influences the perception of virtual humans, with disparities in body weight perception of up to nine percent between different immersive XR displays. Based on all findings, implications for application design were derived, including recommendations regarding reconstruction, animation, body weight modification, and body weight estimation methods for virtual humans, but also for the general user experience. By revealing influences on the perception of virtual humans, this dissertation contributes to understanding the intricate relationship between users and virtual humans. The findings and implications presented have the potential to enhance the design and development of virtual humans, leading to improved user experiences and broader applications beyond the domain of body perception.}, author = {Wolf, Erik}, keywords = {myown}, note = {Under review}, school = {Julius-Maximilians-Universität Würzburg}, title = {Individual-, System-, and Application-Related Factors Influencing the Perception of Virtual Humans in Virtual Environments}, year = 2024 }
• From Avatars to Agents: Self-Related Cues through Embodiment and Personalization Affect Body Perception in Virtual Reality. Fiedler, Marie Luisa; Wolf, Erik; Döllinger, Nina; Mal, David; Botsch, Mario; Latoschik, Marc Erich; Wienrich, Carolin. In IEEE Transactions on Visualization and Computer Graphics, pp. 1–11. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Our work investigates the influence of self-related cues in the design of virtual humans on body perception in virtual reality. In a 2x2 mixed design, 64 participants faced photorealistic virtual humans either as a motion-synchronized embodied avatar or as an autonomous moving agent, appearing subsequently with a personalized and generic texture. Our results unveil that self-related cues through embodiment and personalization yield an individual and complemented increase in participants' sense of embodiment and self-identification towards the virtual human. Different body weight modification and estimation tasks further showed an impact of both factors on participants' body weight perception. Additional analyses revealed that the participant's body mass index predicted body weight estimations in all conditions and that participants' self-esteem and body shape concerns correlated with different body weight perception results. Hence, we have demonstrated the occurrence of double standards through induced self-related cues in virtual human perception, especially through embodiment.

  @article{fiedler2024selfcues, abstract = {Our work investigates the influence of self-related cues in the design of virtual humans on body perception in virtual reality. In a 2x2 mixed design, 64 participants faced photorealistic virtual humans either as a motion-synchronized embodied avatar or as an autonomous moving agent, appearing subsequently with a personalized and generic texture. Our results unveil that self-related cues through embodiment and personalization yield an individual and complemented increase in participants' sense of embodiment and self-identification towards the virtual human. Different body weight modification and estimation tasks further showed an impact of both factors on participants' body weight perception. Additional analyses revealed that the participant's body mass index predicted body weight estimations in all conditions and that participants' self-esteem and body shape concerns correlated with different body weight perception results. Hence, we have demonstrated the occurrence of double standards through induced self-related cues in virtual human perception, especially through embodiment.}, author = {Fiedler, Marie Luisa and Wolf, Erik and Döllinger, Nina and Mal, David and Botsch, Mario and Latoschik, Marc Erich and Wienrich, Carolin}, journal = {IEEE Transactions on Visualization and Computer Graphics}, keywords = {mfiedler}, note = {To be published}, pages = {1-11}, title = {From Avatars to Agents: Self-Related Cues through Embodiment and Personalization Affect Body Perception in Virtual Reality}, year = 2024 }
• Simulating Microservice-based Architectures for Resilience Assessment Enriched by Authentic Container Orchestration. Frank, Sebastian; Straesser, Martin; Wagner, Lion; Haas, Patrick; Hakamian, Alireza; Kounev, Samuel; Van Hoorn, André. In Software Engineering 2024. Gesellschaft für Informatik e.V., Bonn, 2024.
  • [ BibTeX ]
  @incollection{Frank2024Simulating, address = {Bonn}, author = {Frank, Sebastian and Straesser, Martin and Wagner, Lion and Haas, Patrick and Hakamian, Alireza and Kounev, Samuel and Van Hoorn, André}, booktitle = {Software Engineering 2024}, keywords = {container_orchestration}, publisher = {Gesellschaft für Informatik e.V.}, title = {Simulating Microservice-based Architectures for Resilience Assessment Enriched by Authentic Container Orchestration}, year = 2024 }
• Effect of Data Degradation on Motion Re-Identification. Nair, Vivek; Miller, Mark Roman; Wang, Rui; Huang, Brandon; Rack, Christian; Latoschik, Marc Erich; O’Brien, James. In Proceedings of the International Workshop on Privacy and Security in Augmented, Virtual, and eXtended Realities (SEPAR). 2024.
  • [ BibTeX ]
  @inproceedings{nair2024effect, author = {Nair, Vivek and Miller, Mark Roman and Wang, Rui and Huang, Brandon and Rack, Christian and Latoschik, Marc Erich and O'Brien, James}, booktitle = {Proceedings of the International Workshop on Privacy and Security in Augmented, Virtual, and eXtended Realities (SEPAR)}, keywords = {schell}, note = {To be published}, title = {Effect of Data Degradation on Motion Re-Identification}, year = 2024 }
• Effects of Nonverbal Communication of Virtual Agents on Social Pressure and Encouragement in VR. Martinez Pankotsch, Pascal; Oberdörfer, Sebastian; Latoschik, Marc Erich. In Proceedings of the 31st IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VR ’24). IEEE, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Our study investigated how virtual agents impact users in challenging VR environments, exploring if nonverbal animations affect social pressure, positive encouragement, and trust in 30 female participants. Despite showing signs of pressure and support during the experimental trials, we could not find significant differences in post-exposure measurements of social pressure and encouragement, interpersonal trust, and well-being. While inconclusive, the findings suggest potential, indicating the need for further research with improved animations and a larger sample size for validation.

  @inproceedings{martinezpankotsch2024effects, abstract = {Our study investigated how virtual agents impact users in challenging VR environments, exploring if nonverbal animations affect social pressure, positive encouragement, and trust in 30 female participants. Despite showing signs of pressure and support during the experimental trials, we could not find significant differences in post-exposure measurements of social pressure and encouragement, interpersonal trust, and well-being. While inconclusive, the findings suggest potential, indicating the need for further research with improved animations and a larger sample size for validation.}, author = {Martinez Pankotsch, Pascal and Oberdörfer, Sebastian and Latoschik, Marc Erich}, booktitle = {Proceedings of the 31st IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VR '24)}, keywords = {dark-sides-vr}, organization = {IEEE}, title = {Effects of Nonverbal Communication of Virtual Agents on Social Pressure and Encouragement in VR}, year = 2024 }
• Universal Access for Social XR Across Devices: The Impact of Immersion on the Experience in Asymmetric Virtual Collaboration. Merz, Christian; Göttfert, Christopher; Wienrich, Carolin; Latoschik, Marc Erich. In Proceedings of the 31st IEEE Virtual Reality conference (VR ’24). IEEE, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This article investigates the influence of input/output device characteristics and degrees of immersion on the User Experience (UX) of specific eXtended Reality (XR) effects, i.e., presence, self-perception, other-perception, and task perception. It targets universal access to social XR, where dedicated XR hardware is unavailable or can not be used, but participation is desirable or even necessary. We compare three different device configurations: (i) desktop screen with mouse, (ii) desktop screen with tracked controllers, and (iii) Head-Mounted Display (HMD) with tracked controllers. 87 participants took part in collaborative dyadic interaction (a sorting task) with asymmetric device configurations in a specifically developed social XR. In line with prior research, the sense of presence and embodiment were significantly lower for the desktop setups. However, we only found minor differences in task load and no differences in usability and enjoyment of the task between the conditions. Additionally, the perceived humanness and virtual human plausibility of the other were not affected, no matter the device used. Finally, there was no impact regarding co-presence and social presence independent of the level of immersion of oneself or the other. We conclude that the device in social XR is important for self-perception and presence. However, our results indicate that the devices do not affect important UX and usability aspects, specifically, the qualities of social interaction in collaborative scenarios, paving the way for universal access to social XR encounters and significantly promoting participation.

  @inproceedings{merz2024universal, abstract = {This article investigates the influence of input/output device characteristics and degrees of immersion on the User Experience (UX) of specific eXtended Reality (XR) effects, i.e., presence, self-perception, other-perception, and task perception. It targets universal access to social XR, where dedicated XR hardware is unavailable or can not be used, but participation is desirable or even necessary. We compare three different device configurations: (i) desktop screen with mouse, (ii) desktop screen with tracked controllers, and (iii) Head-Mounted Display (HMD) with tracked controllers. 87 participants took part in collaborative dyadic interaction (a sorting task) with asymmetric device configurations in a specifically developed social XR. In line with prior research, the sense of presence and embodiment were significantly lower for the desktop setups. However, we only found minor differences in task load and no differences in usability and enjoyment of the task between the conditions. Additionally, the perceived humanness and virtual human plausibility of the other were not affected, no matter the device used. Finally, there was no impact regarding co-presence and social presence independent of the level of immersion of oneself or the other. We conclude that the device in social XR is important for self-perception and presence. However, our results indicate that the devices do not affect important UX and usability aspects, specifically, the qualities of social interaction in collaborative scenarios, paving the way for universal access to social XR encounters and significantly promoting participation.}, author = {Merz, Christian and Göttfert, Christopher and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {Proceedings of the 31st IEEE Virtual Reality conference (VR '24)}, keywords = {merz}, organization = {IEEE}, title = {Universal Access for Social XR Across Devices: The Impact of Immersion on the Experience in Asymmetric Virtual Collaboration}, year = 2024 }
• Unveiling Temporal Performance Deviation: Leveraging Clustering in Microservices Performance Analysis. Bauer, André; Dittus, Timo; Straesser, Martin; Kamatar, Alok; Baughman, Matt; Beierlieb, Lukas; Hadry, Marius; Grillmeyer, Daniel; Lubas, Yannik; Kounev, Samuel; Foster, Ian; Chard, Kyle. In Companion of the 15th ACM/SPEC International Conference on Performance Engineering, of ICPE ’24 Companion, pp. 72–76. Association for Computing Machinery, New York, NY, USA, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  As the market for cloud computing continues to grow, an increasing number of users are deploying applications as microservices. The shift introduces unique challenges in identifying and addressing performance issues, particularly within large and complex infrastructures. To address this challenge, we propose a methodology that unveils temporal performance deviations in microservices by clustering containers based on their performance characteristics at different time intervals. Showcasing our methodology on the Alibaba dataset, we found both stable and dynamic performance patterns, providing a valuable tool for enhancing overall performance and reliability in modern application landscapes.

  @inproceedings{10.1145/3629527.3651843, abstract = {As the market for cloud computing continues to grow, an increasing number of users are deploying applications as microservices. The shift introduces unique challenges in identifying and addressing performance issues, particularly within large and complex infrastructures. To address this challenge, we propose a methodology that unveils temporal performance deviations in microservices by clustering containers based on their performance characteristics at different time intervals. Showcasing our methodology on the Alibaba dataset, we found both stable and dynamic performance patterns, providing a valuable tool for enhancing overall performance and reliability in modern application landscapes.}, address = {New York, NY, USA}, author = {Bauer, André and Dittus, Timo and Straesser, Martin and Kamatar, Alok and Baughman, Matt and Beierlieb, Lukas and Hadry, Marius and Grillmeyer, Daniel and Lubas, Yannik and Kounev, Samuel and Foster, Ian and Chard, Kyle}, booktitle = {Companion of the 15th ACM/SPEC International Conference on Performance Engineering}, keywords = {descartes}, pages = {72–76}, publisher = {Association for Computing Machinery}, series = {ICPE '24 Companion}, title = {Unveiling Temporal Performance Deviation: Leveraging Clustering in Microservices Performance Analysis}, year = 2024 }
• Unveiling Temporal Performance Deviation: Leveraging Clustering in Microservices Performance Analysis. Bauer, André; Dittus, Timo; Straesser, Martin; Kamatar, Alok; Baughman, Matt; Beierlieb, Lukas; Hadry, Marius; Grillmeyer, Daniel; Lubas, Yannik; Kounev, Samuel; Foster, Ian; Chard, Kyle. In Companion of the 15th ACM/SPEC International Conference on Performance Engineering, of ICPE ’24 Companion, pp. 72–76. Association for Computing Machinery, New York, NY, USA, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  As the market for cloud computing continues to grow, an increasing number of users are deploying applications as microservices. The shift introduces unique challenges in identifying and addressing performance issues, particularly within large and complex infrastructures. To address this challenge, we propose a methodology that unveils temporal performance deviations in microservices by clustering containers based on their performance characteristics at different time intervals. Showcasing our methodology on the Alibaba dataset, we found both stable and dynamic performance patterns, providing a valuable tool for enhancing overall performance and reliability in modern application landscapes.

  @inproceedings{10.1145/3629527.3651843, abstract = {As the market for cloud computing continues to grow, an increasing number of users are deploying applications as microservices. The shift introduces unique challenges in identifying and addressing performance issues, particularly within large and complex infrastructures. To address this challenge, we propose a methodology that unveils temporal performance deviations in microservices by clustering containers based on their performance characteristics at different time intervals. Showcasing our methodology on the Alibaba dataset, we found both stable and dynamic performance patterns, providing a valuable tool for enhancing overall performance and reliability in modern application landscapes.}, address = {New York, NY, USA}, author = {Bauer, André and Dittus, Timo and Straesser, Martin and Kamatar, Alok and Baughman, Matt and Beierlieb, Lukas and Hadry, Marius and Grillmeyer, Daniel and Lubas, Yannik and Kounev, Samuel and Foster, Ian and Chard, Kyle}, booktitle = {Companion of the 15th ACM/SPEC International Conference on Performance Engineering}, keywords = {descartes}, pages = {72–76}, publisher = {Association for Computing Machinery}, series = {ICPE '24 Companion}, title = {Unveiling Temporal Performance Deviation: Leveraging Clustering in Microservices Performance Analysis}, year = 2024 }
• Influence of Virtual Shoe Formality on Gait and Cognitive Performance in a VR Walking Task. Oberdörfer, Sebastian; Birnstiel, Sandra; Latoschik, Marc Erich. In Proceedings of the 31st IEEE Virtual Reality conference (VR ’24). IEEE, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Depending on their formality, clothes do not only change one's appearance, but can also influence behavior and cognitive processes. Shoes are a special aspect of an outfit. Besides coming in various degrees of formality, their structure can affect human gait. Avatars used to embody users in immersive Virtual Reality (VR) can wear any kind of clothing. According to the Proteus Effect, the appearance of a user's avatar can influence their behavior. Users change their behavior in accordance to the expected behavior of the avatar. In our study, we embody 39 participants with a generic avatar of the user's gender wearing three different pairs of shoes as within condition. The shoes differ in degree of formality. We measure the gait during a 2-minute walking task during which participants wore the same real shoe and assess selective attention using the Stroop task. Our results show significant differences in gait between the tested virtual shoe pairs. We found small effects between the three shoe conditions with respect to selective attention. However, we found no significant differences with respect to correct items and response time in the Stroop task. Thus, our results indicate that virtual shoes are accepted by users and, although not eliciting any physical constraints, lead to changes in gait. This suggests that users not only adjust personal behavior according to the Proteus Effect, but also are affected by virtual biomechanical constraints. Also, our results suggest a potential influence of virtual clothing on cognitive performance.

  @inproceedings{oberdorfer2024influence, abstract = {Depending on their formality, clothes do not only change one's appearance, but can also influence behavior and cognitive processes. Shoes are a special aspect of an outfit. Besides coming in various degrees of formality, their structure can affect human gait. Avatars used to embody users in immersive Virtual Reality (VR) can wear any kind of clothing. According to the Proteus Effect, the appearance of a user's avatar can influence their behavior. Users change their behavior in accordance to the expected behavior of the avatar. In our study, we embody 39 participants with a generic avatar of the user's gender wearing three different pairs of shoes as within condition. The shoes differ in degree of formality. We measure the gait during a 2-minute walking task during which participants wore the same real shoe and assess selective attention using the Stroop task. Our results show significant differences in gait between the tested virtual shoe pairs. We found small effects between the three shoe conditions with respect to selective attention. However, we found no significant differences with respect to correct items and response time in the Stroop task. Thus, our results indicate that virtual shoes are accepted by users and, although not eliciting any physical constraints, lead to changes in gait. This suggests that users not only adjust personal behavior according to the Proteus Effect, but also are affected by virtual biomechanical constraints. Also, our results suggest a potential influence of virtual clothing on cognitive performance.}, author = {Oberdörfer, Sebastian and Birnstiel, Sandra and Latoschik, Marc Erich}, booktitle = {Proceedings of the 31st IEEE Virtual Reality conference (VR '24)}, keywords = {dark-sides-vr}, organization = {IEEE}, title = {Influence of Virtual Shoe Formality on Gait and Cognitive Performance in a VR Walking Task}, year = 2024 }
• Outerplanar and Forest Storyplans. Fiala, Jiří; Firman, Oksana; Liotta, Giuseppe; Wolff, Alexander; Zink, Johannes. In Proc. 50th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM’24), Vol. 14519 of Lecture Notes in Computer Science, H. Fernau, S. Gaspers, R. Klasing (eds.), pp. 211–225. Springer-Verlag, 2024.
  • [ BibTeX ]
  @inproceedings{fflwz-ofs-SOFSEM24, author = {Fiala, Jiří and Firman, Oksana and Liotta, Giuseppe and Wolff, Alexander and Zink, Johannes}, booktitle = {Proc. 50th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM'24)}, editor = {Fernau, Henning and Gaspers, Serge and Klasing, Ralf}, keywords = {myown}, pages = {211–225}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Outerplanar and Forest Storyplans}, volume = 14519, year = 2024 }
• Constrained and Ordered Level Planarity Parameterized by the Number of Levels. Blažej, Vacláv; Klemz, Boris; Klesen, Felix; Sieper, Marie Diana; Wolff, Alexander; Zink, Johannes. In Proc. 40th Annu. Sympos. Comput. Geom. (SoCG’24), Vol. 293 of LIPIcs, W. Mulzer, J. M. Phillips (eds.). Schloss Dagstuhl – Leibniz-Zentrum für Informatik, 2024.
  • [ BibTeX ]
  @inproceedings{bkkswz-colpp-SoCG24, author = {Blažej, Vacláv and Klemz, Boris and Klesen, Felix and Sieper, Marie Diana and Wolff, Alexander and Zink, Johannes}, booktitle = {Proc. 40th Annu. Sympos. Comput. Geom. (SoCG'24)}, editor = {Mulzer, Wolfgang and Phillips, Jeff M.}, keywords = {myown}, publisher = {Schloss Dagstuhl – Leibniz-Zentrum für Informatik}, series = {LIPIcs}, title = {Constrained and Ordered Level Planarity Parameterized by the Number of Levels}, volume = 293, year = 2024 }
• Promoting Eco-Friendly Behavior through Virtual Reality - Implementation and Evaluation of Immersive Feedback Conditions of a Virtual CO2 Calculator. Wienrich, Carolin; Vogt, Stephanie; Döllinger, Nina; Obremski, David. In 2024 CHI Conference on Human Factors in Computing Systems. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Climate change is one of the most pressing global challenges in the 21st century. Urgent actions favoring the environment's well-being are essential to mitigate its potentially irreversible consequences. However, the delayed and often distant nature of the effects of sustainable behavior makes it challenging for individuals to connect with the issue personally. Immersive media are an opportunity to introduce innovative feedback mechanisms to highlight the urgency of behavior effects. We introduce a VR carbon calculator that visualizes users' annual carbon footprint as CO2-filled balloons over multiple periods. In a 2x2 design, participants calculated and visualized their carbon footprint numerically or as balloons over one or three years. We found no effect of our visualization but a significant impact of the visualized period on participants' environmental self-efficacy. These findings emphasize the importance of target-oriented design in VR behavior interventions.

  @inproceedings{wienrich2024promoting, abstract = {Climate change is one of the most pressing global challenges in the 21st century. Urgent actions favoring the environment's well-being are essential to mitigate its potentially irreversible consequences. However, the delayed and often distant nature of the effects of sustainable behavior makes it challenging for individuals to connect with the issue personally. Immersive media are an opportunity to introduce innovative feedback mechanisms to highlight the urgency of behavior effects. We introduce a VR carbon calculator that visualizes users' annual carbon footprint as CO2-filled balloons over multiple periods. In a 2x2 design, participants calculated and visualized their carbon footprint numerically or as balloons over one or three years. We found no effect of our visualization but a significant impact of the visualized period on participants' environmental self-efficacy. These findings emphasize the importance of target-oriented design in VR behavior interventions.}, author = {Wienrich, Carolin and Vogt, Stephanie and Döllinger, Nina and Obremski, David}, booktitle = {2024 CHI Conference on Human Factors in Computing Systems}, keywords = {c.wienrich}, title = {Promoting Eco-Friendly Behavior through Virtual Reality - Implementation and Evaluation of Immersive Feedback Conditions of a Virtual CO2 Calculator}, year = 2024 }
• Navigating the Kinematic Maze: Analyzing, Standardizing and Unifying XR Motion Datasets. Rack, Christian; Nair, Vivek; Schach, Lukas; Foschum, Felix; Roth, Marcel; Latoschik, Marc Erich. In 2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW). IEEE, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper addresses the critical importance of standards and documentation in kinematic research, particularly within Extended Reality (XR) environments. We focus on the pivotal role of motion data, emphasizing the challenges posed by the current lack of standardized practices in XR user motion datasets. Our work involves a detailed analysis of 8 existing datasets, identifying gaps in documentation and essential specifications such as coordinate systems, rotation representations, and units of measurement. We highlight how these gaps can lead to misinterpretations and irreproducible results. Based on our findings, we propose a set of guidelines and best practices for creating and documenting motion datasets, aiming to improve their quality, usability, and reproducibility. We also created a web-based tool for visual inspection of motion recordings, further aiding in dataset evaluation and standardization. Furthermore, we introduce the XR Motion Dataset Catalogue, a collection of the analyzed datasets in a unified and aligned format. This initiative significantly streamlines access for researchers, allowing them to download partial or entire datasets with a single line of code and without the need for additional alignment efforts. Our contributions enhance dataset integrity and reliability in kinematic research, paving the way for more consistent and scientifically robust studies in this evolving field.

  @inproceedings{noauthororeditor2024navigating, abstract = {This paper addresses the critical importance of standards and documentation in kinematic research, particularly within Extended Reality (XR) environments. We focus on the pivotal role of motion data, emphasizing the challenges posed by the current lack of standardized practices in XR user motion datasets. Our work involves a detailed analysis of 8 existing datasets, identifying gaps in documentation and essential specifications such as coordinate systems, rotation representations, and units of measurement. We highlight how these gaps can lead to misinterpretations and irreproducible results. Based on our findings, we propose a set of guidelines and best practices for creating and documenting motion datasets, aiming to improve their quality, usability, and reproducibility. We also created a web-based tool for visual inspection of motion recordings, further aiding in dataset evaluation and standardization. Furthermore, we introduce the XR Motion Dataset Catalogue, a collection of the analyzed datasets in a unified and aligned format. This initiative significantly streamlines access for researchers, allowing them to download partial or entire datasets with a single line of code and without the need for additional alignment efforts. Our contributions enhance dataset integrity and reliability in kinematic research, paving the way for more consistent and scientifically robust studies in this evolving field.}, author = {Rack, Christian and Nair, Vivek and Schach, Lukas and Foschum, Felix and Roth, Marcel and Latoschik, Marc Erich}, booktitle = {2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {schell}, organization = {IEEE}, title = {Navigating the Kinematic Maze: Analyzing, Standardizing and Unifying XR Motion Datasets}, year = 2024 }
• From 2D-Screens to VR: Exploring the Effect of Immersion on the Plausibility of Virtual Humans. Mal, David; Wolf, Erik; Döllinger, Nina; Botsch, Mario; Wienrich, Carolin; Latoschik, Marc Erich. In CHI 24 Conference on Human Factors in Computing Systems Extended Abstracts, pp. 1–8. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Virtual humans significantly contribute to users' plausible XR experiences. However, it may be not only the congruent rendering of the virtual human but also the intermediary display technology having a significant impact on virtual humans' plausibility. In a low-immersive desktop-based and a high-immersive VR condition, participants rated realistic and abstract animated virtual humans regarding plausibility, affective appraisal, and social judgments. First, our results confirmed the factor structure of a preliminary virtual human plausibility questionnaire in VR. Further, the appearance and behavior of realistic virtual humans were overall perceived as more plausible compared to abstract virtual humans, an effect that increased with high immersion. Moreover, only for high immersion, realistic virtual humans were rated as more trustworthy and sympathetic than abstract virtual humans. Interestingly, we observed a potential uncanny valley effect for low but not for high immersion. We discuss the impact of a natural perception of anthropomorphic and realistic cues in VR and highlight the potential of immersive technology to elicit distinct effects in virtual humans.

  @inproceedings{mal2024vhpvr, abstract = {Virtual humans significantly contribute to users' plausible XR experiences. However, it may be not only the congruent rendering of the virtual human but also the intermediary display technology having a significant impact on virtual humans' plausibility. In a low-immersive desktop-based and a high-immersive VR condition, participants rated realistic and abstract animated virtual humans regarding plausibility, affective appraisal, and social judgments. First, our results confirmed the factor structure of a preliminary virtual human plausibility questionnaire in VR. Further, the appearance and behavior of realistic virtual humans were overall perceived as more plausible compared to abstract virtual humans, an effect that increased with high immersion. Moreover, only for high immersion, realistic virtual humans were rated as more trustworthy and sympathetic than abstract virtual humans. Interestingly, we observed a potential uncanny valley effect for low but not for high immersion. We discuss the impact of a natural perception of anthropomorphic and realistic cues in VR and highlight the potential of immersive technology to elicit distinct effects in virtual humans.}, author = {Mal, David and Wolf, Erik and Döllinger, Nina and Botsch, Mario and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {CHI 24 Conference on Human Factors in Computing Systems Extended Abstracts}, keywords = {dmal}, pages = {1-8}, title = {From 2D-Screens to VR: Exploring the Effect of Immersion on the Plausibility of Virtual Humans}, year = 2024 }
• Towards Explainable, Coordinated and Proactive Autoscaling for Microservices and Function Chains. Straesser, Martin. 2024.
  • [ BibTeX ]
  @presentation{straesser2024towards, author = {Straesser, Martin}, keywords = {microservices}, title = {Towards Explainable, Coordinated and Proactive Autoscaling for Microservices and Function Chains}, year = 2024 }
• Virtual Body Swapping: A VR-Based Approach to Embodied Third-Person Self-Processing in Mind-Body Therapy. Döllinger, Nina; Mal, David; Keppler, Sebastian; Wolf, Erik; Botsch, Mario; Israel, Johann Habakuk; Latoschik, Marc Erich; Wienrich, Carolin. In 2024 CHI Conference on Human Factors in Computing Systems, pp. 1–18. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Virtual reality (VR) offers various opportunities for innovative therapeutic approaches, especially regarding self-related mind-body interventions. We introduce a VR body swap system enabling multiple users to swap their perspectives and appearances and evaluate its effects on virtual sense of embodiment (SoE) and perception- and cognition-based self-related processes. In a self-compassion-framed scenario, twenty participants embodied their personalized, photorealistic avatar, swapped bodies with an unfamiliar peer, and reported their SoE, interoceptive awareness (perception), and self-compassion (cognition). Participants' experiences differed between bottom-up and top-down processes. Regarding SoE, their agency and self-location shifted to the swap avatar, while their top-down self-identification remained with their personalized avatar. Further, the experience positively affected interoceptive awareness but not self-compassion. Our outcomes offer novel insights into the SoE in a multiple-embodiment scenario and highlight the need to differentiate between the different processes in intervention design. They raise concerns and requirements for future research on avatar-based mind-body interventions.

  @inproceedings{dollinger2024bodyswap, abstract = {Virtual reality (VR) offers various opportunities for innovative therapeutic approaches, especially regarding self-related mind-body interventions. We introduce a VR body swap system enabling multiple users to swap their perspectives and appearances and evaluate its effects on virtual sense of embodiment (SoE) and perception- and cognition-based self-related processes. In a self-compassion-framed scenario, twenty participants embodied their personalized, photorealistic avatar, swapped bodies with an unfamiliar peer, and reported their SoE, interoceptive awareness (perception), and self-compassion (cognition). Participants' experiences differed between bottom-up and top-down processes. Regarding SoE, their agency and self-location shifted to the swap avatar, while their top-down self-identification remained with their personalized avatar. Further, the experience positively affected interoceptive awareness but not self-compassion. Our outcomes offer novel insights into the SoE in a multiple-embodiment scenario and highlight the need to differentiate between the different processes in intervention design. They raise concerns and requirements for future research on avatar-based mind-body interventions.}, author = {Döllinger, Nina and Mal, David and Keppler, Sebastian and Wolf, Erik and Botsch, Mario and Israel, Johann Habakuk and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {2024 CHI Conference on Human Factors in Computing Systems}, keywords = {dmal}, pages = {1-18}, title = {Virtual Body Swapping: A VR-Based Approach to Embodied Third-Person Self-Processing in Mind-Body Therapy}, year = 2024 }
• The Missing Link in Network Intrusion Detection: Taking AI/ML Research Efforts to Users. Dietz, Katharina; Mühlhauser, Michael; Kögel, Jochen; Schwinger, Stephan; Sichermann, Marleen; Seufert, Michael; Herrmann, Dominik; Hoßfeld, Tobias. In IEEE Access. 2024.
  • [ BibTeX ]
  @article{info3-article-2024-4, author = {Dietz, Katharina and Mühlhauser, Michael and Kögel, Jochen and Schwinger, Stephan and Sichermann, Marleen and Seufert, Michael and Herrmann, Dominik and Hoßfeld, Tobias}, journal = {IEEE Access}, keywords = {vipnano}, month = {05}, title = {The Missing Link in Network Intrusion Detection: Taking AI/ML Research Efforts to Users}, year = 2024 }
• Evaluation is key: a survey on evaluation measures for synthetic time series. Stenger, Michael; Leppich, Robert; Foster, Ian; Kounev, Samuel; Bauer, Andr{é}. In Journal of Big Data, 11, p. 66. 2024.
  • [ BibTeX ]
  @article{Stenger2024, author = {Stenger, Michael and Leppich, Robert and Foster, Ian and Kounev, Samuel and Bauer, Andr{\'e}}, journal = {Journal of Big Data}, keywords = {t_journalmagazine}, month = {05}, pages = 66, title = {Evaluation is key: a survey on evaluation measures for synthetic time series}, volume = 11, year = 2024 }
• Serverless Computing: An Old Wine in New Bottles or More?. Kounev, Samuel. 2024, May.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Market analysts are agreed that serverless computing has strong market potential, with projected compound annual growth rates varying between 21% and 28% through 2028 and a projected market value of $36.8 billion by that time. Although serverless computing has gained significant attention in industry and academia over the past years, there is still no consensus about its unique distinguishing characteristics and precise understanding of how these characteristics differ from classical cloud computing. For example, there is no wide agreement on whether serverless is solely a set of requirements from the cloud user’s perspective or it should also mandate specific implementation choices on the provider side, such as implementing an autoscaling mechanism to achieve elasticity. Similarly, there is no agreement on whether serverless is just the operational part, or it should also include specific programming models, interfaces, or calling protocols. In this talk, we seek to dispel this confusion by evaluating the essential conceptual characteristics of serverless computing as a paradigm, while putting the various terms around it into perspective. We examine how the term serverless computing, and related terms, are used today. We explain the historical evolution leading to serverless computing, starting with mainframe virtualization in the 1960 through to Grid and cloud computing all the way up to today. We review existing cloud computing service models, including IaaS, PaaS, SaaS, CaaS, FaaS, and BaaS, discussing how they relate to the serverless paradigm. In the second part of talk, we focus on performance challenges in serverless computing both from the user’s perspective (finding the optimal size of serverless functions) as well as from the provider’s perspective (ensuring predictable and fast container start times coupled with fine-granular and accurate elastic scaling mechanisms).

  @misc{kounev2024ccgrid, abstract = {Market analysts are agreed that serverless computing has strong market potential, with projected compound annual growth rates varying between 21% and 28% through 2028 and a projected market value of $36.8 billion by that time. Although serverless computing has gained significant attention in industry and academia over the past years, there is still no consensus about its unique distinguishing characteristics and precise understanding of how these characteristics differ from classical cloud computing. For example, there is no wide agreement on whether serverless is solely a set of requirements from the cloud user’s perspective or it should also mandate specific implementation choices on the provider side, such as implementing an autoscaling mechanism to achieve elasticity. Similarly, there is no agreement on whether serverless is just the operational part, or it should also include specific programming models, interfaces, or calling protocols. In this talk, we seek to dispel this confusion by evaluating the essential conceptual characteristics of serverless computing as a paradigm, while putting the various terms around it into perspective. We examine how the term serverless computing, and related terms, are used today. We explain the historical evolution leading to serverless computing, starting with mainframe virtualization in the 1960 through to Grid and cloud computing all the way up to today. We review existing cloud computing service models, including IaaS, PaaS, SaaS, CaaS, FaaS, and BaaS, discussing how they relate to the serverless paradigm. In the second part of talk, we focus on performance challenges in serverless computing both from the user’s perspective (finding the optimal size of serverless functions) as well as from the provider’s perspective (ensuring predictable and fast container start times coupled with fine-granular and accurate elastic scaling mechanisms).}, author = {Kounev, Samuel}, keywords = {t_presscoverage}, month = {05}, note = {https://2024.ccgrid-conference.org/speakers/skounev/}, title = {Serverless Computing: An Old Wine in New Bottles or More?}, year = 2024 }
• Assessing Depth Perception in VR and Video See-Through AR: A Comparison on Distance Judgment, Performance, and Preference. Westermeier, Franziska; Brübach, Larissa; Wienrich, Carolin; Latoschik, Marc Erich. In IEEE Transactions on Visualization and Computer Graphics, 30(5), pp. 2140–2150. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Spatial User Interfaces along the Reality-Virtuality continuum heavily depend on accurate depth perception. However, current display technologies still exhibit shortcomings in the simulation of accurate depth cues, and these shortcomings also vary between Virtual or Augmented Reality (VR, AR: eXtended Reality (XR) for short). This article compares depth perception between VR and Video See-Through (VST) AR. We developed a digital twin of an existing office room where users had to perform five depth-dependent tasks in VR and VST AR. Thirty-two participants took part in a user study using a 1×4 within-subjects design. Our results reveal higher misjudgment rates in VST AR due to conflicting depth cues between virtual and physical content. Increased head movements observed in participants were interpreted as a compensatory response to these conflicting cues. Furthermore, a longer task completion time in the VST AR condition indicates a lower task performance in VST AR. Interestingly, while participants rated the VR condition as easier and contrary to the increased misjudgments and lower performance with the VST AR display, a majority still expressed a preference for the VST AR experience. We discuss and explain these findings with the high visual dominance and referential power of the physical content in the VST AR condition, leading to a higher spatial presence and plausibility.

  @article{westermeier2024assessing, abstract = {Spatial User Interfaces along the Reality-Virtuality continuum heavily depend on accurate depth perception. However, current display technologies still exhibit shortcomings in the simulation of accurate depth cues, and these shortcomings also vary between Virtual or Augmented Reality (VR, AR: eXtended Reality (XR) for short). This article compares depth perception between VR and Video See-Through (VST) AR. We developed a digital twin of an existing office room where users had to perform five depth-dependent tasks in VR and VST AR. Thirty-two participants took part in a user study using a 1×4 within-subjects design. Our results reveal higher misjudgment rates in VST AR due to conflicting depth cues between virtual and physical content. Increased head movements observed in participants were interpreted as a compensatory response to these conflicting cues. Furthermore, a longer task completion time in the VST AR condition indicates a lower task performance in VST AR. Interestingly, while participants rated the VR condition as easier and contrary to the increased misjudgments and lower performance with the VST AR display, a majority still expressed a preference for the VST AR experience. We discuss and explain these findings with the high visual dominance and referential power of the physical content in the VST AR condition, leading to a higher spatial presence and plausibility.}, author = {Westermeier, Franziska and Brübach, Larissa and Wienrich, Carolin and Latoschik, Marc Erich}, journal = {IEEE Transactions on Visualization and Computer Graphics}, keywords = {xrhub}, month = {05}, number = 5, pages = {2140 - 2150}, title = {Assessing Depth Perception in VR and Video See-Through AR: A Comparison on Distance Judgment, Performance, and Preference}, volume = 30, year = 2024 }
• The Effects of Expertise, Humanness, and Congruence on Perceived Trust, Warmth, Competence and Intention to Use Embodied AI. Krop, Philipp; Koch, Martin J.; Carolus, Astrid; Latoschik, Marc Erich; Wienrich, Carolin. In Extended Abstracts of the CHI Conference on Human Factors in Computing Systems (CHI EA ’24), p. 9. ACM, New York, NY, USA, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Even though people imagine different embodiments when asked which AI they would like to work with, most studies investigate trust in AI systems without specific physical appearances. This study aims to close this gap by combining influencing factors of trust to analyze their impact on the perceived trustworthiness, warmth, and competence of an embodied AI. We recruited 68 par- ticipants who observed three co-working scenes with an embodied AI, presented as expert/novice (expertise), human/AI (humanness), or congruent/slightly incongruent to the environment (congruence). Our results show that the expertise condition had the largest im- pact on trust, acceptance, and perceived warmth and competence. When controlled for perceived competence, the humanness of the AI and the congruence of its embodiment to the environment also influence acceptance. The results show that besides expertise and the perceived competence of the AI, other design variables are rele- vant for successful human-AI interaction, especially when the AI is embodied.

  @inproceedings{krop2024effects, abstract = {Even though people imagine different embodiments when asked which AI they would like to work with, most studies investigate trust in AI systems without specific physical appearances. This study aims to close this gap by combining influencing factors of trust to analyze their impact on the perceived trustworthiness, warmth, and competence of an embodied AI. We recruited 68 par- ticipants who observed three co-working scenes with an embodied AI, presented as expert/novice (expertise), human/AI (humanness), or congruent/slightly incongruent to the environment (congruence). Our results show that the expertise condition had the largest im- pact on trust, acceptance, and perceived warmth and competence. When controlled for perceived competence, the humanness of the AI and the congruence of its embodiment to the environment also influence acceptance. The results show that besides expertise and the perceived competence of the AI, other design variables are rele- vant for successful human-AI interaction, especially when the AI is embodied.}, address = {New York, NY, USA}, author = {Krop, Philipp and Koch, Martin J. and Carolus, Astrid and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {Extended Abstracts of the CHI Conference on Human Factors in Computing Systems (CHI EA ’24)}, keywords = {aiatwork}, month = {05}, organization = {ACM}, pages = 9, publisher = {ACM}, title = {The Effects of Expertise, Humanness, and Congruence on Perceived Trust, Warmth, Competence and Intention to Use Embodied AI}, year = 2024 }
• Evaluation is key: a survey on evaluation measures for synthetic time series. Stenger, Michael; Leppich, Robert; Foster, Ian; Kounev, Samuel; Bauer, Andr{é}. In Journal of Big Data, 11, p. 66. 2024.
  • [ BibTeX ]
  @article{Stenger2024, author = {Stenger, Michael and Leppich, Robert and Foster, Ian and Kounev, Samuel and Bauer, Andr{\'e}}, journal = {Journal of Big Data}, keywords = {t_journalmagazine}, month = {05}, pages = 66, title = {Evaluation is key: a survey on evaluation measures for synthetic time series}, volume = 11, year = 2024 }
• HALIDS: a hardware-assisted machine learning IDS for in-network monitoring. Brandino, Belén; Grampin, Eduardo; Dietz, Katharina; Wehner, Nikolas; Seufert, Michael; Hoßfeld, Tobias; Casas, Pedro. In 2024 8th Network Traffic Measurement and Analysis Conference (TMA), Dresden, Germany. 2024.
  • [ BibTeX ]
  @inproceedings{info3-poster-2024-1, author = {Brandino, Belén and Grampin, Eduardo and Dietz, Katharina and Wehner, Nikolas and Seufert, Michael and Hoßfeld, Tobias and Casas, Pedro}, booktitle = {2024 8th Network Traffic Measurement and Analysis Conference (TMA), Dresden, Germany}, keywords = {myown}, month = {05}, title = {HALIDS: a hardware-assisted machine learning IDS for in-network monitoring}, year = 2024 }
• Thinking in Categories: A Survey on Assessing the Quality for Time Series Synthesis. Stenger, Michael; Bauer, Andr{é}; Prantl, Thomas; Leppich, Robert; Hudson, Nathaniel; Chard, Kyle; Foster, Ian; Kounev, Samuel. In J. Data and Information Quality, 16(2). Association for Computing Machinery, New York, NY, USA, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Time series data are widely used and provide a wealth of information for countless applications. However, some applications are faced with a limited amount of data, or the data cannot be used due to confidentiality concerns. To overcome these obstacles, time series can be generated synthetically. For example, electrocardiograms can be synthesized to make them available for building models to predict conditions such as cardiac arrhythmia without leaking patient information. Although many different approaches to time series synthesis have been proposed, evaluating the quality of synthetic time series data poses unique challenges and remains an open problem, as there is a lack of a clear definition of what constitutes a “good” synthesis. To this end, we present a comprehensive literature survey to identify different aspects of synthesis quality and their relationships. Based on this, we propose a definition of synthesis quality and a systematic evaluation procedure for assessing it. With this work, we aim to provide a common language and criteria for evaluating synthetic time series data. Our goal is to promote more rigorous and reproducible research in time series synthesis by enabling researchers and practitioners to generate high-quality synthetic time series data.

  @article{10.1145/3666006, abstract = {Time series data are widely used and provide a wealth of information for countless applications. However, some applications are faced with a limited amount of data, or the data cannot be used due to confidentiality concerns. To overcome these obstacles, time series can be generated synthetically. For example, electrocardiograms can be synthesized to make them available for building models to predict conditions such as cardiac arrhythmia without leaking patient information. Although many different approaches to time series synthesis have been proposed, evaluating the quality of synthetic time series data poses unique challenges and remains an open problem, as there is a lack of a clear definition of what constitutes a “good” synthesis. To this end, we present a comprehensive literature survey to identify different aspects of synthesis quality and their relationships. Based on this, we propose a definition of synthesis quality and a systematic evaluation procedure for assessing it. With this work, we aim to provide a common language and criteria for evaluating synthetic time series data. Our goal is to promote more rigorous and reproducible research in time series synthesis by enabling researchers and practitioners to generate high-quality synthetic time series data.}, address = {New York, NY, USA}, author = {Stenger, Michael and Bauer, Andr\'{e} and Prantl, Thomas and Leppich, Robert and Hudson, Nathaniel and Chard, Kyle and Foster, Ian and Kounev, Samuel}, journal = {J. Data and Information Quality}, keywords = {t_journalmagazine}, month = {06}, number = 2, publisher = {Association for Computing Machinery}, title = {Thinking in Categories: A Survey on Assessing the Quality for Time Series Synthesis}, volume = 16, year = 2024 }
• Machine Learning with Computer Networks: Techniques, Datasets and Models. Afifi, Haitham; Pochaba, Sabrina; Boltres, Andreas; Laniewski, Dominic; Haberer, Janek; Paeleke, Leonard; Poorzare, Reza; Stolpmann, Daniel; Wehner, Nikolas; Redder, Adrian; Samikwa, Eric; Seufert, Michael. In IEEE Access. 2024.
  • [ BibTeX ]
  @article{info3-article-2024-2, author = {Afifi, Haitham and Pochaba, Sabrina and Boltres, Andreas and Laniewski, Dominic and Haberer, Janek and Paeleke, Leonard and Poorzare, Reza and Stolpmann, Daniel and Wehner, Nikolas and Redder, Adrian and Samikwa, Eric and Seufert, Michael}, journal = {IEEE Access}, keywords = {myown}, month = {04}, title = {Machine Learning with Computer Networks: Techniques, Datasets and Models}, year = 2024 }
• QoEXplainer: Mediating Explainable Quality of Experience Models with Large Language Models. Wehner, Nikolas; Feldhus, Nils; Seufert, Michael; Möller, Sebastian; Hoßfeld, Tobias. In 16th International Conference on Quality of Multimedia Experience (QoMEX). Karlshamn, Sweden, 2024.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2024-4, address = {Karlshamn, Sweden}, author = {Wehner, Nikolas and Feldhus, Nils and Seufert, Michael and Möller, Sebastian and Hoßfeld, Tobias}, booktitle = {16th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {myown}, month = {06}, title = {QoEXplainer: Mediating Explainable Quality of Experience Models with Large Language Models}, year = 2024 }
• Thinking in Categories: A Survey on Assessing the Quality for Time Series Synthesis. Stenger, Michael; Bauer, Andr{é}; Prantl, Thomas; Leppich, Robert; Hudson, Nathaniel; Chard, Kyle; Foster, Ian; Kounev, Samuel. In J. Data and Information Quality, 16(2). Association for Computing Machinery, New York, NY, USA, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Time series data are widely used and provide a wealth of information for countless applications. However, some applications are faced with a limited amount of data, or the data cannot be used due to confidentiality concerns. To overcome these obstacles, time series can be generated synthetically. For example, electrocardiograms can be synthesized to make them available for building models to predict conditions such as cardiac arrhythmia without leaking patient information. Although many different approaches to time series synthesis have been proposed, evaluating the quality of synthetic time series data poses unique challenges and remains an open problem, as there is a lack of a clear definition of what constitutes a “good” synthesis. To this end, we present a comprehensive literature survey to identify different aspects of synthesis quality and their relationships. Based on this, we propose a definition of synthesis quality and a systematic evaluation procedure for assessing it. With this work, we aim to provide a common language and criteria for evaluating synthetic time series data. Our goal is to promote more rigorous and reproducible research in time series synthesis by enabling researchers and practitioners to generate high-quality synthetic time series data.

  @article{10.1145/3666006, abstract = {Time series data are widely used and provide a wealth of information for countless applications. However, some applications are faced with a limited amount of data, or the data cannot be used due to confidentiality concerns. To overcome these obstacles, time series can be generated synthetically. For example, electrocardiograms can be synthesized to make them available for building models to predict conditions such as cardiac arrhythmia without leaking patient information. Although many different approaches to time series synthesis have been proposed, evaluating the quality of synthetic time series data poses unique challenges and remains an open problem, as there is a lack of a clear definition of what constitutes a “good” synthesis. To this end, we present a comprehensive literature survey to identify different aspects of synthesis quality and their relationships. Based on this, we propose a definition of synthesis quality and a systematic evaluation procedure for assessing it. With this work, we aim to provide a common language and criteria for evaluating synthetic time series data. Our goal is to promote more rigorous and reproducible research in time series synthesis by enabling researchers and practitioners to generate high-quality synthetic time series data.}, address = {New York, NY, USA}, author = {Stenger, Michael and Bauer, Andr\'{e} and Prantl, Thomas and Leppich, Robert and Hudson, Nathaniel and Chard, Kyle and Foster, Ian and Kounev, Samuel}, journal = {J. Data and Information Quality}, keywords = {t_journalmagazine}, month = {06}, number = 2, publisher = {Association for Computing Machinery}, title = {Thinking in Categories: A Survey on Assessing the Quality for Time Series Synthesis}, volume = 16, year = 2024 }
• Understanding Serverless Computing: The Evolution of Cloud Service Models. Kounev, Samuel. 2024, June.
  • [ BibTeX ]
  • [ URL ]
  @misc{kounev2024understanding, author = {Kounev, Samuel}, keywords = {t_presscoverage}, month = {06}, note = {https://www.serverlesscomputing.org/woscx3/talks.html}, title = {Understanding Serverless Computing: The Evolution of Cloud Service Models}, year = 2024 }
• Thinking in Categories: A Survey on Assessing the Quality for Time Series Synthesis. Stenger, Michael; Bauer, Andr{é}; Prantl, Thomas; Leppich, Robert; Hudson, Nathaniel; Chard, Kyle; Foster, Ian; Kounev, Samuel. In J. Data and Information Quality, 16(2). Association for Computing Machinery, New York, NY, USA, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Time series data are widely used and provide a wealth of information for countless applications. However, some applications are faced with a limited amount of data, or the data cannot be used due to confidentiality concerns. To overcome these obstacles, time series can be generated synthetically. For example, electrocardiograms can be synthesized to make them available for building models to predict conditions such as cardiac arrhythmia without leaking patient information. Although many different approaches to time series synthesis have been proposed, evaluating the quality of synthetic time series data poses unique challenges and remains an open problem, as there is a lack of a clear definition of what constitutes a “good” synthesis. To this end, we present a comprehensive literature survey to identify different aspects of synthesis quality and their relationships. Based on this, we propose a definition of synthesis quality and a systematic evaluation procedure for assessing it. With this work, we aim to provide a common language and criteria for evaluating synthetic time series data. Our goal is to promote more rigorous and reproducible research in time series synthesis by enabling researchers and practitioners to generate high-quality synthetic time series data.

  @article{10.1145/3666006, abstract = {Time series data are widely used and provide a wealth of information for countless applications. However, some applications are faced with a limited amount of data, or the data cannot be used due to confidentiality concerns. To overcome these obstacles, time series can be generated synthetically. For example, electrocardiograms can be synthesized to make them available for building models to predict conditions such as cardiac arrhythmia without leaking patient information. Although many different approaches to time series synthesis have been proposed, evaluating the quality of synthetic time series data poses unique challenges and remains an open problem, as there is a lack of a clear definition of what constitutes a “good” synthesis. To this end, we present a comprehensive literature survey to identify different aspects of synthesis quality and their relationships. Based on this, we propose a definition of synthesis quality and a systematic evaluation procedure for assessing it. With this work, we aim to provide a common language and criteria for evaluating synthetic time series data. Our goal is to promote more rigorous and reproducible research in time series synthesis by enabling researchers and practitioners to generate high-quality synthetic time series data.}, address = {New York, NY, USA}, author = {Stenger, Michael and Bauer, Andr\'{e} and Prantl, Thomas and Leppich, Robert and Hudson, Nathaniel and Chard, Kyle and Foster, Ian and Kounev, Samuel}, journal = {J. Data and Information Quality}, keywords = {t_journalmagazine}, month = {06}, number = 2, publisher = {Association for Computing Machinery}, title = {Thinking in Categories: A Survey on Assessing the Quality for Time Series Synthesis}, volume = 16, year = 2024 }
• (Not) The Sum of Its Parts: Relating Individual Video and Browsing Stimuli to Web Session QoE. Schleicher, Johannes; Wehner, Nikolas; Hoßfeld, Tobias; Seufert, Michael. In 16th International Conference on Quality of Multimedia Experience (QoMEX). Karlshamn, Sweden, 2024.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2024-3, address = {Karlshamn, Sweden}, author = {Schleicher, Johannes and Wehner, Nikolas and Hoßfeld, Tobias and Seufert, Michael}, booktitle = {16th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {myown}, month = {06}, title = {(Not) The Sum of Its Parts: Relating Individual Video and Browsing Stimuli to Web Session QoE}, year = 2024 }
• Security Analysis of a Decentralized, Revocable and Verifiable Attribute-Based Encryption Scheme. Prantl, Thomas; Lauer, Marco; Horn, Lukas; Engel, Simon; Dingel, David; Kounev, Samuel; Bauer, André; Krupitzer, Christian. In Proceedings of the 19th International Conference on Availability, Reliability and Security, of ARES 2024. ACM, 2024.
  • [ BibTeX ]
  @inproceedings{ARES_2024_ABE, author = {Prantl, Thomas and Lauer, Marco and Horn, Lukas and Engel, Simon and Dingel, David and Kounev, Samuel and Bauer, André and Krupitzer, Christian}, booktitle = {Proceedings of the 19th International Conference on Availability, Reliability and Security}, keywords = {descartes}, publisher = {ACM}, series = {ARES 2024}, title = {Security Analysis of a Decentralized, Revocable and Verifiable Attribute-Based Encryption Scheme}, year = 2024 }
• Benchmarking of Secure Group Communication schemes with Focus on IoT. Prantl, Thomas; Bauer, André; Engel, Simon; Horn, Lukas; Krupitzer, Christian; Iffl"{a}nder, Lukas; Kounev, Samuel. In Discover Data, 2(1). Springer Science and Business Media LLC, 2024.
  • [ BibTeX ]
  • [ URL ]
  @article{PrBaEnHoKrIfKo_Discover_Data_2024, author = {Prantl, Thomas and Bauer, André and Engel, Simon and Horn, Lukas and Krupitzer, Christian and Iffl"{a}nder, Lukas and Kounev, Samuel}, journal = {Discover Data}, keywords = {t_journalmagazine}, month = {05}, number = 1, publisher = {Springer Science and Business Media LLC}, title = {Benchmarking of Secure Group Communication schemes with Focus on IoT}, volume = 2, year = 2024 }
• Benchmarking of Secure Group Communication schemes with Focus on IoT. Prantl, Thomas; Bauer, André; Engel, Simon; Horn, Lukas; Krupitzer, Christian; Iffl"{a}nder, Lukas; Kounev, Samuel. In Discover Data, 2(1). Springer Science and Business Media LLC, 2024.
  • [ BibTeX ]
  • [ URL ]
  @article{PrBaEnHoKrIfKo_Discover_Data_2024, author = {Prantl, Thomas and Bauer, André and Engel, Simon and Horn, Lukas and Krupitzer, Christian and Iffl"{a}nder, Lukas and Kounev, Samuel}, journal = {Discover Data}, keywords = {t_journalmagazine}, month = {05}, number = 1, publisher = {Springer Science and Business Media LLC}, title = {Benchmarking of Secure Group Communication schemes with Focus on IoT}, volume = 2, year = 2024 }
• Marina: Realizing ML-Driven Real-Time Network Traffic Monitoring at Terabit Scale. Seufert, Michael; Dietz, Katharina; Wehner, Nikolas; Geißler, Stefan; Schüler, Joshua; Wolz, Manuel; Hotho, Andreas; Casas, Pedro; Hoßfeld, Tobias; Feldmann, Anja. In Transactions on Network and Service Management (TNSM). 2024.
  • [ BibTeX ]
  @article{info3-article-2024-1, author = {Seufert, Michael and Dietz, Katharina and Wehner, Nikolas and Geißler, Stefan and Schüler, Joshua and Wolz, Manuel and Hotho, Andreas and Casas, Pedro and Hoßfeld, Tobias and Feldmann, Anja}, journal = {Transactions on Network and Service Management (TNSM)}, keywords = {ucn}, month = {03}, title = {Marina: Realizing ML-Driven Real-Time Network Traffic Monitoring at Terabit Scale}, year = 2024 }
• Investigation of Serverless Consumption and Performance in Multi-Access Edge Computing. TrungKien, Nguyen; Loh, Frank; TrungKiem, Nguyen; MinhChau, Nguyen; Huu Thanh, Nguyen; Hoßfeld, Tobias. In The 38th International Conference on Information Networking (ICOIN). 2024.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2024-1, author = {TrungKien, Nguyen and Loh, Frank and TrungKiem, Nguyen and MinhChau, Nguyen and Huu Thanh, Nguyen and Hoßfeld, Tobias}, booktitle = {The 38th International Conference on Information Networking (ICOIN)}, keywords = {myown}, month = {01}, title = {Investigation of Serverless Consumption and Performance in Multi-Access Edge Computing}, year = 2024 }
• Proteus Effect or Bodily Affordance? The Influence of Virtual High-Heels on Gait Behavior. Oberdörfer, Sebastian; Birnstiel, Sandra; Latoschik, Marc Erich. In Virtual Reality, 28(81). 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Shoes are an important part of the fashion industry, stereotypically affect our self-awareness as well as external perception, and can even biomechanically modify our gait pattern. Immersive Virtual Reality (VR) enables users not only to explore virtual environments, but also to control an avatar as a proxy for themselves. These avatars can wear any kind of shoe which might similarly affect self-awareness due to the Proteus Effect and even cause a bodily affordance to change the gait pattern. Bodily affordance describes a behavioral change in accordance with the expected constraints of the avatar a user is embodied with. In this article, we present the results of three user studies investigating potential changes in the gait pattern evoked by wearing virtual high-heels. Two user studies targeted female participants and one user study focused male participants. The participants wore either virtual sneakers or virtual high-heels while constantly wearing sneakers or socks in reality. To measure the gait pattern, the participants walked on a treadmill that also was added to the virtual environment. We measured significant differences in stride length and in the flexion of the hips and knees at heel strike and partly at toe off. Also, participants reported to walk more comfortably in the virtual sneakers in contrast to the virtual high-heels. This indicates a strong acceptance of the virtual shoes as their real shoes and hence suggests the existence of a bodily affordance. While sparking a discussion about the boundaries as well as aspects of the Proteus Effect and providing another insight into the effects of embodiment in VR, our results might also be important for researchers and developers.

  @article{oberdorfer2024proteus, abstract = {Shoes are an important part of the fashion industry, stereotypically affect our self-awareness as well as external perception, and can even biomechanically modify our gait pattern. Immersive Virtual Reality (VR) enables users not only to explore virtual environments, but also to control an avatar as a proxy for themselves. These avatars can wear any kind of shoe which might similarly affect self-awareness due to the Proteus Effect and even cause a bodily affordance to change the gait pattern. Bodily affordance describes a behavioral change in accordance with the expected constraints of the avatar a user is embodied with. In this article, we present the results of three user studies investigating potential changes in the gait pattern evoked by wearing virtual high-heels. Two user studies targeted female participants and one user study focused male participants. The participants wore either virtual sneakers or virtual high-heels while constantly wearing sneakers or socks in reality. To measure the gait pattern, the participants walked on a treadmill that also was added to the virtual environment. We measured significant differences in stride length and in the flexion of the hips and knees at heel strike and partly at toe off. Also, participants reported to walk more comfortably in the virtual sneakers in contrast to the virtual high-heels. This indicates a strong acceptance of the virtual shoes as their real shoes and hence suggests the existence of a bodily affordance. While sparking a discussion about the boundaries as well as aspects of the Proteus Effect and providing another insight into the effects of embodiment in VR, our results might also be important for researchers and developers.}, author = {Oberdörfer, Sebastian and Birnstiel, Sandra and Latoschik, Marc Erich}, journal = {Virtual Reality}, keywords = {dark-sides-vr}, number = 81, title = {Proteus Effect or Bodily Affordance? The Influence of Virtual High-Heels on Gait Behavior}, volume = 28, year = 2024 }
• Patient-Centered Chronic Wound Care Mobile Apps: Systematic Identification, Analysis, and Assessment. Dege, Tassilo; Glatzel, Bernadette; Borst, Vanessa; Grän, Franziska; Goller, Simon; Glatzel, Caroline; Goebeler, Matthias; Schmieder, Astrid. In JMIR mHealth and uHealth, 12. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Background: The prevalence of chronic wounds is predicted to increase within the aging populations in industrialized countries. Patients experience significant distress due to pain, wound secretions, and the resulting immobilization. As the number of wounds continues to rise, their adequate care becomes increasingly costly in terms of health care resources worldwide. eHealth support systems are being increasingly integrated into patient care. However, to date, no systematic analysis of such apps for chronic wounds has been published. Objective: The aims of this study were to systematically identify and subjectively assess publicly available German- or English-language mobile apps for patients with chronic wounds, with quality assessments performed by both patients and physicians. Methods: Two reviewers independently conducted a systematic search and assessment of German- or English-language mobile apps for patients with chronic wounds that were available in the Google Play Store and Apple App Store from April 2022 to May 2022. In total, 3 apps met the inclusion and exclusion criteria and were reviewed independently by 10 physicians using the German Mobile App Rating Scale (MARS) and the System Usability Scale (SUS). The app with the highest mean MARS score was subsequently reviewed by 11 patients with chronic wounds using the German user version of the MARS (uMARS) and the SUS. Additionally, Affinity for Technology Interaction (ATI) scale scores were collected from both patients and physicians. Results: This study assessed mobile apps for patients with chronic wounds that were selected from a pool of 118 identified apps. Of the 73 apps available in both app stores, 10 were patient oriented. After excluding apps with advertisements or costs, 3 apps were evaluated by 10 physicians. Mean MARS scores ranged from 2.64 (SD 0.65) to 3.88 (SD 0.65) out of 5, and mean SUS scores ranged from 50.75 (SD 27) to 80.5 (SD 17.7) out of 100. WUND APP received the highest mean MARS score (mean 3.88, SD 0.65 out of 5) among physicians. Hence, it was subsequently assessed by 11 patients and achieved a similar rating (uMARS score: mean 3.89, SD 0.4 out of 5). Technical affinity, as measured with the ATI scale, was slightly lower in patients (score: mean 3.62, SD 1.35 out of 6) compared to physicians (score: mean 3.88, SD 1.03 out 6). Conclusions: The quality ratings from physicians and patients were comparable and indicated mediocre app quality. Technical affinity, as assessed by using the ATI scale, was slightly lower for patients. Adequate apps for patients with chronic wounds remain limited, emphasizing the need for improved app development to meet patient needs. The ATI scale proved valuable for assessing technical affinity among different user groups.

  @article{dege2024patientcentered, abstract = {Background: The prevalence of chronic wounds is predicted to increase within the aging populations in industrialized countries. Patients experience significant distress due to pain, wound secretions, and the resulting immobilization. As the number of wounds continues to rise, their adequate care becomes increasingly costly in terms of health care resources worldwide. eHealth support systems are being increasingly integrated into patient care. However, to date, no systematic analysis of such apps for chronic wounds has been published. Objective: The aims of this study were to systematically identify and subjectively assess publicly available German- or English-language mobile apps for patients with chronic wounds, with quality assessments performed by both patients and physicians. Methods: Two reviewers independently conducted a systematic search and assessment of German- or English-language mobile apps for patients with chronic wounds that were available in the Google Play Store and Apple App Store from April 2022 to May 2022. In total, 3 apps met the inclusion and exclusion criteria and were reviewed independently by 10 physicians using the German Mobile App Rating Scale (MARS) and the System Usability Scale (SUS). The app with the highest mean MARS score was subsequently reviewed by 11 patients with chronic wounds using the German user version of the MARS (uMARS) and the SUS. Additionally, Affinity for Technology Interaction (ATI) scale scores were collected from both patients and physicians. Results: This study assessed mobile apps for patients with chronic wounds that were selected from a pool of 118 identified apps. Of the 73 apps available in both app stores, 10 were patient oriented. After excluding apps with advertisements or costs, 3 apps were evaluated by 10 physicians. Mean MARS scores ranged from 2.64 (SD 0.65) to 3.88 (SD 0.65) out of 5, and mean SUS scores ranged from 50.75 (SD 27) to 80.5 (SD 17.7) out of 100. WUND APP received the highest mean MARS score (mean 3.88, SD 0.65 out of 5) among physicians. Hence, it was subsequently assessed by 11 patients and achieved a similar rating (uMARS score: mean 3.89, SD 0.4 out of 5). Technical affinity, as measured with the ATI scale, was slightly lower in patients (score: mean 3.62, SD 1.35 out of 6) compared to physicians (score: mean 3.88, SD 1.03 out 6). Conclusions: The quality ratings from physicians and patients were comparable and indicated mediocre app quality. Technical affinity, as assessed by using the ATI scale, was slightly lower for patients. Adequate apps for patients with chronic wounds remain limited, emphasizing the need for improved app development to meet patient needs. The ATI scale proved valuable for assessing technical affinity among different user groups.}, author = {Dege, Tassilo and Glatzel, Bernadette and Borst, Vanessa and Grän, Franziska and Goller, Simon and Glatzel, Caroline and Goebeler, Matthias and Schmieder, Astrid}, journal = {JMIR mHealth and uHealth}, keywords = {t_journalmagazine}, month = {03}, title = {Patient-Centered Chronic Wound Care Mobile Apps: Systematic Identification, Analysis, and Assessment}, volume = 12, year = 2024 }
• Towards an Altered Body Image Through the Exposure to a Modulated Self in Virtual Reality. Wolf, Erik; Wienrich, Carolin; Latoschik, Marc Erich. In 2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW), pp. 857–858. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Self-exposure using modulated embodied avatars in virtual reality (VR) may support a positive body image. However, further investigation is needed to address methodological challenges and to understand the concrete effects, including their quantification. We present an iteratively refined paradigm for studying the tangible effects of exposure to a modulated self in VR. Participants perform body-centered movements in front of a virtual mirror, encountering their photorealistically personalized embodied avatar with increased, decreased, or unchanged body size. Additionally, we propose different body size estimation tasks conducted in reality and VR before and after exposure to assess participants' putative-elicited perceptual adaptations.

  @inproceedings{wolf2024towards, abstract = {Self-exposure using modulated embodied avatars in virtual reality (VR) may support a positive body image. However, further investigation is needed to address methodological challenges and to understand the concrete effects, including their quantification. We present an iteratively refined paradigm for studying the tangible effects of exposure to a modulated self in VR. Participants perform body-centered movements in front of a virtual mirror, encountering their photorealistically personalized embodied avatar with increased, decreased, or unchanged body size. Additionally, we propose different body size estimation tasks conducted in reality and VR before and after exposure to assess participants' putative-elicited perceptual adaptations.}, author = {Wolf, Erik and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {vitras}, pages = {857-858}, title = {Towards an Altered Body Image Through the Exposure to a Modulated Self in Virtual Reality}, year = 2024 }
• Unveiling Temporal Performance Deviation: Leveraging Clustering in Microservices Performance Analysis. Bauer, André; Dittus, Timo; Straesser, Martin; Kamatar, Alok; Baughman, Matt; Beierlieb, Lukas; Hadry, Marius; Grillmeyer, Daniel; Lubas, Yannik; Kounev, Samuel; Foster, Ian; Chard, Kyle. In Companion of the 15th ACM/SPEC International Conference on Performance Engineering, of ICPE ’24 Companion, pp. 72–76. Association for Computing Machinery, New York, NY, USA, 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  As the market for cloud computing continues to grow, an increasing number of users are deploying applications as microservices. The shift introduces unique challenges in identifying and addressing performance issues, particularly within large and complex infrastructures. To address this challenge, we propose a methodology that unveils temporal performance deviations in microservices by clustering containers based on their performance characteristics at different time intervals. Showcasing our methodology on the Alibaba dataset, we found both stable and dynamic performance patterns, providing a valuable tool for enhancing overall performance and reliability in modern application landscapes.

  @inproceedings{10.1145/3629527.3651843, abstract = {As the market for cloud computing continues to grow, an increasing number of users are deploying applications as microservices. The shift introduces unique challenges in identifying and addressing performance issues, particularly within large and complex infrastructures. To address this challenge, we propose a methodology that unveils temporal performance deviations in microservices by clustering containers based on their performance characteristics at different time intervals. Showcasing our methodology on the Alibaba dataset, we found both stable and dynamic performance patterns, providing a valuable tool for enhancing overall performance and reliability in modern application landscapes.}, address = {New York, NY, USA}, author = {Bauer, André and Dittus, Timo and Straesser, Martin and Kamatar, Alok and Baughman, Matt and Beierlieb, Lukas and Hadry, Marius and Grillmeyer, Daniel and Lubas, Yannik and Kounev, Samuel and Foster, Ian and Chard, Kyle}, booktitle = {Companion of the 15th ACM/SPEC International Conference on Performance Engineering}, keywords = {descartes}, pages = {72–76}, publisher = {Association for Computing Machinery}, series = {ICPE '24 Companion}, title = {Unveiling Temporal Performance Deviation: Leveraging Clustering in Microservices Performance Analysis}, year = 2024 }
• Parameterized Approximation for Robust Clustering in Discrete Geometric Spaces. Abbasi, Fateme; Banerjee, Sandip; Byrka, Jaroslaw; Chalermsook, Parinya; Gadekar, Ameet; Khodamoradi, Kamyar; Marx, Dániel; Sharma, Roohani; Spoerhase, Joachim. In Proc. 51st International Colloquium on Automata, Languages and Programming (ICALP’24). 2024.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{abbasi-etal24:robust-clustering-geometric-spaces, author = {Abbasi, Fateme and Banerjee, Sandip and Byrka, Jaroslaw and Chalermsook, Parinya and Gadekar, Ameet and Khodamoradi, Kamyar and Marx, Dániel and Sharma, Roohani and Spoerhase, Joachim}, booktitle = {Proc. 51st International Colloquium on Automata, Languages and Programming (ICALP'24)}, keywords = {algorithm}, title = {Parameterized Approximation for Robust Clustering in Discrete Geometric Spaces}, year = 2024 }
• Comprehensive Exploration of Synthetic Data Generation: A Survey. Bauer, André; and Trapp, Simon; and Stenger, Michael; and Leppich, Robert; and Kounev, Samuel; and Leznik, Mark; and Chard, Kyle; and Foster, Ian. In arXiv preprint, p. 103. 2024.
  • [ BibTeX ]
  @article{bauer2024comprehensive, author = {Bauer, André and and Trapp, Simon and and Stenger, Michael and and Leppich, Robert and and Kounev, Samuel and and Leznik, Mark and and Chard, Kyle and and Foster, Ian}, journal = {arXiv preprint}, keywords = {t_journalmagazine}, note = {https://doi.org/10.48550/arXiv.2401.02524}, pages = 103, title = {Comprehensive Exploration of Synthetic Data Generation: A Survey}, year = 2024 }
• Monitoring the Quality of Streaming and Internet of Things Applications. Technical Report (PhD dissertation), . Loh, Frank. PhD dissertation. University of Würzburg, 2024, January.
  • [ BibTeX ]
  @phdthesis{info3-dissertation-2024-1, author = {Loh, Frank}, keywords = {myown}, month = {01}, school = {University of Würzburg}, title = {Monitoring the Quality of Streaming and Internet of Things Applications}, year = 2024 }
• Recommender-based User Guidance Framework. Babu, Sooraj K; Chetitah, Mounsif; von Mammen, Sebastian. In 2024 IEEE International Conference on Artificial Intelligence and eXtended and Virtual Reality (AIxVR), pp. 275–280. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  User guidance is crucial for a seamless user experience in a software system. This paper explores the need for effective user guidance mechanisms to enhance user experience and reduce human errors and frustration. In order to do that, we formalise and symbolically represent user guidance for versatile applications across diverse contexts by considering the knowledge base on users and software systems. We comprehensively analyse four distinct categories of user guidance mechanisms, namely, familiarisation, continuation, navigation, and customisation, with examples and expected data needed for each category. In addition, we investigate whether a recommender system (RS) can function as an appropriate tool to intelligently guide a user through a virtual reality (VR) authoring platform and describe the implementation of the corresponding RS-based guidance mechanism that aligns with the proposed formalisation. The paper concludes with a discussion of the present state of affairs and prospects for future research.

  @inproceedings{10445551, abstract = {User guidance is crucial for a seamless user experience in a software system. This paper explores the need for effective user guidance mechanisms to enhance user experience and reduce human errors and frustration. In order to do that, we formalise and symbolically represent user guidance for versatile applications across diverse contexts by considering the knowledge base on users and software systems. We comprehensively analyse four distinct categories of user guidance mechanisms, namely, familiarisation, continuation, navigation, and customisation, with examples and expected data needed for each category. In addition, we investigate whether a recommender system (RS) can function as an appropriate tool to intelligently guide a user through a virtual reality (VR) authoring platform and describe the implementation of the corresponding RS-based guidance mechanism that aligns with the proposed formalisation. The paper concludes with a discussion of the present state of affairs and prospects for future research.}, author = {Babu, Sooraj K and Chetitah, Mounsif and von Mammen, Sebastian}, booktitle = {2024 IEEE International Conference on Artificial Intelligence and eXtended and Virtual Reality (AIxVR)}, keywords = {myown}, month = {01}, pages = {275-280}, title = {Recommender-based User Guidance Framework}, year = 2024 }
• CompTrails: comparing hypotheses across behavioral networks. Koopmann, Tobias; Becker, Martin; Lemmerich, Florian; Hotho, Andreas. In Data Mining and Knowledge Discovery. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The term Behavioral Networks describes networks that contain relational information on human behavior. This ranges from social networks that contain friendships or cooperations between individuals, to navigational networks that contain geographical or web navigation, and many more. Understanding the forces driving behavior within these networks can be beneficial to improving the underlying network, for example, by generating new hyperlinks on websites, or by proposing new connections and friends on social networks. Previous approaches considered different hypotheses on a single network and evaluated which hypothesis fits best. These hypotheses can represent human intuition and expert opinions or be based on previous insights. In this work, we extend these approaches to enable the comparison of a single hypothesis between multiple networks. We unveil several issues of naive approaches that potentially impact comparisons and lead to undesired results. Based on these findings, we propose a framework with five flexible components that allow addressing specific analysis goals tailored to the application scenario. We show the benefits and limits of our approach by applying it to synthetic data and several real-world datasets, including web navigation, bibliometric navigation, and geographic navigation. Our work supports practitioners and researchers with the aim of understanding similarities and differences in human behavior between environments.

  @article{Koopmann2024, abstract = {The term Behavioral Networks describes networks that contain relational information on human behavior. This ranges from social networks that contain friendships or cooperations between individuals, to navigational networks that contain geographical or web navigation, and many more. Understanding the forces driving behavior within these networks can be beneficial to improving the underlying network, for example, by generating new hyperlinks on websites, or by proposing new connections and friends on social networks. Previous approaches considered different hypotheses on a single network and evaluated which hypothesis fits best. These hypotheses can represent human intuition and expert opinions or be based on previous insights. In this work, we extend these approaches to enable the comparison of a single hypothesis between multiple networks. We unveil several issues of naive approaches that potentially impact comparisons and lead to undesired results. Based on these findings, we propose a framework with five flexible components that allow addressing specific analysis goals tailored to the application scenario. We show the benefits and limits of our approach by applying it to synthetic data and several real-world datasets, including web navigation, bibliometric navigation, and geographic navigation. Our work supports practitioners and researchers with the aim of understanding similarities and differences in human behavior between environments.}, author = {Koopmann, Tobias and Becker, Martin and Lemmerich, Florian and Hotho, Andreas}, journal = {Data Mining and Knowledge Discovery}, keywords = {hypotheses}, month = {01}, title = {CompTrails: comparing hypotheses across behavioral networks}, year = 2024 }
• Plan the Access? Generic Hardware Independent Energy Consumption and Efficiency Model for Different LoRaWAN Channel Access Approaches. Loh, Frank; Raffeck, Simon; Geißler, Stefan; Hoßfeld, Tobias. In IEEE Internet of Things Journal. 2024.
  • [ BibTeX ]
  @article{info3-article-2024-3, author = {Loh, Frank and Raffeck, Simon and Geißler, Stefan and Hoßfeld, Tobias}, journal = {IEEE Internet of Things Journal}, keywords = {greenfield}, month = {02}, title = {Plan the Access? Generic Hardware Independent Energy Consumption and Efficiency Model for Different LoRaWAN Channel Access Approaches}, year = 2024 }
• A Data-Driven Model for Range Sensors. Spiess, Florian; Strobel, Norbert; Kaupp, Tobias; Kounev, Samuel. In International Journal of Semantic Computing, pp. 1–18. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In this paper, an analysis of the precision of range sensors is presented. Light Detection and Ranging (LIDAR) data from three different sensors (HLS-LFCD-LDS, SICK TIM561, and Kinect V2), stereo data from the Realsense D435, and structured light data from both Kinect V1 for Xbox and the Xtion PRO Live were analyzed regarding the influence of range, incident angle to the surface, and surface material. In addition, a comparison with standard deviation models based on vendor-provided specifications was performed. We found that the vendor specifications are in general not specific enough to facilitate accurate sensor simulations. Therefore, we developed a data-driven model for range precision. Our model can be used to create realistic sensor simulations and to develop robot navigation algorithms weighing sensor range readings based on the precision.

  @article{doi:10.1142/S1793351X24300012, abstract = {In this paper, an analysis of the precision of range sensors is presented. Light Detection and Ranging (LIDAR) data from three different sensors (HLS-LFCD-LDS, SICK TIM561, and Kinect V2), stereo data from the Realsense D435, and structured light data from both Kinect V1 for Xbox and the Xtion PRO Live were analyzed regarding the influence of range, incident angle to the surface, and surface material. In addition, a comparison with standard deviation models based on vendor-provided specifications was performed. We found that the vendor specifications are in general not specific enough to facilitate accurate sensor simulations. Therefore, we developed a data-driven model for range precision. Our model can be used to create realistic sensor simulations and to develop robot navigation algorithms weighing sensor range readings based on the precision.}, author = {Spiess, Florian and Strobel, Norbert and Kaupp, Tobias and Kounev, Samuel}, journal = {International Journal of Semantic Computing}, keywords = {t_journalmagazine}, month = {02}, pages = {1-18}, title = {A Data-Driven Model for Range Sensors}, year = 2024 }
• A Data-Driven Model for Range Sensors. Spiess, Florian; Strobel, Norbert; Kaupp, Tobias; Kounev, Samuel. In International Journal of Semantic Computing, pp. 1–18. 2024.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In this paper, an analysis of the precision of range sensors is presented. Light Detection and Ranging (LIDAR) data from three different sensors (HLS-LFCD-LDS, SICK TIM561, and Kinect V2), stereo data from the Realsense D435, and structured light data from both Kinect V1 for Xbox and the Xtion PRO Live were analyzed regarding the influence of range, incident angle to the surface, and surface material. In addition, a comparison with standard deviation models based on vendor-provided specifications was performed. We found that the vendor specifications are in general not specific enough to facilitate accurate sensor simulations. Therefore, we developed a data-driven model for range precision. Our model can be used to create realistic sensor simulations and to develop robot navigation algorithms weighing sensor range readings based on the precision.

  @article{doi:10.1142/S1793351X24300012, abstract = {In this paper, an analysis of the precision of range sensors is presented. Light Detection and Ranging (LIDAR) data from three different sensors (HLS-LFCD-LDS, SICK TIM561, and Kinect V2), stereo data from the Realsense D435, and structured light data from both Kinect V1 for Xbox and the Xtion PRO Live were analyzed regarding the influence of range, incident angle to the surface, and surface material. In addition, a comparison with standard deviation models based on vendor-provided specifications was performed. We found that the vendor specifications are in general not specific enough to facilitate accurate sensor simulations. Therefore, we developed a data-driven model for range precision. Our model can be used to create realistic sensor simulations and to develop robot navigation algorithms weighing sensor range readings based on the precision.}, author = {Spiess, Florian and Strobel, Norbert and Kaupp, Tobias and Kounev, Samuel}, journal = {International Journal of Semantic Computing}, keywords = {t_journalmagazine}, month = {02}, pages = {1-18}, title = {A Data-Driven Model for Range Sensors}, year = 2024 }
• Investigation of Container Network Function Deployment Costs in the Edge Cloud. TrungKien, Nguyen; Simonovski, Filip; Loh, Frank; Hoßfeld, Tobias; Huu Thanh, Nguyen. In 27th Conference on Innovation in Clouds, Internet and Networks (ICIN). 2024.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2024-2, author = {TrungKien, Nguyen and Simonovski, Filip and Loh, Frank and Hoßfeld, Tobias and Huu Thanh, Nguyen}, booktitle = {27th Conference on Innovation in Clouds, Internet and Networks (ICIN)}, keywords = {myown}, month = {03}, title = {Investigation of Container Network Function Deployment Costs in the Edge Cloud}, year = 2024 }
• Recent Advances in Procedural Generation of Buildings: From Diversity to Integration. Kutzias, Damian; von Mammen, Sebastian. In IEEE Trans. Games, 16(1), pp. 16–35. 2024.
  • [ BibTeX ]
  • [ URL ]
  @article{journals/tciaig/KutziasM24, author = {Kutzias, Damian and von Mammen, Sebastian}, journal = {IEEE Trans. Games}, keywords = {myown}, month = {03}, number = 1, pages = {16-35}, title = {Recent Advances in Procedural Generation of Buildings: From Diversity to Integration.}, volume = 16, year = 2024 }

• Planar {L}-Drawings of Directed Graphs. Chaplick, Steven; Chimani, Markus; Cornelsen, Sabine; {Da Lozzo}, Giordano; Nöllenburg, Martin; Patrignani, Maurizio; Tollis, Ioannis G.; Wolff, Alexander. In Computing in Geometry and Topology, 2(1), pp. 7:1–7:15. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  In this paper, we study drawings of directed graphs. We use the L-drawing standard where each edge is represented by a polygonal chain that consists of a vertical line segment incident to the source of the edge and a horizontal line segment incident to the target. \par First, we consider planar L-drawings. We provide necessary conditions for the existence of these drawings and show that testing for the existence of a planar L-drawing is an NP-complete problem. We also show how to decide in linear time whether there exists a planar L-drawing of a plane directed graph with a fixed assignment of the edges to the four sides (top, bottom, left, and right) of the vertices. \par Second, we consider upward- (resp.\ upward-rightward-) planar L-drawings. We provide upper bounds on the maximum number of edges of graphs admitting such drawings. Moreover, we characterize the directed st-graphs admitting an upward- (resp.\ upward-rightward-) planar L-drawing as exactly those admitting an embedding supporting a bitonic (resp.\ monotonically decreasing) st-ordering.

  @article{cccdnptw-plddg-JGAA23, abstract = {In this paper, we study drawings of directed graphs. We use the L-drawing standard where each edge is represented by a polygonal chain that consists of a vertical line segment incident to the source of the edge and a horizontal line segment incident to the target. \par First, we consider planar L-drawings. We provide necessary conditions for the existence of these drawings and show that testing for the existence of a planar L-drawing is an NP-complete problem. We also show how to decide in linear time whether there exists a planar L-drawing of a plane directed graph with a fixed assignment of the edges to the four sides (top, bottom, left, and right) of the vertices. \par Second, we consider upward- (resp.\ upward-rightward-) planar L-drawings. We provide upper bounds on the maximum number of edges of graphs admitting such drawings. Moreover, we characterize the directed st-graphs admitting an upward- (resp.\ upward-rightward-) planar L-drawing as exactly those admitting an embedding supporting a bitonic (resp.\ monotonically decreasing) st-ordering.}, author = {Chaplick, Steven and Chimani, Markus and Cornelsen, Sabine and {Da Lozzo}, Giordano and Nöllenburg, Martin and Patrignani, Maurizio and Tollis, Ioannis G. and Wolff, Alexander}, journal = {Computing in Geometry and Topology}, keywords = {bitonic_st-ordering}, number = 1, pages = {7:1–7:15}, title = {Planar {L}-Drawings of Directed Graphs}, volume = 2, year = 2023 }
• Telescope: An Automated Hybrid Forecasting Approach on a Level-Playing Field. Bauer, André; Leznik, Mark; Stenger, Michael; Leppich, Robert; Herbst, Nikolas; Kounev, Samuel; Foster, Ian. 2023.
  • [ BibTeX ]
  @misc{bauer2023telescope, author = {Bauer, André and Leznik, Mark and Stenger, Michael and Leppich, Robert and Herbst, Nikolas and Kounev, Samuel and Foster, Ian}, keywords = {t_journalmagazine}, title = {Telescope: An Automated Hybrid Forecasting Approach on a Level-Playing Field}, year = 2023 }
• A Simple Pipeline for Orthogonal Graph Drawing. Hegemann, Tim; Wolff, Alexander. In Proc. 31st Int. Symp. Graph Drawing \& Network Vis. (GD’23), Vol. 14466 of Lecture Notes in Computer Science, M. Bekos, M. Chimani (eds.), pp. 170–186. Springer-Verlag, 2023.
  • [ BibTeX ]
  @inproceedings{hw-spogd-GD23, author = {Hegemann, Tim and Wolff, Alexander}, booktitle = {Proc. 31st Int. Symp. Graph Drawing \& Network Vis. (GD'23)}, editor = {Bekos, Michael and Chimani, Markus}, keywords = {myown}, pages = {170–186}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {A Simple Pipeline for Orthogonal Graph Drawing}, volume = 14466, year = 2023 }
• An Empirical Study of Container Image Configurations and Their Impact on Start Times. Straesser, Martin; Bauer, André; Leppich, Robert; Herbst, Nikolas; Chard, Kyle; Foster, Ian; Kounev, Samuel. In 2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing (CCGrid), pp. 94–105. IEEE, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{straesser2023starttime, author = {Straesser, Martin and Bauer, André and Leppich, Robert and Herbst, Nikolas and Chard, Kyle and Foster, Ian and Kounev, Samuel}, booktitle = {2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing (CCGrid)}, keywords = {empirical_study}, pages = {94-105}, publisher = {IEEE}, title = {An Empirical Study of Container Image Configurations and Their Impact on Start Times}, year = 2023 }
• Visualizing Multispecies Coalescent Trees: Drawing Gene Trees Inside Species Trees. Klawitter, Jonathan; Klesen, Felix; Niederer, Moritz; Wolff, Alexander. In Proc. 49th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM’23), Vol. 13878 of Lecture Notes in Computer Science, L. Gąsieniec (ed.), pp. 96–110. Springer-Verlag, 2023.
  • [ BibTeX ]
  @inproceedings{kknw-vmct-SOFSEM23, author = {Klawitter, Jonathan and Klesen, Felix and Niederer, Moritz and Wolff, Alexander}, booktitle = {Proc. 49th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM'23)}, editor = {Gąsieniec, Leszek}, keywords = {myown}, pages = {96–110}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Visualizing Multispecies Coalescent Trees: Drawing Gene Trees Inside Species Trees}, volume = 13878, year = 2023 }
• Autoscaler Evaluation and Configuration: A Practitioner’s Guideline. Straesser, Martin; Eismann, Simon; von Kistowski, J{ó}akim; Bauer, Andr{é}; Kounev, Samuel. In Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23, pp. 31–41. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Autoscalers are indispensable parts of modern cloud deployments and determine the service quality and cost of a cloud application in dynamic workloads. The configuration of an autoscaler strongly influences its performance and is also one of the biggest challenges and showstoppers for the practical applicability of many research autoscalers. Many proposed cloud experiment methodologies can only be partially applied in practice, and many autoscaling papers use custom evaluation methods and metrics. This paper presents a practical guideline for obtaining meaningful and interpretable results on autoscaler performance with reasonable overhead. We provide step-by-step instructions for defining realistic usage behaviors and traffic patterns. We divide the analysis of autoscaler performance into a qualitative antipattern-based analysis and a quantitative analysis. To demonstrate the applicability of our guideline, we conduct several experiments with a microservice of our industry partner in a realistic test environment.

  @inproceedings{straesser2023guideline, abstract = {Autoscalers are indispensable parts of modern cloud deployments and determine the service quality and cost of a cloud application in dynamic workloads. The configuration of an autoscaler strongly influences its performance and is also one of the biggest challenges and showstoppers for the practical applicability of many research autoscalers. Many proposed cloud experiment methodologies can only be partially applied in practice, and many autoscaling papers use custom evaluation methods and metrics. This paper presents a practical guideline for obtaining meaningful and interpretable results on autoscaler performance with reasonable overhead. We provide step-by-step instructions for defining realistic usage behaviors and traffic patterns. We divide the analysis of autoscaler performance into a qualitative antipattern-based analysis and a quantitative analysis. To demonstrate the applicability of our guideline, we conduct several experiments with a microservice of our industry partner in a realistic test environment.}, address = {New York, NY, USA}, author = {Straesser, Martin and Eismann, Simon and von Kistowski, J\'{o}akim and Bauer, Andr\'{e} and Kounev, Samuel}, booktitle = {Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {methodology}, pages = {31-41}, publisher = {Association for Computing Machinery}, series = {ICPE '23}, title = {Autoscaler Evaluation and Configuration: A Practitioner's Guideline}, year = 2023 }
• A Trace-driven Performance Evaluation of Hash-based Task Placement Algorithms for Cache-enabled Serverless Computing. Talluri, Sacheendra; Herbst, Nikolas; Abad, Cristina; Trivedi, Animesh; Iosup, Alexandru. In 2023 ACM International Conference on Computing Frontiers (CF ’23). 2023.
  • [ BibTeX ]
  @inproceedings{2023-cf-hash-task-placement, author = {Talluri, Sacheendra and Herbst, Nikolas and Abad, Cristina and Trivedi, Animesh and Iosup, Alexandru}, booktitle = {2023 ACM International Conference on Computing Frontiers (CF '23)}, keywords = {performance}, title = {A Trace-driven Performance Evaluation of Hash-based Task Placement Algorithms for Cache-enabled Serverless Computing}, year = 2023 }
• Serverless Computing Lifecycle Model for Edge Cloud Deployments. Nguyen, TrungKien; Loh, Frank; Nguyen, Tung; Doan, Duong; Huu Thanh, Nguyen; Hoßfeld, Tobias. In IEEE International Conference on Communications 2023 - GreenNet Workshop. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Serverless computing is a new cloud computing execution model. It offers little operational and administrative overhead, function activation on-demand, and significantly reduced resource consumption. For that reason, it is studied heavily in recent literature by means of handling incoming traffic, applicability for different tasks, and overall performance. Especially the introduction of states, where functionality is kept in CPU or memory can improve performance significantly. However, an in-depth analysis of the resource demand by among others, CPU and memory usage, latency, and energy consumption is still a blank spot in literature. To this end, we propose a serverless lifecycle model with intermediate states and deploy an image processing test setup in the edge cloud to test it. Furthermore, we measure important resource metrics of all states and state transitions of the model. This helps us to answer the question, whether keeping functions available in specific states of a serverless computing instance can improve performance without massive negative influence on the resource requirements.

  @inproceedings{info3-article-2023-4, abstract = {Serverless computing is a new cloud computing execution model. It offers little operational and administrative overhead, function activation on-demand, and significantly reduced resource consumption. For that reason, it is studied heavily in recent literature by means of handling incoming traffic, applicability for different tasks, and overall performance. Especially the introduction of states, where functionality is kept in CPU or memory can improve performance significantly. However, an in-depth analysis of the resource demand by among others, CPU and memory usage, latency, and energy consumption is still a blank spot in literature. To this end, we propose a serverless lifecycle model with intermediate states and deploy an image processing test setup in the edge cloud to test it. Furthermore, we measure important resource metrics of all states and state transitions of the model. This helps us to answer the question, whether keeping functions available in specific states of a serverless computing instance can improve performance without massive negative influence on the resource requirements.}, author = {Nguyen, TrungKien and Loh, Frank and Nguyen, Tung and Doan, Duong and Huu Thanh, Nguyen and Hoßfeld, Tobias}, booktitle = {IEEE International Conference on Communications 2023 - GreenNet Workshop}, keywords = {myown}, title = {Serverless Computing Lifecycle Model for Edge Cloud Deployments}, year = 2023 }
• Towards Simulation-Driven Optimization of Container Orchestration Mechanisms. Dittus, Timo; Straesser, Martin; Kounev, Samuel. 2023.
  • [ BibTeX ]
  @presentation{dittus2023simdrivenopt, author = {Dittus, Timo and Straesser, Martin and Kounev, Samuel}, keywords = {container_orchestration}, title = {Towards Simulation-Driven Optimization of Container Orchestration Mechanisms}, year = 2023 }
• From Clocks to Pendulums: A Study on the Influence of External Moving Objects on Time Perception in Virtual Environments. Landeck, Maximilian; Unruh, Fabian; Lugrin, Jean-Luc; Latoschik, Marc Erich. In The 29th ACM Symposium on Virtual Reality Software and Technology (VRST), 29th, p. 11. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper investigates the relationship between perceived object motion and the experience of time in virtual environments. We developed an application to measure how the motion properties of virtual objects and the degree of immersion and embodiment may affect the time experience. A first study (n = 145) was conducted remotely using an online video survey, while a second study (n = 60) was conducted under laboratory conditions in virtual reality (VR). Participants in both studies experienced seven different virtual objects in a randomized order and then answered questions about time experience. The VR study added an "embodiment" condition in which participants were either represented by a virtual full body or lacked any form of virtual body representation. In both studies, time was judged to pass faster when viewing oscillating motion in immersive and non-immersive settings and independently of the presence or absence of a virtual body. This trend was strongest when virtual pendulums were displayed. Both studies also found a significant inverse correlation between the passage of time and boredom. Our results support the development of applications that manipulate the perception of time in virtual environments for therapeutic use, for instance, for disorders such as depression, autism, and schizophrenia. Disturbances in the perception of time are known to be associated with these disorders.

  @article{noauthororeditor, abstract = {This paper investigates the relationship between perceived object motion and the experience of time in virtual environments. We developed an application to measure how the motion properties of virtual objects and the degree of immersion and embodiment may affect the time experience. A first study (n = 145) was conducted remotely using an online video survey, while a second study (n = 60) was conducted under laboratory conditions in virtual reality (VR). Participants in both studies experienced seven different virtual objects in a randomized order and then answered questions about time experience. The VR study added an "embodiment" condition in which participants were either represented by a virtual full body or lacked any form of virtual body representation. In both studies, time was judged to pass faster when viewing oscillating motion in immersive and non-immersive settings and independently of the presence or absence of a virtual body. This trend was strongest when virtual pendulums were displayed. Both studies also found a significant inverse correlation between the passage of time and boredom. Our results support the development of applications that manipulate the perception of time in virtual environments for therapeutic use, for instance, for disorders such as depression, autism, and schizophrenia. Disturbances in the perception of time are known to be associated with these disorders.}, author = {Landeck, Maximilian and Unruh, Fabian and Lugrin, Jean-Luc and Latoschik, Marc Erich}, journal = {The 29th ACM Symposium on Virtual Reality Software and Technology (VRST)}, keywords = {landeck}, pages = 11, title = {From Clocks to Pendulums: A Study on the Influence of External Moving Objects on Time Perception in Virtual Environments}, volume = {29th}, year = 2023 }
• Telescope: An Automated Hybrid Forecasting Approach on a Level-Playing Field. Bauer, André; Leznik, Mark; Stenger, Michael; Leppich, Robert; Herbst, Nikolas; Kounev, Samuel; Foster, Ian. 2023.
  • [ BibTeX ]
  @misc{bauer2023telescope, author = {Bauer, André and Leznik, Mark and Stenger, Michael and Leppich, Robert and Herbst, Nikolas and Kounev, Samuel and Foster, Ian}, keywords = {t_journalmagazine}, title = {Telescope: An Automated Hybrid Forecasting Approach on a Level-Playing Field}, year = 2023 }
• ExDe: Design space exploration of scheduler architectures and mechanisms for serverless data-processing. Talluri, Sacheendra; Herbst, Nikolas; Abad, Cristina; {De Matteis}, Tiziano; Iosup, Alexandru. In Future Generation Computer Systems. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Serverless computing is increasingly used for data-processing applications in both science and business domains. At the core of serverless data-processing systems is the scheduler, which ensures dynamic decisions about task and data placement. Due to the variety of user, cluster, and workload properties, the design space for high-performance and cost-effective scheduling architectures and mechanisms is vast. The large design space is difficult to explore and characterize. To help the system designer disentangle this complexity, we present ExDe, a framework to systematically explore the design space of scheduling architectures and mechanisms. The framework includes a conceptual model and a simulator to assist in design space exploration. We use the framework, and real-world workloads, to characterize the performance of three scheduling architectures and two mechanisms. Our framework is open-source software available on Zenodo.

  @article{TALLURI2023, abstract = {Serverless computing is increasingly used for data-processing applications in both science and business domains. At the core of serverless data-processing systems is the scheduler, which ensures dynamic decisions about task and data placement. Due to the variety of user, cluster, and workload properties, the design space for high-performance and cost-effective scheduling architectures and mechanisms is vast. The large design space is difficult to explore and characterize. To help the system designer disentangle this complexity, we present ExDe, a framework to systematically explore the design space of scheduling architectures and mechanisms. The framework includes a conceptual model and a simulator to assist in design space exploration. We use the framework, and real-world workloads, to characterize the performance of three scheduling architectures and two mechanisms. Our framework is open-source software available on Zenodo.}, author = {Talluri, Sacheendra and Herbst, Nikolas and Abad, Cristina and {De Matteis}, Tiziano and Iosup, Alexandru}, journal = {Future Generation Computer Systems}, keywords = {t_journalmagazine}, note = {https://www.sciencedirect.com/science/article/pii/S0167739X23004211}, title = {ExDe: Design space exploration of scheduler architectures and mechanisms for serverless data-processing}, year = 2023 }
• Measuring trust with the Wayfinding Task: Implementing a novel task in immersive virtual reality and desktop setups across remote and in-person test environments. Clements, Michael F.; Brübach, Larissa; Glazov, Jessica; Gu, Stephanie; Kashif, Rahila; Catmur, Caroline; Georgescu, Alexandra L. In PLOS ONE. 2023.
  • [ BibTeX ]
  @article{clements2023measuring, author = {Clements, Michael F. and Brübach, Larissa and Glazov, Jessica and Gu, Stephanie and Kashif, Rahila and Catmur, Caroline and Georgescu, Alexandra L.}, journal = {PLOS ONE}, keywords = {myown}, title = {Measuring trust with the Wayfinding Task: Implementing a novel task in immersive virtual reality and desktop setups across remote and in-person test environments}, year = 2023 }
• Morphing Rectangular Duals. Chaplick, Steven; Kindermann, Philipp; Klawitter, Jonathan; Rutter, Ignaz; Wolff, Alexander. In Proc. 30th Int. Symp. Graph Drawing \& Network Vis. (GD’22), Vol. 13764 of Lecture Notes in Computer Science, P. Angelini, R. von Hanxleden (eds.), pp. 389–403. Springer-Verlag, 2023.
  • [ BibTeX ]
  @inproceedings{ckkrw-mrd-GD22, author = {Chaplick, Steven and Kindermann, Philipp and Klawitter, Jonathan and Rutter, Ignaz and Wolff, Alexander}, booktitle = {Proc. 30th Int. Symp. Graph Drawing \& Network Vis. (GD'22)}, editor = {Angelini, Patrizio and von Hanxleden, Reinhard}, keywords = {myown}, pages = {389–403}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Morphing Rectangular Duals}, volume = 13764, year = 2023 }
• The Complexity of Drawing Graphs on Few Lines and Few Planes. Chaplick, Steven; Fleszar, Krzysztof; Lipp, Fabian; Ravsky, Alexander; Verbitsky, Oleg; Wolff, Alexander. In Journal of Graph Algorithms \& Applications, 27(6), pp. 459–488. 2023.
  • [ BibTeX ]
  @article{cflrvw-cdgfl-JGAA23, author = {Chaplick, Steven and Fleszar, Krzysztof and Lipp, Fabian and Ravsky, Alexander and Verbitsky, Oleg and Wolff, Alexander}, journal = {Journal of Graph Algorithms \& Applications}, keywords = {myown}, number = 6, pages = {459–488}, title = {The Complexity of Drawing Graphs on Few Lines and Few Planes}, volume = 27, year = 2023 }
• Coloring and Recognizing Mixed Interval Graphs. Gutowski, Grzegorz; Junosza-Szaniawski, Konstanty; Klesen, Felix; Rzążewski, Paweł; Wolff, Alexander; Zink, Johannes. In Proc. 34th Annu. Int. Symp. Algorithms Comput. (ISAAC’23), Vol. 283 of LIPIcs, S. Iwata, N. Kakimura (eds.), pp. 36:1–36:14. Schloss Dagstuhl – Leibniz-Zentrum für Informatik, 2023.
  • [ BibTeX ]
  @inproceedings{gjkrwz-crdig-ISAAC23, author = {Gutowski, Grzegorz and Junosza-Szaniawski, Konstanty and Klesen, Felix and Rzążewski, Paweł and Wolff, Alexander and Zink, Johannes}, booktitle = {Proc. 34th Annu. Int. Symp. Algorithms Comput. (ISAAC'23)}, editor = {Iwata, Satoru and Kakimura, Naonori}, keywords = {myown}, pages = {36:1–36:14}, publisher = {Schloss Dagstuhl – Leibniz-Zentrum für Informatik}, series = {LIPIcs}, title = {Coloring and Recognizing Mixed Interval Graphs}, volume = 283, year = 2023 }
• Towards Querying Multimodal Annotations Using Graphs. Bruschke, Jonas; Köber, Cindy; Utescher, Ronja; Niebling, Florian. In Research and Education in Urban History in the Age of Digital Libraries, S. Münster, A. Pattee, C. Kröber, F. Niebling (eds.), pp. 65–87. Springer Nature Switzerland, Cham, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Photographs and 3D reconstructions of buildings as well as textual information and documents play an important role in art history and architectural studies when it comes to investigating architecture, the construction history of buildings, and the impact these constructions had on a city. Advanced tools have the potential to enhance and support research workflows and source criticism by linking corresponding materials and annotations, such that relevant data can be quickly queried and identified. Images are a primary source in the 3D reconstruction process, with the possibility to create spatializations of additional photographs of buildings which were not part of the initial SfM process, enabling the linking of annotations between these photographs and the respective 3D model. In contrast, identifying and locating respective annotations in text sources requires a different approach due to their more abstract nature. This paper presents concepts for automatic linking of texts and their respective annotations to corresponding images, as well as to 3D models and their annotations. Controlled vocabularies for architectural elements and a graph representation are utilized to reduce ambiguity when querying related instances.

  @inproceedings{10.1007/978-3-031-38871-2_5, abstract = {Photographs and 3D reconstructions of buildings as well as textual information and documents play an important role in art history and architectural studies when it comes to investigating architecture, the construction history of buildings, and the impact these constructions had on a city. Advanced tools have the potential to enhance and support research workflows and source criticism by linking corresponding materials and annotations, such that relevant data can be quickly queried and identified. Images are a primary source in the 3D reconstruction process, with the possibility to create spatializations of additional photographs of buildings which were not part of the initial SfM process, enabling the linking of annotations between these photographs and the respective 3D model. In contrast, identifying and locating respective annotations in text sources requires a different approach due to their more abstract nature. This paper presents concepts for automatic linking of texts and their respective annotations to corresponding images, as well as to 3D models and their annotations. Controlled vocabularies for architectural elements and a graph representation are utilized to reduce ambiguity when querying related instances.}, address = {Cham}, author = {Bruschke, Jonas and Köber, Cindy and Utescher, Ronja and Niebling, Florian}, booktitle = {Research and Education in Urban History in the Age of Digital Libraries}, editor = {Münster, Sander and Pattee, Aaron and Kröber, Cindy and Niebling, Florian}, keywords = {histstadt4d}, pages = {65–87}, publisher = {Springer Nature Switzerland}, title = {Towards Querying Multimodal Annotations Using Graphs}, year = 2023 }
• Virtual reality in medical emergencies training: benefits, perceived stress, and learning success. M{ü}hling, Tobias; Sp{ä}th, Isabelle; Backhaus, Joy; Milke, Nathalie; Oberd{ö}rfer, Sebastian; Meining, Alexander; Latoschik, Marc Erich; K{ö}nig, Sarah. In Multimedia Systems. Springer Nature, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Medical graduates lack procedural skills experience required to manage emergencies. Recent advances in virtual reality (VR)technology enable the creation of highly immersive learning environments representing easy-to-use and affordable solutionsfor training with simulation. However, the feasibility in compulsory teaching, possible side effects of immersion, perceivedstress, and didactic benefits have to be investigated systematically. VR-based training sessions using head-mounted displaysalongside a real-time dynamic physiology system were held by student assistants for small groups followed by debriefing witha tutor. In the pilot study, 36 students rated simulation sickness. In the main study, 97 students completed a virtual scenarioas active participants (AP) and 130 students as observers (OBS) from the first-person perspective on a monitor. Participantscompleted questionnaires for evaluation purposes and exploratory factor analysis was performed on the items. The extent ofsimulation sickness remained low to acceptable among participants of the pilot study. In the main study, students valued therealistic environment and guided practical exercise. AP perceived the degree of immersion as well as the estimated learn-ing success to be greater than OBS and proved to be more motivated post training. With respect to AP, the factor “sense ofcontrol” revealed a typical inverse U-shaped relationship to the scales “didactic value” and “individual learning benefit”.Summing up, curricular implementation of highly immersive VR-based training of emergencies proved feasible and founda high degree of acceptance among medical students. This study also provides insights into how different conceptions of perceived stress distinctively moderate subjective learning success.

  @article{muhling:2023, abstract = {Medical graduates lack procedural skills experience required to manage emergencies. Recent advances in virtual reality (VR)technology enable the creation of highly immersive learning environments representing easy-to-use and affordable solutionsfor training with simulation. However, the feasibility in compulsory teaching, possible side effects of immersion, perceivedstress, and didactic benefits have to be investigated systematically. VR-based training sessions using head-mounted displaysalongside a real-time dynamic physiology system were held by student assistants for small groups followed by debriefing witha tutor. In the pilot study, 36 students rated simulation sickness. In the main study, 97 students completed a virtual scenarioas active participants (AP) and 130 students as observers (OBS) from the first-person perspective on a monitor. Participantscompleted questionnaires for evaluation purposes and exploratory factor analysis was performed on the items. The extent ofsimulation sickness remained low to acceptable among participants of the pilot study. In the main study, students valued therealistic environment and guided practical exercise. AP perceived the degree of immersion as well as the estimated learn-ing success to be greater than OBS and proved to be more motivated post training. With respect to AP, the factor “sense ofcontrol” revealed a typical inverse U-shaped relationship to the scales “didactic value” and “individual learning benefit”.Summing up, curricular implementation of highly immersive VR-based training of emergencies proved feasible and founda high degree of acceptance among medical students. This study also provides insights into how different conceptions of perceived stress distinctively moderate subjective learning success.}, author = {M{\"u}hling, Tobias and Sp{\"a}th, Isabelle and Backhaus, Joy and Milke, Nathalie and Oberd{\"o}rfer, Sebastian and Meining, Alexander and Latoschik, Marc Erich and K{\"o}nig, Sarah}, journal = {Multimedia Systems}, keywords = {myown}, publisher = {Springer Nature}, title = {Virtual reality in medical emergencies training: benefits, perceived stress, and learning success}, year = 2023 }
• Text Input for Non-Stationary XR Workspaces: Investigating Tap and Word-Gesture Keyboards in Virtual and Augmented Reality. Kern, Florian; Niebling, Florian; Latoschik, Marc Erich. In IEEE Transactions on Visualization and Computer Graphics, pp. 2658–2669. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This article compares two state-of-the-art text input techniques between non-stationary virtual reality (VR) and video see-through augmented reality (VST AR) use-cases as XR display condition. The developed contact-based mid-air virtual tap and wordgesture (swipe) keyboard provide established support functions for text correction, word suggestions, capitalization, and punctuation. A user evaluation with 64 participants revealed that XR displays and input techniques strongly affect text entry performance, while subjective measures are only influenced by the input techniques. We found significantly higher usability and user experience ratings for tap keyboards compared to swipe keyboards in both VR and VST AR. Task load was also lower for tap keyboards. In terms of performance, both input techniques were significantly faster in VR than in VST AR. Further, the tap keyboard was significantly faster than the swipe keyboard in VR. Participants showed a significant learning effect with only ten sentences typed per condition. Our results are consistent with previous work in VR and optical see-through (OST) AR, but additionally provide novel insights into usability and performance of the selected text input techniques for VST AR. The significant differences in subjective and objective measures emphasize the importance of specific evaluations for each possible combination of input techniques and XR displays to provide reusable, reliable, and high-quality text input solutions. With our work, we form a foundation for future research and XR workspaces. Our reference implementation is publicly available to encourage replicability and reuse in future XR workspaces.

  @article{kern2023input, abstract = {This article compares two state-of-the-art text input techniques between non-stationary virtual reality (VR) and video see-through augmented reality (VST AR) use-cases as XR display condition. The developed contact-based mid-air virtual tap and wordgesture (swipe) keyboard provide established support functions for text correction, word suggestions, capitalization, and punctuation. A user evaluation with 64 participants revealed that XR displays and input techniques strongly affect text entry performance, while subjective measures are only influenced by the input techniques. We found significantly higher usability and user experience ratings for tap keyboards compared to swipe keyboards in both VR and VST AR. Task load was also lower for tap keyboards. In terms of performance, both input techniques were significantly faster in VR than in VST AR. Further, the tap keyboard was significantly faster than the swipe keyboard in VR. Participants showed a significant learning effect with only ten sentences typed per condition. Our results are consistent with previous work in VR and optical see-through (OST) AR, but additionally provide novel insights into usability and performance of the selected text input techniques for VST AR. The significant differences in subjective and objective measures emphasize the importance of specific evaluations for each possible combination of input techniques and XR displays to provide reusable, reliable, and high-quality text input solutions. With our work, we form a foundation for future research and XR workspaces. Our reference implementation is publicly available to encourage replicability and reuse in future XR workspaces.}, author = {Kern, Florian and Niebling, Florian and Latoschik, Marc Erich}, journal = {IEEE Transactions on Visualization and Computer Graphics}, keywords = {vilearn}, pages = {2658–2669}, title = {Text Input for Non-Stationary XR Workspaces: Investigating Tap and Word-Gesture Keyboards in Virtual and Augmented Reality}, year = 2023 }
• The Parametrized Complexity of the Segment Number. Cornelsen, Sabine; {Da Lozzo}, Giordano; Grilli, Luca; Gupta, Siddharth; Kratochvíl, Jan; Wolff, Alexander. In Proc. 31st Int. Symp. Graph Drawing \& Network Vis. (GD’23), Vol. 14466 of Lecture Notes in Computer Science, M. Bekos, M. Chimani (eds.), pp. 97–113. Springer-Verlag, 2023.
  • [ BibTeX ]
  @inproceedings{cdggkw-pcsn-GD23, author = {Cornelsen, Sabine and {Da Lozzo}, Giordano and Grilli, Luca and Gupta, Siddharth and Kratochvíl, Jan and Wolff, Alexander}, booktitle = {Proc. 31st Int. Symp. Graph Drawing \& Network Vis. (GD'23)}, editor = {Bekos, Michael and Chimani, Markus}, keywords = {myown}, pages = {97–113}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {The Parametrized Complexity of the Segment Number}, volume = 14466, year = 2023 }
• An Evaluation of Other-Avatar Facial Animation Methods for Social VR. Kullmann, Peter; Menzel, Timo; Botsch, Mario; Latoschik, Marc Erich. In Extended Abstracts of the 2023 CHI Conference on Human Factors in Computing Systems, of CHI EA ’23, pp. 1–7. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  We report a mixed-design study on the effect of facial animation method (static, synthesized, or tracked expressions) and its synchronization to speaker audio (in sync or delayed by the method’s inherent latency) on an avatar’s perceived naturalness and plausibility. We created a virtual human for an actor and recorded his spontaneous half-minute responses to conversation prompts. As a simulated immersive interaction, 44 participants unfamiliar with the actor observed and rated performances rendered with the avatar, each with the different facial animation methods. Half of them observed performances in sync and the others with the animation method’s latency. Results show audio synchronization did not influence ratings and static faces were rated less natural and less plausible than animated faces. Notably, synthesized expressions were rated as more natural and more plausible than tracked expressions. Moreover, ratings of verbal behavior naturalness differed in the same way. We discuss implications of these results for avatar-mediated communication.

  @inproceedings{kullmann2023facialExpressionComparison, abstract = {We report a mixed-design study on the effect of facial animation method (static, synthesized, or tracked expressions) and its synchronization to speaker audio (in sync or delayed by the method’s inherent latency) on an avatar’s perceived naturalness and plausibility. We created a virtual human for an actor and recorded his spontaneous half-minute responses to conversation prompts. As a simulated immersive interaction, 44 participants unfamiliar with the actor observed and rated performances rendered with the avatar, each with the different facial animation methods. Half of them observed performances in sync and the others with the animation method’s latency. Results show audio synchronization did not influence ratings and static faces were rated less natural and less plausible than animated faces. Notably, synthesized expressions were rated as more natural and more plausible than tracked expressions. Moreover, ratings of verbal behavior naturalness differed in the same way. We discuss implications of these results for avatar-mediated communication.}, address = {New York, NY, USA}, author = {Kullmann, Peter and Menzel, Timo and Botsch, Mario and Latoschik, Marc Erich}, booktitle = {Extended Abstracts of the 2023 CHI Conference on Human Factors in Computing Systems}, keywords = {xrhub}, pages = {1–7}, publisher = {Association for Computing Machinery}, series = {CHI EA '23}, title = {An Evaluation of Other-Avatar Facial Animation Methods for Social VR}, year = 2023 }
• Gamification Framework for Reinforcement Learning-based Neuropsychology Experiments. Chetitah, Mounsif; Müller, Julian; Deserno, Lorenz; Walttman, Maria; von Mammen, Sebastian. In Proceedings of the 18th International Conference on the Foundations of Digital Games, pp. 1–4. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Reinforcement learning (RL) is an adaptive process where an agent relies on its experience to improve the outcome of its performance. It learns by taking actions to maximize its rewards, and by minimizing the gap between predicted and received rewards. In experimental neuropsychology, RL algorithms are used as a conceptual basis to account for several aspects of human motivation and cognition. A number of neuropsychological experiments, such as reversal learning, sequential decision-making, and go-no-go tasks, are required to validate the decisive RL algorithms. The experiments are conducted in digital environments and are comprised of numerous trials that lead to participants’ frustration and fatigue. This paper presents a gamification framework for reinforcement-based neuropsychology experiments that aims to increase participant engagement and provide them with appropriate testing environments.

  @inproceedings{chetitah2023gamification, abstract = {Reinforcement learning (RL) is an adaptive process where an agent relies on its experience to improve the outcome of its performance. It learns by taking actions to maximize its rewards, and by minimizing the gap between predicted and received rewards. In experimental neuropsychology, RL algorithms are used as a conceptual basis to account for several aspects of human motivation and cognition. A number of neuropsychological experiments, such as reversal learning, sequential decision-making, and go-no-go tasks, are required to validate the decisive RL algorithms. The experiments are conducted in digital environments and are comprised of numerous trials that lead to participants’ frustration and fatigue. This paper presents a gamification framework for reinforcement-based neuropsychology experiments that aims to increase participant engagement and provide them with appropriate testing environments.}, author = {Chetitah, Mounsif and Müller, Julian and Deserno, Lorenz and Walttman, Maria and von Mammen, Sebastian}, booktitle = {Proceedings of the 18th International Conference on the Foundations of Digital Games}, keywords = {myown}, pages = {1–4}, title = {Gamification Framework for Reinforcement Learning-based Neuropsychology Experiments}, year = 2023 }
• An Approach to Investigate an Influence of Visual Angle Size on Emotional Activation During a Decision-Making Task. Oberdörfer, Sebastian; Birnstiel, Sandra; Steinhaeusser, Sophia C.; Latoschik, Marc Erich. In Virtual, Augmented and Mixed Reality (HCII 2023), of Lecture Notes in Computer Science, pp. 649–664. Springer Nature Switzerland, Cham, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Decision-making is an important ability in our daily lives. Decision-making can be influenced by emotions. A virtual environment and objects in it might follow an emotional design, thus potentially influ- encing the mood of a user. A higher visual angle on a particular stimulus can lead to a higher emotional response to it. The use of immersive vir- tual reality (VR) surrounds a user visually with a virtual environment, as opposed to the partial immersion of using a normal computer screen. This higher immersion may result in a greater visual angle on a particu- lar stimulus and thus a stronger emotional response to it. In a between- subjects user study, we compare the results of a decision-making task in VR presented in three different visual angles. We used the Iowa Gambling Task (IGT) as task and to detect potential differences in decision-making. The IGT was displayed in one of three dimensions, thus yielding visual angles of 20◦, 35◦, and 50◦. Our results indicate no difference between the three conditions with respect to decision-making. Thus, our results possibly imply that a higher visual angle has no influence on a task that is influenced by emotions but is otherwise cognitive.

  @inproceedings{oberdorfer2023approach, abstract = {Decision-making is an important ability in our daily lives. Decision-making can be influenced by emotions. A virtual environment and objects in it might follow an emotional design, thus potentially influ- encing the mood of a user. A higher visual angle on a particular stimulus can lead to a higher emotional response to it. The use of immersive vir- tual reality (VR) surrounds a user visually with a virtual environment, as opposed to the partial immersion of using a normal computer screen. This higher immersion may result in a greater visual angle on a particu- lar stimulus and thus a stronger emotional response to it. In a between- subjects user study, we compare the results of a decision-making task in VR presented in three different visual angles. We used the Iowa Gambling Task (IGT) as task and to detect potential differences in decision-making. The IGT was displayed in one of three dimensions, thus yielding visual angles of 20◦, 35◦, and 50◦. Our results indicate no difference between the three conditions with respect to decision-making. Thus, our results possibly imply that a higher visual angle has no influence on a task that is influenced by emotions but is otherwise cognitive.}, address = {Cham}, author = {Oberdörfer, Sebastian and Birnstiel, Sandra and Steinhaeusser, Sophia C. and Latoschik, Marc Erich}, booktitle = {Virtual, Augmented and Mixed Reality (HCII 2023)}, keywords = {steinhaeusser}, pages = {649–664}, publisher = {Springer Nature Switzerland}, series = {Lecture Notes in Computer Science}, title = {An Approach to Investigate an Influence of Visual Angle Size on Emotional Activation During a Decision-Making Task}, year = 2023 }
• The NarRobot Plugin - Connecting the Social Robot Reeti to the Unity Game Engine. Steinhaeusser, Sophia C.; Siol, Lenny; Ganal, Elisabeth; Maier, Sophia; Lugrin, Birgit. In Companion of the 2023 ACM/IEEE International Conference on Human-Robot Interaction (HRI). 2023.
  • [ BibTeX ]
  @inproceedings{steinhaeusser2023narrobot, author = {Steinhaeusser, Sophia C. and Siol, Lenny and Ganal, Elisabeth and Maier, Sophia and Lugrin, Birgit}, booktitle = {Companion of the 2023 ACM/IEEE International Conference on Human-Robot Interaction (HRI)}, keywords = {steinhaeusser}, title = {The NarRobot Plugin - Connecting the Social Robot Reeti to the Unity Game Engine}, year = 2023 }
• Deep Neural Network Regression for Normalized Digital Surface Model Generation with Sentinel-2 Imagery. Müller, Konstantin; Leppich, Robert; Geiß, Christian; Borst, Vanessa; Pelizari, Patrick Aravena; Kounev, Samuel. In IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, pp. 1–14. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  In recent history, normalized digital surface models (nDSMs) have been constantly gaining importance as a means to solve large-scale geographic problems. High-resolution surface models are precious, as they can provide detailed information for a specific area. However, measurements with a high resolution are time-consuming and costly. Only a few approaches exist to create high-resolution normalized digital surface models for extensive areas. This paper explores approaches to extract high-resolution nDSMs from low-resolution Sentinel-2 data, allowing us to derive large-scale models. We thereby utilize the advantages of Sentinel 2 being open access, having global coverage, and providing steady updates through a high repetition rate. Several deep-learning models are trained to overcome the gap in producing high-resolution surface maps from low-resolution input data. With U-Net as a base architecture, we extend the capabilities of our model by integrating tailored multiscale encoders with differently sized kernels in the convolution as well as conformed self-attention inside the skip connection gates. Using pixel-wise regression, our U-Net base models can achieve a mean height error of approximately two meters. Moreover, through our enhancements to the model architecture, we reduce the model error by more than seven percent.

  @article{10189905, abstract = {In recent history, normalized digital surface models (nDSMs) have been constantly gaining importance as a means to solve large-scale geographic problems. High-resolution surface models are precious, as they can provide detailed information for a specific area. However, measurements with a high resolution are time-consuming and costly. Only a few approaches exist to create high-resolution normalized digital surface models for extensive areas. This paper explores approaches to extract high-resolution nDSMs from low-resolution Sentinel-2 data, allowing us to derive large-scale models. We thereby utilize the advantages of Sentinel 2 being open access, having global coverage, and providing steady updates through a high repetition rate. Several deep-learning models are trained to overcome the gap in producing high-resolution surface maps from low-resolution input data. With U-Net as a base architecture, we extend the capabilities of our model by integrating tailored multiscale encoders with differently sized kernels in the convolution as well as conformed self-attention inside the skip connection gates. Using pixel-wise regression, our U-Net base models can achieve a mean height error of approximately two meters. Moreover, through our enhancements to the model architecture, we reduce the model error by more than seven percent.}, author = {Müller, Konstantin and Leppich, Robert and Geiß, Christian and Borst, Vanessa and Pelizari, Patrick Aravena and Kounev, Samuel}, journal = {IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing}, keywords = {t_journalmagazine}, pages = {1-14}, title = {Deep Neural Network Regression for Normalized Digital Surface Model Generation with Sentinel-2 Imagery}, year = 2023 }
• The Impact of Avatar and Environment Congruence on Plausibility, Embodiment, Presence, and the Proteus Effect in Virtual Reality. Mal, David; Wolf, Erik; Döllinger, Nina; Wienrich, Carolin; Latoschik, Marc Erich. In IEEE Transactions on Visualization and Computer Graphics, 29(5), pp. 2358–2368. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Many studies show the significance of the Proteus effect for serious virtual reality applications. The present study extends the existing knowledge by considering the relationship (congruence) between the self-embodiment (avatar) and the virtual environment. We investigated the impact of avatar and environment types and their congruence on avatar plausibility, sense of embodiment, spatial presence, and the Proteus effect. In a 2 × 2 between-subjects design, participants embodied either an avatar in sports- or business wear in a semantic congruent or incongruent environment while performing lightweight exercises in virtual reality. The avatar-environment congruence significantly affected the avatar’s plausibility but not the sense of embodiment or spatial presence. However, a significant Proteus effect emerged only for participants who reported a high feeling of (virtual) body ownership, indicating that a strong sense of having and owning a virtual body is key to facilitating the Proteus effect. We discuss the results assuming current theories of bottom-up and top-down determinants of the Proteus effect and thus contribute to understanding its underlying mechanisms and determinants.

  @article{mal2023impact, abstract = {Many studies show the significance of the Proteus effect for serious virtual reality applications. The present study extends the existing knowledge by considering the relationship (congruence) between the self-embodiment (avatar) and the virtual environment. We investigated the impact of avatar and environment types and their congruence on avatar plausibility, sense of embodiment, spatial presence, and the Proteus effect. In a 2 × 2 between-subjects design, participants embodied either an avatar in sports- or business wear in a semantic congruent or incongruent environment while performing lightweight exercises in virtual reality. The avatar-environment congruence significantly affected the avatar’s plausibility but not the sense of embodiment or spatial presence. However, a significant Proteus effect emerged only for participants who reported a high feeling of (virtual) body ownership, indicating that a strong sense of having and owning a virtual body is key to facilitating the Proteus effect. We discuss the results assuming current theories of bottom-up and top-down determinants of the Proteus effect and thus contribute to understanding its underlying mechanisms and determinants.}, author = {Mal, David and Wolf, Erik and Döllinger, Nina and Wienrich, Carolin and Latoschik, Marc Erich}, journal = {IEEE Transactions on Visualization and Computer Graphics}, keywords = {dmal}, number = 5, pages = {2358-2368}, title = {The Impact of Avatar and Environment Congruence on Plausibility, Embodiment, Presence, and the Proteus Effect in Virtual Reality}, volume = 29, year = 2023 }
• Measuring Interpersonal Trust towards Virtual Humans with a Virtual Maze Paradigm. Lin, Jinghuai; Cronjé, Johrine; Käthner, Ivo; Pauli, Paul; Latoschik, Marc Erich. In IEEE Transactions on Visualization and Computer Graphics (TVCG). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Virtual humans, including virtual agents and avatars, play an increasingly important role as VR technology advances. For example, virtual humans are used as proxies of users in social VR or as interfaces for AI assistants in online financing. Interpersonal trust is an essential prerequisite in real-life interactions, as well as in the virtual world. However, to date, there are no established interpersonal trust measurement tools specifically for virtual humans in virtual reality. Previously, a virtual maze task was proposed to measure trust towards virtual characters. For the current study, a variant of the paradigm was implemented. The task of the users (the trustors) is to navigate through a maze in virtual reality, where they can interact with a virtual human (the trustee). They can choose to 1) ask for advice and 2) follow advice from the virtual human if they want to. These measures served as behavioural measures of trust. We conducted a validation study with 70 participants in a between-subject design. The two conditions did not differ in the content of the advice but in the appearance, tone of voice and engagement of the trustees (alleged as avatars controlled by other participants). Results indicate that the experimental manipulation was successful, as participants rated the virtual human as more trustworthy in the trustworthy condition than in the untrustworthy condition. Importantly, this manipulation affected the trust behaviour of our participants, who, in the trustworthy condition, asked for advice more often and followed advice more often, indicating that the paradigm is sensitive to assessing interpersonal trust towards virtual humans. Thus, our paradigm can be used to measure differences in interpersonal trust towards virtual humans and may serve as a valuable research tool to investigate trust in virtual reality.

  @article{lin2023measuring, abstract = {Virtual humans, including virtual agents and avatars, play an increasingly important role as VR technology advances. For example, virtual humans are used as proxies of users in social VR or as interfaces for AI assistants in online financing. Interpersonal trust is an essential prerequisite in real-life interactions, as well as in the virtual world. However, to date, there are no established interpersonal trust measurement tools specifically for virtual humans in virtual reality. Previously, a virtual maze task was proposed to measure trust towards virtual characters. For the current study, a variant of the paradigm was implemented. The task of the users (the trustors) is to navigate through a maze in virtual reality, where they can interact with a virtual human (the trustee). They can choose to 1) ask for advice and 2) follow advice from the virtual human if they want to. These measures served as behavioural measures of trust. We conducted a validation study with 70 participants in a between-subject design. The two conditions did not differ in the content of the advice but in the appearance, tone of voice and engagement of the trustees (alleged as avatars controlled by other participants). Results indicate that the experimental manipulation was successful, as participants rated the virtual human as more trustworthy in the trustworthy condition than in the untrustworthy condition. Importantly, this manipulation affected the trust behaviour of our participants, who, in the trustworthy condition, asked for advice more often and followed advice more often, indicating that the paradigm is sensitive to assessing interpersonal trust towards virtual humans. Thus, our paradigm can be used to measure differences in interpersonal trust towards virtual humans and may serve as a valuable research tool to investigate trust in virtual reality.}, author = {Lin, Jinghuai and Cronjé, Johrine and Käthner, Ivo and Pauli, Paul and Latoschik, Marc Erich}, journal = {IEEE Transactions on Visualization and Computer Graphics (TVCG)}, keywords = {emlab}, note = {IEEE VR Best Paper Honorable Mention 🏆}, title = {Measuring Interpersonal Trust towards Virtual Humans with a Virtual Maze Paradigm}, year = 2023 }
• Using a Social Robot as a Hotel Assessment Tool. Lein, Martina; Donnermann, Melissa; Steinhaeusser, Sophia C.; Lugrin, Birgit. In Companion of the 2023 ACM/IEEE International Conference on Human-Robot Interaction (HRI). 2023.
  • [ BibTeX ]
  @inproceedings{lein2023, author = {Lein, Martina and Donnermann, Melissa and Steinhaeusser, Sophia C. and Lugrin, Birgit}, booktitle = {Companion of the 2023 ACM/IEEE International Conference on Human-Robot Interaction (HRI)}, keywords = {lein}, title = {Using a Social Robot as a Hotel Assessment Tool}, year = 2023 }
• Posture Parameters for Personality-Enhanced Virtual Audiences. Lugrin, Jean-Luc; Topel, Jessica; Glémarec, Yann; Lugrin, Birgit; Latoschik, Marc Erich. In Proceedings of the 23rd International Conference on Intelligent Virtual Agents (IVA). 2023.
  • [ BibTeX ]
  • [ URL ]
  @conference{lugrin2023posture, author = {Lugrin, Jean-Luc and Topel, Jessica and Glémarec, Yann and Lugrin, Birgit and Latoschik, Marc Erich}, booktitle = {Proceedings of the 23rd International Conference on Intelligent Virtual Agents (IVA)}, keywords = {hci-uwb}, title = {Posture Parameters for Personality-Enhanced Virtual Audiences}, year = 2023 }
• The Complexity of Finding Tangles. Firman, Oksana; Kindermann, Philipp; Klemz, Boris; Ravsky, Alexander; Wolff, Alexander; Zink, Johannes. In Proc. 49th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM’23), Vol. 13878 of Lecture Notes in Computer Science, L. Gąsieniec (ed.), pp. 3–17. Springer-Verlag, 2023.
  • [ BibTeX ]
  @inproceedings{fkkrwz-cotf-SOFSEM23, author = {Firman, Oksana and Kindermann, Philipp and Klemz, Boris and Ravsky, Alexander and Wolff, Alexander and Zink, Johannes}, booktitle = {Proc. 49th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM'23)}, editor = {Gąsieniec, Leszek}, keywords = {myown}, pages = {3–17}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {The Complexity of Finding Tangles}, volume = 13878, year = 2023 }
• Investigating Crowdsourced Help Facilities for Enhancing User Guidance. Babu, Sooraj K.; Brandner, Tobias; Truman, Samuel; Mammen, Sebastian von. In International Conference on Interactive Media, Smart Systems and Emerging Technologies (IMET), N. Pelechano, F. Liarokapis, D. Rohmer, A. Asadipour (eds.). The Eurographics Association, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  We present two help facilities aimed at addressing the challenges faced by users new to a software. Software documentation should ideally familiarise with the overall functionality, navigate through the concrete workflows, and opportunities for customisation. Large degrees of freedom in the use and vast basic scopes, however, often make it infeasible to convey this information upfront. Rather, it needs to be broken into helpful bits and pieces which are delivered at appropriate times. In order to address this challenge, we have designed two concrete help facilities, i.e. tooltips and tips-of-the-day, to feature crowdsourced information. In this paper, we present the results of a formative study to implement early proofs-of-concept for the open-source game authoring platform Godot. To support further research, we have made the code base publicly available on GitHub.

  @inproceedings{10.2312:imet.20231252, abstract = {We present two help facilities aimed at addressing the challenges faced by users new to a software. Software documentation should ideally familiarise with the overall functionality, navigate through the concrete workflows, and opportunities for customisation. Large degrees of freedom in the use and vast basic scopes, however, often make it infeasible to convey this information upfront. Rather, it needs to be broken into helpful bits and pieces which are delivered at appropriate times. In order to address this challenge, we have designed two concrete help facilities, i.e. tooltips and tips-of-the-day, to feature crowdsourced information. In this paper, we present the results of a formative study to implement early proofs-of-concept for the open-source game authoring platform Godot. To support further research, we have made the code base publicly available on GitHub.}, author = {Babu, Sooraj K. and Brandner, Tobias and Truman, Samuel and Mammen, Sebastian von}, booktitle = {International Conference on Interactive Media, Smart Systems and Emerging Technologies (IMET)}, editor = {Pelechano, Nuria and Liarokapis, Fotis and Rohmer, Damien and Asadipour, Ali}, keywords = {myown}, publisher = {The Eurographics Association}, title = {Investigating Crowdsourced Help Facilities for Enhancing User Guidance}, year = 2023 }
• An Empirical Study of Container Image Configurations and Their Impact on Start Times. Straesser, Martin; Bauer, André; Leppich, Robert; Herbst, Nikolas; Chard, Kyle; Foster, Ian; Kounev, Samuel. In 2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing (CCGrid), pp. 94–105. IEEE, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{straesser2023starttime, author = {Straesser, Martin and Bauer, André and Leppich, Robert and Herbst, Nikolas and Chard, Kyle and Foster, Ian and Kounev, Samuel}, booktitle = {2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing (CCGrid)}, keywords = {empirical_study}, pages = {94-105}, publisher = {IEEE}, title = {An Empirical Study of Container Image Configurations and Their Impact on Start Times}, year = 2023 }
• Virtual Reality im modernen Englischunterricht und das Potenzial für Inter- und Transkulturelles Lernen - Eine Pilotstudie. Hein, Rebecca; Steinbock, Jeanine; Eisenmann, Maria; Latoschik, Marc Erich; Wienrich, Carolin. In MedienPädagogik: Zeitschrift für Theorie Und Praxis Der Medienbildung, (51), M. Mulders; J. Buchner; A. Dengel; R. Zender (eds.), pp. 191–213. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Dieser Beitrag präsentiert die Ergebnisse des Seminarkonzepts und der durchgeführten Begleitforschung zum inter- und transkulturellen Lernen in Virtual Reality (VR). Im Rahmen eines Universitätsseminars entwarfen TEFL-Studierende (Teaching English as a Foreign Language) Unterrichtsstunden für fortgeschrittene Lernende des Faches Englisch der gymnasialen Oberstufe, die sich mit der Entwicklung von Empathie und der Fähigkeit zur Perspektivübernahme in interkulturellen Kommunikations- und Austauschsituationen befassten. Der Fokus des Konzepts lag dabei auf dem Verständnis und der Annahme kultureller Gemeinsamkeiten und Unterschiede. Hier werden beispielhaft zwei der erstellten Unterrichtsentwürfe für VR Interventionen vorgestellt und diskutiert. Begleitend zum Seminar wurden empirische Daten erhoben. Zum einen wurde das Potenzial des InteractionSuitcase (eine Sammlung virtueller Objekte) von den Studierenden bewertet. Zum anderen wurde explorativ eine qualitative Methode zur Messung interkultureller Kompetenz (Autobiography of Intercultural Encounters) getestet. Die Ergebnisse dieser explorativen Pilotstudie zeigen, dass die Interaktion mit dem InteractionSuitcase von den Studierenden als intuitiv und gewinnbringend für die Konzeption von Unterrichtskonzepten bewertet wurde. Dennoch integrierten die Studierenden die Manipulation der virtuellen Avatare häufiger im Gegensatz zum InteractionSuitcase in die Unterrichtskonzepte. Der Beitrag verfolgt das Ziel, das Potenzial von VR für inter- und transkulturelles Lernen im gymnasialen Englischunterricht zu identifizieren.

  @article{hein2023medienpaed, abstract = {Dieser Beitrag präsentiert die Ergebnisse des Seminarkonzepts und der durchgeführten Begleitforschung zum inter- und transkulturellen Lernen in Virtual Reality (VR). Im Rahmen eines Universitätsseminars entwarfen TEFL-Studierende (Teaching English as a Foreign Language) Unterrichtsstunden für fortgeschrittene Lernende des Faches Englisch der gymnasialen Oberstufe, die sich mit der Entwicklung von Empathie und der Fähigkeit zur Perspektivübernahme in interkulturellen Kommunikations- und Austauschsituationen befassten. Der Fokus des Konzepts lag dabei auf dem Verständnis und der Annahme kultureller Gemeinsamkeiten und Unterschiede. Hier werden beispielhaft zwei der erstellten Unterrichtsentwürfe für VR Interventionen vorgestellt und diskutiert. Begleitend zum Seminar wurden empirische Daten erhoben. Zum einen wurde das Potenzial des InteractionSuitcase (eine Sammlung virtueller Objekte) von den Studierenden bewertet. Zum anderen wurde explorativ eine qualitative Methode zur Messung interkultureller Kompetenz (Autobiography of Intercultural Encounters) getestet. Die Ergebnisse dieser explorativen Pilotstudie zeigen, dass die Interaktion mit dem InteractionSuitcase von den Studierenden als intuitiv und gewinnbringend für die Konzeption von Unterrichtskonzepten bewertet wurde. Dennoch integrierten die Studierenden die Manipulation der virtuellen Avatare häufiger im Gegensatz zum InteractionSuitcase in die Unterrichtskonzepte. Der Beitrag verfolgt das Ziel, das Potenzial von VR für inter- und transkulturelles Lernen im gymnasialen Englischunterricht zu identifizieren.}, author = {Hein, Rebecca and Steinbock, Jeanine and Eisenmann, Maria and Latoschik, Marc Erich and Wienrich, Carolin}, editor = {Mulders, Miriam and Buchner, Josef and Dengel, Andreas and Zender, Raphael}, journal = {MedienPädagogik: Zeitschrift für Theorie Und Praxis Der Medienbildung}, keywords = {coteach}, number = 51, pages = {191-213}, title = {Virtual Reality im modernen Englischunterricht und das Potenzial für Inter- und Transkulturelles Lernen - Eine Pilotstudie}, year = 2023 }
• DynaBench: A Benchmark Dataset for Learning Dynamical Systems from Low-Resolution Data. Dulny, Andrzej; Hotho, Andreas; Krause, Anna. In Machine Learning and Knowledge Discovery in Databases: Research Track, D. Koutra, C. Plant, M. Gomez Rodriguez, E. Baralis, F. Bonchi (eds.), pp. 438–455. Springer Nature Switzerland, Cham, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Previous work on learning physical systems from data has focused on high-resolution grid-structured measurements. However, real-world knowledge of such systems (e.g. weather data) relies on sparsely scattered measuring stations. In this paper, we introduce a novel simulated benchmark dataset, DynaBench, for learning dynamical systems directly from sparsely scattered data without prior knowledge of the equations. The dataset focuses on predicting the evolution of a dynamical system from low-resolution, unstructured measurements. We simulate six different partial differential equations covering a variety of physical systems commonly used in the literature and evaluate several machine learning models, including traditional graph neural networks and point cloud processing models, with the task of predicting the evolution of the system. The proposed benchmark dataset is expected to advance the state of art as an out-of-the-box easy-to-use tool for evaluating models in a setting where only unstructured low-resolution observations are available. The benchmark is available at https://professor-x.de/dynabench.

  @inproceedings{dulny2023dynabench, abstract = {Previous work on learning physical systems from data has focused on high-resolution grid-structured measurements. However, real-world knowledge of such systems (e.g. weather data) relies on sparsely scattered measuring stations. In this paper, we introduce a novel simulated benchmark dataset, DynaBench, for learning dynamical systems directly from sparsely scattered data without prior knowledge of the equations. The dataset focuses on predicting the evolution of a dynamical system from low-resolution, unstructured measurements. We simulate six different partial differential equations covering a variety of physical systems commonly used in the literature and evaluate several machine learning models, including traditional graph neural networks and point cloud processing models, with the task of predicting the evolution of the system. The proposed benchmark dataset is expected to advance the state of art as an out-of-the-box easy-to-use tool for evaluating models in a setting where only unstructured low-resolution observations are available. The benchmark is available at https://professor-x.de/dynabench.}, address = {Cham}, author = {Dulny, Andrzej and Hotho, Andreas and Krause, Anna}, booktitle = {Machine Learning and Knowledge Discovery in Databases: Research Track}, editor = {Koutra, Danai and Plant, Claudia and Gomez Rodriguez, Manuel and Baralis, Elena and Bonchi, Francesco}, keywords = {from:martinr}, pages = {438–455}, publisher = {Springer Nature Switzerland}, title = {DynaBench: A Benchmark Dataset for Learning Dynamical Systems from Low-Resolution Data}, year = 2023 }
• Telescope: An Automated Hybrid Forecasting Approach on a Level-Playing Field. Bauer, André; Leznik, Mark; Stenger, Michael; Leppich, Robert; Herbst, Nikolas; Kounev, Samuel; Foster, Ian. 2023.
  • [ BibTeX ]
  @misc{bauer2023telescope, author = {Bauer, André and Leznik, Mark and Stenger, Michael and Leppich, Robert and Herbst, Nikolas and Kounev, Samuel and Foster, Ian}, keywords = {t_journalmagazine}, title = {Telescope: An Automated Hybrid Forecasting Approach on a Level-Playing Field}, year = 2023 }
• Serverless Computing Revisited: Evolution, State-of-the-Art, and Performance Challenges. Kounev, Samuel. 2023.
  • [ BibTeX ]
  • [ URL ]
  @presentation{kounev2023serverless, author = {Kounev, Samuel}, keywords = {descartes}, note = {Joint Keynote at ICPE 2023 Workshops: LTB 2023 und FastContinuum 2023}, title = {Serverless Computing Revisited: Evolution, State-of-the-Art, and Performance Challenges}, year = 2023 }
• Deep Neural Network Regression for Normalized Digital Surface Model Generation with Sentinel-2 Imagery. Müller, Konstantin; Leppich, Robert; Geiß, Christian; Borst, Vanessa; Pelizari, Patrick Aravena; Kounev, Samuel. In IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, pp. 1–14. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  In recent history, normalized digital surface models (nDSMs) have been constantly gaining importance as a means to solve large-scale geographic problems. High-resolution surface models are precious, as they can provide detailed information for a specific area. However, measurements with a high resolution are time-consuming and costly. Only a few approaches exist to create high-resolution normalized digital surface models for extensive areas. This paper explores approaches to extract high-resolution nDSMs from low-resolution Sentinel-2 data, allowing us to derive large-scale models. We thereby utilize the advantages of Sentinel 2 being open access, having global coverage, and providing steady updates through a high repetition rate. Several deep-learning models are trained to overcome the gap in producing high-resolution surface maps from low-resolution input data. With U-Net as a base architecture, we extend the capabilities of our model by integrating tailored multiscale encoders with differently sized kernels in the convolution as well as conformed self-attention inside the skip connection gates. Using pixel-wise regression, our U-Net base models can achieve a mean height error of approximately two meters. Moreover, through our enhancements to the model architecture, we reduce the model error by more than seven percent.

  @article{10189905, abstract = {In recent history, normalized digital surface models (nDSMs) have been constantly gaining importance as a means to solve large-scale geographic problems. High-resolution surface models are precious, as they can provide detailed information for a specific area. However, measurements with a high resolution are time-consuming and costly. Only a few approaches exist to create high-resolution normalized digital surface models for extensive areas. This paper explores approaches to extract high-resolution nDSMs from low-resolution Sentinel-2 data, allowing us to derive large-scale models. We thereby utilize the advantages of Sentinel 2 being open access, having global coverage, and providing steady updates through a high repetition rate. Several deep-learning models are trained to overcome the gap in producing high-resolution surface maps from low-resolution input data. With U-Net as a base architecture, we extend the capabilities of our model by integrating tailored multiscale encoders with differently sized kernels in the convolution as well as conformed self-attention inside the skip connection gates. Using pixel-wise regression, our U-Net base models can achieve a mean height error of approximately two meters. Moreover, through our enhancements to the model architecture, we reduce the model error by more than seven percent.}, author = {Müller, Konstantin and Leppich, Robert and Geiß, Christian and Borst, Vanessa and Pelizari, Patrick Aravena and Kounev, Samuel}, journal = {IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing}, keywords = {t_journalmagazine}, pages = {1-14}, title = {Deep Neural Network Regression for Normalized Digital Surface Model Generation with Sentinel-2 Imagery}, year = 2023 }
• Deep Neural Network Regression for Normalized Digital Surface Model Generation with Sentinel-2 Imagery. Müller, Konstantin; Leppich, Robert; Geiß, Christian; Borst, Vanessa; Pelizari, Patrick Aravena; Kounev, Samuel. In IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, pp. 1–14. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  In recent history, normalized digital surface models (nDSMs) have been constantly gaining importance as a means to solve large-scale geographic problems. High-resolution surface models are precious, as they can provide detailed information for a specific area. However, measurements with a high resolution are time-consuming and costly. Only a few approaches exist to create high-resolution normalized digital surface models for extensive areas. This paper explores approaches to extract high-resolution nDSMs from low-resolution Sentinel-2 data, allowing us to derive large-scale models. We thereby utilize the advantages of Sentinel 2 being open access, having global coverage, and providing steady updates through a high repetition rate. Several deep-learning models are trained to overcome the gap in producing high-resolution surface maps from low-resolution input data. With U-Net as a base architecture, we extend the capabilities of our model by integrating tailored multiscale encoders with differently sized kernels in the convolution as well as conformed self-attention inside the skip connection gates. Using pixel-wise regression, our U-Net base models can achieve a mean height error of approximately two meters. Moreover, through our enhancements to the model architecture, we reduce the model error by more than seven percent.

  @article{10189905, abstract = {In recent history, normalized digital surface models (nDSMs) have been constantly gaining importance as a means to solve large-scale geographic problems. High-resolution surface models are precious, as they can provide detailed information for a specific area. However, measurements with a high resolution are time-consuming and costly. Only a few approaches exist to create high-resolution normalized digital surface models for extensive areas. This paper explores approaches to extract high-resolution nDSMs from low-resolution Sentinel-2 data, allowing us to derive large-scale models. We thereby utilize the advantages of Sentinel 2 being open access, having global coverage, and providing steady updates through a high repetition rate. Several deep-learning models are trained to overcome the gap in producing high-resolution surface maps from low-resolution input data. With U-Net as a base architecture, we extend the capabilities of our model by integrating tailored multiscale encoders with differently sized kernels in the convolution as well as conformed self-attention inside the skip connection gates. Using pixel-wise regression, our U-Net base models can achieve a mean height error of approximately two meters. Moreover, through our enhancements to the model architecture, we reduce the model error by more than seven percent.}, author = {Müller, Konstantin and Leppich, Robert and Geiß, Christian and Borst, Vanessa and Pelizari, Patrick Aravena and Kounev, Samuel}, journal = {IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing}, keywords = {t_journalmagazine}, pages = {1-14}, title = {Deep Neural Network Regression for Normalized Digital Surface Model Generation with Sentinel-2 Imagery}, year = 2023 }
• Recommendation of Secure Group Communication Schemes using Multi Objective Optimization. Prantl, Thomas; Bauer, André; Iffländer, Lukas; Krupitzer, Christian; Kounev, Samuel. In International Journal of Information Security. 2023.
  • [ BibTeX ]
  @article{PrBaIfKrKo_IJoIS_SGC_Pareto, author = {Prantl, Thomas and Bauer, André and Iffländer, Lukas and Krupitzer, Christian and Kounev, Samuel}, journal = {International Journal of Information Security}, keywords = {t_journalmagazine}, title = {Recommendation of Secure Group Communication Schemes using Multi Objective Optimization}, year = 2023 }
• Integrating Julia Code into the Unity Game Engine to Dive into Aquatic Plant Growth. Lewerentz, Anne; Manke, Nico; Schantz, David; Cabral, Juliano Sarmento; von Mammen, Sebastian. In IMET, N. Pelechano, F. Liarokapis, A. Asadipour, D. Rohmer, M. Fairén, J. Moyés (eds.), pp. 97–100. Eurographics, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{conf/imet/LewerentzMSCM23, author = {Lewerentz, Anne and Manke, Nico and Schantz, David and Cabral, Juliano Sarmento and von Mammen, Sebastian}, booktitle = {IMET}, crossref = {conf/imet/2023}, editor = {Pelechano, Nuria and Liarokapis, Fotis and Asadipour, Ali and Rohmer, Damien and Fairén, Marta and Moyés, Jordi}, keywords = {myown}, pages = {97-100}, publisher = {Eurographics}, title = {Integrating Julia Code into the Unity Game Engine to Dive into Aquatic Plant Growth.}, year = 2023 }
• Motion Learning Toolbox – A Python library for preprocessing of XR motion tracking data for machine learning applications. Rack, Christian; Schach, Lukas; Latoschik, Marc. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The Motion Learning Toolbox is a Python library designed to facilitate the preprocessing of motion tracking data in extended reality (XR) setups. It's particularly useful for researchers and engineers wanting to use XR tracking data as input for machine learning models. Originally developed for academic research targeting the identification of XR users by their motions, this toolbox includes a variety of data encoding methods that enhance machine learning model performance.

  @misc{rack2023motionlearningtoolbox, abstract = {The Motion Learning Toolbox is a Python library designed to facilitate the preprocessing of motion tracking data in extended reality (XR) setups. It's particularly useful for researchers and engineers wanting to use XR tracking data as input for machine learning models. Originally developed for academic research targeting the identification of XR users by their motions, this toolbox includes a variety of data encoding methods that enhance machine learning model performance.}, author = {Rack, Christian and Schach, Lukas and Latoschik, Marc}, howpublished = {GitHub Repository}, keywords = {schell}, title = {Motion Learning Toolbox – A Python library for preprocessing of XR motion tracking data for machine learning applications}, year = 2023 }
• How Do Employees Imagine AI They Want to Work with: A Drawing Study. Straka, Samantha; Koch, Martin Jakobus; Carolus, Astrid; Latoschik, Marc Erich; Wienrich, Carolin. In Extended Abstracts of the 2023 CHI Conference on Human Factors in Computing Systems, of CHI EA ’23. Association for Computing Machinery, Hamburg, Germany, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Perceptions about AI influence the attribution of characteristics and the interaction with AI. To find out how workers imagine an AI they would like to work with and what characteristics they attribute to it, we asked 174 working individuals to draw an AI they would like to work with, to report five adjectives they associate with their drawing and to evaluate the drawn and three other, typical AI representations (e.g. robot, smartphone) either presented as male or female. Participants mainly drew humanoid or robotic AIs. The adjectives that describe AI mainly referred to the inner characteristics, capabilities, shape, or relationship types. Regarding the evaluation, we identified four dimensions (warmth, competence, animacy, size) that can be reproduced for male and female AIs and different AI representations. This work addresses diverse conceptions of AI in the workplace and shows that human-centered AI development is necessary to address the huge design space.

  @inproceedings{10.1145/3544549.3585631, abstract = {Perceptions about AI influence the attribution of characteristics and the interaction with AI. To find out how workers imagine an AI they would like to work with and what characteristics they attribute to it, we asked 174 working individuals to draw an AI they would like to work with, to report five adjectives they associate with their drawing and to evaluate the drawn and three other, typical AI representations (e.g. robot, smartphone) either presented as male or female. Participants mainly drew humanoid or robotic AIs. The adjectives that describe AI mainly referred to the inner characteristics, capabilities, shape, or relationship types. Regarding the evaluation, we identified four dimensions (warmth, competence, animacy, size) that can be reproduced for male and female AIs and different AI representations. This work addresses diverse conceptions of AI in the workplace and shows that human-centered AI development is necessary to address the huge design space.}, address = {New York, NY, USA}, author = {Straka, Samantha and Koch, Martin Jakobus and Carolus, Astrid and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {Extended Abstracts of the 2023 CHI Conference on Human Factors in Computing Systems}, keywords = {intelligence}, publisher = {Association for Computing Machinery}, series = {CHI EA '23}, title = {How Do Employees Imagine AI They Want to Work with: A Drawing Study}, year = 2023 }
• Superfrog: Comparing Learning Outcomes and Potentials of a Worksheet, Smartphone, and Tangible AR Learning Environment. Oberdörfer, Sebastian; Elsässer, Anne; Grafe, Silke; Latoschik, Marc Erich. In 2023 9th International Conference of the Immersive Learning Research Network (iLRN). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The widespread availability of smartphones facilitates the integration of digital, augmented reality (AR), and tangible augmented reality (TAR) learning environments into the classroom. A haptic aspect can enhance the user’s overall experience during a learning process. To investigate further benefits of using TAR for educational purposes, we compare a TAR and a smartphone learning environment with a traditional worksheet counterpart in terms of learning effectiveness, emotions, motivation, and cognitive load. 64 sixth-grade students from a German high school used one of the three conditions to learn about frog anatomy. We found no significant differences in learning effectiveness and cognitive load. The TAR condition elicited significantly higher positive emotions than the worksheet, but not the smartphone condition. Both digital learning environments elicited significantly higher motivation, in contrast to the worksheet. Thus, our results suggest that smartphone and TAR learning environments are equally beneficial for enhancing learning.

  @inproceedings{oberdorfer2023comparing, abstract = {The widespread availability of smartphones facilitates the integration of digital, augmented reality (AR), and tangible augmented reality (TAR) learning environments into the classroom. A haptic aspect can enhance the user’s overall experience during a learning process. To investigate further benefits of using TAR for educational purposes, we compare a TAR and a smartphone learning environment with a traditional worksheet counterpart in terms of learning effectiveness, emotions, motivation, and cognitive load. 64 sixth-grade students from a German high school used one of the three conditions to learn about frog anatomy. We found no significant differences in learning effectiveness and cognitive load. The TAR condition elicited significantly higher positive emotions than the worksheet, but not the smartphone condition. Both digital learning environments elicited significantly higher motivation, in contrast to the worksheet. Thus, our results suggest that smartphone and TAR learning environments are equally beneficial for enhancing learning.}, author = {Oberdörfer, Sebastian and Elsässer, Anne and Grafe, Silke and Latoschik, Marc Erich}, booktitle = {2023 9th International Conference of the Immersive Learning Research Network (iLRN)}, keywords = {myown}, title = {Superfrog: Comparing Learning Outcomes and Potentials of a Worksheet, Smartphone, and Tangible AR Learning Environment}, year = 2023 }
• DFM4SFM - Dense Feature Matching for Structure from Motion. Seibt, Simon; Von Rymon Lipinski, Bartosz; Chang, Thomas; Latoschik, Marc Erich. In 2023 IEEE International Conference on Image Processing Challenges and Workshops (ICIPCW), pp. 1–5. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Structure from motion (SfM) is a fundamental task in computer vision and allows recovering the 3D structure of a stationary scene from an image set. Finding robust and accurate feature matches plays a crucial role in the early stages of SfM. So in this work, we propose a novel method for computing image correspondences based on dense feature matching (DFM) using homographic decomposition: The underlying pipeline provides refinement of existing matches through iterative rematching, detection of occlusions and extrapolation of additional matches in critical image areas between image pairs. Our main contributions are improvements of DFM specifically for SfM, resulting in global refinement and global extrapolation of image correspondences between related views. Furthermore, we propose an iterative version of the Delaunay-triangulation-based outlier detection algorithm for robust processing of repeated image patterns. Through experiments, we demonstrate that the proposed method significantlv improves the reconstruction accuracy.

  @inproceedings{10328368, abstract = {Structure from motion (SfM) is a fundamental task in computer vision and allows recovering the 3D structure of a stationary scene from an image set. Finding robust and accurate feature matches plays a crucial role in the early stages of SfM. So in this work, we propose a novel method for computing image correspondences based on dense feature matching (DFM) using homographic decomposition: The underlying pipeline provides refinement of existing matches through iterative rematching, detection of occlusions and extrapolation of additional matches in critical image areas between image pairs. Our main contributions are improvements of DFM specifically for SfM, resulting in global refinement and global extrapolation of image correspondences between related views. Furthermore, we propose an iterative version of the Delaunay-triangulation-based outlier detection algorithm for robust processing of repeated image patterns. Through experiments, we demonstrate that the proposed method significantlv improves the reconstruction accuracy.}, author = {Seibt, Simon and Von Rymon Lipinski, Bartosz and Chang, Thomas and Latoschik, Marc Erich}, booktitle = {2023 IEEE International Conference on Image Processing Challenges and Workshops (ICIPCW)}, keywords = {myown}, pages = {1-5}, title = {DFM4SFM - Dense Feature Matching for Structure from Motion}, year = 2023 }
• Ontologically Mapping Learning Objectives and Gameplay Goals. Chetitah, Mounsif; von Mammen, Sebastian. In CoG, pp. 1–4. IEEE, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{conf/cig/ChetitahM23, author = {Chetitah, Mounsif and von Mammen, Sebastian}, booktitle = {CoG}, crossref = {conf/cig/2023}, keywords = {myown}, pages = {1-4}, publisher = {IEEE}, title = {Ontologically Mapping Learning Objectives and Gameplay Goals.}, year = 2023 }
• Reality Stack I/O: A Versatile and Modular Framework for Simplifying and Unifying XR Applications and Research. Kern, Florian; Latoschik, Marc Erich. In 2023 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct), pp. 74–76. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper introduces Reality Stack I/O (RSIO), a versatile and modular framework designed to facilitate the development of extended reality (XR) applications. Researchers and developers often spend a significant amount of time enabling cross-device and cross-platform compatibility, leading to delays and increased complexity. RSIO provides the essential features to simplify and unify the development of XR applications. It enhances cross-device and cross-platform compatibility, expedites integration, and allows developers to focus more on building XR experiences rather than device integration. We offer a public Unity reference implementation with examples.

  @inproceedings{10322199, abstract = {This paper introduces Reality Stack I/O (RSIO), a versatile and modular framework designed to facilitate the development of extended reality (XR) applications. Researchers and developers often spend a significant amount of time enabling cross-device and cross-platform compatibility, leading to delays and increased complexity. RSIO provides the essential features to simplify and unify the development of XR applications. It enhances cross-device and cross-platform compatibility, expedites integration, and allows developers to focus more on building XR experiences rather than device integration. We offer a public Unity reference implementation with examples.}, author = {Kern, Florian and Latoschik, Marc Erich}, booktitle = {2023 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct)}, keywords = {vilearn}, pages = {74-76}, title = {Reality Stack I/O: A Versatile and Modular Framework for Simplifying and Unifying XR Applications and Research}, year = 2023 }
• A Systematic Evaluation of Incongruencies and Their Influence on Plausibility in Virtual Reality. Brübach, Larissa; Westermeier, Franziska; Wienrich, Carolin; Latoschik, Marc Erich. In 2023 IEEE International Symposium on Mixed and Augmented Reality (ISMAR), of ISMAR ’23, pp. 894–901. IEEE Computer Society, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Currently, there is an ongoing debate about the influencing factors of one's extended reality (XR) experience. Plausibility, congruence, and their role have recently gained more and more attention. One of the latest models to describe XR experiences, the Congruence and Plausibility model (CaP), puts plausibility and congruence right in the center. However, it is unclear what influence they have on the overall XR experience and what influences our perceived plausibility rating. In this paper, we implemented four different incongruencies within a virtual reality scene using breaks in plausibility as an analogy to breaks in presence. These manipulations were either located on the cognitive or perceptual layer of the CaP model. They were also either connected to the task at hand or not. We tested these manipulations in a virtual bowling environment to see which influence they had. Our results show that manipulations connected to the task caused a lower perceived plausibility. Additionally, cognitive manipulations seem to have a larger influence than perceptual manipulations. We were able to cause a break in plausibility with one of our incongruencies. These results show a first direction on how the influence of plausibility in XR can be systematically investigated in the future.

  @inproceedings{brubach2023systematic, abstract = {Currently, there is an ongoing debate about the influencing factors of one's extended reality (XR) experience. Plausibility, congruence, and their role have recently gained more and more attention. One of the latest models to describe XR experiences, the Congruence and Plausibility model (CaP), puts plausibility and congruence right in the center. However, it is unclear what influence they have on the overall XR experience and what influences our perceived plausibility rating. In this paper, we implemented four different incongruencies within a virtual reality scene using breaks in plausibility as an analogy to breaks in presence. These manipulations were either located on the cognitive or perceptual layer of the CaP model. They were also either connected to the task at hand or not. We tested these manipulations in a virtual bowling environment to see which influence they had. Our results show that manipulations connected to the task caused a lower perceived plausibility. Additionally, cognitive manipulations seem to have a larger influence than perceptual manipulations. We were able to cause a break in plausibility with one of our incongruencies. These results show a first direction on how the influence of plausibility in XR can be systematically investigated in the future.}, author = {Brübach, Larissa and Westermeier, Franziska and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {2023 IEEE International Symposium on Mixed and Augmented Reality (ISMAR)}, keywords = {xrhub}, pages = {894-901}, publisher = {IEEE Computer Society}, series = {ISMAR '23}, title = {A Systematic Evaluation of Incongruencies and Their Influence on Plausibility in Virtual Reality}, year = 2023 }
• Traversing the Pass: Improving the Knowledge Retention of Serious Games Using a Pedagogical Agent. Krop, Philipp; Oberdörfer, Sebastian; Latoschik, Marc Erich. In Proceedings of the 23rd ACM International Conference on Intelligent Virtual Agents. Association for Computing Machinery, Würzburg, Germany, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Machine learning is an essential aspect of modern life that many educational institutions incorporate into their curricula. Often, students struggle to grasp how neural networks learn. Teaching these concepts could be assisted with pedagogical agents and serious games, which both have proven helpful for complex topics like engineering. We present "Traversing the Pass," a serious game that utilizes a mentor-like agent to explain the underlying machine learning concepts and provides feedback. We optimized the agent’s design in a pre-study before evaluating its effectiveness compared to a text-only user interface with experts and students. Participants performed better in a second assessment two weeks later if they played the game using the agent. Although criticized as repetitive, the game created an understanding of basic machine learning concepts and achieved high flow values. Our results indicate that agents could be used to enhance the beneficial effects of serious games with improved knowledge retention.

  @inproceedings{krop2023traversing, abstract = {Machine learning is an essential aspect of modern life that many educational institutions incorporate into their curricula. Often, students struggle to grasp how neural networks learn. Teaching these concepts could be assisted with pedagogical agents and serious games, which both have proven helpful for complex topics like engineering. We present "Traversing the Pass," a serious game that utilizes a mentor-like agent to explain the underlying machine learning concepts and provides feedback. We optimized the agent’s design in a pre-study before evaluating its effectiveness compared to a text-only user interface with experts and students. Participants performed better in a second assessment two weeks later if they played the game using the agent. Although criticized as repetitive, the game created an understanding of basic machine learning concepts and achieved high flow values. Our results indicate that agents could be used to enhance the beneficial effects of serious games with improved knowledge retention.}, address = {Würzburg, Germany}, author = {Krop, Philipp and Oberdörfer, Sebastian and Latoschik, Marc Erich}, booktitle = {Proceedings of the 23rd ACM International Conference on Intelligent Virtual Agents}, keywords = {aiatwork}, publisher = {Association for Computing Machinery}, title = {Traversing the Pass: Improving the Knowledge Retention of Serious Games Using a Pedagogical Agent}, year = 2023 }
• Journey Through a Virtual Tunnel: Simulated Motion and its Effects on the Experience of Time. Landeck, Maximilian; Alvarez Igarz{á}bal, Federico; Unruh, Fabian; Habenicht, Hannah; Khoshnoud, Shiva; Wittmann, Marc; Lugrin, Jean-Luc; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 3, p. 195. Frontiers, 2023.
  • [ BibTeX ]
  • [ URL ]
  @article{landeck3journey, author = {Landeck, Maximilian and Alvarez Igarz{\'a}bal, Federico and Unruh, Fabian and Habenicht, Hannah and Khoshnoud, Shiva and Wittmann, Marc and Lugrin, Jean-Luc and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {hci-uwb}, pages = 195, publisher = {Frontiers}, title = {Journey Through a Virtual Tunnel: Simulated Motion and its Effects on the Experience of Time}, volume = 3, year = 2023 }
• Virtual reality in medical emergencies training: benefits, perceived stress, and learning success. Mühling, Tobias; Späth, Isabelle; Backhaus, Joy; Milke, Nathalie; Oberdörfer, Sebastian; Meining, Alexander; Latoschik, Marc Erich; König, Sarah. In Multimedia System. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Medical graduates lack procedural skills experience required to manage emergencies. Recent advances in virtual reality (VR) technology enable the creation of highly immersive learning environments representing easy-to-use and affordable solutions for training with simulation. However, the feasibility in compulsory teaching, possible side effects of immersion, perceived stress, and didactic benefits have to be investigated systematically. VR-based training sessions using head-mounted displays alongside a real-time dynamic physiology system were held by student assistants for small groups followed by debriefing with a tutor. In the pilot study, 36 students rated simulation sickness. In the main study, 97 students completed a virtual scenario as active participants (AP) and 130 students as observers (OBS) from the first-person perspective on a monitor. Participants completed questionnaires for evaluation purposes and exploratory factor analysis was performed on the items. The extent of simulation sickness remained low to acceptable among participants of the pilot study. In the main study, students valued the realistic environment and guided practical exercise. AP perceived the degree of immersion as well as the estimated learning success to be greater than OBS and proved to be more motivated post training. With respect to AP, the factor “sense of control” revealed a typical inverse U-shaped relationship to the scales “didactic value” and “individual learning benefit”. Summing up, curricular implementation of highly immersive VR-based training of emergencies proved feasible and found a high degree of acceptance among medical students. This study also provides insights into how different conceptions of perceived stress distinctively moderate subjective learning success.

  @article{muhling2023virtual, abstract = {Medical graduates lack procedural skills experience required to manage emergencies. Recent advances in virtual reality (VR) technology enable the creation of highly immersive learning environments representing easy-to-use and affordable solutions for training with simulation. However, the feasibility in compulsory teaching, possible side effects of immersion, perceived stress, and didactic benefits have to be investigated systematically. VR-based training sessions using head-mounted displays alongside a real-time dynamic physiology system were held by student assistants for small groups followed by debriefing with a tutor. In the pilot study, 36 students rated simulation sickness. In the main study, 97 students completed a virtual scenario as active participants (AP) and 130 students as observers (OBS) from the first-person perspective on a monitor. Participants completed questionnaires for evaluation purposes and exploratory factor analysis was performed on the items. The extent of simulation sickness remained low to acceptable among participants of the pilot study. In the main study, students valued the realistic environment and guided practical exercise. AP perceived the degree of immersion as well as the estimated learning success to be greater than OBS and proved to be more motivated post training. With respect to AP, the factor “sense of control” revealed a typical inverse U-shaped relationship to the scales “didactic value” and “individual learning benefit”. Summing up, curricular implementation of highly immersive VR-based training of emergencies proved feasible and found a high degree of acceptance among medical students. This study also provides insights into how different conceptions of perceived stress distinctively moderate subjective learning success.}, author = {Mühling, Tobias and Späth, Isabelle and Backhaus, Joy and Milke, Nathalie and Oberdörfer, Sebastian and Meining, Alexander and Latoschik, Marc Erich and König, Sarah}, journal = {Multimedia System}, keywords = {myown}, title = {Virtual reality in medical emergencies training: benefits, perceived stress, and learning success}, year = 2023 }
• Work, Trade, Learn: Developing an Immersive Serious Game for History Education. Fernes, David; Oberdörfer, Sebastian; Latoschik, Marc Erich. In 2023 9th International Conference of the Immersive Learning Research Network (iLRN). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  History education often struggles with a lack of interest from students. Serious games can help make learning about history more engaging. Students can directly experience situations of the past as well as interact and communicate with agents representing people of the respective era. This allows for situated learning. Besides using computer screens, the gameplay can also be experienced using immersive Virtual Reality (VR). VR adds an additional spatial level and can further increase the engagement as well as vividness. To investigate the benefits of using VR for serious games targeting the learning of history, we developed a serious game for desktop-3D and VR. Our serious game puts a player into the role of a medieval miller’s apprentice. Following a situated learning approach, the learner operates a mill and interacts with several other characters. These agents discuss relevant facts of the medieval life, thus enabling the construction of knowledge about the life in medieval towns. An evaluation showed that the game in general was successful in increasing the user’s knowledge about the covered topics as well as their topic interest in history. Whether the immersive VR or the simple desktop version of the application was used did not have any influence on these results. Additional feedback was gathered to improve the game further in the future.

  @inproceedings{fernes2023trade, abstract = {History education often struggles with a lack of interest from students. Serious games can help make learning about history more engaging. Students can directly experience situations of the past as well as interact and communicate with agents representing people of the respective era. This allows for situated learning. Besides using computer screens, the gameplay can also be experienced using immersive Virtual Reality (VR). VR adds an additional spatial level and can further increase the engagement as well as vividness. To investigate the benefits of using VR for serious games targeting the learning of history, we developed a serious game for desktop-3D and VR. Our serious game puts a player into the role of a medieval miller’s apprentice. Following a situated learning approach, the learner operates a mill and interacts with several other characters. These agents discuss relevant facts of the medieval life, thus enabling the construction of knowledge about the life in medieval towns. An evaluation showed that the game in general was successful in increasing the user’s knowledge about the covered topics as well as their topic interest in history. Whether the immersive VR or the simple desktop version of the application was used did not have any influence on these results. Additional feedback was gathered to improve the game further in the future.}, author = {Fernes, David and Oberdörfer, Sebastian and Latoschik, Marc Erich}, booktitle = {2023 9th International Conference of the Immersive Learning Research Network (iLRN)}, keywords = {myown}, title = {Work, Trade, Learn: Developing an Immersive Serious Game for History Education}, year = 2023 }
• An Update on the Virtual Mission Control Room. Sittner, Felix; Hartmann, Oliver; Montenegro, Sergio; Friese, Jan-Philipp; Brübach, Larissa; Latoschik, Marc Erich; Wienrich, Carolin. In . Utah State University, Logan, UT, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In 2021 we presented the Virtual Mission Control Room (VMCR) on the verge from fun educational project to testing ground for remote cooperative mission control. Since then, we successfully participated in ESA's 2022 campaign "New ideas to make XR a reality", which granted us additional funding to improve the VMCR software and conduct usability testing in cooperation with the chair of human-computer-interaction. In this paper and the corresponding poster session we give an update on the current state of the project, the new features and project structure. We explain the changes suggested by early test users and ESA to make operators feel more at home in the virtual environment. Subsequently, our project partners present their first suggestions for improvements to the VMCR as well as their plans for user testing. We conclude with lessons learned and and a look ahead into our plans for the future of the project.

  @proceedings{sittner2023update, abstract = {In 2021 we presented the Virtual Mission Control Room (VMCR) on the verge from fun educational project to testing ground for remote cooperative mission control. Since then, we successfully participated in ESA's 2022 campaign "New ideas to make XR a reality", which granted us additional funding to improve the VMCR software and conduct usability testing in cooperation with the chair of human-computer-interaction. In this paper and the corresponding poster session we give an update on the current state of the project, the new features and project structure. We explain the changes suggested by early test users and ESA to make operators feel more at home in the virtual environment. Subsequently, our project partners present their first suggestions for improvements to the VMCR as well as their plans for user testing. We conclude with lessons learned and and a look ahead into our plans for the future of the project.}, address = {Utah State University, Logan, UT}, author = {Sittner, Felix and Hartmann, Oliver and Montenegro, Sergio and Friese, Jan-Philipp and Brübach, Larissa and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {2023 Small Satellite Conference}, howpublished = {Technical Poster Session 5}, keywords = {xrhub}, title = {An Update on the Virtual Mission Control Room}, year = 2023 }
• Visual Indicators Representing Avatars’ Authenticity in Social Virtual Reality and Their Impacts on Perceived Trustworthiness. Lin, Jinghuai; Cronjé, Johrine; Wienrich, Carolin; Pauli, Paul; Latoschik, Marc Erich. In IEEE Transactions on Visualization and Computer Graphics (TVCG). 2023.
  • [ BibTeX ]
  • [ URL ]
  @article{lin2023visual, author = {Lin, Jinghuai and Cronjé, Johrine and Wienrich, Carolin and Pauli, Paul and Latoschik, Marc Erich}, journal = {IEEE Transactions on Visualization and Computer Graphics (TVCG)}, keywords = {prima}, title = {Visual Indicators Representing Avatars' Authenticity in Social Virtual Reality and Their Impacts on Perceived Trustworthiness}, year = 2023 }
• A Subjective Quality Assessment of Temporally Reprojected Specular Reflections in Virtual Reality. Mišiak, Martin; Fuhrmann, Arnulph; Latoschik, Marc Erich. In 2023 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW), pp. 825–826. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Temporal reprojection is a popular method for mitigating sampling artifacts from a variety of sources. This work investigates it's impact on the subjective quality of specular reflections in Virtual Reality(VR). Our results show that temporal reprojection is highly effective at improving the visual comfort of specular materials, especially at low sample counts. A slightly diminished effect could also be observed in improving the subjective accuracy of the resulting reflection.

  @inproceedings{misiak2023subjective, abstract = {Temporal reprojection is a popular method for mitigating sampling artifacts from a variety of sources. This work investigates it's impact on the subjective quality of specular reflections in Virtual Reality(VR). Our results show that temporal reprojection is highly effective at improving the visual comfort of specular materials, especially at low sample counts. A slightly diminished effect could also be observed in improving the subjective accuracy of the resulting reflection.}, author = {Mišiak, Martin and Fuhrmann, Arnulph and Latoschik, Marc Erich}, booktitle = {2023 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {myown}, pages = {825-826}, title = {A Subjective Quality Assessment of Temporally Reprojected Specular Reflections in Virtual Reality}, year = 2023 }
• Searching for the Ground Truth: Assessing the Similarity of Benchmarking Runs. Bauer, Andr{é}; Straesser, Martin; Leznik, Mark; Beierlieb, Lukas; Hadry, Marius; Hudson, Nathaniel; Chard, Kyle; Kounev, Samuel; Foster, Ian. In Companion of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23 Companion, pp. 95–99. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Stable and repeatable measurements are essential for comparing the performance of different systems or applications, and benchmarks are used to ensure accuracy and replication. However, if the corresponding measurements are not stable and repeatable, wrong conclusions can be drawn. To facilitate the task of determining whether the measurements are similar, we used a data set of 586 micro-benchmarks to (i) analyze the data set itself, (ii) examine our previous approach, and (iii) propose and evaluate a heuristic. To evaluate the different approaches, we perform a peer review to assess the dissimilarity of the benchmark runs. Our results show that this task is challenging even for humans and that our heuristic exhibits a sensitivity of 92%.

  @inproceedings{10.1145/3578245.3584693, abstract = {Stable and repeatable measurements are essential for comparing the performance of different systems or applications, and benchmarks are used to ensure accuracy and replication. However, if the corresponding measurements are not stable and repeatable, wrong conclusions can be drawn. To facilitate the task of determining whether the measurements are similar, we used a data set of 586 micro-benchmarks to (i) analyze the data set itself, (ii) examine our previous approach, and (iii) propose and evaluate a heuristic. To evaluate the different approaches, we perform a peer review to assess the dissimilarity of the benchmark runs. Our results show that this task is challenging even for humans and that our heuristic exhibits a sensitivity of 92%.}, address = {New York, NY, USA}, author = {Bauer, Andr\'{e} and Straesser, Martin and Leznik, Mark and Beierlieb, Lukas and Hadry, Marius and Hudson, Nathaniel and Chard, Kyle and Kounev, Samuel and Foster, Ian}, booktitle = {Companion of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {distance_measures}, pages = {95–99}, publisher = {Association for Computing Machinery}, series = {ICPE '23 Companion}, title = {Searching for the Ground Truth: Assessing the Similarity of Benchmarking Runs}, year = 2023 }
• Long-Term Effects of Perceived Friendship with Intelligent Voice Assistants on Usage Behavior, User Experience, and Social Perceptions. Wienrich, Carolin; Carolus, Astrid; Markus, André; Augustin, Yannik; Pfister, Jan; Hotho, Andreas. In Computers, 12(4). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Social patterns and roles can develop when users talk to intelligent voice assistants (IVAs) daily. The current study investigates whether users assign different roles to devices and how this affects their usage behavior, user experience, and social perceptions. Since social roles take time to establish, we equipped 106 participants with Alexa or Google assistants and some smart home devices and observed their interactions for nine months. We analyzed diverse subjective (questionnaire) and objective data (interaction data). By combining social science and data science analyses, we identified two distinct clusters—users who assigned a friendship role to IVAs over time and users who did not. Interestingly, these clusters exhibited significant differences in their usage behavior, user experience, and social perceptions of the devices. For example, participants who assigned a role to IVAs attributed more friendship to them used them more frequently, reported more enjoyment during interactions, and perceived more empathy for IVAs. In addition, these users had distinct personal requirements, for example, they reported more loneliness. This study provides valuable insights into the role-specific effects and consequences of voice assistants. Recent developments in conversational language models such as ChatGPT suggest that the findings of this study could make an important contribution to the design of dialogic human–AI interactions.

  @article{wienrich2023longterm, abstract = {Social patterns and roles can develop when users talk to intelligent voice assistants (IVAs) daily. The current study investigates whether users assign different roles to devices and how this affects their usage behavior, user experience, and social perceptions. Since social roles take time to establish, we equipped 106 participants with Alexa or Google assistants and some smart home devices and observed their interactions for nine months. We analyzed diverse subjective (questionnaire) and objective data (interaction data). By combining social science and data science analyses, we identified two distinct clusters—users who assigned a friendship role to IVAs over time and users who did not. Interestingly, these clusters exhibited significant differences in their usage behavior, user experience, and social perceptions of the devices. For example, participants who assigned a role to IVAs attributed more friendship to them used them more frequently, reported more enjoyment during interactions, and perceived more empathy for IVAs. In addition, these users had distinct personal requirements, for example, they reported more loneliness. This study provides valuable insights into the role-specific effects and consequences of voice assistants. Recent developments in conversational language models such as ChatGPT suggest that the findings of this study could make an important contribution to the design of dialogic human–AI interactions.}, author = {Wienrich, Carolin and Carolus, Astrid and Markus, André and Augustin, Yannik and Pfister, Jan and Hotho, Andreas}, journal = {Computers}, keywords = {from:janpf}, number = 4, title = {Long-Term Effects of Perceived Friendship with Intelligent Voice Assistants on Usage Behavior, User Experience, and Social Perceptions}, volume = 12, year = 2023 }
• Outside-Obstacle Representations with All Vertices on the Outer Face. Firman, Oksana; Kindermann, Philipp; Klawitter, Jonathan; Klemz, Boris; Klesen, Felix; Wolff, Alexander. In Proc. 30th Int. Symp. Graph Drawing \& Network Vis. (GD’22), Vol. 13764 of Lecture Notes in Computer Science, P. Angelini, R. von Hanxleden (eds.), pp. 432–440. Springer-Verlag, 2023.
  • [ BibTeX ]
  @inproceedings{fkkkkw-ooravof-GD22, author = {Firman, Oksana and Kindermann, Philipp and Klawitter, Jonathan and Klemz, Boris and Klesen, Felix and Wolff, Alexander}, booktitle = {Proc. 30th Int. Symp. Graph Drawing \& Network Vis. (GD'22)}, editor = {Angelini, Patrizio and von Hanxleden, Reinhard}, keywords = {myown}, pages = {432–440}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Outside-Obstacle Representations with All Vertices on the Outer Face}, volume = 13764, year = 2023 }
• The Computational Complexity of the {ChordLink} Model. Kindermann, Philipp; Sauer, Jan; Wolff, Alexander. In Journal of Graph Algorithms \& Applications, 27(9), pp. 759–767. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  In order to visualize well-clustered graphs with many intra-cluster but few inter-cluster edges, hybrid approaches have been proposed. For example, ChordLink draws the clusters as chord diagrams and embeds these into a node-link diagram that represents the overall structure of the clustered graph. The ChordLink approach consists of four steps; node replication, node permutation, node merging, and chord insertion. In this paper, we focus on the optimization problems defined by two of these steps. We show that the decision version of the problem defined by node permutation is NP-complete and present an efficient algorithm for a special case. For chord insertion, we show that it is NP-complete to decide whether a crossing-free placement of the chords exists. Moreover, it is APX-hard to minimize the number of crossings among the chords. Our results answer an open question posed by Angori, Didimo, Montecchiani, Pagliuca, and Tappini, who introduced ChordLink [TVCG 2021].

  @article{ksw-cccm-JGAA23, abstract = {In order to visualize well-clustered graphs with many intra-cluster but few inter-cluster edges, hybrid approaches have been proposed. For example, ChordLink draws the clusters as chord diagrams and embeds these into a node-link diagram that represents the overall structure of the clustered graph. The ChordLink approach consists of four steps; node replication, node permutation, node merging, and chord insertion. In this paper, we focus on the optimization problems defined by two of these steps. We show that the decision version of the problem defined by node permutation is NP-complete and present an efficient algorithm for a special case. For chord insertion, we show that it is NP-complete to decide whether a crossing-free placement of the chords exists. Moreover, it is APX-hard to minimize the number of crossings among the chords. Our results answer an open question posed by Angori, Didimo, Montecchiani, Pagliuca, and Tappini, who introduced ChordLink [TVCG 2021].}, author = {Kindermann, Philipp and Sauer, Jan and Wolff, Alexander}, journal = {Journal of Graph Algorithms \& Applications}, keywords = {APX-hard}, number = 9, pages = {759–767}, title = {The Computational Complexity of the {ChordLink} Model}, volume = 27, year = 2023 }
• Are Embodied Avatars Harmful to our Self-Experience? The Impact of Virtual Embodiment on Body Awareness. Döllinger, Nina; Wolf, Erik; Botsch, Mario; Latoschik, Marc Erich; Wienrich, Carolin. In 2023 CHI Conference on Human Factors in Computing Systems, pp. 1–14. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Virtual Reality (VR) allows us to replace our visible body with a virtual self-representation (avatar) and to explore its effects on our body perception. While the feeling of owning and controlling a virtual body is widely researched, how VR affects the awareness of internal body signals (body awareness) remains open. Forty participants performed moving meditation tasks in reality and VR, either facing their mirror image or not. Both the virtual environment and avatars photorealistically matched their real counterparts. We found a negative effect of VR on body awareness, mediated by feeling embodied in and changed by the avatar. Further, we revealed a negative effect of a mirror on body awareness. Our results indicate that assessing body awareness should be essential in evaluating VR designs and avatar embodiment aiming at mental health, as even a scenario as close to reality as possible can distract users from their internal body signals.

  @inproceedings{dollinger2023embodied, abstract = {Virtual Reality (VR) allows us to replace our visible body with a virtual self-representation (avatar) and to explore its effects on our body perception. While the feeling of owning and controlling a virtual body is widely researched, how VR affects the awareness of internal body signals (body awareness) remains open. Forty participants performed moving meditation tasks in reality and VR, either facing their mirror image or not. Both the virtual environment and avatars photorealistically matched their real counterparts. We found a negative effect of VR on body awareness, mediated by feeling embodied in and changed by the avatar. Further, we revealed a negative effect of a mirror on body awareness. Our results indicate that assessing body awareness should be essential in evaluating VR designs and avatar embodiment aiming at mental health, as even a scenario as close to reality as possible can distract users from their internal body signals.}, author = {Döllinger, Nina and Wolf, Erik and Botsch, Mario and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {2023 CHI Conference on Human Factors in Computing Systems}, keywords = {vitras}, note = {Honorable Mention 🏆}, pages = {1-14}, title = {Are Embodied Avatars Harmful to our Self-Experience? The Impact of Virtual Embodiment on Body Awareness}, year = 2023 }
• Autoscaler Evaluation and Configuration: A Practitioner’s Guideline. Straesser, Martin; Eismann, Simon; von Kistowski, J{ó}akim; Bauer, Andr{é}; Kounev, Samuel. In Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23, pp. 31–41. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Autoscalers are indispensable parts of modern cloud deployments and determine the service quality and cost of a cloud application in dynamic workloads. The configuration of an autoscaler strongly influences its performance and is also one of the biggest challenges and showstoppers for the practical applicability of many research autoscalers. Many proposed cloud experiment methodologies can only be partially applied in practice, and many autoscaling papers use custom evaluation methods and metrics. This paper presents a practical guideline for obtaining meaningful and interpretable results on autoscaler performance with reasonable overhead. We provide step-by-step instructions for defining realistic usage behaviors and traffic patterns. We divide the analysis of autoscaler performance into a qualitative antipattern-based analysis and a quantitative analysis. To demonstrate the applicability of our guideline, we conduct several experiments with a microservice of our industry partner in a realistic test environment.

  @inproceedings{straesser2023guideline, abstract = {Autoscalers are indispensable parts of modern cloud deployments and determine the service quality and cost of a cloud application in dynamic workloads. The configuration of an autoscaler strongly influences its performance and is also one of the biggest challenges and showstoppers for the practical applicability of many research autoscalers. Many proposed cloud experiment methodologies can only be partially applied in practice, and many autoscaling papers use custom evaluation methods and metrics. This paper presents a practical guideline for obtaining meaningful and interpretable results on autoscaler performance with reasonable overhead. We provide step-by-step instructions for defining realistic usage behaviors and traffic patterns. We divide the analysis of autoscaler performance into a qualitative antipattern-based analysis and a quantitative analysis. To demonstrate the applicability of our guideline, we conduct several experiments with a microservice of our industry partner in a realistic test environment.}, address = {New York, NY, USA}, author = {Straesser, Martin and Eismann, Simon and von Kistowski, J\'{o}akim and Bauer, Andr\'{e} and Kounev, Samuel}, booktitle = {Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {methodology}, pages = {31-41}, publisher = {Association for Computing Machinery}, series = {ICPE '23}, title = {Autoscaler Evaluation and Configuration: A Practitioner's Guideline}, year = 2023 }
• Power to the Applications: The Vision of Continuous Decentralized Autoscaling. Straesser, Martin; Geißler, Stefan; Hoßfeld, Tobias; Kounev, Samuel. In 2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing Workshops (CCGridW), pp. 281–283. IEEE, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{straesser2023decentral, author = {Straesser, Martin and Geißler, Stefan and Hoßfeld, Tobias and Kounev, Samuel}, booktitle = {2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing Workshops (CCGridW)}, keywords = {t_poster}, pages = {281-283}, publisher = {IEEE}, title = {Power to the Applications: The Vision of Continuous Decentralized Autoscaling}, year = 2023 }
• An Empirical Study of Container Image Configurations and Their Impact on Start Times. Straesser, Martin; Bauer, André; Leppich, Robert; Herbst, Nikolas; Chard, Kyle; Foster, Ian; Kounev, Samuel. In 2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing (CCGrid), pp. 94–105. IEEE, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{straesser2023starttime, author = {Straesser, Martin and Bauer, André and Leppich, Robert and Herbst, Nikolas and Chard, Kyle and Foster, Ian and Kounev, Samuel}, booktitle = {2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing (CCGrid)}, keywords = {empirical_study}, pages = {94-105}, publisher = {IEEE}, title = {An Empirical Study of Container Image Configurations and Their Impact on Start Times}, year = 2023 }
• Performance Impact Analysis of Homomorphic Encryption: A Case Study Using Linear Regression as an Example. Prantl, Thomas; Engel, Simon; Horn, Lukas; Kaiser, Dennis; Iffländer, Lukas; Bauer, André; Krupitzer, Christian; Kounev, Samuel. In Information Security Practice and Experience, W. Meng, Z. Yan, V. Piuri (eds.), pp. 284–298. Springer Nature Singapore, Singapore, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  In recent years, the trend has increasingly been to store and process data in the cloud. However, this is based on the premise that cloud providers treat the data in a trustworthy manner. One way of using the data in the cloud without the provider having access to it is homomorphic encryption. However, since this encryption has only recently become practicable, analysis of its for practical applications is still in its infancy. Therefore, we investigate the performance of homomorphic encryption using a real-world application, namely linear regression. Our main finding is that although the homomorphic computation of linear regression is in the range of minutes and thus slower than in the non-homomorphic case, linear regression can be computed homomorphic and is therefore suitable for use cases where data security is the top priority.

  @inproceedings{PrEnHoDeIfBaKrKo_ISPEC_De_Bello, abstract = {In recent years, the trend has increasingly been to store and process data in the cloud. However, this is based on the premise that cloud providers treat the data in a trustworthy manner. One way of using the data in the cloud without the provider having access to it is homomorphic encryption. However, since this encryption has only recently become practicable, analysis of its for practical applications is still in its infancy. Therefore, we investigate the performance of homomorphic encryption using a real-world application, namely linear regression. Our main finding is that although the homomorphic computation of linear regression is in the range of minutes and thus slower than in the non-homomorphic case, linear regression can be computed homomorphic and is therefore suitable for use cases where data security is the top priority.}, address = {Singapore}, author = {Prantl, Thomas and Engel, Simon and Horn, Lukas and Kaiser, Dennis and Iffl\"ander, Lukas and Bauer, Andr\'e and Krupitzer, Christian and Kounev, Samuel}, booktitle = {Information Security Practice and Experience}, editor = {Meng, Weizhi and Yan, Zheng and Piuri, Vincenzo}, keywords = {t_proceedings}, pages = {284–298}, publisher = {Springer Nature Singapore}, title = {Performance Impact Analysis of Homomorphic Encryption: A Case Study Using Linear Regression as an Example}, year = 2023 }
• Towards a Cryptography Encyclopedia: A Survey on Attribute-Based Encryption. Prantl, Thomas; Zeck, Timo; Horn, Lukas; Iffländer, Lukas; Bauer, André; Dmitrienko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In Journal of Surveillance, Security and Safety. 2023.
  • [ BibTeX ]
  @article{PrZeHoIfBaDmKrKo_ABESurvey, author = {Prantl, Thomas and Zeck, Timo and Horn, Lukas and Iffl\"ander, Lukas and Bauer, Andr\'e and Dmitrienko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, journal = {Journal of Surveillance, Security and Safety}, keywords = {t_journalmagazine}, title = {Towards a Cryptography Encyclopedia: A Survey on Attribute-Based Encryption}, year = 2023 }
• Kubernetes-in-the-Loop: Enriching Microservice Simulation Through Authentic Container Orchestration. Straesser, Martin; Haas, Patrick; Frank, Sebastian; Hakamian, Alireza; Van Hoorn, André; Kounev, Samuel. In Performance Evaluation Methodologies and Tools. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Microservices deployed and managed by container orchestration frameworks like Kubernetes are the bases of modern cloud applications. In microservice performance modeling and prediction, simulations provide a lightweight alternative to experimental analysis, which requires dedicated infrastructure and a laborious setup. However, existing simulators cannot run realistic scenarios, as performance-critical orchestration mechanisms (like scheduling or autoscaling) are manually modeled and can consequently not be represented in their full complexity and configuration space. This work combines a state-of-the-art simulation for microservice performance with Kubernetes container orchestration. Hereby, we include the original implementation of Kubernetes artifacts enabling realistic scenarios and testing of orchestration policies with low overhead. In two experiments with Kubernetes' kube-scheduler and cluster-autoscaler, we demonstrate that our framework can correctly handle different configurations of these orchestration mechanisms boosting both the simulation's use cases and authenticity.

  @inproceedings{straesser2023kubernetesintheloop, abstract = {Microservices deployed and managed by container orchestration frameworks like Kubernetes are the bases of modern cloud applications. In microservice performance modeling and prediction, simulations provide a lightweight alternative to experimental analysis, which requires dedicated infrastructure and a laborious setup. However, existing simulators cannot run realistic scenarios, as performance-critical orchestration mechanisms (like scheduling or autoscaling) are manually modeled and can consequently not be represented in their full complexity and configuration space. This work combines a state-of-the-art simulation for microservice performance with Kubernetes container orchestration. Hereby, we include the original implementation of Kubernetes artifacts enabling realistic scenarios and testing of orchestration policies with low overhead. In two experiments with Kubernetes' kube-scheduler and cluster-autoscaler, we demonstrate that our framework can correctly handle different configurations of these orchestration mechanisms boosting both the simulation's use cases and authenticity.}, author = {Straesser, Martin and Haas, Patrick and Frank, Sebastian and Hakamian, Alireza and Van Hoorn, André and Kounev, Samuel}, booktitle = {Performance Evaluation Methodologies and Tools}, keywords = {discrete_event_simulation}, note = {In print.}, title = {Kubernetes-in-the-Loop: Enriching Microservice Simulation Through Authentic Container Orchestration}, year = 2023 }
• Higher-Order DeepTrails: Unified Approach to *Trails. Koopmann, Tobias; Pfister, Jan; Markus, André; Carolus, Astrid; Wienrich, Carolin; Hotho, Andreas. In Proceedings of the {LWDA} 2023 Workshops: FGWM, FGKD, and FGDB, Marburg (Germany), Oktober 9-11th, 2023, of {CEUR} Workshop Proceedings, M. Leyer, J. Wichmann (eds.). CEUR-WS.org, 2023.
  • [ BibTeX ]
  @inproceedings{koopmann2023higherorder, author = {Koopmann, Tobias and Pfister, Jan and Markus, André and Carolus, Astrid and Wienrich, Carolin and Hotho, Andreas}, booktitle = {Proceedings of the {LWDA} 2023 Workshops: FGWM, FGKD, and FGDB, Marburg (Germany), Oktober 9-11th, 2023}, editor = {Leyer, Michael and Wichmann, Johannes}, keywords = {from:martinr}, publisher = {CEUR-WS.org}, series = {{CEUR} Workshop Proceedings}, title = {Higher-Order DeepTrails: Unified Approach to *Trails}, year = 2023 }
• A literature review of IoT and CPS—What they are, and what they are not. Lesch, Veronika; Z{ü}fle, Marwin; Bauer, Andr{é}; Iffl{ä}nder, Lukas; Krupitzer, Christian; Kounev, Samuel. In Journal of Systems and Software, p. 111631. Elsevier, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Today, we are confronted with many concepts such as Cyber–Physical-Systems (CPS), Internet of Things (IoT), Industry 4.0, Industrial Internet, Ubiquitous Computing, Pervasive Computing and many more. Some researchers use all of these terms interchangeably, while others interpret them in ways that contradict each other. The inconsistent and interchangeable usage of these terms creates the impression that authors abuse them as buzzwords to attract attention. Hence, the question arises: Is the existence of all these terms justified? In this paper, we first look at the origin of the terms. Then, we focus on Internet of Things (IoT) and Cyber-Physical-Systems (CPS) as those terms are more often used as the others and further often seen as underlying technologies. We presentthe results of a literature review, including academic, industry and gray literature, with the objective to identify and discuss several clusters of similar statements on both terms. Building on this, we present definitions for IoT and CPS that reflect the core intuition of the terms as found in the literature review while providing a clear demarcation of the two terms. Then, we illustrate the applicability of our findings on several use cases. Finally, we discuss the relation to the other topics closely related to adaptive systems, namely Industry 4.0, Industrial Internet, Ubiquitous Computing, and Pervasive Computing.

  @article{lesch2023literature, abstract = {Today, we are confronted with many concepts such as Cyber–Physical-Systems (CPS), Internet of Things (IoT), Industry 4.0, Industrial Internet, Ubiquitous Computing, Pervasive Computing and many more. Some researchers use all of these terms interchangeably, while others interpret them in ways that contradict each other. The inconsistent and interchangeable usage of these terms creates the impression that authors abuse them as buzzwords to attract attention. Hence, the question arises: Is the existence of all these terms justified? In this paper, we first look at the origin of the terms. Then, we focus on Internet of Things (IoT) and Cyber-Physical-Systems (CPS) as those terms are more often used as the others and further often seen as underlying technologies. We presentthe results of a literature review, including academic, industry and gray literature, with the objective to identify and discuss several clusters of similar statements on both terms. Building on this, we present definitions for IoT and CPS that reflect the core intuition of the terms as found in the literature review while providing a clear demarcation of the two terms. Then, we illustrate the applicability of our findings on several use cases. Finally, we discuss the relation to the other topics closely related to adaptive systems, namely Industry 4.0, Industrial Internet, Ubiquitous Computing, and Pervasive Computing.}, author = {Lesch, Veronika and Z{\"u}fle, Marwin and Bauer, Andr{\'e} and Iffl{\"a}nder, Lukas and Krupitzer, Christian and Kounev, Samuel}, journal = {Journal of Systems and Software}, keywords = {t_journalmagazine}, pages = 111631, publisher = {Elsevier}, title = {A literature review of IoT and CPS—What they are, and what they are not}, year = 2023 }
• Challenges and Future Directions in Efficiency Benchmarking (Vision Paper). Meissner, Maximilian; Lange, Klaus-Dieter; Sharma, Sanjay; Arnold, Jeremy; Cragin, Aaron; Galizia, Patrick; Petrich, Mike; Zhang, Bin; Kounev, Samuel. In Companion of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23 Companion, pp. 51–55. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  SPEC benchmarks are crucial contributors behind the improvement of server efficiency since 2007, given their role in making the power consumption and efficiency of servers transparent for government regulators, customers, and the manufacturers themselves.As the IT landscape experiences radical transformations, efficiency benchmarks need to be updated accordingly to generate results relevant to government regulators, manufacturers, and customers. In this paper, we outline current challenges efficiency benchmark developers are tackling and highlight recent technological developments the next generation of efficiency benchmarks should take into account.

  @inproceedings{10.1145/3578245.3585034, abstract = {SPEC benchmarks are crucial contributors behind the improvement of server efficiency since 2007, given their role in making the power consumption and efficiency of servers transparent for government regulators, customers, and the manufacturers themselves.As the IT landscape experiences radical transformations, efficiency benchmarks need to be updated accordingly to generate results relevant to government regulators, manufacturers, and customers. In this paper, we outline current challenges efficiency benchmark developers are tackling and highlight recent technological developments the next generation of efficiency benchmarks should take into account.}, address = {New York, NY, USA}, author = {Meissner, Maximilian and Lange, Klaus-Dieter and Sharma, Sanjay and Arnold, Jeremy and Cragin, Aaron and Galizia, Patrick and Petrich, Mike and Zhang, Bin and Kounev, Samuel}, booktitle = {Companion of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {descartes}, pages = {51–55}, publisher = {Association for Computing Machinery}, series = {ICPE '23 Companion}, title = {Challenges and Future Directions in Efficiency Benchmarking (Vision Paper)}, year = 2023 }
• Performance Engineering of Serverless Applications and Platforms. Technical Report (PhD dissertation), . Eismann, Simon. PhD dissertation. Universit{ä}t W{ü}rzburg, 2023.
  • [ BibTeX ]
  @phdthesis{Eismann2023, author = {Eismann, Simon}, keywords = {descartes}, school = {Universit{\"a}t W{\"u}rzburg}, title = {Performance Engineering of Serverless Applications and Platforms}, type = {doctoralthesis}, year = 2023 }
• Case-Based Sample Generation using Multi-Armed Bandits. Korger, Andreas; Baumeister, Joachim. In ICCBR 2023: International Conference on Case-Based Reasoning. Springer, 2023.
  • [ BibTeX ]
  @inproceedings{KB:ICCBR:2023, author = {Korger, Andreas and Baumeister, Joachim}, booktitle = {ICCBR 2023: International Conference on Case-Based Reasoning}, keywords = {cbr}, publisher = {Springer}, title = {Case-Based Sample Generation using Multi-Armed Bandits}, year = 2023 }
• TaylorPDENet: Learning PDEs from non-grid Data. Heinisch, Paul; Dulny, Andrzej; Krause, Anna; Hotho, Andreas. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Modeling data obtained from dynamical systems has gained attention in recent years as a challenging task for machine learning models. Previous approaches assume the measurements to be distributed on a grid. However, for real-world applications like weather prediction, the observations are taken from arbitrary locations within the spatial domain. In this paper, we propose TaylorPDENet - a novel machine learning method that is designed to overcome this challenge. Our algorithm uses the multidimensional Taylor expansion of a dynamical system at each observation point to estimate the spatial derivatives to perform predictions. TaylorPDENet is able to accomplish two objectives simultaneously: accurately forecast the evolution of a complex dynamical system and explicitly reconstruct the underlying differential equation describing the system. We evaluate our model on a variety of advection-diffusion equations with different parameters and show that it performs similarly to equivalent approaches on grid-structured data while being able to process unstructured data as well.

  @misc{heinisch2023taylorpdenet, abstract = {Modeling data obtained from dynamical systems has gained attention in recent years as a challenging task for machine learning models. Previous approaches assume the measurements to be distributed on a grid. However, for real-world applications like weather prediction, the observations are taken from arbitrary locations within the spatial domain. In this paper, we propose TaylorPDENet - a novel machine learning method that is designed to overcome this challenge. Our algorithm uses the multidimensional Taylor expansion of a dynamical system at each observation point to estimate the spatial derivatives to perform predictions. TaylorPDENet is able to accomplish two objectives simultaneously: accurately forecast the evolution of a complex dynamical system and explicitly reconstruct the underlying differential equation describing the system. We evaluate our model on a variety of advection-diffusion equations with different parameters and show that it performs similarly to equivalent approaches on grid-structured data while being able to process unstructured data as well.}, author = {Heinisch, Paul and Dulny, Andrzej and Krause, Anna and Hotho, Andreas}, keywords = {from:martinr}, note = {cite arxiv:2306.14511}, title = {TaylorPDENet: Learning PDEs from non-grid Data}, year = 2023 }
• Case-Based Sample Generation using Multi-Armed Bandits. Korger, Andreas; Baumeister, Joachim. In Lernen, Wissen, Daten, Analysen (LWDA), pp. 282–297. 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{korger2023casebased, author = {Korger, Andreas and Baumeister, Joachim}, booktitle = {Lernen, Wissen, Daten, Analysen (LWDA)}, keywords = {evaluation}, pages = {282-297}, title = {Case-Based Sample Generation using Multi-Armed Bandits}, year = 2023 }
• Mind the Gap: Edge Facility Location Problems in Theory and Practice. Beck, Moritz; Spoerhase, Joachim; Storandt, Sabine. In Proc. 9th International Conference on Algorithms and Discrete Applied Mathematics (CALDAM’23), Vol. 13947, pp. 321–334. 2023.
  • [ BibTeX ]
  @inproceedings{beck-etal23:edge-fac-loc, author = {Beck, Moritz and Spoerhase, Joachim and Storandt, Sabine}, booktitle = {Proc. 9th International Conference on Algorithms and Discrete Applied Mathematics (CALDAM'23)}, keywords = {facility}, pages = {321–334}, title = {Mind the Gap: Edge Facility Location Problems in Theory and Practice}, volume = 13947, year = 2023 }
• Auswirkung von (virtuellen) Körperbildübungen auf das Ernährungsverhalten von Personen mit Adipositas – Ergebnisse der ViTraS-Pilotstudie. Gemesi, Kathrin; Döllinger, Nina; Weinberger, Natascha-Alexandra; Wolf, Erik; Mal, David; Wienrich, Carolin; Luck-Sikorski, Claudia; Bader, Erik; Holzapfel, Christina. In Adipositas - Ursachen, Folgeerkrankungen, Therapie, 17(03), pp. S10–05. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Einleitung Die multimodale Adipositastherapie besteht aus Elementen der Ernährung, der Bewegung und des Verhaltens bzw. des Körperbildes. Anwendungen der virtuellen Realität (VR) können das Methodenspektrum der Körperbildtherapie erweitern. Im vorliegenden Projekt wurde ein VR-System (bestehend aus einem Avatar und einem virtuellen Spiegel) zur Verbesserung von Körperwahrnehmung und Körperbild bei Personen mit Adipositas entwickelt. Methoden Im Rahmen der multizentrischen kontrollierten ViTraS-Pilotstudie (Registrierungsnummer: DRKS00027906) wurden bei Personen mit Adipositas virtuelle bzw. traditionelle Körperbildübungen angewendet. Es fanden drei Sitzungen im Abstand von ca. zwei Wochen statt. Über die Zeit wurden anthropometrische Daten sowie Daten zum Ernährungsverhalten (Dutch Eating Behavior Questionnaire (DEBQ) und eine Auswahl von Fragen des The Eating Motivation Survey (TEMS)) erfasst. In zwei Sitzungen wurden Körperbildübungen virtuell (VR-Gruppe) oder nicht-virtuell (Kontrollgruppe) durchgeführt. Eine online Follow-Up-Datenerhebung fand 6 Wochen nach der letzten Sitzung statt. Ergebnisse Insgesamt wurden 66 Personen (VR-Gruppe: 31, Kontrollgruppe: 35) in die Studie eingeschlossen. Die Personen waren zu 79% (52/66) weiblich, 45±13 Jahre alt und der mittlere BMI lag bei 37±4 kg/m2. Die Auswertung des DEBQ Fragebogens hat ergeben, dass in der VR-Gruppe gezügeltes Essverhalten von Anfang bis Ende der Studie signifikant (p<0,05) zugenommen hat. Die Ergebnisse der Auswahl von Fragen des TEMS hat keine signifikanten (p≥0,05) Unterschiede innerhalb oder zwischen den Gruppen ergeben. Schlussfolgerung Die Studie hat ergeben, dass die Durchführung von virtuellen Körperbildübungen eine Auswirkung auf das Ernährungsverhalten von Personen mit Adipositas haben kann.

  @article{gemesi2023auswirkung, abstract = {Einleitung Die multimodale Adipositastherapie besteht aus Elementen der Ernährung, der Bewegung und des Verhaltens bzw. des Körperbildes. Anwendungen der virtuellen Realität (VR) können das Methodenspektrum der Körperbildtherapie erweitern. Im vorliegenden Projekt wurde ein VR-System (bestehend aus einem Avatar und einem virtuellen Spiegel) zur Verbesserung von Körperwahrnehmung und Körperbild bei Personen mit Adipositas entwickelt. Methoden Im Rahmen der multizentrischen kontrollierten ViTraS-Pilotstudie (Registrierungsnummer: DRKS00027906) wurden bei Personen mit Adipositas virtuelle bzw. traditionelle Körperbildübungen angewendet. Es fanden drei Sitzungen im Abstand von ca. zwei Wochen statt. Über die Zeit wurden anthropometrische Daten sowie Daten zum Ernährungsverhalten (Dutch Eating Behavior Questionnaire (DEBQ) und eine Auswahl von Fragen des The Eating Motivation Survey (TEMS)) erfasst. In zwei Sitzungen wurden Körperbildübungen virtuell (VR-Gruppe) oder nicht-virtuell (Kontrollgruppe) durchgeführt. Eine online Follow-Up-Datenerhebung fand 6 Wochen nach der letzten Sitzung statt. Ergebnisse Insgesamt wurden 66 Personen (VR-Gruppe: 31, Kontrollgruppe: 35) in die Studie eingeschlossen. Die Personen waren zu 79% (52/66) weiblich, 45±13 Jahre alt und der mittlere BMI lag bei 37±4 kg/m2. Die Auswertung des DEBQ Fragebogens hat ergeben, dass in der VR-Gruppe gezügeltes Essverhalten von Anfang bis Ende der Studie signifikant (p<0,05) zugenommen hat. Die Ergebnisse der Auswahl von Fragen des TEMS hat keine signifikanten (p≥0,05) Unterschiede innerhalb oder zwischen den Gruppen ergeben. Schlussfolgerung Die Studie hat ergeben, dass die Durchführung von virtuellen Körperbildübungen eine Auswirkung auf das Ernährungsverhalten von Personen mit Adipositas haben kann.}, author = {Gemesi, Kathrin and Döllinger, Nina and Weinberger, Natascha-Alexandra and Wolf, Erik and Mal, David and Wienrich, Carolin and Luck-Sikorski, Claudia and Bader, Erik and Holzapfel, Christina}, journal = {Adipositas - Ursachen, Folgeerkrankungen, Therapie}, keywords = {dmal}, number = {03}, pages = {S10-05}, title = {Auswirkung von (virtuellen) Körperbildübungen auf das Ernährungsverhalten von Personen mit Adipositas – Ergebnisse der ViTraS-Pilotstudie}, volume = 17, year = 2023 }
• Searching for the Ground Truth: Assessing the Similarity of Benchmarking Runs. Bauer, Andr{é}; Straesser, Martin; Leznik, Mark; Beierlieb, Lukas; Hadry, Marius; Hudson, Nathaniel; Chard, Kyle; Kounev, Samuel; Foster, Ian. In Companion of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23 Companion, pp. 95–99. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Stable and repeatable measurements are essential for comparing the performance of different systems or applications, and benchmarks are used to ensure accuracy and replication. However, if the corresponding measurements are not stable and repeatable, wrong conclusions can be drawn. To facilitate the task of determining whether the measurements are similar, we used a data set of 586 micro-benchmarks to (i) analyze the data set itself, (ii) examine our previous approach, and (iii) propose and evaluate a heuristic. To evaluate the different approaches, we perform a peer review to assess the dissimilarity of the benchmark runs. Our results show that this task is challenging even for humans and that our heuristic exhibits a sensitivity of 92%.

  @inproceedings{10.1145/3578245.3584693, abstract = {Stable and repeatable measurements are essential for comparing the performance of different systems or applications, and benchmarks are used to ensure accuracy and replication. However, if the corresponding measurements are not stable and repeatable, wrong conclusions can be drawn. To facilitate the task of determining whether the measurements are similar, we used a data set of 586 micro-benchmarks to (i) analyze the data set itself, (ii) examine our previous approach, and (iii) propose and evaluate a heuristic. To evaluate the different approaches, we perform a peer review to assess the dissimilarity of the benchmark runs. Our results show that this task is challenging even for humans and that our heuristic exhibits a sensitivity of 92%.}, address = {New York, NY, USA}, author = {Bauer, Andr\'{e} and Straesser, Martin and Leznik, Mark and Beierlieb, Lukas and Hadry, Marius and Hudson, Nathaniel and Chard, Kyle and Kounev, Samuel and Foster, Ian}, booktitle = {Companion of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {distance_measures}, pages = {95–99}, publisher = {Association for Computing Machinery}, series = {ICPE '23 Companion}, title = {Searching for the Ground Truth: Assessing the Similarity of Benchmarking Runs}, year = 2023 }
• Challenges and Future Directions in Efficiency Benchmarking (Vision Paper). Meissner, Maximilian; Lange, Klaus-Dieter; Sharma, Sanjay; Arnold, Jeremy; Cragin, Aaron; Galizia, Patrick; Petrich, Mike; Zhang, Bin; Kounev, Samuel. In Companion of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23 Companion, pp. 51–55. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  SPEC benchmarks are crucial contributors behind the improvement of server efficiency since 2007, given their role in making the power consumption and efficiency of servers transparent for government regulators, customers, and the manufacturers themselves.As the IT landscape experiences radical transformations, efficiency benchmarks need to be updated accordingly to generate results relevant to government regulators, manufacturers, and customers. In this paper, we outline current challenges efficiency benchmark developers are tackling and highlight recent technological developments the next generation of efficiency benchmarks should take into account.

  @inproceedings{10.1145/3578245.3585034, abstract = {SPEC benchmarks are crucial contributors behind the improvement of server efficiency since 2007, given their role in making the power consumption and efficiency of servers transparent for government regulators, customers, and the manufacturers themselves.As the IT landscape experiences radical transformations, efficiency benchmarks need to be updated accordingly to generate results relevant to government regulators, manufacturers, and customers. In this paper, we outline current challenges efficiency benchmark developers are tackling and highlight recent technological developments the next generation of efficiency benchmarks should take into account.}, address = {New York, NY, USA}, author = {Meissner, Maximilian and Lange, Klaus-Dieter and Sharma, Sanjay and Arnold, Jeremy and Cragin, Aaron and Galizia, Patrick and Petrich, Mike and Zhang, Bin and Kounev, Samuel}, booktitle = {Companion of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {descartes}, pages = {51–55}, publisher = {Association for Computing Machinery}, series = {ICPE '23 Companion}, title = {Challenges and Future Directions in Efficiency Benchmarking (Vision Paper)}, year = 2023 }
• Performance Impact Analysis of Homomorphic Encryption: A Case Study Using Linear Regression as an Example. Prantl, Thomas; Engel, Simon; Horn, Lukas; Kaiser, Dennis; Iffländer, Lukas; Bauer, André; Krupitzer, Christian; Kounev, Samuel. In Information Security Practice and Experience, W. Meng, Z. Yan, V. Piuri (eds.), pp. 284–298. Springer Nature Singapore, Singapore, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  In recent years, the trend has increasingly been to store and process data in the cloud. However, this is based on the premise that cloud providers treat the data in a trustworthy manner. One way of using the data in the cloud without the provider having access to it is homomorphic encryption. However, since this encryption has only recently become practicable, analysis of its for practical applications is still in its infancy. Therefore, we investigate the performance of homomorphic encryption using a real-world application, namely linear regression. Our main finding is that although the homomorphic computation of linear regression is in the range of minutes and thus slower than in the non-homomorphic case, linear regression can be computed homomorphic and is therefore suitable for use cases where data security is the top priority.

  @inproceedings{PrEnHoDeIfBaKrKo_ISPEC_De_Bello, abstract = {In recent years, the trend has increasingly been to store and process data in the cloud. However, this is based on the premise that cloud providers treat the data in a trustworthy manner. One way of using the data in the cloud without the provider having access to it is homomorphic encryption. However, since this encryption has only recently become practicable, analysis of its for practical applications is still in its infancy. Therefore, we investigate the performance of homomorphic encryption using a real-world application, namely linear regression. Our main finding is that although the homomorphic computation of linear regression is in the range of minutes and thus slower than in the non-homomorphic case, linear regression can be computed homomorphic and is therefore suitable for use cases where data security is the top priority.}, address = {Singapore}, author = {Prantl, Thomas and Engel, Simon and Horn, Lukas and Kaiser, Dennis and Iffl\"ander, Lukas and Bauer, Andr\'e and Krupitzer, Christian and Kounev, Samuel}, booktitle = {Information Security Practice and Experience}, editor = {Meng, Weizhi and Yan, Zheng and Piuri, Vincenzo}, keywords = {t_proceedings}, pages = {284–298}, publisher = {Springer Nature Singapore}, title = {Performance Impact Analysis of Homomorphic Encryption: A Case Study Using Linear Regression as an Example}, year = 2023 }
• Can Neural Networks Distinguish High-school Level Mathematical Concepts?. Wankerl, Sebastian; Dulny, Andrzej; Goetz, Gerhard; Hotho, Andreas. In Accepted at ICDM. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Processing symbolic mathematics algorithmically is an important field of research. It has applications in computer algebra systems and supports researchers as well as applied mathematicians in their daily work. Recently, exploring the ability of neural networks to grasp mathematical concepts has received special attention. One particularly complex task for neural networks is to understand the relation of two mathematical expressions to each other. Despite the advances in learning mathematical relationships, previous studies are limited by small-scale datasets, relatively simple formula construction by few axiomatic rules and even artifacts in the data. With this work, we aim at overcoming these limitations and provide a deeper insight into the representation power of neural networks for classifying mathematical relations. We introduce a novel data generation algorithm to allow for more complex formula compositions and fully include mathematical fields up to high-school level. We research several tree-based and sequential neural architectures for classifying mathematical relations and conduct a systematic analysis of the models against rule-based as well as neural baselines with a focus on varying data set complexity, generalization abilities, and understanding of syntactical patterns. Our findings highlight the effectiveness of tree-structured models for this task and show the potential of deep learning models to distinguish high-school level mathematical concepts.

  @conference{wankerl2023neural, abstract = {Processing symbolic mathematics algorithmically is an important field of research. It has applications in computer algebra systems and supports researchers as well as applied mathematicians in their daily work. Recently, exploring the ability of neural networks to grasp mathematical concepts has received special attention. One particularly complex task for neural networks is to understand the relation of two mathematical expressions to each other. Despite the advances in learning mathematical relationships, previous studies are limited by small-scale datasets, relatively simple formula construction by few axiomatic rules and even artifacts in the data. With this work, we aim at overcoming these limitations and provide a deeper insight into the representation power of neural networks for classifying mathematical relations. We introduce a novel data generation algorithm to allow for more complex formula compositions and fully include mathematical fields up to high-school level. We research several tree-based and sequential neural architectures for classifying mathematical relations and conduct a systematic analysis of the models against rule-based as well as neural baselines with a focus on varying data set complexity, generalization abilities, and understanding of syntactical patterns. Our findings highlight the effectiveness of tree-structured models for this task and show the potential of deep learning models to distinguish high-school level mathematical concepts.}, author = {Wankerl, Sebastian and Dulny, Andrzej and Goetz, Gerhard and Hotho, Andreas}, booktitle = {Accepted at ICDM}, keywords = {from:martinr}, title = {Can Neural Networks Distinguish High-school Level Mathematical Concepts?}, year = 2023 }
• Towards a Cryptography Encyclopedia: A Survey on Attribute-Based Encryption. Prantl, Thomas; Zeck, Timo; Horn, Lukas; Iffländer, Lukas; Bauer, André; Dmitrienko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In Journal of Surveillance, Security and Safety. 2023.
  • [ BibTeX ]
  @article{PrZeHoIfBaDmKrKo_ABESurvey, author = {Prantl, Thomas and Zeck, Timo and Horn, Lukas and Iffl\"ander, Lukas and Bauer, Andr\'e and Dmitrienko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, journal = {Journal of Surveillance, Security and Safety}, keywords = {t_journalmagazine}, title = {Towards a Cryptography Encyclopedia: A Survey on Attribute-Based Encryption}, year = 2023 }
• Power to the Applications: The Vision of Continuous Decentralized Autoscaling. Straesser, Martin; Geißler, Stefan; Hoßfeld, Tobias; Kounev, Samuel. In 2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing Workshops (CCGridW), pp. 281–283. IEEE, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{straesser2023decentral, author = {Straesser, Martin and Geißler, Stefan and Hoßfeld, Tobias and Kounev, Samuel}, booktitle = {2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing Workshops (CCGridW)}, keywords = {t_poster}, pages = {281-283}, publisher = {IEEE}, title = {Power to the Applications: The Vision of Continuous Decentralized Autoscaling}, year = 2023 }
• A Systematic Approach for Benchmarking of Container Orchestration Frameworks. Straesser, Martin; Mathiasch, Jonas; Bauer, Andr{é}; Kounev, Samuel. In Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23, pp. 187–198. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Container orchestration frameworks play a critical role in modern cloud computing paradigms such as cloud-native or serverless computing. They significantly impact the quality and cost of service deployment as they manage many performance-critical tasks such as container provisioning, scheduling, scaling, and networking. Consequently, a comprehensive performance assessment of container orchestration frameworks is essential. However, until now, there is no benchmarking approach that covers the many different tasks implemented in such platforms and supports evaluating different technology stacks. In this paper, we present a systematic approach that enables benchmarking of container orchestrators. Based on a definition of container orchestration, we define the core requirements and benchmarking scope for such platforms. Each requirement is then linked to metrics and measurement methods, and a benchmark architecture is proposed. With COFFEE, we introduce a benchmarking tool supporting the definition of complex test campaigns for container orchestration frameworks. We demonstrate the potential of our approach with case studies of the frameworks Kubernetes and Nomad in a self-hosted environment and on the Google Cloud Platform. The presented case studies focus on container startup times, crash recovery, rolling updates, and more.

  @inproceedings{straesser2023orchestration, abstract = {Container orchestration frameworks play a critical role in modern cloud computing paradigms such as cloud-native or serverless computing. They significantly impact the quality and cost of service deployment as they manage many performance-critical tasks such as container provisioning, scheduling, scaling, and networking. Consequently, a comprehensive performance assessment of container orchestration frameworks is essential. However, until now, there is no benchmarking approach that covers the many different tasks implemented in such platforms and supports evaluating different technology stacks. In this paper, we present a systematic approach that enables benchmarking of container orchestrators. Based on a definition of container orchestration, we define the core requirements and benchmarking scope for such platforms. Each requirement is then linked to metrics and measurement methods, and a benchmark architecture is proposed. With COFFEE, we introduce a benchmarking tool supporting the definition of complex test campaigns for container orchestration frameworks. We demonstrate the potential of our approach with case studies of the frameworks Kubernetes and Nomad in a self-hosted environment and on the Google Cloud Platform. The presented case studies focus on container startup times, crash recovery, rolling updates, and more.}, address = {New York, NY, USA}, author = {Straesser, Martin and Mathiasch, Jonas and Bauer, Andr\'{e} and Kounev, Samuel}, booktitle = {Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {container_orchestration}, pages = {187-198}, publisher = {Association for Computing Machinery}, series = {ICPE '23}, title = {A Systematic Approach for Benchmarking of Container Orchestration Frameworks}, year = 2023 }
• Autoscaler Evaluation and Configuration: A Practitioner’s Guideline. Straesser, Martin; Eismann, Simon; von Kistowski, J{ó}akim; Bauer, Andr{é}; Kounev, Samuel. In Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23, pp. 31–41. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Autoscalers are indispensable parts of modern cloud deployments and determine the service quality and cost of a cloud application in dynamic workloads. The configuration of an autoscaler strongly influences its performance and is also one of the biggest challenges and showstoppers for the practical applicability of many research autoscalers. Many proposed cloud experiment methodologies can only be partially applied in practice, and many autoscaling papers use custom evaluation methods and metrics. This paper presents a practical guideline for obtaining meaningful and interpretable results on autoscaler performance with reasonable overhead. We provide step-by-step instructions for defining realistic usage behaviors and traffic patterns. We divide the analysis of autoscaler performance into a qualitative antipattern-based analysis and a quantitative analysis. To demonstrate the applicability of our guideline, we conduct several experiments with a microservice of our industry partner in a realistic test environment.

  @inproceedings{straesser2023guideline, abstract = {Autoscalers are indispensable parts of modern cloud deployments and determine the service quality and cost of a cloud application in dynamic workloads. The configuration of an autoscaler strongly influences its performance and is also one of the biggest challenges and showstoppers for the practical applicability of many research autoscalers. Many proposed cloud experiment methodologies can only be partially applied in practice, and many autoscaling papers use custom evaluation methods and metrics. This paper presents a practical guideline for obtaining meaningful and interpretable results on autoscaler performance with reasonable overhead. We provide step-by-step instructions for defining realistic usage behaviors and traffic patterns. We divide the analysis of autoscaler performance into a qualitative antipattern-based analysis and a quantitative analysis. To demonstrate the applicability of our guideline, we conduct several experiments with a microservice of our industry partner in a realistic test environment.}, address = {New York, NY, USA}, author = {Straesser, Martin and Eismann, Simon and von Kistowski, J\'{o}akim and Bauer, Andr\'{e} and Kounev, Samuel}, booktitle = {Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {methodology}, pages = {31-41}, publisher = {Association for Computing Machinery}, series = {ICPE '23}, title = {Autoscaler Evaluation and Configuration: A Practitioner's Guideline}, year = 2023 }
• Do you Agree? Contrasting Google’s Core Web Vitals and the Impact of Cookie Consent Banners with Actual Web QoE. Wehner, Nikolas; Seufert, Michael; Schatz, Raimund; Hoßfeld, Tobias. In Quality and User Experience. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Providing sophisticated web Quality of Experience (QoE) has become paramount for web service providers and network operators alike. Due to advances in web technologies (HTML5, respon- sive design, etc.), traditional web QoE models focusing mainly on loading times have to be refined and improved. In this work, we relate Google’s Core Web Vitals, a set of metrics for improving user experience, to the loading time aspects of web QoE, and investigate whether the Core Web Vitals and web QoE agree on the perceived experience. To this end, we first perform objective measurements in the web using Google’s Lighthouse. To close the gap be- tween metrics and experience, we complement these objective measurements with subjective assessment by performing multiple crowdsourcing QoE studies. For this purpose, we developed CWeQS, a customized framework to emulate the entire web page loading process, and ask users for their experience while controlling the Core Web Vitals, which is available to the public. To properly configure CWeQS for the planned QoE study and the crowdsourcing setup, we conduct pre-studies, in which we evaluate the importance of the loading strategy of a web page and the impor- tance of the user task. The obtained insights allow us to conduct the desired QoE studies for each of the Core Web Vitals. Furthermore, we assess the impact of cookie consent banners, which have become ubiquitous due to regulatory demands, on the Core Web Vitals and investigate their influence on web QoE. Our results suggest that the Core Web Vitals are much less predictive for web QoE than expected and that page loading times remain the main metric and influence factor in this context. We further observe that unobtrusive and acentric cookie consent banners are preferred by end-users and that addi- tional delays caused by interacting with consent banners in order to agree to or reject cookies should be accounted along with the actual page load time to reduce waiting times and thus to improve web QoE.

  @article{info3-article-2023-3, abstract = {Providing sophisticated web Quality of Experience (QoE) has become paramount for web service providers and network operators alike. Due to advances in web technologies (HTML5, respon- sive design, etc.), traditional web QoE models focusing mainly on loading times have to be refined and improved. In this work, we relate Google’s Core Web Vitals, a set of metrics for improving user experience, to the loading time aspects of web QoE, and investigate whether the Core Web Vitals and web QoE agree on the perceived experience. To this end, we first perform objective measurements in the web using Google’s Lighthouse. To close the gap be- tween metrics and experience, we complement these objective measurements with subjective assessment by performing multiple crowdsourcing QoE studies. For this purpose, we developed CWeQS, a customized framework to emulate the entire web page loading process, and ask users for their experience while controlling the Core Web Vitals, which is available to the public. To properly configure CWeQS for the planned QoE study and the crowdsourcing setup, we conduct pre-studies, in which we evaluate the importance of the loading strategy of a web page and the impor- tance of the user task. The obtained insights allow us to conduct the desired QoE studies for each of the Core Web Vitals. Furthermore, we assess the impact of cookie consent banners, which have become ubiquitous due to regulatory demands, on the Core Web Vitals and investigate their influence on web QoE. Our results suggest that the Core Web Vitals are much less predictive for web QoE than expected and that page loading times remain the main metric and influence factor in this context. We further observe that unobtrusive and acentric cookie consent banners are preferred by end-users and that addi- tional delays caused by interacting with consent banners in order to agree to or reject cookies should be accounted along with the actual page load time to reduce waiting times and thus to improve web QoE.}, author = {Wehner, Nikolas and Seufert, Michael and Schatz, Raimund and Hoßfeld, Tobias}, journal = {Quality and User Experience}, keywords = {ucn}, title = {Do you Agree? Contrasting Google’s Core Web Vitals and the Impact of Cookie Consent Banners with Actual Web QoE}, year = 2023 }
• Towards Simulation-Driven Optimization of Container Orchestration Mechanisms. Dittus, Timo; Straesser, Martin; Kounev, Samuel. 2023.
  • [ BibTeX ]
  @presentation{dittus2023simdrivenopt, author = {Dittus, Timo and Straesser, Martin and Kounev, Samuel}, keywords = {container_orchestration}, title = {Towards Simulation-Driven Optimization of Container Orchestration Mechanisms}, year = 2023 }
• BLOCSIE - Benchmark for LOCalization in a Simulated Industrial Environment. Spiess, Florian; Bluemm, Daniel; Strobel, Norbert; Kaupp, Tobias; Kounev, Samuel. In 2023 21st International Conference on Advanced Robotics (ICAR), pp. 577–584. 2023.
  • [ BibTeX ]
  @inproceedings{10406777, author = {Spiess, Florian and Bluemm, Daniel and Strobel, Norbert and Kaupp, Tobias and Kounev, Samuel}, booktitle = {2023 21st International Conference on Advanced Robotics (ICAR)}, keywords = {descartes}, pages = {577-584}, title = {BLOCSIE - Benchmark for LOCalization in a Simulated Industrial Environment}, year = 2023 }
• Enhancing Sequential Next-Item Prediction through Modelling Non-Item Pages. Fischer, Elisabeth; Schlör, Daniel; Zehe, Albin; Hotho, Andreas. 2023.
  • [ BibTeX ]
  @unpublished{fischer2023enhancing, author = {Fischer, Elisabeth and Schlör, Daniel and Zehe, Albin and Hotho, Andreas}, keywords = {recommender}, title = {Enhancing Sequential Next-Item Prediction through Modelling Non-Item Pages}, year = 2023 }
• Independent Set in $k$-Claw-Free Graphs: Conditional $\chi$-Boundedness and the Power of {LP/SDP} Relaxations. Chalermsook, Parinya; Gadekar, Ameet; Khodamoradi, Kamyar; Spoerhase, Joachim. In Proc. International Workshop on Approximation and Online Algorithms (WAOA’23). 2023.
  • [ BibTeX ]
  @inproceedings{chalermsook-etal23:k-claw-free, author = {Chalermsook, Parinya and Gadekar, Ameet and Khodamoradi, Kamyar and Spoerhase, Joachim}, booktitle = {Proc. International Workshop on Approximation and Online Algorithms (WAOA'23)}, keywords = {graph}, note = {to appear}, title = {Independent Set in $k$-Claw-Free Graphs: Conditional $\chi$-Boundedness and the Power of {LP/SDP} Relaxations}, year = 2023 }
• Searching for the Ground Truth: Assessing the Similarity of Benchmarking Runs. Bauer, Andr{é}; Straesser, Martin; Leznik, Mark; Beierlieb, Lukas; Hadry, Marius; Hudson, Nathaniel; Chard, Kyle; Kounev, Samuel; Foster, Ian. In Companion of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23 Companion, pp. 95–99. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Stable and repeatable measurements are essential for comparing the performance of different systems or applications, and benchmarks are used to ensure accuracy and replication. However, if the corresponding measurements are not stable and repeatable, wrong conclusions can be drawn. To facilitate the task of determining whether the measurements are similar, we used a data set of 586 micro-benchmarks to (i) analyze the data set itself, (ii) examine our previous approach, and (iii) propose and evaluate a heuristic. To evaluate the different approaches, we perform a peer review to assess the dissimilarity of the benchmark runs. Our results show that this task is challenging even for humans and that our heuristic exhibits a sensitivity of 92%.

  @inproceedings{10.1145/3578245.3584693, abstract = {Stable and repeatable measurements are essential for comparing the performance of different systems or applications, and benchmarks are used to ensure accuracy and replication. However, if the corresponding measurements are not stable and repeatable, wrong conclusions can be drawn. To facilitate the task of determining whether the measurements are similar, we used a data set of 586 micro-benchmarks to (i) analyze the data set itself, (ii) examine our previous approach, and (iii) propose and evaluate a heuristic. To evaluate the different approaches, we perform a peer review to assess the dissimilarity of the benchmark runs. Our results show that this task is challenging even for humans and that our heuristic exhibits a sensitivity of 92%.}, address = {New York, NY, USA}, author = {Bauer, Andr\'{e} and Straesser, Martin and Leznik, Mark and Beierlieb, Lukas and Hadry, Marius and Hudson, Nathaniel and Chard, Kyle and Kounev, Samuel and Foster, Ian}, booktitle = {Companion of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {distance_measures}, pages = {95–99}, publisher = {Association for Computing Machinery}, series = {ICPE '23 Companion}, title = {Searching for the Ground Truth: Assessing the Similarity of Benchmarking Runs}, year = 2023 }
• Parameterized Approaches to Orthogonal Compaction. Didimo, Walter; Gupta, Siddharth; Kindermann, Philipp; Liotta, Giuseppe; Wolff, Alexander; Zehavi, Meirav. In Proc. 49th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM’23), Vol. 13878 of Lecture Notes in Computer Science, L. Gąsieniec (ed.), pp. 111–128. Springer-Verlag, 2023.
  • [ BibTeX ]
  @inproceedings{dgklwz-paoc-SOFSEM23, author = {Didimo, Walter and Gupta, Siddharth and Kindermann, Philipp and Liotta, Giuseppe and Wolff, Alexander and Zehavi, Meirav}, booktitle = {Proc. 49th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM'23)}, editor = {Gąsieniec, Leszek}, keywords = {myown}, pages = {111–128}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Parameterized Approaches to Orthogonal Compaction}, volume = 13878, year = 2023 }
• Evaluating feature relevance XAI in network intrusion detection. Tritscher, Julian; Wolf, Maximilian; Hotho, Andreas; Schlör, Daniel. In The World Conference on eXplainable Artificial Intelligence (xAI 2023) - to appear. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  As machine learning models become increasingly complex, there is a growing need for explainability to understand and trust the decision-making processes. In the domain of network intrusion detection, post-hoc feature relevance explanations have been widely used to provide insight into the factors driving model decisions. However, recent research has highlighted challenges with these methods when applied to anomaly detection, which can vary in importance and impact depending on the application domain. In this paper, we investigate the challenges of post-hoc feature relevance explanations for network intrusion detection, a critical area for ensuring the security and integrity of computer networks. To gain a deeper understanding of these challenges for the application domain, we quantitatively and qualitatively investigate the popular feature relevance approach SHAP when explaining different network intrusion detection approaches. We conduct experiments to jointly evaluate detection quality and explainability, and explore the impact of replacement data, a commonly overlooked hyperparameter of post-hoc feature relevance approaches. We find that post-hoc XAI can provide high quality explanations, but requires a careful choice of its replacement data as default settings and common choices do not transfer across different detection models. Our study showcases the viability of post-hoc XAI for network intrusion detection systems, but highlights the need for rigorous evaluations of produced explanations.

  @article{tritscher2023evaluating, abstract = {As machine learning models become increasingly complex, there is a growing need for explainability to understand and trust the decision-making processes. In the domain of network intrusion detection, post-hoc feature relevance explanations have been widely used to provide insight into the factors driving model decisions. However, recent research has highlighted challenges with these methods when applied to anomaly detection, which can vary in importance and impact depending on the application domain. In this paper, we investigate the challenges of post-hoc feature relevance explanations for network intrusion detection, a critical area for ensuring the security and integrity of computer networks. To gain a deeper understanding of these challenges for the application domain, we quantitatively and qualitatively investigate the popular feature relevance approach SHAP when explaining different network intrusion detection approaches. We conduct experiments to jointly evaluate detection quality and explainability, and explore the impact of replacement data, a commonly overlooked hyperparameter of post-hoc feature relevance approaches. We find that post-hoc XAI can provide high quality explanations, but requires a careful choice of its replacement data as default settings and common choices do not transfer across different detection models. Our study showcases the viability of post-hoc XAI for network intrusion detection systems, but highlights the need for rigorous evaluations of produced explanations.}, author = {Tritscher, Julian and Wolf, Maximilian and Hotho, Andreas and Schlör, Daniel}, journal = {The World Conference on eXplainable Artificial Intelligence (xAI 2023) - to appear}, keywords = {xai}, title = {Evaluating feature relevance XAI in network intrusion detection}, year = 2023 }
• Body and Time: Virtual Embodiment and its effect on Time Perception. Unruh, Fabian; Vogel, David H.V.; Landeck, Maximilian; Lugrin, Jean-Luc; Latoschik, Marc Erich. In IEEE Transactions on Visualization and Computer Graphics (TVCG), 29(5), pp. 2626–2636. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This article explores the effect of one’s body representation on time perception. Time Perception is modulated by a variety of factors including, e.g., the current situation or activity, it can display significant disturbances caused by psychological disorders, and it is influenced by emotional and interoceptive states, i.e., ”the sense of the physiological condition of the body”. We investigated this relation between one’s own body and the perception of time in a novel Virtual Reality (VR) experiment explicitly fostering user activity. 36 participants randomly experienced different degrees of embodiment: i) without an avatar (low), ii) with hands (medium), and iii) with a high quality avatar (high). Participants had to repeatedly activate a virtual lamp and estimate the duration of time intervals as well as judge the passage of time. Our results show a significant effect of embodiment on time perception: time passes slower in the low embodiment condition compared to the medium and high conditions. In contrast to prior work, the study provides missing evidence that this effect is independent of the level of activity of participants: In our task users were prompted to repeatedly perform body actions, thereby ruling-out a potential influence of the level of activity. Importantly, duration judgements in both the millisecond and minute ranges seemed unaffected by variations in embodiment. Taken together, these results lead to a better understanding of the relationship between the body and time.

  @article{unruh2023virtual, abstract = {This article explores the effect of one’s body representation on time perception. Time Perception is modulated by a variety of factors including, e.g., the current situation or activity, it can display significant disturbances caused by psychological disorders, and it is influenced by emotional and interoceptive states, i.e., ”the sense of the physiological condition of the body”. We investigated this relation between one’s own body and the perception of time in a novel Virtual Reality (VR) experiment explicitly fostering user activity. 36 participants randomly experienced different degrees of embodiment: i) without an avatar (low), ii) with hands (medium), and iii) with a high quality avatar (high). Participants had to repeatedly activate a virtual lamp and estimate the duration of time intervals as well as judge the passage of time. Our results show a significant effect of embodiment on time perception: time passes slower in the low embodiment condition compared to the medium and high conditions. In contrast to prior work, the study provides missing evidence that this effect is independent of the level of activity of participants: In our task users were prompted to repeatedly perform body actions, thereby ruling-out a potential influence of the level of activity. Importantly, duration judgements in both the millisecond and minute ranges seemed unaffected by variations in embodiment. Taken together, these results lead to a better understanding of the relationship between the body and time.}, author = {Unruh, Fabian and Vogel, David H.V. and Landeck, Maximilian and Lugrin, Jean-Luc and Latoschik, Marc Erich}, journal = {IEEE Transactions on Visualization and Computer Graphics (TVCG)}, keywords = {hci-uwb}, month = {05}, note = {IEEE VR Best Paper Nominee 🏆}, number = 5, pages = {2626 - 2636}, title = {Body and Time: Virtual Embodiment and its effect on Time Perception}, volume = 29, year = 2023 }
• Towards Understanding the Signaling Traffic in 5G Core Networks. Raffeck, Simon; Geißler, Stefan; Hoßfeld, Tobias. In KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023. 2023.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2023-8, author = {Raffeck, Simon and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023}, keywords = {can}, month = {06}, title = {Towards Understanding the Signaling Traffic in 5G Core Networks}, year = 2023 }
• Erdbeobachtung der Walddynamik und Biodiversität in Echtzeit. Kounev, Samuel. 2023, June.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Highlightvortrag auf der Eröffnungsveranstaltung der wissenschaftlichen Plattform ‚terrabyte’ zur Analyse von Erdbeobachtungsdaten des Deutschen Zentrums für Luft- und Raumfahrt (DLR) im Leibniz-Rechenzentrum (LRZ) der Bayerischen Akademie der Wissenschaften.

  @misc{kounev2023erdbeobachtung, abstract = {Highlightvortrag auf der Eröffnungsveranstaltung der wissenschaftlichen Plattform ‚terrabyte’ zur Analyse von Erdbeobachtungsdaten des Deutschen Zentrums für Luft- und Raumfahrt (DLR) im Leibniz-Rechenzentrum (LRZ) der Bayerischen Akademie der Wissenschaften.}, author = {Kounev, Samuel}, keywords = {t_presscoverage}, month = {06}, note = {https://www.sueddeutsche.de/muenchen/landkreismuenchen/garching-leibniz-rechenzentrum-deutsches-zentrum-fuer-luft-und-raumfahrt-erdbeobachtungsdaten-terrabyte-1.5933991}, title = {Erdbeobachtung der Walddynamik und Biodiversität in Echtzeit}, year = 2023 }
• Understanding the Performance of Different Packet Reception and Timestamping Methods in Linux. Grigorjew, Alexej; Schumann, Lukas Kilian; Diederich, Philip; Hoßfeld, Tobias; Kellerer, Wolfgang. In WueWoWAS’23 KuVS Fachgespraech - Wuerzburg Workshop on Next-Generation Communication Networks. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  This document briefly presents some renowned packet reception techniques for network packets in Linux systems. Further, it compares their performance when measuring packet timestamps with respect to throughput and accuracy. Both software and hardware timestamps are compared, and various parameters are examined, including frame size, link speed, network interface card, and CPU load. The results indicate that hardware timestamping offers significantly better accuracy with no downsides, and that packet reception techniques that avoid system calls offer superior measurement throughput.

  @inproceedings{info3-inproceedings-2023-11, abstract = {This document briefly presents some renowned packet reception techniques for network packets in Linux systems. Further, it compares their performance when measuring packet timestamps with respect to throughput and accuracy. Both software and hardware timestamps are compared, and various parameters are examined, including frame size, link speed, network interface card, and CPU load. The results indicate that hardware timestamping offers significantly better accuracy with no downsides, and that packet reception techniques that avoid system calls offer superior measurement throughput.}, author = {Grigorjew, Alexej and Schumann, Lukas Kilian and Diederich, Philip and Hoßfeld, Tobias and Kellerer, Wolfgang}, booktitle = {WueWoWAS'23 KuVS Fachgespraech - Wuerzburg Workshop on Next-Generation Communication Networks}, keywords = {appaware2}, month = {06}, title = {Understanding the Performance of Different Packet Reception and Timestamping Methods in Linux}, year = 2023 }
• Paving the Way for an Energy Efficient and Sustainable Future Internet of Things. Loh, Frank; Raffeck, Simon; Geißler, Stefan; Hoßfeld, Tobias. In KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023. 2023.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2023-12, author = {Loh, Frank and Raffeck, Simon and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023}, keywords = {myown}, month = {06}, title = {Paving the Way for an Energy Efficient and Sustainable Future Internet of Things}, year = 2023 }
• INTRODUCING A MULTIMODAL DATASET FOR THE RESEARCH OF ARCHITECTURAL ELEMENTS. Bruschke, J.; Kröber, C.; Maiwald, F.; Utescher, R.; Pattee, A. In The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLVIII-M-2-2023, pp. 325–331. Copernicus GmbH, 2023.
  • [ BibTeX ]
  • [ URL ]
  @article{Bruschke_archilabel_2023, author = {Bruschke, J. and Kröber, C. and Maiwald, F. and Utescher, R. and Pattee, A.}, journal = {The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences}, keywords = {histstadt4d}, month = {06}, pages = {325–331}, publisher = {Copernicus GmbH}, title = {INTRODUCING A MULTIMODAL DATASET FOR THE RESEARCH OF ARCHITECTURAL ELEMENTS}, volume = {XLVIII-M-2-2023}, year = 2023 }
• Uplink-based Live Session Model for Stalling Prediction in Video Streaming. Loh, Frank; Pimpinella, Andrea; Geißler, Stefan; Hoßfeld, Tobias. In IEEE/IFIP Network Operations and Management Symposium (NOMS). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Today, video streaming is responsible for about 50 % of all Internet traffic worldwide. To cope with this massive amount of video streaming data, a major concern of network providers is the development of efficient traffic monitoring and management techniques. However, fast and efficient monitoring which leads to intelligent management decisions is becoming highly resource intense and complex, due to the steady increase of the number of streamed videos and the quality of the streamed content. Considering HTTP adaptive streaming applications, we present a simple machine learning free, uplink request based approach to estimate drops in the video playback buffer. These drops are the first indicator leading to quality impairment events like downwards quality changes or stalling. With our approach, instead of analyzing thousands of encrypted packets in the network, we only need to consider one single packet every 5 s - 10 s on average, depending on the video chunk size and independently of the played resolution. Nevertheless, we are able to detect nearly all stalling events or consider a trade-off between stalling detection recall and false positives. Our approach can be implemented completely moving average based, thus not requiring any parameter setup or other expert knowledge. Due to its simplicity, it can be deployed on any access point to collect streaming quality information that is useful for active network management and intelligent resource provisioning but also in a data center to analyze a massive number of parallel video flows

  @inproceedings{info3-inproceedings-2023-16, abstract = {Today, video streaming is responsible for about 50 % of all Internet traffic worldwide. To cope with this massive amount of video streaming data, a major concern of network providers is the development of efficient traffic monitoring and management techniques. However, fast and efficient monitoring which leads to intelligent management decisions is becoming highly resource intense and complex, due to the steady increase of the number of streamed videos and the quality of the streamed content. Considering HTTP adaptive streaming applications, we present a simple machine learning free, uplink request based approach to estimate drops in the video playback buffer. These drops are the first indicator leading to quality impairment events like downwards quality changes or stalling. With our approach, instead of analyzing thousands of encrypted packets in the network, we only need to consider one single packet every 5 s - 10 s on average, depending on the video chunk size and independently of the played resolution. Nevertheless, we are able to detect nearly all stalling events or consider a trade-off between stalling detection recall and false positives. Our approach can be implemented completely moving average based, thus not requiring any parameter setup or other expert knowledge. Due to its simplicity, it can be deployed on any access point to collect streaming quality information that is useful for active network management and intelligent resource provisioning but also in a data center to analyze a massive number of parallel video flows}, author = {Loh, Frank and Pimpinella, Andrea and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {IEEE/IFIP Network Operations and Management Symposium (NOMS)}, keywords = {myown}, month = {05}, title = {Uplink-based Live Session Model for Stalling Prediction in Video Streaming}, year = 2023 }
• Exploring Plausibility and Presence in Mixed Reality Experiences. Westermeier, Franziska; Brübach, Larissa; Latoschik, Marc Erich; Wienrich, Carolin. In IEEE Transactions on Visualization and Computer Graphics, 29(5), pp. 2680–2689. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Mixed Reality (MR) applications along Milgram's Reality-Virtuality (RV) continuum motivated a number of recent theories on potential constructs and factors describing MR experiences. This paper investigates the impact of incongruencies on the sensation/perception and cognition layers to provoke breaks in plausibility, and the effects these breaks have on spatial and overall presence as prominent constructs of Virtual Reality (VR). We developed a simulated maintenance application to test virtual electrical devices. Participants performed test operations on these devices in a counterbalanced, randomized 2x2 between-subject design in either VR as congruent, or Augmented Reality (AR) as incongruent on the sensation/perception layer. Cognitive incongruency was induced by the absence of traceable power outages, decoupling perceived cause and effect after activating potentially defective devices. Our results indicate significant differences in the plausibility ratings between the VR and AR conditions, hence between congruent/incongruent conditions on the sensation/perception layer. In addition, spatial presence revealed a comparable interaction pattern with the VR vs AR conditions. Both factors decreased for the AR condition (incongruent sensation/perception) compared to VR (congruent sensation/perception) for the congruent cognitive case but increased for the incongruent cognitive case. The results are discussed and put into perspective in the scope of recent theories of MR experiences.

  @article{westermeier2023exploring, abstract = {Mixed Reality (MR) applications along Milgram's Reality-Virtuality (RV) continuum motivated a number of recent theories on potential constructs and factors describing MR experiences. This paper investigates the impact of incongruencies on the sensation/perception and cognition layers to provoke breaks in plausibility, and the effects these breaks have on spatial and overall presence as prominent constructs of Virtual Reality (VR). We developed a simulated maintenance application to test virtual electrical devices. Participants performed test operations on these devices in a counterbalanced, randomized 2x2 between-subject design in either VR as congruent, or Augmented Reality (AR) as incongruent on the sensation/perception layer. Cognitive incongruency was induced by the absence of traceable power outages, decoupling perceived cause and effect after activating potentially defective devices. Our results indicate significant differences in the plausibility ratings between the VR and AR conditions, hence between congruent/incongruent conditions on the sensation/perception layer. In addition, spatial presence revealed a comparable interaction pattern with the VR vs AR conditions. Both factors decreased for the AR condition (incongruent sensation/perception) compared to VR (congruent sensation/perception) for the congruent cognitive case but increased for the incongruent cognitive case. The results are discussed and put into perspective in the scope of recent theories of MR experiences.}, author = {Westermeier, Franziska and Brübach, Larissa and Latoschik, Marc Erich and Wienrich, Carolin}, journal = {IEEE Transactions on Visualization and Computer Graphics}, keywords = {xrhub}, month = {05}, note = {IEEE VR Best Paper Nominee 🏆}, number = 5, pages = {2680-2689}, title = {Exploring Plausibility and Presence in Mixed Reality Experiences}, volume = 29, year = 2023 }
• Moving Down the Stack: Performance Evaluation of Packet Processing Technologies for Stateful Firewalls. Dietz, Katharina; Gray, Nicholas; Wolz, Manuel; Lorenz, Claas; Hoßfeld, Tobias; Seufert, Michael. In 34th IEEE/IFIP Network Operations and Management Symposium (NOMS). Miami, Florida, 2023.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2023-2, address = {Miami, Florida}, author = {Dietz, Katharina and Gray, Nicholas and Wolz, Manuel and Lorenz, Claas and Hoßfeld, Tobias and Seufert, Michael}, booktitle = {34th IEEE/IFIP Network Operations and Management Symposium (NOMS)}, keywords = {ucn}, month = {05}, title = {Moving Down the Stack: Performance Evaluation of Packet Processing Technologies for Stateful Firewalls}, year = 2023 }
• Potentials and Limitations of Machine-Learning-supported Network Management for User-centric Communication Networks. Technical Report (PhD dissertation), . Seufert, Michael. PhD dissertation. University of Wuerzburg, 2023, May.
  • [ BibTeX ]
  @phdthesis{info3-habilitation-2023-1, author = {Seufert, Michael}, keywords = {myown}, month = {05}, school = {University of Wuerzburg}, title = {Potentials and Limitations of Machine-Learning-supported Network Management for User-centric Communication Networks}, year = 2023 }
• Collision and Energy Efficiency Assessment of LoRaWANs with Cluster-Based Gateway Placement. Loh, Frank; Baur, Carina; Geißler, Stefan; ElBakoury, Hesham; Hoßfeld, Tobias. In IEEE International Conference on Communications Workshops. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  LoRaWAN is one of the most prominent low power wide area network technologies. It offers long transmission distances with little energy consumption. The drawback is potential message collision. For that reason, recent literature discusses different alternatives to the currently used random channel access suffering from many message collisions and evaluates improvement possibilities. This is of major interest for network operators to future-proof LoRaWAN quality. One approach to reduce collision probability is cell size management via intelligent gateway placement. For that reason, this work presents an exhaustive study for k-means based clustering to distribute gateways. Different network quality metrics, namely full coverage for all sensors, collision probability, and energy efficiency, are evaluated. Thus, the contribution is a simple and scalable gateway placement approach for LoRaWAN. The performance evaluation shows a trade-off between placed gateways and energy efficiency. Furthermore, with reasonable runtime for large-scale networks, the clustering based approach is a viable solution for future network pre-planning or even final placement.

  @inproceedings{info3-inproceedings-2023-18, abstract = {LoRaWAN is one of the most prominent low power wide area network technologies. It offers long transmission distances with little energy consumption. The drawback is potential message collision. For that reason, recent literature discusses different alternatives to the currently used random channel access suffering from many message collisions and evaluates improvement possibilities. This is of major interest for network operators to future-proof LoRaWAN quality. One approach to reduce collision probability is cell size management via intelligent gateway placement. For that reason, this work presents an exhaustive study for k-means based clustering to distribute gateways. Different network quality metrics, namely full coverage for all sensors, collision probability, and energy efficiency, are evaluated. Thus, the contribution is a simple and scalable gateway placement approach for LoRaWAN. The performance evaluation shows a trade-off between placed gateways and energy efficiency. Furthermore, with reasonable runtime for large-scale networks, the clustering based approach is a viable solution for future network pre-planning or even final placement.}, author = {Loh, Frank and Baur, Carina and Geißler, Stefan and ElBakoury, Hesham and Hoßfeld, Tobias}, booktitle = {IEEE International Conference on Communications Workshops}, keywords = {myown}, month = {06}, title = {Collision and Energy Efficiency Assessment of LoRaWANs with Cluster-Based Gateway Placement}, year = 2023 }
• Machine Learning Based Study of QoE Metrics in Twitch. tv Live Streaming. Loh, Frank; Hildebrand, Kathrin; Wamser, Florian; Geißler, Stefan; Hoßfeld, Tobias. In IEEE/IFIP Network Operations and Management Symposium (NOMS). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Video streaming generates most network traffic in today’s Internet. For that reason, video on demand streaming is researched heavily in recent years, and many traffic monitoring mechanisms, flow and stream models, and models to predict the user perceived quality are well established. However, the quickly growing live streaming sector is not considered in these Quality of Experience models and not even the relation between network traffic and playback quality has been studied so far, forming a gap in literature. For that reason, we investigate Twitch.tv streaming as one of the largest live streaming platforms based on a large dataset and investigate the possibility to predict live streaming quality based on uplink request information. We apply approaches that are well studied for on demand streaming to predict quality changes, playback quality, and video interruption events as the most important metrics impairing user perceived quality. In this context, we answer whether these models are suitable for live streaming, if small changes are sufficient for satisfactory prediction results, or if fundamental changes and new models are required.

  @inproceedings{info3-inproceedings-2023-17, abstract = {Video streaming generates most network traffic in today’s Internet. For that reason, video on demand streaming is researched heavily in recent years, and many traffic monitoring mechanisms, flow and stream models, and models to predict the user perceived quality are well established. However, the quickly growing live streaming sector is not considered in these Quality of Experience models and not even the relation between network traffic and playback quality has been studied so far, forming a gap in literature. For that reason, we investigate Twitch.tv streaming as one of the largest live streaming platforms based on a large dataset and investigate the possibility to predict live streaming quality based on uplink request information. We apply approaches that are well studied for on demand streaming to predict quality changes, playback quality, and video interruption events as the most important metrics impairing user perceived quality. In this context, we answer whether these models are suitable for live streaming, if small changes are sufficient for satisfactory prediction results, or if fundamental changes and new models are required.}, author = {Loh, Frank and Hildebrand, Kathrin and Wamser, Florian and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {IEEE/IFIP Network Operations and Management Symposium (NOMS)}, keywords = {myown}, month = {05}, title = {Machine Learning Based Study of QoE Metrics in Twitch. tv Live Streaming}, year = 2023 }
• Segmentierung und Verlaufskontrolle chronischer Wunden durch künstliche Intelligenz mithilfe einer mobilen App (WUNDERKINT Studie). Borst, Vanessa; Dege, Tassilo; Grän, Franziska; Hamrouni, Sandra; Michel, Daniel; Hager, Valerie; Goebeler, Matthias; Leppich, Robert; Kounev, Samuel; Schmieder, Astrid. In Allergologie. JDDG: Journal der Deutschen Dermatologischen Gesellschaft, Vol. 21, pp. 28–177. John Wiley & Sons Ltd., 2023.
  • [ BibTeX ]
  • [ URL ]
  @incollection{borst_ddg23_v2, author = {Borst, Vanessa and Dege, Tassilo and Grän, Franziska and Hamrouni, Sandra and Michel, Daniel and Hager, Valerie and Goebeler, Matthias and Leppich, Robert and Kounev, Samuel and Schmieder, Astrid}, booktitle = {Allergologie. JDDG: Journal der Deutschen Dermatologischen Gesellschaft}, keywords = {t_poster}, month = {04}, note = {Poster Abstract (No. P322, pp. 175-176)}, number = {S1}, pages = {28-177}, publisher = {John Wiley & Sons Ltd.}, title = {Segmentierung und Verlaufskontrolle chronischer Wunden durch künstliche Intelligenz mithilfe einer mobilen App (WUNDERKINT Studie)}, volume = 21, year = 2023 }
• Segmentierung und Verlaufskontrolle chronischer Wunden durch künstliche Intelligenz mithilfe einer mobilen App (WUNDERKINT Studie). Borst, Vanessa; Dege, Tassilo; Grän, Franziska; Hamrouni, Sandra; Michel, Daniel; Hager, Valerie; Goebeler, Matthias; Leppich, Robert; Kounev, Samuel; Schmieder, Astrid. In Allergologie. JDDG: Journal der Deutschen Dermatologischen Gesellschaft, Vol. 21, pp. 28–177. John Wiley & Sons Ltd., 2023.
  • [ BibTeX ]
  • [ URL ]
  @incollection{borst_ddg23_v2, author = {Borst, Vanessa and Dege, Tassilo and Grän, Franziska and Hamrouni, Sandra and Michel, Daniel and Hager, Valerie and Goebeler, Matthias and Leppich, Robert and Kounev, Samuel and Schmieder, Astrid}, booktitle = {Allergologie. JDDG: Journal der Deutschen Dermatologischen Gesellschaft}, keywords = {t_poster}, month = {04}, note = {Poster Abstract (No. P322, pp. 175-176)}, number = {S1}, pages = {28-177}, publisher = {John Wiley & Sons Ltd.}, title = {Segmentierung und Verlaufskontrolle chronischer Wunden durch künstliche Intelligenz mithilfe einer mobilen App (WUNDERKINT Studie)}, volume = 21, year = 2023 }
• Segmentierung und Verlaufskontrolle chronischer Wunden durch künstliche Intelligenz mithilfe einer mobilen App (WUNDERKINT Studie). Borst, Vanessa; Dege, Tassilo; Grän, Franziska; Hamrouni, Sandra; Michel, Daniel; Hager, Valerie; Goebeler, Matthias; Leppich, Robert; Kounev, Samuel; Schmieder, Astrid. In Allergologie. JDDG: Journal der Deutschen Dermatologischen Gesellschaft, Vol. 21, pp. 28–177. John Wiley & Sons Ltd., 2023.
  • [ BibTeX ]
  • [ URL ]
  @incollection{borst_ddg23_v2, author = {Borst, Vanessa and Dege, Tassilo and Grän, Franziska and Hamrouni, Sandra and Michel, Daniel and Hager, Valerie and Goebeler, Matthias and Leppich, Robert and Kounev, Samuel and Schmieder, Astrid}, booktitle = {Allergologie. JDDG: Journal der Deutschen Dermatologischen Gesellschaft}, keywords = {t_poster}, month = {04}, note = {Poster Abstract (No. P322, pp. 175-176)}, number = {S1}, pages = {28-177}, publisher = {John Wiley & Sons Ltd.}, title = {Segmentierung und Verlaufskontrolle chronischer Wunden durch künstliche Intelligenz mithilfe einer mobilen App (WUNDERKINT Studie)}, volume = 21, year = 2023 }
• Harnessing the Potential of the Metaverse to Counter its Dangers. Wienrich, Carolin; Krauss, Jana; Polifke, Lukas; Horn, Viktoria; Bürger, Arne; Latoschik, Marc-Erich. 2023, April.
  • [ BibTeX ]
  @misc{wienrich2023harnessing, author = {Wienrich, Carolin and Krauss, Jana and Polifke, Lukas and Horn, Viktoria and Bürger, Arne and Latoschik, Marc-Erich}, howpublished = {Presented at workshop "Combating Toxicity, Harassment, and Abuse in Online Social Spaces: A Workshop at CHI 2023"}, keywords = {jkrauss}, month = {04}, title = {Harnessing the Potential of the Metaverse to Counter its Dangers}, year = 2023 }
• SPEC Research Group Newsletter, Issue 12. Kounev, Samuel; van Hoorn, Andre; Straesser, Martin; Bauer, Andr{é}. 2023, April.
  • [ BibTeX ]
  • [ URL ]
  @misc{SPEC-RG-NEWSLETTER-12, author = {Kounev, Samuel and van Hoorn, Andre and Straesser, Martin and Bauer, Andr{é}}, keywords = {SPEC}, month = {04}, note = {Published by Standard Performance Evaluation Corporation (SPEC)}, title = {SPEC Research Group Newsletter, Issue 12}, year = 2023 }
• Record, Review, Edit, Apply: A Motion Data Pipeline for Virtual Reality Development {\&} Design. Hofmann, Sarah; Özdemir, Cem; von Mammen, Sebastian. In Proceedings of the 18th International Conference on the Foundations of Digital Games. {ACM}, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Hofmann_2023, author = {Hofmann, Sarah and Özdemir, Cem and von Mammen, Sebastian}, booktitle = {Proceedings of the 18th International Conference on the Foundations of Digital Games}, keywords = {myown}, month = {04}, publisher = {{ACM}}, title = {Record, Review, Edit, Apply: A Motion Data Pipeline for Virtual Reality Development {\&} Design}, year = 2023 }
• {femtoPro}: virtual-reality interactive training simulator of an ultrafast laser laboratory. Brixner, Tobias; Mueller, Stefan; Müller, Andreas; Knote, Andreas; Schnepp, Wilhelm; Truman, Samuel; Vetter, Anne; von Mammen, Sebastian. In Applied Physics B, 129(5). Springer Science and Business Media {LLC}, 2023.
  • [ BibTeX ]
  • [ URL ]
  @article{Brixner_2023, author = {Brixner, Tobias and Mueller, Stefan and Müller, Andreas and Knote, Andreas and Schnepp, Wilhelm and Truman, Samuel and Vetter, Anne and von Mammen, Sebastian}, journal = {Applied Physics B}, keywords = {simulation}, month = {04}, number = 5, publisher = {Springer Science and Business Media {LLC}}, title = {{femtoPro}: virtual-reality interactive training simulator of an ultrafast laser laboratory}, volume = 129, year = 2023 }
• SPEC Research Group Newsletter, Issue 12. Kounev, Samuel; van Hoorn, Andre; Straesser, Martin; Bauer, Andr{é}. 2023, April.
  • [ BibTeX ]
  • [ URL ]
  @misc{SPEC-RG-NEWSLETTER-12, author = {Kounev, Samuel and van Hoorn, Andre and Straesser, Martin and Bauer, Andr{é}}, keywords = {SPEC}, month = {04}, note = {Published by Standard Performance Evaluation Corporation (SPEC)}, title = {SPEC Research Group Newsletter, Issue 12}, year = 2023 }
• On the Validity of Credit-Based Shaper Delay Guarantees in Decentralized Reservation Protocols. Maile, Lisa; Voitlein, Dominik; Grigorjew, Alexej; Hielscher, Kai-Steffen J.; German, Reinhard. In 31st International Conference on Real-Time Networks and Systems. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Resource reservation is a fundamental mechanism for ensuring quality of service in time-sensitive networks, which can be decentralized by using reservation protocols. In the Ethernet technology Time-Sensitive Networking, this has been proposed in conjunction with the Credit-Based Shaper. For the reservation, the standards assume a maximum worst-case latency bound at each hop. However, we will show through formal analysis and simulation that these worst-case latency bounds are not safe. To face this, we propose an extension to the current standards to allow the reservation of time-sensitive traffic with reliable latency guarantees. The effectiveness of our approach is demonstrated through simulations of both synthetic and industrial networks. Finally, by providing additional information about neighboring devices, we could further increase the maximum reservable traffic by up to 20% in our test cases.

  @inproceedings{info3-inproceedings-2023-5, abstract = {Resource reservation is a fundamental mechanism for ensuring quality of service in time-sensitive networks, which can be decentralized by using reservation protocols. In the Ethernet technology Time-Sensitive Networking, this has been proposed in conjunction with the Credit-Based Shaper. For the reservation, the standards assume a maximum worst-case latency bound at each hop. However, we will show through formal analysis and simulation that these worst-case latency bounds are not safe. To face this, we propose an extension to the current standards to allow the reservation of time-sensitive traffic with reliable latency guarantees. The effectiveness of our approach is demonstrated through simulations of both synthetic and industrial networks. Finally, by providing additional information about neighboring devices, we could further increase the maximum reservable traffic by up to 20% in our test cases.}, author = {Maile, Lisa and Voitlein, Dominik and Grigorjew, Alexej and Hielscher, Kai-Steffen J. and German, Reinhard}, booktitle = {31st International Conference on Real-Time Networks and Systems}, keywords = {can}, month = {06}, title = {On the Validity of Credit-Based Shaper Delay Guarantees in Decentralized Reservation Protocols}, year = 2023 }
• Explainable Data-Driven QoE Modelling using XAI. Wehner, Nikolas; Seufert, Anika; Hoßfeld, Tobias; Seufert, Michael. In 15th International Conference on Quality of Multimedia Experience (QoMEX). Ghent, Belgium, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Data-driven QoE modelling using Machine Learning (ML) allows to reduce the modelling bias and to continuously integrate new QoE results into the QoE model, which can improve its generalizability. The downside is that the majority of ML models are black-box models, which prevent to obtain insights about QoE influence factors and their fundamental relationships that are highly relevant for researchers and providers of services and networks. However, recent advances in the field of eXplainable Artificial Intelligence (XAI) resolve these issues. Thus, XAI allows to benefit from data-driven QoE modelling to obtain generalizable QoE models, and at the same time to understand what QoE factors are relevant and how they affect the QoE score. In this work, we showcase the feasibility of explainable data-driven QoE modelling for video streaming, since video streaming QoE has been well researched, and thus, allows us to validate our results. Finally, we discuss opportunities and challenges of deploying XAI for QoE modelling.

  @inproceedings{info3-inproceedings-2023-4, abstract = {Data-driven QoE modelling using Machine Learning (ML) allows to reduce the modelling bias and to continuously integrate new QoE results into the QoE model, which can improve its generalizability. The downside is that the majority of ML models are black-box models, which prevent to obtain insights about QoE influence factors and their fundamental relationships that are highly relevant for researchers and providers of services and networks. However, recent advances in the field of eXplainable Artificial Intelligence (XAI) resolve these issues. Thus, XAI allows to benefit from data-driven QoE modelling to obtain generalizable QoE models, and at the same time to understand what QoE factors are relevant and how they affect the QoE score. In this work, we showcase the feasibility of explainable data-driven QoE modelling for video streaming, since video streaming QoE has been well researched, and thus, allows us to validate our results. Finally, we discuss opportunities and challenges of deploying XAI for QoE modelling.}, address = {Ghent, Belgium}, author = {Wehner, Nikolas and Seufert, Anika and Hoßfeld, Tobias and Seufert, Michael}, booktitle = {15th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ucn}, month = {06}, title = {Explainable Data-Driven QoE Modelling using XAI}, year = 2023 }
• Virtual-to-Physical Surface Alignment and Refinement Techniques for Handwriting, Sketching, and Selection in XR. Kern, Florian; Tschanter, Jonathan; Latoschik, Marc Erich. In 2023 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW), pp. 502–506. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The alignment of virtual to physical surfaces is essential to improve symbolic input and selection in XR. Previous techniques optimized for efficiency can lead to inaccuracies. We investigate regression-based refinement techniques and introduce a surface accuracy eval-uation. The results revealed that refinement techniques can highly improve surface accuracy and show that accuracy depends on the gesture shape and surface dimension. Our reference implementation and dataset are publicly available.

  @inproceedings{10108564, abstract = {The alignment of virtual to physical surfaces is essential to improve symbolic input and selection in XR. Previous techniques optimized for efficiency can lead to inaccuracies. We investigate regression-based refinement techniques and introduce a surface accuracy eval-uation. The results revealed that refinement techniques can highly improve surface accuracy and show that accuracy depends on the gesture shape and surface dimension. Our reference implementation and dataset are publicly available.}, author = {Kern, Florian and Tschanter, Jonathan and Latoschik, Marc Erich}, booktitle = {2023 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {vilearn}, month = {03}, pages = {502-506}, title = {Virtual-to-Physical Surface Alignment and Refinement Techniques for Handwriting, Sketching, and Selection in XR}, year = 2023 }
• Self-Aware Optimization of Adaptation Planning Strategies. Lesch, Veronika; Hadry, Marius; Krupitzer, Christian; Kounev, Samuel. In ACM Transactions on Autonomous and Adaptive Systems, 18(3). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In today’s world, circumstances, processes, and requirements for software systems are becoming increasingly complex. In order to operate properly in such dynamic environments, software systems must adapt to these changes, which has led to the research area of Self-Adaptive Systems (SAS). Platooning is one example of adaptive systems in Intelligent Transportation Systems, which is the ability of vehicles to travel with close inter-vehicle distances. This technology leads to an increase in road throughput and safety, which directly addresses the increased infrastructure needs due to increased traffic on the roads. However, the No-Free-Lunch theorem states that the performance of one adaptation planning strategy is not necessarily transferable to other problems. Moreover, especially in the field of SAS, the selection of the most appropriate strategy depends on the current situation of the system. In this paper, we address the problem of self-aware optimization of adaptation planning strategies by designing a framework that includes situation detection, strategy selection, and parameter optimization of the selected strategies. We apply our approach on the case study platooning coordination and evaluate the performance of the proposed framework.

  @article{lesch2022selfaware, abstract = {In today’s world, circumstances, processes, and requirements for software systems are becoming increasingly complex. In order to operate properly in such dynamic environments, software systems must adapt to these changes, which has led to the research area of Self-Adaptive Systems (SAS). Platooning is one example of adaptive systems in Intelligent Transportation Systems, which is the ability of vehicles to travel with close inter-vehicle distances. This technology leads to an increase in road throughput and safety, which directly addresses the increased infrastructure needs due to increased traffic on the roads. However, the No-Free-Lunch theorem states that the performance of one adaptation planning strategy is not necessarily transferable to other problems. Moreover, especially in the field of SAS, the selection of the most appropriate strategy depends on the current situation of the system. In this paper, we address the problem of self-aware optimization of adaptation planning strategies by designing a framework that includes situation detection, strategy selection, and parameter optimization of the selected strategies. We apply our approach on the case study platooning coordination and evaluate the performance of the proposed framework.}, author = {Lesch, Veronika and Hadry, Marius and Krupitzer, Christian and Kounev, Samuel}, journal = {ACM Transactions on Autonomous and Adaptive Systems}, keywords = {self-awareness}, month = {09}, number = 3, title = {Self-Aware Optimization of Adaptation Planning Strategies}, volume = 18, year = 2023 }
• Liquor-HGNN: A heterogeneous graph neural network for leakage detection in water distribution networks. "Schaller, Melanie"; "Steininger, Michael"; "Dulny, Andrzej"; "Schlör, Daniel"; "Hotho, Andreas". In LWDA’23: Lernen, Wissen, Daten, Analysen. October 09--11, 2023, Marburg, Germany, M. Leyer (ed.). 2023.
  • [ BibTeX ]
  @article{schaller2023liquorhgnn, author = {"Schaller, Melanie" and "Steininger, Michael" and "Dulny, Andrzej" and "Schlör, Daniel" and "Hotho, Andreas"}, editor = {Leyer, M.}, journal = {LWDA'23: Lernen, Wissen, Daten, Analysen. October 09–11, 2023, Marburg, Germany}, keywords = {from:manli}, month = {Oktober}, title = {Liquor-HGNN: A heterogeneous graph neural network for leakage detection in water distribution networks}, year = 2023 }
• ConvMOS: climate model output statistics with deep learning. Steininger, Michael; Abel, Daniel; Ziegler, Katrin; Krause, Anna; Paeth, Heiko; Hotho, Andreas. In Data Mining and Knowledge Discovery, 37(1), pp. 136–166. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Climate models are the tool of choice for scientists researching climate change. Like all models they suffer from errors, particularly systematic and location-specific representation errors. One way to reduce these errors is model output statistics (MOS) where the model output is fitted to observational data with machine learning. In this work, we assess the use of convolutional Deep Learning climate MOS approaches and present the ConvMOS architecture which is specifically designed based on the observation that there are systematic and location-specific errors in the precipitation estimates of climate models. We apply ConvMOS models to the simulated precipitation of the regional climate model REMO, showing that a combination of per-location model parameters for reducing location-specific errors and global model parameters for reducing systematic errors is indeed beneficial for MOS performance. We find that ConvMOS models can reduce errors considerably and perform significantly better than three commonly used MOS approaches and plain ResNet and U-Net models in most cases. Our results show that non-linear MOS models underestimate the number of extreme precipitation events, which we alleviate by training models specialized towards extreme precipitation events with the imbalanced regression method DenseLoss. While we consider climate MOS, we argue that aspects of ConvMOS may also be beneficial in other domains with geospatial data, such as air pollution modeling or weather forecasts.

  @article{steininger2023convmos, abstract = {Climate models are the tool of choice for scientists researching climate change. Like all models they suffer from errors, particularly systematic and location-specific representation errors. One way to reduce these errors is model output statistics (MOS) where the model output is fitted to observational data with machine learning. In this work, we assess the use of convolutional Deep Learning climate MOS approaches and present the ConvMOS architecture which is specifically designed based on the observation that there are systematic and location-specific errors in the precipitation estimates of climate models. We apply ConvMOS models to the simulated precipitation of the regional climate model REMO, showing that a combination of per-location model parameters for reducing location-specific errors and global model parameters for reducing systematic errors is indeed beneficial for MOS performance. We find that ConvMOS models can reduce errors considerably and perform significantly better than three commonly used MOS approaches and plain ResNet and U-Net models in most cases. Our results show that non-linear MOS models underestimate the number of extreme precipitation events, which we alleviate by training models specialized towards extreme precipitation events with the imbalanced regression method DenseLoss. While we consider climate MOS, we argue that aspects of ConvMOS may also be beneficial in other domains with geospatial data, such as air pollution modeling or weather forecasts.}, author = {Steininger, Michael and Abel, Daniel and Ziegler, Katrin and Krause, Anna and Paeth, Heiko and Hotho, Andreas}, journal = {Data Mining and Knowledge Discovery}, keywords = {selected}, number = 1, pages = {136–166}, title = {ConvMOS: climate model output statistics with deep learning}, volume = 37, year = 2023 }
• De Bello Homomorphico: Investigation of the extensibility of the OpenFHE library with basic mathematical functions by means of common approaches using the example of the CKKS cryptosystem. Prantl, Thomas; Horn, Lukas; Engel, Simon; Iffländer, Lukas; Beierlieb, Lukas; Krupitzer, Christian; Bauer, André; Sakarvadia, Mansi; Foster, Ian; Kounev, Samuel. In International Journal of Information Security. 2023.
  • [ BibTeX ]
  @article{PrHoEnIfBeKrBaSaFoKo_IJoIS_SGC_Pareto, author = {Prantl, Thomas and Horn, Lukas and Engel, Simon and Iffl\"ander, Lukas and Beierlieb, Lukas and Krupitzer, Christian and Bauer, Andr\'e and Sakarvadia, Mansi and Foster, Ian and Kounev, Samuel}, journal = {International Journal of Information Security}, keywords = {t_journalmagazine}, month = 11, title = {De Bello Homomorphico: Investigation of the extensibility of the OpenFHE library with basic mathematical functions by means of common approaches using the example of the CKKS cryptosystem}, year = 2023 }
• De Bello Homomorphico: Investigation of the extensibility of the OpenFHE library with basic mathematical functions by means of common approaches using the example of the CKKS cryptosystem. Prantl, Thomas; Horn, Lukas; Engel, Simon; Iffländer, Lukas; Beierlieb, Lukas; Krupitzer, Christian; Bauer, André; Sakarvadia, Mansi; Foster, Ian; Kounev, Samuel. In International Journal of Information Security. 2023.
  • [ BibTeX ]
  @article{PrHoEnIfBeKrBaSaFoKo_IJoIS_SGC_Pareto, author = {Prantl, Thomas and Horn, Lukas and Engel, Simon and Iffl\"ander, Lukas and Beierlieb, Lukas and Krupitzer, Christian and Bauer, Andr\'e and Sakarvadia, Mansi and Foster, Ian and Kounev, Samuel}, journal = {International Journal of Information Security}, keywords = {t_journalmagazine}, month = 11, title = {De Bello Homomorphico: Investigation of the extensibility of the OpenFHE library with basic mathematical functions by means of common approaches using the example of the CKKS cryptosystem}, year = 2023 }
• Time Perception Research in Virtual Reality: Lessons Learned. Landeck, Maximilian; Unruh, Fabian; Lugrin, Jean-Luc; Latoschik, Marc Erich. In Mensch und Computer 2023, Mensch und Computer 2023 . Veröffentlicht durch die Gesellschaft für Informatik e.V. in P. Fröhlich & V. Cobus (Hrsg.), 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In this article, we present a selection of recent studies from our research group that investigated the relationship between time perception and virtual reality (VR). We focus on the influence of avatar embodiment, visual fidelity, motion perception, and body representation. We summarize findings on the impact of these factors on time perception, discuss lessons learned, and implications for future applications. In a waiting room experiment, the passage of time in VR with an avatar was perceived significantly faster than without an avatar. The passage of time in the real waiting room was not perceived as significantly different from the waiting room in VR with or without an avatar. In an interactive scenario, the absence of a virtual avatar resulted in a significantly slower perceived passage of time compared to the partial and full-body avatar conditions. High and medium embodiment conditions are assumed to be more plausible and to less different from a real experience. A virtual tunnel that induced the illusion of self-motion (vection) appeared to contribute to the perceived passage of time and experience of time. This effect was shown to increase with tunnel speed and the number of tunnel segments. A framework was proposed for the use of virtual zeitgebers along three dimensions (speed, density, synchronicity) to systematically control the experience of time. The body itself, as well as external objects, seem to be addressed by this theory of virtual zeitgebers. Finally, the standardization of the methodology and future research considerations are discussed.

  @inproceedings{landeck2023perception, abstract = {In this article, we present a selection of recent studies from our research group that investigated the relationship between time perception and virtual reality (VR). We focus on the influence of avatar embodiment, visual fidelity, motion perception, and body representation. We summarize findings on the impact of these factors on time perception, discuss lessons learned, and implications for future applications. In a waiting room experiment, the passage of time in VR with an avatar was perceived significantly faster than without an avatar. The passage of time in the real waiting room was not perceived as significantly different from the waiting room in VR with or without an avatar. In an interactive scenario, the absence of a virtual avatar resulted in a significantly slower perceived passage of time compared to the partial and full-body avatar conditions. High and medium embodiment conditions are assumed to be more plausible and to less different from a real experience. A virtual tunnel that induced the illusion of self-motion (vection) appeared to contribute to the perceived passage of time and experience of time. This effect was shown to increase with tunnel speed and the number of tunnel segments. A framework was proposed for the use of virtual zeitgebers along three dimensions (speed, density, synchronicity) to systematically control the experience of time. The body itself, as well as external objects, seem to be addressed by this theory of virtual zeitgebers. Finally, the standardization of the methodology and future research considerations are discussed.}, author = {Landeck, Maximilian and Unruh, Fabian and Lugrin, Jean-Luc and Latoschik, Marc Erich}, booktitle = {Mensch und Computer 2023}, edition = {Mensch und Computer 2023}, keywords = {landeck}, month = {09}, organization = {Gesellschaft für Informatik e.V.}, publisher = {Veröffentlicht durch die Gesellschaft für Informatik e.V. in P. Fröhlich & V. Cobus (Hrsg.)}, title = {Time Perception Research in Virtual Reality: Lessons Learned}, type = {workshop band}, year = 2023 }
• Demystifying User-based Active Learning for Network Monitoring Tasks. Dietz, Katharina; Wehner, Nikolas; Casas, Pedro; Hoßfeld, Tobias; Seufert, Michael. In 2nd Workshop on Machine Learning & Networking (MaLeNe) as part of NetSys’23. Potsdam, Germany, 2023.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2023-9, address = {Potsdam, Germany}, author = {Dietz, Katharina and Wehner, Nikolas and Casas, Pedro and Hoßfeld, Tobias and Seufert, Michael}, booktitle = {2nd Workshop on Machine Learning & Networking (MaLeNe) as part of NetSys'23}, keywords = {ucn}, month = {09}, title = {Demystifying User-based Active Learning for Network Monitoring Tasks}, year = 2023 }
• Discrete-Time Analysis of Multi-Component Queuing Networks under Renewal Approximation. Geißler, Stefan; Lange, Stanislav; Hasslinger, Gerhard; Tran-Gia, Phuoc; Hoßfeld, Tobias. In 34th International Teletraffic Congress (ITC). Shenzhen, China. 2023.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2023-1, author = {Geißler, Stefan and Lange, Stanislav and Hasslinger, Gerhard and Tran-Gia, Phuoc and Hoßfeld, Tobias}, booktitle = {34th International Teletraffic Congress (ITC). Shenzhen, China}, keywords = {myown}, month = {09}, title = {Discrete-Time Analysis of Multi-Component Queuing Networks under Renewal Approximation}, year = 2023 }
• Developing a Library of Problem Scenarios for Time-Sensitive and Real-Time Networking. Grigorjew, Alexej; Vomhoff, Viktoria; Geißler, Stefan; Diederich, Philip; Hoßfeld, Tobias; Kellerer, Wolfgang. In International Conference on Networked Systems 2023 (NetSys). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  The lack of realistic problem instances is one of the major challenges when it comes to evaluating and comparing mechanisms and approaches in the area of real-time networking. To this end, we aim at establishing a library of general as well as use case specific scenarios including different network topologies and traffic streams with the goal of promoting comparability among research works and facilitate the development of innovative approaches. We present our foundational framework for the generation of these synthetic problem instances and call on the community to contribute their experiences and insights.

  @inproceedings{info3-inproceedings-2023-15, abstract = {The lack of realistic problem instances is one of the major challenges when it comes to evaluating and comparing mechanisms and approaches in the area of real-time networking. To this end, we aim at establishing a library of general as well as use case specific scenarios including different network topologies and traffic streams with the goal of promoting comparability among research works and facilitate the development of innovative approaches. We present our foundational framework for the generation of these synthetic problem instances and call on the community to contribute their experiences and insights.}, author = {Grigorjew, Alexej and Vomhoff, Viktoria and Geißler, Stefan and Diederich, Philip and Hoßfeld, Tobias and Kellerer, Wolfgang}, booktitle = {International Conference on Networked Systems 2023 (NetSys)}, keywords = {appaware2}, month = {09}, title = {Developing a Library of Problem Scenarios for Time-Sensitive and Real-Time Networking}, year = 2023 }
• Resilience in Time-Sensitive Networking: An Overview and Open Research Directions. Grigorjew, Alexej; Geißler, Stefan; Diederich, Philip; Hoßfeld, Tobias; Kellerer, Wolfgang. In 2023 13th International Workshop on Resilient Networks Design and Modeling (RNDM). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Time-Sensitive Networking (TSN) puts stringent requirements on its devices to provide deterministic services over Ethernet-based networks. Resilience is an important attribute for TSN to achieve dependable time-sensitive data transmission. Existing literature on resilience of TSN mostly focuses on a particular subset of TSN mechanisms for resilience analysis. This paper takes an overall systems viewpoint and analyzes the resilience in TSN systems provided by the interaction of multiple mechanisms. It discusses their dependencies, possible faults, and possible mitigations of a selected subset of standards. Thereby, it highlights open challenges for future research directions.

  @inproceedings{info3-inproceedings-2023-13, abstract = {Time-Sensitive Networking (TSN) puts stringent requirements on its devices to provide deterministic services over Ethernet-based networks. Resilience is an important attribute for TSN to achieve dependable time-sensitive data transmission. Existing literature on resilience of TSN mostly focuses on a particular subset of TSN mechanisms for resilience analysis. This paper takes an overall systems viewpoint and analyzes the resilience in TSN systems provided by the interaction of multiple mechanisms. It discusses their dependencies, possible faults, and possible mitigations of a selected subset of standards. Thereby, it highlights open challenges for future research directions.}, author = {Grigorjew, Alexej and Geißler, Stefan and Diederich, Philip and Hoßfeld, Tobias and Kellerer, Wolfgang}, booktitle = {2023 13th International Workshop on Resilient Networks Design and Modeling (RNDM)}, keywords = {appaware2}, month = {09}, title = {Resilience in Time-Sensitive Networking: An Overview and Open Research Directions}, year = 2023 }
• Want more WANs? Comparison of Traditional and GAN-based Generation of Wide Area Network Topologies via Graph and Performance Metrics. Dietz, Katharina; Seufert, Michael; Hoßfeld, Tobias. In Transactions on Network and Service Management (TNSM). 2023.
  • [ BibTeX ]
  @article{info3-article-2023-5, author = {Dietz, Katharina and Seufert, Michael and Hoßfeld, Tobias}, journal = {Transactions on Network and Service Management (TNSM)}, keywords = {ucn}, month = {07}, title = {Want more WANs? Comparison of Traditional and GAN-based Generation of Wide Area Network Topologies via Graph and Performance Metrics}, year = 2023 }
• Self-Aware Optimization of Adaptation Planning Strategies. Lesch, Veronika; Hadry, Marius; Krupitzer, Christian; Kounev, Samuel. In ACM Transactions on Autonomous and Adaptive Systems, 18(3). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In today’s world, circumstances, processes, and requirements for software systems are becoming increasingly complex. In order to operate properly in such dynamic environments, software systems must adapt to these changes, which has led to the research area of Self-Adaptive Systems (SAS). Platooning is one example of adaptive systems in Intelligent Transportation Systems, which is the ability of vehicles to travel with close inter-vehicle distances. This technology leads to an increase in road throughput and safety, which directly addresses the increased infrastructure needs due to increased traffic on the roads. However, the No-Free-Lunch theorem states that the performance of one adaptation planning strategy is not necessarily transferable to other problems. Moreover, especially in the field of SAS, the selection of the most appropriate strategy depends on the current situation of the system. In this paper, we address the problem of self-aware optimization of adaptation planning strategies by designing a framework that includes situation detection, strategy selection, and parameter optimization of the selected strategies. We apply our approach on the case study platooning coordination and evaluate the performance of the proposed framework.

  @article{lesch2022selfaware, abstract = {In today’s world, circumstances, processes, and requirements for software systems are becoming increasingly complex. In order to operate properly in such dynamic environments, software systems must adapt to these changes, which has led to the research area of Self-Adaptive Systems (SAS). Platooning is one example of adaptive systems in Intelligent Transportation Systems, which is the ability of vehicles to travel with close inter-vehicle distances. This technology leads to an increase in road throughput and safety, which directly addresses the increased infrastructure needs due to increased traffic on the roads. However, the No-Free-Lunch theorem states that the performance of one adaptation planning strategy is not necessarily transferable to other problems. Moreover, especially in the field of SAS, the selection of the most appropriate strategy depends on the current situation of the system. In this paper, we address the problem of self-aware optimization of adaptation planning strategies by designing a framework that includes situation detection, strategy selection, and parameter optimization of the selected strategies. We apply our approach on the case study platooning coordination and evaluate the performance of the proposed framework.}, author = {Lesch, Veronika and Hadry, Marius and Krupitzer, Christian and Kounev, Samuel}, journal = {ACM Transactions on Autonomous and Adaptive Systems}, keywords = {self-awareness}, month = {09}, number = 3, title = {Self-Aware Optimization of Adaptation Planning Strategies}, volume = 18, year = 2023 }
• Accurate Live Visualization of Packet Delays, Inter-Arrival Times, and Burstiness for Real-Time Networks. Grigorjew, Alexej; Geißler, Stefan; Ziegler, Maximilian; Schumann, Lukas Kilian; Diederich, Philip; Hock, David; Hoßfeld, Tobias; Kellerer, Wolfgang. In International Conference on Networked Systems 2023 (NetSys). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  In this demonstration, a live delay and traffic volume visualization is presented. It is created with consumer off-the-shelf components, provides sub-microsecond accuracy, and provides sufficient performance for line rate measurements without sampling. The tool can help to accelerate the development and operation of real-time networks.

  @inproceedings{info3-inproceedings-2023-14, abstract = {In this demonstration, a live delay and traffic volume visualization is presented. It is created with consumer off-the-shelf components, provides sub-microsecond accuracy, and provides sufficient performance for line rate measurements without sampling. The tool can help to accelerate the development and operation of real-time networks.}, author = {Grigorjew, Alexej and Geißler, Stefan and Ziegler, Maximilian and Schumann, Lukas Kilian and Diederich, Philip and Hock, David and Hoßfeld, Tobias and Kellerer, Wolfgang}, booktitle = {International Conference on Networked Systems 2023 (NetSys)}, keywords = {kosinu5}, month = {09}, title = {Accurate Live Visualization of Packet Delays, Inter-Arrival Times, and Burstiness for Real-Time Networks}, year = 2023 }
• MAILS - Meta AI Literacy Scale: Development and Testing of an AI Literacy Questionnaire Based on Well-Founded Competency Models and Psychological Change- and Meta-Competencies. Carolus, Astrid; Koch, Martin J.; Straka, Samantha; Latoschik, Marc Erich; Wienrich, Carolin. In Computers in Human Behavior: Artificial Humans, 1(2), p. 100014. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Valid measurement of AI literacy is important for the selection of personnel, identification of shortages in skill and knowledge, and evaluation of AI literacy interventions. A questionnaire is missing that is deeply grounded in the existing literature on AI literacy, is modularly applicable depending on the goals, and includes further psychological competencies in addition to the typical facets of AIL. This paper presents the development and validation of a questionnaire considering the desiderata described above. We derived items to represent different facets of AI literacy and psychological competencies, such as problem-solving, learning, and emotion regulation in regard to AI. We collected data from 300 German-speaking adults to confirm the factorial structure. The result is the Meta AI Literacy Scale (MAILS) for AI literacy with the facets Use & apply AI, Understand AI, Detect AI, and AI Ethics and the ability to Create AI as a separate construct, and AI Self-efficacy in learning and problem-solving and AI Self-management (i.e., AI persuasion literacy and emotion regulation). This study contributes to the research on AI literacy by providing a measurement instrument relying on profound competency models. Psy­ chological competencies are included particularly important in the context of pervasive change through AI systems.

  @article{carolus2023mails, abstract = {Valid measurement of AI literacy is important for the selection of personnel, identification of shortages in skill and knowledge, and evaluation of AI literacy interventions. A questionnaire is missing that is deeply grounded in the existing literature on AI literacy, is modularly applicable depending on the goals, and includes further psychological competencies in addition to the typical facets of AIL. This paper presents the development and validation of a questionnaire considering the desiderata described above. We derived items to represent different facets of AI literacy and psychological competencies, such as problem-solving, learning, and emotion regulation in regard to AI. We collected data from 300 German-speaking adults to confirm the factorial structure. The result is the Meta AI Literacy Scale (MAILS) for AI literacy with the facets Use & apply AI, Understand AI, Detect AI, and AI Ethics and the ability to Create AI as a separate construct, and AI Self-efficacy in learning and problem-solving and AI Self-management (i.e., AI persuasion literacy and emotion regulation). This study contributes to the research on AI literacy by providing a measurement instrument relying on profound competency models. Psy­ chological competencies are included particularly important in the context of pervasive change through AI systems.}, author = {Carolus, Astrid and Koch, Martin J. and Straka, Samantha and Latoschik, Marc Erich and Wienrich, Carolin}, journal = {Computers in Human Behavior: Artificial Humans}, keywords = {aiatwork}, month = {08}, number = 2, pages = 100014, title = {MAILS - Meta AI Literacy Scale: Development and Testing of an AI Literacy Questionnaire Based on Well-Founded Competency Models and Psychological Change- and Meta-Competencies}, type = {Publication}, volume = 1, year = 2023 }
• MVNOCoreSim: A Digital Twin for Virtualized IoT-centric Mobile Core Networks. Geissler, Stefan; Wamser, Florian; Bauer, Wolfgang; Gebert, Steffen; Kounev, Samuel; Hossfeld, Tobias. In IEEE Internet of Things, 10(15), pp. 13974–13987. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The rapid growth of connected devices has led to the implementation of IoT-centric platforms designed to provide connectivity for machine-to-machine type communication. Specifically, mobile virtual network operators (MVNOs) provide global service for IoT use cases by leveraging roaming in readily deployed physical networks. This global deployment of connected devices poses a significant challenge regarding the operation of centralized core networks with respect to dimensioning, scaling as well as system survivability in case of signaling incidents. Overload control mechanisms for IoT mobile networks offer a proactive solution for mitigating excessive signaling traffic from IoT devices in mobile core networks. However, global scaling and a heterogeneous composition of devices present network operators with additional challenges. To address these challenges, this work presents a detailed, protocol level simulation framework of a real-world IoT MVNO core network. We present both models for the expected IoT signaling load and the processing of signaling messages based on measurements in a live, production environment as well as a dedicated testbed. Finally, we present a case study on various overload mechanisms and identify critical performance characteristics to compare their performance. The results of this study categorize overload control mechanisms and shed light on the necessity for MVNOs to deal with the upcoming IoT traffic by defining appropriate overload control mechanisms in mobile core networks to ensure network survivability under unforeseen conditions.

  @article{geissler2023mvnocoresim, abstract = {The rapid growth of connected devices has led to the implementation of IoT-centric platforms designed to provide connectivity for machine-to-machine type communication. Specifically, mobile virtual network operators (MVNOs) provide global service for IoT use cases by leveraging roaming in readily deployed physical networks. This global deployment of connected devices poses a significant challenge regarding the operation of centralized core networks with respect to dimensioning, scaling as well as system survivability in case of signaling incidents. Overload control mechanisms for IoT mobile networks offer a proactive solution for mitigating excessive signaling traffic from IoT devices in mobile core networks. However, global scaling and a heterogeneous composition of devices present network operators with additional challenges. To address these challenges, this work presents a detailed, protocol level simulation framework of a real-world IoT MVNO core network. We present both models for the expected IoT signaling load and the processing of signaling messages based on measurements in a live, production environment as well as a dedicated testbed. Finally, we present a case study on various overload mechanisms and identify critical performance characteristics to compare their performance. The results of this study categorize overload control mechanisms and shed light on the necessity for MVNOs to deal with the upcoming IoT traffic by defining appropriate overload control mechanisms in mobile core networks to ensure network survivability under unforeseen conditions.}, author = {Geissler, Stefan and Wamser, Florian and Bauer, Wolfgang and Gebert, Steffen and Kounev, Samuel and Hossfeld, Tobias}, journal = {IEEE Internet of Things}, keywords = {t_journalmagazine}, month = {08}, number = 15, pages = {13974-13987}, title = {MVNOCoreSim: A Digital Twin for Virtualized IoT-centric Mobile Core Networks}, volume = 10, year = 2023 }
• Serverless Computing: What It Is, and What It Is Not?. Kounev, Samuel; Herbst, Nikolas; Abad, Cristina L.; Iosup, Alexandru; Foster, Ian; Shenoy, Prashant; Rana, Omer; Chien, Andrew A. In Commun. ACM, 66(9), pp. 80–92. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Dispelling the confusion around serverless computing by capturing its essential and conceptual characteristics.

  @article{10.1145/3587249, abstract = {Dispelling the confusion around serverless computing by capturing its essential and conceptual characteristics.}, address = {New York, NY, USA}, author = {Kounev, Samuel and Herbst, Nikolas and Abad, Cristina L. and Iosup, Alexandru and Foster, Ian and Shenoy, Prashant and Rana, Omer and Chien, Andrew A.}, journal = {Commun. ACM}, keywords = {t_journalmagazine}, month = {08}, number = 9, pages = {80–92}, publisher = {Association for Computing Machinery}, title = {Serverless Computing: What It Is, and What It Is Not?}, volume = 66, year = 2023 }
• Serverless Computing: What It Is, and What It Is Not?. Kounev, Samuel; Herbst, Nikolas; Abad, Cristina L.; Iosup, Alexandru; Foster, Ian; Shenoy, Prashant; Rana, Omer; Chien, Andrew A. In Commun. ACM, 66(9), pp. 80–92. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Dispelling the confusion around serverless computing by capturing its essential and conceptual characteristics.

  @article{10.1145/3587249, abstract = {Dispelling the confusion around serverless computing by capturing its essential and conceptual characteristics.}, address = {New York, NY, USA}, author = {Kounev, Samuel and Herbst, Nikolas and Abad, Cristina L. and Iosup, Alexandru and Foster, Ian and Shenoy, Prashant and Rana, Omer and Chien, Andrew A.}, journal = {Commun. ACM}, keywords = {t_journalmagazine}, month = {08}, number = 9, pages = {80–92}, publisher = {Association for Computing Machinery}, title = {Serverless Computing: What It Is, and What It Is Not?}, volume = 66, year = 2023 }
• Baked Burger Bash: A Serious Virtual Reality Game Informing about the Effects of Acute Cannabinoid Intoxication. Vetter, Anne; Büttner, Johannes; von Mammen, Sebastian. In 2023 IEEE Conference on Games (CoG), pp. 1–4. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  This paper presents Baked Burger Bash, a serious game that aims to enhance a drug prevention program for adolescents using virtual reality (VR). The game is based on a simulation of acute cannabinoid intoxication embedded in an interactive cooking game. The player takes on the role of a food truck chef who needs to serve up the orders of passers-by. Various effects of intoxication make it hard to live up to the customers’ expectations. In this paper, we present the scientific background, insights from formative playtests, and feedback from a drug prevention expert who guided the iterative development.

  @inproceedings{10333198, abstract = {This paper presents Baked Burger Bash, a serious game that aims to enhance a drug prevention program for adolescents using virtual reality (VR). The game is based on a simulation of acute cannabinoid intoxication embedded in an interactive cooking game. The player takes on the role of a food truck chef who needs to serve up the orders of passers-by. Various effects of intoxication make it hard to live up to the customers’ expectations. In this paper, we present the scientific background, insights from formative playtests, and feedback from a drug prevention expert who guided the iterative development.}, author = {Vetter, Anne and Büttner, Johannes and von Mammen, Sebastian}, booktitle = {2023 IEEE Conference on Games (CoG)}, keywords = {myown}, month = {08}, pages = {1-4}, title = {Baked Burger Bash: A Serious Virtual Reality Game Informing about the Effects of Acute Cannabinoid Intoxication}, year = 2023 }
• Engineering Surrogate Models for Boid Systems. {von Pichowski}, Jan; {von Mammen}, Sebastian. In Proceedings of ALIFE 2023, pp. 102–110. MIT Press, Sapporo, Japan, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{von-Pichowski:2023aa, address = {Sapporo, Japan}, author = {{von Pichowski}, Jan and {von Mammen}, Sebastian}, booktitle = {Proceedings of ALIFE 2023}, keywords = {myown}, month = {07}, pages = {102-110}, publisher = {MIT Press}, title = {Engineering Surrogate Models for Boid Systems}, year = 2023 }
• Zero-Shot Clickbait Spoiling by Rephrasing Titles as Questions. Wangsadirdja, Dirk; Pfister, Jan; Kobs, Konstantin; Hotho, Andreas. In Proceedings of the The 17th International Workshop on Semantic Evaluation (SemEval-2023), pp. 1090–1095. Association for Computational Linguistics, Toronto, Canada, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In this paper, we describe our approach to the clickbait spoiling task of SemEval 2023. The core idea behind our system is to leverage pre-trained models capable of Question Answering (QA) to extract the spoiler from article texts based on the clickbait title without any task-specific training. Since oftentimes, these titles are not phrased as questions, we automatically rephrase the clickbait titles as questions in order to better suit the pretraining task of the QA-capable models. Also, to fit as much relevant context into the model's limited input size as possible, we propose to reorder the sentences by their relevance using a semantic similarity model. Finally, we evaluate QA as well as text generation models (via prompting) to extract the spoiler from the text.Based on the validation data, our final model selects each of these components depending on the spoiler type and achieves satisfactory zero-shot results. The ideas described in this paper can easily be applied in fine-tuning settings.

  @inproceedings{wangsadirdja2023zeroshot, abstract = {In this paper, we describe our approach to the clickbait spoiling task of SemEval 2023. The core idea behind our system is to leverage pre-trained models capable of Question Answering (QA) to extract the spoiler from article texts based on the clickbait title without any task-specific training. Since oftentimes, these titles are not phrased as questions, we automatically rephrase the clickbait titles as questions in order to better suit the pretraining task of the QA-capable models. Also, to fit as much relevant context into the model's limited input size as possible, we propose to reorder the sentences by their relevance using a semantic similarity model. Finally, we evaluate QA as well as text generation models (via prompting) to extract the spoiler from the text.Based on the validation data, our final model selects each of these components depending on the spoiler type and achieves satisfactory zero-shot results. The ideas described in this paper can easily be applied in fine-tuning settings.}, address = {Toronto, Canada}, author = {Wangsadirdja, Dirk and Pfister, Jan and Kobs, Konstantin and Hotho, Andreas}, booktitle = {Proceedings of the The 17th International Workshop on Semantic Evaluation (SemEval-2023)}, keywords = {from:janpf}, month = {07}, pages = {1090–1095}, publisher = {Association for Computational Linguistics}, title = {Zero-Shot Clickbait Spoiling by Rephrasing Titles as Questions}, year = 2023 }
• On Profiling, Benchmarking and Behavioral Analysis of SDN Architecture Under DDoS Attacks. Huu Thanh, Nguyen; NgocTuan, Nguyen; AnhKhoa, Dang; CongTuan, Le; TrungKien, Nguyen; XuanDung, Nguyen; QuynhThu, Ngo; Wamser, Florian. In Journal of Network and Systems Management. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Software-Defined Networking (SDN) has attracted much attention from research and industrial communities recently as it is more agile and flexible compared to conventional networking technology in offering new network functions and services. By separating the network control functions from the forwarding devices and placing them in a centralized, softwarized and programmable SDN controller, new network functions and services can be easily added into the network in an on-demand manner. However, the centralized control paradigm and the flow-based forwarding principle make the SDN architecture more fragile and vulnerable to malicious actions, such as cyber hijacking or DDoS attacks. In this paper, we focus on analyzing and evaluating negative impacts of DDoS attacks on the SDN architecture. By performing stress tests, the performance of such common SDN controllers as POX, Ryu and Floodlight under DDoS attacks is benchmarked, along with their impacts on the SDN switch and OpenFlow channel. We also address some new threats and vulnerabilities introduced by the nature of SDN.

  @article{info3-article-2023-1, abstract = {Software-Defined Networking (SDN) has attracted much attention from research and industrial communities recently as it is more agile and flexible compared to conventional networking technology in offering new network functions and services. By separating the network control functions from the forwarding devices and placing them in a centralized, softwarized and programmable SDN controller, new network functions and services can be easily added into the network in an on-demand manner. However, the centralized control paradigm and the flow-based forwarding principle make the SDN architecture more fragile and vulnerable to malicious actions, such as cyber hijacking or DDoS attacks. In this paper, we focus on analyzing and evaluating negative impacts of DDoS attacks on the SDN architecture. By performing stress tests, the performance of such common SDN controllers as POX, Ryu and Floodlight under DDoS attacks is benchmarked, along with their impacts on the SDN switch and OpenFlow channel. We also address some new threats and vulnerabilities introduced by the nature of SDN.}, author = {Huu Thanh, Nguyen and NgocTuan, Nguyen and AnhKhoa, Dang and CongTuan, Le and TrungKien, Nguyen and XuanDung, Nguyen and QuynhThu, Ngo and Wamser, Florian}, journal = {Journal of Network and Systems Management}, keywords = {myown}, month = {03}, title = {On Profiling, Benchmarking and Behavioral Analysis of SDN Architecture Under DDoS Attacks}, year = 2023 }
• De Bello Homomorphico: Investigation of the extensibility of the OpenFHE library with basic mathematical functions by means of common approaches using the example of the CKKS cryptosystem. Prantl, Thomas; Horn, Lukas; Engel, Simon; Iffländer, Lukas; Beierlieb, Lukas; Krupitzer, Christian; Bauer, André; Sakarvadia, Mansi; Foster, Ian; Kounev, Samuel. In International Journal of Information Security. 2023.
  • [ BibTeX ]
  @article{PrHoEnIfBeKrBaSaFoKo_IJoIS_SGC_Pareto, author = {Prantl, Thomas and Horn, Lukas and Engel, Simon and Iffl\"ander, Lukas and Beierlieb, Lukas and Krupitzer, Christian and Bauer, Andr\'e and Sakarvadia, Mansi and Foster, Ian and Kounev, Samuel}, journal = {International Journal of Information Security}, keywords = {t_journalmagazine}, month = 11, title = {De Bello Homomorphico: Investigation of the extensibility of the OpenFHE library with basic mathematical functions by means of common approaches using the example of the CKKS cryptosystem}, year = 2023 }
• Share and Multiply: Modeling Communication and Generated Traffic in Private WhatsApp Groups. Seufert, Anika; Poignée, Fabian; Seufert, Michael; Hoßfeld, Tobias. In IEEE Access, 11, pp. 25401–25414. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Group-based communication is a highly popular communication paradigm, which is especially prominent in mobile instant messaging (MIM) applications, such as WhatsApp. Chat groups in MIM applications facilitate the sharing of various types of messages (e.g., text, voice, image, video) among a large number of participants. As each message has to be transmitted to every other member of the group, which multiplies the traffic, this has a massive impact on the underlying communication networks. However, most chat groups are private and network operators cannot obtain deep insights into MIM communication via network measurements due to end-to-end encryption. Thus, the generation of traffic is not well understood, given that it depends on sizes of communication groups, speed of communication, and exchanged message types. In this work, we provide a huge data set of 5,956 private WhatsApp chat histories, which contains over 76 million messages from more than 117,000 users. We describe and model the properties of chat groups and users, and the communication within these chat groups, which gives unprecedented insights into private MIM communication. In addition, we conduct exemplary measurements for the most popular message types, which empower the provided models to estimate the traffic over time in a chat group.

  @article{info3-article-2023-2, abstract = {Group-based communication is a highly popular communication paradigm, which is especially prominent in mobile instant messaging (MIM) applications, such as WhatsApp. Chat groups in MIM applications facilitate the sharing of various types of messages (e.g., text, voice, image, video) among a large number of participants. As each message has to be transmitted to every other member of the group, which multiplies the traffic, this has a massive impact on the underlying communication networks. However, most chat groups are private and network operators cannot obtain deep insights into MIM communication via network measurements due to end-to-end encryption. Thus, the generation of traffic is not well understood, given that it depends on sizes of communication groups, speed of communication, and exchanged message types. In this work, we provide a huge data set of 5,956 private WhatsApp chat histories, which contains over 76 million messages from more than 117,000 users. We describe and model the properties of chat groups and users, and the communication within these chat groups, which gives unprecedented insights into private MIM communication. In addition, we conduct exemplary measurements for the most popular message types, which empower the provided models to estimate the traffic over time in a chat group.}, author = {Seufert, Anika and Poignée, Fabian and Seufert, Michael and Hoßfeld, Tobias}, journal = {IEEE Access}, keywords = {ucn}, month = {03}, pages = {25401 - 25414}, title = {Share and Multiply: Modeling Communication and Generated Traffic in Private WhatsApp Groups}, volume = 11, year = 2023 }
• An Empirical Study of Container Image Configurations and Their Impact on Start Times. Straesser, Martin; Bauer, André; Leppich, Robert; Herbst, Nikolas; Chard, Kyle; Foster, Ian; Kounev, Samuel. In 2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing (CCGrid), pp. 94–105. IEEE, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{straesser2023starttime, author = {Straesser, Martin and Bauer, André and Leppich, Robert and Herbst, Nikolas and Chard, Kyle and Foster, Ian and Kounev, Samuel}, booktitle = {2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing (CCGrid)}, keywords = {empirical_study}, pages = {94-105}, publisher = {IEEE}, title = {An Empirical Study of Container Image Configurations and Their Impact on Start Times}, year = 2023 }
• Usability of a {{Mhealth Solution}} Using {{Speech Recognition}} for {{Point-of-care Diagnostic Management}}. Kerwagen, Fabian; Fuchs, Konrad F.; Ullrich, Melanie; Schulze, Andreas; Straka, Samantha; Krop, Philipp; Latoschik, Marc E.; Gilbert, Fabian; Kunz, Andreas; Fette, Georg; St{ö}rk, Stefan; Ertl, Maximilian. In Journal of Medical Systems, 47(18). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The administrative burden for physicians in the hospital can affect the quality of patient care. The Service Center Medical Informatics (SMI) of the University Hospital Würzburg developed and implemented the smartphone-based mobile application (MA) ukw.mobile1 that uses speech recognition for the point-of-care ordering of radiological examinations. The aim of this study was to examine the usability of the MA workflow for the point-of-care ordering of radiological examinations. All physicians at the Department of Trauma and Plastic Surgery at the University Hospital Würzburg, Germany, were asked to participate in a survey including the short version of the User Experience Questionnaire (UEQ-S) and the Unified Theory of Acceptance and Use of Technology (UTAUT). For the analysis of the different domains of user experience (overall attractiveness, pragmatic quality and hedonic quality), we used a two-sided dependent sample t-test. For the determinants of the acceptance model, we employed regression analysis. Twenty-one of 30 physicians (mean age 34\,{$\pm$}\,8 years, 62\% male) completed the questionnaire. Compared to the conventional desktop application (DA) workflow, the new MA workflow showed superior overall attractiveness (mean difference 2.15\,{$\pm$}\,1.33), pragmatic quality (mean difference 1.90\,{$\pm$}\,1.16), and hedonic quality (mean difference 2.41\,{$\pm$}\,1.62; all p\,{$<$}\,.001). The user acceptance measured by the UTAUT (mean 4.49\,{$\pm$}\,0.41; min. 1, max. 5) was also high. Performance expectancy (beta\,=\,0.57, p\,=\,.02) and effort expectancy (beta\,=\,0.36, p\,=\,.04) were identified as predictors of acceptance, the full predictive model explained 65.4\% of the variance. Point-of-care mHealth solutions using innovative technology such as speech-recognition seem to address the users' needs and to offer higher usability in comparison to conventional technology. Implementation of user-centered mHealth innovations might therefore help to facilitate physicians' daily work.

  @article{kerwagen2023, abstract = {The administrative burden for physicians in the hospital can affect the quality of patient care. The Service Center Medical Informatics (SMI) of the University Hospital W\"urzburg developed and implemented the smartphone-based mobile application (MA) ukw.mobile1 that uses speech recognition for the point-of-care ordering of radiological examinations. The aim of this study was to examine the usability of the MA workflow for the point-of-care ordering of radiological examinations. All physicians at the Department of Trauma and Plastic Surgery at the University Hospital W\"urzburg, Germany, were asked to participate in a survey including the short version of the User Experience Questionnaire (UEQ-S) and the Unified Theory of Acceptance and Use of Technology (UTAUT). For the analysis of the different domains of user experience (overall attractiveness, pragmatic quality and hedonic quality), we used a two-sided dependent sample t-test. For the determinants of the acceptance model, we employed regression analysis. Twenty-one of 30 physicians (mean age 34\,{$\pm$}\,8 years, 62\% male) completed the questionnaire. Compared to the conventional desktop application (DA) workflow, the new MA workflow showed superior overall attractiveness (mean difference 2.15\,{$\pm$}\,1.33), pragmatic quality (mean difference 1.90\,{$\pm$}\,1.16), and hedonic quality (mean difference 2.41\,{$\pm$}\,1.62; all p\,{$<$}\,.001). The user acceptance measured by the UTAUT (mean 4.49\,{$\pm$}\,0.41; min. 1, max. 5) was also high. Performance expectancy (beta\,=\,0.57, p\,=\,.02) and effort expectancy (beta\,=\,0.36, p\,=\,.04) were identified as predictors of acceptance, the full predictive model explained 65.4\% of the variance. Point-of-care mHealth solutions using innovative technology such as speech-recognition seem to address the users' needs and to offer higher usability in comparison to conventional technology. Implementation of user-centered mHealth innovations might therefore help to facilitate physicians' daily work.}, author = {Kerwagen, Fabian and Fuchs, Konrad F. and Ullrich, Melanie and Schulze, Andreas and Straka, Samantha and Krop, Philipp and Latoschik, Marc E. and Gilbert, Fabian and Kunz, Andreas and Fette, Georg and St{\"o}rk, Stefan and Ertl, Maximilian}, journal = {Journal of Medical Systems}, keywords = {latoschik}, number = 18, title = {Usability of a {{Mhealth Solution}} Using {{Speech Recognition}} for {{Point-of-care Diagnostic Management}}}, volume = 47, year = 2023 }
• Giving Historical Photographs a New Perspective: Introducing Camera Orientation Parameters as New Metadata in a Large-Scale 4D Application. Maiwald, Ferdinand; Bruschke, Jonas; Schneider, Danilo; Wacker, Markus; Niebling, Florian. In Remote Sensing, 15(7), p. 1879. 2023.
  • [ BibTeX ]
  • [ URL ]
  @article{maiwald2023giving, author = {Maiwald, Ferdinand and Bruschke, Jonas and Schneider, Danilo and Wacker, Markus and Niebling, Florian}, journal = {Remote Sensing}, keywords = {histstadt4d}, number = 7, pages = 1879, title = {Giving Historical Photographs a New Perspective: Introducing Camera Orientation Parameters as New Metadata in a Large-Scale 4D Application}, type = {Journal Article}, volume = 15, year = 2023 }
• Holographic Augmented Reality Mirrors for Daily Self-Reflection on the Own Body Image. Fiedler, Marie Luisa; Wolf, Erik; Wienrich, Carolin; Latoschik, Marc Erich. In CHI 2023 WS28 Integrating Individual and Social Contexts into Self-Reflection Technologies Workshop, pp. 1–4. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Mirror self-reflection can help us to develop a deeper understanding and appreciation of our body. Due to technological advancements, holographic augmented reality (AR) mirrors can create realistic visualizations of virtual humans that can represent one's appearance in an altered way while remaining in a familiar environment. Further developing those mirrors opens a new field for use in everyday life. In this work, we outline possible future scenarios where AR mirrors can empower individuals to visualize their emotions, thought patterns, and discrepancies related to their physical body and mental body image. Thus, AR mirrors can encourage their self-reflection, promote a positive and healthy relationship with their bodies, or motivate them to take action to improve their well-being.

  @inproceedings{fiedler2023holographic, abstract = {Mirror self-reflection can help us to develop a deeper understanding and appreciation of our body. Due to technological advancements, holographic augmented reality (AR) mirrors can create realistic visualizations of virtual humans that can represent one's appearance in an altered way while remaining in a familiar environment. Further developing those mirrors opens a new field for use in everyday life. In this work, we outline possible future scenarios where AR mirrors can empower individuals to visualize their emotions, thought patterns, and discrepancies related to their physical body and mental body image. Thus, AR mirrors can encourage their self-reflection, promote a positive and healthy relationship with their bodies, or motivate them to take action to improve their well-being.}, author = {Fiedler, Marie Luisa and Wolf, Erik and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {CHI 2023 WS28 Integrating Individual and Social Contexts into Self-Reflection Technologies Workshop}, keywords = {mfiedler}, pages = {1-4}, title = {Holographic Augmented Reality Mirrors for Daily Self-Reflection on the Own Body Image}, year = 2023 }
• Who Is Alyx? A new Behavioral Biometric Dataset for User Identification in XR. Rack, Christian; Fernando, Tamara; Yalcin, Murat; Hotho, Andreas; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 4, D. Swapp (ed.). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  This article presents a new dataset containing motion and physiological data of users playing the game 'Half-Life: Alyx'. The dataset specifically targets behavioral and biometric identification of XR users. It includes motion and eye-tracking data captured by a HTC Vive Pro of 71 users playing the game on two separate days for 45 minutes. Additionally, we collected physiological data from 31 of these users. We provide benchmark performances for the task of motion-based identification of XR users with two prominent state-of-the-art deep learning architectures (GRU and CNN). After training on the first session of each user, the best model can identify the 71 users in the second session with a mean accuracy of 95% within 2 minutes. The dataset is freely available under https://github.com/cschell/who-is-alyx

  @article{rack2023behavioral, abstract = {This article presents a new dataset containing motion and physiological data of users playing the game 'Half-Life: Alyx'. The dataset specifically targets behavioral and biometric identification of XR users. It includes motion and eye-tracking data captured by a HTC Vive Pro of 71 users playing the game on two separate days for 45 minutes. Additionally, we collected physiological data from 31 of these users. We provide benchmark performances for the task of motion-based identification of XR users with two prominent state-of-the-art deep learning architectures (GRU and CNN). After training on the first session of each user, the best model can identify the 71 users in the second session with a mean accuracy of 95% within 2 minutes. The dataset is freely available under https://github.com/cschell/who-is-alyx}, author = {Rack, Christian and Fernando, Tamara and Yalcin, Murat and Hotho, Andreas and Latoschik, Marc Erich}, editor = {Swapp, David}, journal = {Frontiers in Virtual Reality}, keywords = {schell}, title = {Who Is Alyx? A new Behavioral Biometric Dataset for User Identification in XR}, volume = 4, year = 2023 }
• The Impact of Reflection Approximations on Visual Quality in Virtual Reality. Mišiak, Martin; Fuhrmann, Arnulph; Latoschik, Marc Erich. In ACM Symposium on Applied Perception 2023 (SAP ’23), August. ACM, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{misiak2023reflectionApprox, author = {Mišiak, Martin and Fuhrmann, Arnulph and Latoschik, Marc Erich}, booktitle = {ACM Symposium on Applied Perception 2023 (SAP '23), August}, keywords = {myown}, note = {To be published}, publisher = {ACM}, title = {The Impact of Reflection Approximations on Visual Quality in Virtual Reality}, year = 2023 }
• “If It’s Not Me It Doesn’t Make a Difference” – The Impact of Avatar Personalization on User Experience and Body Awareness in Virtual Reality. Döllinger, Nina; Beck, Matthias; Wolf, Erik; Mal, David; Botsch, Mario; Latoschik, Marc Erich; Wienrich, Carolin. In 2023 IEEE International Symposium on Mixed and Augmented Reality (ISMAR), pp. 483–492. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Body awareness is relevant for the efficacy of psychotherapy. However, previous work on virtual reality (VR) and avatar-assisted therapy has often overlooked it. We investigated the effect of avatar individualization on body awareness in the context of VR-specific user experience, including sense of embodiment (SoE), plausibility, and sense of presence (SoP). In a between-subject design, 86 participants embodied three avatar types and engaged in VR movement exercises. The avatars were (1) generic and gender-matched, (2) customized from a set of pre-existing options, or (3) personalized photorealistic scans. Compared to the other conditions, participants with personalized avatars reported increased SoE, yet higher eeriness and reduced body awareness. Further, SoE and SoP positively correlated with body awareness across conditions. Our results indicate that VR user experience and body awareness do not always dovetail and do not necessarily predict each other. Future research should work towards a balance between body awareness and SoE.

  @inproceedings{dollinger2023doesnt, abstract = {Body awareness is relevant for the efficacy of psychotherapy. However, previous work on virtual reality (VR) and avatar-assisted therapy has often overlooked it. We investigated the effect of avatar individualization on body awareness in the context of VR-specific user experience, including sense of embodiment (SoE), plausibility, and sense of presence (SoP). In a between-subject design, 86 participants embodied three avatar types and engaged in VR movement exercises. The avatars were (1) generic and gender-matched, (2) customized from a set of pre-existing options, or (3) personalized photorealistic scans. Compared to the other conditions, participants with personalized avatars reported increased SoE, yet higher eeriness and reduced body awareness. Further, SoE and SoP positively correlated with body awareness across conditions. Our results indicate that VR user experience and body awareness do not always dovetail and do not necessarily predict each other. Future research should work towards a balance between body awareness and SoE.}, author = {Döllinger, Nina and Beck, Matthias and Wolf, Erik and Mal, David and Botsch, Mario and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {2023 IEEE International Symposium on Mixed and Augmented Reality (ISMAR)}, keywords = {dmal}, pages = {483-492}, title = {“If It’s Not Me It Doesn’t Make a Difference” – The Impact of Avatar Personalization on User Experience and Body Awareness in Virtual Reality}, year = 2023 }
• Embodiment and Personalization for Self-Identification with Virtual Humans. Fiedler, Marie Luisa; Wolf, Erik; Döllinger, Nina; Botsch, Mario; Latoschik, Marc Erich; Wienrich, Carolin. In 2023 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW), pp. 799–800. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Our work investigates the impact of virtual human embodiment and personalization on the sense of embodiment (SoE) and self-identification (SI). We introduce preliminary items to query self-similarity (SS) and self-attribution (SA) with virtual humans as dimensions of SI. In our study, 64 participants successively observed personalized and generic-looking virtual humans, either as embodied avatars in a virtual mirror or as agents while performing tasks. They reported significantly higher SoE and SI when facing personalized virtual humans and significantly higher SoE and SA when facing embodied avatars, indicating that both factors have strong separate and complimentary influence on SoE and SI.

  @inproceedings{fiedler2023selfidentification, abstract = {Our work investigates the impact of virtual human embodiment and personalization on the sense of embodiment (SoE) and self-identification (SI). We introduce preliminary items to query self-similarity (SS) and self-attribution (SA) with virtual humans as dimensions of SI. In our study, 64 participants successively observed personalized and generic-looking virtual humans, either as embodied avatars in a virtual mirror or as agents while performing tasks. They reported significantly higher SoE and SI when facing personalized virtual humans and significantly higher SoE and SA when facing embodied avatars, indicating that both factors have strong separate and complimentary influence on SoE and SI.}, author = {Fiedler, Marie Luisa and Wolf, Erik and Döllinger, Nina and Botsch, Mario and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {2023 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {mfiedler}, pages = {799-800}, title = {Embodiment and Personalization for Self-Identification with Virtual Humans}, year = 2023 }
• A Systematic Approach for Benchmarking of Container Orchestration Frameworks. Straesser, Martin; Mathiasch, Jonas; Bauer, Andr{é}; Kounev, Samuel. In Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23, pp. 187–198. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Container orchestration frameworks play a critical role in modern cloud computing paradigms such as cloud-native or serverless computing. They significantly impact the quality and cost of service deployment as they manage many performance-critical tasks such as container provisioning, scheduling, scaling, and networking. Consequently, a comprehensive performance assessment of container orchestration frameworks is essential. However, until now, there is no benchmarking approach that covers the many different tasks implemented in such platforms and supports evaluating different technology stacks. In this paper, we present a systematic approach that enables benchmarking of container orchestrators. Based on a definition of container orchestration, we define the core requirements and benchmarking scope for such platforms. Each requirement is then linked to metrics and measurement methods, and a benchmark architecture is proposed. With COFFEE, we introduce a benchmarking tool supporting the definition of complex test campaigns for container orchestration frameworks. We demonstrate the potential of our approach with case studies of the frameworks Kubernetes and Nomad in a self-hosted environment and on the Google Cloud Platform. The presented case studies focus on container startup times, crash recovery, rolling updates, and more.

  @inproceedings{straesser2023orchestration, abstract = {Container orchestration frameworks play a critical role in modern cloud computing paradigms such as cloud-native or serverless computing. They significantly impact the quality and cost of service deployment as they manage many performance-critical tasks such as container provisioning, scheduling, scaling, and networking. Consequently, a comprehensive performance assessment of container orchestration frameworks is essential. However, until now, there is no benchmarking approach that covers the many different tasks implemented in such platforms and supports evaluating different technology stacks. In this paper, we present a systematic approach that enables benchmarking of container orchestrators. Based on a definition of container orchestration, we define the core requirements and benchmarking scope for such platforms. Each requirement is then linked to metrics and measurement methods, and a benchmark architecture is proposed. With COFFEE, we introduce a benchmarking tool supporting the definition of complex test campaigns for container orchestration frameworks. We demonstrate the potential of our approach with case studies of the frameworks Kubernetes and Nomad in a self-hosted environment and on the Google Cloud Platform. The presented case studies focus on container startup times, crash recovery, rolling updates, and more.}, address = {New York, NY, USA}, author = {Straesser, Martin and Mathiasch, Jonas and Bauer, Andr\'{e} and Kounev, Samuel}, booktitle = {Proceedings of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {container_orchestration}, pages = {187-198}, publisher = {Association for Computing Machinery}, series = {ICPE '23}, title = {A Systematic Approach for Benchmarking of Container Orchestration Frameworks}, year = 2023 }
• Recommendation of Secure Group Communication Schemes using Multi Objective Optimization. Prantl, Thomas; Bauer, André; Iffländer, Lukas; Krupitzer, Christian; Kounev, Samuel. In International Journal of Information Security. 2023.
  • [ BibTeX ]
  @article{PrBaIfKrKo_IJoIS_SGC_Pareto, author = {Prantl, Thomas and Bauer, André and Iffländer, Lukas and Krupitzer, Christian and Kounev, Samuel}, journal = {International Journal of Information Security}, keywords = {t_journalmagazine}, title = {Recommendation of Secure Group Communication Schemes using Multi Objective Optimization}, year = 2023 }
• User-centred Design and Development of a Graphical User Interface for Learning Classifier Systems. Babu, Sooraj K; Schneider, Tim; von Mammen, Sebastian. In GECCO ’23 Companion: Proceedings of the Companion Conference on Genetic and Evolutionary Computation, pp. 1830–1837. ACM, Lisbon, Portugal, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This study presents an application that offers an interactive representation of the learning cycle of a learning classifier system (LCS), a rule-based machine learning technique. The research approach utilized a combination of human-computer interaction requirements, design heuristics, and user-centred engineering to scaffold the development of a graphical user interface for an LCS. The evaluation of the application by LCS experts and a novice yielded encouraging results, demonstrating its ability to convey the LCS mechanics to the users. In addition, the experts validated the correctness of the learning cycle. The study's contribution is two-fold: it presents an innovative approach to making the user understand the underlying mechanics of LCS and validates the effectiveness of the developed application. Furthermore, this work sets the stage for future research towards design revision and to further develop the application to accommodate different LCS models and custom data.

  @conference{babu2023usercentred, abstract = {This study presents an application that offers an interactive representation of the learning cycle of a learning classifier system (LCS), a rule-based machine learning technique. The research approach utilized a combination of human-computer interaction requirements, design heuristics, and user-centred engineering to scaffold the development of a graphical user interface for an LCS. The evaluation of the application by LCS experts and a novice yielded encouraging results, demonstrating its ability to convey the LCS mechanics to the users. In addition, the experts validated the correctness of the learning cycle. The study's contribution is two-fold: it presents an innovative approach to making the user understand the underlying mechanics of LCS and validates the effectiveness of the developed application. Furthermore, this work sets the stage for future research towards design revision and to further develop the application to accommodate different LCS models and custom data.}, address = {Lisbon, Portugal}, author = {Babu, Sooraj K and Schneider, Tim and von Mammen, Sebastian}, booktitle = {GECCO '23 Companion: Proceedings of the Companion Conference on Genetic and Evolutionary Computation}, keywords = {via-vr}, pages = {1830–1837}, publisher = {ACM}, title = {User-centred Design and Development of a Graphical User Interface for Learning Classifier Systems}, year = 2023 }
• BLOCSIE - Benchmark for LOCalization in a Simulated Industrial Environment. Spiess, Florian; Bluemm, Daniel; Strobel, Norbert; Kaupp, Tobias; Kounev, Samuel. In 2023 21st International Conference on Advanced Robotics (ICAR), pp. 577–584. 2023.
  • [ BibTeX ]
  @inproceedings{10406777, author = {Spiess, Florian and Bluemm, Daniel and Strobel, Norbert and Kaupp, Tobias and Kounev, Samuel}, booktitle = {2023 21st International Conference on Advanced Robotics (ICAR)}, keywords = {descartes}, pages = {577-584}, title = {BLOCSIE - Benchmark for LOCalization in a Simulated Industrial Environment}, year = 2023 }
• Optimizing Medical Service Request Processes through Language Modeling and Semantic Search. Schlör, Daniel; Pfister, Jan; Hotho, Andreas. In 2023 the 7th International Conference on Medical and Health Informatics (ICMHI), of ICMHI 2023, pp. 136–141. Association for Computing Machinery, Kyoto, Japan, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Medical service requests are a crucial part of the workflow in hospitals and healthcare organizations. However, the process of requesting medical services can be time consuming and can require physicians and medical personnel to navigate complex interfaces and enter detailed information about the requested service. In this paper, we propose a system that uses machine learning techniques such as large language models and semantic search to optimize the process of requesting medical services. Our approach enables physicians to request medical services using natural language rather than navigating complex interfaces, allowing for more efficient and flexible interactions with hospital information systems. We evaluate our approach on real-world data and discuss the implications of our work for the future of digital health care. Our results suggest that our approach has the potential to streamline the process of requesting medical services and reduce the time and manual effort required in the daily hospital routine.

  @inproceedings{10.1145/3608298.3608324, abstract = {Medical service requests are a crucial part of the workflow in hospitals and healthcare organizations. However, the process of requesting medical services can be time consuming and can require physicians and medical personnel to navigate complex interfaces and enter detailed information about the requested service. In this paper, we propose a system that uses machine learning techniques such as large language models and semantic search to optimize the process of requesting medical services. Our approach enables physicians to request medical services using natural language rather than navigating complex interfaces, allowing for more efficient and flexible interactions with hospital information systems. We evaluate our approach on real-world data and discuss the implications of our work for the future of digital health care. Our results suggest that our approach has the potential to streamline the process of requesting medical services and reduce the time and manual effort required in the daily hospital routine.}, address = {New York, NY, USA}, author = {Schlör, Daniel and Pfister, Jan and Hotho, Andreas}, booktitle = {2023 the 7th International Conference on Medical and Health Informatics (ICMHI)}, keywords = {llm}, pages = {136–141}, publisher = {Association for Computing Machinery}, series = {ICMHI 2023}, title = {Optimizing Medical Service Request Processes through Language Modeling and Semantic Search}, year = 2023 }
• Parameterized Approximation Schemes for Clustering with General Norm Objectives. Abbasi, Fateme; Banerjee, Sandip; Byrka, Jaroslaw; Chalermsook, Parinya; Gadekar, Ameet; Khodamoradi, Kamyar; Marx, Daniel; Sharma, Roohani; Spoerhase, Joachim. In Proc. 64th IEEE Symposium on Foundations of Computer Science (FOCS’23). 2023.
  • [ BibTeX ]
  @inproceedings{abbasi-etal23:epas-norm-clustering, author = {Abbasi, Fateme and Banerjee, Sandip and Byrka, Jaroslaw and Chalermsook, Parinya and Gadekar, Ameet and Khodamoradi, Kamyar and Marx, Daniel and Sharma, Roohani and Spoerhase, Joachim}, booktitle = {Proc. 64th IEEE Symposium on Foundations of Computer Science (FOCS'23)}, keywords = {key}, note = {to appear}, title = {Parameterized Approximation Schemes for Clustering with General Norm Objectives}, year = 2023 }
• Kubernetes-in-the-Loop: Enriching Microservice Simulation Through Authentic Container Orchestration. Straesser, Martin; Haas, Patrick; Frank, Sebastian; Hakamian, Alireza; Van Hoorn, André; Kounev, Samuel. In Performance Evaluation Methodologies and Tools. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Microservices deployed and managed by container orchestration frameworks like Kubernetes are the bases of modern cloud applications. In microservice performance modeling and prediction, simulations provide a lightweight alternative to experimental analysis, which requires dedicated infrastructure and a laborious setup. However, existing simulators cannot run realistic scenarios, as performance-critical orchestration mechanisms (like scheduling or autoscaling) are manually modeled and can consequently not be represented in their full complexity and configuration space. This work combines a state-of-the-art simulation for microservice performance with Kubernetes container orchestration. Hereby, we include the original implementation of Kubernetes artifacts enabling realistic scenarios and testing of orchestration policies with low overhead. In two experiments with Kubernetes' kube-scheduler and cluster-autoscaler, we demonstrate that our framework can correctly handle different configurations of these orchestration mechanisms boosting both the simulation's use cases and authenticity.

  @inproceedings{straesser2023kubernetesintheloop, abstract = {Microservices deployed and managed by container orchestration frameworks like Kubernetes are the bases of modern cloud applications. In microservice performance modeling and prediction, simulations provide a lightweight alternative to experimental analysis, which requires dedicated infrastructure and a laborious setup. However, existing simulators cannot run realistic scenarios, as performance-critical orchestration mechanisms (like scheduling or autoscaling) are manually modeled and can consequently not be represented in their full complexity and configuration space. This work combines a state-of-the-art simulation for microservice performance with Kubernetes container orchestration. Hereby, we include the original implementation of Kubernetes artifacts enabling realistic scenarios and testing of orchestration policies with low overhead. In two experiments with Kubernetes' kube-scheduler and cluster-autoscaler, we demonstrate that our framework can correctly handle different configurations of these orchestration mechanisms boosting both the simulation's use cases and authenticity.}, author = {Straesser, Martin and Haas, Patrick and Frank, Sebastian and Hakamian, Alireza and Van Hoorn, André and Kounev, Samuel}, booktitle = {Performance Evaluation Methodologies and Tools}, keywords = {discrete_event_simulation}, note = {In print.}, title = {Kubernetes-in-the-Loop: Enriching Microservice Simulation Through Authentic Container Orchestration}, year = 2023 }
• CapsKG: Enabling Continual Knowledge Integration in Language Models for Automatic Knowledge Graph Completion. Omeliyanenko, Janna; Zehe, Albin; Hotho, Andreas; Schlör, Daniel. In International Semantic Web Conference ISWC 2023, to appear. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Automated completion of knowledge graphs is a popular topic in the Semantic Web community that aims to automatically and continuously integrate new appearing knowledge into knowledge graphs using artificial intelligence. Recently, approaches that leverage implicit knowledge from language models for this task have shown promising re- sults. However, by fine-tuning language models directly to the domain of knowledge graphs, models forget their original language representation and associated knowledge. An existing solution to address this issue is a trainable adapter, which is integrated into a frozen language model to extract the relevant knowledge without altering the model itself. How- ever, this constrains the generalizability to the specific extraction task and by design requires new and independent adapters to be trained for new knowledge extraction tasks. This effectively prevents the model from benefiting from existing knowledge incorporated in previously trained adapters. In this paper, we propose to combine the benefits of adapters for knowl- edge graph completion with the idea of integrating capsules, introduced in the field of continual learning. This allows the continuous integra- tion of knowledge into a joint model by sharing and reusing previously trained capsules. We find that our approach outperforms solutions using traditional adapters, while requiring notably fewer parameters for con- tinuous knowledge integration. Moreover, we show that this architecture benefits significantly from knowledge sharing in low-resource situations, outperforming adapter-based models on the task of link prediction.

  @article{omeliyanenko2023capskg, abstract = {Automated completion of knowledge graphs is a popular topic in the Semantic Web community that aims to automatically and continuously integrate new appearing knowledge into knowledge graphs using artificial intelligence. Recently, approaches that leverage implicit knowledge from language models for this task have shown promising re- sults. However, by fine-tuning language models directly to the domain of knowledge graphs, models forget their original language representation and associated knowledge. An existing solution to address this issue is a trainable adapter, which is integrated into a frozen language model to extract the relevant knowledge without altering the model itself. How- ever, this constrains the generalizability to the specific extraction task and by design requires new and independent adapters to be trained for new knowledge extraction tasks. This effectively prevents the model from benefiting from existing knowledge incorporated in previously trained adapters. In this paper, we propose to combine the benefits of adapters for knowl- edge graph completion with the idea of integrating capsules, introduced in the field of continual learning. This allows the continuous integra- tion of knowledge into a joint model by sharing and reusing previously trained capsules. We find that our approach outperforms solutions using traditional adapters, while requiring notably fewer parameters for con- tinuous knowledge integration. Moreover, we show that this architecture benefits significantly from knowledge sharing in low-resource situations, outperforming adapter-based models on the task of link prediction.}, author = {Omeliyanenko, Janna and Zehe, Albin and Hotho, Andreas and Schlör, Daniel}, journal = {International Semantic Web Conference ISWC 2023, to appear}, keywords = {graph}, title = {CapsKG: Enabling Continual Knowledge Integration in Language Models for Automatic Knowledge Graph Completion}, year = 2023 }
• Swarming Detection in Smart Beehives Using Auto Encoders for Audio Data. Janetzky, Pascal; Schaller, Melanie; Krause, Anna; Hotho, Andreas. In 2023 30th International Conference on Systems, Signals and Image Processing (IWSSIP), pp. 1–5. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  —Swarming is the natural mechanism by which bee colonies reproduce, but for beekeepers it is a challenge. Precision beekeeping can aid their work through early notifications about impending swarms. In this work, we focus on identifying swarms and their early indicators in audio data captured from a smart beehive. The challenge with such domain-specific data is the low availability of labelled samples, the strong label imbalance, and the recording of undesired sources. We approach this challenge through a two-step setup: First, we use an auto encoder network to detect sounds from mechanical sources and then use it to clean data. Secondly, on the cleaned data we then employ a second network to identify event-related bee sounds. Using spectrogram features, our networks are able to reach a balanced accuracy score of more than 99 % in the detection of special bee events. The findings of this initial study can serve as the starting point for further research on handling imbalanced data collections from smart, remote sensor environments that also contain undesired signals.

  @inproceedings{janetzky2023swarming, abstract = {—Swarming is the natural mechanism by which bee colonies reproduce, but for beekeepers it is a challenge. Precision beekeeping can aid their work through early notifications about impending swarms. In this work, we focus on identifying swarms and their early indicators in audio data captured from a smart beehive. The challenge with such domain-specific data is the low availability of labelled samples, the strong label imbalance, and the recording of undesired sources. We approach this challenge through a two-step setup: First, we use an auto encoder network to detect sounds from mechanical sources and then use it to clean data. Secondly, on the cleaned data we then employ a second network to identify event-related bee sounds. Using spectrogram features, our networks are able to reach a balanced accuracy score of more than 99 % in the detection of special bee events. The findings of this initial study can serve as the starting point for further research on handling imbalanced data collections from smart, remote sensor environments that also contain undesired signals.}, author = {Janetzky, Pascal and Schaller, Melanie and Krause, Anna and Hotho, Andreas}, booktitle = {2023 30th International Conference on Systems, Signals and Image Processing (IWSSIP)}, keywords = {from:jascal_panetzky}, pages = {1-5}, title = {Swarming Detection in Smart Beehives Using Auto Encoders for Audio Data}, year = 2023 }
• Automatic Speech Detection on a Smart Beehive’s Raspberry Pi. Janetzky, Pascal; Lissmann, Philipp; Hotho, Andreas; Krause, Anna. In LWDA 2023 - Learning, Knowledge, Data, and Analysis (accepted). 2023.
  • [ BibTeX ]
  @inproceedings{janetzky2023automatic, author = {Janetzky, Pascal and Lissmann, Philipp and Hotho, Andreas and Krause, Anna}, booktitle = {LWDA 2023 - Learning, Knowledge, Data, and Analysis (accepted)}, keywords = {from:martinr}, title = {Automatic Speech Detection on a Smart Beehive's Raspberry Pi}, year = 2023 }
• Feature relevance XAI in anomaly detection: Reviewing approaches and challenges. Tritscher, Julian; Krause, Anna; Hotho, Andreas. In Frontiers in Artificial Intelligence, 6. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  With complexity of artificial intelligence systems increasing continuously in past years, studies to explain these complex systems have grown in popularity. While much work has focused on explaining artificial intelligence systems in popular domains such as classification and regression, explanations in the area of anomaly detection have only recently received increasing attention from researchers. In particular, explaining singular model decisions of a complex anomaly detector by highlighting which inputs were responsible for a decision, commonly referred to as local post-hoc feature relevance, has lately been studied by several authors. In this paper, we systematically structure these works based on their access to training data and the anomaly detection model, and provide a detailed overview of their operation in the anomaly detection domain. We demonstrate their performance and highlight their limitations in multiple experimental showcases, discussing current challenges and opportunities for future work in feature relevance XAI for anomaly detection.

  @article{tritscher2023feature, abstract = {With complexity of artificial intelligence systems increasing continuously in past years, studies to explain these complex systems have grown in popularity. While much work has focused on explaining artificial intelligence systems in popular domains such as classification and regression, explanations in the area of anomaly detection have only recently received increasing attention from researchers. In particular, explaining singular model decisions of a complex anomaly detector by highlighting which inputs were responsible for a decision, commonly referred to as local post-hoc feature relevance, has lately been studied by several authors. In this paper, we systematically structure these works based on their access to training data and the anomaly detection model, and provide a detailed overview of their operation in the anomaly detection domain. We demonstrate their performance and highlight their limitations in multiple experimental showcases, discussing current challenges and opportunities for future work in feature relevance XAI for anomaly detection.}, author = {Tritscher, Julian and Krause, Anna and Hotho, Andreas}, journal = {Frontiers in Artificial Intelligence}, keywords = {xai}, month = {02}, title = {Feature relevance XAI in anomaly detection: Reviewing approaches and challenges}, volume = 6, year = 2023 }
• A Virtualized Augmented Reality Simulation for Exploring Perceptual Incongruencies. Westermeier, Franziska; Brübach, Larissa; Wienrich, Carolin; Latoschik, Marc Erich. In Proceedings of the 29th ACM Symposium on Virtual Reality Software and Technology, of VRST ’23. Association for Computing Machinery, Christchurch, New Zealand, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  When blending virtual and physical content, certain incongruencies emerge from hardware limitations, inaccurate tracking, or different appearances of virtual and physical content. They restrain us from perceiving virtual and physical content as one experience. Hence, it is crucial to investigate these issues to determine how they influence our experience. We present a virtualized augmented reality simulation that can systematically examine single incongruencies or different configurations.

  @inproceedings{westermeier2023virtualized, abstract = {When blending virtual and physical content, certain incongruencies emerge from hardware limitations, inaccurate tracking, or different appearances of virtual and physical content. They restrain us from perceiving virtual and physical content as one experience. Hence, it is crucial to investigate these issues to determine how they influence our experience. We present a virtualized augmented reality simulation that can systematically examine single incongruencies or different configurations.}, address = {New York, NY, USA}, author = {Westermeier, Franziska and Brübach, Larissa and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {Proceedings of the 29th ACM Symposium on Virtual Reality Software and Technology}, keywords = {xrhub}, publisher = {Association for Computing Machinery}, series = {VRST '23}, title = {A Virtualized Augmented Reality Simulation for Exploring Perceptual Incongruencies}, year = 2023 }
• Towards a Computational Analysis of Suspense: Detecting Dangerous Situations. Zehe, Albin; Schröter, Julian; Hotho, Andreas. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Suspense is an important tool in storytelling to keep readers engaged and wanting to read more. However, it has so far not been studied extensively in Computational Literary Studies. In this paper, we focus on one of the elements authors can use to build up suspense: dangerous situations. We introduce a corpus of texts annotated with dangerous situations, distinguishing between 7 types of danger. Additionally, we annotate parts of the text that describe fear experienced by a character, regardless of the actual presence of danger. We present experiments towards the automatic detection of these situations, finding that unsupervised baseline methods can provide valuable signals for the detection, but more complex methods are necessary for further analysis. Not unexpectedly, the description of danger and fear often relies heavily on the context, both local (e.g., situations where danger is only mentioned, but not actually present) and global (e.g., "storm" being used in a literal sense in an adventure novel, but metaphorically in a romance novel).

  @misc{zehe2023towards, abstract = {Suspense is an important tool in storytelling to keep readers engaged and wanting to read more. However, it has so far not been studied extensively in Computational Literary Studies. In this paper, we focus on one of the elements authors can use to build up suspense: dangerous situations. We introduce a corpus of texts annotated with dangerous situations, distinguishing between 7 types of danger. Additionally, we annotate parts of the text that describe fear experienced by a character, regardless of the actual presence of danger. We present experiments towards the automatic detection of these situations, finding that unsupervised baseline methods can provide valuable signals for the detection, but more complex methods are necessary for further analysis. Not unexpectedly, the description of danger and fear often relies heavily on the context, both local (e.g., situations where danger is only mentioned, but not actually present) and global (e.g., "storm" being used in a literal sense in an adventure novel, but metaphorically in a romance novel).}, author = {Zehe, Albin and Schröter, Julian and Hotho, Andreas}, keywords = {suspense}, note = {cite arxiv:2305.06818 Comment: 4 pages + references & appendix; work in progress}, title = {Towards a Computational Analysis of Suspense: Detecting Dangerous Situations}, year = 2023 }
• Towards Virtual Audience Simulation For Speech Therapy. Glémarec, Yann; Lugrin, Jean-Luc; Hörmann, Amelie; Bosser, Anne-Gwenn; Buche, Cédric; Latoschik, Marc Erich; Lauer, Norina. In Proceedings of the 23rd International Conference on Intelligent Virtual Agents (IVA). 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{noauthororeditor2023towards, author = {Glémarec, Yann and Lugrin, Jean-Luc and Hörmann, Amelie and Bosser, Anne-Gwenn and Buche, Cédric and Latoschik, Marc Erich and Lauer, Norina}, booktitle = {Proceedings of the 23rd International Conference on Intelligent Virtual Agents (IVA)}, keywords = {hci-uwb}, title = {Towards Virtual Audience Simulation For Speech Therapy}, year = 2023 }
• Challenges of Serverless Deployment in Edge-MEC-Cloud. Nguyen, TrungKien; Loh, Frank; Hoßfeld, Tobias. In KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks 2023. 2023.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2023-6, author = {Nguyen, TrungKien and Loh, Frank and Hoßfeld, Tobias}, booktitle = {KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks 2023}, keywords = {myown}, title = {Challenges of Serverless Deployment in Edge-MEC-Cloud}, year = 2023 }
• An Evaluation of Dichoptic Tonemapping in Virtual Reality Experiences. Mišiak, Martin; Müller, Tom; Fuhrmann, Arnulph; Latoschik, Marc Erich. In GI VR/AR Workshop. Gesellschaft für Informatik eV, 2023.
  • [ BibTeX ]
  @inproceedings{misiak2023evaluation, author = {Mišiak, Martin and Müller, Tom and Fuhrmann, Arnulph and Latoschik, Marc Erich}, booktitle = {GI VR/AR Workshop}, keywords = {myown}, organization = {Gesellschaft für Informatik eV}, title = {An Evaluation of Dichoptic Tonemapping in Virtual Reality Experiences}, year = 2023 }
• Optimizing storage assignment, order picking, and their interaction in mezzanine warehouses. Lesch, Veronika; Müller, Patrick B.M.; Krämer, Moritz; Hadry, Marius; Kounev, Samuel; Krupitzer, Christian. In Applied intelligence, p. 25. 2023.
  • [ BibTeX ]
  • [ URL ]
  @article{lesch2023optimizing, author = {Lesch, Veronika and Müller, Patrick B.M. and Krämer, Moritz and Hadry, Marius and Kounev, Samuel and Krupitzer, Christian}, journal = {Applied intelligence}, keywords = {t_journalmagazine}, month = {02}, pages = 25, title = {Optimizing storage assignment, order picking, and their interaction in mezzanine warehouses}, year = 2023 }
• Extensible Motion-based Identification of XR Users with Non-Specific Motion. Rack, Christian; Kobs, Konstantin; Fernando, Tamara; Hotho, Andreas; Latoschik, Marc Erich. p. arXiv:2302.07517. 2023, February.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In this paper, we combine the strengths of distance-based and classification-based approaches for the task of identifying extended reality users by their movements. For this we explore an embedding-based model that leverages deep metric learning. We train the model on a dataset of users playing the VR game "Half-Life: Alyx" and conduct multiple experiments and analyses using a state of the art classification-based model as baseline. The results show that the embedding-based method 1) is able to identify new users from non-specific movements using only a few minutes of enrollment data, 2) can enroll new users within seconds, while retraining the baseline approach takes almost a day, 3) is more reliable than the baseline approach when only little enrollment data is available, 4) can be used to identify new users from another dataset recorded with different VR devices. Altogether, our solution is a foundation for easily extensible XR user identification systems, applicable to a wide range of user motions. It also paves the way for production-ready models that could be used by XR practitioners without the requirements of expertise, hardware, or data for training deep learning models.

  @preprint{2023arXiv230207517S, abstract = {In this paper, we combine the strengths of distance-based and classification-based approaches for the task of identifying extended reality users by their movements. For this we explore an embedding-based model that leverages deep metric learning. We train the model on a dataset of users playing the VR game "Half-Life: Alyx" and conduct multiple experiments and analyses using a state of the art classification-based model as baseline. The results show that the embedding-based method 1) is able to identify new users from non-specific movements using only a few minutes of enrollment data, 2) can enroll new users within seconds, while retraining the baseline approach takes almost a day, 3) is more reliable than the baseline approach when only little enrollment data is available, 4) can be used to identify new users from another dataset recorded with different VR devices. Altogether, our solution is a foundation for easily extensible XR user identification systems, applicable to a wide range of user motions. It also paves the way for production-ready models that could be used by XR practitioners without the requirements of expertise, hardware, or data for training deep learning models.}, author = {Rack, Christian and Kobs, Konstantin and Fernando, Tamara and Hotho, Andreas and Latoschik, Marc Erich}, journal = {arXiv}, keywords = {schell}, month = {02}, pages = {arXiv:2302.07517}, title = {Extensible Motion-based Identification of XR Users with Non-Specific Motion}, year = 2023 }
• Optimizing storage assignment, order picking, and their interaction in mezzanine warehouses. Lesch, Veronika; Müller, Patrick B.M.; Krämer, Moritz; Hadry, Marius; Kounev, Samuel; Krupitzer, Christian. In Applied intelligence, p. 25. 2023.
  • [ BibTeX ]
  • [ URL ]
  @article{lesch2023optimizing, author = {Lesch, Veronika and Müller, Patrick B.M. and Krämer, Moritz and Hadry, Marius and Kounev, Samuel and Krupitzer, Christian}, journal = {Applied intelligence}, keywords = {t_journalmagazine}, month = {02}, pages = 25, title = {Optimizing storage assignment, order picking, and their interaction in mezzanine warehouses}, year = 2023 }
• Traffic-Adaptive Scheme for SDN Control Plane with Containerized Architecture. AnhKhoa, Dang; TrungKiem, Nguyen; TrungKien, Nguyen; NgocTuan, Nguyen; Huu Thanh, Nguyen. In 2023 17th International Conference on Ubiquitous Information Management and Communication (IMCOM). 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Software-Defined Networking (SDN) is gaining attention for its flexibility in programmability. It enhances network configuration and provides global visibility for administrators via a single interface. However, the centralized nature of SDN exposes many issues in scalability and resiliency. In this paper, with the advent of cloud computing, we present a containerized architecture capable of fast scaling up and down based on traffic load for SDN control plane. With our novel traffic-adaptive algorithm, the results show that the proposed system is able to fit performance with high incoming new-flow requests and scale down underused controllers for resource efficiency.

  @inproceedings{info3-inproceedings-2023-3, abstract = {Software-Defined Networking (SDN) is gaining attention for its flexibility in programmability. It enhances network configuration and provides global visibility for administrators via a single interface. However, the centralized nature of SDN exposes many issues in scalability and resiliency. In this paper, with the advent of cloud computing, we present a containerized architecture capable of fast scaling up and down based on traffic load for SDN control plane. With our novel traffic-adaptive algorithm, the results show that the proposed system is able to fit performance with high incoming new-flow requests and scale down underused controllers for resource efficiency.}, author = {AnhKhoa, Dang and TrungKiem, Nguyen and TrungKien, Nguyen and NgocTuan, Nguyen and Huu Thanh, Nguyen}, booktitle = {2023 17th International Conference on Ubiquitous Information Management and Communication (IMCOM)}, keywords = {myown}, month = {01}, title = {Traffic-Adaptive Scheme for SDN Control Plane with Containerized Architecture}, year = 2023 }
• Industrial User Experience Index vs. Quality of Experience Models. Hoßfeld, Tobias; Seufert, Anika; Loh, Frank; Wunderer, Stefan; Davies, John. In IEEE Communications Magazine, 61(1), pp. 98–104. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Network operators have increased interest in understanding and quantifying the user perceived quality of experience (QoE). Appropriate QoE models allow mapping of measurable QoS parameters to QoE metrics like mean opinion scores (MOS) or poor-or-worse (PoW) ratios. Unfortunately, there are no QoE models for all applications available yet, and development and standardization is rather time-consuming. For that reason, industry often implements simple but effective approaches based on expert knowledge to get a user experience index able to deliver high value insights. This index is often defined based on thresholds of measurable QoS parameters to classify the resulting user experience. The question arises whether such a threshold-based user experience index can properly estimate the QoE in a system. We therefore answer in this work whether the user experience index is able to quantify the expected QoE in a system and if other QoE metrics like PoW ratios can be derived. Furthermore, we discuss the interpretation and the limits of the index. As a key contribution, we present a detailed systematic analysis of the threshold-based QoE concept and discuss its usability as QoE estimation methodology for industry.

  @article{info3-article-2023-7, abstract = {Network operators have increased interest in understanding and quantifying the user perceived quality of experience (QoE). Appropriate QoE models allow mapping of measurable QoS parameters to QoE metrics like mean opinion scores (MOS) or poor-or-worse (PoW) ratios. Unfortunately, there are no QoE models for all applications available yet, and development and standardization is rather time-consuming. For that reason, industry often implements simple but effective approaches based on expert knowledge to get a user experience index able to deliver high value insights. This index is often defined based on thresholds of measurable QoS parameters to classify the resulting user experience. The question arises whether such a threshold-based user experience index can properly estimate the QoE in a system. We therefore answer in this work whether the user experience index is able to quantify the expected QoE in a system and if other QoE metrics like PoW ratios can be derived. Furthermore, we discuss the interpretation and the limits of the index. As a key contribution, we present a detailed systematic analysis of the threshold-based QoE concept and discuss its usability as QoE estimation methodology for industry.}, author = {Hoßfeld, Tobias and Seufert, Anika and Loh, Frank and Wunderer, Stefan and Davies, John}, journal = {IEEE Communications Magazine}, keywords = {5gqmon}, month = {01}, number = 1, pages = {98-104}, title = {Industrial User Experience Index vs. Quality of Experience Models}, volume = 61, year = 2023 }
• Searching for the Ground Truth: Assessing the Similarity of Benchmarking Runs. Bauer, Andr{é}; Straesser, Martin; Leznik, Mark; Beierlieb, Lukas; Hadry, Marius; Hudson, Nathaniel; Chard, Kyle; Kounev, Samuel; Foster, Ian. In Companion of the 2023 ACM/SPEC International Conference on Performance Engineering, of ICPE ’23 Companion, pp. 95–99. Association for Computing Machinery, New York, NY, USA, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Stable and repeatable measurements are essential for comparing the performance of different systems or applications, and benchmarks are used to ensure accuracy and replication. However, if the corresponding measurements are not stable and repeatable, wrong conclusions can be drawn. To facilitate the task of determining whether the measurements are similar, we used a data set of 586 micro-benchmarks to (i) analyze the data set itself, (ii) examine our previous approach, and (iii) propose and evaluate a heuristic. To evaluate the different approaches, we perform a peer review to assess the dissimilarity of the benchmark runs. Our results show that this task is challenging even for humans and that our heuristic exhibits a sensitivity of 92%.

  @inproceedings{10.1145/3578245.3584693, abstract = {Stable and repeatable measurements are essential for comparing the performance of different systems or applications, and benchmarks are used to ensure accuracy and replication. However, if the corresponding measurements are not stable and repeatable, wrong conclusions can be drawn. To facilitate the task of determining whether the measurements are similar, we used a data set of 586 micro-benchmarks to (i) analyze the data set itself, (ii) examine our previous approach, and (iii) propose and evaluate a heuristic. To evaluate the different approaches, we perform a peer review to assess the dissimilarity of the benchmark runs. Our results show that this task is challenging even for humans and that our heuristic exhibits a sensitivity of 92%.}, address = {New York, NY, USA}, author = {Bauer, Andr\'{e} and Straesser, Martin and Leznik, Mark and Beierlieb, Lukas and Hadry, Marius and Hudson, Nathaniel and Chard, Kyle and Kounev, Samuel and Foster, Ian}, booktitle = {Companion of the 2023 ACM/SPEC International Conference on Performance Engineering}, keywords = {distance_measures}, pages = {95–99}, publisher = {Association for Computing Machinery}, series = {ICPE '23 Companion}, title = {Searching for the Ground Truth: Assessing the Similarity of Benchmarking Runs}, year = 2023 }
• Occupational Fraud Detection through Agent-based Data Generation. Tritscher, Julian; Roos, Alexander; Schlör, Daniel; Hotho, Andreas; Krause, Anna. In The 8th Workshop on MIning DAta for financial applicationS MIDAS 2023 - to appear. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Occupational fraud is an increasing concern for enterprises that is estimated to cause losses of around 5% of company revenue each year. With the increasing data tracked by companies through enterprise resource planning systems, recent research has taken interest in the automated detection of occupational fraud. Automated detection is however hindered by the unavailability of labeled fraud cases which require known occupational frauds within company data and costly expert annotation. Even despite the existence of anomaly detection methods that can be trained on unsupervised data, selecting the ideal preprocessing techniques, the most suitable model, and the optimal hyperparameters necessitates the availability of labeled data for evaluation purposes. To alleviate this issue, we propose to use simulation through multi-agent systems for generating business processes according to best practices from economics and creating labeled synthetic data that closely matches a given unlabeled real-world dataset. We extend an existing simulation by incorporating functionality for including, tracking and automatic labeling of occupational fraud cases. Using this simulation, we propose a framework that decides on important design choices for fraud detection models in enterprise resource planning data and does not require labeled real-world data. We demonstrate in multiple experiments that the framework can aid automated occupational fraud detection through data generation.

  @article{tritscher2023occupational, abstract = {Occupational fraud is an increasing concern for enterprises that is estimated to cause losses of around 5% of company revenue each year. With the increasing data tracked by companies through enterprise resource planning systems, recent research has taken interest in the automated detection of occupational fraud. Automated detection is however hindered by the unavailability of labeled fraud cases which require known occupational frauds within company data and costly expert annotation. Even despite the existence of anomaly detection methods that can be trained on unsupervised data, selecting the ideal preprocessing techniques, the most suitable model, and the optimal hyperparameters necessitates the availability of labeled data for evaluation purposes. To alleviate this issue, we propose to use simulation through multi-agent systems for generating business processes according to best practices from economics and creating labeled synthetic data that closely matches a given unlabeled real-world dataset. We extend an existing simulation by incorporating functionality for including, tracking and automatic labeling of occupational fraud cases. Using this simulation, we propose a framework that decides on important design choices for fraud detection models in enterprise resource planning data and does not require labeled real-world data. We demonstrate in multiple experiments that the framework can aid automated occupational fraud detection through data generation.}, author = {Tritscher, Julian and Roos, Alexander and Schlör, Daniel and Hotho, Andreas and Krause, Anna}, journal = {The 8th Workshop on MIning DAta for financial applicationS MIDAS 2023 - to appear}, keywords = {mas}, title = {Occupational Fraud Detection through Agent-based Data Generation}, year = 2023 }
• Efficient graph-based gateway placement for large-scale LoRaWAN deployments. Loh, Frank; Mehling, Noah; Geißler, Stefan. In Computer Communications, 204, pp. 11–23. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  Low Power Wide Area Networks with Long Range Wide Area Networks (LoRaWANs) as one of their most prominent representatives are promising solutions for future Internet of Things deployments. The technology is characterized by low energy requirements leading to long battery lifetimes. However, the drawbacks are limited throughput rates and the unreliable nature of the LoRa technology. Specifically its random channel access approach leads to significant message collisions and thus, data loss in larger deployments. From a network planning point of view, the reduction of potentially colliding messages at the frequency bands in combination with limiting the transmission duration of messages is a promising approach. For that reason, we present a novel graph-based gateway placement approach. We show that our approach performs similar to state-of-the-art related work in the worst case and reduces the required number of gateways by up to 40% while reducing the collision probability by up to 70%. Furthermore, we overcome the challenge of scalability of our approach when placing gateways in very large networks. By splitting the problem into smaller problem instances by pre-clustering, we can solve arbitrarily large instances efficiently without a significant increase in number of required gateways in real networks.

  @article{info3-article-2023-6, abstract = {Low Power Wide Area Networks with Long Range Wide Area Networks (LoRaWANs) as one of their most prominent representatives are promising solutions for future Internet of Things deployments. The technology is characterized by low energy requirements leading to long battery lifetimes. However, the drawbacks are limited throughput rates and the unreliable nature of the LoRa technology. Specifically its random channel access approach leads to significant message collisions and thus, data loss in larger deployments. From a network planning point of view, the reduction of potentially colliding messages at the frequency bands in combination with limiting the transmission duration of messages is a promising approach. For that reason, we present a novel graph-based gateway placement approach. We show that our approach performs similar to state-of-the-art related work in the worst case and reduces the required number of gateways by up to 40% while reducing the collision probability by up to 70%. Furthermore, we overcome the challenge of scalability of our approach when placing gateways in very large networks. By splitting the problem into smaller problem instances by pre-clustering, we can solve arbitrarily large instances efficiently without a significant increase in number of required gateways in real networks.}, author = {Loh, Frank and Mehling, Noah and Geißler, Stefan}, journal = {Computer Communications}, keywords = {myown}, month = {02}, pages = {11-23}, title = {Efficient graph-based gateway placement for large-scale LoRaWAN deployments}, volume = 204, year = 2023 }
• DBM: Decentralized Burst Mitigation for Periodic LoRa Devices using Self-Organizing Radio Access. Raffeck, Simon; Geißler, Stefan; Hoßfeld, Tobias. In ICC 2023 - IEEE International Conference on Communications. 2023.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2023-7, author = {Raffeck, Simon and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {ICC 2023 - IEEE International Conference on Communications}, keywords = {can}, title = {DBM: Decentralized Burst Mitigation for Periodic LoRa Devices using Self-Organizing Radio Access}, year = 2023 }
• Morphing Planar Graph Drawings Through {3D}. Buchin, Kevin; Evans, Will; Frati, Fabrizio; Kostitsyna, Irina; Löffler, Maarten; Ophelders, Tim; Wolff, Alexander. In Proc. 49th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM’23), Vol. 13878 of Lecture Notes in Computer Science, L. Gąsieniec (ed.), pp. 80–95. Springer-Verlag, 2023.
  • [ BibTeX ]
  @inproceedings{befklow-mpgdt3d-SOFSEM23, author = {Buchin, Kevin and Evans, Will and Frati, Fabrizio and Kostitsyna, Irina and Löffler, Maarten and Ophelders, Tim and Wolff, Alexander}, booktitle = {Proc. 49th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM'23)}, editor = {Gąsieniec, Leszek}, keywords = {myown}, pages = {80–95}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Morphing Planar Graph Drawings Through {3D}}, volume = 13878, year = 2023 }
• Generating Microservice Applications for Performance Benchmarking. Lubas, Yannik; Straesser, Martin; Kounev, Samuel. 2023.
  • [ BibTeX ]
  @presentation{lubas2023generating, author = {Lubas, Yannik and Straesser, Martin and Kounev, Samuel}, keywords = {microservices}, title = {Generating Microservice Applications for Performance Benchmarking}, year = 2023 }
• Morphing Planar Graph Drawings Through {3D}. Buchin, Kevin; Evans, Will; Frati, Fabrizio; Kostitsyna, Irina; Löffler, Maarten; Ophelders, Tim; Wolff, Alexander. In Computing in Geometry and Topology, 2(1), pp. 5:1–5:18. 2023.
  • [ Abstract ]
  • [ BibTeX ]
  In this paper, we investigate crossing-free 3D morphs between planar straight-line drawings. We show that, for any two (not necessarily topologically equivalent) planar straight-line drawings of an $n$-vertex planar graph, there exists a piecewise-linear crossing-free 3D morph with $O(n^2)$ steps that transforms one drawing into the other. We also give some evidence why it is difficult to obtain a linear lower bound (which exists in 2D) for the number of steps of a crossing-free 3D morph.

  @article{befklow-mpgdt3d-CGT23, abstract = {In this paper, we investigate crossing-free 3D morphs between planar straight-line drawings. We show that, for any two (not necessarily topologically equivalent) planar straight-line drawings of an $n$-vertex planar graph, there exists a piecewise-linear crossing-free 3D morph with $O(n^2)$ steps that transforms one drawing into the other. We also give some evidence why it is difficult to obtain a linear lower bound (which exists in 2D) for the number of steps of a crossing-free 3D morph.}, author = {Buchin, Kevin and Evans, Will and Frati, Fabrizio and Kostitsyna, Irina and Löffler, Maarten and Ophelders, Tim and Wolff, Alexander}, journal = {Computing in Geometry and Topology}, keywords = {morphing}, number = 1, pages = {5:1–5:18}, title = {Morphing Planar Graph Drawings Through {3D}}, volume = 2, year = 2023 }
• Coloring Mixed and Directional Interval Graphs. Gutowski, Grzegorz; Mittelstädt, Florian; Rutter, Ignaz; Spoerhase, Joachim; Wolff, Alexander; Zink, Johannes. In Proc. 30th Int. Symp. Graph Drawing \& Network Vis. (GD’22), Vol. 13764 of Lecture Notes in Computer Science, P. Angelini, R. von Hanxleden (eds.), pp. 418–431. Springer-Verlag, 2023.
  • [ BibTeX ]
  @inproceedings{gmrswz-cmdig-GD22, author = {Gutowski, Grzegorz and Mittelstädt, Florian and Rutter, Ignaz and Spoerhase, Joachim and Wolff, Alexander and Zink, Johannes}, booktitle = {Proc. 30th Int. Symp. Graph Drawing \& Network Vis. (GD'22)}, editor = {Angelini, Patrizio and von Hanxleden, Reinhard}, keywords = {myown}, pages = {418–431}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Coloring Mixed and Directional Interval Graphs}, volume = 13764, year = 2023 }
• Modulith: A Game Engine Made for Modding. G{ö}tz, Daniel; von Mammen, Sebastian. In Proceedings of the 18th International Conference on the Foundations of Digital Games, of FDG ’23. Association for Computing Machinery, Lisbon, Portugal, 2023.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  A modular game engine facilitates development of game technologies and game contents. The latter includes content creation by the player in the form of modding. Based on a requirements analysis to meet the needs of developers, gamers and modders, we present a novel concept for a fully modular game engine. This concept includes a module system, which allows additional code to be loaded at runtime, and various support systems that simplify the use of the engine and the creation of modules. We present a proof-of-concept implementation, underline its fulfillment of the unearthed requirements, and demonstrate its use.

  @inproceedings{10.1145/3582437.3582486, abstract = {A modular game engine facilitates development of game technologies and game contents. The latter includes content creation by the player in the form of modding. Based on a requirements analysis to meet the needs of developers, gamers and modders, we present a novel concept for a fully modular game engine. This concept includes a module system, which allows additional code to be loaded at runtime, and various support systems that simplify the use of the engine and the creation of modules. We present a proof-of-concept implementation, underline its fulfillment of the unearthed requirements, and demonstrate its use.}, address = {New York, NY, USA}, author = {G\"{o}tz, Daniel and von Mammen, Sebastian}, booktitle = {Proceedings of the 18th International Conference on the Foundations of Digital Games}, keywords = {myown}, publisher = {Association for Computing Machinery}, series = {FDG '23}, title = {Modulith: A Game Engine Made for Modding}, year = 2023 }
• SKOS-Utils: Developing and Checking SKOS Knowledge Graphs (Tool Presentation). Baumeister, Joachim; Ross, Valentin. In LWDA 2023 - Learning, Knowledge, Data, Analysis. 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{BR:FGWM:23, author = {Baumeister, Joachim and Ross, Valentin}, booktitle = {LWDA 2023 - Learning, Knowledge, Data, Analysis}, keywords = {skos}, title = {SKOS-Utils: Developing and Checking SKOS Knowledge Graphs (Tool Presentation)}, year = 2023 }
• A Constant-Factor Approximation Algorithm for Reconciliation $k$-Median. Spoerhase, Joachim; Khodamoradi, Kamyar; Riegel, Benedikt; Ordozgoiti, Bruno; Gionis, Aristides. In Proc. International Conference on Artificial Intelligence and Statistics (AISTATS’23), Vol. 206, pp. 1719–1746. {PMLR}, 2023.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{spoerhase-etal23:recon-k-median, author = {Spoerhase, Joachim and Khodamoradi, Kamyar and Riegel, Benedikt and Ordozgoiti, Bruno and Gionis, Aristides}, booktitle = {Proc. International Conference on Artificial Intelligence and Statistics (AISTATS'23)}, keywords = {reconciliation}, pages = {1719–1746}, publisher = {{PMLR}}, title = {A Constant-Factor Approximation Algorithm for Reconciliation $k$-Median}, volume = 206, year = 2023 }
• NB-IoT vs. LTE-M: Measurement Study of the Energy Consumption of LPWAN Technologies. Vomhoff, Viktoria; Raffeck, Simon; Geißler, Stefan; Hoßfeld, Tobias. In 2023 IEEE International Conference on Communications Workshops (ICC Workshops). 2023.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2023-10, author = {Vomhoff, Viktoria and Raffeck, Simon and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {2023 IEEE International Conference on Communications Workshops (ICC Workshops)}, keywords = {can}, title = {NB-IoT vs. LTE-M: Measurement Study of the Energy Consumption of LPWAN Technologies}, year = 2023 }
• Generating Microservice Applications for Performance Benchmarking. Lubas, Yannik; Straesser, Martin; Kounev, Samuel. 2023.
  • [ BibTeX ]
  @presentation{lubas2023generating, author = {Lubas, Yannik and Straesser, Martin and Kounev, Samuel}, keywords = {microservices}, title = {Generating Microservice Applications for Performance Benchmarking}, year = 2023 }

• Does Distance Matter? Embodiment and Perception of Personalized Avatars in Relation to the Self-Observation Distance in Virtual Reality. Wolf, Erik; Döllinger, Nina; Mal, David; Wenninger, Stephan; Bartl, Andrea; Botsch, Mario; Latoschik, Marc Erich; Wienrich, Carolin. In Frontiers in Virtual Reality, 3. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Virtual reality applications employing avatar embodiment typically use virtual mirrors to allow users to perceive their digital selves not only from a first-person perspective but also from a holistic third-person view. However, due to distance-related biases such as the distance compression effect or a reduced relative rendering resolution, the self-observation distance (SOD) between the user and the virtual mirror might influence how users perceive their embodied avatar. Our article systematically investigates the effects of a short (1 meter), middle (2.5 meter), and far (4 meter) SOD between user and mirror on the perception of personalized and self-embodied avatars. The avatars were photorealistic reconstructed using state-of-the-art photogrammetric methods. Thirty participants were repeatedly exposed to their real-time animated self-embodied avatars in each of the three SOD conditions. In each condition, the personalized avatars were repeatedly altered in their body weight, and participants were asked to judge the (1) sense of embodiment, (2) body weight perception, and (3) affective appraisal towards their avatar. We found that the different SODs are unlikely to influence any of our measures except for the perceived body weight estimation difficulty. Here, the participants judged the difficulty significantly higher for the farthest SOD. We further found that the participants' self-esteem significantly impacted their ability to modify their avatar's body weight to their current body weight and that it positively correlated with the perceived attractiveness of the avatar. Additionally, the participants' concerns about their body shape affected how eerie they perceived their avatars. Both measures influenced the perceived body weight estimation difficulty. For practical application, we conclude that the virtual mirror in embodiment scenarios can be freely placed and varied at a distance of one to four meters from the user without expecting major effects on the perception of the avatar.

  @article{wolf2022distance, abstract = {Virtual reality applications employing avatar embodiment typically use virtual mirrors to allow users to perceive their digital selves not only from a first-person perspective but also from a holistic third-person view. However, due to distance-related biases such as the distance compression effect or a reduced relative rendering resolution, the self-observation distance (SOD) between the user and the virtual mirror might influence how users perceive their embodied avatar. Our article systematically investigates the effects of a short (1 meter), middle (2.5 meter), and far (4 meter) SOD between user and mirror on the perception of personalized and self-embodied avatars. The avatars were photorealistic reconstructed using state-of-the-art photogrammetric methods. Thirty participants were repeatedly exposed to their real-time animated self-embodied avatars in each of the three SOD conditions. In each condition, the personalized avatars were repeatedly altered in their body weight, and participants were asked to judge the (1) sense of embodiment, (2) body weight perception, and (3) affective appraisal towards their avatar. We found that the different SODs are unlikely to influence any of our measures except for the perceived body weight estimation difficulty. Here, the participants judged the difficulty significantly higher for the farthest SOD. We further found that the participants' self-esteem significantly impacted their ability to modify their avatar's body weight to their current body weight and that it positively correlated with the perceived attractiveness of the avatar. Additionally, the participants' concerns about their body shape affected how eerie they perceived their avatars. Both measures influenced the perceived body weight estimation difficulty. For practical application, we conclude that the virtual mirror in embodiment scenarios can be freely placed and varied at a distance of one to four meters from the user without expecting major effects on the perception of the avatar.}, author = {Wolf, Erik and Döllinger, Nina and Mal, David and Wenninger, Stephan and Bartl, Andrea and Botsch, Mario and Latoschik, Marc Erich and Wienrich, Carolin}, journal = {Frontiers in Virtual Reality}, keywords = {dmal}, title = {Does Distance Matter? Embodiment and Perception of Personalized Avatars in Relation to the Self-Observation Distance in Virtual Reality}, volume = 3, year = 2022 }
• Investigating Adaptive Robot Tutoring in a Long-Term Interaction in Higher Education. Donnermann, Melissa; Schaper, Philipp; Lugrin, Birgit. In 31st IEEE International Conference on Robot and Human Interactive Communication (RO-MAN 2022), pp. 171–178. IEEE, 2022.
  • [ BibTeX ]
  @inproceedings{donnermann2022investigating, author = {Donnermann, Melissa and Schaper, Philipp and Lugrin, Birgit}, booktitle = {31st IEEE International Conference on Robot and Human Interactive Communication (RO-MAN 2022)}, keywords = {mi}, organization = {IEEE}, pages = {171-178}, title = {Investigating Adaptive Robot Tutoring in a Long-Term Interaction in Higher Education}, year = 2022 }
• Remote at Court – Challenges and Solutions of Video Conferencing in the Judicial System. Wienrich, Carolin; Fries, Lennart; Latoschik, Marc Erich. In Proceedings 25th HCI International Conference, Vol. Design, Operation and Evaluation of Mobile Communications, pp. 82–106. Springer, 2022.
  • [ BibTeX ]
  @inproceedings{wienrich2022remote, author = {Wienrich, Carolin and Fries, Lennart and Latoschik, Marc Erich}, booktitle = {Proceedings 25th HCI International Conference}, keywords = {hci-uwb}, pages = {82-106}, publisher = {Springer}, title = {Remote at Court – Challenges and Solutions of Video Conferencing in the Judicial System}, volume = {Design, Operation and Evaluation of Mobile Communications}, year = 2022 }
• {Real-Time Music-Driven Movie Design Framework}. Hofmann, Sarah; Seeger, Maximilian; Rogge-Pott, Henning; Mammen, Sebastian von. In Workshop on Intelligent Cinematography and Editing, R. Ronfard, H.-Y. Wu (eds.). The Eurographics Association, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{10.2312:wiced.20221052, author = {Hofmann, Sarah and Seeger, Maximilian and Rogge-Pott, Henning and Mammen, Sebastian von}, booktitle = {Workshop on Intelligent Cinematography and Editing}, editor = {Ronfard, Rémi and Wu, Hui-Yin}, keywords = {myown}, publisher = {The Eurographics Association}, title = {{Real-Time Music-Driven Movie Design Framework}}, year = 2022 }
• Embodied Gambling–Investigating the Influence of Level of Embodiment, Avatar Appearance, and Virtual Environment Design on an Online VR Slot Machine. Oberdörfer, Sebastian; Schraudt, David; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 3. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Slot machines are one of the most played games by players suffering from gambling disorder. New technologies like immersive Virtual Reality (VR) offer more possibilities to exploit erroneous beliefs in the context of gambling. Recent research indicates a higher risk potential when playing a slot machine in VR than on desktop. To continue this investigation, we evaluate the effects of providing different degrees of embodiment, i.e., minimal and full embodiment. The avatars used for the full embodiment further differ in their appearance, i.e., they elicit a high or a low socio-economic status. The virtual environment (VE) design can cause a potential influence on the overall gambling behavior. Thus, we also embed the slot machine in two different VEs that differ in their emotional design: a colorful underwater playground environment and a virtual counterpart of our lab. These design considerations resulted in four different versions of the same VR slot machine: 1) full embodiment with high socio-economic status, 2) full embodiment with low socio-economic status, 3) minimal embodiment playground VE, and 4) minimal embodiment laboratory VE. Both full embodiment versions also used the playground VE. We determine the risk potential by logging gambling frequency as well as stake size, and measuring harm-inducing factors, i.e., dissociation, urge to gamble, dark flow, and illusion of control, using questionnaires. Following a between groups experimental design, 82 participants played for 20 game rounds one of the four versions. We recruited our sample from the students enrolled at the University of Würzburg. Our safety protocol ensured that only participants without any recent gambling activity took part in the experiment. In this comparative user study, we found no effect of the embodiment nor VE design on neither the gambling frequency, stake sizes, nor risk potential. However, our results provide further support for the hypothesis of the higher visual angle on gambling stimuli and hence the increased emotional response being the true cause for the higher risk potential.

  @article{oberdorfer2022embodied, abstract = {Slot machines are one of the most played games by players suffering from gambling disorder. New technologies like immersive Virtual Reality (VR) offer more possibilities to exploit erroneous beliefs in the context of gambling. Recent research indicates a higher risk potential when playing a slot machine in VR than on desktop. To continue this investigation, we evaluate the effects of providing different degrees of embodiment, i.e., minimal and full embodiment. The avatars used for the full embodiment further differ in their appearance, i.e., they elicit a high or a low socio-economic status. The virtual environment (VE) design can cause a potential influence on the overall gambling behavior. Thus, we also embed the slot machine in two different VEs that differ in their emotional design: a colorful underwater playground environment and a virtual counterpart of our lab. These design considerations resulted in four different versions of the same VR slot machine: 1) full embodiment with high socio-economic status, 2) full embodiment with low socio-economic status, 3) minimal embodiment playground VE, and 4) minimal embodiment laboratory VE. Both full embodiment versions also used the playground VE. We determine the risk potential by logging gambling frequency as well as stake size, and measuring harm-inducing factors, i.e., dissociation, urge to gamble, dark flow, and illusion of control, using questionnaires. Following a between groups experimental design, 82 participants played for 20 game rounds one of the four versions. We recruited our sample from the students enrolled at the University of Würzburg. Our safety protocol ensured that only participants without any recent gambling activity took part in the experiment. In this comparative user study, we found no effect of the embodiment nor VE design on neither the gambling frequency, stake sizes, nor risk potential. However, our results provide further support for the hypothesis of the higher visual angle on gambling stimuli and hence the increased emotional response being the true cause for the higher risk potential.}, author = {Oberdörfer, Sebastian and Schraudt, David and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {myown}, title = {Embodied Gambling–Investigating the Influence of Level of Embodiment, Avatar Appearance, and Virtual Environment Design on an Online VR Slot Machine}, volume = 3, year = 2022 }
• A multi-method approach to compare presence, fear induction and desensitization in survival horror games within the reality-virtuality-continuum. Steinhaeusser, Sophia C.; Eckstein, Benjamin; Lugrin, Birgit. In Entertainment Computing, p. 100539. Elsevier, 2022.
  • [ BibTeX ]
  @article{Steinhaeusser_2022, author = {Steinhaeusser, Sophia C. and Eckstein, Benjamin and Lugrin, Birgit}, journal = {Entertainment Computing}, keywords = {steinhaeusser}, pages = 100539, publisher = {Elsevier}, title = {A multi-method approach to compare presence, fear induction and desensitization in survival horror games within the reality-virtuality-continuum}, year = 2022 }
• Automated Blendshape Personalization for Faithful Face Animations Using Commodity Smartphones. Menzel, Timo; Botsch, Mario; Latoschik, Marc Erich. In Proceedings of the 28th ACM Symposium on Virtual Reality Software and Technology (VRST ’22). Association for Computing Machinery, New York, NY, USA, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Digital reconstruction of humans has various interesting use-cases. Animated virtual humans, avatars and agents alike, are the central entities in virtual embodied human-computer and human-human encounters in social XR. Here, a faithful reconstruction of facial expressions becomes paramount due to their prominent role in non-verbal behavior and social interaction. Current XR-platforms, like Unity 3D or the Unreal Engine, integrate recent smartphone technologies to animate faces of virtual humans by facial motion capturing. Using the same technology, this article presents an optimization-based approach to generate personalized blendshapes as animation targets for facial expressions. The proposed method combines a position-based optimization with a seamless partial deformation transfer, necessary for a faithful reconstruction. Our method is fully automated and considerably outperforms existing solutions based on example-based facial rigging or deformation transfer, and overall results in a much lower reconstruction error. It also neatly integrates with recent smartphone-based reconstruction pipelines for mesh generation and automated rigging, further paving the way to a widespread application of human-like and personalized avatars and agents in various use-cases.

  @inproceedings{menzel2022automated, abstract = {Digital reconstruction of humans has various interesting use-cases. Animated virtual humans, avatars and agents alike, are the central entities in virtual embodied human-computer and human-human encounters in social XR. Here, a faithful reconstruction of facial expressions becomes paramount due to their prominent role in non-verbal behavior and social interaction. Current XR-platforms, like Unity 3D or the Unreal Engine, integrate recent smartphone technologies to animate faces of virtual humans by facial motion capturing. Using the same technology, this article presents an optimization-based approach to generate personalized blendshapes as animation targets for facial expressions. The proposed method combines a position-based optimization with a seamless partial deformation transfer, necessary for a faithful reconstruction. Our method is fully automated and considerably outperforms existing solutions based on example-based facial rigging or deformation transfer, and overall results in a much lower reconstruction error. It also neatly integrates with recent smartphone-based reconstruction pipelines for mesh generation and automated rigging, further paving the way to a widespread application of human-like and personalized avatars and agents in various use-cases.}, address = {New York, NY, USA}, author = {Menzel, Timo and Botsch, Mario and Latoschik, Marc Erich}, booktitle = {Proceedings of the 28th ACM Symposium on Virtual Reality Software and Technology (VRST ’22)}, keywords = {via-vr}, number = 22, publisher = {Association for Computing Machinery}, title = {Automated Blendshape Personalization for Faithful Face Animations Using Commodity Smartphones}, year = 2022 }
• Classroom management competency enhancement for student teachers using a fully immersive virtual classroom. Seufert, Christian; Oberd{ö}rfer, Sebastian; Roth, Alice; Grafe, Silke; Lugrin, Jean-Luc; Latoschik, Marc Erich. In Computers & Education, 179, p. 104410. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The purpose of this study is to examine whether pre-service teachers studying classroom management (CM) in a virtual reality (VR)-supported setting enhance their CM competencies more than students do in a setting using conventional methods. With this aim in mind and to address a lack of available situations of practicing and reflecting CM competencies besides simply gaining theoretical knowledge about CM in education, we integrated a novel fully immersive VR application in selected CM courses. We evaluated the development of self-assessed and instructor-rated CM competencies and the learning quality in the different learning conditions. Additionally, we evaluated the presence, social presence, believability and utility of the VR application and the VR-assisted and video-assisted course. Participants were pre-service teachers (n = 55) of the University of W{ü}rzburg who participated in a quasi-experimental pre-test/post-test intervention. The students were randomly assigned to one of two intervention groups: the test group used the virtual classroom Breaking Bad Behaviors (BBB) during the term (n = 39), and the comparison group's learning was video-assisted (n = 16). The instructor rating shows significant differences between the VR group and the video group, the two points of measurement and for the interaction between the condition and time of measurement. It demonstrates a highly significant improvement in CM competencies in the VR setting between the pre-test and post-test (p < 0.001, Cohen's d = 1.06) as compared to the video-based setting. The participants of the VR setting themselves rated their CM competencies in the post-test significantly higher than in the pre-test (p = 0.02, Cohen's d = 0.39). Interestingly, the video group also rated themselves better in the post-test (p = 0.02, Cohen's d = 0.67), which reveals that self-assessment and external assessment show different results. In addition, we observed that even if both groups gained similar theoretical knowledge, the CM competencies developed to a greater degree in the VR-based settings. The participants rated the CM training system a useful tool to evaluate and reflect on individual teacher actions. Its immersion contributes to a high presence and the simulation of realistic scenarios in a CM course. These findings suggest that VR-based settings can lead to a higher benefit in the enhancement of pre-service teachers' CM competencies.

  @article{seufert:2022n, abstract = {The purpose of this study is to examine whether pre-service teachers studying classroom management (CM) in a virtual reality (VR)-supported setting enhance their CM competencies more than students do in a setting using conventional methods. With this aim in mind and to address a lack of available situations of practicing and reflecting CM competencies besides simply gaining theoretical knowledge about CM in education, we integrated a novel fully immersive VR application in selected CM courses. We evaluated the development of self-assessed and instructor-rated CM competencies and the learning quality in the different learning conditions. Additionally, we evaluated the presence, social presence, believability and utility of the VR application and the VR-assisted and video-assisted course. Participants were pre-service teachers (n = 55) of the University of W{\"u}rzburg who participated in a quasi-experimental pre-test/post-test intervention. The students were randomly assigned to one of two intervention groups: the test group used the virtual classroom Breaking Bad Behaviors (BBB) during the term (n = 39), and the comparison group's learning was video-assisted (n = 16). The instructor rating shows significant differences between the VR group and the video group, the two points of measurement and for the interaction between the condition and time of measurement. It demonstrates a highly significant improvement in CM competencies in the VR setting between the pre-test and post-test (p < 0.001, Cohen's d = 1.06) as compared to the video-based setting. The participants of the VR setting themselves rated their CM competencies in the post-test significantly higher than in the pre-test (p = 0.02, Cohen's d = 0.39). Interestingly, the video group also rated themselves better in the post-test (p = 0.02, Cohen's d = 0.67), which reveals that self-assessment and external assessment show different results. In addition, we observed that even if both groups gained similar theoretical knowledge, the CM competencies developed to a greater degree in the VR-based settings. The participants rated the CM training system a useful tool to evaluate and reflect on individual teacher actions. Its immersion contributes to a high presence and the simulation of realistic scenarios in a CM course. These findings suggest that VR-based settings can lead to a higher benefit in the enhancement of pre-service teachers' CM competencies.}, author = {Seufert, Christian and Oberd{\"o}rfer, Sebastian and Roth, Alice and Grafe, Silke and Lugrin, Jean-Luc and Latoschik, Marc Erich}, journal = {Computers & Education}, keywords = {Initial}, pages = 104410, title = {Classroom management competency enhancement for student teachers using a fully immersive virtual classroom}, volume = 179, year = 2022 }
• The State of Serverless Applications: Collection, Characterization, and Community Consensus. Eismann, Simon; Scheuner, Joel; van Eyk, Erwin; Schwinger, Maximilian; Grohmann, Johannes; Herbst, Nikolas; Abad, Cristina; Iosup, Alexandru. In Transactions on Software Engineering, 48(10), pp. 4152–4166. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Over the last five years, all major cloud platform providers have increased their serverless offerings. Many early adopters report significant benefits for serverless-based over traditional applications, and many companies are considering moving to serverless themselves. However, currently there exist only few, scattered, and sometimes even conflicting reports on when serverless applications are well suited and what the best practices for their implementation are. We address this problem in the present study about the state of serverless applications. We collect descriptions of 89 serverless applications from open-source projects, academic literature, industrial literature, and domain-specific feedback. We analyze 16 characteristics that describe why and when successful adopters are using serverless applications, and how they are building them. We further compare the results of our characterization study to 10 existing, mostly industrial, studies and datasets; this allows us to identify points of consensus across multiple studies, investigate points of disagreement, and overall confirm the validity of our results. The results of this study can help managers to decide if they should adopt serverless technology, engineers to learn about current practices of building serverless applications, and researchers and platform providers to better understand the current landscape of serverless applications.

  @article{eismann2021state, abstract = {Over the last five years, all major cloud platform providers have increased their serverless offerings. Many early adopters report significant benefits for serverless-based over traditional applications, and many companies are considering moving to serverless themselves. However, currently there exist only few, scattered, and sometimes even conflicting reports on when serverless applications are well suited and what the best practices for their implementation are. We address this problem in the present study about the state of serverless applications. We collect descriptions of 89 serverless applications from open-source projects, academic literature, industrial literature, and domain-specific feedback. We analyze 16 characteristics that describe why and when successful adopters are using serverless applications, and how they are building them. We further compare the results of our characterization study to 10 existing, mostly industrial, studies and datasets; this allows us to identify points of consensus across multiple studies, investigate points of disagreement, and overall confirm the validity of our results. The results of this study can help managers to decide if they should adopt serverless technology, engineers to learn about current practices of building serverless applications, and researchers and platform providers to better understand the current landscape of serverless applications.}, author = {Eismann, Simon and Scheuner, Joel and van Eyk, Erwin and Schwinger, Maximilian and Grohmann, Johannes and Herbst, Nikolas and Abad, Cristina and Iosup, Alexandru}, journal = {Transactions on Software Engineering}, keywords = {t_journalmagazine}, number = 10, pages = {4152- 4166}, title = {The State of Serverless Applications: Collection, Characterization, and Community Consensus}, volume = 48, year = 2022 }
• Addressing Motivation in an E-Learning Scenario by applying Narration and Choice. Schaper, Philipp; Riedmann, Anna; Semineth, Miriam; Lugrin, Birgit. In Proceedings of the 35th British Human-Computer Interaction Conference (BCS HCI 22). 2022.
  • [ BibTeX ]
  @inproceedings{schaper2022addressing, author = {Schaper, Philipp and Riedmann, Anna and Semineth, Miriam and Lugrin, Birgit}, booktitle = {Proceedings of the 35th British Human-Computer Interaction Conference (BCS HCI 22)}, keywords = {mi}, title = {Addressing Motivation in an E-Learning Scenario by applying Narration and Choice}, year = 2022 }
• CortexVR: Immersive analysis and training of cognitive executive functions of soccer players using virtual reality and machine learning. Krupitzer, Christian; Naber, Jens; Stauffert, Jan-Philipp; Mayer, Jan; Spielmann, Jan; Ehmann, Paul; Boci, Noel; Bürkle, Maurice; Ho, André; Komorek, Clemens; others. In Frontiers in Psychology, 13:754732. Frontiers, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Goal: This paper presents an immersive Virtual Reality (VR) system to analyze and train Executive Functions (EFs) of soccer players. EFs are important cognitive functions for athletes. They are a relevant quality that distinguishes amateurs from professionals. Method: The system is based on immersive technology, hence, the user interacts naturally and experiences a training session in a virtual world. The proposed system has a modular design supporting the extension of various so-called game modes. Game modes combine selected game mechanics with specific simulation content to target particular training aspects. The system architecture decouples selection/parameterization and analysis of training sessions via a coaching app from an Unity3D-based VR simulation core. Monitoring of user performance and progress is recorded by a database that sends the necessary feedback to the coaching app for analysis. Results: The system is tested for VR-critical performance criteria to reveal the usefulness of a new interaction paradigm in the cognitive training and analysis of EFs. Subjective ratings for overall usability show that the design as VR application enhances the user experience compared to a traditional desktop app; whereas the new, unfamiliar interaction paradigm does not negatively impact the effort for using the application. Conclusion: The system can provide immersive training of EF in a fully virtual environment, eliminating potential distraction. It further provides an easy-to-use analyzes tool to compare user but also an automatic, adaptive training mode.

  @article{krupitzer2022cortexvr, abstract = {Goal: This paper presents an immersive Virtual Reality (VR) system to analyze and train Executive Functions (EFs) of soccer players. EFs are important cognitive functions for athletes. They are a relevant quality that distinguishes amateurs from professionals. Method: The system is based on immersive technology, hence, the user interacts naturally and experiences a training session in a virtual world. The proposed system has a modular design supporting the extension of various so-called game modes. Game modes combine selected game mechanics with specific simulation content to target particular training aspects. The system architecture decouples selection/parameterization and analysis of training sessions via a coaching app from an Unity3D-based VR simulation core. Monitoring of user performance and progress is recorded by a database that sends the necessary feedback to the coaching app for analysis. Results: The system is tested for VR-critical performance criteria to reveal the usefulness of a new interaction paradigm in the cognitive training and analysis of EFs. Subjective ratings for overall usability show that the design as VR application enhances the user experience compared to a traditional desktop app; whereas the new, unfamiliar interaction paradigm does not negatively impact the effort for using the application. Conclusion: The system can provide immersive training of EF in a fully virtual environment, eliminating potential distraction. It further provides an easy-to-use analyzes tool to compare user but also an automatic, adaptive training mode.}, author = {Krupitzer, Christian and Naber, Jens and Stauffert, Jan-Philipp and Mayer, Jan and Spielmann, Jan and Ehmann, Paul and Boci, Noel and Bürkle, Maurice and Ho, André and Komorek, Clemens and others}, journal = {Frontiers in Psychology}, keywords = {own}, publisher = {Frontiers}, title = {CortexVR: Immersive analysis and training of cognitive executive functions of soccer players using virtual reality and machine learning}, volume = {13:754732}, year = 2022 }
• Exploring Presence, Avatar Embodiment, and Body Perception with a Holographic Augmented Reality Mirror. Wolf, Erik; Fiedler, Marie Luisa; Döllinger, Nina; Wienrich, Carolin; Latoschik, Marc Erich. In 2022 IEEE Conference on Virtual Reality and 3D User Interfaces (VR), pp. 350–359. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The embodiment of avatars in virtual reality (VR) is a promising tool for enhancing the user's mental health. A great example is the treatment of body image disturbances, where eliciting a full-body illusion can help identify, visualize, and modulate persisting misperceptions. Augmented reality (AR) could complement recent advances in the field by incorporating real elements, such as the therapist or the user's real body, into therapeutic scenarios. However, research on the use of AR in this context is very sparse. Therefore, we present a holographic AR mirror system based on an optical see-through (OST) device and markerless body tracking, collect valuable qualitative feedback regarding its user experience, and compare quantitative results regarding presence, embodiment, and body weight perception to similar systems using video see-through (VST) AR and VR. For our OST AR system, a total of 27 normal-weight female participants provided predominantly positive feedback on display properties (field of view, luminosity, and transparency of virtual objects), body tracking, and the perception of the avatar’s appearance and movements. In the quantitative comparison to the VST AR and VR systems, participants reported significantly lower feelings of presence, while they estimated the body weight of the generic avatar significantly higher when using our OST AR system. For virtual body ownership and agency, we found only partially significant differences. In summary, our study shows the general applicability of OST AR in the given context offering huge potential in future therapeutic scenarios. However, the comparative evaluation between OST AR, VST AR, and VR also revealed significant differences in relevant measures. Future work is mandatory to corroborate our findings and to classify the significance in a therapeutic context.

  @inproceedings{wolf2022holographic, abstract = {The embodiment of avatars in virtual reality (VR) is a promising tool for enhancing the user's mental health. A great example is the treatment of body image disturbances, where eliciting a full-body illusion can help identify, visualize, and modulate persisting misperceptions. Augmented reality (AR) could complement recent advances in the field by incorporating real elements, such as the therapist or the user's real body, into therapeutic scenarios. However, research on the use of AR in this context is very sparse. Therefore, we present a holographic AR mirror system based on an optical see-through (OST) device and markerless body tracking, collect valuable qualitative feedback regarding its user experience, and compare quantitative results regarding presence, embodiment, and body weight perception to similar systems using video see-through (VST) AR and VR. For our OST AR system, a total of 27 normal-weight female participants provided predominantly positive feedback on display properties (field of view, luminosity, and transparency of virtual objects), body tracking, and the perception of the avatar’s appearance and movements. In the quantitative comparison to the VST AR and VR systems, participants reported significantly lower feelings of presence, while they estimated the body weight of the generic avatar significantly higher when using our OST AR system. For virtual body ownership and agency, we found only partially significant differences. In summary, our study shows the general applicability of OST AR in the given context offering huge potential in future therapeutic scenarios. However, the comparative evaluation between OST AR, VST AR, and VR also revealed significant differences in relevant measures. Future work is mandatory to corroborate our findings and to classify the significance in a therapeutic context.}, author = {Wolf, Erik and Fiedler, Marie Luisa and Döllinger, Nina and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {2022 IEEE Conference on Virtual Reality and 3D User Interfaces (VR)}, keywords = {mfiedler}, pages = {350-359}, title = {Exploring Presence, Avatar Embodiment, and Body Perception with a Holographic Augmented Reality Mirror}, year = 2022 }
• Simple Algorithms for Partial and Simultaneous Rectangular Duals with Given Contact Orientations. Chaplick, Steven; Felsner, Stefan; Kindermann, Philipp; Klawitter, Jonathan; Rutter, Ignaz; Wolff, Alexander. In Theoretical Computer Science, 919, pp. 66–74. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  A rectangular dual of a graph $G$ is a contact representation of $G$ by axis-aligned rectangles such that (i) no four rectangles share a point and (ii) the union of all rectangles is a rectangle. The \emph{partial representation extension problem} for rectangular duals asks whether a given partial rectangular dual can be extended to a rectangular dual, that is, whether there exists a rectangular dual where some vertices are represented by prescribed rectangles. The \emph{simultaneous representation problem} for rectangular duals asks whether two (or more) given graphs that share a subgraph admit rectangular duals that coincide on the shared subgraph. Combinatorially, a rectangular dual can be described by a regular edge labeling (REL), which determines the orientations of the rectangle contacts. \par We describe linear-time algorithms for the partial representation extension problem and the simultaneous representation problem for rectangular duals when each input graph is given together with a REL. Both algorithms are based on formulations as linear programs, yet they have geometric interpretations and can be seen as extensions of the classic algorithm by Kant and He that computes a rectangular dual for a given graph.

  @article{cfkkrw-sapsr-TCS22, abstract = {A rectangular dual of a graph $G$ is a contact representation of $G$ by axis-aligned rectangles such that (i) no four rectangles share a point and (ii) the union of all rectangles is a rectangle. The \emph{partial representation extension problem} for rectangular duals asks whether a given partial rectangular dual can be extended to a rectangular dual, that is, whether there exists a rectangular dual where some vertices are represented by prescribed rectangles. The \emph{simultaneous representation problem} for rectangular duals asks whether two (or more) given graphs that share a subgraph admit rectangular duals that coincide on the shared subgraph. Combinatorially, a rectangular dual can be described by a regular edge labeling (REL), which determines the orientations of the rectangle contacts. \par We describe linear-time algorithms for the partial representation extension problem and the simultaneous representation problem for rectangular duals when each input graph is given together with a REL. Both algorithms are based on formulations as linear programs, yet they have geometric interpretations and can be seen as extensions of the classic algorithm by Kant and He that computes a rectangular dual for a given graph.}, author = {Chaplick, Steven and Felsner, Stefan and Kindermann, Philipp and Klawitter, Jonathan and Rutter, Ignaz and Wolff, Alexander}, journal = {Theoretical Computer Science}, keywords = {contact_representation}, pages = {66–74}, title = {Simple Algorithms for Partial and Simultaneous Rectangular Duals with Given Contact Orientations}, volume = 919, year = 2022 }
• Towards a Cryptography Benchmark: A View on Attribute Based Encryption Schemes. Prantl, Thomas; Zeck, Timo; Iffländer, Lukas; Beierlieb, Lukas; Dmitrenko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In 2022 5th Conference on Cloud and Internet of Things (CIoT). IEEE, 2022.
  • [ BibTeX ]
  @inproceedings{PrZeIfBeDmKrKo2022-CIoT-ABEBenchmark, author = {Prantl, Thomas and Zeck, Timo and Iffländer, Lukas and Beierlieb, Lukas and Dmitrenko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, booktitle = {2022 5th Conference on Cloud and Internet of Things (CIoT)}, keywords = {descartes}, organization = {IEEE}, title = {Towards a Cryptography Benchmark: A View on Attribute Based Encryption Schemes}, year = 2022 }
• On Learning Hierarchical Embeddings from Encrypted Network Traffic. Wehner, Nikolas; Ring, Markus; Sch{{ü}}ler, Joshua; Hotho, Andreas; Hoßfeld, Tobias; Seufert, Michael. In 2022 {IEEE/IFIP} Network Operations and Management Symposium, {NOMS} 2022, Budapest, Hungary, April 25-29, 2022, pp. 1–7. {IEEE}, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{DBLP:conf/noms/WehnerRSHHS22, author = {Wehner, Nikolas and Ring, Markus and Sch{\"{u}}ler, Joshua and Hotho, Andreas and Ho{\ss}feld, Tobias and Seufert, Michael}, booktitle = {2022 {IEEE/IFIP} Network Operations and Management Symposium, {NOMS} 2022, Budapest, Hungary, April 25-29, 2022}, keywords = 2022, pages = {1–7}, publisher = {{IEEE}}, title = {On Learning Hierarchical Embeddings from Encrypted Network Traffic}, year = 2022 }
• On Background Bias in Deep Metric Learning. Kobs, Konstantin; Hotho, Andreas. In CoRR, abs/2210.01615. 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{DBLP:journals/corr/abs-2210-01615, author = {Kobs, Konstantin and Hotho, Andreas}, journal = {CoRR}, keywords = 2022, title = {On Background Bias in Deep Metric Learning}, volume = {abs/2210.01615}, year = 2022 }
• {Investigating the Predictability of QoS Metrics in Cellular Networks}. Herrnleben, Stefan; Grohmann, Johannes; Lesch, Veronika; Prantl, Thomas; Metzger, Florian; Hoßfeld, Tobias; Kounev, Samuel. In 2022 IEEE/ACM 30th International Symposium on Quality of Service (IWQoS), pp. 1–10. 2022.
  • [ BibTeX ]
  @inproceedings{HeGrLePrMeHoKo-2022-IWQoS-QoS-Prediction-Cellular-Networks, author = {Herrnleben, Stefan and Grohmann, Johannes and Lesch, Veronika and Prantl, Thomas and Metzger, Florian and Hoßfeld, Tobias and Kounev, Samuel}, booktitle = {2022 IEEE/ACM 30th International Symposium on Quality of Service (IWQoS)}, keywords = {descartes}, pages = {1-10}, title = {{Investigating the Predictability of QoS Metrics in Cellular Networks}}, year = 2022 }
• Comparison of Data Representations and Machine Learning Architectures for User Identification on Arbitrary Motion Sequences. Schell, Christian; Hotho, Andreas; Latoschik, Marc Erich. In CoRR, abs/2210.00527. 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{DBLP:journals/corr/abs-2210-00527, author = {Schell, Christian and Hotho, Andreas and Latoschik, Marc Erich}, journal = {CoRR}, keywords = 2022, title = {Comparison of Data Representations and Machine Learning Architectures for User Identification on Arbitrary Motion Sequences}, volume = {abs/2210.00527}, year = 2022 }
• CLIP knows image aesthetics. Hentschel, Simon; Kobs, Konstantin; Hotho, Andreas. In Frontiers in artificial intelligence, 5, p. 976235. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Most Image Aesthetic Assessment (IAA) methods use a pretrained ImageNet classification model as a base to fine-tune. We hypothesize that content classification is not an optimal pretraining task for IAA, since the task discourages the extraction of features that are useful for IAA, e.g., composition, lighting, or style. On the other hand, we argue that the Contrastive Language-Image Pretraining (CLIP) model is a better base for IAA models, since it has been trained using natural language supervision. Due to the rich nature of language, CLIP needs to learn a broad range of image features that correlate with sentences describing the image content, composition, environments, and even subjective feelings about the image. While it has been shown that CLIP extracts features useful for content classification tasks, its suitability for tasks that require the extraction of style-based features like IAA has not yet been shown. We test our hypothesis by conducting a three-step study, investigating the usefulness of features extracted by CLIP compared to features obtained from the last layer of a comparable ImageNet classification model. In each step, we get more computationally expensive. First, we engineer natural language prompts that let CLIP assess an image's aesthetic without adjusting any weights in the model. To overcome the challenge that CLIP's prompting only is applicable to classification tasks, we propose a simple but effective strategy to convert multiple prompts to a continuous scalar as required when predicting an image's mean aesthetic score. Second, we train a linear regression on the AVA dataset using image features obtained by CLIP's image encoder. The resulting model outperforms a linear regression trained on features from an ImageNet classification model. It also shows competitive performance with fully fine-tuned networks based on ImageNet, while only training a single layer. Finally, by fine-tuning CLIP's image encoder on the AVA dataset, we show that CLIP only needs a fraction of training epochs to converge, while also performing better than a fine-tuned ImageNet model. Overall, our experiments suggest that CLIP is better suited as a base model for IAA methods than ImageNet pretrained networks.

  @article{PMID:36504688, abstract = {Most Image Aesthetic Assessment (IAA) methods use a pretrained ImageNet classification model as a base to fine-tune. We hypothesize that content classification is not an optimal pretraining task for IAA, since the task discourages the extraction of features that are useful for IAA, e.g., composition, lighting, or style. On the other hand, we argue that the Contrastive Language-Image Pretraining (CLIP) model is a better base for IAA models, since it has been trained using natural language supervision. Due to the rich nature of language, CLIP needs to learn a broad range of image features that correlate with sentences describing the image content, composition, environments, and even subjective feelings about the image. While it has been shown that CLIP extracts features useful for content classification tasks, its suitability for tasks that require the extraction of style-based features like IAA has not yet been shown. We test our hypothesis by conducting a three-step study, investigating the usefulness of features extracted by CLIP compared to features obtained from the last layer of a comparable ImageNet classification model. In each step, we get more computationally expensive. First, we engineer natural language prompts that let CLIP assess an image's aesthetic without adjusting any weights in the model. To overcome the challenge that CLIP's prompting only is applicable to classification tasks, we propose a simple but effective strategy to convert multiple prompts to a continuous scalar as required when predicting an image's mean aesthetic score. Second, we train a linear regression on the AVA dataset using image features obtained by CLIP's image encoder. The resulting model outperforms a linear regression trained on features from an ImageNet classification model. It also shows competitive performance with fully fine-tuned networks based on ImageNet, while only training a single layer. Finally, by fine-tuning CLIP's image encoder on the AVA dataset, we show that CLIP only needs a fraction of training epochs to converge, while also performing better than a fine-tuned ImageNet model. Overall, our experiments suggest that CLIP is better suited as a base model for IAA methods than ImageNet pretrained networks.}, author = {Hentschel, Simon and Kobs, Konstantin and Hotho, Andreas}, journal = {Frontiers in artificial intelligence}, keywords = 2022, pages = 976235, title = {CLIP knows image aesthetics}, volume = 5, year = 2022 }
• Multimodale KI zur Unterstützung geschichtswissenschaftlicher Quellenkritik – Ein Forschungsaufriss. Münster, Sander; Bruschke, Jonas; Kröber, Cindy; Hoppe, Stephan; Maiwald, Ferdinand; Niebling, Florian; Pattee, Aaron; Utescher, Ronja; Zarriess, Sina. In DHd2022: Kulturen des digitalen Gedächtnisses, pp. 179–182. 2022.
  • [ BibTeX ]
  @inproceedings{mnster2022multimodale, author = {Münster, Sander and Bruschke, Jonas and Kröber, Cindy and Hoppe, Stephan and Maiwald, Ferdinand and Niebling, Florian and Pattee, Aaron and Utescher, Ronja and Zarriess, Sina}, booktitle = {DHd2022: Kulturen des digitalen Gedächtnisses}, keywords = {histstadt4d}, pages = {179–182}, title = {Multimodale KI zur Unterstützung geschichtswissenschaftlicher Quellenkritik – Ein Forschungsaufriss}, type = {Conference Proceedings}, year = 2022 }
• {Investigating the Predictability of QoS Metrics in Cellular Networks}. Herrnleben, Stefan; Grohmann, Johannes; Lesch, Veronika; Prantl, Thomas; Metzger, Florian; Hoßfeld, Tobias; Kounev, Samuel. In 2022 IEEE/ACM 30th International Symposium on Quality of Service (IWQoS), pp. 1–10. 2022.
  • [ BibTeX ]
  @inproceedings{HeGrLePrMeHoKo-2022-IWQoS-QoS-Prediction-Cellular-Networks, author = {Herrnleben, Stefan and Grohmann, Johannes and Lesch, Veronika and Prantl, Thomas and Metzger, Florian and Hoßfeld, Tobias and Kounev, Samuel}, booktitle = {2022 IEEE/ACM 30th International Symposium on Quality of Service (IWQoS)}, keywords = {descartes}, pages = {1-10}, title = {{Investigating the Predictability of QoS Metrics in Cellular Networks}}, year = 2022 }
• Social Robots in Applied Settings: A Long-Term Study on Adaptive Robotic Tutors in Higher Education. Donnermann, Melissa; Schaper, Philipp; Lugrin, Birgit. In Frontiers in Robotics and AI, 9. Frontiers Media SA, 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{Donnermann_2022, author = {Donnermann, Melissa and Schaper, Philipp and Lugrin, Birgit}, journal = {Frontiers in Robotics and AI}, keywords = {mi}, publisher = {Frontiers Media SA}, title = {Social Robots in Applied Settings: A Long-Term Study on Adaptive Robotic Tutors in Higher Education}, volume = 9, year = 2022 }
• The Relationship Between the Distribution of Training Intensity and Performance of Kayak and Canoe Sprinters: A Retrospective Observational Analysis of One Season of Competition. Matzka, Manuel; Leppich, Robert; Holmberg, Hans-Christer; Sperlich, Billy; Zinner, Christoph. In Frontiers in Sports and Active Living, 3, p. 788108. Frontiers Media SA, 2022.
  • [ BibTeX ]
  @article{matzka2022relationship, author = {Matzka, Manuel and Leppich, Robert and Holmberg, Hans-Christer and Sperlich, Billy and Zinner, Christoph}, journal = {Frontiers in Sports and Active Living}, keywords = {t_journalmagazine}, pages = 788108, publisher = {Frontiers Media SA}, title = {The Relationship Between the Distribution of Training Intensity and Performance of Kayak and Canoe Sprinters: A Retrospective Observational Analysis of One Season of Competition}, volume = 3, year = 2022 }
• Anomaly Detection in Beehives: An Algorithm Comparison. Davidson, Padraig; Steininger, Michael; Lautenschlager, Florian; Krause, Anna; Hotho, Andreas. In Sensor Networks, A. Ahrens, R. V. Prasad, C. Benavente-Peces, N. Ansari (eds.), pp. 1–20. Springer International Publishing, Cham, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Sensor-equipped beehives allow monitoring the living conditions of bees. Machine learning models can use the data of such hives to learn behavioral patterns and find anomalous events. One type of event that is of particular interest to apiarists for economical reasons is bee swarming. Other events of interest are behavioral anomalies from illness and technical anomalies, e.g. sensor failure. Beekeepers can be supported by suitable machine learning models which can detect these events.

  @inproceedings{10.1007/978-3-031-17718-7_1, abstract = {Sensor-equipped beehives allow monitoring the living conditions of bees. Machine learning models can use the data of such hives to learn behavioral patterns and find anomalous events. One type of event that is of particular interest to apiarists for economical reasons is bee swarming. Other events of interest are behavioral anomalies from illness and technical anomalies, e.g. sensor failure. Beekeepers can be supported by suitable machine learning models which can detect these events.}, address = {Cham}, author = {Davidson, Padraig and Steininger, Michael and Lautenschlager, Florian and Krause, Anna and Hotho, Andreas}, booktitle = {Sensor Networks}, editor = {Ahrens, Andreas and Prasad, RangaRao Venkatesha and Benavente-Peces, C{\'e}sar and Ansari, Nirwan}, keywords = 2022, pages = {1–20}, publisher = {Springer International Publishing}, title = {Anomaly Detection in Beehives: An Algorithm Comparison}, year = 2022 }
• Towards Responsible Medical Diagnostics Recommendation Systems. Schl{{ö}}r, Daniel; Hotho, Andreas. In CoRR, abs/2209.03760. 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{DBLP:journals/corr/abs-2209-03760, author = {Schl{\"{o}}r, Daniel and Hotho, Andreas}, journal = {CoRR}, keywords = 2022, title = {Towards Responsible Medical Diagnostics Recommendation Systems}, volume = {abs/2209.03760}, year = 2022 }
• NeuralPDE: Modelling Dynamical Systems from Data. Dulny, Andrzej; Hotho, Andreas; Krause, Anna. In {KI} 2022: Advances in Artificial Intelligence - 45th German Conference on AI, Trier, Germany, September 19-23, 2022, Proceedings, Vol. 13404 of Lecture Notes in Computer Science, R. Bergmann, L. Malburg, S. C. Rodermund, I. J. Timm (eds.), pp. 75–89. Springer, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{DBLP:conf/ki/DulnyHK22, author = {Dulny, Andrzej and Hotho, Andreas and Krause, Anna}, booktitle = {{KI} 2022: Advances in Artificial Intelligence - 45th German Conference on AI, Trier, Germany, September 19-23, 2022, Proceedings}, editor = {Bergmann, Ralph and Malburg, Lukas and Rodermund, Stephanie C. and Timm, Ingo J.}, keywords = 2022, pages = {75–89}, publisher = {Springer}, series = {Lecture Notes in Computer Science}, title = {NeuralPDE: Modelling Dynamical Systems from Data}, volume = 13404, year = 2022 }
• {Investigating the Predictability of QoS Metrics in Cellular Networks}. Herrnleben, Stefan; Grohmann, Johannes; Lesch, Veronika; Prantl, Thomas; Metzger, Florian; Hoßfeld, Tobias; Kounev, Samuel. In 2022 IEEE/ACM 30th International Symposium on Quality of Service (IWQoS), pp. 1–10. 2022.
  • [ BibTeX ]
  @inproceedings{HeGrLePrMeHoKo-2022-IWQoS-QoS-Prediction-Cellular-Networks, author = {Herrnleben, Stefan and Grohmann, Johannes and Lesch, Veronika and Prantl, Thomas and Metzger, Florian and Hoßfeld, Tobias and Kounev, Samuel}, booktitle = {2022 IEEE/ACM 30th International Symposium on Quality of Service (IWQoS)}, keywords = {descartes}, pages = {1-10}, title = {{Investigating the Predictability of QoS Metrics in Cellular Networks}}, year = 2022 }
• Joyful Adventures and Frightening Places - Designing Emotion-Inducing Virtual Environments. Steinhaeusser, Sophia C; Oberdörfer, Sebastian; von Mammen, Sebastian; Latoschik, Marc Erich; Lugrin, Birgit. In Frontiers in Virtual Reality. 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{steinhaeusser2022joyful, author = {Steinhaeusser, Sophia C and Oberdörfer, Sebastian and von Mammen, Sebastian and Latoschik, Marc Erich and Lugrin, Birgit}, journal = {Frontiers in Virtual Reality}, keywords = {mi}, title = {Joyful Adventures and Frightening Places - Designing Emotion-Inducing Virtual Environments}, year = 2022 }
• The Possibility of Inducing the Proteus Effect for Social VR Users. Oyanagi, Akimi; Narumi, Takuji; Lugrin, Jean-Luc; Aoyama, Kazuma; Ito, Kenichiro; Amemiya, Tomohiro; Hirose, Michitaka. In International Conference on Human-Computer Interaction, pp. 143–158. Springer Nature Switzerland, Cham, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The Proteus effect in Virtual Reality (VR) happens when the user's behavior or attitude are affected by their avatar's appearance. The virtual body appearance is somehow affecting the emotional, behavioral and psychological state of its user. In recent years, manipulation of an avatar has become a more common situation because of social VR platforms. It is considered that the Proteus effect can be induced even for social VR users. However, there are possibilities to disrupt the Proteus effect by becoming accustomed to embodying an avatar or attachment to their avatar.

  @inproceedings{10.1007/978-3-031-21707-4_11, abstract = {The Proteus effect in Virtual Reality (VR) happens when the user's behavior or attitude are affected by their avatar's appearance. The virtual body appearance is somehow affecting the emotional, behavioral and psychological state of its user. In recent years, manipulation of an avatar has become a more common situation because of social VR platforms. It is considered that the Proteus effect can be induced even for social VR users. However, there are possibilities to disrupt the Proteus effect by becoming accustomed to embodying an avatar or attachment to their avatar.}, address = {Cham}, author = {Oyanagi, Akimi and Narumi, Takuji and Lugrin, Jean-Luc and Aoyama, Kazuma and Ito, Kenichiro and Amemiya, Tomohiro and Hirose, Michitaka}, booktitle = {International Conference on Human-Computer Interaction}, keywords = {proteus}, pages = {143–158}, publisher = {Springer Nature Switzerland}, title = {The Possibility of Inducing the Proteus Effect for Social VR Users}, year = 2022 }
• Plausibility and Perception of Personalized Virtual Humans between Virtual and Augmented Reality. Wolf, Erik; Mal, David; Frohnapfel, Viktor; Döllinger, Nina; Wenninger, Stephan; Botsch, Mario; Latoschik, Marc Erich; Wienrich, Carolin. In 2022 IEEE International Symposium on Mixed and Augmented Reality (ISMAR), pp. 489–498. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This article investigates the effects of different XR displays on the perception and plausibility of personalized virtual humans. We compared immersive virtual reality (VR), video see-through augmented reality (VST AR), and optical see-through AR (OST AR). The personalized virtual alter egos were generated by state-of-the-art photogrammetry methods. 42 participants were repeatedly exposed to animated versions of their 3D-reconstructed virtual alter egos in each of the three XR display conditions. The reconstructed virtual alter egos were additionally modified in body weight for each repetition. We show that the display types lead to different degrees of incongruence between the renderings of the virtual humans and the presentation of the respective environmental backgrounds, leading to significant effects of perceived mismatches as part of a plausibility measurement. The device-related effects were further partly confirmed by subjective misestimations of the modified body weight and the measured spatial presence. Here, the exceedingly incongruent OST AR condition leads to the significantly highest weight misestimations as well as to the lowest perceived spatial presence. However, similar effects could not be confirmed for the affective appraisal (i.e., humanness, eeriness, or attractiveness) of the virtual humans, giving rise to the assumption that these factors might be unrelated to each other.

  @inproceedings{wolf2022plausibility, abstract = {This article investigates the effects of different XR displays on the perception and plausibility of personalized virtual humans. We compared immersive virtual reality (VR), video see-through augmented reality (VST AR), and optical see-through AR (OST AR). The personalized virtual alter egos were generated by state-of-the-art photogrammetry methods. 42 participants were repeatedly exposed to animated versions of their 3D-reconstructed virtual alter egos in each of the three XR display conditions. The reconstructed virtual alter egos were additionally modified in body weight for each repetition. We show that the display types lead to different degrees of incongruence between the renderings of the virtual humans and the presentation of the respective environmental backgrounds, leading to significant effects of perceived mismatches as part of a plausibility measurement. The device-related effects were further partly confirmed by subjective misestimations of the modified body weight and the measured spatial presence. Here, the exceedingly incongruent OST AR condition leads to the significantly highest weight misestimations as well as to the lowest perceived spatial presence. However, similar effects could not be confirmed for the affective appraisal (i.e., humanness, eeriness, or attractiveness) of the virtual humans, giving rise to the assumption that these factors might be unrelated to each other.}, author = {Wolf, Erik and Mal, David and Frohnapfel, Viktor and Döllinger, Nina and Wenninger, Stephan and Botsch, Mario and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {2022 IEEE International Symposium on Mixed and Augmented Reality (ISMAR)}, keywords = {dmal}, pages = {489-498}, title = {Plausibility and Perception of Personalized Virtual Humans between Virtual and Augmented Reality}, year = 2022 }
• Interactive, Visual Simulation of a Spatio-Temporal Model of Gas Exchange in the Human Alveolus. Schmid, Kerstin; Knote, Andreas; Mück, Alexander; Pfeiffer, Keram; von Mammen, Sebastian; Fischer, Sabine C. In Frontiers in Bioinformatics, 1. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In interdisciplinary fields such as systems biology, good communication between experimentalists and theorists is crucial for the success of a project. Theoretical modeling in physiology usually describes complex systems with many interdependencies. On one hand, these models have to be grounded on experimental data. On the other hand, experimenters must be able to understand the interdependent complexities of the theoretical model in order to interpret the model’s results in the physiological context. We promote interactive, visual simulations as an engaging way to present theoretical models in physiology and to make complex processes tangible. Based on a requirements analysis, we developed a new model for gas exchange in the human alveolus in combination with an interactive simulation software named Alvin. Alvin exceeds the current standard with its spatio-temporal resolution and a combination of visual and quantitative feedback. In Alvin, the course of the simulation can be traced in a three-dimensional rendering of an alveolus and dynamic plots. The user can interact by configuring essential model parameters. Alvin allows to run and compare multiple simulation instances simultaneously. We exemplified the use of Alvin for research by identifying unknown dependencies in published experimental data. Employing a detailed questionnaire, we showed the benefits of Alvin for education. We postulate that interactive, visual simulation of theoretical models, as we have implemented with Alvin on respiratory processes in the alveolus, can be of great help for communication between specialists and thereby advancing research.

  @article{10.3389/fbinf.2021.774300, abstract = {In interdisciplinary fields such as systems biology, good communication between experimentalists and theorists is crucial for the success of a project. Theoretical modeling in physiology usually describes complex systems with many interdependencies. On one hand, these models have to be grounded on experimental data. On the other hand, experimenters must be able to understand the interdependent complexities of the theoretical model in order to interpret the model’s results in the physiological context. We promote interactive, visual simulations as an engaging way to present theoretical models in physiology and to make complex processes tangible. Based on a requirements analysis, we developed a new model for gas exchange in the human alveolus in combination with an interactive simulation software named Alvin. Alvin exceeds the current standard with its spatio-temporal resolution and a combination of visual and quantitative feedback. In Alvin, the course of the simulation can be traced in a three-dimensional rendering of an alveolus and dynamic plots. The user can interact by configuring essential model parameters. Alvin allows to run and compare multiple simulation instances simultaneously. We exemplified the use of Alvin for research by identifying unknown dependencies in published experimental data. Employing a detailed questionnaire, we showed the benefits of Alvin for education. We postulate that interactive, visual simulation of theoretical models, as we have implemented with Alvin on respiratory processes in the alveolus, can be of great help for communication between specialists and thereby advancing research.}, author = {Schmid, Kerstin and Knote, Andreas and Mück, Alexander and Pfeiffer, Keram and von Mammen, Sebastian and Fischer, Sabine C.}, journal = {Frontiers in Bioinformatics}, keywords = {myown}, title = {Interactive, Visual Simulation of a Spatio-Temporal Model of Gas Exchange in the Human Alveolus}, volume = 1, year = 2022 }
• SenPoi at SemEval-2022 Task 10: Point me to your Opinion, SenPoi. Pfister, Jan; Wankerl, Sebastian; Hotho, Andreas. In Proceedings of the 16th International Workshop on Semantic Evaluation, SemEval@NAACL 2022, Seattle, Washington, United States, July 14-15, 2022, G. Emerson, N. Schluter, G. Stanovsky, R. Kumar, A. Palmer, N. Schneider, S. Singh, S. Ratan (eds.), pp. 1313–1323. Association for Computational Linguistics, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{DBLP:conf/semeval/PfisterWH22, author = {Pfister, Jan and Wankerl, Sebastian and Hotho, Andreas}, booktitle = {Proceedings of the 16th International Workshop on Semantic Evaluation, SemEval@NAACL 2022, Seattle, Washington, United States, July 14-15, 2022}, editor = {Emerson, Guy and Schluter, Natalie and Stanovsky, Gabriel and Kumar, Ritesh and Palmer, Alexis and Schneider, Nathan and Singh, Siddharth and Ratan, Shyam}, keywords = 2022, pages = {1313–1323}, publisher = {Association for Computational Linguistics}, title = {SenPoi at SemEval-2022 Task 10: Point me to your Opinion, SenPoi}, year = 2022 }
• Controlling the STAGE: A High-Level Control System for Virtual Audiences In Virtual Reality. Glémarec, Yann; Lugrin, Jean-Luc; Bosser, Anne-Gwenn; Buche, Cedric; Latoschik, Marc Erich. In Frontiers in Virtual Reality – Virtual Reality and Human Behaviour. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This article presents a novel method for controlling a virtual audience system (VAS) in Virtual Reality (VR) application, called STAGE, which has been originally designed for supervised public speaking training in university seminars dedicated to the preparation and delivery of scientific talks. We are interested in creating pedagogical \emph{narratives}: narratives encompass affective phenomena and rather than organizing events changing the course of a training scenario, pedagogical plans using our system focus on organizing the affects it arouses for the trainees. Efficiently controlling a virtual audience towards a specific training objective while evaluating the speaker's performance presents a challenge for a seminar instructor: the high level of cognitive and physical demands required to be able to control the virtual audience, whilst evaluating speaker's performance, adjusting and allowing it to quickly react to the user’s behaviors and interactions. It is indeed a critical limitation of a number of existing systems that they rely on a Wizard of Oz approach, where the tutor drives the audience in reaction to the user’s performance. We address this problem by integrating with a VAS a high-level control component for tutors, which allows using predefined audience behavior rules, defining custom ones, as well as intervening during run-time for finer control of the unfolding of the pedagogical plan. At its core, this component offers a tool to program, select, modify and monitor interactive training narratives using a high-level representation. The STAGE offers the following features: i) a high-level API to program pedagogical narratives focusing on a specific public speaking situation and training objectives, ii) an interactive visualization interface iii) computation and visualization of user metrics, iv) a semi-autonomous virtual audience composed of virtual spectators with automatic reactions to the speaker and surrounding spectators while following the pedagogical plan V) and the possibility for the instructor to embody a virtual spectator to ask questions or guide the speaker from within the Virtual Environment. We present here the design, implementation of the tutoring system and its integration in STAGE, and discuss its reception by end-users.

  @article{glemarec2022controlling, abstract = {This article presents a novel method for controlling a virtual audience system (VAS) in Virtual Reality (VR) application, called STAGE, which has been originally designed for supervised public speaking training in university seminars dedicated to the preparation and delivery of scientific talks. We are interested in creating pedagogical \emph{narratives}: narratives encompass affective phenomena and rather than organizing events changing the course of a training scenario, pedagogical plans using our system focus on organizing the affects it arouses for the trainees. Efficiently controlling a virtual audience towards a specific training objective while evaluating the speaker's performance presents a challenge for a seminar instructor: the high level of cognitive and physical demands required to be able to control the virtual audience, whilst evaluating speaker's performance, adjusting and allowing it to quickly react to the user’s behaviors and interactions. It is indeed a critical limitation of a number of existing systems that they rely on a Wizard of Oz approach, where the tutor drives the audience in reaction to the user’s performance. We address this problem by integrating with a VAS a high-level control component for tutors, which allows using predefined audience behavior rules, defining custom ones, as well as intervening during run-time for finer control of the unfolding of the pedagogical plan. At its core, this component offers a tool to program, select, modify and monitor interactive training narratives using a high-level representation. The STAGE offers the following features: i) a high-level API to program pedagogical narratives focusing on a specific public speaking situation and training objectives, ii) an interactive visualization interface iii) computation and visualization of user metrics, iv) a semi-autonomous virtual audience composed of virtual spectators with automatic reactions to the speaker and surrounding spectators while following the pedagogical plan V) and the possibility for the instructor to embody a virtual spectator to ask questions or guide the speaker from within the Virtual Environment. We present here the design, implementation of the tutoring system and its integration in STAGE, and discuss its reception by end-users.}, author = {Glémarec, Yann and Lugrin, Jean-Luc and Bosser, Anne-Gwenn and Buche, Cedric and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality – Virtual Reality and Human Behaviour}, keywords = {myown}, title = {Controlling the STAGE: A High-Level Control System for Virtual Audiences In Virtual Reality}, year = 2022 }
• Designing Social Robots’ Speech in the Hotel Context-A Series of Online Studies. Steinhaeusser, Sophia C.; Lein, Martina; Donnermann, Melissa; Lugrin, Birgit. In 2022 31st IEEE International Conference on Robot and Human Interactive Communication (RO-MAN), pp. 163–170. IEEE, 2022.
  • [ BibTeX ]
  @inproceedings{steinhaeusser2022designing, author = {Steinhaeusser, Sophia C. and Lein, Martina and Donnermann, Melissa and Lugrin, Birgit}, booktitle = {2022 31st IEEE International Conference on Robot and Human Interactive Communication (RO-MAN)}, keywords = {lein}, organization = {IEEE}, pages = {163-170}, title = {Designing Social Robots' Speech in the Hotel Context-A Series of Online Studies}, year = 2022 }
• A Fully-Immersive Virtual Reality Setup to Study Gait Modulation. Palmisano, Chiara; Kullmann, Peter; Hanafi, Ibrahem; Verrecchia, Marta; Latoschik, Marc Erich; Canessa, Andrea; Fischbach, Martin; Isaias, Ioannis Ugo. In Frontiers in Human Neuroscience, 16. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Objective: Gait adaptation to environmental challenges is fundamental for independent and safe community ambulation. The possibility of precisely studying gait modulation using standardized protocols of gait analysis closely resembling everyday life scenarios is still an unmet need.Methods: We have developed a fully-immersive virtual reality (VR) environment where subjects have to adjust their walking pattern to avoid collision with a virtual agent (VA) crossing their gait trajectory. We collected kinematic data of 12 healthy young subjects walking in real world (RW) and in the VR environment, both with (VR/A+) and without (VR/A-) the VA perturbation. The VR environment closely resembled the RW scenario of the gait laboratory. To ensure standardization of the obstacle presentation the starting time speed and trajectory of the VA were defined using the kinematics of the participant as detected online during each walking trial.Results: We did not observe kinematic differences between walking in RW and VR/A-, suggesting that our VR environment per se might not induce significant changes in the locomotor pattern. When facing the VA all subjects consistently reduced stride length and velocity while increasing stride duration. Trunk inclination and mediolateral trajectory deviation also facilitated avoidance of the obstacle.Conclusions: This proof-of-concept study shows that our VR/A+ paradigm effectively induced a timely gait modulation in a standardized immersive and realistic scenario. This protocol could be a powerful research tool to study gait modulation and its derangements in relation to aging and clinical conditions.

  @article{10.3389/fnhum.2022.783452, abstract = {Objective: Gait adaptation to environmental challenges is fundamental for independent and safe community ambulation. The possibility of precisely studying gait modulation using standardized protocols of gait analysis closely resembling everyday life scenarios is still an unmet need.Methods: We have developed a fully-immersive virtual reality (VR) environment where subjects have to adjust their walking pattern to avoid collision with a virtual agent (VA) crossing their gait trajectory. We collected kinematic data of 12 healthy young subjects walking in real world (RW) and in the VR environment, both with (VR/A+) and without (VR/A-) the VA perturbation. The VR environment closely resembled the RW scenario of the gait laboratory. To ensure standardization of the obstacle presentation the starting time speed and trajectory of the VA were defined using the kinematics of the participant as detected online during each walking trial.Results: We did not observe kinematic differences between walking in RW and VR/A-, suggesting that our VR environment per se might not induce significant changes in the locomotor pattern. When facing the VA all subjects consistently reduced stride length and velocity while increasing stride duration. Trunk inclination and mediolateral trajectory deviation also facilitated avoidance of the obstacle.Conclusions: This proof-of-concept study shows that our VR/A+ paradigm effectively induced a timely gait modulation in a standardized immersive and realistic scenario. This protocol could be a powerful research tool to study gait modulation and its derangements in relation to aging and clinical conditions.}, author = {Palmisano, Chiara and Kullmann, Peter and Hanafi, Ibrahem and Verrecchia, Marta and Latoschik, Marc Erich and Canessa, Andrea and Fischbach, Martin and Isaias, Ioannis Ugo}, journal = {Frontiers in Human Neuroscience}, keywords = {hci-uwb}, title = {A Fully-Immersive Virtual Reality Setup to Study Gait Modulation}, volume = 16, year = 2022 }
• Don’t Touch This! - Investigating the Potential of Visualizing Touched Surfaces on the Consideration of Behavior Change. Ganal, E.; Heimbrock, M.; Schaper, P.; Lugrin, B. In Persuasive Technology 2022, N. Baghaei, J. Vassileva, R. Ali, K. Oyibo (eds.). Springer International Publishing, 2022.
  • [ BibTeX ]
  @inproceedings{ganal2022touch, author = {Ganal, E. and Heimbrock, M. and Schaper, P. and Lugrin, B.}, booktitle = {Persuasive Technology 2022}, editor = {Baghaei, N. and Vassileva, J. and Ali, R. and Oyibo, K.}, keywords = {reflectedreality}, publisher = {Springer International Publishing}, title = {Don’t Touch This! - Investigating the Potential of Visualizing Touched Surfaces on the Consideration of Behavior Change}, year = 2022 }
• Minimum Rectilinear Polygons for Given Angle Sequences. Evans, William S.; Fleszar, Krzysztof; Kindermann, Philipp; Saeedi, Noushin; Shin, Chan-Su; Wolff, Alexander. In Computational Geometry: Theory and Applications, 100(101820), pp. 1–39. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  A rectilinear polygon is a simple polygon whose edges are axis-aligned. Walking counterclockwise on the boundary of such a polygon yields a sequence of left turns and right turns. The number of left turns always equals the number of right turns plus four. It is known that any such sequence can be realized by a rectilinear polygon. \par In this paper, we consider the problem of finding realizations that minimize the perimeter or the area of the polygon or the area of the bounding box of the polygon. We show that all three problems are NP-hard in general. This answers an open question of Patrignani [CGTA 2001], who showed that it is NP-hard to minimize the area of the bounding box of an orthogonal drawing of a given planar graph. We also show that realizing a polyline within a bounding box of minimum area (or within a fixed given rectangle) is NP-hard. Then we consider the special cases of x-monotone and xy-monotone rectilinear polygons. For these, we can optimize the three objectives efficiently.

  @article{efkssw-mrpga-CGTA22, abstract = {A rectilinear polygon is a simple polygon whose edges are axis-aligned. Walking counterclockwise on the boundary of such a polygon yields a sequence of left turns and right turns. The number of left turns always equals the number of right turns plus four. It is known that any such sequence can be realized by a rectilinear polygon. \par In this paper, we consider the problem of finding realizations that minimize the perimeter or the area of the polygon or the area of the bounding box of the polygon. We show that all three problems are NP-hard in general. This answers an open question of Patrignani [CGTA 2001], who showed that it is NP-hard to minimize the area of the bounding box of an orthogonal drawing of a given planar graph. We also show that realizing a polyline within a bounding box of minimum area (or within a fixed given rectangle) is NP-hard. Then we consider the special cases of x-monotone and xy-monotone rectilinear polygons. For these, we can optimize the three objectives efficiently.}, author = {Evans, William S. and Fleszar, Krzysztof and Kindermann, Philipp and Saeedi, Noushin and Shin, Chan-Su and Wolff, Alexander}, journal = {Computational Geometry: Theory and Applications}, keywords = {myown}, number = 101820, pages = {1–39}, title = {Minimum Rectilinear Polygons for Given Angle Sequences}, volume = 100, year = 2022 }
• The State of Serverless Applications: Collection, Characterization, and Community Consensus. Eismann, Simon; Scheuner, Joel; van Eyk, Erwin; Schwinger, Maximilian; Grohmann, Johannes; Herbst, Nikolas; Abad, Cristina; Iosup, Alexandru. In Transactions on Software Engineering, 48(10), pp. 4152–4166. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Over the last five years, all major cloud platform providers have increased their serverless offerings. Many early adopters report significant benefits for serverless-based over traditional applications, and many companies are considering moving to serverless themselves. However, currently there exist only few, scattered, and sometimes even conflicting reports on when serverless applications are well suited and what the best practices for their implementation are. We address this problem in the present study about the state of serverless applications. We collect descriptions of 89 serverless applications from open-source projects, academic literature, industrial literature, and domain-specific feedback. We analyze 16 characteristics that describe why and when successful adopters are using serverless applications, and how they are building them. We further compare the results of our characterization study to 10 existing, mostly industrial, studies and datasets; this allows us to identify points of consensus across multiple studies, investigate points of disagreement, and overall confirm the validity of our results. The results of this study can help managers to decide if they should adopt serverless technology, engineers to learn about current practices of building serverless applications, and researchers and platform providers to better understand the current landscape of serverless applications.

  @article{eismann2021state, abstract = {Over the last five years, all major cloud platform providers have increased their serverless offerings. Many early adopters report significant benefits for serverless-based over traditional applications, and many companies are considering moving to serverless themselves. However, currently there exist only few, scattered, and sometimes even conflicting reports on when serverless applications are well suited and what the best practices for their implementation are. We address this problem in the present study about the state of serverless applications. We collect descriptions of 89 serverless applications from open-source projects, academic literature, industrial literature, and domain-specific feedback. We analyze 16 characteristics that describe why and when successful adopters are using serverless applications, and how they are building them. We further compare the results of our characterization study to 10 existing, mostly industrial, studies and datasets; this allows us to identify points of consensus across multiple studies, investigate points of disagreement, and overall confirm the validity of our results. The results of this study can help managers to decide if they should adopt serverless technology, engineers to learn about current practices of building serverless applications, and researchers and platform providers to better understand the current landscape of serverless applications.}, author = {Eismann, Simon and Scheuner, Joel and van Eyk, Erwin and Schwinger, Maximilian and Grohmann, Johannes and Herbst, Nikolas and Abad, Cristina and Iosup, Alexandru}, journal = {Transactions on Software Engineering}, keywords = {t_journalmagazine}, number = 10, pages = {4152- 4166}, title = {The State of Serverless Applications: Collection, Characterization, and Community Consensus}, volume = 48, year = 2022 }
• Why Is It Not Solved Yet? Challenges for Production-Ready Autoscaling. Straesser, Martin; Grohmann, Johannes; von Kistowski, J{ó}akim; Eismann, Simon; Bauer, Andr{é}; Kounev, Samuel. In Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering, of ICPE ’22, pp. 105–115. Association for Computing Machinery, New York, NY, USA, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Autoscaling is a task of major importance in the cloud computing domain as it directly affects both operating costs and customer experience. Although there has been active research in this area for over ten years now, there is still a significant gap between the proposed methods in the literature and the deployed autoscalers in practice. Hence, many research autoscalers do not find their way into production deployments. This paper describes six core challenges that arise in production systems that are still not solved by most research autoscalers. We illustrate these problems through experiments in a realistic cloud environment with a real-world multi-service business application and show that commonly used autoscalers have various shortcomings. In addition, we analyze the behavior of overloaded services and show that these can be problematic for existing autoscalers. Generally, we analyze that these challenges are only insufficiently addressed in the literature and conclude that future scaling approaches should focus on the needs of production systems.

  @inproceedings{10.1145/3489525.3511680, abstract = {Autoscaling is a task of major importance in the cloud computing domain as it directly affects both operating costs and customer experience. Although there has been active research in this area for over ten years now, there is still a significant gap between the proposed methods in the literature and the deployed autoscalers in practice. Hence, many research autoscalers do not find their way into production deployments. This paper describes six core challenges that arise in production systems that are still not solved by most research autoscalers. We illustrate these problems through experiments in a realistic cloud environment with a real-world multi-service business application and show that commonly used autoscalers have various shortcomings. In addition, we analyze the behavior of overloaded services and show that these can be problematic for existing autoscalers. Generally, we analyze that these challenges are only insufficiently addressed in the literature and conclude that future scaling approaches should focus on the needs of production systems.}, address = {New York, NY, USA}, author = {Straesser, Martin and Grohmann, Johannes and von Kistowski, J\'{o}akim and Eismann, Simon and Bauer, Andr\'{e} and Kounev, Samuel}, booktitle = {Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering}, keywords = {microservices}, pages = {105–115}, publisher = {Association for Computing Machinery}, series = {ICPE '22}, title = {Why Is It Not Solved Yet? Challenges for Production-Ready Autoscaling}, year = 2022 }
• Conflict Handling in Product Configuration using Answer Set Programming. Herud, Konstantin; Baumeister, Joachim; Sabuncu, Orkunt; Schaub, Torsten. In ICLP Workshop Answer Set Programming and Other Computing Paradigms. 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{hbs:22, author = {Herud, Konstantin and Baumeister, Joachim and Sabuncu, Orkunt and Schaub, Torsten}, booktitle = {ICLP Workshop Answer Set Programming and Other Computing Paradigms}, keywords = {explanation}, title = {Conflict Handling in Product Configuration using Answer Set Programming}, year = 2022 }
• An Experience Report on the Suitability of a Distributed Group Encryption Scheme for an IoT Use Case. Prantl, Thomas; Engel, Simon; Bauer, Andre; Ben Yahya, Ala Eddine; Herrnleben, Stefan; Iffländer, Lukas; Dmitrienko, Alexandra; Kounev, Samuel. In 2022 IEEE 95th Vehicular Technology Conference (VTC2022). IEEE, 2022.
  • [ BibTeX ]
  @inproceedings{PrEnBaAlHeIfDmKo2022-IoT/CPS-DistributedGroupEncryption, author = {Prantl, Thomas and Engel, Simon and Bauer, Andre and Ben Yahya, Ala Eddine and Herrnleben, Stefan and Iffländer, Lukas and Dmitrienko, Alexandra and Kounev, Samuel}, booktitle = {2022 IEEE 95th Vehicular Technology Conference (VTC2022)}, keywords = {t_workshop}, organization = {IEEE}, title = {An Experience Report on the Suitability of a Distributed Group Encryption Scheme for an IoT Use Case}, year = 2022 }
• The Impact of Different System Call Representations on Intrusion Detection. Wunderlich, Sarah; Ring, Markus; Landes, Dieter; Hotho, Andreas. In Log. J. {IGPL}, 30(2), pp. 239–251. 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{DBLP:journals/igpl/WunderlichRLH22, author = {Wunderlich, Sarah and Ring, Markus and Landes, Dieter and Hotho, Andreas}, journal = {Log. J. {IGPL}}, keywords = 2022, number = 2, pages = {239–251}, title = {The Impact of Different System Call Representations on Intrusion Detection}, volume = 30, year = 2022 }
• Why Is It Not Solved Yet? Challenges for Production-Ready Autoscaling. Straesser, Martin; Grohmann, Johannes; von Kistowski, J{ó}akim; Eismann, Simon; Bauer, Andr{é}; Kounev, Samuel. In Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering, of ICPE ’22, pp. 105–115. Association for Computing Machinery, New York, NY, USA, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Autoscaling is a task of major importance in the cloud computing domain as it directly affects both operating costs and customer experience. Although there has been active research in this area for over ten years now, there is still a significant gap between the proposed methods in the literature and the deployed autoscalers in practice. Hence, many research autoscalers do not find their way into production deployments. This paper describes six core challenges that arise in production systems that are still not solved by most research autoscalers. We illustrate these problems through experiments in a realistic cloud environment with a real-world multi-service business application and show that commonly used autoscalers have various shortcomings. In addition, we analyze the behavior of overloaded services and show that these can be problematic for existing autoscalers. Generally, we analyze that these challenges are only insufficiently addressed in the literature and conclude that future scaling approaches should focus on the needs of production systems.

  @inproceedings{10.1145/3489525.3511680, abstract = {Autoscaling is a task of major importance in the cloud computing domain as it directly affects both operating costs and customer experience. Although there has been active research in this area for over ten years now, there is still a significant gap between the proposed methods in the literature and the deployed autoscalers in practice. Hence, many research autoscalers do not find their way into production deployments. This paper describes six core challenges that arise in production systems that are still not solved by most research autoscalers. We illustrate these problems through experiments in a realistic cloud environment with a real-world multi-service business application and show that commonly used autoscalers have various shortcomings. In addition, we analyze the behavior of overloaded services and show that these can be problematic for existing autoscalers. Generally, we analyze that these challenges are only insufficiently addressed in the literature and conclude that future scaling approaches should focus on the needs of production systems.}, address = {New York, NY, USA}, author = {Straesser, Martin and Grohmann, Johannes and von Kistowski, J\'{o}akim and Eismann, Simon and Bauer, Andr\'{e} and Kounev, Samuel}, booktitle = {Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering}, keywords = {microservices}, pages = {105–115}, publisher = {Association for Computing Machinery}, series = {ICPE '22}, title = {Why Is It Not Solved Yet? Challenges for Production-Ready Autoscaling}, year = 2022 }
• Retrospektive Analyse ausgew{ä}hlter Belastungs-und Beanspruchungsparameter einer professionellen Fußball-mannschaft vor und w{ä}hrend coronabedingter Kontakt-beschr{ä}nkungen in der Spielsaison 2019/20. Kunz, Philipp; D{ü}king, Peter; Leppich, Robert; Lachmann, Jonas; Sperlich, Billy. In Leipziger Sportwissenschaftliche Beitr{ä}ge Jahrgang 63 (2022 Heft 1, p. 75. Lehmanns Media, 2022.
  • [ BibTeX ]
  @article{kunz2022retrospektive, author = {Kunz, Philipp and D{\"u}king, Peter and Leppich, Robert and Lachmann, Jonas and Sperlich, Billy}, journal = {Leipziger Sportwissenschaftliche Beitr{\"a}ge Jahrgang 63 (2022 Heft 1}, keywords = {t_interdisciplinary}, pages = 75, publisher = {Lehmanns Media}, title = {Retrospektive Analyse ausgew{\"a}hlter Belastungs-und Beanspruchungsparameter einer professionellen Fu{\ss}ball-mannschaft vor und w{\"a}hrend coronabedingter Kontakt-beschr{\"a}nkungen in der Spielsaison 2019/20}, year = 2022 }
• Usability and User Experience of Virtual Objects Supporting Learning and Communicating in Virtual Reality. Hein, Rebecca; Latoschik, Marc Erich; Wienrich, Carolin. In Mensch und Computer 2022 - Tagungsband, B. Pfleging, K. Gerling, S. Mayer (eds.), pp. 510–514. ACM, New York, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This study aims to evaluate the usability and user experience of the InteractionSuitecase. This is a collection of virtual objects that have cultural connotations (associated with German or Anglo-American culture). They are intended to promote communication about cultural differences and similarities in English lessons at German schools. They are thus part of a didactic concept for using social VR for trans- and intercultural learning. Future teacher used the virtual objects during a practical seminar and rated them as useful. Further they associates a positive user experience. Since the virtual objects should encourage communication, the sense of connectedness instead of isolation is a very important results. The results proved the readiness of the InteractionSuitcase for further pedagogical applications.

  @inproceedings{mci/Hein2022, abstract = {This study aims to evaluate the usability and user experience of the InteractionSuitecase. This is a collection of virtual objects that have cultural connotations (associated with German or Anglo-American culture). They are intended to promote communication about cultural differences and similarities in English lessons at German schools. They are thus part of a didactic concept for using social VR for trans- and intercultural learning. Future teacher used the virtual objects during a practical seminar and rated them as useful. Further they associates a positive user experience. Since the virtual objects should encourage communication, the sense of connectedness instead of isolation is a very important results. The results proved the readiness of the InteractionSuitcase for further pedagogical applications.}, address = {New York}, author = {Hein, Rebecca and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {Mensch und Computer 2022 - Tagungsband}, editor = {Pfleging, Bastian and Gerling, Kathrin and Mayer, Sven}, keywords = {coteach}, pages = {510-514}, publisher = {ACM}, title = {Usability and User Experience of Virtual Objects Supporting Learning and Communicating in Virtual Reality}, year = 2022 }
• An Experience Report on the Suitability of a Distributed Group Encryption Scheme for an IoT Use Case. Prantl, Thomas; Engel, Simon; Bauer, Andre; Ben Yahya, Ala Eddine; Herrnleben, Stefan; Iffländer, Lukas; Dmitrienko, Alexandra; Kounev, Samuel. In 2022 IEEE 95th Vehicular Technology Conference (VTC2022). IEEE, 2022.
  • [ BibTeX ]
  @inproceedings{PrEnBaAlHeIfDmKo2022-IoT/CPS-DistributedGroupEncryption, author = {Prantl, Thomas and Engel, Simon and Bauer, Andre and Ben Yahya, Ala Eddine and Herrnleben, Stefan and Iffländer, Lukas and Dmitrienko, Alexandra and Kounev, Samuel}, booktitle = {2022 IEEE 95th Vehicular Technology Conference (VTC2022)}, keywords = {t_workshop}, organization = {IEEE}, title = {An Experience Report on the Suitability of a Distributed Group Encryption Scheme for an IoT Use Case}, year = 2022 }
• Towards a Cryptography Benchmark: A View on Attribute Based Encryption Schemes. Prantl, Thomas; Zeck, Timo; Iffländer, Lukas; Beierlieb, Lukas; Dmitrenko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In 2022 5th Conference on Cloud and Internet of Things (CIoT). IEEE, 2022.
  • [ BibTeX ]
  @inproceedings{PrZeIfBeDmKrKo2022-CIoT-ABEBenchmark, author = {Prantl, Thomas and Zeck, Timo and Iffländer, Lukas and Beierlieb, Lukas and Dmitrenko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, booktitle = {2022 5th Conference on Cloud and Internet of Things (CIoT)}, keywords = {descartes}, organization = {IEEE}, title = {Towards a Cryptography Benchmark: A View on Attribute Based Encryption Schemes}, year = 2022 }
• A data-driven Sensor Model for LIDAR Range Measurements used for Mobile Robot Navigation. Spiess, Florian; Strobel, Norbert; Kaupp, Tobias; Kounev, Samuel. In Proceedings of the IEEE IRC 2022 Conference. 2022.
  • [ BibTeX ]
  @conference{spiess2022datadriven, author = {Spiess, Florian and Strobel, Norbert and Kaupp, Tobias and Kounev, Samuel}, booktitle = {Proceedings of the IEEE IRC 2022 Conference}, keywords = {t_interdisciplinary}, title = {A data-driven Sensor Model for LIDAR Range Measurements used for Mobile Robot Navigation}, year = 2022 }
• Identification of clinically distinct and prognostically important phenogroups in patients with acute heart failure by a machine learning approach. Albert, J Judith; Leppich, R; Borst, V; Sahiti, F; Scholz, N; Cejka, V; Morbach, C; Ertl, G; Angermann, C; Frantz, S; others. In EUROPEAN JOURNAL OF HEART FAILURE, Vol. 24, pp. 179–179. WILEY 111 RIVER ST, HOBOKEN 07030-5774, NJ USA, 2022.
  • [ BibTeX ]
  @inproceedings{albert2022identification, author = {Albert, J Judith and Leppich, R and Borst, V and Sahiti, F and Scholz, N and Cejka, V and Morbach, C and Ertl, G and Angermann, C and Frantz, S and others}, booktitle = {EUROPEAN JOURNAL OF HEART FAILURE}, keywords = {t_interdisciplinary}, organization = {WILEY 111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, pages = {179–179}, title = {Identification of clinically distinct and prognostically important phenogroups in patients with acute heart failure by a machine learning approach}, volume = 24, year = 2022 }
• The Computational Complexity of the {ChordLink} Model. Kindermann, Philipp; Sauer, Jan; Wolff, Alexander. In Proc. 38th Europ. Workshop Comput. Geom. (EuroCG’22), E. {Di Giacomo}, F. Montecchiani (eds.), pp. 10:1–7. 2022.
  • [ BibTeX ]
  @inproceedings{ksw-cccm-EuroCG22, author = {Kindermann, Philipp and Sauer, Jan and Wolff, Alexander}, booktitle = {Proc. 38th Europ. Workshop Comput. Geom. (EuroCG'22)}, editor = {{Di Giacomo}, Emilio and Montecchiani, Fabrizio}, keywords = {myown}, pages = {10:1–7}, title = {The Computational Complexity of the {ChordLink} Model}, year = 2022 }
• Digital body, identity and privacy in social virtual reality: A systematic review. Lin, Jinghuai; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 3. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Social Virtual Reality (social VR or SVR) provides digital spaces for diverse human activities, social interactions, and embodied face-to-face encounters. While our digital bodies in SVR can in general be of almost any conceivable appearance, individualized or even personalized avatars bearing users’ likeness recently became an interesting research topic. Such digital bodies show a great potential to enhance the authenticity of social VR citizens and increase the trustworthiness of interpersonal interaction. However, using such digital bodies might expose users to privacy and identity issues such as identity theft: For instance, how do we know whether the avatars we encounter in the virtual world are who they claim to be? Safeguarding users’ identities and privacy, and preventing harm from identity infringement, are crucial to the future of social VR. This article provides a systematic review on the protection of users’ identity and privacy in social VR, with a specific focus on digital bodies. Based on 814 sources, we identified and analyzed 49 papers that either: 1) discuss or raise concerns about the addressed issues, 2) provide technologies and potential solutions for protecting digital bodies, or 3) examine the relationship between the digital bodies and users of social VR citizens. We notice a severe lack of research and attention on the addressed topic and identify several research gaps that need to be filled. While some legal and ethical concerns about the potential identity issues of the digital bodies have been raised, and despite some progress in specific areas such as user authentication has been made, little research has proposed practical solutions. Finally, we suggest potential future research directions for digital body protection and include relevant research that might provide insights. We hope this work could provide a good overview of the existing discussion, potential solutions, and future directions for researchers with similar concerns. We also wish to draw attention to identity and privacy issues in social VR and call for interdisciplinary collaboration.

  @article{lin2022digital, abstract = {Social Virtual Reality (social VR or SVR) provides digital spaces for diverse human activities, social interactions, and embodied face-to-face encounters. While our digital bodies in SVR can in general be of almost any conceivable appearance, individualized or even personalized avatars bearing users’ likeness recently became an interesting research topic. Such digital bodies show a great potential to enhance the authenticity of social VR citizens and increase the trustworthiness of interpersonal interaction. However, using such digital bodies might expose users to privacy and identity issues such as identity theft: For instance, how do we know whether the avatars we encounter in the virtual world are who they claim to be? Safeguarding users’ identities and privacy, and preventing harm from identity infringement, are crucial to the future of social VR. This article provides a systematic review on the protection of users’ identity and privacy in social VR, with a specific focus on digital bodies. Based on 814 sources, we identified and analyzed 49 papers that either: 1) discuss or raise concerns about the addressed issues, 2) provide technologies and potential solutions for protecting digital bodies, or 3) examine the relationship between the digital bodies and users of social VR citizens. We notice a severe lack of research and attention on the addressed topic and identify several research gaps that need to be filled. While some legal and ethical concerns about the potential identity issues of the digital bodies have been raised, and despite some progress in specific areas such as user authentication has been made, little research has proposed practical solutions. Finally, we suggest potential future research directions for digital body protection and include relevant research that might provide insights. We hope this work could provide a good overview of the existing discussion, potential solutions, and future directions for researchers with similar concerns. We also wish to draw attention to identity and privacy issues in social VR and call for interdisciplinary collaboration.}, author = {Lin, Jinghuai and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {emlab}, title = {Digital body, identity and privacy in social virtual reality: A systematic review}, volume = 3, year = 2022 }
• A Theory Based Adaptive Pedagogical Agent in a Reading App for Primary Students - A User Study. Riedmann, Anna; Schaper, Philipp; Jakob, Benedikt; Lugrin, Birgit. In Intelligent Tutoring Systems. ITS 2022. Lecture Notes in Computer Science, Vol. 13284, S. Crossley, E. Popescu (eds.). Springer, 2022.
  • [ BibTeX ]
  @inproceedings{riedmann2022theory, author = {Riedmann, Anna and Schaper, Philipp and Jakob, Benedikt and Lugrin, Birgit}, booktitle = {Intelligent Tutoring Systems. ITS 2022. Lecture Notes in Computer Science}, editor = {Crossley, S. and Popescu, E.}, keywords = {mi}, publisher = {Springer}, title = {A Theory Based Adaptive Pedagogical Agent in a Reading App for Primary Students - A User Study}, volume = 13284, year = 2022 }
• Integration of a social robot and gamification in adult learning and effects on motivation, engagement and performance. Riedmann, Anna; Schaper, Philipp; Lugrin, Birgit. In AI & Society. Springer, 2022.
  • [ BibTeX ]
  @article{Riedmann_2022, author = {Riedmann, Anna and Schaper, Philipp and Lugrin, Birgit}, journal = {AI & Society}, keywords = {mi}, publisher = {Springer}, title = {Integration of a social robot and gamification in adult learning and effects on motivation, engagement and performance}, year = 2022 }
• Bounding and Computing Obstacle Numbers of Graphs. Balko, Martin; Chaplick, Steven; Ganian, Robert; Gupta, Siddharth; Hoffmann, Michael; Valtr, Pavel; Wolff, Alexander. In Proc. 30th Europ. Symp. Algorithms (ESA’22), Vol. 244 of LIPIcs, S. Chechik, G. Navarro, E. Rotenberg, G. Herman (eds.), pp. 11:1–13. Schloss Dagstuhl – Leibniz-Zentrum für Informatik, 2022.
  • [ BibTeX ]
  @inproceedings{bcghvw-bcong-ESA22, author = {Balko, Martin and Chaplick, Steven and Ganian, Robert and Gupta, Siddharth and Hoffmann, Michael and Valtr, Pavel and Wolff, Alexander}, booktitle = {Proc. 30th Europ. Symp. Algorithms (ESA'22)}, editor = {Chechik, Shiri and Navarro, Gonzalo and Rotenberg, Eva and Herman, Grzegorz}, keywords = {myown}, pages = {11:1–13}, publisher = {Schloss Dagstuhl – Leibniz-Zentrum für Informatik}, series = {LIPIcs}, title = {Bounding and Computing Obstacle Numbers of Graphs}, volume = 244, year = 2022 }
• Semi-unsupervised Learning for Time Series Classification. Davidson, Padraig; Steininger, Michael; Huhn, Andr{{é}}; Krause, Anna; Hotho, Andreas. In CoRR, abs/2207.03119. 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{DBLP:journals/corr/abs-2207-03119, author = {Davidson, Padraig and Steininger, Michael and Huhn, Andr{\'{e}} and Krause, Anna and Hotho, Andreas}, journal = {CoRR}, keywords = 2022, title = {Semi-unsupervised Learning for Time Series Classification}, volume = {abs/2207.03119}, year = 2022 }
• Virtual Reality for Mind and Body: Does the Sense of Embodiment Towards a Virtual Body Affect Physical Body Awareness?. Döllinger, Nina; Wolf, Erik; Mal, David; Erdmannsdörfer, Nico; Botsch, Mario; Latoschik, Marc Erich; Wienrich, Carolin. In CHI 22 Conference on Human Factors in Computing Systems Extended Abstracts, pp. 1–8. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Mind-body therapies aim to improve health by combining physical and mental exercises. Recent developments tend to incorporate virtual reality (VR) into their design and execution, but there is a lack of research concerning the inclusion of virtual bodies and their effect on body awareness in these designs. In this study, 24 participants performed in-VR body awareness movement tasks in front of a virtual mirror while embodying a photorealistic, personalized avatar. Subsequently, they performed a heartbeat counting task and rated their perceived body awareness and sense of embodiment towards the avatar. We found a significant relationship between sense of embodiment and self-reported body awareness but not between sense of embodiment and heartbeat counting. Future work can build on these findings and further explore the relationship between avatar embodiment and body awareness.

  @inproceedings{dollinger2022virtual, abstract = {Mind-body therapies aim to improve health by combining physical and mental exercises. Recent developments tend to incorporate virtual reality (VR) into their design and execution, but there is a lack of research concerning the inclusion of virtual bodies and their effect on body awareness in these designs. In this study, 24 participants performed in-VR body awareness movement tasks in front of a virtual mirror while embodying a photorealistic, personalized avatar. Subsequently, they performed a heartbeat counting task and rated their perceived body awareness and sense of embodiment towards the avatar. We found a significant relationship between sense of embodiment and self-reported body awareness but not between sense of embodiment and heartbeat counting. Future work can build on these findings and further explore the relationship between avatar embodiment and body awareness.}, author = {Döllinger, Nina and Wolf, Erik and Mal, David and Erdmannsdörfer, Nico and Botsch, Mario and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {CHI 22 Conference on Human Factors in Computing Systems Extended Abstracts}, keywords = {dmal}, pages = {1-8}, title = {Virtual Reality for Mind and Body: Does the Sense of Embodiment Towards a Virtual Body Affect Physical Body Awareness?}, year = 2022 }
• Challenge Discussion on Socially Interactive Agents: Considerations on Social Interaction, Computational Architectures, Evaluation, and Ethics. Lugrin, Birgit; Pelachaud, Catherine; André, Elisabeth; Aylett, Ruth; Bickmore, Timothy; Breazeal, Cynthia; Broekens, Joost; Dautenhahn, Kerstin; Gratch, Jonathan; Kopp, Stefan; Nadel, Jacqueline; Paiva, Ana; Wykowska, Agnieszka. In The Handbook on Socially Interactive Agents: 20 years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics Volume 2: Interactivity, Platforms, Application, pp. 561–626. ACM, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inbook{10.1145/3563659.3563677, author = {Lugrin, Birgit and Pelachaud, Catherine and André, Elisabeth and Aylett, Ruth and Bickmore, Timothy and Breazeal, Cynthia and Broekens, Joost and Dautenhahn, Kerstin and Gratch, Jonathan and Kopp, Stefan and Nadel, Jacqueline and Paiva, Ana and Wykowska, Agnieszka}, journal = {The Handbook on Socially Interactive Agents: 20 years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics Volume 2: Interactivity, Platforms, Application}, keywords = {mi}, pages = {561–626}, publisher = {ACM}, title = {Challenge Discussion on Socially Interactive Agents: Considerations on Social Interaction, Computational Architectures, Evaluation, and Ethics}, year = 2022 }
• Comparison of Data Encodings and Machine Learning Architectures for User Identification on Arbitrary Motion Sequences. Rack, Christian; Hotho, Andreas; Latoschik, Marc Erich. In Proceedings of the IEEE International conference on artificial intelligence & Virtual Reality (IEEE AIVR). IEEE, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{schell2022comparison, author = {Rack, Christian and Hotho, Andreas and Latoschik, Marc Erich}, booktitle = {Proceedings of the IEEE International conference on artificial intelligence & Virtual Reality (IEEE AIVR)}, keywords = {schell}, publisher = {IEEE}, title = {Comparison of Data Encodings and Machine Learning Architectures for User Identification on Arbitrary Motion Sequences}, year = 2022 }
• The Effects of Avatar and Environment Design on Embodiment, Presence, Activation, and Task Load in a Virtual Reality Exercise Application. Bartl, Andrea; Merz, Christian; Roth, Daniel; Latoschik, Marc Erich. In IEEE International Symposium on Mixed and Augmented Reality (ISMAR). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  ABSTRACT The development of embodied Virtual Reality (VR) systems involves multiple central design choices. These design choices affect the user perception and therefore require thorough consideration. This article reports on two user studies investigating the influence of common design choices on relevant intermediate factors (sense of embodiment, presence, motivation, activation, and task load) in a VR application for physical exercises. The first study manipulated the avatar fidelity (abstract, partial body vs. anthropomorphic, full-body) and the environment (with vs. without mirror). The second study manipulated the avatar type (healthy vs. injured) and the environment type (beach vs. hospital) and, hence, the avatar-environment congruence. The full-body avatar significantly increased the sense of embodiment and decreased mental demand. Interestingly, the mirror did not influence the dependent variables. The injured avatar significantly increased the temporal demand. The beach environment significantly reduced the tense activation. On the beach, participants felt more present in the incongruent condition embodying the injured avatar.

  @inproceedings{bartl2022effects, abstract = {ABSTRACT The development of embodied Virtual Reality (VR) systems involves multiple central design choices. These design choices affect the user perception and therefore require thorough consideration. This article reports on two user studies investigating the influence of common design choices on relevant intermediate factors (sense of embodiment, presence, motivation, activation, and task load) in a VR application for physical exercises. The first study manipulated the avatar fidelity (abstract, partial body vs. anthropomorphic, full-body) and the environment (with vs. without mirror). The second study manipulated the avatar type (healthy vs. injured) and the environment type (beach vs. hospital) and, hence, the avatar-environment congruence. The full-body avatar significantly increased the sense of embodiment and decreased mental demand. Interestingly, the mirror did not influence the dependent variables. The injured avatar significantly increased the temporal demand. The beach environment significantly reduced the tense activation. On the beach, participants felt more present in the incongruent condition embodying the injured avatar.}, author = {Bartl, Andrea and Merz, Christian and Roth, Daniel and Latoschik, Marc Erich}, booktitle = {IEEE International Symposium on Mixed and Augmented Reality (ISMAR)}, keywords = {xrhub}, title = {The Effects of Avatar and Environment Design on Embodiment, Presence, Activation, and Task Load in a Virtual Reality Exercise Application}, year = 2022 }
• Opportunities and Challenges of Virtual Reality in Healthcare – A Domain Experts Inquiry. Halbig, Andreas; Babu, Sooraj K.; Gatter, Shirin; Latoschik, Marc Erich; Brukamp, Kirsten; von Mammen, Sebastian. In Frontiers in Virtual Reality, 3. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In recent years, the applications and accessibility of Virtual Reality (VR) for the healthcare sector have continued to grow. However, so far, most VR applications are only relevant in research settings. Information about what healthcare professionals would need to independently integrate VR applications into their daily working routines is missing. The actual needs and concerns of the people who work in the healthcare sector are often disregarded in the development of VR applications, even though they are the ones who are supposed to use them in practice. By means of this study, we systematically involve health professionals in the development process of VR applications. In particular, we conducted an online survey with 102 healthcare professionals based on a video prototype which demonstrates a software platform that allows them to create and utilise VR experiences on their own. For this study, we adapted and extended the Technology Acceptance Model (TAM). The survey focused on the perceived usefulness and the ease of use of such a platform, as well as the attitude and ethical concerns the users might have. The results show a generally positive attitude toward such a software platform. The users can imagine various use cases in different health domains. However, the perceived usefulness is tied to the actual ease of use of the platform and sufficient support for learning and working with the platform. In the discussion, we explain how these results can be generalized to facilitate the integration of VR in healthcare practice.

  @article{halbig:2022q, abstract = {In recent years, the applications and accessibility of Virtual Reality (VR) for the healthcare sector have continued to grow. However, so far, most VR applications are only relevant in research settings. Information about what healthcare professionals would need to independently integrate VR applications into their daily working routines is missing. The actual needs and concerns of the people who work in the healthcare sector are often disregarded in the development of VR applications, even though they are the ones who are supposed to use them in practice. By means of this study, we systematically involve health professionals in the development process of VR applications. In particular, we conducted an online survey with 102 healthcare professionals based on a video prototype which demonstrates a software platform that allows them to create and utilise VR experiences on their own. For this study, we adapted and extended the Technology Acceptance Model (TAM). The survey focused on the perceived usefulness and the ease of use of such a platform, as well as the attitude and ethical concerns the users might have. The results show a generally positive attitude toward such a software platform. The users can imagine various use cases in different health domains. However, the perceived usefulness is tied to the actual ease of use of the platform and sufficient support for learning and working with the platform. In the discussion, we explain how these results can be generalized to facilitate the integration of VR in healthcare practice.}, author = {Halbig, Andreas and Babu, Sooraj K. and Gatter, Shirin and Latoschik, Marc Erich and Brukamp, Kirsten and von Mammen, Sebastian}, journal = {Frontiers in Virtual Reality}, keywords = {via-vr}, title = {Opportunities and Challenges of Virtual Reality in Healthcare – A Domain Experts Inquiry}, volume = 3, year = 2022 }
• Self-Touch: An Immersive Interaction-Technique to Enhance Body Awareness. Keppler, Sebastian; Döllinger, Nina; Wienrich, Carolin; Latoschik, Marc Erich; Israel, Johann Habakuk. In i-com, 21(3), pp. 329–337. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Physical well-being depends essentially on how the own body is perceived. A missing correspondence between the perception of one’s own body and reality can be distressing and eventually lead to mental illness. The touch of the own body is a multi-sensory experience to strengthen the feeling of the own body. We have developed an interaction technique that allows the self-touch of the own body in an immersive environment to support therapy procedures. Through additional visual feedback, we want to strengthen the feeling for the own body to achieve a sustainable effect in the own body perception. We conducted an expert evaluation to analyse the potential impact of our application and to localize and fix possible usability problems. The experts noted the ease of understanding and suitability of the interaction technique for increasing body awareness. However, the technical challenges such as stable and accurate body tracking were also mentioned. In addition, new ideas were given that would further support body awareness.

  @article{KepplerDöllingerWienrichLatoschikIsrael+2022+329+337, abstract = {Physical well-being depends essentially on how the own body is perceived. A missing correspondence between the perception of one’s own body and reality can be distressing and eventually lead to mental illness. The touch of the own body is a multi-sensory experience to strengthen the feeling of the own body. We have developed an interaction technique that allows the self-touch of the own body in an immersive environment to support therapy procedures. Through additional visual feedback, we want to strengthen the feeling for the own body to achieve a sustainable effect in the own body perception. We conducted an expert evaluation to analyse the potential impact of our application and to localize and fix possible usability problems. The experts noted the ease of understanding and suitability of the interaction technique for increasing body awareness. However, the technical challenges such as stable and accurate body tracking were also mentioned. In addition, new ideas were given that would further support body awareness.}, author = {Keppler, Sebastian and Döllinger, Nina and Wienrich, Carolin and Latoschik, Marc Erich and Israel, Johann Habakuk}, journal = {i-com}, keywords = {vitras}, number = 3, pages = {329–337}, title = {Self-Touch: An Immersive Interaction-Technique to Enhance Body Awareness}, volume = 21, year = 2022 }
• CortexVR: Immersive analysis and training of cognitive executive functions of soccer players using virtual reality and machine learning. Krupitzer, Christian; Naber, Jens; Stauffert, Jan-Philipp; Mayer, Jan; Spielmann, Jan; Ehmann, Paul; Boci, Noel; B{ü}rkle, Maurice; Ho, Andr{é}; Komorek, Clemens; Heinickel, Felix; Kounev, Samuel; Becker, Christian; Latoschik, Marc Erich. In Frontiers in Psychology, p. 5139. Frontiers, 2022.
  • [ BibTeX ]
  @article{krupitzer2022cortexvr, author = {Krupitzer, Christian and Naber, Jens and Stauffert, Jan-Philipp and Mayer, Jan and Spielmann, Jan and Ehmann, Paul and Boci, Noel and B{\"u}rkle, Maurice and Ho, Andr{\'e} and Komorek, Clemens and Heinickel, Felix and Kounev, Samuel and Becker, Christian and Latoschik, Marc Erich}, journal = {Frontiers in Psychology}, keywords = {t_journalmagazine}, pages = 5139, publisher = {Frontiers}, title = {CortexVR: Immersive analysis and training of cognitive executive functions of soccer players using virtual reality and machine learning}, year = 2022 }
• Coloring Mixed and Directional Interval Graphs. Gutowski, Grzegorz; Mittelst{{ä}}dt, Florian; Rutter, Ignaz; Spoerhase, Joachim; Wolff, Alexander; Zink, Johannes. In Proc. 30th International Symposium Graph Drawing and Network Visualization (GD’22), Vol. 13764, pp. 418–431. 2022.
  • [ BibTeX ]
  @inproceedings{gutowski-etal22:mixed-interval-graphs, author = {Gutowski, Grzegorz and Mittelst{\"{a}}dt, Florian and Rutter, Ignaz and Spoerhase, Joachim and Wolff, Alexander and Zink, Johannes}, booktitle = {Proc. 30th International Symposium Graph Drawing and Network Visualization (GD'22)}, keywords = {graph}, pages = {418–431}, title = {Coloring Mixed and Directional Interval Graphs}, volume = 13764, year = 2022 }
• One Graph to Rule them All: Using {NLP} and Graph Neural Networks to analyse Tolkien’s Legendarium. Perri, Vincenzo; Qarkaxhija, Lisi; Zehe, Albin; Hotho, Andreas; Scholtes, Ingo. In Proceedings of the Computational Humanities Research Conference 2022, {CHR} 2022, Antwerp, Belgium, December 12-14, 2022, Vol. 3290 of {CEUR} Workshop Proceedings, F. Karsdorp, K. L. Nielbo (eds.), pp. 291–317. CEUR-WS.org, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{DBLP:conf/chr/PerriQZHS22, author = {Perri, Vincenzo and Qarkaxhija, Lisi and Zehe, Albin and Hotho, Andreas and Scholtes, Ingo}, booktitle = {Proceedings of the Computational Humanities Research Conference 2022, {CHR} 2022, Antwerp, Belgium, December 12-14, 2022}, editor = {Karsdorp, Folgert and Nielbo, Kristoffer L.}, keywords = 2022, pages = {291–317}, publisher = {CEUR-WS.org}, series = {{CEUR} Workshop Proceedings}, title = {One Graph to Rule them All: Using {NLP} and Graph Neural Networks to analyse Tolkien's Legendarium}, volume = 3290, year = 2022 }
• Open ERP System Data For Occupational Fraud Detection. Tritscher, Julian; Gwinner, Fabian; Schlör, Daniel; Krause, Anna; Hotho, Andreas. In arxiv. 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{tritscher2022erpData, author = {Tritscher, Julian and Gwinner, Fabian and Schlör, Daniel and Krause, Anna and Hotho, Andreas}, journal = {arxiv}, keywords = 2022, title = {Open ERP System Data For Occupational Fraud Detection}, year = 2022 }
• A literature review on optimization techniques for adaptation planning in adaptive systems: State of the art and research directions. Henrichs, Elia; Lesch, Veronika; Straesser, Martin; Kounev, Samuel; Krupitzer, Christian. In Information and Software Technology, 149, p. 106940. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Context: Recent developments in modern IT systems including internet of things, edge/fog computing, or cyber–physical systems support intelligent and seamless interaction between users and systems. This requires a reaction to changes in their environment or the system. Adaptive systems provide mechanisms for these reactions. Objective: To implement this functionality, several approaches for the planning of adaptations exist that rely on rules, utility functions, or advanced techniques, such as machine learning. As the adaptation space with possible options is often extensively huge, optimization techniques might support efficient determination of the adaptation space and identify the system’s optimal configuration. With this paper, we provide a systematic review of adaptation planning as the optimization target. Method: In this paper, we review which optimization techniques are applied for adaptation planning in adaptive systems using a systematic literature review approach. Results: We reviewed 115 paper in detail out of an initial search set of 9,588 papers. Our analysis reveals that learning techniques and genetic algorithms are by far dominant; in total, heuristics (anytime learning) are more frequently applied as exact algorithms. We observed that around 57% of the approaches target multi-objectiveness and around 30% integrate distributed optimization. As last dimension, we focused on situation-awareness, which is only supported by two approaches. Conclusion: In this paper, we provide an overview of the current state of the art of approaches that rely on optimization techniques for planning adaptations in adaptive systems and further derive open research challenges, in particular regarding the integration of distributed optimization and situation-awareness.

  @article{HENRICHS2022106940, abstract = {Context: Recent developments in modern IT systems including internet of things, edge/fog computing, or cyber–physical systems support intelligent and seamless interaction between users and systems. This requires a reaction to changes in their environment or the system. Adaptive systems provide mechanisms for these reactions. Objective: To implement this functionality, several approaches for the planning of adaptations exist that rely on rules, utility functions, or advanced techniques, such as machine learning. As the adaptation space with possible options is often extensively huge, optimization techniques might support efficient determination of the adaptation space and identify the system’s optimal configuration. With this paper, we provide a systematic review of adaptation planning as the optimization target. Method: In this paper, we review which optimization techniques are applied for adaptation planning in adaptive systems using a systematic literature review approach. Results: We reviewed 115 paper in detail out of an initial search set of 9,588 papers. Our analysis reveals that learning techniques and genetic algorithms are by far dominant; in total, heuristics (anytime learning) are more frequently applied as exact algorithms. We observed that around 57% of the approaches target multi-objectiveness and around 30% integrate distributed optimization. As last dimension, we focused on situation-awareness, which is only supported by two approaches. Conclusion: In this paper, we provide an overview of the current state of the art of approaches that rely on optimization techniques for planning adaptations in adaptive systems and further derive open research challenges, in particular regarding the integration of distributed optimization and situation-awareness.}, author = {Henrichs, Elia and Lesch, Veronika and Straesser, Martin and Kounev, Samuel and Krupitzer, Christian}, journal = {Information and Software Technology}, keywords = {t_journalmagazine}, pages = 106940, title = {A literature review on optimization techniques for adaptation planning in adaptive systems: State of the art and research directions}, volume = 149, year = 2022 }
• Reducing the Cognitive Load of Playing a Digital Tabletop Game with a Multimodal Interface. Zimmerer, Chris; Krop, Philipp; Fischbach, Martin; Latoschik, Marc Erich. In CHI Conference on Human Factors in Computing Systems, of CHI ’22. Association for Computing Machinery, New Orleans, LA, USA, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Multimodal Interfaces (MMIs) combining speech and spatial input have the potential to elicit minimal cognitive load. Low cognitive load increases effectiveness as well as user satisfaction and is regarded as an important aspect of intuitive use. While this potential has been extensively theorized in the research community, experiments that provide supporting observations based on functional interfaces are still scarce. In particular, there is a lack of studies comparing the commonly used Unimodal Interfaces (UMIs) with theoretically superior synergistic MMI alternatives. Yet, these studies are an essential prerequisite for generalizing results, developing practice-oriented guidelines, and ultimately exploiting the potential of MMIs in a broader range of applications. This work contributes a novel observation towards the resolution of this shortcoming in the context of the following combination of applied interaction techniques, tasks, application domain, and technology: We present a comprehensive evaluation of a synergistic speech & touch MMI and a touch-only menu-based UMI (interaction techniques) for selection and system control tasks in a digital tabletop game (application domain) on an interactive surface (technology). Cognitive load, user experience, and intuitive use are evaluated, with the former being assessed by means of the dual-task paradigm. Our experiment shows that the implemented MMI causes significantly less cognitive load and is perceived significantly more usable and intuitive than the UMI. Based on our results, we derive recommendations for the interface design of digital tabletop games on interactive surfaces. Further, we argue that our results and design recommendations are suitable to be generalized to other application domains on interactive surfaces for selection and system control tasks.

  @inproceedings{10.1145/3491102.3502062, abstract = {Multimodal Interfaces (MMIs) combining speech and spatial input have the potential to elicit minimal cognitive load. Low cognitive load increases effectiveness as well as user satisfaction and is regarded as an important aspect of intuitive use. While this potential has been extensively theorized in the research community, experiments that provide supporting observations based on functional interfaces are still scarce. In particular, there is a lack of studies comparing the commonly used Unimodal Interfaces (UMIs) with theoretically superior synergistic MMI alternatives. Yet, these studies are an essential prerequisite for generalizing results, developing practice-oriented guidelines, and ultimately exploiting the potential of MMIs in a broader range of applications. This work contributes a novel observation towards the resolution of this shortcoming in the context of the following combination of applied interaction techniques, tasks, application domain, and technology: We present a comprehensive evaluation of a synergistic speech & touch MMI and a touch-only menu-based UMI (interaction techniques) for selection and system control tasks in a digital tabletop game (application domain) on an interactive surface (technology). Cognitive load, user experience, and intuitive use are evaluated, with the former being assessed by means of the dual-task paradigm. Our experiment shows that the implemented MMI causes significantly less cognitive load and is perceived significantly more usable and intuitive than the UMI. Based on our results, we derive recommendations for the interface design of digital tabletop games on interactive surfaces. Further, we argue that our results and design recommendations are suitable to be generalized to other application domains on interactive surfaces for selection and system control tasks.}, address = {New York, NY, USA}, author = {Zimmerer, Chris and Krop, Philipp and Fischbach, Martin and Latoschik, Marc Erich}, booktitle = {CHI Conference on Human Factors in Computing Systems}, keywords = {mmi}, publisher = {Association for Computing Machinery}, series = {CHI '22}, title = {Reducing the Cognitive Load of Playing a Digital Tabletop Game with a Multimodal Interface}, year = 2022 }
• Ransomware Detection in Databases through Dynamic Analysis of Query Sequences. Sendner, Christoph; Iffländer, Lukas; Schindler, Sebastian; Jobst, Michael; Dmitrienko, Alexandra; Kounev, Samuel. In 2022 IEEE Conference on Communications and Network Security (CNS). 2022.
  • [ BibTeX ]
  @conference{sendner2022ransomware, author = {Sendner, Christoph and Iffländer, Lukas and Schindler, Sebastian and Jobst, Michael and Dmitrienko, Alexandra and Kounev, Samuel}, booktitle = {2022 IEEE Conference on Communications and Network Security (CNS)}, keywords = {sss-group}, title = {Ransomware Detection in Databases through Dynamic Analysis of Query Sequences}, year = 2022 }
• Leveraging Kubernetes Source Code for Performance Simulation. Straesser, Martin; Haas, Patrick. 2022.
  • [ BibTeX ]
  • [ URL ]
  @presentation{straesser2022leveraging, author = {Straesser, Martin and Haas, Patrick}, keywords = {container_orchestration}, title = {Leveraging Kubernetes Source Code for Performance Simulation}, year = 2022 }
• A case study on the stability of performance tests for serverless applications. Eismann, Simon; Costa, Diego; Liao, Lizhi; Bezemer, Cor-Paul; Shang, Weiyi; van Hoorn, André; Kounev, Samuel. In Journal of Systems and Software (JSS), 189. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Context: While in serverless computing, application resource management and operational concerns are generally delegated to the cloud provider, ensuring that serverless applications meet their performance requirements is still a responsibility of the developers. Performance testing is a commonly used performance assessment practice; however, it traditionally requires visibility of the resource environment. Objective: In this study, we investigate whether performance tests of serverless applications are stable, that is, if their results are reproducible, and what implications the serverless paradigm has for performance tests. Method: We conduct a case study where we collect two datasets of performance test results: (a) repetitions of performance tests for varying memory size and load intensities and (b) three repetitions of the same performance test every day for ten months. Results: We find that performance tests of serverless applications are comparatively stable if conducted on the same day. However, we also observe short-term performance variations and frequent long-term performance changes. Conclusion: Performance tests for serverless applications can be stable; however, the serverless model impacts the planning, execution, and analysis of performance tests.

  @article{eismann2022study, abstract = {Context: While in serverless computing, application resource management and operational concerns are generally delegated to the cloud provider, ensuring that serverless applications meet their performance requirements is still a responsibility of the developers. Performance testing is a commonly used performance assessment practice; however, it traditionally requires visibility of the resource environment. Objective: In this study, we investigate whether performance tests of serverless applications are stable, that is, if their results are reproducible, and what implications the serverless paradigm has for performance tests. Method: We conduct a case study where we collect two datasets of performance test results: (a) repetitions of performance tests for varying memory size and load intensities and (b) three repetitions of the same performance test every day for ten months. Results: We find that performance tests of serverless applications are comparatively stable if conducted on the same day. However, we also observe short-term performance variations and frequent long-term performance changes. Conclusion: Performance tests for serverless applications can be stable; however, the serverless model impacts the planning, execution, and analysis of performance tests.}, author = {Eismann, Simon and Costa, Diego and Liao, Lizhi and Bezemer, Cor-Paul and Shang, Weiyi and van Hoorn, André and Kounev, Samuel}, journal = {Journal of Systems and Software (JSS)}, keywords = {t_journalmagazine}, title = {A case study on the stability of performance tests for serverless applications}, volume = 189, year = 2022 }
• Layered drawing of undirected graphs with generalized port constraints. Zink, Johannes; Walter, Julian; Baumeister, Joachim; Wolff, Alexander. In Computational Geometry: Theory and Applications, 105-106, p. 101886. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  The aim of this research is a practical method to draw cable plans of complex machines. Such plans consist of electronic components and cables connecting specific ports of the components. Since the machines are configured for each client individually, cable plans need to be drawn automatically. The drawings must be well readable so that technicians can use them to debug the machines. In order to model plug sockets, we introduce port groups; within a group, ports can change their position (which we use to improve the aesthetics of the layout), but together the ports of a group must form a contiguous block. We approach the problem of drawing such cable plans by extending the well-known Sugiyama framework such that it incorporates ports and port groups. Since the framework assumes directed graphs, we propose several ways to orient the edges of the given undirected graph. We compare these methods experimentally, both on real-world data and synthetic data that carefully simulates real-world data. We measure the aesthetics of the resulting drawings by counting bends and crossings. Using these metrics, we experimentally compare our approach to Kieler JVLC 2014, a library for drawing graphs in the presence of port constraints. Our method produced 10--30 \% fewer crossings, while it performed equally well or slightly worse than Kieler with respect to the number of bends and the time used to compute a drawing.

  @article{ZINK2022101886, abstract = {The aim of this research is a practical method to draw cable plans of complex machines. Such plans consist of electronic components and cables connecting specific ports of the components. Since the machines are configured for each client individually, cable plans need to be drawn automatically. The drawings must be well readable so that technicians can use them to debug the machines. In order to model plug sockets, we introduce port groups; within a group, ports can change their position (which we use to improve the aesthetics of the layout), but together the ports of a group must form a contiguous block. We approach the problem of drawing such cable plans by extending the well-known Sugiyama framework such that it incorporates ports and port groups. Since the framework assumes directed graphs, we propose several ways to orient the edges of the given undirected graph. We compare these methods experimentally, both on real-world data and synthetic data that carefully simulates real-world data. We measure the aesthetics of the resulting drawings by counting bends and crossings. Using these metrics, we experimentally compare our approach to Kieler JVLC 2014, a library for drawing graphs in the presence of port constraints. Our method produced 10–30 \% fewer crossings, while it performed equally well or slightly worse than Kieler with respect to the number of bends and the time used to compute a drawing.}, author = {Zink, Johannes and Walter, Julian and Baumeister, Joachim and Wolff, Alexander}, journal = {Computational Geometry: Theory and Applications}, keywords = {myown}, pages = 101886, title = {Layered drawing of undirected graphs with generalized port constraints}, volume = {105-106}, year = 2022 }
• Hypergraph Representation via Axis-Aligned Point-Subspace Cover. Firman, Oksana; Spoerhase, Joachim. In Proc. 16th International Conference and Workshops on Algorithms and Computation (WALCOM’22), Vol. 13174, pp. 328–339. 2022.
  • [ BibTeX ]
  @inproceedings{firman-spoerhase22:point-subspace-cover, author = {Firman, Oksana and Spoerhase, Joachim}, booktitle = {Proc. 16th International Conference and Workshops on Algorithms and Computation (WALCOM'22)}, keywords = {representation}, pages = {328–339}, title = {Hypergraph Representation via Axis-Aligned Point-Subspace Cover}, volume = 13174, year = 2022 }
• Addressing Waste Separation With a Persuasive Augmented Reality App. Schaper, Philipp; Riedmann, Anna; Oberdörfer, Sebastian; Lugrin, Birgit. In Proceedings of the 24th International Conference on Mobile Human-Computer Interaction (MobileHCI ’22). Association for Computing Machinery, New York, NY, USA, 2022.
  • [ BibTeX ]
  @inproceedings{schaper2022addressing, address = {New York, NY, USA}, author = {Schaper, Philipp and Riedmann, Anna and Oberdörfer, Sebastian and Lugrin, Birgit}, booktitle = {Proceedings of the 24th International Conference on Mobile Human-Computer Interaction (MobileHCI '22)}, keywords = {mi}, publisher = {Association for Computing Machinery}, title = {Addressing Waste Separation With a Persuasive Augmented Reality App}, year = 2022 }
• Stay Safe! Safety Precautions for Walking on a Conventional Treadmill in VR. Birnstiel, Sandra; Oberdörfer, Sebastian; Latoschik, Marc Erich. In Proceedings of the 29th IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VR ’22), pp. 732–733. IEEE, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Conventional treadmills are used in virtual reality (VR) applications, such as for rehabilitation training or gait studies. However, using the devices in VR poses risks of injury. Therefore, this study investigates safety precautions when using a conventional treadmill for a walking task. We designed a safety belt and displayed parts of the treadmill in VR. The safety belt was much appreciated by the participants and did not affect the walking behavior. However, the participants requested more visual cues in the user’s field of view.

  @inproceedings{birnstiel2022safety, abstract = {Conventional treadmills are used in virtual reality (VR) applications, such as for rehabilitation training or gait studies. However, using the devices in VR poses risks of injury. Therefore, this study investigates safety precautions when using a conventional treadmill for a walking task. We designed a safety belt and displayed parts of the treadmill in VR. The safety belt was much appreciated by the participants and did not affect the walking behavior. However, the participants requested more visual cues in the user’s field of view.}, author = {Birnstiel, Sandra and Oberdörfer, Sebastian and Latoschik, Marc Erich}, booktitle = {Proceedings of the 29th IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VR '22)}, keywords = {myown}, organization = {IEEE}, pages = {732-733}, title = {Stay Safe! Safety Precautions for Walking on a Conventional Treadmill in VR}, year = 2022 }
• bioDIVERsity. Ein Computerspiel gegen das Imageproblem von Wasserpflanzen. und David Schantz und Julian Gröh und Andreas Knote und Prof. Dr. Sebastian von Mammen und Prof. Dr. Juliano Cabral, Anne Lewerentz. In Mitteilungen der Fränkischen Geographischen Gesellschaft, (67), pp. 29–36. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Wasserpflanzen haben ein Imageproblem: Sie stören vermeintlich beim Baden in Seen, was zu panikartigenReaktionen führen kann. Begriffe wie „Schlingpflanzen“ und „Veralgung“ werden falsch verwendet odersind negativ konnotiert. Zudem sieht man Wasserpflanzen kaum, da sie überwiegend unter der Wasseroberflächewachsen. Ihre vielen wertvollen Funktionen im Ökosystem See bleiben daher oft unerkannt undsind durch die schlechte Erreichbarkeit und Erfahrbarkeit nur schwer zu vermitteln.Virtuelle Medien eröffnen eine neue Möglichkeit, schwierig erreichbare Orte erfahrbar zu machen. Fürdie Vermittlung von Umweltthemen – gerade an eine jüngere Zielgruppe – wird ein großes Potential indigitalen Spielen und Simulationen (Computerspiele, Apps, Virtual Reality-Spiele), speziell sogenanntenSerious Games, gesehen.Ein Prototyp für das Serious Game bioDIVERsity wurde im Rahmen eines interdisziplinären Kurses derArbeitsgruppe Games Engineering am Institut für Informatik in Zusammenarbeit mit dem Center for Computationaland Theoretical Biology an der Universität Würzburg entwickelt. Ziel des Spiels ist es, KindernKenntnisse über das Ökosystem See und die Auswirkungen der Wasserqualität und der Klimabedingungenauf Wasserpflanzen zu vermitteln. Darüber hinaus soll ein Bewusstsein für dieses Ökosystem und die Auswirkungenmenschlicher Eingriffe entstehen.

  @article{Lewerentz:2022aa, abstract = {Wasserpflanzen haben ein Imageproblem: Sie stören vermeintlich beim Baden in Seen, was zu panikartigenReaktionen führen kann. Begriffe wie „Schlingpflanzen“ und „Veralgung“ werden falsch verwendet odersind negativ konnotiert. Zudem sieht man Wasserpflanzen kaum, da sie überwiegend unter der Wasseroberflächewachsen. Ihre vielen wertvollen Funktionen im Ökosystem See bleiben daher oft unerkannt undsind durch die schlechte Erreichbarkeit und Erfahrbarkeit nur schwer zu vermitteln.Virtuelle Medien eröffnen eine neue Möglichkeit, schwierig erreichbare Orte erfahrbar zu machen. Fürdie Vermittlung von Umweltthemen – gerade an eine jüngere Zielgruppe – wird ein großes Potential indigitalen Spielen und Simulationen (Computerspiele, Apps, Virtual Reality-Spiele), speziell sogenanntenSerious Games, gesehen.Ein Prototyp für das Serious Game bioDIVERsity wurde im Rahmen eines interdisziplinären Kurses derArbeitsgruppe Games Engineering am Institut für Informatik in Zusammenarbeit mit dem Center for Computationaland Theoretical Biology an der Universität Würzburg entwickelt. Ziel des Spiels ist es, KindernKenntnisse über das Ökosystem See und die Auswirkungen der Wasserqualität und der Klimabedingungenauf Wasserpflanzen zu vermitteln. Darüber hinaus soll ein Bewusstsein für dieses Ökosystem und die Auswirkungenmenschlicher Eingriffe entstehen.}, author = {und David Schantz und Julian Gröh und Andreas Knote und Prof. Dr. Sebastian von Mammen und Prof. Dr. Juliano Cabral, Anne Lewerentz}, journal = {Mitteilungen der Fränkischen Geographischen Gesellschaft}, keywords = {myown}, number = 67, pages = {29–36}, title = {bioDIVERsity. Ein Computerspiel gegen das Imageproblem von Wasserpflanzen}, year = 2022 }
• Attitude of Nutrition Experts Toward Psychotherapy and Virtual Reality as Part of Obesity Treatment—An Online Survey. Gemesi, Kathrin; Holzmann, Sophie Laura; Hochrein, Regine; D{ö}llinger, Nina; Wienrich, Carolin; Weinberger, Natascha-Alexandra; Luck-Sikorski, Claudia; Holzapfel, Christina. In Frontiers in Psychiatry, 13. Frontiers Media SA, 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{gemesi2022attitude, author = {Gemesi, Kathrin and Holzmann, Sophie Laura and Hochrein, Regine and D{\"o}llinger, Nina and Wienrich, Carolin and Weinberger, Natascha-Alexandra and Luck-Sikorski, Claudia and Holzapfel, Christina}, journal = {Frontiers in Psychiatry}, keywords = {vitras}, publisher = {Frontiers Media SA}, title = {Attitude of Nutrition Experts Toward Psychotherapy and Virtual Reality as Part of Obesity Treatment—An Online Survey}, volume = 13, year = 2022 }
• Why Is It Not Solved Yet? Challenges for Production-Ready Autoscaling. Straesser, Martin; Grohmann, Johannes; von Kistowski, J{ó}akim; Eismann, Simon; Bauer, Andr{é}; Kounev, Samuel. In Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering, of ICPE ’22, pp. 105–115. Association for Computing Machinery, New York, NY, USA, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Autoscaling is a task of major importance in the cloud computing domain as it directly affects both operating costs and customer experience. Although there has been active research in this area for over ten years now, there is still a significant gap between the proposed methods in the literature and the deployed autoscalers in practice. Hence, many research autoscalers do not find their way into production deployments. This paper describes six core challenges that arise in production systems that are still not solved by most research autoscalers. We illustrate these problems through experiments in a realistic cloud environment with a real-world multi-service business application and show that commonly used autoscalers have various shortcomings. In addition, we analyze the behavior of overloaded services and show that these can be problematic for existing autoscalers. Generally, we analyze that these challenges are only insufficiently addressed in the literature and conclude that future scaling approaches should focus on the needs of production systems.

  @inproceedings{10.1145/3489525.3511680, abstract = {Autoscaling is a task of major importance in the cloud computing domain as it directly affects both operating costs and customer experience. Although there has been active research in this area for over ten years now, there is still a significant gap between the proposed methods in the literature and the deployed autoscalers in practice. Hence, many research autoscalers do not find their way into production deployments. This paper describes six core challenges that arise in production systems that are still not solved by most research autoscalers. We illustrate these problems through experiments in a realistic cloud environment with a real-world multi-service business application and show that commonly used autoscalers have various shortcomings. In addition, we analyze the behavior of overloaded services and show that these can be problematic for existing autoscalers. Generally, we analyze that these challenges are only insufficiently addressed in the literature and conclude that future scaling approaches should focus on the needs of production systems.}, address = {New York, NY, USA}, author = {Straesser, Martin and Grohmann, Johannes and von Kistowski, J\'{o}akim and Eismann, Simon and Bauer, Andr\'{e} and Kounev, Samuel}, booktitle = {Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering}, keywords = {microservices}, pages = {105–115}, publisher = {Association for Computing Machinery}, series = {ICPE '22}, title = {Why Is It Not Solved Yet? Challenges for Production-Ready Autoscaling}, year = 2022 }
• Virtual Reality im modernen Englischunterricht und das Potenzial für Inter- und Transkulturelles Lernen. Hein, Rebecca; Steinbock, Jeanine; Eisenmann, Maria; Wienrich, Carolin; Latoschik, Marc Erich. In MedienPädagogik Zeitschrift für Theorie und Praxis der Medienbildung, 47, pp. 246–266. 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{hein2021medienpaed, author = {Hein, Rebecca and Steinbock, Jeanine and Eisenmann, Maria and Wienrich, Carolin and Latoschik, Marc Erich}, journal = {MedienPädagogik Zeitschrift für Theorie und Praxis der Medienbildung}, keywords = {coteach}, pages = {246-266}, title = {Virtual Reality im modernen Englischunterricht und das Potenzial für Inter- und Transkulturelles Lernen}, volume = 47, year = 2022 }
• A Case Study on the Rapid Development of Natural and Synergistic Multimodal Interfaces for XR Use-Cases. Zimmerer, Chris; Fischbach, Martin; Latoschik, Marc Erich. In CHI Conference on Human Factors in Computing Systems Extended Abstracts, of CHI EA ’22. Association for Computing Machinery, New Orleans, LA, USA, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Multimodal Interfaces (MMIs) supporting the synergistic use of natural modalities like speech and gesture have been conceived as promising for spatial or 3D interactions, e.g., in Virtual, Augmented, and Mixed Reality (XR for short). Yet, the currently prevailing user interfaces are unimodal. Commercially available software platforms like the Unity or Unreal game engines simplify the complexity of developing XR applications through appropriate tool support. They provide ready-to-use device integration, e.g., for 3D controllers or motion tracking, and according interaction techniques such as menus, (3D) point-and-click, or even simple symbolic gestures to rapidly develop unimodal interfaces. A comparable tool support is yet missing for multimodal solutions in this and similar areas. We believe that this hinders user-centered research based on rapid prototyping of MMIs, the identification and formulation of practical design guidelines, the development of killer applications highlighting the power of MMIs, and ultimately a widespread adoption of MMIs. This article investigates potential reasons for the ongoing uncommonness of MMIs. Our case study illustrates and analyzes lessons learned during the development and application of a toolchain that supports rapid development of natural and synergistic MMIs for XR use-cases. We analyze the toolchain in terms of developer usability, development time, and MMI customization. This analysis is based on the knowledge gained in years of research and academic education. Specifically, it reflects on the development of appropriate MMI tools and their application in various demo use-cases, in user-centered research, and in the lab work of a mandatory MMI course of an HCI master’s program. The derived insights highlight successful choices made as well as potential areas for improvement.

  @inproceedings{10.1145/3491101.3503552, abstract = {Multimodal Interfaces (MMIs) supporting the synergistic use of natural modalities like speech and gesture have been conceived as promising for spatial or 3D interactions, e.g., in Virtual, Augmented, and Mixed Reality (XR for short). Yet, the currently prevailing user interfaces are unimodal. Commercially available software platforms like the Unity or Unreal game engines simplify the complexity of developing XR applications through appropriate tool support. They provide ready-to-use device integration, e.g., for 3D controllers or motion tracking, and according interaction techniques such as menus, (3D) point-and-click, or even simple symbolic gestures to rapidly develop unimodal interfaces. A comparable tool support is yet missing for multimodal solutions in this and similar areas. We believe that this hinders user-centered research based on rapid prototyping of MMIs, the identification and formulation of practical design guidelines, the development of killer applications highlighting the power of MMIs, and ultimately a widespread adoption of MMIs. This article investigates potential reasons for the ongoing uncommonness of MMIs. Our case study illustrates and analyzes lessons learned during the development and application of a toolchain that supports rapid development of natural and synergistic MMIs for XR use-cases. We analyze the toolchain in terms of developer usability, development time, and MMI customization. This analysis is based on the knowledge gained in years of research and academic education. Specifically, it reflects on the development of appropriate MMI tools and their application in various demo use-cases, in user-centered research, and in the lab work of a mandatory MMI course of an HCI master’s program. The derived insights highlight successful choices made as well as potential areas for improvement.}, address = {New York, NY, USA}, author = {Zimmerer, Chris and Fischbach, Martin and Latoschik, Marc Erich}, booktitle = {CHI Conference on Human Factors in Computing Systems Extended Abstracts}, keywords = {mmi}, publisher = {Association for Computing Machinery}, series = {CHI EA '22}, title = {A Case Study on the Rapid Development of Natural and Synergistic Multimodal Interfaces for XR Use-Cases}, year = 2022 }
• The Handbook on Socially Interactive Agents: 20 years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics Volume 2: Interactivity, Platforms, Application. Lugrin, Birgit; Pelachaud, Catherine; Traum, David. ACM, 2022.
  • [ BibTeX ]
  • [ URL ]
  @book{2022, author = {Lugrin, Birgit and Pelachaud, Catherine and Traum, David}, keywords = {MI}, publisher = {ACM}, title = {The Handbook on Socially Interactive Agents: 20 years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics Volume 2: Interactivity, Platforms, Application}, year = 2022 }
• Effects of Colored LEDs in Robotic Storytelling on Storytelling Experience and Robot Perception. Steinhaeusser, Sophia C.; Lugrin, Birgit. In Proceedings of the 2022 ACM/IEEE International Conference on Human-Robot Interaction (HRI2022). IEEE Press, 2022.
  • [ BibTeX ]
  @inproceedings{steinhaeusser2022effects, author = {Steinhaeusser, Sophia C. and Lugrin, Birgit}, booktitle = {Proceedings of the 2022 ACM/IEEE International Conference on Human-Robot Interaction (HRI2022)}, keywords = {steinhaeusser}, publisher = {IEEE Press}, title = {Effects of Colored LEDs in Robotic Storytelling on Storytelling Experience and Robot Perception}, year = 2022 }
• Preface. Lugrin, Birgit. In The Handbook on Socially Interactive Agents: 20 years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics Volume 2: Interactivity, Platforms, Application, p. xxv-xl. ACM, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inbook{noauthororeditor, author = {Lugrin, Birgit}, journal = {The Handbook on Socially Interactive Agents: 20 years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics Volume 2: Interactivity, Platforms, Application}, keywords = {mi}, pages = {xxv-xl}, publisher = {ACM}, title = {Preface}, year = 2022 }
• The Segment Number: Algorithms and Universal Lower Bounds for Some Classes of Planar Graphs. Goeßmann, Ina; Klawitter, Jonathan; Klemz, Boris; Klesen, Felix; Kobourov, Stephen G.; Kryven, Myroslav; Wolff, Alexander; Zink, Johannes. In Proc. 48th Int. Workshop Graph-Theoretic Concepts Comput. Sci. (WG’22), Vol. 13453 of Lecture Notes in Computer Science, M. Bekos, M. Kaufmann (eds.), p. 16 pages. Springer-Verlag, 2022.
  • [ BibTeX ]
  @inproceedings{gkkkkkwz-snaul-WG22, author = {Goe{\ss}mann, Ina and Klawitter, Jonathan and Klemz, Boris and Klesen, Felix and Kobourov, Stephen G. and Kryven, Myroslav and Wolff, Alexander and Zink, Johannes}, booktitle = {Proc. 48th Int. Workshop Graph-Theoretic Concepts Comput. Sci. (WG'22)}, editor = {Bekos, Michael and Kaufmann, Michael}, keywords = {visual_complexity}, pages = {16 pages}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {The Segment Number: Algorithms and Universal Lower Bounds for Some Classes of Planar Graphs}, volume = 13453, year = 2022 }
• Layered Drawing of Undirected Graphs with Generalized Port Constraints. Zink, Johannes; Walter, Julian; Baumeister, Joachim; Wolff, Alexander. In Computational Geometry: Theory and Applications, 105--106(101886), pp. 1–29. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  The aim of this research is a practical method to draw cable plans of complex machines. Such plans consist of electronic components and cables connecting specific ports of the components. Since the machines are configured for each client individually, cable plans need to be drawn automatically. The drawings must be well readable so that technicians can use them to debug the machines. In order to model plug sockets, we introduce port groups; within a group, ports can change their position (which we use to improve the aesthetics of the layout), but together the ports of a group must form a contiguous block. \par We approach the problem of drawing such cable plans by extending the well-known Sugiyama framework such that it incorporates ports and port groups. Since the framework assumes directed graphs, we propose several ways to orient the edges of the given undirected graph. We compare these methods experimentally, both on real-world data and synthetic data that carefully simulates real-world data. We measure the aesthetics of the resulting drawings by counting bends and crossings. Using these metrics, we experimentally compare our approach to Kieler [JVLC 2014], a library for drawing graphs in the presence of port constraints. Our method produced 10--30 \% fewer crossings, while it performed equally well or slightly worse than Kieler with respect to the number of bends and the time used to compute a drawing.

  @article{zwbw-ldugg-CGTA22, abstract = {The aim of this research is a practical method to draw cable plans of complex machines. Such plans consist of electronic components and cables connecting specific ports of the components. Since the machines are configured for each client individually, cable plans need to be drawn automatically. The drawings must be well readable so that technicians can use them to debug the machines. In order to model plug sockets, we introduce port groups; within a group, ports can change their position (which we use to improve the aesthetics of the layout), but together the ports of a group must form a contiguous block. \par We approach the problem of drawing such cable plans by extending the well-known Sugiyama framework such that it incorporates ports and port groups. Since the framework assumes directed graphs, we propose several ways to orient the edges of the given undirected graph. We compare these methods experimentally, both on real-world data and synthetic data that carefully simulates real-world data. We measure the aesthetics of the resulting drawings by counting bends and crossings. Using these metrics, we experimentally compare our approach to Kieler [JVLC 2014], a library for drawing graphs in the presence of port constraints. Our method produced 10–30 \% fewer crossings, while it performed equally well or slightly worse than Kieler with respect to the number of bends and the time used to compute a drawing.}, author = {Zink, Johannes and Walter, Julian and Baumeister, Joachim and Wolff, Alexander}, journal = {Computational Geometry: Theory and Applications}, keywords = {Sugiyama_framework}, number = 101886, pages = {1–29}, title = {Layered Drawing of Undirected Graphs with Generalized Port Constraints}, volume = {105–106}, year = 2022 }
• Analyzing Eye Tracking Data in Mirror Exposure. Döllinger, Nina; Göttfert, Christopher; Wolf, Erik; Mal, David; Latoschik, Marc Erich; Wienrich, Carolin. In 2022 Conference on Mensch und Computer, pp. 513–517. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Mirror exposure is an important method in the treatment of body image disturbances. Eye tracking can support the unaffected assessment of attention biases during mirror exposure. However, the analysis of eye tracking data in mirror exposure comes with various difficulties and is associated with a high manual workload during data processing. We present an automated data processing framework that enables us to determine any body part as an area of interest without placing markers on the bodies of participants. A short, formative user study proved the quality compared to the gold standard. The automatic processing and openness for different systems allow a broad range of applications.

  @inproceedings{dollinger2022eyetracking, abstract = {Mirror exposure is an important method in the treatment of body image disturbances. Eye tracking can support the unaffected assessment of attention biases during mirror exposure. However, the analysis of eye tracking data in mirror exposure comes with various difficulties and is associated with a high manual workload during data processing. We present an automated data processing framework that enables us to determine any body part as an area of interest without placing markers on the bodies of participants. A short, formative user study proved the quality compared to the gold standard. The automatic processing and openness for different systems allow a broad range of applications.}, author = {Döllinger, Nina and Göttfert, Christopher and Wolf, Erik and Mal, David and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {2022 Conference on Mensch und Computer}, keywords = {dmal}, pages = {513–517}, title = {Analyzing Eye Tracking Data in Mirror Exposure}, year = 2022 }
• MiSim: A Simulator for Resilience Assessment of Microservice-based Architectures. Frank, Sebastian; Wagner, Lion; Hakamian, Alireza; Straesser, Martin; van Hoorn, Andre. In 2022 IEEE 22nd International Conference on Software Quality, Reliability and Security (QRS), pp. 1014–1025. IEEE, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Increased resilience compared to monolithic architectures is both one of the key promises of microservice-based architectures and a big challenge, e.g., due to the systems’ distributed nature. Resilience assessment through simulation requires fewer resources than the measurement-based techniques used in practice. However, there is no existing simulation approach that is suitable for a holistic resilience assessment of microservices comprised of (i) representative fault injections, (ii) common resilience mechanisms, and (iii) time-varying workloads. This paper presents MiSim — an extensible simulator for resilience assessment of microservice-based architectures. It overcomes the stated limitations of related work. MiSim fits resilience engineering practices by supporting scenario-based experiments and requiring only lightweight input models. We demonstrate how MiSim simulates (1) common resilience mechanisms — i.e., circuit breaker, connection limiter, retry, load balancer, and autoscaler — and (2) fault injections — i.e., instance/service killing and latency injections. In addition, we use TeaStore, a reference microservice-based architecture, aiming to reproduce scaling behavior from an experiment by using simulation. Our results show that MiSim allows for quantitative insights into microservice-based systems’ complex transient behavior by providing up to 25 metrics.

  @inproceedings{FrankWagnerHakamianStraesserVanHoorn2022MiSim, abstract = {Increased resilience compared to monolithic architectures is both one of the key promises of microservice-based architectures and a big challenge, e.g., due to the systems’ distributed nature. Resilience assessment through simulation requires fewer resources than the measurement-based techniques used in practice. However, there is no existing simulation approach that is suitable for a holistic resilience assessment of microservices comprised of (i) representative fault injections, (ii) common resilience mechanisms, and (iii) time-varying workloads. This paper presents MiSim — an extensible simulator for resilience assessment of microservice-based architectures. It overcomes the stated limitations of related work. MiSim fits resilience engineering practices by supporting scenario-based experiments and requiring only lightweight input models. We demonstrate how MiSim simulates (1) common resilience mechanisms — i.e., circuit breaker, connection limiter, retry, load balancer, and autoscaler — and (2) fault injections — i.e., instance/service killing and latency injections. In addition, we use TeaStore, a reference microservice-based architecture, aiming to reproduce scaling behavior from an experiment by using simulation. Our results show that MiSim allows for quantitative insights into microservice-based systems’ complex transient behavior by providing up to 25 metrics.}, author = {Frank, Sebastian and Wagner, Lion and Hakamian, Alireza and Straesser, Martin and van Hoorn, Andre}, booktitle = {2022 IEEE 22nd International Conference on Software Quality, Reliability and Security (QRS)}, keywords = {resilience}, pages = {1014-1025}, publisher = {IEEE}, title = {MiSim: A Simulator for Resilience Assessment of Microservice-based Architectures}, year = 2022 }
• Accuracy and Systematic Biases of Heart Rate Measurements by Consumer-Grade Fitness Trackers in Postoperative Patients: Prospective Clinical Trial. Helmer, Philipp; Hottenrott, Sebastian; Rodemers, Philipp; Leppich, Robert; Helwich, Maja; Pryss, R{ü}diger; Kranke, Peter; Meybohm, Patrick; Winkler, Bernd E; Sammeth, Michael. In Journal of Medical Internet Research, 24(12), p. e42359. JMIR Publications Toronto, Canada, 2022.
  • [ BibTeX ]
  @article{helmer2022accuracy, author = {Helmer, Philipp and Hottenrott, Sebastian and Rodemers, Philipp and Leppich, Robert and Helwich, Maja and Pryss, R{\"u}diger and Kranke, Peter and Meybohm, Patrick and Winkler, Bernd E and Sammeth, Michael}, journal = {Journal of Medical Internet Research}, keywords = {t_journalmagazine}, number = 12, pages = {e42359}, publisher = {JMIR Publications Toronto, Canada}, title = {Accuracy and Systematic Biases of Heart Rate Measurements by Consumer-Grade Fitness Trackers in Postoperative Patients: Prospective Clinical Trial}, volume = 24, year = 2022 }
• Fly My Little Dragon: Using AR to Learn Geometry. Oberdörfer, Sebastian; Krop, Philipp; Straka, Samantha; Grafe, Silke; Latoschik, Marc Erich. In Proceedings of the IEEE Conference on Games (CoG ’22), pp. 528–531. IEEE, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  We present the gamified AR learning environment ARES. During the gameplay, learners guide the little dragon called ”Ares” through dungeons. Using AR, ARES threedimensionally integrates the dungeons in the real-world. Each dungeon represents a coordinate system with obstacles that ultimately create mathematical exercises, e.g. rotating a door to let the dragon fly through it. Overcoming such a challenge requires a learner to spatially analyze the exercise and apply the fundamental mathematical principles. ARES displays a debriefing screen at the end of a dungeon to further support the learning process. In a preliminary qualitative user study, preservice and in-service teachers saw great potential in ARES for providing further practical and motivating exercises to deepen the knowledge in the classroom and at home.

  @inproceedings{oberdorfer2022little, abstract = {We present the gamified AR learning environment ARES. During the gameplay, learners guide the little dragon called ”Ares” through dungeons. Using AR, ARES threedimensionally integrates the dungeons in the real-world. Each dungeon represents a coordinate system with obstacles that ultimately create mathematical exercises, e.g. rotating a door to let the dragon fly through it. Overcoming such a challenge requires a learner to spatially analyze the exercise and apply the fundamental mathematical principles. ARES displays a debriefing screen at the end of a dungeon to further support the learning process. In a preliminary qualitative user study, preservice and in-service teachers saw great potential in ARES for providing further practical and motivating exercises to deepen the knowledge in the classroom and at home.}, author = {Oberdörfer, Sebastian and Krop, Philipp and Straka, Samantha and Grafe, Silke and Latoschik, Marc Erich}, booktitle = {Proceedings of the IEEE Conference on Games (CoG '22)}, keywords = {myown}, month = {08}, pages = {528-531}, publisher = {IEEE}, title = {Fly My Little Dragon: Using AR to Learn Geometry}, year = 2022 }
• Retrospective Analysis of Training Intensity Distribution Based on Race Pace Versus Physiological Benchmarks in Highly Trained Sprint Kayakers. Matzka, Manuel; Leppich, Robert; Sperlich, Billy; Zinner, Christoph. In Sports Medicine-Open, 8(1), pp. 1–12. SpringerOpen, 2022.
  • [ BibTeX ]
  @article{matzka2022retrospective, author = {Matzka, Manuel and Leppich, Robert and Sperlich, Billy and Zinner, Christoph}, journal = {Sports Medicine-Open}, keywords = {t_journalmagazine}, number = 1, pages = {1–12}, publisher = {SpringerOpen}, title = {Retrospective Analysis of Training Intensity Distribution Based on Race Pace Versus Physiological Benchmarks in Highly Trained Sprint Kayakers}, volume = 8, year = 2022 }
• Congruence and Plausibility, not Presence?! Pivotal Conditions for XR Experiences and Effects, a Novel Model. Latoschik, Marc Erich; Wienrich, Carolin. In Frontiers in Virtual Reality, 3:694433. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Presence is often considered the most important quale describing the subjective feeling of being in a computer-generated and/or computer-mediated virtual environment. The identification and separation of orthogonal presence components, i.e., the place illusion and the plausibility illusion, has been an accepted theoretical model describing Virtual Reality (VR) experiences for some time. This perspective article challenges this presence-oriented VR theory. First, we argue that a place illusion cannot be the major construct to describe the much wider scope of virtual, augmented, and mixed reality (VR, AR, MR: or XR for short). Second, we argue that there is no plausibility illusion but merely plausibility, and we derive the place illusion caused by the congruent and plausible generation of spatial cues and similarly for all the current model’s so-defined illusions. Finally, we propose congruence and plausibility to become the central essential conditions in a novel theoretical model describing XR experiences and effects.

  @article{latoschik2021coherence, abstract = {Presence is often considered the most important quale describing the subjective feeling of being in a computer-generated and/or computer-mediated virtual environment. The identification and separation of orthogonal presence components, i.e., the place illusion and the plausibility illusion, has been an accepted theoretical model describing Virtual Reality (VR) experiences for some time. This perspective article challenges this presence-oriented VR theory. First, we argue that a place illusion cannot be the major construct to describe the much wider scope of virtual, augmented, and mixed reality (VR, AR, MR: or XR for short). Second, we argue that there is no plausibility illusion but merely plausibility, and we derive the place illusion caused by the congruent and plausible generation of spatial cues and similarly for all the current model’s so-defined illusions. Finally, we propose congruence and plausibility to become the central essential conditions in a novel theoretical model describing XR experiences and effects.}, author = {Latoschik, Marc Erich and Wienrich, Carolin}, journal = {Frontiers in Virtual Reality}, keywords = {c.wienrich}, month = {06}, title = {Congruence and Plausibility, not Presence?! Pivotal Conditions for XR Experiences and Effects, a Novel Model}, volume = {3:694433}, year = 2022 }
• Point me to your Opinion, {S}en{P}oi. Pfister, Jan; Wankerl, Sebastian; Hotho, Andreas. In Proceedings of the 16th International Workshop on Semantic Evaluation (SemEval-2022), pp. 1313–1323. Association for Computational Linguistics, Seattle, United States, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Structured Sentiment Analysis is the task of extracting sentiment tuples in a graph structure commonly from review texts. We adapt the Aspect-Based Sentiment Analysis pointer network BARTABSA to model this tuple extraction as a sequence prediction task and extend their output grammar to account for the increased complexity of Structured Sentiment Analysis. To predict structured sentiment tuples in languages other than English we swap BART for a multilingual mT5 and introduce a novel Output Length Regularization to mitigate overfitting to common target sequence lengths, thereby improving the performance of the model by up to 70{\%}. We evaluate our approach on seven datasets in five languages including a zero shot crosslingual setting.

  @inproceedings{pfister-etal-2022-senpoi, abstract = {Structured Sentiment Analysis is the task of extracting sentiment tuples in a graph structure commonly from review texts. We adapt the Aspect-Based Sentiment Analysis pointer network BARTABSA to model this tuple extraction as a sequence prediction task and extend their output grammar to account for the increased complexity of Structured Sentiment Analysis. To predict structured sentiment tuples in languages other than English we swap BART for a multilingual mT5 and introduce a novel Output Length Regularization to mitigate overfitting to common target sequence lengths, thereby improving the performance of the model by up to 70{\%}. We evaluate our approach on seven datasets in five languages including a zero shot crosslingual setting.}, address = {Seattle, United States}, author = {Pfister, Jan and Wankerl, Sebastian and Hotho, Andreas}, booktitle = {Proceedings of the 16th International Workshop on Semantic Evaluation (SemEval-2022)}, keywords = {from:janpf}, month = {07}, pages = {1313–1323}, publisher = {Association for Computational Linguistics}, title = {Point me to your Opinion, {S}en{P}oi}, year = 2022 }
• DBM: Decentralized Burst Mitigation for Self-Organizing LoRa Deployments. Raffeck, Simon; Geißler, Stefan; Hoßfeld, Tobias. In KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2022. 2022.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2022-7, author = {Raffeck, Simon and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2022}, keywords = {can}, month = {07}, title = {DBM: Decentralized Burst Mitigation for Self-Organizing LoRa Deployments}, year = 2022 }
• Analytical Model for the Energy Efficiency in Low Power IoT Deployments. Hoßfeld, Tobias; Raffeck, Simon; Loh, Frank; Geißler, Stefan. In 1st International Workshop on Network Energy Efficiency in the Softwarization Era. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  The recent rise of the Internet of Things (IoT) has given way to numerous challenges and research questions. One of the most critical issues in the area of low powered devices is the question of energy efficiency. Here, technologies like LoRa or Zigbee emerged, promising low power consumption while maintaining adequate performance. However, even when using these tailor made technologies, several configuration aspects need to be taken into account to provide high performance, energy efficient operation. To this end, we propose a generic model to compute the energy efficiency of wireless sensors under the assumption of perfect CSMA/CA channel access. We present numerical results for a typical LoRa device and highlight extensions towards other channel access mechanisms. Finally, we apply Kleinrock's power metric to obtain ideal system configurations for varying load parameters.

  @inproceedings{info3-inproceedings-2022-6, abstract = {The recent rise of the Internet of Things (IoT) has given way to numerous challenges and research questions. One of the most critical issues in the area of low powered devices is the question of energy efficiency. Here, technologies like LoRa or Zigbee emerged, promising low power consumption while maintaining adequate performance. However, even when using these tailor made technologies, several configuration aspects need to be taken into account to provide high performance, energy efficient operation. To this end, we propose a generic model to compute the energy efficiency of wireless sensors under the assumption of perfect CSMA/CA channel access. We present numerical results for a typical LoRa device and highlight extensions towards other channel access mechanisms. Finally, we apply Kleinrock's power metric to obtain ideal system configurations for varying load parameters.}, author = {Hoßfeld, Tobias and Raffeck, Simon and Loh, Frank and Geißler, Stefan}, booktitle = {1st International Workshop on Network Energy Efficiency in the Softwarization Era}, keywords = {can}, month = {06}, title = {Analytical Model for the Energy Efficiency in Low Power IoT Deployments}, year = 2022 }
• Graph-Based Gateway Placement for Better Performance in LoRaWAN Deployments. Loh, Frank; Mehling, Noah; Geißler, Stefan; Hoßfeld, Tobias. In 20th Mediterranean Communication and Computer Networking Conference (MedComNet). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Low Power Wide Area Networks with Long Range Wide Area Networks (LoRaWANs) as one of their most prominent representatives are very promising solutions for future Internet of Things deployments. The technology is characterized by low energy requirements leading to long battery lifetimes. However, the drawback is very limited throughput rates. However, the unreliable nature of the LoRa technology is hindering the adoption. Especially its random channel access approach leads to significant message collisions and thus, data loss in larger deployments. From a network planning point of view, one possibility to deal with collisions is the reduction of potentially colliding messages at the frequency bands in combination with limiting the transmission duration of messages. For that reason, we present a novel graph-based gateway placement approach. The main focus is collision probability reduction, which directly increases reliability in LoRaWAN deployments. We show that our approach performs similar to state-of-the-art related work in the worst case and reduces the required number of gateways by up to 40% while reducing the collision probability by up to 70%. Furthermore, we discuss the scalability of our approach to cover arbitrarily large networks with gateways and only little overhead by splitting the problem into smaller sub-problems.

  @inproceedings{info3-inproceedings-2022-19, abstract = {Low Power Wide Area Networks with Long Range Wide Area Networks (LoRaWANs) as one of their most prominent representatives are very promising solutions for future Internet of Things deployments. The technology is characterized by low energy requirements leading to long battery lifetimes. However, the drawback is very limited throughput rates. However, the unreliable nature of the LoRa technology is hindering the adoption. Especially its random channel access approach leads to significant message collisions and thus, data loss in larger deployments. From a network planning point of view, one possibility to deal with collisions is the reduction of potentially colliding messages at the frequency bands in combination with limiting the transmission duration of messages. For that reason, we present a novel graph-based gateway placement approach. The main focus is collision probability reduction, which directly increases reliability in LoRaWAN deployments. We show that our approach performs similar to state-of-the-art related work in the worst case and reduces the required number of gateways by up to 40% while reducing the collision probability by up to 70%. Furthermore, we discuss the scalability of our approach to cover arbitrarily large networks with gateways and only little overhead by splitting the problem into smaller sub-problems.}, author = {Loh, Frank and Mehling, Noah and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {20th Mediterranean Communication and Computer Networking Conference (MedComNet)}, keywords = {5mart}, month = {06}, title = {Graph-Based Gateway Placement for Better Performance in LoRaWAN Deployments}, year = 2022 }
• X-Ray Goggles for the ISP: Improving in-Network Web and App QoE Monitoring with Deep Learning. Casas, Pedro; Wassermann, Sarah; Seufert, Michael; Wehner, Nikolas; Dinica, Olivia; Hoßfeld, Tobias. In Network Traffic Measurement and Analysis Conference (TMA). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  The wide adoption of end-to-end encryption is drastically limiting the visibility Internet Service Providers (ISPs) have on the performance of the services consumed by their customers. In times of strong competition, where customer experience plays a key role in churn management, ISPs require novel solutions enabling network-wide Quality of Experience (QoE) monitoring. To this end, we present DeepQoE, a deep-learning based approach to infer the QoE of web services and mobile applications from the ISP perspective, relying exclusively on the analysis of encrypted network traffic. Using raw features derived from the encrypted stream of bytes as input to deep Convolutional Neural Networks (CNNs), DeepQoE infers the Speed Index of web browsing sessions and general mobile apps with unprecedented accuracy, improving the state of the art by more than 25%, and reducing the QoE inference error in terms of mean opinion scores by nearly 40%. DeepQoE implements a web fingerprinting solution to identify individual web browsing sessions within concurrent web pages traffic, enabling highly detailed, per web page QoE inference in practical deployments. Extensive evaluations over a large and heterogeneous dataset composed of web and app measurements, using different device types and for top-popular websites and apps, confirm the out-performance of DeepQoE over previously used shallow-learning models, as well as the deep-model generalization to different devices, web pages, apps, and network setups. DeepQoE is the first deployable system providing such a deep, highly-detailed QoE for individual web browsing and mobile apps over encrypted traffic, using deep learning models on heterogeneous measurements.

  @inproceedings{info3-inproceedings-2022-11, abstract = {The wide adoption of end-to-end encryption is drastically limiting the visibility Internet Service Providers (ISPs) have on the performance of the services consumed by their customers. In times of strong competition, where customer experience plays a key role in churn management, ISPs require novel solutions enabling network-wide Quality of Experience (QoE) monitoring. To this end, we present DeepQoE, a deep-learning based approach to infer the QoE of web services and mobile applications from the ISP perspective, relying exclusively on the analysis of encrypted network traffic. Using raw features derived from the encrypted stream of bytes as input to deep Convolutional Neural Networks (CNNs), DeepQoE infers the Speed Index of web browsing sessions and general mobile apps with unprecedented accuracy, improving the state of the art by more than 25%, and reducing the QoE inference error in terms of mean opinion scores by nearly 40%. DeepQoE implements a web fingerprinting solution to identify individual web browsing sessions within concurrent web pages traffic, enabling highly detailed, per web page QoE inference in practical deployments. Extensive evaluations over a large and heterogeneous dataset composed of web and app measurements, using different device types and for top-popular websites and apps, confirm the out-performance of DeepQoE over previously used shallow-learning models, as well as the deep-model generalization to different devices, web pages, apps, and network setups. DeepQoE is the first deployable system providing such a deep, highly-detailed QoE for individual web browsing and mobile apps over encrypted traffic, using deep learning models on heterogeneous measurements.}, author = {Casas, Pedro and Wassermann, Sarah and Seufert, Michael and Wehner, Nikolas and Dinica, Olivia and Hoßfeld, Tobias}, booktitle = {Network Traffic Measurement and Analysis Conference (TMA)}, keywords = {myown}, month = {06}, title = {X-Ray Goggles for the ISP: Improving in-Network Web and App QoE Monitoring with Deep Learning}, year = 2022 }
• YouTube Dataset on Mobile Streaming for Internet Traffic Modeling and Streaming Analysis. Loh, Frank; Wamser, Florian; Poignée, Fabian; Geißler, Stefan; Hoßfeld, Tobias. In Nature, Scientific Data. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Around 4.9 billion Internet users worldwide watch billions of hours of online video every day. As a result, streaming is by far the predominant type of traffic in communication networks. According to Google statistics, three out of five video views come from mobile devices. Thus, in view of the continuous technological advances in end devices and increasing mobile use, datasets for mobile streaming are indispensable in research but only sparsely dealt with in literature so far. With this public dataset, we provide 1,081 hours of time-synchronous video measurements at network, transport, and application layer with the native YouTube streaming client on mobile devices. The dataset includes 80 network scenarios with 171 different individual bandwidth settings measured in 5,181 runs with limited bandwidth, 1,939 runs with emulated 3 G/4 G traces, and 4,022 runs with pre-defined bandwidth changes. This corresponds to 332 GB video payload. We present the most relevant quality indicators for scientific use, i.e., initial playback delay, streaming video quality, adaptive video quality changes, video rebuffering events, and streaming phases.

  @article{info3-article-2022-17, abstract = {Around 4.9 billion Internet users worldwide watch billions of hours of online video every day. As a result, streaming is by far the predominant type of traffic in communication networks. According to Google statistics, three out of five video views come from mobile devices. Thus, in view of the continuous technological advances in end devices and increasing mobile use, datasets for mobile streaming are indispensable in research but only sparsely dealt with in literature so far. With this public dataset, we provide 1,081 hours of time-synchronous video measurements at network, transport, and application layer with the native YouTube streaming client on mobile devices. The dataset includes 80 network scenarios with 171 different individual bandwidth settings measured in 5,181 runs with limited bandwidth, 1,939 runs with emulated 3 G/4 G traces, and 4,022 runs with pre-defined bandwidth changes. This corresponds to 332 GB video payload. We present the most relevant quality indicators for scientific use, i.e., initial playback delay, streaming video quality, adaptive video quality changes, video rebuffering events, and streaming phases.}, author = {Loh, Frank and Wamser, Florian and Poignée, Fabian and Geißler, Stefan and Hoßfeld, Tobias}, journal = {Nature, Scientific Data}, keywords = {myown}, month = {06}, title = {YouTube Dataset on Mobile Streaming for Internet Traffic Modeling and Streaming Analysis}, year = 2022 }
• Constant Delay Switching: Asynchronous Traffic Shaping with Jitter Control. Grigorjew, Alexej; Metzger, Florian; Hoßfeld, Tobias; Specht, Johannes; Götz, Franz-Josef; Chen, Feng; Schmitt, Jürgen. In 2022 IFIP Networking Conference (IFIP Networking). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Recent developments in the Time Sensitive Networking (TSN) group have put forth a number of mechanisms to improve deterministic latency in layer 2 switches. Their shaping approaches differ with respect to prerequisites, flexibility, maximum latency, and latency variation (jitter). Asynchronous solutions provide flexibility in dynamic scenarios, but Credit-Based Shaping (CBS) and Asynchronous Traffic Shaping (ATS) come with a high latency variance, as the minimum latency is not affected by them. Some applications in industrial and automotive use cases require low jitter while trying to avoid a dependency on time synchronization, and even TSN's redundancy mechanism benefits from a lower latency variance. This work is bridging the gap between low-jitter transmission requirements and asynchronous shaping mechanisms. In this paper, the application of a stateless Asynchronous Constant Delay Shaper (ACDS) is discussed. It collects the queuing duration from the previous bridge to delay each frame for the remaining time such that a constant per-hop delay for each frame is achieved. The discussion includes the prerequisites, the mechanism itself, and its technical complexity, as well as a formal analysis of its guaranteed latency by proving its relation to a token-bucket based ATS. Further, two extensions are discussed, and an evaluation shows the applicability of ACDS by comparing its jitter to ATS in a frame-level simulation.

  @inproceedings{info3-inproceedings-2022-15, abstract = {Recent developments in the Time Sensitive Networking (TSN) group have put forth a number of mechanisms to improve deterministic latency in layer 2 switches. Their shaping approaches differ with respect to prerequisites, flexibility, maximum latency, and latency variation (jitter). Asynchronous solutions provide flexibility in dynamic scenarios, but Credit-Based Shaping (CBS) and Asynchronous Traffic Shaping (ATS) come with a high latency variance, as the minimum latency is not affected by them. Some applications in industrial and automotive use cases require low jitter while trying to avoid a dependency on time synchronization, and even TSN's redundancy mechanism benefits from a lower latency variance. This work is bridging the gap between low-jitter transmission requirements and asynchronous shaping mechanisms. In this paper, the application of a stateless Asynchronous Constant Delay Shaper (ACDS) is discussed. It collects the queuing duration from the previous bridge to delay each frame for the remaining time such that a constant per-hop delay for each frame is achieved. The discussion includes the prerequisites, the mechanism itself, and its technical complexity, as well as a formal analysis of its guaranteed latency by proving its relation to a token-bucket based ATS. Further, two extensions are discussed, and an evaluation shows the applicability of ACDS by comparing its jitter to ATS in a frame-level simulation.}, author = {Grigorjew, Alexej and Metzger, Florian and Hoßfeld, Tobias and Specht, Johannes and Götz, Franz-Josef and Chen, Feng and Schmitt, Jürgen}, booktitle = {2022 IFIP Networking Conference (IFIP Networking)}, keywords = {kosinu5}, month = {06}, title = {Constant Delay Switching: Asynchronous Traffic Shaping with Jitter Control}, year = 2022 }
• DeepCrypt - Deep Learning for QoE Monitoring and Fingerprinting of User Actions in Adaptive Video Streaming. Casas, Pedro; Seufert, Michael; Wassermann, Sarah; Gardlo, Bruno; Wehner, Nikolas; Schatz, Raimund. In IEEE Conference on Network Softwarization (IEEE NetSoft 2022). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  We introduce DeepCrypt, a deep-learning based approach to analyze YouTube video streaming Quality of Experience (QoE) from the Internet Service Provider (ISP) perspective, relying exclusively on the analysis of encrypted network traffic. Using raw features derived on-line from the encrypted stream of bytes, DeepCrypt can infer six different video QoE indicators capturing the user-perceived performance of the service, including the initial playback delay, the number and frequency of rebuffering events, the video playback quality, the video encoding bitrate, and the number of quality changes. DeepCrypt offers deep visibility into the behavior of the end-user, enabling the fingerprinting and detection of different user actions on the video player, such as video pauses and playback scrubbing (forward, backward, out-of-buffer), offering a complete visibility on the video streaming process from in-network traffic measurements. Extensive evaluations over a large and heterogeneous dataset composed of mobile and fixed-line measurements, using the YouTube HTML5 player, the native YouTube mobile app, as well as a generic HTML5 video player built on top of open source libraries, and considering measurements collected at different ISPs, confirm the out-performance of DeepCrypt over previously used shallow-learning models, as well as the deep-model generalization to different video players and network setups. To the best of our knowledge, this is the first paper tackling such a combined QoE and user-actions approach for video streaming applications, using deep learning models over heterogeneous measurements.

  @inproceedings{info3-inproceedings-2022-9, abstract = {We introduce DeepCrypt, a deep-learning based approach to analyze YouTube video streaming Quality of Experience (QoE) from the Internet Service Provider (ISP) perspective, relying exclusively on the analysis of encrypted network traffic. Using raw features derived on-line from the encrypted stream of bytes, DeepCrypt can infer six different video QoE indicators capturing the user-perceived performance of the service, including the initial playback delay, the number and frequency of rebuffering events, the video playback quality, the video encoding bitrate, and the number of quality changes. DeepCrypt offers deep visibility into the behavior of the end-user, enabling the fingerprinting and detection of different user actions on the video player, such as video pauses and playback scrubbing (forward, backward, out-of-buffer), offering a complete visibility on the video streaming process from in-network traffic measurements. Extensive evaluations over a large and heterogeneous dataset composed of mobile and fixed-line measurements, using the YouTube HTML5 player, the native YouTube mobile app, as well as a generic HTML5 video player built on top of open source libraries, and considering measurements collected at different ISPs, confirm the out-performance of DeepCrypt over previously used shallow-learning models, as well as the deep-model generalization to different video players and network setups. To the best of our knowledge, this is the first paper tackling such a combined QoE and user-actions approach for video streaming applications, using deep learning models over heterogeneous measurements.}, author = {Casas, Pedro and Seufert, Michael and Wassermann, Sarah and Gardlo, Bruno and Wehner, Nikolas and Schatz, Raimund}, booktitle = {IEEE Conference on Network Softwarization (IEEE NetSoft 2022)}, keywords = {myown}, month = {06}, title = {DeepCrypt - Deep Learning for QoE Monitoring and Fingerprinting of User Actions in Adaptive Video Streaming}, year = 2022 }
• An Introduction to Online Video Game QoS and QoE Influencing Factors. Metzger, Florian; Geißler, Stefan; Grigorjew, Alexej; Loh, Frank; Moldovan, Christian; Seufert, Michael; Hoßfeld, Tobias. In IEEE Communications Surveys & Tutorials. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Online video games and cloud gaming are rapidly growing in pervasiveness. Their resource demands can put significant stress on the global communication infrastructure. And network conditions are amongst the chief factors that influence one's enjoyment while playing games. This makes it imperative for video games to be considered for network dimensioning, server placement or protocol development. For that reason, in this work we provide an introduction to the technical aspects of video games in general and of their network aspects in particular. This understanding forms the basis for a rich taxonomy of factors that influence and provide context to a video game's Quality of Service (QoS) and Quality of Experience (QoE). The taxonomy covers influence factors from all aspects involved in a video game, from the subjective player and game influence factors to the system and networking influence factors. Finally, this work gives an overview of conducted and ongoing research as well as future research opportunities while taking into account lessons learned from past approaches.

  @article{info3-article-2022-16, abstract = {Online video games and cloud gaming are rapidly growing in pervasiveness. Their resource demands can put significant stress on the global communication infrastructure. And network conditions are amongst the chief factors that influence one's enjoyment while playing games. This makes it imperative for video games to be considered for network dimensioning, server placement or protocol development. For that reason, in this work we provide an introduction to the technical aspects of video games in general and of their network aspects in particular. This understanding forms the basis for a rich taxonomy of factors that influence and provide context to a video game's Quality of Service (QoS) and Quality of Experience (QoE). The taxonomy covers influence factors from all aspects involved in a video game, from the subjective player and game influence factors to the system and networking influence factors. Finally, this work gives an overview of conducted and ongoing research as well as future research opportunities while taking into account lessons learned from past approaches.}, author = {Metzger, Florian and Geißler, Stefan and Grigorjew, Alexej and Loh, Frank and Moldovan, Christian and Seufert, Michael and Hoßfeld, Tobias}, journal = {IEEE Communications Surveys & Tutorials}, keywords = {10.1109/COMST.2022.3177251}, month = {05}, title = {An Introduction to Online Video Game QoS and QoE Influencing Factors}, year = 2022 }
• Edge-Case Integration into Established NAT Traversal Techniques. Keller, Simon; Hoßfeld, Tobias; von Mammen, Sebastian. In 2022 IEEE Ninth International Conference on Communications and Electronics (ICCE), pp. 75–80. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Traversing Network Address Translation (NAT) is often necessary for establishing direct communication between clients. The traversal of NAT with static port translation is solved in many cases by the Session Traversal Utilities for NAT (STUN) protocol. Nevertheless, it does not cover the traversal of progressing symmetric and random symmetric NAT, which make it necessary to correctly predict opened ports. This paper presents a method for predicting (a) progressing symmetric NAT-translated ports based on a network traffic model and the Expected Value Method, and (b) random symmetric NAT-translated ports based on heuristics between monitored and opened ports across numerous traversal attempts. Tests were conducted in German cities using local cellular communication providers. Compared to established approaches, they yielded considerable improvements traversing progressing symmetric NAT and slight improvements traversing random symmetric NAT in real-world environments.

  @inproceedings{9852092, abstract = {Traversing Network Address Translation (NAT) is often necessary for establishing direct communication between clients. The traversal of NAT with static port translation is solved in many cases by the Session Traversal Utilities for NAT (STUN) protocol. Nevertheless, it does not cover the traversal of progressing symmetric and random symmetric NAT, which make it necessary to correctly predict opened ports. This paper presents a method for predicting (a) progressing symmetric NAT-translated ports based on a network traffic model and the Expected Value Method, and (b) random symmetric NAT-translated ports based on heuristics between monitored and opened ports across numerous traversal attempts. Tests were conducted in German cities using local cellular communication providers. Compared to established approaches, they yielded considerable improvements traversing progressing symmetric NAT and slight improvements traversing random symmetric NAT in real-world environments.}, author = {Keller, Simon and Hoßfeld, Tobias and von Mammen, Sebastian}, booktitle = {2022 IEEE Ninth International Conference on Communications and Electronics (ICCE)}, keywords = {myown}, month = {07}, pages = {75-80}, title = {Edge-Case Integration into Established NAT Traversal Techniques}, year = 2022 }
• Experience and Guidelines for Sorting Algorithm Choices and Their Energy Efficiency. Meissner, Maximilian; Kamthania, Supriya; Rawtani, Nishant; Bucek, James; Lange, Klaus-Dieter; Kounev, Samuel. In Companion of the 2022 ACM/SPEC International Conference on Performance Engineering. ACM, New York, NY, USA, 2022.
  • [ BibTeX ]
  @inproceedings{meissner2022experience, address = {New York, NY, USA}, author = {Meissner, Maximilian and Kamthania, Supriya and Rawtani, Nishant and Bucek, James and Lange, Klaus-Dieter and Kounev, Samuel}, booktitle = {Companion of the 2022 ACM/SPEC International Conference on Performance Engineering}, keywords = {t_workshop}, month = {04}, publisher = {ACM}, title = {Experience and Guidelines for Sorting Algorithm Choices and Their Energy Efficiency}, year = 2022 }
• Automated Triage of Performance Change Points Using Time Series Analysis and Machine Learning. Bauer, André; Straesser, Martin; Beierlieb, Lukas; Meissner, Maximilian; Kounev, Samuel. In Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering. ACM, 2022.
  • [ BibTeX ]
  @conference{bauer2022automated, author = {Bauer, André and Straesser, Martin and Beierlieb, Lukas and Meissner, Maximilian and Kounev, Samuel}, booktitle = {Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering}, keywords = {machine_learning}, month = {04}, publisher = {ACM}, title = {Automated Triage of Performance Change Points Using Time Series Analysis and Machine Learning}, year = 2022 }
• Automated Triage of Performance Change Points Using Time Series Analysis and Machine Learning. Bauer, André; Straesser, Martin; Beierlieb, Lukas; Meissner, Maximilian; Kounev, Samuel. In Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering. ACM, 2022.
  • [ BibTeX ]
  @conference{bauer2022automated, author = {Bauer, André and Straesser, Martin and Beierlieb, Lukas and Meissner, Maximilian and Kounev, Samuel}, booktitle = {Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering}, keywords = {machine_learning}, month = {04}, publisher = {ACM}, title = {Automated Triage of Performance Change Points Using Time Series Analysis and Machine Learning}, year = 2022 }
• Dataset: Who is Alyx? (GitHub Repository). Rack, Christian; Sieper, Fabian; Schach, Lukas; Latoschik, Marc E. 2022, April.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This dataset contains over 110 hours of motion, eye-tracking and physiological data from 71 players of the virtual reality game “Half-Life: Alyx”. Each player played the game on two separate days for about 45 minutes using a HTC Vive Pro.

  @dataset{who_is_alyx_2022, abstract = {This dataset contains over 110 hours of motion, eye-tracking and physiological data from 71 players of the virtual reality game “Half-Life: Alyx”. Each player played the game on two separate days for about 45 minutes using a HTC Vive Pro.}, author = {Rack, Christian and Sieper, Fabian and Schach, Lukas and Latoschik, Marc E.}, keywords = {VirtualReality}, month = {04}, title = {Dataset: Who is Alyx? (GitHub Repository)}, year = 2022 }
• Characterizing Mobile Signaling Anomalies in the Internet-of-Things. Vomhoff, Viktoria; Geißler, Stefan; Loh, Frank; Bauer, Wolfgang; Hoßfeld, Tobias. In 2nd IFIP/IEEE International workshop on Fully-Flexible Internet Architectures and Protocols for the Next-Generation Tactile Internet (FlexNGIA). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  The development and adoption speed of new Internet of Things (IoT) devices and applications is constantly increasing. In particular in mobile networks, however, constant connectivity for all newly developed, globally spread, and occasionally geographically mobile devices is challenging. While the main business of current network operators is in particular, not to roam these new device generation between different networks, whereas new so-called Mobile Virtual Network Operators (MVNOs) arise with exactly this business case. They use already available Radio Access Networks and deploy SIM cards that are able to establish data connection everywhere on the basis of international roaming agreements. However, because of the complex interconnection of different systems, additional challenges arise. Outages in one network component might impact the whole system. In this work, we study these signaling anomalies called incidents based on a dataset received from a global MVNO. The goal of this work is to determine traffic characteristics during these incidents towards a better understanding of signaling traffic in IoT networks. Thus, this work can be seen as a fundamental basis to help operators in a characterization, and in particular prediction and avoidance of signaling incidents.

  @inproceedings{info3-inproceedings-2022-4, abstract = {The development and adoption speed of new Internet of Things (IoT) devices and applications is constantly increasing. In particular in mobile networks, however, constant connectivity for all newly developed, globally spread, and occasionally geographically mobile devices is challenging. While the main business of current network operators is in particular, not to roam these new device generation between different networks, whereas new so-called Mobile Virtual Network Operators (MVNOs) arise with exactly this business case. They use already available Radio Access Networks and deploy SIM cards that are able to establish data connection everywhere on the basis of international roaming agreements. However, because of the complex interconnection of different systems, additional challenges arise. Outages in one network component might impact the whole system. In this work, we study these signaling anomalies called incidents based on a dataset received from a global MVNO. The goal of this work is to determine traffic characteristics during these incidents towards a better understanding of signaling traffic in IoT networks. Thus, this work can be seen as a fundamental basis to help operators in a characterization, and in particular prediction and avoidance of signaling incidents.}, author = {Vomhoff, Viktoria and Geißler, Stefan and Loh, Frank and Bauer, Wolfgang and Hoßfeld, Tobias}, booktitle = {2nd IFIP/IEEE International workshop on Fully-Flexible Internet Architectures and Protocols for the Next-Generation Tactile Internet (FlexNGIA)}, keywords = {can}, month = {04}, title = {Characterizing Mobile Signaling Anomalies in the Internet-of-Things}, year = 2022 }
• SPEC Research Group Newsletter, Issue 11. Kounev, Samuel; van Hoorn, Andre; Straesser, Martin; Bauer, Andr{é}. 2022, April.
  • [ BibTeX ]
  @misc{SPEC-RG-NEWSLETTER-11, author = {Kounev, Samuel and van Hoorn, Andre and Straesser, Martin and Bauer, Andr{é}}, keywords = {SPEC}, month = {04}, note = {Published by Standard Performance Evaluation Corporation (SPEC)}, title = {SPEC Research Group Newsletter, Issue 11}, year = 2022 }
• Automated Triage of Performance Change Points Using Time Series Analysis and Machine Learning. Bauer, André; Straesser, Martin; Beierlieb, Lukas; Meissner, Maximilian; Kounev, Samuel. In Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering. ACM, 2022.
  • [ BibTeX ]
  @conference{bauer2022automated, author = {Bauer, André and Straesser, Martin and Beierlieb, Lukas and Meissner, Maximilian and Kounev, Samuel}, booktitle = {Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering}, keywords = {machine_learning}, month = {04}, publisher = {ACM}, title = {Automated Triage of Performance Change Points Using Time Series Analysis and Machine Learning}, year = 2022 }
• Performance Evaluation of Next-Generation Data Plane Architectures and their Components. Technical Report (PhD dissertation), . Geißler, Stefan. PhD dissertation. University of Würzburg, 2022, April.
  • [ Abstract ]
  • [ BibTeX ]
  In this doctoral thesis we cover the performance evaluation of next generation data plane architectures, comprised of complex software as well as programmable hardware components that allow fine granular configuration. In the scope of the thesis we propose mechanisms to monitor the performance of singular components and model key performance indicators of software based packet processing solutions. We present novel approaches towards network abstraction that allow the integration of heterogeneous data plane technologies into a singular network while maintaining total transparency between control and data plane. Finally, we investigate a full, complex system consisting of multiple software-based solutions and perform a detailed performance analysis. We employ simulative approaches to investigate overload control mechanisms that allow efficient operation under adversary conditions. The contributions of this work build the foundation for future research in the areas of network softwarization and network function virtualization.

  @phdthesis{info3-dissertation-2022-1, abstract = {In this doctoral thesis we cover the performance evaluation of next generation data plane architectures, comprised of complex software as well as programmable hardware components that allow fine granular configuration. In the scope of the thesis we propose mechanisms to monitor the performance of singular components and model key performance indicators of software based packet processing solutions. We present novel approaches towards network abstraction that allow the integration of heterogeneous data plane technologies into a singular network while maintaining total transparency between control and data plane. Finally, we investigate a full, complex system consisting of multiple software-based solutions and perform a detailed performance analysis. We employ simulative approaches to investigate overload control mechanisms that allow efficient operation under adversary conditions. The contributions of this work build the foundation for future research in the areas of network softwarization and network function virtualization.}, author = {Geißler, Stefan}, keywords = {can}, month = {04}, school = {University of Würzburg}, title = {Performance Evaluation of Next-Generation Data Plane Architectures and their Components}, year = 2022 }
• Affordable Measurement Setups for Networking Device Latency with Sub-Microsecond Accuracy. Grigorjew, Alexej; Diederich, Philip; Hoßfeld, Tobias; Kellerer, Wolfgang. In WueWoWAS’22 KuVS Fachgespraech - Wuerzburg Workshop on Next-Generation Communication Networks. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  This document presents a networking latency measurement setup that focuses on affordability and universal applicability, and can provide sub-microsecond accuracy. It explains the prerequisites, hardware choices, and considerations to respect during measurement. In addition, it discusses the necessity for exhaustive latency measurements when dealing with high availability and low latency requirements. Preliminary results show that the accuracy is within 0.02 microseconds when used with the Intel I350-T2 network adapter.

  @inproceedings{info3-inproceedings-2022-14, abstract = {This document presents a networking latency measurement setup that focuses on affordability and universal applicability, and can provide sub-microsecond accuracy. It explains the prerequisites, hardware choices, and considerations to respect during measurement. In addition, it discusses the necessity for exhaustive latency measurements when dealing with high availability and low latency requirements. Preliminary results show that the accuracy is within 0.02 microseconds when used with the Intel I350-T2 network adapter.}, author = {Grigorjew, Alexej and Diederich, Philip and Hoßfeld, Tobias and Kellerer, Wolfgang}, booktitle = {WueWoWAS'22 KuVS Fachgespraech - Wuerzburg Workshop on Next-Generation Communication Networks}, keywords = {appaware2}, month = {07}, title = {Affordable Measurement Setups for Networking Device Latency with Sub-Microsecond Accuracy}, year = 2022 }
• {femtoPro}: {Ultrafast} {Phenomena} in {Virtual} {Reality}. Müller, Stefan; Brixner, Tobias; Knote, Andreas; Schnepp, Wilhelm; Truman, Samuel; Vetter, Anne; von Mammen, Sebastian. In The {International} {Conference} on {Ultrafast} {Phenomena} ({UP}) 2022 (2022), paper {W4A}.42, p. W4A.42. Optica Publishing Group, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  We introduce “femtoPro,” an interactive simulator of an ultrafast laser laboratory in virtual reality (VR). Gaussian beam propagation as well as linear and nonlinear optical phenomena are calculated in real time on consumer-grade VR devices.

  @inproceedings{mullerFemtoProUltrafastPhenomena2022, abstract = {We introduce “femtoPro,” an interactive simulator of an ultrafast laser laboratory in virtual reality (VR). Gaussian beam propagation as well as linear and nonlinear optical phenomena are calculated in real time on consumer-grade VR devices.}, author = {Müller, Stefan and Brixner, Tobias and Knote, Andreas and Schnepp, Wilhelm and Truman, Samuel and Vetter, Anne and von Mammen, Sebastian}, booktitle = {The {International} {Conference} on {Ultrafast} {Phenomena} ({UP}) 2022 (2022), paper {W4A}.42}, keywords = {VR}, month = {07}, pages = {W4A.42}, publisher = {Optica Publishing Group}, title = {{femtoPro}: {Ultrafast} {Phenomena} in {Virtual} {Reality}}, year = 2022 }
• Pandemic in the Digital Age: Analyzing WhatsApp Communication Behavior before, during, and after the COVID-19 Lockdown. Seufert, Anika; Poignée, Fabian; Hoßfeld, Tobias; Seufert, Michael. In Humanities and Social Sciences Communications, 9(1), pp. 140 (1–9). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  The strict restrictions introduced by the COVID-19 lockdowns, which started from March 2020, changed people’s daily lives and habits on many different levels. In this work, we investigate the impact of the lockdown on the communication behavior in the mobile instant messaging application WhatsApp. Our evaluations are based on a large dataset of 2577 private chat histories with 25,378,093 messages from 51,973 users. The analysis of the one-to-one and group conversations confirms that the lockdown severely altered the communication in WhatsApp chats compared to pre-pandemic time ranges. In particular, we observe short-term effects, which caused an increased message frequency in the first lockdown months and a shifted communication activity during the day in March and April 2020. Moreover, we also see long-term effects of the ongoing pandemic situation until February 2021, which indicate a change of communication behavior towards more regular messaging, as well as a persisting change in activity during the day. The results of our work show that even anonymized chat histories can tell us a lot about people’s behavior and especially behavioral changes during the COVID-19 pandemic and thus are of great relevance for behavioral researchers. Furthermore, looking at the pandemic from an Internet provider perspective, these insights can be used during the next pandemic, or if the current COVID-19 situation worsens, to adapt communication networks to the changed usage behavior early on and thus avoid network congestion.

  @article{info3-article-2022-14, abstract = {The strict restrictions introduced by the COVID-19 lockdowns, which started from March 2020, changed people’s daily lives and habits on many different levels. In this work, we investigate the impact of the lockdown on the communication behavior in the mobile instant messaging application WhatsApp. Our evaluations are based on a large dataset of 2577 private chat histories with 25,378,093 messages from 51,973 users. The analysis of the one-to-one and group conversations confirms that the lockdown severely altered the communication in WhatsApp chats compared to pre-pandemic time ranges. In particular, we observe short-term effects, which caused an increased message frequency in the first lockdown months and a shifted communication activity during the day in March and April 2020. Moreover, we also see long-term effects of the ongoing pandemic situation until February 2021, which indicate a change of communication behavior towards more regular messaging, as well as a persisting change in activity during the day. The results of our work show that even anonymized chat histories can tell us a lot about people’s behavior and especially behavioral changes during the COVID-19 pandemic and thus are of great relevance for behavioral researchers. Furthermore, looking at the pandemic from an Internet provider perspective, these insights can be used during the next pandemic, or if the current COVID-19 situation worsens, to adapt communication networks to the changed usage behavior early on and thus avoid network congestion.}, author = {Seufert, Anika and Poignée, Fabian and Hoßfeld, Tobias and Seufert, Michael}, journal = {Humanities and Social Sciences Communications}, keywords = {ucn}, month = {04}, number = 1, pages = {140 (1-9)}, title = {Pandemic in the Digital Age: Analyzing WhatsApp Communication Behavior before, during, and after the COVID-19 Lockdown}, volume = 9, year = 2022 }
• Generic Model to Quantify Energy Consumption for Different LoRaWAN Channel Access Methods. Loh, Frank; Raffeck, Simon; Geißler, Stefan; Hoßfeld, Tobias. In 18th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  LoRaWAN is one of the most promising Internet of Things technologies with regard to low energy consumption. However, the currently used random channel access has much potential for improvement. Thus, current literature studies alternative channel access approaches, but the energy consumption is often not taken into consideration. For that reason, we present a generic model to quantify energy consumption in LoRaWAN for different channel access mechanisms based on a state machine. With our model, we can describe the energy consumption for specific access mechanisms or for the complete network. Our model shows that random access only performs best if no additional receive windows are opened. A simple improvement is Listen before Talk. For networks with high load, improvements are achieved by a more complex scheduled MAC. Our model serves as a basis for future energy consumption studies, conducted through measurements or simulations.

  @inproceedings{info3-inproceedings-2022-21, abstract = {LoRaWAN is one of the most promising Internet of Things technologies with regard to low energy consumption. However, the currently used random channel access has much potential for improvement. Thus, current literature studies alternative channel access approaches, but the energy consumption is often not taken into consideration. For that reason, we present a generic model to quantify energy consumption in LoRaWAN for different channel access mechanisms based on a state machine. With our model, we can describe the energy consumption for specific access mechanisms or for the complete network. Our model shows that random access only performs best if no additional receive windows are opened. A simple improvement is Listen before Talk. For networks with high load, improvements are achieved by a more complex scheduled MAC. Our model serves as a basis for future energy consumption studies, conducted through measurements or simulations.}, author = {Loh, Frank and Raffeck, Simon and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {18th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob)}, keywords = {5mart}, month = 10, title = {Generic Model to Quantify Energy Consumption for Different LoRaWAN Channel Access Methods}, year = 2022 }
• The Influence of Visible Cables and Story Content on Perceived Autonomy in Social Human-Robot Interaction. Roesler, Eileen; Steinhaeusser, Sophia C.; Lugrin, Birgit; Onnasch, Linda. In Robotics, 12(1), p. 3. MDPI, 2022.
  • [ BibTeX ]
  @article{Roesler_2022, author = {Roesler, Eileen and Steinhaeusser, Sophia C. and Lugrin, Birgit and Onnasch, Linda}, journal = {Robotics}, keywords = {steinhaeusser}, month = 12, number = 1, pages = 3, publisher = {MDPI}, title = {The Influence of Visible Cables and Story Content on Perceived Autonomy in Social Human-Robot Interaction}, volume = 12, year = 2022 }
• A case study on the stability of performance tests for serverless applications. Eismann, Simon; Costa, Diego; Liao, Lizhi; Bezemer, Cor-Paul; Shang, Weiyi; van Hoorn, André; Kounev, Samuel. In Journal of Systems and Software (JSS), 189. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Context: While in serverless computing, application resource management and operational concerns are generally delegated to the cloud provider, ensuring that serverless applications meet their performance requirements is still a responsibility of the developers. Performance testing is a commonly used performance assessment practice; however, it traditionally requires visibility of the resource environment. Objective: In this study, we investigate whether performance tests of serverless applications are stable, that is, if their results are reproducible, and what implications the serverless paradigm has for performance tests. Method: We conduct a case study where we collect two datasets of performance test results: (a) repetitions of performance tests for varying memory size and load intensities and (b) three repetitions of the same performance test every day for ten months. Results: We find that performance tests of serverless applications are comparatively stable if conducted on the same day. However, we also observe short-term performance variations and frequent long-term performance changes. Conclusion: Performance tests for serverless applications can be stable; however, the serverless model impacts the planning, execution, and analysis of performance tests.

  @article{eismann2022study, abstract = {Context: While in serverless computing, application resource management and operational concerns are generally delegated to the cloud provider, ensuring that serverless applications meet their performance requirements is still a responsibility of the developers. Performance testing is a commonly used performance assessment practice; however, it traditionally requires visibility of the resource environment. Objective: In this study, we investigate whether performance tests of serverless applications are stable, that is, if their results are reproducible, and what implications the serverless paradigm has for performance tests. Method: We conduct a case study where we collect two datasets of performance test results: (a) repetitions of performance tests for varying memory size and load intensities and (b) three repetitions of the same performance test every day for ten months. Results: We find that performance tests of serverless applications are comparatively stable if conducted on the same day. However, we also observe short-term performance variations and frequent long-term performance changes. Conclusion: Performance tests for serverless applications can be stable; however, the serverless model impacts the planning, execution, and analysis of performance tests.}, author = {Eismann, Simon and Costa, Diego and Liao, Lizhi and Bezemer, Cor-Paul and Shang, Weiyi and van Hoorn, André and Kounev, Samuel}, journal = {Journal of Systems and Software (JSS)}, keywords = {t_journalmagazine}, title = {A case study on the stability of performance tests for serverless applications}, volume = 189, year = 2022 }
• Mixed-Cultural Speech for Intelligent Virtual Agents - the Impact of Different Non-Native Accents Using Natural or Synthetic Speech in the English Language. Obremski, David; Hering, Helena Babette; Friedrich, Paula; Lugrin, Birgit. In HAI ’22: International Conference on Human-Agent Interaction, pp. 67–75. ACM, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Obremski_HAI_Paper_2022, author = {Obremski, David and Hering, Helena Babette and Friedrich, Paula and Lugrin, Birgit}, booktitle = {HAI '22: International Conference on Human-Agent Interaction}, keywords = {accent}, month = 12, pages = {67-75}, publisher = {ACM}, title = {Mixed-Cultural Speech for Intelligent Virtual Agents - the Impact of Different Non-Native Accents Using Natural or Synthetic Speech in the English Language}, year = 2022 }
• Push the Red Button: Comparing Notification Placement with Augmented and Non-Augmented Tasks in AR. Plabst, Lucas; Oberdörfer, Sebastian; Ortega, Francisco Raul; Niebling, Florian. In Proceedings of the 10th Symposium on Spatial User Interaction (SUI ’22). ACM, New York, NY, USA, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{plabst2022press, address = {New York, NY, USA}, author = {Plabst, Lucas and Oberdörfer, Sebastian and Ortega, Francisco Raul and Niebling, Florian}, booktitle = {Proceedings of the 10th Symposium on Spatial User Interaction (SUI '22)}, keywords = {myown}, month = 12, publisher = {ACM}, title = {Push the Red Button: Comparing Notification Placement with Augmented and Non-Augmented Tasks in AR}, year = 2022 }
• Mixed-Cultural Speech for Mixed-Cultural Users - Natural vs. Synthetic Speech for Virtual Agents. Obremski, David; Lugrin, Birgit. In HAI ’22: International Conference on Human-Agent Interaction, pp. 290–292. ACM, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Obremski_HAI_Poster_2022, author = {Obremski, David and Lugrin, Birgit}, booktitle = {HAI '22: International Conference on Human-Agent Interaction}, keywords = {accent}, month = 12, pages = {290-292}, publisher = {ACM}, title = {Mixed-Cultural Speech for Mixed-Cultural Users - Natural vs. Synthetic Speech for Virtual Agents}, year = 2022 }
• Fingerprinting Webpages and Smartphone Apps from Encrypted Network Traffic with WebScanner. Casas, Pedro; Wehner, Nikolas; Wassermann, Sarah; Seufert, Michael. In Global Internet (GI) Symposium. Paris, France, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  The wide adoption of end-to-end encryption drastically limits the visibility Internet Service Providers (ISPs) have on the services consumed by their customers. This is particularly challenging for monitoring and analysis of web and apps traffic, which is highly complex and heterogeneous. Loading a web page or app today requires tens of flows to download the various resources located in distributed cloud servers from different content providers. We introduce WebScanner, a webpage and app fingerprinting approach capable to identify all the traffic flows corresponding to individual webpage and app loading sessions within concurrent web pages traffic, enabling highly detailed, per webpage analysis in practical deployments. Different from the state of the art in web and app traffic fingerprinting, and as our most relevant contribution, WebScanner automatically performs the parsing of all the traffic generated by a web visit and its isolation from concurrent traffic, instead of assuming that an external oracle system does so. WebScanner also implements a deep fingerprinting approach to detect user action-dependent traffic from apps, relying on simple machine learning models and strong input features as fingerprints. Extensive evaluation across a large measurement dataset of popular webpages and mobile apps confirms the outstanding performance of WebScanner, identifying the top-500 Alexa websites with precision and recall (P/R) above 95%, isolating their full contents with P/R above 80% for up to 15 concurrent webpages, and detecting specific action-dependent apps traffic with average P/R above 92%.

  @inproceedings{info3-inproceedings-2022-18, abstract = {The wide adoption of end-to-end encryption drastically limits the visibility Internet Service Providers (ISPs) have on the services consumed by their customers. This is particularly challenging for monitoring and analysis of web and apps traffic, which is highly complex and heterogeneous. Loading a web page or app today requires tens of flows to download the various resources located in distributed cloud servers from different content providers. We introduce WebScanner, a webpage and app fingerprinting approach capable to identify all the traffic flows corresponding to individual webpage and app loading sessions within concurrent web pages traffic, enabling highly detailed, per webpage analysis in practical deployments. Different from the state of the art in web and app traffic fingerprinting, and as our most relevant contribution, WebScanner automatically performs the parsing of all the traffic generated by a web visit and its isolation from concurrent traffic, instead of assuming that an external oracle system does so. WebScanner also implements a deep fingerprinting approach to detect user action-dependent traffic from apps, relying on simple machine learning models and strong input features as fingerprints. Extensive evaluation across a large measurement dataset of popular webpages and mobile apps confirms the outstanding performance of WebScanner, identifying the top-500 Alexa websites with precision and recall (P/R) above 95%, isolating their full contents with P/R above 80% for up to 15 concurrent webpages, and detecting specific action-dependent apps traffic with average P/R above 92%.}, address = {Paris, France}, author = {Casas, Pedro and Wehner, Nikolas and Wassermann, Sarah and Seufert, Michael}, booktitle = {Global Internet (GI) Symposium}, keywords = {ucn}, month = 11, title = {Fingerprinting Webpages and Smartphone Apps from Encrypted Network Traffic with WebScanner}, year = 2022 }
• The impact of mixed-cultural speech on the stereotypical perception of a virtual robot. Obremski, David; Friedrich, Paula; Haak, Nora; Schaper, Philipp; Lugrin, Birgit. In Frontiers in Robotics and AI, 9. Frontiers Media SA, 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{Obremski_2022, author = {Obremski, David and Friedrich, Paula and Haak, Nora and Schaper, Philipp and Lugrin, Birgit}, journal = {Frontiers in Robotics and AI}, keywords = {accent}, month = 11, publisher = {Frontiers Media SA}, title = {The impact of mixed-cultural speech on the stereotypical perception of a virtual robot}, volume = 9, year = 2022 }
• Exploratory Study on the Perception of Intelligent Virtual Agents With Non-Native Accents Using Synthetic and Natural Speech in German. Obremski, David; Hering, Helena Babette; Friedrich, Paula; Lugrin, Birgit. In INTERNATIONAL CONFERENCE ON MULTIMODAL INTERACTION. ACM, 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Obremski_2022, author = {Obremski, David and Hering, Helena Babette and Friedrich, Paula and Lugrin, Birgit}, booktitle = {INTERNATIONAL CONFERENCE ON MULTIMODAL INTERACTION}, keywords = {accent}, month = 11, publisher = {ACM}, title = {Exploratory Study on the Perception of Intelligent Virtual Agents With Non-Native Accents Using Synthetic and Natural Speech in German}, year = 2022 }
• Comparing Traditional and GAN-based Approaches for the Synthesis of Wide Area Network Topologies. Dietz, Katharina; Seufert, Michael; Hoßfeld, Tobias. In 18th International Conference on Network and Service Management (CNSM). Thessaloniki, Greece, 2022.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2022-16, address = {Thessaloniki, Greece}, author = {Dietz, Katharina and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {18th International Conference on Network and Service Management (CNSM)}, keywords = {ucn}, month = 10, title = {Comparing Traditional and GAN-based Approaches for the Synthesis of Wide Area Network Topologies}, year = 2022 }
• {W}ue{D}evils at {S}em{E}val-2022 Task 8: Multilingual News Article Similarity via Pair-Wise Sentence Similarity Matrices. Wangsadirdja, Dirk; Heinickel, Felix; Trapp, Simon; Zehe, Albin; Kobs, Konstantin; Hotho, Andreas. In Proceedings of the 16th International Workshop on Semantic Evaluation (SemEval-2022), pp. 1235–1243. Association for Computational Linguistics, Seattle, United States, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  We present a system that creates pair-wise cosine and arccosine sentence similarity matrices using multilingual sentence embeddings obtained from pre-trained SBERT and Universal Sentence Encoder (USE) models respectively. For each news article sentence, it searches the most similar sentence from the other article and computes an average score. Further, a convolutional neural network calculates a total similarity score for the article pairs on these matrices. Finally, a random forest regressor merges the previous results to a final score that can optionally be extended with a publishing date score.

  @inproceedings{wangsadirdja2022wuedevils, abstract = {We present a system that creates pair-wise cosine and arccosine sentence similarity matrices using multilingual sentence embeddings obtained from pre-trained SBERT and Universal Sentence Encoder (USE) models respectively. For each news article sentence, it searches the most similar sentence from the other article and computes an average score. Further, a convolutional neural network calculates a total similarity score for the article pairs on these matrices. Finally, a random forest regressor merges the previous results to a final score that can optionally be extended with a publishing date score.}, address = {Seattle, United States}, author = {Wangsadirdja, Dirk and Heinickel, Felix and Trapp, Simon and Zehe, Albin and Kobs, Konstantin and Hotho, Andreas}, booktitle = {Proceedings of the 16th International Workshop on Semantic Evaluation (SemEval-2022)}, keywords = {multilingual}, month = {07}, pages = {1235–1243}, publisher = {Association for Computational Linguistics}, title = {{W}ue{D}evils at {S}em{E}val-2022 Task 8: Multilingual News Article Similarity via Pair-Wise Sentence Similarity Matrices}, year = 2022 }
• Parametric Skin Wound Generation for Medical Simulations. Schott, Christian; Hofmann, Sarah; von Mammen, Sebastian. In 2022 International Conference on Interactive Media, Smart Systems and Emerging Technologies (IMET), pp. 1–8. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Medical simulations offer various opportunities to improve treatment training in different areas of medicine. The realism and thus effectiveness of wound care training goes hand in hand with the realism of the wounds themselves. In this paper, we propose a novel approach to (a) procedurally generate convincing-looking wound textures and (b) to dynamically project them onto animated, skinned meshes. Our method allows for creating dermal wounds of different types including abrasions, lacerations and puncture wounds. We analyzed the outcome by recreating visualization instances of these types, demonstrating the applicability of our system.

  @inproceedings{9929659, abstract = {Medical simulations offer various opportunities to improve treatment training in different areas of medicine. The realism and thus effectiveness of wound care training goes hand in hand with the realism of the wounds themselves. In this paper, we propose a novel approach to (a) procedurally generate convincing-looking wound textures and (b) to dynamically project them onto animated, skinned meshes. Our method allows for creating dermal wounds of different types including abrasions, lacerations and puncture wounds. We analyzed the outcome by recreating visualization instances of these types, demonstrating the applicability of our system.}, author = {Schott, Christian and Hofmann, Sarah and von Mammen, Sebastian}, booktitle = {2022 International Conference on Interactive Media, Smart Systems and Emerging Technologies (IMET)}, keywords = {via-vr}, month = 10, pages = {1-8}, title = {Parametric Skin Wound Generation for Medical Simulations}, year = 2022 }
• Discrete-Time Analysis of Multi-Component Queuing Networks under Renewal Approximation. Geißler, Stefan; Lange, Stanislav; Haßllinger, Gerhard; Tran-Gia, Phuoc; Hoßfeld, Tobias. In 34st International Teletraffic Congress (ITC). , Shenzhen, China. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  The analytical and numerical performance evaluation of network components and distributed systems has been a staple in the networking community for many years. However, the ever growing complexity of modern systems and the need to gain detailed insights into systems consisting of many, interconnected components emphasizes the need for an extension to the classical single-component approach, and although approaches like Jackson Networks exist, their limited application scope lags behind the complexity of modern environments. To this end, we revisit existing models of the common Gi/Gi/1-oo queue, extend them to allow the concatenation of multiple queueing components, and evaluate the approximation error introduced through renewal approximation. We revisit previously performed parameter studies and evaluate the approximation error for a wide range of parameter combinations that we can solve through the power of modern computing equipment and efficient numerical implementations of our models. We show the main impact factors for the linear concatenation of queueing components as well as the split and superposition of processes. Our evaluations show that the renewal approximation can be applied to a wide range of parameters while still obtaining results within acceptable error margins.

  @inproceedings{info3-inproceedings-2022-17, abstract = {The analytical and numerical performance evaluation of network components and distributed systems has been a staple in the networking community for many years. However, the ever growing complexity of modern systems and the need to gain detailed insights into systems consisting of many, interconnected components emphasizes the need for an extension to the classical single-component approach, and although approaches like Jackson Networks exist, their limited application scope lags behind the complexity of modern environments. To this end, we revisit existing models of the common Gi/Gi/1-oo queue, extend them to allow the concatenation of multiple queueing components, and evaluate the approximation error introduced through renewal approximation. We revisit previously performed parameter studies and evaluate the approximation error for a wide range of parameter combinations that we can solve through the power of modern computing equipment and efficient numerical implementations of our models. We show the main impact factors for the linear concatenation of queueing components as well as the split and superposition of processes. Our evaluations show that the renewal approximation can be applied to a wide range of parameters while still obtaining results within acceptable error margins.}, author = {Geißler, Stefan and Lange, Stanislav and Haßllinger, Gerhard and Tran-Gia, Phuoc and Hoßfeld, Tobias}, booktitle = {34st International Teletraffic Congress (ITC). , Shenzhen, China}, keywords = {can}, month = {09}, title = {Discrete-Time Analysis of Multi-Component Queuing Networks under Renewal Approximation}, year = 2022 }
• Waiting along the Path: How Browsing Delays Impact the QoE of Music Streaming Applications. Seufert, Anika; Schweifler, Ralf; Poignée, Fabian; Seufert, Michael; Hoßfeld, Tobias. In 14th International Conference on Quality of Multimedia Experience (QoMEX). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Streaming has become the dominant source of media consumption, which not only applies to the widely researched field of video streaming, but also to music streaming. Here, previous studies so far have only researched the impact of streaming aspects, such as stalling events or initial loading times, on the QoE of music streaming. However, when using a music streaming application, users are already facing waiting times along the click path before they can start the actual streaming. These waiting times are caused by browsing delays, e.g., during searching for songs or scrolling through playlists, and can potentially deteriorate the QoE of the music streaming application. In this work, we conduct an online QoE study to quantify the impact of these browsing delays with the support of an emulated mobile music streaming web app. We found that browsing delays have no impact on the music streaming QoE, which shows that users are able to clearly distinguish between the two main functionalities of such apps, namely, browsing and streaming. However, browsing delays significantly reduce the QoE of the entire music streaming application, to a similar extent as if QoE degradations happen during the actual streaming. This shows that both browsing and streaming are equally important and have to be considered when designing music streaming applications.

  @inproceedings{info3-inproceedings-2022-13, abstract = {Streaming has become the dominant source of media consumption, which not only applies to the widely researched field of video streaming, but also to music streaming. Here, previous studies so far have only researched the impact of streaming aspects, such as stalling events or initial loading times, on the QoE of music streaming. However, when using a music streaming application, users are already facing waiting times along the click path before they can start the actual streaming. These waiting times are caused by browsing delays, e.g., during searching for songs or scrolling through playlists, and can potentially deteriorate the QoE of the music streaming application. In this work, we conduct an online QoE study to quantify the impact of these browsing delays with the support of an emulated mobile music streaming web app. We found that browsing delays have no impact on the music streaming QoE, which shows that users are able to clearly distinguish between the two main functionalities of such apps, namely, browsing and streaming. However, browsing delays significantly reduce the QoE of the entire music streaming application, to a similar extent as if QoE degradations happen during the actual streaming. This shows that both browsing and streaming are equally important and have to be considered when designing music streaming applications.}, author = {Seufert, Anika and Schweifler, Ralf and Poignée, Fabian and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {14th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {myown}, month = {09}, title = {Waiting along the Path: How Browsing Delays Impact the QoE of Music Streaming Applications}, year = 2022 }
• A Vital Improvement? Relating Google’s Core Web Vitals to Actual Web QoE. Wehner, Nikolas; Amir, Monisha; Seufert, Michael; Schatz, Raimund; Hoßfeld, Tobias. In 14th International Conference on Quality of Multimedia Experience (QoMEX), Best Paper Award. Lippstadt, Germany, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Providing sophisticated Web Quality of Experience (QoE) has become paramount for web service providers and network operators alike. Due to advances in Web technologies (HTML5, responsive design, etc.), traditional Web QoE models focusing mainly on loading times have to be refined and improved. In this work, we relate Google's Core Web Vitals, a set of metrics for improving user experience, to the loading time aspects of Web QoE. To this end, we first perform objective measurements in the Web using Google's Lighthouse. To close the gap between metrics and experience, we complement these objective measurements with subjective assessment by performing multiple crowdsourcing QoE studies. In these studies, we use CWeQS, a customized framework to emulate the entire web page loading process, and ask users for their experience while controlling the Core Web Vitals. Our results suggest that the Core Web Vitals have less predictive value for Web QoE than expected and that page loading times remain the main influence factor in this context.

  @inproceedings{info3-inproceedings-2022-12, abstract = {Providing sophisticated Web Quality of Experience (QoE) has become paramount for web service providers and network operators alike. Due to advances in Web technologies (HTML5, responsive design, etc.), traditional Web QoE models focusing mainly on loading times have to be refined and improved. In this work, we relate Google's Core Web Vitals, a set of metrics for improving user experience, to the loading time aspects of Web QoE. To this end, we first perform objective measurements in the Web using Google's Lighthouse. To close the gap between metrics and experience, we complement these objective measurements with subjective assessment by performing multiple crowdsourcing QoE studies. In these studies, we use CWeQS, a customized framework to emulate the entire web page loading process, and ask users for their experience while controlling the Core Web Vitals. Our results suggest that the Core Web Vitals have less predictive value for Web QoE than expected and that page loading times remain the main influence factor in this context.}, address = {Lippstadt, Germany}, author = {Wehner, Nikolas and Amir, Monisha and Seufert, Michael and Schatz, Raimund and Hoßfeld, Tobias}, booktitle = {14th International Conference on Quality of Multimedia Experience (QoMEX), Best Paper Award}, keywords = {ucn}, month = {09}, title = {A Vital Improvement? Relating Google's Core Web Vitals to Actual Web QoE}, year = 2022 }
• Repeated experience or a virtual nose to reduce simulator sickness? Investigating prediction of the sensorial conflict theory and the rest-frame hypothesis in two virtual games. Wienrich, Carolin; Obremski, David; Israel, Johann Habakuk. In Entertainment Computing, 43, p. 100514. Elsevier {BV}, 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{Wienrich_2022, author = {Wienrich, Carolin and Obremski, David and Israel, Johann Habakuk}, journal = {Entertainment Computing}, keywords = {MI}, month = {08}, pages = 100514, publisher = {Elsevier {BV}}, title = {Repeated experience or a virtual nose to reduce simulator sickness? Investigating prediction of the sensorial conflict theory and the rest-frame hypothesis in two virtual games}, volume = 43, year = 2022 }
• LoRaWAN Network Planning in Smart Environments: Towards Reliability, Scalability, and Cost Reduction. Loh, Frank; Geißler, Stefan; Hoßfeld, Tobias. In WueWoWAS 22 - KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  The goal in this work is to present a guidance for LoRaWAN planning to improve overall reliability for message transmissions and scalability. At the end, the cost component is discussed. Therefore, a five step approach is presented that helps to plan a LoRaWAN deployment step by step: Based on the device locations, an initial gateway placement is suggested followed by in-depth frequency and channel access planning. After an initial planning phase, updates for channel access and the initial gateway planning is suggested that should also be done periodically during network operation. Since current gateway placement approaches are only studied with random channel access, there is a lot of potential in the cell planning phase. Furthermore, the performance of different channel access approaches is highly related on network load, and thus cell size and sensor density. Last, the influence of different cell planning ideas on expected costs are discussed.

  @inproceedings{info3-inproceedings-2022-20, abstract = {The goal in this work is to present a guidance for LoRaWAN planning to improve overall reliability for message transmissions and scalability. At the end, the cost component is discussed. Therefore, a five step approach is presented that helps to plan a LoRaWAN deployment step by step: Based on the device locations, an initial gateway placement is suggested followed by in-depth frequency and channel access planning. After an initial planning phase, updates for channel access and the initial gateway planning is suggested that should also be done periodically during network operation. Since current gateway placement approaches are only studied with random channel access, there is a lot of potential in the cell planning phase. Furthermore, the performance of different channel access approaches is highly related on network load, and thus cell size and sensor density. Last, the influence of different cell planning ideas on expected costs are discussed.}, author = {Loh, Frank and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {WueWoWAS 22 - KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks}, keywords = {5mart}, month = {07}, title = {LoRaWAN Network Planning in Smart Environments: Towards Reliability, Scalability, and Cost Reduction}, year = 2022 }
• Identification of Signaling Patterns in Mobile IoT Signaling Traffic. Vomhoff, Viktoria; Geißler, Stefan; Hoßfeld, Tobias. In WueWoWAS 22 - KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks. 2022.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2022-8, author = {Vomhoff, Viktoria and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {WueWoWAS 22 - KuVS Fachgespräch - Würzburg Workshop on Next-Generation Communication Networks}, keywords = {can}, month = {07}, title = {Identification of Signaling Patterns in Mobile IoT Signaling Traffic}, year = 2022 }
• {LSX} team5 at {S}em{E}val-2022 Task 8: Multilingual News Article Similarity Assessment based on Word- and Sentence Mover{’}s Distance. Heil, Stefan; Kopp, Karina; Zehe, Albin; Kobs, Konstantin; Hotho, Andreas. In Proceedings of the 16th International Workshop on Semantic Evaluation (SemEval-2022), pp. 1190–1195. Association for Computational Linguistics, Seattle, United States, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper introduces our submission for the SemEval 2022 Task 8: Multilingual News Article Similarity. The task of the competition consisted of the development of a model, capable of determining the similarity between pairs of multilingual news articles. To address this challenge, we evaluated the Word Mover{'}s Distance in conjunction with word embeddings from ConceptNet Numberbatch and term frequencies of WorldLex, as well the Sentence Mover{'}s Distance based on sentence embeddings generated by pretrained transformer models of Sentence-BERT. To facilitate the comparison of multilingual articles with Sentence-BERT models, we deployed a Neural Machine Translation system. All our models achieve stable results in multilingual similarity estimation without learning parameters.

  @inproceedings{heil2022lsxteam5, abstract = {This paper introduces our submission for the SemEval 2022 Task 8: Multilingual News Article Similarity. The task of the competition consisted of the development of a model, capable of determining the similarity between pairs of multilingual news articles. To address this challenge, we evaluated the Word Mover{'}s Distance in conjunction with word embeddings from ConceptNet Numberbatch and term frequencies of WorldLex, as well the Sentence Mover{'}s Distance based on sentence embeddings generated by pretrained transformer models of Sentence-BERT. To facilitate the comparison of multilingual articles with Sentence-BERT models, we deployed a Neural Machine Translation system. All our models achieve stable results in multilingual similarity estimation without learning parameters.}, address = {Seattle, United States}, author = {Heil, Stefan and Kopp, Karina and Zehe, Albin and Kobs, Konstantin and Hotho, Andreas}, booktitle = {Proceedings of the 16th International Workshop on Semantic Evaluation (SemEval-2022)}, keywords = {multilingual}, month = {07}, pages = {1190–1195}, publisher = {Association for Computational Linguistics}, title = {{LSX} team5 at {S}em{E}val-2022 Task 8: Multilingual News Article Similarity Assessment based on Word- and Sentence Mover{'}s Distance}, year = 2022 }
• Data Usage in IoT: A Characterization of GTP Tunnels in M2M Mobile Networks. Raffeck, Simon; Geißler, Stefan; Krolikowski, Michael; Gebert, Steffen; Hoßfeld, Tobias. In 2nd IFIP/IEEE International workshop on Fully-Flexible Internet Architectures and Protocols for the Next-Generation Tactile Internet (FlexNGIA). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  IoT and M2M devices have seen a significant growth in usage and deployment over the last years. Gaining insight into device and data usage behavior exhibited by the participants of mobile networks is elementary for MNO and MVNO to scale their networks and provide a reliable service. This work aims to make use of its first of a kind dataset, spanning multiple countries and MNO, to provide a detailed characterization of GTP tunnels and devices. To this end, general statistics are used to describe the observed data traffic focusing on the distribution of the tunnel duration and volume as well as periodic device behavior. An approximate metric is introduced to analyze the periodicity and synchronicity of IoT devices. Lastly, we publish the data investigated in this work and provide a large scale dataset on the data usage behavior of IoT devices to interested researchers.

  @inproceedings{info3-inproceedings-2022-5, abstract = {IoT and M2M devices have seen a significant growth in usage and deployment over the last years. Gaining insight into device and data usage behavior exhibited by the participants of mobile networks is elementary for MNO and MVNO to scale their networks and provide a reliable service. This work aims to make use of its first of a kind dataset, spanning multiple countries and MNO, to provide a detailed characterization of GTP tunnels and devices. To this end, general statistics are used to describe the observed data traffic focusing on the distribution of the tunnel duration and volume as well as periodic device behavior. An approximate metric is introduced to analyze the periodicity and synchronicity of IoT devices. Lastly, we publish the data investigated in this work and provide a large scale dataset on the data usage behavior of IoT devices to interested researchers.}, author = {Raffeck, Simon and Geißler, Stefan and Krolikowski, Michael and Gebert, Steffen and Hoßfeld, Tobias}, booktitle = {2nd IFIP/IEEE International workshop on Fully-Flexible Internet Architectures and Protocols for the Next-Generation Tactile Internet (FlexNGIA)}, keywords = {can}, month = {04}, title = {Data Usage in IoT: A Characterization of GTP Tunnels in M2M Mobile Networks}, year = 2022 }
• Not all Web Pages are Born the Same. Content Tailored Learning for Web QoE Inference. Casas, Pedro; Wassermann, Sarah; Wehner, Nikolas; Seufert, Michael; Hoßfeld, Tobias. In IEEE International Symposium on Measurements & Networking (M&N 2022). 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Web Quality of Experience (QoE) monitoring is a critical task for Internet Service Providers (ISPs), especially due to the key role played by customer experience in churn management. Previously, we have tackled the problem of Web QoE inference from the ISP perspective, relying on passive measurement of encrypted network traffic and machine learning models. In this paper, we exploit the broad heterogeneity of contents embedded in web pages to improve the state of the art performance in Web QoE inference, relying on web-content learning model tailoring. By analyzing the top-500 most popular web pages of the Internet through unsupervised learning, we discover different web page content classes which realize significantly different Web QoE inference performance. We train supervised learning inference models separately for each of these classes, using the well-known Speed Index (SI) metric as proxy to Web QoE. Empirical evaluations on a large corpus of Web QoE measurements for top popular websites demonstrate that our combined content-tailored approach improves the inference performance of the SI by almost 30% with respect to previous single-model approaches, reducing the QoE inference error in terms of mean opinion scores by more than 40%.

  @inproceedings{info3-inproceedings-2022-10, abstract = {Web Quality of Experience (QoE) monitoring is a critical task for Internet Service Providers (ISPs), especially due to the key role played by customer experience in churn management. Previously, we have tackled the problem of Web QoE inference from the ISP perspective, relying on passive measurement of encrypted network traffic and machine learning models. In this paper, we exploit the broad heterogeneity of contents embedded in web pages to improve the state of the art performance in Web QoE inference, relying on web-content learning model tailoring. By analyzing the top-500 most popular web pages of the Internet through unsupervised learning, we discover different web page content classes which realize significantly different Web QoE inference performance. We train supervised learning inference models separately for each of these classes, using the well-known Speed Index (SI) metric as proxy to Web QoE. Empirical evaluations on a large corpus of Web QoE measurements for top popular websites demonstrate that our combined content-tailored approach improves the inference performance of the SI by almost 30% with respect to previous single-model approaches, reducing the QoE inference error in terms of mean opinion scores by more than 40%.}, author = {Casas, Pedro and Wassermann, Sarah and Wehner, Nikolas and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {IEEE International Symposium on Measurements & Networking (M&N 2022)}, keywords = {myown}, month = {07}, title = {Not all Web Pages are Born the Same. Content Tailored Learning for Web QoE Inference}, year = 2022 }
• On Learning Hierarchical Embeddings from Encrypted Network Traffic. Wehner, Nikolas; Ring, Markus; Schüler, Joshua; Hotho, Andreas; Hoßfeld, Tobias; Seufert, Michael. In 33th IEEE/IFIP Network Operations and Management Symposium (NOMS). Budapest, Hungary, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  This work presents a novel concept for learning embeddings from encrypted network traffic. In contrast to existing approaches, we evaluate the feasibility of hierarchical embeddings by iteratively aggregating packet embeddings to flow embeddings, and flow embeddings to trace embeddings. The hierarchical embedding concept was designed to especially consider complex dependencies of Internet traffic on different time scales. We describe this novel embedding concept for the domain of network traffic in full detail, and evaluate its performance for the downstream task of website fingerprinting, i.e., identifying websites from encrypted traffic, which is relevant for network management, e.g., as a prerequisite for QoE monitoring or for intrusion detection. Our evaluation reveals that embeddings are a promising solution for website fingerprinting as our model correctly labels up to 99.8\% of traces from 500 target websites.

  @inproceedings{info3-inproceedings-2022-1, abstract = {This work presents a novel concept for learning embeddings from encrypted network traffic. In contrast to existing approaches, we evaluate the feasibility of hierarchical embeddings by iteratively aggregating packet embeddings to flow embeddings, and flow embeddings to trace embeddings. The hierarchical embedding concept was designed to especially consider complex dependencies of Internet traffic on different time scales. We describe this novel embedding concept for the domain of network traffic in full detail, and evaluate its performance for the downstream task of website fingerprinting, i.e., identifying websites from encrypted traffic, which is relevant for network management, e.g., as a prerequisite for QoE monitoring or for intrusion detection. Our evaluation reveals that embeddings are a promising solution for website fingerprinting as our model correctly labels up to 99.8\% of traces from 500 target websites.}, address = {Budapest, Hungary}, author = {Wehner, Nikolas and Ring, Markus and Schüler, Joshua and Hotho, Andreas and Hoßfeld, Tobias and Seufert, Michael}, booktitle = {33th IEEE/IFIP Network Operations and Management Symposium (NOMS)}, keywords = {myown}, month = {04}, title = {On Learning Hierarchical Embeddings from Encrypted Network Traffic}, year = 2022 }
• Interactive Hemodynamic Simulation Model of a Cross-scale Cardiovascular System. Hofmann, Sarah; M{ü}ller, Andreas; von Mammen, Sebastian. In ANNSIM 22. Society for Modeling & Simulation International (SCS), 2022.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Hofmann2022INTERACTIVEHS, author = {Hofmann, Sarah and M{\"u}ller, Andreas and von Mammen, Sebastian}, booktitle = {ANNSIM 22}, keywords = {myown}, publisher = {Society for Modeling & Simulation International (SCS)}, title = {Interactive Hemodynamic Simulation Model of a Cross-scale Cardiovascular System}, year = 2022 }
• SCRAPS: Scalable Collective Remote Attestation for Pub-Sub IoT Networks with Untrusted Proxy Verifier. Petzi, Lukas; Ben Yahya, Ala Eddine; Dmitrienko, Alexandra; Tsudik, Gene; Prantl, Thomas; Kounev, Samuel. Vol. USENIX Security ’22. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Remote Attestation (RA) is a basic security mechanism that detects malicious presence on various types of computing components, e.g., IoT devices. In a typical IoT setting, RA involves a trusted Verifier that sends a challenge to an untrusted remote Prover, which must in turn reply with a fresh and authentic evidence of being in a trustworthy state. However,most current RA schemes assume a central Verifier, which rep-resents a single point of failure. This feature is problematic when mutually suspicious stakeholders are involved. Furthermore, scalability issues arise as the number of IoT devices (Provers) grows. Although some RA schemes allow peer Provers to act as Verifiers, they involve unrealistic (for IoT devices) requirements, such as time synchronization and synchronous communication. Moreover, they incur heavy memory, computation,and communication burdens, while not considering sleeping or otherwise disconnected devices. Motivated by the need to address these limitations, we construct Scalable Collective Remote Attestation for Pub-Sub (SCRAPS), a novel collective RA scheme. It achieves scalability by outsourcing Verifier duties to a smart contract and mitigates DoS attacks against both Provers and Verifiers. It also removes the need for synchronous communication. Furthermore,RA evidence in SCRAPS is publicly verifiable, which significantly reduces the number of attestation evidence computations, thus lowering Prover burden. We report on a prototype of SCRAPS over Hyperledger Sawtooth (a blockchain geared for IoT use-cases) and evaluate its performance, scalability, and security aspects.

  @proceedings{petzi2022scraps, abstract = {Remote Attestation (RA) is a basic security mechanism that detects malicious presence on various types of computing components, e.g., IoT devices. In a typical IoT setting, RA involves a trusted Verifier that sends a challenge to an untrusted remote Prover, which must in turn reply with a fresh and authentic evidence of being in a trustworthy state. However,most current RA schemes assume a central Verifier, which rep-resents a single point of failure. This feature is problematic when mutually suspicious stakeholders are involved. Furthermore, scalability issues arise as the number of IoT devices (Provers) grows. Although some RA schemes allow peer Provers to act as Verifiers, they involve unrealistic (for IoT devices) requirements, such as time synchronization and synchronous communication. Moreover, they incur heavy memory, computation,and communication burdens, while not considering sleeping or otherwise disconnected devices. Motivated by the need to address these limitations, we construct Scalable Collective Remote Attestation for Pub-Sub (SCRAPS), a novel collective RA scheme. It achieves scalability by outsourcing Verifier duties to a smart contract and mitigates DoS attacks against both Provers and Verifiers. It also removes the need for synchronous communication. Furthermore,RA evidence in SCRAPS is publicly verifiable, which significantly reduces the number of attestation evidence computations, thus lowering Prover burden. We report on a prototype of SCRAPS over Hyperledger Sawtooth (a blockchain geared for IoT use-cases) and evaluate its performance, scalability, and security aspects.}, author = {Petzi, Lukas and Ben Yahya, Ala Eddine and Dmitrienko, Alexandra and Tsudik, Gene and Prantl, Thomas and Kounev, Samuel}, keywords = {sss-group}, note = {Coming Soon}, title = {SCRAPS: Scalable Collective Remote Attestation for Pub-Sub IoT Networks with Untrusted Proxy Verifier}, volume = {USENIX Security '22}, year = 2022 }
• Artificial Intelligence-Based Early Detection Of Acute Kidney Injury After Cardiac Surgery. Kalisnik, Jurij Matija; Bauer, Andr{é}; Vogt, Ferdinand Aurel; Stickl, Franziska Josephine; Zibert, Janez; Fittkau, Matthias; Bertsch, Thomas; Kounev, Samuel; Fischlein, Theodor. In European Journal of Cardio-Thoracic Surgery. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Objectives: This study aims to improve early detection of cardiac surgery-associated acute kidney injury using artificial intelligence-based algorithms. Methods: Data from consecutive patients undergoing cardiac surgery between 2008 and 2018 in our institution served as the source for artificial intelligence-based modeling. Cardiac surgery-associated acute kidney injury was defined according to the Kidney Disease Improving Global Outcomes criteria. Different machine learning algorithms were trained and validated to detect cardiac surgery-associated acute kidney injury within 12 hours after surgery. Demographic characteristics, comorbidities, preoperative cardiac status, intra- and postoperative variables including creatinine and hemoglobin values were retrieved for analysis. Results: From 7507 patients analyzed, 1699 patients (22.6 %) developed cardiac surgery-associated acute kidney injury. The ultimate detection model, 'Detect-A(K)I', recognizes cardiac surgery-associated acute kidney injury within 12 hours with an area under the curve of 88.0 %, sensitivity of 78.0 %, specificity of 78.9 %, and accuracy of 82.1 %. The optimal parameter set includes serial changes of creatinine and hemoglobin, operative emergency, bleeding-associated variables, cardiac ischemic time and cardiac function-associated variables, age, diuretics and active infection, chronic obstructive lung and peripheral vascular disease. Conclusion: The 'Detect-A(K)I' model successfully detects cardiac surgery-associated acute kidney injury within 12 hours after surgery with the best discriminatory characteristics reported so far.

  @article{kalisnik2022artificial, abstract = {Objectives: This study aims to improve early detection of cardiac surgery-associated acute kidney injury using artificial intelligence-based algorithms. Methods: Data from consecutive patients undergoing cardiac surgery between 2008 and 2018 in our institution served as the source for artificial intelligence-based modeling. Cardiac surgery-associated acute kidney injury was defined according to the Kidney Disease Improving Global Outcomes criteria. Different machine learning algorithms were trained and validated to detect cardiac surgery-associated acute kidney injury within 12 hours after surgery. Demographic characteristics, comorbidities, preoperative cardiac status, intra- and postoperative variables including creatinine and hemoglobin values were retrieved for analysis. Results: From 7507 patients analyzed, 1699 patients (22.6 %) developed cardiac surgery-associated acute kidney injury. The ultimate detection model, 'Detect-A(K)I', recognizes cardiac surgery-associated acute kidney injury within 12 hours with an area under the curve of 88.0 %, sensitivity of 78.0 %, specificity of 78.9 %, and accuracy of 82.1 %. The optimal parameter set includes serial changes of creatinine and hemoglobin, operative emergency, bleeding-associated variables, cardiac ischemic time and cardiac function-associated variables, age, diuretics and active infection, chronic obstructive lung and peripheral vascular disease. Conclusion: The 'Detect-A(K)I' model successfully detects cardiac surgery-associated acute kidney injury within 12 hours after surgery with the best discriminatory characteristics reported so far.}, author = {Kalisnik, Jurij Matija and Bauer, Andr{é} and Vogt, Ferdinand Aurel and Stickl, Franziska Josephine and Zibert, Janez and Fittkau, Matthias and Bertsch, Thomas and Kounev, Samuel and Fischlein, Theodor}, journal = {European Journal of Cardio-Thoracic Surgery}, keywords = {t_journalmagazine}, note = {Joint first authorship; To be published soon}, title = {Artificial Intelligence-Based Early Detection Of Acute Kidney Injury After Cardiac Surgery}, year = 2022 }
• Algorithms for Floor Planning with Proximity Requirements. Klawitter, Jonathan; Klesen, Felix; Wolff, Alexander. In Proc. CAAD Future 2021, Vol. 1465 of CCIS, D. J. Gerber, A. Nahmad, B. Bogosian, E. Pantazis, C. Miltiadis (eds.), pp. 151–171. Springer-Verlag, 2022.
  • [ BibTeX ]
  @inproceedings{kkw-afppr-CAADF21, author = {Klawitter, Jonathan and Klesen, Felix and Wolff, Alexander}, booktitle = {Proc. CAAD Future 2021}, editor = {Gerber, David J. and Nahmad, Alicia and Bogosian, Biayna and Pantazis, Evan and Miltiadis, Constantinos}, keywords = {myown}, pages = {151–171}, publisher = {Springer-Verlag}, series = {CCIS}, title = {Algorithms for Floor Planning with Proximity Requirements}, volume = 1465, year = 2022 }
• Learning Classifier Systems as Recommender Systems. Babu, Sooraj K; von Mammen, Sebastian. In Lifelike Computing Systems Workshop LIFELIKE 2022. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  A multitude of software domains, ranging from e-commerce services to personal digital assistants, rely on recommender systems (RS) to enhance their performance and customer experience. There are several established approaches to RS, including algorithms, namely, collaborative filtering, content based filtering, and various hybrid systems that use different verticals of data, such as the user’s preferences, the metadata of items to be suggested, etc., to generate recommendations. Contrary to those, we adopt a classifier system to benefit from its rule-based knowledge representation and interwoven learning mechanisms. In this paper, we present our approach and elaborate on its potential use to flexibly and effectively guide a user through the application of an authoring platform.

  @inproceedings{babu2022learning, abstract = {A multitude of software domains, ranging from e-commerce services to personal digital assistants, rely on recommender systems (RS) to enhance their performance and customer experience. There are several established approaches to RS, including algorithms, namely, collaborative filtering, content based filtering, and various hybrid systems that use different verticals of data, such as the user’s preferences, the metadata of items to be suggested, etc., to generate recommendations. Contrary to those, we adopt a classifier system to benefit from its rule-based knowledge representation and interwoven learning mechanisms. In this paper, we present our approach and elaborate on its potential use to flexibly and effectively guide a user through the application of an authoring platform.}, author = {Babu, Sooraj K and von Mammen, Sebastian}, booktitle = {Lifelike Computing Systems Workshop LIFELIKE 2022}, keywords = {via-vr}, title = {Learning Classifier Systems as Recommender Systems}, year = 2022 }
• A Multi-Layered User Guidance Framework. Babu, Sooraj K. In Organic Computing Doctoral Dissertation Colloquium (OC-DDC). Kassel University Press, Kassel, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Using a complex software system can pose a difficult challenge for its users, especially for those without technical backgrounds. This paper outlines a concept to deploy Recommender Systems coupled with Intelligent User Interfaces as an effective mechanism to guide a user of a complex software system through context-aware suggestions. More concretely, we focus on an authoring tool that our research draws motivation from and will find opportunities for evaluation---it is a platform that aims at empowering medical professionals to create virtual reality experiences to help their work. This paper elaborates on the envisioned concept and the plan for implementation and evaluation.

  @conference{babu2022multilayered, abstract = {Using a complex software system can pose a difficult challenge for its users, especially for those without technical backgrounds. This paper outlines a concept to deploy Recommender Systems coupled with Intelligent User Interfaces as an effective mechanism to guide a user of a complex software system through context-aware suggestions. More concretely, we focus on an authoring tool that our research draws motivation from and will find opportunities for evaluation—it is a platform that aims at empowering medical professionals to create virtual reality experiences to help their work. This paper elaborates on the envisioned concept and the plan for implementation and evaluation.}, address = {Kassel}, author = {Babu, Sooraj K}, booktitle = {Organic Computing Doctoral Dissertation Colloquium (OC-DDC)}, keywords = {via-vr}, publisher = {Kassel University Press}, title = {A Multi-Layered User Guidance Framework}, year = 2022 }
• Dense Feature Matching based on Homographic Decomposition. Seibt, Simon; von Ramon Lipinski, Bartosz; Latoschik, March Erich. In IEEE Access, X, pp. 1–1. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Finding robust and accurate feature matches is a fundamental problem in computer vision. However, incorrect correspondences and suboptimal matching accuracies lead to significant challenges for many real-world applications. In conventional feature matching, corresponding features in an image pair are greedily searched using their descriptor distance. The resulting matching set is then typically used as input for geometric model fitting methods to find an appropriate fundamental matrix and filter out incorrect matches. Unfortunately, this basic approach cannot solve all practical problems, such as fundamental matrix degeneration, matching ambiguities caused by repeated patterns and rejection of initially mismatched features without further reconsideration. In this paper we introduce a novel matching pipeline, which addresses all of the aforementioned challenges at once: First, we perform iterative rematching to give mismatched feature points a further chance for being considered in later processing steps. Thereby, we are searching for inliers that exhibit the same homographic transformation per iteration. The resulting homographic decomposition is used for refining matches, occlusion detection (e.g. due to parallaxes) and extrapolation of additional features in critical image areas. Furthermore, Delaunay triangulation of the matching set is utilized to minimize the repeated pattern problem and to implement focused matching. Doing so, enables us to further increase matching quality by concentrating on local image areas, defined by the triangular mesh. We present and discuss experimental results with multiple real-world matching datasets. Our contributions, besides improving matching recall and precision for image processing applications in general, also relate to use cases in image-based computer graphics.

  @article{seibt2022dense, abstract = {Finding robust and accurate feature matches is a fundamental problem in computer vision. However, incorrect correspondences and suboptimal matching accuracies lead to significant challenges for many real-world applications. In conventional feature matching, corresponding features in an image pair are greedily searched using their descriptor distance. The resulting matching set is then typically used as input for geometric model fitting methods to find an appropriate fundamental matrix and filter out incorrect matches. Unfortunately, this basic approach cannot solve all practical problems, such as fundamental matrix degeneration, matching ambiguities caused by repeated patterns and rejection of initially mismatched features without further reconsideration. In this paper we introduce a novel matching pipeline, which addresses all of the aforementioned challenges at once: First, we perform iterative rematching to give mismatched feature points a further chance for being considered in later processing steps. Thereby, we are searching for inliers that exhibit the same homographic transformation per iteration. The resulting homographic decomposition is used for refining matches, occlusion detection (e.g. due to parallaxes) and extrapolation of additional features in critical image areas. Furthermore, Delaunay triangulation of the matching set is utilized to minimize the repeated pattern problem and to implement focused matching. Doing so, enables us to further increase matching quality by concentrating on local image areas, defined by the triangular mesh. We present and discuss experimental results with multiple real-world matching datasets. Our contributions, besides improving matching recall and precision for image processing applications in general, also relate to use cases in image-based computer graphics.}, author = {Seibt, Simon and von Ramon Lipinski, Bartosz and Latoschik, March Erich}, journal = {IEEE Access}, keywords = {latoschik}, pages = {1-1}, title = {Dense Feature Matching based on Homographic Decomposition}, volume = {X}, year = 2022 }
• Same, Same, but Dissimilar: Exploring Measurements for Workload Time-Series Similarity. Leznik, Mark; Grohmann, Johannes; Kliche, Nina; Bauer, Andr{é}; Seybold, Daniel; Eismann, Simon; Kounev, Samuel; Domaschka, J{ö}rg. In Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering, of ICPE ’22, pp. 89–96. Association for Computing Machinery, New York, NY, USA, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Benchmarking is a core element in the toolbox of most systems researchers and is used for analyzing, comparing, and validating complex systems. In the quest for reliable benchmark results, a consensus has formed that a significant experiment must be based on multiple runs. To interpret these runs, mean and standard deviation are often used. In case of experiments where each run produces a time series, applying and comparing the mean is not easily applicable and not necessarily statistically sound. Such an approach ignores the possibility of significant differences between runs with a similar average. In order to verify this hypothesis, we conducted a survey of 1,112 publications of selected performance engineering and systems conferences canvassing open data sets from performance experiments. The identified 3 data sets purely rely on average and standard deviation. Therefore, we propose a novel analysis approach based on similarity analysis to enhance the reliability of performance evaluations. Our approach evaluates 12 (dis-)similarity measures with respect to their applicability in analysing performance measurements and identifies four suitable similarity measures. We validate our approach by demonstrating the increase in reliability for the data sets found in the survey.

  @inproceedings{leznik2022dissimilar, abstract = {Benchmarking is a core element in the toolbox of most systems researchers and is used for analyzing, comparing, and validating complex systems. In the quest for reliable benchmark results, a consensus has formed that a significant experiment must be based on multiple runs. To interpret these runs, mean and standard deviation are often used. In case of experiments where each run produces a time series, applying and comparing the mean is not easily applicable and not necessarily statistically sound. Such an approach ignores the possibility of significant differences between runs with a similar average. In order to verify this hypothesis, we conducted a survey of 1,112 publications of selected performance engineering and systems conferences canvassing open data sets from performance experiments. The identified 3 data sets purely rely on average and standard deviation. Therefore, we propose a novel analysis approach based on similarity analysis to enhance the reliability of performance evaluations. Our approach evaluates 12 (dis-)similarity measures with respect to their applicability in analysing performance measurements and identifies four suitable similarity measures. We validate our approach by demonstrating the increase in reliability for the data sets found in the survey.}, address = {New York, NY, USA}, author = {Leznik, Mark and Grohmann, Johannes and Kliche, Nina and Bauer, Andr\'{e} and Seybold, Daniel and Eismann, Simon and Kounev, Samuel and Domaschka, J\"{o}rg}, booktitle = {Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering}, keywords = {analysis}, pages = {89–96}, publisher = {Association for Computing Machinery}, series = {ICPE '22}, title = {Same, Same, but Dissimilar: Exploring Measurements for Workload Time-Series Similarity}, year = 2022 }
• Digitale Leseförderung: Effekte eines silbenbasierten digitalen Lesetrainings in Klasse 2. Heß, J.; Karageorgos, P.; Richter, T.; Müller, B.; Riedmann, A.; Schaper, P.; Lugrin, B. In Vortrag auf dem 52. Kongress der Deutschen Gesellschaft für Psychologie (DGPs). 2022.
  • [ BibTeX ]
  @conference{hess2022digitale, author = {Heß, J. and Karageorgos, P. and Richter, T. and Müller, B. and Riedmann, A. and Schaper, P. and Lugrin, B.}, booktitle = {Vortrag auf dem 52. Kongress der Deutschen Gesellschaft für Psychologie (DGPs)}, keywords = {mi}, title = {Digitale Leseförderung: Effekte eines silbenbasierten digitalen Lesetrainings in Klasse 2}, year = 2022 }
• Inter- and Transcultural Learning in Social Virtual Reality: A Proposal for an Inter- and Transcultural Virtual Object Database to be Used in the Implementation, Reflection, and Evaluation of Virtual Encounters. Hein, Rebecca M.; Latoschik, Marc Erich; Wienrich, Carolin. In Multimodal Technologies and Interaction, 6(7), F. L. {Mark Billinghurst; M.-C. Su (eds.), p. 50. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Visual stimuli are frequently used to improve memory, language learning or perception, and understanding of metacognitive processes. However, in virtual reality (VR), there are few systematically and empirically derived databases. This paper proposes the first collection of virtual objects based on empirical evaluation for inter-and transcultural encounters between English- and German-speaking learners. We used explicit and implicit measurement methods to identify cultural associations and the degree of stereotypical perception for each virtual stimuli (n = 293) through two online studies, including native German and English-speaking participants. The analysis resulted in a final well-describable database of 128 objects (called InteractionSuitcase). In future applications, the objects can be used as a great interaction or conversation asset and behavioral measurement tool in social VR applications, especially in the field of foreign language education. For example, encounters can use the objects to describe their culture, or teachers can intuitively assess stereotyped attitudes of the encounters.

  @article{mti6070050, abstract = {Visual stimuli are frequently used to improve memory, language learning or perception, and understanding of metacognitive processes. However, in virtual reality (VR), there are few systematically and empirically derived databases. This paper proposes the first collection of virtual objects based on empirical evaluation for inter-and transcultural encounters between English- and German-speaking learners. We used explicit and implicit measurement methods to identify cultural associations and the degree of stereotypical perception for each virtual stimuli (n = 293) through two online studies, including native German and English-speaking participants. The analysis resulted in a final well-describable database of 128 objects (called InteractionSuitcase). In future applications, the objects can be used as a great interaction or conversation asset and behavioral measurement tool in social VR applications, especially in the field of foreign language education. For example, encounters can use the objects to describe their culture, or teachers can intuitively assess stereotyped attitudes of the encounters.}, author = {Hein, Rebecca M. and Latoschik, Marc Erich and Wienrich, Carolin}, editor = {{Mark Billinghurst, Fotis Liarokapis}, Lars Erik Holmquist and Su, Mu-Chun}, journal = {Multimodal Technologies and Interaction}, keywords = {coteach}, number = 7, pages = 50, title = {Inter- and Transcultural Learning in Social Virtual Reality: A Proposal for an Inter- and Transcultural Virtual Object Database to be Used in the Implementation, Reflection, and Evaluation of Virtual Encounters}, volume = 6, year = 2022 }
• Towards a Cryptography Benchmark: A View on Attribute Based Encryption Schemes. Prantl, Thomas; Zeck, Timo; Iffländer, Lukas; Beierlieb, Lukas; Dmitrenko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In 2022 5th Conference on Cloud and Internet of Things (CIoT). IEEE, 2022.
  • [ BibTeX ]
  @inproceedings{PrZeIfBeDmKrKo2022-CIoT-ABEBenchmark, author = {Prantl, Thomas and Zeck, Timo and Iffländer, Lukas and Beierlieb, Lukas and Dmitrenko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, booktitle = {2022 5th Conference on Cloud and Internet of Things (CIoT)}, keywords = {descartes}, organization = {IEEE}, title = {Towards a Cryptography Benchmark: A View on Attribute Based Encryption Schemes}, year = 2022 }
• Ein 4D-Browser für historische Fotografien – Forschungspotenziale für die Kunstgeschichte. Das Projekt HistStadt4D. Bruschke, Jonas; Kröber, Cindy; Niebling, Florian. In Landes- und Regionalgeschichte digital, M. Munke (ed.), pp. 106–114. Thelem, Dresden und München, 2022.
  • [ BibTeX ]
  @inbook{bruschke20224dbrowser, address = {Dresden und München}, author = {Bruschke, Jonas and Kröber, Cindy and Niebling, Florian}, booktitle = {Landes- und Regionalgeschichte digital}, editor = {Munke, Martin}, keywords = {histstadt4d}, pages = {106-114}, publisher = {Thelem}, title = {Ein 4D-Browser für historische Fotografien – Forschungspotenziale für die Kunstgeschichte. Das Projekt HistStadt4D}, type = {Book Section}, year = 2022 }
• Second Language Learning through Storytelling with a Social Robot-An Online Case Study. Steinhaeusser, Sophia C.; Riedmann, Anna; Schaper, Philipp; Guthmann, Emily; Pfister, Julia; Schmitt, Katharina; Wild, Theresa; Lugrin, Birgit. In 2022 31st IEEE International Conference on Robot and Human Interactive Communication (RO-MAN), pp. 67–74. IEEE, 2022.
  • [ BibTeX ]
  @inproceedings{steinhaeusser2022second, author = {Steinhaeusser, Sophia C. and Riedmann, Anna and Schaper, Philipp and Guthmann, Emily and Pfister, Julia and Schmitt, Katharina and Wild, Theresa and Lugrin, Birgit}, booktitle = {2022 31st IEEE International Conference on Robot and Human Interactive Communication (RO-MAN)}, keywords = {steinhaeusser}, organization = {IEEE}, pages = {67-74}, title = {Second Language Learning through Storytelling with a Social Robot-An Online Case Study}, year = 2022 }
• Iteratively Digitizing an Analogue Syllable-Based Reading Intervention. Riedmann, Anna; Schaper, Philipp; Donnermann, Melissa; Lein, Martina; Steinhaeusser, Sophia C.; Karageorgos, Panagiotis; Müller, Bettina; Richter, Tobias; Lugrin, Birgit. In Interacting with Computers. Oxford University Press, 2022.
  • [ BibTeX ]
  @article{2022, author = {Riedmann, Anna and Schaper, Philipp and Donnermann, Melissa and Lein, Martina and Steinhaeusser, Sophia C. and Karageorgos, Panagiotis and Müller, Bettina and Richter, Tobias and Lugrin, Birgit}, journal = {Interacting with Computers}, keywords = {lein}, publisher = {Oxford University Press}, title = {Iteratively Digitizing an Analogue Syllable-Based Reading Intervention}, year = 2022 }
• Virtual Human Coherence and Plausibility – Towards a Validated Scale. Mal, David; Wolf, Erik; Döllinger, Nina; Botsch, Mario; Wienrich, Carolin; Latoschik, Marc Erich. In 2022 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW), pp. 788–789. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Virtual humans contribute to users’ state of plausibility in various XR applications. We present the development and preliminary evaluation of a self-assessment questionnaire to quantify virtual human’s plausibility in virtual environments based on eleven concise items. A principal component analysis of 650 appraisals collected in an online survey revealed two highly reliable components within the items. We interpret the components as possible factors, i.e., appearance and behavior plausibility and match to the virtual environment, and propose future work aiming towards a standardized virtual human plausibility scale by validating the structure and sensitivity of both sub-components in XR environments.

  @inproceedings{mal2022virtual, abstract = {Virtual humans contribute to users’ state of plausibility in various XR applications. We present the development and preliminary evaluation of a self-assessment questionnaire to quantify virtual human’s plausibility in virtual environments based on eleven concise items. A principal component analysis of 650 appraisals collected in an online survey revealed two highly reliable components within the items. We interpret the components as possible factors, i.e., appearance and behavior plausibility and match to the virtual environment, and propose future work aiming towards a standardized virtual human plausibility scale by validating the structure and sensitivity of both sub-components in XR environments.}, author = {Mal, David and Wolf, Erik and Döllinger, Nina and Botsch, Mario and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {2022 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {dmal}, pages = {788-789}, title = {Virtual Human Coherence and Plausibility – Towards a Validated Scale}, year = 2022 }
• Resize Me! Exploring the User Experience of Embodied Realistic Modulatable Avatars for Body Image Intervention in Virtual Reality. Döllinger, Nina; Wolf, Erik; Mal, David; Wenninger, Stephan; Botsch, Mario; Latoschik, Marc Erich; Wienrich, Carolin. In Frontiers in Virtual Reality, 3. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Obesity is a serious disease that can affect both physical and psychological well-being. Due to weight stigmatization, many affected individuals suffer from body image disturbances whereby they perceive their body in a distorted way, evaluate it negatively, or neglect it. Beyond established interventions such as mirror exposure, recent advancements aim to complement body image treatments by the embodiment of visually altered virtual bodies in virtual reality (VR). We present a high-fidelity prototype of an advanced VR system that allows users to embody a rapidly generated personalized, photorealistic avatar and to realistically modulate its body weight in real-time within a carefully designed virtual environment. In a formative multi-method approach, a total of 12 participants rated the general user experience (UX) of our system during body scan and VR experience using semi-structured qualitative interviews and multiple quantitative UX measures. Using body weight modification tasks, we further compared three different interaction methods for real-time body weight modification and measured our system’s impact on the body image relevant measures body awareness and body weight perception. From the feedback received, demonstrating an already solid UX of our overall system and providing constructive input for further improvement, we derived a set of design guidelines to guide future development and evaluation processes of systems supporting body image interventions.

  @article{dollinger2022resizeme, abstract = {Obesity is a serious disease that can affect both physical and psychological well-being. Due to weight stigmatization, many affected individuals suffer from body image disturbances whereby they perceive their body in a distorted way, evaluate it negatively, or neglect it. Beyond established interventions such as mirror exposure, recent advancements aim to complement body image treatments by the embodiment of visually altered virtual bodies in virtual reality (VR). We present a high-fidelity prototype of an advanced VR system that allows users to embody a rapidly generated personalized, photorealistic avatar and to realistically modulate its body weight in real-time within a carefully designed virtual environment. In a formative multi-method approach, a total of 12 participants rated the general user experience (UX) of our system during body scan and VR experience using semi-structured qualitative interviews and multiple quantitative UX measures. Using body weight modification tasks, we further compared three different interaction methods for real-time body weight modification and measured our system’s impact on the body image relevant measures body awareness and body weight perception. From the feedback received, demonstrating an already solid UX of our overall system and providing constructive input for further improvement, we derived a set of design guidelines to guide future development and evaluation processes of systems supporting body image interventions.}, author = {Döllinger, Nina and Wolf, Erik and Mal, David and Wenninger, Stephan and Botsch, Mario and Latoschik, Marc Erich and Wienrich, Carolin}, journal = {Frontiers in Virtual Reality}, keywords = {dmal}, title = {Resize Me! Exploring the User Experience of Embodied Realistic Modulatable Avatars for Body Image Intervention in Virtual Reality}, volume = 3, year = 2022 }
• An Experience Report on the Suitability of a Distributed Group Encryption Scheme for an IoT Use Case. Prantl, Thomas; Engel, Simon; Bauer, Andre; Ben Yahya, Ala Eddine; Herrnleben, Stefan; Iffländer, Lukas; Dmitrienko, Alexandra; Kounev, Samuel. In 2022 IEEE 95th Vehicular Technology Conference (VTC2022). IEEE, 2022.
  • [ BibTeX ]
  @inproceedings{PrEnBaAlHeIfDmKo2022-IoT/CPS-DistributedGroupEncryption, author = {Prantl, Thomas and Engel, Simon and Bauer, Andre and Ben Yahya, Ala Eddine and Herrnleben, Stefan and Iffländer, Lukas and Dmitrienko, Alexandra and Kounev, Samuel}, booktitle = {2022 IEEE 95th Vehicular Technology Conference (VTC2022)}, keywords = {t_workshop}, organization = {IEEE}, title = {An Experience Report on the Suitability of a Distributed Group Encryption Scheme for an IoT Use Case}, year = 2022 }
• FADE: Towards Flexible and Adaptive Distance Estimation Considering Obstacles. Hadry, Marius; Lesch, Veronika; Kounev, Samuel. In Companion of the 13th ACM/SPEC International Conference on Performance Engineering (ICPE 2022). ACM, 2022.
  • [ BibTeX ]
  @inproceedings{hadry2022towards, author = {Hadry, Marius and Lesch, Veronika and Kounev, Samuel}, booktitle = {Companion of the 13th ACM/SPEC International Conference on Performance Engineering (ICPE 2022)}, keywords = {cyber-physical_systems}, month = {04}, publisher = {ACM}, title = {FADE: Towards Flexible and Adaptive Distance Estimation Considering Obstacles}, year = 2022 }
• A Survey on Secure Group Communication Schemes with Focus on IoT Communication. Prantl, Thomas; Zeck, Timo; Bauer, André; Ten, Peter; Prantl, Dominik; Ben Yahya, Ala Eddine; Iffländer, Lukas; Dmitrienko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In IEEE Access. IEEE, 2022.
  • [ BibTeX ]
  @article{PrZeBaTePrYaIfDmKrKo_IEEEAccess_SGCSurvey, author = {Prantl, Thomas and Zeck, Timo and Bauer, André and Ten, Peter and Prantl, Dominik and Ben Yahya, Ala Eddine and Iffländer, Lukas and Dmitrienko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, journal = {IEEE Access}, keywords = {t_journalmagazine}, publisher = {IEEE}, title = {A Survey on Secure Group Communication Schemes with Focus on IoT Communication}, year = 2022 }
• SCRAPS: Scalable Collective Remote Attestation for Pub-Sub IoT Networks with Untrusted Proxy Verifier. Petzi, Lukas; Ben Yahya, Ala Eddine; Dmitrienko, Alexandra; Tsudik, Gene; Prantl, Thomas; Kounev, Samuel. Vol. USENIX Security ’22. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Remote Attestation (RA) is a basic security mechanism that detects malicious presence on various types of computing components, e.g., IoT devices. In a typical IoT setting, RA involves a trusted Verifier that sends a challenge to an untrusted remote Prover, which must in turn reply with a fresh and authentic evidence of being in a trustworthy state. However,most current RA schemes assume a central Verifier, which rep-resents a single point of failure. This feature is problematic when mutually suspicious stakeholders are involved. Furthermore, scalability issues arise as the number of IoT devices (Provers) grows. Although some RA schemes allow peer Provers to act as Verifiers, they involve unrealistic (for IoT devices) requirements, such as time synchronization and synchronous communication. Moreover, they incur heavy memory, computation,and communication burdens, while not considering sleeping or otherwise disconnected devices. Motivated by the need to address these limitations, we construct Scalable Collective Remote Attestation for Pub-Sub (SCRAPS), a novel collective RA scheme. It achieves scalability by outsourcing Verifier duties to a smart contract and mitigates DoS attacks against both Provers and Verifiers. It also removes the need for synchronous communication. Furthermore,RA evidence in SCRAPS is publicly verifiable, which significantly reduces the number of attestation evidence computations, thus lowering Prover burden. We report on a prototype of SCRAPS over Hyperledger Sawtooth (a blockchain geared for IoT use-cases) and evaluate its performance, scalability, and security aspects.

  @proceedings{petzi2022scraps, abstract = {Remote Attestation (RA) is a basic security mechanism that detects malicious presence on various types of computing components, e.g., IoT devices. In a typical IoT setting, RA involves a trusted Verifier that sends a challenge to an untrusted remote Prover, which must in turn reply with a fresh and authentic evidence of being in a trustworthy state. However,most current RA schemes assume a central Verifier, which rep-resents a single point of failure. This feature is problematic when mutually suspicious stakeholders are involved. Furthermore, scalability issues arise as the number of IoT devices (Provers) grows. Although some RA schemes allow peer Provers to act as Verifiers, they involve unrealistic (for IoT devices) requirements, such as time synchronization and synchronous communication. Moreover, they incur heavy memory, computation,and communication burdens, while not considering sleeping or otherwise disconnected devices. Motivated by the need to address these limitations, we construct Scalable Collective Remote Attestation for Pub-Sub (SCRAPS), a novel collective RA scheme. It achieves scalability by outsourcing Verifier duties to a smart contract and mitigates DoS attacks against both Provers and Verifiers. It also removes the need for synchronous communication. Furthermore,RA evidence in SCRAPS is publicly verifiable, which significantly reduces the number of attestation evidence computations, thus lowering Prover burden. We report on a prototype of SCRAPS over Hyperledger Sawtooth (a blockchain geared for IoT use-cases) and evaluate its performance, scalability, and security aspects.}, author = {Petzi, Lukas and Ben Yahya, Ala Eddine and Dmitrienko, Alexandra and Tsudik, Gene and Prantl, Thomas and Kounev, Samuel}, keywords = {sss-group}, note = {Coming Soon}, title = {SCRAPS: Scalable Collective Remote Attestation for Pub-Sub IoT Networks with Untrusted Proxy Verifier}, volume = {USENIX Security '22}, year = 2022 }
• Are You Referring to Me? - Giving Virtual Objects Awareness. Stingl, René; Zimmerer, Chris; Fischbach, Martin; Latoschik, Marc Erich. In 2022 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct), pp. 671–673. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This work introduces an interaction technique to determine the user’s non-verbal deixis in Virtual Reality (VR) applications. We tailored it for multimodal speech & gesture interfaces (MMIs). Here, non-verbal deixis is often determined by the use of ray-casting due to its simplicity and intuitiveness. However, ray-casting’s rigidness and dichotomous nature pose limitations concerning the MMI’s flexibility and efficiency. In contrast, our technique considers a more comprehensive set of directional cues to determine non-verbal deixis and provides probabilistic output to tackle these limitations. We present a machine-learning-based reference implementation of our technique in VR and the results of a first performance benchmark. Future work includes an in-depth user study evaluating our technique’s user experience in an MMI.

  @inproceedings{9974498, abstract = {This work introduces an interaction technique to determine the user’s non-verbal deixis in Virtual Reality (VR) applications. We tailored it for multimodal speech & gesture interfaces (MMIs). Here, non-verbal deixis is often determined by the use of ray-casting due to its simplicity and intuitiveness. However, ray-casting’s rigidness and dichotomous nature pose limitations concerning the MMI’s flexibility and efficiency. In contrast, our technique considers a more comprehensive set of directional cues to determine non-verbal deixis and provides probabilistic output to tackle these limitations. We present a machine-learning-based reference implementation of our technique in VR and the results of a first performance benchmark. Future work includes an in-depth user study evaluating our technique’s user experience in an MMI.}, author = {Stingl, René and Zimmerer, Chris and Fischbach, Martin and Latoschik, Marc Erich}, booktitle = {2022 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct)}, keywords = {mmi}, pages = {671-673}, title = {Are You Referring to Me? - Giving Virtual Objects Awareness}, year = 2022 }
• Same, Same, but Dissimilar: Exploring Measurements for Workload Time-Series Similarity. Leznik, Mark; Grohmann, Johannes; Kliche, Nina; Bauer, Andr{é}; Seybold, Daniel; Eismann, Simon; Kounev, Samuel; Domaschka, J{ö}rg. In Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering, of ICPE ’22, pp. 89–96. Association for Computing Machinery, New York, NY, USA, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Benchmarking is a core element in the toolbox of most systems researchers and is used for analyzing, comparing, and validating complex systems. In the quest for reliable benchmark results, a consensus has formed that a significant experiment must be based on multiple runs. To interpret these runs, mean and standard deviation are often used. In case of experiments where each run produces a time series, applying and comparing the mean is not easily applicable and not necessarily statistically sound. Such an approach ignores the possibility of significant differences between runs with a similar average. In order to verify this hypothesis, we conducted a survey of 1,112 publications of selected performance engineering and systems conferences canvassing open data sets from performance experiments. The identified 3 data sets purely rely on average and standard deviation. Therefore, we propose a novel analysis approach based on similarity analysis to enhance the reliability of performance evaluations. Our approach evaluates 12 (dis-)similarity measures with respect to their applicability in analysing performance measurements and identifies four suitable similarity measures. We validate our approach by demonstrating the increase in reliability for the data sets found in the survey.

  @inproceedings{leznik2022dissimilar, abstract = {Benchmarking is a core element in the toolbox of most systems researchers and is used for analyzing, comparing, and validating complex systems. In the quest for reliable benchmark results, a consensus has formed that a significant experiment must be based on multiple runs. To interpret these runs, mean and standard deviation are often used. In case of experiments where each run produces a time series, applying and comparing the mean is not easily applicable and not necessarily statistically sound. Such an approach ignores the possibility of significant differences between runs with a similar average. In order to verify this hypothesis, we conducted a survey of 1,112 publications of selected performance engineering and systems conferences canvassing open data sets from performance experiments. The identified 3 data sets purely rely on average and standard deviation. Therefore, we propose a novel analysis approach based on similarity analysis to enhance the reliability of performance evaluations. Our approach evaluates 12 (dis-)similarity measures with respect to their applicability in analysing performance measurements and identifies four suitable similarity measures. We validate our approach by demonstrating the increase in reliability for the data sets found in the survey.}, address = {New York, NY, USA}, author = {Leznik, Mark and Grohmann, Johannes and Kliche, Nina and Bauer, Andr\'{e} and Seybold, Daniel and Eismann, Simon and Kounev, Samuel and Domaschka, J\"{o}rg}, booktitle = {Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering}, keywords = {analysis}, pages = {89–96}, publisher = {Association for Computing Machinery}, series = {ICPE '22}, title = {Same, Same, but Dissimilar: Exploring Measurements for Workload Time-Series Similarity}, year = 2022 }
• Anonymized GTP Tunnel Trace in Mobile IoT. Raffeck, Simon; Geißler, Stefan; Krolikowski, Michael; Gebert, Steffen; Hoßfeld, Tobias. 2022, February.
  • [ Abstract ]
  • [ BibTeX ]
  Extensive dataset containing one whole month of create and delete events as well as the total, received, and transmitted volume of devices. We obtained data tunnel related events and volume values over 30 days in October 2021. In total the dataset contains a sample of 500000 unique devices that generate 155 million individual data tunnels.

  @misc{info3-misc-2022-1, abstract = {Extensive dataset containing one whole month of create and delete events as well as the total, received, and transmitted volume of devices. We obtained data tunnel related events and volume values over 30 days in October 2021. In total the dataset contains a sample of 500000 unique devices that generate 155 million individual data tunnels.}, author = {Raffeck, Simon and Geißler, Stefan and Krolikowski, Michael and Gebert, Steffen and Hoßfeld, Tobias}, howpublished = {https://zenodo.org/record/6045708}, keywords = {can}, month = {02}, title = {Anonymized GTP Tunnel Trace in Mobile IoT}, year = 2022 }
• Automated Triage of Performance Change Points Using Time Series Analysis and Machine Learning. Bauer, André; Straesser, Martin; Beierlieb, Lukas; Meissner, Maximilian; Kounev, Samuel. In Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering. ACM, 2022.
  • [ BibTeX ]
  @conference{bauer2022automated, author = {Bauer, André and Straesser, Martin and Beierlieb, Lukas and Meissner, Maximilian and Kounev, Samuel}, booktitle = {Proceedings of the 2022 ACM/SPEC on International Conference on Performance Engineering}, keywords = {machine_learning}, month = {04}, publisher = {ACM}, title = {Automated Triage of Performance Change Points Using Time Series Analysis and Machine Learning}, year = 2022 }
• Simulative Performance Study of Slotted Aloha for LoRaWAN Channel Access. Loh, Frank; Mehling, Noah; Geißler, Stefan; Hoßfeld, Tobias. In IEEE/IFIP Network Operations and Management Symposium. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  Future Internet of Things deployments generate a multitude of new challenges and opportunities. While 5G networks promise massive throughput rates with ultra low delays, many verticals in the areas of Industry 4.0, Smart City, or Smart Agriculture only transmit tiny amounts of data and instead demand high energy efficiency. This is addressed by access technologies like Low Power Wide Area Networks being com- plementary to high performance 5G networks. Especially Long Range Wide Area Network (LoRaWAN) promises transmissions across long distances with low energy requirements with the drawback of unreliable transmission due to potential message collisions through random channel access. For that reason, a broad parameter study simulation for LoRaWAN channel access with slotted Aloha is presented for real world scenarios and influences like clock drifts or cross traffic. The key impact factors of this channel access approach are studied with focus on the collision probability in various scenarios and simulation results are compared to the current state of the art. The contribution of this work are guidelines for parameter settings in a LoRaWAN with slotted Aloha channel access and performance comparisons for different settings. This information is crucial to scale and operate future LoRaWANs.

  @inproceedings{info3-article-2022-13, abstract = {Future Internet of Things deployments generate a multitude of new challenges and opportunities. While 5G networks promise massive throughput rates with ultra low delays, many verticals in the areas of Industry 4.0, Smart City, or Smart Agriculture only transmit tiny amounts of data and instead demand high energy efficiency. This is addressed by access technologies like Low Power Wide Area Networks being com- plementary to high performance 5G networks. Especially Long Range Wide Area Network (LoRaWAN) promises transmissions across long distances with low energy requirements with the drawback of unreliable transmission due to potential message collisions through random channel access. For that reason, a broad parameter study simulation for LoRaWAN channel access with slotted Aloha is presented for real world scenarios and influences like clock drifts or cross traffic. The key impact factors of this channel access approach are studied with focus on the collision probability in various scenarios and simulation results are compared to the current state of the art. The contribution of this work are guidelines for parameter settings in a LoRaWAN with slotted Aloha channel access and performance comparisons for different settings. This information is crucial to scale and operate future LoRaWANs.}, author = {Loh, Frank and Mehling, Noah and Geißler, Stefan and Hoßfeld, Tobias}, booktitle = {IEEE/IFIP Network Operations and Management Symposium}, keywords = {can}, month = {04}, title = {Simulative Performance Study of Slotted Aloha for LoRaWAN Channel Access}, year = 2022 }
• A Survey on Secure Group Communication Schemes with Focus on IoT Communication. Prantl, Thomas; Zeck, Timo; Bauer, André; Ten, Peter; Prantl, Dominik; Ben Yahya, Ala Eddine; Iffländer, Lukas; Dmitrienko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In IEEE Access. IEEE, 2022.
  • [ BibTeX ]
  @article{PrZeBaTePrYaIfDmKrKo_IEEEAccess_SGCSurvey, author = {Prantl, Thomas and Zeck, Timo and Bauer, André and Ten, Peter and Prantl, Dominik and Ben Yahya, Ala Eddine and Iffländer, Lukas and Dmitrienko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, journal = {IEEE Access}, keywords = {t_journalmagazine}, publisher = {IEEE}, title = {A Survey on Secure Group Communication Schemes with Focus on IoT Communication}, year = 2022 }
• SPEC Research Group Newsletter, Issue 11. Kounev, Samuel; van Hoorn, Andre; Straesser, Martin; Bauer, Andr{é}. 2022, April.
  • [ BibTeX ]
  @misc{SPEC-RG-NEWSLETTER-11, author = {Kounev, Samuel and van Hoorn, Andre and Straesser, Martin and Bauer, Andr{é}}, keywords = {SPEC}, month = {04}, note = {Published by Standard Performance Evaluation Corporation (SPEC)}, title = {SPEC Research Group Newsletter, Issue 11}, year = 2022 }
• FADE: Towards Flexible and Adaptive Distance Estimation Considering Obstacles. Hadry, Marius; Lesch, Veronika; Kounev, Samuel. In Companion of the 13th ACM/SPEC International Conference on Performance Engineering (ICPE 2022). ACM, 2022.
  • [ BibTeX ]
  @inproceedings{hadry2022towards, author = {Hadry, Marius and Lesch, Veronika and Kounev, Samuel}, booktitle = {Companion of the 13th ACM/SPEC International Conference on Performance Engineering (ICPE 2022)}, keywords = {cyber-physical_systems}, month = {04}, publisher = {ACM}, title = {FADE: Towards Flexible and Adaptive Distance Estimation Considering Obstacles}, year = 2022 }
• SPEC Efficiency Benchmark Development: How to Contribute to the Future of Energy Conservation. Meissner, Maximilian; Lange, Klaus-Dieter; Arnold, Jeremy; Sharma, Sanjay; Tipley, Roger; Rawtani, Nishant; Reiner, David; Petrich, Mike; Cragin, Aaron. In Companion of the 2022 ACM/SPEC International Conference on Performance Engineering. ACM, New York, NY, USA, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  A driving force behind the improvement of server efficiency in recent years is the use of SPEC benchmarks. They are used in mandatory government regulations, the ISO/IEC 21836:2020 standard, and product marketing, giving server manufacturers and buyers significant incentive to improve energy efficiency. To produce relevant results, benchmarks need to take into account future trends in hardware and software development, such as the introduction of new accelerators and workloads. To keep pace with the development of the fast moving IT landscape, SPEC plans to introduce a workload bounty program to encourage researchers to develop novel workloads. Submitted workloads will be considered for inclusion in future SPEC Efficiency benchmarks and rewarded. In this paper, we outline the process of energy-efficiency benchmark development. SPEC ensures the development of high-quality benchmarks for government regulations through its extensive experience and collaboration with stakeholders from industry, academia, and governments. One of the tools that emerged from this process is the Chauffeur Worklet Development Kit (WDK), which can be used by researchers to develop next-generation workloads to enhance the real-world relevance of future SPEC benchmarks, a critical element for the benchmarks to contribute to future energy conservation.

  @inproceedings{meissner2022efficiency, abstract = {A driving force behind the improvement of server efficiency in recent years is the use of SPEC benchmarks. They are used in mandatory government regulations, the ISO/IEC 21836:2020 standard, and product marketing, giving server manufacturers and buyers significant incentive to improve energy efficiency. To produce relevant results, benchmarks need to take into account future trends in hardware and software development, such as the introduction of new accelerators and workloads. To keep pace with the development of the fast moving IT landscape, SPEC plans to introduce a workload bounty program to encourage researchers to develop novel workloads. Submitted workloads will be considered for inclusion in future SPEC Efficiency benchmarks and rewarded. In this paper, we outline the process of energy-efficiency benchmark development. SPEC ensures the development of high-quality benchmarks for government regulations through its extensive experience and collaboration with stakeholders from industry, academia, and governments. One of the tools that emerged from this process is the Chauffeur Worklet Development Kit (WDK), which can be used by researchers to develop next-generation workloads to enhance the real-world relevance of future SPEC benchmarks, a critical element for the benchmarks to contribute to future energy conservation.}, address = {New York, NY, USA}, author = {Meissner, Maximilian and Lange, Klaus-Dieter and Arnold, Jeremy and Sharma, Sanjay and Tipley, Roger and Rawtani, Nishant and Reiner, David and Petrich, Mike and Cragin, Aaron}, booktitle = {Companion of the 2022 ACM/SPEC International Conference on Performance Engineering}, keywords = {spec}, month = {04}, publisher = {ACM}, title = {SPEC Efficiency Benchmark Development: How to Contribute to the Future of Energy Conservation}, year = 2022 }
• ML-based Performance Prediction of SDN using Simulated Data from Real and Synthetic Networks. Dietz, Katharina; Gray, Nicholas; Seufert, Michael; Hoßfeld, Tobias. In 33th IEEE/IFIP Network Operations and Management Symposium (NOMS). Budapest, Hungary, 2022.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2022-2, address = {Budapest, Hungary}, author = {Dietz, Katharina and Gray, Nicholas and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {33th IEEE/IFIP Network Operations and Management Symposium (NOMS)}, keywords = {ucn}, month = {04}, title = {ML-based Performance Prediction of SDN using Simulated Data from Real and Synthetic Networks}, year = 2022 }
• Experience and Guidelines for Sorting Algorithm Choices and Their Energy Efficiency. Meissner, Maximilian; Kamthania, Supriya; Rawtani, Nishant; Bucek, James; Lange, Klaus-Dieter; Kounev, Samuel. In Companion of the 2022 ACM/SPEC International Conference on Performance Engineering. ACM, New York, NY, USA, 2022.
  • [ BibTeX ]
  @inproceedings{meissner2022experience, address = {New York, NY, USA}, author = {Meissner, Maximilian and Kamthania, Supriya and Rawtani, Nishant and Bucek, James and Lange, Klaus-Dieter and Kounev, Samuel}, booktitle = {Companion of the 2022 ACM/SPEC International Conference on Performance Engineering}, keywords = {t_workshop}, month = {04}, publisher = {ACM}, title = {Experience and Guidelines for Sorting Algorithm Choices and Their Energy Efficiency}, year = 2022 }
• Breaking Plausibility Without Breaking Presence - Evidence For The Multi-Layer Nature Of Plausibility. Brübach, Larissa; Westermeier, Franziska; Wienrich, Carolin; Latoschik, Marc Erich. In IEEE Transactions on Visualization and Computer Graphics, 28(5), pp. 2267–2276. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  A novel theoretical model recently introduced coherence and plausibility as the essential conditions of XR experiences, challenging contemporary presence-oriented concepts. This article reports on two experiments validating this model, which assumes coherence activation on three layers (cognition, perception, and sensation) as the potential sources leading to a condition of plausibility and from there to other XR qualia such as presence or body ownership. The experiments introduce and utilize breaks in plausibility (in analogy to breaks in presence): We induce incoherence on the perceptual and the cognitive layer simultaneously by a simulation of object behaviors that do not conform to the laws of physics, i.e., gravity. We show that this manipulation breaks plausibility and hence confirm that it results in the desired effects in the theorized condition space but that the breaks in plausibility did not affect presence. In addition, we show that a cognitive manipulation by a storyline framing is too weak to successfully counteract the strong bottom-up inconsistencies. Both results are in line with the predictions of the recently introduced three-layer model of coherence and plausibility, which incorporates well-known top-down and bottom-up rivalries and its theorized increased independence between plausibility and presence.

  @article{9714117, abstract = {A novel theoretical model recently introduced coherence and plausibility as the essential conditions of XR experiences, challenging contemporary presence-oriented concepts. This article reports on two experiments validating this model, which assumes coherence activation on three layers (cognition, perception, and sensation) as the potential sources leading to a condition of plausibility and from there to other XR qualia such as presence or body ownership. The experiments introduce and utilize breaks in plausibility (in analogy to breaks in presence): We induce incoherence on the perceptual and the cognitive layer simultaneously by a simulation of object behaviors that do not conform to the laws of physics, i.e., gravity. We show that this manipulation breaks plausibility and hence confirm that it results in the desired effects in the theorized condition space but that the breaks in plausibility did not affect presence. In addition, we show that a cognitive manipulation by a storyline framing is too weak to successfully counteract the strong bottom-up inconsistencies. Both results are in line with the predictions of the recently introduced three-layer model of coherence and plausibility, which incorporates well-known top-down and bottom-up rivalries and its theorized increased independence between plausibility and presence.}, author = {Brübach, Larissa and Westermeier, Franziska and Wienrich, Carolin and Latoschik, Marc Erich}, journal = {IEEE Transactions on Visualization and Computer Graphics}, keywords = {xrhub}, month = {02}, note = {IEEE VR Best Journal Paper Nominee 🏆}, number = 5, pages = {2267-2276}, title = {Breaking Plausibility Without Breaking Presence - Evidence For The Multi-Layer Nature Of Plausibility}, volume = 28, year = 2022 }
• IT-Supported Request Management for Clinical Radiology: Contextual Design and Remote Prototype Testing. Krop, Philipp; Straka, Samantha; Ullrich, Melanie; Ertl, Maximilian; Latoschik, Marc Erich. In CHI Conference on Human Factors in Computing Systems Extended Abstracts, of CHI EA ’22, pp. 1–8. Association for Computing Machinery, New York, NY, USA, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Management of radiology requests in larger clinical contexts is characterized by a complex and distributed workflow. In our partner hospital, representing many similar clinics, these processes often still rely on exchanging physical papers and forms, making patient or case data challenging to access. This often leads to phone calls with long waiting queues, which are time-inefficient and result in frequent interrupts. We report on a user-centered design approach based on Rapid Contextual Design with an additional focus group to optimize and iteratively develop a new workflow. Participants found our prototypes fast and intuitive, the design clean and consistent, relevant information easy to access, and the request process fast and easy. Due to the COVID pandemic, we switched to remote prototype testing, which yielded equally good feedback and increased the participation rate. In the end, we propose best practices for remote prototype testing in hospitals with complex and distributed workflows.

  @inproceedings{krop2022a, abstract = {Management of radiology requests in larger clinical contexts is characterized by a complex and distributed workflow. In our partner hospital, representing many similar clinics, these processes often still rely on exchanging physical papers and forms, making patient or case data challenging to access. This often leads to phone calls with long waiting queues, which are time-inefficient and result in frequent interrupts. We report on a user-centered design approach based on Rapid Contextual Design with an additional focus group to optimize and iteratively develop a new workflow. Participants found our prototypes fast and intuitive, the design clean and consistent, relevant information easy to access, and the request process fast and easy. Due to the COVID pandemic, we switched to remote prototype testing, which yielded equally good feedback and increased the participation rate. In the end, we propose best practices for remote prototype testing in hospitals with complex and distributed workflows.}, address = {New York, NY, USA}, author = {Krop, Philipp and Straka, Samantha and Ullrich, Melanie and Ertl, Maximilian and Latoschik, Marc Erich}, booktitle = {CHI Conference on Human Factors in Computing Systems Extended Abstracts}, keywords = {latoschik}, month = {04}, number = 45, pages = {1-8}, publisher = {Association for Computing Machinery}, series = {CHI EA '22}, title = {IT-Supported Request Management for Clinical Radiology: Contextual Design and Remote Prototype Testing}, year = 2022 }
• Towards LoRaWAN without Data Loss: Studying the Performance of Different Channel Access Approaches. Loh, Frank; Mehling, Noah; Hoßfeld, Tobias. In Sensors. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  The Long Range Wide Area Network (LoRaWAN) is one of the fastest growing Internet of Things (IoT) access protocols. It operates in the license free 868 MHz band and gives everyone the possibility to create their own small sensor networks. The drawback of this technology is often unscheduled or random channel access, which leads to message collisions and potential data loss. For that reason, recent literature studies alternative approaches for LoRaWAN channel access. In this work, state-of-the-art random channel access is compared with alternative approaches from the litera- ture by means of collision probability. Furthermore, a time scheduled channel access methodology is presented to completely avoid collisions in LoRaWAN. For this approach, an exhaustive simulation study was conducted and the performance was evaluated with random access cross-traffic. In a general theoretical analysis the limits of the time scheduled approach are discussed to comply with duty cycle regulations in LoRaWAN.

  @article{info3-inproceedings-2022-3, abstract = {The Long Range Wide Area Network (LoRaWAN) is one of the fastest growing Internet of Things (IoT) access protocols. It operates in the license free 868 MHz band and gives everyone the possibility to create their own small sensor networks. The drawback of this technology is often unscheduled or random channel access, which leads to message collisions and potential data loss. For that reason, recent literature studies alternative approaches for LoRaWAN channel access. In this work, state-of-the-art random channel access is compared with alternative approaches from the litera- ture by means of collision probability. Furthermore, a time scheduled channel access methodology is presented to completely avoid collisions in LoRaWAN. For this approach, an exhaustive simulation study was conducted and the performance was evaluated with random access cross-traffic. In a general theoretical analysis the limits of the time scheduled approach are discussed to comply with duty cycle regulations in LoRaWAN.}, author = {Loh, Frank and Mehling, Noah and Hoßfeld, Tobias}, journal = {Sensors}, keywords = {5mart}, month = {01}, title = {Towards LoRaWAN without Data Loss: Studying the Performance of Different Channel Access Approaches}, year = 2022 }
• InDiReCT: Language-Guided Zero-Shot Deep Metric Learning for Images. Kobs, Konstantin; Steininger, Michael; Hotho, Andreas. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Common Deep Metric Learning (DML) datasets specify only one notion of similarity, e.g., two images in the Cars196 dataset are deemed similar if they show the same car model. We argue that depending on the application, users of image retrieval systems have different and changing similarity notions that should be incorporated as easily as possible. Therefore, we present Language-Guided Zero-Shot Deep Metric Learning (LanZ-DML) as a new DML setting in which users control the properties that should be important for image representations without training data by only using natural language. To this end, we propose InDiReCT (Image representations using Dimensionality Reduction on CLIP embedded Texts), a model for LanZ-DML on images that exclusively uses a few text prompts for training. InDiReCT utilizes CLIP as a fixed feature extractor for images and texts and transfers the variation in text prompt embeddings to the image embedding space. Extensive experiments on five datasets and overall thirteen similarity notions show that, despite not seeing any images during training, InDiReCT performs better than strong baselines and approaches the performance of fully-supervised models. An analysis reveals that InDiReCT learns to focus on regions of the image that correlate with the desired similarity notion, which makes it a fast to train and easy to use method to create custom embedding spaces only using natural language.

  @misc{kobs2022indirect, abstract = {Common Deep Metric Learning (DML) datasets specify only one notion of similarity, e.g., two images in the Cars196 dataset are deemed similar if they show the same car model. We argue that depending on the application, users of image retrieval systems have different and changing similarity notions that should be incorporated as easily as possible. Therefore, we present Language-Guided Zero-Shot Deep Metric Learning (LanZ-DML) as a new DML setting in which users control the properties that should be important for image representations without training data by only using natural language. To this end, we propose InDiReCT (Image representations using Dimensionality Reduction on CLIP embedded Texts), a model for LanZ-DML on images that exclusively uses a few text prompts for training. InDiReCT utilizes CLIP as a fixed feature extractor for images and texts and transfers the variation in text prompt embeddings to the image embedding space. Extensive experiments on five datasets and overall thirteen similarity notions show that, despite not seeing any images during training, InDiReCT performs better than strong baselines and approaches the performance of fully-supervised models. An analysis reveals that InDiReCT learns to focus on regions of the image that correlate with the desired similarity notion, which makes it a fast to train and easy to use method to create custom embedding spaces only using natural language.}, author = {Kobs, Konstantin and Steininger, Michael and Hotho, Andreas}, keywords = {selected}, note = {cite arxiv:2211.12760Comment: Accepted to WACV 2023}, title = {InDiReCT: Language-Guided Zero-Shot Deep Metric Learning for Images}, year = 2022 }
• Sequential Item Recommendation in the {MOBA} Game Dota 2. Dallmann, Alexander; Kohlmann, Johannes; Zoller, Daniel; Hotho, Andreas. In CoRR, abs/2201.08724. 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{DBLP:journals/corr/abs-2201-08724, author = {Dallmann, Alexander and Kohlmann, Johannes and Zoller, Daniel and Hotho, Andreas}, journal = {CoRR}, keywords = 2022, title = {Sequential Item Recommendation in the {MOBA} Game Dota 2}, volume = {abs/2201.08724}, year = 2022 }
• A data-driven Sensor Model for LIDAR Range Measurements used for Mobile Robot Navigation. Spiess, Florian; Strobel, Norbert; Kaupp, Tobias; Kounev, Samuel. In Proceedings of the IEEE IRC 2022 Conference. 2022.
  • [ BibTeX ]
  @conference{spiess2022datadriven, author = {Spiess, Florian and Strobel, Norbert and Kaupp, Tobias and Kounev, Samuel}, booktitle = {Proceedings of the IEEE IRC 2022 Conference}, keywords = {t_interdisciplinary}, title = {A data-driven Sensor Model for LIDAR Range Measurements used for Mobile Robot Navigation}, year = 2022 }
• {ICPE} ’22: {ACM/SPEC} International Conference on Performance Engineering, Bejing, China, April 9 - 13, 2022. Feng, Dan; Becker, Steffen; Herbst, Nikolas; Leitner, Philipp. D. Feng; S. Becker; N. Herbst; P. Leitner (eds.). {ACM}, 2022.
  • [ BibTeX ]
  • [ URL ]
  @proceedings{DBLP:conf/wosp/2022, author = {Feng, Dan and Becker, Steffen and Herbst, Nikolas and Leitner, Philipp}, editor = {Feng, Dan and Becker, Steffen and Herbst, Nikolas and Leitner, Philipp}, keywords = {t_proceedings}, publisher = {{ACM}}, title = {{ICPE} '22: {ACM/SPEC} International Conference on Performance Engineering, Bejing, China, April 9 - 13, 2022}, year = 2022 }
• {ICPE} ’22: {ACM/SPEC} International Conference on Performance Engineering, Bejing, China, April 9 - 13, 2022, Companion Volume. Feng, Dan; Becker, Steffen; Herbst, Nikolas; Leitner, Philipp. D. Feng; S. Becker; N. Herbst; P. Leitner (eds.). {ACM}, 2022.
  • [ BibTeX ]
  • [ URL ]
  @proceedings{DBLP:conf/wosp/2022c, author = {Feng, Dan and Becker, Steffen and Herbst, Nikolas and Leitner, Philipp}, editor = {Feng, Dan and Becker, Steffen and Herbst, Nikolas and Leitner, Philipp}, keywords = {t_proceedings}, publisher = {{ACM}}, title = {{ICPE} '22: {ACM/SPEC} International Conference on Performance Engineering, Bejing, China, April 9 - 13, 2022, Companion Volume}, year = 2022 }
• Do Different Deep Metric Learning Losses Lead to Similar Learned Features?. Kobs, Konstantin; Steininger, Michael; Dulny, Andrzej; Hotho, Andreas. In CoRR, abs/2205.02698. 2022.
  • [ BibTeX ]
  • [ URL ]
  @article{DBLP:journals/corr/abs-2205-02698, author = {Kobs, Konstantin and Steininger, Michael and Dulny, Andrzej and Hotho, Andreas}, journal = {CoRR}, keywords = 2022, title = {Do Different Deep Metric Learning Losses Lead to Similar Learned Features?}, volume = {abs/2205.02698}, year = 2022 }
• A literature review on optimization techniques for adaptation planning in adaptive systems: State of the art and research directions. Henrichs, Elia; Lesch, Veronika; Straesser, Martin; Kounev, Samuel; Krupitzer, Christian. In Information and Software Technology, 149, p. 106940. 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Context: Recent developments in modern IT systems including internet of things, edge/fog computing, or cyber–physical systems support intelligent and seamless interaction between users and systems. This requires a reaction to changes in their environment or the system. Adaptive systems provide mechanisms for these reactions. Objective: To implement this functionality, several approaches for the planning of adaptations exist that rely on rules, utility functions, or advanced techniques, such as machine learning. As the adaptation space with possible options is often extensively huge, optimization techniques might support efficient determination of the adaptation space and identify the system’s optimal configuration. With this paper, we provide a systematic review of adaptation planning as the optimization target. Method: In this paper, we review which optimization techniques are applied for adaptation planning in adaptive systems using a systematic literature review approach. Results: We reviewed 115 paper in detail out of an initial search set of 9,588 papers. Our analysis reveals that learning techniques and genetic algorithms are by far dominant; in total, heuristics (anytime learning) are more frequently applied as exact algorithms. We observed that around 57% of the approaches target multi-objectiveness and around 30% integrate distributed optimization. As last dimension, we focused on situation-awareness, which is only supported by two approaches. Conclusion: In this paper, we provide an overview of the current state of the art of approaches that rely on optimization techniques for planning adaptations in adaptive systems and further derive open research challenges, in particular regarding the integration of distributed optimization and situation-awareness.

  @article{HENRICHS2022106940, abstract = {Context: Recent developments in modern IT systems including internet of things, edge/fog computing, or cyber–physical systems support intelligent and seamless interaction between users and systems. This requires a reaction to changes in their environment or the system. Adaptive systems provide mechanisms for these reactions. Objective: To implement this functionality, several approaches for the planning of adaptations exist that rely on rules, utility functions, or advanced techniques, such as machine learning. As the adaptation space with possible options is often extensively huge, optimization techniques might support efficient determination of the adaptation space and identify the system’s optimal configuration. With this paper, we provide a systematic review of adaptation planning as the optimization target. Method: In this paper, we review which optimization techniques are applied for adaptation planning in adaptive systems using a systematic literature review approach. Results: We reviewed 115 paper in detail out of an initial search set of 9,588 papers. Our analysis reveals that learning techniques and genetic algorithms are by far dominant; in total, heuristics (anytime learning) are more frequently applied as exact algorithms. We observed that around 57% of the approaches target multi-objectiveness and around 30% integrate distributed optimization. As last dimension, we focused on situation-awareness, which is only supported by two approaches. Conclusion: In this paper, we provide an overview of the current state of the art of approaches that rely on optimization techniques for planning adaptations in adaptive systems and further derive open research challenges, in particular regarding the integration of distributed optimization and situation-awareness.}, author = {Henrichs, Elia and Lesch, Veronika and Straesser, Martin and Kounev, Samuel and Krupitzer, Christian}, journal = {Information and Software Technology}, keywords = {t_journalmagazine}, pages = 106940, title = {A literature review on optimization techniques for adaptation planning in adaptive systems: State of the art and research directions}, volume = 149, year = 2022 }
• Semi-unsupervised Learning for Time Series Classification. Davidson, Padraig; Steininger, Michael; Huhn, André; Krause, Anna; Hotho, Andreas. In Milets@KDD. arXiv, 2022.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Time series are ubiquitous and therefore inherently hard to analyze and ultimately to label or cluster. With the rise of the Internet of Things (IoT) and its smart devices, data is collected in large amounts any given second. The collected data is rich in information, as one can detect accidents (e.g. cars) in real time, or assess injury/sickness over a given time span (e.g. health devices). Due to its chaotic nature and massive amounts of datapoints, timeseries are hard to label manually. Furthermore new classes within the data could emerge over time (contrary to e.g. handwritten digits), which would require relabeling the data. In this paper we present SuSL4TS, a deep generative Gaussian mixture model for semi-unsupervised learning, to classify time series data. With our approach we can alleviate manual labeling steps, since we can detect sparsely labeled classes (semi-supervised) and identify emerging classes hidden in the data (unsupervised). We demonstrate the efficacy of our approach with established time series classification datasets from different domains.

  @article{davidson2022semiunsupervised, abstract = {Time series are ubiquitous and therefore inherently hard to analyze and ultimately to label or cluster. With the rise of the Internet of Things (IoT) and its smart devices, data is collected in large amounts any given second. The collected data is rich in information, as one can detect accidents (e.g. cars) in real time, or assess injury/sickness over a given time span (e.g. health devices). Due to its chaotic nature and massive amounts of datapoints, timeseries are hard to label manually. Furthermore new classes within the data could emerge over time (contrary to e.g. handwritten digits), which would require relabeling the data. In this paper we present SuSL4TS, a deep generative Gaussian mixture model for semi-unsupervised learning, to classify time series data. With our approach we can alleviate manual labeling steps, since we can detect sparsely labeled classes (semi-supervised) and identify emerging classes hidden in the data (unsupervised). We demonstrate the efficacy of our approach with established time series classification datasets from different domains.}, author = {Davidson, Padraig and Steininger, Michael and Huhn, André and Krause, Anna and Hotho, Andreas}, journal = {Milets@KDD}, keywords = {from:pdavidson}, publisher = {arXiv}, title = {Semi-unsupervised Learning for Time Series Classification}, year = 2022 }

• Buzzy: Towards Realistic DBMS Benchmarking via Tailored, Representative, Synthetic Workloads. Domaschka, Jörg; Eismann, Simon; Leznik, Mark; Grohmann, Johannes; Kounev, Samuel; Seybold, Daniel. In Companion of the ACM/SPEC International Conference on Performance Engineering, Vol. ICPE ’21, pp. 175–178. Association for Computing Machinery, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Distributed Database Management Systems (DBMS) are a crucial component of modern IT applications. Understanding their performance and non-functional properties is of paramount importance. Yet, benchmarking distributed DBMS has proven to be difficult in practice. Either, a realistic workload is often mapped to a synthetic workload without knowing if this mapping is correct or available workload traces are replayed. While the latter approach provides more realistic results, real-world traces are hard to obtain and their scope is limited in time scale and variance.We propose collecting real-world traces and then applying data generation techniques to synthesize similar realistic traces based on it. Based in this approach, we can obtain workloads for benchmarking, exhibit variability with respect to different aspects of interest while still being similar to the original traces. Varying generation parameters, we are able to support benchmarking what-if scenarios with hypothetical workloads and introduced anomalies.

  @inproceedings{domaschka2021buzzy, abstract = {Distributed Database Management Systems (DBMS) are a crucial component of modern IT applications. Understanding their performance and non-functional properties is of paramount importance. Yet, benchmarking distributed DBMS has proven to be difficult in practice. Either, a realistic workload is often mapped to a synthetic workload without knowing if this mapping is correct or available workload traces are replayed. While the latter approach provides more realistic results, real-world traces are hard to obtain and their scope is limited in time scale and variance.We propose collecting real-world traces and then applying data generation techniques to synthesize similar realistic traces based on it. Based in this approach, we can obtain workloads for benchmarking, exhibit variability with respect to different aspects of interest while still being similar to the original traces. Varying generation parameters, we are able to support benchmarking what-if scenarios with hypothetical workloads and introduced anomalies.}, address = {New York, NY, USA}, author = {Domaschka, Jörg and Eismann, Simon and Leznik, Mark and Grohmann, Johannes and Kounev, Samuel and Seybold, Daniel}, booktitle = {Companion of the ACM/SPEC International Conference on Performance Engineering}, keywords = {descartes}, pages = {175–178}, publisher = {Association for Computing Machinery}, title = {Buzzy: Towards Realistic DBMS Benchmarking via Tailored, Representative, Synthetic Workloads}, volume = {ICPE '21}, year = 2021 }
• Tackling the Rich Vehicle Routing Problem with Nature-Inspired Algorithms. Lesch, Veronika; König, Maximilian; Kounev, Samuel; Stein, Anthony; Krupitzer, Christian. In Applied Intelligence, 52, pp. 9476–9500. 2021.
  • [ BibTeX ]
  @article{lesch2021tackling, author = {Lesch, Veronika and König, Maximilian and Kounev, Samuel and Stein, Anthony and Krupitzer, Christian}, journal = {Applied Intelligence}, keywords = {t_journalmagazine}, pages = {9476–9500}, title = {Tackling the Rich Vehicle Routing Problem with Nature-Inspired Algorithms}, volume = 52, year = 2021 }
• The integration of training and off-training activities substantially alters training volume and load analysis in elite rowers. Treff, Gunnar; Leppich, Robert; Winkert, Kay; Steinacker, J{ü}rgen M; Mayer, Benjamin; Sperlich, Billy. In Scientific reports, 11(1), pp. 1–10. Nature Publishing Group, 2021.
  • [ BibTeX ]
  @article{treff2021integration, author = {Treff, Gunnar and Leppich, Robert and Winkert, Kay and Steinacker, J{\"u}rgen M and Mayer, Benjamin and Sperlich, Billy}, journal = {Scientific reports}, keywords = {t_journalmagazine}, number = 1, pages = {1–10}, publisher = {Nature Publishing Group}, title = {The integration of training and off-training activities substantially alters training volume and load analysis in elite rowers}, volume = 11, year = 2021 }
• Sizeless: Predicting the Optimal Size of Serverless Functions. Eismann, Simon; Bui, Long; Grohmann, Johannes; Abad, Cristina; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 22nd International MIDDLEWARE Conference, pp. 248–259. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Serverless functions are an emerging cloud computing paradigm that is being rapidly adopted by both industry and academia. In this cloud computing model, the provider opaquely handles resource management tasks such as resource provisioning, deployment, and auto-scaling. The only resource management task that developers are still in charge of is selecting how much resources are allocated to each worker instance. However, selecting the optimal size of serverless functions is quite challenging, so developers often neglect it despite its significant cost and performance benefits. Existing approaches aiming to automate serverless functions resource sizing require dedicated performance tests, which are time-consuming to implement and maintain. In this paper, we introduce an approach to predict the optimal resource size of a serverless function using monitoring data from a single resource size. As our approach does not require dedicated performance tests, it enables cloud providers to implement resource sizing on a platform level and automate the last resource management task associated with serverless functions. We evaluate our approach on four different serverless applications on AWS, where it predicts the execution time of the other memory sizes based on monitoring data for a single memory size with an average prediction error of 15.3%. Based on these predictions, it selects the optimal memory size for 79.0% of the serverless functions and the secondbest memory size for 12.3% of the serverless functions, which results in an average speedup of 39.7% while also decreasing average costs by 2.6%.

  @inproceedings{eismann2021sizeless, abstract = {Serverless functions are an emerging cloud computing paradigm that is being rapidly adopted by both industry and academia. In this cloud computing model, the provider opaquely handles resource management tasks such as resource provisioning, deployment, and auto-scaling. The only resource management task that developers are still in charge of is selecting how much resources are allocated to each worker instance. However, selecting the optimal size of serverless functions is quite challenging, so developers often neglect it despite its significant cost and performance benefits. Existing approaches aiming to automate serverless functions resource sizing require dedicated performance tests, which are time-consuming to implement and maintain. In this paper, we introduce an approach to predict the optimal resource size of a serverless function using monitoring data from a single resource size. As our approach does not require dedicated performance tests, it enables cloud providers to implement resource sizing on a platform level and automate the last resource management task associated with serverless functions. We evaluate our approach on four different serverless applications on AWS, where it predicts the execution time of the other memory sizes based on monitoring data for a single memory size with an average prediction error of 15.3%. Based on these predictions, it selects the optimal memory size for 79.0% of the serverless functions and the secondbest memory size for 12.3% of the serverless functions, which results in an average speedup of 39.7% while also decreasing average costs by 2.6%.}, author = {Eismann, Simon and Bui, Long and Grohmann, Johannes and Abad, Cristina and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 22nd International MIDDLEWARE Conference}, keywords = {descartes}, note = {Best Student Paper Award, ACM Artifacts Evaluated — Functional}, pages = {248–259}, title = {Sizeless: Predicting the Optimal Size of Serverless Functions}, year = 2021 }
• Establishing a cardiac training group for patients with heart failure: the “HIP-in-W{ü}rzburg” study. G{ü}der, G{ü}lmisal; Wilkesmann, Joana; Scholz, Nina; Leppich, Robert; D{ü}king, Peter; Sperlich, Billy; Rost, Christian; Frantz, Stefan; Morbach, Caroline; Sahiti, Floran; others. In Clinical Research in Cardiology, pp. 1–10. Springer, 2021.
  • [ BibTeX ]
  @article{guder2021establishing, author = {G{\"u}der, G{\"u}lmisal and Wilkesmann, Joana and Scholz, Nina and Leppich, Robert and D{\"u}king, Peter and Sperlich, Billy and Rost, Christian and Frantz, Stefan and Morbach, Caroline and Sahiti, Floran and others}, journal = {Clinical Research in Cardiology}, keywords = {t_journalmagazine}, pages = {1–10}, publisher = {Springer}, title = {Establishing a cardiac training group for patients with heart failure: the “HIP-in-W{\"u}rzburg” study}, year = 2021 }
• A Case Study on Optimization of Warehouses. Lesch, Veronika; Müller, Patrick B.M.; Krämer, Moritz; Kounev, Samuel; Krupitzer, Christian. 2021.
  • [ BibTeX ]
  • [ URL ]
  @techreport{lesch2021study, author = {Lesch, Veronika and Müller, Patrick B.M. and Krämer, Moritz and Kounev, Samuel and Krupitzer, Christian}, keywords = {t_techreport}, title = {A Case Study on Optimization of Warehouses}, year = 2021 }
• A Case Study of Vehicle Route Optimization. Lesch, Veronika; König, Maximilian; Kounev, Samuel; Stein, Anthony; Krupitzer, Christian. Universit{ä}t W{ü}rzburg and PASS Logistics Solutions AG and Universit{ä}t Hohenheim, 2021.
  • [ BibTeX ]
  • [ URL ]
  @techreport{lesch2021studyvrp, author = {Lesch, Veronika and König, Maximilian and Kounev, Samuel and Stein, Anthony and Krupitzer, Christian}, institution = {Universit{ä}t W{ü}rzburg and PASS Logistics Solutions AG and Universit{ä}t Hohenheim}, keywords = {t_techreport}, title = {A Case Study of Vehicle Route Optimization}, year = 2021 }
• On Minimum Generalized Manhattan Connections. Antoniadis, Antonios; Capretto, Margarita; Chalermsook, Parinya; Damerius, Christoph; Kling, Peter; Nölke, Lukas; Obscura, Nidia; Spoerhase, Joachim. In Proc. 17th Algorithms and Data Structures Symposium (WADS’21), Vol. 12808, pp. 85–100. 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{antoniadis2021minimum, author = {Antoniadis, Antonios and Capretto, Margarita and Chalermsook, Parinya and Damerius, Christoph and Kling, Peter and Nölke, Lukas and Obscura, Nidia and Spoerhase, Joachim}, booktitle = {Proc. 17th Algorithms and Data Structures Symposium (WADS'21)}, keywords = {structure}, pages = {85–100}, title = {On Minimum Generalized Manhattan Connections}, volume = 12808, year = 2021 }
• Container Start Times: Empirical Analysis and Predictability. Straesser, Martin. 2021.
  • [ BibTeX ]
  • [ URL ]
  @presentation{straesser2021container, author = {Straesser, Martin}, keywords = {empirical_study}, title = {Container Start Times: Empirical Analysis and Predictability}, year = 2021 }
• Sizeless: Predicting the Optimal Size of Serverless Functions. Eismann, Simon; Bui, Long; Grohmann, Johannes; Abad, Cristina; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 22nd International MIDDLEWARE Conference, pp. 248–259. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Serverless functions are an emerging cloud computing paradigm that is being rapidly adopted by both industry and academia. In this cloud computing model, the provider opaquely handles resource management tasks such as resource provisioning, deployment, and auto-scaling. The only resource management task that developers are still in charge of is selecting how much resources are allocated to each worker instance. However, selecting the optimal size of serverless functions is quite challenging, so developers often neglect it despite its significant cost and performance benefits. Existing approaches aiming to automate serverless functions resource sizing require dedicated performance tests, which are time-consuming to implement and maintain. In this paper, we introduce an approach to predict the optimal resource size of a serverless function using monitoring data from a single resource size. As our approach does not require dedicated performance tests, it enables cloud providers to implement resource sizing on a platform level and automate the last resource management task associated with serverless functions. We evaluate our approach on four different serverless applications on AWS, where it predicts the execution time of the other memory sizes based on monitoring data for a single memory size with an average prediction error of 15.3%. Based on these predictions, it selects the optimal memory size for 79.0% of the serverless functions and the secondbest memory size for 12.3% of the serverless functions, which results in an average speedup of 39.7% while also decreasing average costs by 2.6%.

  @inproceedings{eismann2021sizeless, abstract = {Serverless functions are an emerging cloud computing paradigm that is being rapidly adopted by both industry and academia. In this cloud computing model, the provider opaquely handles resource management tasks such as resource provisioning, deployment, and auto-scaling. The only resource management task that developers are still in charge of is selecting how much resources are allocated to each worker instance. However, selecting the optimal size of serverless functions is quite challenging, so developers often neglect it despite its significant cost and performance benefits. Existing approaches aiming to automate serverless functions resource sizing require dedicated performance tests, which are time-consuming to implement and maintain. In this paper, we introduce an approach to predict the optimal resource size of a serverless function using monitoring data from a single resource size. As our approach does not require dedicated performance tests, it enables cloud providers to implement resource sizing on a platform level and automate the last resource management task associated with serverless functions. We evaluate our approach on four different serverless applications on AWS, where it predicts the execution time of the other memory sizes based on monitoring data for a single memory size with an average prediction error of 15.3%. Based on these predictions, it selects the optimal memory size for 79.0% of the serverless functions and the secondbest memory size for 12.3% of the serverless functions, which results in an average speedup of 39.7% while also decreasing average costs by 2.6%.}, author = {Eismann, Simon and Bui, Long and Grohmann, Johannes and Abad, Cristina and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 22nd International MIDDLEWARE Conference}, keywords = {descartes}, note = {Best Student Paper Award, ACM Artifacts Evaluated — Functional}, pages = {248–259}, title = {Sizeless: Predicting the Optimal Size of Serverless Functions}, year = 2021 }
• Tracking rower motion without on-body sensors using an instrumented machine and an artificial neural network. BenSiSaid, Karim; Ababou, Noureddine; Ababou, Amina; Roth, Daniel; von Mammen, Sebastian. In Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology. SAGE Publications Sage UK: London, England, 2021.
  • [ BibTeX ]
  • [ URL ]
  @article{bensisaid2021tracking, author = {BenSiSaid, Karim and Ababou, Noureddine and Ababou, Amina and Roth, Daniel and von Mammen, Sebastian}, journal = {Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology}, keywords = {myown}, publisher = {SAGE Publications Sage UK: London, England}, title = {Tracking rower motion without on-body sensors using an instrumented machine and an artificial neural network}, year = 2021 }
• A financial game with opportunities for fraud. Tritscher, Julian; Krause, Anna; Schlör, Daniel; Gwinner, Fabian; Von Mammen, Sebastian; Hotho, Andreas. In 2021 IEEE Conference on Games (CoG), pp. 1–5. 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Tritscher:2021aa, author = {Tritscher, Julian and Krause, Anna and Schlör, Daniel and Gwinner, Fabian and Von Mammen, Sebastian and Hotho, Andreas}, booktitle = {2021 IEEE Conference on Games (CoG)}, keywords = {myown}, pages = {1-5}, title = {A financial game with opportunities for fraud}, year = 2021 }
• Ka-Boom!!! Visually Exploring Latency Measurements for XR. Stauffert, Jan-Philipp; Korwisi, Kristof; Niebling, Florian; Latoschik, Marc Erich. In Extended Abstracts of the 2021 CHI Conference on Human Factors in Computing Systems, of CHI EA ’21. Association for Computing Machinery, Yokohama, Japan, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Latency can be detrimental for the experience of Virtual Reality. High latency can lead to loss of performance and cybersickness. There are simple approaches to measure approximate latency and more elaborated for more insight into latency behavior. Yet there are still researchers who do not measure the latency of the system they are using to conduct VR experiments. This paper provides an illustrated overview of different approaches to measure latency of VR applications, as well as a small decision-making guide to assist in the choice of the measurement method. The visual style offers a more approachable way to understand how to measure latency.

  @inproceedings{stauffert_kaboom_2021, abstract = {Latency can be detrimental for the experience of Virtual Reality. High latency can lead to loss of performance and cybersickness. There are simple approaches to measure approximate latency and more elaborated for more insight into latency behavior. Yet there are still researchers who do not measure the latency of the system they are using to conduct VR experiments. This paper provides an illustrated overview of different approaches to measure latency of VR applications, as well as a small decision-making guide to assist in the choice of the measurement method. The visual style offers a more approachable way to understand how to measure latency.}, address = {New York, NY, USA}, author = {Stauffert, Jan-Philipp and Korwisi, Kristof and Niebling, Florian and Latoschik, Marc Erich}, booktitle = {Extended Abstracts of the 2021 CHI Conference on Human Factors in Computing Systems}, keywords = {myown}, publisher = {Association for Computing Machinery}, series = {CHI EA '21}, title = {Ka-Boom!!! Visually Exploring Latency Measurements for XR}, year = 2021 }
• Modding Support of Game Engines. Schreiner, Lukas; von Mammen, Sebastian. In The 16th International Conference on the Foundations of Digital Games (FDG) 2021, of FDG’21. Association for Computing Machinery, Montreal, QC, Canada, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper aims at showing how different game engines support modding. To this end, the concepts of modding and game engines alongside their historical evolution are introduced first. Additionally, some well-known game engines and mods are presented, and their unique features are described. Further, the effects of using game engines and those that modding has on games, developers, and players are laid out. Particular focus is placed on the effects on competitive games. These effects include an enhanced lifespan for games and the requirement for more development effort. Finally, the modding-support of selected game engines is illustrated and compared with each other. These engines are the id Tech engine(s), Unreal Engine, the Source engine, and Unity. The paper is then concluded with an outlook on future research possibilities and recommendations to developers.

  @inproceedings{10.1145/3472538.3472574, abstract = {This paper aims at showing how different game engines support modding. To this end, the concepts of modding and game engines alongside their historical evolution are introduced first. Additionally, some well-known game engines and mods are presented, and their unique features are described. Further, the effects of using game engines and those that modding has on games, developers, and players are laid out. Particular focus is placed on the effects on competitive games. These effects include an enhanced lifespan for games and the requirement for more development effort. Finally, the modding-support of selected game engines is illustrated and compared with each other. These engines are the id Tech engine(s), Unreal Engine, the Source engine, and Unity. The paper is then concluded with an outlook on future research possibilities and recommendations to developers.}, address = {New York, NY, USA}, author = {Schreiner, Lukas and von Mammen, Sebastian}, booktitle = {The 16th International Conference on the Foundations of Digital Games (FDG) 2021}, keywords = {myown}, publisher = {Association for Computing Machinery}, series = {FDG'21}, title = {Modding Support of Game Engines}, year = 2021 }
• The Influence of Avatar Embodiment on Time Perception - Towards VR for Time-Based Therapy. Unruh, Fabian; Landeck, Maximilian; Oberd{ö}rfer, Sebastian; Lugrin, Jean-Luc; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 2, p. 71. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Psycho-pathological conditions, such as depression or schizophrenia, are often accompanied by a distorted perception of time. People suffering from this conditions often report that the passage of time slows down considerably and that they are ``stuck in time.'' Virtual Reality (VR) could potentially help to diagnose and maybe treat such mental conditions. However, the conditions in which a VR simulation could correctly diagnose a time perception deviation are still unknown. In this paper, we present an experiment investigating the difference in time experience with and without a virtual body in VR, also known as avatar. The process of substituting a person's body with a virtual body is called avatar embodiment. Numerous studies demonstrated interesting perceptual, emotional, behavioral, and psychological effects caused by avatar embodiment. However, the relations between time perception and avatar embodiment are still unclear. Whether or not the presence or absence of an avatar is already influencing time perception is still open to question. Therefore, we conducted a between-subjects design with and without avatar embodiment as well as a real condition (avatar vs. no-avatar vs. real). A group of 105 healthy subjects had to wait for seven and a half minutes in a room without any distractors (e.g., no window, magazine, people, decoration) or time indicators (e.g., clocks, sunlight). The virtual environment replicates the real physical environment. Participants were unaware that they will be asked to estimate their waiting time duration as well as describing their experience of the passage of time at a later stage. Our main finding shows that the presence of an avatar is leading to a significantly faster perceived passage of time. It seems to be promising to integrate avatar embodiment in future VR time-based therapy applications as they potentially could modulate a user's perception of the passage of time. We also found no significant difference in time perception between the real and the VR conditions (avatar, no-avatar), but further research is needed to better understand this outcome.

  @article{10.3389/frvir.2021.658509, abstract = {Psycho-pathological conditions, such as depression or schizophrenia, are often accompanied by a distorted perception of time. People suffering from this conditions often report that the passage of time slows down considerably and that they are ``stuck in time.'' Virtual Reality (VR) could potentially help to diagnose and maybe treat such mental conditions. However, the conditions in which a VR simulation could correctly diagnose a time perception deviation are still unknown. In this paper, we present an experiment investigating the difference in time experience with and without a virtual body in VR, also known as avatar. The process of substituting a person's body with a virtual body is called avatar embodiment. Numerous studies demonstrated interesting perceptual, emotional, behavioral, and psychological effects caused by avatar embodiment. However, the relations between time perception and avatar embodiment are still unclear. Whether or not the presence or absence of an avatar is already influencing time perception is still open to question. Therefore, we conducted a between-subjects design with and without avatar embodiment as well as a real condition (avatar vs. no-avatar vs. real). A group of 105 healthy subjects had to wait for seven and a half minutes in a room without any distractors (e.g., no window, magazine, people, decoration) or time indicators (e.g., clocks, sunlight). The virtual environment replicates the real physical environment. Participants were unaware that they will be asked to estimate their waiting time duration as well as describing their experience of the passage of time at a later stage. Our main finding shows that the presence of an avatar is leading to a significantly faster perceived passage of time. It seems to be promising to integrate avatar embodiment in future VR time-based therapy applications as they potentially could modulate a user's perception of the passage of time. We also found no significant difference in time perception between the real and the VR conditions (avatar, no-avatar), but further research is needed to better understand this outcome.}, author = {Unruh, Fabian and Landeck, Maximilian and Oberd{\"o}rfer, Sebastian and Lugrin, Jean-Luc and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {hci-uwb}, pages = 71, title = {The Influence of Avatar Embodiment on Time Perception - Towards VR for Time-Based Therapy}, volume = 2, year = 2021 }
• IT-Supported request management for clinical radiology: Analyzing the Radiological Order Workflow through Contextual Interviews. Krop, Philipp; Straka, Samantha; Ullrich, Melanie; Ertl, Maximilian; Latoschik, Marc Erich. In Mensch und Computer 2021 (MuC ’21), September 5-8, 2021, Ingolstadt, Germany, pp. 1–7. Association for Computing Machinery, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Requests for radiological examinations in large medical facilities are a distributed and complex process with potential health-related risks for patients. A user-centered qualitative analysis with contextual interviews uncovered nine core problems, which hinder work efficiency and patient care: (1) Difficulties to access patient data & requests, (2) the large number of phone calls, (3) restricted & abused access rights, (4) request status difficult to track, (5) paper notes used for patient data, (6) lack of assistance for data entry, (7) frustration through documentation, (8) IT-systems not self-explanatory, and (9) conflict between physicians and radiologists.Contextual interviews were found to be a well fitting method to analyze and understand this complex process with multiple user roles. This analysis showed that there is room for improvement in the underlying IT systems, workflows and infrastructure. Our data gave useful insight into solutions to these problems and how we can use technology to improve all aspects of the request management. We are currently addressing those issues with a user-centered design process to design and implement a mobile application, which we will present in future work.

  @inproceedings{kropstraka21, abstract = {Requests for radiological examinations in large medical facilities are a distributed and complex process with potential health-related risks for patients. A user-centered qualitative analysis with contextual interviews uncovered nine core problems, which hinder work efficiency and patient care: (1) Difficulties to access patient data & requests, (2) the large number of phone calls, (3) restricted & abused access rights, (4) request status difficult to track, (5) paper notes used for patient data, (6) lack of assistance for data entry, (7) frustration through documentation, (8) IT-systems not self-explanatory, and (9) conflict between physicians and radiologists.Contextual interviews were found to be a well fitting method to analyze and understand this complex process with multiple user roles. This analysis showed that there is room for improvement in the underlying IT systems, workflows and infrastructure. Our data gave useful insight into solutions to these problems and how we can use technology to improve all aspects of the request management. We are currently addressing those issues with a user-centered design process to design and implement a mobile application, which we will present in future work.}, address = {New York, NY, USA}, author = {Krop, Philipp and Straka, Samantha and Ullrich, Melanie and Ertl, Maximilian and Latoschik, Marc Erich}, booktitle = {Mensch und Computer 2021 (MuC '21), September 5-8, 2021, Ingolstadt, Germany}, keywords = {latoschik}, pages = {1-7}, publisher = {Association for Computing Machinery}, title = {IT-Supported request management for clinical radiology: Analyzing the Radiological Order Workflow through Contextual Interviews}, year = 2021 }
• Non-native speaker perception of Intelligent Virtual Agents in two languages: the impact of amount and type of grammatical mistakes. Obremski, David; Lugrin, Jean-Luc; Schaper, Philipp; Lugrin, Birgit. In Journal on Multimodal User Interfaces. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Having a mixed-cultural membership becomes increasingly common in our modern society. It is thus beneficial in several ways to create Intelligent Virtual Agents (IVAs) that reflect a mixed-cultural background as well, e.g., for educational settings. For research with such IVAs, it is essential that they are classified as non-native by members of a target culture. In this paper, we focus on variations of IVAs' speech to create the impression of non-native speakers that are identified as such by speakers of two different mother tongues. In particular, we investigate grammatical mistakes and identify thresholds beyond which the agents is clearly categorised as a non-native speaker. Therefore, we conducted two experiments: one for native speakers of German, and one for native speakers of English. Results of the German study indicate that beyond 10{\%} of word order mistakes and 25{\%} of infinitive mistakes German-speaking IVAs are perceived as non-native speakers. Results of the English study indicate that beyond 50{\%} of omission mistakes and 50{\%} of infinitive mistakes English-speaking IVAs are perceived as non-native speakers. We believe these thresholds constitute helpful guidelines for computational approaches of non-native speaker generation, simplifying research with IVAs in mixed-cultural settings.

  @article{Obremski2021, abstract = {Having a mixed-cultural membership becomes increasingly common in our modern society. It is thus beneficial in several ways to create Intelligent Virtual Agents (IVAs) that reflect a mixed-cultural background as well, e.g., for educational settings. For research with such IVAs, it is essential that they are classified as non-native by members of a target culture. In this paper, we focus on variations of IVAs' speech to create the impression of non-native speakers that are identified as such by speakers of two different mother tongues. In particular, we investigate grammatical mistakes and identify thresholds beyond which the agents is clearly categorised as a non-native speaker. Therefore, we conducted two experiments: one for native speakers of German, and one for native speakers of English. Results of the German study indicate that beyond 10{\%} of word order mistakes and 25{\%} of infinitive mistakes German-speaking IVAs are perceived as non-native speakers. Results of the English study indicate that beyond 50{\%} of omission mistakes and 50{\%} of infinitive mistakes English-speaking IVAs are perceived as non-native speakers. We believe these thresholds constitute helpful guidelines for computational approaches of non-native speaker generation, simplifying research with IVAs in mixed-cultural settings.}, author = {Obremski, David and Lugrin, Jean-Luc and Schaper, Philipp and Lugrin, Birgit}, journal = {Journal on Multimodal User Interfaces}, keywords = {mi}, title = {Non-native speaker perception of Intelligent Virtual Agents in two languages: the impact of amount and type of grammatical mistakes}, year = 2021 }
• Effects of Acrophobic Fear and Trait Anxiety on Human Behavior in a Virtual Elevated Plus-Maze. Madeira, Octavia; Gromer, Daniel; Latoschik, Marc Erich; Pauli, Paul. In Frontiers in Virtual Reality, 2. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The Elevated Plus-Maze (EPM) is a well-established apparatus to measure anxiety in rodents, i.e., animals exhibiting an increased relative time spent in the closed vs. the open arms are considered anxious. To examine whether such anxiety-modulated behaviors are conserved in humans, we re-translated this paradigm to a human setting using virtual reality in a Cave Automatic Virtual Environment (CAVE) system. In two studies, we examined whether the EPM exploration behavior of humans is modulated by their trait anxiety and also assessed the individuals' levels of acrophobia (fear of height), claustrophobia (fear of confined spaces), sensation seeking, and the reported anxiety when on the maze. First, we constructed an exact virtual copy of the animal EPM adjusted to human proportions. In analogy to animal EPM studies, participants (N = 30) freely explored the EPM for 5 min. In the second study (N = 61), we redesigned the EPM to make it more human-adapted and to differentiate influences of trait anxiety and acrophobia by introducing various floor textures and lower walls of closed arms to the height of standard handrails. In the first experiment, hierarchical regression analyses of exploration behavior revealed the expected association between open arm avoidance and Trait Anxiety, an even stronger association with acrophobic fear. In the second study, results revealed that acrophobia was associated with avoidance of open arms with mesh-floor texture, whereas for trait anxiety, claustrophobia, and sensation seeking, no effect was detected. Also, subjects' fear rating was moderated by all psychometrics but trait anxiety. In sum, both studies consistently indicate that humans show no general open arm avoidance analogous to rodents and that human EPM behavior is modulated strongest by acrophobic fear, whereas trait anxiety plays a subordinate role. Thus, we conclude that the criteria for cross-species validity are met insufficiently in this case. Despite the exploratory nature, our studies provide in-depth insights into human exploration behavior on the virtual EPM.

  @article{madeira:2021x, abstract = {The Elevated Plus-Maze (EPM) is a well-established apparatus to measure anxiety in rodents, i.e., animals exhibiting an increased relative time spent in the closed vs. the open arms are considered anxious. To examine whether such anxiety-modulated behaviors are conserved in humans, we re-translated this paradigm to a human setting using virtual reality in a Cave Automatic Virtual Environment (CAVE) system. In two studies, we examined whether the EPM exploration behavior of humans is modulated by their trait anxiety and also assessed the individuals' levels of acrophobia (fear of height), claustrophobia (fear of confined spaces), sensation seeking, and the reported anxiety when on the maze. First, we constructed an exact virtual copy of the animal EPM adjusted to human proportions. In analogy to animal EPM studies, participants (N = 30) freely explored the EPM for 5 min. In the second study (N = 61), we redesigned the EPM to make it more human-adapted and to differentiate influences of trait anxiety and acrophobia by introducing various floor textures and lower walls of closed arms to the height of standard handrails. In the first experiment, hierarchical regression analyses of exploration behavior revealed the expected association between open arm avoidance and Trait Anxiety, an even stronger association with acrophobic fear. In the second study, results revealed that acrophobia was associated with avoidance of open arms with mesh-floor texture, whereas for trait anxiety, claustrophobia, and sensation seeking, no effect was detected. Also, subjects' fear rating was moderated by all psychometrics but trait anxiety. In sum, both studies consistently indicate that humans show no general open arm avoidance analogous to rodents and that human EPM behavior is modulated strongest by acrophobic fear, whereas trait anxiety plays a subordinate role. Thus, we conclude that the criteria for cross-species validity are met insufficiently in this case. Despite the exploratory nature, our studies provide in-depth insights into human exploration behavior on the virtual EPM.}, author = {Madeira, Octavia and Gromer, Daniel and Latoschik, Marc Erich and Pauli, Paul}, journal = {Frontiers in Virtual Reality}, keywords = {myown}, title = {Effects of Acrophobic Fear and Trait Anxiety on Human Behavior in a Virtual Elevated Plus-Maze}, volume = 2, year = 2021 }
• A Structured Approach to Test the Signal Quality of Electroencephalography Measurements During Use of Head-Mounted Displays for Virtual Reality Applications. Weber, Desirée; Hertweck, Stephan; Alwanni, Hisham; Fiederer, Lukas D. J.; Wang, Xi; Unruh, Fabian; Fischbach, Martin; Latoschik, Marc Erich; Ball, Tonio. In Frontiers in Neuroscience, 15, p. 1527. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Joint applications of virtual reality (VR) systems and electroencephalography (EEG) offer numerous new possibilities ranging from behavioral science to therapy. VR systems allow for highly controlled experimental environments, while EEG offers a non-invasive window to brain activity with a millisecond-ranged temporal resolution. However, EEG measurements are highly susceptible to electromagnetic (EM) noise and the influence of EM noise of head-mounted-displays (HMDs) on EEG signal quality has not been conclusively investigated. In this paper, we propose a structured approach to test HMDs for EM noise potentially harmful to EEG measures. The approach verifies the impact of HMDs on the frequency- and time-domain of the EEG signal recorded in healthy subjects. The verification task includes a comparison of conditions with and without an HMD during (i) an eyes-open vs. eyes-closed task, and (ii) with respect to the sensory- evoked brain activity. The approach is developed and tested to derive potential effects of two commercial HMDs, the Oculus Rift and the HTC Vive Pro, on the quality of 64-channel EEG measurements. The results show that the HMDs consistently introduce artifacts, especially at the line hum of 50 Hz and the HMD refresh rate of 90 Hz, respectively, and their harmonics. The frequency range that is typically most important in non-invasive EEG research and applications (<50 Hz) however, remained largely unaffected. Hence, our findings demonstrate that high-quality EEG recordings, at least in the frequency range up to 50 Hz, can be obtained with the two tested HMDs. However, the number of commercially available HMDs is constantly rising. We strongly suggest to thoroughly test such devices upfront since each HMD will most likely have its own EM footprint and this article provides a structured approach to implement such tests with arbitrary devices.

  @article{weber2021structured, abstract = {Joint applications of virtual reality (VR) systems and electroencephalography (EEG) offer numerous new possibilities ranging from behavioral science to therapy. VR systems allow for highly controlled experimental environments, while EEG offers a non-invasive window to brain activity with a millisecond-ranged temporal resolution. However, EEG measurements are highly susceptible to electromagnetic (EM) noise and the influence of EM noise of head-mounted-displays (HMDs) on EEG signal quality has not been conclusively investigated. In this paper, we propose a structured approach to test HMDs for EM noise potentially harmful to EEG measures. The approach verifies the impact of HMDs on the frequency- and time-domain of the EEG signal recorded in healthy subjects. The verification task includes a comparison of conditions with and without an HMD during (i) an eyes-open vs. eyes-closed task, and (ii) with respect to the sensory- evoked brain activity. The approach is developed and tested to derive potential effects of two commercial HMDs, the Oculus Rift and the HTC Vive Pro, on the quality of 64-channel EEG measurements. The results show that the HMDs consistently introduce artifacts, especially at the line hum of 50 Hz and the HMD refresh rate of 90 Hz, respectively, and their harmonics. The frequency range that is typically most important in non-invasive EEG research and applications (<50 Hz) however, remained largely unaffected. Hence, our findings demonstrate that high-quality EEG recordings, at least in the frequency range up to 50 Hz, can be obtained with the two tested HMDs. However, the number of commercially available HMDs is constantly rising. We strongly suggest to thoroughly test such devices upfront since each HMD will most likely have its own EM footprint and this article provides a structured approach to implement such tests with arbitrary devices.}, author = {Weber, Desirée and Hertweck, Stephan and Alwanni, Hisham and Fiederer, Lukas D. J. and Wang, Xi and Unruh, Fabian and Fischbach, Martin and Latoschik, Marc Erich and Ball, Tonio}, journal = {Frontiers in Neuroscience}, keywords = {hci-uwb}, pages = 1527, title = {A Structured Approach to Test the Signal Quality of Electroencephalography Measurements During Use of Head-Mounted Displays for Virtual Reality Applications}, volume = 15, year = 2021 }
• Mutual Benefits: Interdisciplinary Education of Pre-Service Teachers and HCI Students in VR/AR Learning Environment Design. Oberdörfer, Sebastian; Birnstiel, Sandra; Latoschik, Marc Erich; Grafe, Silke. In Frontiers in Education, 6, p. 233. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The successful development and classroom integration of Virtual (VR) and Augmented Reality (AR) learning environments requires competencies and content knowledge with respect to media didactics and the respective technologies. The paper discusses a pedagogical concept specifically aiming at the interdisciplinary education of pre-service teachers in collaboration with human-computer interaction students. The students’ overarching goal is the interdisciplinary realization and integration of VR/AR learning environments in teaching and learning concepts. To assist this approach, we developed a specific tutorial guiding the developmental process. We evaluate and validate the effectiveness of the overall pedagogical concept by analyzing the change in attitudes regarding 1) the use of VR/AR for educational purposes and in competencies and content knowledge regarding 2) media didactics and 3) technology. Our results indicate a significant improvement in the knowledge of media didactics and technology. We further report on four STEM learning environments that have been developed during the seminar.

  @article{oberdorfer2021mutual, abstract = {The successful development and classroom integration of Virtual (VR) and Augmented Reality (AR) learning environments requires competencies and content knowledge with respect to media didactics and the respective technologies. The paper discusses a pedagogical concept specifically aiming at the interdisciplinary education of pre-service teachers in collaboration with human-computer interaction students. The students’ overarching goal is the interdisciplinary realization and integration of VR/AR learning environments in teaching and learning concepts. To assist this approach, we developed a specific tutorial guiding the developmental process. We evaluate and validate the effectiveness of the overall pedagogical concept by analyzing the change in attitudes regarding 1) the use of VR/AR for educational purposes and in competencies and content knowledge regarding 2) media didactics and 3) technology. Our results indicate a significant improvement in the knowledge of media didactics and technology. We further report on four STEM learning environments that have been developed during the seminar.}, author = {Oberdörfer, Sebastian and Birnstiel, Sandra and Latoschik, Marc Erich and Grafe, Silke}, journal = {Frontiers in Education}, keywords = {varyfast}, pages = 233, title = {Mutual Benefits: Interdisciplinary Education of Pre-Service Teachers and HCI Students in VR/AR Learning Environment Design}, volume = 6, year = 2021 }
• Self-Avatars in Virtual Reality: A Study Protocol for Investigating the Impact of the Deliberateness of Choice and the Context-Match. Bartl, Andrea; Jung, Sungchul; Kullmann, Peter; Wenninger, Stephan; Achenbach, Jascha; Wolf, Erik; Schell, Christian; Lindeman, Robert W.; Botsch, Mario; Latoschik, Marc Erich. In 2021 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW), pp. 565–566. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The illusion of virtual body ownership (VBO) plays a critical role in virtual reality (VR). VR applications provide a broad design space which includes contextual aspects of the virtual surroundings as well as user-driven deliberate choices of their appearance in VR potentially influencing VBO and other well-known effects of VR. We propose a protocol for an experiment to investigate the influence of deliberateness and context-match on VBO and presence. In a first study, we found significant interactions with the environment. Based on our results we derive recommendations for future experiments.

  @inproceedings{bartl2021selfavatars, abstract = {The illusion of virtual body ownership (VBO) plays a critical role in virtual reality (VR). VR applications provide a broad design space which includes contextual aspects of the virtual surroundings as well as user-driven deliberate choices of their appearance in VR potentially influencing VBO and other well-known effects of VR. We propose a protocol for an experiment to investigate the influence of deliberateness and context-match on VBO and presence. In a first study, we found significant interactions with the environment. Based on our results we derive recommendations for future experiments.}, author = {Bartl, Andrea and Jung, Sungchul and Kullmann, Peter and Wenninger, Stephan and Achenbach, Jascha and Wolf, Erik and Schell, Christian and Lindeman, Robert W. and Botsch, Mario and Latoschik, Marc Erich}, booktitle = {2021 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {vitras}, pages = {565-566}, title = {Self-Avatars in Virtual Reality: A Study Protocol for Investigating the Impact of the Deliberateness of Choice and the Context-Match}, year = 2021 }
• Impostor-Based Rendering Acceleration for Virtual, Augmented, and Mixed Reality. Mišiak, Martin; Fuhrmann, Arnulph; Latoschik, Marc Erich. In Proceedings of the 27th ACM Symposium on Virtual Reality Software and Technology, of VRST ’21. Association for Computing Machinery, Osaka, Japan, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper presents an image-based rendering approach to accelerate rendering time of virtual scenes containing a large number of complex high poly count objects. Our approach replaces complex objects by impostors, light-weight image-based representations leveraging geometry and shading related processing costs. In contrast to their classical implementation, our impostors are specifically designed to work in Virtual-, Augmented- and Mixed Reality scenarios (XR for short), as they support stereoscopic rendering to provide correct depth perception. Motion parallax of typical head movements is compensated by using a ray marched parallax correction step. Our approach provides a dynamic run-time recreation of impostors as necessary for larger changes in view position. The dynamic run-time recreation is decoupled from the actual rendering process. Hence, its associated processing cost is therefore distributed over multiple frames. This avoids any unwanted frame drops or latency spikes even for impostors of objects with complex geometry and many polygons. In addition to the significant performance benefit, our impostors compare favorably against the original mesh representation, as geometric and textural temporal aliasing artifacts are heavily suppressed.

  @inproceedings{misiak2021impostorbased, abstract = {This paper presents an image-based rendering approach to accelerate rendering time of virtual scenes containing a large number of complex high poly count objects. Our approach replaces complex objects by impostors, light-weight image-based representations leveraging geometry and shading related processing costs. In contrast to their classical implementation, our impostors are specifically designed to work in Virtual-, Augmented- and Mixed Reality scenarios (XR for short), as they support stereoscopic rendering to provide correct depth perception. Motion parallax of typical head movements is compensated by using a ray marched parallax correction step. Our approach provides a dynamic run-time recreation of impostors as necessary for larger changes in view position. The dynamic run-time recreation is decoupled from the actual rendering process. Hence, its associated processing cost is therefore distributed over multiple frames. This avoids any unwanted frame drops or latency spikes even for impostors of objects with complex geometry and many polygons. In addition to the significant performance benefit, our impostors compare favorably against the original mesh representation, as geometric and textural temporal aliasing artifacts are heavily suppressed.}, address = {New York, NY, USA}, author = {Mišiak, Martin and Fuhrmann, Arnulph and Latoschik, Marc Erich}, booktitle = {Proceedings of the 27th ACM Symposium on Virtual Reality Software and Technology}, keywords = {myown}, publisher = {Association for Computing Machinery}, series = {VRST '21}, title = {Impostor-Based Rendering Acceleration for Virtual, Augmented, and Mixed Reality}, year = 2021 }
• Machine Learning Model Update Strategies for Hard Disk Drive Failure Prediction. Z{ü}fle, Marwin; Erhard, Florian; Kounev, Samuel. In 20th IEEE International Conference on Machine Learning and Applications (ICMLA). 2021.
  • [ BibTeX ]
  @inproceedings{zufle2021machine, author = {Z{\"u}fle, Marwin and Erhard, Florian and Kounev, Samuel}, booktitle = {20th IEEE International Conference on Machine Learning and Applications (ICMLA)}, keywords = {online_monitoring_and_forecasting}, note = {(to appear)}, title = {Machine Learning Model Update Strategies for Hard Disk Drive Failure Prediction}, year = 2021 }
• Performance Modeling and Analysis of Communication Networks. Tran-Gia, Phuoc; Hoßfeld, Tobias. In . Würzburg University Press, https://modeling.systems/, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  This textbook provides an introduction to common methods of performance modeling and analysis of communication systems. These methods form the basis of traffic engineering, teletraffic theory, and analytical system dimensioning. The fundamentals of probability theory, stochastic processes, Markov processes, and embedded Markov chains are presented. Basic queueing models are described with applications in communication networks. Advanced methods are presented that have been frequently used in recent practice, especially discrete-time analysis algorithms, or which go beyond classical performance measures such as Quality of Experience or energy efficiency. Recent examples of modern communication networks include Software Defined Networking and the Internet of Things. Throughout the book, illustrative examples are used to provide practical experience in performance modeling and analysis. Download: https://modeling.systems/

  @book{info3-book-2021-1, abstract = {This textbook provides an introduction to common methods of performance modeling and analysis of communication systems. These methods form the basis of traffic engineering, teletraffic theory, and analytical system dimensioning. The fundamentals of probability theory, stochastic processes, Markov processes, and embedded Markov chains are presented. Basic queueing models are described with applications in communication networks. Advanced methods are presented that have been frequently used in recent practice, especially discrete-time analysis algorithms, or which go beyond classical performance measures such as Quality of Experience or energy efficiency. Recent examples of modern communication networks include Software Defined Networking and the Internet of Things. Throughout the book, illustrative examples are used to provide practical experience in performance modeling and analysis. Download: https://modeling.systems/}, address = {https://modeling.systems/}, author = {Tran-Gia, Phuoc and Hoßfeld, Tobias}, booktitle = {Performance Modeling and Analysis of Communication Networks}, keywords = {myown}, publisher = {Würzburg University Press}, title = {Performance Modeling and Analysis of Communication Networks}, year = 2021 }
• Extending Partial Representations of Rectangular Duals with Given Contact Orientations. Chaplick, Steven; Kindermann, Philipp; Klawitter, Jonathan; Rutter, Ignaz; Wolff, Alexander. In Proc. 12th International Conference on Algorithms and Complexity (CIAC’21), Vol. 12701 of Lecture Notes in Computer Science, T. Calamoneri, F. Coró (eds.), pp. 340–353. Springer-Verlag, 2021.
  • [ BibTeX ]
  @inproceedings{ckkrw-eprrd-CIAC21, author = {Chaplick, Steven and Kindermann, Philipp and Klawitter, Jonathan and Rutter, Ignaz and Wolff, Alexander}, booktitle = {Proc. 12th International Conference on Algorithms and Complexity (CIAC'21)}, editor = {Calamoneri, Tiziana and Coró, Federico}, keywords = {myown}, pages = {340–353}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Extending Partial Representations of Rectangular Duals with Given Contact Orientations}, volume = 12701, year = 2021 }
• A Case Study on Optimization of Warehouses. Lesch, Veronika; M{ü}ller, Patrick; Kr{ä}mer, Moritz; Kounev, Samuel; Krupitzer, Christian. In arXiv preprint arXiv:2112.12058. 2021.
  • [ BibTeX ]
  @article{lesch2021case, author = {Lesch, Veronika and M{\"u}ller, Patrick and Kr{\"a}mer, Moritz and Kounev, Samuel and Krupitzer, Christian}, journal = {arXiv preprint arXiv:2112.12058}, keywords = {t_journalmagazine}, title = {A Case Study on Optimization of Warehouses}, year = 2021 }
• Challenges and Opportunities of Immersive Technologies for Mindfulness Meditation: A Systematic Review. Döllinger, Nina; Wienrich, Carolin; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 2, p. 29. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Mindfulness is considered an important factor of an individual's subjective well-being. Consequently, Human-Computer Interaction (HCI) has investigated approaches that strengthen mindfulness, i.e., by inventing multimedia technologies to support mindfulness meditation. These approaches often use smartphones, tablets, or consumer-grade desktop systems to allow everyday usage in users' private lives or in the scope of organized therapies. Virtual, Augmented, and Mixed Reality (VR, AR, MR; in short: XR) significantly extend the design space for such approaches. XR covers a wide range of potential sensory stimulation, perceptive and cognitive manipulations, content presentation, interaction, and agency. These facilities are linked to typical XR-specific perceptions that are conceptually closely related to mindfulness research, such as (virtual) presence and (virtual) embodiment. However, a successful exploitation of XR that strengthens mindfulness requires a systematic analysis of the potential interrelation and influencing mechanisms between XR technology, its properties, factors, and phenomena and existing models and theories of the construct of mindfulness. This article reports such a systematic analysis of XR-related research from HCI and life sciences to determine the extent to which existing research frameworks on HCI and mindfulness can be applied to XR technologies, the potential of XR technologies to support mindfulness, and open research gaps. Fifty papers of ACM Digital Library and National Institutes of Health's National Library of Medicine (PubMed) with and without empirical efficacy evaluation were included in our analysis. The results reveal that at the current time, empirical research on XR-based mindfulness support mainly focuses on therapy and therapeutic outcomes. Furthermore, most of the currently investigated XR-supported mindfulness interactions are limited to vocally guided meditations within nature-inspired virtual environments. While an analysis of empirical research on those systems did not reveal differences in mindfulness compared to non-mediated mindfulness practices, various design proposals illustrate that XR has the potential to provide interactive and body-based innovations for mindfulness practice. We propose a structured approach for future work to specify and further explore the potential of XR as mindfulness-support. The resulting framework provides design guidelines for XR-based mindfulness support based on the elements and psychological mechanisms of XR interactions.

  @article{10.3389/frvir.2021.644683, abstract = {Mindfulness is considered an important factor of an individual's subjective well-being. Consequently, Human-Computer Interaction (HCI) has investigated approaches that strengthen mindfulness, i.e., by inventing multimedia technologies to support mindfulness meditation. These approaches often use smartphones, tablets, or consumer-grade desktop systems to allow everyday usage in users' private lives or in the scope of organized therapies. Virtual, Augmented, and Mixed Reality (VR, AR, MR; in short: XR) significantly extend the design space for such approaches. XR covers a wide range of potential sensory stimulation, perceptive and cognitive manipulations, content presentation, interaction, and agency. These facilities are linked to typical XR-specific perceptions that are conceptually closely related to mindfulness research, such as (virtual) presence and (virtual) embodiment. However, a successful exploitation of XR that strengthens mindfulness requires a systematic analysis of the potential interrelation and influencing mechanisms between XR technology, its properties, factors, and phenomena and existing models and theories of the construct of mindfulness. This article reports such a systematic analysis of XR-related research from HCI and life sciences to determine the extent to which existing research frameworks on HCI and mindfulness can be applied to XR technologies, the potential of XR technologies to support mindfulness, and open research gaps. Fifty papers of ACM Digital Library and National Institutes of Health's National Library of Medicine (PubMed) with and without empirical efficacy evaluation were included in our analysis. The results reveal that at the current time, empirical research on XR-based mindfulness support mainly focuses on therapy and therapeutic outcomes. Furthermore, most of the currently investigated XR-supported mindfulness interactions are limited to vocally guided meditations within nature-inspired virtual environments. While an analysis of empirical research on those systems did not reveal differences in mindfulness compared to non-mediated mindfulness practices, various design proposals illustrate that XR has the potential to provide interactive and body-based innovations for mindfulness practice. We propose a structured approach for future work to specify and further explore the potential of XR as mindfulness-support. The resulting framework provides design guidelines for XR-based mindfulness support based on the elements and psychological mechanisms of XR interactions.}, author = {Döllinger, Nina and Wienrich, Carolin and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {vitras}, pages = 29, title = {Challenges and Opportunities of Immersive Technologies for Mindfulness Meditation: A Systematic Review}, volume = 2, year = 2021 }
• Software Testing Strategies for Detecting Hypercall Handlers{\textquotesingle} Aging-related Bugs. Beierlieb, Lukas; Avritzer, Alberto; Ifflander, Lukas; Antunes, Nuno; Milenkoski, Aleksandar; Kounev, Samuel. In 2021 {IEEE} International Symposium on Software Reliability Engineering Workshops ({ISSREW}). {IEEE}, 2021.
  • [ BibTeX ]
  @inproceedings{Beierlieb_2021_SoftwareTestingStrategiesforDetectingHypercallHandlersAgingRelatedBugs, author = {Beierlieb, Lukas and Avritzer, Alberto and Ifflander, Lukas and Antunes, Nuno and Milenkoski, Aleksandar and Kounev, Samuel}, booktitle = {2021 {IEEE} International Symposium on Software Reliability Engineering Workshops ({ISSREW})}, keywords = {security}, publisher = {{IEEE}}, title = {Software Testing Strategies for Detecting Hypercall Handlers{\textquotesingle} Aging-related Bugs}, year = 2021 }
• Software Testing Strategies for Detecting Hypercall Handlers{\textquotesingle} Aging-related Bugs. Beierlieb, Lukas; Avritzer, Alberto; Ifflander, Lukas; Antunes, Nuno; Milenkoski, Aleksandar; Kounev, Samuel. In 2021 {IEEE} International Symposium on Software Reliability Engineering Workshops ({ISSREW}). {IEEE}, 2021.
  • [ BibTeX ]
  @inproceedings{Beierlieb_2021_SoftwareTestingStrategiesforDetectingHypercallHandlersAgingRelatedBugs, author = {Beierlieb, Lukas and Avritzer, Alberto and Ifflander, Lukas and Antunes, Nuno and Milenkoski, Aleksandar and Kounev, Samuel}, booktitle = {2021 {IEEE} International Symposium on Software Reliability Engineering Workshops ({ISSREW})}, keywords = {security}, publisher = {{IEEE}}, title = {Software Testing Strategies for Detecting Hypercall Handlers{\textquotesingle} Aging-related Bugs}, year = 2021 }
• Teaching Software Testing Using Automated Grading. Beierlieb, Lukas; Iffländer, Lukas; Schneider, Tobias; Prantl, Thomas; Kounev, Samuel. In Proceedings of the Fifth Workshop "Automatische Bewertung von Programmieraufgaben" (ABP 2021),virtual event, October 28-29, 2021, A. Greubel, S. Strickroth, M. Striewe (eds.). Gesellschaft für Informatik, 2021.
  • [ BibTeX ]
  @inproceedings{Beierlieb_2021_TeachingSoftwareTestingUsingAutomatedGrading, author = {Beierlieb, Lukas and Iffländer, Lukas and Schneider, Tobias and Prantl, Thomas and Kounev, Samuel}, booktitle = {Proceedings of the Fifth Workshop "Automatische Bewertung von Programmieraufgaben" (ABP 2021),virtual event, October 28-29, 2021}, editor = {Greubel, André and Strickroth, Sven and Striewe, Michael}, keywords = {teaching}, publisher = {Gesellschaft für Informatik}, title = {Teaching Software Testing Using Automated Grading}, year = 2021 }
• Buzzy: Towards Realistic DBMS Benchmarking via Tailored, Representative, Synthetic Workloads. Domaschka, Jörg; Eismann, Simon; Leznik, Mark; Grohmann, Johannes; Kounev, Samuel; Seybold, Daniel. In Companion of the ACM/SPEC International Conference on Performance Engineering, Vol. ICPE ’21, pp. 175–178. Association for Computing Machinery, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Distributed Database Management Systems (DBMS) are a crucial component of modern IT applications. Understanding their performance and non-functional properties is of paramount importance. Yet, benchmarking distributed DBMS has proven to be difficult in practice. Either, a realistic workload is often mapped to a synthetic workload without knowing if this mapping is correct or available workload traces are replayed. While the latter approach provides more realistic results, real-world traces are hard to obtain and their scope is limited in time scale and variance.We propose collecting real-world traces and then applying data generation techniques to synthesize similar realistic traces based on it. Based in this approach, we can obtain workloads for benchmarking, exhibit variability with respect to different aspects of interest while still being similar to the original traces. Varying generation parameters, we are able to support benchmarking what-if scenarios with hypothetical workloads and introduced anomalies.

  @inproceedings{domaschka2021buzzy, abstract = {Distributed Database Management Systems (DBMS) are a crucial component of modern IT applications. Understanding their performance and non-functional properties is of paramount importance. Yet, benchmarking distributed DBMS has proven to be difficult in practice. Either, a realistic workload is often mapped to a synthetic workload without knowing if this mapping is correct or available workload traces are replayed. While the latter approach provides more realistic results, real-world traces are hard to obtain and their scope is limited in time scale and variance.We propose collecting real-world traces and then applying data generation techniques to synthesize similar realistic traces based on it. Based in this approach, we can obtain workloads for benchmarking, exhibit variability with respect to different aspects of interest while still being similar to the original traces. Varying generation parameters, we are able to support benchmarking what-if scenarios with hypothetical workloads and introduced anomalies.}, address = {New York, NY, USA}, author = {Domaschka, Jörg and Eismann, Simon and Leznik, Mark and Grohmann, Johannes and Kounev, Samuel and Seybold, Daniel}, booktitle = {Companion of the ACM/SPEC International Conference on Performance Engineering}, keywords = {descartes}, pages = {175–178}, publisher = {Association for Computing Machinery}, title = {Buzzy: Towards Realistic DBMS Benchmarking via Tailored, Representative, Synthetic Workloads}, volume = {ICPE '21}, year = 2021 }
• Auswirkungen der COVID-19-Pandemie auf Sportlerinnen und Sportler in Deutschland. Zinner, Christoph; Matzka, Manuel; Leppich, Robert; Kounev, Samuel; Holmberg, Hans-Christian; Sperlich, Billy. In 53. asp Jahrestagung. 2021.
  • [ BibTeX ]
  @article{zinner2021auswirkungen, author = {Zinner, Christoph and Matzka, Manuel and Leppich, Robert and Kounev, Samuel and Holmberg, Hans-Christian and Sperlich, Billy}, journal = {53. asp Jahrestagung}, keywords = {t_interdisciplinary}, title = {Auswirkungen der COVID-19-Pandemie auf Sportlerinnen und Sportler in Deutschland}, year = 2021 }
• Performance Evaluation of a Post-Quantum Public-Key Cryptosystem. Prantl, Thomas; Prantl, Dominik; Beierlieb, Lukas; Iffländer, Lukas; Dmitrienko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In 2021 IEEE 40th International Performance Computing and Communications Conference (IPCCC). IEEE, 2021.
  • [ BibTeX ]
  @inproceedings{PrPrBeIfDnKrKo2021-IPCCC-QuantumPublicKeyCryposystem, author = {Prantl, Thomas and Prantl, Dominik and Beierlieb, Lukas and Iffländer, Lukas and Dmitrienko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, booktitle = {2021 IEEE 40th International Performance Computing and Communications Conference (IPCCC)}, keywords = {t_workshop}, organization = {IEEE}, title = {Performance Evaluation of a Post-Quantum Public-Key Cryptosystem}, year = 2021 }
• Semi-Supervised Learning for Grain Size Distribution Interpolation. Kobs, Konstantin; Schäfer, Christian; Steininger, Michael; Krause, Anna; Baumhauer, Roland; Paeth, Heiko; Hotho, Andreas. In Pattern Recognition. ICPR International Workshops and Challenges: Virtual Event, January 10--15, 2021, Proceedings, Part VI, pp. 34–44. Springer International Publishing, 2021.
  • [ BibTeX ]
  @inproceedings{kobs2021semi, author = {Kobs, Konstantin and Schäfer, Christian and Steininger, Michael and Krause, Anna and Baumhauer, Roland and Paeth, Heiko and Hotho, Andreas}, booktitle = {Pattern Recognition. ICPR International Workshops and Challenges: Virtual Event, January 10–15, 2021, Proceedings, Part VI}, keywords = 2021, organization = {Springer International Publishing}, pages = {34–44}, title = {Semi-Supervised Learning for Grain Size Distribution Interpolation}, year = 2021 }
• NeuralPDE: Modelling Dynamical Systems from Data. Dulny, Andrzej; Hotho, Andreas; Krause, Anna. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Many physical processes such as weather phenomena or fluid mechanics are governed by partial differential equations (PDEs). Modelling such dynamical systems using Neural Networks is an emerging research field. However, current methods are restricted in various ways: they require prior knowledge about the governing equations, and are limited to linear or first-order equations. In this work we propose NeuralPDE, a model which combines convolutional neural networks (CNNs) with differentiable ODE solvers to model dynamical systems. We show that the Method of Lines used in standard PDE solvers can be represented using convolutions which makes CNNs the natural choice to parametrize arbitrary PDE dynamics. Our model can be applied to any data without requiring any prior knowledge about the governing PDE. We evaluate NeuralPDE on datasets generated by solving a wide variety of PDEs, covering higher orders, non-linear equations and multiple spatial dimensions.

  @misc{dulny2021neuralpde, abstract = {Many physical processes such as weather phenomena or fluid mechanics are governed by partial differential equations (PDEs). Modelling such dynamical systems using Neural Networks is an emerging research field. However, current methods are restricted in various ways: they require prior knowledge about the governing equations, and are limited to linear or first-order equations. In this work we propose NeuralPDE, a model which combines convolutional neural networks (CNNs) with differentiable ODE solvers to model dynamical systems. We show that the Method of Lines used in standard PDE solvers can be represented using convolutions which makes CNNs the natural choice to parametrize arbitrary PDE dynamics. Our model can be applied to any data without requiring any prior knowledge about the governing PDE. We evaluate NeuralPDE on datasets generated by solving a wide variety of PDEs, covering higher orders, non-linear equations and multiple spatial dimensions.}, author = {Dulny, Andrzej and Hotho, Andreas and Krause, Anna}, keywords = {network}, note = {cite arxiv:2111.07671}, title = {NeuralPDE: Modelling Dynamical Systems from Data}, year = 2021 }
• Detecting Presence Of Speech In Acoustic Data Obtained From Beehives. Janetzky, Pascal; Davidson, Padraig; Steininger, Michael; Krause, Anna; Hotho, Andreas. In Proceedings of the 6th Workshop on Detection and Classification of Acoustic Scenes and Events 2021 {(DCASE} 2021), Online, November 15-19, 2021, F. Font, A. Mesaros, D. P. W. Ellis, E. Fonseca, M. Fuentes, B. Elizalde (eds.), pp. 26–30. 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{janetzky2021detecting, author = {Janetzky, Pascal and Davidson, Padraig and Steininger, Michael and Krause, Anna and Hotho, Andreas}, booktitle = {Proceedings of the 6th Workshop on Detection and Classification of Acoustic Scenes and Events 2021 {(DCASE} 2021), Online, November 15-19, 2021}, editor = {Font, Frederic and Mesaros, Annamaria and Ellis, Daniel P. W. and Fonseca, Eduardo and Fuentes, Magdalena and Elizalde, Benjamin}, keywords = 2021, pages = {26–30}, title = {Detecting Presence Of Speech In Acoustic Data Obtained From Beehives}, year = 2021 }
• Systems Benchmarking. Kounev, Samuel. 2021.
  • [ BibTeX ]
  @presentation{kounev2021systems, author = {Kounev, Samuel}, keywords = {descartes}, title = {Systems Benchmarking}, year = 2021 }
• Using the Metro-Map Metaphor for Drawing Hypergraphs. Frank, Fabian; Kaufmann, Michael; Kobourov, Stephen; Mchedlidze, Tamara; Pupyrev, Sergey; Ueckerdt, Torsten; Wolff, Alexander. In Proc. 47th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM’21), Vol. 12607 of Lecture Notes in Computer Science, T. Bureš, R. Dondi, J. Gamper, G. Guerrini, T. Jurdziński, C. Pahl, F. Sikora, P. Wong (eds.), pp. 361–372. Springer-Verlag, 2021.
  • [ BibTeX ]
  @inproceedings{fkkmpuw-ummmdh-SOFSEM21, author = {Frank, Fabian and Kaufmann, Michael and Kobourov, Stephen and Mchedlidze, Tamara and Pupyrev, Sergey and Ueckerdt, Torsten and Wolff, Alexander}, booktitle = {Proc. 47th Int. Conf. Current Trends Theory \& Practice Comput. Sci. (SOFSEM'21)}, editor = {Bureš, Tomáš and Dondi, Riccardo and Gamper, Johann and Guerrini, Giovanna and Jurdziński, Tomasz and Pahl, Claus and Sikora, Florian and Wong, Prudence}, keywords = {myown}, pages = {361–372}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Using the Metro-Map Metaphor for Drawing Hypergraphs}, volume = 12607, year = 2021 }
• Comparing Methods to Visualize Orientation of Photographs: A User Study. Bruschke, Jonas; Wacker, Markus; Niebling, Florian. In Research and Education in Urban History in the Age of Digital Libraries, F. Niebling, S. Münster, H. Messemer (eds.), pp. 129–151. Springer International Publishing, Cham, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  We present methods to visualize characteristics in collections of historical photographs, especially focusing on the presentation of spatial position and orientation of photographs in relation to the buildings they depict. The developed methods were evaluated and compared in a user study focusing on their appropriateness to gain insight into specific research questions of art historians: 1) which buildings have been depicted most often in a collection of images, 2) which positions have been preferred by photographers to take pictures of a given building, 3) what is the main perspective of photographers regarding a specific building. To analyze spatial datasets of photographs, we have adapted related methods used in the visualization of fluid dynamics. As these existing visualization methods are not suitable in all photographic situations---especially when a multitude of photographs are pointing into diverging directions---we have developed additional cluster-based approaches that aim to overcome these issues. Our user study shows that the introduced cluster-based visualizations can elicit a better understanding of large photographic datasets concerning real-world research questions in certain situations, while performing comparably well in situations where existing methods are already adequate.

  @inproceedings{10.1007/978-3-030-93186-5_6, abstract = {We present methods to visualize characteristics in collections of historical photographs, especially focusing on the presentation of spatial position and orientation of photographs in relation to the buildings they depict. The developed methods were evaluated and compared in a user study focusing on their appropriateness to gain insight into specific research questions of art historians: 1) which buildings have been depicted most often in a collection of images, 2) which positions have been preferred by photographers to take pictures of a given building, 3) what is the main perspective of photographers regarding a specific building. To analyze spatial datasets of photographs, we have adapted related methods used in the visualization of fluid dynamics. As these existing visualization methods are not suitable in all photographic situations—especially when a multitude of photographs are pointing into diverging directions—we have developed additional cluster-based approaches that aim to overcome these issues. Our user study shows that the introduced cluster-based visualizations can elicit a better understanding of large photographic datasets concerning real-world research questions in certain situations, while performing comparably well in situations where existing methods are already adequate.}, address = {Cham}, author = {Bruschke, Jonas and Wacker, Markus and Niebling, Florian}, booktitle = {Research and Education in Urban History in the Age of Digital Libraries}, editor = {Niebling, Florian and Münster, Sander and Messemer, Heike}, keywords = {histstadt4d}, pages = {129–151}, publisher = {Springer International Publishing}, title = {Comparing Methods to Visualize Orientation of Photographs: A User Study}, year = 2021 }
• A Systematic Review of Physiological Measurements, Factors, Methods, and Applications in Virtual Reality. Halbig, Andreas; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 2, p. 89. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Measurements of physiological parameters provide an objective, often non-intrusive, and (at least semi-)automatic evaluation and utilization of user behavior. In addition, specific hardware devices of Virtual Reality (VR) often ship with built-in sensors, i.e. eye-tracking and movements sensors. Hence, the combination of physiological measurements and VR applications seems promising. Several approaches have investigated the applicability and benefits of this combination for various fields of applications. However, the range of possible application fields, coupled with potentially useful and beneficial physiological parameters, types of sensor, target variables and factors, and analysis approaches and techniques is manifold. This article provides a systematic overview and an extensive state-of-the-art review of the usage of physiological measurements in VR. We identified 1,119 works that make use of physiological measurements in VR. Within these, we identified 32 approaches that focus on the classification of characteristics of experience, common in VR applications. The first part of this review categorizes the 1,119 works by field of application, i.e. therapy, training, entertainment, and communication and interaction, as well as by the specific target factors and variables measured by the physiological parameters. An additional category summarizes general VR approaches applicable to all specific fields of application since they target typical VR qualities. In the second part of this review, we analyze the target factors and variables regarding the respective methods used for an automatic analysis and, potentially, classification. For example, we highlight which measurement setups have been proven to be sensitive enough to distinguish different levels of arousal, valence, anxiety, stress, or cognitive workload in the virtual realm. This work may prove useful for all researchers wanting to use physiological data in VR and who want to have a good overview of prior approaches taken, their benefits and potential drawbacks.

  @article{10.3389/frvir.2021.694567, abstract = {Measurements of physiological parameters provide an objective, often non-intrusive, and (at least semi-)automatic evaluation and utilization of user behavior. In addition, specific hardware devices of Virtual Reality (VR) often ship with built-in sensors, i.e. eye-tracking and movements sensors. Hence, the combination of physiological measurements and VR applications seems promising. Several approaches have investigated the applicability and benefits of this combination for various fields of applications. However, the range of possible application fields, coupled with potentially useful and beneficial physiological parameters, types of sensor, target variables and factors, and analysis approaches and techniques is manifold. This article provides a systematic overview and an extensive state-of-the-art review of the usage of physiological measurements in VR. We identified 1,119 works that make use of physiological measurements in VR. Within these, we identified 32 approaches that focus on the classification of characteristics of experience, common in VR applications. The first part of this review categorizes the 1,119 works by field of application, i.e. therapy, training, entertainment, and communication and interaction, as well as by the specific target factors and variables measured by the physiological parameters. An additional category summarizes general VR approaches applicable to all specific fields of application since they target typical VR qualities. In the second part of this review, we analyze the target factors and variables regarding the respective methods used for an automatic analysis and, potentially, classification. For example, we highlight which measurement setups have been proven to be sensitive enough to distinguish different levels of arousal, valence, anxiety, stress, or cognitive workload in the virtual realm. This work may prove useful for all researchers wanting to use physiological data in VR and who want to have a good overview of prior approaches taken, their benefits and potential drawbacks.}, author = {Halbig, Andreas and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {via-vr}, pages = 89, title = {A Systematic Review of Physiological Measurements, Factors, Methods, and Applications in Virtual Reality}, volume = 2, year = 2021 }
• Social buffering of human fear is shaped by gender, social concern and the presence of real vs virtual agents. Qi, Yanyan; Bruch, Doroth{é}e; Krop, Philipp; Herrmann, Martin J; Latoschik, Marc Erich; Deckert, J{ü}rgen; Hein, Grit. In Translational psychiatry, 11(1), pp. 1–10. Nature Publishing Group, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The presence of a partner can attenuate physiological fear responses, a phenomenon known as social buffering. However, not all individuals are equally sociable. Here we investigated whether social buffering of fear is shaped by sensitivity to social anxiety (social concern) and whether these effects are different in females and males. We collected skin conductance responses (SCRs) and affect ratings of female and male participants when they experienced aversive and neutral sounds alone (alone treatment) or in the presence of an unknown person of the same gender (social treatment). Individual differences in social concern were assessed based on a well-established questionnaire. Our results showed that social concern had a stronger effect on social buffering in females than in males. The lower females scored on social concern, the stronger the SCRs reduction in the social compared to the alone treatment. The effect of social concern on social buffering of fear in females disappeared if participants were paired with a virtual agent instead of a real person. Together, these results showed that social buffering of human fear is shaped by gender and social concern. In females, the presence of virtual agents can buffer fear, irrespective of individual differences in social concern. These findings specify factors that shape the social modulation of human fear, and thus might be relevant for the treatment of anxiety disorders.

  @article{qi2021social, abstract = {The presence of a partner can attenuate physiological fear responses, a phenomenon known as social buffering. However, not all individuals are equally sociable. Here we investigated whether social buffering of fear is shaped by sensitivity to social anxiety (social concern) and whether these effects are different in females and males. We collected skin conductance responses (SCRs) and affect ratings of female and male participants when they experienced aversive and neutral sounds alone (alone treatment) or in the presence of an unknown person of the same gender (social treatment). Individual differences in social concern were assessed based on a well-established questionnaire. Our results showed that social concern had a stronger effect on social buffering in females than in males. The lower females scored on social concern, the stronger the SCRs reduction in the social compared to the alone treatment. The effect of social concern on social buffering of fear in females disappeared if participants were paired with a virtual agent instead of a real person. Together, these results showed that social buffering of human fear is shaped by gender and social concern. In females, the presence of virtual agents can buffer fear, irrespective of individual differences in social concern. These findings specify factors that shape the social modulation of human fear, and thus might be relevant for the treatment of anxiety disorders.}, author = {Qi, Yanyan and Bruch, Doroth{\'e}e and Krop, Philipp and Herrmann, Martin J and Latoschik, Marc Erich and Deckert, J{\"u}rgen and Hein, Grit}, journal = {Translational psychiatry}, keywords = {myown}, number = 1, pages = {1–10}, publisher = {Nature Publishing Group}, title = {Social buffering of human fear is shaped by gender, social concern and the presence of real vs virtual agents}, volume = 11, year = 2021 }
• Digitale Leseförderung: Konzeption und Evaluation der "Mobilen Leseförderung". Heß, J.; Karageorgos, P.; Richter, T.; Müller, B.; Riedmann, A.; Schaper, P.; Lugrin, B. In Round Table-Session präsentiert auf der Online-Tagung der Fachgruppe Pädagogische Psychologie der Deutschen Gesellschaft für Psychologie (DGPs). 2021.
  • [ BibTeX ]
  @conference{hess2021digitale, author = {Heß, J. and Karageorgos, P. and Richter, T. and Müller, B. and Riedmann, A. and Schaper, P. and Lugrin, B.}, booktitle = {Round Table-Session präsentiert auf der Online-Tagung der Fachgruppe Pädagogische Psychologie der Deutschen Gesellschaft für Psychologie (DGPs)}, keywords = {mi}, title = {Digitale Leseförderung: Konzeption und Evaluation der "Mobilen Leseförderung"}, year = 2021 }
• Towards Adaptive Robotic Tutors in Universities: A Field Study. Donnermann, Melissa; Schaper, Philipp; Lugrin, Birgit. In International Conference on Persuasive Technology (PERSUASIVE 2021). Springer, 2021.
  • [ BibTeX ]
  @inproceedings{donnermann2021towards, author = {Donnermann, Melissa and Schaper, Philipp and Lugrin, Birgit}, booktitle = {International Conference on Persuasive Technology (PERSUASIVE 2021)}, keywords = {mi}, publisher = {Springer}, title = {Towards Adaptive Robotic Tutors in Universities: A Field Study}, year = 2021 }
• Immersive virtual reality during gait rehabilitation increases walking speed and motivation: A usability evaluation with healthy participants and patients with multiple sclerosis and stroke. Winter, Carla; Kern, Florian; Gall, Dominik; Latoschik, Marc Erich; Pauli, Paul; Käthner, Ivo. In Journal of NeuroEngineering and Rehabilitation, 18(68). 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Background. The rehabilitation of gait disorders in multiple sclerosis (MS) and stroke patients is often based on conventional treadmill training. Virtual reality (VR)-based treadmill training can increase motivation and improve therapy outcomes. Objective. The present study aimed at (1) demonstrating the feasibility and acceptance of an immersive virtual reality application (presented via head-mounted display, HMD) for gait rehabilitation with patients, and (2) compare its effects to a semi-immersive presentation (via a monitor) and a conventional treadmill training without VR. Methods and results. 36 healthy participants and 14 persons with MS or stroke participated in each of the three experimental conditions. For both groups, the walking speed in the HMD condition was higher than in treadmill training without VR. Healthy participants reported a higher motivation after the HMD condition as compared with the other conditions. Importantly, no side effects in the sense of simulator sickness occurred and usability ratings were high. Most of the healthy study participants (89 %) and patients (71 %) preferred the HMD-based training among the three conditions and most patients could imagine using it more frequently. Conclusion. The study demonstrated the feasibility of combining a treadmill training with immersive VR. Due to its high usability and low side effects, the immersive system could serve as a valid alternative to conventional treadmill training in gait rehabilitation. It might be particularly suited for patients to improve training motivation and training outcome e. g. the walking speed compared with treadmill training using no or only semi-immersive VR.

  @article{winter2021immersive, abstract = {Background. The rehabilitation of gait disorders in multiple sclerosis (MS) and stroke patients is often based on conventional treadmill training. Virtual reality (VR)-based treadmill training can increase motivation and improve therapy outcomes. Objective. The present study aimed at (1) demonstrating the feasibility and acceptance of an immersive virtual reality application (presented via head-mounted display, HMD) for gait rehabilitation with patients, and (2) compare its effects to a semi-immersive presentation (via a monitor) and a conventional treadmill training without VR. Methods and results. 36 healthy participants and 14 persons with MS or stroke participated in each of the three experimental conditions. For both groups, the walking speed in the HMD condition was higher than in treadmill training without VR. Healthy participants reported a higher motivation after the HMD condition as compared with the other conditions. Importantly, no side effects in the sense of simulator sickness occurred and usability ratings were high. Most of the healthy study participants (89 %) and patients (71 %) preferred the HMD-based training among the three conditions and most patients could imagine using it more frequently. Conclusion. The study demonstrated the feasibility of combining a treadmill training with immersive VR. Due to its high usability and low side effects, the immersive system could serve as a valid alternative to conventional treadmill training in gait rehabilitation. It might be particularly suited for patients to improve training motivation and training outcome e. g. the walking speed compared with treadmill training using no or only semi-immersive VR.}, author = {Winter, Carla and Kern, Florian and Gall, Dominik and Latoschik, Marc Erich and Pauli, Paul and Käthner, Ivo}, journal = {Journal of NeuroEngineering and Rehabilitation}, keywords = {homecoming}, number = 68, title = {Immersive virtual reality during gait rehabilitation increases walking speed and motivation: A usability evaluation with healthy participants and patients with multiple sclerosis and stroke}, volume = 18, year = 2021 }
• Comparing a Robotic Storyteller versus Audio Book with Integration of Sound Effects and Background Music. Steinhaeusser, Sophia C.; Schaper, Philipp; Lugrin, Birgit. In Companion of the 2021 ACM/IEEE International Conference on Human-Robot Interaction (HRI 2021), C. Bethel, A. Paiva, E. Broadbent, D. Feil-Seifer, D. Szafir (eds.). ACM, 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Steinhaeusser_2021, author = {Steinhaeusser, Sophia C. and Schaper, Philipp and Lugrin, Birgit}, booktitle = {Companion of the 2021 ACM/IEEE International Conference on Human-Robot Interaction (HRI 2021)}, editor = {Bethel, Cindy and Paiva, Ana and Broadbent, Elizabeth and Feil-Seifer, David and Szafir, Daniel}, keywords = {steinhaeusser}, publisher = {ACM}, title = {Comparing a Robotic Storyteller versus Audio Book with Integration of Sound Effects and Background Music}, year = 2021 }
• 3D Printing an Accessory Dock for XR Controllers and its Exemplary Use as XR Stylus. Kern, Florian; Popp, Matthias; Kullmann, Peter; Ganal, Elisabeth; Latoschik, Marc Erich. In 27th ACM Symposium on Virtual Reality Software and Technology, of VRST ’21, pp. 1–3. Association for Computing Machinery, Osaka, Japan, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This article introduces the accessory dock, a 3D printed multipurpose extension for consumer-grade XR controllers that enables flexible mounting of self-made and commercial accessories. The uniform design of our concept opens new opportunities for XR systems being used for more diverse purposes, e.g., researchers and practitioners could use and compare arbitrary XR controllers within their experiments while ensuring access to buttons and battery housing. As a first example, we present a stylus tip accessory to build an XR Stylus, which can be directly used with frameworks for handwriting, sketching, and UI interaction on physically aligned virtual surfaces. For new XR controllers, we provide instructions on how to adjust the accessory dock to the controller’s form factor. A video tutorial for the construction and the source files for 3D printing are publicly available for reuse, replication, and extension (https://go.uniwue.de/hci-otss-accessory-dock).

  @inproceedings{kern2021printing, abstract = {This article introduces the accessory dock, a 3D printed multipurpose extension for consumer-grade XR controllers that enables flexible mounting of self-made and commercial accessories. The uniform design of our concept opens new opportunities for XR systems being used for more diverse purposes, e.g., researchers and practitioners could use and compare arbitrary XR controllers within their experiments while ensuring access to buttons and battery housing. As a first example, we present a stylus tip accessory to build an XR Stylus, which can be directly used with frameworks for handwriting, sketching, and UI interaction on physically aligned virtual surfaces. For new XR controllers, we provide instructions on how to adjust the accessory dock to the controller’s form factor. A video tutorial for the construction and the source files for 3D printing are publicly available for reuse, replication, and extension (https://go.uniwue.de/hci-otss-accessory-dock).}, address = {Osaka, Japan}, author = {Kern, Florian and Popp, Matthias and Kullmann, Peter and Ganal, Elisabeth and Latoschik, Marc Erich}, booktitle = {27th ACM Symposium on Virtual Reality Software and Technology}, keywords = {vilearn}, pages = {1-3}, publisher = {Association for Computing Machinery}, series = {VRST '21}, title = {3D Printing an Accessory Dock for XR Controllers and its Exemplary Use as XR Stylus}, year = 2021 }
• Using Hand Tracking and Voice Commands to Physically Align Virtual Surfaces in AR for Handwriting and Sketching with HoloLens 2. Kern, Florian; Keser, Thore; Niebling, Florian; Latoschik, Marc Erich. In 27th ACM Symposium on Virtual Reality Software and Technology, of VRST ’21, pp. 1–3. Association for Computing Machinery, Osaka, Japan, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In this paper, we adapt an existing VR framework for handwriting and sketching on physically aligned virtual surfaces to AR environments using the Microsoft HoloLens 2. We demonstrate a multimodal input metaphor to control the framework’s calibration features using hand tracking and voice commands. Our technical evaluation of fingertip/surface accuracy and precision on physical tables and walls is in line with existing measurements on comparable hardware, albeit considerably lower compared to previous work using controller-based VR devices. We discuss design considerations and the benefits of our unified input metaphor suitable for controller tracking and hand tracking systems. We encourage extensions and replication by providing a publicly available reference implementation (https://go.uniwue.de/hci-otss-hololens).

  @inproceedings{kern2021using, abstract = {In this paper, we adapt an existing VR framework for handwriting and sketching on physically aligned virtual surfaces to AR environments using the Microsoft HoloLens 2. We demonstrate a multimodal input metaphor to control the framework’s calibration features using hand tracking and voice commands. Our technical evaluation of fingertip/surface accuracy and precision on physical tables and walls is in line with existing measurements on comparable hardware, albeit considerably lower compared to previous work using controller-based VR devices. We discuss design considerations and the benefits of our unified input metaphor suitable for controller tracking and hand tracking systems. We encourage extensions and replication by providing a publicly available reference implementation (https://go.uniwue.de/hci-otss-hololens).}, address = {Osaka, Japan}, author = {Kern, Florian and Keser, Thore and Niebling, Florian and Latoschik, Marc Erich}, booktitle = {27th ACM Symposium on Virtual Reality Software and Technology}, keywords = {niebling}, note = {Best poster award. 🏆}, pages = {1-3}, publisher = {Association for Computing Machinery}, series = {VRST '21}, title = {Using Hand Tracking and Voice Commands to Physically Align Virtual Surfaces in AR for Handwriting and Sketching with HoloLens 2}, year = 2021 }
• Game-Ready Inventory Systems for Virtual Reality. Mußmann, Marc; Truman, Samuel; von Mammen, Sebastian. In IEEE COG 2021, 2021. 2021.
  • [ BibTeX ]
  • [ URL ]
  @article{mussmann2021gameready, author = {Mußmann, Marc and Truman, Samuel and von Mammen, Sebastian}, journal = {IEEE COG 2021}, keywords = {via-vr}, note = {Best student paper award 🏆}, title = {Game-Ready Inventory Systems for Virtual Reality}, volume = 2021, year = 2021 }
• Interactive Self-Assembling Agent Ensembles. Truman, Samuel; von Mammen, Sebastian. In Proceedings of the 1st Games Technology Summit. 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{TrumanvonMammen2021, author = {Truman, Samuel and von Mammen, Sebastian}, booktitle = {Proceedings of the 1st Games Technology Summit}, keywords = {myown}, title = {Interactive Self-Assembling Agent Ensembles}, year = 2021 }
• Introduction to Socially Interactive Agents. Lugrin, Birgit. In The Handbook on Socially Interactive Agents – 20 Years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics, Volume 1: Methods, Behavior, Cognition, B. Lugrin, C. Pelachaud, D. Traum (eds.), pp. 1–20. ACM, 2021.
  • [ BibTeX ]
  • [ URL ]
  @incollection{Lugrin_2021, author = {Lugrin, Birgit}, booktitle = {The Handbook on Socially Interactive Agents – 20 Years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics, Volume 1: Methods, Behavior, Cognition}, editor = {Lugrin, Birgit and Pelachaud, Catherine and Traum, David}, keywords = {MI}, pages = {1-20}, publisher = {ACM}, title = {Introduction to Socially Interactive Agents}, year = 2021 }
• Adjacency Graphs of Polyhedral Surfaces. Arseneva, Elena; Kleist, Linda; Klemz, Boris; Löffler, Maarten; Schulz, André; Vogtenhuber, Birgit; Wolff, Alexander. In Proc. 37th Annu. Sympos. Comput. Geom. (SoCG’21), Vol. 189 of LIPIcs, K. Buchin, Éric {Colin de Verdière} (eds.), pp. 11:1–17. Schloss Dagstuhl – Leibniz-Zentrum für Informatik, 2021.
  • [ BibTeX ]
  @inproceedings{akklsvw-dgps-SoCG21, author = {Arseneva, Elena and Kleist, Linda and Klemz, Boris and Löffler, Maarten and Schulz, André and Vogtenhuber, Birgit and Wolff, Alexander}, booktitle = {Proc. 37th Annu. Sympos. Comput. Geom. (SoCG'21)}, editor = {Buchin, Kevin and {Colin de Verdière}, Éric}, keywords = {realizability}, pages = {11:1–17}, publisher = {Schloss Dagstuhl – Leibniz-Zentrum für Informatik}, series = {LIPIcs}, title = {Adjacency Graphs of Polyhedral Surfaces}, volume = 189, year = 2021 }
• WHERE ARE WE NOW ON THE ROAD TO 4D URBAN HISTORY RESEARCH AND DISCOVERY?. Münster, S.; Maiwald, F.; Bruschke, J.; Kröber, C.; Dietz, R.; Messemer, H.; Niebling, F. In ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, VIII-M-1-2021, pp. 109–116. 2021.
  • [ BibTeX ]
  • [ URL ]
  @article{isprs-annals-VIII-M-1-2021-109-2021, author = {Münster, S. and Maiwald, F. and Bruschke, J. and Kröber, C. and Dietz, R. and Messemer, H. and Niebling, F.}, journal = {ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences}, keywords = {histstadt4d}, pages = {109–116}, title = {WHERE ARE WE NOW ON THE ROAD TO 4D URBAN HISTORY RESEARCH AND DISCOVERY?}, volume = {VIII-M-1-2021}, year = 2021 }
• ClusterSets: Optimizing Planar Clusters in Categorical Point Data. Geiger, Jakob; Cornelsen, Sabine; Haunert, Jan-Henrik; Kindermann, Philipp; Mchedlidze, Tamara; Nöllenburg, Martin; Okamoto, Yoshio; Wolff, Alexander. In Comput. Graphics Forum, 40(3), pp. 471–481. 2021.
  • [ BibTeX ]
  @article{gchkmnow-coplc-EuroVis21, author = {Geiger, Jakob and Cornelsen, Sabine and Haunert, Jan-Henrik and Kindermann, Philipp and Mchedlidze, Tamara and Nöllenburg, Martin and Okamoto, Yoshio and Wolff, Alexander}, journal = {Comput. Graphics Forum}, keywords = {myown}, number = 3, pages = {471–481}, title = {ClusterSets: Optimizing Planar Clusters in Categorical Point Data}, volume = 40, year = 2021 }
• Layered Drawing of Undirected Graphs with Generalized Port Constraints. Walter, Julian; Zink, Johannes; Baumeister, Joachim; Wolff, Alexander. In Proc. 28th Int. Symp. Graph Drawing \& Network Vis. (GD’20), Vol. 12590 of Lecture Notes in Computer Science, D. Auber, P. Valtr (eds.), pp. 220–234. Springer-Verlag, 2021.
  • [ BibTeX ]
  @inproceedings{wzbw-ldugg-GD20, author = {Walter, Julian and Zink, Johannes and Baumeister, Joachim and Wolff, Alexander}, booktitle = {Proc. 28th Int. Symp. Graph Drawing \& Network Vis. (GD'20)}, editor = {Auber, David and Valtr, Pavel}, keywords = {myown}, pages = {220–234}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Layered Drawing of Undirected Graphs with Generalized Port Constraints}, volume = 12590, year = 2021 }
• A New Course on Systems Benchmarking-For Scientists and Engineers. Kounev, Samuel. pp. 127–127. 2021.
  • [ BibTeX ]
  • [ URL ]
  @presentation{kounev2021new, author = {Kounev, Samuel}, booktitle = {Companion of the ACM/SPEC International Conference on Performance Engineering}, keywords = {descartes}, pages = {127–127}, title = {A New Course on Systems Benchmarking-For Scientists and Engineers}, year = 2021 }
• The Semantic Web - {ISWC} 2021 - 20th International Semantic Web Conference, {ISWC} 2021, Virtual Event, October 24-28, 2021, Proceedings. Hotho, Andreas; Blomqvist, Eva; Dietze, Stefan; Fokoue, Achille; Ding, Ying; Barnaghi, Payam M.; Haller, Armin; Dragoni, Mauro; Alani, Harith. In Vol. 12922 of Lecture Notes in Computer Science. Springer, 2021.
  • [ BibTeX ]
  • [ URL ]
  @proceedings{DBLP:conf/semweb/2021, editor = {Hotho, Andreas and Blomqvist, Eva and Dietze, Stefan and Fokoue, Achille and Ding, Ying and Barnaghi, Payam M. and Haller, Armin and Dragoni, Mauro and Alani, Harith}, keywords = 2021, publisher = {Springer}, series = {Lecture Notes in Computer Science}, title = {The Semantic Web - {ISWC} 2021 - 20th International Semantic Web Conference, {ISWC} 2021, Virtual Event, October 24-28, 2021, Proceedings}, volume = 12922, year = 2021 }
• Towards Situation-Aware Meta-Optimization of Adaptation Planning Strategies. Lesch, Veronika; Noack, Tanja; Hefter, Johannes; Kounev, Samuel; Krupitzer, Christian. In Proceedings of the 2nd IEEE International Conference on Autonomic Computing and Self-Organizing Systems - ACSOS 2021. IEEE, 2021.
  • [ BibTeX ]
  @inproceedings{lesch2021towards, author = {Lesch, Veronika and Noack, Tanja and Hefter, Johannes and Kounev, Samuel and Krupitzer, Christian}, booktitle = {Proceedings of the 2nd IEEE International Conference on Autonomic Computing and Self-Organizing Systems - ACSOS 2021}, keywords = {internet_of_things}, note = {Best Paper Award Runner Up, Full Paper Acceptance Ratio: 25%}, publisher = {IEEE}, title = {Towards Situation-Aware Meta-Optimization of Adaptation Planning Strategies}, year = 2021 }
• Recommendations for Data-Driven Degradation Estimation with Case Studies from Manufacturing and Dry-Bulk Shipping. Finke, Nils; Mohr, Marisa; Lontke, Alexander; Z{ü}fle, Marwin; Kounev, Samuel; M{ö}ller, Ralf. In Research Challenges in Information Science (RCIS), pp. 189–204. Springer, 2021.
  • [ BibTeX ]
  @inproceedings{finke2021recommendations, author = {Finke, Nils and Mohr, Marisa and Lontke, Alexander and Z{\"u}fle, Marwin and Kounev, Samuel and M{\"o}ller, Ralf}, booktitle = {Research Challenges in Information Science (RCIS)}, keywords = {t_interdisciplinary}, organization = {Springer}, pages = {189–204}, title = {Recommendations for Data-Driven Degradation Estimation with Case Studies from Manufacturing and Dry-Bulk Shipping}, year = 2021 }
• A Case Study on Optimization of Platooning Coordination. Lesch, Veronika; Hadry, Marius; Kounev, Samuel; Krupitzer, Christian. Universit{ä}t W{ü}rzburg and Universit{ä}t Hohenheim, 2021.
  • [ BibTeX ]
  • [ URL ]
  @techreport{lesch2021studyplatooning, author = {Lesch, Veronika and Hadry, Marius and Kounev, Samuel and Krupitzer, Christian}, institution = {Universit{ä}t W{ü}rzburg and Universit{ä}t Hohenheim}, keywords = {t_techreport}, title = {A Case Study on Optimization of Platooning Coordination}, year = 2021 }
• Teaching Software Testing Using Automated Grading. Beierlieb, Lukas; Iffländer, Lukas; Schneider, Tobias; Prantl, Thomas; Kounev, Samuel. In Proceedings of the Fifth Workshop "Automatische Bewertung von Programmieraufgaben" (ABP 2021),virtual event, October 28-29, 2021, A. Greubel, S. Strickroth, M. Striewe (eds.). Gesellschaft für Informatik, 2021.
  • [ BibTeX ]
  @inproceedings{Beierlieb_2021_TeachingSoftwareTestingUsingAutomatedGrading, author = {Beierlieb, Lukas and Iffländer, Lukas and Schneider, Tobias and Prantl, Thomas and Kounev, Samuel}, booktitle = {Proceedings of the Fifth Workshop "Automatische Bewertung von Programmieraufgaben" (ABP 2021),virtual event, October 28-29, 2021}, editor = {Greubel, André and Strickroth, Sven and Striewe, Michael}, keywords = {teaching}, publisher = {Gesellschaft für Informatik}, title = {Teaching Software Testing Using Automated Grading}, year = 2021 }
• ComBench: A Benchmarking Framework for Publish/Subscribe Communication Protocols Under Network Limitations. Herrnleben, Stefan; Leidinger, Maximilian; Lesch, Veronika; Prantl, Thomas; Grohmann, Johannes; Krupitzer, Christian; Kounev, Samuel. In Performance Evaluation Methodologies and Tools, Q. Zhao, L. Xia (eds.), pp. 72–92. Springer International Publishing, Cham, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Efficient and dependable communication is a highly relevant aspect for Internet of Things (IoT) systems in which tiny sensors, actuators, wearables, or other smart devices exchange messages. Various publish/subscribe protocols address the challenges of communication in IoT systems. The selection process of a suitable protocol should consider the communication behavior of the application, the protocol's performance, the resource requirements on the end device, and the network connection quality, as IoT environments often rely on wireless networks. Benchmarking is a common approach to evaluate and compare systems, considering the performance and aspects like dependability or security. In this paper, we present our IoT communication benchmarking framework ComBench for publish/subscribe protocols focusing on constrained networks with varying quality conditions. The benchmarking framework supports system designers, software engineers, and application developers to select and investigate the behavior of communication protocols. Our benchmarking framework contributes to (i) show the impact of fluctuating network quality on communication, (ii) compare multiple protocols, protocol features, and protocol implementations, and (iii) analyze scalability, robustness, and dependability of clients, networks, and brokers in different scenarios. Our case study demonstrates the applicability of our framework to support the decision for the best-suited protocol in various scenarios.

  @inproceedings{10.1007/978-3-030-92511-6_5, abstract = {Efficient and dependable communication is a highly relevant aspect for Internet of Things (IoT) systems in which tiny sensors, actuators, wearables, or other smart devices exchange messages. Various publish/subscribe protocols address the challenges of communication in IoT systems. The selection process of a suitable protocol should consider the communication behavior of the application, the protocol's performance, the resource requirements on the end device, and the network connection quality, as IoT environments often rely on wireless networks. Benchmarking is a common approach to evaluate and compare systems, considering the performance and aspects like dependability or security. In this paper, we present our IoT communication benchmarking framework ComBench for publish/subscribe protocols focusing on constrained networks with varying quality conditions. The benchmarking framework supports system designers, software engineers, and application developers to select and investigate the behavior of communication protocols. Our benchmarking framework contributes to (i) show the impact of fluctuating network quality on communication, (ii) compare multiple protocols, protocol features, and protocol implementations, and (iii) analyze scalability, robustness, and dependability of clients, networks, and brokers in different scenarios. Our case study demonstrates the applicability of our framework to support the decision for the best-suited protocol in various scenarios.}, address = {Cham}, author = {Herrnleben, Stefan and Leidinger, Maximilian and Lesch, Veronika and Prantl, Thomas and Grohmann, Johannes and Krupitzer, Christian and Kounev, Samuel}, booktitle = {Performance Evaluation Methodologies and Tools}, editor = {Zhao, Qianchuan and Xia, Li}, keywords = {networking}, pages = {72–92}, publisher = {Springer International Publishing}, title = {ComBench: A Benchmarking Framework for Publish/Subscribe Communication Protocols Under Network Limitations}, year = 2021 }
• ComBench: A Benchmarking Framework for Publish/Subscribe Communication Protocols Under Network Limitations. Herrnleben, Stefan; Leidinger, Maximilian; Lesch, Veronika; Prantl, Thomas; Grohmann, Johannes; Krupitzer, Christian; Kounev, Samuel. In Performance Evaluation Methodologies and Tools, Q. Zhao, L. Xia (eds.), pp. 72–92. Springer International Publishing, Cham, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Efficient and dependable communication is a highly relevant aspect for Internet of Things (IoT) systems in which tiny sensors, actuators, wearables, or other smart devices exchange messages. Various publish/subscribe protocols address the challenges of communication in IoT systems. The selection process of a suitable protocol should consider the communication behavior of the application, the protocol's performance, the resource requirements on the end device, and the network connection quality, as IoT environments often rely on wireless networks. Benchmarking is a common approach to evaluate and compare systems, considering the performance and aspects like dependability or security. In this paper, we present our IoT communication benchmarking framework ComBench for publish/subscribe protocols focusing on constrained networks with varying quality conditions. The benchmarking framework supports system designers, software engineers, and application developers to select and investigate the behavior of communication protocols. Our benchmarking framework contributes to (i) show the impact of fluctuating network quality on communication, (ii) compare multiple protocols, protocol features, and protocol implementations, and (iii) analyze scalability, robustness, and dependability of clients, networks, and brokers in different scenarios. Our case study demonstrates the applicability of our framework to support the decision for the best-suited protocol in various scenarios.

  @inproceedings{10.1007/978-3-030-92511-6_5, abstract = {Efficient and dependable communication is a highly relevant aspect for Internet of Things (IoT) systems in which tiny sensors, actuators, wearables, or other smart devices exchange messages. Various publish/subscribe protocols address the challenges of communication in IoT systems. The selection process of a suitable protocol should consider the communication behavior of the application, the protocol's performance, the resource requirements on the end device, and the network connection quality, as IoT environments often rely on wireless networks. Benchmarking is a common approach to evaluate and compare systems, considering the performance and aspects like dependability or security. In this paper, we present our IoT communication benchmarking framework ComBench for publish/subscribe protocols focusing on constrained networks with varying quality conditions. The benchmarking framework supports system designers, software engineers, and application developers to select and investigate the behavior of communication protocols. Our benchmarking framework contributes to (i) show the impact of fluctuating network quality on communication, (ii) compare multiple protocols, protocol features, and protocol implementations, and (iii) analyze scalability, robustness, and dependability of clients, networks, and brokers in different scenarios. Our case study demonstrates the applicability of our framework to support the decision for the best-suited protocol in various scenarios.}, address = {Cham}, author = {Herrnleben, Stefan and Leidinger, Maximilian and Lesch, Veronika and Prantl, Thomas and Grohmann, Johannes and Krupitzer, Christian and Kounev, Samuel}, booktitle = {Performance Evaluation Methodologies and Tools}, editor = {Zhao, Qianchuan and Xia, Li}, keywords = {networking}, pages = {72–92}, publisher = {Springer International Publishing}, title = {ComBench: A Benchmarking Framework for Publish/Subscribe Communication Protocols Under Network Limitations}, year = 2021 }
• Spatial Presence in Mixed Realities--Considerations about the Concept, Measures, Design, and Experiments. Wienrich, Carolin; Komma, Philipp; Vogt, Stephanie; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 2, R. Skarbez (ed.), p. 141. Frontiers, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Plenty of theories, models, measures, and investigations target the understanding of virtual presence, i.e., the sense of presence in immersive Virtual Reality (VR). Other varieties of the so-called eXtended Realities (XR), e.g., Augmented and Mixed Reality (AR and MR) incorporate immersive features to a lesser degree and continuously combine spatial cues from the real physical space and the simulated virtual space. This blurred separation questions the applicability of the accumulated knowledge about the similarities of virtual presence and presence occurring in other varieties of XR, and corresponding outcomes. The present work bridges this gap by analyzing the construct of presence in mixed realities (MR). To achieve this, the following presents (1) a short review of definitions, dimensions, and measurements of presence in VR, and (2) the state of the art views on MR. Additionally, we (3) derived a working definition of MR, extending the Milgram continuum. This definition is based on entities reaching from real to virtual manifestations at one time point. Entities possess different degrees of referential power, determining the selection of the frame of reference. Furthermore, we (4) identified three research desiderata, including research questions about the frame of reference, the corresponding dimension of transportation, and the dimension of realism in MR. Mainly the relationship between the main aspects of virtual presence of immersive VR, i.e., the place-illusion, and the plausibility-illusion, and of the referential power of MR entities are discussed regarding the concept, measures, and design of presence in MR. Finally, (5) we suggested an experimental setup to reveal the research heuristic behind experiments investigating presence in MR. The present work contributes to the theories and the meaning of and approaches to simulate and measure presence in MR. We hypothesize that research about essential underlying factors determining user experience (UX) in MR simulations and experiences is still in its infancy and hopes this article provides an encouraging starting point to tackle related questions.

  @article{wienrichspatial, abstract = {Plenty of theories, models, measures, and investigations target the understanding of virtual presence, i.e., the sense of presence in immersive Virtual Reality (VR). Other varieties of the so-called eXtended Realities (XR), e.g., Augmented and Mixed Reality (AR and MR) incorporate immersive features to a lesser degree and continuously combine spatial cues from the real physical space and the simulated virtual space. This blurred separation questions the applicability of the accumulated knowledge about the similarities of virtual presence and presence occurring in other varieties of XR, and corresponding outcomes. The present work bridges this gap by analyzing the construct of presence in mixed realities (MR). To achieve this, the following presents (1) a short review of definitions, dimensions, and measurements of presence in VR, and (2) the state of the art views on MR. Additionally, we (3) derived a working definition of MR, extending the Milgram continuum. This definition is based on entities reaching from real to virtual manifestations at one time point. Entities possess different degrees of referential power, determining the selection of the frame of reference. Furthermore, we (4) identified three research desiderata, including research questions about the frame of reference, the corresponding dimension of transportation, and the dimension of realism in MR. Mainly the relationship between the main aspects of virtual presence of immersive VR, i.e., the place-illusion, and the plausibility-illusion, and of the referential power of MR entities are discussed regarding the concept, measures, and design of presence in MR. Finally, (5) we suggested an experimental setup to reveal the research heuristic behind experiments investigating presence in MR. The present work contributes to the theories and the meaning of and approaches to simulate and measure presence in MR. We hypothesize that research about essential underlying factors determining user experience (UX) in MR simulations and experiences is still in its infancy and hopes this article provides an encouraging starting point to tackle related questions.}, author = {Wienrich, Carolin and Komma, Philipp and Vogt, Stephanie and Latoschik, Marc Erich}, editor = {Skarbez, Richard}, journal = {Frontiers in Virtual Reality}, keywords = {c.wienrich}, pages = 141, publisher = {Frontiers}, title = {Spatial Presence in Mixed Realities–Considerations about the Concept, Measures, Design, and Experiments}, volume = 2, year = 2021 }
• A Systematic Review of Foreign Language Learning with Immersive Technologies (2001-2020). Hein, Rebecca Magdalena; Wienrich, Carolin; Latoschik, Marc Erich. In AIMS Electronics and Electrical Engineering, 5(2), pp. 117–145. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This study provides a systematic literature review of research (2001–2020) in the field of teaching and learning a foreign language and intercultural learning using immersive technologies. Based on 2507 sources, 54 articles were selected according to a predefined selection criteria. The review is aimed at providing information about which immersive interventions are being used for foreign language learning and teaching and where potential research gaps exist. The papers were analyzed and coded according to the following categories: (1) investigation form and education level, (2) degree of immersion, and technology used, (3) predictors, and (4) criterions. The review identified key research findings relating the use of immersive technologies for learning and teaching a foreign language and intercultural learning at cognitive, affective, and conative levels. The findings revealed research gaps in the area of teachers as a target group, and virtual reality (VR) as a fully immersive intervention form. Furthermore, the studies reviewed rarely examined behavior, and implicit measurements related to inter- and trans-cultural learning and teaching. Inter- and transcultural learning and teaching especially is an underrepresented investigation subject. Finally, concrete suggestions for future research are given. The systematic review contributes to the challenge of interdisciplinary cooperation between pedagogy, foreign language didactics, and Human-Computer Interaction to achieve innovative teaching-learning formats and a successful digital transformation.

  @article{noauthororeditor, abstract = {This study provides a systematic literature review of research (2001–2020) in the field of teaching and learning a foreign language and intercultural learning using immersive technologies. Based on 2507 sources, 54 articles were selected according to a predefined selection criteria. The review is aimed at providing information about which immersive interventions are being used for foreign language learning and teaching and where potential research gaps exist. The papers were analyzed and coded according to the following categories: (1) investigation form and education level, (2) degree of immersion, and technology used, (3) predictors, and (4) criterions. The review identified key research findings relating the use of immersive technologies for learning and teaching a foreign language and intercultural learning at cognitive, affective, and conative levels. The findings revealed research gaps in the area of teachers as a target group, and virtual reality (VR) as a fully immersive intervention form. Furthermore, the studies reviewed rarely examined behavior, and implicit measurements related to inter- and trans-cultural learning and teaching. Inter- and transcultural learning and teaching especially is an underrepresented investigation subject. Finally, concrete suggestions for future research are given. The systematic review contributes to the challenge of interdisciplinary cooperation between pedagogy, foreign language didactics, and Human-Computer Interaction to achieve innovative teaching-learning formats and a successful digital transformation.}, author = {Hein, Rebecca Magdalena and Wienrich, Carolin and Latoschik, Marc Erich}, journal = {AIMS Electronics and Electrical Engineering}, keywords = {coteach}, number = 2, pages = {117-145}, title = {A Systematic Review of Foreign Language Learning with Immersive Technologies (2001-2020)}, volume = 5, year = 2021 }
• The Impact of Implicit and Explicit Feedback on Performance and Experience during VR-Supported Motor Rehabilitation. Hamzeheinejad, Negin; Roth, Daniel; Monty, Samantha; Breuer, Julian; Rodenberg, Anuschka; Latoschik, Marc Erich. In 2021 IEEE Virtual Reality and 3D User Interfaces (VR), pp. 382–391. IEEE, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper examines the impact of implicit and explicit feedback in Virtual Reality (VR) on performance and user experience during motor rehabilitation. In this work, explicit feedback consists of visual and auditory cues provided by a virtual trainer, compared to traditional feedback provided by a real physiotherapist. Implicit feedback was generated by the walking motion of the virtual trainer accompanying the patient during virtual walks. Here, the potential synchrony of movements between the trainer and trainee is intended to create an implicit visual affordance of motion adaption. We hypothesize that this will stimulate the activation of mirror neurons, thus fostering neuroadaptive processes. We conducted a clinical user study in a rehabilitation center employing a gait robot. We investigated the performance outcome and subjective experience of four resulting VR-supported rehabilitation conditions: with/without explicit feedback, and with/without implicit (synchronous motion) stimulation by a virtual trainer. We further included two baseline conditions reflecting the current NonVR procedure in the rehabilitation center. Our results show that additional feedback generally resulted in better patient performance, objectively assessed by the necessary applied support force of the robot. Additionally, our VR supported rehabilitation procedure improved enjoyment and satisfaction, while no negative impacts could be observed. Implicit feedback and adapted motion synchrony by the virtual trainer led to higher mental demand, giving rise to hopes of increased neural activity and neuroadaptive stimulation.

  @inproceedings{hamzeheinejad2021impact, abstract = {This paper examines the impact of implicit and explicit feedback in Virtual Reality (VR) on performance and user experience during motor rehabilitation. In this work, explicit feedback consists of visual and auditory cues provided by a virtual trainer, compared to traditional feedback provided by a real physiotherapist. Implicit feedback was generated by the walking motion of the virtual trainer accompanying the patient during virtual walks. Here, the potential synchrony of movements between the trainer and trainee is intended to create an implicit visual affordance of motion adaption. We hypothesize that this will stimulate the activation of mirror neurons, thus fostering neuroadaptive processes. We conducted a clinical user study in a rehabilitation center employing a gait robot. We investigated the performance outcome and subjective experience of four resulting VR-supported rehabilitation conditions: with/without explicit feedback, and with/without implicit (synchronous motion) stimulation by a virtual trainer. We further included two baseline conditions reflecting the current NonVR procedure in the rehabilitation center. Our results show that additional feedback generally resulted in better patient performance, objectively assessed by the necessary applied support force of the robot. Additionally, our VR supported rehabilitation procedure improved enjoyment and satisfaction, while no negative impacts could be observed. Implicit feedback and adapted motion synchrony by the virtual trainer led to higher mental demand, giving rise to hopes of increased neural activity and neuroadaptive stimulation.}, author = {Hamzeheinejad, Negin and Roth, Daniel and Monty, Samantha and Breuer, Julian and Rodenberg, Anuschka and Latoschik, Marc Erich}, booktitle = {2021 IEEE Virtual Reality and 3D User Interfaces (VR)}, keywords = {vrgait}, pages = {382-391}, publisher = {IEEE}, title = {The Impact of Implicit and Explicit Feedback on Performance and Experience during VR-Supported Motor Rehabilitation}, year = 2021 }
• Development of the InteractionSuitcase in virtual reality to support inter- and transcultural learning processes in English as Foreign Language education. Hein, Rebecca; Steinbock, Jeanine; Eisenmann, Maria; Latoschik, Marc Erich; Wienrich, Carolin. In DELFI 2021, A. Kienle, A. Harrer, J. M. Haake, A. Lingnau (eds.), pp. 91–96. Gesellschaft für Informatik e.V., Bonn, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Immersion programs and the experiences they offer learners are irreplaceable. In times of Covid-19, social VR applications can offer enormous potential for the acquisition of inter- and transcultural competencies (ITC). Virtual objects (VO) could initiate communication and reflection processes between learners with different cultural backgrounds and therefore offer an exciting approach. Accordingly, we address the following research questions: (1) What is a sound way to collect objects for the InteractionSuitcase to promote ITC acquisition by means of Social VR? (2) For which aspects do students use the objects when developing an ITC learning scenario? (3) Which VO are considered particularly supportive to initiate and facilitate ITC learning? To answer these research questions, the virtual InteractionSuitcase will be designed and implemented. This paper presents the empirical preliminary work and interim results of the development and evaluation of the InteractionSuitcase, its usage, and the significance of this project for Human- Computer Interaction (HCI) and English as Foreign Language (EFL) research.

  @inproceedings{hein2021development, abstract = {Immersion programs and the experiences they offer learners are irreplaceable. In times of Covid-19, social VR applications can offer enormous potential for the acquisition of inter- and transcultural competencies (ITC). Virtual objects (VO) could initiate communication and reflection processes between learners with different cultural backgrounds and therefore offer an exciting approach. Accordingly, we address the following research questions: (1) What is a sound way to collect objects for the InteractionSuitcase to promote ITC acquisition by means of Social VR? (2) For which aspects do students use the objects when developing an ITC learning scenario? (3) Which VO are considered particularly supportive to initiate and facilitate ITC learning? To answer these research questions, the virtual InteractionSuitcase will be designed and implemented. This paper presents the empirical preliminary work and interim results of the development and evaluation of the InteractionSuitcase, its usage, and the significance of this project for Human- Computer Interaction (HCI) and English as Foreign Language (EFL) research.}, address = {Bonn}, author = {Hein, Rebecca and Steinbock, Jeanine and Eisenmann, Maria and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {DELFI 2021}, editor = {Kienle, Andrea and Harrer, Andreas and Haake, Joerg M. and Lingnau, Andreas}, keywords = {coteach}, pages = {91-96}, publisher = {Gesellschaft für Informatik e.V.}, title = {Development of the InteractionSuitcase in virtual reality to support inter- and transcultural learning processes in English as Foreign Language education}, year = 2021 }
• Towards a digital syllable-based reading intervention: An interview study with second-graders. Schaper, Philipp; Donnermann, Melissa; Doser, Nicole; Lein, Martina; Riedmann, Anna; Steinhaeusser, Sophia C.; Karageorgos, Panagiotis; Müller, Bettina; Richter, Tobias; Lugrin, Birgit. In British HCI Conference 2021 (BCS-HCI 2021). 2021.
  • [ BibTeX ]
  @inproceedings{schaper2021towards, author = {Schaper, Philipp and Donnermann, Melissa and Doser, Nicole and Lein, Martina and Riedmann, Anna and Steinhaeusser, Sophia C. and Karageorgos, Panagiotis and Müller, Bettina and Richter, Tobias and Lugrin, Birgit}, booktitle = {British HCI Conference 2021 (BCS-HCI 2021)}, keywords = {lein}, title = {Towards a digital syllable-based reading intervention: An interview study with second-graders}, year = 2021 }
• Indifferent or Enthusiastic? Virtual Audiences Animation and Perception in Virtual Reality. Glémarec, Yann; Lugrin, Jean-Luc; Bosser, Anne-Gwenn; Collins Jackson, Aryana; Buche, Cédric; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 2, p. 72. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In this paper, we present a virtual audience simulation system for Virtual Reality (VR). The system implements an audience perception model controlling the nonverbal behaviors of virtual spectators, such as facial expressions or postures. Groups of virtual spectators are animated by a set of nonverbal behavior rules representing a particular audience attitude (e.g., indifferent or enthusiastic). Each rule specifies a nonverbal behavior category: posture, head movement, facial expression and gaze direction as well as three parameters: type, frequency and proportion. In a first user-study, we asked participants to pretend to be a speaker in VR and then create sets of nonverbal behaviour parameters to simulate different attitudes. Participants manipulated the nonverbal behaviours of single virtual spectator to match a specific levels of engagement and opinion toward them. In a second user-study, we used these parameters to design different types of virtual audiences with our nonverbal behavior rules and evaluated their perceptions. Our results demonstrate our system’s ability to create virtual audiences with three types of different perceived attitudes: indifferent, critical, enthusiastic. The analysis of the results also lead to a set of recommendations and guidelines regarding attitudes and expressions for future design of audiences for VR therapy and training applications.

  @article{10.3389/frvir.2021.666232, abstract = {In this paper, we present a virtual audience simulation system for Virtual Reality (VR). The system implements an audience perception model controlling the nonverbal behaviors of virtual spectators, such as facial expressions or postures. Groups of virtual spectators are animated by a set of nonverbal behavior rules representing a particular audience attitude (e.g., indifferent or enthusiastic). Each rule specifies a nonverbal behavior category: posture, head movement, facial expression and gaze direction as well as three parameters: type, frequency and proportion. In a first user-study, we asked participants to pretend to be a speaker in VR and then create sets of nonverbal behaviour parameters to simulate different attitudes. Participants manipulated the nonverbal behaviours of single virtual spectator to match a specific levels of engagement and opinion toward them. In a second user-study, we used these parameters to design different types of virtual audiences with our nonverbal behavior rules and evaluated their perceptions. Our results demonstrate our system’s ability to create virtual audiences with three types of different perceived attitudes: indifferent, critical, enthusiastic. The analysis of the results also lead to a set of recommendations and guidelines regarding attitudes and expressions for future design of audiences for VR therapy and training applications.}, author = {Glémarec, Yann and Lugrin, Jean-Luc and Bosser, Anne-Gwenn and Collins Jackson, Aryana and Buche, Cédric and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {vraudi}, pages = 72, title = {Indifferent or Enthusiastic? Virtual Audiences Animation and Perception in Virtual Reality}, volume = 2, year = 2021 }
• User Responses to a Humanoid Robot Observed in Real Life, Virtual Reality, 3D and 2D. Mara, Martina; Stein, Jan-Philipp; Latoschik, Marc Erich; Lugrin, Birgit; Schreiner, Constanze; Hostettler, Rafael; Appel, Markus. In Frontiers in Psychology - Human-Media Interaction, 12, and (ed.), p. 1152. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Humanoid robots (i.e., robots with a human-like body) are projected to be mass marketed in the future in several fields of application. Today, however, user evaluations of humanoid robots are often based on mediated depictions rather than actual observations or interactions with a robot, which holds true not least for scientific user studies. People can be confronted with robots in various modes of presentation, among them (1) 2D videos, (2) 3D, i.e., stereoscopic videos, (3) immersive Virtual Reality (VR), or (4) live on site. A systematic investigation into how such differential modes of presentation influence user perceptions of a robot is still lacking. Thus, the current study systematically compares the effects of different presentation modes with varying immersive potential on user evaluations of a humanoid service robot. Participants (N = 120) observed an interaction between a humanoid service robot and an actor either on 2D or 3D video, via a virtual reality headset (VR) or live. We found support for the expected effect of the presentation mode on perceived immediacy. Effects regarding the degree of human likeness that was attributed to the robot were mixed. The presentation mode had no influence on evaluations in terms of eeriness, likability, and purchase intentions. Implications for empirical research on humanoid robots and practice are discussed.

  @article{mara2021responses, abstract = {Humanoid robots (i.e., robots with a human-like body) are projected to be mass marketed in the future in several fields of application. Today, however, user evaluations of humanoid robots are often based on mediated depictions rather than actual observations or interactions with a robot, which holds true not least for scientific user studies. People can be confronted with robots in various modes of presentation, among them (1) 2D videos, (2) 3D, i.e., stereoscopic videos, (3) immersive Virtual Reality (VR), or (4) live on site. A systematic investigation into how such differential modes of presentation influence user perceptions of a robot is still lacking. Thus, the current study systematically compares the effects of different presentation modes with varying immersive potential on user evaluations of a humanoid service robot. Participants (N = 120) observed an interaction between a humanoid service robot and an actor either on 2D or 3D video, via a virtual reality headset (VR) or live. We found support for the expected effect of the presentation mode on perceived immediacy. Effects regarding the degree of human likeness that was attributed to the robot were mixed. The presentation mode had no influence on evaluations in terms of eeriness, likability, and purchase intentions. Implications for empirical research on humanoid robots and practice are discussed.}, author = {Mara, Martina and Stein, Jan-Philipp and Latoschik, Marc Erich and Lugrin, Birgit and Schreiner, Constanze and Hostettler, Rafael and Appel, Markus}, editor = {and}, journal = {Frontiers in Psychology - Human-Media Interaction}, keywords = {myown}, pages = 1152, title = {User Responses to a Humanoid Robot Observed in Real Life, Virtual Reality, 3D and 2D}, volume = 12, year = 2021 }
• The Handbook on Socially Interactive Agents – 20 Years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics, Volume 1: Methods, Behavior, Cognition. Lugrin, Birgit; Pelachaud, Catherine; Traum, David. ACM, 2021.
  • [ BibTeX ]
  • [ URL ]
  @book{2021, author = {Lugrin, Birgit and Pelachaud, Catherine and Traum, David}, keywords = {MI}, publisher = {ACM}, title = {The Handbook on Socially Interactive Agents – 20 Years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics, Volume 1: Methods, Behavior, Cognition}, year = 2021 }
• Your New Friend NAO vs. Robot No. 783 - Effects of Personal or Impersonal Framing in a Robotic Storytelling Use Case. Steinhaeusser, Sophia C.; Gabel, Juliane J.; Lugrin, Birgit. In Companion of the 2021 ACM/IEEE International Conference on Human-Robot Interaction (HRI 2021), C. Bethel, A. Paiva, E. Broadbent, D. Feil-Seifer, D. Szafir (eds.). ACM, 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Steinhaeusser_2021, author = {Steinhaeusser, Sophia C. and Gabel, Juliane J. and Lugrin, Birgit}, booktitle = {Companion of the 2021 ACM/IEEE International Conference on Human-Robot Interaction (HRI 2021)}, editor = {Bethel, Cindy and Paiva, Ana and Broadbent, Elizabeth and Feil-Seifer, David and Szafir, Daniel}, keywords = {steinhaeusser}, publisher = {ACM}, title = {Your New Friend NAO vs. Robot No. 783 - Effects of Personal or Impersonal Framing in a Robotic Storytelling Use Case}, year = 2021 }
• Utilizing the Observer/Controller Architecture for a General Game AI. Büttner, Johannes. In Organic Computing: Doctoral Dissertation Colloquium 2021, S. Tomforde, C. Krupitzer (eds.), pp. 74–85. kassel university press, 2021.
  • [ BibTeX ]
  • [ URL ]
  @inbook{buttner2021utilizing, author = {Büttner, Johannes}, booktitle = {Organic Computing: Doctoral Dissertation Colloquium 2021}, editor = {Tomforde, Sven and Krupitzer, Christian}, keywords = {myown}, pages = {74–85}, publisher = {kassel university press}, title = {Utilizing the Observer/Controller Architecture for a General Game AI}, year = 2021 }
• Behavioral Framework of Immersive Technologies (BehaveFIT): How and Why Virtual Reality can Support Behavioral Change Processes. Wienrich, Carolin; D{ö}llinger, Nina Ines; Hein, Rebecca. In Frontiers Virtual Reality, 2, p. 84. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The design and evaluation of assisting technologies to support behavior change processes have become an essential topic within the field of human-computer interaction research in general and the field of immersive intervention technologies in particular. The mechanisms and success of behavior change techniques and interventions are broadly investigated in the field of psychology. However, it is not always easy to adapt these psychological findings to the context of immersive technologies. The lack of theoretical foundation also leads to a lack of explanation as to why and how immersive interventions support behavior change processes. The Behavioral Framework for immersive Technologies (BehaveFIT) addresses this lack by 1) presenting an intelligible categorization and condensation of psychological barriers and immersive features, by 2) suggesting a mapping that shows why and how immersive technologies can help to overcome barriers and finally by 3) proposing a generic prediction path that enables a structured, theory-based approach to the development and evaluation of immersive interventions. These three steps explain how BehaveFIT can be used, and include guiding questions for each step. Further, two use cases illustrate the usage of BehaveFIT. Thus, the present paper contributes to guidance for immersive intervention design and evaluation, showing that immersive interventions support behavior change processes and explain and predict 'why' and 'how' immersive interventions can bridge the intention-behavior-gap.

  @article{wienrich2020mind, abstract = {The design and evaluation of assisting technologies to support behavior change processes have become an essential topic within the field of human-computer interaction research in general and the field of immersive intervention technologies in particular. The mechanisms and success of behavior change techniques and interventions are broadly investigated in the field of psychology. However, it is not always easy to adapt these psychological findings to the context of immersive technologies. The lack of theoretical foundation also leads to a lack of explanation as to why and how immersive interventions support behavior change processes. The Behavioral Framework for immersive Technologies (BehaveFIT) addresses this lack by 1) presenting an intelligible categorization and condensation of psychological barriers and immersive features, by 2) suggesting a mapping that shows why and how immersive technologies can help to overcome barriers and finally by 3) proposing a generic prediction path that enables a structured, theory-based approach to the development and evaluation of immersive interventions. These three steps explain how BehaveFIT can be used, and include guiding questions for each step. Further, two use cases illustrate the usage of BehaveFIT. Thus, the present paper contributes to guidance for immersive intervention design and evaluation, showing that immersive interventions support behavior change processes and explain and predict 'why' and 'how' immersive interventions can bridge the intention-behavior-gap.}, author = {Wienrich, Carolin and D{\"o}llinger, Nina Ines and Hein, Rebecca}, journal = {Frontiers Virtual Reality}, keywords = {rebecca.hein}, pages = 84, title = {Behavioral Framework of Immersive Technologies (BehaveFIT): How and Why Virtual Reality can Support Behavioral Change Processes}, volume = 2, year = 2021 }
• The Science of Systems Benchmarking. Kounev, Samuel. 2021.
  • [ BibTeX ]
  • [ URL ]
  @presentation{kounev2021science, author = {Kounev, Samuel}, keywords = {descartes}, title = {The Science of Systems Benchmarking}, year = 2021 }
• Peer group supervision in Zoom and social VR-Preparing preservice teachers for planning and designing digital media integrated classes. Ripka, Gabriela; Grafe, Silke; Latoschik, Marc Erich. In EdMedia+ Innovate Learning, pp. 602–616. Association for the Advancement of Computing in Education (AACE), 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  21-century challenges demand a change towards collaborative and constructive seminar designs in initial teacher education regarding preservice teachers acquiring meta-conceptual awareness (TPACK) about how to implement emerging technologies in their future profession. Against this background the paper addresses the following research questions: 1) How should a pedagogical concept for remote initial teacher education be designed to promote metacognitive learning processes of preservice teachers? 2) How do preservice teachers perceive these learning processes in video-based communication and social VR? Regarding the pedagogical concept, peer group supervision and an action-and development-oriented approach using Zoom and social VR were identified as relevant for an instructional design that provides collaborative and constructive learning processes for students. In this exploratory study, 17 students participated in two iterative cycles of peer group supervision performing design tasks in groups. A content analysis of reflective video statements and qualitative group interviews was carried out using a qualitative research design. Results indicate the successful implementation of peer group supervision. Regarding media's implementation, Zoom's screen-sharing option and breakout session benefitted the consultation process as well as social VR's "realistic" experience of creating a "sense of community".

  @inproceedings{ripka2021peer, abstract = {21-century challenges demand a change towards collaborative and constructive seminar designs in initial teacher education regarding preservice teachers acquiring meta-conceptual awareness (TPACK) about how to implement emerging technologies in their future profession. Against this background the paper addresses the following research questions: 1) How should a pedagogical concept for remote initial teacher education be designed to promote metacognitive learning processes of preservice teachers? 2) How do preservice teachers perceive these learning processes in video-based communication and social VR? Regarding the pedagogical concept, peer group supervision and an action-and development-oriented approach using Zoom and social VR were identified as relevant for an instructional design that provides collaborative and constructive learning processes for students. In this exploratory study, 17 students participated in two iterative cycles of peer group supervision performing design tasks in groups. A content analysis of reflective video statements and qualitative group interviews was carried out using a qualitative research design. Results indicate the successful implementation of peer group supervision. Regarding media's implementation, Zoom's screen-sharing option and breakout session benefitted the consultation process as well as social VR's "realistic" experience of creating a "sense of community".}, author = {Ripka, Gabriela and Grafe, Silke and Latoschik, Marc Erich}, booktitle = {EdMedia+ Innovate Learning}, keywords = {myown}, organization = {Association for the Advancement of Computing in Education (AACE)}, pages = {602-616}, title = {Peer group supervision in Zoom and social VR-Preparing preservice teachers for planning and designing digital media integrated classes}, year = 2021 }
• The emotional robotic storyteller: On the influence of affect congruency on narrative transportation, robot perception, and persuasion. Appel, Markus; Lugrin, Birgit; Kühle, Mayla; Heindl, Corinna. In Computers in Human Behavior, p. 106749. Elsevier, 2021.
  • [ BibTeX ]
  • [ URL ]
  @article{Appel_2021, author = {Appel, Markus and Lugrin, Birgit and Kühle, Mayla and Heindl, Corinna}, journal = {Computers in Human Behavior}, keywords = {mi}, pages = 106749, publisher = {Elsevier}, title = {The emotional robotic storyteller: On the influence of affect congruency on narrative transportation, robot perception, and persuasion}, year = 2021 }
• Auswirkungen der COVID-19-Pandemie auf Sportlerinnen und Sportler in Deutschland. Zinner, Christoph; Matzka, Manuel; Leppich, Robert; Kounev, Samuel; Holmberg, Hans-Christian; Sperlich, Billy. In 53. asp Jahrestagung. 2021.
  • [ BibTeX ]
  @article{zinner2021auswirkungen, author = {Zinner, Christoph and Matzka, Manuel and Leppich, Robert and Kounev, Samuel and Holmberg, Hans-Christian and Sperlich, Billy}, journal = {53. asp Jahrestagung}, keywords = {t_interdisciplinary}, title = {Auswirkungen der COVID-19-Pandemie auf Sportlerinnen und Sportler in Deutschland}, year = 2021 }
• Teaching Software Testing Using Automated Grading. Beierlieb, Lukas; Iffländer, Lukas; Schneider, Tobias; Prantl, Thomas; Kounev, Samuel. In Proceedings of the Fifth Workshop "Automatische Bewertung von Programmieraufgaben" (ABP 2021),virtual event, October 28-29, 2021, A. Greubel, S. Strickroth, M. Striewe (eds.). Gesellschaft für Informatik, 2021.
  • [ BibTeX ]
  @inproceedings{Beierlieb_2021_TeachingSoftwareTestingUsingAutomatedGrading, author = {Beierlieb, Lukas and Iffländer, Lukas and Schneider, Tobias and Prantl, Thomas and Kounev, Samuel}, booktitle = {Proceedings of the Fifth Workshop "Automatische Bewertung von Programmieraufgaben" (ABP 2021),virtual event, October 28-29, 2021}, editor = {Greubel, André and Strickroth, Sven and Striewe, Michael}, keywords = {teaching}, publisher = {Gesellschaft für Informatik}, title = {Teaching Software Testing Using Automated Grading}, year = 2021 }
• An Overview on Approaches for Coordination of Platoons. Lesch, Veronika; Breitbach, Martin; Segata, Michele; Becker, Christian; Kounev, Samuel; Krupitzer, Christian. In IEEE Transactions on Intelligent Transportation Systems. 2021.
  • [ BibTeX ]
  @article{lesch2021overview, author = {Lesch, Veronika and Breitbach, Martin and Segata, Michele and Becker, Christian and Kounev, Samuel and Krupitzer, Christian}, journal = {IEEE Transactions on Intelligent Transportation Systems}, keywords = {platooning}, note = {Early Access on IEEE Xplore}, title = {An Overview on Approaches for Coordination of Platoons}, year = 2021 }
• {Serverless Computing (Dagstuhl Seminar 21201)}. Abad, Cristina; Foster, Ian T.; Herbst, Nikolas; Iosup, Alexandru. In Dagstuhl Reports, 11(4), C. Abad; I. T. Foster; N. Herbst; A. Iosup (eds.), pp. 34–93. Schloss Dagstuhl -- Leibniz-Zentrum f{ü}r Informatik, Dagstuhl, Germany, 2021.
  • [ BibTeX ]
  • [ URL ]
  @article{abad_et_al:DagRep.11.4.34, address = {Dagstuhl, Germany}, annote = {Keywords: Cloud computing, Cloud continuum, data-driven, design patterns, DevOps, experimentation, model-driven, serverless computing, simulation, software architecture, systems management, vision}, author = {Abad, Cristina and Foster, Ian T. and Herbst, Nikolas and Iosup, Alexandru}, editor = {Abad, Cristina and Foster, Ian T. and Herbst, Nikolas and Iosup, Alexandru}, journal = {Dagstuhl Reports}, keywords = {resource_management}, number = 4, pages = {34–93}, publisher = {Schloss Dagstuhl – Leibniz-Zentrum f{\"u}r Informatik}, title = {{Serverless Computing (Dagstuhl Seminar 21201)}}, volume = 11, year = 2021 }
• Anomaly Detection in Beehives: An Algorithm Comparison. Davidson, Padraig; Steininger, Michael; Lautenschlager, Florian; Krause, Anna; Hotho, Andreas. 2021.
  • [ BibTeX ]
  @misc{davidson2021anomaly, author = {Davidson, Padraig and Steininger, Michael and Lautenschlager, Florian and Krause, Anna and Hotho, Andreas}, keywords = 2021, title = {Anomaly Detection in Beehives: An Algorithm Comparison}, year = 2021 }
• A Case Study on Optimization of Platooning Coordination. Lesch, Veronika; Hadry, Marius; Kounev, Samuel; Krupitzer, Christian. Universit{ä}t W{ü}rzburg and Universit{ä}t Hohenheim, 2021.
  • [ BibTeX ]
  • [ URL ]
  @techreport{lesch2021studyplatooning, author = {Lesch, Veronika and Hadry, Marius and Kounev, Samuel and Krupitzer, Christian}, institution = {Universit{ä}t W{ü}rzburg and Universit{ä}t Hohenheim}, keywords = {t_techreport}, title = {A Case Study on Optimization of Platooning Coordination}, year = 2021 }
• Performance Evaluation of a Post-Quantum Public-Key Cryptosystem. Prantl, Thomas; Prantl, Dominik; Beierlieb, Lukas; Iffländer, Lukas; Dmitrienko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In 2021 IEEE 40th International Performance Computing and Communications Conference (IPCCC). IEEE, 2021.
  • [ BibTeX ]
  @inproceedings{PrPrBeIfDnKrKo2021-IPCCC-QuantumPublicKeyCryposystem, author = {Prantl, Thomas and Prantl, Dominik and Beierlieb, Lukas and Iffländer, Lukas and Dmitrienko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, booktitle = {2021 IEEE 40th International Performance Computing and Communications Conference (IPCCC)}, keywords = {t_workshop}, organization = {IEEE}, title = {Performance Evaluation of a Post-Quantum Public-Key Cryptosystem}, year = 2021 }
• Consistent Simplification of Polyline Tree Bundles. Bosch, Yannick; Schäfer, Peter; Spoerhase, Joachim; Storandt, Sabine; Zink, Johannes. In Proc. 27th International Computing and Combinatorics Conference (COCOON’21). 2021.
  • [ BibTeX ]
  @inproceedings{bosch-etal21:polyline-simplification, author = {Bosch, Yannick and Schäfer, Peter and Spoerhase, Joachim and Storandt, Sabine and Zink, Johannes}, booktitle = {Proc. 27th International Computing and Combinatorics Conference (COCOON'21)}, keywords = {graph}, note = {to appear}, title = {Consistent Simplification of Polyline Tree Bundles}, year = 2021 }
• A financial game with opportunities for fraud. Tritscher, Julian; Krause, Anna; Schl{{ö}}r, Daniel; Gwinner, Fabian; von Mammen, Sebastian; Hotho, Andreas. In 2021 {IEEE} Conference on Games (CoG), Copenhagen, Denmark, August 17-20, 2021, pp. 1–5. {IEEE}, 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{DBLP:conf/cig/TritscherKSGMH21, author = {Tritscher, Julian and Krause, Anna and Schl{\"{o}}r, Daniel and Gwinner, Fabian and von Mammen, Sebastian and Hotho, Andreas}, booktitle = {2021 {IEEE} Conference on Games (CoG), Copenhagen, Denmark, August 17-20, 2021}, keywords = {myown}, pages = {1–5}, publisher = {{IEEE}}, title = {A financial game with opportunities for fraud}, year = 2021 }
• A Machine Learning-based Workflow for Automatic Detection of Anomalies in Machine Tools. Züfle, Marwin; Moog, Felix; Lesch, Veronika; Krupitzer, Christian; Kounev, Samuel. In ISA Transactions: The Journal of Automation. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Despite the increased sensor-based data collection in Industry 4.0, the practical use of this data is still in its infancy. In contrast, academic literature provides several approaches to detect machine failures but, in most cases, relies on simulations and vast amounts of training data. Since it is often not practical to collect such amounts of data in an industrial context, we propose an approach to detect the current production mode and machine degradation states on a comparably small data set. Our approach integrates domain knowledge about manufacturing systems into a highly generalizable end-to-end workflow ranging from raw data processing, phase segmentation, data resampling, and feature extraction to machine tool anomaly detection. The workflow applies unsupervised clustering techniques to identify the current production mode and supervised classification models for detecting the present degradation. A resampling strategy and classical machine learning models enable the workflow to handle small data sets and distinguish between normal and abnormal machine tool behavior. To the best of our knowledge, there exists no such end-to-end workflow in the literature that uses the entire machine signal as input to identify anomalies for individual tools. Our evaluation with data from a real multi-purpose machine shows that the proposed workflow detects anomalies with an average F1-score of almost 93%.

  @article{zuefle2021anomalydetection, abstract = {Despite the increased sensor-based data collection in Industry 4.0, the practical use of this data is still in its infancy. In contrast, academic literature provides several approaches to detect machine failures but, in most cases, relies on simulations and vast amounts of training data. Since it is often not practical to collect such amounts of data in an industrial context, we propose an approach to detect the current production mode and machine degradation states on a comparably small data set. Our approach integrates domain knowledge about manufacturing systems into a highly generalizable end-to-end workflow ranging from raw data processing, phase segmentation, data resampling, and feature extraction to machine tool anomaly detection. The workflow applies unsupervised clustering techniques to identify the current production mode and supervised classification models for detecting the present degradation. A resampling strategy and classical machine learning models enable the workflow to handle small data sets and distinguish between normal and abnormal machine tool behavior. To the best of our knowledge, there exists no such end-to-end workflow in the literature that uses the entire machine signal as input to identify anomalies for individual tools. Our evaluation with data from a real multi-purpose machine shows that the proposed workflow detects anomalies with an average F1-score of almost 93%.}, author = {Züfle, Marwin and Moog, Felix and Lesch, Veronika and Krupitzer, Christian and Kounev, Samuel}, journal = {ISA Transactions: The Journal of Automation}, keywords = {t_journalmagazine}, note = {(in press)}, title = {A Machine Learning-based Workflow for Automatic Detection of Anomalies in Machine Tools}, year = 2021 }
• Performance Evaluation of a Post-Quantum Public-Key Cryptosystem. Prantl, Thomas; Prantl, Dominik; Beierlieb, Lukas; Iffländer, Lukas; Dmitrienko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In 2021 IEEE 40th International Performance Computing and Communications Conference (IPCCC). IEEE, 2021.
  • [ BibTeX ]
  @inproceedings{PrPrBeIfDnKrKo2021-IPCCC-QuantumPublicKeyCryposystem, author = {Prantl, Thomas and Prantl, Dominik and Beierlieb, Lukas and Iffländer, Lukas and Dmitrienko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, booktitle = {2021 IEEE 40th International Performance Computing and Communications Conference (IPCCC)}, keywords = {t_workshop}, organization = {IEEE}, title = {Performance Evaluation of a Post-Quantum Public-Key Cryptosystem}, year = 2021 }
• Sizeless: Predicting the Optimal Size of Serverless Functions. Eismann, Simon; Bui, Long; Grohmann, Johannes; Abad, Cristina; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 22nd International MIDDLEWARE Conference, pp. 248–259. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Serverless functions are an emerging cloud computing paradigm that is being rapidly adopted by both industry and academia. In this cloud computing model, the provider opaquely handles resource management tasks such as resource provisioning, deployment, and auto-scaling. The only resource management task that developers are still in charge of is selecting how much resources are allocated to each worker instance. However, selecting the optimal size of serverless functions is quite challenging, so developers often neglect it despite its significant cost and performance benefits. Existing approaches aiming to automate serverless functions resource sizing require dedicated performance tests, which are time-consuming to implement and maintain. In this paper, we introduce an approach to predict the optimal resource size of a serverless function using monitoring data from a single resource size. As our approach does not require dedicated performance tests, it enables cloud providers to implement resource sizing on a platform level and automate the last resource management task associated with serverless functions. We evaluate our approach on four different serverless applications on AWS, where it predicts the execution time of the other memory sizes based on monitoring data for a single memory size with an average prediction error of 15.3%. Based on these predictions, it selects the optimal memory size for 79.0% of the serverless functions and the secondbest memory size for 12.3% of the serverless functions, which results in an average speedup of 39.7% while also decreasing average costs by 2.6%.

  @inproceedings{eismann2021sizeless, abstract = {Serverless functions are an emerging cloud computing paradigm that is being rapidly adopted by both industry and academia. In this cloud computing model, the provider opaquely handles resource management tasks such as resource provisioning, deployment, and auto-scaling. The only resource management task that developers are still in charge of is selecting how much resources are allocated to each worker instance. However, selecting the optimal size of serverless functions is quite challenging, so developers often neglect it despite its significant cost and performance benefits. Existing approaches aiming to automate serverless functions resource sizing require dedicated performance tests, which are time-consuming to implement and maintain. In this paper, we introduce an approach to predict the optimal resource size of a serverless function using monitoring data from a single resource size. As our approach does not require dedicated performance tests, it enables cloud providers to implement resource sizing on a platform level and automate the last resource management task associated with serverless functions. We evaluate our approach on four different serverless applications on AWS, where it predicts the execution time of the other memory sizes based on monitoring data for a single memory size with an average prediction error of 15.3%. Based on these predictions, it selects the optimal memory size for 79.0% of the serverless functions and the secondbest memory size for 12.3% of the serverless functions, which results in an average speedup of 39.7% while also decreasing average costs by 2.6%.}, author = {Eismann, Simon and Bui, Long and Grohmann, Johannes and Abad, Cristina and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 22nd International MIDDLEWARE Conference}, keywords = {descartes}, note = {Best Student Paper Award, ACM Artifacts Evaluated — Functional}, pages = {248–259}, title = {Sizeless: Predicting the Optimal Size of Serverless Functions}, year = 2021 }
• Density-based weighting for imbalanced regression. Steininger, Michael; Kobs, Konstantin; Davidson, Padraig; Krause, Anna; Hotho, Andreas. In Machine Learning, A. Appice; S. Escalera; J. A. Gamez; H. Trautmann (eds.). 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In many real world settings,imbalanced data impedes model performance of learning algorithms, like neural networks, mostly for rare cases. This is especially problematic for tasks focusing on these rare occurrences. For example, when estimating precipitation, extreme rainfall events are scarce but important considering their potential consequences. While there are numerous well studied solutions for classification settings, most of them cannot be applied to regression easily. Of the few solutions for regression tasks, barely any have explored cost-sensitive learning which is known to have advantages compared to sampling-based methods in classification tasks. In this work, we propose a sample weighting approach for imbalanced regression datasets called DenseWeight and a cost-sensitive learning approach for neural network regression with imbalanced data called DenseLoss based on our weighting scheme. DenseWeight weights data points according to their target value rarities through kernel density estimation (KDE). DenseLoss adjusts each data point’s influence on the loss according to DenseWeight, giving rare data points more influence on modeltraining compared to common data points. We show on multiple differently distributed datasets that DenseLoss significantly improves model performance for rare data points through its density-based weighting scheme. Additionally, we compare DenseLoss to the state-of-the-art method SMOGN, finding that our method mostly yields better performance. Our approach provides more control over model training as it enables us to actively decide on the trade-off between focusing on common or rare cases through a single hyperparameter, allowing the training of better models for rare data points.

  @article{steininger2021densitybased, abstract = {In many real world settings,imbalanced data impedes model performance of learning algorithms, like neural networks, mostly for rare cases. This is especially problematic for tasks focusing on these rare occurrences. For example, when estimating precipitation, extreme rainfall events are scarce but important considering their potential consequences. While there are numerous well studied solutions for classification settings, most of them cannot be applied to regression easily. Of the few solutions for regression tasks, barely any have explored cost-sensitive learning which is known to have advantages compared to sampling-based methods in classification tasks. In this work, we propose a sample weighting approach for imbalanced regression datasets called DenseWeight and a cost-sensitive learning approach for neural network regression with imbalanced data called DenseLoss based on our weighting scheme. DenseWeight weights data points according to their target value rarities through kernel density estimation (KDE). DenseLoss adjusts each data point’s influence on the loss according to DenseWeight, giving rare data points more influence on modeltraining compared to common data points. We show on multiple differently distributed datasets that DenseLoss significantly improves model performance for rare data points through its density-based weighting scheme. Additionally, we compare DenseLoss to the state-of-the-art method SMOGN, finding that our method mostly yields better performance. Our approach provides more control over model training as it enables us to actively decide on the trade-off between focusing on common or rare cases through a single hyperparameter, allowing the training of better models for rare data points.}, author = {Steininger, Michael and Kobs, Konstantin and Davidson, Padraig and Krause, Anna and Hotho, Andreas}, editor = {Appice, Annalisa and Escalera, Sergio and Gamez, Jose A. and Trautmann, Heike}, journal = {Machine Learning}, keywords = {selected}, title = {Density-based weighting for imbalanced regression}, year = 2021 }
• Motivating Interactive Self-Organisation. von Mammen, Sebastian. In Lifelike Computing Systems Workshop 2020 and 2021. 2021.
  • [ BibTeX ]
  • [ URL ]
  @article{von2021motivating, author = {von Mammen, Sebastian}, journal = {Lifelike Computing Systems Workshop 2020 and 2021}, keywords = {myown}, title = {Motivating Interactive Self-Organisation}, year = 2021 }
• Uplink vs. Downlink: Machine Learning-Based Quality Prediction for HTTP Adaptive Video Streaming. Loh, Frank; Poignée, Fabian; Wamser, Florian; Leidinger, Ferdinand; Hoßfeld, Tobias. In Sensors, 21(12), p. 4172. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Streaming video is responsible for the bulk of Internet traffic these days. For this reason, Internet providers and network operators try to make predictions and assessments about the streaming quality for an end user. Current monitoring solutions are based on a variety of different machine learning approaches. The challenge for providers and operators nowadays is that existing approaches require large amounts of data. In this work, the most relevant quality of experience metrics, i.e., the initial playback delay, the video streaming quality, video quality changes, and video rebuffering events, are examined using a voluminous data set of more than 13,000 YouTube video streaming runs that were collected with the native YouTube mobile app. Three Machine Learning models are developed and compared to estimate playback behavior based on uplink request information. The main focus has been on developing a lightweight approach using as few features and as little data as possible, while maintaining state-of-the-art performance.

  @article{info3-article-2021-3, abstract = {Streaming video is responsible for the bulk of Internet traffic these days. For this reason, Internet providers and network operators try to make predictions and assessments about the streaming quality for an end user. Current monitoring solutions are based on a variety of different machine learning approaches. The challenge for providers and operators nowadays is that existing approaches require large amounts of data. In this work, the most relevant quality of experience metrics, i.e., the initial playback delay, the video streaming quality, video quality changes, and video rebuffering events, are examined using a voluminous data set of more than 13,000 YouTube video streaming runs that were collected with the native YouTube mobile app. Three Machine Learning models are developed and compared to estimate playback behavior based on uplink request information. The main focus has been on developing a lightweight approach using as few features and as little data as possible, while maintaining state-of-the-art performance.}, author = {Loh, Frank and Poignée, Fabian and Wamser, Florian and Leidinger, Ferdinand and Hoßfeld, Tobias}, journal = {Sensors}, keywords = {can}, number = 12, pages = 4172, title = {Uplink vs. Downlink: Machine Learning-Based Quality Prediction for HTTP Adaptive Video Streaming}, volume = 21, year = 2021 }
• Internalisation of Situational Motivation in an E-Learning Scenario Using Gamification. Schaper, Philipp; Riedmann, Anna; Lugrin, Birgit. In International Conference on Artificial Intelligence in Education (AIED 2021), pp. 314–319. Springer, 2021.
  • [ BibTeX ]
  @inproceedings{schaper2021internalisation, author = {Schaper, Philipp and Riedmann, Anna and Lugrin, Birgit}, booktitle = {International Conference on Artificial Intelligence in Education (AIED 2021)}, keywords = {mi}, organization = {Springer}, pages = {314-319}, title = {Internalisation of Situational Motivation in an E-Learning Scenario Using Gamification}, year = 2021 }
• Inter- und Transkulturelles Lernen in Virtual Reality - Ein Seminarkonzept für die Lehrkräfteausbildung im Fach Englisch. Hein, Rebecca M; Steinbock, Jeanine; Eisenmann, Maria; Wienrich, Carolin; Latoschik, Marc Erich. In In: Söbke, H. & Weise, M. (Hrsg.), Wettbewerbsband AVRiL 2021, pp. 34–39. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Inter- und transkulturelle Kompetenzen sind zentrale Elemente einer aktiven Teilhabe in einer modernen Gesellschaft. Die Fremdsprachenforschung setzt sich im Kontext der Digitalisierung mit neuen Konzepten zum Erwerb dieser Kompetenzen im Fremdsprachenunterricht auseinander. Eine Zusammenarbeit mit der HCI-Forschung zum Einsatz von social VR im Klassenzimmer lässt auf einen positiven Erkenntnisgewinn schließen. So lautet die zentrale Forschungshypothese, dass vollimmersive Lernumgebungen verstärkt inter- und transkulturelle Lernprozesse fördern, weil Lernende VR-Welten nicht nur betrachten, sondern innerhalb dieser selbstwirksam interagieren und das Umfeld eigenständig manipulieren können. Darauf aufbauend wurde ein Seminarkonzept entwickelt, in dem Lehramtsstudierende für das Fach Englisch inter- und transkulturelle Lehr/Lernszenarien in VR konzipieren, die sie dann in ihrer Unterrichtspraxis einsetzen können. So lernen Studierende das Potenzial von VR nicht nur kennen, sondern ebenso dieses unterrichtlich umzusetzen.

  @article{hein2021inter, abstract = {Inter- und transkulturelle Kompetenzen sind zentrale Elemente einer aktiven Teilhabe in einer modernen Gesellschaft. Die Fremdsprachenforschung setzt sich im Kontext der Digitalisierung mit neuen Konzepten zum Erwerb dieser Kompetenzen im Fremdsprachenunterricht auseinander. Eine Zusammenarbeit mit der HCI-Forschung zum Einsatz von social VR im Klassenzimmer lässt auf einen positiven Erkenntnisgewinn schließen. So lautet die zentrale Forschungshypothese, dass vollimmersive Lernumgebungen verstärkt inter- und transkulturelle Lernprozesse fördern, weil Lernende VR-Welten nicht nur betrachten, sondern innerhalb dieser selbstwirksam interagieren und das Umfeld eigenständig manipulieren können. Darauf aufbauend wurde ein Seminarkonzept entwickelt, in dem Lehramtsstudierende für das Fach Englisch inter- und transkulturelle Lehr/Lernszenarien in VR konzipieren, die sie dann in ihrer Unterrichtspraxis einsetzen können. So lernen Studierende das Potenzial von VR nicht nur kennen, sondern ebenso dieses unterrichtlich umzusetzen.}, author = {Hein, Rebecca M and Steinbock, Jeanine and Eisenmann, Maria and Wienrich, Carolin and Latoschik, Marc Erich}, journal = {In: Söbke, H. & Weise, M. (Hrsg.), Wettbewerbsband AVRiL 2021}, keywords = {c.wienrich}, pages = {34-39}, title = {Inter- und Transkulturelles Lernen in Virtual Reality - Ein Seminarkonzept für die Lehrkräfteausbildung im Fach Englisch}, year = 2021 }
• Fostering Teacher Educator Technology Competencies (TETCs) in and with Virtual Reality. A Case Study. Schröter, Thomas; Tiede, Jennifer; Latoschik, Marc Erich. In Proceedings of EdMedia + Innovate Learning, T. Bastiaens (ed.), pp. 617–629. Association for the Advancement of Computing in Education (AACE), 2021.
  • [ BibTeX ]
  @conference{schroter2021fostering, author = {Schröter, Thomas and Tiede, Jennifer and Latoschik, Marc Erich}, booktitle = {Proceedings of EdMedia + Innovate Learning}, editor = {Bastiaens, T.}, keywords = {Schröter}, organization = {Association for the Advancement of Computing in Education (AACE)}, pages = {617-629}, publisher = {Association for the Advancement of Computing in Education (AACE)}, title = {Fostering Teacher Educator Technology Competencies (TETCs) in and with Virtual Reality. A Case Study}, year = 2021 }
• Virtual Body Ownership Intensifies Emotional Responses to Virtual Stimuli. Gall, Dominik; Roth, Daniel; Stauffert, Jan-Philipp; Zarges, Julian; Latoschik, Marc Erich. In Frontiers in Psychology - Cognitive Science, 12, S. R. DiPaola; U. Bernardet; J. Gratch (eds.), p. 3833. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Modulating emotional responses to virtual stimuli is a fundamental goal of many immersive interactive applications. In this study, we leverage the illusion of illusory embodiment and show that owning a virtual body provides means to modulate emotional responses. In a single-factor repeated-measures experiment, we manipulated the degree of illusory embodiment and assessed the emotional responses to virtual stimuli. We presented emotional stimuli in the same environment as the virtual body. Participants experienced higher arousal, dominance, and more intense valence in the high embodiment condition compared to the low embodiment condition. The illusion of embodiment thus intensifies the emotional processing of the virtual environment. This result suggests that artificial bodies can increase the effectiveness of immersive applications psychotherapy, entertainment, computer-mediated social interactions, or health applications.

  @article{gall2021virtual, abstract = {Modulating emotional responses to virtual stimuli is a fundamental goal of many immersive interactive applications. In this study, we leverage the illusion of illusory embodiment and show that owning a virtual body provides means to modulate emotional responses. In a single-factor repeated-measures experiment, we manipulated the degree of illusory embodiment and assessed the emotional responses to virtual stimuli. We presented emotional stimuli in the same environment as the virtual body. Participants experienced higher arousal, dominance, and more intense valence in the high embodiment condition compared to the low embodiment condition. The illusion of embodiment thus intensifies the emotional processing of the virtual environment. This result suggests that artificial bodies can increase the effectiveness of immersive applications psychotherapy, entertainment, computer-mediated social interactions, or health applications.}, author = {Gall, Dominik and Roth, Daniel and Stauffert, Jan-Philipp and Zarges, Julian and Latoschik, Marc Erich}, editor = {DiPaola, Steve Richard and Bernardet, Ulysses and Gratch, Jonathan}, journal = {Frontiers in Psychology - Cognitive Science}, keywords = {myown}, pages = 3833, title = {Virtual Body Ownership Intensifies Emotional Responses to Virtual Stimuli}, volume = 12, year = 2021 }
• Effects of Acrophobic Fear and Trait Anxiety on Human Behavior in a Virtual Elevated Plus-Maze. Madeira, Octávia; Gromer, Daniel; Latoschik, Marc Erich; Pauli, Paul. In Frontiers in Virtual Reality, 2, p. 19. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The Elevated Plus-Maze (EPM) is a well-established apparatus to measure anxiety in rodents, i.e. animals exhibiting an increased relative time spent in the closed versus the open arms are considered anxious. To examine whether such anxiety-modulated behavior is conserved in humans, we re-translated this paradigm to a human setting using virtual reality in a Cave Automatic Virtual Environment (CAVE) system. In two studies, we examined whether the EPM exploration behavior of humans is modulated by their trait anxiety, but also assessed the individuals’ levels of acrophobia (fear of height), claustrophobia (fear of confined spaces), sensation seeking and the reported anxiety when on the maze. First, we constructed an exact virtual copy of the animal EPM adjusted to human proportions. In analogy to animal EPM studies, participants (N = 30) freely explored the EPM for five minutes. In the second study (N = 61), we redesigned the EPM to make it more human-adapted and to differentiate influences of trait anxiety and acrophobia by introducing various floor textures and lower walls of closed arms to the height of common handrails. In the first experiment, hierarchical regression analyses of exploration behavior revealed the expected association between open arm avoidance and Trait Anxiety, but an even stronger association with acrophobic fear. In the second study, results revealed that acrophobia was associated with avoidance of open arms with mesh-floor texture, whereas for trait anxiety, claustrophobia and sensation seeking no effect was detected. In addition, subjects’ fear rating was moderated by all psychometrics but trait anxiety. In sum, both studies consistently indicate that humans show no general open arm avoidance analogous to rodents and that human EPM behavior is modulated strongest by acrophobic fear, whereas trait anxiety plays a subordinate role. Thus, we conclude that the criteria for a cross-species validity are met insufficiently in this case. Despite of the exploratory nature, our studies provide in-depth insights into human exploration behavior on the virtual EPM.

  @article{madeira2021effects, abstract = {The Elevated Plus-Maze (EPM) is a well-established apparatus to measure anxiety in rodents, i.e. animals exhibiting an increased relative time spent in the closed versus the open arms are considered anxious. To examine whether such anxiety-modulated behavior is conserved in humans, we re-translated this paradigm to a human setting using virtual reality in a Cave Automatic Virtual Environment (CAVE) system. In two studies, we examined whether the EPM exploration behavior of humans is modulated by their trait anxiety, but also assessed the individuals’ levels of acrophobia (fear of height), claustrophobia (fear of confined spaces), sensation seeking and the reported anxiety when on the maze. First, we constructed an exact virtual copy of the animal EPM adjusted to human proportions. In analogy to animal EPM studies, participants (N = 30) freely explored the EPM for five minutes. In the second study (N = 61), we redesigned the EPM to make it more human-adapted and to differentiate influences of trait anxiety and acrophobia by introducing various floor textures and lower walls of closed arms to the height of common handrails. In the first experiment, hierarchical regression analyses of exploration behavior revealed the expected association between open arm avoidance and Trait Anxiety, but an even stronger association with acrophobic fear. In the second study, results revealed that acrophobia was associated with avoidance of open arms with mesh-floor texture, whereas for trait anxiety, claustrophobia and sensation seeking no effect was detected. In addition, subjects’ fear rating was moderated by all psychometrics but trait anxiety. In sum, both studies consistently indicate that humans show no general open arm avoidance analogous to rodents and that human EPM behavior is modulated strongest by acrophobic fear, whereas trait anxiety plays a subordinate role. Thus, we conclude that the criteria for a cross-species validity are met insufficiently in this case. Despite of the exploratory nature, our studies provide in-depth insights into human exploration behavior on the virtual EPM.}, author = {Madeira, Octávia and Gromer, Daniel and Latoschik, Marc Erich and Pauli, Paul}, journal = {Frontiers in Virtual Reality}, keywords = {myown}, pages = 19, title = {Effects of Acrophobic Fear and Trait Anxiety on Human Behavior in a Virtual Elevated Plus-Maze}, volume = 2, year = 2021 }
• eXtended Artificial Intelligence: New Prospects of Human-AI Interaction Research. Wienrich, Carolin; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 2, p. 94. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Artificial Intelligence (AI) covers a broad spectrum of computational problems and use cases. Many of those implicate profound and sometimes intricate questions of how humans interact or should interact with AIs. Moreover, many users or future users do have abstract ideas of what AI is, significantly depending on the specific embodiment of AI applications. Human-centered-design approaches would suggest evaluating the impact of different embodiments on human perception of and interaction with AI. An approach that is difficult to realize due to the sheer complexity of application fields and embodiments in reality. However, here XR opens new possibilities to research human-AI interactions. The article's contribution is twofold: First, it provides a theoretical treatment and model of human-AI interaction based on an XR-AI continuum as a framework for and a perspective of different approaches of XR-AI combinations. It motivates XR-AI combinations as a method to learn about the effects of prospective human-AI interfaces and shows why the combination of XR and AI fruitfully contributes to a valid and systematic investigation of human-AI interactions and interfaces. Second, the article provides two exemplary experiments investigating the aforementioned approach for two distinct AI-systems. The first experiment reveals an interesting gender effect in human-robot interaction, while the second experiment reveals an Eliza effect of a recommender system. Here the article introduces two paradigmatic implementations of the proposed XR testbed for human-AI interactions and interfaces and shows how a valid and systematic investigation can be conducted. In sum, the article opens new perspectives on how XR benefits human-centered AI design and development.

  @article{wienrich2021extended, abstract = {Artificial Intelligence (AI) covers a broad spectrum of computational problems and use cases. Many of those implicate profound and sometimes intricate questions of how humans interact or should interact with AIs. Moreover, many users or future users do have abstract ideas of what AI is, significantly depending on the specific embodiment of AI applications. Human-centered-design approaches would suggest evaluating the impact of different embodiments on human perception of and interaction with AI. An approach that is difficult to realize due to the sheer complexity of application fields and embodiments in reality. However, here XR opens new possibilities to research human-AI interactions. The article's contribution is twofold: First, it provides a theoretical treatment and model of human-AI interaction based on an XR-AI continuum as a framework for and a perspective of different approaches of XR-AI combinations. It motivates XR-AI combinations as a method to learn about the effects of prospective human-AI interfaces and shows why the combination of XR and AI fruitfully contributes to a valid and systematic investigation of human-AI interactions and interfaces. Second, the article provides two exemplary experiments investigating the aforementioned approach for two distinct AI-systems. The first experiment reveals an interesting gender effect in human-robot interaction, while the second experiment reveals an Eliza effect of a recommender system. Here the article introduces two paradigmatic implementations of the proposed XR testbed for human-AI interactions and interfaces and shows how a valid and systematic investigation can be conducted. In sum, the article opens new perspectives on how XR benefits human-centered AI design and development.}, author = {Wienrich, Carolin and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {aiatwork}, pages = 94, title = {eXtended Artificial Intelligence: New Prospects of Human-AI Interaction Research}, volume = 2, year = 2021 }
• Mapping pre-service teachers’ TPACK development using a social virtual reality and a video-conferencing system. Ripka, Gabriela; Grafe, Silke; Latoschik, Marc Erich. In Proceedings of Innovate Learning Summit 2021, T. Bastiaens (ed.), pp. 145–159. Association for the Advancement of Computing in Education (AACE), 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Social VR's characteristics, by offering authentic learning environments that enable interaction remotely and synchronously and permit learning experiences that affect learners in a multi-sensory way, offer great potential for teaching and learning processes. However, concerning its use to promote pre-service teachers' TPACK in initial teacher education, there remains a research desideratum. In this context, this exploratory study addressed the following research question: How did pre-service teachers' TPACK develop using a social VR learning environment prototype in comparison to a video conferencing platform throughout a semester? Following a design-based research approach, an action-oriented pedagogical concept for teaching and learning in social VR was designed and implemented for initial teacher education at a German university with a convenience sample of 14 participants. The lesson plans were collected and analyzed with the help of Epistemic Network Analysis (Shaffer, 2017) at three points of time during the semester and the GATI reflection process (Krauskopf et al., 2018). Further, 14 GATI diagrams gave insights into pre-service teachers' self-estimated TPACK. As the results indicate, pre-service students constructed more complex mental models of TPACK in social VR compared to the video conferencing platform, indicating that more interrelations between knowledge domains could be constructed by planning and designing VR-integrated lesson plans.

  @inproceedings{gabrielaripka, abstract = {Social VR's characteristics, by offering authentic learning environments that enable interaction remotely and synchronously and permit learning experiences that affect learners in a multi-sensory way, offer great potential for teaching and learning processes. However, concerning its use to promote pre-service teachers' TPACK in initial teacher education, there remains a research desideratum. In this context, this exploratory study addressed the following research question: How did pre-service teachers' TPACK develop using a social VR learning environment prototype in comparison to a video conferencing platform throughout a semester? Following a design-based research approach, an action-oriented pedagogical concept for teaching and learning in social VR was designed and implemented for initial teacher education at a German university with a convenience sample of 14 participants. The lesson plans were collected and analyzed with the help of Epistemic Network Analysis (Shaffer, 2017) at three points of time during the semester and the GATI reflection process (Krauskopf et al., 2018). Further, 14 GATI diagrams gave insights into pre-service teachers' self-estimated TPACK. As the results indicate, pre-service students constructed more complex mental models of TPACK in social VR compared to the video conferencing platform, indicating that more interrelations between knowledge domains could be constructed by planning and designing VR-integrated lesson plans.}, author = {Ripka, Gabriela and Grafe, Silke and Latoschik, Marc Erich}, booktitle = {Proceedings of Innovate Learning Summit 2021}, editor = {Bastiaens, T.}, keywords = {myown}, organization = {Association for the Advancement of Computing in Education (AACE)}, pages = {145-159}, title = {Mapping pre-service teachers' TPACK development using a social virtual reality and a video-conferencing system}, year = 2021 }
• Culture for Socially Interactive Agents. Lugrin, Birgit; Rehm, Matthias. In The Handbook on Socially Interactive Agents – 20 Years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics, Volume 1: Methods, Behavior, Cognition, B. Lugrin, C. Pelachaud, D. Traum (eds.), pp. 463–494. ACM, 2021.
  • [ BibTeX ]
  • [ URL ]
  @incollection{Lugrin_2021, author = {Lugrin, Birgit and Rehm, Matthias}, booktitle = {The Handbook on Socially Interactive Agents – 20 Years of Research on Embodied Conversational Agents, Intelligent Virtual Agents, and Social Robotics, Volume 1: Methods, Behavior, Cognition}, editor = {Lugrin, Birgit and Pelachaud, Catherine and Traum, David}, keywords = {MI}, pages = {463-494}, publisher = {ACM}, title = {Culture for Socially Interactive Agents}, year = 2021 }
• Stigmergic, Diegetic Guidance of Swarm Construction. Truman, Samuel; Seitz, Jakob; von Mammen, Sebastian. In 2021 IEEE International Conference on Autonomic Computing and Self-Organizing Systems Companion (ACSOS-C), pp. 226–231. 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Truman:2021aa, author = {Truman, Samuel and Seitz, Jakob and von Mammen, Sebastian}, booktitle = {2021 IEEE International Conference on Autonomic Computing and Self-Organizing Systems Companion (ACSOS-C)}, keywords = {myown}, pages = {226-231}, title = {Stigmergic, Diegetic Guidance of Swarm Construction}, year = 2021 }
• Enchanted by Your Surrounding? Measuring the Effects of Immersion and Design of Virtual Environments on Decision-Making. Oberdörfer, Sebastian; Heidrich, David; Birnstiel, Sandra; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 2, p. 101. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Impaired decision-making leads to the inability to distinguish between advantageous and disadvantageous choices. The impairment of a person’s decision-making is a common goal of gambling games. Given the recent trend of gambling using immersive Virtual Reality it is crucial to investigate the effects of both immersion and the virtual environment (VE) on decision-making. In a novel user study, we measured decision-making using three virtual versions of the Iowa Gambling Task (IGT). The versions differed with regard to the degree of immersion and design of the virtual environment. While emotions affect decision-making, we further measured the positive and negative affect of participants. A higher visual angle on a stimulus leads to an increased emotional response. Thus, we kept the visual angle on the Iowa Gambling Task the same between our conditions. Our results revealed no significant impact of immersion or the VE on the IGT. We further found no significant difference between the conditions with regard to positive and negative affect. This suggests that neither the medium used nor the design of the VE causes an impairment of decision-making. However, in combination with a recent study, we provide first evidence that a higher visual angle on the IGT leads to an effect of impairment.

  @article{oberdorfer2021enchanted, abstract = {Impaired decision-making leads to the inability to distinguish between advantageous and disadvantageous choices. The impairment of a person’s decision-making is a common goal of gambling games. Given the recent trend of gambling using immersive Virtual Reality it is crucial to investigate the effects of both immersion and the virtual environment (VE) on decision-making. In a novel user study, we measured decision-making using three virtual versions of the Iowa Gambling Task (IGT). The versions differed with regard to the degree of immersion and design of the virtual environment. While emotions affect decision-making, we further measured the positive and negative affect of participants. A higher visual angle on a stimulus leads to an increased emotional response. Thus, we kept the visual angle on the Iowa Gambling Task the same between our conditions. Our results revealed no significant impact of immersion or the VE on the IGT. We further found no significant difference between the conditions with regard to positive and negative affect. This suggests that neither the medium used nor the design of the VE causes an impairment of decision-making. However, in combination with a recent study, we provide first evidence that a higher visual angle on the IGT leads to an effect of impairment.}, author = {Oberdörfer, Sebastian and Heidrich, David and Birnstiel, Sandra and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {dark-sides-vr}, pages = 101, title = {Enchanted by Your Surrounding? Measuring the Effects of Immersion and Design of Virtual Environments on Decision-Making}, volume = 2, year = 2021 }
• Serverless Applications:Why, When, and How?. Eismann, Simon; Joel, Scheuner; van Eyk, Erwin; Schwinger, Maximilian; Grohmann, Johannes; Herbst, Nikolas; Abad, Cristina; Iosup, Alexandru. In IEEE Software, 38(1), pp. 32–39. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Serverless computing shows good promise for efficiency and ease-of-use. Yet, there are only a few, scattered and sometimes conflicting reports on questions such as Why do so many companies adopt serverless?, When are serverless applications well suited?, and How are serverless applications currently implemented? To address these questions, we analyze 89 serverless applications from open-source projects, industrial sources, academic literature, and scientific computing—the most extensive study to date.

  @article{eismann2020serverless, abstract = {Serverless computing shows good promise for efficiency and ease-of-use. Yet, there are only a few, scattered and sometimes conflicting reports on questions such as Why do so many companies adopt serverless?, When are serverless applications well suited?, and How are serverless applications currently implemented? To address these questions, we analyze 89 serverless applications from open-source projects, industrial sources, academic literature, and scientific computing—the most extensive study to date.}, author = {Eismann, Simon and Joel, Scheuner and van Eyk, Erwin and Schwinger, Maximilian and Grohmann, Johannes and Herbst, Nikolas and Abad, Cristina and Iosup, Alexandru}, journal = {IEEE Software}, keywords = {t_journalmagazine}, number = 1, pages = {32–39}, title = {Serverless Applications:Why, When, and How?}, volume = 38, year = 2021 }
• Evaluating the multi-task learning approach for land use regression modelling of air pollution. Dulny, Andrzej; Steininger, Michael; Lautenschlager, Florian; Krause, Anna; Hotho, Andreas. In Journal of Physics: Conference Series, 1834(1), p. 012004. {IOP} Publishing, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Air pollution has been linked to several health problems including heart disease, stroke and lung cancer. Modelling and analyzing this dependency requires reliable and accurate air pollutant measurements collected by stationary air monitoring stations. However, usually only a low number of such stations are present within a single city. To retrieve pollution concentrations for unmeasured locations, researchers rely on land use regression (LUR) models. Those models are typically developed for one pollutant only. However, as results in different areas have shown, modelling several related output variables through multi-task learning can improve the prediction results of the models significantly. In this work, we compared prediction results from single-task and multi-task learning multilayer perceptron models on measurements taken from the OpenSense dataset and the London Atmospheric Emissions Inventory dataset. LUR features were generated from OpenStreetMap using OpenLUR and used to train hard parameter sharing multilayer perceptron models. The results show multi-task learning with sufficient data significantly improves the performance of a LUR model.

  @article{dulny2021evaluating, abstract = {Air pollution has been linked to several health problems including heart disease, stroke and lung cancer. Modelling and analyzing this dependency requires reliable and accurate air pollutant measurements collected by stationary air monitoring stations. However, usually only a low number of such stations are present within a single city. To retrieve pollution concentrations for unmeasured locations, researchers rely on land use regression (LUR) models. Those models are typically developed for one pollutant only. However, as results in different areas have shown, modelling several related output variables through multi-task learning can improve the prediction results of the models significantly. In this work, we compared prediction results from single-task and multi-task learning multilayer perceptron models on measurements taken from the OpenSense dataset and the London Atmospheric Emissions Inventory dataset. LUR features were generated from OpenStreetMap using OpenLUR and used to train hard parameter sharing multilayer perceptron models. The results show multi-task learning with sufficient data significantly improves the performance of a LUR model.}, author = {Dulny, Andrzej and Steininger, Michael and Lautenschlager, Florian and Krause, Anna and Hotho, Andreas}, journal = {Journal of Physics: Conference Series}, keywords = {from:msteininger}, month = {03}, number = 1, organization = {IOP Publishing}, pages = {012004}, publisher = {{IOP} Publishing}, title = {Evaluating the multi-task learning approach for land use regression modelling of air pollution}, volume = 1834, year = 2021 }
• The Embodiment of Photorealistic Avatars Influences Female Body Weight Perception in Virtual Reality. Wolf, Erik; Merdan, Nathalie; Döllinger, Nina; Mal, David; Wienrich, Carolin; Botsch, Mario; Latoschik, Marc Erich. In 2021 IEEE Virtual Reality and 3D User Interfaces (VR), pp. 65–74. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Embodiment and body perception have become important research topics in the field of virtual reality (VR). VR is considered a particularly promising tool to support research and therapy in regard to distorted body weight perception. However, the influence of embodiment on body weight perception has yet to be clarified. To address this gap, we compared body weight perception of 56 female participants of normal weight using a VR application. They either (a) self-embodied a photorealistic, non-personalized virtual human and performed body movements in front of a virtual mirror or (b) only observed the virtual human as other's avatar (or agent) performing the same movements in front of them. Afterward, participants had to estimate the virtual human's body weight. Additionally, we considered the influence of the participants' body mass index (BMI) on the estimations and captured the participants' feelings of presence and embodiment. Participants estimated the body weight of the virtual human as their embodied self-avatars significantly lower compared to participants rating the virtual human as other's avatar. Furthermore, the estimations of body weight were significantly predicted by the participant's BMI with embodiment, but not without. Our results clearly highlight embodiment as an important factor influencing the perception of virtual humans' body weights in VR.

  @inproceedings{wolf2021embodiment, abstract = {Embodiment and body perception have become important research topics in the field of virtual reality (VR). VR is considered a particularly promising tool to support research and therapy in regard to distorted body weight perception. However, the influence of embodiment on body weight perception has yet to be clarified. To address this gap, we compared body weight perception of 56 female participants of normal weight using a VR application. They either (a) self-embodied a photorealistic, non-personalized virtual human and performed body movements in front of a virtual mirror or (b) only observed the virtual human as other's avatar (or agent) performing the same movements in front of them. Afterward, participants had to estimate the virtual human's body weight. Additionally, we considered the influence of the participants' body mass index (BMI) on the estimations and captured the participants' feelings of presence and embodiment. Participants estimated the body weight of the virtual human as their embodied self-avatars significantly lower compared to participants rating the virtual human as other's avatar. Furthermore, the estimations of body weight were significantly predicted by the participant's BMI with embodiment, but not without. Our results clearly highlight embodiment as an important factor influencing the perception of virtual humans' body weights in VR.}, author = {Wolf, Erik and Merdan, Nathalie and Döllinger, Nina and Mal, David and Wienrich, Carolin and Botsch, Mario and Latoschik, Marc Erich}, booktitle = {2021 IEEE Virtual Reality and 3D User Interfaces (VR)}, keywords = {vitras}, pages = {65-74}, title = {The Embodiment of Photorealistic Avatars Influences Female Body Weight Perception in Virtual Reality}, year = 2021 }
• Social robots and gamification for technology supported learning: An empirical study on engagement and motivation. Donnermann, Melissa; Lein, Martina; Messingschlager, Tanja; Riedmann, Anna; Schaper, Philipp; Steinhaeusser, Sophia; Lugrin, Birgit. In Computers in Human Behavior, 121, p. 106792. Elsevier, 2021.
  • [ BibTeX ]
  @article{Donnermann_2021, author = {Donnermann, Melissa and Lein, Martina and Messingschlager, Tanja and Riedmann, Anna and Schaper, Philipp and Steinhaeusser, Sophia and Lugrin, Birgit}, journal = {Computers in Human Behavior}, keywords = {lein}, month = {08}, pages = 106792, publisher = {Elsevier}, title = {Social robots and gamification for technology supported learning: An empirical study on engagement and motivation}, volume = 121, year = 2021 }
• Browser Fingerprinting: How to Protect Machine Learning Models and Data with Differential Privacy?. Dietz, Katharina; Mühlhauser, Michael; Seufert, Michael; Gray, Nicholas; Hoßfeld, Tobias; Herrmann, Dominik. In 1st International Workshop on Machine Learning in Networking (MaLeNe) as part of NetSys’21. Lübeck, Germany (Virtual Conference), 2021.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2021-16, address = {Lübeck, Germany (Virtual Conference)}, author = {Dietz, Katharina and Mühlhauser, Michael and Seufert, Michael and Gray, Nicholas and Hoßfeld, Tobias and Herrmann, Dominik}, booktitle = {1st International Workshop on Machine Learning in Networking (MaLeNe) as part of NetSys'21}, keywords = {ucn}, month = {09}, title = {Browser Fingerprinting: How to Protect Machine Learning Models and Data with Differential Privacy?}, year = 2021 }
• Grab the Frog: Comparing Intuitive Use and User Experience of a Smartphone-only, AR-only, and Tangible AR Learning Environment. Oberdörfer, Sebastian; Elsässer, Anne; Grafe, Silke; Latoschik, Marc Erich. In Proceedings of the 23rd International Conference on Mobile Human-Computer Interaction (MobileHCI ’21). Association for Computing Machinery, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The integration of Augmented Reality (AR) in teaching concepts allows for the visualization of complex learning contents and can simultaneously enhance the learning motivation. By providing Tangible Augmented Reality (TAR), an AR learning environment receives a haptic aspect and allows for a direct manipulation of augmented learning materials. However, manipulating tangible objects while using handheld AR might reduce the intuitive use and hence user experience. Users need to simultaneously control the application and manipulate the tangible object. Therefore, we compare the differences in intuitive use and user experience evoked by varied technologies of knowledge presentation in an educational context. In particular, we compare a TAR learning environment targeting the learning of the anatomy of vertebrates to its smartphone-only and AR-only versions. The three versions of the learning environment only differ in their method of knowledge presentation. The three versions show a similar perceived intuitive use. The TAR version, however, yielded a significantly higher attractiveness and stimulation than AR-only and smartphone-only. This suggests a positive effect of TAR learning environments on the overall learning experience.

  @inproceedings{oberdorfer2021comparing, abstract = {The integration of Augmented Reality (AR) in teaching concepts allows for the visualization of complex learning contents and can simultaneously enhance the learning motivation. By providing Tangible Augmented Reality (TAR), an AR learning environment receives a haptic aspect and allows for a direct manipulation of augmented learning materials. However, manipulating tangible objects while using handheld AR might reduce the intuitive use and hence user experience. Users need to simultaneously control the application and manipulate the tangible object. Therefore, we compare the differences in intuitive use and user experience evoked by varied technologies of knowledge presentation in an educational context. In particular, we compare a TAR learning environment targeting the learning of the anatomy of vertebrates to its smartphone-only and AR-only versions. The three versions of the learning environment only differ in their method of knowledge presentation. The three versions show a similar perceived intuitive use. The TAR version, however, yielded a significantly higher attractiveness and stimulation than AR-only and smartphone-only. This suggests a positive effect of TAR learning environments on the overall learning experience.}, address = {New York, NY, USA}, author = {Oberdörfer, Sebastian and Elsässer, Anne and Grafe, Silke and Latoschik, Marc Erich}, booktitle = {Proceedings of the 23rd International Conference on Mobile Human-Computer Interaction (MobileHCI '21)}, keywords = {horst}, month = {09}, publisher = {Association for Computing Machinery}, title = {Grab the Frog: Comparing Intuitive Use and User Experience of a Smartphone-only, AR-only, and Tangible AR Learning Environment}, year = 2021 }
• A Case Study on Sampling Strategies for Evaluating Neural Sequential Item Recommendation Models. Dallmann, Alexander; Zoller, Daniel; Hotho, Andreas. In Fifteenth {ACM} Conference on Recommender Systems. {ACM}, 2021.
  • [ BibTeX ]
  @inproceedings{dallmann2021study, author = {Dallmann, Alexander and Zoller, Daniel and Hotho, Andreas}, booktitle = {Fifteenth {ACM} Conference on Recommender Systems}, keywords = {recommender}, month = {09}, publisher = {{ACM}}, title = {A Case Study on Sampling Strategies for Evaluating Neural Sequential Item Recommendation Models}, year = 2021 }
• Valid Statements by the Crowd: Statistical Measures for Precision in Crowdsourced Mobile Measurements. Wamser, Florian; Seufert, Anika; Hall, Andrew; Wunderer, Stefan; Hoßfeld, Tobias. In Network, 1(2), pp. 215–232. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Crowdsourced network measurements (CNMs) are becoming increasingly popular as they assess the performance of a mobile network from the end user’s perspective on a large scale. Here, network measurements are performed directly on the end-users’ devices, thus taking advantage of the real-world conditions end-users encounter. However, this type of uncontrolled measurement raises questions about its validity and reliability. The problem lies in the nature of this type of data collection. In CNMs, mobile network subscribers are involved to a large extent in the measurement process, and collect data themselves for the operator. The collection of data on user devices in arbitrary locations and at uncontrolled times requires means to ensure validity and reliability. To address this issue, our paper defines concepts and guidelines for analyzing the precision of CNMs; specifically, the number of measurements required to make valid statements. In addition to the formal definition of the aspect, we illustrate the problem and use an extensive sample data set to show possible assessment approaches. This data set consists of more than 20.4 million crowdsourced mobile measurements from across France, measured by a commercial data provider.

  @article{info3-article-2021-5, abstract = {Crowdsourced network measurements (CNMs) are becoming increasingly popular as they assess the performance of a mobile network from the end user’s perspective on a large scale. Here, network measurements are performed directly on the end-users’ devices, thus taking advantage of the real-world conditions end-users encounter. However, this type of uncontrolled measurement raises questions about its validity and reliability. The problem lies in the nature of this type of data collection. In CNMs, mobile network subscribers are involved to a large extent in the measurement process, and collect data themselves for the operator. The collection of data on user devices in arbitrary locations and at uncontrolled times requires means to ensure validity and reliability. To address this issue, our paper defines concepts and guidelines for analyzing the precision of CNMs; specifically, the number of measurements required to make valid statements. In addition to the formal definition of the aspect, we illustrate the problem and use an extensive sample data set to show possible assessment approaches. This data set consists of more than 20.4 million crowdsourced mobile measurements from across France, measured by a commercial data provider.}, author = {Wamser, Florian and Seufert, Anika and Hall, Andrew and Wunderer, Stefan and Hoßfeld, Tobias}, journal = {Network}, keywords = {can}, month = {09}, number = 2, pages = {215–232}, title = {Valid Statements by the Crowd: Statistical Measures for Precision in Crowdsourced Mobile Measurements}, volume = 1, year = 2021 }
• Delivering User Experience over Networks: Towards a Quality of Experience Centered Design Cycle for Improved Design of Networked Applications. Seufert, Anika; Schröder, Svenja; Seufert, Michael. In SN Computer Science, 2. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  To deliver the best user experience (UX), the human-centered design cycle (HCDC) serves as a well-established guideline to application developers. However, it does not yet cover network-specific requirements, which become increasingly crucial, as most applications deliver experience over the Internet. The missing network-centric view is provided by Quality of Experience (QoE), which could team up with UX towards an improved overall experience. By considering QoE aspects during the development process, it can be achieved that applications become network-aware by design. In this paper, the Quality of Experience Centered Design Cycle (QoE-CDC) is proposed, which provides guidelines on how to design applications with respect to network-specific requirements and QoE. Its practical value is showcased for popular application types and validated by outlining the design of a new smartphone application. We show that combining HCDC and QoE-CDC will result in an application design, which reaches a high UX and avoids QoE degradation.

  @article{info3-article-2021-6, abstract = {To deliver the best user experience (UX), the human-centered design cycle (HCDC) serves as a well-established guideline to application developers. However, it does not yet cover network-specific requirements, which become increasingly crucial, as most applications deliver experience over the Internet. The missing network-centric view is provided by Quality of Experience (QoE), which could team up with UX towards an improved overall experience. By considering QoE aspects during the development process, it can be achieved that applications become network-aware by design. In this paper, the Quality of Experience Centered Design Cycle (QoE-CDC) is proposed, which provides guidelines on how to design applications with respect to network-specific requirements and QoE. Its practical value is showcased for popular application types and validated by outlining the design of a new smartphone application. We show that combining HCDC and QoE-CDC will result in an application design, which reaches a high UX and avoids QoE degradation.}, author = {Seufert, Anika and Schröder, Svenja and Seufert, Michael}, journal = {SN Computer Science}, keywords = {myown}, month = {09}, title = {Delivering User Experience over Networks: Towards a Quality of Experience Centered Design Cycle for Improved Design of Networked Applications}, volume = 2, year = 2021 }
• Discrete-Time Modeling of NFV Accelerators that Exploit Batched Processing. Geissler, Stefan; Lange, Stanislav; Linguaglossa, Leonardo; Rossi, Dario; Zinner, Thomas; Hoßfeld, Tobias. In ACM Transactions on Modeling and Performance Evaluation of Computing Systems, 6(3), pp. 1–27. 2021.
  • [ BibTeX ]
  @article{info3-article-2021-12, author = {Geissler, Stefan and Lange, Stanislav and Linguaglossa, Leonardo and Rossi, Dario and Zinner, Thomas and Hoßfeld, Tobias}, journal = {ACM Transactions on Modeling and Performance Evaluation of Computing Systems}, keywords = {can}, month = {09}, number = 3, pages = {1-27}, title = {Discrete-Time Modeling of NFV Accelerators that Exploit Batched Processing}, volume = 6, year = 2021 }
• Rule-based Semantic Relation Extraction in Regulatory Documents. Korger, Andreas; Baumeister, Joachim. In Learning. Knowledge. Data. Analytics. Munich, Germany, 2021.
  • [ BibTeX ]
  @inproceedings{Korger2021, address = {Munich, Germany}, author = {Korger, Andreas and Baumeister, Joachim}, booktitle = {Learning. Knowledge. Data. Analytics}, keywords = {myown}, month = {09}, title = {Rule-based Semantic Relation Extraction in Regulatory Documents}, year = 2021 }
• A Simulation-based Optimization Framework for Online Adaptation of Networks. Herrnleben, Stefan; Grohmann, Johannes; Rygielski, Pitor; Lesch, Veronika; Krupitzer, Christian; Kounev, Samuel. In Proceedings of the 12th EAI International Conference on Simulation Tools and Techniques (SIMUtools), of SIMUtools 2020, H. Song, D. Jiang (eds.), pp. 513–532. Springer International Publishing, Cham, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Today's data centers face a rapid change of deployed services, growing complexity, and increasing performance requirements. Customers expect not only round-the-clock availability of the hosted services but also high responsiveness. Besides optimizing software architectures and deployments, networks have to be adapted to handle the changing and volatile demands. Approaches from self-adaptive systems can be used for optimizing data center networks to continuously meet Service Level Agreements (SLAs) between data center operators and customers. However, existing approaches focus only on specific objectives like topology design, power optimization, or traffic engineering. In this paper, we present an extensible framework that analyzes networks using different types of simulation and adapts them subject to multiple objectives using various adaptation techniques. Analyzing each suggested adaptation ensures that performance requirements and SLAs are continuously met. We evaluate our framework w.r.t. (i) general requirements and assessments of languages and frameworks for adaptation models, (ii) finding Pareto-optimal solutions considering a multi-dimensional cost model, and (iii) scalability. The evaluation shows that our approach detects the bottlenecks and the violated SLAs correctly, outputs valid and cost-optimal adaptations, and keeps the runtime for the adaptation process constant even with increasing network size and an increasing number of alternative configurations.

  @inproceedings{HeGrRyLeKrKo2020-SIMUtools-Network-Online-Adaptation, abstract = {Today's data centers face a rapid change of deployed services, growing complexity, and increasing performance requirements. Customers expect not only round-the-clock availability of the hosted services but also high responsiveness. Besides optimizing software architectures and deployments, networks have to be adapted to handle the changing and volatile demands. Approaches from self-adaptive systems can be used for optimizing data center networks to continuously meet Service Level Agreements (SLAs) between data center operators and customers. However, existing approaches focus only on specific objectives like topology design, power optimization, or traffic engineering. In this paper, we present an extensible framework that analyzes networks using different types of simulation and adapts them subject to multiple objectives using various adaptation techniques. Analyzing each suggested adaptation ensures that performance requirements and SLAs are continuously met. We evaluate our framework w.r.t. (i) general requirements and assessments of languages and frameworks for adaptation models, (ii) finding Pareto-optimal solutions considering a multi-dimensional cost model, and (iii) scalability. The evaluation shows that our approach detects the bottlenecks and the violated SLAs correctly, outputs valid and cost-optimal adaptations, and keeps the runtime for the adaptation process constant even with increasing network size and an increasing number of alternative configurations.}, address = {Cham}, author = {Herrnleben, Stefan and Grohmann, Johannes and Rygielski, Pitor and Lesch, Veronika and Krupitzer, Christian and Kounev, Samuel}, booktitle = {Proceedings of the 12th EAI International Conference on Simulation Tools and Techniques (SIMUtools)}, editor = {Song, Houbing and Jiang, Dingde}, keywords = {networking}, month = {08}, pages = {513–532}, publisher = {Springer International Publishing}, series = {SIMUtools 2020}, title = {A Simulation-based Optimization Framework for Online Adaptation of Networks}, year = 2021 }
• A Simulation-based Optimization Framework for Online Adaptation of Networks. Herrnleben, Stefan; Grohmann, Johannes; Rygielski, Pitor; Lesch, Veronika; Krupitzer, Christian; Kounev, Samuel. In Proceedings of the 12th EAI International Conference on Simulation Tools and Techniques (SIMUtools), of SIMUtools 2020, H. Song, D. Jiang (eds.), pp. 513–532. Springer International Publishing, Cham, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Today's data centers face a rapid change of deployed services, growing complexity, and increasing performance requirements. Customers expect not only round-the-clock availability of the hosted services but also high responsiveness. Besides optimizing software architectures and deployments, networks have to be adapted to handle the changing and volatile demands. Approaches from self-adaptive systems can be used for optimizing data center networks to continuously meet Service Level Agreements (SLAs) between data center operators and customers. However, existing approaches focus only on specific objectives like topology design, power optimization, or traffic engineering. In this paper, we present an extensible framework that analyzes networks using different types of simulation and adapts them subject to multiple objectives using various adaptation techniques. Analyzing each suggested adaptation ensures that performance requirements and SLAs are continuously met. We evaluate our framework w.r.t. (i) general requirements and assessments of languages and frameworks for adaptation models, (ii) finding Pareto-optimal solutions considering a multi-dimensional cost model, and (iii) scalability. The evaluation shows that our approach detects the bottlenecks and the violated SLAs correctly, outputs valid and cost-optimal adaptations, and keeps the runtime for the adaptation process constant even with increasing network size and an increasing number of alternative configurations.

  @inproceedings{HeGrRyLeKrKo2020-SIMUtools-Network-Online-Adaptation, abstract = {Today's data centers face a rapid change of deployed services, growing complexity, and increasing performance requirements. Customers expect not only round-the-clock availability of the hosted services but also high responsiveness. Besides optimizing software architectures and deployments, networks have to be adapted to handle the changing and volatile demands. Approaches from self-adaptive systems can be used for optimizing data center networks to continuously meet Service Level Agreements (SLAs) between data center operators and customers. However, existing approaches focus only on specific objectives like topology design, power optimization, or traffic engineering. In this paper, we present an extensible framework that analyzes networks using different types of simulation and adapts them subject to multiple objectives using various adaptation techniques. Analyzing each suggested adaptation ensures that performance requirements and SLAs are continuously met. We evaluate our framework w.r.t. (i) general requirements and assessments of languages and frameworks for adaptation models, (ii) finding Pareto-optimal solutions considering a multi-dimensional cost model, and (iii) scalability. The evaluation shows that our approach detects the bottlenecks and the violated SLAs correctly, outputs valid and cost-optimal adaptations, and keeps the runtime for the adaptation process constant even with increasing network size and an increasing number of alternative configurations.}, address = {Cham}, author = {Herrnleben, Stefan and Grohmann, Johannes and Rygielski, Pitor and Lesch, Veronika and Krupitzer, Christian and Kounev, Samuel}, booktitle = {Proceedings of the 12th EAI International Conference on Simulation Tools and Techniques (SIMUtools)}, editor = {Song, Houbing and Jiang, Dingde}, keywords = {networking}, month = {08}, pages = {513–532}, publisher = {Springer International Publishing}, series = {SIMUtools 2020}, title = {A Simulation-based Optimization Framework for Online Adaptation of Networks}, year = 2021 }
• Performance Evaluation of Hybrid Crowdsensing and Fixed Sensor Systems for Event Detection in Urban Environments. Hirth, Matthias; Seufert, Michael; Lange, Stanislav; Meixner, Markus; Tran-Gia, Phuoc. In Sensors, 21(17), pp. 5880 (1–19). 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Crowdsensing offers a cost-effective way to collect large amounts of environmental sensor data. However, the spatial distribution of crowdsensing sensors can hardly be influenced, as the participants carry the sensors, and, additionally, the quality of the crowdsensed data can vary significantly. Hybrid systems that use mobile users in conjunction with fixed sensors might help to overcome these limitations, as such system allow assessing the quality of the submitted crowdsensed data and provide sensor values where no crowdsensing data is available. In this work, we use a simulation study to first analyze a simple crowdsensing system concerning the detection performance of spatial events to highlight the potential and limitations of a pure crowdsourcing system. The results indicate that even if only a small share of inhabitants participates in crowdsensing, events that have locations correlated with the population density can be easily and quickly detected using such a system. On the contrary, events with uniformly randomly distributed locations are much harder to detect using a simple crowdsensing-based approach. A second evaluation shows that hybrid systems improve the detection probability and time. Finally, we illustrate how to compute the minimum number of fixed sensors for given detection time thresholds in our exemplary scenario.

  @article{info3-article-2021-4, abstract = {Crowdsensing offers a cost-effective way to collect large amounts of environmental sensor data. However, the spatial distribution of crowdsensing sensors can hardly be influenced, as the participants carry the sensors, and, additionally, the quality of the crowdsensed data can vary significantly. Hybrid systems that use mobile users in conjunction with fixed sensors might help to overcome these limitations, as such system allow assessing the quality of the submitted crowdsensed data and provide sensor values where no crowdsensing data is available. In this work, we use a simulation study to first analyze a simple crowdsensing system concerning the detection performance of spatial events to highlight the potential and limitations of a pure crowdsourcing system. The results indicate that even if only a small share of inhabitants participates in crowdsensing, events that have locations correlated with the population density can be easily and quickly detected using such a system. On the contrary, events with uniformly randomly distributed locations are much harder to detect using a simple crowdsensing-based approach. A second evaluation shows that hybrid systems improve the detection probability and time. Finally, we illustrate how to compute the minimum number of fixed sensors for given detection time thresholds in our exemplary scenario.}, author = {Hirth, Matthias and Seufert, Michael and Lange, Stanislav and Meixner, Markus and Tran-Gia, Phuoc}, journal = {Sensors}, keywords = {ucn}, month = {08}, number = 17, pages = {5880 (1-19)}, title = {Performance Evaluation of Hybrid Crowdsensing and Fixed Sensor Systems for Event Detection in Urban Environments}, volume = 21, year = 2021 }
• Subjective And Objective Assessment Of Video Game Context Factors. Metzger, Florian; Schröder, Svenja; Ratetseder, Albert. 2021, August.
  • [ BibTeX ]
  @misc{info3-misc-2021-1, author = {Metzger, Florian and Schröder, Svenja and Ratetseder, Albert}, howpublished = {https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-242471}, keywords = {myown}, month = {08}, title = {Subjective And Objective Assessment Of Video Game Context Factors}, year = 2021 }
• Machine-Learning Based Prediction of Next HTTP Request Arrival Time in Adaptive Video Streaming. Pimpinella, Andrea; Redondi, Alessandro E.C.; Loh, Frank; Seufert, Michael. In 3rd International Workshop on High-Precision, Predictable, and Low-Latency Networking (HiPNet). Izmir, Turkey (Virtual Conference), 2021.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2021-18, address = {Izmir, Turkey (Virtual Conference)}, author = {Pimpinella, Andrea and Redondi, Alessandro E.C. and Loh, Frank and Seufert, Michael}, booktitle = {3rd International Workshop on High-Precision, Predictable, and Low-Latency Networking (HiPNet)}, keywords = {ucn}, month = 10, title = {Machine-Learning Based Prediction of Next HTTP Request Arrival Time in Adaptive Video Streaming}, year = 2021 }
• The Prospects of Cloud Gaming: Do the Benefits Outweigh the Costs?. Metzger, Florian; Rafetseder, Albert; Schröder, Svenja; Zwickl, Patrick. 2021, August.
  • [ BibTeX ]
  @misc{info3-misc-2021-2, author = {Metzger, Florian and Rafetseder, Albert and Schröder, Svenja and Zwickl, Patrick}, howpublished = {https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-242452}, keywords = {myown}, month = {08}, title = {The Prospects of Cloud Gaming: Do the Benefits Outweigh the Costs?}, year = 2021 }
• Comparison of Transformer-Based Sequential Product Recommendation Models for the Coveo Data Challenge. Fischer, Elisabeth; Zoller, Daniel; Hotho, Andreas. In SIGIR Workshop On eCommerce. 2021.
  • [ BibTeX ]
  @article{fischer2021comparison, author = {Fischer, Elisabeth and Zoller, Daniel and Hotho, Andreas}, journal = {SIGIR Workshop On eCommerce}, keywords = 2021, month = {07}, title = {Comparison of Transformer-Based Sequential Product Recommendation Models for the Coveo Data Challenge}, year = 2021 }
• A Predictive Maintenance Methodology: Predicting the Time-to-Failure of Machines in Industry 4.0. Züfle, Marwin; Agne, Joachim; Grohmann, Johannes; Dörtoluk, Ibrahim; Kounev, Samuel. In Proceedings of the 21st IEEE IES International Conference on Industrial Informatics, of INDIN’21. IEEE, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Predictive maintenance is an essential aspect of the concept of Industry 4.0. In contrast to previous maintenance strategies, which plan repairs based on periodic schedules or threshold values, predictive maintenance is normally based on estimating the time-to-failure of machines. Thus, predictive maintenance enables a more efficient and effective maintenance approach. Although much research has already been done on time-to-failure prediction, most existing works provide only specialized approaches for specific machines. In most cases, these are either rotary machines (i.e., bearings) or lithium-ion batteries. To bridge the gap to a more general time-to-failure prediction, we propose a generic end-to-end predictive maintenance methodology for the time-to-failure prediction of industrial machines. Our methodology exhibits a number of novel aspects including a universally applicable method for feature extraction based on different types of sensor data, well-known feature transformation and selection techniques, adjustable target class assignment based on fault records with three different labeling strategies, and the training of multiple state-of-the-art machine learning classification models including hyperparameter optimization. We evaluated our time-to-failure prediction methodology in a real-world case study consisting of monitoring data gathered over several years from a large industrial press. The results demonstrated the effectiveness of the proposed methodology for six different time-to-failure pre-diction windows, as well as for the downscaled binary prediction of impending failures. In this case study, the multi-class feed-forward neural network model achieved the overall best results.

  @inproceedings{ZuAgGrDoKo-INDIN2021-PdM, abstract = {Predictive maintenance is an essential aspect of the concept of Industry 4.0. In contrast to previous maintenance strategies, which plan repairs based on periodic schedules or threshold values, predictive maintenance is normally based on estimating the time-to-failure of machines. Thus, predictive maintenance enables a more efficient and effective maintenance approach. Although much research has already been done on time-to-failure prediction, most existing works provide only specialized approaches for specific machines. In most cases, these are either rotary machines (i.e., bearings) or lithium-ion batteries. To bridge the gap to a more general time-to-failure prediction, we propose a generic end-to-end predictive maintenance methodology for the time-to-failure prediction of industrial machines. Our methodology exhibits a number of novel aspects including a universally applicable method for feature extraction based on different types of sensor data, well-known feature transformation and selection techniques, adjustable target class assignment based on fault records with three different labeling strategies, and the training of multiple state-of-the-art machine learning classification models including hyperparameter optimization. We evaluated our time-to-failure prediction methodology in a real-world case study consisting of monitoring data gathered over several years from a large industrial press. The results demonstrated the effectiveness of the proposed methodology for six different time-to-failure pre-diction windows, as well as for the downscaled binary prediction of impending failures. In this case study, the multi-class feed-forward neural network model achieved the overall best results.}, author = {Züfle, Marwin and Agne, Joachim and Grohmann, Johannes and Dörtoluk, Ibrahim and Kounev, Samuel}, booktitle = {Proceedings of the 21st IEEE IES International Conference on Industrial Informatics}, keywords = {t_interdisciplinary}, month = {07}, publisher = {IEEE}, series = {INDIN'21}, title = {A Predictive Maintenance Methodology: Predicting the Time-to-Failure of Machines in Industry 4.0}, year = 2021 }
• On Machine Learning based Video QoE Estimation Across Different Networks. Orsolic, Irena; Seufert, Michael. In 16th International Conference on Telecommunications (ConTEL), Best Paper Award. Zagreb, Croatia (Virtual Conference), 2021.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2021-10, address = {Zagreb, Croatia (Virtual Conference)}, author = {Orsolic, Irena and Seufert, Michael}, booktitle = {16th International Conference on Telecommunications (ConTEL), Best Paper Award}, keywords = {ucn}, month = {07}, title = {On Machine Learning based Video QoE Estimation Across Different Networks}, year = 2021 }
• Relationship Status: It’s Complicated. Using APM as a QoE-qualifying Tempo Metric. Metzger, Florian; Stulier, Norman; Borchert, Kathrin; Hirth, Matthias. In Proceedings of the 13th International Conference on Quality of Multimedia Experience (QoMEX 2021). 2021.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2021-13, author = {Metzger, Florian and Stulier, Norman and Borchert, Kathrin and Hirth, Matthias}, booktitle = {Proceedings of the 13th International Conference on Quality of Multimedia Experience (QoMEX 2021)}, keywords = {myown}, month = {06}, title = {Relationship Status: It's Complicated. Using APM as a QoE-qualifying Tempo Metric}, year = 2021 }
• On Inter-Rater Reliability for Crowdsourced QoE. Hoßfeld, Tobias; Seufert, Michael; Naderi, Babak. In 13th International Conference on Quality of Multimedia Experience (QoMEX). Montreal, Canada (Virtual Conference), 2021.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2021-9, address = {Montreal, Canada (Virtual Conference)}, author = {Hoßfeld, Tobias and Seufert, Michael and Naderi, Babak}, booktitle = {13th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ucn}, month = {06}, title = {On Inter-Rater Reliability for Crowdsourced QoE}, year = 2021 }
• Distributed Implementation of Deterministic Networking in Existing Non-TSN Ethernet Switches. Grigorjew, Alexej; Baier, Christian; Metzger, Florian; Hoßfeld, Tobias. In Workshop on Time-sensitive and Deterministic Networking (TsDN). 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Deterministic networking is quickly gaining importance, as several domains previously dominated by bus systems are now switching to Ethernet. While standardization efforts, especially from the Time-Sensitive Networking (TSN) group, are ongoing, practical deployments are still far off until configuration guidelines and resource management are able to use these tools to their full potential. As an alternative, this work presents a working implementation of bounded latency with an off-the-shelf non-TSN Ethernet switch. The solution is based on a distributed reservation protocol and admission control. It proves that bounded latency is already possible with simple priority-based transmission, and it provides valuable insights for the development and operation of future real-time networking solutions.

  @inproceedings{info3-inproceedings-2021-6, abstract = {Deterministic networking is quickly gaining importance, as several domains previously dominated by bus systems are now switching to Ethernet. While standardization efforts, especially from the Time-Sensitive Networking (TSN) group, are ongoing, practical deployments are still far off until configuration guidelines and resource management are able to use these tools to their full potential. As an alternative, this work presents a working implementation of bounded latency with an off-the-shelf non-TSN Ethernet switch. The solution is based on a distributed reservation protocol and admission control. It proves that bounded latency is already possible with simple priority-based transmission, and it provides valuable insights for the development and operation of future real-time networking solutions.}, author = {Grigorjew, Alexej and Baier, Christian and Metzger, Florian and Hoßfeld, Tobias}, booktitle = {Workshop on Time-sensitive and Deterministic Networking (TsDN)}, keywords = {ats-performance}, month = {06}, title = {Distributed Implementation of Deterministic Networking in Existing Non-TSN Ethernet Switches}, year = 2021 }
• Dynamic Real-Time Stream Reservation with TAS and Shared Time Windows. Grigorjew, Alexej; Gray, Nicholas; Hoßfeld, Tobias. In 2nd International Workshop on Time-Sensitive and Deterministic Networking (TENSOR). 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Motivated by new use cases such as industrial automation and in-vehicle communication, Time-Sensitive Networking is further improving the layer~2 standards for real-time communication in Ethernet networks. As periodic traffic is a common requirement in such scenarios, the Time Aware Shaper (TAS) is a highly popular mechanism that allows the realization of real-time guarantees in synchronized networks. Most applications in literature suggest to configure the TAS for full stream isolation such that the lowest delays can be achieved. However, this ``zero-queuing'' strategy requires a high amount of computational resources and time, as the configuration of the gate control lists of each port is a complex task, which is not suitable for scenarios with dynamically changing requirements. This paper presents a novel approach with shared time windows. In combination with stream reservation techniques that are commonly applied for asynchronous mechanisms, the network is able to accept new streams during operation without complex reconfiguration, while still benefiting from some degree of isolation compared to conventional asynchronous shapers. The evaluation shows that, given the right circumstances, the number of accepted real-time streams can be improved significantly.

  @inproceedings{info3-inproceedings-2021-7, abstract = {Motivated by new use cases such as industrial automation and in-vehicle communication, Time-Sensitive Networking is further improving the layer 2 standards for real-time communication in Ethernet networks. As periodic traffic is a common requirement in such scenarios, the Time Aware Shaper (TAS) is a highly popular mechanism that allows the realization of real-time guarantees in synchronized networks. Most applications in literature suggest to configure the TAS for full stream isolation such that the lowest delays can be achieved. However, this ``zero-queuing'' strategy requires a high amount of computational resources and time, as the configuration of the gate control lists of each port is a complex task, which is not suitable for scenarios with dynamically changing requirements. This paper presents a novel approach with shared time windows. In combination with stream reservation techniques that are commonly applied for asynchronous mechanisms, the network is able to accept new streams during operation without complex reconfiguration, while still benefiting from some degree of isolation compared to conventional asynchronous shapers. The evaluation shows that, given the right circumstances, the number of accepted real-time streams can be improved significantly.}, author = {Grigorjew, Alexej and Gray, Nicholas and Hoßfeld, Tobias}, booktitle = {2nd International Workshop on Time-Sensitive and Deterministic Networking (TENSOR)}, keywords = {ngn}, month = {06}, title = {Dynamic Real-Time Stream Reservation with TAS and Shared Time Windows}, year = 2021 }
• SARDE: A Framework for Continuous and Self-Adaptive Resource Demand Estimation. Grohmann, Johannes; Eismann, Simon; Bauer, Andr{é}; Spinner, Simon; Blum, Johannes; Herbst, Nikolas; Kounev, Samuel. In ACM Transactions on Autonomous and Adaptive Systems, 15(2). Association for Computing Machinery, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Resource demands are crucial parameters for modeling and predicting the performance of software systems. Currently, resource demand estimators are usually executed once for system analysis. However, the monitored system, as well as the resource demand itself, are subject to constant change in runtime environments. These changes additionally impact the applicability, the required parametrization as well as the resulting accuracy of individual estimation approaches. Over time, this leads to invalid or outdated estimates, which in turn negatively influence the decision-making of adaptive systems. In this article, we present SARDE, a framework for self-adaptive resource demand estimation in continuous environments. SARDE dynamically and continuously tunes, selects, and executes an ensemble of resource demand estimation approaches to adapt to changes in the environment. This creates an autonomous and unsupervised ensemble estimation technique, providing reliable resource demand estimations in dynamic environments. We evaluate SARDE using two realistic datasets. One set of different micro-benchmarks reflecting different possible system states and one dataset consisting of a continuously running application in a changing environment. Our results show that by continuously applying online optimization, selection and estimation, SARDE is able to efficiently adapt to the online trace and reduce the model error using the resulting ensemble technique.

  @article{GrEiBaSpBlHeKo2021-TaaS-SARDE, abstract = {Resource demands are crucial parameters for modeling and predicting the performance of software systems. Currently, resource demand estimators are usually executed once for system analysis. However, the monitored system, as well as the resource demand itself, are subject to constant change in runtime environments. These changes additionally impact the applicability, the required parametrization as well as the resulting accuracy of individual estimation approaches. Over time, this leads to invalid or outdated estimates, which in turn negatively influence the decision-making of adaptive systems. In this article, we present SARDE, a framework for self-adaptive resource demand estimation in continuous environments. SARDE dynamically and continuously tunes, selects, and executes an ensemble of resource demand estimation approaches to adapt to changes in the environment. This creates an autonomous and unsupervised ensemble estimation technique, providing reliable resource demand estimations in dynamic environments. We evaluate SARDE using two realistic datasets. One set of different micro-benchmarks reflecting different possible system states and one dataset consisting of a continuously running application in a changing environment. Our results show that by continuously applying online optimization, selection and estimation, SARDE is able to efficiently adapt to the online trace and reduce the model error using the resulting ensemble technique.}, address = {New York, NY, USA}, author = {Grohmann, Johannes and Eismann, Simon and Bauer, Andr\'{e} and Spinner, Simon and Blum, Johannes and Herbst, Nikolas and Kounev, Samuel}, journal = {ACM Transactions on Autonomous and Adaptive Systems}, keywords = {t_journalmagazine}, month = {06}, number = 2, publisher = {Association for Computing Machinery}, title = {SARDE: A Framework for Continuous and Self-Adaptive Resource Demand Estimation}, volume = 15, year = 2021 }
• High Performance Network Metadata Extraction Using P4 for ML-Based Intrusion Detection Systems. Gray, Nicholas; Dietz, Katharina; Seufert, Michael; Hoßfeld, Tobias. In 22nd International Conference on High Performance Switching and Routing (HPSR). Paris, France (Virtual Conference), 2021.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2021-8, address = {Paris, France (Virtual Conference)}, author = {Gray, Nicholas and Dietz, Katharina and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {22nd International Conference on High Performance Switching and Routing (HPSR)}, keywords = {ucn}, month = {06}, title = {High Performance Network Metadata Extraction Using P4 for ML-Based Intrusion Detection Systems}, year = 2021 }
• Mobile Web and App QoE Monitoring for ISPs - from Encrypted Traffic to Speed Index through Machine Learning. Casas, Pedro; Wassermann, Sarah; Wehner, Nikolas; Seufert, Michael; Schüler, Joshua; Hoßfeld, Tobias. In 13th Wireless and Mobile Networking Conference (WMNC), Best Paper Award. Montreal, Canada (Virtual Conference), 2021.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2021-17, address = {Montreal, Canada (Virtual Conference)}, author = {Casas, Pedro and Wassermann, Sarah and Wehner, Nikolas and Seufert, Michael and Schüler, Joshua and Hoßfeld, Tobias}, booktitle = {13th Wireless and Mobile Networking Conference (WMNC), Best Paper Award}, keywords = {ucn}, month = 10, title = {Mobile Web and App QoE Monitoring for ISPs - from Encrypted Traffic to Speed Index through Machine Learning}, year = 2021 }
• Do Different Deep Metric Learning Losses Lead to Similar Learned Features?. Kobs, Konstantin; Steininger, Michael; Dulny, Andrzej; Hotho, Andreas. In Proceedings of the IEEE/CVF International Conference on Computer Vision (ICCV), pp. 10644–10654. 2021.
  • [ BibTeX ]
  @article{noauthororeditor, author = {Kobs, Konstantin and Steininger, Michael and Dulny, Andrzej and Hotho, Andreas}, journal = {Proceedings of the IEEE/CVF International Conference on Computer Vision (ICCV)}, keywords = 2021, month = 10, pages = {10644-10654}, title = {Do Different Deep Metric Learning Losses Lead to Similar Learned Features?}, year = 2021 }
• SARDE: A Framework for Continuous and Self-Adaptive Resource Demand Estimation. Grohmann, Johannes; Eismann, Simon; Bauer, Andr{é}; Spinner, Simon; Blum, Johannes; Herbst, Nikolas; Kounev, Samuel. In ACM Transactions on Autonomous and Adaptive Systems, 15(2). Association for Computing Machinery, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Resource demands are crucial parameters for modeling and predicting the performance of software systems. Currently, resource demand estimators are usually executed once for system analysis. However, the monitored system, as well as the resource demand itself, are subject to constant change in runtime environments. These changes additionally impact the applicability, the required parametrization as well as the resulting accuracy of individual estimation approaches. Over time, this leads to invalid or outdated estimates, which in turn negatively influence the decision-making of adaptive systems. In this article, we present SARDE, a framework for self-adaptive resource demand estimation in continuous environments. SARDE dynamically and continuously tunes, selects, and executes an ensemble of resource demand estimation approaches to adapt to changes in the environment. This creates an autonomous and unsupervised ensemble estimation technique, providing reliable resource demand estimations in dynamic environments. We evaluate SARDE using two realistic datasets. One set of different micro-benchmarks reflecting different possible system states and one dataset consisting of a continuously running application in a changing environment. Our results show that by continuously applying online optimization, selection and estimation, SARDE is able to efficiently adapt to the online trace and reduce the model error using the resulting ensemble technique.

  @article{GrEiBaSpBlHeKo2021-TaaS-SARDE, abstract = {Resource demands are crucial parameters for modeling and predicting the performance of software systems. Currently, resource demand estimators are usually executed once for system analysis. However, the monitored system, as well as the resource demand itself, are subject to constant change in runtime environments. These changes additionally impact the applicability, the required parametrization as well as the resulting accuracy of individual estimation approaches. Over time, this leads to invalid or outdated estimates, which in turn negatively influence the decision-making of adaptive systems. In this article, we present SARDE, a framework for self-adaptive resource demand estimation in continuous environments. SARDE dynamically and continuously tunes, selects, and executes an ensemble of resource demand estimation approaches to adapt to changes in the environment. This creates an autonomous and unsupervised ensemble estimation technique, providing reliable resource demand estimations in dynamic environments. We evaluate SARDE using two realistic datasets. One set of different micro-benchmarks reflecting different possible system states and one dataset consisting of a continuously running application in a changing environment. Our results show that by continuously applying online optimization, selection and estimation, SARDE is able to efficiently adapt to the online trace and reduce the model error using the resulting ensemble technique.}, address = {New York, NY, USA}, author = {Grohmann, Johannes and Eismann, Simon and Bauer, Andr\'{e} and Spinner, Simon and Blum, Johannes and Herbst, Nikolas and Kounev, Samuel}, journal = {ACM Transactions on Autonomous and Adaptive Systems}, keywords = {t_journalmagazine}, month = {06}, number = 2, publisher = {Association for Computing Machinery}, title = {SARDE: A Framework for Continuous and Self-Adaptive Resource Demand Estimation}, volume = 15, year = 2021 }
• Machine Learning-based Service Function Chain over UAVs: Resource Profiling and Framework. TrungKien, Nguyen; Hoang Anh, Vu; Dinh Phong, Vu; Ngoc Minh, Nguyen; Huu Thanh, Nguyen. In 2021 31st International Telecommunication Networks and Applications Conference (ITNAC). Sydney, Australia, 2021.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2021-21, address = {Sydney, Australia}, author = {TrungKien, Nguyen and Hoang Anh, Vu and Dinh Phong, Vu and Ngoc Minh, Nguyen and Huu Thanh, Nguyen}, booktitle = {2021 31st International Telecommunication Networks and Applications Conference (ITNAC)}, keywords = {myown}, month = 11, title = {Machine Learning-based Service Function Chain over UAVs: Resource Profiling and Framework}, year = 2021 }
• Playing with Dynamic Systems - Battling Swarms in Virtual Reality. B{ü}ttner, Johannes; Merz, Christian; von Mammen, Sebastian. In Applications of Evolutionary Computation, P. A. Castillo, J. L. Jim{é}nez Laredo (eds.), pp. 309–324. Springer International Publishing, Cham, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In this paper, we present a serious game with the goal to provide an engaging and immersive experience to foster the players' understanding of dynamic networked systems. Confronted with attacking swarm networks, the player has to analyse their underlying network topologies and to systematically dismantle the swarms using a set of different weapons. We detail the game design, including the artificial intelligence of the swarm, the play mechanics and the level designs. Finally, we conducted an analysis of the play performances of a test group over the course of the game which revealed a positive learning outcome.

  @inproceedings{10.1007/978-3-030-72699-7_20, abstract = {In this paper, we present a serious game with the goal to provide an engaging and immersive experience to foster the players' understanding of dynamic networked systems. Confronted with attacking swarm networks, the player has to analyse their underlying network topologies and to systematically dismantle the swarms using a set of different weapons. We detail the game design, including the artificial intelligence of the swarm, the play mechanics and the level designs. Finally, we conducted an analysis of the play performances of a test group over the course of the game which revealed a positive learning outcome.}, address = {Cham}, author = {B{\"u}ttner, Johannes and Merz, Christian and von Mammen, Sebastian}, booktitle = {Applications of Evolutionary Computation}, editor = {Castillo, Pedro A. and Jim{\'e}nez Laredo, Juan Luis}, keywords = {myown}, pages = {309–324}, publisher = {Springer International Publishing}, title = {Playing with Dynamic Systems - Battling Swarms in Virtual Reality}, year = 2021 }
• Learning Mathematical Relations Using Deep Tree Models. Wankerl, Sebastian; Dulny, Andrzej; Götz, Gerhard; Hotho, Andreas. In 2021 20th IEEE International Conference on Machine Learning and Applications (ICMLA), pp. 1681–1687. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  To the present day, computer algebra systems used for calculating mathematical relations on a symbolic level are mainly rule-based systems. Only recently, deep learning has been applied to the task of symbolic mathematics. Researchers succeeded in developing neural networks which can do symbolic calculations of the equivalence of multiple pairing of equations. However, the generator used to create mathematical terms in previous research has several drawbacks and as with all deep learning tasks, the quality of the data used for training the models has a significant impact on the quality of the results. In this work, we propose a new generator for polynomials. We use it to train several recursive neural networks to recognize the equivalence, derivative, or variable substitution between pairs of polynomials for the first time. Our results indicate that these mathematical relations are identifiable with the help of deep learning.

  @inproceedings{9680206, abstract = {To the present day, computer algebra systems used for calculating mathematical relations on a symbolic level are mainly rule-based systems. Only recently, deep learning has been applied to the task of symbolic mathematics. Researchers succeeded in developing neural networks which can do symbolic calculations of the equivalence of multiple pairing of equations. However, the generator used to create mathematical terms in previous research has several drawbacks and as with all deep learning tasks, the quality of the data used for training the models has a significant impact on the quality of the results. In this work, we propose a new generator for polynomials. We use it to train several recursive neural networks to recognize the equivalence, derivative, or variable substitution between pairs of polynomials for the first time. Our results indicate that these mathematical relations are identifiable with the help of deep learning.}, author = {Wankerl, Sebastian and Dulny, Andrzej and Götz, Gerhard and Hotho, Andreas}, booktitle = {2021 20th IEEE International Conference on Machine Learning and Applications (ICMLA)}, keywords = {treemodels}, month = 12, pages = {1681-1687}, title = {Learning Mathematical Relations Using Deep Tree Models}, year = 2021 }
• Towards a Mobile Robot Localization Benchmark with Challenging Sensordata in an Industrial Environment. Spiess, Florian; Friesslich, Jonas; Bluemm, Daniel; Mast, Fabio; Vinokour, Dmitrij; Kounev, Samuel; Kaupp, Tobias; Strobel, Norbert. In 2021 20th International Conference on Advanced Robotics (ICAR), pp. 857–864. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  To arrive at a realistic assessment of localization methods in terms of their performance in an industrial environment under various challenging conditions, we provide a benchmark to evaluate algorithms both for individual components as well as multi-sensor systems. For several sensor types, including wheel odometry, RGB cameras, RGB-D cameras, and LIDAR, potential issues were identified. The accuracy of wheel odometry, for example, when there are bumps on the track. For each sensor type, we explicitly chose a track for the benchmark dataset containing situations where the sensor fails to provide adequate measurements. Based on the acquired sensor data, localization can be achieved either using a single sensor information or sensor fusion. To help evaluate the output of associated localization algorithms, we provide a software to evaluate a set of metrics as part of the paper. An example application of the benchmark with state-of-the-art algorithms for each sensor is also provided.

  @inproceedings{9659355, abstract = {To arrive at a realistic assessment of localization methods in terms of their performance in an industrial environment under various challenging conditions, we provide a benchmark to evaluate algorithms both for individual components as well as multi-sensor systems. For several sensor types, including wheel odometry, RGB cameras, RGB-D cameras, and LIDAR, potential issues were identified. The accuracy of wheel odometry, for example, when there are bumps on the track. For each sensor type, we explicitly chose a track for the benchmark dataset containing situations where the sensor fails to provide adequate measurements. Based on the acquired sensor data, localization can be achieved either using a single sensor information or sensor fusion. To help evaluate the output of associated localization algorithms, we provide a software to evaluate a set of metrics as part of the paper. An example application of the benchmark with state-of-the-art algorithms for each sensor is also provided.}, author = {Spiess, Florian and Friesslich, Jonas and Bluemm, Daniel and Mast, Fabio and Vinokour, Dmitrij and Kounev, Samuel and Kaupp, Tobias and Strobel, Norbert}, booktitle = {2021 20th International Conference on Advanced Robotics (ICAR)}, keywords = {t_interdisciplinary}, month = 12, pages = {857-864}, title = {Towards a Mobile Robot Localization Benchmark with Challenging Sensordata in an Industrial Environment}, year = 2021 }
• Recreating a Medieval Mill as a Virtual Learning Environment. Fernes, David; Oberdörfer, Sebastian; Latoschik, Marc Erich. In Proceedings of the 27th ACM Symposium on Virtual Reality Software and Technology (VRST ’21). Association for Computing Machinery, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Historic buildings shown in open-air museums often lack a good accessibility and visitors rarely can interact with them as well as displayed tools to learn about processes. Providing these buildings in Virtual Reality could be a great supplement for museums to provide accessible and interactive offers. To investigate the effectiveness of this approach and to derive design guidelines, we developed an interactive virtual replicate of a medieval mill. We present the design of the mill and the results of a preliminary usability evaluation.

  @inproceedings{fernes2021recreating, abstract = {Historic buildings shown in open-air museums often lack a good accessibility and visitors rarely can interact with them as well as displayed tools to learn about processes. Providing these buildings in Virtual Reality could be a great supplement for museums to provide accessible and interactive offers. To investigate the effectiveness of this approach and to derive design guidelines, we developed an interactive virtual replicate of a medieval mill. We present the design of the mill and the results of a preliminary usability evaluation.}, address = {New York, NY, USA}, author = {Fernes, David and Oberdörfer, Sebastian and Latoschik, Marc Erich}, booktitle = {Proceedings of the 27th ACM Symposium on Virtual Reality Software and Technology (VRST '21)}, keywords = {myown}, month = 12, publisher = {Association for Computing Machinery}, title = {Recreating a Medieval Mill as a Virtual Learning Environment}, year = 2021 }
• Visualisation methods for patient monitoring in anaesthetic procedures using augmented reality. Plabst, Lucas; Oberdörfer, Sebastian; Happel, Oliver; Niebling, Florian. In VRST ’21: 27th ACM Symposium on Virtual Reality Software and Technology, Osaka, Japan, December 2021. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  In health care, there are still many devices with poorly designed user interfaces that can lead to user errors. Especially in acute care, an error can lead to critical conditions in patients. Previous research has shown that the use of augmented reality can help to better monitor the condition of patients and better detect unforeseen events. The system created in this work is intended to aid in the detection of changes in patient and equipment-data in order to increase detection of critical conditions or errors.

  @inproceedings{plabst2021visualisation, abstract = {In health care, there are still many devices with poorly designed user interfaces that can lead to user errors. Especially in acute care, an error can lead to critical conditions in patients. Previous research has shown that the use of augmented reality can help to better monitor the condition of patients and better detect unforeseen events. The system created in this work is intended to aid in the detection of changes in patient and equipment-data in order to increase detection of critical conditions or errors.}, author = {Plabst, Lucas and Oberdörfer, Sebastian and Happel, Oliver and Niebling, Florian}, booktitle = {VRST '21: 27th ACM Symposium on Virtual Reality Software and Technology, Osaka, Japan, December 2021}, keywords = {niebling}, month = 12, title = {Visualisation methods for patient monitoring in anaesthetic procedures using augmented reality}, year = 2021 }
• Conference Talk Training With a Virtual Audience System. Glémarec, Yann; Lugrin, Jean-luc; Bosser, Anne-Gwenn; Buche, Cédric; Latoschik, Marc Erich. In ACM Symposium on Virtual Reality Software and Technology. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper presents the first prototype of a virtual audience sys-tem (VAS) specifically designed as a training tool for conferencetalks. This system has been tailored for university seminars dedi-cated to the preparation and delivery of scientific talks. We describethe required features which have been identified during the de-velopment process. We also summarize the preliminary feedbackreceived from lecturers and students during the first deployment ofthe system in seminars for bachelor and doctoral students. Finally,we discuss future work and research directions. We believe oursystem architecture and features are providing interesting insightson the development and integration of VR-based educational toolsinto university curriculum.

  @article{noauthororeditor, abstract = {This paper presents the first prototype of a virtual audience sys-tem (VAS) specifically designed as a training tool for conferencetalks. This system has been tailored for university seminars dedi-cated to the preparation and delivery of scientific talks. We describethe required features which have been identified during the de-velopment process. We also summarize the preliminary feedbackreceived from lecturers and students during the first deployment ofthe system in seminars for bachelor and doctoral students. Finally,we discuss future work and research directions. We believe oursystem architecture and features are providing interesting insightson the development and integration of VR-based educational toolsinto university curriculum.}, author = {Glémarec, Yann and Lugrin, Jean-luc and Bosser, Anne-Gwenn and Buche, Cédric and Latoschik, Marc Erich}, journal = {ACM Symposium on Virtual Reality Software and Technology}, keywords = {vraudi}, month = 12, title = {Conference Talk Training With a Virtual Audience System}, year = 2021 }
• CoBERT: Scientific Collaboration Prediction via Sequential Recommendation. Koopmann, Tobias; Kobs, Konstantin; Herud, Konstantin; Hotho, Andreas. In 2021 International Conference on Data Mining Workshops (ICDMW), pp. 45–54. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Collaborations are an Important factor for scientific success, as the joint work leads to results individual scientists cannot easily reach. Recommending collaborations automatically can alleviate the time consuming and tedious search for potential collaborators. Usually, such recommendation systems rely on graph structures modeling co-authorship of papers and content-based relations such as similar paper keywords. Models are then trained to estimate the probability of links between certain authors in these graphs.In this paper, we argue that the order of papers is crucial for reliably predicting future collaborations, which is not considered by graph-based recommendation systems. We thus propose to reformulate the task of collaboration recommendation as a sequential recommendation task. Here, we aim to predict the next co-author in a chronologically sorted sequence of an author’s collaborators. We introduce CoBERT, a BERT4Rec inspired model, that predicts the sequence’s next co-author and thus a potential collaborator. Since the order of co-authors of a single paper is not that important compared to the overall paper order, we leverage positional embeddings encoding paper positions instead of co-author positions in the sequence. Additionally, we inject content features about every paper and their co-authors. We evaluate CoBERT on two datasets consisting of papers from the field of Artificial Intelligence and the journal PlosOne. We show that CoBERT can outperform graph-based methods and BERT4Rec when predicting the co-authors of the next paper. We make our code and data available.

  @inproceedings{koopmann2021cobert, abstract = {Collaborations are an Important factor for scientific success, as the joint work leads to results individual scientists cannot easily reach. Recommending collaborations automatically can alleviate the time consuming and tedious search for potential collaborators. Usually, such recommendation systems rely on graph structures modeling co-authorship of papers and content-based relations such as similar paper keywords. Models are then trained to estimate the probability of links between certain authors in these graphs.In this paper, we argue that the order of papers is crucial for reliably predicting future collaborations, which is not considered by graph-based recommendation systems. We thus propose to reformulate the task of collaboration recommendation as a sequential recommendation task. Here, we aim to predict the next co-author in a chronologically sorted sequence of an author’s collaborators. We introduce CoBERT, a BERT4Rec inspired model, that predicts the sequence’s next co-author and thus a potential collaborator. Since the order of co-authors of a single paper is not that important compared to the overall paper order, we leverage positional embeddings encoding paper positions instead of co-author positions in the sequence. Additionally, we inject content features about every paper and their co-authors. We evaluate CoBERT on two datasets consisting of papers from the field of Artificial Intelligence and the journal PlosOne. We show that CoBERT can outperform graph-based methods and BERT4Rec when predicting the co-authors of the next paper. We make our code and data available.}, author = {Koopmann, Tobias and Kobs, Konstantin and Herud, Konstantin and Hotho, Andreas}, booktitle = {2021 International Conference on Data Mining Workshops (ICDMW)}, keywords = {recommender}, month = 12, pages = {45-54}, title = {CoBERT: Scientific Collaboration Prediction via Sequential Recommendation}, year = 2021 }
• People Detection with Depth Silhouettes and Convolutional Neural Networks on a Mobile Robot. Spiess, Florian; Reinhart, Lucas; Strobel, Norbert; Kaiser, Dennis; Kounev, Samuel; Kaupp, Tobias. In Journal of Image and Graphics, 9(4), J. of Image; Graphics (eds.), pp. 135–139. 2021.
  • [ BibTeX ]
  • [ URL ]
  @article{spiess2021people, author = {Spiess, Florian and Reinhart, Lucas and Strobel, Norbert and Kaiser, Dennis and Kounev, Samuel and Kaupp, Tobias}, editor = {of Image, Journal and Graphics}, journal = {Journal of Image and Graphics}, keywords = {t_journalmagazine}, month = 12, number = 4, pages = {135-139}, title = {People Detection with Depth Silhouettes and Convolutional Neural Networks on a Mobile Robot}, volume = 9, year = 2021 }
• People Detection with Depth Silhouettes and Convolutional Neural Networks on a Mobile Robot. Spiess, Florian; Reinhart, Lucas; Strobel, Norbert; Kaiser, Dennis; Kounev, Samuel; Kaupp, Tobias. In Journal of Image and Graphics, 9(4), J. of Image; Graphics (eds.), pp. 135–139. 2021.
  • [ BibTeX ]
  • [ URL ]
  @article{spiess2021people, author = {Spiess, Florian and Reinhart, Lucas and Strobel, Norbert and Kaiser, Dennis and Kounev, Samuel and Kaupp, Tobias}, editor = {of Image, Journal and Graphics}, journal = {Journal of Image and Graphics}, keywords = {t_journalmagazine}, month = 12, number = 4, pages = {135-139}, title = {People Detection with Depth Silhouettes and Convolutional Neural Networks on a Mobile Robot}, volume = 9, year = 2021 }
• Towards a Mobile Robot Localization Benchmark with Challenging Sensordata in an Industrial Environment. Spiess, Florian; Friesslich, Jonas; Bluemm, Daniel; Mast, Fabio; Vinokour, Dmitrij; Kounev, Samuel; Kaupp, Tobias; Strobel, Norbert. In 2021 20th International Conference on Advanced Robotics (ICAR), pp. 857–864. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  To arrive at a realistic assessment of localization methods in terms of their performance in an industrial environment under various challenging conditions, we provide a benchmark to evaluate algorithms both for individual components as well as multi-sensor systems. For several sensor types, including wheel odometry, RGB cameras, RGB-D cameras, and LIDAR, potential issues were identified. The accuracy of wheel odometry, for example, when there are bumps on the track. For each sensor type, we explicitly chose a track for the benchmark dataset containing situations where the sensor fails to provide adequate measurements. Based on the acquired sensor data, localization can be achieved either using a single sensor information or sensor fusion. To help evaluate the output of associated localization algorithms, we provide a software to evaluate a set of metrics as part of the paper. An example application of the benchmark with state-of-the-art algorithms for each sensor is also provided.

  @inproceedings{9659355, abstract = {To arrive at a realistic assessment of localization methods in terms of their performance in an industrial environment under various challenging conditions, we provide a benchmark to evaluate algorithms both for individual components as well as multi-sensor systems. For several sensor types, including wheel odometry, RGB cameras, RGB-D cameras, and LIDAR, potential issues were identified. The accuracy of wheel odometry, for example, when there are bumps on the track. For each sensor type, we explicitly chose a track for the benchmark dataset containing situations where the sensor fails to provide adequate measurements. Based on the acquired sensor data, localization can be achieved either using a single sensor information or sensor fusion. To help evaluate the output of associated localization algorithms, we provide a software to evaluate a set of metrics as part of the paper. An example application of the benchmark with state-of-the-art algorithms for each sensor is also provided.}, author = {Spiess, Florian and Friesslich, Jonas and Bluemm, Daniel and Mast, Fabio and Vinokour, Dmitrij and Kounev, Samuel and Kaupp, Tobias and Strobel, Norbert}, booktitle = {2021 20th International Conference on Advanced Robotics (ICAR)}, keywords = {t_interdisciplinary}, month = 12, pages = {857-864}, title = {Towards a Mobile Robot Localization Benchmark with Challenging Sensordata in an Industrial Environment}, year = 2021 }
• Measuring the Performance Impact of Branching Instructions. Beierlieb, Lukas; Iffländer, Lukas; Milenkoski, Aleksandar; Prantl, Thomas; Kounev, Samuel. In Proceedings of the 12th Symposium on Software Performance 2021 (SSP’21). 2021.
  • [ BibTeX ]
  @inproceedings{Beierlieb_2021_MeasuringthePerformanceImpactofBranchingInstructions., author = {Beierlieb, Lukas and Iffländer, Lukas and Milenkoski, Aleksandar and Prantl, Thomas and Kounev, Samuel}, booktitle = {Proceedings of the 12th Symposium on Software Performance 2021 (SSP'21)}, keywords = {descartes}, month = 11, title = {Measuring the Performance Impact of Branching Instructions}, year = 2021 }
• LoRaPlan: A Software to Evaluate Gateway Placement in LoRaWAN. Loh, Frank; Mehling, Noah; Metzger, Florian; Hoßfeld, Tobias. In 17th International Conference on Network and Service Management. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Long Range Wide Area Network (LoRaWAN) is one of the fastest growing Internet of Things (IoT) access network solutions. One major challenge in current LoRaWAN planning is message collision due to the random channel access. To study the collision behavior in LoRaWAN, we present LoRaPlan in this demonstration. LoRaPlan is a software to evaluate gateway placement decisions by studying the collision probability. Therefore, sensor and gateway locations can be imported to create a LoRaWAN. Furthermore, existing networks can be extended by additional gateways. Based on this setup, network coverage, network quality with regard to the number of sensors a single gateway has to manage, and also transmission quality and collision probabilities can be studied. In this demonstration, first the process of network creation with gateway and sensor import and additional manual gateway placement in LoRaPlan is presented. Different adjustable parameters are shown and the influence on network coverage and collision probability is discussed. At the end of this demonstration, it is possible for the audience to place their own gateways and evaluate own placements by means of collision probability and the coverage.

  @article{info3-article-2021-11, abstract = {Long Range Wide Area Network (LoRaWAN) is one of the fastest growing Internet of Things (IoT) access network solutions. One major challenge in current LoRaWAN planning is message collision due to the random channel access. To study the collision behavior in LoRaWAN, we present LoRaPlan in this demonstration. LoRaPlan is a software to evaluate gateway placement decisions by studying the collision probability. Therefore, sensor and gateway locations can be imported to create a LoRaWAN. Furthermore, existing networks can be extended by additional gateways. Based on this setup, network coverage, network quality with regard to the number of sensors a single gateway has to manage, and also transmission quality and collision probabilities can be studied. In this demonstration, first the process of network creation with gateway and sensor import and additional manual gateway placement in LoRaPlan is presented. Different adjustable parameters are shown and the influence on network coverage and collision probability is discussed. At the end of this demonstration, it is possible for the audience to place their own gateways and evaluate own placements by means of collision probability and the coverage.}, author = {Loh, Frank and Mehling, Noah and Metzger, Florian and Hoßfeld, Tobias}, journal = {17th International Conference on Network and Service Management}, keywords = {5mart}, month = 10, title = {LoRaPlan: A Software to Evaluate Gateway Placement in LoRaWAN}, year = 2021 }
• Measuring the Performance Impact of Branching Instructions. Beierlieb, Lukas; Iffländer, Lukas; Milenkoski, Aleksandar; Prantl, Thomas; Kounev, Samuel. In Proceedings of the 12th Symposium on Software Performance 2021 (SSP’21). 2021.
  • [ BibTeX ]
  @inproceedings{Beierlieb_2021_MeasuringthePerformanceImpactofBranchingInstructions., author = {Beierlieb, Lukas and Iffländer, Lukas and Milenkoski, Aleksandar and Prantl, Thomas and Kounev, Samuel}, booktitle = {Proceedings of the 12th Symposium on Software Performance 2021 (SSP'21)}, keywords = {descartes}, month = 11, title = {Measuring the Performance Impact of Branching Instructions}, year = 2021 }
• Discrete-time Analysis of Multicomponent GI/GI/1 Queueing Networks. Geissler, Stefan; Lange, Stanislav; Tran-Gia, Phuoc; Hoßfeld, Tobias. In Conference on Networked Systems (NetSys). 2021.
  • [ Abstract ]
  • [ BibTeX ]
  In this work, we provide initial insights regarding the error introduced into multicomponent queueing systems by assuming the departure processes of arbitrary GI/GI/1-∞ queues to be renewal processes. To this end, we compute the sojourn time distribution as well as departure distributions of a linear chain of queueing components and compare the results to a simulation of the same system. By applying the renewal approximation, potential autocorrelations of the departure processes are lost. We investigate the magnitude of this error regarding both the sojourn time as well as interdeparture time distributions for a broad set of parameters. Although more indepth studies are needed, our results show that both distributions can be closely approximated, which allows the application of the model to asses the performance of real world NFV function chains.

  @inproceedings{info3-inproceedings-2021-4, abstract = {In this work, we provide initial insights regarding the error introduced into multicomponent queueing systems by assuming the departure processes of arbitrary GI/GI/1-∞ queues to be renewal processes. To this end, we compute the sojourn time distribution as well as departure distributions of a linear chain of queueing components and compare the results to a simulation of the same system. By applying the renewal approximation, potential autocorrelations of the departure processes are lost. We investigate the magnitude of this error regarding both the sojourn time as well as interdeparture time distributions for a broad set of parameters. Although more indepth studies are needed, our results show that both distributions can be closely approximated, which allows the application of the model to asses the performance of real world NFV function chains.}, author = {Geissler, Stefan and Lange, Stanislav and Tran-Gia, Phuoc and Hoßfeld, Tobias}, booktitle = {Conference on Networked Systems (NetSys)}, keywords = {myown}, month = 11, title = {Discrete-time Analysis of Multicomponent GI/GI/1 Queueing Networks}, year = 2021 }
• Fostering Teacher Educator Technology Competencies (TETCs) in and with Virtual Reality. Results from an Exploratory Study. Schröter, Thomas; Tiede, Jennifer; Grafe, Silke; Latoschik, Marc Erich. In Proceedings of Innovate Learning Summit 2021, T. Bastiaens (ed.), pp. 160–170. Association for the Advancement of Computing in Education (AACE), Online, United States, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  This exploratory study presents the findings and implications of a three-hour further development workshop implemented with a convenience sample of six teacher educators from a German university. The workshop aimed at fostering the Teacher Educator Technology Competencies (TETCs)—with a special focus on virtual reality (VR)—while reverting to the didactic principle of action orientation. To test whether this didactic principle is suitable for fostering the media pedagogical competencies of the target group in and with VR and to identify further design principles, a mixed-methods approach was utilized. The data collection consisted of focus group interviews, which were analyzed via qualitative content analysis, and Teacher Educator Technology Surveys (TETS). The analysis revealed that action orientation is a valuable addition to established didactical models in higher education (HE). Also...

  @inproceedings{SchrTiedGraf2021yx, abstract = {This exploratory study presents the findings and implications of a three-hour further development workshop implemented with a convenience sample of six teacher educators from a German university. The workshop aimed at fostering the Teacher Educator Technology Competencies (TETCs)—with a special focus on virtual reality (VR)—while reverting to the didactic principle of action orientation. To test whether this didactic principle is suitable for fostering the media pedagogical competencies of the target group in and with VR and to identify further design principles, a mixed-methods approach was utilized. The data collection consisted of focus group interviews, which were analyzed via qualitative content analysis, and Teacher Educator Technology Surveys (TETS). The analysis revealed that action orientation is a valuable addition to established didactical models in higher education (HE). Also...}, address = {Online, United States}, author = {Schröter, Thomas and Tiede, Jennifer and Grafe, Silke and Latoschik, Marc Erich}, booktitle = {Proceedings of Innovate Learning Summit 2021}, editor = {Bastiaens, Theo}, keywords = {Schröter}, month = 11, pages = {160–170}, publisher = {Association for the Advancement of Computing in Education (AACE)}, title = {Fostering Teacher Educator Technology Competencies (TETCs) in and with Virtual Reality. Results from an Exploratory Study.}, year = 2021 }
• Measuring the Performance Impact of Branching Instructions. Beierlieb, Lukas; Iffländer, Lukas; Milenkoski, Aleksandar; Prantl, Thomas; Kounev, Samuel. In Proceedings of the 12th Symposium on Software Performance 2021 (SSP’21). 2021.
  • [ BibTeX ]
  @inproceedings{Beierlieb_2021_MeasuringthePerformanceImpactofBranchingInstructions., author = {Beierlieb, Lukas and Iffländer, Lukas and Milenkoski, Aleksandar and Prantl, Thomas and Kounev, Samuel}, booktitle = {Proceedings of the 12th Symposium on Software Performance 2021 (SSP'21)}, keywords = {descartes}, month = 11, title = {Measuring the Performance Impact of Branching Instructions}, year = 2021 }
• Energy-Efficiency Comparison of Common Sorting Algorithms. Schmitt, Norbert; Kamthania, Supriya; Rawtani, Nishant; Mendoza, Luis; Lange, Klaus-Dieter; Kounev, Samuel. In 2021 29th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS), pp. 1–8. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  With the rising demand for information technology comes an increase in energy consumption to power it. Namely, cloud computing is constantly growing, in part due to a rising number of devices using the cloud to provide certain functionality. This growth leads to an increase in energy consumption in data centers and is estimated to climb to over 1PWh in 2030. Hardware manufacturers counter the rising demand for energy in cloud data centers by providing techniques to make servers more energy-efficient. However, the advances cannot fully compensate for the growth. To further increase energy efficiency, software needs to be addressed as well but is often neglected by the developers.In this paper, we compare six sorting algorithms, a common task in most programs, against each other in terms of energy efficiency to allow developers to select the best solution to their problem. We selected well-known algorithms in two variants, and two implementation languages, C and Python. We ran each algorithm on two, out of four, state-of-the-art server systems with different CPUs.

  @inproceedings{9614299, abstract = {With the rising demand for information technology comes an increase in energy consumption to power it. Namely, cloud computing is constantly growing, in part due to a rising number of devices using the cloud to provide certain functionality. This growth leads to an increase in energy consumption in data centers and is estimated to climb to over 1PWh in 2030. Hardware manufacturers counter the rising demand for energy in cloud data centers by providing techniques to make servers more energy-efficient. However, the advances cannot fully compensate for the growth. To further increase energy efficiency, software needs to be addressed as well but is often neglected by the developers.In this paper, we compare six sorting algorithms, a common task in most programs, against each other in terms of energy efficiency to allow developers to select the best solution to their problem. We selected well-known algorithms in two variants, and two implementation languages, C and Python. We ran each algorithm on two, out of four, state-of-the-art server systems with different CPUs.}, author = {Schmitt, Norbert and Kamthania, Supriya and Rawtani, Nishant and Mendoza, Luis and Lange, Klaus-Dieter and Kounev, Samuel}, booktitle = {2021 29th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS)}, keywords = {power}, month = 11, pages = {1-8}, title = {Energy-Efficiency Comparison of Common Sorting Algorithms}, year = 2021 }
• Fostering Intercultural Competencies in Initial Teacher Education. Implementation of Educational Design Prototypes using a Social VR Environment. Foerster, Kristina; Hein, Rebecca; Grafe, Silke; Latoschik, Marc Erich; Wienrich, Carolin. In Proceedings of Innovate Learning Summit 2020 2021, T. Bastiaens (ed.), pp. 73–86. Association for the Advancement of Computing in Education (AACE), Online, United States, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The combination of globalization and digitalization emphasizes the importance of media-related and intercultural competencies of teacher educators and pre-service teachers. This article reports on the initial prototypical implementation of a pedagogical concept to foster such competencies of pre-service teachers. The proposed pedagogical concept utilizes a social VR framework since related work on the characteristics of VR indicate that this medium is particularly well suited for intercultural professional development processes. The development is integrated into a larger design-based-research approach that develops a theory-guided and empirically grounded professional development concept for teacher educators with a special focus on TETC 8. TETC provide a suitable competence framework capable of aligning both requirements for media-related as well as intercultural competencies. In an exploratory study with student teachers we designed...

  @inproceedings{FoerHeinGraf2021ys, abstract = {The combination of globalization and digitalization emphasizes the importance of media-related and intercultural competencies of teacher educators and pre-service teachers. This article reports on the initial prototypical implementation of a pedagogical concept to foster such competencies of pre-service teachers. The proposed pedagogical concept utilizes a social VR framework since related work on the characteristics of VR indicate that this medium is particularly well suited for intercultural professional development processes. The development is integrated into a larger design-based-research approach that develops a theory-guided and empirically grounded professional development concept for teacher educators with a special focus on TETC 8. TETC provide a suitable competence framework capable of aligning both requirements for media-related as well as intercultural competencies. In an exploratory study with student teachers we designed...}, address = {Online, United States}, author = {Foerster, Kristina and Hein, Rebecca and Grafe, Silke and Latoschik, Marc Erich and Wienrich, Carolin}, booktitle = {Proceedings of Innovate Learning Summit 2020 2021}, editor = {Bastiaens, Theo}, keywords = {coteach}, month = 11, pages = {73–86}, publisher = {Association for the Advancement of Computing in Education (AACE)}, title = {Fostering Intercultural Competencies in Initial Teacher Education. Implementation of Educational Design Prototypes using a Social VR Environment}, year = 2021 }
• {Towards Splitting Monolithic Workflows into Serverless Functions and Estimating Their Run-Time in the Earth Observation Domain}. Kaiser, Dennis; Dovhan, Bohdan; Bauer, Andr{é}; Kounev, Samuel. In Proceedings of the 12th Symposium on Software Performance (SSP). 2021.
  • [ BibTeX ]
  @inproceedings{kaiser2021split, author = {Kaiser, Dennis and Dovhan, Bohdan and Bauer, Andr{\'e} and Kounev, Samuel}, booktitle = {Proceedings of the 12th Symposium on Software Performance (SSP)}, keywords = {severless}, month = 11, note = {Extended Abstract}, title = {{Towards Splitting Monolithic Workflows into Serverless Functions and Estimating Their Run-Time in the Earth Observation Domain}}, year = 2021 }
• How are your Apps Doing? QoE Inference and Analysis in Mobile Devices. Wehner, Nikolas; Seufert, Michael; Schüler, Joshua; Casas, Pedro; Hoßfeld, Tobias. In 17th International Conference on Network and Service Management (CNSM). Izmir, Turkey (Virtual Conference), 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Web browsing has become the most important application of the Internet for the end user. When it comes to mobile devices, web services are mainly accessed through apps. This paper tackles the problem of Web Quality of Experience (QoE) in mobile devices, with a specific focus on apps QoE monitoring and analysis, using in-network (encrypted) traffic measurements. Measuring apps QoE is complex, not only from an instrumentation point of view, but also from the heterogeneity of user interactions which might realize substantially different user experience. To this end, we conduct a feasibility study on four specific and popular Android apps and their corresponding web services. Our test automation framework emulates and measures different user interactions commonly executed during an app session, including the app startup, clicking, scrolling, and searching. The resulting traffic is characterized on different dimensions, and machine learning models are trained to identify web services, apps, and user interactions, and to infer their QoE. The proposed models can correctly identify the specific web service and app in 86% of the cases and accurately estimate the associated QoE with small errors. Our preliminary study represents a first step towards an in-network, web QoE monitoring solution for mobile-device apps.

  @inproceedings{info3-inproceedings-2021-15, abstract = {Web browsing has become the most important application of the Internet for the end user. When it comes to mobile devices, web services are mainly accessed through apps. This paper tackles the problem of Web Quality of Experience (QoE) in mobile devices, with a specific focus on apps QoE monitoring and analysis, using in-network (encrypted) traffic measurements. Measuring apps QoE is complex, not only from an instrumentation point of view, but also from the heterogeneity of user interactions which might realize substantially different user experience. To this end, we conduct a feasibility study on four specific and popular Android apps and their corresponding web services. Our test automation framework emulates and measures different user interactions commonly executed during an app session, including the app startup, clicking, scrolling, and searching. The resulting traffic is characterized on different dimensions, and machine learning models are trained to identify web services, apps, and user interactions, and to infer their QoE. The proposed models can correctly identify the specific web service and app in 86% of the cases and accurately estimate the associated QoE with small errors. Our preliminary study represents a first step towards an in-network, web QoE monitoring solution for mobile-device apps.}, address = {Izmir, Turkey (Virtual Conference)}, author = {Wehner, Nikolas and Seufert, Michael and Schüler, Joshua and Casas, Pedro and Hoßfeld, Tobias}, booktitle = {17th International Conference on Network and Service Management (CNSM)}, keywords = {ucn}, month = 10, title = {How are your Apps Doing? QoE Inference and Analysis in Mobile Devices}, year = 2021 }
• Improving LoRaWAN’s Successful Information Transmission Rate with Redundancy. Loh, Frank; Raffeck, Simon; Metzger, Florian; Hoßfeld, Tobias. In 17th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob). 2021.
  • [ Abstract ]
  • [ BibTeX ]
  The adaptation of Internet of Things in our everyday life shows different new demands and challenges. One of the fastest growing technologies in this context are Low Power Wide Area Networks with LoRaWAN as one of their most prominent representatives. The promise of this technology is to transmit sensor data over large distances with very little energy consumption. But transmission behavior, and especially overhead and collision probability, must be studied in detail to improve transmission quality and energy consumption due to the random access nature of LoRaWAN. Because of that, this work investigates the LoRaWAN channel capacity by analyzing the transmission overhead, the collision probability, and the data loss. At the end, an energy consumption comparison is done. The contribution is a novel approach based on aggregation and retransmission that shows a decreased data loss of up to 20% compared to the currently used random channel access.

  @inproceedings{info3-inproceedings-2021-19, abstract = {The adaptation of Internet of Things in our everyday life shows different new demands and challenges. One of the fastest growing technologies in this context are Low Power Wide Area Networks with LoRaWAN as one of their most prominent representatives. The promise of this technology is to transmit sensor data over large distances with very little energy consumption. But transmission behavior, and especially overhead and collision probability, must be studied in detail to improve transmission quality and energy consumption due to the random access nature of LoRaWAN. Because of that, this work investigates the LoRaWAN channel capacity by analyzing the transmission overhead, the collision probability, and the data loss. At the end, an energy consumption comparison is done. The contribution is a novel approach based on aggregation and retransmission that shows a decreased data loss of up to 20% compared to the currently used random channel access.}, author = {Loh, Frank and Raffeck, Simon and Metzger, Florian and Hoßfeld, Tobias}, booktitle = {17th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob)}, keywords = {5mart}, month = 10, title = {Improving LoRaWAN’s Successful Information Transmission Rate with Redundancy}, year = 2021 }
• Robust Gateway Placement for Scalable LoRaWAN. Loh, Frank; Bau, Dominique; Zink, Johannes; Wolff, Alexander; Hoßfeld, Tobias. In 13th IFIP Wireless and Mobile Networking Conference (WMNC). 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Many exciting applications are currently emerging due to the use of technology from the Internet of Things (IoT) in Smart Cities. In recent years, Long Range Wide Area Networks (LoRaWANs) have become one of the main technologies in this field due to long distance coverage, low power consumption sensors, and economic reasons. So far, LoRaWANs have been planned and deployed mainly with the aim of minimizing the number of gateways, while still providing coverage in a geographic area. Packet collisions and future traffic have not been considered. In contrast, we present a gateway placement strategy that is robust against an increase in the number of sensors and in the network load. To this end, we modify an existing local search algorithm for a geometric set cover problem such that it takes the capacities of gateways into account. If we set these capacities below the maximum, the network can accommodate additional sensors in the future. Moreover, our algorithm can extend the initial placement once the capacities are exhausted.

  @inproceedings{info3-inproceedings-2021-20, abstract = {Many exciting applications are currently emerging due to the use of technology from the Internet of Things (IoT) in Smart Cities. In recent years, Long Range Wide Area Networks (LoRaWANs) have become one of the main technologies in this field due to long distance coverage, low power consumption sensors, and economic reasons. So far, LoRaWANs have been planned and deployed mainly with the aim of minimizing the number of gateways, while still providing coverage in a geographic area. Packet collisions and future traffic have not been considered. In contrast, we present a gateway placement strategy that is robust against an increase in the number of sensors and in the network load. To this end, we modify an existing local search algorithm for a geometric set cover problem such that it takes the capacities of gateways into account. If we set these capacities below the maximum, the network can accommodate additional sensors in the future. Moreover, our algorithm can extend the initial placement once the capacities are exhausted.}, author = {Loh, Frank and Bau, Dominique and Zink, Johannes and Wolff, Alexander and Hoßfeld, Tobias}, booktitle = {13th IFIP Wireless and Mobile Networking Conference (WMNC)}, keywords = {5mart}, month = 10, title = {Robust Gateway Placement for Scalable LoRaWAN}, year = 2021 }
• Self-Supervised Multi-Task Pretraining Improves Image Aesthetic Assessment. Pfister, Jan; Kobs, Konstantin; Hotho, Andreas. In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR) Workshops, pp. 816–825. 2021.
  • [ BibTeX ]
  @inproceedings{Pfister_2021_CVPR, author = {Pfister, Jan and Kobs, Konstantin and Hotho, Andreas}, booktitle = {Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR) Workshops}, keywords = 2021, month = {06}, pages = {816-825}, title = {Self-Supervised Multi-Task Pretraining Improves Image Aesthetic Assessment}, year = 2021 }
• Sequential Item Recommendation in the MOBA Game Dota 2. Dallmann, Alexander; Kohlmann, Johannes; Zoller, Daniel; Hotho, Andreas. In 2021 International Conference on Data Mining Workshops (ICDMW), pp. 10–17. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Multiplayer Online Battle Arena (MOBA) games such as Dota 2 attract hundreds of thousands of players every year. Despite the large player base, it is still important to attract new players to prevent the community of a game from becoming inactive. Entering MOBA games is, however, often demanding, requiring the player to learn numerous skills at once. An important factor of success is buying the correct items which forms a complex task depending on various in-game factors such as already purchased items, the team composition, or available resources. A recommendation system can support players by reducing the mental effort required to choose a suitable item, helping, e.g., newer players or players returning to the game after a longer break, to focus on other aspects of the game. Since Sequential Item Recommendation (SIR) has proven to be effective in various domains (e.g. e-commerce, movie recommendation or playlist continuation), we explore the applicability of well-known SIR models in the context of purchase recommendations in Dota 2. To facilitate this research, we collect, analyze and publish Dota-350k, a new large dataset based on recent Dota 2 matches. We find that SIR models can be employed effectively for item recommendation in Dota 2. Our results show that models that consider the order of purchases are the most effective. In contrast to other domains, we find RNN-based models to outperform the more recent Transformer-based architectures on Dota-350k.

  @inproceedings{9679858, abstract = {Multiplayer Online Battle Arena (MOBA) games such as Dota 2 attract hundreds of thousands of players every year. Despite the large player base, it is still important to attract new players to prevent the community of a game from becoming inactive. Entering MOBA games is, however, often demanding, requiring the player to learn numerous skills at once. An important factor of success is buying the correct items which forms a complex task depending on various in-game factors such as already purchased items, the team composition, or available resources. A recommendation system can support players by reducing the mental effort required to choose a suitable item, helping, e.g., newer players or players returning to the game after a longer break, to focus on other aspects of the game. Since Sequential Item Recommendation (SIR) has proven to be effective in various domains (e.g. e-commerce, movie recommendation or playlist continuation), we explore the applicability of well-known SIR models in the context of purchase recommendations in Dota 2. To facilitate this research, we collect, analyze and publish Dota-350k, a new large dataset based on recent Dota 2 matches. We find that SIR models can be employed effectively for item recommendation in Dota 2. Our results show that models that consider the order of purchases are the most effective. In contrast to other domains, we find RNN-based models to outperform the more recent Transformer-based architectures on Dota-350k.}, author = {Dallmann, Alexander and Kohlmann, Johannes and Zoller, Daniel and Hotho, Andreas}, booktitle = {2021 International Conference on Data Mining Workshops (ICDMW)}, keywords = {recommender}, month = 12, pages = {10-17}, title = {Sequential Item Recommendation in the MOBA Game Dota 2}, year = 2021 }
• SARDE: A Framework for Continuous and Self-Adaptive Resource Demand Estimation. Grohmann, Johannes; Eismann, Simon; Bauer, Andr{é}; Spinner, Simon; Blum, Johannes; Herbst, Nikolas; Kounev, Samuel. In ACM Transactions on Autonomous and Adaptive Systems, 15(2). Association for Computing Machinery, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Resource demands are crucial parameters for modeling and predicting the performance of software systems. Currently, resource demand estimators are usually executed once for system analysis. However, the monitored system, as well as the resource demand itself, are subject to constant change in runtime environments. These changes additionally impact the applicability, the required parametrization as well as the resulting accuracy of individual estimation approaches. Over time, this leads to invalid or outdated estimates, which in turn negatively influence the decision-making of adaptive systems. In this article, we present SARDE, a framework for self-adaptive resource demand estimation in continuous environments. SARDE dynamically and continuously tunes, selects, and executes an ensemble of resource demand estimation approaches to adapt to changes in the environment. This creates an autonomous and unsupervised ensemble estimation technique, providing reliable resource demand estimations in dynamic environments. We evaluate SARDE using two realistic datasets. One set of different micro-benchmarks reflecting different possible system states and one dataset consisting of a continuously running application in a changing environment. Our results show that by continuously applying online optimization, selection and estimation, SARDE is able to efficiently adapt to the online trace and reduce the model error using the resulting ensemble technique.

  @article{GrEiBaSpBlHeKo2021-TaaS-SARDE, abstract = {Resource demands are crucial parameters for modeling and predicting the performance of software systems. Currently, resource demand estimators are usually executed once for system analysis. However, the monitored system, as well as the resource demand itself, are subject to constant change in runtime environments. These changes additionally impact the applicability, the required parametrization as well as the resulting accuracy of individual estimation approaches. Over time, this leads to invalid or outdated estimates, which in turn negatively influence the decision-making of adaptive systems. In this article, we present SARDE, a framework for self-adaptive resource demand estimation in continuous environments. SARDE dynamically and continuously tunes, selects, and executes an ensemble of resource demand estimation approaches to adapt to changes in the environment. This creates an autonomous and unsupervised ensemble estimation technique, providing reliable resource demand estimations in dynamic environments. We evaluate SARDE using two realistic datasets. One set of different micro-benchmarks reflecting different possible system states and one dataset consisting of a continuously running application in a changing environment. Our results show that by continuously applying online optimization, selection and estimation, SARDE is able to efficiently adapt to the online trace and reduce the model error using the resulting ensemble technique.}, address = {New York, NY, USA}, author = {Grohmann, Johannes and Eismann, Simon and Bauer, Andr\'{e} and Spinner, Simon and Blum, Johannes and Herbst, Nikolas and Kounev, Samuel}, journal = {ACM Transactions on Autonomous and Adaptive Systems}, keywords = {t_journalmagazine}, month = {06}, number = 2, publisher = {Association for Computing Machinery}, title = {SARDE: A Framework for Continuous and Self-Adaptive Resource Demand Estimation}, volume = 15, year = 2021 }
• Detecting Scenes in Fiction: A new Segmentation Task. Zehe, Albin; Konle, Leonard; Dümpelmann, Lea; Gius, Evelyn; Hotho, Andreas; Jannidis, Fotis; Kaufmann, Lucas; Krug, Markus; Puppe, Frank; Reiter, Nils; Schreiber, Annekea; Wiedmer, Nathalie. In Proceedings of the 16th Conference of the {E}uropean Chapter of the Association for Computational Linguistics: Volume 1, Long Papers. ACL, 2021.
  • [ BibTeX ]
  @inproceedings{zehe2021detecting, author = {Zehe, Albin and Konle, Leonard and Dümpelmann, Lea and Gius, Evelyn and Hotho, Andreas and Jannidis, Fotis and Kaufmann, Lucas and Krug, Markus and Puppe, Frank and Reiter, Nils and Schreiber, Annekea and Wiedmer, Nathalie}, booktitle = {Proceedings of the 16th Conference of the {E}uropean Chapter of the Association for Computational Linguistics: Volume 1, Long Papers}, keywords = {selected}, publisher = {ACL}, title = {Detecting Scenes in Fiction: A new Segmentation Task}, year = 2021 }
• Utility-based Vehicle Routing Integrating User Preferences. Lesch, Veronika; Hadry, Marius; Kounev, Samuel; Krupitzer, Christian. In Proceedings of 3rd International Workshop on Pervasive Computing for Vehicular Systems (PerVehicle), 2021. IEEE, 2021.
  • [ BibTeX ]
  @inproceedings{lesch2021utility, author = {Lesch, Veronika and Hadry, Marius and Kounev, Samuel and Krupitzer, Christian}, booktitle = {Proceedings of 3rd International Workshop on Pervasive Computing for Vehicular Systems (PerVehicle), 2021}, keywords = {t_workshop}, month = {03}, publisher = {IEEE}, title = {Utility-based Vehicle Routing Integrating User Preferences}, year = 2021 }
• A Comparison of Mechanisms for Compensating Negative Impacts of System Integration. Lesch, Veronika; Krupitzer, Christian; Stubenrauch, Kevin; Keil, Nico; Becker, Christian; Kounev, Samuel; Segata, Michele. In Future Generation Computer Systems, 116, pp. 117–131. 2021.
  • [ BibTeX ]
  @article{lesch2020comparison, author = {Lesch, Veronika and Krupitzer, Christian and Stubenrauch, Kevin and Keil, Nico and Becker, Christian and Kounev, Samuel and Segata, Michele}, journal = {Future Generation Computer Systems}, keywords = {platooning}, month = {03}, pages = {117-131}, title = {A Comparison of Mechanisms for Compensating Negative Impacts of System Integration}, volume = 116, year = 2021 }
• Measuring the Effects of Virtual Environment Design on Decision-Making. Oberdörfer, Sebastian; Heidrich, David; Birnstiel, Sandra; Latoschik, Marc Erich. In Proceedings of the 28th IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VR ’21), pp. 442–443. IEEE, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Recent research indicates an impairment in decision-making in immersive Virtual Reality (VR) when completing the Iowa Gambling Task (IGT). There is a high potential for emotions to explain the IGT decision-making behavior. The design of a virtual environment (VE) can influence a user’s mood and hence potentially the decisionmaking. In a novel user study, we measure decision-making using three virtual versions of the IGT. The versions differ with regard to the degree of immersion and design of the VE. Our results revealed no significant impact of the VE on the IGT and hence on decision-making.

  @inproceedings{oberdorfer2021measuring, abstract = {Recent research indicates an impairment in decision-making in immersive Virtual Reality (VR) when completing the Iowa Gambling Task (IGT). There is a high potential for emotions to explain the IGT decision-making behavior. The design of a virtual environment (VE) can influence a user’s mood and hence potentially the decisionmaking. In a novel user study, we measure decision-making using three virtual versions of the IGT. The versions differ with regard to the degree of immersion and design of the VE. Our results revealed no significant impact of the VE on the IGT and hence on decision-making.}, author = {Oberdörfer, Sebastian and Heidrich, David and Birnstiel, Sandra and Latoschik, Marc Erich}, booktitle = {Proceedings of the 28th IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VR '21)}, keywords = {myown}, month = {03}, organization = {IEEE}, pages = {442-443}, title = {Measuring the Effects of Virtual Environment Design on Decision-Making}, year = 2021 }
• Talk to Me: Investigating the Traffic Characteristics of Amazon Echo Dot and Google Home. Loh, Frank; Geissler, Stefan; Schaible, Fabian; Hoßfeld, Tobias. In International Conference on Communications and Electronics, ICCE. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  The application area of smart speakers is steadily increasing with the Amazon Echo family and Google Home being brand leaders. Use cases include, among others, updating the calendar, home automation, or simply assisting users in their every day life. With the increasing amount of devices, the traffic generation and requesting process becomes a relevant subject to be studied in order to create traffic models and predict the impact on networks by these types of devices. Furthermore, with a detailed understanding of the devices, service quality can be monitored and improved for the end user. For that reason, in this work the requesting and traffic generation process of the Amazon Echo Dot and Google Home are studied and the generated network load of both devices is compared. With the insights of this study and additional device usage statistics, detailed traffic and usage models can be created.

  @inproceedings{info3-inproceedings-2021-5, abstract = {The application area of smart speakers is steadily increasing with the Amazon Echo family and Google Home being brand leaders. Use cases include, among others, updating the calendar, home automation, or simply assisting users in their every day life. With the increasing amount of devices, the traffic generation and requesting process becomes a relevant subject to be studied in order to create traffic models and predict the impact on networks by these types of devices. Furthermore, with a detailed understanding of the devices, service quality can be monitored and improved for the end user. For that reason, in this work the requesting and traffic generation process of the Amazon Echo Dot and Google Home are studied and the generated network load of both devices is compared. With the insights of this study and additional device usage statistics, detailed traffic and usage models can be created.}, author = {Loh, Frank and Geissler, Stefan and Schaible, Fabian and Hoßfeld, Tobias}, booktitle = {International Conference on Communications and Electronics, ICCE}, keywords = {myown}, month = {01}, title = {Talk to Me: Investigating the Traffic Characteristics of Amazon Echo Dot and Google Home}, year = 2021 }
• ComBench: A Benchmarking Framework for Publish/Subscribe Communication Protocols Under Network Limitations. Herrnleben, Stefan; Leidinger, Maximilian; Lesch, Veronika; Prantl, Thomas; Grohmann, Johannes; Krupitzer, Christian; Kounev, Samuel. In Performance Evaluation Methodologies and Tools, Q. Zhao, L. Xia (eds.), pp. 72–92. Springer International Publishing, Cham, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Efficient and dependable communication is a highly relevant aspect for Internet of Things (IoT) systems in which tiny sensors, actuators, wearables, or other smart devices exchange messages. Various publish/subscribe protocols address the challenges of communication in IoT systems. The selection process of a suitable protocol should consider the communication behavior of the application, the protocol's performance, the resource requirements on the end device, and the network connection quality, as IoT environments often rely on wireless networks. Benchmarking is a common approach to evaluate and compare systems, considering the performance and aspects like dependability or security. In this paper, we present our IoT communication benchmarking framework ComBench for publish/subscribe protocols focusing on constrained networks with varying quality conditions. The benchmarking framework supports system designers, software engineers, and application developers to select and investigate the behavior of communication protocols. Our benchmarking framework contributes to (i) show the impact of fluctuating network quality on communication, (ii) compare multiple protocols, protocol features, and protocol implementations, and (iii) analyze scalability, robustness, and dependability of clients, networks, and brokers in different scenarios. Our case study demonstrates the applicability of our framework to support the decision for the best-suited protocol in various scenarios.

  @inproceedings{10.1007/978-3-030-92511-6_5, abstract = {Efficient and dependable communication is a highly relevant aspect for Internet of Things (IoT) systems in which tiny sensors, actuators, wearables, or other smart devices exchange messages. Various publish/subscribe protocols address the challenges of communication in IoT systems. The selection process of a suitable protocol should consider the communication behavior of the application, the protocol's performance, the resource requirements on the end device, and the network connection quality, as IoT environments often rely on wireless networks. Benchmarking is a common approach to evaluate and compare systems, considering the performance and aspects like dependability or security. In this paper, we present our IoT communication benchmarking framework ComBench for publish/subscribe protocols focusing on constrained networks with varying quality conditions. The benchmarking framework supports system designers, software engineers, and application developers to select and investigate the behavior of communication protocols. Our benchmarking framework contributes to (i) show the impact of fluctuating network quality on communication, (ii) compare multiple protocols, protocol features, and protocol implementations, and (iii) analyze scalability, robustness, and dependability of clients, networks, and brokers in different scenarios. Our case study demonstrates the applicability of our framework to support the decision for the best-suited protocol in various scenarios.}, address = {Cham}, author = {Herrnleben, Stefan and Leidinger, Maximilian and Lesch, Veronika and Prantl, Thomas and Grohmann, Johannes and Krupitzer, Christian and Kounev, Samuel}, booktitle = {Performance Evaluation Methodologies and Tools}, editor = {Zhao, Qianchuan and Xia, Li}, keywords = {networking}, pages = {72–92}, publisher = {Springer International Publishing}, title = {ComBench: A Benchmarking Framework for Publish/Subscribe Communication Protocols Under Network Limitations}, year = 2021 }
• Serverless Applications:Why, When, and How?. Eismann, Simon; Joel, Scheuner; van Eyk, Erwin; Schwinger, Maximilian; Grohmann, Johannes; Herbst, Nikolas; Abad, Cristina; Iosup, Alexandru. In IEEE Software, 38(1), pp. 32–39. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Serverless computing shows good promise for efficiency and ease-of-use. Yet, there are only a few, scattered and sometimes conflicting reports on questions such as Why do so many companies adopt serverless?, When are serverless applications well suited?, and How are serverless applications currently implemented? To address these questions, we analyze 89 serverless applications from open-source projects, industrial sources, academic literature, and scientific computing—the most extensive study to date.

  @article{eismann2020serverless, abstract = {Serverless computing shows good promise for efficiency and ease-of-use. Yet, there are only a few, scattered and sometimes conflicting reports on questions such as Why do so many companies adopt serverless?, When are serverless applications well suited?, and How are serverless applications currently implemented? To address these questions, we analyze 89 serverless applications from open-source projects, industrial sources, academic literature, and scientific computing—the most extensive study to date.}, author = {Eismann, Simon and Joel, Scheuner and van Eyk, Erwin and Schwinger, Maximilian and Grohmann, Johannes and Herbst, Nikolas and Abad, Cristina and Iosup, Alexandru}, journal = {IEEE Software}, keywords = {t_journalmagazine}, number = 1, pages = {32–39}, title = {Serverless Applications:Why, When, and How?}, volume = 38, year = 2021 }
• Benchmarking of Pre- and Post-Quantum Group Encryption Schemes with Focus on IoT. Prantl, Thomas; Prantl, Dominik; Bauer, André; Iffländer, Lukas; Dmitrenko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In 2021 IEEE 40th International Performance Computing and Communications Conference (IPCCC). 2021.
  • [ BibTeX ]
  @inproceedings{PrPrBaIfDmKrKo2021-IPCCC-QuantumGroupEncryption, author = {Prantl, Thomas and Prantl, Dominik and Bauer, André and Iffländer, Lukas and Dmitrenko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, booktitle = {2021 IEEE 40th International Performance Computing and Communications Conference (IPCCC)}, keywords = {sss-group}, title = {Benchmarking of Pre- and Post-Quantum Group Encryption Schemes with Focus on IoT}, year = 2021 }
• Benchmarking of Pre- and Post-Quantum Group Encryption Schemes with Focus on IoT. Prantl, Thomas; Prantl, Dominik; Bauer, André; Iffländer, Lukas; Dmitrenko, Alexandra; Krupitzer, Christian; Kounev, Samuel. In 2021 IEEE 40th International Performance Computing and Communications Conference (IPCCC). 2021.
  • [ BibTeX ]
  @inproceedings{PrPrBaIfDmKrKo2021-IPCCC-QuantumGroupEncryption, author = {Prantl, Thomas and Prantl, Dominik and Bauer, André and Iffländer, Lukas and Dmitrenko, Alexandra and Krupitzer, Christian and Kounev, Samuel}, booktitle = {2021 IEEE 40th International Performance Computing and Communications Conference (IPCCC)}, keywords = {sss-group}, title = {Benchmarking of Pre- and Post-Quantum Group Encryption Schemes with Focus on IoT}, year = 2021 }
• Extending Partial Representations of Rectangular Duals with Given Contact Orientations. Chaplick, Steven; Kindermann, Philipp; Klawitter, Jonathan; Rutter, Ignaz; Wolff, Alexander. In Proceedings of the 12th International Conference on Algorithms and Complexity (CIAC’21), A. Philippou, C. Georgiou (eds.). 2021.
  • [ Abstract ]
  • [ BibTeX ]
  A rectangular dual of a graph G is a contact representation of G with axis-aligned rectangles such that (i) no four rectangles share a point and (ii) the union of all rectangles is a rectangle. The partial representation extension problem for rectangular duals asks whether a given partial rectangular dual can be extended to a rectangular dual, that is, whether there exists a rectangular dual where some vertices are represented by prescribed rectangles. Combinatorially, a rectangular dual can be described by a regular edge labeling (REL), which determines the orientations of the rectangle contacts. We characterize the RELs that admit an extension, which leads to a linear-time testing algorithm. In the affirmative, we can construct an extension in linear time.

  @inproceedings{ckkrw-eprrd-ciac21, abstract = {A rectangular dual of a graph G is a contact representation of G with axis-aligned rectangles such that (i) no four rectangles share a point and (ii) the union of all rectangles is a rectangle. The partial representation extension problem for rectangular duals asks whether a given partial rectangular dual can be extended to a rectangular dual, that is, whether there exists a rectangular dual where some vertices are represented by prescribed rectangles. Combinatorially, a rectangular dual can be described by a regular edge labeling (REL), which determines the orientations of the rectangle contacts. We characterize the RELs that admit an extension, which leads to a linear-time testing algorithm. In the affirmative, we can construct an extension in linear time.}, author = {Chaplick, Steven and Kindermann, Philipp and Klawitter, Jonathan and Rutter, Ignaz and Wolff, Alexander}, booktitle = {Proceedings of the 12th International Conference on Algorithms and Complexity (CIAC'21)}, editor = {Philippou, Anna and Georgiou, Chryssis}, keywords = {myown}, note = {To appear}, title = {Extending Partial Representations of Rectangular Duals with Given Contact Orientations}, year = 2021 }
• Shared Task on Scene Segmentation @ KONVENS 2021. Zehe, Albin; Konle, Leonard; Guhr, Svenja; Dümpelmann, Lea; Gius, Evelyn; Hotho, Andreas; Jannidis, Fotis; Kaufmann, Lucas; Krug, Markus; Puppe, Frank; Reiter, Nils; Schreiber, Annekea. In Shared Task on Scene Segmentation @ KONVENS 2021, pp. 1–21. 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{zehe2021shared, author = {Zehe, Albin and Konle, Leonard and Guhr, Svenja and Dümpelmann, Lea and Gius, Evelyn and Hotho, Andreas and Jannidis, Fotis and Kaufmann, Lucas and Krug, Markus and Puppe, Frank and Reiter, Nils and Schreiber, Annekea}, booktitle = {Shared Task on Scene Segmentation @ KONVENS 2021}, keywords = 2021, pages = {1-21}, title = {Shared Task on Scene Segmentation @ KONVENS 2021}, year = 2021 }
• Proximity dimensions and the emergence of collaboration: a HypTrails study on German AI research. Koopmann, Tobias; Stubbemann, Maximilian; Kapa, Matthias; Paris, Michael; Buenstorf, Guido; Hanika, Tom; Hotho, Andreas; Jäschke, Robert; Stumme, Gerd. In Scientometrics. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Creation and exchange of knowledge depends on collaboration. Recent work has suggested that the emergence of collaboration frequently relies on geographic proximity. However, being co-located tends to be associated with other dimensions of proximity, such as social ties or a shared organizational environment. To account for such factors, multiple dimensions of proximity have been proposed, including cognitive, institutional, organizational, social and geographical proximity. Since they strongly interrelate, disentangling these dimensions and their respective impact on collaboration is challenging. To address this issue, we propose various methods for measuring different dimensions of proximity. We then present an approach to compare and rank them with respect to the extent to which they indicate co-publications and co-inventions. We adapt the HypTrails approach, which was originally developed to explain human navigation, to co-author and co-inventor graphs. We evaluate this approach on a subset of the German research community, specifically academic authors and inventors active in research on artificial intelligence (AI). We find that social proximity and cognitive proximity are more important for the emergence of collaboration than geographic proximity.

  @article{koopmann2021proximity, abstract = {Creation and exchange of knowledge depends on collaboration. Recent work has suggested that the emergence of collaboration frequently relies on geographic proximity. However, being co-located tends to be associated with other dimensions of proximity, such as social ties or a shared organizational environment. To account for such factors, multiple dimensions of proximity have been proposed, including cognitive, institutional, organizational, social and geographical proximity. Since they strongly interrelate, disentangling these dimensions and their respective impact on collaboration is challenging. To address this issue, we propose various methods for measuring different dimensions of proximity. We then present an approach to compare and rank them with respect to the extent to which they indicate co-publications and co-inventions. We adapt the HypTrails approach, which was originally developed to explain human navigation, to co-author and co-inventor graphs. We evaluate this approach on a subset of the German research community, specifically academic authors and inventors active in research on artificial intelligence (AI). We find that social proximity and cognitive proximity are more important for the emergence of collaboration than geographic proximity.}, author = {Koopmann, Tobias and Stubbemann, Maximilian and Kapa, Matthias and Paris, Michael and Buenstorf, Guido and Hanika, Tom and Hotho, Andreas and Jäschke, Robert and Stumme, Gerd}, journal = {Scientometrics}, keywords = {regio}, title = {Proximity dimensions and the emergence of collaboration: a HypTrails study on German AI research}, year = 2021 }
• Energy-Aware Service Function Chain Embedding in Edge-Cloud Environments for IoT Applications. Nguyen Huu, Thanh; TrungKien, Nguyen; Van Hoa, Ngo; Thu Huong, Truong; Wamser, Florian; Hoßfeld, Tobias. In IEEE Internet of Things Journal. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  The implementation of IoT applications faces several challenges in practice, such as compliance with QoS requirements, resource constraints and energy consumption. In this context, the joint paradigm for IoT applications can resolve some of the issues arising in pure cloud computing scenarios, such as those related to latency, energy or privacy. Therefore, an environment could be promising for resource and energy-efficient IoT applications that implement VNF bound together into SFC. However, a resource and energy efficient SFC placement requires smart SFC embedding mechanisms in the environment, as several challenges arise, such as IoT service chain modeling and evaluation, the trade-off between resource allocation, energy efficiency and performance, and the resource dynamics. In this article, we address issues in modeling resource and energy utilization for IoT applications in environments. A smart traffic monitoring IP camera system is deployed as a use case for a realistic modeling of a service chain. The system is implemented in our testbed, which is designed and developed specifically to model and investigate the resource and energy utilization of SFC embedding strategies. A resource and energy-aware SFC strategy in the environment for IoT applications is then proposed. Our algorithm is able to cope with dynamic load and resource situations emerging from dynamic SFC requests. The strategy is evaluated systematically in terms of acceptance ratio of SFC requests, resource efficiency and utilization, power consumption, and VNF migrations depending on the offered system load. Results show that our strategy outperforms some existing approaches in terms of resource and energy efficiency, thus it overcomes the relevant challenges from practice and meets the demands of IoT applications.

  @article{info3-article-2021-2, abstract = {The implementation of IoT applications faces several challenges in practice, such as compliance with QoS requirements, resource constraints and energy consumption. In this context, the joint paradigm for IoT applications can resolve some of the issues arising in pure cloud computing scenarios, such as those related to latency, energy or privacy. Therefore, an environment could be promising for resource and energy-efficient IoT applications that implement VNF bound together into SFC. However, a resource and energy efficient SFC placement requires smart SFC embedding mechanisms in the environment, as several challenges arise, such as IoT service chain modeling and evaluation, the trade-off between resource allocation, energy efficiency and performance, and the resource dynamics. In this article, we address issues in modeling resource and energy utilization for IoT applications in environments. A smart traffic monitoring IP camera system is deployed as a use case for a realistic modeling of a service chain. The system is implemented in our testbed, which is designed and developed specifically to model and investigate the resource and energy utilization of SFC embedding strategies. A resource and energy-aware SFC strategy in the environment for IoT applications is then proposed. Our algorithm is able to cope with dynamic load and resource situations emerging from dynamic SFC requests. The strategy is evaluated systematically in terms of acceptance ratio of SFC requests, resource efficiency and utilization, power consumption, and VNF migrations depending on the offered system load. Results show that our strategy outperforms some existing approaches in terms of resource and energy efficiency, thus it overcomes the relevant challenges from practice and meets the demands of IoT applications.}, author = {Nguyen Huu, Thanh and TrungKien, Nguyen and Van Hoa, Ngo and Thu Huong, Truong and Wamser, Florian and Hoßfeld, Tobias}, journal = {IEEE Internet of Things Journal}, keywords = {ecodane}, month = {03}, title = {Energy-Aware Service Function Chain Embedding in Edge-Cloud Environments for IoT Applications}, year = 2021 }
• Semi-unsupervised Learning: An In-depth Parameter Analysis. Davidson, Padraig; Buckermann, Florian; Steininger, Michael; Krause, Anna; Hotho, Andreas. In KI 2021: Advances in Artificial Intelligence, S. Edelkamp, R. M{ö}ller, E. Rueckert (eds.), pp. 51–66. Springer International Publishing, Cham, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Creating datasets for supervised learning is a very challenging and expensive task, in which each input example has to be annotated with its expected output (e.g. object class). By combining unsupervised and semi-supervised learning, semi-unsupervised learning proposes a new paradigm for partially labeled datasets with additional unknown classes. In this paper we focus on a better understanding of this new learning paradigm and analyze the impact of the amount of labeled data, the number of augmented classes and the selection of hidden classes on the quality of prediction. Especially the number of augmented classes highly influences classification accuracy, which needs tuning for each dataset, since too few and too many augmented classes are detrimental to classifier performance. We also show that we can improve results on a large variety of datasets when using convolutional networks as feature extractors while applying output driven entropy regularization instead of a simple weight based L2 norm.

  @inproceedings{10.1007/978-3-030-87626-5_5, abstract = {Creating datasets for supervised learning is a very challenging and expensive task, in which each input example has to be annotated with its expected output (e.g. object class). By combining unsupervised and semi-supervised learning, semi-unsupervised learning proposes a new paradigm for partially labeled datasets with additional unknown classes. In this paper we focus on a better understanding of this new learning paradigm and analyze the impact of the amount of labeled data, the number of augmented classes and the selection of hidden classes on the quality of prediction. Especially the number of augmented classes highly influences classification accuracy, which needs tuning for each dataset, since too few and too many augmented classes are detrimental to classifier performance. We also show that we can improve results on a large variety of datasets when using convolutional networks as feature extractors while applying output driven entropy regularization instead of a simple weight based L2 norm.}, address = {Cham}, author = {Davidson, Padraig and Buckermann, Florian and Steininger, Michael and Krause, Anna and Hotho, Andreas}, booktitle = {KI 2021: Advances in Artificial Intelligence}, editor = {Edelkamp, Stefan and M{\"o}ller, Ralf and Rueckert, Elmar}, keywords = {susl}, pages = {51–66}, publisher = {Springer International Publishing}, title = {Semi-unsupervised Learning: An In-depth Parameter Analysis}, year = 2021 }
• A financial game with opportunities for fraud. Tritscher, Julian; Krause, Anna; Schl{ö}r, Daniel; Gwinner, Fabian; von Mammen, Sebastian; Hotho, Andreas. In IEE COG 2021, 2021. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Even though companies store large amounts of business data in enterprise resource planning (ERP) systems, obtaining data for financial fraud detection is prohibitively difficult due to privacy concerns and companies protecting trade secrets. One possible solution is game-based generation of synthetic ERP data, which poses the challenge of designing an environment that generates realistic ERP data and allows players to commit many different types of fraud. In this work, we design a multiplayer game that allows players to cooperatively run a fictional company, while simultaneously challenging them to maximize their personal gain. We introduce an approach for letting players explore fraud scenarios through emergent gameplay and present a prototype that may be primed with information from real world ERP systems to generate realistic data.

  @article{tritscherfinancial, abstract = {Even though companies store large amounts of business data in enterprise resource planning (ERP) systems, obtaining data for financial fraud detection is prohibitively difficult due to privacy concerns and companies protecting trade secrets. One possible solution is game-based generation of synthetic ERP data, which poses the challenge of designing an environment that generates realistic ERP data and allows players to commit many different types of fraud. In this work, we design a multiplayer game that allows players to cooperatively run a fictional company, while simultaneously challenging them to maximize their personal gain. We introduce an approach for letting players explore fraud scenarios through emergent gameplay and present a prototype that may be primed with information from real world ERP systems to generate realistic data.}, author = {Tritscher, Julian and Krause, Anna and Schl{\"o}r, Daniel and Gwinner, Fabian and von Mammen, Sebastian and Hotho, Andreas}, journal = {IEE COG 2021}, keywords = 2021, title = {A financial game with opportunities for fraud}, volume = 2021, year = 2021 }
• Malware detection on windows audit logs using LSTMs. Ring, Markus; Schlör, Daniel; Wunderlich, Sarah; Landes, Dieter; Hotho, Andreas. In Computers & Security, 109, p. 102389. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Malware is a constant threat and is continuously evolving. Security systems try to keep up with the constant change. One challenge that arises is the large amount of logs generated on an operating system and the need to clarify which information contributes to the detection of possible malware. This work aims at the detection of malware using neural networks based on Windows audit log events. Neural networks can only process continuous data, but Windows audit logs are sequential and textual data. To address these challenges, we extract features out of the audit log events and use LSTMs to capture sequential effects. We create different subsets of features and analyze the effects of additional information. Features describe for example the action-type of windows audit log events, process names or target files that are accessed. Textual features are represented either as one-hot encoding or embedding representation, for which we compare three different approaches for representation learning. Effects of different feature subsets and representations are evaluated on a publicly available data set. Results indicate that using additional information improves the performance of the LSTM-model. While different representations lead to similar classification results, analysis of the latent space shows differences more precisely where FastText seems to be the most promising representation.

  @article{RING2021102389, abstract = {Malware is a constant threat and is continuously evolving. Security systems try to keep up with the constant change. One challenge that arises is the large amount of logs generated on an operating system and the need to clarify which information contributes to the detection of possible malware. This work aims at the detection of malware using neural networks based on Windows audit log events. Neural networks can only process continuous data, but Windows audit logs are sequential and textual data. To address these challenges, we extract features out of the audit log events and use LSTMs to capture sequential effects. We create different subsets of features and analyze the effects of additional information. Features describe for example the action-type of windows audit log events, process names or target files that are accessed. Textual features are represented either as one-hot encoding or embedding representation, for which we compare three different approaches for representation learning. Effects of different feature subsets and representations are evaluated on a publicly available data set. Results indicate that using additional information improves the performance of the LSTM-model. While different representations lead to similar classification results, analysis of the latent space shows differences more precisely where FastText seems to be the most promising representation.}, author = {Ring, Markus and Schlör, Daniel and Wunderlich, Sarah and Landes, Dieter and Hotho, Andreas}, journal = {Computers & Security}, keywords = {logs}, pages = 102389, title = {Malware detection on windows audit logs using LSTMs}, volume = 109, year = 2021 }
• Angle Covers: Algorithms and Complexity. Evans, William; Gethner, Ellen; Spalding-Jamieson, Jack; Wolff, Alexander. In Journal of Graph Algorithms \& Applications, 25(2), pp. 643–661. 2021.
  • [ BibTeX ]
  @article{egsw-acac-JGAA21, author = {Evans, William and Gethner, Ellen and Spalding-Jamieson, Jack and Wolff, Alexander}, journal = {Journal of Graph Algorithms \& Applications}, keywords = {myown}, number = 2, pages = {643–661}, title = {Angle Covers: Algorithms and Complexity}, volume = 25, year = 2021 }
• A Swarm Grammar-Based Approach to Virtual World Generation. Raies, Yasin; von Mammen, Sebastian. In Artificial Intelligence in Music, Sound, Art and Design, J. Romero, T. Martins, N. Rodr{í}guez-Fern{á}ndez (eds.), pp. 459–474. Springer International Publishing, Cham, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In this work we formulate and propose an extended version of the multi-agent Swarm Grammar (SG) model for the generation of virtual worlds. It unfolds a comparatively small database into a complex world featuring terrain, vegetation and bodies of water. This approach allows for adaptivity of generated assets to their environment, unbounded worlds and interactivity in their generation. In order to evaluate the model, we conducted sensitivity analyses at a local interaction scale. In addition, at a global scale, we investigated two virtual environments, discussing notable interactions, recurring configuration patterns, and obstacles in working with SGs. These analyses showed that SGs can create visually interesting virtual worlds, but require further work in ease of use. Lastly we identified which future extensions might shrink required database sizes.

  @inproceedings{10.1007/978-3-030-72914-1_30, abstract = {In this work we formulate and propose an extended version of the multi-agent Swarm Grammar (SG) model for the generation of virtual worlds. It unfolds a comparatively small database into a complex world featuring terrain, vegetation and bodies of water. This approach allows for adaptivity of generated assets to their environment, unbounded worlds and interactivity in their generation. In order to evaluate the model, we conducted sensitivity analyses at a local interaction scale. In addition, at a global scale, we investigated two virtual environments, discussing notable interactions, recurring configuration patterns, and obstacles in working with SGs. These analyses showed that SGs can create visually interesting virtual worlds, but require further work in ease of use. Lastly we identified which future extensions might shrink required database sizes.}, address = {Cham}, author = {Raies, Yasin and von Mammen, Sebastian}, booktitle = {Artificial Intelligence in Music, Sound, Art and Design}, editor = {Romero, Juan and Martins, Tiago and Rodr{\'i}guez-Fern{\'a}ndez, Nereida}, keywords = {myown}, pages = {459–474}, publisher = {Springer International Publishing}, title = {A Swarm Grammar-Based Approach to Virtual World Generation}, year = 2021 }
• Affordable But Not Cheap: A Case Study of the Effects of Two 3D-Reconstruction Methods of Virtual Humans. Bartl, Andrea; Wenninger, Stephan; Wolf, Erik; Botsch, Mario; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 2. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Realistic and lifelike 3D-reconstruction of virtual humans has various exciting and important use cases. Our and others' appearances have notable effects on ourselves and our interaction partners in virtual environments, e.g., on acceptance, preference, trust, believability, behavior (the Proteus effect), and more. Today, multiple approaches for the 3D-reconstruction of virtual humans exist. They significantly vary in terms of the degree of achievable realism, the technical complexities, and finally, the overall reconstruction costs involved. This article compares two 3D-reconstruction approaches with very different hardware requirements. The high-cost solution uses a typical complex and elaborated camera rig consisting of 94 digital single-lens reflex (DSLR) cameras. The recently developed low-cost solution uses a smartphone camera to create videos that capture multiple views of a person. Both methods use photogrammetric reconstruction and template fitting with the same template model and differ in their adaptation to the method-specific input material. Each method generates high-quality virtual humans ready to be processed, animated, and rendered by standard XR simulation and game engines such as Unreal or Unity. We compare the results of the two 3D-reconstruction methods in an immersive virtual environment against each other in a user study. Our results indicate that the virtual humans from the low-cost approach are perceived similarly to those from the high-cost approach regarding the perceived similarity to the original, human-likeness, beauty, and uncanniness, despite significant differences in the objectively measured quality. The perceived feeling of change of the own body was higher for the low-cost virtual humans. Quality differences were perceived more strongly for one's own body than for other virtual humans.

  @article{bartl2021affordable, abstract = {Realistic and lifelike 3D-reconstruction of virtual humans has various exciting and important use cases. Our and others' appearances have notable effects on ourselves and our interaction partners in virtual environments, e.g., on acceptance, preference, trust, believability, behavior (the Proteus effect), and more. Today, multiple approaches for the 3D-reconstruction of virtual humans exist. They significantly vary in terms of the degree of achievable realism, the technical complexities, and finally, the overall reconstruction costs involved. This article compares two 3D-reconstruction approaches with very different hardware requirements. The high-cost solution uses a typical complex and elaborated camera rig consisting of 94 digital single-lens reflex (DSLR) cameras. The recently developed low-cost solution uses a smartphone camera to create videos that capture multiple views of a person. Both methods use photogrammetric reconstruction and template fitting with the same template model and differ in their adaptation to the method-specific input material. Each method generates high-quality virtual humans ready to be processed, animated, and rendered by standard XR simulation and game engines such as Unreal or Unity. We compare the results of the two 3D-reconstruction methods in an immersive virtual environment against each other in a user study. Our results indicate that the virtual humans from the low-cost approach are perceived similarly to those from the high-cost approach regarding the perceived similarity to the original, human-likeness, beauty, and uncanniness, despite significant differences in the objectively measured quality. The perceived feeling of change of the own body was higher for the low-cost virtual humans. Quality differences were perceived more strongly for one's own body than for other virtual humans.}, author = {Bartl, Andrea and Wenninger, Stephan and Wolf, Erik and Botsch, Mario and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {vitras}, title = {Affordable But Not Cheap: A Case Study of the Effects of Two 3D-Reconstruction Methods of Virtual Humans}, volume = 2, year = 2021 }
• Anthropomorphize me! - Effects of Robot Gender on Listeners’ Perception of the Social Robot NAO in a Storytelling Use Case. Steinhaeusser, Sophia C.; Schaper, Philipp; Akuffo, Ohenewa Bediako; Friedrich, Paula; Ön, Jülide; Lugrin, Birgit. In Companion of the 2021 ACM/IEEE International Conference on Human-Robot Interaction (HRI 2021), C. Bethel, A. Paiva, E. Broadbent, D. Feil-Seifer, D. Szafir (eds.). ACM, 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Steinhaeusser_2021, author = {Steinhaeusser, Sophia C. and Schaper, Philipp and Akuffo, Ohenewa Bediako and Friedrich, Paula and Ön, Jülide and Lugrin, Birgit}, booktitle = {Companion of the 2021 ACM/IEEE International Conference on Human-Robot Interaction (HRI 2021)}, editor = {Bethel, Cindy and Paiva, Ana and Broadbent, Elizabeth and Feil-Seifer, David and Szafir, Daniel}, keywords = {steinhaeusser}, publisher = {ACM}, title = {Anthropomorphize me! - Effects of Robot Gender on Listeners' Perception of the Social Robot NAO in a Storytelling Use Case}, year = 2021 }
• Training a Reinforcement Learning Agent based on XCS in a Competitive Snake Environment. Büttner, Johannes; Von Mammen, Sebastian. In 2021 IEEE Conference on Games (CoG), pp. 1–5. 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Buttner:2021aa, author = {Büttner, Johannes and Von Mammen, Sebastian}, booktitle = {2021 IEEE Conference on Games (CoG)}, keywords = {myown}, pages = {1-5}, title = {Training a Reinforcement Learning Agent based on XCS in a Competitive Snake Environment}, year = 2021 }
• Off-The-Shelf Stylus: Using XR Devices for Handwriting and Sketching on Physically Aligned Virtual Surfaces. Kern, Florian; Kullmann, Peter; Ganal, Elisabeth; Korwisi, Kristof; Stingl, Rene; Niebling, Florian; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 2, D. Zielasko (ed.), p. 69. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This article introduces the Off-The-Shelf Stylus (OTSS), a framework for 2D interaction (in 3D) as well as for handwriting and sketching with digital pen, ink, and paper on physically aligned virtual surfaces in Virtual, Augmented, and Mixed Reality (VR, AR, MR: XR for short). OTSS supports self-made XR styluses based on consumer-grade six-degrees-of-freedom XR controllers and commercially available styluses. The framework provides separate modules for three basic but vital features: 1) The stylus module provides stylus construction and calibration features. 2) The surface module provides surface calibration and visual feedback features for virtual-physical 2D surface alignment using our so-called 3ViSuAl procedure, and surface interaction features. 3) The evaluation suite provides a comprehensive test bed combining technical measurements for precision, accuracy, and latency with extensive usability evaluations including handwriting and sketching tasks based on established visuomotor, graphomotor, and handwriting research. The framework’s development is accompanied by an extensive open source reference implementation targeting the Unity game engine using an Oculus Rift S headset and Oculus Touch controllers. The development compares three low-cost and low-tech options to equip controllers with a tip and includes a web browser-based surface providing support for interacting, handwriting, and sketching. The evaluation of the reference implementation based on the OTSS framework identified an average stylus precision of 0.98 mm (SD = 0.54 mm) and an average surface accuracy of 0.60 mm (SD = 0.32 mm) in a seated VR environment. The time for displaying the stylus movement as digital ink on the web browser surface in VR was 79.40 ms on average (SD = 23.26 ms), including the physical controller’s motion-to-photon latency visualized by its virtual representation (M = 42.57 ms, SD = 15.70 ms). The usability evaluation (N = 10) revealed a low task load, high usability, and high user experience. Participants successfully reproduced given shapes and created legible handwriting, indicating that the OTSS and it’s reference implementation is ready for everyday use. We provide source code access to our implementation, including stylus and surface calibration and surface interaction features, making it easy to reuse, extend, adapt and/or replicate previous results (https://go.uniwue.de/hci-otss).

  @article{kern2021offtheshelf, abstract = {This article introduces the Off-The-Shelf Stylus (OTSS), a framework for 2D interaction (in 3D) as well as for handwriting and sketching with digital pen, ink, and paper on physically aligned virtual surfaces in Virtual, Augmented, and Mixed Reality (VR, AR, MR: XR for short). OTSS supports self-made XR styluses based on consumer-grade six-degrees-of-freedom XR controllers and commercially available styluses. The framework provides separate modules for three basic but vital features: 1) The stylus module provides stylus construction and calibration features. 2) The surface module provides surface calibration and visual feedback features for virtual-physical 2D surface alignment using our so-called 3ViSuAl procedure, and surface interaction features. 3) The evaluation suite provides a comprehensive test bed combining technical measurements for precision, accuracy, and latency with extensive usability evaluations including handwriting and sketching tasks based on established visuomotor, graphomotor, and handwriting research. The framework’s development is accompanied by an extensive open source reference implementation targeting the Unity game engine using an Oculus Rift S headset and Oculus Touch controllers. The development compares three low-cost and low-tech options to equip controllers with a tip and includes a web browser-based surface providing support for interacting, handwriting, and sketching. The evaluation of the reference implementation based on the OTSS framework identified an average stylus precision of 0.98 mm (SD = 0.54 mm) and an average surface accuracy of 0.60 mm (SD = 0.32 mm) in a seated VR environment. The time for displaying the stylus movement as digital ink on the web browser surface in VR was 79.40 ms on average (SD = 23.26 ms), including the physical controller’s motion-to-photon latency visualized by its virtual representation (M = 42.57 ms, SD = 15.70 ms). The usability evaluation (N = 10) revealed a low task load, high usability, and high user experience. Participants successfully reproduced given shapes and created legible handwriting, indicating that the OTSS and it’s reference implementation is ready for everyday use. We provide source code access to our implementation, including stylus and surface calibration and surface interaction features, making it easy to reuse, extend, adapt and/or replicate previous results (https://go.uniwue.de/hci-otss).}, author = {Kern, Florian and Kullmann, Peter and Ganal, Elisabeth and Korwisi, Kristof and Stingl, Rene and Niebling, Florian and Latoschik, Marc Erich}, editor = {Zielasko, Daniel}, journal = {Frontiers in Virtual Reality}, keywords = {vilearn}, pages = 69, title = {Off-The-Shelf Stylus: Using XR Devices for Handwriting and Sketching on Physically Aligned Virtual Surfaces}, volume = 2, year = 2021 }
• Trust but Verify: Crowdsourced Mobile Network Measurements and Statistical Validity Measures. Seufert, Anika; Wamser, Florian; Wunderer, Stefan; Hall, Andrew; Hoßfeld, Tobias. In 2021 Joint European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit). Porto, Portugal (virtual conference), 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Network operators, regulators, and big data companies use crowdsourced measurements to study the performance of mobile networks on a large scale. Such a type of measurement is defined as the collection and processing of data measured by the crowd, here the crowd of mobile subscribers. Crowdsourced network measurements make it relatively easy and inexpensive to obtain large amounts of network data that also reflect the quality actually received by the end user. However, this measurement method also involves some uncertainties, since, for example, it is not possible to precisely control when, where and with which devices measurements are taken. Thus, there is a trade-off between the reliability of the individual measurement and the scope of the measurements. Therefore, how data of this type is analyzed is particularly important in order to obtain valid results. To address this issue, our paper defines concepts and guidelines for analyzing the validity of crowdsourced mobile network measurements. In particular, we address precision, for example the number of measurements needed to make valid statements, and also representativeness, for example the spatial and temporal distribution of the data. In addition to the formal definition of these two aspects, we illustrate the issue and possible evaluation approaches with the help of an extensive example data set. This data set consists of more than 11.7M crowdsourced mobile measurements from all over France, measured by a commercial mobile data provider. In the end, we provide an evaluation guideline and two possible use cases.

  @inproceedings{info3-inproceedings-2021-11, abstract = {Network operators, regulators, and big data companies use crowdsourced measurements to study the performance of mobile networks on a large scale. Such a type of measurement is defined as the collection and processing of data measured by the crowd, here the crowd of mobile subscribers. Crowdsourced network measurements make it relatively easy and inexpensive to obtain large amounts of network data that also reflect the quality actually received by the end user. However, this measurement method also involves some uncertainties, since, for example, it is not possible to precisely control when, where and with which devices measurements are taken. Thus, there is a trade-off between the reliability of the individual measurement and the scope of the measurements. Therefore, how data of this type is analyzed is particularly important in order to obtain valid results. To address this issue, our paper defines concepts and guidelines for analyzing the validity of crowdsourced mobile network measurements. In particular, we address precision, for example the number of measurements needed to make valid statements, and also representativeness, for example the spatial and temporal distribution of the data. In addition to the formal definition of these two aspects, we illustrate the issue and possible evaluation approaches with the help of an extensive example data set. This data set consists of more than 11.7M crowdsourced mobile measurements from all over France, measured by a commercial mobile data provider. In the end, we provide an evaluation guideline and two possible use cases.}, address = {Porto, Portugal (virtual conference)}, author = {Seufert, Anika and Wamser, Florian and Wunderer, Stefan and Hall, Andrew and Hoßfeld, Tobias}, booktitle = {2021 Joint European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit)}, keywords = {can}, month = {06}, title = {Trust but Verify: Crowdsourced Mobile Network Measurements and Statistical Validity Measures}, year = 2021 }
• Effects of Immersion and Visual Angle on Brand Placement Effectiveness. Oberdörfer, Sebastian; Straka, Samantha; Latoschik, Marc Erich. In Proceedings of the 28th IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VR ’21), pp. 440–441. IEEE, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Typical inherent properties of immersive Virtual Reality (VR) such as felt presence might have an impact on how well brand placements are remembered. In this study, we exposed participants to brand placements in four conditions of varying degrees of immersion and visual angle on the stimulus. Placements appeared either as poster or as puzzle. We measured the recall and recognition of these placements. Our study revealed that neither immersion nor the visual angle had a significant impact on memory for brand placements.

  @inproceedings{oberdorfer2021effects, abstract = {Typical inherent properties of immersive Virtual Reality (VR) such as felt presence might have an impact on how well brand placements are remembered. In this study, we exposed participants to brand placements in four conditions of varying degrees of immersion and visual angle on the stimulus. Placements appeared either as poster or as puzzle. We measured the recall and recognition of these placements. Our study revealed that neither immersion nor the visual angle had a significant impact on memory for brand placements.}, author = {Oberdörfer, Sebastian and Straka, Samantha and Latoschik, Marc Erich}, booktitle = {Proceedings of the 28th IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VR '21)}, keywords = {myown}, month = {03}, organization = {IEEE}, pages = {440-441}, title = {Effects of Immersion and Visual Angle on Brand Placement Effectiveness}, year = 2021 }
• Put that Away and Talk to Me - the Effects of Smartphone induced Ostracism while Interacting with an Intelligent Virtual Agent. Obremski, David; Schäfer, Alicia L.; Lange, Benjamin P.; Lugrin, Birgit; Ganal, Elisabeth; Witt, Laura; Nuñez, Tania R.; Schwarz, Sascha; Schwab, Frank. In Proceedings of the 9th International Conference on Human-Agent Interaction 2021. ACM, 2021.
  • [ BibTeX ]
  @inproceedings{Obremski_2021, author = {Obremski, David and Schäfer, Alicia L. and Lange, Benjamin P. and Lugrin, Birgit and Ganal, Elisabeth and Witt, Laura and Nuñez, Tania R. and Schwarz, Sascha and Schwab, Frank}, booktitle = {Proceedings of the 9th International Conference on Human-Agent Interaction 2021}, keywords = {mi}, publisher = {ACM}, title = {Put that Away and Talk to Me - the Effects of Smartphone induced Ostracism while Interacting with an Intelligent Virtual Agent}, year = 2021 }
• Improving Web QoE Monitoring for Encrypted Network Traffic through Time Series Modeling. Wehner, Nikolas; Seufert, Michael; Schüler, Joshua; Wassermann, Sarah; Casas, Pedro; Hoßfeld, Tobias. In ACM SIGMETRICS Performance Evaluation Review, 48(4), pp. 37–40. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  This paper addresses the problem of Quality of Experience (QoE) monitoring for web browsing. In particular, the inference of common Web QoE metrics such as Speed Index (SI) is investigated. Based on a large dataset collected with open web-measurement platforms on different device-types, a unique feature set is designed and used to estimate the RUMSI -- an efficient approximation to SI, with machine-learning based regression and classification approaches. Results indicate that it is possible to estimate the RUMSI accurately, and that in particular, recurrent neural networks are highly suitable for the task, as they capture the network dynamics more precisely.

  @article{info3-article-2020-4, abstract = {This paper addresses the problem of Quality of Experience (QoE) monitoring for web browsing. In particular, the inference of common Web QoE metrics such as Speed Index (SI) is investigated. Based on a large dataset collected with open web-measurement platforms on different device-types, a unique feature set is designed and used to estimate the RUMSI – an efficient approximation to SI, with machine-learning based regression and classification approaches. Results indicate that it is possible to estimate the RUMSI accurately, and that in particular, recurrent neural networks are highly suitable for the task, as they capture the network dynamics more precisely.}, author = {Wehner, Nikolas and Seufert, Michael and Schüler, Joshua and Wassermann, Sarah and Casas, Pedro and Hoßfeld, Tobias}, journal = {ACM SIGMETRICS Performance Evaluation Review}, keywords = {ucn}, month = {03}, number = 4, pages = {37-40}, title = {Improving Web QoE Monitoring for Encrypted Network Traffic through Time Series Modeling}, volume = 48, year = 2021 }
• Towards a Group Encryption Scheme Benchmark: A View on Centralized Schemes with focus on IoT. Prantl, Thomas; Ten, Peter; Iffländer, Lukas; Herrnleben, Stefan; Dmitrenko, Alexandra; Kounev, Samuel; Krupitzer, Christian. In 2021 ACM/SPEC International Conference on Performance Engineering (ICPE), of ICPE’21. 2021.
  • [ BibTeX ]
  @inproceedings{PrTeIfHeDmKo2021-ICPE-GroupEncryptionCentralizedBenchmark, author = {Prantl, Thomas and Ten, Peter and Iffländer, Lukas and Herrnleben, Stefan and Dmitrenko, Alexandra and Kounev, Samuel and Krupitzer, Christian}, booktitle = {2021 ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {Group\_Encyrption\_Scheme}, month = {04}, series = {ICPE'21}, title = {Towards a Group Encryption Scheme Benchmark: A View on Centralized Schemes with focus on IoT}, year = 2021 }
• QoE Models in the Wild: Comparing Video QoE Models Using a Crowdsourced Data Set. Seufert, Anika; Wamser, Florian; Yarish, David; Macdonald, Hunter; Hoßfeld, Tobias. In 2021 13th International Conference on Quality of Multimedia Experience (QoMEX). Montreal, Canada (virtual conference), 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Crowdsourced measurements solve the problem of being able to assess the performance of a communication network from an end-user perspective, but the new characteristics of the data pose new challenges for QoE modeling. In contrast to existing laboratory or network measurements, this type of measurement at the end-user device primarily involves taking a large number of short sample measurements, which, however, are rich in measured parameters, including many user-, application-, and device-related parameters. To test the applicability and to facilitate the integration of such data, we applied four QoE models from the literature to 290k worldwide video streaming measurements from a commercial data set from August to October 2020. In this work, we will therefore first describe the crowdsourcing video streaming data set to provide insights into the properties of video streaming KPIs in the real-world. Second, we run four popular QoE models using this data set, compare the resulting QoE scores, and derive the impact of individual KPIs for each model. We show that the models assess the QoE at least differently, but sometimes with contradicting statements. Reading this paper, it becomes evident that more work and subjective studies, based on real-world data like the one we have shown, are needed to extend the current QoE models.

  @inproceedings{info3-inproceedings-2021-12, abstract = {Crowdsourced measurements solve the problem of being able to assess the performance of a communication network from an end-user perspective, but the new characteristics of the data pose new challenges for QoE modeling. In contrast to existing laboratory or network measurements, this type of measurement at the end-user device primarily involves taking a large number of short sample measurements, which, however, are rich in measured parameters, including many user-, application-, and device-related parameters. To test the applicability and to facilitate the integration of such data, we applied four QoE models from the literature to 290k worldwide video streaming measurements from a commercial data set from August to October 2020. In this work, we will therefore first describe the crowdsourcing video streaming data set to provide insights into the properties of video streaming KPIs in the real-world. Second, we run four popular QoE models using this data set, compare the resulting QoE scores, and derive the impact of individual KPIs for each model. We show that the models assess the QoE at least differently, but sometimes with contradicting statements. Reading this paper, it becomes evident that more work and subjective studies, based on real-world data like the one we have shown, are needed to extend the current QoE models.}, address = {Montreal, Canada (virtual conference)}, author = {Seufert, Anika and Wamser, Florian and Yarish, David and Macdonald, Hunter and Hoßfeld, Tobias}, booktitle = {2021 13th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {can}, month = {06}, title = {QoE Models in the Wild: Comparing Video QoE Models Using a Crowdsourced Data Set}, year = 2021 }
• Utility-based Vehicle Routing Integrating User Preferences. Lesch, Veronika; Hadry, Marius; Kounev, Samuel; Krupitzer, Christian. In Proceedings of 3rd International Workshop on Pervasive Computing for Vehicular Systems (PerVehicle), 2021. IEEE, 2021.
  • [ BibTeX ]
  @inproceedings{lesch2021utility, author = {Lesch, Veronika and Hadry, Marius and Kounev, Samuel and Krupitzer, Christian}, booktitle = {Proceedings of 3rd International Workshop on Pervasive Computing for Vehicular Systems (PerVehicle), 2021}, keywords = {t_workshop}, month = {03}, publisher = {IEEE}, title = {Utility-based Vehicle Routing Integrating User Preferences}, year = 2021 }
• A Self-Learning Meta-Optimization Framework for Adaptation Planning. Technical Report (Master thesis), . Hadry, Marius. Master thesis. University of W{ü}rzburg, Am Hubland, Informatikgeb{ä}ude, 97074 W{ü}rzburg, Germany, 2021, May.
  • [ BibTeX ]
  @mastersthesis{hadry2021selflearning, address = {Am Hubland, Informatikgeb{\"a}ude, 97074 W{\"u}rzburg, Germany}, author = {Hadry, Marius}, keywords = {Thesis_supervised_by_Veronika_Lesch}, month = {05}, school = {University of W{\"u}rzburg}, title = {A Self-Learning Meta-Optimization Framework for Adaptation Planning}, year = 2021 }
• ML-Assisted Latency Assignments in Time-Sensitive Networking. Grigorjew, Alexej; Seufert, Michael; Wehner, Nikolas; Hofmann, Jan; Hoßfeld, Tobias. In IFIP/IEEE International Symposium on Integrated Network Management (IM 2021). Bordeaux, France (Virtual Conference), 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Recent developments in industrial automation and invehicle communication have raised the requirements of real-time networking. Bus systems that were traditionally deployed in these fields cannot provide sufficient bandwidth and are now shifting towards Ethernet for their real-time communication needs. In this field, standardization efforts from the IEEE and the IETF have developed new data plane mechanisms such as shapers and schedulers, as well as control plane mechanisms such as reservation protocols to support their new requirements. However, their implementation and their optimal configuration remain an important factor for their efficiency. This work presents a machine learning framework that takes on the configuration task. Four different models are trained for the configuration of per-hop latency guarantees in a distributed resource reservation process and compared with respect to their real-time traffic capacity. The evaluation shows that all models provide good configurations for the provided scenarios, but more importantly, they represent a first step for a semi-automated configuration of parameters in Time-Sensitive Networking.

  @inproceedings{info3-inproceedings-2021-2, abstract = {Recent developments in industrial automation and invehicle communication have raised the requirements of real-time networking. Bus systems that were traditionally deployed in these fields cannot provide sufficient bandwidth and are now shifting towards Ethernet for their real-time communication needs. In this field, standardization efforts from the IEEE and the IETF have developed new data plane mechanisms such as shapers and schedulers, as well as control plane mechanisms such as reservation protocols to support their new requirements. However, their implementation and their optimal configuration remain an important factor for their efficiency. This work presents a machine learning framework that takes on the configuration task. Four different models are trained for the configuration of per-hop latency guarantees in a distributed resource reservation process and compared with respect to their real-time traffic capacity. The evaluation shows that all models provide good configurations for the provided scenarios, but more importantly, they represent a first step for a semi-automated configuration of parameters in Time-Sensitive Networking.}, address = {Bordeaux, France (Virtual Conference)}, author = {Grigorjew, Alexej and Seufert, Michael and Wehner, Nikolas and Hofmann, Jan and Hoßfeld, Tobias}, booktitle = {IFIP/IEEE International Symposium on Integrated Network Management (IM 2021)}, keywords = {kikdin}, month = {05}, title = {ML-Assisted Latency Assignments in Time-Sensitive Networking}, year = 2021 }
• Signaling Traffic in Internet-of-Things Mobile Networks. Geissler, Stefan; Wamser, Florian; Bauer, Wolfang; Krolikowski, Michael; Gebert, Steffen; Hoßfeld, Tobias. In IFIP/IEEE International Symposium on Integrated Network Management (IM 2021). Bordeaux, France (Virtual Conference), 2021.
  • [ Abstract ]
  • [ BibTeX ]
  The Internet of Things (IoT) is expected to play an increasingly important role in next-generation mobile networks. Detailed knowledge of this type of traffic and the associated signaling in those networks is of interest to operators and standardization in order to run these networks successfully. The aim of this study is to characterize IoT signaling traffic for mobile communication networks (i) from a network operator’s point of view, (ii) at device level, and (iii) for the establishment of data connections. General statistics on signaling and device behavior, such as the observed IoT traffic volume and message composition, are given before device classes with statistically different signaling behavior are identified. Finally, by characterizing the aggre- gated signaling traffic, we show that the Markov assumption, widespread in standardization and literature, regarding the aggregated arrival process for data connections does not apply in reality.

  @inproceedings{info3-inproceedings-2021-1, abstract = {The Internet of Things (IoT) is expected to play an increasingly important role in next-generation mobile networks. Detailed knowledge of this type of traffic and the associated signaling in those networks is of interest to operators and standardization in order to run these networks successfully. The aim of this study is to characterize IoT signaling traffic for mobile communication networks (i) from a network operator’s point of view, (ii) at device level, and (iii) for the establishment of data connections. General statistics on signaling and device behavior, such as the observed IoT traffic volume and message composition, are given before device classes with statistically different signaling behavior are identified. Finally, by characterizing the aggre- gated signaling traffic, we show that the Markov assumption, widespread in standardization and literature, regarding the aggregated arrival process for data connections does not apply in reality.}, address = {Bordeaux, France (Virtual Conference)}, author = {Geissler, Stefan and Wamser, Florian and Bauer, Wolfang and Krolikowski, Michael and Gebert, Steffen and Hoßfeld, Tobias}, booktitle = {IFIP/IEEE International Symposium on Integrated Network Management (IM 2021)}, keywords = {can}, month = {05}, title = {Signaling Traffic in Internet-of-Things Mobile Networks}, year = 2021 }
• Quality that Matters: QoE Monitoring in Education Service Provider (ESP) Networks. Wehner, Nikolas; Seufert, Michael; Wieser, Viktoria; Casas, Pedro; Capdehourat, Germán. In IFIP/IEEE International Symposium on Integrated Network Management (IM 2021). Bordeaux, France (Virtual Conference), 2021.
  • [ Abstract ]
  • [ BibTeX ]
  Education Service Providers (ESPs) play a crucial role in the digitization of education as they equip students and teachers with reliable devices and provide high quality Internet access at schools. This paper investigates four months worth of continuous measurements conducted by an ESP using a largescale, passive, in-device Quality of Experience (QoE) monitoring system deployed into a nationwide network of education-purpose devices. These measurements cover more than 800 education centers and about 4000 devices, used both in schools and at home. Using this rich dataset, we present an exhaustive characterization of the browsing behavior, and a quantification of the web and video QoE in this educational context. Web QoE results showed a better performance for school Wi-Fi networks compared to home connections, suggesting that several issues may arise for ESPs due to the increasing relevance of home-schooling caused by the COVID-19 pandemic.

  @inproceedings{info3-inproceedings-2021-3, abstract = {Education Service Providers (ESPs) play a crucial role in the digitization of education as they equip students and teachers with reliable devices and provide high quality Internet access at schools. This paper investigates four months worth of continuous measurements conducted by an ESP using a largescale, passive, in-device Quality of Experience (QoE) monitoring system deployed into a nationwide network of education-purpose devices. These measurements cover more than 800 education centers and about 4000 devices, used both in schools and at home. Using this rich dataset, we present an exhaustive characterization of the browsing behavior, and a quantification of the web and video QoE in this educational context. Web QoE results showed a better performance for school Wi-Fi networks compared to home connections, suggesting that several issues may arise for ESPs due to the increasing relevance of home-schooling caused by the COVID-19 pandemic.}, address = {Bordeaux, France (Virtual Conference)}, author = {Wehner, Nikolas and Seufert, Michael and Wieser, Viktoria and Casas, Pedro and Capdehourat, Germán}, booktitle = {IFIP/IEEE International Symposium on Integrated Network Management (IM 2021)}, keywords = {ucn}, month = {05}, title = {Quality that Matters: QoE Monitoring in Education Service Provider (ESP) Networks}, year = 2021 }
• Assessing Media Bias in Cross-Linguistic and Cross-National Populations. Sales, Allan; Zehe, Albin; Marinho, Leandro Balby; Veloso, Adriano; Hotho, Andreas; Omeliyanenko, Janna. In Proceedings of the International AAAI Conference on Web and Social Media, 15(1), pp. 561–572. 2021.
  • [ BibTeX ]
  • [ URL ]
  @article{sales2021assessing, author = {Sales, Allan and Zehe, Albin and Marinho, Leandro Balby and Veloso, Adriano and Hotho, Andreas and Omeliyanenko, Janna}, journal = {Proceedings of the International AAAI Conference on Web and Social Media}, keywords = {media}, month = {05}, number = 1, pages = {561-572}, title = {Assessing Media Bias in Cross-Linguistic and Cross-National Populations}, volume = 15, year = 2021 }
• Performance Impact Analysis of Securing MQTT Using TLS. Prantl, Thomas; Iffländer, Lukas; Herrnleben, Stefan; Engel, Simon; Kounev, Samuel; Krupitzer, Christian. In 2021 ACM/SPEC International Conference on Performance Engineering (ICPE), of ICPE’21. 2021.
  • [ BibTeX ]
  @inproceedings{PrTeIfHeDmKo2021-ICPE-MQTT_TLS, author = {Prantl, Thomas and Iffländer, Lukas and Herrnleben, Stefan and Engel, Simon and Kounev, Samuel and Krupitzer, Christian}, booktitle = {2021 ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {IoT}, month = {04}, series = {ICPE'21}, title = {Performance Impact Analysis of Securing MQTT Using TLS}, year = 2021 }
• Libra: A Benchmark for Time Series Forecasting Methods. Bauer, Andr{é}; Z{ü}fle, Marwin; Eismann, Simon; Grohmann, Johannes; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE). ACM, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In many areas of decision making, forecasting is an essential pillar. Consequently, there are many different forecasting methods. According to the "No-Free-Lunch Theorem", there is no single forecasting method that performs best for all time series. In other words, each method has its advantages and disadvantages depending on the specific use case. Therefore, the choice of the forecasting method remains a mandatory expert task. However, expert knowledge cannot be fully automated. To establish a level playing field for evaluating the performance of time series forecasting methods in a broad setting, we propose Libra, a forecasting benchmark that automatically evaluates and ranks forecasting methods based on their performance in a diverse set of evaluation scenarios. The benchmark comprises four different use cases, each covering 100 heterogeneous time series taken from different domains. The data set was assembled from publicly available time series and was designed to exhibit much higher diversity than existing forecasting competitions. Based on this benchmark, we perform a comprehensive evaluation to compare different existing time series forecasting methods.

  @inproceedings{bauer2021benchmark, abstract = {In many areas of decision making, forecasting is an essential pillar. Consequently, there are many different forecasting methods. According to the "No-Free-Lunch Theorem", there is no single forecasting method that performs best for all time series. In other words, each method has its advantages and disadvantages depending on the specific use case. Therefore, the choice of the forecasting method remains a mandatory expert task. However, expert knowledge cannot be fully automated. To establish a level playing field for evaluating the performance of time series forecasting methods in a broad setting, we propose Libra, a forecasting benchmark that automatically evaluates and ranks forecasting methods based on their performance in a diverse set of evaluation scenarios. The benchmark comprises four different use cases, each covering 100 heterogeneous time series taken from different domains. The data set was assembled from publicly available time series and was designed to exhibit much higher diversity than existing forecasting competitions. Based on this benchmark, we perform a comprehensive evaluation to compare different existing time series forecasting methods.}, address = {New York, NY, USA}, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Eismann, Simon and Grohmann, Johannes and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {benchmark}, month = {04}, organization = {ACM}, title = {Libra: A Benchmark for Time Series Forecasting Methods}, year = 2021 }
• {SPEC} - Spotlight on the International Standards Group ({ISG}). Schmitt, Norbert; Lange, Klaus-Dieter; Sharma, Sanjay; Cragin, Aaron; Reiner, David; Kounev, Samuel. In Companion of the {ACM}/{SPEC} International Conference on Performance Engineering. {ACM}, 2021.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Schmitt_2021, author = {Schmitt, Norbert and Lange, Klaus-Dieter and Sharma, Sanjay and Cragin, Aaron and Reiner, David and Kounev, Samuel}, booktitle = {Companion of the {ACM}/{SPEC} International Conference on Performance Engineering}, keywords = {descartes}, month = {04}, publisher = {{ACM}}, title = {{SPEC} - Spotlight on the International Standards Group ({ISG})}, year = 2021 }
• Classroom management competency enhancement for student teachers using a fully immersive virtual classroom. Seufert, Christian; Oberd{ö}rfer, Sebastian; Roth, Alice; Grafe, Silke; Lugrin, Jean-Luc; Latoschik, Marc Erich. In Computers & Education, p. 104410. 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The purpose of this study is to examine whether pre-service teachers studying classroom management (CM) in a virtual reality (VR)-supported setting enhance their CM competencies more than students do in a setting using conventional methods. With this aim in mind and to address a lack of available situations of practicing and reflecting CM competencies besides simply gaining theoretical knowledge about CM in education, we integrated a novel fully immersive VR application in selected CM courses. We evaluated the development of self-assessed and instructor-rated CM competencies and the learning quality in the different learning conditions. Additionally, we evaluated the presence, social presence, believability and utility of the VR application and the VR-assisted and video-assisted course. Participants were pre-service teachers (n = 55) of the university of XXX who participated in a quasi-experimental pre-test/post-test intervention. The students were randomly assigned to one of two intervention groups: the test group used ProjectName during the term (n = 39), and the comparison group's learning was video-assisted (n = 16). The instructor rating shows significant differences between the VR group and the video group, the two points of measurement and for the interaction between the condition and time of measurement. It demonstrates a highly significant improvement in CM competencies in the VR setting between the pre-test and post-test (p < 0.001, Cohen's d = 1.06) as compared to the video-based setting. The participants of the VR setting themselves rated their CM competencies in the post-test significantly higher than in the pre-test (p = 0.02, Cohen's d = 0.39). Interestingly, the video group also rated themselves better in the post-test (p = 0.02, Cohen's d = 0.67), which reveals that self-assessment and external assessment show different results. In addition, we observed that even if both groups gained similar theoretical knowledge, the CM competencies developed to a greater degree in the VR-based settings. The participants rated the CM training system a useful tool to evaluate and reflect on individual teacher actions. Its immersion contributes to a high presence and the simulation of realistic scenarios in a CM course. These findings suggest that VR-based settings can lead to a higher benefit in the enhancement of pre-service teachers' CM competencies.

  @article{SEUFERT2021104410, abstract = {The purpose of this study is to examine whether pre-service teachers studying classroom management (CM) in a virtual reality (VR)-supported setting enhance their CM competencies more than students do in a setting using conventional methods. With this aim in mind and to address a lack of available situations of practicing and reflecting CM competencies besides simply gaining theoretical knowledge about CM in education, we integrated a novel fully immersive VR application in selected CM courses. We evaluated the development of self-assessed and instructor-rated CM competencies and the learning quality in the different learning conditions. Additionally, we evaluated the presence, social presence, believability and utility of the VR application and the VR-assisted and video-assisted course. Participants were pre-service teachers (n = 55) of the university of XXX who participated in a quasi-experimental pre-test/post-test intervention. The students were randomly assigned to one of two intervention groups: the test group used ProjectName during the term (n = 39), and the comparison group's learning was video-assisted (n = 16). The instructor rating shows significant differences between the VR group and the video group, the two points of measurement and for the interaction between the condition and time of measurement. It demonstrates a highly significant improvement in CM competencies in the VR setting between the pre-test and post-test (p < 0.001, Cohen's d = 1.06) as compared to the video-based setting. The participants of the VR setting themselves rated their CM competencies in the post-test significantly higher than in the pre-test (p = 0.02, Cohen's d = 0.39). Interestingly, the video group also rated themselves better in the post-test (p = 0.02, Cohen's d = 0.67), which reveals that self-assessment and external assessment show different results. In addition, we observed that even if both groups gained similar theoretical knowledge, the CM competencies developed to a greater degree in the VR-based settings. The participants rated the CM training system a useful tool to evaluate and reflect on individual teacher actions. Its immersion contributes to a high presence and the simulation of realistic scenarios in a CM course. These findings suggest that VR-based settings can lead to a higher benefit in the enhancement of pre-service teachers' CM competencies.}, author = {Seufert, Christian and Oberd{\"o}rfer, Sebastian and Roth, Alice and Grafe, Silke and Lugrin, Jean-Luc and Latoschik, Marc Erich}, journal = {Computers & Education}, keywords = {education}, pages = 104410, title = {Classroom management competency enhancement for student teachers using a fully immersive virtual classroom}, year = 2021 }
• Cumulative Quality Modeling for HTTP Adaptive Streaming. Tran, Huyen TT; Pham Ngoc, Nam; Hoßfeld, Tobias; Seufert, Michael; Thang, Truong Cong. In ACM Transactions on Multimedia Computing, Communications, and Applications, 17(1), pp. 22 (1–24). 2021.
  • [ BibTeX ]
  @article{info3-article-2021-1, author = {Tran, Huyen TT and Pham Ngoc, Nam and Hoßfeld, Tobias and Seufert, Michael and Thang, Truong Cong}, journal = {ACM Transactions on Multimedia Computing, Communications, and Applications}, keywords = {ucn}, month = {04}, number = 1, pages = {22 (1-24)}, title = {Cumulative Quality Modeling for HTTP Adaptive Streaming}, volume = 17, year = 2021 }
• Towards a Group Encryption Scheme Benchmark: A View on Centralized Schemes with focus on IoT. Prantl, Thomas; Ten, Peter; Iffländer, Lukas; Herrnleben, Stefan; Dmitrenko, Alexandra; Kounev, Samuel; Krupitzer, Christian. In 2021 ACM/SPEC International Conference on Performance Engineering (ICPE), of ICPE’21. 2021.
  • [ BibTeX ]
  @inproceedings{PrTeIfHeDmKo2021-ICPE-GroupEncryptionCentralizedBenchmark, author = {Prantl, Thomas and Ten, Peter and Iffländer, Lukas and Herrnleben, Stefan and Dmitrenko, Alexandra and Kounev, Samuel and Krupitzer, Christian}, booktitle = {2021 ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {Group\_Encyrption\_Scheme}, month = {04}, series = {ICPE'21}, title = {Towards a Group Encryption Scheme Benchmark: A View on Centralized Schemes with focus on IoT}, year = 2021 }
• {SPEC Research Group Newsletter, vol. 3 no. 2}. Kounev, Samuel; van Hoorn, Andre; Bauer, Andr{é}. 2021, April.
  • [ BibTeX ]
  • [ URL ]
  @misc{SPEC-RG-NEWSLETTER-10, author = {Kounev, Samuel and van Hoorn, Andre and Bauer, Andr{\'e}}, keywords = {SPEC}, month = {04}, note = {Published by Standard Performance Evaluation Corporation (SPEC)}, title = {{SPEC Research Group Newsletter, vol. 3 no. 2}}, year = 2021 }
• Towards a Group Encryption Scheme Benchmark: A View on Centralized Schemes with focus on IoT. Prantl, Thomas; Ten, Peter; Iffländer, Lukas; Herrnleben, Stefan; Dmitrenko, Alexandra; Kounev, Samuel; Krupitzer, Christian. In 2021 ACM/SPEC International Conference on Performance Engineering (ICPE), of ICPE’21. 2021.
  • [ BibTeX ]
  @inproceedings{PrTeIfHeDmKo2021-ICPE-GroupEncryptionCentralizedBenchmark, author = {Prantl, Thomas and Ten, Peter and Iffländer, Lukas and Herrnleben, Stefan and Dmitrenko, Alexandra and Kounev, Samuel and Krupitzer, Christian}, booktitle = {2021 ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {Group\_Encyrption\_Scheme}, month = {04}, series = {ICPE'21}, title = {Towards a Group Encryption Scheme Benchmark: A View on Centralized Schemes with focus on IoT}, year = 2021 }
• SuanMing: Explainable Prediction of Performance Degradations in Microservice Applications. Grohmann, Johannes; Straesser, Martin; Chalbani, Avi; Eismann, Simon; Arian, Yair; Herbst, Nikolas; Peretz, Noam; Kounev, Samuel. In Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE). ACM, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Application performance management (APM) tools are useful to observe the performance properties of an application during production. However, APM is normally purely reactive, that is, it can only report about current or past performance degradation. Although some approaches capable of predictive application monitoring have been proposed, they can only report a predicted degradation but cannot explain its root-cause, making it hard to prevent the expected degradation. In this paper, we present SuanMing---a framework for predicting performance degradation of microservice applications running in cloud environments. SuanMing is able to predict future root causes for anticipated performance degradations and therefore aims at preventing performance degradations before they actually occur. We evaluate SuanMing on two realistic microservice applications, TeaStore and TrainTicket, and we show that our approach is able to predict and pinpoint performance degradations with an accuracy of over 90\%.

  @inproceedings{GrStChEiArHePeKo2021-ICPE, abstract = {Application performance management (APM) tools are useful to observe the performance properties of an application during production. However, APM is normally purely reactive, that is, it can only report about current or past performance degradation. Although some approaches capable of predictive application monitoring have been proposed, they can only report a predicted degradation but cannot explain its root-cause, making it hard to prevent the expected degradation. In this paper, we present SuanMing—a framework for predicting performance degradation of microservice applications running in cloud environments. SuanMing is able to predict future root causes for anticipated performance degradations and therefore aims at preventing performance degradations before they actually occur. We evaluate SuanMing on two realistic microservice applications, TeaStore and TrainTicket, and we show that our approach is able to predict and pinpoint performance degradations with an accuracy of over 90\%.}, address = {New York, NY, USA}, author = {Grohmann, Johannes and Straesser, Martin and Chalbani, Avi and Eismann, Simon and Arian, Yair and Herbst, Nikolas and Peretz, Noam and Kounev, Samuel}, booktitle = {Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {performance}, month = {04}, note = {Acceptance Rate: 29%}, organization = {ACM}, title = {SuanMing: Explainable Prediction of Performance Degradations in Microservice Applications}, year = 2021 }
• SuanMing: Explainable Prediction of Performance Degradations in Microservice Applications. Grohmann, Johannes; Straesser, Martin; Chalbani, Avi; Eismann, Simon; Arian, Yair; Herbst, Nikolas; Peretz, Noam; Kounev, Samuel. In Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE). ACM, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Application performance management (APM) tools are useful to observe the performance properties of an application during production. However, APM is normally purely reactive, that is, it can only report about current or past performance degradation. Although some approaches capable of predictive application monitoring have been proposed, they can only report a predicted degradation but cannot explain its root-cause, making it hard to prevent the expected degradation. In this paper, we present SuanMing---a framework for predicting performance degradation of microservice applications running in cloud environments. SuanMing is able to predict future root causes for anticipated performance degradations and therefore aims at preventing performance degradations before they actually occur. We evaluate SuanMing on two realistic microservice applications, TeaStore and TrainTicket, and we show that our approach is able to predict and pinpoint performance degradations with an accuracy of over 90\%.

  @inproceedings{GrStChEiArHePeKo2021-ICPE, abstract = {Application performance management (APM) tools are useful to observe the performance properties of an application during production. However, APM is normally purely reactive, that is, it can only report about current or past performance degradation. Although some approaches capable of predictive application monitoring have been proposed, they can only report a predicted degradation but cannot explain its root-cause, making it hard to prevent the expected degradation. In this paper, we present SuanMing—a framework for predicting performance degradation of microservice applications running in cloud environments. SuanMing is able to predict future root causes for anticipated performance degradations and therefore aims at preventing performance degradations before they actually occur. We evaluate SuanMing on two realistic microservice applications, TeaStore and TrainTicket, and we show that our approach is able to predict and pinpoint performance degradations with an accuracy of over 90\%.}, address = {New York, NY, USA}, author = {Grohmann, Johannes and Straesser, Martin and Chalbani, Avi and Eismann, Simon and Arian, Yair and Herbst, Nikolas and Peretz, Noam and Kounev, Samuel}, booktitle = {Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {performance}, month = {04}, note = {Acceptance Rate: 29%}, organization = {ACM}, title = {SuanMing: Explainable Prediction of Performance Degradations in Microservice Applications}, year = 2021 }
• Libra: A Benchmark for Time Series Forecasting Methods. Bauer, Andr{é}; Z{ü}fle, Marwin; Eismann, Simon; Grohmann, Johannes; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE). ACM, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In many areas of decision making, forecasting is an essential pillar. Consequently, there are many different forecasting methods. According to the "No-Free-Lunch Theorem", there is no single forecasting method that performs best for all time series. In other words, each method has its advantages and disadvantages depending on the specific use case. Therefore, the choice of the forecasting method remains a mandatory expert task. However, expert knowledge cannot be fully automated. To establish a level playing field for evaluating the performance of time series forecasting methods in a broad setting, we propose Libra, a forecasting benchmark that automatically evaluates and ranks forecasting methods based on their performance in a diverse set of evaluation scenarios. The benchmark comprises four different use cases, each covering 100 heterogeneous time series taken from different domains. The data set was assembled from publicly available time series and was designed to exhibit much higher diversity than existing forecasting competitions. Based on this benchmark, we perform a comprehensive evaluation to compare different existing time series forecasting methods.

  @inproceedings{bauer2021benchmark, abstract = {In many areas of decision making, forecasting is an essential pillar. Consequently, there are many different forecasting methods. According to the "No-Free-Lunch Theorem", there is no single forecasting method that performs best for all time series. In other words, each method has its advantages and disadvantages depending on the specific use case. Therefore, the choice of the forecasting method remains a mandatory expert task. However, expert knowledge cannot be fully automated. To establish a level playing field for evaluating the performance of time series forecasting methods in a broad setting, we propose Libra, a forecasting benchmark that automatically evaluates and ranks forecasting methods based on their performance in a diverse set of evaluation scenarios. The benchmark comprises four different use cases, each covering 100 heterogeneous time series taken from different domains. The data set was assembled from publicly available time series and was designed to exhibit much higher diversity than existing forecasting competitions. Based on this benchmark, we perform a comprehensive evaluation to compare different existing time series forecasting methods.}, address = {New York, NY, USA}, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Eismann, Simon and Grohmann, Johannes and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {benchmark}, month = {04}, organization = {ACM}, title = {Libra: A Benchmark for Time Series Forecasting Methods}, year = 2021 }
• Performance Impact Analysis of Securing MQTT Using TLS. Prantl, Thomas; Iffländer, Lukas; Herrnleben, Stefan; Engel, Simon; Kounev, Samuel; Krupitzer, Christian. In 2021 ACM/SPEC International Conference on Performance Engineering (ICPE), of ICPE’21. 2021.
  • [ BibTeX ]
  @inproceedings{PrTeIfHeDmKo2021-ICPE-MQTT_TLS, author = {Prantl, Thomas and Iffländer, Lukas and Herrnleben, Stefan and Engel, Simon and Kounev, Samuel and Krupitzer, Christian}, booktitle = {2021 ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {IoT}, month = {04}, series = {ICPE'21}, title = {Performance Impact Analysis of Securing MQTT Using TLS}, year = 2021 }
• Performance Impact Analysis of Securing MQTT Using TLS. Prantl, Thomas; Iffländer, Lukas; Herrnleben, Stefan; Engel, Simon; Kounev, Samuel; Krupitzer, Christian. In 2021 ACM/SPEC International Conference on Performance Engineering (ICPE), of ICPE’21. 2021.
  • [ BibTeX ]
  @inproceedings{PrTeIfHeDmKo2021-ICPE-MQTT_TLS, author = {Prantl, Thomas and Iffländer, Lukas and Herrnleben, Stefan and Engel, Simon and Kounev, Samuel and Krupitzer, Christian}, booktitle = {2021 ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {IoT}, month = {04}, series = {ICPE'21}, title = {Performance Impact Analysis of Securing MQTT Using TLS}, year = 2021 }
• SuanMing: Explainable Prediction of Performance Degradations in Microservice Applications. Grohmann, Johannes; Straesser, Martin; Chalbani, Avi; Eismann, Simon; Arian, Yair; Herbst, Nikolas; Peretz, Noam; Kounev, Samuel. In Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE). ACM, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Application performance management (APM) tools are useful to observe the performance properties of an application during production. However, APM is normally purely reactive, that is, it can only report about current or past performance degradation. Although some approaches capable of predictive application monitoring have been proposed, they can only report a predicted degradation but cannot explain its root-cause, making it hard to prevent the expected degradation. In this paper, we present SuanMing---a framework for predicting performance degradation of microservice applications running in cloud environments. SuanMing is able to predict future root causes for anticipated performance degradations and therefore aims at preventing performance degradations before they actually occur. We evaluate SuanMing on two realistic microservice applications, TeaStore and TrainTicket, and we show that our approach is able to predict and pinpoint performance degradations with an accuracy of over 90\%.

  @inproceedings{GrStChEiArHePeKo2021-ICPE, abstract = {Application performance management (APM) tools are useful to observe the performance properties of an application during production. However, APM is normally purely reactive, that is, it can only report about current or past performance degradation. Although some approaches capable of predictive application monitoring have been proposed, they can only report a predicted degradation but cannot explain its root-cause, making it hard to prevent the expected degradation. In this paper, we present SuanMing—a framework for predicting performance degradation of microservice applications running in cloud environments. SuanMing is able to predict future root causes for anticipated performance degradations and therefore aims at preventing performance degradations before they actually occur. We evaluate SuanMing on two realistic microservice applications, TeaStore and TrainTicket, and we show that our approach is able to predict and pinpoint performance degradations with an accuracy of over 90\%.}, address = {New York, NY, USA}, author = {Grohmann, Johannes and Straesser, Martin and Chalbani, Avi and Eismann, Simon and Arian, Yair and Herbst, Nikolas and Peretz, Noam and Kounev, Samuel}, booktitle = {Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {performance}, month = {04}, note = {Acceptance Rate: 29%}, organization = {ACM}, title = {SuanMing: Explainable Prediction of Performance Degradations in Microservice Applications}, year = 2021 }
• SuanMing: Explainable Prediction of Performance Degradations in Microservice Applications. Grohmann, Johannes; Straesser, Martin; Chalbani, Avi; Eismann, Simon; Arian, Yair; Herbst, Nikolas; Peretz, Noam; Kounev, Samuel. In Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE). ACM, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Application performance management (APM) tools are useful to observe the performance properties of an application during production. However, APM is normally purely reactive, that is, it can only report about current or past performance degradation. Although some approaches capable of predictive application monitoring have been proposed, they can only report a predicted degradation but cannot explain its root-cause, making it hard to prevent the expected degradation. In this paper, we present SuanMing---a framework for predicting performance degradation of microservice applications running in cloud environments. SuanMing is able to predict future root causes for anticipated performance degradations and therefore aims at preventing performance degradations before they actually occur. We evaluate SuanMing on two realistic microservice applications, TeaStore and TrainTicket, and we show that our approach is able to predict and pinpoint performance degradations with an accuracy of over 90\%.

  @inproceedings{GrStChEiArHePeKo2021-ICPE, abstract = {Application performance management (APM) tools are useful to observe the performance properties of an application during production. However, APM is normally purely reactive, that is, it can only report about current or past performance degradation. Although some approaches capable of predictive application monitoring have been proposed, they can only report a predicted degradation but cannot explain its root-cause, making it hard to prevent the expected degradation. In this paper, we present SuanMing—a framework for predicting performance degradation of microservice applications running in cloud environments. SuanMing is able to predict future root causes for anticipated performance degradations and therefore aims at preventing performance degradations before they actually occur. We evaluate SuanMing on two realistic microservice applications, TeaStore and TrainTicket, and we show that our approach is able to predict and pinpoint performance degradations with an accuracy of over 90\%.}, address = {New York, NY, USA}, author = {Grohmann, Johannes and Straesser, Martin and Chalbani, Avi and Eismann, Simon and Arian, Yair and Herbst, Nikolas and Peretz, Noam and Kounev, Samuel}, booktitle = {Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {performance}, month = {04}, note = {Acceptance Rate: 29%}, organization = {ACM}, title = {SuanMing: Explainable Prediction of Performance Degradations in Microservice Applications}, year = 2021 }
• Libra: A Benchmark for Time Series Forecasting Methods. Bauer, Andr{é}; Z{ü}fle, Marwin; Eismann, Simon; Grohmann, Johannes; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE). ACM, New York, NY, USA, 2021.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In many areas of decision making, forecasting is an essential pillar. Consequently, there are many different forecasting methods. According to the "No-Free-Lunch Theorem", there is no single forecasting method that performs best for all time series. In other words, each method has its advantages and disadvantages depending on the specific use case. Therefore, the choice of the forecasting method remains a mandatory expert task. However, expert knowledge cannot be fully automated. To establish a level playing field for evaluating the performance of time series forecasting methods in a broad setting, we propose Libra, a forecasting benchmark that automatically evaluates and ranks forecasting methods based on their performance in a diverse set of evaluation scenarios. The benchmark comprises four different use cases, each covering 100 heterogeneous time series taken from different domains. The data set was assembled from publicly available time series and was designed to exhibit much higher diversity than existing forecasting competitions. Based on this benchmark, we perform a comprehensive evaluation to compare different existing time series forecasting methods.

  @inproceedings{bauer2021benchmark, abstract = {In many areas of decision making, forecasting is an essential pillar. Consequently, there are many different forecasting methods. According to the "No-Free-Lunch Theorem", there is no single forecasting method that performs best for all time series. In other words, each method has its advantages and disadvantages depending on the specific use case. Therefore, the choice of the forecasting method remains a mandatory expert task. However, expert knowledge cannot be fully automated. To establish a level playing field for evaluating the performance of time series forecasting methods in a broad setting, we propose Libra, a forecasting benchmark that automatically evaluates and ranks forecasting methods based on their performance in a diverse set of evaluation scenarios. The benchmark comprises four different use cases, each covering 100 heterogeneous time series taken from different domains. The data set was assembled from publicly available time series and was designed to exhibit much higher diversity than existing forecasting competitions. Based on this benchmark, we perform a comprehensive evaluation to compare different existing time series forecasting methods.}, address = {New York, NY, USA}, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Eismann, Simon and Grohmann, Johannes and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 12th ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {benchmark}, month = {04}, organization = {ACM}, title = {Libra: A Benchmark for Time Series Forecasting Methods}, year = 2021 }

• Horror Laboratory and Forest Cabin - A Horror Game Series for Desktop Computer, Virtual Reality, and Smart Substitutional Reality. Steinhaeusser, Sophia C.; Lugrin, Birgit. In Extended Abstracts of the 2020 Annual Symposium on Computer-Human Interaction in Play. ACM, 2020.
  • [ BibTeX ]
  @inproceedings{Steinhaeusser_2020, author = {Steinhaeusser, Sophia C. and Lugrin, Birgit}, booktitle = {Extended Abstracts of the 2020 Annual Symposium on Computer-Human Interaction in Play}, keywords = {steinhaeusser}, publisher = {ACM}, title = {Horror Laboratory and Forest Cabin - A Horror Game Series for Desktop Computer, Virtual Reality, and Smart Substitutional Reality}, year = 2020 }
• An Integrated Design of World-in-Miniature Navigation in Virtual Reality. Truman, Samuel; \textbf{Sebastian {von Mammen}}. In FDG ’20: Proceedings of the 15th International Conference on the Foundations of Digital Games, pp. 1–9. ACM, Bugibba, Malta, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Navigation is considered one of the most fundamental challenges in Virtual Reality (VR) and has been extensively researched [11]. The world-in-miniature (WIM) navigation metaphor allows users to travel in large-scale virtual environments (VEs) regardless of available physical space while maintaining a high-level overview of the VE. It relies on a hand-held, scaled-down duplicate of the entire VE, where the user’s current position is displayed, and an interface provided to introduce his/her next movements [17]. There are several extensions to deal with challenges of this navigation technique, e.g. scaling and scrolling [23]. In this work, a WIM is presented that integrates state-of-the-art research insights and incorporates additional features that became apparent during the integration process. These features are needed to improve user interactions and to provide both look-ahead and post-travel feedback. For instance, a novel occlusion handling feature hides the WIM geometry in a rounded space reaching from the user’s hand to his/her forearm. This allows the user to interact with occluded areas of the WIM such as buildings. Further extensions include different visualizations for occlusion handling, an interactive preview screen, post-travel feedback, automatic WIM customization, a unified diegetic UI design concerning WIM and user representation, and an adaptation of widely established gestures to control scaling and scrolling of the WIM. Overall, the presented WIM design integrates and extends state-of-the-art interaction tasks and visualization concepts to overcome open conceptual gaps and to provide a comprehensive practical solution for traveling in VR.

  @inproceedings{Truman:2020aa, abstract = {Navigation is considered one of the most fundamental challenges in Virtual Reality (VR) and has been extensively researched [11]. The world-in-miniature (WIM) navigation metaphor allows users to travel in large-scale virtual environments (VEs) regardless of available physical space while maintaining a high-level overview of the VE. It relies on a hand-held, scaled-down duplicate of the entire VE, where the user’s current position is displayed, and an interface provided to introduce his/her next movements [17]. There are several extensions to deal with challenges of this navigation technique, e.g. scaling and scrolling [23]. In this work, a WIM is presented that integrates state-of-the-art research insights and incorporates additional features that became apparent during the integration process. These features are needed to improve user interactions and to provide both look-ahead and post-travel feedback. For instance, a novel occlusion handling feature hides the WIM geometry in a rounded space reaching from the user’s hand to his/her forearm. This allows the user to interact with occluded areas of the WIM such as buildings. Further extensions include different visualizations for occlusion handling, an interactive preview screen, post-travel feedback, automatic WIM customization, a unified diegetic UI design concerning WIM and user representation, and an adaptation of widely established gestures to control scaling and scrolling of the WIM. Overall, the presented WIM design integrates and extends state-of-the-art interaction tasks and visualization concepts to overcome open conceptual gaps and to provide a comprehensive practical solution for traveling in VR.}, address = {Bugibba, Malta}, author = {Truman, Samuel and \textbf{Sebastian {von Mammen}}}, booktitle = {FDG '20: Proceedings of the 15th International Conference on the Foundations of Digital Games}, keywords = {myown}, organization = {IEEE}, pages = {1–9}, publisher = {ACM}, title = {An Integrated Design of World-in-Miniature Navigation in Virtual Reality}, year = 2020 }
• Preservice Teachers’ encounter with Social VR – Exploring Virtual Teaching and Learning Processes in Initial Teacher Education. Ripka, Gabriela; Grafe, Silke; Latoschik, Marc Erich. In SITE Interactive Conference, E. Langran (ed.), pp. 549–562. Association for the Advancement of Computing in Education (AACE), 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  With 21st century challenges ahead, higher education teaching and learning need new pedagogical concepts. Technologies like social VR enable student-centered, action-oriented, and situated learning. This paper presents findings of the pedagogical implementation of a distributed social VR prototype, a fully immersive VR learning environment, into an Initial Teacher Education program in Germany. The exploratory study addressed the following research questions: 1) How do preservice teachers perceive teaching and learning activities in fully immersive VR and 2) how should teaching and learning processes using social VR in Teacher Education be designed? It followed a design-based research approach. The pedagogical concept for teaching and learning in social VR was based on principles of action-orientation. A convenience sample of three groups of five students each took part in a 90-minute teaching and learning scenario using a fully immersive VR learning environment. During these seminar units, students engaged in qualitative group interviews and shared their perception of the action-oriented teaching and learning activities in VR. The results showed that preservice teachers had the feeling of being less distracted in social VR. Additionally, during group activities, missing social and behavioral cues made communication procedures more challenging for participants. However, some participants noticed a stronger sense of community while collaborating with others.

  @inproceedings{ripka2020preservice, abstract = {With 21st century challenges ahead, higher education teaching and learning need new pedagogical concepts. Technologies like social VR enable student-centered, action-oriented, and situated learning. This paper presents findings of the pedagogical implementation of a distributed social VR prototype, a fully immersive VR learning environment, into an Initial Teacher Education program in Germany. The exploratory study addressed the following research questions: 1) How do preservice teachers perceive teaching and learning activities in fully immersive VR and 2) how should teaching and learning processes using social VR in Teacher Education be designed? It followed a design-based research approach. The pedagogical concept for teaching and learning in social VR was based on principles of action-orientation. A convenience sample of three groups of five students each took part in a 90-minute teaching and learning scenario using a fully immersive VR learning environment. During these seminar units, students engaged in qualitative group interviews and shared their perception of the action-oriented teaching and learning activities in VR. The results showed that preservice teachers had the feeling of being less distracted in social VR. Additionally, during group activities, missing social and behavioral cues made communication procedures more challenging for participants. However, some participants noticed a stronger sense of community while collaborating with others.}, author = {Ripka, Gabriela and Grafe, Silke and Latoschik, Marc Erich}, booktitle = {SITE Interactive Conference}, editor = {Langran, Elizabeth}, keywords = {myown}, pages = {549–562}, publisher = {Association for the Advancement of Computing in Education (AACE)}, title = {Preservice Teachers' encounter with Social VR – Exploring Virtual Teaching and Learning Processes in Initial Teacher Education}, year = 2020 }
• Realistic Virtual Humans from Smartphone Videos. Wenninger, Stephan; Achenbach, Jascha; Bartl, Andrea; Latoschik, Marc Erich; Botsch, Mario. In VRST, R. J. Teather, C. Joslin, W. Stuerzlinger, P. Figueroa, Y. Hu, A. U. Batmaz, W. Lee, F. Ortega (eds.), pp. 29:1–29:11. ACM, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper introduces an automated 3D-reconstruction method for generating high-quality virtual humans from monocular smartphone cameras. The input of our approach are two video clips, one capturing the whole body and the other providing detailed close-ups of head and face. Optical flow analysis and sharpness estimation select individual frames, from which two dense point clouds for the body and head are computed using multi-view reconstruction. Automatically detected landmarks guide the fitting of a virtual human body template to these point clouds, thereby reconstructing the geometry. A graph-cut stitching approach reconstructs a detailed texture. Our results are compared to existing low-cost monocular approaches as well as to expensive multi-camera scan rigs. We achieve visually convincing reconstructions that are almost on par with complex camera rigs while surpassing similar low-cost approaches. The generated high-quality avatars are ready to be processed, animated, and rendered by standard XR simulation and game engines such as Unreal or Unity

  @inproceedings{conf/vrst/WenningerABLB20, abstract = {This paper introduces an automated 3D-reconstruction method for generating high-quality virtual humans from monocular smartphone cameras. The input of our approach are two video clips, one capturing the whole body and the other providing detailed close-ups of head and face. Optical flow analysis and sharpness estimation select individual frames, from which two dense point clouds for the body and head are computed using multi-view reconstruction. Automatically detected landmarks guide the fitting of a virtual human body template to these point clouds, thereby reconstructing the geometry. A graph-cut stitching approach reconstructs a detailed texture. Our results are compared to existing low-cost monocular approaches as well as to expensive multi-camera scan rigs. We achieve visually convincing reconstructions that are almost on par with complex camera rigs while surpassing similar low-cost approaches. The generated high-quality avatars are ready to be processed, animated, and rendered by standard XR simulation and game engines such as Unreal or Unity}, author = {Wenninger, Stephan and Achenbach, Jascha and Bartl, Andrea and Latoschik, Marc Erich and Botsch, Mario}, booktitle = {VRST}, crossref = {conf/vrst/2020}, editor = {Teather, Robert J. and Joslin, Chris and Stuerzlinger, Wolfgang and Figueroa, Pablo and Hu, Yaoping and Batmaz, Anil Ufuk and Lee, Wonsook and Ortega, Francisco}, keywords = {vitras}, note = {Best paper award 🏆}, pages = {29:1-29:11}, publisher = {ACM}, title = {Realistic Virtual Humans from Smartphone Videos.}, year = 2020 }
• Stick Graphs with and without Length Constraints. Chaplick, Steven; Kindermann, Philipp; Löffler, Andre; Thiele, Florian; Wolff, Alexander; Zaft, Alexander; Zink, Johannes. In Journal of Graph Algorithms \& Applications, 24(4), pp. 657–681. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Stick graphs are intersection graphs of horizontal and vertical line seg- ments that all touch a line of slope −1 and lie above this line. De Luca et al. [GD'18] considered the recognition problem of stick graphs when no order is given (STICK), when the order of either one of the two sets is given (STICK$_A$), and when the order of both sets is given (STICK$_{AB}$). They showed how to solve STICK$_{AB}$ efficiently. \par In this paper, we improve the running time of their algorithm, and we solve STICK$_A$ efficiently. Further, we consider variants of these problems where the lengths of the sticks are given as input. We show that these variants of STICK, STICK$_A$, and STICK$_{AB}$ are all NP-complete. On the positive side, we give an efficient solution for STICK$_{AB}$ with fixed stick lengths if there are no isolated vertices.

  @article{ckltwzz-sglc-JGAA20, abstract = {Stick graphs are intersection graphs of horizontal and vertical line seg- ments that all touch a line of slope −1 and lie above this line. De Luca et al. [GD'18] considered the recognition problem of stick graphs when no order is given (STICK), when the order of either one of the two sets is given (STICK$_A$), and when the order of both sets is given (STICK$_{AB}$). They showed how to solve STICK$_{AB}$ efficiently. \par In this paper, we improve the running time of their algorithm, and we solve STICK$_A$ efficiently. Further, we consider variants of these problems where the lengths of the sticks are given as input. We show that these variants of STICK, STICK$_A$, and STICK$_{AB}$ are all NP-complete. On the positive side, we give an efficient solution for STICK$_{AB}$ with fixed stick lengths if there are no isolated vertices.}, author = {Chaplick, Steven and Kindermann, Philipp and Löffler, Andre and Thiele, Florian and Wolff, Alexander and Zaft, Alexander and Zink, Johannes}, journal = {Journal of Graph Algorithms \& Applications}, keywords = {myown}, number = 4, pages = {657–681}, title = {Stick Graphs with and without Length Constraints}, volume = 24, year = 2020 }
• {Methodological Principles for Reproducible Performance Evaluation in Cloud Computing}. Papadopoulos, Alessandro Vittorio; Versluis, Laurens; Bauer, Andr{{é}}; Herbst, Nikolas; von Kistowski, J{{ó}}akim; Ali{-}Eldin, Ahmed; Abad, Cristina L.; Amaral, Jos{{é}} Nelson; Tuma, Petr; Iosup, Alexandru. In Software Engineering 2020, Fachtagung des GI-Fachbereichs Softwaretechnik, 24.-28. Februar 2020, Innsbruck, Austria, Vol. {P-300} of {LNI}, M. Felderer, W. Hasselbring, R. Rabiser, R. Jung (eds.), pp. 93–94. Gesellschaft f{{ü}}r Informatik e.V., 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{DBLP:conf/se/PapadopoulosVBH20, author = {Papadopoulos, Alessandro Vittorio and Versluis, Laurens and Bauer, Andr{{\'e}} and Herbst, Nikolas and von Kistowski, J{{\'o}}akim and Ali{-}Eldin, Ahmed and Abad, Cristina L. and Amaral, Jos{{\'e}} Nelson and Tuma, Petr and Iosup, Alexandru}, booktitle = {Software Engineering 2020, Fachtagung des GI-Fachbereichs Softwaretechnik, 24.-28. Februar 2020, Innsbruck, Austria}, editor = {Felderer, Michael and Hasselbring, Wilhelm and Rabiser, Rick and Jung, Reiner}, keywords = {se2}, pages = {93–94}, publisher = {Gesellschaft f{{\"u}}r Informatik e.V.}, series = {{LNI}}, title = {{Methodological Principles for Reproducible Performance Evaluation in Cloud Computing}}, volume = {{P-300}}, year = 2020 }
• Layered Drawing of Undirected Graphs with Generalized Port Constraints. Walter, Julian; Zink, Johannes; Baumeister, Joachim; Wolff, Alexander. In 28th International Symposium on Graph Drawing and Network Visualization (GD 2020). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The aim of this research is a practical method to draw cable plans of complex machines. Such plans consist of electronic components and cables connecting specific ports of the components. Since the machines are configured for each client individually, cable plans need to be drawn automatically. The drawings must be well readable so that technicians can use them to debug the machines. In order to model plug sockets, we introduce port groups; within a group, ports can change their position (which we use to improve the aesthetics of the layout), but together the ports of a group must form a contiguous block. We approach the problem of drawing such cable plans by extending the well-known Sugiyama framework such that it incorporates ports and port groups. Since the framework assumes directed graphs, we propose several ways to orient the edges of the given undirected graph. We compare these methods experimentally, both on real-world data and synthetic data that carefully simulates real-world data. We measure the aesthetics of the resulting drawings by counting bends and crossings. Using these metrics, we compare our approach to Kieler [JVLC 2014], a library for drawing graphs in the presence of port constraints.

  @inproceedings{walter2020layered, abstract = {The aim of this research is a practical method to draw cable plans of complex machines. Such plans consist of electronic components and cables connecting specific ports of the components. Since the machines are configured for each client individually, cable plans need to be drawn automatically. The drawings must be well readable so that technicians can use them to debug the machines. In order to model plug sockets, we introduce port groups; within a group, ports can change their position (which we use to improve the aesthetics of the layout), but together the ports of a group must form a contiguous block. We approach the problem of drawing such cable plans by extending the well-known Sugiyama framework such that it incorporates ports and port groups. Since the framework assumes directed graphs, we propose several ways to orient the edges of the given undirected graph. We compare these methods experimentally, both on real-world data and synthetic data that carefully simulates real-world data. We measure the aesthetics of the resulting drawings by counting bends and crossings. Using these metrics, we compare our approach to Kieler [JVLC 2014], a library for drawing graphs in the presence of port constraints.}, author = {Walter, Julian and Zink, Johannes and Baumeister, Joachim and Wolff, Alexander}, booktitle = {28th International Symposium on Graph Drawing and Network Visualization (GD 2020)}, keywords = {myown}, note = {cite arxiv:2008.10583}, title = {Layered Drawing of Undirected Graphs with Generalized Port Constraints}, year = 2020 }
• Time Series Forecasting for Self-Aware Systems. {Bauer}, A.; {Züfle}, M.; {Herbst}, N.; {Zehe}, A.; {Hotho}, A.; {Kounev}, S. In Proceedings of the IEEE, pp. 1–26. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Modern distributed systems and Internet-of-Things applications are governed by fast living and changing requirements. Moreover, they have to struggle with huge amounts of data that they create or have to process. To improve the self-awareness of such systems and enable proactive and autonomous decisions, reliable time series forecasting methods are required. However, selecting a suitable forecasting method for a given scenario is a challenging task. According to the ``No-Free-Lunch Theorem,'' there is no general forecasting method that always performs best. Thus, manual feature engineering remains to be a mandatory expert task to avoid trial and error. Furthermore, determining the expected time-to-result of existing forecasting methods is a challenge. In this article, we extensively assess the state-of-the-art in time series forecasting. We compare existing methods and discuss the issues that have to be addressed to enable their use in a self-aware computing context. To address these issues, we present a step-by-step approach to fully automate the feature engineering and forecasting process. Then, following the principles from benchmarking, we establish a level-playing field for evaluating the accuracy and time-to-result of automated forecasting methods for a broad set of application scenarios. We provide results of a benchmarking competition to guide in selecting and appropriately using existing forecasting methods for a given self-aware computing context. Finally, we present a case study in the area of self-aware data-center resource management to exemplify the benefits of fully automated learning and reasoning processes on time series data.

  @article{bauer2020series, abstract = {Modern distributed systems and Internet-of-Things applications are governed by fast living and changing requirements. Moreover, they have to struggle with huge amounts of data that they create or have to process. To improve the self-awareness of such systems and enable proactive and autonomous decisions, reliable time series forecasting methods are required. However, selecting a suitable forecasting method for a given scenario is a challenging task. According to the ``No-Free-Lunch Theorem,'' there is no general forecasting method that always performs best. Thus, manual feature engineering remains to be a mandatory expert task to avoid trial and error. Furthermore, determining the expected time-to-result of existing forecasting methods is a challenge. In this article, we extensively assess the state-of-the-art in time series forecasting. We compare existing methods and discuss the issues that have to be addressed to enable their use in a self-aware computing context. To address these issues, we present a step-by-step approach to fully automate the feature engineering and forecasting process. Then, following the principles from benchmarking, we establish a level-playing field for evaluating the accuracy and time-to-result of automated forecasting methods for a broad set of application scenarios. We provide results of a benchmarking competition to guide in selecting and appropriately using existing forecasting methods for a given self-aware computing context. Finally, we present a case study in the area of self-aware data-center resource management to exemplify the benefits of fully automated learning and reasoning processes on time series data.}, author = {{Bauer}, A. and {Züfle}, M. and {Herbst}, N. and {Zehe}, A. and {Hotho}, A. and {Kounev}, S.}, journal = {Proceedings of the IEEE}, keywords = {Forecasting}, pages = {1-26}, title = {Time Series Forecasting for Self-Aware Systems}, year = 2020 }
• Evaluation of Post-hoc XAI Approaches Through Synthetic Tabular Data. Tritscher, Julian; Ring, Markus; Schlr, Daniel; Hettinger, Lena; Hotho, Andreas. In Foundations of Intelligent Systems, D. Helic, G. Leitner, M. Stettinger, A. Felfernig, Z. W. Ra{{{\’s}}} (eds.), pp. 422–430. Springer International Publishing, Cham, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Evaluating the explanations given by post-hoc XAI approaches on tabular data is a challenging prospect, since the subjective judgement of explanations of tabular relations is non trivial in contrast to e.g. the judgement of image heatmap explanations. In order to quantify XAI performance on categorical tabular data, where feature relationships can often be described by Boolean functions, we propose an evaluation setting through generation of synthetic datasets. To create gold standard explanations, we present a definition of feature relevance in Boolean functions. In the proposed setting we evaluate eight state-of-the-art XAI approaches and gain novel insights into XAI performance on categorical tabular data. We find that the investigated approaches often fail to faithfully explain even basic relationships within categorical data.

  @inproceedings{tritscher2020evaluation, abstract = {Evaluating the explanations given by post-hoc XAI approaches on tabular data is a challenging prospect, since the subjective judgement of explanations of tabular relations is non trivial in contrast to e.g. the judgement of image heatmap explanations. In order to quantify XAI performance on categorical tabular data, where feature relationships can often be described by Boolean functions, we propose an evaluation setting through generation of synthetic datasets. To create gold standard explanations, we present a definition of feature relevance in Boolean functions. In the proposed setting we evaluate eight state-of-the-art XAI approaches and gain novel insights into XAI performance on categorical tabular data. We find that the investigated approaches often fail to faithfully explain even basic relationships within categorical data.}, address = {Cham}, author = {Tritscher, Julian and Ring, Markus and Schlr, Daniel and Hettinger, Lena and Hotho, Andreas}, booktitle = {Foundations of Intelligent Systems}, editor = {Helic, Denis and Leitner, Gerhard and Stettinger, Martin and Felfernig, Alexander and Ra{\'{s}}, Zbigniew W.}, keywords = {xai}, pages = {422–430}, publisher = {Springer International Publishing}, title = {Evaluation of Post-hoc XAI Approaches Through Synthetic Tabular Data}, year = 2020 }
• {Methodological Principles for Reproducible Performance Evaluation in Cloud Computing}. Papadopoulos, Alessandro Vittorio; Versluis, Laurens; Bauer, Andr{{é}}; Herbst, Nikolas; von Kistowski, J{{ó}}akim; Ali{-}Eldin, Ahmed; Abad, Cristina L.; Amaral, Jos{{é}} Nelson; Tuma, Petr; Iosup, Alexandru. In Software Engineering 2020, Fachtagung des GI-Fachbereichs Softwaretechnik, 24.-28. Februar 2020, Innsbruck, Austria, Vol. {P-300} of {LNI}, M. Felderer, W. Hasselbring, R. Rabiser, R. Jung (eds.), pp. 93–94. Gesellschaft f{{ü}}r Informatik e.V., 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{DBLP:conf/se/PapadopoulosVBH20, author = {Papadopoulos, Alessandro Vittorio and Versluis, Laurens and Bauer, Andr{{\'e}} and Herbst, Nikolas and von Kistowski, J{{\'o}}akim and Ali{-}Eldin, Ahmed and Abad, Cristina L. and Amaral, Jos{{\'e}} Nelson and Tuma, Petr and Iosup, Alexandru}, booktitle = {Software Engineering 2020, Fachtagung des GI-Fachbereichs Softwaretechnik, 24.-28. Februar 2020, Innsbruck, Austria}, editor = {Felderer, Michael and Hasselbring, Wilhelm and Rabiser, Rick and Jung, Reiner}, keywords = {se2}, pages = {93–94}, publisher = {Gesellschaft f{{\"u}}r Informatik e.V.}, series = {{LNI}}, title = {{Methodological Principles for Reproducible Performance Evaluation in Cloud Computing}}, volume = {{P-300}}, year = 2020 }
• Time Series Forecasting for Self-Aware Systems. {Bauer}, A.; {Züfle}, M.; {Herbst}, N.; {Zehe}, A.; {Hotho}, A.; {Kounev}, S. In Proceedings of the IEEE, pp. 1–26. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Modern distributed systems and Internet-of-Things applications are governed by fast living and changing requirements. Moreover, they have to struggle with huge amounts of data that they create or have to process. To improve the self-awareness of such systems and enable proactive and autonomous decisions, reliable time series forecasting methods are required. However, selecting a suitable forecasting method for a given scenario is a challenging task. According to the ``No-Free-Lunch Theorem,'' there is no general forecasting method that always performs best. Thus, manual feature engineering remains to be a mandatory expert task to avoid trial and error. Furthermore, determining the expected time-to-result of existing forecasting methods is a challenge. In this article, we extensively assess the state-of-the-art in time series forecasting. We compare existing methods and discuss the issues that have to be addressed to enable their use in a self-aware computing context. To address these issues, we present a step-by-step approach to fully automate the feature engineering and forecasting process. Then, following the principles from benchmarking, we establish a level-playing field for evaluating the accuracy and time-to-result of automated forecasting methods for a broad set of application scenarios. We provide results of a benchmarking competition to guide in selecting and appropriately using existing forecasting methods for a given self-aware computing context. Finally, we present a case study in the area of self-aware data-center resource management to exemplify the benefits of fully automated learning and reasoning processes on time series data.

  @article{bauer2020series, abstract = {Modern distributed systems and Internet-of-Things applications are governed by fast living and changing requirements. Moreover, they have to struggle with huge amounts of data that they create or have to process. To improve the self-awareness of such systems and enable proactive and autonomous decisions, reliable time series forecasting methods are required. However, selecting a suitable forecasting method for a given scenario is a challenging task. According to the ``No-Free-Lunch Theorem,'' there is no general forecasting method that always performs best. Thus, manual feature engineering remains to be a mandatory expert task to avoid trial and error. Furthermore, determining the expected time-to-result of existing forecasting methods is a challenge. In this article, we extensively assess the state-of-the-art in time series forecasting. We compare existing methods and discuss the issues that have to be addressed to enable their use in a self-aware computing context. To address these issues, we present a step-by-step approach to fully automate the feature engineering and forecasting process. Then, following the principles from benchmarking, we establish a level-playing field for evaluating the accuracy and time-to-result of automated forecasting methods for a broad set of application scenarios. We provide results of a benchmarking competition to guide in selecting and appropriately using existing forecasting methods for a given self-aware computing context. Finally, we present a case study in the area of self-aware data-center resource management to exemplify the benefits of fully automated learning and reasoning processes on time series data.}, author = {{Bauer}, A. and {Züfle}, M. and {Herbst}, N. and {Zehe}, A. and {Hotho}, A. and {Kounev}, S.}, journal = {Proceedings of the IEEE}, keywords = {Forecasting}, pages = {1-26}, title = {Time Series Forecasting for Self-Aware Systems}, year = 2020 }
• NICER — Aesthetic Image Enhancement with Humans in the Loop. Fischer, Michael; Kobs, Konstantin; Hotho, Andreas. In ACHI 2020: The Thirteenth International Conference on Advances in Computer-Human Interactions, pp. 357–362. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Fully- or semi-automatic image enhancement software helps users to increase the visual appeal of photos and does not require in-depth knowledge of manual image editing. However, fully-automatic approaches usually enhance the image in a black-box manner that does not give the user any control over the optimization process, possibly leading to edited images that do not subjectively appeal to the user. Semi-automatic methods mostly allow for controlling which pre-defined editing step is taken, which restricts the users in their creativity and ability to make detailed adjustments, such as brightness or contrast. We argue that incorporating user preferences by guiding an automated enhancement method simplifies image editing and increases the enhancement’s focus on the user. This work thus proposes the Neural Image Correction & Enhancement Routine (NICER), a neural network based approach to no-reference image enhancement in a fully-, semi-automatic or fully manual process that is interactive and user-centered. NICER iteratively adjusts image editing parameters in order to maximize an aesthetic score based on image style and content. Users can modify these parameters at any time and guide the optimization process towards a desired direction. This interactive workflow is a novelty in the field of human-computer interaction for image enhancement tasks. In a user study, we show that NICER can improve image aesthetics without user interaction and that allowing user interaction leads to diverse enhancement outcomes that are strongly preferred over the unedited image. We make our code publicly available to facilitate further research in this direction.

  @inproceedings{fischer2020nicer, abstract = {Fully- or semi-automatic image enhancement software helps users to increase the visual appeal of photos and does not require in-depth knowledge of manual image editing. However, fully-automatic approaches usually enhance the image in a black-box manner that does not give the user any control over the optimization process, possibly leading to edited images that do not subjectively appeal to the user. Semi-automatic methods mostly allow for controlling which pre-defined editing step is taken, which restricts the users in their creativity and ability to make detailed adjustments, such as brightness or contrast. We argue that incorporating user preferences by guiding an automated enhancement method simplifies image editing and increases the enhancement’s focus on the user. This work thus proposes the Neural Image Correction & Enhancement Routine (NICER), a neural network based approach to no-reference image enhancement in a fully-, semi-automatic or fully manual process that is interactive and user-centered. NICER iteratively adjusts image editing parameters in order to maximize an aesthetic score based on image style and content. Users can modify these parameters at any time and guide the optimization process towards a desired direction. This interactive workflow is a novelty in the field of human-computer interaction for image enhancement tasks. In a user study, we show that NICER can improve image aesthetics without user interaction and that allowing user interaction leads to diverse enhancement outcomes that are strongly preferred over the unedited image. We make our code publicly available to facilitate further research in this direction.}, author = {Fischer, Michael and Kobs, Konstantin and Hotho, Andreas}, journal = {ACHI 2020: The Thirteenth International Conference on Advances in Computer-Human Interactions}, keywords = {image-assessment}, pages = {357-362}, title = {NICER — Aesthetic Image Enhancement with Humans in the Loop}, year = 2020 }
• Stimulus modality influences session-to-session transfer of training effects in auditory and tactile streaming-based P300 brain–computer interfaces. Ziebell, P.; Stümpfig, J.; Eidel, M.; Kleih, S. C.; Kübler, A.; Latoschik, M. E.; Halder, S. In Scientific Reports, 10(1), p. 11873-. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Despite recent successes, patients suffering from locked-in syndrome (LIS) still struggle to communicate using vision-independent brain–computer interfaces (BCIs). In this study, we compared auditory and tactile BCIs, regarding training effects and cross-stimulus-modality transfer effects, when switching between stimulus modalities. We utilized a streaming-based P300 BCI, which was developed as a low workload approach to prevent potential BCI-inefficiency. We randomly assigned 20 healthy participants to two groups. The participants received three sessions of training either using an auditory BCI or using a tactile BCI. In an additional fourth session, BCI versions were switched to explore possible cross-stimulus-modality transfer effects. Both BCI versions could be operated successfully in the first session by the majority of the participants, with the tactile BCI being experienced as more intuitive. Significant training effects were found mostly in the auditory BCI group and strong evidence for a cross-stimulus-modality transfer occurred for the auditory training group that switched to the tactile version but not vice versa. All participants were able to control at least one BCI version, suggesting that the investigated paradigms are generally feasible and merit further research into their applicability with LIS end-users. Individual preferences regarding stimulus modality should be considered.

  @article{ziebell2020stimulus, abstract = {Despite recent successes, patients suffering from locked-in syndrome (LIS) still struggle to communicate using vision-independent brain–computer interfaces (BCIs). In this study, we compared auditory and tactile BCIs, regarding training effects and cross-stimulus-modality transfer effects, when switching between stimulus modalities. We utilized a streaming-based P300 BCI, which was developed as a low workload approach to prevent potential BCI-inefficiency. We randomly assigned 20 healthy participants to two groups. The participants received three sessions of training either using an auditory BCI or using a tactile BCI. In an additional fourth session, BCI versions were switched to explore possible cross-stimulus-modality transfer effects. Both BCI versions could be operated successfully in the first session by the majority of the participants, with the tactile BCI being experienced as more intuitive. Significant training effects were found mostly in the auditory BCI group and strong evidence for a cross-stimulus-modality transfer occurred for the auditory training group that switched to the tactile version but not vice versa. All participants were able to control at least one BCI version, suggesting that the investigated paradigms are generally feasible and merit further research into their applicability with LIS end-users. Individual preferences regarding stimulus modality should be considered.}, author = {Ziebell, P. and Stümpfig, J. and Eidel, M. and Kleih, S. C. and Kübler, A. and Latoschik, M. E. and Halder, S.}, journal = {Scientific Reports}, keywords = {marc}, number = 1, pages = {11873–}, title = {Stimulus modality influences session-to-session transfer of training effects in auditory and tactile streaming-based P300 brain–computer interfaces}, volume = 10, year = 2020 }
• Machine Learning and Knowledge Discovery in Databases - European Conference, ECML PKDD 2019, Würzburg, Germany, September 16-20, 2019, Proceedings, Part II. Brefeld, Ulf; Fromont, Élisa; Hotho, Andreas; Knobbe, Arno J.; Maathuis, Marloes H.; Robardet, Céline. In Vol. 11907 of Lecture Notes in Computer Science. Springer, 2020.
  • [ BibTeX ]
  • [ URL ]
  @proceedings{brefeld2020machine2, booktitle = {ECML/PKDD (2)}, editor = {Brefeld, Ulf and Fromont, Élisa and Hotho, Andreas and Knobbe, Arno J. and Maathuis, Marloes H. and Robardet, Céline}, keywords = 2020, publisher = {Springer}, series = {Lecture Notes in Computer Science}, title = {Machine Learning and Knowledge Discovery in Databases - European Conference, ECML PKDD 2019, Würzburg, Germany, September 16-20, 2019, Proceedings, Part II}, volume = 11907, year = 2020 }
• Machine Learning and Knowledge Discovery in Databases - European Conference, ECML PKDD 2019, Würzburg, Germany, September 16-20, 2019, Proceedings, Part III. Brefeld, Ulf; Fromont, Élisa; Hotho, Andreas; Knobbe, Arno J.; Maathuis, Marloes H.; Robardet, Céline. In Vol. 11908 of Lecture Notes in Computer Science. Springer, 2020.
  • [ BibTeX ]
  • [ URL ]
  @proceedings{brefeld2020machine1, booktitle = {ECML/PKDD (3)}, editor = {Brefeld, Ulf and Fromont, Élisa and Hotho, Andreas and Knobbe, Arno J. and Maathuis, Marloes H. and Robardet, Céline}, keywords = 2020, publisher = {Springer}, series = {Lecture Notes in Computer Science}, title = {Machine Learning and Knowledge Discovery in Databases - European Conference, ECML PKDD 2019, Würzburg, Germany, September 16-20, 2019, Proceedings, Part III}, volume = 11908, year = 2020 }
• Layered Drawing of Undirected Graphs with Generalized Port Constraints. Walter, Julian; Zink, Johannes; Baumeister, Joachim; Wolff, Alexander. In 28th International Symposium on Graph Drawing and Network Visualization (GD 2020). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The aim of this research is a practical method to draw cable plans of complex machines. Such plans consist of electronic components and cables connecting specific ports of the components. Since the machines are configured for each client individually, cable plans need to be drawn automatically. The drawings must be well readable so that technicians can use them to debug the machines. In order to model plug sockets, we introduce port groups; within a group, ports can change their position (which we use to improve the aesthetics of the layout), but together the ports of a group must form a contiguous block. We approach the problem of drawing such cable plans by extending the well-known Sugiyama framework such that it incorporates ports and port groups. Since the framework assumes directed graphs, we propose several ways to orient the edges of the given undirected graph. We compare these methods experimentally, both on real-world data and synthetic data that carefully simulates real-world data. We measure the aesthetics of the resulting drawings by counting bends and crossings. Using these metrics, we compare our approach to Kieler [JVLC 2014], a library for drawing graphs in the presence of port constraints.

  @inproceedings{walter2020layered, abstract = {The aim of this research is a practical method to draw cable plans of complex machines. Such plans consist of electronic components and cables connecting specific ports of the components. Since the machines are configured for each client individually, cable plans need to be drawn automatically. The drawings must be well readable so that technicians can use them to debug the machines. In order to model plug sockets, we introduce port groups; within a group, ports can change their position (which we use to improve the aesthetics of the layout), but together the ports of a group must form a contiguous block. We approach the problem of drawing such cable plans by extending the well-known Sugiyama framework such that it incorporates ports and port groups. Since the framework assumes directed graphs, we propose several ways to orient the edges of the given undirected graph. We compare these methods experimentally, both on real-world data and synthetic data that carefully simulates real-world data. We measure the aesthetics of the resulting drawings by counting bends and crossings. Using these metrics, we compare our approach to Kieler [JVLC 2014], a library for drawing graphs in the presence of port constraints.}, author = {Walter, Julian and Zink, Johannes and Baumeister, Joachim and Wolff, Alexander}, booktitle = {28th International Symposium on Graph Drawing and Network Visualization (GD 2020)}, keywords = {myown}, note = {cite arxiv:2008.10583}, title = {Layered Drawing of Undirected Graphs with Generalized Port Constraints}, year = 2020 }
• Context Matters! Identifying Social Context Factors and Assessing Their Relevance for a Socially Assistive Robot. von der Pütten, Astrid Marieke Rosenthal; Lugrin, Birgit; Steinhaeusser, Sophia C.; Klass, Lina. In Companion of the 2020 International Conference on Human-Robot Interaction, pp. 409–411. ACM, 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Rosenthal_von_der_P_tten_2020, author = {von der Pütten, Astrid Marieke Rosenthal and Lugrin, Birgit and Steinhaeusser, Sophia C. and Klass, Lina}, booktitle = {Companion of the 2020 International Conference on Human-Robot Interaction}, keywords = {steinhaeusser}, pages = {409-411}, publisher = {ACM}, title = {Context Matters! Identifying Social Context Factors and Assessing Their Relevance for a Socially Assistive Robot}, year = 2020 }
• Generating Real-Time Strategy Heightmaps using Cellular Automata. Ziegler, Peter; \textbf{Sebastian {von Mammen}}. In FDG ’20: Proceedings of the 15th International Conference on the Foundations of Digital Games. ACM, Bugibba, Malta, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper presents a new approach of heightmap generation for Real-Time Strategy games (RTS) based on Cellular Automata (CA) in the context of various established techniques. The proposed approach uses different CA rulesets to generate and modify maps for the RTS game Supreme Commander. To evaluate the quality of the generated maps, a survey was conducted asking 30 participants about map quality compared to user-generated maps. The participants rated the maps more balanced and novel but less aesthetically pleasing. The paper concludes with according future work propositions to improve the presented approach.

  @inproceedings{Ziegler:2020aa, abstract = {This paper presents a new approach of heightmap generation for Real-Time Strategy games (RTS) based on Cellular Automata (CA) in the context of various established techniques. The proposed approach uses different CA rulesets to generate and modify maps for the RTS game Supreme Commander. To evaluate the quality of the generated maps, a survey was conducted asking 30 participants about map quality compared to user-generated maps. The participants rated the maps more balanced and novel but less aesthetically pleasing. The paper concludes with according future work propositions to improve the presented approach.}, address = {Bugibba, Malta}, author = {Ziegler, Peter and \textbf{Sebastian {von Mammen}}}, booktitle = {FDG '20: Proceedings of the 15th International Conference on the Foundations of Digital Games}, keywords = {myown}, publisher = {ACM}, title = {Generating Real-Time Strategy Heightmaps using Cellular Automata}, year = 2020 }
• Improving Sentiment Analysis with Biofeedback Data. Schlör, Daniel; Zehe, Albin; Kobs, Konstantin; Veseli, Blerta; Westermeier, Franziska; Brübach, Larissa; Roth, Daniel; Latoschik, Marc Erich; Hotho, Andreas. In Proceedings of the Workshop on peOple in laNguage, vIsiOn and the miNd (ONION). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Humans frequently are able to read and interpret emotions of others by directly taking verbal and non-verbal signals in human-to-human communication into account or to infer or even experience emotions from mediated stories. For computers, however, emotion recognition is a complex problem: Thoughts and feelings are the roots of many behavioural responses and they are deeply entangled with neurophysiological changes within humans. As such, emotions are very subjective, often are expressed in a subtle manner, and are highly depending on context. For example, machine learning approaches for text-based sentiment analysis often rely on incorporating sentiment lexicons or language models to capture the contextual meaning. This paper explores if and how we further can enhance sentiment analysis using biofeedback of humans which are experiencing emotions while reading texts. Specifically, we record the heart rate and brain waves of readers that are presented with short texts which have been annotated with the emotions they induce. We use these physiological signals to improve the performance of a lexicon-based sentiment classifier. We find that the combination of several biosignals can improve the ability of a text-based classifier to detect the presence of a sentiment in a text on a per-sentence level.

  @inproceedings{schlor2020improving, abstract = {Humans frequently are able to read and interpret emotions of others by directly taking verbal and non-verbal signals in human-to-human communication into account or to infer or even experience emotions from mediated stories. For computers, however, emotion recognition is a complex problem: Thoughts and feelings are the roots of many behavioural responses and they are deeply entangled with neurophysiological changes within humans. As such, emotions are very subjective, often are expressed in a subtle manner, and are highly depending on context. For example, machine learning approaches for text-based sentiment analysis often rely on incorporating sentiment lexicons or language models to capture the contextual meaning. This paper explores if and how we further can enhance sentiment analysis using biofeedback of humans which are experiencing emotions while reading texts. Specifically, we record the heart rate and brain waves of readers that are presented with short texts which have been annotated with the emotions they induce. We use these physiological signals to improve the performance of a lexicon-based sentiment classifier. We find that the combination of several biosignals can improve the ability of a text-based classifier to detect the presence of a sentiment in a text on a per-sentence level.}, author = {Schlör, Daniel and Zehe, Albin and Kobs, Konstantin and Veseli, Blerta and Westermeier, Franziska and Brübach, Larissa and Roth, Daniel and Latoschik, Marc Erich and Hotho, Andreas}, booktitle = {Proceedings of the Workshop on peOple in laNguage, vIsiOn and the miNd (ONION)}, keywords = {myown}, title = {Improving Sentiment Analysis with Biofeedback Data}, year = 2020 }
• Emergent Multiplayer Games. Wodarczyk, Sebastian; \textbf{Sebastian {von Mammen}}. In IEEE CoG ’20: Proceedings of the 2nd International Conference on Games, pp. 33–40. IEEE, Osaka, Japan, 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Wodarczyk:2020aa, address = {Osaka, Japan}, author = {Wodarczyk, Sebastian and \textbf{Sebastian {von Mammen}}}, booktitle = {IEEE CoG '20: Proceedings of the 2nd International Conference on Games}, keywords = {myown}, organization = {IEEE}, pages = {33-40}, publisher = {IEEE}, title = {Emergent Multiplayer Games}, year = 2020 }
• Supporting Learning in Art History--Artificial Intelligence in Digital Humanities Education. Messemer, Heike; Perera, Walpola Layantha; Heinz, Matthias; Niebling, Florian; Maiwald, Ferdinand. In Workshop Gemeinschaften in Neuen Medien (GeNeMe) 2020. TUDpress, 2020.
  • [ BibTeX ]
  @inproceedings{messemer2020supporting, author = {Messemer, Heike and Perera, Walpola Layantha and Heinz, Matthias and Niebling, Florian and Maiwald, Ferdinand}, booktitle = {Workshop Gemeinschaften in Neuen Medien (GeNeMe) 2020}, keywords = {histstadt4d}, organization = {TUDpress}, title = {Supporting Learning in Art History–Artificial Intelligence in Digital Humanities Education}, year = 2020 }
• Integrating a Social Robot in Higher Education – A Field Study. Donnermann, Melissa; Schaper, Philipp; Lugrin, Birgit. In 29th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN 2020), pp. 573–579. 2020.
  • [ BibTeX ]
  @inproceedings{donnermann2020integrating, author = {Donnermann, Melissa and Schaper, Philipp and Lugrin, Birgit}, booktitle = {29th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN 2020)}, keywords = {MI}, pages = {573-579}, title = {Integrating a Social Robot in Higher Education – A Field Study}, year = 2020 }
• Drawing Subcubic 1-Planar Graphs with Few Bends, Few Slopes, and Large Angles. Kindermann, Philipp; Montecchiani, Fabrizio; Schlipf, Lena; Schulz, André. In Journal of Graph Algorithms and Applications, 25(1), pp. 1–28. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  We show that the 1-planar slope number of 3-connected cubic 1-planar graphs is at most 4 when edges are drawn as polygonal curves with at most one bend per edge. This bound is obtained with drawings whose vertex and crossing resolution is at least pi/4. On the other hand, there is an embedding of a graph that needs 3 slopes when drawn with 1-bend edges. We also show that two slopes always suffice for 1-planar drawings of subcubic 1-planar graphs with at most two bends per edge. This bound is obtained with vertex and crossing resolution pi/2. For straight-line drawings of 1-plane graphs, we present lower bounds for the 1-planar slope number in terms of the number of vertices and of the maximum degree.

  @article{kmss-ds1pg-jgaa20, abstract = {We show that the 1-planar slope number of 3-connected cubic 1-planar graphs is at most 4 when edges are drawn as polygonal curves with at most one bend per edge. This bound is obtained with drawings whose vertex and crossing resolution is at least pi/4. On the other hand, there is an embedding of a graph that needs 3 slopes when drawn with 1-bend edges. We also show that two slopes always suffice for 1-planar drawings of subcubic 1-planar graphs with at most two bends per edge. This bound is obtained with vertex and crossing resolution pi/2. For straight-line drawings of 1-plane graphs, we present lower bounds for the 1-planar slope number in terms of the number of vertices and of the maximum degree.}, author = {Kindermann, Philipp and Montecchiani, Fabrizio and Schlipf, Lena and Schulz, André}, journal = {Journal of Graph Algorithms and Applications}, keywords = {myown}, number = 1, pages = {1–28}, title = {Drawing Subcubic 1-Planar Graphs with Few Bends, Few Slopes, and Large Angles}, volume = 25, year = 2020 }
• What the user’s voice tells us about UX - Analysing parameters of the voice as indicators of the User Experience of the usage of intelligent voice assistants. Obremski, David; Wienrich, Carolin; Carolus, Astrid. Gesellschaft für Informatik e.V., 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{https://doi.org/10.18420/muc2020-ws105-377, author = {Obremski, David and Wienrich, Carolin and Carolus, Astrid}, keywords = {obremski}, publisher = {Gesellschaft für Informatik e.V.}, title = {What the user’s voice tells us about UX - Analysing parameters of the voice as indicators of the User Experience of the usage of intelligent voice assistants}, year = 2020 }
• (Expressive) Social Robot or Tablet? – On the Benefits of Embodiment and Non-verbal Expressivity of the Interface for a Smart Environment. Deublein, Andrea; Lugrin, Birgit. In International Conference on Persuasive Technology (PERSUASIVE 2020), Vol. 12064 of Lecture Notes in Computer Science, G.-H. S., J. T., M. C. (eds.). Springer, 2020.
  • [ BibTeX ]
  @inproceedings{deublein2021expressive, author = {Deublein, Andrea and Lugrin, Birgit}, booktitle = {International Conference on Persuasive Technology (PERSUASIVE 2020)}, editor = {S., Gram-Hansen and T., Jonasen and C., Midden}, keywords = {reflectedreality}, publisher = {Springer}, series = {Lecture Notes in Computer Science}, title = {(Expressive) Social Robot or Tablet? – On the Benefits of Embodiment and Non-verbal Expressivity of the Interface for a Smart Environment}, volume = 12064, year = 2020 }
• Pushing Out the Classroom Walls: A Scalability Benchmark for a Virtual Audience Behaviour Model in Virtual Reality. Glémarec, Yann; Lugrin, Jean-Luc; Bosser, Anne-Gwenn; Cagniat, Paul; Buche, Cédric; Latoschik, Marc Erich. Gesellschaft für Informatik e.V., 2020.
  • [ BibTeX ]
  • [ URL ]
  @article{https://doi.org/10.18420/muc2020-ws134-337, author = {Glémarec, Yann and Lugrin, Jean-Luc and Bosser, Anne-Gwenn and Cagniat, Paul and Buche, Cédric and Latoschik, Marc Erich}, keywords = {vraudi}, publisher = {Gesellschaft für Informatik e.V.}, title = {Pushing Out the Classroom Walls: A Scalability Benchmark for a Virtual Audience Behaviour Model in Virtual Reality}, year = 2020 }
• CoTeach – Connected Teacher Education. Carolin, Wienrich; Eisenmann, Maria; Latoschik, Marc Erich; Grafe, Silke. In Boosting Virtual Reality in Learning, focus europe special edition 2020 , M. Schwaiger (ed.). E.N.T.E.R., 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  CoTeach develops and evaluates innovative teaching and learning contexts for student teachers and scholars. One work package couples the potential of VR with principles of intercultural learning to create tangible experiences with pedagogically responsible value

  @incollection{carolin2020coteach, abstract = {CoTeach develops and evaluates innovative teaching and learning contexts for student teachers and scholars. One work package couples the potential of VR with principles of intercultural learning to create tangible experiences with pedagogically responsible value}, author = {Carolin, Wienrich and Eisenmann, Maria and Latoschik, Marc Erich and Grafe, Silke}, booktitle = {Boosting Virtual Reality in Learning}, edition = {focus europe special edition 2020}, editor = {Schwaiger, Michael}, keywords = {c.wienrich}, publisher = {E.N.T.E.R.}, series = {VRinSight Green Paper}, title = {CoTeach – Connected Teacher Education}, year = 2020 }
• Mind the Gap: A Framework (BehaveFIT) Guiding The Use of Immersive Technologies in Behavior Change Processes. Wienrich, Carolin; Döllinger, Nina Ines; Hein, Rebecca. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The design and evaluation of assisting technologies to support behavior change processes have become an essential topic within the field of human-computer interaction research in general and the field of immersive intervention technologies in particular. The mechanisms and success of behavior change techniques and interventions are broadly investigated in the field of psychology. However, it is not always easy to adapt these psychological findings to the context of immersive technologies. The lack of theoretical foundation also leads to a lack of explanation as to why and how immersive interventions support behavior change processes. The Behavioral Framework for immersive Technologies (BehaveFIT) addresses this lack by (1) presenting an intelligible categorization and condensation of psychological barriers and immersive features, by (2) suggesting a mapping that shows why and how immersive technologies can help to overcome barriers, and finally by (3) proposing a generic prediction path that enables a structured, theory-based approach to the development and evaluation of immersive interventions. These three steps explain how BehaveFIT can be used, and include guiding questions and one example for each step. Thus, the present paper contributes to guidance for immersive intervention design and evaluation, showing that immersive interventions support behavior change processes and explain and predict 'why' and 'how' immersive interventions can bridge the intention-behavior-gap.

  @preprint{wienrich2020framework, abstract = {The design and evaluation of assisting technologies to support behavior change processes have become an essential topic within the field of human-computer interaction research in general and the field of immersive intervention technologies in particular. The mechanisms and success of behavior change techniques and interventions are broadly investigated in the field of psychology. However, it is not always easy to adapt these psychological findings to the context of immersive technologies. The lack of theoretical foundation also leads to a lack of explanation as to why and how immersive interventions support behavior change processes. The Behavioral Framework for immersive Technologies (BehaveFIT) addresses this lack by (1) presenting an intelligible categorization and condensation of psychological barriers and immersive features, by (2) suggesting a mapping that shows why and how immersive technologies can help to overcome barriers, and finally by (3) proposing a generic prediction path that enables a structured, theory-based approach to the development and evaluation of immersive interventions. These three steps explain how BehaveFIT can be used, and include guiding questions and one example for each step. Thus, the present paper contributes to guidance for immersive intervention design and evaluation, showing that immersive interventions support behavior change processes and explain and predict 'why' and 'how' immersive interventions can bridge the intention-behavior-gap.}, author = {Wienrich, Carolin and Döllinger, Nina Ines and Hein, Rebecca}, journal = {arXiv preprint arXiv:2012.10912.}, keywords = {myown}, note = {cite arxiv:2012.10912}, title = {Mind the Gap: A Framework (BehaveFIT) Guiding The Use of Immersive Technologies in Behavior Change Processes}, year = 2020 }
• Body Weight Perception of Females using Photorealistic Avatars in Virtual and Augmented Reality. Wolf, Erik; Döllinger, Nina; Mal, David; Wienrich, Carolin; Botsch, Mario; Latoschik, Marc Erich. In 2020 IEEE International Symposium on Mixed and Augmented Reality (ISMAR), pp. 462–473. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The appearance of avatars can potentially alter changes in their users' perception and behavior. Based on this finding, approaches to support the therapy of body perception disturbances in eating or body weight disorders by mixed reality (MR) systems gain in importance. However, the methodological heterogeneity of previous research has made it difficult to assess the suitability of different MR systems for therapeutic use in these areas. The effects of MR system properties and related psychometric factors on body-related perceptions have so far remained unclear. We developed an interactive virtual mirror embodiment application to investigate the differences between an augmented reality see-through head-mounted-display (HMD) and a virtual reality HMD on the before-mentioned factors. Additionally, we considered the influence of the participant's body-mass-index (BMI) and the BMI difference between participants and their avatars on the estimations. The 54 normal-weight female participants significantly underestimated the weight of their photorealistic, generic avatar in both conditions. Body weight estimations were significantly predicted by the participants' BMI and the BMI difference. We also observed partially significant differences in presence and tendencies for differences in virtual body ownership between the systems. Our results offer new insights into the relationships of body weight perception in different MR environments and provide new perspectives for the development of therapeutic applications.

  @inproceedings{wolf2020bodyweight, abstract = {The appearance of avatars can potentially alter changes in their users' perception and behavior. Based on this finding, approaches to support the therapy of body perception disturbances in eating or body weight disorders by mixed reality (MR) systems gain in importance. However, the methodological heterogeneity of previous research has made it difficult to assess the suitability of different MR systems for therapeutic use in these areas. The effects of MR system properties and related psychometric factors on body-related perceptions have so far remained unclear. We developed an interactive virtual mirror embodiment application to investigate the differences between an augmented reality see-through head-mounted-display (HMD) and a virtual reality HMD on the before-mentioned factors. Additionally, we considered the influence of the participant's body-mass-index (BMI) and the BMI difference between participants and their avatars on the estimations. The 54 normal-weight female participants significantly underestimated the weight of their photorealistic, generic avatar in both conditions. Body weight estimations were significantly predicted by the participants' BMI and the BMI difference. We also observed partially significant differences in presence and tendencies for differences in virtual body ownership between the systems. Our results offer new insights into the relationships of body weight perception in different MR environments and provide new perspectives for the development of therapeutic applications.}, author = {Wolf, Erik and Döllinger, Nina and Mal, David and Wienrich, Carolin and Botsch, Mario and Latoschik, Marc Erich}, booktitle = {2020 IEEE International Symposium on Mixed and Augmented Reality (ISMAR)}, keywords = {dmal}, pages = {462-473}, title = {Body Weight Perception of Females using Photorealistic Avatars in Virtual and Augmented Reality}, year = 2020 }
• Simplification of Polyline Bundles. Spoerhase, Joachim; Storandt, Sabine; Zink, Johannes. In Proc. 17th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT’20). 2020.
  • [ BibTeX ]
  @inproceedings{spoerhase2020simplification, author = {Spoerhase, Joachim and Storandt, Sabine and Zink, Johannes}, booktitle = {Proc. 17th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT'20)}, keywords = {bundle}, title = {Simplification of Polyline Bundles}, year = 2020 }
• The Power of Composition: Abstracting a Multi-Device SDN Data Path Through a Single API. Geissler, Stefan; Herrnleben, Stefan; Bauer, Robert; Grigorjew, Alexej; Zinner, Thomas; Jarschel, Michael. In IEEE Trans. Netw. Serv. Manag., 17(2), pp. 722–735. 2020.
  • [ BibTeX ]
  • [ URL ]
  @article{journals/tnsm/GeisslerHBGZJ20, author = {Geissler, Stefan and Herrnleben, Stefan and Bauer, Robert and Grigorjew, Alexej and Zinner, Thomas and Jarschel, Michael}, journal = {IEEE Trans. Netw. Serv. Manag.}, keywords = {t_full}, number = 2, pages = {722-735}, title = {The Power of Composition: Abstracting a Multi-Device SDN Data Path Through a Single API.}, volume = 17, year = 2020 }
• The Complexity of Finding Tangles. Firman, Oksana; Felsner, Stefan; Kindermann, Philipp; Ravsky, Alexander; Wolff, Alexander; Zink, Johannes. In Proceedings of the 36th European Workshop on Computational Geometry (EuroCG’20), S. Chaplick, P. Kindermann, A. Wolff (eds.), pp. 67:1–67:8. Würzburg, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  We study the following combinatorial problem. Given a set of n y-monotone curves, which we call wires, a tangle determines the order of the wires on a number of horizontal layers such that the orders of the wires on any two consecutive layers differ only in swaps of neighboring wires. Given a multiset L of swaps (that is, unordered pairs of wires) and an initial order of the wires, a tangle realizes L if each pair of wires changes its order exactly as many times as specified by L. Finding a tangle that realizes a given multiset of swaps and uses the least number of layers is known to be NP-hard. We show that it is even NP-hard to decide if a realizing tangle exists.

  @inproceedings{ffkrwz-tcft-eurocg20, abstract = {We study the following combinatorial problem. Given a set of n y-monotone curves, which we call wires, a tangle determines the order of the wires on a number of horizontal layers such that the orders of the wires on any two consecutive layers differ only in swaps of neighboring wires. Given a multiset L of swaps (that is, unordered pairs of wires) and an initial order of the wires, a tangle realizes L if each pair of wires changes its order exactly as many times as specified by L. Finding a tangle that realizes a given multiset of swaps and uses the least number of layers is known to be NP-hard. We show that it is even NP-hard to decide if a realizing tangle exists.}, author = {Firman, Oksana and Felsner, Stefan and Kindermann, Philipp and Ravsky, Alexander and Wolff, Alexander and Zink, Johannes}, booktitle = {Proceedings of the 36th European Workshop on Computational Geometry (EuroCG'20)}, editor = {Chaplick, Steven and Kindermann, Philipp and Wolff, Alexander}, keywords = {myown}, note = {Abstract}, pages = {67:1–67:8}, publisher = {Würzburg}, title = {The Complexity of Finding Tangles}, year = 2020 }
• Von Medienbeiträgen und Applikationen - ein interdisziplinäres Konzept zum Lehren und Lernen mit Augmented und Virtual Reality für die Hochschullehre. Bucher, Kristina; Oberdörfer, Sebastian; Grafe, Silke; Latoschik, Marc Erich. In Schnittstellen und Interfaces - Digitaler Wandel in Bildungseinrichtungen, Vol. 7, T. Knaus, O. Merz (eds.), pp. 225–238. kopaed, Munich, Germany, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Augmented Reality (AR) und Virtual Reality (VR) finden zunehmend Eingang in die Bildungspraxis. Mit ihrem Einsatz sind sowohl Potentiale als auch mögliche Problemlagen für Lehr- und Lernprozesse verbunden. Daher ist es Aufgabe der Lehrerbildung, (angehenden) Lehrpersonen einen Kompetenzerwerb für die Einbindung von AR und VR in Lehr- und Lernprozesse zu ermöglichen. Vor diesem Hintergrund wurde ein interdisziplinäres Konzept für die Hochschullehre entwickelt und hinsichtlich der Zielerreichung empirisch evaluiert. Im Beitrag werden zunächst bedeutsame Gestaltungsaspekte des Konzepts sowie erste Befunde aus einer Pilotuntersuchung vorgestellt. Im Anschluss werden handlungspraktische Erfahrungen der interdisziplinären Zusammenarbeit reflektiert und diskutiert.

  @incollection{bucher2020medienbeitrgen, abstract = {Augmented Reality (AR) und Virtual Reality (VR) finden zunehmend Eingang in die Bildungspraxis. Mit ihrem Einsatz sind sowohl Potentiale als auch mögliche Problemlagen für Lehr- und Lernprozesse verbunden. Daher ist es Aufgabe der Lehrerbildung, (angehenden) Lehrpersonen einen Kompetenzerwerb für die Einbindung von AR und VR in Lehr- und Lernprozesse zu ermöglichen. Vor diesem Hintergrund wurde ein interdisziplinäres Konzept für die Hochschullehre entwickelt und hinsichtlich der Zielerreichung empirisch evaluiert. Im Beitrag werden zunächst bedeutsame Gestaltungsaspekte des Konzepts sowie erste Befunde aus einer Pilotuntersuchung vorgestellt. Im Anschluss werden handlungspraktische Erfahrungen der interdisziplinären Zusammenarbeit reflektiert und diskutiert.}, address = {Munich, Germany}, author = {Bucher, Kristina and Oberdörfer, Sebastian and Grafe, Silke and Latoschik, Marc Erich}, booktitle = {Schnittstellen und Interfaces - Digitaler Wandel in Bildungseinrichtungen}, editor = {Knaus, Thomas and Merz, Olga}, keywords = {varyfast}, pages = {225-238}, publisher = {kopaed}, series = {fraMediale}, title = {Von Medienbeiträgen und Applikationen - ein interdisziplinäres Konzept zum Lehren und Lernen mit Augmented und Virtual Reality für die Hochschullehre}, volume = 7, year = 2020 }
• Financial Fraud Detection with Improved Neural Arithmetic Logic Units. Schlör, Daniel; Ring, Markus; Krause, Anna; Hotho, Andreas. Vol. Fifth Workshop on MIning DAta for financial applicationS. 2020.
  • [ BibTeX ]
  @proceedings{schlor2020financial, author = {Schlör, Daniel and Ring, Markus and Krause, Anna and Hotho, Andreas}, keywords = {inalu}, number = 5, title = {Financial Fraud Detection with Improved Neural Arithmetic Logic Units}, volume = {Fifth Workshop on MIning DAta for financial applicationS}, year = 2020 }
• Anomaly Detection in Beehives using Deep Recurrent Autoencoders. Davidson, Padraig; Steininger, Michael; Lautenschlager, Florian; Kobs, Konstantin; Krause, Anna; Hotho, Andreas. In Proceedings of the 9th International Conference on Sensor Networks (SENSORNETS 2020), pp. 142–149. SCITEPRESS – Science and Technology Publications, Lda., 2020.
  • [ BibTeX ]
  @inproceedings{davidson2020anomaly, author = {Davidson, Padraig and Steininger, Michael and Lautenschlager, Florian and Kobs, Konstantin and Krause, Anna and Hotho, Andreas}, booktitle = {Proceedings of the 9th International Conference on Sensor Networks (SENSORNETS 2020)}, keywords = {beehive}, number = 9, pages = {142-149}, publisher = {SCITEPRESS – Science and Technology Publications, Lda.}, title = {Anomaly Detection in Beehives using Deep Recurrent Autoencoders}, year = 2020 }
• iNALU: Improved Neural Arithmetic Logic Unit. Schlör, Daniel; Ring, Markus; Hotho, Andreas. In Frontiers in Artificial Intelligence, 3, p. 71. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Neural networks have to capture mathematical relationships in order to learn various tasks. They approximate these relations implicitly and therefore often do not generalize well. The recently proposed Neural Arithmetic Logic Unit (NALU) is a novel neural architecture which is able to explicitly represent the mathematical relationships by the units of the network to learn operations such as summation, subtraction or multiplication. Although NALUs have been shown to perform well on various downstream tasks, an in-depth analysis reveals practical shortcomings by design, such as the inability to multiply or divide negative input values or training stability issues for deeper networks. We address these issues and propose an improved model architecture. We evaluate our model empirically in various settings from learning basic arithmetic operations to more complex functions. Our experiments indicate that our model solves stability issues and outperforms the original NALU model in means of arithmetic precision and convergence.

  @article{schlor2020inalu, abstract = {Neural networks have to capture mathematical relationships in order to learn various tasks. They approximate these relations implicitly and therefore often do not generalize well. The recently proposed Neural Arithmetic Logic Unit (NALU) is a novel neural architecture which is able to explicitly represent the mathematical relationships by the units of the network to learn operations such as summation, subtraction or multiplication. Although NALUs have been shown to perform well on various downstream tasks, an in-depth analysis reveals practical shortcomings by design, such as the inability to multiply or divide negative input values or training stability issues for deeper networks. We address these issues and propose an improved model architecture. We evaluate our model empirically in various settings from learning basic arithmetic operations to more complex functions. Our experiments indicate that our model solves stability issues and outperforms the original NALU model in means of arithmetic precision and convergence.}, author = {Schlör, Daniel and Ring, Markus and Hotho, Andreas}, journal = {Frontiers in Artificial Intelligence}, keywords = {selected}, pages = 71, title = {iNALU: Improved Neural Arithmetic Logic Unit}, volume = 3, year = 2020 }
• Integrating Keywords into BERT4Rec for Sequential Recommendation. Fischer, Elisabeth; Zoller, Daniel; Dallmann, Alexander; Hotho, Andreas. In KI 2020: Advances in Artificial Intelligence, Vol. 12325, pp. 275–282. Springer International Publishing, Cham, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  A crucial part of recommender systems is to model the user’s preference based on her previous interactions. Different neural networks (e.g., Recurrent Neural Networks), that predict the next item solely based on the sequence of interactions have been successfully applied to sequential recommendation. Recently, BERT4Rec has been proposed, which adapts the BERT architecture based on the Transformer model and training methods used in the Neural Language Modeling community to this task. However, BERT4Rec still only relies on item identifiers to model the user preference, ignoring other sources of information. Therefore, as a first step to include additional information, we propose KeBERT4Rec, a modification of BERT4Rec, which utilizes keyword descriptions of items. We compare two variants for adding keywords to the model on two datasets, a Movielens dataset and a dataset of an online fashion store. First results show that both versions of our model improves the sequential recommending task compared to BERT4Rec.

  @inproceedings{fischer2020integrating, abstract = {A crucial part of recommender systems is to model the user’s preference based on her previous interactions. Different neural networks (e.g., Recurrent Neural Networks), that predict the next item solely based on the sequence of interactions have been successfully applied to sequential recommendation. Recently, BERT4Rec has been proposed, which adapts the BERT architecture based on the Transformer model and training methods used in the Neural Language Modeling community to this task. However, BERT4Rec still only relies on item identifiers to model the user preference, ignoring other sources of information. Therefore, as a first step to include additional information, we propose KeBERT4Rec, a modification of BERT4Rec, which utilizes keyword descriptions of items. We compare two variants for adding keywords to the model on two datasets, a Movielens dataset and a dataset of an online fashion store. First results show that both versions of our model improves the sequential recommending task compared to BERT4Rec.}, address = {Cham}, author = {Fischer, Elisabeth and Zoller, Daniel and Dallmann, Alexander and Hotho, Andreas}, booktitle = {KI 2020: Advances in Artificial Intelligence}, keywords = {keyword}, pages = {275-282}, publisher = {Springer International Publishing}, title = {Integrating Keywords into BERT4Rec for Sequential Recommendation}, volume = 12325, year = 2020 }
• Machine Learning for Optical Network Security Monitoring: A Practical Perspective. Furdek, Marija; Natalino, Carlos; Lipp, Fabian; Hock, David; Di Giglio, Andrea; Schiano, Marco. In Journal of Lightwave Technology, 38(11), pp. 2860–2871. IEEE, 2020.
  • [ BibTeX ]
  • [ URL ]
  @article{furdek2020machine, author = {Furdek, Marija and Natalino, Carlos and Lipp, Fabian and Hock, David and Di Giglio, Andrea and Schiano, Marco}, journal = {Journal of Lightwave Technology}, keywords = {myown}, number = 11, pages = {2860–2871}, publisher = {IEEE}, title = {Machine Learning for Optical Network Security Monitoring: A Practical Perspective}, volume = 38, year = 2020 }
• OpenLUR: Off-the-shelf air pollution modeling with open features and machine learning. Lautenschlager, Florian; Becker, Martin; Kobs, Konstantin; Steininger, Michael; Davidson, Padraig; Krause, Anna; Hotho, Andreas. In Atmospheric Environment, 233, p. 117535. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  To assess the exposure of citizens to pollutants like NOx or particulate matter in urban areas, land use regression (LUR) models are a well established method. LUR models leverage information about environmental and anthropogenic factors such as cars, heating, or industry to predict air pollution in areas where no measurements have been made. However, existing approaches are often not globally applicable and require tedious hyper-parameter tuning to enable high quality predictions. In this work, we tackle these issues by introducing OpenLUR, an off-the-shelf approach for modeling air pollution that (i) works on a set of novel features solely extracted from the globally and openly available data source OpenStreetMap and (ii) is based on state-of-the-art machine learning featuring automated hyper-parameter tuning in order to minimize manual effort. We show that our proposed features are able to outperform their counterparts from local and closed sources, and illustrate how automated hyper parameter tuning can yield competitve results while alleviating the need for expert knowledge in machine learning and manual effort. Importantly, we further demonstrate the potential of the global availability of our features by applying cross-learning across different cities in order to reduce the need for a large amount of training samples. Overall, OpenLUR represents an off-the-shelf approach that facilitates easily reproducible experiments and the development of globally applicable models.

  @article{lautenschlager2020openlur, abstract = {To assess the exposure of citizens to pollutants like NOx or particulate matter in urban areas, land use regression (LUR) models are a well established method. LUR models leverage information about environmental and anthropogenic factors such as cars, heating, or industry to predict air pollution in areas where no measurements have been made. However, existing approaches are often not globally applicable and require tedious hyper-parameter tuning to enable high quality predictions. In this work, we tackle these issues by introducing OpenLUR, an off-the-shelf approach for modeling air pollution that (i) works on a set of novel features solely extracted from the globally and openly available data source OpenStreetMap and (ii) is based on state-of-the-art machine learning featuring automated hyper-parameter tuning in order to minimize manual effort. We show that our proposed features are able to outperform their counterparts from local and closed sources, and illustrate how automated hyper parameter tuning can yield competitve results while alleviating the need for expert knowledge in machine learning and manual effort. Importantly, we further demonstrate the potential of the global availability of our features by applying cross-learning across different cities in order to reduce the need for a large amount of training samples. Overall, OpenLUR represents an off-the-shelf approach that facilitates easily reproducible experiments and the development of globally applicable models.}, author = {Lautenschlager, Florian and Becker, Martin and Kobs, Konstantin and Steininger, Michael and Davidson, Padraig and Krause, Anna and Hotho, Andreas}, journal = {Atmospheric Environment}, keywords = {pollution}, pages = 117535, title = {OpenLUR: Off-the-shelf air pollution modeling with open features and machine learning}, volume = 233, year = 2020 }
• Analyzing Spatial Distribution of Photographs in Cultural Heritage Applications. Niebling, Florian; Bruschke, Jonas; Messemer, Heike; Wacker, Markus; von Mammen, Sebastian. In Visual Computing for Cultural Heritage, F. Liarokapis, A. Voulodimos, N. Doulamis, A. Doulamis (eds.), pp. 391–408. Springer, Cham, 2020.
  • [ BibTeX ]
  • [ URL ]
  @inbook{books/sp/20/NieblingBMWM20, address = {Cham}, author = {Niebling, Florian and Bruschke, Jonas and Messemer, Heike and Wacker, Markus and von Mammen, Sebastian}, booktitle = {Visual Computing for Cultural Heritage}, editor = {Liarokapis, Fotis and Voulodimos, Athanasios and Doulamis, Nikolaos and Doulamis, Anastasios}, keywords = {histstadt4d}, pages = {391-408}, publisher = {Springer}, title = {Analyzing Spatial Distribution of Photographs in Cultural Heritage Applications}, type = {Book Section}, year = 2020 }
• Immersive Analysis of Crystallographic Diffraction Data. Knote, Andreas; von Mammen, Sebastian; Gao, YunYun; Thorn, Andrea. In VRST, R. J. Teather, C. Joslin, W. Stuerzlinger, P. Figueroa, Y. Hu, A. U. Batmaz, W. Lee, F. R. Ortega (eds.), pp. 58:1–58:3. ACM, 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{conf/vrst/KnoteMGT20, author = {Knote, Andreas and von Mammen, Sebastian and Gao, YunYun and Thorn, Andrea}, booktitle = {VRST}, crossref = {conf/vrst/2020}, editor = {Teather, Robert J. and Joslin, Chris and Stuerzlinger, Wolfgang and Figueroa, Pablo and Hu, Yaoping and Batmaz, Anil Ufuk and Lee, Wonsook and Ortega, Francisco R.}, keywords = {myown}, pages = {58:1-58:3}, publisher = {ACM}, title = {Immersive Analysis of Crystallographic Diffraction Data.}, year = 2020 }
• Graph Drawing Contest Report. Kindermann, Philipp; Mchedlidze, Tamara; Meulemans, Wouter; Rutter, Ignaz. In Proc. 28th International Symposium on Graph Drawing and Network Visualization (GD’20), D. Auber, P. Valtr (eds.). 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{kmmr-gdcr-gd20, author = {Kindermann, Philipp and Mchedlidze, Tamara and Meulemans, Wouter and Rutter, Ignaz}, booktitle = {Proc. 28th International Symposium on Graph Drawing and Network Visualization (GD'20)}, editor = {Auber, David and Valtr, Pavel}, keywords = {graph}, note = {To appear}, title = {Graph Drawing Contest Report}, year = 2020 }
• Digital fitting instructions for further usage in product-lifecycle. Brandenburg, Elisabeth; Ringel, Oliver; Zimmermann, Thomas; D{ö}llinger, Nina; Stark, Rainer. TESConf, 2020.
  • [ BibTeX ]
  @article{brandenburg2020digital, author = {Brandenburg, Elisabeth and Ringel, Oliver and Zimmermann, Thomas and D{\"o}llinger, Nina and Stark, Rainer}, keywords = {myown}, publisher = {TESConf}, title = {Digital fitting instructions for further usage in product-lifecycle}, year = 2020 }
• Reducing the Fear of Height by Inducing Proteus Effect of a Dragon Avatar. Oyanagi, Akimi; Narumi, Takuji; Lugrin, Jean-Luc; Ando, Hideyuki; Ohmura, Ren. In Transactions of the Virtual Reality Society of Japan, Vol. 25. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Existing studies have reported that the Full Body Ownership Illusion let users perceive a virtual body as our own body. It has also revealed the Proteus Effect that avatars' appearance could affect user's behavior, attitude and mental condition by inducing the Full Body Ownership Illusion. While many studies have focused on a humanoid avatar and its psychological effects, a previous study has reported that the Full Body Ownership Transfer can be induced even in the case of an animal avatar. In case of inducing the Full Body Ownership Transfer on an animal avatar, it can be expected to induce the psychological effect different from the one by a human avatar. Hence, this study examines a dragon avatar, which has impression of strong body and flight ability, can reduce the fear of height as the Proteus Effect by the Full Body Ownership Transfer. We carried out an experiment with some scenarios where a subject transformed into a dragon and flied into a height, comparing with operating a human avatar. The results showed that transforming into the dragon avatar can improve subjective score and physiological reaction for the fear of height

  @inproceedings{oyanagi, abstract = {Existing studies have reported that the Full Body Ownership Illusion let users perceive a virtual body as our own body. It has also revealed the Proteus Effect that avatars' appearance could affect user's behavior, attitude and mental condition by inducing the Full Body Ownership Illusion. While many studies have focused on a humanoid avatar and its psychological effects, a previous study has reported that the Full Body Ownership Transfer can be induced even in the case of an animal avatar. In case of inducing the Full Body Ownership Transfer on an animal avatar, it can be expected to induce the psychological effect different from the one by a human avatar. Hence, this study examines a dragon avatar, which has impression of strong body and flight ability, can reduce the fear of height as the Proteus Effect by the Full Body Ownership Transfer. We carried out an experiment with some scenarios where a subject transformed into a dragon and flied into a height, comparing with operating a human avatar. The results showed that transforming into the dragon avatar can improve subjective score and physiological reaction for the fear of height}, author = {Oyanagi, Akimi and Narumi, Takuji and Lugrin, Jean-Luc and Ando, Hideyuki and Ohmura, Ren}, journal = {Transactions of the Virtual Reality Society of Japan}, keywords = {dragon}, note = {Best Paper Award 🏆}, number = 1, title = {Reducing the Fear of Height by Inducing Proteus Effect of a Dragon Avatar}, volume = 25, year = 2020 }
• LM4KG: Improving Common Sense Knowledge Graphs with Language Models. Omeliyanenko, Janna; Zehe, Albin; Hettinger, Lena; Hotho, Andreas. In The Semantic Web -- ISWC 2020, J. Z. Pan, V. Tamma, C. d’Amato, K. Janowicz, B. Fu, A. Polleres, O. Seneviratne, L. Kagal (eds.), pp. 456–473. Springer International Publishing, Cham, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Language Models (LMs) and Knowledge Graphs (KGs) are both active research areas in Machine Learning and Semantic Web. While LMs have brought great improvements for many downstream tasks on their own, they are often combined with KGs providing additionally aggregated, well structured knowledge. Usually, this is done by leveraging KGs to improve LMs. But what happens if we turn this around and use LMs to improve KGs?

  @inproceedings{omeliyanenko2020lm4kg, abstract = {Language Models (LMs) and Knowledge Graphs (KGs) are both active research areas in Machine Learning and Semantic Web. While LMs have brought great improvements for many downstream tasks on their own, they are often combined with KGs providing additionally aggregated, well structured knowledge. Usually, this is done by leveraging KGs to improve LMs. But what happens if we turn this around and use LMs to improve KGs?}, address = {Cham}, author = {Omeliyanenko, Janna and Zehe, Albin and Hettinger, Lena and Hotho, Andreas}, booktitle = {The Semantic Web – ISWC 2020}, editor = {Pan, Jeff Z. and Tamma, Valentina and d'Amato, Claudia and Janowicz, Krzysztof and Fu, Bo and Polleres, Axel and Seneviratne, Oshani and Kagal, Lalana}, keywords = {selected}, pages = {456–473}, publisher = {Springer International Publishing}, title = {LM4KG: Improving Common Sense Knowledge Graphs with Language Models}, year = 2020 }
• An Automated Pipeline for a Browser-Based, City-Scale Mobile 4D VR Application Based on Historical Images. Münster, Sander; Maiwald, Ferdinand; Lehmann, Christoph; Lazariv, Taras; Hofmann, Mathias; Niebling, Florian. In Proceedings of the 2nd Workshop on Structuring and Understanding of Multimedia HeritAge Contents, of SUMAC’20, pp. 33–40. Association for Computing Machinery, Seattle, WA, USA, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The process for automatically creating 3D city models from contemporary photographs and visualizing them on mobile devices is now well established, but historical 4D city models are more challenging. The fourth dimension here is time. This article describes an automated VR pipeline based on historical photographs and resulting in an interactive browser-based device-rendered 4D visualization and information system for mobile devices. Since the pipeline shown is currently still under development, initial results for stages of the process will be shown and assessed for accuracy and usability.

  @inproceedings{10.1145/3423323.3425748, abstract = {The process for automatically creating 3D city models from contemporary photographs and visualizing them on mobile devices is now well established, but historical 4D city models are more challenging. The fourth dimension here is time. This article describes an automated VR pipeline based on historical photographs and resulting in an interactive browser-based device-rendered 4D visualization and information system for mobile devices. Since the pipeline shown is currently still under development, initial results for stages of the process will be shown and assessed for accuracy and usability.}, address = {New York, NY, USA}, author = {Münster, Sander and Maiwald, Ferdinand and Lehmann, Christoph and Lazariv, Taras and Hofmann, Mathias and Niebling, Florian}, booktitle = {Proceedings of the 2nd Workshop on Structuring and Understanding of Multimedia HeritAge Contents}, keywords = {niebling}, pages = {33–40}, publisher = {Association for Computing Machinery}, series = {SUMAC'20}, title = {An Automated Pipeline for a Browser-Based, City-Scale Mobile 4D VR Application Based on Historical Images}, year = 2020 }
• Computing Object Selection Difficulty in VR Using Run-Time Contextual Analysis. Zimmerer, Chris; Heinrich, Ronja; Fischbach, Martin; Lugrin, Jean-Luc; Latoschik, Marc Erich. In 26th ACM Symposium on Virtual Reality Software and Technology, of VRST ’20. Association for Computing Machinery, Virtual Event, Canada, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper introduces a method for computing the difficulty of selection tasks in virtual environments using pointing metaphors by operationalizing an established human motor behavior model. In contrast to previous work, the difficulty is calculated automatically at run-time for arbitrary environments. We present and provide the implementation of our method within Unity 3D. The difficulty is computed based on a contextual analysis of spatial boundary conditions, i.e., target object size and shape, distance to the user, and occlusion. We believe our method will enable developers to build adaptive systems that automatically equip the user with the most appropriate selection technique according to the context. Further, it provides a standard metric to better evaluate and compare different selection techniques.

  @inproceedings{10.1145/3385956.3422089, abstract = {This paper introduces a method for computing the difficulty of selection tasks in virtual environments using pointing metaphors by operationalizing an established human motor behavior model. In contrast to previous work, the difficulty is calculated automatically at run-time for arbitrary environments. We present and provide the implementation of our method within Unity 3D. The difficulty is computed based on a contextual analysis of spatial boundary conditions, i.e., target object size and shape, distance to the user, and occlusion. We believe our method will enable developers to build adaptive systems that automatically equip the user with the most appropriate selection technique according to the context. Further, it provides a standard metric to better evaluate and compare different selection techniques.}, address = {New York, NY, USA}, author = {Zimmerer, Chris and Heinrich, Ronja and Fischbach, Martin and Lugrin, Jean-Luc and Latoschik, Marc Erich}, booktitle = {26th ACM Symposium on Virtual Reality Software and Technology}, keywords = {myown}, note = {Best Poster Award 🏆}, publisher = {Association for Computing Machinery}, series = {VRST '20}, title = {Computing Object Selection Difficulty in VR Using Run-Time Contextual Analysis}, year = 2020 }
• A Simple Primal-Dual Approximation Algorithm for 2-Edge-Connected Spanning Subgraphs. Beyer, Stephan; Chimani, Markus; Spoerhase, Joachim. In Proc. 26th International Computing and Combinatorics Conference (COCOON’20). 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{beyer-etal18:simple-pd-2ecss, author = {Beyer, Stephan and Chimani, Markus and Spoerhase, Joachim}, booktitle = {Proc. 26th International Computing and Combinatorics Conference (COCOON'20)}, keywords = {algorithm}, note = {to appear}, title = {A Simple Primal-Dual Approximation Algorithm for 2-Edge-Connected Spanning Subgraphs}, year = 2020 }
• Quantifying measurement quality and load distribution in Tor. Greubel, Andre; Pohl, Steffen; Kounev, Samuel. In Proceedings of the 36th Annual Computer Security Applications Conference (ACSAC 2020). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Tor is a widely used anonymization network. Traffic is routed over different relay nodes to conceal the communication partners. However, if a single relay handles too much traffic, de-anonymization attacks are possible. The Tor Load Balancing Mechanism (TLBM) is responsible for balanced and secure load distribution. It must verify that relays cannot attract more traffic than they should by lying about their self-reported bandwidth. This work shows that the current bandwidth measurement method used for bandwidth verification is not suitable to verify the bandwidth of many relays. Most importantly, multiple measurements of high-bandwidth relays are uncorrelated to each other. Furthermore, we analyze the current load distribution in Tor. We show that the current load distribution reduces the resources necessary for several large-scale de-anonymization attacks by more than 80\%. Additionally, as Tor favors fast relays during path selection, verifiable relays only handle a small fraction of Tor’s traffic. More precisely, we show that only 7.21\% of all paths consist of entry and exit relays verifiable by measurements. We discuss these results’ security implications and argue that future TLBM research should focus at least as much on secure load distribution as on high traffic performance.

  @article{greubel2020quantifying, abstract = {Tor is a widely used anonymization network. Traffic is routed over different relay nodes to conceal the communication partners. However, if a single relay handles too much traffic, de-anonymization attacks are possible. The Tor Load Balancing Mechanism (TLBM) is responsible for balanced and secure load distribution. It must verify that relays cannot attract more traffic than they should by lying about their self-reported bandwidth. This work shows that the current bandwidth measurement method used for bandwidth verification is not suitable to verify the bandwidth of many relays. Most importantly, multiple measurements of high-bandwidth relays are uncorrelated to each other. Furthermore, we analyze the current load distribution in Tor. We show that the current load distribution reduces the resources necessary for several large-scale de-anonymization attacks by more than 80\%. Additionally, as Tor favors fast relays during path selection, verifiable relays only handle a small fraction of Tor’s traffic. More precisely, we show that only 7.21\% of all paths consist of entry and exit relays verifiable by measurements. We discuss these results’ security implications and argue that future TLBM research should focus at least as much on secure load distribution as on high traffic performance.}, author = {Greubel, Andre and Pohl, Steffen and Kounev, Samuel}, journal = {Proceedings of the 36th Annual Computer Security Applications Conference (ACSAC 2020)}, keywords = {tor}, title = {Quantifying measurement quality and load distribution in Tor}, year = 2020 }
• The impact of the German strategy for containment of Coronavirus SARS-CoV-2 on the training characteristics, physical activity, sleep of highly trained kayakers and canoeists: A retrospective observational study. Zinner, Christoph; Matzka, Manuel; Leppich, Robert; Kounev, Samuel; Holmberg, HC; Sperlich, Billy. In Frontiers in Sports and Active Living, 2, p. 127. Frontiers, 2020.
  • [ BibTeX ]
  @article{zinner2020impact, author = {Zinner, Christoph and Matzka, Manuel and Leppich, Robert and Kounev, Samuel and Holmberg, HC and Sperlich, Billy}, journal = {Frontiers in Sports and Active Living}, keywords = {covid19}, pages = 127, publisher = {Frontiers}, title = {The impact of the German strategy for containment of Coronavirus SARS-CoV-2 on the training characteristics, physical activity, sleep of highly trained kayakers and canoeists: A retrospective observational study}, volume = 2, year = 2020 }
• Approximating Node-Weighted k-MST on Planar Graphs. Byrka, Jarosław; Lewandowski, Mateusz; Spoerhase, Joachim. In Theory of Computing Systems. 2020.
  • [ BibTeX ]
  @article{byrka2020approximating, author = {Byrka, Jarosław and Lewandowski, Mateusz and Spoerhase, Joachim}, journal = {Theory of Computing Systems}, keywords = {network}, title = {Approximating Node-Weighted k-MST on Planar Graphs}, year = 2020 }
• Recognizing Stick Graphs with and without Length Constraints. Chaplick, Steven; Kindermann, Philipp; L{{ö}}ffler, Andre; Thiele, Florian; Wolff, Alexander; Zaft, Alexander; Zink, Johannes. In Journal of Graph Algorithms and Applications, 24(4), pp. 657–681. 2020.
  • [ BibTeX ]
  @article{ckltwzz-rsglc-jgaa20, author = {Chaplick, Steven and Kindermann, Philipp and L{\"{o}}ffler, Andre and Thiele, Florian and Wolff, Alexander and Zaft, Alexander and Zink, Johannes}, journal = {Journal of Graph Algorithms and Applications}, keywords = {myown}, note = {Special Issue on Selected Papers from GD 2020}, number = 4, pages = {657–681}, title = {Recognizing Stick Graphs with and without Length Constraints}, volume = 24, year = 2020 }
• On Mixed Linear Layouts of Series-Parallel Graphs. Angelini, Patrizio; Bekos, Michael; Kindermann, Philipp; Mchedlidze, Tamara. In Proceedings of the 28th International Symposium on Graph Drawing and Network Visualization (GD’20), D. Auber, P. Valtr (eds.). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  A mixed s-stack q-queue layout of a graph consists of a linear ordering of its vertices and of a partition of its edges into s stacks and q queues, such that no two edges in the same stack cross and no two edges in the same queue nest. In 1992, Heath and Rosenberg conjectured that every planar graph admits a mixed 1-stack 1-queue layout. Recently, Pupyrev disproved this conjectured by demonstrating a planar partial 3-tree that does not admit a 1-stack 1-queue layout. In this note, we strengthen Pupyrev's result by showing that the conjecture does not hold even for 2-trees.

  @inproceedings{abkm-mllsp-gd20, abstract = {A mixed s-stack q-queue layout of a graph consists of a linear ordering of its vertices and of a partition of its edges into s stacks and q queues, such that no two edges in the same stack cross and no two edges in the same queue nest. In 1992, Heath and Rosenberg conjectured that every planar graph admits a mixed 1-stack 1-queue layout. Recently, Pupyrev disproved this conjectured by demonstrating a planar partial 3-tree that does not admit a 1-stack 1-queue layout. In this note, we strengthen Pupyrev's result by showing that the conjecture does not hold even for 2-trees.}, author = {Angelini, Patrizio and Bekos, Michael and Kindermann, Philipp and Mchedlidze, Tamara}, booktitle = {Proceedings of the 28th International Symposium on Graph Drawing and Network Visualization (GD'20)}, editor = {Auber, David and Valtr, Pavel}, keywords = {myown}, note = {To appear}, title = {On Mixed Linear Layouts of Series-Parallel Graphs}, year = 2020 }
• Evaluating the multi-task learning approach for land use regression modelling of air pollution. Dulny, Andrzej; Steininger, Michael; Lautenschlager, Florian; Krause, Anna; Hotho, Andreas. In International Conference on Frontiers of Artificial Intelligence and Machine Learning. IASED, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Air pollution has been linked to several health problems including heart disease, stroke and lung cancer. Modelling and analyzing this dependency requires reliable and accurate air pollutant measurements collected by stationary air monitoring stations. However, usually only a low number of such stations are present within a single city. To retrieve pollution concentrations for unmeasured locations, researchers rely on land use regression (LUR) models. Those models are typically developed for one pollutant only. However, as results in different areas have shown, modelling several related output variables through multi-task learning can improve the prediction results of the models significantly. In this work, we compared prediction results from single-task and multi-task learning multilayer perceptron models on measurements taken from the OpenSense dataset and the London Atmospheric Emissions Inventory dataset. LUR features were generated from OpenStreetMap using OpenLUR and used to train hard parameter sharing multilayer perceptron models. The results show multi-task learning with sufficient data significantly improves the performance of a LUR model.

  @inproceedings{dulny2020evaluating, abstract = {Air pollution has been linked to several health problems including heart disease, stroke and lung cancer. Modelling and analyzing this dependency requires reliable and accurate air pollutant measurements collected by stationary air monitoring stations. However, usually only a low number of such stations are present within a single city. To retrieve pollution concentrations for unmeasured locations, researchers rely on land use regression (LUR) models. Those models are typically developed for one pollutant only. However, as results in different areas have shown, modelling several related output variables through multi-task learning can improve the prediction results of the models significantly. In this work, we compared prediction results from single-task and multi-task learning multilayer perceptron models on measurements taken from the OpenSense dataset and the London Atmospheric Emissions Inventory dataset. LUR features were generated from OpenStreetMap using OpenLUR and used to train hard parameter sharing multilayer perceptron models. The results show multi-task learning with sufficient data significantly improves the performance of a LUR model.}, author = {Dulny, Andrzej and Steininger, Michael and Lautenschlager, Florian and Krause, Anna and Hotho, Andreas}, booktitle = {International Conference on Frontiers of Artificial Intelligence and Machine Learning}, keywords = {from:msteininger}, organization = {IASED}, title = {Evaluating the multi-task learning approach for land use regression modelling of air pollution}, year = 2020 }
• Urban History Research and Discovery in the Age of Digital Repositories. A Report About Users and Requirements. Münster, Sander; Niebling, Florian; Bruschke, Jonas; Barthel, Kristina; Friedrichs, Kristina; Kröber, Cindy; Maiwald, Ferdinand. In Digital Cultural Heritage, H. Kremers (ed.), pp. 63–84. Springer International Publishing, Cham, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The research group on four-dimensional research and communication of urban history (HistStadt4D) investigates and develops methods and technologies to transfer extensive repositories of historical photographs and their contextual information into a three-dimensional spatial model, with an additional temporal component. This will make content accessible to researchers and the public, via a 4D browser as well as a location-dependent augmented reality representation. Against this background, this article highlights users and requirements of both scholarly and touristic usage of digital information about urban history, in particular historical photographs.

  @inbook{Münster2020, abstract = {The research group on four-dimensional research and communication of urban history (HistStadt4D) investigates and develops methods and technologies to transfer extensive repositories of historical photographs and their contextual information into a three-dimensional spatial model, with an additional temporal component. This will make content accessible to researchers and the public, via a 4D browser as well as a location-dependent augmented reality representation. Against this background, this article highlights users and requirements of both scholarly and touristic usage of digital information about urban history, in particular historical photographs.}, address = {Cham}, author = {Münster, Sander and Niebling, Florian and Bruschke, Jonas and Barthel, Kristina and Friedrichs, Kristina and Kröber, Cindy and Maiwald, Ferdinand}, booktitle = {Digital Cultural Heritage}, editor = {Kremers, Horst}, keywords = {histstadt4d}, pages = {63–84}, publisher = {Springer International Publishing}, title = {Urban History Research and Discovery in the Age of Digital Repositories. A Report About Users and Requirements}, year = 2020 }
• Simultaneous Run-Time Measurement of Motion-to-Photon Latency and Latency Jitter. Stauffert, Jan-Philipp; Niebling, Florian; Latoschik, Marc Erich. In 2020 IEEE Conference on Virtual Reality and 3D User Interfaces (VR), pp. 636–644. IEEE, 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{stauffert2020simultaneous, author = {Stauffert, Jan-Philipp and Niebling, Florian and Latoschik, Marc Erich}, booktitle = {2020 IEEE Conference on Virtual Reality and 3D User Interfaces (VR)}, keywords = {stauffert}, organization = {IEEE}, pages = {636–644}, title = {Simultaneous Run-Time Measurement of Motion-to-Photon Latency and Latency Jitter}, year = 2020 }
• Horde Battle III or How to Dismantle a Swarm. {Büttner}, Johannes; {Merz}, Christian; {von Mammen}, Sebastian. In 2020 IEEE Conference on Games (CoG), pp. 640–641. IEEE, Osaka, Japan, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In this demo paper, we present the design of a virtual reality (VR) first-person shooter (FPS) in which the player fends off waves of hostile flying swarm robots that took over the Earth. The purpose of this serious game is to train the player in understanding networks by learning how to dismantle them. We explain the play and game mechanics and the level designs tailored to provide an engaging experience and to re-enforce the network perspective of the swarm dynamics.

  @inproceedings{9231746, abstract = {In this demo paper, we present the design of a virtual reality (VR) first-person shooter (FPS) in which the player fends off waves of hostile flying swarm robots that took over the Earth. The purpose of this serious game is to train the player in understanding networks by learning how to dismantle them. We explain the play and game mechanics and the level designs tailored to provide an engaging experience and to re-enforce the network perspective of the swarm dynamics.}, address = {Osaka, Japan}, author = {{Büttner}, Johannes and {Merz}, Christian and {von Mammen}, Sebastian}, booktitle = {2020 IEEE Conference on Games (CoG)}, keywords = {myown}, pages = {640-641}, publisher = {IEEE}, title = {Horde Battle III or How to Dismantle a Swarm}, year = 2020 }
• Finally on Par?! Multimodal and Unimodal Interaction for Open Creative Design Tasks in Virtual Reality. Zimmerer, Chris; Wolf, Erik; Wolf, Sara; Fischbach, Martin; Lugrin, Jean-Luc; Latoschik, Marc Erich. In 2020 International Conference on Multimodal Interaction, pp. 222–231. Virtual Event, Netherlands, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Multimodal Interfaces (MMIs) have been considered to provide promising interaction paradigms for Virtual Reality (VR) for some time. However, they are still far less common than unimodal interfaces (UMIs). This paper presents a summative user study comparing an MMI to a typical UMI for a design task in VR. We developed an application targeting creative 3D object manipulations, i.e., creating 3D objects and modifying typical object properties such as color or size. The associated open user task is based on the Torrence Tests of Creative Thinking. We compared a synergistic multimodal interface using speech-accompanied pointing/grabbing gestures with a more typical unimodal interface using a hierarchical radial menu to trigger actions on selected objects. Independent judges rated the creativity of the resulting products using the Consensual Assessment Technique. Additionally, we measured the creativity-promoting factors flow, usability, and presence. Our results show that the MMI performs on par with the UMI in all measurements despite its limited flexibility and reliability. These promising results demonstrate the technological maturity of MMIs and their potential to extend traditional interaction techniques in VR efficiently.

  @inproceedings{10.1145/3382507.3418850, abstract = {Multimodal Interfaces (MMIs) have been considered to provide promising interaction paradigms for Virtual Reality (VR) for some time. However, they are still far less common than unimodal interfaces (UMIs). This paper presents a summative user study comparing an MMI to a typical UMI for a design task in VR. We developed an application targeting creative 3D object manipulations, i.e., creating 3D objects and modifying typical object properties such as color or size. The associated open user task is based on the Torrence Tests of Creative Thinking. We compared a synergistic multimodal interface using speech-accompanied pointing/grabbing gestures with a more typical unimodal interface using a hierarchical radial menu to trigger actions on selected objects. Independent judges rated the creativity of the resulting products using the Consensual Assessment Technique. Additionally, we measured the creativity-promoting factors flow, usability, and presence. Our results show that the MMI performs on par with the UMI in all measurements despite its limited flexibility and reliability. These promising results demonstrate the technological maturity of MMIs and their potential to extend traditional interaction techniques in VR efficiently.}, author = {Zimmerer, Chris and Wolf, Erik and Wolf, Sara and Fischbach, Martin and Lugrin, Jean-Luc and Latoschik, Marc Erich}, booktitle = {2020 International Conference on Multimodal Interaction}, keywords = {mmi}, note = {Best Paper Nominee 🏆}, pages = {222–231}, title = {Finally on Par?! Multimodal and Unimodal Interaction for Open Creative Design Tasks in Virtual Reality}, year = 2020 }
• Latency and Cybersickness: Impact, Causes, and Measures. A Review. Stauffert, Jan-Philipp; Niebling, Florian; Latoschik, Marc Erich. In Frontiers in Virtual Reality, 1, p. 31. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Latency is a key characteristic inherent to any computer system. Motion-to-Photon (MTP) latency describes the time between the movement of a tracked object and its corresponding movement rendered and depicted by computer-generated images on a graphical output screen. High MTP latency can cause a loss of performance in interactive graphics applications and, even worse, can provoke cybersickness in Virtual Reality (VR) applications. Here, cybersickness can degrade VR experiences or may render the experiences completely unusable. It can confound research findings of an otherwise sound experiment. Latency as a contributing factor to cybersickness needs to be properly understood. Its effects need to be analyzed, its sources need to be identified, good measurement methods need to be developed, and proper counter measures need to be developed in order to reduce potentially harmful impacts of latency on the usability and safety of VR systems. Research shows that latency can exhibit intricate timing patterns with various spiking and periodic behavior. These timing behaviors may vary, yet most are found to provoke cybersickness. Overall, latency can differ drastically between different systems interfering with generalization of measurement results. This review article describes the causes and effects of latency with regard to cybersickness. We report on different existing approaches to measure and report latency. Hence, the article provides readers with the knowledge to understand and report latency for their own applications, evaluations, and experiments. It should also help to measure, identify, and finally control and counteract latency and hence gain confidence into the soundness of empirical data collected by VR exposures. Low latency increases the usability and safety of VR systems.

  @article{stauffert:2020b, abstract = {Latency is a key characteristic inherent to any computer system. Motion-to-Photon (MTP) latency describes the time between the movement of a tracked object and its corresponding movement rendered and depicted by computer-generated images on a graphical output screen. High MTP latency can cause a loss of performance in interactive graphics applications and, even worse, can provoke cybersickness in Virtual Reality (VR) applications. Here, cybersickness can degrade VR experiences or may render the experiences completely unusable. It can confound research findings of an otherwise sound experiment. Latency as a contributing factor to cybersickness needs to be properly understood. Its effects need to be analyzed, its sources need to be identified, good measurement methods need to be developed, and proper counter measures need to be developed in order to reduce potentially harmful impacts of latency on the usability and safety of VR systems. Research shows that latency can exhibit intricate timing patterns with various spiking and periodic behavior. These timing behaviors may vary, yet most are found to provoke cybersickness. Overall, latency can differ drastically between different systems interfering with generalization of measurement results. This review article describes the causes and effects of latency with regard to cybersickness. We report on different existing approaches to measure and report latency. Hence, the article provides readers with the knowledge to understand and report latency for their own applications, evaluations, and experiments. It should also help to measure, identify, and finally control and counteract latency and hence gain confidence into the soundness of empirical data collected by VR exposures. Low latency increases the usability and safety of VR systems.}, author = {Stauffert, Jan-Philipp and Niebling, Florian and Latoschik, Marc Erich}, journal = {Frontiers in Virtual Reality}, keywords = {myown}, pages = 31, title = {Latency and Cybersickness: Impact, Causes, and Measures. A Review}, volume = 1, year = 2020 }
• Virtual Reality als Baustein in der Behandlung akuter und chronischer Schmerzen. Lindner, Stefan; Latoschik, Marc-Erich; Rittner, Heike. In AINS-An{ä}sthesiologie{\textperiodcentered} Intensivmedizin{\textperiodcentered} Notfallmedizin{\textperiodcentered} Schmerztherapie, 55(09), pp. 549–561. Georg Thieme Verlag KG, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Schmerzbehandlung zählt zu den täglichen Routinen klinischer Anästhesisten. Im Rahmen eines wohlüberlegten Einsatzes von Schmerzmedikamenten sind Alternativen zur medikamentösen Schmerztherapie notwendig. Virtual Reality (VR) konnte sich in den letzten Jahren durch immer kostengünstigere und bessere Technologien als realistische Ergänzung etablieren. Möglichkeiten der VR sowie Indikationen und Kontraindikationen werden aufgezeigt.

  @article{lindner2020virtual, abstract = {Schmerzbehandlung zählt zu den täglichen Routinen klinischer Anästhesisten. Im Rahmen eines wohlüberlegten Einsatzes von Schmerzmedikamenten sind Alternativen zur medikamentösen Schmerztherapie notwendig. Virtual Reality (VR) konnte sich in den letzten Jahren durch immer kostengünstigere und bessere Technologien als realistische Ergänzung etablieren. Möglichkeiten der VR sowie Indikationen und Kontraindikationen werden aufgezeigt.}, author = {Lindner, Stefan and Latoschik, Marc-Erich and Rittner, Heike}, journal = {AINS-An{\"a}sthesiologie{\textperiodcentered} Intensivmedizin{\textperiodcentered} Notfallmedizin{\textperiodcentered} Schmerztherapie}, keywords = {myown}, number = {09}, pages = {549–561}, publisher = {Georg Thieme Verlag KG}, title = {Virtual Reality als Baustein in der Behandlung akuter und chronischer Schmerzen}, volume = 55, year = 2020 }
• Teaching and Learning Processes in Immersive VR – Comparing Expectations of Preservice Teachers and Teacher Educators. Ripka, Gabriela; Tiede, Jennifer; Grafe, Silke; Latoschik, Marc Erich. In Society for Information Technology & Teacher Education (SITE) International Conference. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The usage of VR in higher education is not uncommon anymore. However, concepts are mainly still focusing on technical rather than pedagogical aspects of VR in the classroom. The exploration of the expectations of teacher educators as well as of preservice teachers appears indispensable (1) to achieve a sound understanding of requirements, (2) to identify potential design spaces, and finally (3) to create and to derive suitable pedagogical approaches for VR in initial teacher education. This paper presents results of guideline-based qualitative interviews comparing the expectations of teacher educators and of preservice teachers regarding teaching and learning in immersive virtual learning environments. The results showed that preservice teachers and teacher educators expect VR to enrich classes through interactive engagement in situations that would otherwise be too costly or dangerous. Regarding the design, teacher educators put the emphasis on functionality. Student teachers emphasized that they do not want to miss social interactions with their peers. Furthermore, both groups stated preferred modes of collaboration and interaction taking into account the characteristics of a virtual learning surrounding such as being able to use diverse learning spaces for group work. Interviewees agreed on two vital factors for effective learning and teaching processes: flexibility and the possibility of customization considering technical properties that are to deal with. Apart from this, preservice teachers emphasized strongly their worries about data usage and the ethics regarding using avatars and agents for representation.

  @inproceedings{ripka2020teaching, abstract = {The usage of VR in higher education is not uncommon anymore. However, concepts are mainly still focusing on technical rather than pedagogical aspects of VR in the classroom. The exploration of the expectations of teacher educators as well as of preservice teachers appears indispensable (1) to achieve a sound understanding of requirements, (2) to identify potential design spaces, and finally (3) to create and to derive suitable pedagogical approaches for VR in initial teacher education. This paper presents results of guideline-based qualitative interviews comparing the expectations of teacher educators and of preservice teachers regarding teaching and learning in immersive virtual learning environments. The results showed that preservice teachers and teacher educators expect VR to enrich classes through interactive engagement in situations that would otherwise be too costly or dangerous. Regarding the design, teacher educators put the emphasis on functionality. Student teachers emphasized that they do not want to miss social interactions with their peers. Furthermore, both groups stated preferred modes of collaboration and interaction taking into account the characteristics of a virtual learning surrounding such as being able to use diverse learning spaces for group work. Interviewees agreed on two vital factors for effective learning and teaching processes: flexibility and the possibility of customization considering technical properties that are to deal with. Apart from this, preservice teachers emphasized strongly their worries about data usage and the ethics regarding using avatars and agents for representation.}, author = {Ripka, Gabriela and Tiede, Jennifer and Grafe, Silke and Latoschik, Marc Erich}, booktitle = {Society for Information Technology & Teacher Education (SITE) International Conference}, keywords = {vilearn}, title = {Teaching and Learning Processes in Immersive VR – Comparing Expectations of Preservice Teachers and Teacher Educators}, year = 2020 }
• [DC] The Impact of Social Interactions on an Embodied Individual’s Self-perception in Virtual Environments. Mal, David. In 2020 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW), pp. 545–546. IEEE, Atlanta, GA, USA, USA, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In shared immersive virtual reality, users can interact with other participants and experience them as being present in the environment. Thereby different aspects of the respective interaction partners can have an impact on the perceived quality of the communication and possibly also the self-perception of an embodied user. This paper describes various factors the author aims to investigate during his doctoral studies. As the research area of embodied social interactions is broad, relevant factors and concrete research questions have been identified to investigate how social contact with one or multiple other persons may affect one’s self-perception, behavior and her or his relationship with the others while being embodied in a virtual environment.

  @conference{mal2020impact, abstract = {In shared immersive virtual reality, users can interact with other participants and experience them as being present in the environment. Thereby different aspects of the respective interaction partners can have an impact on the perceived quality of the communication and possibly also the self-perception of an embodied user. This paper describes various factors the author aims to investigate during his doctoral studies. As the research area of embodied social interactions is broad, relevant factors and concrete research questions have been identified to investigate how social contact with one or multiple other persons may affect one’s self-perception, behavior and her or his relationship with the others while being embodied in a virtual environment.}, address = {Atlanta, GA, USA, USA}, author = {Mal, David}, booktitle = {2020 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {vitras}, pages = {545-546}, publisher = {IEEE}, title = {[DC] The Impact of Social Interactions on an Embodied Individual’s Self-perception in Virtual Environments}, year = 2020 }
• An Overview of Design Patterns for Self-Adaptive Systems in the Context of the Internet of Things. Krupitzer, Christian; Temizer, Timur; Prantl, Thomas; Raibulet, Claudia. In IEEE Access. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  The Internet of Things (IoT) requires the integration of all available, highly specialized, and heterogeneous devices, ranging from embedded sensor nodes to servers in the cloud. The self-adaptive research domain provides adaptive capabilities that can support the integration in IoT systems. However, developing such systems is a challenging, error-prone, and time-consuming task. In this context, design patterns propose already used and optimized solutions to specific problems in various contexts. Applying design patterns might help to reuse existing knowledge about similar development issues. However, so far, there is a lack of taxonomies on design patterns for self-adaptive systems. To tackle this issue, in this paper, we provide a taxonomy on design patterns for self-adaptive systems that can be transferred to support adaptivity in IoT systems. Besides describing the taxonomy and the design patterns, we discuss their applicability in an Industrial IoT case study.

  @article{ieeeaccess2020:sasdesignpatterns, abstract = {The Internet of Things (IoT) requires the integration of all available, highly specialized, and heterogeneous devices, ranging from embedded sensor nodes to servers in the cloud. The self-adaptive research domain provides adaptive capabilities that can support the integration in IoT systems. However, developing such systems is a challenging, error-prone, and time-consuming task. In this context, design patterns propose already used and optimized solutions to specific problems in various contexts. Applying design patterns might help to reuse existing knowledge about similar development issues. However, so far, there is a lack of taxonomies on design patterns for self-adaptive systems. To tackle this issue, in this paper, we provide a taxonomy on design patterns for self-adaptive systems that can be transferred to support adaptivity in IoT systems. Besides describing the taxonomy and the design patterns, we discuss their applicability in an Industrial IoT case study.}, author = {Krupitzer, Christian and Temizer, Timur and Prantl, Thomas and Raibulet, Claudia}, journal = {IEEE Access}, keywords = {self-adaptive-systems}, title = {An Overview of Design Patterns for Self-Adaptive Systems in the Context of the Internet of Things}, year = 2020 }
• Guided Sine Fitting for Latency Estimation in Virtual Reality. Stauffert, Jan-Philipp; Niebling, Florian; Lugrin, Jean-Luc; Latoschik, Marc Erich. In 2020 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW), pp. 707–708. IEEE, 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{stauffert2020guided, author = {Stauffert, Jan-Philipp and Niebling, Florian and Lugrin, Jean-Luc and Latoschik, Marc Erich}, booktitle = {2020 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {Stauffer}, organization = {IEEE}, pages = {707–708}, title = {Guided Sine Fitting for Latency Estimation in Virtual Reality}, year = 2020 }
• Angle Covers: Algorithms and Complexity. Evans, William; Gethner, Ellen; Spalding-Jamieson, Jack; Wolff, Alexander. In Proc. 14th Int. Workshop Algorithms Comput. (WALCOM’20), Vol. 12049 of Lecture Notes in Computer Science, S. Rahman, K. Sadakane, W.-K. Sung (eds.), pp. 94–106. Springer-Verlag, 2020.
  • [ BibTeX ]
  @inproceedings{egsw-acac-WALCOM20, author = {Evans, William and Gethner, Ellen and Spalding-Jamieson, Jack and Wolff, Alexander}, booktitle = {Proc. 14th Int. Workshop Algorithms Comput. (WALCOM'20)}, editor = {Rahman, Sohel and Sadakane, Kunihiko and Sung, Wing-Kin}, keywords = {myown}, pages = {94–106}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Angle Covers: Algorithms and Complexity}, volume = 12049, year = 2020 }
• Metachron: A framework for time perception research in VR. Landeck, Maximilian; Unruh, Fabian; Lugrin, Jean-Luc; Latoschik, Marc Erich. In Proceedings of the 26th ACM Conference on Virtual Reality Software and Technology. 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Landeck2020Metachron, author = {Landeck, Maximilian and Unruh, Fabian and Lugrin, Jean-Luc and Latoschik, Marc Erich}, booktitle = {Proceedings of the 26th ACM Conference on Virtual Reality Software and Technology}, keywords = {vrst19}, title = {Metachron: A framework for time perception research in VR}, year = 2020 }
• The impact of the German strategy for containment of Coronavirus SARS-CoV-2 on the training characteristics, physical activity, sleep of highly trained kayakers and canoeists: A retrospective observational study. Zinner, Christoph; Matzka, Manuel; Leppich, Robert; Kounev, Samuel; Holmberg, HC; Sperlich, Billy. In Frontiers in Sports and Active Living, 2, p. 127. Frontiers, 2020.
  • [ BibTeX ]
  @article{zinner2020impact, author = {Zinner, Christoph and Matzka, Manuel and Leppich, Robert and Kounev, Samuel and Holmberg, HC and Sperlich, Billy}, journal = {Frontiers in Sports and Active Living}, keywords = {covid19}, pages = 127, publisher = {Frontiers}, title = {The impact of the German strategy for containment of Coronavirus SARS-CoV-2 on the training characteristics, physical activity, sleep of highly trained kayakers and canoeists: A retrospective observational study}, volume = 2, year = 2020 }
• Self-organizing knowledge management might improve the quality of person-centered dementia care: A qualitative study. Gall, Dominik; Preßler, Jan; Hurtienne, Jörn; Latoschik, Marc Erich. In International Journal of Medical Informatics, 139, p. 104132. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Background: In institutional dementia care, person-centered care improves care processes and the quality of life of residents. However, communication gaps impede the implementation of person-centered care in favor of routinized care. Objective: We evaluated whether self-organizing knowledge management reduces communication gaps and improves the quality of person-centered dementia care. Method: We implemented a self-organizing knowledge management system. Eight significant others of residents with severe dementia and six professional caregivers used a mobile application for six months. We conducted qualitative interviews and focus groups afterward. Main findings: Participants reported that the system increased the quality of person-centered care, reduced communication gaps, increased the task satisfaction of caregivers and the wellbeing of significant others. Conclusions: Based on our findings, we develop the following hypotheses: Self-organizing knowledge management might provide a promising tool to improve the quality of person-centered care. It might reduce communication barriers that impede person-centered care. It might allow transferring content-maintaining tasks from caregivers to significant others. Such distribution of tasks, in turn, might be beneficial for both parties. Furthermore, shared knowledge about situational features might guide person-centered interventions.

  @article{gall2020selforganizing, abstract = {Background: In institutional dementia care, person-centered care improves care processes and the quality of life of residents. However, communication gaps impede the implementation of person-centered care in favor of routinized care. Objective: We evaluated whether self-organizing knowledge management reduces communication gaps and improves the quality of person-centered dementia care. Method: We implemented a self-organizing knowledge management system. Eight significant others of residents with severe dementia and six professional caregivers used a mobile application for six months. We conducted qualitative interviews and focus groups afterward. Main findings: Participants reported that the system increased the quality of person-centered care, reduced communication gaps, increased the task satisfaction of caregivers and the wellbeing of significant others. Conclusions: Based on our findings, we develop the following hypotheses: Self-organizing knowledge management might provide a promising tool to improve the quality of person-centered care. It might reduce communication barriers that impede person-centered care. It might allow transferring content-maintaining tasks from caregivers to significant others. Such distribution of tasks, in turn, might be beneficial for both parties. Furthermore, shared knowledge about situational features might guide person-centered interventions.}, author = {Gall, Dominik and Preßler, Jan and Hurtienne, Jörn and Latoschik, Marc Erich}, journal = {International Journal of Medical Informatics}, keywords = {myown}, pages = 104132, title = {Self-organizing knowledge management might improve the quality of person-centered dementia care: A qualitative study}, volume = 139, year = 2020 }
• A Low-Cost Approach to Fish Tank Virtual Reality with Semi-Automatic Calibration Support. Wißmann, Niko; Misiak, Martin; Fuhrmann, Arnulph; Latoschik, Marc Erich. In VR Workshops, pp. 599–600. IEEE, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  We describe the components and implementation of a cost-effective fish tank virtual reality system. It is based on commodity hardware and provides accurate view tracking combined with high resolution stereoscopic rendering. The system is calibrated very quickly in a semi-automatic step using computer vision. By avoiding the resolution disadvantages of current VR headsets, our prototype is suitable for a wide range of perceptual VR studies.

  @inproceedings{conf/vr/WissmannMFL20a, abstract = {We describe the components and implementation of a cost-effective fish tank virtual reality system. It is based on commodity hardware and provides accurate view tracking combined with high resolution stereoscopic rendering. The system is calibrated very quickly in a semi-automatic step using computer vision. By avoiding the resolution disadvantages of current VR headsets, our prototype is suitable for a wide range of perceptual VR studies.}, author = {Wißmann, Niko and Misiak, Martin and Fuhrmann, Arnulph and Latoschik, Marc Erich}, booktitle = {VR Workshops}, crossref = {conf/vr/2020w}, keywords = {hci-uwb}, pages = {599-600}, publisher = {IEEE}, title = {A Low-Cost Approach to Fish Tank Virtual Reality with Semi-Automatic Calibration Support.}, year = 2020 }
• Accelerated Stereo Rendering with Hybrid Reprojection-Based Rasterization and Adaptive Ray-Tracing. Wißmann, Niko; Mišiak, Martin; Fuhrmann, Arnulph; Latoschik, Marc Erich. In Proceedings of the 27th IEEE Virtual Reality conference (IEEE VR ’20). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Stereoscopic rendering is a prominent feature of virtual reality applications to generate depth cues and to provide depth perception in the virtual world. However, straight-forward stereo rendering methods usually are expensive since they render the scene from two eye-points which in general doubles the frame times. This is particularly problematic since virtual reality sets high requirements for real-time capabilities and image resolution. Hence, this paper presents a hybrid rendering system that combines classic rasteriza- tion and real-time ray-tracing to accelerate stereoscopic rendering. The system reprojects the pre-rendered left half of the stereo image pair into the right perspective using a forward grid warping technique and identifies resulting reprojection errors, which are then efficiently resolved by adaptive real-time ray-tracing. A final analysis shows that the system achieves a significant performance gain, has a neg- ligible quality impact, and is suitable even for higher rendering resolutions.

  @inproceedings{wissmann2020accelerated, abstract = {Stereoscopic rendering is a prominent feature of virtual reality applications to generate depth cues and to provide depth perception in the virtual world. However, straight-forward stereo rendering methods usually are expensive since they render the scene from two eye-points which in general doubles the frame times. This is particularly problematic since virtual reality sets high requirements for real-time capabilities and image resolution. Hence, this paper presents a hybrid rendering system that combines classic rasteriza- tion and real-time ray-tracing to accelerate stereoscopic rendering. The system reprojects the pre-rendered left half of the stereo image pair into the right perspective using a forward grid warping technique and identifies resulting reprojection errors, which are then efficiently resolved by adaptive real-time ray-tracing. A final analysis shows that the system achieves a significant performance gain, has a neg- ligible quality impact, and is suitable even for higher rendering resolutions.}, author = {Wißmann, Niko and Mišiak, Martin and Fuhrmann, Arnulph and Latoschik, Marc Erich}, booktitle = {Proceedings of the 27th IEEE Virtual Reality conference (IEEE VR '20)}, keywords = {myown}, note = {Best paper award 🏆}, title = {Accelerated Stereo Rendering with Hybrid Reprojection-Based Rasterization and Adaptive Ray-Tracing}, year = 2020 }
• What if it speaks like it was from the village? Effects of a Robot speaking in Regional Language Variations on Users’ Evaluations. Lugrin, B.; Ströle, E.; Obremski, D.; Schwab, F.; Lange, B. In 29th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN 2020), pp. 1315–1320. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The present contribution investigates the effects of spoken language varieties, in particular non-standard / regional language compared to standard language (in our study: High German), in social robotics. Based on (media) psychological and sociolinguistic research, we assumed that a robot speaking in regional language (i.e., dialect and regional accent) would be considered less competent compared to the same robot speaking in standard language (H1). Contrarily, we assumed that regional language might enhance perceived social skills and likability of a robot, at least so when taking into account whether and how much the human observers making the evaluations talk in regional language themselves. More precisely, it was assumed that the more the study participants spoke in regional language, the better their ratings of the dialect-speaking robot on social skills and likeability would be (H2). We also investigated whether the robot’s gender (male vs. female voice) would have an effect on the ratings (RQ). H1 received full, H2 limited empirical support by the data, while the robot’s gender (RQ) turned out to be a mostly negligible factor. Based on our results, practical implications for robots speaking in regional language varieties are suggested.

  @inproceedings{9223432, abstract = {The present contribution investigates the effects of spoken language varieties, in particular non-standard / regional language compared to standard language (in our study: High German), in social robotics. Based on (media) psychological and sociolinguistic research, we assumed that a robot speaking in regional language (i.e., dialect and regional accent) would be considered less competent compared to the same robot speaking in standard language (H1). Contrarily, we assumed that regional language might enhance perceived social skills and likability of a robot, at least so when taking into account whether and how much the human observers making the evaluations talk in regional language themselves. More precisely, it was assumed that the more the study participants spoke in regional language, the better their ratings of the dialect-speaking robot on social skills and likeability would be (H2). We also investigated whether the robot’s gender (male vs. female voice) would have an effect on the ratings (RQ). H1 received full, H2 limited empirical support by the data, while the robot’s gender (RQ) turned out to be a mostly negligible factor. Based on our results, practical implications for robots speaking in regional language varieties are suggested.}, author = {Lugrin, B. and Ströle, E. and Obremski, D. and Schwab, F. and Lange, B.}, booktitle = {29th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN 2020)}, keywords = {reflectedreality}, pages = {1315-1320}, title = {What if it speaks like it was from the village? Effects of a Robot speaking in Regional Language Variations on Users’ Evaluations}, year = 2020 }
• Construction of the Virtual Embodiment Questionnaire (VEQ). Roth, Daniel; Latoschik, Marc Erich. In IEEE Transactions on Visualization and Computer Graphics (TVCG), 26(12), pp. 3546–3556. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  User embodiment is important for many virtual reality (VR) applications, for example, in the context of social interaction, therapy, training, or entertainment. However, there is no data-driven and validated instrument to empirically measure the perceptual aspects of embodiment, necessary to reliably evaluate this important phenomenon. To provide a method to assess components of virtual embodiment in a reliable and consistent fashion, we constructed a Virtual Embodiment Questionnaire (VEQ). We reviewed previous literature to identify applicable constructs and questionnaire items, and performed a confirmatory factor analysis (CFA) on the data from three experiments (N = 196). The analysis confirmed three factors: (1) ownership of a virtual body, (2) agency over a virtual body, and (3) the perceived change in the body schema. A fourth study (N = 22) was conducted to confirm the reliability and validity of the scale, by investigating the impacts of latency and latency jitter present in the simulation. We present the proposed scale and study results and discuss resulting implications.

  @article{9199571, abstract = {User embodiment is important for many virtual reality (VR) applications, for example, in the context of social interaction, therapy, training, or entertainment. However, there is no data-driven and validated instrument to empirically measure the perceptual aspects of embodiment, necessary to reliably evaluate this important phenomenon. To provide a method to assess components of virtual embodiment in a reliable and consistent fashion, we constructed a Virtual Embodiment Questionnaire (VEQ). We reviewed previous literature to identify applicable constructs and questionnaire items, and performed a confirmatory factor analysis (CFA) on the data from three experiments (N = 196). The analysis confirmed three factors: (1) ownership of a virtual body, (2) agency over a virtual body, and (3) the perceived change in the body schema. A fourth study (N = 22) was conducted to confirm the reliability and validity of the scale, by investigating the impacts of latency and latency jitter present in the simulation. We present the proposed scale and study results and discuss resulting implications.}, author = {Roth, Daniel and Latoschik, Marc Erich}, journal = {IEEE Transactions on Visualization and Computer Graphics (TVCG)}, keywords = {myown}, number = 12, pages = {3546-3556}, title = {Construction of the Virtual Embodiment Questionnaire (VEQ)}, volume = 26, year = 2020 }
• Drawing Graphs with Circular Arcs and Right-Angle Crossings. Chaplick, Steven; Förster, Henry; Kryven, Myroslav; Wolff, Alexander. In Proc. 17th Scand. Symp. and Workshops on Algorithm Theory (SWAT’20), Vol. 162 of LIPIcs, S. Albers (ed.), pp. 21:1–14. Schloss Dagstuhl – Leibniz-Zentrum für Informatik, 2020.
  • [ BibTeX ]
  @inproceedings{cfkw-dgcar-SWAT20, author = {Chaplick, Steven and Förster, Henry and Kryven, Myroslav and Wolff, Alexander}, booktitle = {Proc. 17th Scand. Symp. and Workshops on Algorithm Theory (SWAT'20)}, editor = {Albers, Susanne}, keywords = {charging_argument}, pages = {21:1–14}, publisher = {Schloss Dagstuhl – Leibniz-Zentrum für Informatik}, series = {LIPIcs}, title = {Drawing Graphs with Circular Arcs and Right-Angle Crossings}, volume = 162, year = 2020 }
• Predicting Performance Degradations of Black-box Microservice Applications. Straesser, Martin. 2020.
  • [ BibTeX ]
  • [ URL ]
  @presentation{straesser2020talk, author = {Straesser, Martin}, keywords = {performance_prediction}, title = {Predicting Performance Degradations of Black-box Microservice Applications}, year = 2020 }
• Autofahren der Zukunft: Autonom, vernetzt, gefährlich?. Herrnleben, Stefan; Krupitzer, Christian. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Tesla, Google / Waymo und diverse Automobilhersteller haben gezeigt, dass autonomes Fahren von Autos keine Science Fiction mehr ist. Die Forschung in diesem Bereich versucht das volle Potenzial der Automatisierung durch Vernetzung der Fahrzeuge zu erreichen. In diesem (nicht zu technischem) Vortrag wird der aktuelle Stand der Entwicklung im Bereich autonomen Fahrens vorgestellt, das Potenzial der Technologie in Kombination mit Kommunikation der Fahrzeuge anhand von Fallstudien betrachtet sowie Gefahrenquellen diskutiert.

  @presentation{HeKr2020-UBiZ-Autofahren, abstract = {Tesla, Google / Waymo und diverse Automobilhersteller haben gezeigt, dass autonomes Fahren von Autos keine Science Fiction mehr ist. Die Forschung in diesem Bereich versucht das volle Potenzial der Automatisierung durch Vernetzung der Fahrzeuge zu erreichen. In diesem (nicht zu technischem) Vortrag wird der aktuelle Stand der Entwicklung im Bereich autonomen Fahrens vorgestellt, das Potenzial der Technologie in Kombination mit Kommunikation der Fahrzeuge anhand von Fallstudien betrachtet sowie Gefahrenquellen diskutiert.}, author = {Herrnleben, Stefan and Krupitzer, Christian}, keywords = {myown}, title = {Autofahren der Zukunft: Autonom, vernetzt, gefährlich?}, year = 2020 }
• A Taxonomy of Techniques for SLO Failure Prediction in Software Systems. Grohmann, Johannes; Herbst, Nikolas; Chalbani, Avi; Arian, Yair; Peretz, Noam; Kounev, Samuel. In Computers, 9(1), p. 10. Multidisciplinary Digital Publishing Institute (MDPI), 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Failure prediction is an important aspect of self-aware computing systems. Therefore, a multitude of different approaches has been proposed in the literature over the past few years. In this work, we propose a taxonomy for organizing works focusing on the prediction of Service Level Objective (SLO) failures. Our taxonomy classifies related work along the dimensions of the prediction target (e.g., anomaly detection, performance prediction, or failure prediction), the time horizon (e.g., detection or prediction, online or offline application), and the applied modeling type (e.g., time series forecasting, machine learning, or queueing theory). The classification is derived based on a systematic mapping of relevant papers in the area. Additionally, we give an overview of different techniques in each sub-group and address remaining challenges in order to guide future research.

  @article{grohmann2020-MDPI-taxonomy, abstract = {Failure prediction is an important aspect of self-aware computing systems. Therefore, a multitude of different approaches has been proposed in the literature over the past few years. In this work, we propose a taxonomy for organizing works focusing on the prediction of Service Level Objective (SLO) failures. Our taxonomy classifies related work along the dimensions of the prediction target (e.g., anomaly detection, performance prediction, or failure prediction), the time horizon (e.g., detection or prediction, online or offline application), and the applied modeling type (e.g., time series forecasting, machine learning, or queueing theory). The classification is derived based on a systematic mapping of relevant papers in the area. Additionally, we give an overview of different techniques in each sub-group and address remaining challenges in order to guide future research.}, author = {Grohmann, Johannes and Herbst, Nikolas and Chalbani, Avi and Arian, Yair and Peretz, Noam and Kounev, Samuel}, journal = {Computers}, keywords = {automated_model_learning}, number = 1, pages = 10, publisher = {Multidisciplinary Digital Publishing Institute (MDPI)}, title = {A Taxonomy of Techniques for SLO Failure Prediction in Software Systems}, volume = 9, year = 2020 }
• Drawing Graphs on Few Lines and Few Planes. Chaplick, Steven; Fleszar, Krzysztof; Lipp, Fabian; Ravsky, Alexander; Verbitsky, Oleg; Wolff, Alexander. In Journal of Computational Geometry, 11(1), pp. 433–475. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  We investigate the problem of drawing graphs in 2D and 3D such that their edges (or only their vertices) can be covered by few lines or planes. We insist on straight-line edges and crossing-free drawings. This problem has many relations to other challenging graph-drawing problems such as small-area or small-volume drawings, layered or track drawings, and drawing graphs with low visual complexity. While some facts about our problem are implicit in previous work, this is the first treatment of the problem in its full generality. Our contribution is as follows. \par We show lower and upper bounds for the numbers of lines and planes needed for covering drawings of graphs in certain graph classes. In some cases our bounds are asymptotically tight; in some cases we are able to determine exact values. \par We relate our parameters to standard combinatorial characteristics of graphs (such as the chromatic number, treewidth, or arboricity) and to parameters that have been studied in graph drawing (such as the track number or the number of segments appearing in a drawing). \par We pay special attention to planar graphs. For example, we show that there are qplanar graphs that can be drawn in 3-space on asymptotically fewer lines than in the plane.

  @article{cflrvw-dgflf-JoCG20, abstract = {We investigate the problem of drawing graphs in 2D and 3D such that their edges (or only their vertices) can be covered by few lines or planes. We insist on straight-line edges and crossing-free drawings. This problem has many relations to other challenging graph-drawing problems such as small-area or small-volume drawings, layered or track drawings, and drawing graphs with low visual complexity. While some facts about our problem are implicit in previous work, this is the first treatment of the problem in its full generality. Our contribution is as follows. \par We show lower and upper bounds for the numbers of lines and planes needed for covering drawings of graphs in certain graph classes. In some cases our bounds are asymptotically tight; in some cases we are able to determine exact values. \par We relate our parameters to standard combinatorial characteristics of graphs (such as the chromatic number, treewidth, or arboricity) and to parameters that have been studied in graph drawing (such as the track number or the number of segments appearing in a drawing). \par We pay special attention to planar graphs. For example, we show that there are qplanar graphs that can be drawn in 3-space on asymptotically fewer lines than in the plane.}, author = {Chaplick, Steven and Fleszar, Krzysztof and Lipp, Fabian and Ravsky, Alexander and Verbitsky, Oleg and Wolff, Alexander}, journal = {Journal of Computational Geometry}, keywords = {affine_cover_number}, number = 1, pages = {433–475}, title = {Drawing Graphs on Few Lines and Few Planes}, volume = 11, year = 2020 }
• SIMPL: Secure IoT Management Platform. Prantl, Thomas; Ben Yahya, Ala Eddine; Dmitrienko, Alexandra; Kounev, Samuel; Lipp, Fabian; Hock, David; Rathfelder, Christoph; Hofherr, Martin. In ITG Workshop on IT Security (ITSec). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  The proliferation of IoT devices is increasing at a fast pace, whether for private or business use. However,despite their growing popularity, their safe operation is often not guaranteed. To tackle the security challenges of modern IoT environments, the German Federal Ministry of Education and Research is funding the SIMPL project in order to support research in this area. The contribution of this paper is to introduce the main goal, objectives, and key features of SIMPL

  @inproceedings{PrYaDmKoLiHoRaHo2020-ITSec-SIMPL, abstract = {The proliferation of IoT devices is increasing at a fast pace, whether for private or business use. However,despite their growing popularity, their safe operation is often not guaranteed. To tackle the security challenges of modern IoT environments, the German Federal Ministry of Education and Research is funding the SIMPL project in order to support research in this area. The contribution of this paper is to introduce the main goal, objectives, and key features of SIMPL}, author = {Prantl, Thomas and Ben Yahya, Ala Eddine and Dmitrienko, Alexandra and Kounev, Samuel and Lipp, Fabian and Hock, David and Rathfelder, Christoph and Hofherr, Martin}, booktitle = {ITG Workshop on IT Security (ITSec)}, keywords = {t_workshop}, title = {SIMPL: Secure IoT Management Platform}, year = 2020 }
• The Complexity of Finding Tangles. Firman, Oksana; Felsner, Stefan; Kindermann, Philipp; Ravsky, Alexander; Wolff, Alexander; Zink, Johannes. In Proceedings of the 28th International Symposium on Graph Drawing and Network Visualization (GD’20), D. Auber, P. Valtr (eds.). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  We study the following combinatorial problem. Given a set of n y-monotone curves, which we call wires, a tangle determines the order of the wires on a number of horizontal layers such that the orders of the wires on any two consecutive layers differ only in swaps of neighboring wires. Given a multiset L of swaps (that is, unordered pairs of wires) and an initial order of the wires, a tangle realizes L if each pair of wires changes its order exactly as many times as specified by L. Finding a tangle that realizes a given multiset of swaps and uses the least number of layers is known to be NP-hard. We show that it is even NP-hard to decide if a realizing tangle exists.

  @inproceedings{ffkrwz-tcft-gd20poster, abstract = {We study the following combinatorial problem. Given a set of n y-monotone curves, which we call wires, a tangle determines the order of the wires on a number of horizontal layers such that the orders of the wires on any two consecutive layers differ only in swaps of neighboring wires. Given a multiset L of swaps (that is, unordered pairs of wires) and an initial order of the wires, a tangle realizes L if each pair of wires changes its order exactly as many times as specified by L. Finding a tangle that realizes a given multiset of swaps and uses the least number of layers is known to be NP-hard. We show that it is even NP-hard to decide if a realizing tangle exists.}, author = {Firman, Oksana and Felsner, Stefan and Kindermann, Philipp and Ravsky, Alexander and Wolff, Alexander and Zink, Johannes}, booktitle = {Proceedings of the 28th International Symposium on Graph Drawing and Network Visualization (GD'20)}, editor = {Auber, David and Valtr, Pavel}, keywords = {myown}, note = {Poster. To appear}, title = {The Complexity of Finding Tangles}, year = 2020 }
• One-Bend Drawings of Outerplanar Graphs Inside Simple Polygons. Angelini, Patrizio; Kindermann, Philipp; Löffler, Andre; Schlipf, Lena; Symvonis, Antonios. In Proceedings of the 36th European Workshop on Computational Geometry (EuroCG’20), S. Chaplick, P. Kindermann, A. Wolff (eds.), pp. 70:1–70:6. Würzburg, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  We consider the problem of drawing an outerplanar graph with n vertices with at most one bend per edge if the outer face is already drawn as a simple polygon with m corners. We prove that it can be decided in O(mn) time if such a drawing exists. In the positive case, our algorithm also outputs such a drawing.

  @inproceedings{aklss-obdog-eurocg20, abstract = {We consider the problem of drawing an outerplanar graph with n vertices with at most one bend per edge if the outer face is already drawn as a simple polygon with m corners. We prove that it can be decided in O(mn) time if such a drawing exists. In the positive case, our algorithm also outputs such a drawing.}, author = {Angelini, Patrizio and Kindermann, Philipp and Löffler, Andre and Schlipf, Lena and Symvonis, Antonios}, booktitle = {Proceedings of the 36th European Workshop on Computational Geometry (EuroCG'20)}, editor = {Chaplick, Steven and Kindermann, Philipp and Wolff, Alexander}, keywords = {myown}, note = {Abstract}, pages = {70:1–70:6}, publisher = {Würzburg}, title = {One-Bend Drawings of Outerplanar Graphs Inside Simple Polygons}, year = 2020 }
• Towards Predicting the Subscription Status of Twitch.tv Users. Kobs, Konstantin; Potthast, Martin; Wiegmann, Matti; Zehe, Albin; Stein, Benno; Hotho, Andreas. In Proceedings of ECML-PKDD 2020 ChAT Discovery Challenge on Chat Analytics for Twitch. 2020.
  • [ BibTeX ]
  • [ URL ]
  @article{kobs2020towards, author = {Kobs, Konstantin and Potthast, Martin and Wiegmann, Matti and Zehe, Albin and Stein, Benno and Hotho, Andreas}, journal = {Proceedings of ECML-PKDD 2020 ChAT Discovery Challenge on Chat Analytics for Twitch}, keywords = 2020, title = {Towards Predicting the Subscription Status of Twitch.tv Users}, year = 2020 }
• Deep Learning for Climate Model Output Statistics. Steininger, Michael; Abel, Daniel; Ziegler, Katrin; Krause, Anna; Paeth, Heiko; Hotho, Andreas. In Tackling Climate Change with Machine Learning Workshop at NeurIPS 2020. 2020.
  • [ BibTeX ]
  • [ URL ]
  @article{steininger2020learning, author = {Steininger, Michael and Abel, Daniel and Ziegler, Katrin and Krause, Anna and Paeth, Heiko and Hotho, Andreas}, journal = {Tackling Climate Change with Machine Learning Workshop at NeurIPS 2020}, keywords = 2020, title = {Deep Learning for Climate Model Output Statistics}, year = 2020 }
• Machine Learning and Knowledge Discovery in Databases - European Conference, ECML PKDD 2019, Würzburg, Germany, September 16-20, 2019, Proceedings, Part I. Brefeld, Ulf; Fromont, Élisa; Hotho, Andreas; Knobbe, Arno J.; Maathuis, Marloes H.; Robardet, Céline. In Vol. 11906 of Lecture Notes in Computer Science. Springer, 2020.
  • [ BibTeX ]
  • [ URL ]
  @proceedings{brefeld2020machine3, booktitle = {ECML/PKDD (1)}, editor = {Brefeld, Ulf and Fromont, Élisa and Hotho, Andreas and Knobbe, Arno J. and Maathuis, Marloes H. and Robardet, Céline}, keywords = 2020, publisher = {Springer}, series = {Lecture Notes in Computer Science}, title = {Machine Learning and Knowledge Discovery in Databases - European Conference, ECML PKDD 2019, Würzburg, Germany, September 16-20, 2019, Proceedings, Part I}, volume = 11906, year = 2020 }
• {Beyond Microbenchmarks: The SPEC-RG Vision for A Comprehensive Serverless Benchmark}. van Eyk, Erwin; Scheuner, Joel; Eismann, Simon; Abad, Cristina; Iosup, Alexandru. In Companion of the 2020 ACM/SPEC International Conference on Performance Engineering. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Serverless computing services, such as Function-as-a-Service (FaaS), hold the attractive promise of a high level of abstraction and high performance, combined with the minimization of operational logic. Several large ecosystems of serverless platforms, both open- and closed-source, aim to realize this promise. Consequently, a lucrative market has emerged. However, the performance trade-offs of these systems are not well-understood. Moreover, it is exactly the high level of abstraction and the opaqueness of the operational-side that make performance evaluation studies of serverless platforms challenging. Learning from the history of IT platforms, we argue that a benchmark for serverless platforms could help address this challenge. We envision a comprehensive serverless benchmark, which we contrast to the narrow focus of prior work in this area. We argue that a comprehensive benchmark will need to take into account more than just runtime overhead, and include notions of cost, realistic workloads, more (open-source) platforms, and cloud integrations. Finally, we show through preliminary real-world experiments how such a benchmark can help compare the performance overhead when running a serverless workload on state-of-the-art platforms.

  @inproceedings{10.1145/3185768.3186293, abstract = {Serverless computing services, such as Function-as-a-Service (FaaS), hold the attractive promise of a high level of abstraction and high performance, combined with the minimization of operational logic. Several large ecosystems of serverless platforms, both open- and closed-source, aim to realize this promise. Consequently, a lucrative market has emerged. However, the performance trade-offs of these systems are not well-understood. Moreover, it is exactly the high level of abstraction and the opaqueness of the operational-side that make performance evaluation studies of serverless platforms challenging. Learning from the history of IT platforms, we argue that a benchmark for serverless platforms could help address this challenge. We envision a comprehensive serverless benchmark, which we contrast to the narrow focus of prior work in this area. We argue that a comprehensive benchmark will need to take into account more than just runtime overhead, and include notions of cost, realistic workloads, more (open-source) platforms, and cloud integrations. Finally, we show through preliminary real-world experiments how such a benchmark can help compare the performance overhead when running a serverless workload on state-of-the-art platforms.}, author = {van Eyk, Erwin and Scheuner, Joel and Eismann, Simon and Abad, Cristina and Iosup, Alexandru}, booktitle = {Companion of the 2020 ACM/SPEC International Conference on Performance Engineering}, keywords = {SPEC}, title = {{Beyond Microbenchmarks: The SPEC-RG Vision for A Comprehensive Serverless Benchmark}}, year = 2020 }
• Drawing Graphs on Few Lines and Few Planes. Chaplick, Steven; Fleszar, Krzysztof; Lipp, Fabian; Ravsky, Alexander; Verbitsky, Oleg; Wolff, Alexander. In Journal of Computational Geometry, 11(1), pp. 433–475. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  We investigate the problem of drawing graphs in 2D and 3D such that their edges (or only their vertices) can be covered by few lines or planes. We insist on straight-line edges and crossing-free drawings. This problem has many relations to other challenging graph-drawing problems such as small-area or small-volume drawings, layered or track drawings, and drawing graphs with low visual complexity. While some facts about our problem are implicit in previous work, this is the first treatment of the problem in its full generality. Our contribution is as follows. \par We show lower and upper bounds for the numbers of lines and planes needed for covering drawings of graphs in certain graph classes. In some cases our bounds are asymptotically tight; in some cases we are able to determine exact values. \par We relate our parameters to standard combinatorial characteristics of graphs (such as the chromatic number, treewidth, or arboricity) and to parameters that have been studied in graph drawing (such as the track number or the number of segments appearing in a drawing). \par We pay special attention to planar graphs. For example, we show that there are qplanar graphs that can be drawn in 3-space on asymptotically fewer lines than in the plane.

  @article{cflrvw-dgflf-JoCG20, abstract = {We investigate the problem of drawing graphs in 2D and 3D such that their edges (or only their vertices) can be covered by few lines or planes. We insist on straight-line edges and crossing-free drawings. This problem has many relations to other challenging graph-drawing problems such as small-area or small-volume drawings, layered or track drawings, and drawing graphs with low visual complexity. While some facts about our problem are implicit in previous work, this is the first treatment of the problem in its full generality. Our contribution is as follows. \par We show lower and upper bounds for the numbers of lines and planes needed for covering drawings of graphs in certain graph classes. In some cases our bounds are asymptotically tight; in some cases we are able to determine exact values. \par We relate our parameters to standard combinatorial characteristics of graphs (such as the chromatic number, treewidth, or arboricity) and to parameters that have been studied in graph drawing (such as the track number or the number of segments appearing in a drawing). \par We pay special attention to planar graphs. For example, we show that there are qplanar graphs that can be drawn in 3-space on asymptotically fewer lines than in the plane.}, author = {Chaplick, Steven and Fleszar, Krzysztof and Lipp, Fabian and Ravsky, Alexander and Verbitsky, Oleg and Wolff, Alexander}, journal = {Journal of Computational Geometry}, keywords = {affine_cover_number}, number = 1, pages = {433–475}, title = {Drawing Graphs on Few Lines and Few Planes}, volume = 11, year = 2020 }
• Finding Optimal Sequences for Area Aggregation---{A}* vs.\ Integer Linear Programming. Peng, Dongliang; Wolff, Alexander; Haunert, Jan-Henrik. In ACM Transactions on Spatial Algorithms and Systems, 7(1). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  To provide users with maps of different scales and to allow them to zoom in and out without losing context, automatic methods for map generalization are needed. We approach this problem for land-cover maps. Given two land-cover maps at two different scales, we want to find a sequence of small incremental changes that gradually transforms one map into the other. We assume that the two input maps consist of polygons, each of which belongs to a given land-cover type. Every polygon on the smaller-scale map is the union of a set of adjacent polygons on the larger-scale map. \par In each step of the computed sequence, the smallest area is merged with one of its neighbors. We do not select that neighbor according to a prescribed rule but compute the whole sequence of pairwise merges at once, based on global optimization. We have proved that this problem is NP-hard. We formalize this optimization problem as that of finding a shortest path in a (very large) graph. We present the A$^\star$ algorithm and integer linear programming to solve this optimization problem. To avoid long computing times, we allow the two methods to return non-optimal results. In addition, we present a greedy algorithm as a benchmark. We tested the three methods with a dataset of the official German topographic database ATKIS. Our main result is that A$^\star$ finds optimal aggregation sequences for more instances than the other two methods within a given time frame.

  @article{pwh-fosaa-TSAS20, abstract = {To provide users with maps of different scales and to allow them to zoom in and out without losing context, automatic methods for map generalization are needed. We approach this problem for land-cover maps. Given two land-cover maps at two different scales, we want to find a sequence of small incremental changes that gradually transforms one map into the other. We assume that the two input maps consist of polygons, each of which belongs to a given land-cover type. Every polygon on the smaller-scale map is the union of a set of adjacent polygons on the larger-scale map. \par In each step of the computed sequence, the smallest area is merged with one of its neighbors. We do not select that neighbor according to a prescribed rule but compute the whole sequence of pairwise merges at once, based on global optimization. We have proved that this problem is NP-hard. We formalize this optimization problem as that of finding a shortest path in a (very large) graph. We present the A$^\star$ algorithm and integer linear programming to solve this optimization problem. To avoid long computing times, we allow the two methods to return non-optimal results. In addition, we present a greedy algorithm as a benchmark. We tested the three methods with a dataset of the official German topographic database ATKIS. Our main result is that A$^\star$ finds optimal aggregation sequences for more instances than the other two methods within a given time frame.}, author = {Peng, Dongliang and Wolff, Alexander and Haunert, Jan-Henrik}, journal = {ACM Transactions on Spatial Algorithms and Systems}, keywords = {land_cover}, note = {article 4 (40 pages)}, number = 1, title = {Finding Optimal Sequences for Area Aggregation—{A}* vs.\ Integer Linear Programming}, volume = 7, year = 2020 }
• Bundled Crossings Revisited. Chaplick, Steven; van Dijk, Thomas C.; Kryven, Myroslav; Park, Ji-Won; Ravsky, Alexander; Wolff, Alexander. In Journal of Graph Algorithms \& Applications, 24(4), pp. 621–655. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  An effective way to reduce clutter in a graph drawing that has (many) crossings is to group edges that travel in parallel into bundles. Each edge can participate in many such bundles. Any crossing in this bundled graph occurs between two bundles, i.e., as a bundled crossing. We consider the problem of bundled crossing minimization: A graph is given and the goal is to find a bundled drawing with at most $k$ bundled crossings. We show that the problem is NP-hard when we require a simple drawing. Our main result is an FPT algorithm (in $k$) for simple circular layouts where vertices must be placed on a circle and edges must be drawn inside the circle. These results make use of the connection between bundled crossings and graph genus. We also consider bundling crossings in a given drawing, in particular for storyline visualizations.

  @article{cdkprw-bcr-JGAA20, abstract = {An effective way to reduce clutter in a graph drawing that has (many) crossings is to group edges that travel in parallel into bundles. Each edge can participate in many such bundles. Any crossing in this bundled graph occurs between two bundles, i.e., as a bundled crossing. We consider the problem of bundled crossing minimization: A graph is given and the goal is to find a bundled drawing with at most $k$ bundled crossings. We show that the problem is NP-hard when we require a simple drawing. Our main result is an FPT algorithm (in $k$) for simple circular layouts where vertices must be placed on a circle and edges must be drawn inside the circle. These results make use of the connection between bundled crossings and graph genus. We also consider bundling crossings in a given drawing, in particular for storyline visualizations.}, author = {Chaplick, Steven and van Dijk, Thomas C. and Kryven, Myroslav and Park, Ji-Won and Ravsky, Alexander and Wolff, Alexander}, journal = {Journal of Graph Algorithms \& Applications}, keywords = {fixed-parameter_tractable}, number = 4, pages = {621–655}, title = {Bundled Crossings Revisited}, volume = 24, year = 2020 }
• Developing a Study Design on the Effects of Different Motion Tracking Approaches on the User Embodiment in Virtual Reality. Ganal, Elisabeth; Bartl, Andrea; Westermeier, Franziska; Roth, Daniel; Latoschik, Marc Erich. In Mensch und Computer 2020, C. Hansen, A. Nürnberger, B. Preim (eds.). Gesellschaft für Informatik e.V., 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{https://doi.org/10.18420/muc2020-ws134-341, author = {Ganal, Elisabeth and Bartl, Andrea and Westermeier, Franziska and Roth, Daniel and Latoschik, Marc Erich}, editor = {Hansen, C. and Nürnberger, A. and Preim, B.}, journal = {Mensch und Computer 2020}, keywords = {westermeier}, publisher = {Gesellschaft für Informatik e.V.}, title = {Developing a Study Design on the Effects of Different Motion Tracking Approaches on the User Embodiment in Virtual Reality}, year = 2020 }
• HarryMotions – Classifying Relationships in Harry Potter based on Emotion Analysis. Zehe, Albin; Arns, Julia; Hettinger, Lena; Hotho, Andreas. In 5th SwissText & 16th KONVENS Joint Conference. 2020.
  • [ BibTeX ]
  @inproceedings{zehe2020harrymotions, author = {Zehe, Albin and Arns, Julia and Hettinger, Lena and Hotho, Andreas}, booktitle = {5th SwissText & 16th KONVENS Joint Conference}, keywords = 2020, title = {HarryMotions – Classifying Relationships in Harry Potter based on Emotion Analysis}, year = 2020 }
• {Time Series Forecasting for Self-Aware Systems}. Bauer, Andr{é}; Z{ü}fle, Marwin; Herbst, Nikolas; Zehe, Albin; Hotho, Andreas; Kounev, Samuel. In Proceedings of the IEEE, 108(7), pp. 1068–1093. 2020.
  • [ BibTeX ]
  @article{BaZuHeZeHoKo-PIEEE-Forecasting, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Herbst, Nikolas and Zehe, Albin and Hotho, Andreas and Kounev, Samuel}, journal = {Proceedings of the IEEE}, keywords = {t_journalmagazine}, month = {07}, number = 7, pages = {1068 - 1093}, title = {{Time Series Forecasting for Self-Aware Systems}}, volume = 108, year = 2020 }
• An IoT Network Emulator for Analyzing the Influence of Varying Network Quality. Herrnleben, Stefan; Ailabouni, Rudy; Grohmann, Johannes; Prantl, Thomas; Krupitzer, Christian; Kounev, Samuel. In Proceedings of the 12th EAI International Conference on Simulation Tools and Techniques (SIMUtools), of SIMUtools 2020. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  IoT devices often communicate over wireless or cellular networks with varying connection quality. These fluctuations are caused, among others, by the free-space path loss (FSPL), buildings, topological obstacles, weather, and mobility of the receiver. Varying signal quality affects bandwidth, transmission delays, packet loss, and jitter. Mobile IoT applications exposed to varying connection characteristics have to handle such variations and take them into account during development and testing. However, tests in real mobile networks are complex and challenging to reproduce. Therefore, network emulators can be used to simulate the behavior of real-world networks by adding artificial disturbance. However, existing network emulators often require a lot of technical knowledge and complex setup. Integrating such emulators into automated software testing pipelines could be a challenging task. In this paper, we propose a framework for emulating IoT networks with varying quality characteristics. An existing base emulator is used and integrated into our framework enabling the user to utilize it without extensive network expertise and configuration effort. The evaluation proves that our framework can simulate a variety of different network quality characteristics as well as emulating real-world network traces.

  @inproceedings{HeAiGrPrKrKo2020-SIMUtools-IoT-Network-Emulator, abstract = {IoT devices often communicate over wireless or cellular networks with varying connection quality. These fluctuations are caused, among others, by the free-space path loss (FSPL), buildings, topological obstacles, weather, and mobility of the receiver. Varying signal quality affects bandwidth, transmission delays, packet loss, and jitter. Mobile IoT applications exposed to varying connection characteristics have to handle such variations and take them into account during development and testing. However, tests in real mobile networks are complex and challenging to reproduce. Therefore, network emulators can be used to simulate the behavior of real-world networks by adding artificial disturbance. However, existing network emulators often require a lot of technical knowledge and complex setup. Integrating such emulators into automated software testing pipelines could be a challenging task. In this paper, we propose a framework for emulating IoT networks with varying quality characteristics. An existing base emulator is used and integrated into our framework enabling the user to utilize it without extensive network expertise and configuration effort. The evaluation proves that our framework can simulate a variety of different network quality characteristics as well as emulating real-world network traces.}, author = {Herrnleben, Stefan and Ailabouni, Rudy and Grohmann, Johannes and Prantl, Thomas and Krupitzer, Christian and Kounev, Samuel}, booktitle = {Proceedings of the 12th EAI International Conference on Simulation Tools and Techniques (SIMUtools)}, keywords = {networking}, month = {08}, series = {SIMUtools 2020}, title = {An IoT Network Emulator for Analyzing the Influence of Varying Network Quality}, year = 2020 }
• An IoT Network Emulator for Analyzing the Influence of Varying Network Quality. Herrnleben, Stefan; Ailabouni, Rudy; Grohmann, Johannes; Prantl, Thomas; Krupitzer, Christian; Kounev, Samuel. In Proceedings of the 12th EAI International Conference on Simulation Tools and Techniques (SIMUtools), of SIMUtools 2020. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  IoT devices often communicate over wireless or cellular networks with varying connection quality. These fluctuations are caused, among others, by the free-space path loss (FSPL), buildings, topological obstacles, weather, and mobility of the receiver. Varying signal quality affects bandwidth, transmission delays, packet loss, and jitter. Mobile IoT applications exposed to varying connection characteristics have to handle such variations and take them into account during development and testing. However, tests in real mobile networks are complex and challenging to reproduce. Therefore, network emulators can be used to simulate the behavior of real-world networks by adding artificial disturbance. However, existing network emulators often require a lot of technical knowledge and complex setup. Integrating such emulators into automated software testing pipelines could be a challenging task. In this paper, we propose a framework for emulating IoT networks with varying quality characteristics. An existing base emulator is used and integrated into our framework enabling the user to utilize it without extensive network expertise and configuration effort. The evaluation proves that our framework can simulate a variety of different network quality characteristics as well as emulating real-world network traces.

  @inproceedings{HeAiGrPrKrKo2020-SIMUtools-IoT-Network-Emulator, abstract = {IoT devices often communicate over wireless or cellular networks with varying connection quality. These fluctuations are caused, among others, by the free-space path loss (FSPL), buildings, topological obstacles, weather, and mobility of the receiver. Varying signal quality affects bandwidth, transmission delays, packet loss, and jitter. Mobile IoT applications exposed to varying connection characteristics have to handle such variations and take them into account during development and testing. However, tests in real mobile networks are complex and challenging to reproduce. Therefore, network emulators can be used to simulate the behavior of real-world networks by adding artificial disturbance. However, existing network emulators often require a lot of technical knowledge and complex setup. Integrating such emulators into automated software testing pipelines could be a challenging task. In this paper, we propose a framework for emulating IoT networks with varying quality characteristics. An existing base emulator is used and integrated into our framework enabling the user to utilize it without extensive network expertise and configuration effort. The evaluation proves that our framework can simulate a variety of different network quality characteristics as well as emulating real-world network traces.}, author = {Herrnleben, Stefan and Ailabouni, Rudy and Grohmann, Johannes and Prantl, Thomas and Krupitzer, Christian and Kounev, Samuel}, booktitle = {Proceedings of the 12th EAI International Conference on Simulation Tools and Techniques (SIMUtools)}, keywords = {networking}, month = {08}, series = {SIMUtools 2020}, title = {An IoT Network Emulator for Analyzing the Influence of Varying Network Quality}, year = 2020 }
• How Good is your Mobile (Web) Surfing? SpeedIndex Inference from Encrypted Traffic. Wassermann, Sarah; Casas, Pedro; Seufert, Michael; Wehner, Nikolas; Schüler, Joshua; Hoßfeld, Tobias. New York City, NY, USA, 2020, August.
  • [ Abstract ]
  • [ BibTeX ]
  We address the problem ofWeb QoE monitoring, in particular Speed Index (SI), from the Internet Service Provider (ISP) perspective, relying on in-network, passive measurements. Given the wide adoption of end-to-end encryption, we resort to machine-learning models to infer the SI of individual web-page loading sessions, using as input only packet-level data. Our study targets the analysis of SI in mobile devices, including smartphones and tablets. To the best of our knowledge, this is the first paper addressing the inference of SI from encrypted network traffic in mobile devices.

  @misc{info3-poster-2020-1, abstract = {We address the problem ofWeb QoE monitoring, in particular Speed Index (SI), from the Internet Service Provider (ISP) perspective, relying on in-network, passive measurements. Given the wide adoption of end-to-end encryption, we resort to machine-learning models to infer the SI of individual web-page loading sessions, using as input only packet-level data. Our study targets the analysis of SI in mobile devices, including smartphones and tablets. To the best of our knowledge, this is the first paper addressing the inference of SI from encrypted network traffic in mobile devices.}, address = {New York City, NY, USA}, author = {Wassermann, Sarah and Casas, Pedro and Seufert, Michael and Wehner, Nikolas and Schüler, Joshua and Hoßfeld, Tobias}, booktitle = {ACM Special Interest Group on Data Communication Conference (SIGCOMM)}, keywords = {ucn}, month = {08}, title = {How Good is your Mobile (Web) Surfing? SpeedIndex Inference from Encrypted Traffic}, year = 2020 }
• The Art of Loci: Immerse to Memorize. {Vetter}, Anne; {Götz}, Daniel; {von Mammen}, Sebastian. In 2020 IEEE Conference on Games (CoG), pp. 642–645. IEEE, Osaka, Japan, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  There are uncountable things to be remembered, but most people were never shown how to memorize effectively. With this paper, the application The Art of Loci (TAoL) is presented, to provide the means for efficient and fun learning. In a virtual reality (VR) environment users can express their study material visually, either creating dimensional mind maps or experimenting with mnemonic strategies, such as mind palaces. We also present common memorization techniques in light of their underlying pedagogical foundations and discuss the respective features of TAoL in comparison with similar software applications.

  @inproceedings{9231610, abstract = {There are uncountable things to be remembered, but most people were never shown how to memorize effectively. With this paper, the application The Art of Loci (TAoL) is presented, to provide the means for efficient and fun learning. In a virtual reality (VR) environment users can express their study material visually, either creating dimensional mind maps or experimenting with mnemonic strategies, such as mind palaces. We also present common memorization techniques in light of their underlying pedagogical foundations and discuss the respective features of TAoL in comparison with similar software applications.}, address = {Osaka, Japan}, author = {{Vetter}, Anne and {Götz}, Daniel and {von Mammen}, Sebastian}, booktitle = {2020 IEEE Conference on Games (CoG)}, keywords = {myown}, month = {08}, pages = {642-645}, publisher = {IEEE}, title = {The Art of Loci: Immerse to Memorize}, year = 2020 }
• An IoT Network Emulator for Analyzing the Influence of Varying Network Quality. Herrnleben, Stefan; Ailabouni, Rudy; Grohmann, Johannes; Prantl, Thomas; Krupitzer, Christian; Kounev, Samuel. In Proceedings of the 12th EAI International Conference on Simulation Tools and Techniques (SIMUtools), of SIMUtools 2020. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  IoT devices often communicate over wireless or cellular networks with varying connection quality. These fluctuations are caused, among others, by the free-space path loss (FSPL), buildings, topological obstacles, weather, and mobility of the receiver. Varying signal quality affects bandwidth, transmission delays, packet loss, and jitter. Mobile IoT applications exposed to varying connection characteristics have to handle such variations and take them into account during development and testing. However, tests in real mobile networks are complex and challenging to reproduce. Therefore, network emulators can be used to simulate the behavior of real-world networks by adding artificial disturbance. However, existing network emulators often require a lot of technical knowledge and complex setup. Integrating such emulators into automated software testing pipelines could be a challenging task. In this paper, we propose a framework for emulating IoT networks with varying quality characteristics. An existing base emulator is used and integrated into our framework enabling the user to utilize it without extensive network expertise and configuration effort. The evaluation proves that our framework can simulate a variety of different network quality characteristics as well as emulating real-world network traces.

  @inproceedings{HeAiGrPrKrKo2020-SIMUtools-IoT-Network-Emulator, abstract = {IoT devices often communicate over wireless or cellular networks with varying connection quality. These fluctuations are caused, among others, by the free-space path loss (FSPL), buildings, topological obstacles, weather, and mobility of the receiver. Varying signal quality affects bandwidth, transmission delays, packet loss, and jitter. Mobile IoT applications exposed to varying connection characteristics have to handle such variations and take them into account during development and testing. However, tests in real mobile networks are complex and challenging to reproduce. Therefore, network emulators can be used to simulate the behavior of real-world networks by adding artificial disturbance. However, existing network emulators often require a lot of technical knowledge and complex setup. Integrating such emulators into automated software testing pipelines could be a challenging task. In this paper, we propose a framework for emulating IoT networks with varying quality characteristics. An existing base emulator is used and integrated into our framework enabling the user to utilize it without extensive network expertise and configuration effort. The evaluation proves that our framework can simulate a variety of different network quality characteristics as well as emulating real-world network traces.}, author = {Herrnleben, Stefan and Ailabouni, Rudy and Grohmann, Johannes and Prantl, Thomas and Krupitzer, Christian and Kounev, Samuel}, booktitle = {Proceedings of the 12th EAI International Conference on Simulation Tools and Techniques (SIMUtools)}, keywords = {networking}, month = {08}, series = {SIMUtools 2020}, title = {An IoT Network Emulator for Analyzing the Influence of Varying Network Quality}, year = 2020 }
• {Time Series Forecasting for Self-Aware Systems}. Bauer, Andr{é}; Z{ü}fle, Marwin; Herbst, Nikolas; Zehe, Albin; Hotho, Andreas; Kounev, Samuel. In Proceedings of the IEEE, 108(7), pp. 1068–1093. 2020.
  • [ BibTeX ]
  @article{BaZuHeZeHoKo-PIEEE-Forecasting, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Herbst, Nikolas and Zehe, Albin and Hotho, Andreas and Kounev, Samuel}, journal = {Proceedings of the IEEE}, keywords = {t_journalmagazine}, month = {07}, number = 7, pages = {1068 - 1093}, title = {{Time Series Forecasting for Self-Aware Systems}}, volume = 108, year = 2020 }
• Deriving QoE in systems: from fundamental relationships to a QoE‑based Service‑level Quality Index. Hoßfeld, Tobias; Heegaard, Poul E.; Skorin-Kapov, Lea; Varela, Martin. In Springer Quality and User Experience, 5(7), p. https://rdcu.be/b483m. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  With Quality of Experience (QoE) research having made significant advances over the years, service and network providers aim at user-centric evaluation of the services provided in their system. The question arises how to derive QoE in systems. In the context of subjective user studies conducted to derive relationships between influence factors and QoE, user diversity leads to varying distributions of user rating scores for different test conditions. Such models are commonly exploited by providers to derive various QoE metrics in their system, such as expected QoE, or the percentage of users rating above a certain threshold. The question then becomes how to combine (a) user rating distributions obtained from subjective studies, and (b) system parameter distributions, so as to obtain the actual observed QoE distribution in the system? Moreover, how can various QoE metrics of interest in the system be derived? We prove fundamental relationships for the derivation of QoE in systems, thus providing an important link between the QoE community and the systems community. In our numerical examples, we focus mainly on QoE metrics. We furthermore provide a more generalized view on quantifying the quality of systems by defining a QoE-based Service-level Quality Index. This index exploits the fact that quality can be seen as a proxy measure for utility. Following the assumption that not all user sessions should be weighted equally, we aim to provide a generic framework that can be utilized to quantify the overall utility of a service delivered by a system.

  @article{info3-article-2020-2, abstract = {With Quality of Experience (QoE) research having made significant advances over the years, service and network providers aim at user-centric evaluation of the services provided in their system. The question arises how to derive QoE in systems. In the context of subjective user studies conducted to derive relationships between influence factors and QoE, user diversity leads to varying distributions of user rating scores for different test conditions. Such models are commonly exploited by providers to derive various QoE metrics in their system, such as expected QoE, or the percentage of users rating above a certain threshold. The question then becomes how to combine (a) user rating distributions obtained from subjective studies, and (b) system parameter distributions, so as to obtain the actual observed QoE distribution in the system? Moreover, how can various QoE metrics of interest in the system be derived? We prove fundamental relationships for the derivation of QoE in systems, thus providing an important link between the QoE community and the systems community. In our numerical examples, we focus mainly on QoE metrics. We furthermore provide a more generalized view on quantifying the quality of systems by defining a QoE-based Service-level Quality Index. This index exploits the fact that quality can be seen as a proxy measure for utility. Following the assumption that not all user sessions should be weighted equally, we aim to provide a generic framework that can be utilized to quantify the overall utility of a service delivered by a system.}, author = {Hoßfeld, Tobias and Heegaard, Poul E. and Skorin-Kapov, Lea and Varela, Martin}, journal = {Springer Quality and User Experience}, keywords = {dfg-sdn}, month = {07}, number = 7, pages = {https://rdcu.be/b483m}, title = {Deriving QoE in systems: from fundamental relationships to a QoE‑based Service‑level Quality Index}, volume = 5, year = 2020 }
• From QoS Distributions to QoE Distributions: a System’s Perspective. Hoßfeld, Tobias; Heegaard, Poul E.; Varela, Martin; Skorin-Kapov, Lea; Fiedler, Markus. In 4th International Workshop on Quality of Experience Management (QoE Management 2020), featured by IEEE Conference on Network Softwarization (IEEE NetSoft 2020). Ghent, Belgium, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  In the context of QoE management, network and service providers commonly rely on models that map system QoS conditions (e.g., system response time, packet loss, etc.) to estimated end user QoE values. Observable QoS conditions in the system may be assumed to follow a certain distribution, meaning that different end users will experience different conditions. On the other hand, drawing from the results of subjective user studies, we know that user diversity leads to distributions of user scores for any given test conditions (in this case referring to the QoS parameters of interest). Our previous studies have shown that to correctly derive various QoE metrics (e.g., Mean Opinion Score (MOS), quantiles, probability of users rating 'good or better', etc.) in a system under given conditions, there is a need to consider rating distributions obtained from user studies, which are often times not available. In the paper we extend these findings to show how to approximate user rating distributions given a QoS-to-MOS mapping function and second order statistics. Such a user rating distribution may then be combined with a QoS distribution observed in a system to finally derive corresponding distributions of QoE scores. Scripts are provided for the approximating a QoE distribution with a Beta distribution for given MOS and SOS parameter at https://github.com/hossfeld/approx-qoe-distribution.

  @inproceedings{info3-inproceedings-2020-6, abstract = {In the context of QoE management, network and service providers commonly rely on models that map system QoS conditions (e.g., system response time, packet loss, etc.) to estimated end user QoE values. Observable QoS conditions in the system may be assumed to follow a certain distribution, meaning that different end users will experience different conditions. On the other hand, drawing from the results of subjective user studies, we know that user diversity leads to distributions of user scores for any given test conditions (in this case referring to the QoS parameters of interest). Our previous studies have shown that to correctly derive various QoE metrics (e.g., Mean Opinion Score (MOS), quantiles, probability of users rating 'good or better', etc.) in a system under given conditions, there is a need to consider rating distributions obtained from user studies, which are often times not available. In the paper we extend these findings to show how to approximate user rating distributions given a QoS-to-MOS mapping function and second order statistics. Such a user rating distribution may then be combined with a QoS distribution observed in a system to finally derive corresponding distributions of QoE scores. Scripts are provided for the approximating a QoE distribution with a Beta distribution for given MOS and SOS parameter at https://github.com/hossfeld/approx-qoe-distribution.}, address = {Ghent, Belgium}, author = {Hoßfeld, Tobias and Heegaard, Poul E. and Varela, Martin and Skorin-Kapov, Lea and Fiedler, Markus}, booktitle = {4th International Workshop on Quality of Experience Management (QoE Management 2020), featured by IEEE Conference on Network Softwarization (IEEE NetSoft 2020)}, keywords = {myown}, month = {07}, title = {From QoS Distributions to QoE Distributions: a System's Perspective}, year = 2020 }
• Subjective perception of craniofacial growth asymmetries in patients with deformational plagiocephaly. Kunz, Felix; Hirth, Matthias; Schweitzer, Tilmann; Linz, Christian; Goetz, Berhard; Stellzig-Eisenhauer, Angelika; Borchert, Kathrin; Böhm, Hartmut. In Springer Clinical Oral Investigations, 24, pp. https://doi.org/10.1007/s00784–020. 2020.
  • [ BibTeX ]
  @article{info3-article-2020-3, author = {Kunz, Felix and Hirth, Matthias and Schweitzer, Tilmann and Linz, Christian and Goetz, Berhard and Stellzig-Eisenhauer, Angelika and Borchert, Kathrin and Böhm, Hartmut}, journal = {Springer Clinical Oral Investigations}, keywords = {myown}, month = {07}, pages = {https://doi.org/10.1007/s00784-020-03417-y}, title = {Subjective perception of craniofacial growth asymmetries in patients with deformational plagiocephaly}, volume = 24, year = 2020 }
• Crowdsourced Network Measurements in Germany: Mobile Internet Experience from End User Perspective. Schwind, Anika; Wamser, Florian; Hoßfeld, Tobias; Wunderer, Stefan; Tarnvik, Erik; Hall, Andy. In Broadband Coverage in Germany; 14. ITG Symposium. Berlin, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Collecting and analyzing meaningful data in mobile networks is the key to assessing network performance. Crowdsourced Network Measurements (CNMs) provide insights beyond the network layer and offer performance and other measurements at the application and user-level towards Quality of Experience (QoE). In this paper, the mobile Internet experience for Germany is evaluated with the help of crowdsourcing from the perspective of an end user. We statistically analyze a dataset with throughput measurements on the end device from Tutela Ltd., which covers more than 2.5 million throughput tests across Germany from January to July 2019. We give insights into this emerging methodology and highlight the benefits of this method. The paper contains statistics and conclusions for several large cities as well as regions in Germany compared to general statements for Germany, since individual measurements and averages often only imprecisely reflect the situation. The goal is to give a holistic view of the performance of the current mobile network in Germany. Reading this paper, it becomes evident that reliable statements about the quality of the mobile network for Germany depend on a large number of peculiarities in different regions with their own performance characteristics due to different network deployments and population numbers.

  @inproceedings{info3-inproceedings-2020-13, abstract = {Collecting and analyzing meaningful data in mobile networks is the key to assessing network performance. Crowdsourced Network Measurements (CNMs) provide insights beyond the network layer and offer performance and other measurements at the application and user-level towards Quality of Experience (QoE). In this paper, the mobile Internet experience for Germany is evaluated with the help of crowdsourcing from the perspective of an end user. We statistically analyze a dataset with throughput measurements on the end device from Tutela Ltd., which covers more than 2.5 million throughput tests across Germany from January to July 2019. We give insights into this emerging methodology and highlight the benefits of this method. The paper contains statistics and conclusions for several large cities as well as regions in Germany compared to general statements for Germany, since individual measurements and averages often only imprecisely reflect the situation. The goal is to give a holistic view of the performance of the current mobile network in Germany. Reading this paper, it becomes evident that reliable statements about the quality of the mobile network for Germany depend on a large number of peculiarities in different regions with their own performance characteristics due to different network deployments and population numbers.}, address = {Berlin}, author = {Schwind, Anika and Wamser, Florian and Hoßfeld, Tobias and Wunderer, Stefan and Tarnvik, Erik and Hall, Andy}, booktitle = {Broadband Coverage in Germany; 14. ITG Symposium}, keywords = {can}, month = {08}, title = {Crowdsourced Network Measurements in Germany: Mobile Internet Experience from End User Perspective}, year = 2020 }
• Poster: Per-Hop Bridge-Local Latency Bounds with Strict Priority Transmission Selection. Grigorjew, Alexej; Metzger, Florian; Hoßfeld, Tobias; Specht, Johannes; Götz, Franz-Josef; Chen, Feng; Schmitt, Jürgen. In IFIP Networking Conference. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  This work presents a proven per-hop latency bound for real-time networks with admission control that does not rely on shaping or timed gates. It can be applied in a distributed control plane using only bridge-local information, making it an ideal candidate for brownfield real-time network installations. A brief comparison with Asynchronous Traffic Shaping (ATS) shows that the achieved network utilization is comparable to that of ATS in some scenarios, while it only lags behind in scenarios with accumulating bursts where re-shaping could actually reduce the interference of the observed streams.

  @inproceedings{info3-inproceedings-2020-16, abstract = {This work presents a proven per-hop latency bound for real-time networks with admission control that does not rely on shaping or timed gates. It can be applied in a distributed control plane using only bridge-local information, making it an ideal candidate for brownfield real-time network installations. A brief comparison with Asynchronous Traffic Shaping (ATS) shows that the achieved network utilization is comparable to that of ATS in some scenarios, while it only lags behind in scenarios with accumulating bursts where re-shaping could actually reduce the interference of the observed streams.}, author = {Grigorjew, Alexej and Metzger, Florian and Hoßfeld, Tobias and Specht, Johannes and Götz, Franz-Josef and Chen, Feng and Schmitt, Jürgen}, booktitle = {IFIP Networking Conference}, keywords = {ats-performance}, month = {06}, title = {Poster: Per-Hop Bridge-Local Latency Bounds with Strict Priority Transmission Selection}, year = 2020 }
• A Review of Serverless Use Cases and their Characteristics. Eismann, Simon; Scheuner, Joel; van Eyk, Erwin; Schwinger, Maximilian; Grohmann, Johannes; Herbst, Nikolas; Abad, Cristina; Iosup, Alexandru. SPEC RG, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The serverless computing paradigm promises many desirable properties for cloud applications - low-cost, fine-grained deployment, and management-free operation. Consequently, the paradigm has underwent rapid growth: there currently exist tens of serverless platforms and all global cloud providers host serverless operations. To help tune existing platforms, guide the design of new serverless approaches, and overall contribute to understanding this paradigm, in this work we present a long-term, comprehensive effort to identify, collect, and characterize serverless use cases. We survey 89 use cases, sourced from white and grey literature, and from consultations with experts in areas such as scientific computing. We study each use case using 24 characteristics, including general aspects, but also workload, application, and requirements. When the use cases employ workflows, we further analyze their characteristics. Overall, we hope our study will be useful for both academia and industry, and encourage the community to further share and communicate their use cases.

  @techreport{eismann2020review, abstract = {The serverless computing paradigm promises many desirable properties for cloud applications - low-cost, fine-grained deployment, and management-free operation. Consequently, the paradigm has underwent rapid growth: there currently exist tens of serverless platforms and all global cloud providers host serverless operations. To help tune existing platforms, guide the design of new serverless approaches, and overall contribute to understanding this paradigm, in this work we present a long-term, comprehensive effort to identify, collect, and characterize serverless use cases. We survey 89 use cases, sourced from white and grey literature, and from consultations with experts in areas such as scientific computing. We study each use case using 24 characteristics, including general aspects, but also workload, application, and requirements. When the use cases employ workflows, we further analyze their characteristics. Overall, we hope our study will be useful for both academia and industry, and encourage the community to further share and communicate their use cases.}, author = {Eismann, Simon and Scheuner, Joel and van Eyk, Erwin and Schwinger, Maximilian and Grohmann, Johannes and Herbst, Nikolas and Abad, Cristina and Iosup, Alexandru}, keywords = {t_techreport}, month = {06}, publisher = {SPEC RG}, title = {A Review of Serverless Use Cases and their Characteristics}, year = 2020 }
• A Review of Serverless Use Cases and their Characteristics. Eismann, Simon; Scheuner, Joel; van Eyk, Erwin; Schwinger, Maximilian; Grohmann, Johannes; Herbst, Nikolas; Abad, Cristina; Iosup, Alexandru. SPEC RG, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The serverless computing paradigm promises many desirable properties for cloud applications - low-cost, fine-grained deployment, and management-free operation. Consequently, the paradigm has underwent rapid growth: there currently exist tens of serverless platforms and all global cloud providers host serverless operations. To help tune existing platforms, guide the design of new serverless approaches, and overall contribute to understanding this paradigm, in this work we present a long-term, comprehensive effort to identify, collect, and characterize serverless use cases. We survey 89 use cases, sourced from white and grey literature, and from consultations with experts in areas such as scientific computing. We study each use case using 24 characteristics, including general aspects, but also workload, application, and requirements. When the use cases employ workflows, we further analyze their characteristics. Overall, we hope our study will be useful for both academia and industry, and encourage the community to further share and communicate their use cases.

  @techreport{eismann2020review, abstract = {The serverless computing paradigm promises many desirable properties for cloud applications - low-cost, fine-grained deployment, and management-free operation. Consequently, the paradigm has underwent rapid growth: there currently exist tens of serverless platforms and all global cloud providers host serverless operations. To help tune existing platforms, guide the design of new serverless approaches, and overall contribute to understanding this paradigm, in this work we present a long-term, comprehensive effort to identify, collect, and characterize serverless use cases. We survey 89 use cases, sourced from white and grey literature, and from consultations with experts in areas such as scientific computing. We study each use case using 24 characteristics, including general aspects, but also workload, application, and requirements. When the use cases employ workflows, we further analyze their characteristics. Overall, we hope our study will be useful for both academia and industry, and encourage the community to further share and communicate their use cases.}, author = {Eismann, Simon and Scheuner, Joel and van Eyk, Erwin and Schwinger, Maximilian and Grohmann, Johannes and Herbst, Nikolas and Abad, Cristina and Iosup, Alexandru}, keywords = {t_techreport}, month = {06}, publisher = {SPEC RG}, title = {A Review of Serverless Use Cases and their Characteristics}, year = 2020 }
• Different Points of View: Impact of 3D Point Cloud Reduction on QoE of Rendered Images. Seufert, Michael. 12th International Conference on Quality of Multimedia Experience (QoMEX), Athlone, Ireland (virtual), 2020, May 27.
  • [ BibTeX ]
  @presentation{info3-presentation-2020-2, address = {12th International Conference on Quality of Multimedia Experience (QoMEX), Athlone, Ireland (virtual)}, author = {Seufert, Michael}, keywords = {ucn}, month = {05}, title = {Different Points of View: Impact of 3D Point Cloud Reduction on QoE of Rendered Images}, year = 2020 }
• Inferring Web QoE with Machine Learning from Encrypted Network Traffic. Wehner, Nikolas. 2nd KuVS Workshop on Machine Learning for Networking, Würzburg, Germany, 2020, October 8.
  • [ Abstract ]
  • [ BibTeX ]
  In this work, the problem of Quality of Experience (QoE) monitoring of web browsing is addressed. In particular, the inference of common Web QoE metrics like RUMSI with machine learning is investigated. Based on a large dataset collected with WebPageTest on three different devices, a unique feature set is used to approximate Web QoE metrics with regression and classification approaches. This work highlights work in progress.

  @presentation{info3-presentation-2020-3, abstract = {In this work, the problem of Quality of Experience (QoE) monitoring of web browsing is addressed. In particular, the inference of common Web QoE metrics like RUMSI with machine learning is investigated. Based on a large dataset collected with WebPageTest on three different devices, a unique feature set is used to approximate Web QoE metrics with regression and classification approaches. This work highlights work in progress.}, address = {2nd KuVS Workshop on Machine Learning for Networking, Würzburg, Germany}, author = {Wehner, Nikolas}, keywords = {myown}, month = 10, title = {Inferring Web QoE with Machine Learning from Encrypted Network Traffic}, year = 2020 }
• Crowdsensed QoE for the community - a concept to make QoE assessment accessible. Metzger, Florian. 2020, May.
  • [ BibTeX ]
  @misc{info3-misc-2020-2, author = {Metzger, Florian}, howpublished = {https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-203748}, keywords = {myown}, month = {05}, title = {Crowdsensed QoE for the community - a concept to make QoE assessment accessible}, year = 2020 }
• Emote-Controlled: Obtaining Implicit Viewer Feedback through Emote based Sentiment Analysis on Comments of Popular Twitch.tv Channels. Kobs, Konstantin; Zehe, Albin; Bernstetter, Armin; Chibane, Julian; Pfister, Jan; Tritscher, Julian; Hotho, Andreas. In {ACM} Transactions on Social Computing, 3(2), pp. 1–34. Association for Computing Machinery ({ACM}), 2020.
  • [ BibTeX ]
  • [ URL ]
  @article{kobs2020emotecontrolled, author = {Kobs, Konstantin and Zehe, Albin and Bernstetter, Armin and Chibane, Julian and Pfister, Jan and Tritscher, Julian and Hotho, Andreas}, journal = {{ACM} Transactions on Social Computing}, keywords = {selected}, month = {05}, number = 2, pages = {1–34}, publisher = {Association for Computing Machinery ({ACM})}, title = {Emote-Controlled: Obtaining Implicit Viewer Feedback through Emote based Sentiment Analysis on Comments of Popular Twitch.tv Channels}, volume = 3, year = 2020 }
• Different Points of View: Impact of 3D Point Cloud Reduction on QoE of Rendered Images. Seufert, Michael; Kargl, Julian; Schauer, Johannes; Nüchter, Andreas; Hoßfeld, Tobias. In 12th International Conference on Quality of Multimedia Experience (QoMEX). Athlone, Ireland, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Modern photogrammetric methods as well as laser measurement systems make it easy to collect large 3D point clouds that sample objects or environments. As the recorded point clouds can be used to render computer-generated images and models, they are of particular interest in the domains of geographical and architectural engineering, as well for computer graphics (e.g., games or virtual reality). However, point clouds have a huge storage demand, thus, point clouds shall be reduced by removing some of the points. This will inevitably also reduce the Quality of Experience (QoE) of media, which is rendered from the reduced point clouds. In this work, the impact of two different reduction methods on the QoE of rendered images is investigated from two point of views, i.e., based on ratings from both naive crowdworkers as well as point cloud experts.

  @inproceedings{info3-inproceedings-2020-4, abstract = {Modern photogrammetric methods as well as laser measurement systems make it easy to collect large 3D point clouds that sample objects or environments. As the recorded point clouds can be used to render computer-generated images and models, they are of particular interest in the domains of geographical and architectural engineering, as well for computer graphics (e.g., games or virtual reality). However, point clouds have a huge storage demand, thus, point clouds shall be reduced by removing some of the points. This will inevitably also reduce the Quality of Experience (QoE) of media, which is rendered from the reduced point clouds. In this work, the impact of two different reduction methods on the QoE of rendered images is investigated from two point of views, i.e., based on ratings from both naive crowdworkers as well as point cloud experts.}, address = {Athlone, Ireland}, author = {Seufert, Michael and Kargl, Julian and Schauer, Johannes and Nüchter, Andreas and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ua-net}, month = {05}, title = {Different Points of View: Impact of 3D Point Cloud Reduction on QoE of Rendered Images}, year = 2020 }
• Visual angle modulates affective responses to audiovisual stimuli. Gall, Dominik; Latoschik, Marc Erich. In Computers in Human Behavior, 109, p. 106346. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  What we see influences our emotions. Technology often mediates the visual content we perceive. Visual angle is an essential parameter of how we see such content. It operationalizes visible properties of human-computer interfaces. However, we know little about the content-independent effect of visual angle on emotional responses to audiovisual stimuli. We show that visual angle alone affects emotional responses to audiovisual features, independent of object perception. We conducted a 2 x 2 x 3 factorial repeated-measures experiment with 143 undergraduate students. We simultaneously presented monochrome rectangles with pure tones and assessed valence, arousal, and dominance. In the high visual angle condition, arousal increased, valence and dominance decreased, and lightness modulated arousal. In the low visual angle condition, pitch modulated arousal, and lightness affected valence. Visual angle weights the affective relevance of perception modalities independent of spatial representations. Visual angle serves as an early-stage perceptual feature for organizing emotional responses. Control of this presentation layer allows for provoking or avoiding emotional response where intended.

  @article{gall2020visual, abstract = {What we see influences our emotions. Technology often mediates the visual content we perceive. Visual angle is an essential parameter of how we see such content. It operationalizes visible properties of human-computer interfaces. However, we know little about the content-independent effect of visual angle on emotional responses to audiovisual stimuli. We show that visual angle alone affects emotional responses to audiovisual features, independent of object perception. We conducted a 2 x 2 x 3 factorial repeated-measures experiment with 143 undergraduate students. We simultaneously presented monochrome rectangles with pure tones and assessed valence, arousal, and dominance. In the high visual angle condition, arousal increased, valence and dominance decreased, and lightness modulated arousal. In the low visual angle condition, pitch modulated arousal, and lightness affected valence. Visual angle weights the affective relevance of perception modalities independent of spatial representations. Visual angle serves as an early-stage perceptual feature for organizing emotional responses. Control of this presentation layer allows for provoking or avoiding emotional response where intended.}, author = {Gall, Dominik and Latoschik, Marc Erich}, journal = {Computers in Human Behavior}, keywords = {myown}, month = {08}, pages = 106346, title = {Visual angle modulates affective responses to audiovisual stimuli}, volume = 109, year = 2020 }
• Horst – The Teaching Frog: Learning the Anatomy of a Frog Using Tangible AR. Oberdörfer, Sebastian; Elsässer, Anne; Schraudt, David; Grafe, Silke; Latoschik, Marc Erich. In Proceedings of the 2020 Mensch und Computer Conference (MuC ’20), pp. 303–307. Association for Computing Machinery, New York, NY, USA, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Learning environments targeting Augmented Reality (AR) visualize complex facts, can increase a learner's motivation, and allow for the application of learning contents. When using tangible user interfaces, the learning process receives a physical aspect improving the overall intuitive use. We present a tangible AR system targeting the learning of a frog's anatomy. The learning environment is based on a plushfrog containing removable markers. Detecting the markers, replaces them with 3D models of the organs. By extracting individual organs, learners can inspect them up close and learn more about their functions. Our AR frog further includes a quiz for a self-assessment of the learning progress and a gamification system to raise the overall motivation.

  @inproceedings{oberdorfer2020horst, abstract = {Learning environments targeting Augmented Reality (AR) visualize complex facts, can increase a learner's motivation, and allow for the application of learning contents. When using tangible user interfaces, the learning process receives a physical aspect improving the overall intuitive use. We present a tangible AR system targeting the learning of a frog's anatomy. The learning environment is based on a plushfrog containing removable markers. Detecting the markers, replaces them with 3D models of the organs. By extracting individual organs, learners can inspect them up close and learn more about their functions. Our AR frog further includes a quiz for a self-assessment of the learning progress and a gamification system to raise the overall motivation.}, address = {New York, NY, USA}, author = {Oberdörfer, Sebastian and Elsässer, Anne and Schraudt, David and Grafe, Silke and Latoschik, Marc Erich}, booktitle = {Proceedings of the 2020 Mensch und Computer Conference (MuC '20)}, keywords = {horst}, month = {09}, pages = {303-307}, publisher = {Association for Computing Machinery}, title = {Horst – The Teaching Frog: Learning the Anatomy of a Frog Using Tangible AR}, year = 2020 }
• Improving Sentiment Analysis with Biofeedback Data. Schl{ö}r, Daniel; Zehe, Albin; Kobs, Konstantin; Veseli, Blerta; Westermeier, Franziska; Br{ü}bach, Larissa; Roth, Daniel; Latoschik, Marc Erich; Hotho, Andreas. In Proceedings of LREC2020 Workshop ``People in language, vision and the mind’’ (ONION2020), pp. 28–33. European Language Resources Association (ELRA), Marseille, France, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Humans frequently are able to read and interpret emotions of others by directly taking verbal and non-verbal signals in human-to-human communication into account or to infer or even experience emotions from mediated stories. For computers, however, emotion recognition is a complex problem: Thoughts and feelings are the roots of many behavioural responses and they are deeply entangled with neurophysiological changes within humans. As such, emotions are very subjective, often are expressed in a subtle manner, and are highly depending on context. For example, machine learning approaches for text-based sentiment analysis often rely on incorporating sentiment lexicons or language models to capture the contextual meaning. This paper explores if and how we further can enhance sentiment analysis using biofeedback of humans which are experiencing emotions while reading texts. Specifically, we record the heart rate and brain waves of readers that are presented with short texts which have been annotated with the emotions they induce. We use these physiological signals to improve the performance of a lexicon-based sentiment classifier. We find that the combination of several biosignals can improve the ability of a text-based classifier to detect the presence of a sentiment in a text on a per-sentence level.

  @inproceedings{schlor2020improving, abstract = {Humans frequently are able to read and interpret emotions of others by directly taking verbal and non-verbal signals in human-to-human communication into account or to infer or even experience emotions from mediated stories. For computers, however, emotion recognition is a complex problem: Thoughts and feelings are the roots of many behavioural responses and they are deeply entangled with neurophysiological changes within humans. As such, emotions are very subjective, often are expressed in a subtle manner, and are highly depending on context. For example, machine learning approaches for text-based sentiment analysis often rely on incorporating sentiment lexicons or language models to capture the contextual meaning. This paper explores if and how we further can enhance sentiment analysis using biofeedback of humans which are experiencing emotions while reading texts. Specifically, we record the heart rate and brain waves of readers that are presented with short texts which have been annotated with the emotions they induce. We use these physiological signals to improve the performance of a lexicon-based sentiment classifier. We find that the combination of several biosignals can improve the ability of a text-based classifier to detect the presence of a sentiment in a text on a per-sentence level.}, address = {Marseille, France}, author = {Schl{\"o}r, Daniel and Zehe, Albin and Kobs, Konstantin and Veseli, Blerta and Westermeier, Franziska and Br{\"u}bach, Larissa and Roth, Daniel and Latoschik, Marc Erich and Hotho, Andreas}, booktitle = {Proceedings of LREC2020 Workshop ``People in language, vision and the mind'' (ONION2020)}, keywords = 2020, month = {05}, pages = {28–33}, publisher = {European Language Resources Association (ELRA)}, title = {Improving Sentiment Analysis with Biofeedback Data}, year = 2020 }
• Where to Submit? Helping Researchers to Choose the Right Venue. Kobs, Konstantin; Koopmann, Tobias; Zehe, Albin; Fernes, David; Krop, Philipp; Hotho, Andreas. In Findings of the Association for Computational Linguistics: EMNLP 2020, pp. 878–883. Association for Computational Linguistics, Online, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Whenever researchers write a paper, the same question occurs: {``}Where to submit?{''} In this work, we introduce WTS, an open and interpretable NLP system that recommends conferences and journals to researchers based on the title, abstract, and/or keywords of a given paper. We adapt the TextCNN architecture and automatically analyze its predictions using the Integrated Gradients method to highlight words and phrases that led to the recommendation of a scientific venue. We train and test our method on publications from the fields of artificial intelligence (AI) and medicine, both derived from the Semantic Scholar dataset. WTS achieves an Accuracy@5 of approximately 83{\%} for AI papers and 95{\%} in the field of medicine. It is open source and available for testing on https://wheretosubmit.ml.

  @inproceedings{kobs2020where, abstract = {Whenever researchers write a paper, the same question occurs: {``}Where to submit?{''} In this work, we introduce WTS, an open and interpretable NLP system that recommends conferences and journals to researchers based on the title, abstract, and/or keywords of a given paper. We adapt the TextCNN architecture and automatically analyze its predictions using the Integrated Gradients method to highlight words and phrases that led to the recommendation of a scientific venue. We train and test our method on publications from the fields of artificial intelligence (AI) and medicine, both derived from the Semantic Scholar dataset. WTS achieves an Accuracy@5 of approximately 83{\%} for AI papers and 95{\%} in the field of medicine. It is open source and available for testing on https://wheretosubmit.ml.}, address = {Online}, author = {Kobs, Konstantin and Koopmann, Tobias and Zehe, Albin and Fernes, David and Krop, Philipp and Hotho, Andreas}, booktitle = {Findings of the Association for Computational Linguistics: EMNLP 2020}, keywords = {research}, month = 11, pages = {878–883}, publisher = {Association for Computational Linguistics}, title = {Where to Submit? Helping Researchers to Choose the Right Venue}, year = 2020 }
• SimLoss: Class Similarities in Cross Entropy. Kobs, Konstantin; Steininger, Michael; Zehe, Albin; Lautenschlager, Florian; Hotho, Andreas. In Foundations of Intelligent Systems, D. Helic, G. Leitner, M. Stettinger, A. Felfernig, Z. W. Ra{{{\’s}}} (eds.), pp. 431–439. Springer International Publishing, Cham, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  One common loss function in neural network classification tasks is Categorical Cross Entropy (CCE), which punishes all misclassifications equally. However, classes often have an inherent structure. For instance, classifying an image of a rose as ``violet'' is better than as ``truck''. We introduce SimLoss, a drop-in replacement for CCE that incorporates class similarities along with two techniques to construct such matrices from task-specific knowledge. We test SimLoss on Age Estimation and Image Classification and find that it brings significant improvements over CCE on several metrics. SimLoss therefore allows for explicit modeling of background knowledge by simply exchanging the loss function, while keeping the neural network architecture the same. Code and additional resources are available at https://github.com/konstantinkobs/SimLoss

  @inproceedings{kobs2020simloss, abstract = {One common loss function in neural network classification tasks is Categorical Cross Entropy (CCE), which punishes all misclassifications equally. However, classes often have an inherent structure. For instance, classifying an image of a rose as ``violet'' is better than as ``truck''. We introduce SimLoss, a drop-in replacement for CCE that incorporates class similarities along with two techniques to construct such matrices from task-specific knowledge. We test SimLoss on Age Estimation and Image Classification and find that it brings significant improvements over CCE on several metrics. SimLoss therefore allows for explicit modeling of background knowledge by simply exchanging the loss function, while keeping the neural network architecture the same. Code and additional resources are available at https://github.com/konstantinkobs/SimLoss}, address = {Cham}, author = {Kobs, Konstantin and Steininger, Michael and Zehe, Albin and Lautenschlager, Florian and Hotho, Andreas}, booktitle = {Foundations of Intelligent Systems}, editor = {Helic, Denis and Leitner, Gerhard and Stettinger, Martin and Felfernig, Alexander and Ra{\'{s}}, Zbigniew W.}, keywords = 2020, pages = {431–439}, publisher = {Springer International Publishing}, title = {SimLoss: Class Similarities in Cross Entropy}, year = 2020 }
• Survey and Experimental Comparison of RGB-D Indoor Robot Navigation Methods Supported by ROS and Their Expansion via Fusion with Wheel Odometry and IMU Data. Spiess, Florian; Friesslich, Jonas; Tobias, Kaupp; Kounev, Samuel; Strobel, Norbert. In International Journal of Mechanical Engineering and Robotics Research (IJMERR), 9(12), P. R. (Chunhui) Yang (ed.), pp. 1532–1540. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper presents an experimental evaluation and comparison of selected Visual Odometry (VO) and Visual-SLAM (V-SLAM) algorithms for indoor mobile robot navigation supported by the Robot Operating System (ROS). The focus is on algorithms involving RGB-D cameras. Since RGB-D cameras integrate color and depth information, they output coherent measurement data and facilitate an efficient processing pipeline. The various underlying methods of vision-based algorithms are described and evaluated on two datasets covering different indoor situations as well as various lighting and movement conditions. In general, V-SLAM algorithms yielded better results. They were superior with respect to handling drift, in particular when loop closures were involved. However, the results confirmed that VO algorithms could outperform V-SLAM methods under certain circumstances. This happened when there was a very good match between an algorithm’s design objectives and the situation at hand. While the experiments showed that there is no single best algorithm for every scenario, ORB-SLAM2 is recommended as a robust stand-alone RGB-D based localization method available under ROS. Furthermore, we observed that the position estimation error could be reduced by around 67% on average when combining vision-based position estimates with sensor data obtained from wheel odometry and an inertial measurement unit (IMU), respectively. This clearly demonstrates the potential of sensor fusion techniques. The best results in case of sensor fusion were obtained with RGB-DSLAMv2.

  @article{yang2020survey, abstract = {This paper presents an experimental evaluation and comparison of selected Visual Odometry (VO) and Visual-SLAM (V-SLAM) algorithms for indoor mobile robot navigation supported by the Robot Operating System (ROS). The focus is on algorithms involving RGB-D cameras. Since RGB-D cameras integrate color and depth information, they output coherent measurement data and facilitate an efficient processing pipeline. The various underlying methods of vision-based algorithms are described and evaluated on two datasets covering different indoor situations as well as various lighting and movement conditions. In general, V-SLAM algorithms yielded better results. They were superior with respect to handling drift, in particular when loop closures were involved. However, the results confirmed that VO algorithms could outperform V-SLAM methods under certain circumstances. This happened when there was a very good match between an algorithm’s design objectives and the situation at hand. While the experiments showed that there is no single best algorithm for every scenario, ORB-SLAM2 is recommended as a robust stand-alone RGB-D based localization method available under ROS. Furthermore, we observed that the position estimation error could be reduced by around 67% on average when combining vision-based position estimates with sensor data obtained from wheel odometry and an inertial measurement unit (IMU), respectively. This clearly demonstrates the potential of sensor fusion techniques. The best results in case of sensor fusion were obtained with RGB-DSLAMv2.}, author = {Spiess, Florian and Friesslich, Jonas and Tobias, Kaupp and Kounev, Samuel and Strobel, Norbert}, editor = {Yang, Prof Richard (Chunhui)}, journal = {International Journal of Mechanical Engineering and Robotics Research (IJMERR)}, keywords = {rgb}, month = 12, number = 12, pages = {1532-1540}, title = {Survey and Experimental Comparison of RGB-D Indoor Robot Navigation Methods Supported by ROS and Their Expansion via Fusion with Wheel Odometry and IMU Data}, volume = 9, year = 2020 }
• Performance, Power, and Energy-Efficiency Impact Analysis of Compiler Optimizations on the SPEC CPU 2017 Benchmark Suite. Schmitt, Norbert; Bucek, James; Beckett, John; Cragin, Aaron; Lange, Klaus-Dieter; Kounev, Samuel. In 2020 IEEE/ACM 13th International Conference on Utility and Cloud Computing (UCC), pp. 292–301. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The growth of cloud services leads to more and more data centers that are increasingly larger and consume considerable amounts of power. To increase energy efficiency, both the actual server equipment and the software must become more energy efficient. Software has a major impact on hardware utilization levels, and subsequently, the energy efficiency. While energy efficiency is often seen as identical to performance, we argue that this may not be necessarily the case. A sizable amount of energy could be saved, increasing energy efficiency by leveraging compiler optimizations but at the same time impacting performance and power consumption over time. We analyze the SPEC CPU 2017 benchmark suite with 43 benchmarks from different domains, including integer and floating-point heavy computations on a state-of-the-art server system for cloud applications. Our results show that power consumption displays more stable behavior if less compiler optimizations are used and also confirmed that performance and energy efficiency are different optimizations goals. Additionally, compiler optimizations possibly could be used to enable power capping on a software level and care must be taken when selecting such optimizations.

  @inproceedings{9302787, abstract = {The growth of cloud services leads to more and more data centers that are increasingly larger and consume considerable amounts of power. To increase energy efficiency, both the actual server equipment and the software must become more energy efficient. Software has a major impact on hardware utilization levels, and subsequently, the energy efficiency. While energy efficiency is often seen as identical to performance, we argue that this may not be necessarily the case. A sizable amount of energy could be saved, increasing energy efficiency by leveraging compiler optimizations but at the same time impacting performance and power consumption over time. We analyze the SPEC CPU 2017 benchmark suite with 43 benchmarks from different domains, including integer and floating-point heavy computations on a state-of-the-art server system for cloud applications. Our results show that power consumption displays more stable behavior if less compiler optimizations are used and also confirmed that performance and energy efficiency are different optimizations goals. Additionally, compiler optimizations possibly could be used to enable power capping on a software level and care must be taken when selecting such optimizations.}, author = {Schmitt, Norbert and Bucek, James and Beckett, John and Cragin, Aaron and Lange, Klaus-Dieter and Kounev, Samuel}, booktitle = {2020 IEEE/ACM 13th International Conference on Utility and Cloud Computing (UCC)}, keywords = {power}, month = 12, pages = {292-301}, title = {Performance, Power, and Energy-Efficiency Impact Analysis of Compiler Optimizations on the SPEC CPU 2017 Benchmark Suite}, year = 2020 }
• Statistical Methods and Models based on Quality of Experience Distributions. Seufert, Michael. In Quality and User Experience, 6(1). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Due to biased assumptions on the underlying ordinal rating scale in subjective Quality of Experience (QoE) studies, Mean Opinion Score (MOS)-based evaluations provide results, which are hard to interpret and can be misleading. This paper proposes to consider the full QoE distribution for evaluating, reporting, and modeling QoE results instead of relying on MOS-based metrics derived from results based on ordinal rating scales. The QoE distribution can be represented in a concise way by using the parameters of a multinomial distribution without losing any information about the underlying QoE ratings, and even keeps backward compatibility with previous, biased MOS-based results. Considering QoE results as a realization of a multinomial distribution allows to rely on a well-established theoretical background, which enables meaningful evaluations also for ordinal rating scales. Moreover, QoE models based on QoE distributions keep detailed information from the results of a QoE study of a technical system, and thus, give an unprecedented richness of insights into the end users’ experience with the technical system. In this work, existing and novel statistical methods for QoE distributions are summarized and exemplary evaluations are outlined. Furthermore, using the novel concept of quality steps, simulative and analytical QoE models based on QoE distributions are presented and showcased. The goal is to demonstrate the fundamental advantages of considering QoE distributions over MOS-based evaluations if the underlying rating data is ordinal in nature.

  @article{info3-article-2020-7, abstract = {Due to biased assumptions on the underlying ordinal rating scale in subjective Quality of Experience (QoE) studies, Mean Opinion Score (MOS)-based evaluations provide results, which are hard to interpret and can be misleading. This paper proposes to consider the full QoE distribution for evaluating, reporting, and modeling QoE results instead of relying on MOS-based metrics derived from results based on ordinal rating scales. The QoE distribution can be represented in a concise way by using the parameters of a multinomial distribution without losing any information about the underlying QoE ratings, and even keeps backward compatibility with previous, biased MOS-based results. Considering QoE results as a realization of a multinomial distribution allows to rely on a well-established theoretical background, which enables meaningful evaluations also for ordinal rating scales. Moreover, QoE models based on QoE distributions keep detailed information from the results of a QoE study of a technical system, and thus, give an unprecedented richness of insights into the end users’ experience with the technical system. In this work, existing and novel statistical methods for QoE distributions are summarized and exemplary evaluations are outlined. Furthermore, using the novel concept of quality steps, simulative and analytical QoE models based on QoE distributions are presented and showcased. The goal is to demonstrate the fundamental advantages of considering QoE distributions over MOS-based evaluations if the underlying rating data is ordinal in nature.}, author = {Seufert, Michael}, journal = {Quality and User Experience}, keywords = {ucn}, month = 12, number = 1, title = {Statistical Methods and Models based on Quality of Experience Distributions}, volume = 6, year = 2020 }
• ViCrypt to the Rescue: Real-time, Machine-Learning-driven Video-QoE Monitoring for Encrypted Streaming Traffic. Wassermann, Sarah; Seufert, Michael; Casas, Pedro; Li, Gang; Kuang, Li. In IEEE Transactions on Network and Service Management, 17(4), pp. 2007–2023. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Video streaming is the killer application of the Internet today. In this paper, we address the problem of real-time, passive Quality-of-Experience (QoE) monitoring of HTTP Adaptive Video Streaming (HAS), from the Internet-Service-Provider (ISP) perspective - i.e., relying exclusively on in-network traffic measurements. Given the wide adoption of end-to-end encryption, we resort to machine-learning (ML) models to estimate multiple key video-QoE indicators (KQIs) from the analysis of the encrypted traffic. We present ViCrypt, an ML-driven monitoring solution able to infer the most important KQIs for HTTP Adaptive Streaming (HAS), namely stalling, initial delay, video resolution, and average video bitrate. ViCrypt performs estimations in real-time, during the playback of an ongoing video-streaming session, with a fine-grained temporal resolution of just one second. For this, it relies on lightweight, stream-like features continuously extracted from the encrypted stream of packets. Empirical evaluations on a large and heterogeneous corpus of YouTube measurements show that ViCrypt can infer the targeted KQIs with high accuracy, enabling large-scale passive video-QoE monitoring and proactive QoE-aware traffic management. Different from the state of the art, and besides real-time operation, ViCrypt is not bound to coarse-grained KQI-classes, providing better and sharper insights than other solutions. Finally, ViCrypt does not require chunk-detection approaches for feature extraction, significantly reducing the complexity of the monitoring approach, and potentially improving on generalization to different HAS protocols used by other video-streaming services such as Netflix and Amazon.

  @article{info3-article-2020-5, abstract = {Video streaming is the killer application of the Internet today. In this paper, we address the problem of real-time, passive Quality-of-Experience (QoE) monitoring of HTTP Adaptive Video Streaming (HAS), from the Internet-Service-Provider (ISP) perspective - i.e., relying exclusively on in-network traffic measurements. Given the wide adoption of end-to-end encryption, we resort to machine-learning (ML) models to estimate multiple key video-QoE indicators (KQIs) from the analysis of the encrypted traffic. We present ViCrypt, an ML-driven monitoring solution able to infer the most important KQIs for HTTP Adaptive Streaming (HAS), namely stalling, initial delay, video resolution, and average video bitrate. ViCrypt performs estimations in real-time, during the playback of an ongoing video-streaming session, with a fine-grained temporal resolution of just one second. For this, it relies on lightweight, stream-like features continuously extracted from the encrypted stream of packets. Empirical evaluations on a large and heterogeneous corpus of YouTube measurements show that ViCrypt can infer the targeted KQIs with high accuracy, enabling large-scale passive video-QoE monitoring and proactive QoE-aware traffic management. Different from the state of the art, and besides real-time operation, ViCrypt is not bound to coarse-grained KQI-classes, providing better and sharper insights than other solutions. Finally, ViCrypt does not require chunk-detection approaches for feature extraction, significantly reducing the complexity of the monitoring approach, and potentially improving on generalization to different HAS protocols used by other video-streaming services such as Netflix and Amazon.}, author = {Wassermann, Sarah and Seufert, Michael and Casas, Pedro and Li, Gang and Kuang, Li}, journal = {IEEE Transactions on Network and Service Management}, keywords = {ucn}, month = 12, number = 4, pages = {2007 - 2023}, title = {ViCrypt to the Rescue: Real-time, Machine-Learning-driven Video-QoE Monitoring for Encrypted Streaming Traffic}, volume = 17, year = 2020 }
• Survey and Experimental Comparison of RGB-D Indoor Robot Navigation Methods Supported by ROS and Their Expansion via Fusion with Wheel Odometry and IMU Data. Spiess, Florian; Friesslich, Jonas; Tobias, Kaupp; Kounev, Samuel; Strobel, Norbert. In International Journal of Mechanical Engineering and Robotics Research (IJMERR), 9(12), P. R. (Chunhui) Yang (ed.), pp. 1532–1540. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper presents an experimental evaluation and comparison of selected Visual Odometry (VO) and Visual-SLAM (V-SLAM) algorithms for indoor mobile robot navigation supported by the Robot Operating System (ROS). The focus is on algorithms involving RGB-D cameras. Since RGB-D cameras integrate color and depth information, they output coherent measurement data and facilitate an efficient processing pipeline. The various underlying methods of vision-based algorithms are described and evaluated on two datasets covering different indoor situations as well as various lighting and movement conditions. In general, V-SLAM algorithms yielded better results. They were superior with respect to handling drift, in particular when loop closures were involved. However, the results confirmed that VO algorithms could outperform V-SLAM methods under certain circumstances. This happened when there was a very good match between an algorithm’s design objectives and the situation at hand. While the experiments showed that there is no single best algorithm for every scenario, ORB-SLAM2 is recommended as a robust stand-alone RGB-D based localization method available under ROS. Furthermore, we observed that the position estimation error could be reduced by around 67% on average when combining vision-based position estimates with sensor data obtained from wheel odometry and an inertial measurement unit (IMU), respectively. This clearly demonstrates the potential of sensor fusion techniques. The best results in case of sensor fusion were obtained with RGB-DSLAMv2.

  @article{yang2020survey, abstract = {This paper presents an experimental evaluation and comparison of selected Visual Odometry (VO) and Visual-SLAM (V-SLAM) algorithms for indoor mobile robot navigation supported by the Robot Operating System (ROS). The focus is on algorithms involving RGB-D cameras. Since RGB-D cameras integrate color and depth information, they output coherent measurement data and facilitate an efficient processing pipeline. The various underlying methods of vision-based algorithms are described and evaluated on two datasets covering different indoor situations as well as various lighting and movement conditions. In general, V-SLAM algorithms yielded better results. They were superior with respect to handling drift, in particular when loop closures were involved. However, the results confirmed that VO algorithms could outperform V-SLAM methods under certain circumstances. This happened when there was a very good match between an algorithm’s design objectives and the situation at hand. While the experiments showed that there is no single best algorithm for every scenario, ORB-SLAM2 is recommended as a robust stand-alone RGB-D based localization method available under ROS. Furthermore, we observed that the position estimation error could be reduced by around 67% on average when combining vision-based position estimates with sensor data obtained from wheel odometry and an inertial measurement unit (IMU), respectively. This clearly demonstrates the potential of sensor fusion techniques. The best results in case of sensor fusion were obtained with RGB-DSLAMv2.}, author = {Spiess, Florian and Friesslich, Jonas and Tobias, Kaupp and Kounev, Samuel and Strobel, Norbert}, editor = {Yang, Prof Richard (Chunhui)}, journal = {International Journal of Mechanical Engineering and Robotics Research (IJMERR)}, keywords = {rgb}, month = 12, number = 12, pages = {1532-1540}, title = {Survey and Experimental Comparison of RGB-D Indoor Robot Navigation Methods Supported by ROS and Their Expansion via Fusion with Wheel Odometry and IMU Data}, volume = 9, year = 2020 }
• Baloo: Measuring and Modeling the Performance Configurations of Distributed DBMS. Grohmann, Johannes; Seybold, Daniel; Eismann, Simon; Leznik, Mark; Kounev, Samuel; Domaschka, Jörg. In 2020 28th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS), of MASCOTS ’20, pp. 1–8. IEEE, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Correctly configuring a distributed database management system (DBMS) deployed in a cloud environment for maximizing performance poses many challenges to operators. Even if the entire configuration spectrum could be measured directly, which is often infeasible due to the multitude of parameters, single measurements are subject to random variations and need to be repeated multiple times. In this work, we propose Baloo, a framework for systematically measuring and modeling different performance-relevant configurations of distributed DBMS in cloud environments. Baloo dynamically estimates the required number of configurations, as well as the number of required measurement repetitions per configuration based on a desired target accuracy. We evaluate Baloo based on a data set consisting of 900 DBMS configuration measurements conducted in our private cloud setup. Our evaluation shows that the highly configurable framework is able to achieve a prediction error of up to 12% while saving 80% of the measurement effort. We also publish all code and the acquired data set to foster future research.

  @inproceedings{GrSeEiLeKoDo2020-MASCOTS-DBMSPerformance, abstract = {Correctly configuring a distributed database management system (DBMS) deployed in a cloud environment for maximizing performance poses many challenges to operators. Even if the entire configuration spectrum could be measured directly, which is often infeasible due to the multitude of parameters, single measurements are subject to random variations and need to be repeated multiple times. In this work, we propose Baloo, a framework for systematically measuring and modeling different performance-relevant configurations of distributed DBMS in cloud environments. Baloo dynamically estimates the required number of configurations, as well as the number of required measurement repetitions per configuration based on a desired target accuracy. We evaluate Baloo based on a data set consisting of 900 DBMS configuration measurements conducted in our private cloud setup. Our evaluation shows that the highly configurable framework is able to achieve a prediction error of up to 12% while saving 80% of the measurement effort. We also publish all code and the acquired data set to foster future research.}, author = {Grohmann, Johannes and Seybold, Daniel and Eismann, Simon and Leznik, Mark and Kounev, Samuel and Domaschka, Jörg}, booktitle = {2020 28th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS)}, keywords = {automated_model_learning}, month = 11, note = {Acceptance Rate: 27%}, pages = {1–8}, publisher = {IEEE}, series = {MASCOTS '20}, title = {Baloo: Measuring and Modeling the Performance Configurations of Distributed DBMS}, year = 2020 }
• Evaluating the Performance of a State-of-the-Art Group-oriented Encryption Scheme for Dynamic Groups in an IoT Scenario. Prantl, Thomas; Ten, Peter; Iffländer, Lukas; Dmitrenko, Alexandra; Kounev, Samuel; Krupitzer, Christian. In 2020 IEEE 28th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS), of MASCOTS ’20. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  New emerging technologies, such as autonomous driving, intelligent buildings, and smart cities, are promising to revolutionize user experience and offer new services. The world has to undergo large scale deployment of billions of things — cost-efficient intelligent sensors that will be interconnected into extensive networks and will collect and supply data to intelligent algorithms — to make it happen. To date, however, it is challenging to secure such an infrastructure for many-fold reasons, such as resource constraints of things, large scale deployment, manyto-many communication patterns, and dynamically changing communication groups. All these factors rule out most of the state-of-the-art encryption and key-management techniques. Group encryption algorithms are well-suitable for many-tomany communication patterns typical for IoT networks, and many of them can deal with dynamic groups. There are, however, very few constructions that could potentially fulfill the computational and storage constraints of IoT devices while providing sufficient scalability for large networks. The promising candidates, such as construction by Nishat et al. [1], were not evaluated using IoT platforms and under constraints typical for IoT networks. In this paper, we aim to fill this gap and present the evaluation of a state-of-the-art group-oriented encryption scheme by Nishat et al. to identify its applicability to IoT systems. In detail, we provide a measurement workflow, a revised version of the approach, and describe a reproducible hardware testbed. Using this evaluation environment, we analyze the performance of the encryption scheme in a typical IoT scenario from a group member perspective. The results show that all calculation times can be assumed to be constant and are always below 2 seconds. The memory requirement for permanent parameters can also be considered to be constant and are below 8.5 kbit in each case. However, the information that has to be stored temporarily for group updates has turned out to be the bottleneck of the scheme, since their memory requirements increase linearly with the group size.

  @inproceedings{PrTeIfDmKo2020-MASCOTS-GroupEncryption, abstract = {New emerging technologies, such as autonomous driving, intelligent buildings, and smart cities, are promising to revolutionize user experience and offer new services. The world has to undergo large scale deployment of billions of things — cost-efficient intelligent sensors that will be interconnected into extensive networks and will collect and supply data to intelligent algorithms — to make it happen. To date, however, it is challenging to secure such an infrastructure for many-fold reasons, such as resource constraints of things, large scale deployment, manyto-many communication patterns, and dynamically changing communication groups. All these factors rule out most of the state-of-the-art encryption and key-management techniques. Group encryption algorithms are well-suitable for many-tomany communication patterns typical for IoT networks, and many of them can deal with dynamic groups. There are, however, very few constructions that could potentially fulfill the computational and storage constraints of IoT devices while providing sufficient scalability for large networks. The promising candidates, such as construction by Nishat et al. [1], were not evaluated using IoT platforms and under constraints typical for IoT networks. In this paper, we aim to fill this gap and present the evaluation of a state-of-the-art group-oriented encryption scheme by Nishat et al. to identify its applicability to IoT systems. In detail, we provide a measurement workflow, a revised version of the approach, and describe a reproducible hardware testbed. Using this evaluation environment, we analyze the performance of the encryption scheme in a typical IoT scenario from a group member perspective. The results show that all calculation times can be assumed to be constant and are always below 2 seconds. The memory requirement for permanent parameters can also be considered to be constant and are below 8.5 kbit in each case. However, the information that has to be stored temporarily for group updates has turned out to be the bottleneck of the scheme, since their memory requirements increase linearly with the group size.}, author = {Prantl, Thomas and Ten, Peter and Iffländer, Lukas and Dmitrenko, Alexandra and Kounev, Samuel and Krupitzer, Christian}, booktitle = {2020 IEEE 28th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS)}, keywords = {Performance_Evaluation}, month = 11, note = {Acceptance Rate: 27\%}, series = {MASCOTS '20}, title = {Evaluating the Performance of a State-of-the-Art Group-oriented Encryption Scheme for Dynamic Groups in an IoT Scenario}, year = 2020 }
• Where to Submit? Helping Researchers to Choose the Right Venue. Kobs, Konstantin; Koopmann, Tobias; Zehe, Albin; Fernes, David; Krop, Philipp; Hotho, Andreas. In Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing: Findings, pp. 878–883. Association for Computational Linguistics, Online, 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{kobs-etal-2020-submit, address = {Online}, author = {Kobs, Konstantin and Koopmann, Tobias and Zehe, Albin and Fernes, David and Krop, Philipp and Hotho, Andreas}, booktitle = {Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing: Findings}, keywords = {myown}, month = 11, pages = {878–883}, publisher = {Association for Computational Linguistics}, title = {Where to Submit? Helping Researchers to Choose the Right Venue}, year = 2020 }
• Scoring High: Analysis and Prediction of Viewer Behavior and Engagement in the Context of 2018 FIFA WC Live Streaming. Wehner, Nikolas; Seufert, Michael; Egger-Lampl, Sebastian; Gardlo, Bruno; Casas, Pedro; Schatz, Raimund. In Proceedings of the 28th ACM International Conference on Multimedia (MM). Seattle, WA, USA, 2020.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2020-9, address = {Seattle, WA, USA}, author = {Wehner, Nikolas and Seufert, Michael and Egger-Lampl, Sebastian and Gardlo, Bruno and Casas, Pedro and Schatz, Raimund}, booktitle = {Proceedings of the 28th ACM International Conference on Multimedia (MM)}, keywords = {ucn}, month = 10, title = {Scoring High: Analysis and Prediction of Viewer Behavior and Engagement in the Context of 2018 FIFA WC Live Streaming}, year = 2020 }
• Improving Web QoE Monitoring for Encrypted Network Traffic through Time Series Modeling. Wehner, Nikolas; Seufert, Michael; Schüler, Joshua; Wassermann, Sarah; Casas, Pedro; Hoßfeld, Tobias. In 2nd Workshop on AI in Networks and Distributed Systems (WAIN). Milan, Italy, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  This paper addresses the problem of Quality of Experience (QoE) monitoring for web browsing. In particular, the inference of common Web QoE metrics such as Speed Index (SI) is investigated. Based on a large dataset collected with open web-measurement platforms on different device-types, a unique feature set is designed and used to estimate the RUMSI -- an efficient approximation to SI, with machine-learning based regression and classification approaches. Results indicate that it is possible to estimate the RUMSI accurately, and that in particular, recurrent neural networks are highly suitable for the task, as they capture the network dynamics more precisely.

  @inproceedings{info3-inproceedings-2020-12, abstract = {This paper addresses the problem of Quality of Experience (QoE) monitoring for web browsing. In particular, the inference of common Web QoE metrics such as Speed Index (SI) is investigated. Based on a large dataset collected with open web-measurement platforms on different device-types, a unique feature set is designed and used to estimate the RUMSI – an efficient approximation to SI, with machine-learning based regression and classification approaches. Results indicate that it is possible to estimate the RUMSI accurately, and that in particular, recurrent neural networks are highly suitable for the task, as they capture the network dynamics more precisely.}, address = {Milan, Italy}, author = {Wehner, Nikolas and Seufert, Michael and Schüler, Joshua and Wassermann, Sarah and Casas, Pedro and Hoßfeld, Tobias}, booktitle = {2nd Workshop on AI in Networks and Distributed Systems (WAIN)}, keywords = {ucn}, month = 11, title = {Improving Web QoE Monitoring for Encrypted Network Traffic through Time Series Modeling}, year = 2020 }
• In vitro vs in vivo: does the study’s interface design influence crowdsourced video QoE?. Borchert, Kathrin; Seufert, Anika; Gamboa, Edwin; Hirth, Matthias; Hoßfeld, Tobias. In Quality and User Experience. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Evaluating the Quality of Experience (QoE) of video streaming and its influence factors has become paramount for streaming providers, as they want to maintain high satisfaction for their customers. In this context, crowdsourced user studies became a valuable tool to evaluate different factors which can affect the perceived user experience on a large scale. In general, most of these crowdsourcing studies either use, what we refer to, as an in vivo or an in vitro interface design. In vivo design means that the study participant has to rate the QoE of a video that is embedded in an application similar to a real streaming service, e.g., YouTube or Netflix. In vitro design refers to a setting, in which the video stream is separated from a specific service and thus, the video plays on a plain background. Although these interface designs vary widely, the results are often compared and generalized. In this work, we use a crowdsourcing study to investigate the influence of three interface design alternatives, an in vitro and two in vivo designs with different levels of interactiveness, on the perceived video QoE. Contrary to our expectations, the results indicate that there is no significant influence of the study’s interface design in general on the video experience. Furthermore, we found that the in vivo design does not reduce the test takers’ attentiveness. However, we observed that participants who interacted with the test interface reported a higher video QoE than other groups.

  @article{info3-article-2020-6, abstract = {Evaluating the Quality of Experience (QoE) of video streaming and its influence factors has become paramount for streaming providers, as they want to maintain high satisfaction for their customers. In this context, crowdsourced user studies became a valuable tool to evaluate different factors which can affect the perceived user experience on a large scale. In general, most of these crowdsourcing studies either use, what we refer to, as an in vivo or an in vitro interface design. In vivo design means that the study participant has to rate the QoE of a video that is embedded in an application similar to a real streaming service, e.g., YouTube or Netflix. In vitro design refers to a setting, in which the video stream is separated from a specific service and thus, the video plays on a plain background. Although these interface designs vary widely, the results are often compared and generalized. In this work, we use a crowdsourcing study to investigate the influence of three interface design alternatives, an in vitro and two in vivo designs with different levels of interactiveness, on the perceived video QoE. Contrary to our expectations, the results indicate that there is no significant influence of the study’s interface design in general on the video experience. Furthermore, we found that the in vivo design does not reduce the test takers’ attentiveness. However, we observed that participants who interacted with the test interface reported a higher video QoE than other groups.}, author = {Borchert, Kathrin and Seufert, Anika and Gamboa, Edwin and Hirth, Matthias and Hoßfeld, Tobias}, journal = {Quality and User Experience}, keywords = {ua-net}, month = 11, title = {In vitro vs in vivo: does the study’s interface design influence crowdsourced video QoE?}, year = 2020 }
• Evaluating the Performance of a State-of-the-Art Group-oriented Encryption Scheme for Dynamic Groups in an IoT Scenario. Prantl, Thomas; Ten, Peter; Iffländer, Lukas; Dmitrenko, Alexandra; Kounev, Samuel; Krupitzer, Christian. In 2020 IEEE 28th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS), of MASCOTS ’20. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  New emerging technologies, such as autonomous driving, intelligent buildings, and smart cities, are promising to revolutionize user experience and offer new services. The world has to undergo large scale deployment of billions of things — cost-efficient intelligent sensors that will be interconnected into extensive networks and will collect and supply data to intelligent algorithms — to make it happen. To date, however, it is challenging to secure such an infrastructure for many-fold reasons, such as resource constraints of things, large scale deployment, manyto-many communication patterns, and dynamically changing communication groups. All these factors rule out most of the state-of-the-art encryption and key-management techniques. Group encryption algorithms are well-suitable for many-tomany communication patterns typical for IoT networks, and many of them can deal with dynamic groups. There are, however, very few constructions that could potentially fulfill the computational and storage constraints of IoT devices while providing sufficient scalability for large networks. The promising candidates, such as construction by Nishat et al. [1], were not evaluated using IoT platforms and under constraints typical for IoT networks. In this paper, we aim to fill this gap and present the evaluation of a state-of-the-art group-oriented encryption scheme by Nishat et al. to identify its applicability to IoT systems. In detail, we provide a measurement workflow, a revised version of the approach, and describe a reproducible hardware testbed. Using this evaluation environment, we analyze the performance of the encryption scheme in a typical IoT scenario from a group member perspective. The results show that all calculation times can be assumed to be constant and are always below 2 seconds. The memory requirement for permanent parameters can also be considered to be constant and are below 8.5 kbit in each case. However, the information that has to be stored temporarily for group updates has turned out to be the bottleneck of the scheme, since their memory requirements increase linearly with the group size.

  @inproceedings{PrTeIfDmKo2020-MASCOTS-GroupEncryption, abstract = {New emerging technologies, such as autonomous driving, intelligent buildings, and smart cities, are promising to revolutionize user experience and offer new services. The world has to undergo large scale deployment of billions of things — cost-efficient intelligent sensors that will be interconnected into extensive networks and will collect and supply data to intelligent algorithms — to make it happen. To date, however, it is challenging to secure such an infrastructure for many-fold reasons, such as resource constraints of things, large scale deployment, manyto-many communication patterns, and dynamically changing communication groups. All these factors rule out most of the state-of-the-art encryption and key-management techniques. Group encryption algorithms are well-suitable for many-tomany communication patterns typical for IoT networks, and many of them can deal with dynamic groups. There are, however, very few constructions that could potentially fulfill the computational and storage constraints of IoT devices while providing sufficient scalability for large networks. The promising candidates, such as construction by Nishat et al. [1], were not evaluated using IoT platforms and under constraints typical for IoT networks. In this paper, we aim to fill this gap and present the evaluation of a state-of-the-art group-oriented encryption scheme by Nishat et al. to identify its applicability to IoT systems. In detail, we provide a measurement workflow, a revised version of the approach, and describe a reproducible hardware testbed. Using this evaluation environment, we analyze the performance of the encryption scheme in a typical IoT scenario from a group member perspective. The results show that all calculation times can be assumed to be constant and are always below 2 seconds. The memory requirement for permanent parameters can also be considered to be constant and are below 8.5 kbit in each case. However, the information that has to be stored temporarily for group updates has turned out to be the bottleneck of the scheme, since their memory requirements increase linearly with the group size.}, author = {Prantl, Thomas and Ten, Peter and Iffländer, Lukas and Dmitrenko, Alexandra and Kounev, Samuel and Krupitzer, Christian}, booktitle = {2020 IEEE 28th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS)}, keywords = {Performance_Evaluation}, month = 11, note = {Acceptance Rate: 27\%}, series = {MASCOTS '20}, title = {Evaluating the Performance of a State-of-the-Art Group-oriented Encryption Scheme for Dynamic Groups in an IoT Scenario}, year = 2020 }
• Baloo: Measuring and Modeling the Performance Configurations of Distributed DBMS. Grohmann, Johannes; Seybold, Daniel; Eismann, Simon; Leznik, Mark; Kounev, Samuel; Domaschka, Jörg. In 2020 28th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS), of MASCOTS ’20, pp. 1–8. IEEE, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Correctly configuring a distributed database management system (DBMS) deployed in a cloud environment for maximizing performance poses many challenges to operators. Even if the entire configuration spectrum could be measured directly, which is often infeasible due to the multitude of parameters, single measurements are subject to random variations and need to be repeated multiple times. In this work, we propose Baloo, a framework for systematically measuring and modeling different performance-relevant configurations of distributed DBMS in cloud environments. Baloo dynamically estimates the required number of configurations, as well as the number of required measurement repetitions per configuration based on a desired target accuracy. We evaluate Baloo based on a data set consisting of 900 DBMS configuration measurements conducted in our private cloud setup. Our evaluation shows that the highly configurable framework is able to achieve a prediction error of up to 12% while saving 80% of the measurement effort. We also publish all code and the acquired data set to foster future research.

  @inproceedings{GrSeEiLeKoDo2020-MASCOTS-DBMSPerformance, abstract = {Correctly configuring a distributed database management system (DBMS) deployed in a cloud environment for maximizing performance poses many challenges to operators. Even if the entire configuration spectrum could be measured directly, which is often infeasible due to the multitude of parameters, single measurements are subject to random variations and need to be repeated multiple times. In this work, we propose Baloo, a framework for systematically measuring and modeling different performance-relevant configurations of distributed DBMS in cloud environments. Baloo dynamically estimates the required number of configurations, as well as the number of required measurement repetitions per configuration based on a desired target accuracy. We evaluate Baloo based on a data set consisting of 900 DBMS configuration measurements conducted in our private cloud setup. Our evaluation shows that the highly configurable framework is able to achieve a prediction error of up to 12% while saving 80% of the measurement effort. We also publish all code and the acquired data set to foster future research.}, author = {Grohmann, Johannes and Seybold, Daniel and Eismann, Simon and Leznik, Mark and Kounev, Samuel and Domaschka, Jörg}, booktitle = {2020 28th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS)}, keywords = {automated_model_learning}, month = 11, note = {Acceptance Rate: 27%}, pages = {1–8}, publisher = {IEEE}, series = {MASCOTS '20}, title = {Baloo: Measuring and Modeling the Performance Configurations of Distributed DBMS}, year = 2020 }
• Mind the (QoE) Gap: On the Incompatibility of Web and Video QoE Models in the Wild. Seufert, Michael; Wehner, Nikolas; Wieser, Viktoria; Casas, Pedro; Capdehourat, Germán. In 16th International Conference on Network and Service Management (CNSM). Izmir, Turkey, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Education Service Providers (ESPs) have a paramount role in the digitization of education, providing reliable devices for students and teachers and high quality Internet access at schools. In this paper, a large-scale, passive, in-device Quality of Experience (QoE) monitoring system is presented, which was deployed into a nationwide network of education-purpose devices. Four months' worth of continuous measurements were conducted by an ESP, covering more than 800 education centers and about 4000 devices, used both in schools and at home. When analyzing the QoE of web sessions in school networks, we identify a fundamental issue with the compatibility of web browsing and video QoE models, which inhibits the successful application of QoE-aware network management for multiple services.

  @inproceedings{info3-inproceedings-2020-11, abstract = {Education Service Providers (ESPs) have a paramount role in the digitization of education, providing reliable devices for students and teachers and high quality Internet access at schools. In this paper, a large-scale, passive, in-device Quality of Experience (QoE) monitoring system is presented, which was deployed into a nationwide network of education-purpose devices. Four months' worth of continuous measurements were conducted by an ESP, covering more than 800 education centers and about 4000 devices, used both in schools and at home. When analyzing the QoE of web sessions in school networks, we identify a fundamental issue with the compatibility of web browsing and video QoE models, which inhibits the successful application of QoE-aware network management for multiple services.}, address = {Izmir, Turkey}, author = {Seufert, Michael and Wehner, Nikolas and Wieser, Viktoria and Casas, Pedro and Capdehourat, Germán}, booktitle = {16th International Conference on Network and Service Management (CNSM)}, keywords = {ucn}, month = 11, title = {Mind the (QoE) Gap: On the Incompatibility of Web and Video QoE Models in the Wild}, year = 2020 }
• Are you on Mobile or Desktop? On the Impact of End-User Device on Web QoE Inference from Encrypted Traffic. Wassermann, Sarah; Casas, Pedro; Ben Houidi, Zied; Huet, Alexis; Seufert, Michael; Wehner, Nikolas; Schüler, Joshua; Cai, Sheng-Ming; Shi, Hao; Xu, Jinchun; Hoßfeld, Tobias; Rossi, Dario. In 16th International Conference on Network and Service Management (CNSM). Izmir, Turkey, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Web browsing is one of the key applications of the Internet, if not the most important one. We address the problem of Web Quality of Experience (QoE) monitoring from the ISP perspective, relying on in-network, passive measurements. As a proxy to Web QoE, we focus on the analysis of the well-known SpeedIndex (SI) metric. Given the lack of app-level data visibility introduced by the wide adoption of end-to-end encryption, we resort to machine-learning models to infer the SI and the QoE level of individual web page loading sessions, using as input only packet- and flow-level data. Our study targets the impact of different end-user device types (e.g., smartphone, desktop, tablet) on the performance of such models. Empirical evaluations on a large, multi-device, heterogeneous corpus of Web QoE measurements for top popular websites demonstrate that the proposed solution can infer the SI as well as estimate QoE ranges with high accuracy, using either packet-level or flow-level measurements. In addition, we show that the device type adds a strong bias in the feasibility of these Web QoE models, putting into question the applicability of previously conceived approaches on single-device measurements. To improve the state of affairs, we conceive cross-device generalizable models operating at both packet and flow levels, offering a feasible solution for Web QoE monitoring in operational, multi-device networks. To the best of our knowledge, this is the first study tackling the analysis of Web QoE from encrypted network traffic in multi-device scenarios.

  @inproceedings{info3-inproceedings-2020-10, abstract = {Web browsing is one of the key applications of the Internet, if not the most important one. We address the problem of Web Quality of Experience (QoE) monitoring from the ISP perspective, relying on in-network, passive measurements. As a proxy to Web QoE, we focus on the analysis of the well-known SpeedIndex (SI) metric. Given the lack of app-level data visibility introduced by the wide adoption of end-to-end encryption, we resort to machine-learning models to infer the SI and the QoE level of individual web page loading sessions, using as input only packet- and flow-level data. Our study targets the impact of different end-user device types (e.g., smartphone, desktop, tablet) on the performance of such models. Empirical evaluations on a large, multi-device, heterogeneous corpus of Web QoE measurements for top popular websites demonstrate that the proposed solution can infer the SI as well as estimate QoE ranges with high accuracy, using either packet-level or flow-level measurements. In addition, we show that the device type adds a strong bias in the feasibility of these Web QoE models, putting into question the applicability of previously conceived approaches on single-device measurements. To improve the state of affairs, we conceive cross-device generalizable models operating at both packet and flow levels, offering a feasible solution for Web QoE monitoring in operational, multi-device networks. To the best of our knowledge, this is the first study tackling the analysis of Web QoE from encrypted network traffic in multi-device scenarios.}, address = {Izmir, Turkey}, author = {Wassermann, Sarah and Casas, Pedro and Ben Houidi, Zied and Huet, Alexis and Seufert, Michael and Wehner, Nikolas and Schüler, Joshua and Cai, Sheng-Ming and Shi, Hao and Xu, Jinchun and Hoßfeld, Tobias and Rossi, Dario}, booktitle = {16th International Conference on Network and Service Management (CNSM)}, keywords = {ucn}, month = 11, title = {Are you on Mobile or Desktop? On the Impact of End-User Device on Web QoE Inference from Encrypted Traffic}, year = 2020 }
• Bounded Latency with Bridge-Local Stream Reservation and Strict Priority Queuing. Grigorjew, Alexej; Metzger, Florian; Hoßfeld, Tobias; Specht, Johannes; Götz, Franz-Josef; Chen, Feng; Schmitt, Jürgen. In 11th International Conference on Network of the Future (NoF). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Bridge-local latency computation is often regarded with caution, while new shaping mechanisms and timed gates are developed to achieve deterministic guarantees. However, these new concepts require additional hardware support in the forwarding devices, and many of them are based on assumptions of central control and network-wide information being available. This document presents a per-hop latency bound for individual streams in a class-based network that applies the IEEE 802.1Q strict priority transmission selection algorithm. It does not rely on shaping or timed gates and uses the accumulated latency fields during the reservation process to provide upper bounds with bridge-local information. The presented delay bound is proven formally and then evaluated with respect to its accuracy. It shows that deterministic latency with priority queuing is indeed feasible, and it indicates the required information that must be provided during resource reservation, e.g., to protocols developed in IEEE 802.1Qdd.

  @inproceedings{info3-inproceedings-2020-17, abstract = {Bridge-local latency computation is often regarded with caution, while new shaping mechanisms and timed gates are developed to achieve deterministic guarantees. However, these new concepts require additional hardware support in the forwarding devices, and many of them are based on assumptions of central control and network-wide information being available. This document presents a per-hop latency bound for individual streams in a class-based network that applies the IEEE 802.1Q strict priority transmission selection algorithm. It does not rely on shaping or timed gates and uses the accumulated latency fields during the reservation process to provide upper bounds with bridge-local information. The presented delay bound is proven formally and then evaluated with respect to its accuracy. It shows that deterministic latency with priority queuing is indeed feasible, and it indicates the required information that must be provided during resource reservation, e.g., to protocols developed in IEEE 802.1Qdd.}, author = {Grigorjew, Alexej and Metzger, Florian and Hoßfeld, Tobias and Specht, Johannes and Götz, Franz-Josef and Chen, Feng and Schmitt, Jürgen}, booktitle = {11th International Conference on Network of the Future (NoF)}, keywords = {ats-performance}, month = 11, title = {Bounded Latency with Bridge-Local Stream Reservation and Strict Priority Queuing}, year = 2020 }
• Scoring High: Analysis and Prediction of Viewer Behavior and Engagement in the Context of 2018 FIFA WC Live Streaming. Wehner, Nikolas. Proceedings of the 28th ACM International Conference on Multimedia (MM), Seattle, WA, USA, 2020, October 12.
  • [ Abstract ]
  • [ BibTeX ]
  Large-scale events pose severe challenges to live video streaming service providers, who need to cope with high, peaking viewer numbers and the resulting fluctuating resource demands, keeping high levels of Quality of Experience (QoE) to avoid end-user frustration and churn. In this paper, we analyze a unique dataset consisting of more than a million 2018 FIFA World Cup mobile live streaming sessions, collected at a large national public broadcaster. Different from previous work, we analyze QoE and user engagement as well as their interaction, in dependency to specific soccer match events, which have the potential to trigger flash crowds during a match. Flash crowds are a particular challenge to video service providers, since they cause sudden load peaks and consequently, the likelihood of quality problems. We further exploit the data to model viewer engagement over the course of a soccer match, and show that client counts follow very similar patterns of change across all matches. We believe that the analysis as well as the resulting models are valuable sources of insight for service providers, equipping them with tools for customer-centric resource and capacity management.

  @presentation{info3-presentation-2020-4, abstract = {Large-scale events pose severe challenges to live video streaming service providers, who need to cope with high, peaking viewer numbers and the resulting fluctuating resource demands, keeping high levels of Quality of Experience (QoE) to avoid end-user frustration and churn. In this paper, we analyze a unique dataset consisting of more than a million 2018 FIFA World Cup mobile live streaming sessions, collected at a large national public broadcaster. Different from previous work, we analyze QoE and user engagement as well as their interaction, in dependency to specific soccer match events, which have the potential to trigger flash crowds during a match. Flash crowds are a particular challenge to video service providers, since they cause sudden load peaks and consequently, the likelihood of quality problems. We further exploit the data to model viewer engagement over the course of a soccer match, and show that client counts follow very similar patterns of change across all matches. We believe that the analysis as well as the resulting models are valuable sources of insight for service providers, equipping them with tools for customer-centric resource and capacity management.}, address = {Proceedings of the 28th ACM International Conference on Multimedia (MM), Seattle, WA, USA}, author = {Wehner, Nikolas}, keywords = {myown}, month = 10, title = {Scoring High: Analysis and Prediction of Viewer Behavior and Engagement in the Context of 2018 FIFA WC Live Streaming}, year = 2020 }
• Estimating Quality of Experience of Enterprise Applications - A Crowdsourcing-based Approach. Technical Report (PhD dissertation), . Borchert, Kathrin. PhD dissertation. University of Würzburg, 2020, October.
  • [ BibTeX ]
  @phdthesis{info3-dissertation-2020-1, author = {Borchert, Kathrin}, keywords = {myown}, month = 10, school = {University of Würzburg}, title = {Estimating Quality of Experience of Enterprise Applications - A Crowdsourcing-based Approach}, year = 2020 }
• Personal Task Design Preferences of Crowdworkers. Hirth, Matthias; Borchert, Kathrin; de Moor, Katrien; Borst, Vanessa; Hoßfeld, Tobias. In 12th International Conference on Quality of Multimedia Experience (QoMEX). Athlone, Ireland, 2020.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2020-5, address = {Athlone, Ireland}, author = {Hirth, Matthias and Borchert, Kathrin and de Moor, Katrien and Borst, Vanessa and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {t_full}, month = {05}, title = {Personal Task Design Preferences of Crowdworkers}, year = 2020 }
• A Framework for Time Series Preprocessing and History-based Forecasting Method Recommendation. Z{ü}fle, Marwin; Kounev, Samuel. In Proceedings of the 15th Conference on Computer Science and Information Systems (FedCSIS): Data Mining Competition of the International Symposium on Advanced Artificial Intelligence in Applications. 2020.
  • [ BibTeX ]
  @inproceedings{ZuKo-AAIA2020-Framework, author = {Z{\"u}fle, Marwin and Kounev, Samuel}, booktitle = {Proceedings of the 15th Conference on Computer Science and Information Systems (FedCSIS): Data Mining Competition of the International Symposium on Advanced Artificial Intelligence in Applications}, keywords = {online_monitoring_and_forecasting}, month = {09}, title = {A Framework for Time Series Preprocessing and History-based Forecasting Method Recommendation}, year = 2020 }
• Personal Task Design Preferences of Crowdworkers. Hirth, Matthias; Borchert, Kathrin; de Moor, Katrien; Borst, Vanessa; Hoßfeld, Tobias. In 12th International Conference on Quality of Multimedia Experience (QoMEX). Athlone, Ireland, 2020.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2020-5, address = {Athlone, Ireland}, author = {Hirth, Matthias and Borchert, Kathrin and de Moor, Katrien and Borst, Vanessa and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {t_full}, month = {05}, title = {Personal Task Design Preferences of Crowdworkers}, year = 2020 }
• {A Concept for Crowd-sensed Prediction of Mobile Network Connectivity}. Herrnleben, Stefan; Zeidler, Bernd; Z{ü}fle, Marwin; Krupitzer, Christian; Kounev, Samuel. In GI/ITG Workshop on Machine Learning in the Context of Communication Networks 2020. 2020.
  • [ BibTeX ]
  @inproceedings{HeZeZuKrKo-FGMLN2020-Prediction-of-Mobile-Network-Connectivity, author = {Herrnleben, Stefan and Zeidler, Bernd and Z{\"u}fle, Marwin and Krupitzer, Christian and Kounev, Samuel}, booktitle = {GI/ITG Workshop on Machine Learning in the Context of Communication Networks 2020}, keywords = {t_workshop}, month = {02}, title = {{A Concept for Crowd-sensed Prediction of Mobile Network Connectivity}}, year = 2020 }
• Case-Based Generation of Regulatory Documents and their Semantic Relatedness. Korger, Andreas; Baumeister, Joachim. In Proceedings of the Future of Information and Communications Conference (FICC) 2020, of Advances in Intelligent Systems and Computing. Springer, San Francisco., 2020.
  • [ BibTeX ]
  @inproceedings{korger2020casebased, address = {San Francisco.}, author = {Korger, Andreas and Baumeister, Joachim}, booktitle = {Proceedings of the Future of Information and Communications Conference (FICC) 2020}, keywords = {myown}, month = {03}, publisher = {Springer}, series = {Advances in Intelligent Systems and Computing}, title = {Case-Based Generation of Regulatory Documents and their Semantic Relatedness}, year = 2020 }
• Think Twice: The Influence of Immersion on Decision Making during Gambling in Virtual Reality. Oberdörfer, Sebastian; Heidrich, David; Latoschik, Marc Erich. In Proceedings of the 27th IEEE Virtual Reality conference (VR ’20), pp. 483–492. IEEE, Atlanta, USA, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Immersive Virtual Reality (VR) is increasingly being explored as an alternative medium for gambling games to attract players. Typically, gambling games try to impair a player’s decision making, usually for the disadvantage of the players’ financial outcome. An impaired decision making results in the inability to differentiate between advantageous and disadvantageous options. We investigated if and how immersion impacts decision making using a VR-based realization of the Iowa Gambling Task (IGT) to pinpoint potential risks and effects of gambling in VR. During the IGT, subjects are challenged to draw cards from four different decks of which two are advantageous. The selections made serve as a measure of a participant’s decision making during the task. In a novel user study, we compared the effects of immersion on decision making between a low-immersive desktop-3D-based IGT realization and a high immersive VR version. Our results revealed significantly more disadvantageous decisions when playing the immersive VR version. This indicates an impair- ing effect of immersion on simulated real life decision making and provides empirical evidence for a high risk potential of gambling games targeting immersive VR.

  @inproceedings{oberdorfer2020think, abstract = {Immersive Virtual Reality (VR) is increasingly being explored as an alternative medium for gambling games to attract players. Typically, gambling games try to impair a player’s decision making, usually for the disadvantage of the players’ financial outcome. An impaired decision making results in the inability to differentiate between advantageous and disadvantageous options. We investigated if and how immersion impacts decision making using a VR-based realization of the Iowa Gambling Task (IGT) to pinpoint potential risks and effects of gambling in VR. During the IGT, subjects are challenged to draw cards from four different decks of which two are advantageous. The selections made serve as a measure of a participant’s decision making during the task. In a novel user study, we compared the effects of immersion on decision making between a low-immersive desktop-3D-based IGT realization and a high immersive VR version. Our results revealed significantly more disadvantageous decisions when playing the immersive VR version. This indicates an impair- ing effect of immersion on simulated real life decision making and provides empirical evidence for a high risk potential of gambling games targeting immersive VR.}, address = {Atlanta, USA}, author = {Oberdörfer, Sebastian and Heidrich, David and Latoschik, Marc Erich}, booktitle = {Proceedings of the 27th IEEE Virtual Reality conference (VR '20)}, keywords = {myown}, month = {03}, organization = {IEEE}, pages = {483-492}, title = {Think Twice: The Influence of Immersion on Decision Making during Gambling in Virtual Reality}, year = 2020 }
• {Model-based Performance Predictions for SDN-based Networks: A Case Study}. Herrnleben, Stefan; Rygielski, Piotr; Grohmann, Johannes; Eismann, Simon; Hossfeld, Tobias; Kounev, Samuel. In Proceedings of the 20th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems, of MMB 2020. Springer, Cham, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Emerging paradigms for network virtualization like Software-Defined Networking (SDN) and Network Functions Virtualization (NFV) form new challenges for accurate performance modeling and analysis tools. Therefore, performance modeling and prediction approaches that support SDN or NFV technologies help system operators to analyze the performance of a data center and its corresponding network. The Descartes Network Infrastructures (DNI) offers a high-level descriptive language to model SDN-based networks, which can be transformed into various predictive modeling formalisms. However, these modeling concepts have not yet been evaluated in a realistic scenario. In this paper, we present an extensive case study evaluating the DNI modeling capabilities, the transformations to predictive models, and the performance prediction using the OMNeT++ and SimQPN simulation frameworks. We present five realistic scenarios of a content distribution network (CDN), compare the performance predictions with real-world measurements, and discuss modeling gaps and calibration issues causing mispredictions in some scenarios.

  @inproceedings{HeRyGrEiHoKo-MMB2020-Model-based-SDN-Performance, abstract = {Emerging paradigms for network virtualization like Software-Defined Networking (SDN) and Network Functions Virtualization (NFV) form new challenges for accurate performance modeling and analysis tools. Therefore, performance modeling and prediction approaches that support SDN or NFV technologies help system operators to analyze the performance of a data center and its corresponding network. The Descartes Network Infrastructures (DNI) offers a high-level descriptive language to model SDN-based networks, which can be transformed into various predictive modeling formalisms. However, these modeling concepts have not yet been evaluated in a realistic scenario. In this paper, we present an extensive case study evaluating the DNI modeling capabilities, the transformations to predictive models, and the performance prediction using the OMNeT++ and SimQPN simulation frameworks. We present five realistic scenarios of a content distribution network (CDN), compare the performance predictions with real-world measurements, and discuss modeling gaps and calibration issues causing mispredictions in some scenarios.}, address = {Cham}, author = {Herrnleben, Stefan and Rygielski, Piotr and Grohmann, Johannes and Eismann, Simon and Hossfeld, Tobias and Kounev, Samuel}, booktitle = {Proceedings of the 20th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems}, keywords = {SDN}, month = {03}, publisher = {Springer}, series = {MMB 2020}, title = {{Model-based Performance Predictions for SDN-based Networks: A Case Study}}, year = 2020 }
• White Paper on Crowdsourced Network and QoE Measurements – Definitions, Use Cases and Challenges. Technical Report (10.25972/OPUS-20232), . Hoßfeld, Tobias; Wunderer, Stefan; Beyer, André; Hall, Andrew; Schwind, Anika; Gassner, Christian; Guillemin, Fabrice; Wamser, Florian; Wascinski, Krzysztof; Hirth, Matthias; Seufert, Michael; Casas, Pedro; Tran-Gia, Phuoc; Robitza, Werner; Wascinski, Wojciech; Ben Houidi, Zied. Würzburg, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  The goal of the white paper at hand is as follows. The definitions of the terms build a framework for discussions around the hype topic ‘crowdsourcing’. This serves as a basis for differentiation and a consistent view from different perspectives on crowdsourced network measurements, with the goal to provide a commonly accepted definition in the community. The focus is on the context of mobile and fixed network operators, but also on measurements of different layers (network, application, user layer). In addition, the white paper shows the value of crowdsourcing for selected use cases, e.g., to improve QoE or regulatory issues. Finally, the major challenges and issues for researchers and practitioners are highlighted. This white paper is the outcome of the Würzburg seminar on “Crowdsourced Network and QoE Measurements” which took place from 25-26 September 2019 in Würzburg, Germany. International experts were invited from industry and academia. They are well known in their communities, having different backgrounds in crowdsourcing, mobile networks, network measurements, network performance, Quality of Service (QoS), and Quality of Experience (QoE). The discussions in the seminar focused on how crowdsourcing will support vendors, operators, and regulators to determine the Quality of Experience in new 5G networks that enable various new applications and network architectures. As a result of the discussions, the need for a white paper manifested, with the goal of providing a scientific discussion of the terms “crowdsourced network measurements” and “crowdsourced QoE measurements”, describing relevant use cases for such crowdsourced data, and its underlying challenges. During the seminar, those main topics were identified, intensively discussed in break-out groups, and brought back into the plenum several times. The outcome of the seminar is this white paper at hand which is – to our knowledge – the first one covering the topic of crowdsourced network and QoE measurements.

  @techreport{info3-misc-2020-1, abstract = {The goal of the white paper at hand is as follows. The definitions of the terms build a framework for discussions around the hype topic ‘crowdsourcing’. This serves as a basis for differentiation and a consistent view from different perspectives on crowdsourced network measurements, with the goal to provide a commonly accepted definition in the community. The focus is on the context of mobile and fixed network operators, but also on measurements of different layers (network, application, user layer). In addition, the white paper shows the value of crowdsourcing for selected use cases, e.g., to improve QoE or regulatory issues. Finally, the major challenges and issues for researchers and practitioners are highlighted. This white paper is the outcome of the Würzburg seminar on “Crowdsourced Network and QoE Measurements” which took place from 25-26 September 2019 in Würzburg, Germany. International experts were invited from industry and academia. They are well known in their communities, having different backgrounds in crowdsourcing, mobile networks, network measurements, network performance, Quality of Service (QoS), and Quality of Experience (QoE). The discussions in the seminar focused on how crowdsourcing will support vendors, operators, and regulators to determine the Quality of Experience in new 5G networks that enable various new applications and network architectures. As a result of the discussions, the need for a white paper manifested, with the goal of providing a scientific discussion of the terms “crowdsourced network measurements” and “crowdsourced QoE measurements”, describing relevant use cases for such crowdsourced data, and its underlying challenges. During the seminar, those main topics were identified, intensively discussed in break-out groups, and brought back into the plenum several times. The outcome of the seminar is this white paper at hand which is – to our knowledge – the first one covering the topic of crowdsourced network and QoE measurements.}, author = {Hoßfeld, Tobias and Wunderer, Stefan and Beyer, André and Hall, Andrew and Schwind, Anika and Gassner, Christian and Guillemin, Fabrice and Wamser, Florian and Wascinski, Krzysztof and Hirth, Matthias and Seufert, Michael and Casas, Pedro and Tran-Gia, Phuoc and Robitza, Werner and Wascinski, Wojciech and Ben Houidi, Zied}, institution = {Würzburg}, keywords = {ua-net}, month = {03}, number = {10.25972/OPUS-20232}, title = {White Paper on Crowdsourced Network and QoE Measurements – Definitions, Use Cases and Challenges}, year = 2020 }
• {To Fail Or Not To Fail: Predicting Hard Disk Drive Failure Time Windows}. Z{ü}fle, Marwin; Krupitzer, Christian; Erhard, Florian; Grohmann, Johannes; Kounev, Samuel. In Proceedings of the 20th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems, of MMB 2020, pp. 19–36. Springer, Cham, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Due to the increasing size of today's data centers as well as the expectation of 24/7 availability, the complexity in the administration of hardware continuously icreases. Techniques as the Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) support the monitoring of the hardware. However, those techniques often lack algorithms for intelligent data analytics. Especially, the integration of machine learning to identify potential failures in advance seems to be promising to reduce administration overhead. In this work, we present three machine learning approaches to (i) identify imminent failures, (ii) predict time windows for failures, as well as (iii) predict the exact time-to-failure. In a case study with real data from 369 hard disks, we achieve an F1-score of up to 98.0% and 97.6% for predicting potential failures with two or multiple time windows, respectively, and a hit rate of 84.9% (with a mean absolute error of 4.5 hours) for predicting the time-to-failure.

  @inproceedings{ZuKrErGrKo-MMB2020-ToFailOrNotToFail, abstract = {Due to the increasing size of today's data centers as well as the expectation of 24/7 availability, the complexity in the administration of hardware continuously icreases. Techniques as the Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) support the monitoring of the hardware. However, those techniques often lack algorithms for intelligent data analytics. Especially, the integration of machine learning to identify potential failures in advance seems to be promising to reduce administration overhead. In this work, we present three machine learning approaches to (i) identify imminent failures, (ii) predict time windows for failures, as well as (iii) predict the exact time-to-failure. In a case study with real data from 369 hard disks, we achieve an F1-score of up to 98.0% and 97.6% for predicting potential failures with two or multiple time windows, respectively, and a hit rate of 84.9% (with a mean absolute error of 4.5 hours) for predicting the time-to-failure.}, address = {Cham}, author = {Z{\"u}fle, Marwin and Krupitzer, Christian and Erhard, Florian and Grohmann, Johannes and Kounev, Samuel}, booktitle = {Proceedings of the 20th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems}, keywords = {Reliability}, month = {03}, pages = {19–36}, publisher = {Springer}, series = {MMB 2020}, title = {{To Fail Or Not To Fail: Predicting Hard Disk Drive Failure Time Windows}}, year = 2020 }
• Machine Learning-based Real-time Estimation of Quality of Experience from Encrypted Video Streaming Traffic. Wehner, Nikolas. 1st KuVS Workshop on Machine Learning for Networking, Munich, Germany, 2020, February 21.
  • [ BibTeX ]
  @presentation{info3-presentation-2020-1, address = {1st KuVS Workshop on Machine Learning for Networking, Munich, Germany}, author = {Wehner, Nikolas}, keywords = {ucn}, month = {02}, title = {Machine Learning-based Real-time Estimation of Quality of Experience from Encrypted Video Streaming Traffic}, year = 2020 }
• {A Survey on Predictive Maintenance for Industry 4.0}. Krupitzer, Christian; Wagenhals, Tim; Z{ü}fle, Marwin; Lesch, Veronika; Sch{ä}fer, Dominik; Mozaffarin, Amin; Edinger, Janick; Becker, Christian; Kounev, Samuel. Universit{ä}t W{ü}rzburg and University of Mannheim and Syntax Systems GmbH and MOZYS Engineering GmbH, 2020.
  • [ BibTeX ]
  • [ URL ]
  @techreport{Krupitzer2020ASurveyPdM, author = {Krupitzer, Christian and Wagenhals, Tim and Z{\"u}fle, Marwin and Lesch, Veronika and Sch{\"a}fer, Dominik and Mozaffarin, Amin and Edinger, Janick and Becker, Christian and Kounev, Samuel}, institution = {Universit{\"a}t W{\"u}rzburg and University of Mannheim and Syntax Systems GmbH and MOZYS Engineering GmbH}, journal = {arXiv}, keywords = {Reliability}, month = {02}, title = {{A Survey on Predictive Maintenance for Industry 4.0}}, year = 2020 }
• {A Concept for Crowd-sensed Prediction of Mobile Network Connectivity}. Herrnleben, Stefan; Zeidler, Bernd; Z{ü}fle, Marwin; Krupitzer, Christian; Kounev, Samuel. In GI/ITG Workshop on Machine Learning in the Context of Communication Networks 2020. 2020.
  • [ BibTeX ]
  @inproceedings{HeZeZuKrKo-FGMLN2020-Prediction-of-Mobile-Network-Connectivity, author = {Herrnleben, Stefan and Zeidler, Bernd and Z{\"u}fle, Marwin and Krupitzer, Christian and Kounev, Samuel}, booktitle = {GI/ITG Workshop on Machine Learning in the Context of Communication Networks 2020}, keywords = {t_workshop}, month = {02}, title = {{A Concept for Crowd-sensed Prediction of Mobile Network Connectivity}}, year = 2020 }
• {Towards Self-Aware Multirotor Formations}. Kaiser, Dennis; Lesch, Veronika; Rothe, Julian; Strohmeier, Michael; Spiess, Florian; Krupitzer, Christian; Montenegro, Sergio; Kounev, Samuel. In Computers, 9(7). MDPI, 2020.
  • [ BibTeX ]
  @article{Kaiser2020Towards, author = {Kaiser, Dennis and Lesch, Veronika and Rothe, Julian and Strohmeier, Michael and Spiess, Florian and Krupitzer, Christian and Montenegro, Sergio and Kounev, Samuel}, journal = {Computers}, keywords = {Intelligent_Transportation_Systems}, month = {02}, note = {Special Issue on Self-Aware Computing}, number = 7, publisher = {MDPI}, title = {{Towards Self-Aware Multirotor Formations}}, volume = 9, year = 2020 }
• {Model-based Performance Predictions for SDN-based Networks: A Case Study}. Herrnleben, Stefan; Rygielski, Piotr; Grohmann, Johannes; Eismann, Simon; Hossfeld, Tobias; Kounev, Samuel. In Proceedings of the 20th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems, of MMB 2020. Springer, Cham, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Emerging paradigms for network virtualization like Software-Defined Networking (SDN) and Network Functions Virtualization (NFV) form new challenges for accurate performance modeling and analysis tools. Therefore, performance modeling and prediction approaches that support SDN or NFV technologies help system operators to analyze the performance of a data center and its corresponding network. The Descartes Network Infrastructures (DNI) offers a high-level descriptive language to model SDN-based networks, which can be transformed into various predictive modeling formalisms. However, these modeling concepts have not yet been evaluated in a realistic scenario. In this paper, we present an extensive case study evaluating the DNI modeling capabilities, the transformations to predictive models, and the performance prediction using the OMNeT++ and SimQPN simulation frameworks. We present five realistic scenarios of a content distribution network (CDN), compare the performance predictions with real-world measurements, and discuss modeling gaps and calibration issues causing mispredictions in some scenarios.

  @inproceedings{HeRyGrEiHoKo-MMB2020-Model-based-SDN-Performance, abstract = {Emerging paradigms for network virtualization like Software-Defined Networking (SDN) and Network Functions Virtualization (NFV) form new challenges for accurate performance modeling and analysis tools. Therefore, performance modeling and prediction approaches that support SDN or NFV technologies help system operators to analyze the performance of a data center and its corresponding network. The Descartes Network Infrastructures (DNI) offers a high-level descriptive language to model SDN-based networks, which can be transformed into various predictive modeling formalisms. However, these modeling concepts have not yet been evaluated in a realistic scenario. In this paper, we present an extensive case study evaluating the DNI modeling capabilities, the transformations to predictive models, and the performance prediction using the OMNeT++ and SimQPN simulation frameworks. We present five realistic scenarios of a content distribution network (CDN), compare the performance predictions with real-world measurements, and discuss modeling gaps and calibration issues causing mispredictions in some scenarios.}, address = {Cham}, author = {Herrnleben, Stefan and Rygielski, Piotr and Grohmann, Johannes and Eismann, Simon and Hossfeld, Tobias and Kounev, Samuel}, booktitle = {Proceedings of the 20th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems}, keywords = {SDN}, month = {03}, publisher = {Springer}, series = {MMB 2020}, title = {{Model-based Performance Predictions for SDN-based Networks: A Case Study}}, year = 2020 }
• {A Survey on Human Machine Interaction in Industry 4.0}. Krupitzer, Christian; M{ü}ller, Sebastian; Lesch, Veronika; Z{ü}fle, Marwin; Edinger, Janick; Lemken, Alexander; Sch{ä}fer, Dominik; Kounev, Samuel; Becker, Christian. Universit{ä}t W{ü}rzburg and University of Mannheim and ioxp GmbH and Syntax Systems GmbH, 2020.
  • [ BibTeX ]
  • [ URL ]
  @techreport{Krupitzer2020ASurvey, author = {Krupitzer, Christian and M{\"u}ller, Sebastian and Lesch, Veronika and Z{\"u}fle, Marwin and Edinger, Janick and Lemken, Alexander and Sch{\"a}fer, Dominik and Kounev, Samuel and Becker, Christian}, institution = {Universit{\"a}t W{\"u}rzburg and University of Mannheim and ioxp GmbH and Syntax Systems GmbH}, journal = {arXiv}, keywords = {t_interdisciplinary}, month = {02}, title = {{A Survey on Human Machine Interaction in Industry 4.0}}, year = 2020 }
• {Elasticity of Cloud Platforms}. Herbst, Nikolas; Bauer, Andr{é}; Kounev, Samuel. In {Systems Benchmarking: For Scientists and Engineers}, S. Kounev, K.-D. Lange, J. von Kistowski (eds.), pp. 319–340. Springer, 2020.
  • [ BibTeX ]
  @inproceedings{bauer2020bookelasticity, author = {Herbst, Nikolas and Bauer, Andr{\'e} and Kounev, Samuel}, booktitle = {{Systems Benchmarking: For Scientists and Engineers}}, editor = {Kounev, Samuel and Lange, Klaus-Dieter and von Kistowski, J{\'o}akim}, keywords = {t_bookchapter}, month = {01}, organization = {Springer}, pages = {319-340}, title = {{Elasticity of Cloud Platforms}}, year = 2020 }
• {Elasticity of Cloud Platforms}. Herbst, Nikolas; Bauer, Andr{é}; Kounev, Samuel. In {Systems Benchmarking: For Scientists and Engineers}, S. Kounev, K.-D. Lange, J. von Kistowski (eds.), pp. 319–340. Springer, 2020.
  • [ BibTeX ]
  @inproceedings{bauer2020bookelasticity, author = {Herbst, Nikolas and Bauer, Andr{\'e} and Kounev, Samuel}, booktitle = {{Systems Benchmarking: For Scientists and Engineers}}, editor = {Kounev, Samuel and Lange, Klaus-Dieter and von Kistowski, J{\'o}akim}, keywords = {t_bookchapter}, month = {01}, organization = {Springer}, pages = {319-340}, title = {{Elasticity of Cloud Platforms}}, year = 2020 }
• PTAS for Steiner Tree on Map Graphs. Byrka, Jaroslaw; Lewandowski, Mateusz; Meesum, Syed Mohammad; Spoerhase, Joachim; Uniyal, Sumedha. In Proc. 14th Latin American Theoretical Informatics Symposium (LATIN’20). 2020.
  • [ BibTeX ]
  @inproceedings{byrka2020steiner, author = {Byrka, Jaroslaw and Lewandowski, Mateusz and Meesum, Syed Mohammad and Spoerhase, Joachim and Uniyal, Sumedha}, booktitle = {Proc. 14th Latin American Theoretical Informatics Symposium (LATIN'20)}, keywords = {algorithm}, title = {PTAS for Steiner Tree on Map Graphs}, year = 2020 }
• The Stub Resolution of 1-Planar Graphs. Kaufmann, Michael; Kratochvil, Jan; Lipp, Fabian; Montecchiani, Fabrizio; Raftopoulou, Chrysanthi; Valtr, Pavel. In WALCOM: Algorithms and Computation, Vol. 12049 of Lecture Notes in Computer Science, M. S. Rahman, K. Sadakane, W.-K. Sung (eds.), pp. 170–182. Springer, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  The resolution of a drawing plays a crucial role when defining criteria for its quality. In the past, grid resolution, edge-length resolution, angular resolution and crossing resolution have been investigated. In this paper, we investigate the stub resolution, a recently introduced criterion for nonplanar drawings. A crossed edge is divided into parts, called stubs, which should not be too short for the sake of readability. Thus, the stub resolution of a drawing is defined as the minimum ratio between the length of a stub and the length of the entire edge, over all the edges of the drawing. We consider 1-planar graphs and we explore scenarios in which near optimal stub resolution, i.e. arbitrarily close to {\$}{\$}{\backslash}frac{\{}1{\}}{\{}2{\}}{\$}{\$}, can be obtained in drawings with zero, one, or two bends per edge, as well as further resolution criteria, such as angular and crossing resolution. In particular, our main contributions are as follows: (i) Every 1-planar graph with independent crossing edges has a straight-line drawing with near optimal stub resolution; (ii) Every 1-planar graph has a 1-bend drawing with near optimal stub resolution.

  @inproceedings{10.1007/978-3-030-39881-1_15, abstract = {The resolution of a drawing plays a crucial role when defining criteria for its quality. In the past, grid resolution, edge-length resolution, angular resolution and crossing resolution have been investigated. In this paper, we investigate the stub resolution, a recently introduced criterion for nonplanar drawings. A crossed edge is divided into parts, called stubs, which should not be too short for the sake of readability. Thus, the stub resolution of a drawing is defined as the minimum ratio between the length of a stub and the length of the entire edge, over all the edges of the drawing. We consider 1-planar graphs and we explore scenarios in which near optimal stub resolution, i.e. arbitrarily close to {\$}{\$}{\backslash}frac{\{}1{\}}{\{}2{\}}{\$}{\$}, can be obtained in drawings with zero, one, or two bends per edge, as well as further resolution criteria, such as angular and crossing resolution. In particular, our main contributions are as follows: (i) Every 1-planar graph with independent crossing edges has a straight-line drawing with near optimal stub resolution; (ii) Every 1-planar graph has a 1-bend drawing with near optimal stub resolution.}, author = {Kaufmann, Michael and Kratochvil, Jan and Lipp, Fabian and Montecchiani, Fabrizio and Raftopoulou, Chrysanthi and Valtr, Pavel}, booktitle = {WALCOM: Algorithms and Computation}, editor = {Rahman, M. Sohel and Sadakane, Kunihiko and Sung, Wing-Kin}, keywords = {stub}, pages = {170–182}, publisher = {Springer}, series = {Lecture Notes in Computer Science}, title = {The Stub Resolution of 1-Planar Graphs}, volume = 12049, year = 2020 }
• A Taxonomy of Techniques for SLO Failure Prediction in Software Systems. Grohmann, Johannes; Herbst, Nikolas; Chalbani, Avi; Arian, Yair; Peretz, Noam; Kounev, Samuel. In Computers, 9(1), p. 10. Multidisciplinary Digital Publishing Institute (MDPI), 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Failure prediction is an important aspect of self-aware computing systems. Therefore, a multitude of different approaches has been proposed in the literature over the past few years. In this work, we propose a taxonomy for organizing works focusing on the prediction of Service Level Objective (SLO) failures. Our taxonomy classifies related work along the dimensions of the prediction target (e.g., anomaly detection, performance prediction, or failure prediction), the time horizon (e.g., detection or prediction, online or offline application), and the applied modeling type (e.g., time series forecasting, machine learning, or queueing theory). The classification is derived based on a systematic mapping of relevant papers in the area. Additionally, we give an overview of different techniques in each sub-group and address remaining challenges in order to guide future research.

  @article{grohmann2020-MDPI-taxonomy, abstract = {Failure prediction is an important aspect of self-aware computing systems. Therefore, a multitude of different approaches has been proposed in the literature over the past few years. In this work, we propose a taxonomy for organizing works focusing on the prediction of Service Level Objective (SLO) failures. Our taxonomy classifies related work along the dimensions of the prediction target (e.g., anomaly detection, performance prediction, or failure prediction), the time horizon (e.g., detection or prediction, online or offline application), and the applied modeling type (e.g., time series forecasting, machine learning, or queueing theory). The classification is derived based on a systematic mapping of relevant papers in the area. Additionally, we give an overview of different techniques in each sub-group and address remaining challenges in order to guide future research.}, author = {Grohmann, Johannes and Herbst, Nikolas and Chalbani, Avi and Arian, Yair and Peretz, Noam and Kounev, Samuel}, journal = {Computers}, keywords = {automated_model_learning}, number = 1, pages = 10, publisher = {Multidisciplinary Digital Publishing Institute (MDPI)}, title = {A Taxonomy of Techniques for SLO Failure Prediction in Software Systems}, volume = 9, year = 2020 }
• Simulative Evaluation of KPIs in SDN for Topology Classification and Performance Prediction Models. Gray, Nicholas; Dietz, Katharina; Hoßfeld, Tobias. In 2020 16th International Conference on Network and Service Management (CNSM). 2020.
  • [ Abstract ]
  • [ BibTeX ]
  In recent years Software-defined Networking (SDN) has gained increased popularity by reducing the complexity of management operations and increasing the performance of networks. As a result, the number of purchasable SDN devices and their deployment in real world network constantly rises, making a thorough understanding of their behaviors and interactions even more important. In this work we analyze distributed controller architectures via simulation, identify Key Performance Indicators (KPIs), classify various network topologies with respect to their impact on SDN, as well as create a prediction model to estimate the overall performance of the overall SDN ecosystem, which can be used for network planning.

  @inproceedings{info3-inproceedings-2020-15, abstract = {In recent years Software-defined Networking (SDN) has gained increased popularity by reducing the complexity of management operations and increasing the performance of networks. As a result, the number of purchasable SDN devices and their deployment in real world network constantly rises, making a thorough understanding of their behaviors and interactions even more important. In this work we analyze distributed controller architectures via simulation, identify Key Performance Indicators (KPIs), classify various network topologies with respect to their impact on SDN, as well as create a prediction model to estimate the overall performance of the overall SDN ecosystem, which can be used for network planning.}, author = {Gray, Nicholas and Dietz, Katharina and Hoßfeld, Tobias}, booktitle = {2020 16th International Conference on Network and Service Management (CNSM)}, keywords = {myown}, title = {Simulative Evaluation of KPIs in SDN for Topology Classification and Performance Prediction Models}, year = 2020 }
• Studying the Impact of the Content Selection Method on the Video QoE on Mobile Devices. Wehner, Nikolas; Mertinat, Nils; Seufert, Michael; Hoßfeld, Tobias. Athlone, Ireland, 2020, May.
  • [ Abstract ]
  • [ BibTeX ]
  When conducting video QoE studies, participants are usually asked to rate the QoE of prepared test videos. However, participants are given no choice to select content, which they like or in which they are interested. This may cause annoyance or frustration when conducting the QoE study, which eventually might affect the QoE results of the study. The consequent question is whether the content liking has a direct impact on the submitted ratings by the participants and whether the freedom of choosing the video content in QoE studies results in better ratings. To investigate this research question, MCA, an existing framework for crowdsourced video testing, is extended and used in a pilot field study. MCA runs on mobile devices and allows users to watch the tested conditions of a QoE study within video content of their interest. The results of a QoE study with individual and dynamic content selection are compared to a QoE study with pre-selected contents. Moreover, this work includes a comparison to a previous QoE study for validation. As the previous study was conducted on desktop PCs, the MCA study further allows to identify differences in the stalling perception between studies on desktop PCs and mobile devices.

  @misc{info3-poster-2020-2, abstract = {When conducting video QoE studies, participants are usually asked to rate the QoE of prepared test videos. However, participants are given no choice to select content, which they like or in which they are interested. This may cause annoyance or frustration when conducting the QoE study, which eventually might affect the QoE results of the study. The consequent question is whether the content liking has a direct impact on the submitted ratings by the participants and whether the freedom of choosing the video content in QoE studies results in better ratings. To investigate this research question, MCA, an existing framework for crowdsourced video testing, is extended and used in a pilot field study. MCA runs on mobile devices and allows users to watch the tested conditions of a QoE study within video content of their interest. The results of a QoE study with individual and dynamic content selection are compared to a QoE study with pre-selected contents. Moreover, this work includes a comparison to a previous QoE study for validation. As the previous study was conducted on desktop PCs, the MCA study further allows to identify differences in the stalling perception between studies on desktop PCs and mobile devices.}, address = {Athlone, Ireland}, author = {Wehner, Nikolas and Mertinat, Nils and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ucn}, month = {05}, title = {Studying the Impact of the Content Selection Method on the Video QoE on Mobile Devices}, year = 2020 }
• Construction of a Corpus for the Evaluation of Textual Case-based Reasoning Architectures. Korger, Andreas; Baumeister, Joachim. In LWDA 2020 -- Lernen, Wissen, Daten, Analysen. 2020.
  • [ BibTeX ]
  @inproceedings{KB:20, author = {Korger, Andreas and Baumeister, Joachim}, booktitle = {LWDA 2020 – Lernen, Wissen, Daten, Analysen}, keywords = {myown}, title = {Construction of a Corpus for the Evaluation of Textual Case-based Reasoning Architectures}, year = 2020 }
• IJNM Special Issue - Editorial - QoE-centric Analysis and Management of Communication Networks. Wamser, Florian; Alay, Özgü; Metzger, Florian; Valentin, Stefan. In International Journal of Network Management, Special Issue: QoE-centric Analysis and Management of Communication Networks. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  The heterogeneity and variability of Internet applications has increased considerably in recent years. Applications such as video streaming are responsible for a large part of data traffic on the Internet. Internet telephony and video conferencing systems have become part of our daily lives. At the same time, the Internet of Things is striving to exceed previous expectations regarding the number of devices. Furthermore, the proliferation of video games, virtual reality applications, and 360° video applications is increasing. All this leads to specific but different requirements from applications to frameworks, service platforms, and networks. For each service, users desire special service criteria, such as smooth interactivity, fast downloads, high availability, or extensive content. Such requirements can usually be summarized under the term Quality of Experience, i.e., the overall satisfaction of a user with the system cur- rently in use. In the age of big data and dynamic networks, Quality of Experience is still looking for its place, and good solutions are in high demand. This Special Issue addresses the latest advances and challenges in analysis, design, modeling, measurement, and performance evaluation of Quality of Experience and Quality of Experience-oriented metrics and management.

  @article{info3-article-2020-1, abstract = {The heterogeneity and variability of Internet applications has increased considerably in recent years. Applications such as video streaming are responsible for a large part of data traffic on the Internet. Internet telephony and video conferencing systems have become part of our daily lives. At the same time, the Internet of Things is striving to exceed previous expectations regarding the number of devices. Furthermore, the proliferation of video games, virtual reality applications, and 360° video applications is increasing. All this leads to specific but different requirements from applications to frameworks, service platforms, and networks. For each service, users desire special service criteria, such as smooth interactivity, fast downloads, high availability, or extensive content. Such requirements can usually be summarized under the term Quality of Experience, i.e., the overall satisfaction of a user with the system cur- rently in use. In the age of big data and dynamic networks, Quality of Experience is still looking for its place, and good solutions are in high demand. This Special Issue addresses the latest advances and challenges in analysis, design, modeling, measurement, and performance evaluation of Quality of Experience and Quality of Experience-oriented metrics and management.}, author = {Wamser, Florian and Alay, Özgü and Metzger, Florian and Valentin, Stefan}, journal = {International Journal of Network Management}, keywords = {can}, month = {03}, title = {IJNM Special Issue - Editorial - QoE-centric Analysis and Management of Communication Networks}, volume = {Special Issue: QoE-centric Analysis and Management of Communication Networks}, year = 2020 }
• {Towards Self-Aware Multirotor Formations}. Kaiser, Dennis; Lesch, Veronika; Rothe, Julian; Strohmeier, Michael; Spiess, Florian; Krupitzer, Christian; Montenegro, Sergio; Kounev, Samuel. In Computers, 9(7). MDPI, 2020.
  • [ BibTeX ]
  @article{Kaiser2020Towards, author = {Kaiser, Dennis and Lesch, Veronika and Rothe, Julian and Strohmeier, Michael and Spiess, Florian and Krupitzer, Christian and Montenegro, Sergio and Kounev, Samuel}, journal = {Computers}, keywords = {Intelligent_Transportation_Systems}, month = {02}, note = {Special Issue on Self-Aware Computing}, number = 7, publisher = {MDPI}, title = {{Towards Self-Aware Multirotor Formations}}, volume = 9, year = 2020 }
• Is the Uplink Enough? Estimating Video Stalls from Encrypted Network Traffic. Loh, Frank; Wamser, Florian; Moldovan, Christian; Zeidler, Bernd; Tsilimantos, Dimitrios; Valentin, Stefan; Hoßfeld, Tobias. In 32th IEEE/IFIP Network Operations and Management Symposium. Budapest, Hungary, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Today’s traffic projections speak of almost 58 % video traffic across the Internet. Nearly all video traffic is encrypted, accounting for more than 50 % encrypted traffic worldwide. To analyze video traffic today, or even estimate its quality in the network, a deep look into the traffic characteristics has to be done. But then, important quality metrics from the traffic behavior can be derived. Based on extensive measurements we show in this work how to measure and estimate video stalls for mobile adaptive streaming. The underlying dataset includes more than 900 hours of video footage from the native YouTube app, measured over 18 different videos in 56 network scenarios in two cities in Europe. We outline a possible approach to estimate the video playback buffer size based on uplink video chunk requests in real-time to break down the video stalls. This work is intended as a tool for network operators to receive further knowledge of the characteristics of video streaming traffic to quantify the most important QoE degradation factors of one of the most important applications today.

  @inproceedings{info3-inproceedings-2020-2, abstract = {Today’s traffic projections speak of almost 58 % video traffic across the Internet. Nearly all video traffic is encrypted, accounting for more than 50 % encrypted traffic worldwide. To analyze video traffic today, or even estimate its quality in the network, a deep look into the traffic characteristics has to be done. But then, important quality metrics from the traffic behavior can be derived. Based on extensive measurements we show in this work how to measure and estimate video stalls for mobile adaptive streaming. The underlying dataset includes more than 900 hours of video footage from the native YouTube app, measured over 18 different videos in 56 network scenarios in two cities in Europe. We outline a possible approach to estimate the video playback buffer size based on uplink video chunk requests in real-time to break down the video stalls. This work is intended as a tool for network operators to receive further knowledge of the characteristics of video streaming traffic to quantify the most important QoE degradation factors of one of the most important applications today.}, address = {Budapest, Hungary}, author = {Loh, Frank and Wamser, Florian and Moldovan, Christian and Zeidler, Bernd and Tsilimantos, Dimitrios and Valentin, Stefan and Hoßfeld, Tobias}, booktitle = {32th IEEE/IFIP Network Operations and Management Symposium}, keywords = {can}, month = {04}, title = {Is the Uplink Enough? Estimating Video Stalls from Encrypted Network Traffic}, year = 2020 }
• Predicting the Costs of Serverless Workflows. Eismann, Simon; Grohmann, Johannes; van Eyk, Erwin; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 2020 ACM/SPEC International Conference on Performance Engineering (ICPE), of ICPE ’20, pp. 265–276. Association for Computing Machinery (ACM), New York, NY, USA, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Function-as-a-Service (FaaS) platforms enable users to run arbitrary functions without being concerned about operational issues, while only paying for the consumed resources. Individual functions are often composed into workflows for complex tasks. However, the pay-per-use model and nontransparent reporting by cloud providers make it challenging to estimate the expected cost of a workflow, which prevents informed business decisions. Existing cost-estimation approaches assume a static response time for the serverless functions, without taking input parameters into account. In this paper, we propose a methodology for the cost prediction of serverless workflows consisting of input-parameter sensitive function models and a monte-carlo simulation of an abstract workflow model. Our approach enables workflow designers to predict, compare, and optimize the expected costs and performance of a planned workflow, which currently requires time-intensive experimentation. In our evaluation, we show that our approach can predict the response time and output parameters of a function based on its input parameters with an accuracy of 96.1%. In a case study with two audio-processing workflows, our approach predicts the costs of the two workflows with an accuracy of 96.2%.

  @inproceedings{EiGrEyHeKo2020-ICPE-ServerlessWorkflows, abstract = {Function-as-a-Service (FaaS) platforms enable users to run arbitrary functions without being concerned about operational issues, while only paying for the consumed resources. Individual functions are often composed into workflows for complex tasks. However, the pay-per-use model and nontransparent reporting by cloud providers make it challenging to estimate the expected cost of a workflow, which prevents informed business decisions. Existing cost-estimation approaches assume a static response time for the serverless functions, without taking input parameters into account. In this paper, we propose a methodology for the cost prediction of serverless workflows consisting of input-parameter sensitive function models and a monte-carlo simulation of an abstract workflow model. Our approach enables workflow designers to predict, compare, and optimize the expected costs and performance of a planned workflow, which currently requires time-intensive experimentation. In our evaluation, we show that our approach can predict the response time and output parameters of a function based on its input parameters with an accuracy of 96.1%. In a case study with two audio-processing workflows, our approach predicts the costs of the two workflows with an accuracy of 96.2%.}, address = {New York, NY, USA}, author = {Eismann, Simon and Grohmann, Johannes and van Eyk, Erwin and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 2020 ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {se2}, month = {04}, note = {{Acceptance Rate: 23.4% (15/64)}}, pages = {265–276}, publisher = {Association for Computing Machinery (ACM)}, series = {ICPE '20}, title = {Predicting the Costs of Serverless Workflows}, year = 2020 }
• Studying the Impact of the Content Selection Method on the Video QoE on Mobile Devices. Wehner, Nikolas; Mertinat, Nils; Seufert, Michael; Hoßfeld, Tobias. In 12th International Conference on Quality of Multimedia Experience (QoMEX). Athlone, Ireland, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  When conducting video QoE studies, participants are usually asked to rate the QoE of prepared test videos. However, participants are given no choice to select content, which they like or in which they are interested. This may cause annoyance or frustration when conducting the QoE study, which eventually might affect the QoE results of the study. The consequent question is whether the content liking has a direct impact on the submitted ratings by the participants and whether the freedom of choosing the video content in QoE studies results in better ratings. To investigate this research question, MCA, an existing framework for crowdsourced video testing, is extended and used in a pilot field study. MCA runs on mobile devices and allows users to watch the tested conditions of a QoE study within video content of their interest. The results of a QoE study with individual and dynamic content selection are compared to a QoE study with pre-selected contents. Moreover, this work includes a comparison to a previous QoE study for validation. As the previous study was conducted on desktop PCs, the MCA study further allows to identify differences in the stalling perception between studies on desktop PCs and mobile devices.

  @inproceedings{info3-inproceedings-2020-8, abstract = {When conducting video QoE studies, participants are usually asked to rate the QoE of prepared test videos. However, participants are given no choice to select content, which they like or in which they are interested. This may cause annoyance or frustration when conducting the QoE study, which eventually might affect the QoE results of the study. The consequent question is whether the content liking has a direct impact on the submitted ratings by the participants and whether the freedom of choosing the video content in QoE studies results in better ratings. To investigate this research question, MCA, an existing framework for crowdsourced video testing, is extended and used in a pilot field study. MCA runs on mobile devices and allows users to watch the tested conditions of a QoE study within video content of their interest. The results of a QoE study with individual and dynamic content selection are compared to a QoE study with pre-selected contents. Moreover, this work includes a comparison to a previous QoE study for validation. As the previous study was conducted on desktop PCs, the MCA study further allows to identify differences in the stalling perception between studies on desktop PCs and mobile devices.}, address = {Athlone, Ireland}, author = {Wehner, Nikolas and Mertinat, Nils and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ucn}, month = {05}, title = {Studying the Impact of the Content Selection Method on the Video QoE on Mobile Devices}, year = 2020 }
• {Model-based Performance Predictions for SDN-based Networks: A Case Study}. Herrnleben, Stefan; Rygielski, Piotr; Grohmann, Johannes; Eismann, Simon; Hossfeld, Tobias; Kounev, Samuel. In Proceedings of the 20th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems, of MMB 2020. Springer, Cham, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Emerging paradigms for network virtualization like Software-Defined Networking (SDN) and Network Functions Virtualization (NFV) form new challenges for accurate performance modeling and analysis tools. Therefore, performance modeling and prediction approaches that support SDN or NFV technologies help system operators to analyze the performance of a data center and its corresponding network. The Descartes Network Infrastructures (DNI) offers a high-level descriptive language to model SDN-based networks, which can be transformed into various predictive modeling formalisms. However, these modeling concepts have not yet been evaluated in a realistic scenario. In this paper, we present an extensive case study evaluating the DNI modeling capabilities, the transformations to predictive models, and the performance prediction using the OMNeT++ and SimQPN simulation frameworks. We present five realistic scenarios of a content distribution network (CDN), compare the performance predictions with real-world measurements, and discuss modeling gaps and calibration issues causing mispredictions in some scenarios.

  @inproceedings{HeRyGrEiHoKo-MMB2020-Model-based-SDN-Performance, abstract = {Emerging paradigms for network virtualization like Software-Defined Networking (SDN) and Network Functions Virtualization (NFV) form new challenges for accurate performance modeling and analysis tools. Therefore, performance modeling and prediction approaches that support SDN or NFV technologies help system operators to analyze the performance of a data center and its corresponding network. The Descartes Network Infrastructures (DNI) offers a high-level descriptive language to model SDN-based networks, which can be transformed into various predictive modeling formalisms. However, these modeling concepts have not yet been evaluated in a realistic scenario. In this paper, we present an extensive case study evaluating the DNI modeling capabilities, the transformations to predictive models, and the performance prediction using the OMNeT++ and SimQPN simulation frameworks. We present five realistic scenarios of a content distribution network (CDN), compare the performance predictions with real-world measurements, and discuss modeling gaps and calibration issues causing mispredictions in some scenarios.}, address = {Cham}, author = {Herrnleben, Stefan and Rygielski, Piotr and Grohmann, Johannes and Eismann, Simon and Hossfeld, Tobias and Kounev, Samuel}, booktitle = {Proceedings of the 20th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems}, keywords = {SDN}, month = {03}, publisher = {Springer}, series = {MMB 2020}, title = {{Model-based Performance Predictions for SDN-based Networks: A Case Study}}, year = 2020 }
• QoE Assessment of Enterprise Applications based on Self-motivated Ratings. Borchert, Kathrin; Seufert, Michael; Hildebrand, Kathrin; Hoßfeld, Tobias. In 12th International Conference on Quality of Multimedia Experience (QoMEX). Athlone, Ireland, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  In most companies, enterprise applications, such as office products or databases, are heavily used by employees during work hours. Impairments and performance issues not only slow down business processes, but might also increase the frustration of the workforce. While Quality of Experience (QoE) has been widely studied for personal multimedia applications, such as video streaming, its application to the business usage domain is still in its infancy. Due to several reasons, e.g., the high complexity of IT infrastructure, classical QoE studies can hardly be transferred to business applications. These studies are often independent from the context of usage and actively poll ratings from their participants. This work contrasts the commonly used "pull" method for collecting user ratings with a self-motivated "push" approach. This approach is inspired by complaint systems, in which users can directly report problems with a technical system as soon as they notice them. Therefore, performance assessments of a business application from employees of a cooperating company are collected with both rating systems during a time span of 1.5 years. Besides the analysis of the interaction of users with the "push" system, differences between the two methods are discussed. Further, QoE models for the monitored business application are derived based on the self-motivated "push" ratings.

  @inproceedings{info3-inproceedings-2020-3, abstract = {In most companies, enterprise applications, such as office products or databases, are heavily used by employees during work hours. Impairments and performance issues not only slow down business processes, but might also increase the frustration of the workforce. While Quality of Experience (QoE) has been widely studied for personal multimedia applications, such as video streaming, its application to the business usage domain is still in its infancy. Due to several reasons, e.g., the high complexity of IT infrastructure, classical QoE studies can hardly be transferred to business applications. These studies are often independent from the context of usage and actively poll ratings from their participants. This work contrasts the commonly used "pull" method for collecting user ratings with a self-motivated "push" approach. This approach is inspired by complaint systems, in which users can directly report problems with a technical system as soon as they notice them. Therefore, performance assessments of a business application from employees of a cooperating company are collected with both rating systems during a time span of 1.5 years. Besides the analysis of the interaction of users with the "push" system, differences between the two methods are discussed. Further, QoE models for the monitored business application are derived based on the self-motivated "push" ratings.}, address = {Athlone, Ireland}, author = {Borchert, Kathrin and Seufert, Michael and Hildebrand, Kathrin and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {kubus}, month = {05}, title = {QoE Assessment of Enterprise Applications based on Self-motivated Ratings}, year = 2020 }
• Smartwatch-Derived Data and Machine Learning Algorithms Estimate Classes of Ratings of Perceived Exertion in Runners: A Pilot Study. Davidson, Padraig; Düking, Peter; Zinner, Christoph; Sperlich, Billy; Hotho, Andreas. In Sensors. 2020.
  • [ BibTeX ]
  • [ URL ]
  @article{davidson2020smartwatchderived, author = {Davidson, Padraig and Düking, Peter and Zinner, Christoph and Sperlich, Billy and Hotho, Andreas}, journal = {Sensors}, keywords = 2020, month = {05}, title = {Smartwatch-Derived Data and Machine Learning Algorithms Estimate Classes of Ratings of Perceived Exertion in Runners: A Pilot Study}, year = 2020 }
• Predicting Performance Degradations of Microservice Applications. Technical Report (Master thesis), . Straesser, Martin. Master thesis. University of Wuerzburg, 2020, May.
  • [ BibTeX ]
  @mastersthesis{straesser2020predicting, author = {Straesser, Martin}, keywords = {performance_prediction}, month = {05}, note = {Wuerzburg Software Engineering Award 2020: Best Master Thesis}, school = {University of Wuerzburg}, title = {Predicting Performance Degradations of Microservice Applications}, year = 2020 }
• {An Automated Forecasting Framework based on Method Recommendation for Seasonal Time Series}. Bauer, Andr{é}; Z{ü}fle, Marwin; Grohmann, Johannes; Schmitt, Norbert; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the ACM/SPEC International Conference on Performance Engineering, of ICPE ’20, pp. 48–55. Association for Computing Machinery (ACM), New York, NY, USA, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Due to the fast-paced and changing demands of their users, computing systems require autonomic resource management. To enable proactive and accurate decision-making for changes causing a particular overhead, reliable forecasts are needed. In fact, choosing the best performing forecasting method for a given time series scenario is a crucial task. Taking the "No-Free-Lunch Theorem" into account, there exists no forecasting method that performs best on all types of time series. To this end, we propose an automated approach that (i) extracts characteristics from a given time series, (ii) selects the best-suited machine learning method based on recommendation, and finally, (iii) performs the forecast. Our approach offers the benefit of not relying on a single method with its possibly inaccurate forecasts. In an extensive evaluation, our approach achieves the best forecasting accuracy.

  @inproceedings{BaZuGrScHeKo-ICPE20-Seasonal-Forecast, abstract = {Due to the fast-paced and changing demands of their users, computing systems require autonomic resource management. To enable proactive and accurate decision-making for changes causing a particular overhead, reliable forecasts are needed. In fact, choosing the best performing forecasting method for a given time series scenario is a crucial task. Taking the "No-Free-Lunch Theorem" into account, there exists no forecasting method that performs best on all types of time series. To this end, we propose an automated approach that (i) extracts characteristics from a given time series, (ii) selects the best-suited machine learning method based on recommendation, and finally, (iii) performs the forecast. Our approach offers the benefit of not relying on a single method with its possibly inaccurate forecasts. In an extensive evaluation, our approach achieves the best forecasting accuracy.}, address = {New York, NY, USA}, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Grohmann, Johannes and Schmitt, Norbert and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the ACM/SPEC International Conference on Performance Engineering}, keywords = {PRISMA}, month = {04}, pages = {48–55}, publisher = {Association for Computing Machinery (ACM)}, series = {ICPE '20}, title = {{An Automated Forecasting Framework based on Method Recommendation for Seasonal Time Series}}, year = 2020 }
• {SPEC Research Group Newsletter, vol. 3 no. 1}. Kounev, Samuel; van Hoorn, Andre; Bauer, Andr{é}; Herbst, Nikolas. 2020, April.
  • [ BibTeX ]
  • [ URL ]
  @misc{kounev2020research, author = {Kounev, Samuel and van Hoorn, Andre and Bauer, Andr{\'e} and Herbst, Nikolas}, keywords = {se2}, month = {04}, note = {Published by Standard Performance Evaluation Corporation (SPEC)}, title = {{SPEC Research Group Newsletter, vol. 3 no. 1}}, year = 2020 }
• {Energy Efficiency Analysis of Compiler Optimizations on the SPEC CPU 2017 Benchmark Suite}. Schmitt, Norbert; Bucek, James; Lange, Klaus-Dieter; Kounev, Samuel. In Proceedings of the 11th ACM/SPEC International Conference on Performance Engineering (ICPE 2020). ACM, New York, NY, USA, 2020.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{ScLaBuKo-ICPE20-SPEC-CPU2017, address = {New York, NY, USA}, author = {Schmitt, Norbert and Bucek, James and Lange, Klaus-Dieter and Kounev, Samuel}, booktitle = {Proceedings of the 11th ACM/SPEC International Conference on Performance Engineering (ICPE 2020)}, keywords = {Power}, month = {04}, publisher = {ACM}, title = {{Energy Efficiency Analysis of Compiler Optimizations on the SPEC CPU 2017 Benchmark Suite}}, year = 2020 }
• Predicting the Costs of Serverless Workflows. Eismann, Simon; Grohmann, Johannes; van Eyk, Erwin; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 2020 ACM/SPEC International Conference on Performance Engineering (ICPE), of ICPE ’20, pp. 265–276. Association for Computing Machinery (ACM), New York, NY, USA, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Function-as-a-Service (FaaS) platforms enable users to run arbitrary functions without being concerned about operational issues, while only paying for the consumed resources. Individual functions are often composed into workflows for complex tasks. However, the pay-per-use model and nontransparent reporting by cloud providers make it challenging to estimate the expected cost of a workflow, which prevents informed business decisions. Existing cost-estimation approaches assume a static response time for the serverless functions, without taking input parameters into account. In this paper, we propose a methodology for the cost prediction of serverless workflows consisting of input-parameter sensitive function models and a monte-carlo simulation of an abstract workflow model. Our approach enables workflow designers to predict, compare, and optimize the expected costs and performance of a planned workflow, which currently requires time-intensive experimentation. In our evaluation, we show that our approach can predict the response time and output parameters of a function based on its input parameters with an accuracy of 96.1%. In a case study with two audio-processing workflows, our approach predicts the costs of the two workflows with an accuracy of 96.2%.

  @inproceedings{EiGrEyHeKo2020-ICPE-ServerlessWorkflows, abstract = {Function-as-a-Service (FaaS) platforms enable users to run arbitrary functions without being concerned about operational issues, while only paying for the consumed resources. Individual functions are often composed into workflows for complex tasks. However, the pay-per-use model and nontransparent reporting by cloud providers make it challenging to estimate the expected cost of a workflow, which prevents informed business decisions. Existing cost-estimation approaches assume a static response time for the serverless functions, without taking input parameters into account. In this paper, we propose a methodology for the cost prediction of serverless workflows consisting of input-parameter sensitive function models and a monte-carlo simulation of an abstract workflow model. Our approach enables workflow designers to predict, compare, and optimize the expected costs and performance of a planned workflow, which currently requires time-intensive experimentation. In our evaluation, we show that our approach can predict the response time and output parameters of a function based on its input parameters with an accuracy of 96.1%. In a case study with two audio-processing workflows, our approach predicts the costs of the two workflows with an accuracy of 96.2%.}, address = {New York, NY, USA}, author = {Eismann, Simon and Grohmann, Johannes and van Eyk, Erwin and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 2020 ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {se2}, month = {04}, note = {{Acceptance Rate: 23.4% (15/64)}}, pages = {265–276}, publisher = {Association for Computing Machinery (ACM)}, series = {ICPE '20}, title = {Predicting the Costs of Serverless Workflows}, year = 2020 }
• Telescope: An Automatic Feature Extraction and Transformation Approach for Time Series Forecasting on a Level-Playing Field. Bauer, Andr{é}; Z{ü}fle, Marwin; Herbst, Nikolas; Kounev, Samuel; Curtef, Valentin. In Proceedings of the 36th International Conference on Data Engineering (ICDE). 2020.
  • [ BibTeX ]
  @inproceedings{BaZuHeKoCu-ICDE-Telescope, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Herbst, Nikolas and Kounev, Samuel and Curtef, Valentin}, booktitle = {Proceedings of the 36th International Conference on Data Engineering (ICDE)}, keywords = {Prediction}, month = {04}, title = {Telescope: An Automatic Feature Extraction and Transformation Approach for Time Series Forecasting on a Level-Playing Field}, year = 2020 }
• {SPEC Research Group Newsletter, vol. 3 no. 1}. Kounev, Samuel; van Hoorn, Andre; Bauer, Andr{é}; Herbst, Nikolas. 2020, April.
  • [ BibTeX ]
  • [ URL ]
  @misc{kounev2020research, author = {Kounev, Samuel and van Hoorn, Andre and Bauer, Andr{\'e} and Herbst, Nikolas}, keywords = {se2}, month = {04}, note = {Published by Standard Performance Evaluation Corporation (SPEC)}, title = {{SPEC Research Group Newsletter, vol. 3 no. 1}}, year = 2020 }
• Predicting the Costs of Serverless Workflows. Eismann, Simon; Grohmann, Johannes; van Eyk, Erwin; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 2020 ACM/SPEC International Conference on Performance Engineering (ICPE), of ICPE ’20, pp. 265–276. Association for Computing Machinery (ACM), New York, NY, USA, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Function-as-a-Service (FaaS) platforms enable users to run arbitrary functions without being concerned about operational issues, while only paying for the consumed resources. Individual functions are often composed into workflows for complex tasks. However, the pay-per-use model and nontransparent reporting by cloud providers make it challenging to estimate the expected cost of a workflow, which prevents informed business decisions. Existing cost-estimation approaches assume a static response time for the serverless functions, without taking input parameters into account. In this paper, we propose a methodology for the cost prediction of serverless workflows consisting of input-parameter sensitive function models and a monte-carlo simulation of an abstract workflow model. Our approach enables workflow designers to predict, compare, and optimize the expected costs and performance of a planned workflow, which currently requires time-intensive experimentation. In our evaluation, we show that our approach can predict the response time and output parameters of a function based on its input parameters with an accuracy of 96.1%. In a case study with two audio-processing workflows, our approach predicts the costs of the two workflows with an accuracy of 96.2%.

  @inproceedings{EiGrEyHeKo2020-ICPE-ServerlessWorkflows, abstract = {Function-as-a-Service (FaaS) platforms enable users to run arbitrary functions without being concerned about operational issues, while only paying for the consumed resources. Individual functions are often composed into workflows for complex tasks. However, the pay-per-use model and nontransparent reporting by cloud providers make it challenging to estimate the expected cost of a workflow, which prevents informed business decisions. Existing cost-estimation approaches assume a static response time for the serverless functions, without taking input parameters into account. In this paper, we propose a methodology for the cost prediction of serverless workflows consisting of input-parameter sensitive function models and a monte-carlo simulation of an abstract workflow model. Our approach enables workflow designers to predict, compare, and optimize the expected costs and performance of a planned workflow, which currently requires time-intensive experimentation. In our evaluation, we show that our approach can predict the response time and output parameters of a function based on its input parameters with an accuracy of 96.1%. In a case study with two audio-processing workflows, our approach predicts the costs of the two workflows with an accuracy of 96.2%.}, address = {New York, NY, USA}, author = {Eismann, Simon and Grohmann, Johannes and van Eyk, Erwin and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 2020 ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {se2}, month = {04}, note = {{Acceptance Rate: 23.4% (15/64)}}, pages = {265–276}, publisher = {Association for Computing Machinery (ACM)}, series = {ICPE '20}, title = {Predicting the Costs of Serverless Workflows}, year = 2020 }
• {Microservices: A Performance Tester’s Dream or Nightmare?}. Eismann, Simon; Bezemer, Cor-Paul; Shang, Weiyi; Okanovic, Dusan; van Hoorn, Andre. In Proceedings of the 2020 ACM/SPEC International Conference on Performance Engineering (ICPE), of ICPE’20. 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In recent years, there has been a shift in software development towards microservice-based architectures, which consist of small services that focus on one particular functionality. Many companies are migrating their applications to such architectures to reap the benefits of microservices, such as increased flexibility, scalability and a smaller granularity of the offered functionality by a service. On the one hand, the benefits of microservices for functional testing are often praised, as the focus on one functionality and their smaller granularity allow for more targeted and more convenient testing. On the other hand, using microservices has their consequences (both positive and negative) on other types of testing, such as performance testing. Performance testing is traditionally done by establishing the baseline performance of a software version, which is then used to compare the performance testing results of later software versions. However, as we show in this paper, establishing such a baseline performance is challenging in microservice applications. In this paper, we discuss the benefits and challenges of microservices from a performance testers point of view. Through a series of experiments on the TeaStore application, we demonstrate how microservices affect the performance testing process, and we demonstrate that it is not straightforward to achieve reliable performance testing results for a microservice application.

  @inproceedings{EiBeShOkHo2020-ICPE-ServerlessWorkflows, abstract = {In recent years, there has been a shift in software development towards microservice-based architectures, which consist of small services that focus on one particular functionality. Many companies are migrating their applications to such architectures to reap the benefits of microservices, such as increased flexibility, scalability and a smaller granularity of the offered functionality by a service. On the one hand, the benefits of microservices for functional testing are often praised, as the focus on one functionality and their smaller granularity allow for more targeted and more convenient testing. On the other hand, using microservices has their consequences (both positive and negative) on other types of testing, such as performance testing. Performance testing is traditionally done by establishing the baseline performance of a software version, which is then used to compare the performance testing results of later software versions. However, as we show in this paper, establishing such a baseline performance is challenging in microservice applications. In this paper, we discuss the benefits and challenges of microservices from a performance testers point of view. Through a series of experiments on the TeaStore application, we demonstrate how microservices affect the performance testing process, and we demonstrate that it is not straightforward to achieve reliable performance testing results for a microservice application.}, author = {Eismann, Simon and Bezemer, Cor-Paul and Shang, Weiyi and Okanovic, Dusan and van Hoorn, Andre}, booktitle = {Proceedings of the 2020 ACM/SPEC International Conference on Performance Engineering (ICPE)}, keywords = {se2}, month = {04}, note = {{Acceptance Rate: 23.4% (15/64), ACM Artifacts Evaluated — Functional}}, series = {ICPE'20}, title = {{Microservices: A Performance Tester's Dream or Nightmare?}}, year = 2020 }
• Telescope: An Automatic Feature Extraction and Transformation Approach for Time Series Forecasting on a Level-Playing Field. Bauer, Andr{é}; Z{ü}fle, Marwin; Herbst, Nikolas; Kounev, Samuel; Curtef, Valentin. In Proceedings of the 36th International Conference on Data Engineering (ICDE). 2020.
  • [ BibTeX ]
  @inproceedings{BaZuHeKoCu-ICDE-Telescope, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Herbst, Nikolas and Kounev, Samuel and Curtef, Valentin}, booktitle = {Proceedings of the 36th International Conference on Data Engineering (ICDE)}, keywords = {Prediction}, month = {04}, title = {Telescope: An Automatic Feature Extraction and Transformation Approach for Time Series Forecasting on a Level-Playing Field}, year = 2020 }
• Optimizing HAS for 360-Degree Videos. Moldovan, Christian; Loh, Frank; Seufert, Michael; Hoßfeld, Tobias. In 5th IEEE/IFIP International Workshop on Analytics for Network and Service Management (AnNet). Budapest, Hungary, 2020.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2020-1, address = {Budapest, Hungary}, author = {Moldovan, Christian and Loh, Frank and Seufert, Michael and Hoßfeld, Tobias}, booktitle = {5th IEEE/IFIP International Workshop on Analytics for Network and Service Management (AnNet)}, keywords = {net-man}, month = {04}, title = {Optimizing HAS for 360-Degree Videos}, year = 2020 }
• MapLUR: Exploring a New Paradigm for Estimating Air Pollution Using Deep Learning on Map Images. Steininger, Michael; Kobs, Konstantin; Zehe, Albin; Lautenschlager, Florian; Becker, Martin; Hotho, Andreas. In ACM Trans. Spatial Algorithms Syst., 6(3). Association for Computing Machinery, New York, NY, USA, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Land-use regression (LUR) models are important for the assessment of air pollution concentrations in areas without measurement stations. While many such models exist, they often use manually constructed features based on restricted, locally available data. Thus, they are typically hard to reproduce and challenging to adapt to areas beyond those they have been developed for. In this paper, we advocate a paradigm shift for LUR models: We propose the Data-driven, Open, Global (DOG) paradigm that entails models based on purely data-driven approaches using only openly and globally available data. Progress within this paradigm will alleviate the need for experts to adapt models to the local characteristics of the available data sources and thus facilitate the generalizability of air pollution models to new areas on a global scale. In order to illustrate the feasibility of the DOG paradigm for LUR, we introduce a deep learning model called MapLUR. It is based on a convolutional neural network architecture and is trained exclusively on globally and openly available map data without requiring manual feature engineering. We compare our model to state-of-the-art baselines like linear regression, random forests and multi-layer perceptrons using a large data set of modeled NO2 concentrations in Central London. Our results show that MapLUR significantly outperforms these approaches even though they are provided with manually tailored features. Furthermore, we illustrate that the automatic feature extraction inherent to models based on the DOG paradigm can learn features that are readily interpretable and closely resemble those commonly used in traditional LUR approaches.

  @article{steininger2020maplur, abstract = {Land-use regression (LUR) models are important for the assessment of air pollution concentrations in areas without measurement stations. While many such models exist, they often use manually constructed features based on restricted, locally available data. Thus, they are typically hard to reproduce and challenging to adapt to areas beyond those they have been developed for. In this paper, we advocate a paradigm shift for LUR models: We propose the Data-driven, Open, Global (DOG) paradigm that entails models based on purely data-driven approaches using only openly and globally available data. Progress within this paradigm will alleviate the need for experts to adapt models to the local characteristics of the available data sources and thus facilitate the generalizability of air pollution models to new areas on a global scale. In order to illustrate the feasibility of the DOG paradigm for LUR, we introduce a deep learning model called MapLUR. It is based on a convolutional neural network architecture and is trained exclusively on globally and openly available map data without requiring manual feature engineering. We compare our model to state-of-the-art baselines like linear regression, random forests and multi-layer perceptrons using a large data set of modeled NO2 concentrations in Central London. Our results show that MapLUR significantly outperforms these approaches even though they are provided with manually tailored features. Furthermore, we illustrate that the automatic feature extraction inherent to models based on the DOG paradigm can learn features that are readily interpretable and closely resemble those commonly used in traditional LUR approaches.}, address = {New York, NY, USA}, author = {Steininger, Michael and Kobs, Konstantin and Zehe, Albin and Lautenschlager, Florian and Becker, Martin and Hotho, Andreas}, journal = {ACM Trans. Spatial Algorithms Syst.}, keywords = {pollution}, month = {04}, number = 3, publisher = {Association for Computing Machinery}, title = {MapLUR: Exploring a New Paradigm for Estimating Air Pollution Using Deep Learning on Map Images}, volume = 6, year = 2020 }
• {An Automated Forecasting Framework based on Method Recommendation for Seasonal Time Series}. Bauer, Andr{é}; Z{ü}fle, Marwin; Grohmann, Johannes; Schmitt, Norbert; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the ACM/SPEC International Conference on Performance Engineering, of ICPE ’20, pp. 48–55. Association for Computing Machinery (ACM), New York, NY, USA, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Due to the fast-paced and changing demands of their users, computing systems require autonomic resource management. To enable proactive and accurate decision-making for changes causing a particular overhead, reliable forecasts are needed. In fact, choosing the best performing forecasting method for a given time series scenario is a crucial task. Taking the "No-Free-Lunch Theorem" into account, there exists no forecasting method that performs best on all types of time series. To this end, we propose an automated approach that (i) extracts characteristics from a given time series, (ii) selects the best-suited machine learning method based on recommendation, and finally, (iii) performs the forecast. Our approach offers the benefit of not relying on a single method with its possibly inaccurate forecasts. In an extensive evaluation, our approach achieves the best forecasting accuracy.

  @inproceedings{BaZuGrScHeKo-ICPE20-Seasonal-Forecast, abstract = {Due to the fast-paced and changing demands of their users, computing systems require autonomic resource management. To enable proactive and accurate decision-making for changes causing a particular overhead, reliable forecasts are needed. In fact, choosing the best performing forecasting method for a given time series scenario is a crucial task. Taking the "No-Free-Lunch Theorem" into account, there exists no forecasting method that performs best on all types of time series. To this end, we propose an automated approach that (i) extracts characteristics from a given time series, (ii) selects the best-suited machine learning method based on recommendation, and finally, (iii) performs the forecast. Our approach offers the benefit of not relying on a single method with its possibly inaccurate forecasts. In an extensive evaluation, our approach achieves the best forecasting accuracy.}, address = {New York, NY, USA}, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Grohmann, Johannes and Schmitt, Norbert and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the ACM/SPEC International Conference on Performance Engineering}, keywords = {PRISMA}, month = {04}, pages = {48–55}, publisher = {Association for Computing Machinery (ACM)}, series = {ICPE '20}, title = {{An Automated Forecasting Framework based on Method Recommendation for Seasonal Time Series}}, year = 2020 }
• Don’t Stop the Music: Crowdsourced QoE Assessment of Music Streaming with Stalling. Schwind, Anika; Moldovan, Christian; Janiak, Tim; Dworschak, Nemo-Dario; Hoßfeld, Tobias. In 12th International Conference on Quality of Multimedia Experience (QoMEX). Athlone, Ireland, 2020.
  • [ Abstract ]
  • [ BibTeX ]
  Streaming made a lasting effect on the way our society consumes media in the last decade. While due to streaming the way we listen to music and podcasts has changed drastically, there are very few studies about its Quality of Experience (QoE) and possible influence factors. From video QoE studies, we know that, for example, undesirable stops of the stream (stalling events) have a significant impact on QoE. However, the way in which music and video streaming is consumed differs significantly, as music is often played in the background, and thus, the influence of stalling could be significantly different. Thus, this work evaluates the impact of stalling on music streaming QoE. Therefore, we conduct two crowdsourced user studies: In the first study, users have to rate four songs with different stalling patterns and evaluate the degree of impairments. Afterwards, we compare the ratings to the results of a lab study and show that they are highly correlated, and that crowdsourcing is a suitable way of measuring music streaming QoE. In addition, we conduct a second crowdsourcing study to investigate the influence of the user's attentiveness on QoE. Here, participants have to listen to one song with two stalling events, while one half of them had to transcribe a handwritten text with music playing in the background. The attentiveness shows no influence on the perceived streaming quality, but it shows a significant influence on the perceived quality degradation due to stalling events. Furthermore, considerably more stalling events were missed for workers who focused on the transcription. These results are an important step towards establishing new methods for investigating QoE in multimedia.

  @inproceedings{info3-inproceedings-2020-7, abstract = {Streaming made a lasting effect on the way our society consumes media in the last decade. While due to streaming the way we listen to music and podcasts has changed drastically, there are very few studies about its Quality of Experience (QoE) and possible influence factors. From video QoE studies, we know that, for example, undesirable stops of the stream (stalling events) have a significant impact on QoE. However, the way in which music and video streaming is consumed differs significantly, as music is often played in the background, and thus, the influence of stalling could be significantly different. Thus, this work evaluates the impact of stalling on music streaming QoE. Therefore, we conduct two crowdsourced user studies: In the first study, users have to rate four songs with different stalling patterns and evaluate the degree of impairments. Afterwards, we compare the ratings to the results of a lab study and show that they are highly correlated, and that crowdsourcing is a suitable way of measuring music streaming QoE. In addition, we conduct a second crowdsourcing study to investigate the influence of the user's attentiveness on QoE. Here, participants have to listen to one song with two stalling events, while one half of them had to transcribe a handwritten text with music playing in the background. The attentiveness shows no influence on the perceived streaming quality, but it shows a significant influence on the perceived quality degradation due to stalling events. Furthermore, considerably more stalling events were missed for workers who focused on the transcription. These results are an important step towards establishing new methods for investigating QoE in multimedia.}, address = {Athlone, Ireland}, author = {Schwind, Anika and Moldovan, Christian and Janiak, Tim and Dworschak, Nemo-Dario and Hoßfeld, Tobias}, booktitle = {12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ua-net}, month = {05}, title = {Don’t Stop the Music: Crowdsourced QoE Assessment of Music Streaming with Stalling}, year = 2020 }

• Greedy Rectilinear Drawings. Angelini, Patrizio; Bekos, Michael; Didimo, Walter; Grilli, Luca; Kindermann, Philipp; Mchedlidze, Tamara; Prutkin, Roman; Symvonis, Antonios; Tappini, Alessandra. In Theoretical Computer Science, 795, pp. 375–397. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  A drawing of a graph is greedy if for each ordered pair of vertices u and v, there is a path from u to v such that the Euclidean distance to v decreases monotonically at every vertex of the path. The existence of greedy drawings has been widely studied under different topological and geometric constraints, such as planarity, face convexity, and drawing succinctness. We introduce greedy rectilinear drawings, in which each edge is either a horizontal or a vertical segment. These drawings have several properties that improve human readability and support network routing. We address the problem of testing whether a planar rectilinear representation, i.e., a plane graph with specified vertex angles, admits vertex coordinates that define a greedy drawing. We provide a characterization, a linear-time testing algorithm, and a full generative scheme for universal greedy rectilinear representations, i.e., those for which every drawing is greedy. For general greedy rectilinear representations, we give a combinatorial characterization and, based on it, a polynomial-time testing and drawing algorithm for a meaningful subset of instances.

  @article{abdgkmpst-grd-gd18, abstract = {A drawing of a graph is greedy if for each ordered pair of vertices u and v, there is a path from u to v such that the Euclidean distance to v decreases monotonically at every vertex of the path. The existence of greedy drawings has been widely studied under different topological and geometric constraints, such as planarity, face convexity, and drawing succinctness. We introduce greedy rectilinear drawings, in which each edge is either a horizontal or a vertical segment. These drawings have several properties that improve human readability and support network routing. We address the problem of testing whether a planar rectilinear representation, i.e., a plane graph with specified vertex angles, admits vertex coordinates that define a greedy drawing. We provide a characterization, a linear-time testing algorithm, and a full generative scheme for universal greedy rectilinear representations, i.e., those for which every drawing is greedy. For general greedy rectilinear representations, we give a combinatorial characterization and, based on it, a polynomial-time testing and drawing algorithm for a meaningful subset of instances.}, author = {Angelini, Patrizio and Bekos, Michael and Didimo, Walter and Grilli, Luca and Kindermann, Philipp and Mchedlidze, Tamara and Prutkin, Roman and Symvonis, Antonios and Tappini, Alessandra}, journal = {Theoretical Computer Science}, keywords = {myown}, pages = {375–397}, title = {Greedy Rectilinear Drawings}, volume = 795, year = 2019 }
• Online model learning for self-aware computing infrastructures. Spinner, Simon; Grohmann, Johannes; Eismann, Simon; Kounev, Samuel. In Journal of Systems and Software, 147, pp. 1–16. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Performance models are valuable and powerful tools for performance prediction. However, the creation of performance models usually requires significant manual effort. Furthermore, as the modeled structures are subject to frequent change in modern infrastructures, such performance models need to be adapted as well. We therefore propose a reference architecture for online model learning in virtualized environments, which enables the automatic extraction of the aforementioned performance models. We follow an agent-based approach, which enables us to incorporate the extraction of information about the application structure as well as the virtualization structures present in modern computing centers. Our evaluation shows that our collaborating agents are able to reduce the manual effort of performance model extraction by 85.4%. The resulting performance model is able to predict the system utilization with an absolute error of less than 4% and the end-to-end response time with a relative error of less than 21%.

  @article{SpGrEiKo2019-JSS-ModelLearning, abstract = {Performance models are valuable and powerful tools for performance prediction. However, the creation of performance models usually requires significant manual effort. Furthermore, as the modeled structures are subject to frequent change in modern infrastructures, such performance models need to be adapted as well. We therefore propose a reference architecture for online model learning in virtualized environments, which enables the automatic extraction of the aforementioned performance models. We follow an agent-based approach, which enables us to incorporate the extraction of information about the application structure as well as the virtualization structures present in modern computing centers. Our evaluation shows that our collaborating agents are able to reduce the manual effort of performance model extraction by 85.4%. The resulting performance model is able to predict the system utilization with an absolute error of less than 4% and the end-to-end response time with a relative error of less than 21%.}, author = {Spinner, Simon and Grohmann, Johannes and Eismann, Simon and Kounev, Samuel}, journal = {Journal of Systems and Software}, keywords = {Virtualization}, pages = {1–16}, title = {Online model learning for self-aware computing infrastructures}, volume = 147, year = 2019 }
• NOracle: Who is communicating with whom in my network?. Kalmbach, Patrick; Hock, David; Lipp, Fabian; Kellerer, Wolfgang; Blenk, Andreas. In SIGCOMM Posters and Demos, pp. 48–50. ACM, 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{conf/sigcomm/KalmbachHLKB19, author = {Kalmbach, Patrick and Hock, David and Lipp, Fabian and Kellerer, Wolfgang and Blenk, Andreas}, booktitle = {SIGCOMM Posters and Demos}, crossref = {conf/sigcomm/2019p}, keywords = {myown}, pages = {48-50}, publisher = {ACM}, title = {NOracle: Who is communicating with whom in my network?}, year = 2019 }
• Stick Graphs with Length Constraints. Chaplick, Steven; Kindermann, Philipp; L{ö}ffler, Andre; Thiele, Florian; Wolff, Alexander; Zaft, Alexander; Zink, Johannes. In Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. T{ó}th (eds.), pp. 3–17. Springer-Verlag, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Stick graphs are intersection graphs of horizontal and vertical line segments that all touch a line of slope -1 and lie above this line. De Luca et al. [GD’18] considered the recognition problem of stick graphs when no order is given (STICK), when the order of either one of the two sets is given (STICK_A), and when the order of both sets is given (STICK_AB). They showed how to solve STICK_AB efficiently. In this paper, we improve the running time of their algorithm, and we solve STICK_A efficiently. Further, we consider variants of these problems where the lengths of the sticks are given as input. We show that these variants of STICK, STICK_A , and STICK_AB are all NP-complete. On the positive side, we give an efficient solution for STICK_AB with fixed stick lengths if there are no isolated vertices.

  @inproceedings{ckltwzz-sglc-gd19, abstract = {Stick graphs are intersection graphs of horizontal and vertical line segments that all touch a line of slope -1 and lie above this line. De Luca et al. [GD’18] considered the recognition problem of stick graphs when no order is given (STICK), when the order of either one of the two sets is given (STICK_A), and when the order of both sets is given (STICK_AB). They showed how to solve STICK_AB efficiently. In this paper, we improve the running time of their algorithm, and we solve STICK_A efficiently. Further, we consider variants of these problems where the lengths of the sticks are given as input. We show that these variants of STICK, STICK_A , and STICK_AB are all NP-complete. On the positive side, we give an efficient solution for STICK_AB with fixed stick lengths if there are no isolated vertices.}, author = {Chaplick, Steven and Kindermann, Philipp and L\"{o}ffler, Andre and Thiele, Florian and Wolff, Alexander and Zaft, Alexander and Zink, Johannes}, booktitle = {Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD'19)}, editor = {Archambault, Daniel and T\'{o}th, Csaba D.}, keywords = {myown}, pages = {3–17}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Stick Graphs with Length Constraints}, volume = 11904, year = 2019 }
• Towards Narrative-Driven Atmosphere for Virtual Classroom. Lugrin, Jean-Luc; Latoschik, Marc Erich; Glémarec, Yann; Bosser, Anne-Gween; Chollet, Mathieu; Lugrin, Birgit. In Extended Abstracts of the 2019 CHI Conference on Human Factors in Computing Systems, pp. 1–6. 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{lugrin2019towards, author = {Lugrin, Jean-Luc and Latoschik, Marc Erich and Glémarec, Yann and Bosser, Anne-Gween and Chollet, Mathieu and Lugrin, Birgit}, booktitle = {Extended Abstracts of the 2019 CHI Conference on Human Factors in Computing Systems}, keywords = {mi}, pages = {1-6}, title = {Towards Narrative-Driven Atmosphere for Virtual Classroom}, year = 2019 }
• Das Wissen in der 3D-Rekonstruktion. Münster, Sander; Messemer, Heike; Große, Peggy; Kuroczyński, Piotr; Niebling, Florian. In DHd 2019 Digital Humanities: multimedial & multimodal. Konferenzabstracts, Frankfurt am Main, P. Sahle (ed.), pp. 63–65. 2019.
  • [ BibTeX ]
  @inbook{RN15, author = {Münster, Sander and Messemer, Heike and Große, Peggy and Kuroczyński, Piotr and Niebling, Florian}, booktitle = {DHd 2019 Digital Humanities: multimedial & multimodal. Konferenzabstracts, Frankfurt am Main}, editor = {Sahle, Patrick}, keywords = {histstadt4d}, pages = {63-65}, title = {Das Wissen in der 3D-Rekonstruktion}, type = {Book Section}, year = 2019 }
• Rapid Preparation of Eye Tracking Data for Debriefung in Medical Training: A Feasibility Study. Wolf, Erik; Heinrich, Ronja; Michalek, Annabell; Schraudt, David; Hohm, Anna; Hein, Rebecca; Grundgeiger, Tobias; Happel, Oliver. In 2019 Human Factors and Ergonomics Society Annual Meeting, Vol. 63, pp. 733–737. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Simulation-based medical training is an increasingly used method to improve the technical and non-technical performance of clinical staff. An essential part of training is the debriefing of the participants, often using audio, video, or even eye tracking recordings. We conducted a practice-oriented feasibility study to test an eye tracking data preparation procedure, which automatically provided information about the gaze distribution on areas of interest such as the vital sign monitor or the patient simulator. We acquired eye tracking data during three simulation scenarios and provided gaze distribution data for debriefing within 30 minutes. Additionally, we qualitatively evaluated the usefulness of the generated eye tracking data for debriefings. Participating students and debriefers were mostly positive about the data provided; however, future research should improve the technical side of the procedure and investigate best practices regarding how to present and use the data in debriefings.

  @inproceedings{wolf2019rapid, abstract = {Simulation-based medical training is an increasingly used method to improve the technical and non-technical performance of clinical staff. An essential part of training is the debriefing of the participants, often using audio, video, or even eye tracking recordings. We conducted a practice-oriented feasibility study to test an eye tracking data preparation procedure, which automatically provided information about the gaze distribution on areas of interest such as the vital sign monitor or the patient simulator. We acquired eye tracking data during three simulation scenarios and provided gaze distribution data for debriefing within 30 minutes. Additionally, we qualitatively evaluated the usefulness of the generated eye tracking data for debriefings. Participating students and debriefers were mostly positive about the data provided; however, future research should improve the technical side of the procedure and investigate best practices regarding how to present and use the data in debriefings.}, author = {Wolf, Erik and Heinrich, Ronja and Michalek, Annabell and Schraudt, David and Hohm, Anna and Hein, Rebecca and Grundgeiger, Tobias and Happel, Oliver}, booktitle = {2019 Human Factors and Ergonomics Society Annual Meeting}, keywords = {piis}, number = 1, pages = {733-737}, title = {Rapid Preparation of Eye Tracking Data for Debriefung in Medical Training: A Feasibility Study}, volume = 63, year = 2019 }
• Head-Worn Displays and Spearcons: Supporting Multiple Patient Monitoring. Klueber, Sara; Wolf, Erik; Grundgeiger, Tobias; Brecknell, Birgit; Mohamed, Ismail; Sanderson, Penelope M. In Applied Ergonomics, 78, pp. 86–96. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In hospitals, clinicians often need to monitor several patients while performing other tasks. However, visual displays that show patients' vital signs are in fixed locations and auditory alarms intended to alert clinicians may be missed. Information such as spearcons (time-compressed speech earcons) that ‘travels’ with the clinician and is delivered by earpiece and/or head-worn displays (HWDs), might overcome these problems. In this study, non-clinicians monitored five simulated patients in three 10-min scenarios while performing a demanding tracking task. Monitoring accuracy was better for participants using spearcons and a HWD (88.7%) or a HWD alone (86.2%) than for participants using spearcons alone (74.1%). Participants using the spearcons and HWD (37.7%) performed the tracking task no differently from participants using spearcons alone (37.1%) but participants using the HWD alone performed worse overall (33.1%). The combination of both displays may be a suitable solution for monitoring multiple patients.

  @article{klueber2019headworn, abstract = {In hospitals, clinicians often need to monitor several patients while performing other tasks. However, visual displays that show patients' vital signs are in fixed locations and auditory alarms intended to alert clinicians may be missed. Information such as spearcons (time-compressed speech earcons) that ‘travels’ with the clinician and is delivered by earpiece and/or head-worn displays (HWDs), might overcome these problems. In this study, non-clinicians monitored five simulated patients in three 10-min scenarios while performing a demanding tracking task. Monitoring accuracy was better for participants using spearcons and a HWD (88.7%) or a HWD alone (86.2%) than for participants using spearcons alone (74.1%). Participants using the spearcons and HWD (37.7%) performed the tracking task no differently from participants using spearcons alone (37.1%) but participants using the HWD alone performed worse overall (33.1%). The combination of both displays may be a suitable solution for monitoring multiple patients.}, author = {Klueber, Sara and Wolf, Erik and Grundgeiger, Tobias and Brecknell, Birgit and Mohamed, Ismail and Sanderson, Penelope M.}, journal = {Applied Ergonomics}, keywords = {myown}, pages = {86-96}, title = {Head-Worn Displays and Spearcons: Supporting Multiple Patient Monitoring}, volume = 78, year = 2019 }
• Modeling and Evaluating Emotion, Contextual Head Movement and Voices for a Social Robot Storyteller. Striepe, Hendrik; Donnermann, Melissa; Lein, Martina; Lugrin, Birgit. In International Journal of Social Robotics. 2019.
  • [ BibTeX ]
  @article{Striepe2019, author = {Striepe, Hendrik and Donnermann, Melissa and Lein, Martina and Lugrin, Birgit}, journal = {International Journal of Social Robotics}, keywords = {lein}, title = {Modeling and Evaluating Emotion, Contextual Head Movement and Voices for a Social Robot Storyteller}, year = 2019 }
• Usability-Testing für Softwarewerkzeuge in den Digital Humanities am Beispiel von Bildrepositorien. Dewitz, Leyla; Münster, Sander; Niebling, Florian. In DHd 2019 Digital Humanities: multimedial & multimodal. Konferenzabstracts, Frankfurt am Main, P. Sahle (ed.), pp. 52–55. 2019.
  • [ BibTeX ]
  @article{dewitz2019usabilitytesting, author = {Dewitz, Leyla and Münster, Sander and Niebling, Florian}, editor = {Sahle, Patrick}, journal = {DHd 2019 Digital Humanities: multimedial & multimodal. Konferenzabstracts, Frankfurt am Main}, keywords = {histstadt4d}, pages = {52-55}, title = {Usability-Testing für Softwarewerkzeuge in den Digital Humanities am Beispiel von Bildrepositorien}, year = 2019 }
• Non-Native Speaker Generation and Perception for Mixed-Cultural Settings. Obremski, David; Lugrin, Jean-Luc; Schaper, Philipp; Lugrin, Birgit. In ACM International Conference on Intelligent Virtual Agents 2019. ACM, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  This paper presents an experiment evaluating the effects of virtual agents' language proficiency on whether they are perceived as a native speakers or not. Our first results indicate that beyond 10% word order mistakes and 25% infinitive mistakes, virtual agents are perceived as non-native speakers, even though their appearance and non-verbal behaviour were not altered. We believe these thresholds constitute interesting guidelines possibly simplifying the design of non-native speaker simulations.

  @article{obremski2019nonnative, abstract = {This paper presents an experiment evaluating the effects of virtual agents' language proficiency on whether they are perceived as a native speakers or not. Our first results indicate that beyond 10% word order mistakes and 25% infinitive mistakes, virtual agents are perceived as non-native speakers, even though their appearance and non-verbal behaviour were not altered. We believe these thresholds constitute interesting guidelines possibly simplifying the design of non-native speaker simulations.}, author = {Obremski, David and Lugrin, Jean-Luc and Schaper, Philipp and Lugrin, Birgit}, journal = {ACM International Conference on Intelligent Virtual Agents 2019}, keywords = {mi}, publisher = {ACM}, title = {Non-Native Speaker Generation and Perception for Mixed-Cultural Settings}, year = 2019 }
• HISTORICAL PHOTOS AND VISUALIZATIONS: POTENTIAL FOR RESEARCH. Dewitz, Leyla; Kröber, Cindy; Messemer, Heike; Maiwald, Ferdinand; Münster, Sander; Bruschke, Jonas; Niebling, Florian. In ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLII-2/W15, pp. 405–412. 2019.
  • [ BibTeX ]
  • [ URL ]
  @article{isprs-archives-XLII-2-W15-405-2019, author = {Dewitz, Leyla and Kröber, Cindy and Messemer, Heike and Maiwald, Ferdinand and Münster, Sander and Bruschke, Jonas and Niebling, Florian}, journal = {ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences}, keywords = {histstadt4d}, pages = {405–412}, title = {HISTORICAL PHOTOS AND VISUALIZATIONS: POTENTIAL FOR RESEARCH}, volume = {XLII-2/W15}, year = 2019 }
• Investigating Gesture-based Commands for First-Person Shooter Games in Virtual Reality. Schmitt, Johann; Lugrin, Jean-Luc; Carolin, and Wienrich; Latoschik, Marc Erich. In Proceedings of User-embodied Interaction in Virtual Reality, Mensch und Computer 2019. 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{LugrinGesture2019, author = {Schmitt, Johann and Lugrin, Jean-Luc and and Wienrich Carolin and Latoschik, Marc Erich}, booktitle = {Proceedings of User-embodied Interaction in Virtual Reality, Mensch und Computer 2019}, keywords = {c.wienrich}, title = {Investigating Gesture-based Commands for First-Person Shooter Games in Virtual Reality}, year = 2019 }
• Drone-Steering: A Novel VR Traveling Technique. Lugrin, Jean-Luc; Juchno, Andreas; Schaper, Philipp; Landeck, Maximilian; Latoschik, Marc Erich. In Proceedings of the 25th ACM Conference on Virtual Reality Software and Technology, Vol. VRST’19, P. of the 25th ACM Conference on Virtual Reality Software, Technology (eds.). 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{lugrin2019dronesteering, author = {Lugrin, Jean-Luc and Juchno, Andreas and Schaper, Philipp and Landeck, Maximilian and Latoschik, Marc Erich}, booktitle = {Proceedings of the 25th ACM Conference on Virtual Reality Software and Technology}, editor = {of the 25th ACM Conference on Virtual Reality Software, Proceedings and Technology}, keywords = {vrst19}, title = {Drone-Steering: A Novel VR Traveling Technique}, volume = {VRST'19}, year = 2019 }
• Introducing ACASS: An Annotated Character Animation Stimulus Set for Controlled (e)Motion Perception Studies. Lammers, Sebastian; Bente, Gary; Tepest, Ralf; Jording, Mathis; Roth, Daniel; Vogeley, Kai. In Frontiers in Robotics and AI, 6, p. 94. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Others' movements inform us about their current activities as well as their intentions and emotions. Research on the distinct mechanisms underlying action recognition and emotion inferences has been limited due to a lack of suitable comparative stimulus material. Problematic confounds can derive from low-level physical features (e.g., luminance), as well as from higher-level psychological features (e.g., stimulus difficulty). Here we present a standardized stimulus dataset, which allows to address both action and emotion recognition with identical stimuli. The stimulus set consists of 792 computer animations with a neutral avatar based on full body motion capture protocols. Motion capture was performed on 22 human volunteers, instructed to perform six everyday activities (mopping, sweeping, painting with a roller, painting with a brush, wiping, sanding) in three different moods (angry, happy, sad). Five-second clips of each motion protocol were rendered into AVI-files using two virtual camera perspectives for each clip. In contrast to video stimuli, the computer animations allowed to standardize the physical appearance of the avatar and to control lighting and coloring conditions, thus reducing the stimulus variation to mere movement. To control for low level optical features of the stimuli, we developed and applied a set of MATLAB routines extracting basic physical features of the stimuli, including average background-foreground proportion and frame-by-frame pixel change dynamics. This information was used to identify outliers and to homogenize the stimuli across action and emotion categories. This led to a smaller stimulus subset (n = 83 animations within the 792 clip database) which only contained two different actions (mopping, sweeping) and two different moods (angry, happy). To further homogenize this stimulus subset with regard to psychological criteria we conducted an online observer study (N = 112 participants) to assess the recognition rates for actions and moods, which led to a final sub-selection of 32 clips (eight per category) within the database. The ACASS database and its subsets provide unique opportunities for research applications in social psychology, social neuroscience, and applied clinical studies on communication disorders. All 792 AVI-files, selected subsets, MATLAB code, annotations, and motion capture data (FBX-files) are available online.

  @article{10.3389/frobt.2019.00094, abstract = {Others' movements inform us about their current activities as well as their intentions and emotions. Research on the distinct mechanisms underlying action recognition and emotion inferences has been limited due to a lack of suitable comparative stimulus material. Problematic confounds can derive from low-level physical features (e.g., luminance), as well as from higher-level psychological features (e.g., stimulus difficulty). Here we present a standardized stimulus dataset, which allows to address both action and emotion recognition with identical stimuli. The stimulus set consists of 792 computer animations with a neutral avatar based on full body motion capture protocols. Motion capture was performed on 22 human volunteers, instructed to perform six everyday activities (mopping, sweeping, painting with a roller, painting with a brush, wiping, sanding) in three different moods (angry, happy, sad). Five-second clips of each motion protocol were rendered into AVI-files using two virtual camera perspectives for each clip. In contrast to video stimuli, the computer animations allowed to standardize the physical appearance of the avatar and to control lighting and coloring conditions, thus reducing the stimulus variation to mere movement. To control for low level optical features of the stimuli, we developed and applied a set of MATLAB routines extracting basic physical features of the stimuli, including average background-foreground proportion and frame-by-frame pixel change dynamics. This information was used to identify outliers and to homogenize the stimuli across action and emotion categories. This led to a smaller stimulus subset (n = 83 animations within the 792 clip database) which only contained two different actions (mopping, sweeping) and two different moods (angry, happy). To further homogenize this stimulus subset with regard to psychological criteria we conducted an online observer study (N = 112 participants) to assess the recognition rates for actions and moods, which led to a final sub-selection of 32 clips (eight per category) within the database. The ACASS database and its subsets provide unique opportunities for research applications in social psychology, social neuroscience, and applied clinical studies on communication disorders. All 792 AVI-files, selected subsets, MATLAB code, annotations, and motion capture data (FBX-files) are available online.}, author = {Lammers, Sebastian and Bente, Gary and Tepest, Ralf and Jording, Mathis and Roth, Daniel and Vogeley, Kai}, journal = {Frontiers in Robotics and AI}, keywords = {insync}, pages = 94, title = {Introducing ACASS: An Annotated Character Animation Stimulus Set for Controlled (e)Motion Perception Studies}, volume = 6, year = 2019 }
• Computing Optimal-Height Tangles Faster. Firman, Oksana; Kindermann, Philipp; Ravsky, Alexander; Wolff, Alexander; Zink, Johannes. In Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. Tóth (eds.), pp. 203–215. Springer-Verlag, 2019.
  • [ BibTeX ]
  @inproceedings{fkrwz-cohtf-GD19, author = {Firman, Oksana and Kindermann, Philipp and Ravsky, Alexander and Wolff, Alexander and Zink, Johannes}, booktitle = {Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD'19)}, editor = {Archambault, Daniel and Tóth, Csaba D.}, keywords = {gd-info1}, pages = {203–215}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Computing Optimal-Height Tangles Faster}, volume = 11904, year = 2019 }
• Drawing Graphs on Few Circles and Few Spheres. Kryven, Myroslav; Ravsky, Alexander; Wolff, Alexander. In Journal of Graph Algorithms \& Applications, 23(2), pp. 371–391. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Given a drawing of a graph, its \emph{visual complexity} is defined as the number of geometrical entities in the drawing, for example, the number of segments in a straight-line drawing or the number of arcs in a circular-arc drawing (in 2D). Recently, Chaplick et al.\ [GD 2016] introduced a different measure for the visual complexity, the \emph{affine cover number}, which is the minimum number of lines (or planes) that together cover a crossing-free straight-line drawing of a graph G in 2D (3D). In this paper, we introduce the \emph{spherical cover number}, which is the minimum number of circles (or spheres) that together cover a crossing-free circular-arc drawing in 2D (or 3D). It turns out that spherical covers are sometimes significantly smaller than affine covers. For complete, complete bipartite, and platonic graphs, we analyze their spherical cover numbers and compare them to their affine cover numbers as well as their segment and arc numbers. We also link the spherical cover number to other graph parameters such as treewidth and linear arboricity.

  @article{krw-dgfcf-JGAA19, abstract = {Given a drawing of a graph, its \emph{visual complexity} is defined as the number of geometrical entities in the drawing, for example, the number of segments in a straight-line drawing or the number of arcs in a circular-arc drawing (in 2D). Recently, Chaplick et al.\ [GD 2016] introduced a different measure for the visual complexity, the \emph{affine cover number}, which is the minimum number of lines (or planes) that together cover a crossing-free straight-line drawing of a graph G in 2D (3D). In this paper, we introduce the \emph{spherical cover number}, which is the minimum number of circles (or spheres) that together cover a crossing-free circular-arc drawing in 2D (or 3D). It turns out that spherical covers are sometimes significantly smaller than affine covers. For complete, complete bipartite, and platonic graphs, we analyze their spherical cover numbers and compare them to their affine cover numbers as well as their segment and arc numbers. We also link the spherical cover number to other graph parameters such as treewidth and linear arboricity.}, author = {Kryven, Myroslav and Ravsky, Alexander and Wolff, Alexander}, journal = {Journal of Graph Algorithms \& Applications}, keywords = {gd-info1}, number = 2, pages = {371–391}, title = {Drawing Graphs on Few Circles and Few Spheres}, volume = 23, year = 2019 }
• Brain 2 Communicate: EEG-based Affect Recognition to Augment Virtual Social Interactions. Roth, Daniel; Westermeier, Franziska; Brübach, Larissa; Feigl, Tobias; Schell, Christian; Latoschik, Marc Erich. In Mensch und Computer 2019 - Workshopband. Gesellschaft für Informatik e.V., Bonn, 2019.
  • [ BibTeX ]
  • [ URL ]
  @conference{roth2019toappearbrain, address = {Bonn}, author = {Roth, Daniel and Westermeier, Franziska and Brübach, Larissa and Feigl, Tobias and Schell, Christian and Latoschik, Marc Erich}, booktitle = {Mensch und Computer 2019 - Workshopband}, keywords = {injectx}, publisher = {Gesellschaft für Informatik e.V.}, title = {Brain 2 Communicate: EEG-based Affect Recognition to Augment Virtual Social Interactions}, year = 2019 }
• "Paint that object yellow": Multimodal Interaction to Enhance Creativity During Design Tasks in VR. Wolf, Erik; Klüber, Sara; Zimmerer, Chris; Lugrin, Jean-Luc; Latoschik, Marc Erich. In 2019 International Conference on Multimodal Interaction, pp. 195–204. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Virtual reality (VR) has always been considered a promising medium to support designers with alternative work environments. Still, graphical user interfaces are prone to induce attention shifts between the user interface and the manipulated target objects which hampers the creative process. This work proposes a speech-and-gesture-based interaction paradigm for creative tasks in VR. We developed a multimodal toolbox (MTB) for VR-based design applications and compared it to a typical unimodal menu-based toolbox (UTB). The comparison uses a design-oriented use-case and mea-sures flow, usability, and presence as relevant characteristicsfor a VR-based design process. The multimodal approach (1) led to a lower perceived task duration and a higher reported feeling of flow. It (2) provided a higher intuitive use and a lower mental workload while not being slower than an UTB. Finally, it (3) generated a higher feeling of presence. Overall, our results confirm significant advantages of the proposed multimodal interaction paradigm and the developed MTB for important characteristics of design processes in VR.

  @inproceedings{wolf2019paint, abstract = {Virtual reality (VR) has always been considered a promising medium to support designers with alternative work environments. Still, graphical user interfaces are prone to induce attention shifts between the user interface and the manipulated target objects which hampers the creative process. This work proposes a speech-and-gesture-based interaction paradigm for creative tasks in VR. We developed a multimodal toolbox (MTB) for VR-based design applications and compared it to a typical unimodal menu-based toolbox (UTB). The comparison uses a design-oriented use-case and mea-sures flow, usability, and presence as relevant characteristicsfor a VR-based design process. The multimodal approach (1) led to a lower perceived task duration and a higher reported feeling of flow. It (2) provided a higher intuitive use and a lower mental workload while not being slower than an UTB. Finally, it (3) generated a higher feeling of presence. Overall, our results confirm significant advantages of the proposed multimodal interaction paradigm and the developed MTB for important characteristics of design processes in VR.}, author = {Wolf, Erik and Klüber, Sara and Zimmerer, Chris and Lugrin, Jean-Luc and Latoschik, Marc Erich}, booktitle = {2019 International Conference on Multimodal Interaction}, keywords = {mmi}, note = {Best Paper Runner-Up 🏆}, pages = {195-204}, title = {"Paint that object yellow": Multimodal Interaction to Enhance Creativity During Design Tasks in VR}, year = 2019 }
• Interactive Visualization of Multi-Cellular Tumor Spheroids. Knote, Andreas; Bernard, David; \textbf{S. {von Mammen}}; Cussat-Blanc, Sylvain. 2019.
  • [ BibTeX ]
  • [ URL ]
  @misc{Knote:2019ac, author = {Knote, Andreas and Bernard, David and \textbf{S. {von Mammen}} and Cussat-Blanc, Sylvain}, howpublished = {Poster, Visualizing Biological Data VIZBI 2019, Heidelberg, Germany}, keywords = {myown}, title = {Interactive Visualization of Multi-Cellular Tumor Spheroids}, year = 2019 }
• Virtuelle Realität als Ergänzung des Laufbandtrainings zur Rehabilitation von Gangstörungen bei Patienten mit Schlaganfall und Multipler Sklerose. Winter, Carla; Kern, Florian; Käthner, Ivo; Gall, Dominik; Latoschik, Marc Erich; Pauli, Paul. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Die Technik der virtuellen Realität (VR) bietet neue Behandlungsmöglichkeiten in der Rehabilitation neurologischer Erkrankungen. Vorherige Studien haben gezeigt, dass ein VR-basiertes Laufbandtraining bei Patienten mit Gangstörungen nicht nur den physischen, sondern auch den psychischen Therapieerfolg steigert und damit eine sinnvolle Ergänzung zum herkömmlichen Gangtraining darstellt. In der vorliegenden Studie wurde untersucht, welche Auswirkungen die immersive Darbietung einer virtuellen Umgebung (über ein Head-Mounted-Display, HMD) gegenüber der semi-immersiven Darbietung der VR (über einen Flachbildmonitor) und dem herkömmlichen Laufbandtraining ohne VR hat. Dazu durchliefen zunächst 36 gesunde Probanden und anschließend 14 MS- bzw. Schlaganfallpatienten mit Gangstörungen jeweils die drei verschiedenen Laufbandbedingungen (immersiv, semi-immersiv und ohne VR). Die eingesetzte virtuelle Umgebung enthielt Gamification-Elemente zur Motivationssteigerung und wurde auf Grundlage der Selbstbestimmungstheorie nach Ryan und Deci implementiert. Die Studie mit gesunden Probanden diente dazu, die Gebrauchstauglichkeit (Usability) zu prüfen und technische Defizite aufzudecken. In einer Proof-of-Concept-Studie mit 14 MS- und Schlaganfallpatienten wurde anschließend anhand der Anwendung getestet, ob Patienten mit einem VR-gestützten Laufbandtraining im Rahmen der Behandlung ihrer Gangstörungen (EDSS < 6) ihre Lauffähigkeiten verbessern können. Primäres Outcome Maß war in beiden Studien die durchschnittliche Laufgeschwindigkeit innerhalb der einzelnen Bedingungen. Mittels standardisierter Fragebögen wurden zusätzlich Motivation, Benutzerfreundlichkeit, Präsenzerleben (Igroup Presence Questionnaire) und Nebenwirkungen des VR-Systems (Simulator Sickness Questionnaire) untersucht. Außerdem wurde die Präferenz der Studienteilnehmer in Bezug auf die drei Bedingungen erfragt. Sowohl in der Studie mit gesunden Teilnehmern als auch in der Patientenstudie zeigte sich bei der HMD-Bedingung eine signifikant höhere durchschnittliche Laufgeschwindigkeit als beim Laufbandtraining ohne VR. Das Präsenzerleben war in beiden Studien in der HMD-Bedingung signifikant höher als in der Monitor-Bedingung. Darüber hinaus sind keine Nebenwirkungen durch die virtuelle Welt im Sinne einer Simulator Sickness aufgetreten. Die Studienteilnehmer hatten keine relevanten VR-bedingten Haltungsschwierigkeiten oder Probleme in Bezug auf das visuelle Display. Während die Motivation bei den gesunden Probanden nach dem HMD-Durchgang im Vergleich zu den anderen beiden Bedingungen höher ausfiel, wurden in der Patientenstudie keine signifikanten Unterschiede detektiert. Dennoch gaben die Patienten an, die virtuelle Welt in der HMD-Bedingung als motivierender empfunden zu haben als in der Monitor-Bedingung. Unter allen drei Bedingungen wurde das HMD-Laufbandtraining von 71 % (n = 14) der Patienten und 89 % (n = 36) der gesunden Versuchsteilnehmer präferiert. Ebenfalls 71 % der Patienten könnten sich vorstellen, das HMD-Laufbandtraining in Zukunft häufiger zu nutzen.

  @presentation{winter2019virtuelle, abstract = {Die Technik der virtuellen Realität (VR) bietet neue Behandlungsmöglichkeiten in der Rehabilitation neurologischer Erkrankungen. Vorherige Studien haben gezeigt, dass ein VR-basiertes Laufbandtraining bei Patienten mit Gangstörungen nicht nur den physischen, sondern auch den psychischen Therapieerfolg steigert und damit eine sinnvolle Ergänzung zum herkömmlichen Gangtraining darstellt. In der vorliegenden Studie wurde untersucht, welche Auswirkungen die immersive Darbietung einer virtuellen Umgebung (über ein Head-Mounted-Display, HMD) gegenüber der semi-immersiven Darbietung der VR (über einen Flachbildmonitor) und dem herkömmlichen Laufbandtraining ohne VR hat. Dazu durchliefen zunächst 36 gesunde Probanden und anschließend 14 MS- bzw. Schlaganfallpatienten mit Gangstörungen jeweils die drei verschiedenen Laufbandbedingungen (immersiv, semi-immersiv und ohne VR). Die eingesetzte virtuelle Umgebung enthielt Gamification-Elemente zur Motivationssteigerung und wurde auf Grundlage der Selbstbestimmungstheorie nach Ryan und Deci implementiert. Die Studie mit gesunden Probanden diente dazu, die Gebrauchstauglichkeit (Usability) zu prüfen und technische Defizite aufzudecken. In einer Proof-of-Concept-Studie mit 14 MS- und Schlaganfallpatienten wurde anschließend anhand der Anwendung getestet, ob Patienten mit einem VR-gestützten Laufbandtraining im Rahmen der Behandlung ihrer Gangstörungen (EDSS < 6) ihre Lauffähigkeiten verbessern können. Primäres Outcome Maß war in beiden Studien die durchschnittliche Laufgeschwindigkeit innerhalb der einzelnen Bedingungen. Mittels standardisierter Fragebögen wurden zusätzlich Motivation, Benutzerfreundlichkeit, Präsenzerleben (Igroup Presence Questionnaire) und Nebenwirkungen des VR-Systems (Simulator Sickness Questionnaire) untersucht. Außerdem wurde die Präferenz der Studienteilnehmer in Bezug auf die drei Bedingungen erfragt. Sowohl in der Studie mit gesunden Teilnehmern als auch in der Patientenstudie zeigte sich bei der HMD-Bedingung eine signifikant höhere durchschnittliche Laufgeschwindigkeit als beim Laufbandtraining ohne VR. Das Präsenzerleben war in beiden Studien in der HMD-Bedingung signifikant höher als in der Monitor-Bedingung. Darüber hinaus sind keine Nebenwirkungen durch die virtuelle Welt im Sinne einer Simulator Sickness aufgetreten. Die Studienteilnehmer hatten keine relevanten VR-bedingten Haltungsschwierigkeiten oder Probleme in Bezug auf das visuelle Display. Während die Motivation bei den gesunden Probanden nach dem HMD-Durchgang im Vergleich zu den anderen beiden Bedingungen höher ausfiel, wurden in der Patientenstudie keine signifikanten Unterschiede detektiert. Dennoch gaben die Patienten an, die virtuelle Welt in der HMD-Bedingung als motivierender empfunden zu haben als in der Monitor-Bedingung. Unter allen drei Bedingungen wurde das HMD-Laufbandtraining von 71 % (n = 14) der Patienten und 89 % (n = 36) der gesunden Versuchsteilnehmer präferiert. Ebenfalls 71 % der Patienten könnten sich vorstellen, das HMD-Laufbandtraining in Zukunft häufiger zu nutzen.}, author = {Winter, Carla and Kern, Florian and Käthner, Ivo and Gall, Dominik and Latoschik, Marc Erich and Pauli, Paul}, journal = {Ethik in der Medizin}, keywords = {homecoming}, number = 15, title = {Virtuelle Realität als Ergänzung des Laufbandtrainings zur Rehabilitation von Gangstörungen bei Patienten mit Schlaganfall und Multipler Sklerose}, volume = 14, year = 2019 }
• Survey of Performance Acceleration Techniques for Network Function Virtualization. Linguaglossa, Leonardo; Lange, Stanislav; Pontarelli, Salvatore; Retvari, Gabor; Rossi, Dario; Zinner, Thomas; Bificulo, Roberto; Jarschel, Michael; Bianchi, Giuseppe. In Proceedings of the IEEE. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  The ongoing network softwarization trend holds the promise to revolutionize network infrastructures by making them more flexible, reconfigurable, portable, and more adaptive than ever. Still, the migration from hard-coded/hardwired network functions towards their software-programmable counterparts comes along with the need for tailored optimizations and acceleration techniques, so as to avoid, or at least mitigate, the throughput/latency performance degradation with respect to fixed function network elements. The contribution of this article is twofold. First, we provide a comprehensive overview of the host-based Network Function Virtualization (NFV) ecosystem, covering a broad range of techniques, from low level hardware acceleration and bump-in-the-wire offloading approaches, to high-level software acceleration solutions, including the virtualization technique itself. Second, we derive guidelines regarding the design, development, and operation of NFV-based deployments that meet the flexibility and scalability requirements of modern communication networks.

  @article{info3-article-2019-1, abstract = {The ongoing network softwarization trend holds the promise to revolutionize network infrastructures by making them more flexible, reconfigurable, portable, and more adaptive than ever. Still, the migration from hard-coded/hardwired network functions towards their software-programmable counterparts comes along with the need for tailored optimizations and acceleration techniques, so as to avoid, or at least mitigate, the throughput/latency performance degradation with respect to fixed function network elements. The contribution of this article is twofold. First, we provide a comprehensive overview of the host-based Network Function Virtualization (NFV) ecosystem, covering a broad range of techniques, from low level hardware acceleration and bump-in-the-wire offloading approaches, to high-level software acceleration solutions, including the virtualization technique itself. Second, we derive guidelines regarding the design, development, and operation of NFV-based deployments that meet the flexibility and scalability requirements of modern communication networks.}, author = {Linguaglossa, Leonardo and Lange, Stanislav and Pontarelli, Salvatore and Retvari, Gabor and Rossi, Dario and Zinner, Thomas and Bificulo, Roberto and Jarschel, Michael and Bianchi, Giuseppe}, journal = {Proceedings of the IEEE}, keywords = {sendate}, month = {01}, title = {Survey of Performance Acceleration Techniques for Network Function Virtualization}, year = 2019 }
• Usability of Gamified Knowledge Learning in VR and Desktop-3D. Oberdörfer, Sebastian; Heidrich, David; Latoschik, Marc Erich. In Proceedings of the 2019 CHI Conference on Human Factors in Computing Systems, of CHI ’19, pp. 1–13. Association for Computing Machinery, New York, NY, USA, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Affine Transformations (ATs) often escape an intuitive approach due to their high complexity. Therefore, we developed GEtiT that directly encodes ATs in its game mechanics and scales the knowledge's level of abstraction. This results in an intuitive application as well as audiovisual presentation of ATs and hence in a knowledge learning. We also developed a specific Virtual Reality (VR) version to explore the effects of immersive VR on the learning outcomes. This paper presents our approach of directly encoding abstract knowledge in game mechanics, the conceptual design of GEtiT and its technical implementation. Both versions are compared in regard to their usability in a user study. The results show that both GEtiT versions induce a high degree of flow and elicit a good intuitive use. They validate the effectiveness of the design and the resulting knowledge application requirements. Participants favored GEtiT VR thus showing a potentially higher learning quality when using VR.

  @inproceedings{oberdorfertobepublishedusability, abstract = {Affine Transformations (ATs) often escape an intuitive approach due to their high complexity. Therefore, we developed GEtiT that directly encodes ATs in its game mechanics and scales the knowledge's level of abstraction. This results in an intuitive application as well as audiovisual presentation of ATs and hence in a knowledge learning. We also developed a specific Virtual Reality (VR) version to explore the effects of immersive VR on the learning outcomes. This paper presents our approach of directly encoding abstract knowledge in game mechanics, the conceptual design of GEtiT and its technical implementation. Both versions are compared in regard to their usability in a user study. The results show that both GEtiT versions induce a high degree of flow and elicit a good intuitive use. They validate the effectiveness of the design and the resulting knowledge application requirements. Participants favored GEtiT VR thus showing a potentially higher learning quality when using VR.}, address = {New York, NY, USA}, author = {Oberdörfer, Sebastian and Heidrich, David and Latoschik, Marc Erich}, booktitle = {Proceedings of the 2019 CHI Conference on Human Factors in Computing Systems}, keywords = {getit}, pages = {1-13}, publisher = {Association for Computing Machinery}, series = {CHI ’19}, title = {Usability of Gamified Knowledge Learning in VR and Desktop-3D}, year = 2019 }
• Monitorless: Predicting Performance Degradation in Cloud Applications with Machine Learning. Grohmann, Johannes; Nicholson, Patrick K.; Iglesias, Jesus Omana; Kounev, Samuel; Lugones, Diego. In Proceedings of the 20th International Middleware Conference, of Middleware ’19, pp. 149–162. Association for Computing Machinery (ACM), New York, NY, USA, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Today, software operation engineers rely on application key performance indicators (KPIs) for sizing and orchestrating cloud resources dynamically. KPIs are monitored to assess the achievable performance and to configure various cloud-specific parameters such as flavors of instances and autoscaling rules, among others. Usually, keeping KPIs within acceptable levels requires application expertise which is expensive and can slow down the continuous delivery of software. Expertise is required because KPIs are normally based on application-specific quality-of-service metrics, like service response time and processing rate, instead of generic platform metrics, like those typical across various environments (e.g., CPU and memory utilization, I/O rate, etc.)In this paper, we investigate the feasibility of outsourcing the management of application performance from developers to cloud operators. In the same way that the serverless paradigm allows the execution environment to be fully managed by a third party, we discuss a monitorless model to streamline application deployment by delegating performance management. We show that training a machine learning model with platform-level data, collected from the execution of representative containerized services, allows inferring application KPI degradation. This is an opportunity to simplify operations as engineers can rely solely on platform metrics -- while still fulfilling application KPIs -- to configure portable and application agnostic rules and other cloud-specific parameters to automatically trigger actions such as autoscaling, instance migration, network slicing, etc.Results show that monitorless infers KPI degradation with an accuracy of 97% and, notably, it performs similarly to typical autoscaling solutions, even when autoscaling rules are optimally tuned with knowledge of the expected workload.

  @inproceedings{GrNiIgKoLu-MIDDLEWARE2019-Monitorless, abstract = {Today, software operation engineers rely on application key performance indicators (KPIs) for sizing and orchestrating cloud resources dynamically. KPIs are monitored to assess the achievable performance and to configure various cloud-specific parameters such as flavors of instances and autoscaling rules, among others. Usually, keeping KPIs within acceptable levels requires application expertise which is expensive and can slow down the continuous delivery of software. Expertise is required because KPIs are normally based on application-specific quality-of-service metrics, like service response time and processing rate, instead of generic platform metrics, like those typical across various environments (e.g., CPU and memory utilization, I/O rate, etc.)In this paper, we investigate the feasibility of outsourcing the management of application performance from developers to cloud operators. In the same way that the serverless paradigm allows the execution environment to be fully managed by a third party, we discuss a monitorless model to streamline application deployment by delegating performance management. We show that training a machine learning model with platform-level data, collected from the execution of representative containerized services, allows inferring application KPI degradation. This is an opportunity to simplify operations as engineers can rely solely on platform metrics – while still fulfilling application KPIs – to configure portable and application agnostic rules and other cloud-specific parameters to automatically trigger actions such as autoscaling, instance migration, network slicing, etc.Results show that monitorless infers KPI degradation with an accuracy of 97% and, notably, it performs similarly to typical autoscaling solutions, even when autoscaling rules are optimally tuned with knowledge of the expected workload.}, address = {New York, NY, USA}, author = {Grohmann, Johannes and Nicholson, Patrick K. and Iglesias, Jesus Omana and Kounev, Samuel and Lugones, Diego}, booktitle = {Proceedings of the 20th International Middleware Conference}, keywords = {Virtualization}, pages = {149–162}, publisher = {Association for Computing Machinery (ACM)}, series = {Middleware '19}, title = {Monitorless: Predicting Performance Degradation in Cloud Applications with Machine Learning}, year = 2019 }
• Maximum Matchings and Minimum Blocking Sets in $\Theta_6$-Graphs. Biedl, Therese; Biniaz, Ahmad; Irvine, Veronika; Jain, Kshitij; Kindermann, Philipp; Lubiw, Anna. In Proceedings of the 35th European Workshop on Computational Geometry (EuroCG’19), M. Löffler (ed.). Utrecht, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Theta_6-graphs are important geometric graphs that have many applications. They are equivalent to Delaunay graphs where empty equilateral triangles with a horizontal edge take the place of empty circles. We investigate lower bounds on the size of maximum matchings in these graphs. The best known lower bound is (n-1)/3, where n is the number of vertices of the graph. Babu et al. (2014) conjectured that any Theta_6-graph has a perfect matching (as is true for standard Delaunay graphs). Although this conjecture remains open, we improve the lower bound to (3n-8)/7. We also relate the size of maximum matchings in Theta_6-graphs to the minimum size of a blocking set. Every edge of a Theta_6-graph on a point set P corresponds to an empty triangle that contains the endpoints of the edge but no other point of P. A blocking set has at least one point in each such triangle. We prove that the size of a maximum matching is at least b(n)/2 where b(n) is the minimum, over all Theta_6-graphs with n vertices, of the minimum size of a blocking set. In the other direction, lower bounds on matchings allow us to show that b(n) >= 3n/4 - 2.

  @inproceedings{bbijkl-mmmbs-eurocg19, abstract = {Theta_6-graphs are important geometric graphs that have many applications. They are equivalent to Delaunay graphs where empty equilateral triangles with a horizontal edge take the place of empty circles. We investigate lower bounds on the size of maximum matchings in these graphs. The best known lower bound is (n-1)/3, where n is the number of vertices of the graph. Babu et al. (2014) conjectured that any Theta_6-graph has a perfect matching (as is true for standard Delaunay graphs). Although this conjecture remains open, we improve the lower bound to (3n-8)/7. We also relate the size of maximum matchings in Theta_6-graphs to the minimum size of a blocking set. Every edge of a Theta_6-graph on a point set P corresponds to an empty triangle that contains the endpoints of the edge but no other point of P. A blocking set has at least one point in each such triangle. We prove that the size of a maximum matching is at least b(n)/2 where b(n) is the minimum, over all Theta_6-graphs with n vertices, of the minimum size of a blocking set. In the other direction, lower bounds on matchings allow us to show that b(n) >= 3n/4 - 2.}, author = {Biedl, Therese and Biniaz, Ahmad and Irvine, Veronika and Jain, Kshitij and Kindermann, Philipp and Lubiw, Anna}, booktitle = {Proceedings of the 35th European Workshop on Computational Geometry (EuroCG'19)}, editor = {Löffler, Maarten}, keywords = {myown}, note = {Abstract}, publisher = {Utrecht}, title = {Maximum Matchings and Minimum Blocking Sets in $\Theta_6$-Graphs}, year = 2019 }
• Machine Learning Models for YouTube QoE and User Engagement Prediction in Smartphones. Wassermann, Sarah; Wehner, Nikolas; Casas, Pedro. In ACM SIGMETRICS Performance Evaluation Review, 46(3), pp. 155–158. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Measuring and monitoring YouTube Quality of Experience is a challenging task, especially when dealing with cellular networks and smartphone users. Using a large-scale database of crowdsourced YouTube-QoE measurements in smartphones, we conceive multiple machine-learning models to infer different YouTube-QoE-relevant metrics and userbehavior- related metrics from network-level measurements, without requiring root access to the smartphone, video-player embedding, or any other reverse-engineering-like approaches. The dataset includes measurements from more than 360 users worldwide, spanning over the last five years. Our preliminary results suggest that QoE-based monitoring of YouTube mobile can be realized through machine learning models with high accuracy, relying only on network-related features and without accessing any higher-layer metric to perform the estimations.

  @article{info3-article-2019-10, abstract = {Measuring and monitoring YouTube Quality of Experience is a challenging task, especially when dealing with cellular networks and smartphone users. Using a large-scale database of crowdsourced YouTube-QoE measurements in smartphones, we conceive multiple machine-learning models to infer different YouTube-QoE-relevant metrics and userbehavior- related metrics from network-level measurements, without requiring root access to the smartphone, video-player embedding, or any other reverse-engineering-like approaches. The dataset includes measurements from more than 360 users worldwide, spanning over the last five years. Our preliminary results suggest that QoE-based monitoring of YouTube mobile can be realized through machine learning models with high accuracy, relying only on network-related features and without accessing any higher-layer metric to perform the estimations.}, author = {Wassermann, Sarah and Wehner, Nikolas and Casas, Pedro}, journal = {ACM SIGMETRICS Performance Evaluation Review}, keywords = {copy}, month = {01}, number = 3, pages = {155-158}, title = {Machine Learning Models for YouTube QoE and User Engagement Prediction in Smartphones}, volume = 46, year = 2019 }
• Resilience, Availability, and Serviceability Evaluation in Software-defined Networks. Technical Report (PhD dissertation), . Metter, Christopher. PhD dissertation. Universitiy of Würzburg, 2019, January.
  • [ BibTeX ]
  @phdthesis{info3-dissertation-2019-1, author = {Metter, Christopher}, keywords = {myown}, month = {01}, school = {Universitiy of Würzburg}, title = {Resilience, Availability, and Serviceability Evaluation in Software-defined Networks}, year = 2019 }
• Maximum Matchings and Minimum Blocking Sets in $\Theta_6$-Graphs. Biedl, Therese; Biniaz, Ahmad; Irvine, Veronika; Jain, Kshitij; Kindermann, Philipp; Lubiw, Anna. In Proceedings of the 45th International Workshop on Graph-Theoretic Concepts in Computer Science (WG’19), Vol. 11789 of Lecture Notes in Computer Science, I. Sau, D. M. Thilikos (eds.), pp. 258–270. Springer-Verlag, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Theta_6-graphs are important geometric graphs that have many applications. They are equivalent to Delaunay graphs where empty equilateral triangles with a horizontal edge take the place of empty circles. We investigate lower bounds on the size of maximum matchings in these graphs. The best known lower bound is (n-1)/3, where n is the number of vertices of the graph. Babu et al. (2014) conjectured that any Theta_6-graph has a perfect matching (as is true for standard Delaunay graphs). Although this conjecture remains open, we improve the lower bound to (3n-8)/7. We also relate the size of maximum matchings in Theta_6-graphs to the minimum size of a blocking set. Every edge of a Theta_6-graph on a point set P corresponds to an empty triangle that contains the endpoints of the edge but no other point of P. A blocking set has at least one point in each such triangle. We prove that the size of a maximum matching is at least b(n)/2 where b(n) is the minimum, over all Theta_6-graphs with n vertices, of the minimum size of a blocking set. In the other direction, lower bounds on matchings allow us to show that b(n) >= 3n/4 - 2.

  @inproceedings{bbijkl-mmmbs-wg19, abstract = {Theta_6-graphs are important geometric graphs that have many applications. They are equivalent to Delaunay graphs where empty equilateral triangles with a horizontal edge take the place of empty circles. We investigate lower bounds on the size of maximum matchings in these graphs. The best known lower bound is (n-1)/3, where n is the number of vertices of the graph. Babu et al. (2014) conjectured that any Theta_6-graph has a perfect matching (as is true for standard Delaunay graphs). Although this conjecture remains open, we improve the lower bound to (3n-8)/7. We also relate the size of maximum matchings in Theta_6-graphs to the minimum size of a blocking set. Every edge of a Theta_6-graph on a point set P corresponds to an empty triangle that contains the endpoints of the edge but no other point of P. A blocking set has at least one point in each such triangle. We prove that the size of a maximum matching is at least b(n)/2 where b(n) is the minimum, over all Theta_6-graphs with n vertices, of the minimum size of a blocking set. In the other direction, lower bounds on matchings allow us to show that b(n) >= 3n/4 - 2.}, author = {Biedl, Therese and Biniaz, Ahmad and Irvine, Veronika and Jain, Kshitij and Kindermann, Philipp and Lubiw, Anna}, booktitle = {Proceedings of the 45th International Workshop on Graph-Theoretic Concepts in Computer Science (WG'19)}, editor = {Sau, Ignasi and Thilikos, Dimitrios M.}, keywords = {myown}, pages = {258–270}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Maximum Matchings and Minimum Blocking Sets in $\Theta_6$-Graphs}, volume = 11789, year = 2019 }
• Computing Optimal Tangles Faster. Firman, Oksana; Kindermann, Philipp; Ravsky, Alexander; Wolff, Alexander; Zink, Johannes. In Proceedings of the 35th European Workshop on Computational Geometry (EuroCG’19), M. Löffler (ed.). Utrecht, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  We study the following combinatorial problem. Given a set of n y-monotone wires, a tangle determines the order of the wires on a number of horizontal layers such that the orders of the wires on any two consecutive layers differ only in swaps of neighboring wires. Given a multiset L of swaps (that is, unordered pairs of numbers between 1 and n) and an initial order of the wires, a tangle realizes L if each pair of wires changes its order exactly as many times as specified by L. The aim is to find a tangle that realizes L using the smallest number of layers. We show that this problem is NP-hard, and we give an algorithm that computes an optimal tangle for n wires and a given list L of swaps in O((2|L|/n^2+1)^(n^2/2)phi^n n) time, where phi~1.618 is the golden ratio. We can treat lists where every swap occurs at most once in O(n! phi^n) time. We implemented the algorithm for the general case and compared it to an existing algorithm.

  @inproceedings{fkrwz-cotf-eurocg19, abstract = {We study the following combinatorial problem. Given a set of n y-monotone wires, a tangle determines the order of the wires on a number of horizontal layers such that the orders of the wires on any two consecutive layers differ only in swaps of neighboring wires. Given a multiset L of swaps (that is, unordered pairs of numbers between 1 and n) and an initial order of the wires, a tangle realizes L if each pair of wires changes its order exactly as many times as specified by L. The aim is to find a tangle that realizes L using the smallest number of layers. We show that this problem is NP-hard, and we give an algorithm that computes an optimal tangle for n wires and a given list L of swaps in O((2|L|/n^2+1)^(n^2/2)phi^n n) time, where phi 1.618 is the golden ratio. We can treat lists where every swap occurs at most once in O(n! phi^n) time. We implemented the algorithm for the general case and compared it to an existing algorithm.}, author = {Firman, Oksana and Kindermann, Philipp and Ravsky, Alexander and Wolff, Alexander and Zink, Johannes}, booktitle = {Proceedings of the 35th European Workshop on Computational Geometry (EuroCG'19)}, editor = {Löffler, Maarten}, keywords = {myown}, note = {Abstract}, publisher = {Utrecht}, title = {Computing Optimal Tangles Faster}, year = 2019 }
• Computing Optimal Tangles Faster. Firman, Oksana; Kindermann, Philipp; Ravsky, Alexander; Wolff, Alexander; Zink, Johannes. In Proceedings of the 12th Annual Meeting of the Asian Association for Algorithms and Computation (AAAC’19), S.-W. Cheng (ed.). Seoul, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  We study the following combinatorial problem. Given a set of n y-monotone wires, a tangle determines the order of the wires on a number of horizontal layers such that the orders of the wires on any two consecutive layers differ only in swaps of neighboring wires. Given a multiset L of swaps (that is, unordered pairs of numbers between 1 and n) and an initial order of the wires, a tangle realizes L if each pair of wires changes its order exactly as many times as specified by L. The aim is to find a tangle that realizes L using the smallest number of layers. We show that this problem is NP-hard, and we give an algorithm that computes an optimal tangle for n wires and a given list L of swaps in O((2|L|/n^2+1)^(n^2/2)phi^n n) time, where phi~1.618 is the golden ratio. We can treat lists where every swap occurs at most once in O(n! phi^n) time. We implemented the algorithm for the general case and compared it to an existing algorithm.

  @inproceedings{fkrwz-cotf-aaac19, abstract = {We study the following combinatorial problem. Given a set of n y-monotone wires, a tangle determines the order of the wires on a number of horizontal layers such that the orders of the wires on any two consecutive layers differ only in swaps of neighboring wires. Given a multiset L of swaps (that is, unordered pairs of numbers between 1 and n) and an initial order of the wires, a tangle realizes L if each pair of wires changes its order exactly as many times as specified by L. The aim is to find a tangle that realizes L using the smallest number of layers. We show that this problem is NP-hard, and we give an algorithm that computes an optimal tangle for n wires and a given list L of swaps in O((2|L|/n^2+1)^(n^2/2)phi^n n) time, where phi 1.618 is the golden ratio. We can treat lists where every swap occurs at most once in O(n! phi^n) time. We implemented the algorithm for the general case and compared it to an existing algorithm.}, author = {Firman, Oksana and Kindermann, Philipp and Ravsky, Alexander and Wolff, Alexander and Zink, Johannes}, booktitle = {Proceedings of the 12th Annual Meeting of the Asian Association for Algorithms and Computation (AAAC'19)}, editor = {Cheng, Siu-Wing}, keywords = {myown}, note = {Abstract}, publisher = {Seoul}, title = {Computing Optimal Tangles Faster}, year = 2019 }
• Experience-based Quality Assessment of Distributed Knowledge Graphs. Baumeister, Joachim. In WM 2019 - 10te Konferenz Professionelles Wissensmanagement. 2019.
  • [ BibTeX ]
  @inproceedings{baumeister2019experiencebased, author = {Baumeister, Joachim}, booktitle = {WM 2019 - 10te Konferenz Professionelles Wissensmanagement}, keywords = {anomalies}, title = {Experience-based Quality Assessment of Distributed Knowledge Graphs}, year = 2019 }
• Comparison of System Call Representations for Intrusion Detection. Wunderlich, Sarah; Ring, Markus; Landes, Dieter; Hotho, Andreas. In CISIS-ICEUTE, Vol. 951 of Advances in Intelligent Systems and Computing, F. Martínez-Álvarez, A. T. Lora, J. A. S. Muñoz, H. Quintián, E. Corchado (eds.), pp. 14–24. Springer, 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{wunderlich2019comparison, author = {Wunderlich, Sarah and Ring, Markus and Landes, Dieter and Hotho, Andreas}, booktitle = {CISIS-ICEUTE}, crossref = {conf/cisis-spain/2019}, editor = {Martínez-Álvarez, Francisco and Lora, Alicia Troncoso and Muñoz, José António Sáez and Quintián, Héctor and Corchado, Emilio}, keywords = {ml}, pages = {14-24}, publisher = {Springer}, series = {Advances in Intelligent Systems and Computing}, title = {Comparison of System Call Representations for Intrusion Detection.}, volume = 951, year = 2019 }
• A Survey of Network-based Intrusion Detection Data Sets. Ring, Markus; Wunderlich, Sarah; Scheuring, Deniz; Landes, Dieter; Hotho, Andreas. In Computers & Security, 86, pp. 147–167. Elsevier Advanced Technology, 2019.
  • [ BibTeX ]
  • [ URL ]
  @article{ring2019survey, author = {Ring, Markus and Wunderlich, Sarah and Scheuring, Deniz and Landes, Dieter and Hotho, Andreas}, journal = {Computers & Security}, keywords = {datasets}, pages = {147-167}, publisher = {Elsevier Advanced Technology}, title = {A Survey of Network-based Intrusion Detection Data Sets}, volume = 86, year = 2019 }
• The Interplay between QoE, User Behavior and System Blocking in QoE Management. Hoßfeld, Tobias; Atzori, Luigi; Heegaard, Poul E.; Skorin-Kapov, Lea; Varela, Martin. In 22nd Conference on Innovation in Clouds, Internet and Networks and Workshops (ICIN). 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-15, author = {Hoßfeld, Tobias and Atzori, Luigi and Heegaard, Poul E. and Skorin-Kapov, Lea and Varela, Martin}, booktitle = {22nd Conference on Innovation in Clouds, Internet and Networks and Workshops (ICIN)}, keywords = {myown}, title = {The Interplay between QoE, User Behavior and System Blocking in QoE Management}, year = 2019 }
• Immersive Virtual Reality and Gamification Within Procedurally Generated Environments to Increase Motivation During Gait Rehabilitation. Kern, Florian; Winter, Carla; Gall, Dominik; Käthner, Ivo; Pauli, Paul; Latoschik, Marc Erich. In 2019 IEEE Conference on Virtual Reality and 3D User Interfaces (VR), pp. 500–509. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Virtual Reality (VR) technology offers promising opportunities to improve traditional treadmill-based rehabilitation programs. We present an immersive VR rehabilitation system that includes a head-mounted display and motion sensors. The application is designed to promote the experience of relatedness, autonomy, and competence. The application uses procedural content generation to generate diverse landscapes. We evaluated the effect of the immersive rehabilitation system on motivation and affect. We conducted a repeated measures study with 36 healthy participants to compare the immersive program to a traditional rehabilitation program. Participants reported significant greater enjoyment, felt more competent and experienced higher decision freedom and meaningfulness in the immersive VR gait training compared to the traditional training. They experienced significantly lower physical demand, simulator sickness, and state anxiety, and felt less pressured while still perceiving a higher personal performance. We derive three design implications for future applications in gait rehabilitation: Immersive VR provides a promising augmentation for gait rehabilitation. Gamification features provide a design guideline for content creation in gait rehabilitation. Relatedness and autonomy provide critical content features in gait rehabilitation.

  @inproceedings{kern2019immersive, abstract = {Virtual Reality (VR) technology offers promising opportunities to improve traditional treadmill-based rehabilitation programs. We present an immersive VR rehabilitation system that includes a head-mounted display and motion sensors. The application is designed to promote the experience of relatedness, autonomy, and competence. The application uses procedural content generation to generate diverse landscapes. We evaluated the effect of the immersive rehabilitation system on motivation and affect. We conducted a repeated measures study with 36 healthy participants to compare the immersive program to a traditional rehabilitation program. Participants reported significant greater enjoyment, felt more competent and experienced higher decision freedom and meaningfulness in the immersive VR gait training compared to the traditional training. They experienced significantly lower physical demand, simulator sickness, and state anxiety, and felt less pressured while still perceiving a higher personal performance. We derive three design implications for future applications in gait rehabilitation: Immersive VR provides a promising augmentation for gait rehabilitation. Gamification features provide a design guideline for content creation in gait rehabilitation. Relatedness and autonomy provide critical content features in gait rehabilitation.}, author = {Kern, Florian and Winter, Carla and Gall, Dominik and Käthner, Ivo and Pauli, Paul and Latoschik, Marc Erich}, booktitle = {2019 IEEE Conference on Virtual Reality and 3D User Interfaces (VR)}, keywords = {homecoming}, pages = {500-509}, title = {Immersive Virtual Reality and Gamification Within Procedurally Generated Environments to Increase Motivation During Gait Rehabilitation}, year = 2019 }
• Graph Drawing Contest Report. Kindermann, Philipp; Mchedlidze, Tamara; Rutter, Ignaz. In Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. T{ó}th (eds.), pp. 575–583. Springer-Verlag, 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{kmr-gdcr-gd19, author = {Kindermann, Philipp and Mchedlidze, Tamara and Rutter, Ignaz}, booktitle = {Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD'19)}, editor = {Archambault, Daniel and T\'{o}th, Csaba D.}, keywords = {myown}, pages = {575–583}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Graph Drawing Contest Report}, volume = 11904, year = 2019 }
• Lombardi Drawings of Knots and Links. Kindermann, Philipp; Kobourov, Stephen; L{ö}ffler, Maarten; N{ö}llenburg, Martin; Schulz, Andr{é}; Vogtenhuber, Birgit. In Journal of Computational Geometry, 10(1), pp. 444–476. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Knot and link diagrams are projections of one or more 3-dimensional simple closed curves into $R^2$, such that no more than two points project to the same point in $R^2$. These diagrams are drawings of 4-regular plane multigraphs. Knots are typically smooth curves in $R^3$, so their projections should be smooth curves in $R^2$ with good continuity and large crossing angles: exactly the properties of Lombardi graph drawings (defined by circular-arc edges and perfect angular resolution). We show that several knots do not allow Lombardi drawings. On the other hand, we identify a large class of 4-regular plane multigraphs that do have Lombardi drawings. We then study two relaxations of Lombardi drawings and show that every knot admits a plane 2-Lombardi drawing (where edges are composed of two circular arcs). Further, every knot is \emph{near-Lombardi}, that is, it can be drawn as Lombardi drawing when relaxing the angular resolution requirement by an arbitrary small angular offset $\eps$, while maintaining a $180^\circ$ angle between opposite edges.

  @article{kklnsv-ldkl-jocg19, abstract = {Knot and link diagrams are projections of one or more 3-dimensional simple closed curves into $R^2$, such that no more than two points project to the same point in $R^2$. These diagrams are drawings of 4-regular plane multigraphs. Knots are typically smooth curves in $R^3$, so their projections should be smooth curves in $R^2$ with good continuity and large crossing angles: exactly the properties of Lombardi graph drawings (defined by circular-arc edges and perfect angular resolution). We show that several knots do not allow Lombardi drawings. On the other hand, we identify a large class of 4-regular plane multigraphs that do have Lombardi drawings. We then study two relaxations of Lombardi drawings and show that every knot admits a plane 2-Lombardi drawing (where edges are composed of two circular arcs). Further, every knot is \emph{near-Lombardi}, that is, it can be drawn as Lombardi drawing when relaxing the angular resolution requirement by an arbitrary small angular offset $\eps$, while maintaining a $180^\circ$ angle between opposite edges.}, author = {Kindermann, Philipp and Kobourov, Stephen and L{\"o}ffler, Maarten and N{\"o}llenburg, Martin and Schulz, Andr{\'e} and Vogtenhuber, Birgit}, journal = {Journal of Computational Geometry}, keywords = {myown}, number = 1, pages = {444–476}, title = {Lombardi Drawings of Knots and Links}, volume = 10, year = 2019 }
• On the Right Track! Analysing and Predicting Navigation Success in Wikipedia. Koopmann, Tobias; Dallmann, Alexander; Hettinger, Lena; Niebler, Thomas; Hotho, Andreas. In Proceedings of the 30th ACM Conference on Hypertext and Social Media, of HT ’19, C. Atzenbeck, J. Rubart, D. E. Millard (eds.), pp. 143–152. ACM, Hof, Germany, 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Koopmann:2019:RTA:3342220.3343650, address = {New York, NY, USA}, author = {Koopmann, Tobias and Dallmann, Alexander and Hettinger, Lena and Niebler, Thomas and Hotho, Andreas}, booktitle = {Proceedings of the 30th ACM Conference on Hypertext and Social Media}, editor = {Atzenbeck, Claus and Rubart, Jessica and Millard, David E.}, keywords = {user}, pages = {143–152}, publisher = {ACM}, series = {HT '19}, title = {On the Right Track! Analysing and Predicting Navigation Success in Wikipedia}, year = 2019 }
• Compact Drawings of 1-Planar Graphs with Right-Angle Crossings and Few Bends. Chaplick, Steven; Lipp, Fabian; Wolff, Alexander; Zink, Johannes. In Computational Geometry: Theory and Applications, 84, pp. 50–68. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  We study the following classes of beyond-planar graphs: 1-planar, IC-planar, and NIC-planar graphs. These are the graphs that admit a 1-planar, IC-planar, and NIC-planar drawing, respectively. A drawing of a graph is \emph{1-planar} if every edge is crossed at most once. A 1-planar drawing is \emph{IC-planar} if no two pairs of crossing edges share a vertex. A 1-planar drawing is \emph{NIC-planar} if no two pairs of crossing edges share two vertices. We study the relations of these beyond-planar graph classes (\emph{beyond-planar graphs} is a collective term for the primary attempts to generalize the planar graphs) to \emph{right-angle crossing} (\emph{RAC}) graphs that admit compact drawings on the grid with few bends. We present four drawing algorithms that preserve the given embeddings. First, we show that every $n$-vertex NIC-planar graph admits a NIC-planar RAC drawing with at most one bend per edge on a grid of size $O(n) \times O(n)$. Then, we show that every $n$-vertex 1-planar graph admits a 1-planar RAC drawing with at most two bends per edge on a grid of size $O(n^3) \times O(n^3)$. Finally, we make two known algorithms embedding-preserving; for drawing 1-planar RAC graphs with at most one bend per edge and for drawing IC-planar RAC graphs straight-line.

  @article{clwz-cd1pg-CGTA19, abstract = {We study the following classes of beyond-planar graphs: 1-planar, IC-planar, and NIC-planar graphs. These are the graphs that admit a 1-planar, IC-planar, and NIC-planar drawing, respectively. A drawing of a graph is \emph{1-planar} if every edge is crossed at most once. A 1-planar drawing is \emph{IC-planar} if no two pairs of crossing edges share a vertex. A 1-planar drawing is \emph{NIC-planar} if no two pairs of crossing edges share two vertices. We study the relations of these beyond-planar graph classes (\emph{beyond-planar graphs} is a collective term for the primary attempts to generalize the planar graphs) to \emph{right-angle crossing} (\emph{RAC}) graphs that admit compact drawings on the grid with few bends. We present four drawing algorithms that preserve the given embeddings. First, we show that every $n$-vertex NIC-planar graph admits a NIC-planar RAC drawing with at most one bend per edge on a grid of size $O(n) \times O(n)$. Then, we show that every $n$-vertex 1-planar graph admits a 1-planar RAC drawing with at most two bends per edge on a grid of size $O(n^3) \times O(n^3)$. Finally, we make two known algorithms embedding-preserving; for drawing 1-planar RAC graphs with at most one bend per edge and for drawing IC-planar RAC graphs straight-line.}, author = {Chaplick, Steven and Lipp, Fabian and Wolff, Alexander and Zink, Johannes}, journal = {Computational Geometry: Theory and Applications}, keywords = {gd-info1}, note = {Special Issue on the 34th European Workshop on Computational Geometry}, pages = {50–68}, title = {Compact Drawings of 1-Planar Graphs with Right-Angle Crossings and Few Bends}, volume = 84, year = 2019 }
• Variants of the Segment Number of a Graph. Okamoto, Yoshio; Ravsky, Alexander; Wolff, Alexander. In Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. Tóth (eds.), pp. 430–443. Springer-Verlag, 2019.
  • [ BibTeX ]
  @inproceedings{orw-ysng-GD19, author = {Okamoto, Yoshio and Ravsky, Alexander and Wolff, Alexander}, booktitle = {Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD'19)}, editor = {Archambault, Daniel and Tóth, Csaba D.}, keywords = {myown}, pages = {430–443}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Variants of the Segment Number of a Graph}, volume = 11904, year = 2019 }
• Representing Graphs and Hypergraphs by Touching Polygons in {3D}. Evans, William; Rzążewski, Paweł; Saeedi, Noushin; Shin, Chan-Su; Wolff, Alexander. In Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. Tóth (eds.), pp. 18–32. Springer-Verlag, 2019.
  • [ BibTeX ]
  @inproceedings{erssw-rghtp-GD19, author = {Evans, William and Rzążewski, Paweł and Saeedi, Noushin and Shin, Chan-Su and Wolff, Alexander}, booktitle = {Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD'19)}, editor = {Archambault, Daniel and Tóth, Csaba D.}, keywords = {myown}, note = {http://arxiv.org/abs/1908.08273}, pages = {18–32}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Representing Graphs and Hypergraphs by Touching Polygons in {3D}}, volume = 11904, year = 2019 }
• Visualizing Orientations of Large Numbers of Photographs. Niebling, Florian. In Proceedings of the 1st Workshop on Structuring and Understanding of Multimedia heritAge Contents, of SUMAC ’19, pp. 1–2. ACM, Nice, France, 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Niebling:2019:VOL:3347317.3352729, address = {New York, NY, USA}, author = {Niebling, Florian}, booktitle = {Proceedings of the 1st Workshop on Structuring and Understanding of Multimedia heritAge Contents}, keywords = {histstadt4d}, pages = {1–2}, publisher = {ACM}, series = {SUMAC '19}, title = {Visualizing Orientations of Large Numbers of Photographs}, year = 2019 }
• VIA VR: A Technology Platform for Virtual Adventures for Healthcare and Well-Being. von Mammen, Sebastian; M{ü}ller, Andreas; Latoschik, Marc Erich; Botsch, Mario; Brukamp, Kirsten; Schr{ö}der, Carsten; Wacker, Michael. In VS-Games, pp. 1–2. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  To harness the potential of virtual reality (VR) in the healthcare sector, the expenditures for users such as clinics, doctors or health insurances, have to be reduced – a requirement the technology platform VIA VR (an acronym from “virtual reality adventures” and VR) promises to fulfill by combining several key technologies to allow specialists from the healthcare sector to create high-impact VR adventures without the need for a background in programming or the design of virtual worlds. This paper fleshes out the concept of VIA VR, its technological pillars and the planned R&D agenda.

  @inproceedings{von2019via, abstract = {To harness the potential of virtual reality (VR) in the healthcare sector, the expenditures for users such as clinics, doctors or health insurances, have to be reduced – a requirement the technology platform VIA VR (an acronym from “virtual reality adventures” and VR) promises to fulfill by combining several key technologies to allow specialists from the healthcare sector to create high-impact VR adventures without the need for a background in programming or the design of virtual worlds. This paper fleshes out the concept of VIA VR, its technological pillars and the planned R&D agenda.}, author = {von Mammen, Sebastian and M{\"u}ller, Andreas and Latoschik, Marc Erich and Botsch, Mario and Brukamp, Kirsten and Schr{\"o}der, Carsten and Wacker, Michael}, journal = {VS-Games}, keywords = {via-vr}, pages = {1-2}, title = {VIA VR: A Technology Platform for Virtual Adventures for Healthcare and Well-Being}, year = 2019 }
• Wenn eine Miniatur laufen lernt. \textbf{S. {von Mammen}}; Schmidt, Hans-G{ü}nter. In Bibliotheksforum Bayern, 13(4), pp. 250–253. 2019.
  • [ BibTeX ]
  • [ URL ]
  @article{von-Mammen:2019aa, author = {\textbf{S. {von Mammen}} and Schmidt, Hans-G{\"u}nter}, journal = {Bibliotheksforum Bayern}, keywords = {myown}, number = 4, pages = {250–253}, title = {Wenn eine Miniatur laufen lernt}, volume = 13, year = 2019 }
• Approaching Difficult Terrain with Sensitivity: A Virtual Reality Game on the Five Stages of Grief. Roth, Daniel; \textbf{S. {von Mammen}}; Keil, Julian; Schildknecht, Manuel; Latoschik, Marc Erich. In 2019 11th International Conference on Virtual Worlds and Games for Serious Applications (VS-Games), pp. 1–4. IEEE, 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Roth:2019aa, author = {Roth, Daniel and \textbf{S. {von Mammen}} and Keil, Julian and Schildknecht, Manuel and Latoschik, Marc Erich}, booktitle = {2019 11th International Conference on Virtual Worlds and Games for Serious Applications (VS-Games)}, keywords = {myown}, organization = {IEEE}, pages = {1–4}, title = {Approaching Difficult Terrain with Sensitivity: A Virtual Reality Game on the Five Stages of Grief}, year = 2019 }
• Stick Graphs with Length Constraints. Chaplick, Steven; Kindermann, Philipp; Löffler, Andre; Thiele, Florian; Wolff, Alexander; Zaft, Alexander; Zink, Johannes. In Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. Tóth (eds.), pp. 3–17. Springer-Verlag, 2019.
  • [ BibTeX ]
  @inproceedings{ckltwzz-sglc-GD19, author = {Chaplick, Steven and Kindermann, Philipp and Löffler, Andre and Thiele, Florian and Wolff, Alexander and Zaft, Alexander and Zink, Johannes}, booktitle = {Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD'19)}, editor = {Archambault, Daniel and Tóth, Csaba D.}, keywords = {gd-info1}, pages = {3–17}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Stick Graphs with Length Constraints}, volume = 11904, year = 2019 }
• ViTraS - Virtual Reality Therapy by Stimulation of Modulated Body Image - Project Outline. Döllinger, Nina; Wienrich, Carolin; Wolf, Erik; Botsch, Mario; Latoschik, Marc Erich. In 2019 Mensch und Computer - Workshopband, pp. 606–611. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In the recent decades, obesity has become one of the major public health issues and is associated with severe other diseases. Although current multidisciplinary therapy approaches already include behavioral therapy techniques, the oftentimes remaining lack of psychotherapeutic support after surgery leads to relapses and renewed weight gain. This paper presents an overview of the project ViTraS-Virtual Reality Therapy by Stimulation of Modulated BodyImage - that addresses these challenges by (i) Developing an integrative model predicting the influential paths of immersive media for an effective behavioral change; (ii) Developing an augmented reality (AR)-mirror system enabling an effective therapy on body self-perception of patients, and (iii)Developing a multi-user virtual reality (VR)-system supply-ing social support from therapists and other patients. The three components of the ViTraS projects are briefly introduced, as well as a first VR-based prototype of the mirror system.

  @inproceedings{dollinger2019toappearvitras, abstract = {In the recent decades, obesity has become one of the major public health issues and is associated with severe other diseases. Although current multidisciplinary therapy approaches already include behavioral therapy techniques, the oftentimes remaining lack of psychotherapeutic support after surgery leads to relapses and renewed weight gain. This paper presents an overview of the project ViTraS-Virtual Reality Therapy by Stimulation of Modulated BodyImage - that addresses these challenges by (i) Developing an integrative model predicting the influential paths of immersive media for an effective behavioral change; (ii) Developing an augmented reality (AR)-mirror system enabling an effective therapy on body self-perception of patients, and (iii)Developing a multi-user virtual reality (VR)-system supply-ing social support from therapists and other patients. The three components of the ViTraS projects are briefly introduced, as well as a first VR-based prototype of the mirror system.}, author = {Döllinger, Nina and Wienrich, Carolin and Wolf, Erik and Botsch, Mario and Latoschik, Marc Erich}, booktitle = {2019 Mensch und Computer - Workshopband}, keywords = {vitras}, pages = {606-611}, title = {ViTraS - Virtual Reality Therapy by Stimulation of Modulated Body Image - Project Outline}, year = 2019 }
• Alexa, How Can I Reason with Prolog?. Nogatz, Falco; Kübert, Julia; Seipel, Dietmar; Abreu, Salvador. In Proceedings of 8th Symposium on Languages, Applications, Technologies (SLATE), Vol. 74 of OpenAccess Series in Informatics (OASIcs), pp. 17:1–17:9. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  As with Amazon’s Echo and its conversational agent Alexa, smart voice-controlled devices become ever more present in daily life, and many different applications can be integrated into this platform. In this paper, we present a framework that eases the development of skills in Prolog. As Prolog has a long history in natural language processing, we may integrate well-established techniques, such as reasoning about knowledge with Attempto Controlled English, instead of depending on example phrases and pre-defined slots.

  @inproceedings{nogatz2019alexa, abstract = {As with Amazon’s Echo and its conversational agent Alexa, smart voice-controlled devices become ever more present in daily life, and many different applications can be integrated into this platform. In this paper, we present a framework that eases the development of skills in Prolog. As Prolog has a long history in natural language processing, we may integrate well-established techniques, such as reasoning about knowledge with Attempto Controlled English, instead of depending on example phrases and pre-defined slots.}, author = {Nogatz, Falco and Kübert, Julia and Seipel, Dietmar and Abreu, Salvador}, booktitle = {Proceedings of 8th Symposium on Languages, Applications, Technologies (SLATE)}, keywords = {myown}, pages = {17:1-17:9}, series = {OpenAccess Series in Informatics (OASIcs)}, title = {Alexa, How Can I Reason with Prolog?}, volume = 74, year = 2019 }
• Tight Times: Semantics and Distractibility of Pneumatic Compression Feedback for Wearable Devices. Löffler, Diana; Tscharn, Robert; Schaper, Philipp; Hollenbach, Melissa; Mocke, Viola. In Proceedings of Mensch und Computer 2019. ACM, 2019.
  • [ BibTeX ]
  @inproceedings{Löffler_2019, author = {Löffler, Diana and Tscharn, Robert and Schaper, Philipp and Hollenbach, Melissa and Mocke, Viola}, booktitle = {Proceedings of Mensch und Computer 2019}, keywords = {myown}, publisher = {ACM}, title = {Tight Times: Semantics and Distractibility of Pneumatic Compression Feedback for Wearable Devices}, year = 2019 }
• Finding Tutte Paths in Linear Time. Biedl, Therese; Kindermann, Philipp. In Proceedings of the 46th International Colloquium on Automata, Languages, and Programming (ICALP’19), Vol. 132 of LIPIcs, C. Baier, I. Chatzigiannakis, P. Flocchini, S. Leonardi (eds.), pp. 23:1–23:14. Schloss Dagstuhl - Leibniz-Zentrum fuer Informatik, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  It is well-known that every planar graph has a Tutte path, i.e., a path P such that any component of G-P has at most three attachment points on P. However, it was only recently shown that such Tutte paths can be found in polynomial time. In this paper, we give a new proof that 3-connected planar graphs have Tutte paths, which leads to a linear-time algorithm to find Tutte paths. Furthermore, our Tutte path has special properties: it visits all exterior vertices, all components of G-P have exactly three attachment points, and we can assign distinct representatives to them that are interior vertices. Finally, our running time bound is slightly stronger; we can bound it in terms of the degrees of the faces that are incident to P. This allows us to find some applications of Tutte paths (such as binary spanning trees and 2-walks) in linear time as well.

  @inproceedings{bk-ftplt-icalp19, abstract = {It is well-known that every planar graph has a Tutte path, i.e., a path P such that any component of G-P has at most three attachment points on P. However, it was only recently shown that such Tutte paths can be found in polynomial time. In this paper, we give a new proof that 3-connected planar graphs have Tutte paths, which leads to a linear-time algorithm to find Tutte paths. Furthermore, our Tutte path has special properties: it visits all exterior vertices, all components of G-P have exactly three attachment points, and we can assign distinct representatives to them that are interior vertices. Finally, our running time bound is slightly stronger; we can bound it in terms of the degrees of the faces that are incident to P. This allows us to find some applications of Tutte paths (such as binary spanning trees and 2-walks) in linear time as well.}, author = {Biedl, Therese and Kindermann, Philipp}, booktitle = {Proceedings of the 46th International Colloquium on Automata, Languages, and Programming (ICALP'19)}, editor = {Baier, Christel and Chatzigiannakis, Ioannis and Flocchini, Paola and Leonardi, Stefano}, keywords = {myown}, pages = {23:1–23:14}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum fuer Informatik}, series = {LIPIcs}, title = {Finding Tutte Paths in Linear Time}, volume = 132, year = 2019 }
• Fundamental Relationships for Deriving QoE in Systems. Hoßfeld, Tobias; Heegaard, Poul E.; Skorin-Kapov, Lea; Varela, Martin. In 2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX) (QoMEX 2019). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  In the context of subjective user studies conducted to derive relationships between influence factors and QoE, user diversity leads to distributions of user scores for test conditions. Such models are commonly exploited by service/network providers to derive various QoE metrics in their system, such as expected QoE, or the percentage of users rating above a certain threshold. The question arises as to how to combine a) user rating distributions obtained from subjective studies, and b) system performance condition distributions, so as to obtain the actual observed QoE distribution in the system? Moreover, how can various QoE metrics of interest in the system be derived? We prove a fundamental relationship showing that the expected system QoE is equal to the expected Mean Opinion Score (MOS) in the system. While subjective user studies commonly report only QoS-to-MOS mapping functions, we show that to derive additional QoE metrics in the system, it is necessary to use corresponding QoS-to-QoE metric mapping functions (beyond only QoS-to-MOS) as derived from user rating distributions in subjective studies. The results of the paper provide important insights for deriving QoE metrics from a systems perspective.

  @inproceedings{info3-inproceedings-2019-23, abstract = {In the context of subjective user studies conducted to derive relationships between influence factors and QoE, user diversity leads to distributions of user scores for test conditions. Such models are commonly exploited by service/network providers to derive various QoE metrics in their system, such as expected QoE, or the percentage of users rating above a certain threshold. The question arises as to how to combine a) user rating distributions obtained from subjective studies, and b) system performance condition distributions, so as to obtain the actual observed QoE distribution in the system? Moreover, how can various QoE metrics of interest in the system be derived? We prove a fundamental relationship showing that the expected system QoE is equal to the expected Mean Opinion Score (MOS) in the system. While subjective user studies commonly report only QoS-to-MOS mapping functions, we show that to derive additional QoE metrics in the system, it is necessary to use corresponding QoS-to-QoE metric mapping functions (beyond only QoS-to-MOS) as derived from user rating distributions in subjective studies. The results of the paper provide important insights for deriving QoE metrics from a systems perspective.}, author = {Hoßfeld, Tobias and Heegaard, Poul E. and Skorin-Kapov, Lea and Varela, Martin}, booktitle = {2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX) (QoMEX 2019)}, keywords = {myown}, title = {Fundamental Relationships for Deriving QoE in Systems}, year = 2019 }
• {How is Performance Addressed in DevOps?}. Bezemer, Cor{-}Paul; Eismann, Simon; Ferme, Vincenzo; Grohmann, Johannes; Heinrich, Robert; Jamshidi, Pooyan; Shang, Weiyi; van Hoorn, Andr{{é}}; Villavicencio, M{{ó}}nica; Walter, J{{ü}}rgen; Willnecker, Felix. In Proceedings of the 2019 ACM/SPEC International Conference on Performance Engineering, of ICPE ’19, pp. 45–50. Association for Computing Machinery (ACM), New York, NY, USA, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  DevOps is a modern software engineering paradigm that is gaining widespread adoption in industry. The goal of DevOps is to bring software changes into production with a high frequency and fast feedback cycles. This conflicts with software quality assurance activities, particularly with respect to performance. For instance, performance evaluation activities --- such as load testing --- require a considerable amount of time to get statistically significant results. We conducted an industrial survey to get insights into how performance is addressed in industrial DevOps settings. In particular, we were interested in the frequency of executing performance evaluations, the tools being used, the granularity of the obtained performance data, and the use of model-based techniques. The survey responses, which come from a wide variety of participants from different industry sectors, indicate that the complexity of performance engineering approaches and tools is a barrier for wide-spread adoption of performance analysis in DevOps. The implication of our results is that performance analysis tools need to have a short learning curve, and should be easy to integrate into the DevOps pipeline in order to be adopted by practitioners.

  @inproceedings{BeEiFeGrRhJaShHoViWaWi2019-ICPE-DevOpsSurvey, abstract = {DevOps is a modern software engineering paradigm that is gaining widespread adoption in industry. The goal of DevOps is to bring software changes into production with a high frequency and fast feedback cycles. This conflicts with software quality assurance activities, particularly with respect to performance. For instance, performance evaluation activities — such as load testing — require a considerable amount of time to get statistically significant results. We conducted an industrial survey to get insights into how performance is addressed in industrial DevOps settings. In particular, we were interested in the frequency of executing performance evaluations, the tools being used, the granularity of the obtained performance data, and the use of model-based techniques. The survey responses, which come from a wide variety of participants from different industry sectors, indicate that the complexity of performance engineering approaches and tools is a barrier for wide-spread adoption of performance analysis in DevOps. The implication of our results is that performance analysis tools need to have a short learning curve, and should be easy to integrate into the DevOps pipeline in order to be adopted by practitioners.}, address = {New York, NY, USA}, author = {Bezemer, Cor{-}Paul and Eismann, Simon and Ferme, Vincenzo and Grohmann, Johannes and Heinrich, Robert and Jamshidi, Pooyan and Shang, Weiyi and van Hoorn, Andr{{\'e}} and Villavicencio, M{{\'o}}nica and Walter, J{{\"u}}rgen and Willnecker, Felix}, booktitle = {Proceedings of the 2019 ACM/SPEC International Conference on Performance Engineering}, keywords = {SPEC}, pages = {45–50}, publisher = {Association for Computing Machinery (ACM)}, series = {ICPE '19}, title = {{How is Performance Addressed in DevOps?}}, year = 2019 }
• Survey on Graph and Hypergraph Drawing. Schulz, André; Wolff, Alexander. M. Löffler; A. Lubiw; S. Schleimer; E. M. W. Chambers (eds.), pp. 87–89. Schloss Dagstuhl – Leibniz-Zentrum für Informatik, 2019.
  • [ BibTeX ]
  @misc{sw-sghd-DR19, author = {Schulz, André and Wolff, Alexander}, booktitle = {Computation in Low-Dimensional Geometry and Topology (Dagstuhl Seminar 19352)}, editor = {Löffler, Maarten and Lubiw, Anna and Schleimer, Saul and Chambers, Erin Moriarty Wolf}, keywords = {Geometric_topology}, pages = {87–89}, publisher = {Schloss Dagstuhl – Leibniz-Zentrum für Informatik}, series = {Dagstuhl Reports}, title = {Survey on Graph and Hypergraph Drawing}, volume = {9 (number 8)}, year = 2019 }
• Simulated Reference Frame Effects on Steering, Jumping and Sliding. Lugrin, Jean-Luc; Landeck, Maximilian; Latoschik, Marc Erich. In Proceedings of the 26th IEEE Virtual Reality (VR) conference, pp. 1062–1063. 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{lugrin2019simulated, author = {Lugrin, Jean-Luc and Landeck, Maximilian and Latoschik, Marc Erich}, booktitle = {Proceedings of the 26th IEEE Virtual Reality (VR) conference}, keywords = {myown}, pages = {1062-1063}, title = {Simulated Reference Frame Effects on Steering, Jumping and Sliding}, year = 2019 }
• Monitoring Vital Signs with Time-Compressed Speech. Sanderson, Penelope M.; Brecknell, Birgit; Leong, SokYee; Klueber, Sara; Wolf, Erik; Hickling, Anna; Tang, Tsz-Lok; Bell, Emilea; Li, Simon Y. W.; Loeb, Robert G. In Journal of Experimental Psychology: Applied, 25(4), pp. 647–673. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Spearcons—time-compressed speech phrases—may be an effective way of communicating vital signs to clinicians without disturbing patients and their families. Four experiments tested the effectiveness of spearcons for conveying oxygen saturation (SpO2) and heart rate (HR) of one or more patients. Experiment 1 demonstrated that spearcons were more effective than earcons (abstract auditory motifs) at conveying clinical ranges. Experiment 2 demonstrated that casual listeners could not learn to decipher the spearcons whereas listeners told the exact vocabulary could. Experiment 3 demonstrated that participants could interpret sequences of sounds representing multiple patients better with spearcons than with pitch-based earcons, especially when tones replaced the spearcons for normal patients. Experiment 4 compared multiple-patient monitoring of two vital signs with either spearcons, a visual display showing SpO2 and HR in the same temporal sequence as the spearcons, or a visual display showing multiple patient levels simultaneously. All displays conveyed which patients were abnormal with high accuracy. Visual displays better conveyed the vital sign levels for each patient, but cannot be used eyes-free. All displays showed accuracy decrements with working memory load. Spearcons may be viable for single and multiple patient monitoring. Further research should test spearcons with more vital signs, during multitasking, and longitudinally.

  @article{sanderson2019monitoring, abstract = {Spearcons—time-compressed speech phrases—may be an effective way of communicating vital signs to clinicians without disturbing patients and their families. Four experiments tested the effectiveness of spearcons for conveying oxygen saturation (SpO2) and heart rate (HR) of one or more patients. Experiment 1 demonstrated that spearcons were more effective than earcons (abstract auditory motifs) at conveying clinical ranges. Experiment 2 demonstrated that casual listeners could not learn to decipher the spearcons whereas listeners told the exact vocabulary could. Experiment 3 demonstrated that participants could interpret sequences of sounds representing multiple patients better with spearcons than with pitch-based earcons, especially when tones replaced the spearcons for normal patients. Experiment 4 compared multiple-patient monitoring of two vital signs with either spearcons, a visual display showing SpO2 and HR in the same temporal sequence as the spearcons, or a visual display showing multiple patient levels simultaneously. All displays conveyed which patients were abnormal with high accuracy. Visual displays better conveyed the vital sign levels for each patient, but cannot be used eyes-free. All displays showed accuracy decrements with working memory load. Spearcons may be viable for single and multiple patient monitoring. Further research should test spearcons with more vital signs, during multitasking, and longitudinally.}, author = {Sanderson, Penelope M. and Brecknell, Birgit and Leong, SokYee and Klueber, Sara and Wolf, Erik and Hickling, Anna and Tang, Tsz-Lok and Bell, Emilea and Li, Simon Y. W. and Loeb, Robert G.}, journal = {Journal of Experimental Psychology: Applied}, keywords = {myown}, number = 4, pages = {647–673}, title = {Monitoring Vital Signs with Time-Compressed Speech}, volume = 25, year = 2019 }
• Brain Activity in Virtual Reality: Assessing Signal Quality of High-Resolution EEG While Using Head-Mounted Displays. Hertweck, Stephan; Weber, Desirée; Alwanni, Hisham; Unruh, Fabian; Fischbach, Martin; Latoschik, Marc Erich; Ball, Tonio. In Proceedings of the 26th IEEE Conference on Virtual Reality and 3D User Interfaces (VR), pp. 970–971. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Biometric measures such as the electroencephalogram (EEG) promise to become viable alternatives to subjective questionnaire ratings for the evaluation of psychophysical effects associated with Virtual Reality (VR) systems, as they provide objective and continuous measurements without breaking the exposure. The extent to which the EEG signal can be disturbed by the presence of VR sys- tems, however, has been barely investigated. This study outlines how to evaluate the compatibility of a given EEG-VR setup on the example of two commercial head-mounted displays (HMDs), the Oculus Rift and the HTC Vive Pro. We use a novel experimental protocol to compare the spectral composition between conditions with and without an HMD present during an eyes-open vs. eyes-closed task. We found general artifacts at the line hum of 50 Hz, and additional HMD refresh rate artifacts (90 Hz) for the Oculus rift exclusively. Frequency components typically most interesting to non-invasive EEG research and applications (<50 Hz), however, remained largely unaffected. We observed similar topographies of visually-induced modulation of alpha band power for both HMD conditions in all subjects. Hence, the study introduces a necessary validation test for HMDs in combination with EEG and further promotes EEG as a potential biometric measurement method for psychophysical effects in VR systems.

  @inproceedings{hertweck2019brain, abstract = {Biometric measures such as the electroencephalogram (EEG) promise to become viable alternatives to subjective questionnaire ratings for the evaluation of psychophysical effects associated with Virtual Reality (VR) systems, as they provide objective and continuous measurements without breaking the exposure. The extent to which the EEG signal can be disturbed by the presence of VR sys- tems, however, has been barely investigated. This study outlines how to evaluate the compatibility of a given EEG-VR setup on the example of two commercial head-mounted displays (HMDs), the Oculus Rift and the HTC Vive Pro. We use a novel experimental protocol to compare the spectral composition between conditions with and without an HMD present during an eyes-open vs. eyes-closed task. We found general artifacts at the line hum of 50 Hz, and additional HMD refresh rate artifacts (90 Hz) for the Oculus rift exclusively. Frequency components typically most interesting to non-invasive EEG research and applications (<50 Hz), however, remained largely unaffected. We observed similar topographies of visually-induced modulation of alpha band power for both HMD conditions in all subjects. Hence, the study introduces a necessary validation test for HMDs in combination with EEG and further promotes EEG as a potential biometric measurement method for psychophysical effects in VR systems.}, author = {Hertweck, Stephan and Weber, Desirée and Alwanni, Hisham and Unruh, Fabian and Fischbach, Martin and Latoschik, Marc Erich and Ball, Tonio}, booktitle = {Proceedings of the 26th IEEE Conference on Virtual Reality and 3D User Interfaces (VR)}, keywords = {interactive-opera}, pages = {970-971}, publisher = {IEEE}, title = {Brain Activity in Virtual Reality: Assessing Signal Quality of High-Resolution EEG While Using Head-Mounted Displays}, year = 2019 }
• Smart substitutional reality: Integrating the smart home into virtual reality. Eckstein, Benjamin; Krapp, Eva; Elsässer, Anne; Lugrin, Birgit. In Entertainment Computing, 31, p. 100306. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Recent advances in VR technology allow users to consume immersive content within their own living room. Substitutional Reality (SR) promises to enhance this experience by integrating the physical environment into the simulation. We propose a novel approach, called Smart Substitutional Reality (SSR), that extends the passive haptics of SR with the interactive functionality of a smart home environment. SSR is meant to serve as a foundation for serious games. In this paper, we describe the concept of SSR alongside the implementation of a prototype in our smart lab. We designed multiple virtual environments with a varying degree of mismatch compared to the real world, and added selected objects to induce additional haptic and thermal stimuli to increase immersion. In two user studies we investigate their impact on spatial presence and intrinsic motivation which are especially important for serious games. Results suggest that spatial presence is maintained with higher mismatch, and increased by inducing additional stimuli. Intrinsic motivation is increased in both cases.

  @article{ECKSTEIN2019100306, abstract = {Recent advances in VR technology allow users to consume immersive content within their own living room. Substitutional Reality (SR) promises to enhance this experience by integrating the physical environment into the simulation. We propose a novel approach, called Smart Substitutional Reality (SSR), that extends the passive haptics of SR with the interactive functionality of a smart home environment. SSR is meant to serve as a foundation for serious games. In this paper, we describe the concept of SSR alongside the implementation of a prototype in our smart lab. We designed multiple virtual environments with a varying degree of mismatch compared to the real world, and added selected objects to induce additional haptic and thermal stimuli to increase immersion. In two user studies we investigate their impact on spatial presence and intrinsic motivation which are especially important for serious games. Results suggest that spatial presence is maintained with higher mismatch, and increased by inducing additional stimuli. Intrinsic motivation is increased in both cases.}, author = {Eckstein, Benjamin and Krapp, Eva and Elsässer, Anne and Lugrin, Birgit}, journal = {Entertainment Computing}, keywords = {reflectedreality}, pages = 100306, title = {Smart substitutional reality: Integrating the smart home into virtual reality}, volume = 31, year = 2019 }
• Comparing Human Factors for Augmented Reality supported Single and Cooperative Repair Operations of Industrial Robots. Aschenbrenner, Doris; Leutert, Florian; Cencen, Argun; Verlinden, Jouke; Schilling, Klaus; Latoschik, Marc Erich; Lukosch, Stephan. In Frontiers in Robotics and AI, 6, p. 37. Frontiers, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  In order to support the decision-making process of industry on how to implement Augmented Reality (AR) in production, this article wants to provide guidance through a set of comparative user studies. The results are obtained from the feedback of 160 participants who performed the same repair task on a switch cabinet of an industrial robot. The studies compare several AR instruction applications on different display devices (head-mounted display, handheld tablet PC and projection-based spatial AR) with baseline conditions (paper instructions and phone support), both in a single-user and a collaborative setting. Next to insights on the performance of the individual device types for the single mode operation, the study is able to show significant indications on AR techniques are being especially helpful in a collaborative setting.

  @article{aschenbrenner2019comparing, abstract = {In order to support the decision-making process of industry on how to implement Augmented Reality (AR) in production, this article wants to provide guidance through a set of comparative user studies. The results are obtained from the feedback of 160 participants who performed the same repair task on a switch cabinet of an industrial robot. The studies compare several AR instruction applications on different display devices (head-mounted display, handheld tablet PC and projection-based spatial AR) with baseline conditions (paper instructions and phone support), both in a single-user and a collaborative setting. Next to insights on the performance of the individual device types for the single mode operation, the study is able to show significant indications on AR techniques are being especially helpful in a collaborative setting.}, author = {Aschenbrenner, Doris and Leutert, Florian and Cencen, Argun and Verlinden, Jouke and Schilling, Klaus and Latoschik, Marc Erich and Lukosch, Stephan}, journal = {Frontiers in Robotics and AI}, keywords = {marc}, pages = 37, publisher = {Frontiers}, title = {Comparing Human Factors for Augmented Reality supported Single and Cooperative Repair Operations of Industrial Robots}, volume = 6, year = 2019 }
• Experiencing Waiting Time in Virtual Reality. Lugrin, Jean-Luc; Unruh, Fabian; Landeck, Maximilian; Lamour, Yoan; Latoschik, Marc Erich; Vogeley, Kai; Wittmann, Marc. In Proceedings of the 25th ACM Conference on Virtual Reality Software and Technology. 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{lugrin2019experiencing, author = {Lugrin, Jean-Luc and Unruh, Fabian and Landeck, Maximilian and Lamour, Yoan and Latoschik, Marc Erich and Vogeley, Kai and Wittmann, Marc}, booktitle = {Proceedings of the 25th ACM Conference on Virtual Reality Software and Technology}, keywords = {vrst19}, title = {Experiencing Waiting Time in Virtual Reality}, year = 2019 }
• Definite Clause Grammars with Parse Trees: Extension for Prolog. Nogatz, Falco; Seipel, Dietmar; Abreu, Salvador. In Proceedings of 8th Symposium on Languages, Applications, Technologies (SLATE), Vol. 74 of OpenAccess Series in Informatics (OASIcs), pp. 7:1–7:14. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Definite Clause Grammars (DCGs) are a convenient way to specify possibly non-context-free grammars for natural and formal languages. They can be used to progressively build a parse tree as grammar rules are applied by providing an extra argument in the DCG rule’s head. In the simplest way, this is a structure that contains the name of the used nonterminal. This extension of a DCG has been proposed for natural language processing in the past and can be done automatically in Prolog using term expansion. We extend this approach by a meta-nonterminal to specify optional and sequences of nonterminals, as these structures are common in grammars for formal, domain-specific languages. We specify a term expansion that represents these sequences as lists while preserving the grammar’s ability to be used both for parsing and serialising, i.e. to create a parse tree by a given source code and vice-versa. We show that this mechanism can be used to lift grammars specified in extended Backus–Naur form (EBNF) to generate parse trees. As a case study, we present a parser for the Prolog programming language itself based only on the grammars given in the ISO Prolog standard which produces corresponding parse trees.

  @inproceedings{nogatz2019dcg4pt, abstract = {Definite Clause Grammars (DCGs) are a convenient way to specify possibly non-context-free grammars for natural and formal languages. They can be used to progressively build a parse tree as grammar rules are applied by providing an extra argument in the DCG rule’s head. In the simplest way, this is a structure that contains the name of the used nonterminal. This extension of a DCG has been proposed for natural language processing in the past and can be done automatically in Prolog using term expansion. We extend this approach by a meta-nonterminal to specify optional and sequences of nonterminals, as these structures are common in grammars for formal, domain-specific languages. We specify a term expansion that represents these sequences as lists while preserving the grammar’s ability to be used both for parsing and serialising, i.e. to create a parse tree by a given source code and vice-versa. We show that this mechanism can be used to lift grammars specified in extended Backus–Naur form (EBNF) to generate parse trees. As a case study, we present a parser for the Prolog programming language itself based only on the grammars given in the ISO Prolog standard which produces corresponding parse trees.}, author = {Nogatz, Falco and Seipel, Dietmar and Abreu, Salvador}, booktitle = {Proceedings of 8th Symposium on Languages, Applications, Technologies (SLATE)}, keywords = {myown}, pages = {7:1-7:14}, series = {OpenAccess Series in Informatics (OASIcs)}, title = {Definite Clause Grammars with Parse Trees: Extension for Prolog}, volume = 74, year = 2019 }
• Distinct functional roles of the mirror neuron system and the mentalizing system. Geiger, Alexander; Bente, Gary; Lammers, Sebastian; Tepest, Ralf; Roth, Daniel; Bzdok, Danilo; Vogeley, Kai. In NeuroImage, 202, p. 116102. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Movements can inform us about what people are doing and also about how they feel. This phenomenologically evident distinction has been suggested to correspond functionally with differential neural correlates denoted as mirror neuron system (MNS) and mentalizing system (MENT). To separate out the roles of the underlying systems we presented identical stimuli under different task demands: character animations showing everyday activities (mopping, sweeping) performed in different moods (angry, happy). Thirty-two participants were undergoing functional magnetic resonance imaging (fMRI) while asked to identify either the performed movement or the displayed mood. Univariate GLM analysis revealed the expected activation of either in MNS or MENT depending on the task. A complementary multivariate pattern-learning analysis based on the “social brain atlas” confirmed the expected recruitment of both systems. In conclusion, both approaches converge onto clearly distinct functional roles of both social neural networks in a novel dynamic social perception paradigm.

  @article{geiger2019distinct, abstract = {Movements can inform us about what people are doing and also about how they feel. This phenomenologically evident distinction has been suggested to correspond functionally with differential neural correlates denoted as mirror neuron system (MNS) and mentalizing system (MENT). To separate out the roles of the underlying systems we presented identical stimuli under different task demands: character animations showing everyday activities (mopping, sweeping) performed in different moods (angry, happy). Thirty-two participants were undergoing functional magnetic resonance imaging (fMRI) while asked to identify either the performed movement or the displayed mood. Univariate GLM analysis revealed the expected activation of either in MNS or MENT depending on the task. A complementary multivariate pattern-learning analysis based on the “social brain atlas” confirmed the expected recruitment of both systems. In conclusion, both approaches converge onto clearly distinct functional roles of both social neural networks in a novel dynamic social perception paradigm.}, author = {Geiger, Alexander and Bente, Gary and Lammers, Sebastian and Tepest, Ralf and Roth, Daniel and Bzdok, Danilo and Vogeley, Kai}, journal = {NeuroImage}, keywords = {insync}, pages = 116102, title = {Distinct functional roles of the mirror neuron system and the mentalizing system}, volume = 202, year = 2019 }
• The Impact of Stereo Rendering on the Perception of Normal Mapped Geometry in Virtual Reality. Mišiak, Martin; Wissmann, Niko; Fuhrmann, Arnulph; Latoschik, Marc Erich. In Proceedings of the 25th ACM Symposium on Virtual Reality Software and Technology, of VRST ’19, pp. 92:1–92:2. Association for Computing Machinery, Parramatta, NSW, Australia, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This paper investigates the effects of normal mapping on the perception of geometric depth between stereoscopic and non-stereoscopic views. Results show, that in a head-tracked environment, the addition of binocular disparity has no impact on the error rate in the detection of normal-mapped geometry. It does however significantly shorten the detection time.

  @inproceedings{misiak2019impact, abstract = {This paper investigates the effects of normal mapping on the perception of geometric depth between stereoscopic and non-stereoscopic views. Results show, that in a head-tracked environment, the addition of binocular disparity has no impact on the error rate in the detection of normal-mapped geometry. It does however significantly shorten the detection time.}, address = {New York, NY, USA}, author = {Mišiak, Martin and Wissmann, Niko and Fuhrmann, Arnulph and Latoschik, Marc Erich}, booktitle = {Proceedings of the 25th ACM Symposium on Virtual Reality Software and Technology}, keywords = {myown}, pages = {92:1-92:2}, publisher = {Association for Computing Machinery}, series = {VRST '19}, title = {The Impact of Stereo Rendering on the Perception of Normal Mapped Geometry in Virtual Reality}, year = 2019 }
• Ambiguous Bodies: The Role of Displayed Arousal in Emotion [Mis]Perception. Reynolds, Reed M.; Novotny, Eric; Lee, Joomi; Roth, Daniel; Bente, Gary. In Journal of Nonverbal Behavior. 2019.
  • [ BibTeX ]
  • [ URL ]
  @article{reynolds2019toappearambiguous, author = {Reynolds, Reed M. and Novotny, Eric and Lee, Joomi and Roth, Daniel and Bente, Gary}, journal = {Journal of Nonverbal Behavior}, keywords = {droth}, title = {Ambiguous Bodies: The Role of Displayed Arousal in Emotion [Mis]Perception}, year = 2019 }
• Knowledge Encoding in Game Mechanics: Transfer-Oriented Knowledge Learning in Desktop-3D and VR. Oberdörfer, Sebastian; Latoschik, Marc Erich. In International Journal of Computer Games Technology, 2019. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Affine Transformations (ATs) are a complex and abstract learning content. Encoding the AT knowledge in GameMechanics (GMs) achieves a repetitive knowledge application and audiovisual demonstration. Playing a serious game providing these GMs leads to motivating and effective knowledge learning. Using immersive Virtual Reality (VR) has the potential to even further increase the serious game’s learning outcome and learning quality.This paper compares the effectiveness and efficiency of desktop-3D and VR in respect to the achieved learning outcome. Also, the present study analyzes the effectiveness of an enhanced audiovisual knowledge encoding and the provision of a debriefing system. The results validate the effectiveness of the knowledge encoding in GMs to achieve knowledge learning. The study also indicates that VR is beneficial for the overall learning quality and that an enhanced audiovisual encoding has only a limited effect on the learning outcome.

  @article{oberdorfer2019knowledge, abstract = {Affine Transformations (ATs) are a complex and abstract learning content. Encoding the AT knowledge in GameMechanics (GMs) achieves a repetitive knowledge application and audiovisual demonstration. Playing a serious game providing these GMs leads to motivating and effective knowledge learning. Using immersive Virtual Reality (VR) has the potential to even further increase the serious game’s learning outcome and learning quality.This paper compares the effectiveness and efficiency of desktop-3D and VR in respect to the achieved learning outcome. Also, the present study analyzes the effectiveness of an enhanced audiovisual knowledge encoding and the provision of a debriefing system. The results validate the effectiveness of the knowledge encoding in GMs to achieve knowledge learning. The study also indicates that VR is beneficial for the overall learning quality and that an enhanced audiovisual encoding has only a limited effect on the learning outcome.}, author = {Oberdörfer, Sebastian and Latoschik, Marc Erich}, journal = {International Journal of Computer Games Technology}, keywords = {getit}, title = {Knowledge Encoding in Game Mechanics: Transfer-Oriented Knowledge Learning in Desktop-3D and VR}, volume = 2019, year = 2019 }
• VReanimate II: training first aid and reanimation in virtual reality. Bucher, Kristina; Blome, Tim; Rudolph, Stefan; \textbf{S. {von Mammen}}. In Journal of Computers in Education, 6(1), pp. 53–78. Springer, 2019.
  • [ BibTeX ]
  • [ URL ]
  @article{Bucher:2019aa, author = {Bucher, Kristina and Blome, Tim and Rudolph, Stefan and \textbf{S. {von Mammen}}}, journal = {Journal of Computers in Education}, keywords = {myown}, number = 1, pages = {53–78}, publisher = {Springer}, title = {VReanimate II: training first aid and reanimation in virtual reality}, volume = 6, year = 2019 }
• Peeking under the Hood – How the Measurement Setup Influences the Video Streaming Behavior. Schwind, Anika; Janiak, Lea; Moldovan, Christian; Wamser, Florian; Hoßfeld, Tobias. In The 3rd International Workshop on Quality of Experience Management (QoE-Management 2019). Paris, France, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Global Internet video traffic will dramatically increase in the next years. With this rapid growth, interest in the application behavior of video streaming services and the resulting user experience rises. In particular, there is a need to understand the influence of system parameters on the streaming performance. Thus, several monitoring approaches have been developed which allow conducting automated measurements on a large-scale, for example, lightweight approaches for measurements running in the mobile networks or setups using a virtual frame buffer for servers without a display running in virtualized cloud environments. In some cases, the measurement hardware can totally be controlled, in other cases, there is no knowledge about parallel running services. In this paper, we answer the question whether and how much the measurement setup (e.g., virtualization, headless browsers, load on machines) influences the video streaming behavior. Therefore, we compare eight management setups with the ground truth (an end user watching a video on the own device) by evaluating the key performance indicators on application layer during video streaming, i.e. initial video playout delays and stalling. Our results reveal important insights: some of the common measurement setups heavily influence the measurements and must be avoided to collect reliable results.

  @inproceedings{info3-inproceedings-2019-6, abstract = {Global Internet video traffic will dramatically increase in the next years. With this rapid growth, interest in the application behavior of video streaming services and the resulting user experience rises. In particular, there is a need to understand the influence of system parameters on the streaming performance. Thus, several monitoring approaches have been developed which allow conducting automated measurements on a large-scale, for example, lightweight approaches for measurements running in the mobile networks or setups using a virtual frame buffer for servers without a display running in virtualized cloud environments. In some cases, the measurement hardware can totally be controlled, in other cases, there is no knowledge about parallel running services. In this paper, we answer the question whether and how much the measurement setup (e.g., virtualization, headless browsers, load on machines) influences the video streaming behavior. Therefore, we compare eight management setups with the ground truth (an end user watching a video on the own device) by evaluating the key performance indicators on application layer during video streaming, i.e. initial video playout delays and stalling. Our results reveal important insights: some of the common measurement setups heavily influence the measurements and must be avoided to collect reliable results.}, address = {Paris, France}, author = {Schwind, Anika and Janiak, Lea and Moldovan, Christian and Wamser, Florian and Hoßfeld, Tobias}, booktitle = {The 3rd International Workshop on Quality of Experience Management (QoE-Management 2019)}, keywords = {ua-net}, month = {02}, title = {Peeking under the Hood – How the Measurement Setup Influences the Video Streaming Behavior}, year = 2019 }
• Prolog Coding Guidelines: Status and Tool Support. Nogatz, Falco; Körner, Philipp; Krings, Sebastian. In Technical Communications of the 35th International Conference on Logic Programming (ICLP). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  The importance of coding guidelines is generally accepted throughout developers of every programming language. Naturally, Prolog makes no exception. However, establishing coding guidelines is fraught with obstacles: Finding common ground on kind and selection of rules is matter of debate; once found, adhering to or enforcing rules is complicated as well, not least because of Prolog’s flexible syntax without keywords. In this paper, we evaluate the status of coding guidelines in the Prolog community and discuss to what extent they can be automatically verified. We implemented a linter for Prolog and applied it to several packages to get a hold on the current state of the community.

  @inproceedings{nogatz2019prolog, abstract = {The importance of coding guidelines is generally accepted throughout developers of every programming language. Naturally, Prolog makes no exception. However, establishing coding guidelines is fraught with obstacles: Finding common ground on kind and selection of rules is matter of debate; once found, adhering to or enforcing rules is complicated as well, not least because of Prolog’s flexible syntax without keywords. In this paper, we evaluate the status of coding guidelines in the Prolog community and discuss to what extent they can be automatically verified. We implemented a linter for Prolog and applied it to several packages to get a hold on the current state of the community.}, author = {Nogatz, Falco and Körner, Philipp and Krings, Sebastian}, booktitle = {Technical Communications of the 35th International Conference on Logic Programming (ICLP)}, keywords = {myown}, note = {(to appear)}, title = {Prolog Coding Guidelines: Status and Tool Support}, year = 2019 }
• Detection of Scenes in Fiction. Gius, Evelyn; Jannidis, Fotis; Krug, Markus; Zehe, Albin; Hotho, Andreas; Puppe, Frank; Krebs, Jonathan; Reiter, Nils; Wiedmer, Nathalie; Konle, Leonard. In Proceedings of Digital Humanities 2019. 2019.
  • [ BibTeX ]
  @inproceedings{gius2019detection, author = {Gius, Evelyn and Jannidis, Fotis and Krug, Markus and Zehe, Albin and Hotho, Andreas and Puppe, Frank and Krebs, Jonathan and Reiter, Nils and Wiedmer, Nathalie and Konle, Leonard}, booktitle = {Proceedings of Digital Humanities 2019}, keywords = {dh2019}, title = {Detection of Scenes in Fiction}, year = 2019 }
• Online model learning for self-aware computing infrastructures. Spinner, Simon; Grohmann, Johannes; Eismann, Simon; Kounev, Samuel. In Journal of Systems and Software, 147, pp. 1–16. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Performance models are valuable and powerful tools for performance prediction. However, the creation of performance models usually requires significant manual effort. Furthermore, as the modeled structures are subject to frequent change in modern infrastructures, such performance models need to be adapted as well. We therefore propose a reference architecture for online model learning in virtualized environments, which enables the automatic extraction of the aforementioned performance models. We follow an agent-based approach, which enables us to incorporate the extraction of information about the application structure as well as the virtualization structures present in modern computing centers. Our evaluation shows that our collaborating agents are able to reduce the manual effort of performance model extraction by 85.4%. The resulting performance model is able to predict the system utilization with an absolute error of less than 4% and the end-to-end response time with a relative error of less than 21%.

  @article{SpGrEiKo2019-JSS-ModelLearning, abstract = {Performance models are valuable and powerful tools for performance prediction. However, the creation of performance models usually requires significant manual effort. Furthermore, as the modeled structures are subject to frequent change in modern infrastructures, such performance models need to be adapted as well. We therefore propose a reference architecture for online model learning in virtualized environments, which enables the automatic extraction of the aforementioned performance models. We follow an agent-based approach, which enables us to incorporate the extraction of information about the application structure as well as the virtualization structures present in modern computing centers. Our evaluation shows that our collaborating agents are able to reduce the manual effort of performance model extraction by 85.4%. The resulting performance model is able to predict the system utilization with an absolute error of less than 4% and the end-to-end response time with a relative error of less than 21%.}, author = {Spinner, Simon and Grohmann, Johannes and Eismann, Simon and Kounev, Samuel}, journal = {Journal of Systems and Software}, keywords = {Virtualization}, pages = {1–16}, title = {Online model learning for self-aware computing infrastructures}, volume = 147, year = 2019 }
• Solving Mathematical Exercises: Prediction of Students’ Success. Wankerl, Sebastian; Götz, Gerhard; Hotho, Andreas. In LWDA, Vol. 2454 of CEUR Workshop Proceedings, R. Jäschke, M. Weidlich (eds.), pp. 190–194. CEUR-WS.org, 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{wankerl2019solving, author = {Wankerl, Sebastian and Götz, Gerhard and Hotho, Andreas}, booktitle = {LWDA}, editor = {Jäschke, Robert and Weidlich, Matthias}, keywords = 2019, pages = {190-194}, publisher = {CEUR-WS.org}, series = {CEUR Workshop Proceedings}, title = {Solving Mathematical Exercises: Prediction of Students’ Success}, volume = 2454, year = 2019 }
• Compact drawings of 1-planar graphs with right-angle crossings and few bends. Chaplick, Steven; Lipp, Fabian; Wolff, Alexander; Zink, Johannes. In Comput. Geom., 84, pp. 50–68. 2019.
  • [ BibTeX ]
  • [ URL ]
  @article{journals/comgeo/ChaplickLWZ19, author = {Chaplick, Steven and Lipp, Fabian and Wolff, Alexander and Zink, Johannes}, journal = {Comput. Geom.}, keywords = {myown}, pages = {50-68}, title = {Compact drawings of 1-planar graphs with right-angle crossings and few bends.}, volume = 84, year = 2019 }
• Flow-based network traffic generation using Generative Adversarial Networks. Ring, Markus; Schlör, Daniel; Landes, Dieter; Hotho, Andreas. In Computers & Security, 82, pp. 156–172. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Flow-based data sets are necessary for evaluating network-based intrusion detection systems (NIDS). In this work, we propose a novel methodology for generating realistic flow-based network traffic. Our approach is based on Generative Adversarial Networks (GANs) which achieve good results for image generation. A major challenge lies in the fact that GANs can only process continuous attributes. However, flow-based data inevitably contain categorical attributes such as IP addresses or port numbers. Therefore, we propose three different preprocessing approaches for flow-based data in order to transform them into continuous values. Further, we present a new method for evaluating the generated flow-based network traffic which uses domain knowledge to define quality tests. We use the three approaches for generating flow-based network traffic based on the CIDDS-001 data set. Experiments indicate that two of the three approaches are able to generate high quality data.

  @article{RING2019156, abstract = {Flow-based data sets are necessary for evaluating network-based intrusion detection systems (NIDS). In this work, we propose a novel methodology for generating realistic flow-based network traffic. Our approach is based on Generative Adversarial Networks (GANs) which achieve good results for image generation. A major challenge lies in the fact that GANs can only process continuous attributes. However, flow-based data inevitably contain categorical attributes such as IP addresses or port numbers. Therefore, we propose three different preprocessing approaches for flow-based data in order to transform them into continuous values. Further, we present a new method for evaluating the generated flow-based network traffic which uses domain knowledge to define quality tests. We use the three approaches for generating flow-based network traffic based on the CIDDS-001 data set. Experiments indicate that two of the three approaches are able to generate high quality data.}, author = {Ring, Markus and Schlör, Daniel and Landes, Dieter and Hotho, Andreas}, journal = {Computers & Security}, keywords = {generation}, pages = {156 - 172}, title = {Flow-based network traffic generation using Generative Adversarial Networks}, volume = 82, year = 2019 }
• {Predicting Server Power Consumption from Standard Rating Results}. von Kistowski, J{ó}akim; Grohmann, Johannes; Schmitt, Norbert; Kounev, Samuel. In Proceedings of the 19th ACM/SPEC International Conference on Performance Engineering, of ICPE ’19, pp. 301–312. Association for Computing Machinery (ACM), New York, NY, USA, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Data center providers and server operators try to reduce the power consumption of their servers. Finding an energy efficient server for a specific target application is a first step in this regard. Estimating the power consumption of an application on an unavailable server is difficult, as nameplate power values are generally overestimations. Offline power models are able to predict the consumption accurately, but are usually intended for system design, requiring very specific and detailed knowledge about the system under consideration. In this paper, we introduce an offline power prediction method that uses the results of standard power rating tools. The method predicts the power consumption of a specific application for multiple load levels on a target server that is otherwise unavailable for testing. We evaluate our approach by predicting the power consumption of three applications on different physical servers. Our method is able to achieve an average prediction error of 9.49% for three workloads running on real-world, physical servers.

  @inproceedings{KiGrScKo2019-ICPE-PowerPrediction, abstract = {Data center providers and server operators try to reduce the power consumption of their servers. Finding an energy efficient server for a specific target application is a first step in this regard. Estimating the power consumption of an application on an unavailable server is difficult, as nameplate power values are generally overestimations. Offline power models are able to predict the consumption accurately, but are usually intended for system design, requiring very specific and detailed knowledge about the system under consideration. In this paper, we introduce an offline power prediction method that uses the results of standard power rating tools. The method predicts the power consumption of a specific application for multiple load levels on a target server that is otherwise unavailable for testing. We evaluate our approach by predicting the power consumption of three applications on different physical servers. Our method is able to achieve an average prediction error of 9.49% for three workloads running on real-world, physical servers.}, address = {New York, NY, USA}, author = {von Kistowski, J{\'o}akim and Grohmann, Johannes and Schmitt, Norbert and Kounev, Samuel}, booktitle = {Proceedings of the 19th ACM/SPEC International Conference on Performance Engineering}, keywords = {Power}, note = {{Full Paper Acceptance Rate: 18.6\% (13/70)}}, pages = {301–312}, publisher = {Association for Computing Machinery (ACM)}, series = {ICPE '19}, title = {{Predicting Server Power Consumption from Standard Rating Results}}, year = 2019 }
• Performance Oriented Dynamic Bypassing for Intrusion Detection Systems. Iffländer, Lukas; Stoll, Jonathan; Rawtani, Nishant; Lesch, Veronika; Lange, Klaus-Dieter; Kounev, Samuel. In Proceedings of the 2019 ACM/SPEC International Conference on Performance Engineering, of ICPE ’19, pp. 159–166. ACM, New York, NY, USA, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Attacks on software systems are becoming more and more frequent, aggressive and sophisticated. With the changing threat landscape, in 2018, organizations are looking at when they will be attacked, not if. Intrusion Detection Systems (IDSs) can help in defending against these attacks. The systems that host IDSs require extensive computing resources as IDSs tend to detect attacks under overloaded conditions wrongfully. With the end of Moore's law and the growing adoption of Internet of Things, designers of security systems can no longer expect processing power to keep up the pace with them. This limitation requires ways to increase the performance of these systems without adding additional compute power. In this work, we present two dynamic and a static approach to bypass IDS for traffic deemed benign. We provide its prototype implementation and evaluate our solution. Our evaluation shows promising results. Performance is increased up to the level of a system without an IDS. Attack detection is within the margin of error from the 100% rate. However, our findings show that dynamic approaches perform best when using software switches. The use of a hardware switch reduces the detection rate and performance significantly.

  @inproceedings{Ifflaender2019_PerformanceOrientedDynamicBypassingforIntrusionDetectionSystems, abstract = {Attacks on software systems are becoming more and more frequent, aggressive and sophisticated. With the changing threat landscape, in 2018, organizations are looking at when they will be attacked, not if. Intrusion Detection Systems (IDSs) can help in defending against these attacks. The systems that host IDSs require extensive computing resources as IDSs tend to detect attacks under overloaded conditions wrongfully. With the end of Moore's law and the growing adoption of Internet of Things, designers of security systems can no longer expect processing power to keep up the pace with them. This limitation requires ways to increase the performance of these systems without adding additional compute power. In this work, we present two dynamic and a static approach to bypass IDS for traffic deemed benign. We provide its prototype implementation and evaluate our solution. Our evaluation shows promising results. Performance is increased up to the level of a system without an IDS. Attack detection is within the margin of error from the 100% rate. However, our findings show that dynamic approaches perform best when using software switches. The use of a hardware switch reduces the detection rate and performance significantly.}, address = {New York, NY, USA}, author = {Iffländer, Lukas and Stoll, Jonathan and Rawtani, Nishant and Lesch, Veronika and Lange, Klaus-Dieter and Kounev, Samuel}, booktitle = {Proceedings of the 2019 ACM/SPEC International Conference on Performance Engineering}, keywords = {Optimization}, pages = {159–166}, publisher = {ACM}, series = {ICPE '19}, title = {Performance Oriented Dynamic Bypassing for Intrusion Detection Systems}, year = 2019 }
• EClaiRE: Context Matters! – Comparing Word Embeddings for Relation Classification. Hettinger, Lena; Zehe, Albin; Dallmann, Alexander; Hotho, Andreas. In INFORMATIK 2019: 50 Jahre Gesellschaft für Informatik – Informatik für Gesellschaft, K. David, K. Geihs, M. Lange, G. Stumme (eds.), pp. 191–204. Gesellschaft für Informatik e.V., Bonn, 2019.
  • [ BibTeX ]
  @inproceedings{hettinger2019eclaire, address = {Bonn}, author = {Hettinger, Lena and Zehe, Albin and Dallmann, Alexander and Hotho, Andreas}, booktitle = {INFORMATIK 2019: 50 Jahre Gesellschaft für Informatik – Informatik für Gesellschaft}, editor = {David, Klaus and Geihs, Kurt and Lange, Martin and Stumme, Gerd}, keywords = {classification}, pages = {191-204}, publisher = {Gesellschaft für Informatik e.V.}, title = {EClaiRE: Context Matters! – Comparing Word Embeddings for Relation Classification}, year = 2019 }
• Team Xenophilius Lovegood at SemEval-2019 Task 4: Hyperpartisanship Classification using Convolutional Neural Networks. Zehe, Albin; Hettinger, Lena; Ernst, Stefan; Hauptmann, Christian; Hotho, Andreas. In Proceedings of The 13th International Workshop on Semantic Evaluation. Association for Computational Linguistics, 2019.
  • [ BibTeX ]
  @inproceedings{zehe2019xenophilius, author = {Zehe, Albin and Hettinger, Lena and Ernst, Stefan and Hauptmann, Christian and Hotho, Andreas}, booktitle = {Proceedings of The 13th International Workshop on Semantic Evaluation}, keywords = {nn}, publisher = {Association for Computational Linguistics}, title = {Team Xenophilius Lovegood at SemEval-2019 Task 4: Hyperpartisanship Classification using Convolutional Neural Networks}, year = 2019 }
• A Tight Approximation for Submodular Maximization with Mixed Packing and Covering Constraints. Mizrachi, Eyal; Schwartz, Roy; Spoerhase, Joachim; Uniyal, Sumedha. In Proc. 46th International Colloquium on Automata, Languages and Programming (ICALP’19). 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{mizrachi-etal19:submodular-mixed, author = {Mizrachi, Eyal and Schwartz, Roy and Spoerhase, Joachim and Uniyal, Sumedha}, booktitle = {Proc. 46th International Colloquium on Automata, Languages and Programming (ICALP'19)}, keywords = {key}, note = {to appear}, title = {A Tight Approximation for Submodular Maximization with Mixed Packing and Covering Constraints}, year = 2019 }
• Towards Adaptive {Car-to-Cloud} Communication. Herrnleben, Stefan; Pfannem{ü}ller, Martin; Krupitzer, Christian; Kounev, Samuel; Segata, Michele; Fastnacht, Felix; Nigmann, Magnus. In Proceedings of the IEEE International Conference on Pervasive Computing and Communications Workshops (PerCom Workshops). Kyoto, Japan, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Recent developments in communication technology have led to cloud resources becoming ubiquitous. These resources enable many new applications by offering computational power for remote embedded devices. In combination with advances in the area of smart driving, this seems to be especially beneficial for applications such as remote maintenance of vehicles or integration with smart city services. As autonomous driving continues to gain traction, Car-to-Cloud communication can support transferring collected data to the cloud, e.g., for dynamic learning of new map information. Additionally, passengers can benefit from novel entertainment services. All these developments require a stable connection between a mobile vehicle and the cloud resources. In this vision paper, we survey Car-to-Cloud communication applications. Based on the analysis of the varying requirements for these applications, we formulate research questions and challenges. Further, we discuss how these challenges can be addressed by means of an adaptive Car-to-Cloud communication middleware. We conclude with an overview on our activities in this area and an outlook on our planned future work on adaptive communication.

  @inproceedings{HePfKrKoSeFaNi2019-PerAwareCity-carToCloudCommunication, abstract = {Recent developments in communication technology have led to cloud resources becoming ubiquitous. These resources enable many new applications by offering computational power for remote embedded devices. In combination with advances in the area of smart driving, this seems to be especially beneficial for applications such as remote maintenance of vehicles or integration with smart city services. As autonomous driving continues to gain traction, Car-to-Cloud communication can support transferring collected data to the cloud, e.g., for dynamic learning of new map information. Additionally, passengers can benefit from novel entertainment services. All these developments require a stable connection between a mobile vehicle and the cloud resources. In this vision paper, we survey Car-to-Cloud communication applications. Based on the analysis of the varying requirements for these applications, we formulate research questions and challenges. Further, we discuss how these challenges can be addressed by means of an adaptive Car-to-Cloud communication middleware. We conclude with an overview on our activities in this area and an outlook on our planned future work on adaptive communication.}, address = {Kyoto, Japan}, author = {Herrnleben, Stefan and Pfannem{\"u}ller, Martin and Krupitzer, Christian and Kounev, Samuel and Segata, Michele and Fastnacht, Felix and Nigmann, Magnus}, booktitle = {Proceedings of the IEEE International Conference on Pervasive Computing and Communications Workshops (PerCom Workshops)}, keywords = {Intelligent_Transportation_Systems}, title = {Towards Adaptive {Car-to-Cloud} Communication}, year = 2019 }
• Towards Adaptive {Car-to-Cloud} Communication. Herrnleben, Stefan; Pfannem{ü}ller, Martin; Krupitzer, Christian; Kounev, Samuel; Segata, Michele; Fastnacht, Felix; Nigmann, Magnus. In Proceedings of the IEEE International Conference on Pervasive Computing and Communications Workshops (PerCom Workshops). Kyoto, Japan, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Recent developments in communication technology have led to cloud resources becoming ubiquitous. These resources enable many new applications by offering computational power for remote embedded devices. In combination with advances in the area of smart driving, this seems to be especially beneficial for applications such as remote maintenance of vehicles or integration with smart city services. As autonomous driving continues to gain traction, Car-to-Cloud communication can support transferring collected data to the cloud, e.g., for dynamic learning of new map information. Additionally, passengers can benefit from novel entertainment services. All these developments require a stable connection between a mobile vehicle and the cloud resources. In this vision paper, we survey Car-to-Cloud communication applications. Based on the analysis of the varying requirements for these applications, we formulate research questions and challenges. Further, we discuss how these challenges can be addressed by means of an adaptive Car-to-Cloud communication middleware. We conclude with an overview on our activities in this area and an outlook on our planned future work on adaptive communication.

  @inproceedings{HePfKrKoSeFaNi2019-PerAwareCity-carToCloudCommunication, abstract = {Recent developments in communication technology have led to cloud resources becoming ubiquitous. These resources enable many new applications by offering computational power for remote embedded devices. In combination with advances in the area of smart driving, this seems to be especially beneficial for applications such as remote maintenance of vehicles or integration with smart city services. As autonomous driving continues to gain traction, Car-to-Cloud communication can support transferring collected data to the cloud, e.g., for dynamic learning of new map information. Additionally, passengers can benefit from novel entertainment services. All these developments require a stable connection between a mobile vehicle and the cloud resources. In this vision paper, we survey Car-to-Cloud communication applications. Based on the analysis of the varying requirements for these applications, we formulate research questions and challenges. Further, we discuss how these challenges can be addressed by means of an adaptive Car-to-Cloud communication middleware. We conclude with an overview on our activities in this area and an outlook on our planned future work on adaptive communication.}, address = {Kyoto, Japan}, author = {Herrnleben, Stefan and Pfannem{\"u}ller, Martin and Krupitzer, Christian and Kounev, Samuel and Segata, Michele and Fastnacht, Felix and Nigmann, Magnus}, booktitle = {Proceedings of the IEEE International Conference on Pervasive Computing and Communications Workshops (PerCom Workshops)}, keywords = {Intelligent_Transportation_Systems}, title = {Towards Adaptive {Car-to-Cloud} Communication}, year = 2019 }
• {Measuring and Rating the Energy-Efficiency of Servers}. von Kistowski, J{ó}akim; Lange, Klaus-Dieter; Arnold, Jeremy A.; Beckett, John; Block, Hansfried; Tricker, Mike; Sharma, Sanjay; Pais, Johann; Kounev, Samuel. In Future Generation Computer Systems, 100, pp. 579–589. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Data centers and servers consume a significant amount of electrical power. As future data centers increase in size, it becomes increasingly important to be able to select servers based on their energy efficiency. Rating the efficiency of servers is challenging, as it depends on the software executed on that server and on its load profile. To account for this, a measurement and rating methodology for servers must make use of both realistic and varying workloads. Existing energy-efficiency benchmarks either run standardized application loads at multiple load levels or multiple micro-benchmarks at full load. This does not enable a full analysis of system behavior as the energy efficiency for different kinds of software at low load levels remains unknown. This article introduces a measurement methodology and metrics for energy-efficiency rating of servers. The methodology defines system setup and instrumentation for reproducible results. It is designed to use multiple, specifically chosen workloads at different load levels for a full system characterization. All partial results are aggregated in a final metric that can be used by regulators to define server-labeling criteria. The methodology and workloads have been implemented in the standardized Server Efficiency Rating Tool. We show the applicability and use of the measurement methodology specifically considering its reproducibility, fairness, and relevance. A reproducibility analysis shows that efficiency scores vary with a maximum coefficient of 1.04\% for repeated experiments. In addition, we evaluate the proposed metrics by investigating their energy-efficiency rating on a set of 385 different servers and show the relevance of the selected workloads by analyzing relationships to real-world applications.

  @article{KiLaArBeBlTrShPaKo-FGCS2019-ServerEfficiency, abstract = {Data centers and servers consume a significant amount of electrical power. As future data centers increase in size, it becomes increasingly important to be able to select servers based on their energy efficiency. Rating the efficiency of servers is challenging, as it depends on the software executed on that server and on its load profile. To account for this, a measurement and rating methodology for servers must make use of both realistic and varying workloads. Existing energy-efficiency benchmarks either run standardized application loads at multiple load levels or multiple micro-benchmarks at full load. This does not enable a full analysis of system behavior as the energy efficiency for different kinds of software at low load levels remains unknown. This article introduces a measurement methodology and metrics for energy-efficiency rating of servers. The methodology defines system setup and instrumentation for reproducible results. It is designed to use multiple, specifically chosen workloads at different load levels for a full system characterization. All partial results are aggregated in a final metric that can be used by regulators to define server-labeling criteria. The methodology and workloads have been implemented in the standardized Server Efficiency Rating Tool. We show the applicability and use of the measurement methodology specifically considering its reproducibility, fairness, and relevance. A reproducibility analysis shows that efficiency scores vary with a maximum coefficient of 1.04\% for repeated experiments. In addition, we evaluate the proposed metrics by investigating their energy-efficiency rating on a set of 385 different servers and show the relevance of the selected workloads by analyzing relationships to real-world applications.}, author = {von Kistowski, J{\'o}akim and Lange, Klaus-Dieter and Arnold, Jeremy A. and Beckett, John and Block, Hansfried and Tricker, Mike and Sharma, Sanjay and Pais, Johann and Kounev, Samuel}, journal = {Future Generation Computer Systems}, keywords = {Power}, pages = {579 - 589}, title = {{Measuring and Rating the Energy-Efficiency of Servers}}, volume = 100, year = 2019 }
• {Measuring the Energy Efficiency of Transactional Loads on GPGPU}. von Kistowski, J{ó}akim; Pais, Johann; Wahl, Tobias; Lange, Klaus-Dieter; Block, Hansfried; Beckett, John; Kounev, Samuel. In Proceedings of the 19th ACM/SPEC International Conference on Performance Engineering, of ICPE ’19. ACM, New York, NY, USA, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  {General Purpose Graphics Processing Units (GPGPUs) are becoming more and more common in current servers and data centers, which in turn consume a significant amount of electrical power. Measuring and benchmarking this power consumption is important as it helps with optimization and selection of these servers. However, benchmarking and comparing the energy efficiency of GPGPU workloads is challenging as standardized workloads are rare and standardized power and efficiency measurement methods and metrics do not exist. In addition, not all GPGPU systems run at maximum load all the time. Systems that are utilized in transactional, request driven workloads, for example, can run at lower utilization levels. Existing benchmarks for GPGPU systems primarily consider performance and are intended only to run at maximum load. They do not measure performance or energy efficiency at other loads. In turn, server energy-efficiency benchmarks that consider multiple load levels do not address GPGPUs. This paper introduces a measurement methodology for servers with GPGPU accelerators that considers multiple load levels for transactional workloads. The methodology also addresses verifiability of results in order to achieve comparability of different device solutions. We analyze our methodology on three different systems with solutions from two different accelerator vendors. We investigate the efficacy of different methods of load levels scaling and our methodology's reproducibility. We show that the methodology is able to produce consistent and reproducible results with a maximum coefficient of variation of 1.4\% regarding power consumption.}

  @inproceedings{KiPaWaLaBlBeKo2019-ICPE-GPGPUPower, abstract = {{General Purpose Graphics Processing Units (GPGPUs) are becoming more and more common in current servers and data centers, which in turn consume a significant amount of electrical power. Measuring and benchmarking this power consumption is important as it helps with optimization and selection of these servers. However, benchmarking and comparing the energy efficiency of GPGPU workloads is challenging as standardized workloads are rare and standardized power and efficiency measurement methods and metrics do not exist. In addition, not all GPGPU systems run at maximum load all the time. Systems that are utilized in transactional, request driven workloads, for example, can run at lower utilization levels. Existing benchmarks for GPGPU systems primarily consider performance and are intended only to run at maximum load. They do not measure performance or energy efficiency at other loads. In turn, server energy-efficiency benchmarks that consider multiple load levels do not address GPGPUs. This paper introduces a measurement methodology for servers with GPGPU accelerators that considers multiple load levels for transactional workloads. The methodology also addresses verifiability of results in order to achieve comparability of different device solutions. We analyze our methodology on three different systems with solutions from two different accelerator vendors. We investigate the efficacy of different methods of load levels scaling and our methodology's reproducibility. We show that the methodology is able to produce consistent and reproducible results with a maximum coefficient of variation of 1.4\% regarding power consumption.}}, address = {New York, NY, USA}, author = {von Kistowski, J{\'o}akim and Pais, Johann and Wahl, Tobias and Lange, Klaus-Dieter and Block, Hansfried and Beckett, John and Kounev, Samuel}, booktitle = {Proceedings of the 19th ACM/SPEC International Conference on Performance Engineering}, keywords = {Power}, note = {{<b>Best Industry Paper Award</b>}}, publisher = {ACM}, series = {ICPE '19}, title = {{Measuring the Energy Efficiency of Transactional Loads on GPGPU}}, year = 2019 }
• Crossing Numbers of Beyond-Planar Graphs. Chimani, Markus; Kindermann, Philipp; Montecchiani, Fabrizio; Valtr, Pavel. In Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. T{ó}th (eds.), pp. 78–86. Springer-Verlag, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  We study lower bounds on the minimum number of crossings for 1-planar, quasi-planar, and fan-planar graphs. We prove that there are n-vertex 1-planar (quasi-planar, fan-planar) graphs such that any 1-planar (quasi-planar, fan-planar) drawing has Omega(n) crossings, while O(1) crossings suffice in a crossing-minimal drawing with no restrictions on local edge crossing patterns.

  @inproceedings{ckmv-cnbpg-gd19, abstract = {We study lower bounds on the minimum number of crossings for 1-planar, quasi-planar, and fan-planar graphs. We prove that there are n-vertex 1-planar (quasi-planar, fan-planar) graphs such that any 1-planar (quasi-planar, fan-planar) drawing has Omega(n) crossings, while O(1) crossings suffice in a crossing-minimal drawing with no restrictions on local edge crossing patterns.}, author = {Chimani, Markus and Kindermann, Philipp and Montecchiani, Fabrizio and Valtr, Pavel}, booktitle = {Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD'19)}, editor = {Archambault, Daniel and T\'{o}th, Csaba D.}, keywords = {myown}, pages = {78–86}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Crossing Numbers of Beyond-Planar Graphs}, volume = 11904, year = 2019 }
• Drawing Planar Graphs with Few Segments on a Polynomial Grid. Kindermann, Philipp; Mchedlidze, Tamara; Schneck, Thomas; Symvonis, Antonios. In Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. T{ó}th (eds.), pp. 416–429. Springer-Verlag, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  The visual complexity of a graph drawing can be measured by the number of geometric objects used for the representation of its elements. In this paper, we study planar graph drawings where edges are represented by few segments. In such a drawing, one segment may represent multiple edges forming a path. Drawings of planar graphs with few segments were intensively studied in the past years. However, the area requirements were only considered for limited subclasses of planar graphs. In this paper, we show that trees have drawings with 3n/4-1 segments and n^2 area, improving the previous result of O(n^{3.58}). We also show that 3-connected planar graphs and biconnected outerplanar graphs have a drawing with 8n/3-O(1) and 3n/2-O(1) segments, respectively, and O(n^3) area.

  @inproceedings{kmss-dpgfs-gd19, abstract = {The visual complexity of a graph drawing can be measured by the number of geometric objects used for the representation of its elements. In this paper, we study planar graph drawings where edges are represented by few segments. In such a drawing, one segment may represent multiple edges forming a path. Drawings of planar graphs with few segments were intensively studied in the past years. However, the area requirements were only considered for limited subclasses of planar graphs. In this paper, we show that trees have drawings with 3n/4-1 segments and n^2 area, improving the previous result of O(n^{3.58}). We also show that 3-connected planar graphs and biconnected outerplanar graphs have a drawing with 8n/3-O(1) and 3n/2-O(1) segments, respectively, and O(n^3) area.}, author = {Kindermann, Philipp and Mchedlidze, Tamara and Schneck, Thomas and Symvonis, Antonios}, booktitle = {Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD'19)}, editor = {Archambault, Daniel and T\'{o}th, Csaba D.}, keywords = {myown}, pages = {416–429}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Drawing Planar Graphs with Few Segments on a Polynomial Grid}, volume = 11904, year = 2019 }
• Hands Off my Database: Ransomware Detection in Databases through Dynamic Analysis of Query Sequences. Iffl{{ä}}nder, Lukas; Dmitrienko, Alexandra; Hagen, Christoph; Jobst, Michael; Kounev, Samuel. In ArXiv | arXiv:1907.06775v1. 2019.
  • [ BibTeX ]
  • [ URL ]
  @article{DBLP:journals/corr/abs-1907-06775, author = {Iffl{\"{a}}nder, Lukas and Dmitrienko, Alexandra and Hagen, Christoph and Jobst, Michael and Kounev, Samuel}, journal = {ArXiv | arXiv:1907.06775v1}, keywords = {ransomware}, title = {Hands Off my Database: Ransomware Detection in Databases through Dynamic Analysis of Query Sequences}, year = 2019 }
• Textual Case-based Adaptation using Semantic Relatedness - A Case Study in the Domain of Security Documents. Korger, Andreas; Baumeister, Joachim. In WM2019 - 10te Konferenz Professionelles Wissensmanagement. 2019.
  • [ BibTeX ]
  @inproceedings{korger2019textual, author = {Korger, Andreas and Baumeister, Joachim}, booktitle = {WM2019 - 10te Konferenz Professionelles Wissensmanagement}, keywords = {myown}, title = {Textual Case-based Adaptation using Semantic Relatedness - A Case Study in the Domain of Security Documents}, year = 2019 }
• Interactive Agent-Based Biological Cell Simulations for Morphogenesis. Knote, Andreas; \textbf{S. {von Mammen}}. pp. 115–124. Kassel University Press, 2019.
  • [ BibTeX ]
  • [ URL ]
  @inbook{Knote:2019aa, author = {Knote, Andreas and \textbf{S. {von Mammen}}}, chapter = 9, keywords = {myown}, pages = {115-124}, publisher = {Kassel University Press}, title = {Interactive Agent-Based Biological Cell Simulations for Morphogenesis}, year = 2019 }
• [DC] VR Simulation as a Motivator in Gait Rehabilitation. Hamzeheinejad, Negin. In 2019 IEEE Conference on Virtual Reality and 3D User Interfaces (VR), pp. 1383–1384. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Gait rehabilitation is a necessary process for patients suffering from post-stroke motor impairments. The patients are required to perform repetitive practices using a robot-assisted gait device. Repeated exercises can become extremely frustrating and the patients lose their motivation over time. In my PhD research, I focus on Virtual Reality (VR) as a medium to improve gait rehabilitation in terms of enjoyment, motivation, efficiency, and effectiveness. The objective is to systematically investigate different factors, such as the presence of a trainer, interactivity, gamification, and storytelling in a two-step process. First, by evaluating the applicability of different factors for the clinical use with healthy subjects. Second, by evaluating the effectiveness of the VR simulation with patients with gait deficits, especially stroke patients in collaboration with a [country] clinic.

  @inproceedings{hamzeheinejad2019simulation, abstract = {Gait rehabilitation is a necessary process for patients suffering from post-stroke motor impairments. The patients are required to perform repetitive practices using a robot-assisted gait device. Repeated exercises can become extremely frustrating and the patients lose their motivation over time. In my PhD research, I focus on Virtual Reality (VR) as a medium to improve gait rehabilitation in terms of enjoyment, motivation, efficiency, and effectiveness. The objective is to systematically investigate different factors, such as the presence of a trainer, interactivity, gamification, and storytelling in a two-step process. First, by evaluating the applicability of different factors for the clinical use with healthy subjects. Second, by evaluating the effectiveness of the VR simulation with patients with gait deficits, especially stroke patients in collaboration with a [country] clinic.}, author = {Hamzeheinejad, Negin}, booktitle = {2019 IEEE Conference on Virtual Reality and 3D User Interfaces (VR)}, keywords = {vrgait}, pages = {1383-1384}, publisher = {IEEE}, title = {[DC] VR Simulation as a Motivator in Gait Rehabilitation}, year = 2019 }
• A Scalability Benchmark for a Virtual Audience Perception Model in Virtual Reality. Glémarec, Yann; Bosser, Anne-Gwenn; Lugrin, Jean-Luc; Chollet, Mathieu; Buche, Cédric; Landeck, Maximilian; Latoschik, Marc Erich. In Proceedings of the 25th ACM Conference on Virtual Reality Software and Technology, Vol. VRST’19. 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{glemarec2019scalability, author = {Glémarec, Yann and Bosser, Anne-Gwenn and Lugrin, Jean-Luc and Chollet, Mathieu and Buche, Cédric and Landeck, Maximilian and Latoschik, Marc Erich}, booktitle = {Proceedings of the 25th ACM Conference on Virtual Reality Software and Technology}, keywords = {vrst19}, title = {A Scalability Benchmark for a Virtual Audience Perception Model in Virtual Reality}, volume = {VRST'19}, year = 2019 }
• Predicting Learning Effects of Computer Games Using the Gamified Knowledge Encoding Model. Oberdörfer, Sebastian; Latoschik, Marc Erich. In Entertainment Computing, 32, M. Rauterberg; F. Liarokapis (eds.), p. 100315. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Game mechanics encode a computer game’s underlying principles as their internal rules. These game rules consist of information relevant to a specific learning content in the case of a serious game. This paper describes an approach to predict the learning effect of computer games by analyzing the structure of the provided game mechanics. In particular, we utilize the Gamified Knowledge Encoding model to predict the learning effects of playing the computer game Kerbal Space Program (KSP). We tested the correctness of the prediction in a user study evaluating the learning effects of playing KSP. Participants achieved a significant increase in knowledge about orbital mechanics during their first gameplay hours. In the second phase of the study, we assessed KSP’s applicability as an educational tool and compared it to a traditional learning method in respect to the learning outcome. The results indicate a highly motivating and effective knowledge learning. Also, participants used KSP to validate complex theoretical spaceflight concepts.

  @article{oberdorfer2019predicting, abstract = {Game mechanics encode a computer game’s underlying principles as their internal rules. These game rules consist of information relevant to a specific learning content in the case of a serious game. This paper describes an approach to predict the learning effect of computer games by analyzing the structure of the provided game mechanics. In particular, we utilize the Gamified Knowledge Encoding model to predict the learning effects of playing the computer game Kerbal Space Program (KSP). We tested the correctness of the prediction in a user study evaluating the learning effects of playing KSP. Participants achieved a significant increase in knowledge about orbital mechanics during their first gameplay hours. In the second phase of the study, we assessed KSP’s applicability as an educational tool and compared it to a traditional learning method in respect to the learning outcome. The results indicate a highly motivating and effective knowledge learning. Also, participants used KSP to validate complex theoretical spaceflight concepts.}, author = {Oberdörfer, Sebastian and Latoschik, Marc Erich}, editor = {Rauterberg, Matthias and Liarokapis, Fotis}, journal = {Entertainment Computing}, keywords = {myown}, pages = 100315, title = {Predicting Learning Effects of Computer Games Using the Gamified Knowledge Encoding Model}, volume = 32, year = 2019 }
• Empathy \& Information: Ingredients for a Children’s Game on Diabetes. Burkholz, Jan; \textbf{S. {von Mammen}}. In 2019 11th International Conference on Virtual Worlds and Games for Serious Applications (VS-Games), pp. 1–2. IEEE, 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Burkholz:2019aa, author = {Burkholz, Jan and \textbf{S. {von Mammen}}}, booktitle = {2019 11th International Conference on Virtual Worlds and Games for Serious Applications (VS-Games)}, keywords = {myown}, note = {Best poster paper award 🏆}, organization = {IEEE}, pages = {1–2}, title = {Empathy \& Information: Ingredients for a Children's Game on Diabetes}, year = 2019 }
• Line and Plane Cover Numbers Revisited. Biedl, Therese; Felsner, Stefan; Meijer, Henk; Wolff, Alexander. In Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. Tóth (eds.), pp. 409–415. Springer-Verlag, 2019.
  • [ BibTeX ]
  @inproceedings{bfmw-lpcnr-GD19, author = {Biedl, Therese and Felsner, Stefan and Meijer, Henk and Wolff, Alexander}, booktitle = {Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD'19)}, editor = {Archambault, Daniel and Tóth, Csaba D.}, keywords = {myown}, pages = {409–415}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Line and Plane Cover Numbers Revisited}, volume = 11904, year = 2019 }
• Visual Analytics for Sets over Time and Space. Fabrikant, Sara Irina; Miksch, Silvia; Wolff, Alexander. In Vol. 9, pp. 31–57. Schloss Dagstuhl – Leibniz-Zentrum für Informatik, 2019.
  • [ BibTeX ]
  @proceedings{fmw-vasts-DR19, annote = {Keywords: Geovisualization, graph drawing, information visualization, set visualization, visual analytics}, editor = {Fabrikant, Sara Irina and Miksch, Silvia and Wolff, Alexander}, journal = {Dagstuhl Reports}, keywords = {myown}, note = {Dagstuhl Seminar 19192}, number = 5, pages = {31–57}, publisher = {Schloss Dagstuhl – Leibniz-Zentrum für Informatik}, title = {Visual Analytics for Sets over Time and Space}, volume = 9, year = 2019 }
• Bundled Crossings Revisited. Chaplick, Steven; van Dijk, Thomas C.; Kryven, Myroslav; Park, Ji-Won; Ravsky, Alexander; Wolff, Alexander. In Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. Tóth (eds.), pp. 63–77. Springer-Verlag, 2019.
  • [ BibTeX ]
  @inproceedings{cdkprw-bcr-GD19, author = {Chaplick, Steven and van Dijk, Thomas C. and Kryven, Myroslav and Park, Ji-Won and Ravsky, Alexander and Wolff, Alexander}, booktitle = {Proc. 27th Int. Symp. Graph Drawing \& Network Vis. (GD'19)}, editor = {Archambault, Daniel and Tóth, Csaba D.}, keywords = {myown}, pages = {63–77}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Bundled Crossings Revisited}, volume = 11904, year = 2019 }
• Perceived Authenticity, Empathy, and Pro-social Intentions Evoked Through Avatar-mediated Self-disclosures. Roth, Daniel; Bloch, Carola; Schmitt, Josephine; Frischlich, Lena; Latoschik, Marc Erich; Bente, Gary. In Proceedings of Mensch Und Computer 2019, of MuC’19, pp. 21–30. ACM, New York, NY, USA, 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{roth2019toappearperceived, address = {New York, NY, USA}, author = {Roth, Daniel and Bloch, Carola and Schmitt, Josephine and Frischlich, Lena and Latoschik, Marc Erich and Bente, Gary}, booktitle = {Proceedings of Mensch Und Computer 2019}, keywords = {droth}, pages = {21–30}, publisher = {ACM}, series = {MuC'19}, title = {Perceived Authenticity, Empathy, and Pro-social Intentions Evoked Through Avatar-mediated Self-disclosures}, year = 2019 }
• Commission Errors with Forced Response Lag. Schaper, Philipp; Grundgeiger, Tobias. In Quarterly Journal of Experimental Psychology, 72(10), pp. 2380–2392. 2019.
  • [ BibTeX ]
  @article{schaper2019commission, author = {Schaper, Philipp and Grundgeiger, Tobias}, journal = {Quarterly Journal of Experimental Psychology}, keywords = {myown}, number = 10, pages = {2380-2392}, title = {Commission Errors with Forced Response Lag}, volume = 72, year = 2019 }
• Dissecting the performance of YouTube video streaming in mobile networks. Schwind, Anika; Midoglu, Cise; Alay, Özgü; Griwodz, Carsten; Wamser, Florian. In International Journal of Network Management. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Video streaming applications constitute a significant portion of the Internet traffic today, with mobile accounting for more than half of the online video views. The high share of video in the current Internet traffic mix has prompted many studies that examine video streaming through measurements. However, streaming performance depends on many different factors at different layers of the TCP/IP stack. For example, browser selection at the application layer or the choice of protocol in transport layer can have significant impact on the video performance. Furthermore, video performance heavily depends on the underlying network conditions (eg, network and link layers). For mobile networks, the conditions vary significantly, since each operator has a different deployment strategy and configuration. In this paper, we focus on YouTube and carry out a comprehensive study investigating the influence of different factors on streaming performance. Leveraging the Measuring Mobile Broadband Networks in Europe (MONROE) test bed that enables experimentation with 13 different network configurations in four countries, we collect more than 1800 measurement samples in operational mobile networks. With this campaign, our goal is to quantify the impact of parameters from different layers on YouTube's streaming quality of experience (QoE). More specifically, we analyze the role of the browser (eg, Firefox and Chrome), the impact of transport protocol (eg, TCP or QUIC), the influence of network bandwidth, and signal coverage on streaming QoE. Our analysis reveals that all these parameters need to be taken into account jointly for network management practices, in order to ensure a high end‐user experience.

  @article{info3-article-2019-2, abstract = {Video streaming applications constitute a significant portion of the Internet traffic today, with mobile accounting for more than half of the online video views. The high share of video in the current Internet traffic mix has prompted many studies that examine video streaming through measurements. However, streaming performance depends on many different factors at different layers of the TCP/IP stack. For example, browser selection at the application layer or the choice of protocol in transport layer can have significant impact on the video performance. Furthermore, video performance heavily depends on the underlying network conditions (eg, network and link layers). For mobile networks, the conditions vary significantly, since each operator has a different deployment strategy and configuration. In this paper, we focus on YouTube and carry out a comprehensive study investigating the influence of different factors on streaming performance. Leveraging the Measuring Mobile Broadband Networks in Europe (MONROE) test bed that enables experimentation with 13 different network configurations in four countries, we collect more than 1800 measurement samples in operational mobile networks. With this campaign, our goal is to quantify the impact of parameters from different layers on YouTube's streaming quality of experience (QoE). More specifically, we analyze the role of the browser (eg, Firefox and Chrome), the impact of transport protocol (eg, TCP or QUIC), the influence of network bandwidth, and signal coverage on streaming QoE. Our analysis reveals that all these parameters need to be taken into account jointly for network management practices, in order to ensure a high end‐user experience.}, author = {Schwind, Anika and Midoglu, Cise and Alay, Özgü and Griwodz, Carsten and Wamser, Florian}, journal = {International Journal of Network Management}, keywords = {can}, month = {01}, title = {Dissecting the performance of YouTube video streaming in mobile networks}, year = 2019 }
• {Utilizing Clustering to Optimize Resource Demand Estimation Approaches}. Grohmann, Johannes; Eismann, Simon; Bauer, Andre; Zuefle, Marwin; Herbst, Nikolas; Kounev, Samuel. In 2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W), pp. 134–139. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Resource demands are crucial parameters for modeling and predicting the performance of software systems. Direct measurement of these resource demands is usually infeasible due to instrumentation overheads causing measurement interferences and perturbation in production environments. Thus, a number of statistical estimation approaches (e.g., based on optimization, regression or Kalman filters) have been proposed in the literature. Most of these approaches are parameterized. These parameters influence the estimation quality and the required computation time. Existing work uses historical data as training sets to optimize those parameters and to minimize the estimation error of those approaches. However, if the data traces are fundamentally different, the optimal parameter settings are different as well. In this paper, we propose to use automated clustering in order to group training sets into groups of similar optimization behavior. This way, optimization can be specifically tailored to certain groups of traces in a self-aware manner. During run-time, every trace is first sorted into a cluster, where the respective cluster-wide parameter optimum can be applied. A preliminary case study shows that clustering can provide promising improvements.

  @inproceedings{GrEiBaZuHeKo2019-ICAC-RDEClustering, abstract = {Resource demands are crucial parameters for modeling and predicting the performance of software systems. Direct measurement of these resource demands is usually infeasible due to instrumentation overheads causing measurement interferences and perturbation in production environments. Thus, a number of statistical estimation approaches (e.g., based on optimization, regression or Kalman filters) have been proposed in the literature. Most of these approaches are parameterized. These parameters influence the estimation quality and the required computation time. Existing work uses historical data as training sets to optimize those parameters and to minimize the estimation error of those approaches. However, if the data traces are fundamentally different, the optimal parameter settings are different as well. In this paper, we propose to use automated clustering in order to group training sets into groups of similar optimization behavior. This way, optimization can be specifically tailored to certain groups of traces in a self-aware manner. During run-time, every trace is first sorted into a cluster, where the respective cluster-wide parameter optimum can be applied. A preliminary case study shows that clustering can provide promising improvements.}, author = {Grohmann, Johannes and Eismann, Simon and Bauer, Andre and Zuefle, Marwin and Herbst, Nikolas and Kounev, Samuel}, booktitle = {2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)}, keywords = {Optimization}, month = {06}, pages = {134–139}, publisher = {IEEE}, title = {{Utilizing Clustering to Optimize Resource Demand Estimation Approaches}}, year = 2019 }
• Stream-based Machine Learning for Real-time QoE Analysis of Encrypted Video Streaming Traffic. Seufert, Michael; Casas, Pedro; Wehner, Nikolas; Li, Gang; Kuang, Li. In 3rd International Workshop on Quality of Experience Management (QoE-Management). Paris, France, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  As stalling is the worst Quality of Experience (QoE) degradation of HTTP adaptive video streaming (HAS), this work presents a stream-based machine learning approach, ViCrypt, which analyzes stalling of YouTube streaming sessions in real-time from encrypted network traffic. The video streaming session is subdivided into a stream of short time slots of 1 s length, while considering two additional macro windows each for the current streaming trend and the whole ongoing streaming session. Constant memory features are extracted from the encrypted network traffic in these three windows in a stream-based fashion, and fed into a random forest model, which predicts whether the current time slot contains stalling or not. The presented system can predict stalling with a very high accuracy and the finest granularity to date (1 s), and thus, can be used in networks for real-time QoE analysis from encrypted YouTube video streaming traffic. The independent predictions for each consecutive slot of a streaming session can further be aggregated to obtain stalling estimations for the whole session. Thereby, the proposed method allows to quantify the initial delay, as well as the overall number of stalling events and the stalling ratio, i.e., the ratio of total stalling time and total playback time.

  @inproceedings{info3-inproceedings-2019-8, abstract = {As stalling is the worst Quality of Experience (QoE) degradation of HTTP adaptive video streaming (HAS), this work presents a stream-based machine learning approach, ViCrypt, which analyzes stalling of YouTube streaming sessions in real-time from encrypted network traffic. The video streaming session is subdivided into a stream of short time slots of 1 s length, while considering two additional macro windows each for the current streaming trend and the whole ongoing streaming session. Constant memory features are extracted from the encrypted network traffic in these three windows in a stream-based fashion, and fed into a random forest model, which predicts whether the current time slot contains stalling or not. The presented system can predict stalling with a very high accuracy and the finest granularity to date (1 s), and thus, can be used in networks for real-time QoE analysis from encrypted YouTube video streaming traffic. The independent predictions for each consecutive slot of a streaming session can further be aggregated to obtain stalling estimations for the whole session. Thereby, the proposed method allows to quantify the initial delay, as well as the overall number of stalling events and the stalling ratio, i.e., the ratio of total stalling time and total playback time.}, address = {Paris, France}, author = {Seufert, Michael and Casas, Pedro and Wehner, Nikolas and Li, Gang and Kuang, Li}, booktitle = {3rd International Workshop on Quality of Experience Management (QoE-Management)}, keywords = {net-man}, month = {02}, title = {Stream-based Machine Learning for Real-time QoE Analysis of Encrypted Video Streaming Traffic}, year = 2019 }
• {An Evaluation Tool for Cost-Aware Vehicle Route Calculation}. Technical Report (Master thesis), . Hadry, Marius. Master thesis. University of W{ü}rzburg, Am Hubland, Informatikgeb{ä}ude, 97074 W{ü}rzburg, Germany, 2019, August.
  • [ BibTeX ]
  @mastersthesis{Hadry2019, address = {Am Hubland, Informatikgeb{\"a}ude, 97074 W{\"u}rzburg, Germany}, author = {Hadry, Marius}, keywords = {Self-adaptive-systems}, month = {08}, school = {University of W{\"u}rzburg}, title = {{An Evaluation Tool for Cost-Aware Vehicle Route Calculation}}, type = {{Bachelor Thesis}}, year = 2019 }
• Crowd-based Study of Gameplay Impairments and Player Performance in DOTA 2. Hirth, Matthias; Borchert, Kathrin; Allendorf, Fabian; Metzger, Florian; Hoßfeld, Tobias. In 4th Internet-QoE Workshop: QoE-based Analysis and Management of Data Communication Networks (Internet-QoE’19). Los Cabos, Mexico, 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-24, address = {Los Cabos, Mexico}, author = {Hirth, Matthias and Borchert, Kathrin and Allendorf, Fabian and Metzger, Florian and Hoßfeld, Tobias}, booktitle = {4th Internet-QoE Workshop: QoE-based Analysis and Management of Data Communication Networks (Internet-QoE'19)}, keywords = {ua-net}, month = 10, title = {Crowd-based Study of Gameplay Impairments and Player Performance in DOTA 2}, year = 2019 }
• Modeling of Traffic Flows in Internet of Things Using Renewal Approximation. Wamser, Florian; Tran-Gia, Phuoc; Geissler, Stefan; Hoßfeld, Tobias. In International Conference on Optimization and Decision Science (ODS2019). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  This paper proposes a versatile approach to model aggregated traffic flows in the Internet of Things (IoT) using renewal approximation. The modeled traffic originates from a large number of sources or devices consisting of a set of sensors mixed with classical elastic random traffic modeled as Poisson arrival process. The work shows the exact derivation in the simple case for periodic sensors. It shows further results in the mixed case with periodic sensors and a background process. The renewal approximation allows to derive the required number of sensors such that the aggregated traffic can be approximated as Poisson process.

  @inproceedings{info3-article-2019-8, abstract = {This paper proposes a versatile approach to model aggregated traffic flows in the Internet of Things (IoT) using renewal approximation. The modeled traffic originates from a large number of sources or devices consisting of a set of sensors mixed with classical elastic random traffic modeled as Poisson arrival process. The work shows the exact derivation in the simple case for periodic sensors. It shows further results in the mixed case with periodic sensors and a background process. The renewal approximation allows to derive the required number of sensors such that the aggregated traffic can be approximated as Poisson process.}, author = {Wamser, Florian and Tran-Gia, Phuoc and Geissler, Stefan and Hoßfeld, Tobias}, booktitle = {International Conference on Optimization and Decision Science (ODS2019)}, keywords = {can}, month = {09}, title = {Modeling of Traffic Flows in Internet of Things Using Renewal Approximation}, year = 2019 }
• Engineering a Showcase of Virtual Reality Exposure Therapy. Müller, Andreas; Truman, Samuel; von Mammen, Sebastian; Brukamp, Kirsten. In 2019 11th International Conference on Virtual Worlds and Games for Serious Applications (VS-Games), pp. 1–2. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Numerous research studies and controlled trials have unveiled the potential of serious games in various health-related areas [1]. Their range of application can be even further extended by the use of virtual reality (VR) technology, which allows the realistic representation of interactive contents. Virtual Reality Exposure Therapy (VRET) is a very promising novel use case for the development of serious games. Held in a virtual environment (VE) adaptive to the needs of the patient, this form of therapy can outperform traditional realworld measures [2], [3]. One of its major success factors is the engagement of the patient, which can be increased by an immersive gaming experience. We show a demonstrator of VRET application for a fire-related post-traumatic stress disorder (PTSD). In this demonstrator, features to support actively guided VR experiences are improved on, focusing on the interactive adaptivity of the VE.

  @inproceedings{conf/vsgames/MullerTMB19, abstract = {Numerous research studies and controlled trials have unveiled the potential of serious games in various health-related areas [1]. Their range of application can be even further extended by the use of virtual reality (VR) technology, which allows the realistic representation of interactive contents. Virtual Reality Exposure Therapy (VRET) is a very promising novel use case for the development of serious games. Held in a virtual environment (VE) adaptive to the needs of the patient, this form of therapy can outperform traditional realworld measures [2], [3]. One of its major success factors is the engagement of the patient, which can be increased by an immersive gaming experience. We show a demonstrator of VRET application for a fire-related post-traumatic stress disorder (PTSD). In this demonstrator, features to support actively guided VR experiences are improved on, focusing on the interactive adaptivity of the VE.}, author = {Müller, Andreas and Truman, Samuel and von Mammen, Sebastian and Brukamp, Kirsten}, booktitle = {2019 11th International Conference on Virtual Worlds and Games for Serious Applications (VS-Games)}, keywords = {via-vr}, month = {09}, pages = {1-2}, publisher = {IEEE}, title = {Engineering a Showcase of Virtual Reality Exposure Therapy}, year = 2019 }
• Crowd-based Assessment of Deformational Cranial Asymmetries. Borchert, Kathrin; Hirth, Matthias; Stellzig-Eisenhauer, Angelika; Kunz, Felix. In International Workshop on Crowd-Powered e-Services (CROPS). Trondheim, Norway, 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-17, address = {Trondheim, Norway}, author = {Borchert, Kathrin and Hirth, Matthias and Stellzig-Eisenhauer, Angelika and Kunz, Felix}, booktitle = {International Workshop on Crowd-Powered e-Services (CROPS)}, keywords = {ua-net}, month = {09}, title = {Crowd-based Assessment of Deformational Cranial Asymmetries}, year = 2019 }
• On the Analysis of YouTube QoE in Cellular Networks through in-Smartphone Measurements. Wassermann, Sarah; Casas, Pedro; Seufert, Michael; Wamser, Florian. In 12th IFIP Wireless and Mobile Networking Conference (WMNC). Paris, France, 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-18, address = {Paris, France}, author = {Wassermann, Sarah and Casas, Pedro and Seufert, Michael and Wamser, Florian}, booktitle = {12th IFIP Wireless and Mobile Networking Conference (WMNC)}, keywords = {ua-net}, month = {09}, title = {On the Analysis of YouTube QoE in Cellular Networks through in-Smartphone Measurements}, year = 2019 }
• Fancy Fruits - An Augmented Reality Application for Special Needs Education. Steinhaeusser, Sophia C; Riedmann, Anna; Haller, Max; Oberdörfer, Sebastian; Bucher, Kristina; Latoschik, Marc Erich. In Proceedings of the 11th International Conference on Virtual Worlds and Games for Serious Applications (VS Games 2019), pp. 1–4. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Augmented Reality (AR) allows for a connection between real and virtual worlds, thus providing a high potential for Special Needs Education (SNE). We developed an educational application called Fancy Fruits to teach disabled children the components of regional fruits and vegetables. The app includes marker-based AR elements connecting the real situation with virtual information. To evaluate the application, a field study was conducted. Eleven children with mental disabilities took part in the study. The results show a high enjoyment of the participants. The study also validated the app's child-friendly design.

  @inproceedings{steinhaeusser2019fancy, abstract = {Augmented Reality (AR) allows for a connection between real and virtual worlds, thus providing a high potential for Special Needs Education (SNE). We developed an educational application called Fancy Fruits to teach disabled children the components of regional fruits and vegetables. The app includes marker-based AR elements connecting the real situation with virtual information. To evaluate the application, a field study was conducted. Eleven children with mental disabilities took part in the study. The results show a high enjoyment of the participants. The study also validated the app's child-friendly design.}, author = {Steinhaeusser, Sophia C and Riedmann, Anna and Haller, Max and Oberdörfer, Sebastian and Bucher, Kristina and Latoschik, Marc Erich}, booktitle = {Proceedings of the 11th International Conference on Virtual Worlds and Games for Serious Applications (VS Games 2019)}, keywords = {steinhaeusser}, month = {09}, organization = {IEEE}, pages = {1-4}, title = {Fancy Fruits - An Augmented Reality Application for Special Needs Education}, year = 2019 }
• Task Scheduling on Crowdsourcing Platforms for Enabling Completion Time SLAs. Hirth, Matthias; Steurer, Florian; Borchert, Kathrin; Dubiner, Dan. In 31st International Teletraffic Congress (ITC). Budapest, Hungary, 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-20, address = {Budapest, Hungary}, author = {Hirth, Matthias and Steurer, Florian and Borchert, Kathrin and Dubiner, Dan}, booktitle = {31st International Teletraffic Congress (ITC)}, keywords = {ua-net}, month = {08}, title = {Task Scheduling on Crowdsourcing Platforms for Enabling Completion Time SLAs}, year = 2019 }
• Discrete-Time Analysis of the Blockchain Distributed Ledger Technology. Geissler, Stefan; Prantl, Thomas; Lange, Stanislav; Wamser, Florian; Hoßfeld, Tobias. In 31st International Teletraffic Congress (ITC). , Budapest, Hungary. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Blockchain and distributed ledger technologies have become more and more popular and widespread during recent years. After the initial hype about the technology and many cryptocurrency related use cases, the technology slowly starts to make its way into other domains like food tracking and document management. In order to further contribute to the search of what this technology can be used for, more detailed performance evaluations are required in order to investigate key performance indicators and general limits of the technology. To this end, we develop a discrete-time queueing model that allows a detailed evaluation of the characteristics of a blockchain system, such as the transaction waiting time distribution. Furthermore, we validate the model by comparing the results to values obtained from measurements in a closed lab environment based on the Ethereum blockchain.

  @inproceedings{info3-inproceedings-2019-19, abstract = {Blockchain and distributed ledger technologies have become more and more popular and widespread during recent years. After the initial hype about the technology and many cryptocurrency related use cases, the technology slowly starts to make its way into other domains like food tracking and document management. In order to further contribute to the search of what this technology can be used for, more detailed performance evaluations are required in order to investigate key performance indicators and general limits of the technology. To this end, we develop a discrete-time queueing model that allows a detailed evaluation of the characteristics of a blockchain system, such as the transaction waiting time distribution. Furthermore, we validate the model by comparing the results to values obtained from measurements in a closed lab environment based on the Ethereum blockchain.}, author = {Geissler, Stefan and Prantl, Thomas and Lange, Stanislav and Wamser, Florian and Hoßfeld, Tobias}, booktitle = {31st International Teletraffic Congress (ITC). , Budapest, Hungary}, keywords = {net-man}, month = {08}, title = {Discrete-Time Analysis of the Blockchain Distributed Ledger Technology}, year = 2019 }
• Discrete-Time Analysis of the Blockchain Distributed Ledger Technology. Geissler, Stefan; Prantl, Thomas; Lange, Stanislav; Wamser, Florian; Hossfeld, Tobias. In Proceedings of the 31st International Teletraffic Congress (ITC). 2019.
  • [ BibTeX ]
  @inproceedings{GePrLaWaHo2019-ITC-Blockchain, author = {Geissler, Stefan and Prantl, Thomas and Lange, Stanislav and Wamser, Florian and Hossfeld, Tobias}, booktitle = {Proceedings of the 31st International Teletraffic Congress (ITC)}, keywords = {descartes}, month = {08}, title = {Discrete-Time Analysis of the Blockchain Distributed Ledger Technology}, year = 2019 }
• Methodological Principles for Reproducible Performance Evaluation in Cloud Computing. Papadopoulos, Alessandro Vittorio; Versluis, Laurens; Bauer, Andr{é}; Herbst, Nikolas; von Kistowski, J{ó}akim; Ali-Eldin, Ahmed; Abad, Cristina; Amaral, J. Nelson; Tuma, Petr; Iosup, Alexandru. In IEEE Transactions on Software Engineering, 47(8), pp. 1528–1543. 2019.
  • [ BibTeX ]
  @article{PaVeBaHeKiAEAbAmTuIo2019-TSE-MethodologicalPrinciples, author = {Papadopoulos, Alessandro Vittorio and Versluis, Laurens and Bauer, Andr{\'e} and Herbst, Nikolas and von Kistowski, J{\'o}akim and Ali-Eldin, Ahmed and Abad, Cristina and Amaral, J. Nelson and Tuma, Petr and Iosup, Alexandru}, journal = {IEEE Transactions on Software Engineering}, keywords = {SPEC}, month = {07}, number = 8, pages = {1528-1543}, title = {Methodological Principles for Reproducible Performance Evaluation in Cloud Computing}, volume = 47, year = 2019 }
• A Systematic View on Speech Assistants for Service Technicians. Baumeister, Joachim; Sehne, Veronika; Wienrich, Carolin. In Proceedings of LWDA - Lernen. Wissen. Daten. Analysen 2019, pp. 195–206. Humboldt-Universität zu Berlin, 2019.
  • [ BibTeX ]
  @inproceedings{baumeister2019systematic, address = {Humboldt-Universität zu Berlin}, author = {Baumeister, Joachim and Sehne, Veronika and Wienrich, Carolin}, booktitle = {Proceedings of LWDA - Lernen. Wissen. Daten. Analysen 2019}, keywords = {myown}, month = 10, pages = {195-206}, title = {A Systematic View on Speech Assistants for Service Technicians}, year = 2019 }
• {From the Internet-of-Things to the Internet-of-Thinking-Things}. Kounev, Samuel. 2019, July.
  • [ BibTeX ]
  @misc{talk-Kounev-InvTUM19, author = {Kounev, Samuel}, howpublished = {Informatik-Sonderkolloquium "Engineering Software for Decentralized Systems", Fakult{\"a}t f{\"u}r Informatik, Technische Universit{\"a}t M{\"u}nchen, Munich, Germany}, keywords = {descartes}, month = {07}, title = {{From the Internet-of-Things to the Internet-of-Thinking-Things}}, year = 2019 }
• Chamulteon: Coordinated Auto-Scaling of Micro-Services. Bauer, Andr{é}; Lesch, Veronika; Versluis, Laurens; Ilyushkin, Alexey; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 39th IEEE International Conference on Distributed Computing Systems (ICDCS). 2019.
  • [ BibTeX ]
  @inproceedings{BaLeVeIlHeKo2019-ICDCS-Chamulteon, author = {Bauer, Andr{\'e} and Lesch, Veronika and Versluis, Laurens and Ilyushkin, Alexey and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 39th IEEE International Conference on Distributed Computing Systems (ICDCS)}, keywords = {SPEC}, month = {07}, title = {Chamulteon: Coordinated Auto-Scaling of Micro-Services}, year = 2019 }
• Chamulteon: Coordinated Auto-Scaling of Micro-Services. Bauer, Andr{é}; Lesch, Veronika; Versluis, Laurens; Ilyushkin, Alexey; Herbst, Nikolas; Kounev, Samuel. In Proceedings of the 39th IEEE International Conference on Distributed Computing Systems (ICDCS). 2019.
  • [ BibTeX ]
  @inproceedings{BaLeVeIlHeKo2019-ICDCS-Chamulteon, author = {Bauer, Andr{\'e} and Lesch, Veronika and Versluis, Laurens and Ilyushkin, Alexey and Herbst, Nikolas and Kounev, Samuel}, booktitle = {Proceedings of the 39th IEEE International Conference on Distributed Computing Systems (ICDCS)}, keywords = {SPEC}, month = {07}, title = {Chamulteon: Coordinated Auto-Scaling of Micro-Services}, year = 2019 }
• Hands Off my Database: Ransomware Detection in Databases through Dynamic Analysis of Query Sequences. Iffländer, Lukas; Dmitrienko, Alexandra; Hagen, Christoph; Jobst, Michael; Kounev, Samuel. Universit{ä}t W{ü}rzburg, 2019.
  • [ BibTeX ]
  • [ URL ]
  @techreport{Ifflander_Hands_Off_my_Database, author = {Iffländer, Lukas and Dmitrienko, Alexandra and Hagen, Christoph and Jobst, Michael and Kounev, Samuel}, institution = {Universit{\"a}t W{\"u}rzburg}, journal = {arXiv}, keywords = {t_techreport}, month = {07}, title = {Hands Off my Database: Ransomware Detection in Databases through Dynamic Analysis of Query Sequences}, year = 2019 }
• A 4D information system for the exploration of multitemporal images and maps using photogrammetry, Web technologies and VR/AR. Maiwald, Ferdinand; Bruschke, Jonas; Lehmann, Christoph; Niebling, Florian. In Virtual Archaeology Review, 10(21), J. L. Lerma (ed.), pp. 1–13. 2019.
  • [ BibTeX ]
  @article{maiwald2019information, author = {Maiwald, Ferdinand and Bruschke, Jonas and Lehmann, Christoph and Niebling, Florian}, editor = {Lerma, José Luis}, journal = {Virtual Archaeology Review}, keywords = {histstadt4d}, month = {07}, number = 21, pages = {1-13}, title = {A 4D information system for the exploration of multitemporal images and maps using photogrammetry, Web technologies and VR/AR}, volume = 10, year = 2019 }
• Considering User Behavior in the Quality of Experience Cycle: Towards Proactive QoE-aware Traffic Management. Seufert, Michael; Wassermann, Sarah; Casas, Pedro. In IEEE Communications Letters, 23(7), pp. 1145–1148. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  The concept of Quality of Experience (QoE) of Internet services is widely recognized by service providers and network operators. They strive to deliver the best experience to their customers in order to increase revenues and avoid churn. Therefore, QoE is increasingly considered as an integral part of the reactive traffic management cycle of network operators. Additionally, QoE also constitutes a cycle of its own, which includes the user behavior and the service requirements. This work describes this QoE cycle, which is not widely taken into account yet, discusses the interactions of the two cycles, and derives implications towards an improved and proactive QoE-aware traffic management. A showcase on how network operators can obtain hints on the change of network requirements from detecting user behavior in encrypted video traffic is also presented in this paper.

  @article{info3-article-2019-5, abstract = {The concept of Quality of Experience (QoE) of Internet services is widely recognized by service providers and network operators. They strive to deliver the best experience to their customers in order to increase revenues and avoid churn. Therefore, QoE is increasingly considered as an integral part of the reactive traffic management cycle of network operators. Additionally, QoE also constitutes a cycle of its own, which includes the user behavior and the service requirements. This work describes this QoE cycle, which is not widely taken into account yet, discusses the interactions of the two cycles, and derives implications towards an improved and proactive QoE-aware traffic management. A showcase on how network operators can obtain hints on the change of network requirements from detecting user behavior in encrypted video traffic is also presented in this paper.}, author = {Seufert, Michael and Wassermann, Sarah and Casas, Pedro}, journal = {IEEE Communications Letters}, keywords = {ua-net}, month = {07}, number = 7, pages = {1145-1148}, title = {Considering User Behavior in the Quality of Experience Cycle: Towards Proactive QoE-aware Traffic Management}, volume = 23, year = 2019 }
• Is QUIC becoming the New TCP? On the Potential Impact of a New Protocol on Networked Multimedia QoE. Seufert, Michael. 11th International Conference on Quality of Multimedia Experience (QoMEX), Berlin, Germany, 2019, June 7.
  • [ BibTeX ]
  @presentation{info3-presentation-2019-5, address = {11th International Conference on Quality of Multimedia Experience (QoMEX), Berlin, Germany}, author = {Seufert, Michael}, keywords = {myown}, month = {06}, title = {Is QUIC becoming the New TCP? On the Potential Impact of a New Protocol on Networked Multimedia QoE}, year = 2019 }
• Fundamental Advantages of Considering Quality of Experience Distributions over Mean Opinion Scores. Seufert, Michael. 11th International Conference on Quality of Multimedia Experience (QoMEX), Berlin, Germany, 2019, June 5.
  • [ BibTeX ]
  @presentation{info3-presentation-2019-4, address = {11th International Conference on Quality of Multimedia Experience (QoMEX), Berlin, Germany}, author = {Seufert, Michael}, keywords = {myown}, month = {06}, title = {Fundamental Advantages of Considering Quality of Experience Distributions over Mean Opinion Scores}, year = 2019 }
• Research Activities Report for "Managing Web & Cloud QoE TF". Seufert, Michael. 13th Qualinet General Meeting, Berlin, Germany, 2019, June 4.
  • [ BibTeX ]
  @presentation{info3-presentation-2019-3, address = {13th Qualinet General Meeting, Berlin, Germany}, author = {Seufert, Michael}, keywords = {myown}, month = {06}, title = {Research Activities Report for "Managing Web & Cloud QoE TF"}, year = 2019 }
• {Detecting Parametric Dependencies for Performance Models Using Feature Selection Techniques}. Grohmann, Johannes; Eismann, Simon; Elflein, Sven; Mazkatli, Manar; von Kistowski, J{ó}akim; Kounev, Samuel. In 2019 IEEE 27th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS), of MASCOTS ’19, pp. 309–322. IEEE Computer Society, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Architectural performance models are a common approach to predict the performance properties of a software system. Parametric dependencies, which describe the relation between the input parameters of a component and its performance properties, significantly increase the prediction accuracy of architectural performance models. However, manually modeling parametric dependencies is time-intensive and requires expert knowledge. Existing automated extraction approaches require dedicated performance tests, which are often infeasible. In this paper, we introduce an approach to automatically identify parametric dependencies from monitoring data using feature selection techniques from the area of machine learning. We evaluate the applicability of three techniques selected from each of the three groups of feature selection methods: a filter method, an embedded method, and a wrapper method. Our evaluation shows that the filter technique outperforms the other approaches. Based on these results, we apply this technique to a distributed micro-service web-shop, where it correctly identifies 11 performance-relevant dependencies, achieving a precision of 91.7% based on a manually labeled gold-standard.

  @inproceedings{GrEiElMaKiKo2019-MASCOTS-DependencyIdentification, abstract = {Architectural performance models are a common approach to predict the performance properties of a software system. Parametric dependencies, which describe the relation between the input parameters of a component and its performance properties, significantly increase the prediction accuracy of architectural performance models. However, manually modeling parametric dependencies is time-intensive and requires expert knowledge. Existing automated extraction approaches require dedicated performance tests, which are often infeasible. In this paper, we introduce an approach to automatically identify parametric dependencies from monitoring data using feature selection techniques from the area of machine learning. We evaluate the applicability of three techniques selected from each of the three groups of feature selection methods: a filter method, an embedded method, and a wrapper method. Our evaluation shows that the filter technique outperforms the other approaches. Based on these results, we apply this technique to a distributed micro-service web-shop, where it correctly identifies 11 performance-relevant dependencies, achieving a precision of 91.7% based on a manually labeled gold-standard.}, author = {Grohmann, Johannes and Eismann, Simon and Elflein, Sven and Mazkatli, Manar and von Kistowski, J{\'o}akim and Kounev, Samuel}, booktitle = {2019 IEEE 27th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS)}, keywords = {Automated_model_learning}, month = 10, note = {{Acceptance Rate: 23.8% (29/122)}}, pages = {309–322}, publisher = {IEEE Computer Society}, series = {MASCOTS '19}, title = {{Detecting Parametric Dependencies for Performance Models Using Feature Selection Techniques}}, year = 2019 }
• Case-Based Retrieval and Adaptation of Regulatory Documents and their Context. Korger, Andreas; Baumeister, Joachim. In Proceedings of LWDA - Lernen. Wissen. Daten. Analysen 2019, pp. 292–303. Humboldt-Universität zu Berlin, 2019.
  • [ BibTeX ]
  @inproceedings{korger2019casebased, address = {Humboldt-Universität zu Berlin}, author = {Korger, Andreas and Baumeister, Joachim}, booktitle = {Proceedings of LWDA - Lernen. Wissen. Daten. Analysen 2019}, keywords = {myown}, month = 10, pages = {292-303}, title = {Case-Based Retrieval and Adaptation of Regulatory Documents and their Context}, year = 2019 }
• Let me Decrypt your Beauty: Real-time Prediction of Video Resolution and Bitrate for Encrypted Video Streaming. Wassermann, Sarah; Seufert, Michael; Casas, Pedro; Li, Gang; Kuang, Li. Paris, France, 2019, June.
  • [ BibTeX ]
  @misc{info3-software-2019-1, address = {Paris, France}, author = {Wassermann, Sarah and Seufert, Michael and Casas, Pedro and Li, Gang and Kuang, Li}, booktitle = {Network Traffic Measurement and Analysis Conference (TMA)}, keywords = {net-man}, month = {06}, title = {Let me Decrypt your Beauty: Real-time Prediction of Video Resolution and Bitrate for Encrypted Video Streaming}, year = 2019 }
• Towards Testing the Software Aging Behavior of Hypervisor Hypercall Interfaces. Beierlieb, Lukas; Iffländer, Lukas; Milenkoski, Aleksandar; Goncalves, Charles F.; Antunes, Nuno; Kounev, Samuel. In 2019 {IEEE} International Symposium on Software Reliability Engineering Workshops ({ISSREW}). {IEEE}, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  With the continuing rise of cloud technology hypervisors play a vital role in the performance and reliability of current services. As long-running applications, they are susceptible to software aging. Hypervisors offer so-called hypercall interfaces for communication with the hosted virtual machines. These interfaces require thorough robustness to assure performance, security, and reliability. Existing research either deals with the aging properties of hypervisors in general without considering the hypercalls or focuses on finding hypercall-related vulnerabilities. In this work, we discuss open challenges regarding hypercall interfaces. To address these challenges, we propose an extensive framework architecture to perform robustness testing on hypercall interfaces. This framework supports extensive test campaigns as well as the modeling of hypercall interfaces.

  @inproceedings{Beierlieb_2019_TowardsTestingtheSoftwareAgingBehaviorofHypervisorHypercallInterfaces, abstract = {With the continuing rise of cloud technology hypervisors play a vital role in the performance and reliability of current services. As long-running applications, they are susceptible to software aging. Hypervisors offer so-called hypercall interfaces for communication with the hosted virtual machines. These interfaces require thorough robustness to assure performance, security, and reliability. Existing research either deals with the aging properties of hypervisors in general without considering the hypercalls or focuses on finding hypercall-related vulnerabilities. In this work, we discuss open challenges regarding hypercall interfaces. To address these challenges, we propose an extensive framework architecture to perform robustness testing on hypercall interfaces. This framework supports extensive test campaigns as well as the modeling of hypercall interfaces.}, author = {Beierlieb, Lukas and Iffländer, Lukas and Milenkoski, Aleksandar and Goncalves, Charles F. and Antunes, Nuno and Kounev, Samuel}, booktitle = {2019 {IEEE} International Symposium on Software Reliability Engineering Workshops ({ISSREW})}, keywords = {t_workshop}, month = 11, organization = {{IEEE}}, title = {Towards Testing the Software Aging Behavior of Hypervisor Hypercall Interfaces}, year = 2019 }
• Kaa: Evaluating Elasticity of Cloud-hosted DBMS. Seybold, Daniel; Volpert, Simon; Wesner, Stefan; Bauer, Andr{é}; Herbst, Nikolas; Domaschka, J{ö}rg. In Proceedings of the 11th IEEE International Conference on Cloud Computing (CloudCom). 2019.
  • [ BibTeX ]
  @inproceedings{SeVoWeBaHeDo-CloudCom-Kaa, author = {Seybold, Daniel and Volpert, Simon and Wesner, Stefan and Bauer, Andr{\'e} and Herbst, Nikolas and Domaschka, J{\"o}rg}, booktitle = {Proceedings of the 11th IEEE International Conference on Cloud Computing (CloudCom)}, keywords = {Elasticity}, month = 12, title = {Kaa: Evaluating Elasticity of Cloud-hosted DBMS}, year = 2019 }
• Hypercall Interface Testing for the Example of Hyper-V. Technical Report (Master thesis), . Beierlieb, Lukas. Master thesis. University of Würzburg, Am Hubland, Informatikgebäude, 97074 Würzburg, Germany, 2019, December.
  • [ BibTeX ]
  @mastersthesis{beierlieb2019hypercall, address = {Am Hubland, Informatikgebäude, 97074 Würzburg, Germany}, author = {Beierlieb, Lukas}, keywords = {descartes}, month = 12, note = {Würzburg Software Engineering Award Runner Up Masterthesis}, school = {University of Würzburg}, title = {Hypercall Interface Testing for the Example of Hyper-V}, type = {Bachelor Thesis}, year = 2019 }
• Immersive Analysis of 3D Multi-cellular In-Vitro and In-Silico Cell Cultures. {Knote}, Andreas; {Fischer}, Sabine; {Cussat-Blanc}, Sylvain; {Niebling}, Florian; {Bernard}, David; {Cogoni}, Florian; \textbf{S. {von Mammen}}. In 2019 IEEE International Conference on Artificial Intelligence and Virtual Reality (AIVR), pp. 82–827. 2019.
  • [ BibTeX ]
  • [ URL ]
  @inproceedings{Knote:2019ab, author = {{Knote}, Andreas and {Fischer}, Sabine and {Cussat-Blanc}, Sylvain and {Niebling}, Florian and {Bernard}, David and {Cogoni}, Florian and \textbf{S. {von Mammen}}}, booktitle = {2019 IEEE International Conference on Artificial Intelligence and Virtual Reality (AIVR)}, keywords = {biology,}, month = 12, pages = {82-827}, title = {Immersive Analysis of 3D Multi-cellular In-Vitro and In-Silico Cell Cultures}, year = 2019 }
• {On Learning Parametric Dependencies from Monitoring Data}. Grohmann, Johannes; Eismann, Simon; Kounev, Samuel. In Proceedings of the 10th Symposium on Software Performance 2019 (SSP’19). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  A common approach to predict system performance are so-called architectural performance models. In these models, parametric dependencies describe the relation between the input parameters of a component and its performance properties and therefore significantly increase the model expressiveness. However, manually modeling parametric dependencies is often infeasible in practice. Existing automated extraction approaches require either application source code or dedicated performance tests, which are not always available. We therefore introduced one approach for identification and one for characterization of parametric dependencies, solely based on run-time monitoring data. In this paper, we propose our idea on combining both techniques in order to create a holistic approach for the identification and characterization of parametric dependencies. Furthermore, we discuss challenges we are currently facing and potential ideas on how to overcome them.

  @inproceedings{GrEiKo2019-SSP-LearningDependencies, abstract = {A common approach to predict system performance are so-called architectural performance models. In these models, parametric dependencies describe the relation between the input parameters of a component and its performance properties and therefore significantly increase the model expressiveness. However, manually modeling parametric dependencies is often infeasible in practice. Existing automated extraction approaches require either application source code or dedicated performance tests, which are not always available. We therefore introduced one approach for identification and one for characterization of parametric dependencies, solely based on run-time monitoring data. In this paper, we propose our idea on combining both techniques in order to create a holistic approach for the identification and characterization of parametric dependencies. Furthermore, we discuss challenges we are currently facing and potential ideas on how to overcome them.}, author = {Grohmann, Johannes and Eismann, Simon and Kounev, Samuel}, booktitle = {Proceedings of the 10th Symposium on Software Performance 2019 (SSP'19)}, keywords = {t_workshop}, month = 11, title = {{On Learning Parametric Dependencies from Monitoring Data}}, year = 2019 }
• Towards Testing the Performance Influence of Hypervisor Hypercall Interface Behavior. Beierlieb, Lukas; Iffländer, Lukas; Kounev, Samuel; Milenkoski, Aleksandar. In Proceedings of the 10th Symposium on Software Performance 2019 (SSP’19). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  With the continuing rise of cloud technology hypervisors play a vital role in the performance and reliability of current services. Hypervisors offer so-called hypercall interfaces for communication with the hosted virtual machines. These interfaces require thorough robustness to assure performance, security, and reliability. Existing research focusses on finding hypercall-related vulnerabilities. In this work, we discuss open challenges regarding hypercall interfaces. To address these challenges, we propose an extensive framework architecture to perform robustness testing on hypercall interfaces. This framework supports test campaigns and modeling of hypercall interfaces.

  @inproceedings{Beierlieb_2019_TowardsTestingthePerformanceInfluenceofHypervisorHypercallInterfaceBehavior, abstract = {With the continuing rise of cloud technology hypervisors play a vital role in the performance and reliability of current services. Hypervisors offer so-called hypercall interfaces for communication with the hosted virtual machines. These interfaces require thorough robustness to assure performance, security, and reliability. Existing research focusses on finding hypercall-related vulnerabilities. In this work, we discuss open challenges regarding hypercall interfaces. To address these challenges, we propose an extensive framework architecture to perform robustness testing on hypercall interfaces. This framework supports test campaigns and modeling of hypercall interfaces.}, author = {Beierlieb, Lukas and Iffländer, Lukas and Kounev, Samuel and Milenkoski, Aleksandar}, booktitle = {Proceedings of the 10th Symposium on Software Performance 2019 (SSP'19)}, keywords = {t_workshop}, month = 11, title = {Towards Testing the Performance Influence of Hypervisor Hypercall Interface Behavior}, year = 2019 }
• {Artificial Intelligence in Medicine - From Data Collection to Prediction}. Z{ü}fle, Marwin; Leppich, Robert. 2019, November.
  • [ BibTeX ]
  @misc{talk-ZuLe, author = {Z{\"u}fle, Marwin and Leppich, Robert}, howpublished = {Invited Talk at Klinikum N{\"u}rnberg}, keywords = {Sports}, month = 11, title = {{Artificial Intelligence in Medicine - From Data Collection to Prediction}}, year = 2019 }
• The SPEC-RG Reference Architecture for FaaS: From Microservices and Containers to Serverless Platforms. van Eyk, Erwin; Grohmann, Johannes; Eismann, Simon; Bauer, Andr{é}; Versluis, Laurens; Toader, Lucian; Schmitt, Norbert; Herbst, Nikolas; Abad, Cristina L.; Iosup, Alexandru. In IEEE Internet Computing, 23(6), pp. 7–18. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Microservices, containers, and serverless computing belong to a trend toward applications composed of many small, self-contained, and automatically managed components. Core to serverless computing, Function-as-a-Service (FaaS) platforms employ state-of-the-art container technology and microservices-based architectures to enable users to manage complex applications without the need for systems-level expertise. Victim of its own success, and partially due to proprietary technology, currently the community has a limited overview of these platforms. To address this, we propose a reference architecture and ecosystem for FaaS platforms. Based on a year-long survey of real-world platforms conducted within the SPEC-RG Cloud Group, we highlight specific components and identify common operational patterns.

  @article{vEGrEiBaVeToScHeAbIo-IC-FaaS, abstract = {Microservices, containers, and serverless computing belong to a trend toward applications composed of many small, self-contained, and automatically managed components. Core to serverless computing, Function-as-a-Service (FaaS) platforms employ state-of-the-art container technology and microservices-based architectures to enable users to manage complex applications without the need for systems-level expertise. Victim of its own success, and partially due to proprietary technology, currently the community has a limited overview of these platforms. To address this, we propose a reference architecture and ecosystem for FaaS platforms. Based on a year-long survey of real-world platforms conducted within the SPEC-RG Cloud Group, we highlight specific components and identify common operational patterns.}, author = {van Eyk, Erwin and Grohmann, Johannes and Eismann, Simon and Bauer, Andr{\'e} and Versluis, Laurens and Toader, Lucian and Schmitt, Norbert and Herbst, Nikolas and Abad, Cristina L. and Iosup, Alexandru}, journal = {IEEE Internet Computing}, keywords = {SPEC}, month = 11, number = 6, pages = {7–18}, publisher = {IEEE}, title = {The SPEC-RG Reference Architecture for FaaS: From Microservices and Containers to Serverless Platforms}, volume = 23, year = 2019 }
• Rapid Preparation of Eye Tracking Data For Debriefing In Medical Training: A Feasibility Study. Wolf, E.; Heinrich, R.; Michalek, A.; Schraudt, D.; Hohm, A.; Hein, R.; Grundgeiger, T.; Happel, O. In Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 63(1), pp. 733–737. {SAGE} Publications, 2019.
  • [ BibTeX ]
  • [ URL ]
  @article{Wolf_2019, author = {Wolf, E. and Heinrich, R. and Michalek, A. and Schraudt, D. and Hohm, A. and Hein, R. and Grundgeiger, T. and Happel, O.}, journal = {Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, keywords = {myown}, month = 11, number = 1, pages = {733–737}, publisher = {{SAGE} Publications}, title = {Rapid Preparation of Eye Tracking Data For Debriefing In Medical Training: A Feasibility Study}, volume = 63, year = 2019 }
• Towards Testing the Performance Influence of Hypervisor Hypercall Interface Behavior. Beierlieb, Lukas; Iffländer, Lukas; Kounev, Samuel; Milenkoski, Aleksandar. In Proceedings of the 10th Symposium on Software Performance 2019 (SSP’19). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  With the continuing rise of cloud technology hypervisors play a vital role in the performance and reliability of current services. Hypervisors offer so-called hypercall interfaces for communication with the hosted virtual machines. These interfaces require thorough robustness to assure performance, security, and reliability. Existing research focusses on finding hypercall-related vulnerabilities. In this work, we discuss open challenges regarding hypercall interfaces. To address these challenges, we propose an extensive framework architecture to perform robustness testing on hypercall interfaces. This framework supports test campaigns and modeling of hypercall interfaces.

  @inproceedings{Beierlieb_2019_TowardsTestingthePerformanceInfluenceofHypervisorHypercallInterfaceBehavior, abstract = {With the continuing rise of cloud technology hypervisors play a vital role in the performance and reliability of current services. Hypervisors offer so-called hypercall interfaces for communication with the hosted virtual machines. These interfaces require thorough robustness to assure performance, security, and reliability. Existing research focusses on finding hypercall-related vulnerabilities. In this work, we discuss open challenges regarding hypercall interfaces. To address these challenges, we propose an extensive framework architecture to perform robustness testing on hypercall interfaces. This framework supports test campaigns and modeling of hypercall interfaces.}, author = {Beierlieb, Lukas and Iffländer, Lukas and Kounev, Samuel and Milenkoski, Aleksandar}, booktitle = {Proceedings of the 10th Symposium on Software Performance 2019 (SSP'19)}, keywords = {t_workshop}, month = 11, title = {Towards Testing the Performance Influence of Hypervisor Hypercall Interface Behavior}, year = 2019 }
• The SPEC-RG Reference Architecture for FaaS: From Microservices and Containers to Serverless Platforms. van Eyk, Erwin; Grohmann, Johannes; Eismann, Simon; Bauer, Andr{é}; Versluis, Laurens; Toader, Lucian; Schmitt, Norbert; Herbst, Nikolas; Abad, Cristina L.; Iosup, Alexandru. In IEEE Internet Computing, 23(6), pp. 7–18. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Microservices, containers, and serverless computing belong to a trend toward applications composed of many small, self-contained, and automatically managed components. Core to serverless computing, Function-as-a-Service (FaaS) platforms employ state-of-the-art container technology and microservices-based architectures to enable users to manage complex applications without the need for systems-level expertise. Victim of its own success, and partially due to proprietary technology, currently the community has a limited overview of these platforms. To address this, we propose a reference architecture and ecosystem for FaaS platforms. Based on a year-long survey of real-world platforms conducted within the SPEC-RG Cloud Group, we highlight specific components and identify common operational patterns.

  @article{vEGrEiBaVeToScHeAbIo-IC-FaaS, abstract = {Microservices, containers, and serverless computing belong to a trend toward applications composed of many small, self-contained, and automatically managed components. Core to serverless computing, Function-as-a-Service (FaaS) platforms employ state-of-the-art container technology and microservices-based architectures to enable users to manage complex applications without the need for systems-level expertise. Victim of its own success, and partially due to proprietary technology, currently the community has a limited overview of these platforms. To address this, we propose a reference architecture and ecosystem for FaaS platforms. Based on a year-long survey of real-world platforms conducted within the SPEC-RG Cloud Group, we highlight specific components and identify common operational patterns.}, author = {van Eyk, Erwin and Grohmann, Johannes and Eismann, Simon and Bauer, Andr{\'e} and Versluis, Laurens and Toader, Lucian and Schmitt, Norbert and Herbst, Nikolas and Abad, Cristina L. and Iosup, Alexandru}, journal = {IEEE Internet Computing}, keywords = {SPEC}, month = 11, number = 6, pages = {7–18}, publisher = {IEEE}, title = {The SPEC-RG Reference Architecture for FaaS: From Microservices and Containers to Serverless Platforms}, volume = 23, year = 2019 }
• {Detecting Parametric Dependencies for Performance Models Using Feature Selection Techniques}. Grohmann, Johannes; Eismann, Simon; Elflein, Sven; Mazkatli, Manar; von Kistowski, J{ó}akim; Kounev, Samuel. In 2019 IEEE 27th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS), of MASCOTS ’19, pp. 309–322. IEEE Computer Society, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Architectural performance models are a common approach to predict the performance properties of a software system. Parametric dependencies, which describe the relation between the input parameters of a component and its performance properties, significantly increase the prediction accuracy of architectural performance models. However, manually modeling parametric dependencies is time-intensive and requires expert knowledge. Existing automated extraction approaches require dedicated performance tests, which are often infeasible. In this paper, we introduce an approach to automatically identify parametric dependencies from monitoring data using feature selection techniques from the area of machine learning. We evaluate the applicability of three techniques selected from each of the three groups of feature selection methods: a filter method, an embedded method, and a wrapper method. Our evaluation shows that the filter technique outperforms the other approaches. Based on these results, we apply this technique to a distributed micro-service web-shop, where it correctly identifies 11 performance-relevant dependencies, achieving a precision of 91.7% based on a manually labeled gold-standard.

  @inproceedings{GrEiElMaKiKo2019-MASCOTS-DependencyIdentification, abstract = {Architectural performance models are a common approach to predict the performance properties of a software system. Parametric dependencies, which describe the relation between the input parameters of a component and its performance properties, significantly increase the prediction accuracy of architectural performance models. However, manually modeling parametric dependencies is time-intensive and requires expert knowledge. Existing automated extraction approaches require dedicated performance tests, which are often infeasible. In this paper, we introduce an approach to automatically identify parametric dependencies from monitoring data using feature selection techniques from the area of machine learning. We evaluate the applicability of three techniques selected from each of the three groups of feature selection methods: a filter method, an embedded method, and a wrapper method. Our evaluation shows that the filter technique outperforms the other approaches. Based on these results, we apply this technique to a distributed micro-service web-shop, where it correctly identifies 11 performance-relevant dependencies, achieving a precision of 91.7% based on a manually labeled gold-standard.}, author = {Grohmann, Johannes and Eismann, Simon and Elflein, Sven and Mazkatli, Manar and von Kistowski, J{\'o}akim and Kounev, Samuel}, booktitle = {2019 IEEE 27th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS)}, keywords = {Automated_model_learning}, month = 10, note = {{Acceptance Rate: 23.8% (29/122)}}, pages = {309–322}, publisher = {IEEE Computer Society}, series = {MASCOTS '19}, title = {{Detecting Parametric Dependencies for Performance Models Using Feature Selection Techniques}}, year = 2019 }
• {On Learning Parametric Dependencies from Monitoring Data}. Grohmann, Johannes; Eismann, Simon; Kounev, Samuel. In Proceedings of the 10th Symposium on Software Performance 2019 (SSP’19). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  A common approach to predict system performance are so-called architectural performance models. In these models, parametric dependencies describe the relation between the input parameters of a component and its performance properties and therefore significantly increase the model expressiveness. However, manually modeling parametric dependencies is often infeasible in practice. Existing automated extraction approaches require either application source code or dedicated performance tests, which are not always available. We therefore introduced one approach for identification and one for characterization of parametric dependencies, solely based on run-time monitoring data. In this paper, we propose our idea on combining both techniques in order to create a holistic approach for the identification and characterization of parametric dependencies. Furthermore, we discuss challenges we are currently facing and potential ideas on how to overcome them.

  @inproceedings{GrEiKo2019-SSP-LearningDependencies, abstract = {A common approach to predict system performance are so-called architectural performance models. In these models, parametric dependencies describe the relation between the input parameters of a component and its performance properties and therefore significantly increase the model expressiveness. However, manually modeling parametric dependencies is often infeasible in practice. Existing automated extraction approaches require either application source code or dedicated performance tests, which are not always available. We therefore introduced one approach for identification and one for characterization of parametric dependencies, solely based on run-time monitoring data. In this paper, we propose our idea on combining both techniques in order to create a holistic approach for the identification and characterization of parametric dependencies. Furthermore, we discuss challenges we are currently facing and potential ideas on how to overcome them.}, author = {Grohmann, Johannes and Eismann, Simon and Kounev, Samuel}, booktitle = {Proceedings of the 10th Symposium on Software Performance 2019 (SSP'19)}, keywords = {t_workshop}, month = 11, title = {{On Learning Parametric Dependencies from Monitoring Data}}, year = 2019 }
• The Power of Composition: Abstracting a Multi-Device SDN Data Path Through a Single API. Geissler, Stefan; Herrnleben, Stefan; Bauer, Robert; Grigorjew, Alexej; Jarschel, Michael; Zinner, Thomas. In IEEE Transactions on Network and Service Management. 2019.
  • [ BibTeX ]
  @article{info3-article-2019-11, author = {Geissler, Stefan and Herrnleben, Stefan and Bauer, Robert and Grigorjew, Alexej and Jarschel, Michael and Zinner, Thomas}, journal = {IEEE Transactions on Network and Service Management}, keywords = {fia}, month = 11, title = {The Power of Composition: Abstracting a Multi-Device SDN Data Path Through a Single API}, year = 2019 }
• Technologies for Social Augmentations in User-Embodied Virtual Reality. Roth, Daniel; Bente, Gary; Kullmann, Peter; Mal, David; Purps, Christian Felix; Vogeley, Kai; Latoschik, Marc Erich. In 25th ACM Symposium on Virtual Reality Software and Technology (VRST), of VRST ’19, pp. 1–12. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Technologies for Virtual, Mixed, and Augmented Reality (VR, MR, and AR) allow to artificially augment social interactions and thus to go beyond what is possible in real life. Motivations for the use of social augmentations are manifold, for example, to synthesize behavior when sensory input is missing, to provide additional affordances in shared environments, or to support inclusion and training of individuals with social communication disorders. We review and categorize augmentation approaches and propose a software architecture based on four data layers. Three components further handle the status analysis, the modification, and the blending of behaviors. We present a prototype (injectX) that supports behavior tracking (body motion, eye gaze, and facial expressions from the lower face), status analysis, decision-making, augmentation, and behavior blending in immersive interactions. Along with a critical reflection, we consider further technical and ethical aspects.

  @conference{roth2019technologies, abstract = {Technologies for Virtual, Mixed, and Augmented Reality (VR, MR, and AR) allow to artificially augment social interactions and thus to go beyond what is possible in real life. Motivations for the use of social augmentations are manifold, for example, to synthesize behavior when sensory input is missing, to provide additional affordances in shared environments, or to support inclusion and training of individuals with social communication disorders. We review and categorize augmentation approaches and propose a software architecture based on four data layers. Three components further handle the status analysis, the modification, and the blending of behaviors. We present a prototype (injectX) that supports behavior tracking (body motion, eye gaze, and facial expressions from the lower face), status analysis, decision-making, augmentation, and behavior blending in immersive interactions. Along with a critical reflection, we consider further technical and ethical aspects.}, author = {Roth, Daniel and Bente, Gary and Kullmann, Peter and Mal, David and Purps, Christian Felix and Vogeley, Kai and Latoschik, Marc Erich}, booktitle = {25th ACM Symposium on Virtual Reality Software and Technology (VRST)}, keywords = {insync}, month = 11, pages = {1-12}, series = {VRST '19}, title = {Technologies for Social Augmentations in User-Embodied Virtual Reality}, year = 2019 }
• Towards Testing the Software Aging Behavior of Hypervisor Hypercall Interfaces. Beierlieb, Lukas; Iffländer, Lukas; Milenkoski, Aleksandar; Goncalves, Charles F.; Antunes, Nuno; Kounev, Samuel. In 2019 {IEEE} International Symposium on Software Reliability Engineering Workshops ({ISSREW}). {IEEE}, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  With the continuing rise of cloud technology hypervisors play a vital role in the performance and reliability of current services. As long-running applications, they are susceptible to software aging. Hypervisors offer so-called hypercall interfaces for communication with the hosted virtual machines. These interfaces require thorough robustness to assure performance, security, and reliability. Existing research either deals with the aging properties of hypervisors in general without considering the hypercalls or focuses on finding hypercall-related vulnerabilities. In this work, we discuss open challenges regarding hypercall interfaces. To address these challenges, we propose an extensive framework architecture to perform robustness testing on hypercall interfaces. This framework supports extensive test campaigns as well as the modeling of hypercall interfaces.

  @inproceedings{Beierlieb_2019_TowardsTestingtheSoftwareAgingBehaviorofHypervisorHypercallInterfaces, abstract = {With the continuing rise of cloud technology hypervisors play a vital role in the performance and reliability of current services. As long-running applications, they are susceptible to software aging. Hypervisors offer so-called hypercall interfaces for communication with the hosted virtual machines. These interfaces require thorough robustness to assure performance, security, and reliability. Existing research either deals with the aging properties of hypervisors in general without considering the hypercalls or focuses on finding hypercall-related vulnerabilities. In this work, we discuss open challenges regarding hypercall interfaces. To address these challenges, we propose an extensive framework architecture to perform robustness testing on hypercall interfaces. This framework supports extensive test campaigns as well as the modeling of hypercall interfaces.}, author = {Beierlieb, Lukas and Iffländer, Lukas and Milenkoski, Aleksandar and Goncalves, Charles F. and Antunes, Nuno and Kounev, Samuel}, booktitle = {2019 {IEEE} International Symposium on Software Reliability Engineering Workshops ({ISSREW})}, keywords = {t_workshop}, month = 11, organization = {{IEEE}}, title = {Towards Testing the Software Aging Behavior of Hypervisor Hypercall Interfaces}, year = 2019 }
• The Power of Composition: Abstracting a Multi-Device SDN Data Path Through a Single API. Geissler, Stefan; Herrnleben, Stefan; Bauer, Robert; Grigorjew, Alexej; Jarschel, Michael; Zinner, Thomas. In IEEE Transactions on Network and Service Management. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Software Defined Networking aims to separate network control and data plane by moving the control logic from network elements into a logically-centralized controller. Using a well-defined, unified control-channel protocol, such as OpenFlow, the controller is able to configure the forwarding behavior of data plane devices. Here, the OpenFlow protocol is translated to vendor- and device-specific instructions that, for instance, manipulate the flow table entries of a switch. In practice, SDN-enabled switches often feature different hardware capabilities and configurations with respect to the number of flow tables, their implementation, and which kind of data plane features they support. This leads to device heterogeneity within the SDN landscape, thereby obstructing the increased scalability and flexibility promised by the SDN paradigm. To overcome this challenge we propose TableVisor, a transparent proxy-layer for the SDN control channel that enables the flexible abstraction of heterogeneous data plane devices into a single emulated data plane switch. In this paper, we extend our previous work by introducing features to integrate modern P4 devices into an existing SDN environment and perform a detailed performance evaluation to quantify the overhead induced by our approach.

  @inproceedings{info3-article-2019-11, abstract = {Software Defined Networking aims to separate network control and data plane by moving the control logic from network elements into a logically-centralized controller. Using a well-defined, unified control-channel protocol, such as OpenFlow, the controller is able to configure the forwarding behavior of data plane devices. Here, the OpenFlow protocol is translated to vendor- and device-specific instructions that, for instance, manipulate the flow table entries of a switch. In practice, SDN-enabled switches often feature different hardware capabilities and configurations with respect to the number of flow tables, their implementation, and which kind of data plane features they support. This leads to device heterogeneity within the SDN landscape, thereby obstructing the increased scalability and flexibility promised by the SDN paradigm. To overcome this challenge we propose TableVisor, a transparent proxy-layer for the SDN control channel that enables the flexible abstraction of heterogeneous data plane devices into a single emulated data plane switch. In this paper, we extend our previous work by introducing features to integrate modern P4 devices into an existing SDN environment and perform a detailed performance evaluation to quantify the overhead induced by our approach.}, author = {Geissler, Stefan and Herrnleben, Stefan and Bauer, Robert and Grigorjew, Alexej and Jarschel, Michael and Zinner, Thomas}, journal = {IEEE Transactions on Network and Service Management}, keywords = {sdn}, month = 11, title = {The Power of Composition: Abstracting a Multi-Device SDN Data Path Through a Single API}, year = 2019 }
• Sick Moves! Motion Parameters as Indicators of Simulator Sickness. Feigl, Tobias; Roth, Daniel; Gradl, Stefan; Wirth, Markus Gerhard; Philippsen, Michael; Latoschik, Marc Erich; Eskofier, Bjoern; Mutschler, Christopher. In IEEE Transactions on Visualization and Computer Graphics (TVCG), 25(11), pp. 3146–3157. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  We explore motion parameters, more specifically gait parameters, asan objective indicator to assess simulator sickness in Virtual Reality(VR). We discuss the potential relationships between simulator sick-ness, immersion, and presence. We used two different camera pose(position and orientation) estimation methods for the evaluation ofmotion tasks in a large-scale VR environment: a simple model andan optimized model that allows for a more accurate and natural map-ping of human senses. Participants performed multiple motion tasks(walking, balancing, running) in three conditions: a physical realitybaseline condition, a VR condition with the simple model, and a VRcondition with the optimized model. We compared these conditionswith regard to the resulting sickness and gait, as well as the perceivedpresence in the VR conditions. The subjective measures confirmedthat the optimized pose estimation model reduces simulator sick-ness and increases the perceived presence. The results further showthat both models affect the gait parameters and simulator sickness,which is why we further investigated a classification approach thatdeals with non-linear correlation dependencies between gait param-eters and simulator sickness. We argue that our approach could beused to assess and predict simulator sickness based on human gaitparameters and we provide implications for future research

  @article{feigl2019toappearmoves, abstract = {We explore motion parameters, more specifically gait parameters, asan objective indicator to assess simulator sickness in Virtual Reality(VR). We discuss the potential relationships between simulator sick-ness, immersion, and presence. We used two different camera pose(position and orientation) estimation methods for the evaluation ofmotion tasks in a large-scale VR environment: a simple model andan optimized model that allows for a more accurate and natural map-ping of human senses. Participants performed multiple motion tasks(walking, balancing, running) in three conditions: a physical realitybaseline condition, a VR condition with the simple model, and a VRcondition with the optimized model. We compared these conditionswith regard to the resulting sickness and gait, as well as the perceivedpresence in the VR conditions. The subjective measures confirmedthat the optimized pose estimation model reduces simulator sick-ness and increases the perceived presence. The results further showthat both models affect the gait parameters and simulator sickness,which is why we further investigated a classification approach thatdeals with non-linear correlation dependencies between gait param-eters and simulator sickness. We argue that our approach could beused to assess and predict simulator sickness based on human gaitparameters and we provide implications for future research}, author = {Feigl, Tobias and Roth, Daniel and Gradl, Stefan and Wirth, Markus Gerhard and Philippsen, Michael and Latoschik, Marc Erich and Eskofier, Bjoern and Mutschler, Christopher}, journal = {IEEE Transactions on Visualization and Computer Graphics (TVCG)}, keywords = {droth}, month = 11, number = 11, pages = {3146-3157}, title = {Sick Moves! Motion Parameters as Indicators of Simulator Sickness}, volume = 25, year = 2019 }
• QoE Analysis of Spotify Audio Streaming and App Browsing. Schwind, Anika; Haberzettl, Lorenz; Wamser, Florian; Hoßfeld, Tobias. In 4th Internet-QoE Workshop: QoE-based Analysis and Management of Data Communication Networks (Internet-QoE’19). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Spotify is the most-listened audio streaming provider in 2019 with 217 million active users per month. Providers are therefore interested in the quality and functionality of Spotify in order to provide their users with the best possible streaming quality. While video streaming services such as Netflix and their streaming approach have been extensively explored in previous research, audio streaming services like Spotify and their corresponding behavior at certain network conditions have not been considered in detail yet. In this paper, we perform a QoE analysis under various network conditions and examine the app browsing performance of the audio streaming platform Spotify using its native Android mobile application. We have developed a measurement tool that emulates a user listening to audio through Spotify. While streaming, application and network layer parameters are captured that have a high correlation to the user’s QoE. The paper shows a baseline scenario including the streaming of a single song as well as playlist streaming behavior. Next, the effect of interruptions on the streaming behavior is evaluated and finally, the influence of network impairments on QoE key performance indicators such as initial delay is shown.

  @inproceedings{info3-inproceedings-2019-27, abstract = {Spotify is the most-listened audio streaming provider in 2019 with 217 million active users per month. Providers are therefore interested in the quality and functionality of Spotify in order to provide their users with the best possible streaming quality. While video streaming services such as Netflix and their streaming approach have been extensively explored in previous research, audio streaming services like Spotify and their corresponding behavior at certain network conditions have not been considered in detail yet. In this paper, we perform a QoE analysis under various network conditions and examine the app browsing performance of the audio streaming platform Spotify using its native Android mobile application. We have developed a measurement tool that emulates a user listening to audio through Spotify. While streaming, application and network layer parameters are captured that have a high correlation to the user’s QoE. The paper shows a baseline scenario including the streaming of a single song as well as playlist streaming behavior. Next, the effect of interruptions on the streaming behavior is evaluated and finally, the influence of network impairments on QoE key performance indicators such as initial delay is shown.}, author = {Schwind, Anika and Haberzettl, Lorenz and Wamser, Florian and Hoßfeld, Tobias}, booktitle = {4th Internet-QoE Workshop: QoE-based Analysis and Management of Data Communication Networks (Internet-QoE'19)}, keywords = {can}, month = 10, title = {QoE Analysis of Spotify Audio Streaming and App Browsing}, year = 2019 }
• I See What you See: Real Time Prediction of Video Quality from Encrypted Streaming Traffic. Wassermann, Sarah; Seufert, Michael; Casas, Pedro; Li, Gang; Kuang, Li. In 4th Workshop on QoE-based Analysis and Management of Data Communication Networks (Internet-QoE). Los Cabos, Mexico, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  We address the problem of real-time QoE monitoring of HAS, from the ISP perspective, focusing in particular on videoresolution analysis. Given the wide adoption of end-to-end encryption, we resort to machine-learning models to predict different video resolution levels in a fine-grained scale, ranging from 144p to 1080p resolution, using as input only packet-level data. The proposed measurement system performs predictions in real time, during the course of an ongoing video-streaming session, with a time granularity as small as one second. We consider the particular case of YouTube video streaming. Empirical evaluations on a large and heterogeneous corpus of YouTube measurements demonstrate that the proposed system can predict video resolution with very high accuracy, and in real time. Different from state of the art, the prediction task is not bound to coarse-grained video quality classes and does not require chunk-detection approaches for feature extraction.

  @inproceedings{info3-inproceedings-2019-28, abstract = {We address the problem of real-time QoE monitoring of HAS, from the ISP perspective, focusing in particular on videoresolution analysis. Given the wide adoption of end-to-end encryption, we resort to machine-learning models to predict different video resolution levels in a fine-grained scale, ranging from 144p to 1080p resolution, using as input only packet-level data. The proposed measurement system performs predictions in real time, during the course of an ongoing video-streaming session, with a time granularity as small as one second. We consider the particular case of YouTube video streaming. Empirical evaluations on a large and heterogeneous corpus of YouTube measurements demonstrate that the proposed system can predict video resolution with very high accuracy, and in real time. Different from state of the art, the prediction task is not bound to coarse-grained video quality classes and does not require chunk-detection approaches for feature extraction.}, address = {Los Cabos, Mexico}, author = {Wassermann, Sarah and Seufert, Michael and Casas, Pedro and Li, Gang and Kuang, Li}, booktitle = {4th Workshop on QoE-based Analysis and Management of Data Communication Networks (Internet-QoE)}, keywords = {ua-net}, month = 10, title = {I See What you See: Real Time Prediction of Video Quality from Encrypted Streaming Traffic}, year = 2019 }
• Traffic Measurement Study on Video Streaming with the Amazon Echo Show. Loh, Frank; Vomhoff, Viktoria; Wamser, Florian; Metzger, Florian; Hoßfeld, Tobias. In 4th Internet-QoE Workshop: QoE-based Analysis and Management of Data Communication Networks. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  The Amazon Echo Show is one of the most widely used smart speakers with the ability to stream video. Due to its popularity, the traffc profiles of such devices are of interest to network operators and providers. This work presents a measurement study of the Amazon Echo Show in terms of network traffc and streaming behavior. More than 470 hours of streaming data are collected and analyzed at network layer. Based on this, streaming quality is derived at application layer. The study quantifies the traffc and shows that streaming with the Amazon Echo Show is comparable to streaming with a native web browser, but in a more conservative way.

  @inproceedings{info3-inproceedings-2019-26, abstract = {The Amazon Echo Show is one of the most widely used smart speakers with the ability to stream video. Due to its popularity, the traffc profiles of such devices are of interest to network operators and providers. This work presents a measurement study of the Amazon Echo Show in terms of network traffc and streaming behavior. More than 470 hours of streaming data are collected and analyzed at network layer. Based on this, streaming quality is derived at application layer. The study quantifies the traffc and shows that streaming with the Amazon Echo Show is comparable to streaming with a native web browser, but in a more conservative way.}, author = {Loh, Frank and Vomhoff, Viktoria and Wamser, Florian and Metzger, Florian and Hoßfeld, Tobias}, booktitle = {4th Internet-QoE Workshop: QoE-based Analysis and Management of Data Communication Networks}, keywords = {can}, month = 10, title = {Traffic Measurement Study on Video Streaming with the Amazon Echo Show}, year = 2019 }
• ViCrypt: Real-time, Fine-grained Prediction of Video Quality from Encrypted Streaming Traffic. Wassermann, Sarah; Seufert, Michael; Casas, Pedro; Li, Gang; Kuang, Li. Amsterdam, The Netherlands, 2019, October.
  • [ BibTeX ]
  @misc{info3-poster-2019-2, address = {Amsterdam, The Netherlands}, author = {Wassermann, Sarah and Seufert, Michael and Casas, Pedro and Li, Gang and Kuang, Li}, booktitle = {19th ACM Internet Measurement Conference (IMC)}, keywords = {ucn}, month = 10, title = {ViCrypt: Real-time, Fine-grained Prediction of Video Quality from Encrypted Streaming Traffic}, year = 2019 }
• Contributions to TF "Managing Web & Cloud QoE". Moldovan, Christian. 13th Qualinet General Meeting, Berlin, Germany, 2019, June 4.
  • [ BibTeX ]
  @presentation{info3-presentation-2019-6, address = {13th Qualinet General Meeting, Berlin, Germany}, author = {Moldovan, Christian}, keywords = {myown}, month = {06}, title = {Contributions to TF "Managing Web & Cloud QoE"}, year = 2019 }
• Fundamental Advantages of Considering Quality of Experience Distributions over Mean Opinion Scores. Seufert, Michael. In 11th International Conference on Quality of Multimedia Experience (QoMEX). Berlin, Germany, 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-14, address = {Berlin, Germany}, author = {Seufert, Michael}, booktitle = {11th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ua-net}, month = {06}, title = {Fundamental Advantages of Considering Quality of Experience Distributions over Mean Opinion Scores}, year = 2019 }
• BBGDASH: A Max-Min Bounded Bitrate Guidance for SDN Enabled Adaptive Video Streaming. Alissa, Ali; Bentalab, Abdelhak; Zinner, Thomas; Ghita, Bogdan; Mkwawa, Is-Haka. In 22nd Conference on Innovation in Clouds, Internet and Networks and Workshops (ICIN. 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-2, author = {Alissa, Ali and Bentalab, Abdelhak and Zinner, Thomas and Ghita, Bogdan and Mkwawa, Is-Haka}, booktitle = {22nd Conference on Innovation in Clouds, Internet and Networks and Workshops (ICIN}, keywords = {myown}, month = {02}, title = {BBGDASH: A Max-Min Bounded Bitrate Guidance for SDN Enabled Adaptive Video Streaming}, year = 2019 }
• Gray, Nicholas, et al. "Highlighting the Gap Between Expected and Actual Behavior in P4-enabled Networks. Gray, Nicholas; Grigorjew, Alexej; Hoßfeld, Tobias; Shukla, Apoorv; Zinner, Thomas. In IFIP/IEEE Symposium on Integrated Network and Service Management (IM). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Modern networks increasingly rely on Software-defined Networking (SDN) and Network Function Virtualization (NFV) to augment their flexibility in high load scenarios. To further enhance the performance, a part of the functionality is often offloaded to forwarding devices, which are used as hardware accelerators and are configured by high level programming languages such as P4. However, hardware vendors use sophisticated technologies to implement these standards, which need to be understood by the programmer to avoid unintended behavior. In this demonstration we highlight the severe consequences of only relying on the network programming language when ignoring the device-specific limitations. We show this by the example of a Denial of Service attack against a P4-enabled SmartNIC. Finally, we discuss possible mitigations to this attack and stress the importance of an overall understanding of the entire system.

  @inproceedings{info3-demo-2019-1, abstract = {Modern networks increasingly rely on Software-defined Networking (SDN) and Network Function Virtualization (NFV) to augment their flexibility in high load scenarios. To further enhance the performance, a part of the functionality is often offloaded to forwarding devices, which are used as hardware accelerators and are configured by high level programming languages such as P4. However, hardware vendors use sophisticated technologies to implement these standards, which need to be understood by the programmer to avoid unintended behavior. In this demonstration we highlight the severe consequences of only relying on the network programming language when ignoring the device-specific limitations. We show this by the example of a Denial of Service attack against a P4-enabled SmartNIC. Finally, we discuss possible mitigations to this attack and stress the importance of an overall understanding of the entire system.}, author = {Gray, Nicholas and Grigorjew, Alexej and Hoßfeld, Tobias and Shukla, Apoorv and Zinner, Thomas}, booktitle = {IFIP/IEEE Symposium on Integrated Network and Service Management (IM)}, keywords = {sardine}, month = {03}, title = {Gray, Nicholas, et al. "Highlighting the Gap Between Expected and Actual Behavior in P4-enabled Networks}, year = 2019 }
• {Chameleon: A Hybrid, Proactive Auto-Scaling Mechanism on a Level-Playing Field}. Bauer, Andr{é}; Herbst, Nikolas; Spinner, Simon; Ali-Eldin, Ahmed; Kounev, Samuel. In IEEE Transactions on Parallel and Distributed Systems, 30(4), pp. 800–813. IEEE, 2019.
  • [ BibTeX ]
  @article{BaHeSpAEKo2019-TPDS-ChameleonAutoscaler, author = {Bauer, Andr{\'e} and Herbst, Nikolas and Spinner, Simon and Ali-Eldin, Ahmed and Kounev, Samuel}, journal = {IEEE Transactions on Parallel and Distributed Systems}, keywords = {Self-adaptive-systems}, month = {04}, number = 4, pages = {800–813}, publisher = {IEEE}, title = {{Chameleon: A Hybrid, Proactive Auto-Scaling Mechanism on a Level-Playing Field}}, volume = 30, year = 2019 }
• {Chameleon: A Hybrid, Proactive Auto-Scaling Mechanism on a Level-Playing Field}. Bauer, Andr{é}; Herbst, Nikolas; Spinner, Simon; Ali-Eldin, Ahmed; Kounev, Samuel. In IEEE Transactions on Parallel and Distributed Systems, 30(4), pp. 800–813. IEEE, 2019.
  • [ BibTeX ]
  @article{BaHeSpAEKo2019-TPDS-ChameleonAutoscaler, author = {Bauer, Andr{\'e} and Herbst, Nikolas and Spinner, Simon and Ali-Eldin, Ahmed and Kounev, Samuel}, journal = {IEEE Transactions on Parallel and Distributed Systems}, keywords = {Self-adaptive-systems}, month = {04}, number = 4, pages = {800–813}, publisher = {IEEE}, title = {{Chameleon: A Hybrid, Proactive Auto-Scaling Mechanism on a Level-Playing Field}}, volume = 30, year = 2019 }
• Features that Matter: Feature Selection for On-line Stalling Prediction in Encrypted Video Streaming. Seufert, Michael; Casas, Pedro; Wehner, Nikolas; Li, Gang; Kuang, Li. In 2nd International Workshop on Network Intelligence (NI). Paris, France, 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-11, address = {Paris, France}, author = {Seufert, Michael and Casas, Pedro and Wehner, Nikolas and Li, Gang and Kuang, Li}, booktitle = {2nd International Workshop on Network Intelligence (NI)}, keywords = {net-man}, month = {04}, title = {Features that Matter: Feature Selection for On-line Stalling Prediction in Encrypted Video Streaming}, year = 2019 }
• {SPEC Research Group Newsletter, vol. 2 no. 4}. Kounev, Samuel; van Hoorn, Andre; Bauer, Andr{é}; Herbst, Nikolas. 2019, April.
  • [ BibTeX ]
  • [ URL ]
  @misc{SPEC-RG-NEWSLETTER-8, author = {Kounev, Samuel and van Hoorn, Andre and Bauer, Andr{\'e} and Herbst, Nikolas}, keywords = {se2}, month = {04}, note = {Published by Standard Performance Evaluation Corporation (SPEC)}, title = {{SPEC Research Group Newsletter, vol. 2 no. 4}}, year = 2019 }
• {Methodological Principles for Reproducible Performance Evaluation in Cloud Computing - A SPEC Research Technical Report}. Technical Report (SPEC-RG-2019-04), . Papadopoulos, Alessandro Vittorio; Versluis, Laurens; Bauer, Andr{é}; Herbst, Nikolas; von Kistowski, J{ó}akim; Ali-Eldin, Ahmed; Abad, Cristina; Amaral, J. Nelson; Tuma, Petr; Iosup, Alexandru. SPEC Research Group --- Cloud Working Group, Standard Performance Evaluation Corporation (SPEC), 2019.
  • [ BibTeX ]
  • [ URL ]
  @techreport{PaVeBaHeKiEAAbAmTuIo2019-SPEC-CloudPerformance, author = {Papadopoulos, Alessandro Vittorio and Versluis, Laurens and Bauer, Andr{\'e} and Herbst, Nikolas and von Kistowski, J{\'o}akim and Ali-Eldin, Ahmed and Abad, Cristina and Amaral, J. Nelson and Tuma, Petr and Iosup, Alexandru}, institution = {SPEC Research Group — Cloud Working Group, Standard Performance Evaluation Corporation (SPEC)}, keywords = {SPEC}, month = {04}, number = {SPEC-RG-2019-04}, title = {{Methodological Principles for Reproducible Performance Evaluation in Cloud Computing - A SPEC Research Technical Report}}, year = 2019 }
• {A Concept for an Adaptive Communication Middleware for Car-2-Cloud Applications}. Herrnleben, Stefan. 2019, April.
  • [ BibTeX ]
  @misc{He2019-SelPhyS-Car2Cloud, author = {Herrnleben, Stefan}, howpublished = {Talk at Workshop on Self-Awareness in Cyber-Physical Systems 2019}, keywords = {t_workshop}, month = {04}, title = {{A Concept for an Adaptive Communication Middleware for Car-2-Cloud Applications}}, year = 2019 }
• Modeling of Aggregated IoT Traffic and Its Application to an IoT Cloud. Metzger, Florian; Hoßfeld, Tobias; Bauer, André; Kounev, Samuel; Heegaard, Poul E. In Proceedings of the IEEE, 107(4), pp. 679–694. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  As the Internet of Things (IoT) continues to gain traction in telecommunication networks, a very large number of devices are expected to be connected and used in the near future. In order to appropriately plan and dimension the network, as well as the back-end cloud systems and the resulting signaling load, traffic models are employed. These models are designed to accurately capture and predict the properties of IoT traffic in a concise manner. To achieve this, Poisson process approximations, based on the Palm–Khintchine theorem, have often been used in the past. Due to the scale (and the difference in scales in various IoT networks) of the modeled systems, the fidelity of this approximation is crucial, as, in practice, it is very challenging to accurately measure or simulate large-scale IoT deployments. The main goal of this paper is to understand the level of accuracy of the Poisson approximation model. To this end, we first survey both common IoT network properties and network scales as well as traffic types. Second, we explain and discuss the Palm–Khintiche theorem, how it is applied to the problem, and which inaccuracies can occur when using it. Based on this, we derive guidelines as to when a Poisson process can be assumed for aggregated periodic IoT traffic. Finally, we evaluate our approach in the context of an IoT cloud scaler use case.

  @article{info3-article-2019-3, abstract = {As the Internet of Things (IoT) continues to gain traction in telecommunication networks, a very large number of devices are expected to be connected and used in the near future. In order to appropriately plan and dimension the network, as well as the back-end cloud systems and the resulting signaling load, traffic models are employed. These models are designed to accurately capture and predict the properties of IoT traffic in a concise manner. To achieve this, Poisson process approximations, based on the Palm–Khintchine theorem, have often been used in the past. Due to the scale (and the difference in scales in various IoT networks) of the modeled systems, the fidelity of this approximation is crucial, as, in practice, it is very challenging to accurately measure or simulate large-scale IoT deployments. The main goal of this paper is to understand the level of accuracy of the Poisson approximation model. To this end, we first survey both common IoT network properties and network scales as well as traffic types. Second, we explain and discuss the Palm–Khintiche theorem, how it is applied to the problem, and which inaccuracies can occur when using it. Based on this, we derive guidelines as to when a Poisson process can be assumed for aggregated periodic IoT traffic. Finally, we evaluate our approach in the context of an IoT cloud scaler use case.}, author = {Metzger, Florian and Hoßfeld, Tobias and Bauer, André and Kounev, Samuel and Heegaard, Poul E.}, journal = {Proceedings of the IEEE}, keywords = {doi:10.1109/JPROC.2019.2901578}, month = {04}, number = 4, pages = {679-694}, title = {Modeling of Aggregated IoT Traffic and Its Application to an IoT Cloud}, volume = 107, year = 2019 }
• Energy-Efficient Adaptation Logic for HTTP Streaming in Mobile Networks. Moldovan, Christian. 2019 International Conference on Networked Systems (NetSys), Garching, Germany, 2019, March 20.
  • [ BibTeX ]
  @presentation{info3-presentation-2019-7, address = {2019 International Conference on Networked Systems (NetSys), Garching, Germany}, author = {Moldovan, Christian}, keywords = {myown}, month = {03}, title = {Energy-Efficient Adaptation Logic for HTTP Streaming in Mobile Networks}, year = 2019 }
• Quality of Experience and Access Network Traffic Management of HTTP Adaptive Video Streaming. Seufert, Michael. International Conference on Networked Systems (NetSys), KuVS Dissertation Award 2018, Munich, Germany, 2019, March 20.
  • [ BibTeX ]
  @presentation{info3-presentation-2019-2, address = {International Conference on Networked Systems (NetSys), KuVS Dissertation Award 2018, Munich, Germany}, author = {Seufert, Michael}, keywords = {myown}, month = {03}, title = {Quality of Experience and Access Network Traffic Management of HTTP Adaptive Video Streaming}, year = 2019 }
• {Integrating Statistical Response Time Models in Architectural Performance Models}. Eismann, Simon; Grohmann, Johannes; Walter, J{ü}rgen; von Kistowski, J{ó}akim; Kounev, Samuel. In Proceedings of the 2019 IEEE International Conference on Software Architecture (ICSA), pp. 71–80. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Performance predictions enable software architects to optimize the performance of a software system early in the development cycle. Architectural performance models and statistical response time models are commonly used to derive these performance predictions. However, both methods have significant downsides: Statistical response time models can only predict scenarios for which training data is available, making the prediction of previously unseen system configurations infeasible. In contrast, the time required to simulate an architectural performance model increases exponentially with both system size and level of modeling detail, making the analysis of large, detailed models challenging. Existing approaches use statistical response time models in architectural performance models to avoid modeling subsystems that are difficult or time-consuming to model, yet they do not consider simulation time. In this paper, we propose to model software systems using classical queuing theory and statistical response time models in parallel. This approach allows users to tailor the model for each analysis run, based on the performed adaptations and the requested performance metrics. Our approach enables faster model solution compared to traditional performance models while retaining their ability to predict previously unseen scenarios. In our experiments we observed speedups of up to 94.8%, making the analysis of much larger and more detailed systems feasible.

  @inproceedings{EiGrWaKiKo2019-ICSA-Integrating, abstract = {Performance predictions enable software architects to optimize the performance of a software system early in the development cycle. Architectural performance models and statistical response time models are commonly used to derive these performance predictions. However, both methods have significant downsides: Statistical response time models can only predict scenarios for which training data is available, making the prediction of previously unseen system configurations infeasible. In contrast, the time required to simulate an architectural performance model increases exponentially with both system size and level of modeling detail, making the analysis of large, detailed models challenging. Existing approaches use statistical response time models in architectural performance models to avoid modeling subsystems that are difficult or time-consuming to model, yet they do not consider simulation time. In this paper, we propose to model software systems using classical queuing theory and statistical response time models in parallel. This approach allows users to tailor the model for each analysis run, based on the performed adaptations and the requested performance metrics. Our approach enables faster model solution compared to traditional performance models while retaining their ability to predict previously unseen scenarios. In our experiments we observed speedups of up to 94.8%, making the analysis of much larger and more detailed systems feasible.}, author = {Eismann, Simon and Grohmann, Johannes and Walter, J{\"u}rgen and von Kistowski, J{\'o}akim and Kounev, Samuel}, booktitle = {Proceedings of the 2019 IEEE International Conference on Software Architecture (ICSA)}, keywords = {PRISMA}, month = {03}, note = {Acceptance Rate: 21,9\% (21/96)}, pages = {71–80}, publisher = {IEEE}, title = {{Integrating Statistical Response Time Models in Architectural Performance Models}}, year = 2019 }
• {Modeling of Aggregated IoT Traffic and Its Application to an IoT Cloud}. Metzger, Florian; Hoßfeld, Tobias; Bauer, Andr{é}; Kounev, Samuel; Heegaard, Poul. E. In Proceedings of the IEEE, 107(4), pp. 679–694. 2019.
  • [ BibTeX ]
  @article{MeHoBaKoHe2019-PIEEE-IoTTraffic, author = {Metzger, Florian and Ho{\ss}feld, Tobias and Bauer, Andr{\'e} and Kounev, Samuel and Heegaard, Poul. E.}, journal = {Proceedings of the IEEE}, keywords = {t_journalmagazine}, month = {04}, number = 4, pages = {679-694}, title = {{Modeling of Aggregated IoT Traffic and Its Application to an IoT Cloud}}, volume = 107, year = 2019 }
• Energy-Efficient Adaptation Logic for HTTP Streaming in Mobile Networks. Moldovan, Christian; Wamser, Florian; Hoßfeld, Tobias. In 2019 International Conference on Networked Systems (NetSys). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  The requirements for video streaming have changed drastically during the past years. In today's Internet, high definition resolutions are considered default for videos, even in mobile settings, and with 4G penetration reaching 90 percent in the US, this no longer poses a big problem. However, while mobile bandwidth has increased, the battery life time of mobile devices has not increased significantly. Furthermore, current data plans are still not large enough to regularly stream movies during the commute. Users still resort to downloading media before travel. In this paper we propose a new HTTP adaptive streaming algorithm that delivers videos in high quality while avoiding stalling events, schedules the download of video segments so that a energy conserving idle state is often reached and keeps the buffer low at points in the video where many viewers abandon the video to save data. While most adaptive streaming algorithms optimize quality and stalling, this is the first attempt to use an adaptive streaming algorithm to reduce energy consumption. Since video streaming providers mostly care about the Quality of Experience when watching videos, energy efficiency is left to the device manufacturers. Therefore, both parties have little incentive to cooperate in this regard. But on the Internet of tomorrow, where most videos are watched on mobile devices, energy efficiency and the Quality of Experience must go hand in hand.

  @inproceedings{info3-inproceedings-2019-9, abstract = {The requirements for video streaming have changed drastically during the past years. In today's Internet, high definition resolutions are considered default for videos, even in mobile settings, and with 4G penetration reaching 90 percent in the US, this no longer poses a big problem. However, while mobile bandwidth has increased, the battery life time of mobile devices has not increased significantly. Furthermore, current data plans are still not large enough to regularly stream movies during the commute. Users still resort to downloading media before travel. In this paper we propose a new HTTP adaptive streaming algorithm that delivers videos in high quality while avoiding stalling events, schedules the download of video segments so that a energy conserving idle state is often reached and keeps the buffer low at points in the video where many viewers abandon the video to save data. While most adaptive streaming algorithms optimize quality and stalling, this is the first attempt to use an adaptive streaming algorithm to reduce energy consumption. Since video streaming providers mostly care about the Quality of Experience when watching videos, energy efficiency is left to the device manufacturers. Therefore, both parties have little incentive to cooperate in this regard. But on the Internet of tomorrow, where most videos are watched on mobile devices, energy efficiency and the Quality of Experience must go hand in hand.}, author = {Moldovan, Christian and Wamser, Florian and Hoßfeld, Tobias}, booktitle = {2019 International Conference on Networked Systems (NetSys)}, keywords = {energy-efficiency}, month = {03}, title = {Energy-Efficient Adaptation Logic for HTTP Streaming in Mobile Networks}, year = 2019 }
• Web Performance Pitfalls. Enghardt, Theresa; Zinner, Thomas; Feldmann, Anja. In Passive and Active Measurement Conference (PAM). 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-1, author = {Enghardt, Theresa and Zinner, Thomas and Feldmann, Anja}, booktitle = {Passive and Active Measurement Conference (PAM)}, keywords = {myown}, month = {03}, title = {Web Performance Pitfalls}, year = 2019 }
• KOMon - Kernel-based Online Monitoring of VNF Packet Processing Times. Geissler, Stefan; Lange, Stanislav; Wamser, Florian; Zinner, Thomas; Hoßfeld, Tobias. In 2019 International Conference on Networked Systems (NetSys), Best Paper Award. 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-5, author = {Geissler, Stefan and Lange, Stanislav and Wamser, Florian and Zinner, Thomas and Hoßfeld, Tobias}, booktitle = {2019 International Conference on Networked Systems (NetSys), Best Paper Award}, keywords = {sendate}, month = {03}, title = {KOMon - Kernel-based Online Monitoring of VNF Packet Processing Times}, year = 2019 }
• {Integrating Statistical Response Time Models in Architectural Performance Models}. Eismann, Simon; Grohmann, Johannes; Walter, J{ü}rgen; von Kistowski, J{ó}akim; Kounev, Samuel. In Proceedings of the 2019 IEEE International Conference on Software Architecture (ICSA), pp. 71–80. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Performance predictions enable software architects to optimize the performance of a software system early in the development cycle. Architectural performance models and statistical response time models are commonly used to derive these performance predictions. However, both methods have significant downsides: Statistical response time models can only predict scenarios for which training data is available, making the prediction of previously unseen system configurations infeasible. In contrast, the time required to simulate an architectural performance model increases exponentially with both system size and level of modeling detail, making the analysis of large, detailed models challenging. Existing approaches use statistical response time models in architectural performance models to avoid modeling subsystems that are difficult or time-consuming to model, yet they do not consider simulation time. In this paper, we propose to model software systems using classical queuing theory and statistical response time models in parallel. This approach allows users to tailor the model for each analysis run, based on the performed adaptations and the requested performance metrics. Our approach enables faster model solution compared to traditional performance models while retaining their ability to predict previously unseen scenarios. In our experiments we observed speedups of up to 94.8%, making the analysis of much larger and more detailed systems feasible.

  @inproceedings{EiGrWaKiKo2019-ICSA-Integrating, abstract = {Performance predictions enable software architects to optimize the performance of a software system early in the development cycle. Architectural performance models and statistical response time models are commonly used to derive these performance predictions. However, both methods have significant downsides: Statistical response time models can only predict scenarios for which training data is available, making the prediction of previously unseen system configurations infeasible. In contrast, the time required to simulate an architectural performance model increases exponentially with both system size and level of modeling detail, making the analysis of large, detailed models challenging. Existing approaches use statistical response time models in architectural performance models to avoid modeling subsystems that are difficult or time-consuming to model, yet they do not consider simulation time. In this paper, we propose to model software systems using classical queuing theory and statistical response time models in parallel. This approach allows users to tailor the model for each analysis run, based on the performed adaptations and the requested performance metrics. Our approach enables faster model solution compared to traditional performance models while retaining their ability to predict previously unseen scenarios. In our experiments we observed speedups of up to 94.8%, making the analysis of much larger and more detailed systems feasible.}, author = {Eismann, Simon and Grohmann, Johannes and Walter, J{\"u}rgen and von Kistowski, J{\'o}akim and Kounev, Samuel}, booktitle = {Proceedings of the 2019 IEEE International Conference on Software Architecture (ICSA)}, keywords = {PRISMA}, month = {03}, note = {Acceptance Rate: 21,9\% (21/96)}, pages = {71–80}, publisher = {IEEE}, title = {{Integrating Statistical Response Time Models in Architectural Performance Models}}, year = 2019 }
• A Simulation of Asynchronous Traffic Shapers in Switched Ethernet Networks. Grigorjew, Alexej; Metzger, Florian; Hoßfeld, Tobias; Specht, Johannes. In Workshop for Advanced Communication Networks for Industrial Applications. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  As the requirements of real-time networking in- crease, the IEEE Time-Sensitive Networking (TSN) task group is working on new standards for high bandwidth and low latency Ethernet switching. In particular, the upcoming P802.1Qcr standard features Asynchronous Traffic Shaping (ATS), which is a promising approach for real-time networks with high dynamics and critical safety requirements. Additionally, parallel concepts such as frame preemption can be used to reduce delays even further. This work presents a discrete event simulation framework that can analyze the performance of these concepts. It implements frame preemption and multiple shaping algorithms, while recording latency and queue utilization statistics at the switches. In addition, an evaluation of a linear topology with four switches is performed under high link utilization, which demonstrates the benefit of the above mechanisms compared to regular Ethernet switching.

  @inproceedings{info3-inproceedings-2019-16, abstract = {As the requirements of real-time networking in- crease, the IEEE Time-Sensitive Networking (TSN) task group is working on new standards for high bandwidth and low latency Ethernet switching. In particular, the upcoming P802.1Qcr standard features Asynchronous Traffic Shaping (ATS), which is a promising approach for real-time networks with high dynamics and critical safety requirements. Additionally, parallel concepts such as frame preemption can be used to reduce delays even further. This work presents a discrete event simulation framework that can analyze the performance of these concepts. It implements frame preemption and multiple shaping algorithms, while recording latency and queue utilization statistics at the switches. In addition, an evaluation of a linear topology with four switches is performed under high link utilization, which demonstrates the benefit of the above mechanisms compared to regular Ethernet switching.}, author = {Grigorjew, Alexej and Metzger, Florian and Hoßfeld, Tobias and Specht, Johannes}, booktitle = {Workshop for Advanced Communication Networks for Industrial Applications}, keywords = {fullstack}, month = {03}, title = {A Simulation of Asynchronous Traffic Shapers in Switched Ethernet Networks}, year = 2019 }
• QUICker or not? - an Empirical Analysis of QUIC vs TCP for Video Streaming QoE Provisioning. Seufert, Michael. 3rd International Workshop on Quality of Experience Management (QoE-Management), Paris, France, 2019, February 18.
  • [ BibTeX ]
  @presentation{info3-presentation-2019-1, address = {3rd International Workshop on Quality of Experience Management (QoE-Management), Paris, France}, author = {Seufert, Michael}, keywords = {myown}, month = {02}, title = {QUICker or not? - an Empirical Analysis of QUIC vs TCP for Video Streaming QoE Provisioning}, year = 2019 }
• QUICker or not? - an Empirical Analysis of QUIC vs TCP for Video Streaming QoE Provisioning. Seufert, Michael; Schatz, Raimund; Wehner, Nikolas; Casas, Pedro. In 3rd International Workshop on Quality of Experience Management (QoE-Management). Paris, France, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  The introduction of the QUIC (Quick UDP Internet Connections) transport protocol by Google aimed to improve the Quality of Experience (QoE) with web services compared to the prevailing Transport Control Protocol (TCP). Nowadays, QUIC has become the default protocol to communicate between the Google Chrome browser and Google servers and accounts for an increasing share of the Internet traffic. This work investigates whether the promised QoE benefits of QUIC are indeed noticeable for end users or not. A measurement study was conducted for YouTube video streaming in two mobile and two fixed access networks, in which a defined set of videos was streamed back-to-back with QUIC and TCP in randomized order. QoE factors of video streaming (such as initial delay, the visual quality of the video, and stalling) were compared statistically to find significant differences between the streaming over QUIC and the streaming over TCP. Surprisingly, no evidence for any QoE improvement of QUIC over TCP in the context of YouTube streaming could be found.

  @inproceedings{info3-inproceedings-2019-7, abstract = {The introduction of the QUIC (Quick UDP Internet Connections) transport protocol by Google aimed to improve the Quality of Experience (QoE) with web services compared to the prevailing Transport Control Protocol (TCP). Nowadays, QUIC has become the default protocol to communicate between the Google Chrome browser and Google servers and accounts for an increasing share of the Internet traffic. This work investigates whether the promised QoE benefits of QUIC are indeed noticeable for end users or not. A measurement study was conducted for YouTube video streaming in two mobile and two fixed access networks, in which a defined set of videos was streamed back-to-back with QUIC and TCP in randomized order. QoE factors of video streaming (such as initial delay, the visual quality of the video, and stalling) were compared statistically to find significant differences between the streaming over QUIC and the streaming over TCP. Surprisingly, no evidence for any QoE improvement of QUIC over TCP in the context of YouTube streaming could be found.}, address = {Paris, France}, author = {Seufert, Michael and Schatz, Raimund and Wehner, Nikolas and Casas, Pedro}, booktitle = {3rd International Workshop on Quality of Experience Management (QoE-Management)}, keywords = {ua-net}, month = {02}, title = {QUICker or not? - an Empirical Analysis of QUIC vs TCP for Video Streaming QoE Provisioning}, year = 2019 }
• {TeaStore - A Micro-Service Application for Benchmarking, Modeling and Resource Management Research}. Eismann, Simon. 2019, February.
  • [ Abstract ]
  • [ BibTeX ]
  Researchers propose and employ various methods to analyze, model, optimize and manage modern distributed micro-service applications. In order to demonstrate and evaluate these methods in realistic scenarios, researchers rely on reference applications. These applications should offer a range of different behaviors, degrees of freedom allowing for customization and should use a modern and representative technology stack. Unfortunately, existing testing and benchmarking applications are either outdated, designed for specific testing scenarios, or do not offer the necessary degrees of freedom. In this talk, we introduce the TeaStore, a state-of-the-art test and reference application with a micro-service architecture. TeaStore offers services with different performance characteristics and many degrees of freedom regarding deployment and configuration to be used as a benchmarking framework for researchers. Based on three experiments, we demonstrate TeaStore's use in three different research contexts: performance modeling, cloud resource management, and energy efficiency analysis.

  @misc{talk-Eismann-SE2019, abstract = {Researchers propose and employ various methods to analyze, model, optimize and manage modern distributed micro-service applications. In order to demonstrate and evaluate these methods in realistic scenarios, researchers rely on reference applications. These applications should offer a range of different behaviors, degrees of freedom allowing for customization and should use a modern and representative technology stack. Unfortunately, existing testing and benchmarking applications are either outdated, designed for specific testing scenarios, or do not offer the necessary degrees of freedom. In this talk, we introduce the TeaStore, a state-of-the-art test and reference application with a micro-service architecture. TeaStore offers services with different performance characteristics and many degrees of freedom regarding deployment and configuration to be used as a benchmarking framework for researchers. Based on three experiments, we demonstrate TeaStore's use in three different research contexts: performance modeling, cloud resource management, and energy efficiency analysis.}, author = {Eismann, Simon}, howpublished = {Multikonferenz Software Engineering & Management 2019}, keywords = {Cloud}, month = {02}, title = {{TeaStore - A Micro-Service Application for Benchmarking, Modeling and Resource Management Research}}, year = 2019 }
• Automation und Digitalisierung - Potenzial und Einsatz von Blockchain- und Distributed-Ledger-Technologien in der Automatisierungstechnik. Skwarek, Volker; Reher, Julian; Geissler, Stefan; Zinner, Thomas. 2019, February.
  • [ BibTeX ]
  @misc{info3-misc-2019-1, author = {Skwarek, Volker and Reher, Julian and Geissler, Stefan and Zinner, Thomas}, howpublished = {Zentralverband Elektrotechnik- und Elektroindustrie}, keywords = {net-man}, month = {02}, title = {Automation und Digitalisierung - Potenzial und Einsatz von Blockchain- und Distributed-Ledger-Technologien in der Automatisierungstechnik}, year = 2019 }
• Computing QoE-relevant Adaptive Video Streaming Metrics using Discrete-Time Analysis. Schwarzmann, Susanna; Breitbach, Paula; Zinner, Thomas. In Third International Workshop on Quality of Experience Management 2019. 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-3, author = {Schwarzmann, Susanna and Breitbach, Paula and Zinner, Thomas}, booktitle = {Third International Workshop on Quality of Experience Management 2019}, keywords = {dfg-sdn}, month = {02}, title = {Computing QoE-relevant Adaptive Video Streaming Metrics using Discrete-Time Analysis}, year = 2019 }
• {SPEC Research Group Newsletter, vol. 2 no. 4}. Kounev, Samuel; van Hoorn, Andre; Bauer, Andr{é}; Herbst, Nikolas. 2019, April.
  • [ BibTeX ]
  • [ URL ]
  @misc{SPEC-RG-NEWSLETTER-8, author = {Kounev, Samuel and van Hoorn, Andre and Bauer, Andr{\'e} and Herbst, Nikolas}, keywords = {se2}, month = {04}, note = {Published by Standard Performance Evaluation Corporation (SPEC)}, title = {{SPEC Research Group Newsletter, vol. 2 no. 4}}, year = 2019 }
• Discrete-Time Modeling of NFV Accelerators that Exploit Batched Processing. Lange, Stanislav; Linguaglossa, Leonardo; Geissler, Stefan; Rossi, Dario; Zinner, Thomas. In IEEE Conference on Computer Communications (Infocom). 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-4, author = {Lange, Stanislav and Linguaglossa, Leonardo and Geissler, Stefan and Rossi, Dario and Zinner, Thomas}, booktitle = {IEEE Conference on Computer Communications (Infocom)}, keywords = {sendate}, month = {04}, title = {Discrete-Time Modeling of NFV Accelerators that Exploit Batched Processing}, year = 2019 }
• Using Attention Testing to Select Crowdsourced Workers and Research Participants. Göritz, Anja; Borchert, Kathrin; Hirth, Matthias. In Social Science Computer Review. 2019.
  • [ BibTeX ]
  @article{info3-article-2019-7, author = {Göritz, Anja and Borchert, Kathrin and Hirth, Matthias}, journal = {Social Science Computer Review}, keywords = {myown}, month = {06}, title = {Using Attention Testing to Select Crowdsourced Workers and Research Participants}, year = 2019 }
• From click to playback: a dataset to study the response time of mobile YouTube. Loh, Frank; Wamser, Florian; Moldovan, Christian; Zeidler, Bernd; Hoßfeld, Tobias; Tsilimantos, Dimitrios; Valentin, Stefan. In Proceedings of the 10th ACM Multimedia Systems Conference, pp. 267–272. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Responding fluently to user requests is important to keep them immersed. In this paper, we are presenting an extensive dataset to study the response time of YouTube's mobile video streaming service on Android. We illustrate the application of our dataset by studying YouTube's initial delay for a subset of 9 videos in 75 network scenarios. We find that in 41% of the cases, YouTube exceeds the attention span of a typical user, while deep immersion is only reached in 15% of the cases. Our factor analysis implies that the allocation of the initial CDN node is the critical link in this delay chain. Since our dataset includes a large variety of factors, we are describing setup, methodology, and data structure in detail. Our dataset and measurement tools are publicly available.

  @inproceedings{info3-inproceedings-2019-25, abstract = {Responding fluently to user requests is important to keep them immersed. In this paper, we are presenting an extensive dataset to study the response time of YouTube's mobile video streaming service on Android. We illustrate the application of our dataset by studying YouTube's initial delay for a subset of 9 videos in 75 network scenarios. We find that in 41% of the cases, YouTube exceeds the attention span of a typical user, while deep immersion is only reached in 15% of the cases. Our factor analysis implies that the allocation of the initial CDN node is the critical link in this delay chain. Since our dataset includes a large variety of factors, we are describing setup, methodology, and data structure in detail. Our dataset and measurement tools are publicly available.}, author = {Loh, Frank and Wamser, Florian and Moldovan, Christian and Zeidler, Bernd and Hoßfeld, Tobias and Tsilimantos, Dimitrios and Valentin, Stefan}, booktitle = {Proceedings of the 10th ACM Multimedia Systems Conference}, keywords = {can}, month = {06}, pages = {267-272}, title = {From click to playback: a dataset to study the response time of mobile YouTube}, year = 2019 }
• {Autonomic Forecasting Method Selection: Examination and Ways Ahead}. Z{ü}fle, Marwin; Bauer, Andr{é}; Lesch, Veronika; Krupitzer, Christian; Herbst, Nikolas; Kounev, Samuel; Curtef, Valentin. In Proceedings of the 16th {IEEE} International Conference on Autonomic Computing (ICAC). IEEE, 2019.
  • [ BibTeX ]
  @inproceedings{ZuBaLeKrHeKoCu2019-ICAC-Autonomic, author = {Z{\"u}fle, Marwin and Bauer, Andr{\'e} and Lesch, Veronika and Krupitzer, Christian and Herbst, Nikolas and Kounev, Samuel and Curtef, Valentin}, booktitle = {Proceedings of the 16th {IEEE} International Conference on Autonomic Computing (ICAC)}, keywords = {PRISMA}, month = {06}, publisher = {IEEE}, title = {{Autonomic Forecasting Method Selection: Examination and Ways Ahead}}, year = 2019 }
• {Best Practices for Time Series Forecasting}. Bauer, Andr{é}; Z{ü}fle, Marwin; Herbst, Nikolas; Kounev, Samuel. In {2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)}. 2019.
  • [ BibTeX ]
  @inproceedings{BaZuHeKo2019-ICAC-ForecastingTutorial, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Herbst, Nikolas and Kounev, Samuel}, booktitle = {{2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)}}, keywords = {t_tutorial}, month = {06}, title = {{Best Practices for Time Series Forecasting}}, year = 2019 }
• {Best Practices for Time Series Forecasting}. Bauer, Andr{é}; Z{ü}fle, Marwin; Herbst, Nikolas; Kounev, Samuel. In {2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)}. 2019.
  • [ BibTeX ]
  @inproceedings{BaZuHeKo2019-ICAC-ForecastingTutorial, author = {Bauer, Andr{\'e} and Z{\"u}fle, Marwin and Herbst, Nikolas and Kounev, Samuel}, booktitle = {{2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)}}, keywords = {t_tutorial}, month = {06}, title = {{Best Practices for Time Series Forecasting}}, year = 2019 }
• {Utilizing Clustering to Optimize Resource Demand Estimation Approaches}. Grohmann, Johannes; Eismann, Simon; Bauer, Andre; Zuefle, Marwin; Herbst, Nikolas; Kounev, Samuel. In 2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W), pp. 134–139. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Resource demands are crucial parameters for modeling and predicting the performance of software systems. Direct measurement of these resource demands is usually infeasible due to instrumentation overheads causing measurement interferences and perturbation in production environments. Thus, a number of statistical estimation approaches (e.g., based on optimization, regression or Kalman filters) have been proposed in the literature. Most of these approaches are parameterized. These parameters influence the estimation quality and the required computation time. Existing work uses historical data as training sets to optimize those parameters and to minimize the estimation error of those approaches. However, if the data traces are fundamentally different, the optimal parameter settings are different as well. In this paper, we propose to use automated clustering in order to group training sets into groups of similar optimization behavior. This way, optimization can be specifically tailored to certain groups of traces in a self-aware manner. During run-time, every trace is first sorted into a cluster, where the respective cluster-wide parameter optimum can be applied. A preliminary case study shows that clustering can provide promising improvements.

  @inproceedings{GrEiBaZuHeKo2019-ICAC-RDEClustering, abstract = {Resource demands are crucial parameters for modeling and predicting the performance of software systems. Direct measurement of these resource demands is usually infeasible due to instrumentation overheads causing measurement interferences and perturbation in production environments. Thus, a number of statistical estimation approaches (e.g., based on optimization, regression or Kalman filters) have been proposed in the literature. Most of these approaches are parameterized. These parameters influence the estimation quality and the required computation time. Existing work uses historical data as training sets to optimize those parameters and to minimize the estimation error of those approaches. However, if the data traces are fundamentally different, the optimal parameter settings are different as well. In this paper, we propose to use automated clustering in order to group training sets into groups of similar optimization behavior. This way, optimization can be specifically tailored to certain groups of traces in a self-aware manner. During run-time, every trace is first sorted into a cluster, where the respective cluster-wide parameter optimum can be applied. A preliminary case study shows that clustering can provide promising improvements.}, author = {Grohmann, Johannes and Eismann, Simon and Bauer, Andre and Zuefle, Marwin and Herbst, Nikolas and Kounev, Samuel}, booktitle = {2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)}, keywords = {Optimization}, month = {06}, pages = {134–139}, publisher = {IEEE}, title = {{Utilizing Clustering to Optimize Resource Demand Estimation Approaches}}, year = 2019 }
• {Der Weg vom Internet-der-Dinge zum Internet-der-denkenden-Dinge}. Kounev, Samuel. W{ü}rzburz, Germany, 2019, June.
  • [ BibTeX ]
  @misc{Talk-Ko2019-RotaryClub-SeAC, address = {W{\"u}rzburz, Germany}, author = {Kounev, Samuel}, howpublished = {Rotary Club W{\"u}rzburg, 11.06.2019}, keywords = {descartes}, month = {06}, title = {{Der Weg vom Internet-der-Dinge zum Internet-der-denkenden-Dinge}}, year = 2019 }
• User Behavior and Engagement of a Mobile Video Streaming User from Crowdsourced Measurements. Moldovan, Christian. Berlin, Germany, 2019, June.
  • [ BibTeX ]
  @misc{info3-poster-2019-1, address = {Berlin, Germany}, author = {Moldovan, Christian}, booktitle = {2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {myown}, month = {06}, title = {User Behavior and Engagement of a Mobile Video Streaming User from Crowdsourced Measurements}, year = 2019 }
• Agile Scalability Engineering: The ScrumScale Method. Brataas, Gunnar; Hanssen, Geir; Herbst, Nikolas; van Hoorn, Andr{é}. In IEEE Software, 37(5), pp. 77–85. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Scalability is a property that must be carefully designed into a system. A case study in the largest Norwegian public portal, Altinn, illustrates how developers and scalability experts improved scalability and spent less time during scalability testing. With minor adjustments to an agile development process, stakeholders spend more up-front time together.

  @article{ScrumScale2019IEEESW, abstract = {Scalability is a property that must be carefully designed into a system. A case study in the largest Norwegian public portal, Altinn, illustrates how developers and scalability experts improved scalability and spent less time during scalability testing. With minor adjustments to an agile development process, stakeholders spend more up-front time together.}, author = {Brataas, Gunnar and Hanssen, Geir and Herbst, Nikolas and van Hoorn, Andr{\'e}}, journal = {IEEE Software}, keywords = {se2}, month = {06}, note = {to appear}, number = 5, pages = {77-85}, publisher = {IEEE}, title = {Agile Scalability Engineering: The ScrumScale Method}, volume = 37, year = 2019 }
• {Systematic Search for Optimal Resource Configurations of Distributed Applications}. Bauer, Andr{é}; Eismann, Simon; Grohmann, Johannes; Herbst, Nikolas; Kounev, Samuel. In 2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W), pp. 120–125. IEEE Computer Society, Los Alamitos, CA, USA, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  With the advent of the micro-service paradigm, applications are divided into small, distributed parts. Knowledge of optimal resource configurations of such applications is required both for autonomic resource management as well as its assessment. Due to the high-dimensional search space of all possible configurations, the systematic measuring of the optimal configurations is challenging. To this end, we introduce a search algorithm based on hill-climbing for finding all optimal configurations in a feasible time and integrate it in an existing measuring framework. This approach enables the assessment, comparison and optimization of autonomic resource management approaches for micro-service applications. The evaluation shows that our approach is able to find all optimal configurations in the considered scenarios, while state-of-the-art multi-objective search algorithms do not.

  @inproceedings{BaEiGrHeKo-ICAC-BUNGEE, abstract = {With the advent of the micro-service paradigm, applications are divided into small, distributed parts. Knowledge of optimal resource configurations of such applications is required both for autonomic resource management as well as its assessment. Due to the high-dimensional search space of all possible configurations, the systematic measuring of the optimal configurations is challenging. To this end, we introduce a search algorithm based on hill-climbing for finding all optimal configurations in a feasible time and integrate it in an existing measuring framework. This approach enables the assessment, comparison and optimization of autonomic resource management approaches for micro-service applications. The evaluation shows that our approach is able to find all optimal configurations in the considered scenarios, while state-of-the-art multi-objective search algorithms do not.}, address = {Los Alamitos, CA, USA}, author = {Bauer, Andr{\'e} and Eismann, Simon and Grohmann, Johannes and Herbst, Nikolas and Kounev, Samuel}, booktitle = {2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)}, keywords = {Optimization}, month = {06}, pages = {120–125}, publisher = {IEEE Computer Society}, title = {{Systematic Search for Optimal Resource Configurations of Distributed Applications}}, year = 2019 }
• In Vivo or in Vitro? Influence of the Study Design on Crowdsourced Video QoE. Borchert, Kathrin; Schwind, Anika; Hirth, Matthias; Hoßfeld, Tobias. In 11th International Conference on Quality of Multimedia Experience (QoMEX). 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-10, author = {Borchert, Kathrin and Schwind, Anika and Hirth, Matthias and Hoßfeld, Tobias}, booktitle = {11th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ua-net}, month = {06}, title = {In Vivo or in Vitro? Influence of the Study Design on Crowdsourced Video QoE}, year = 2019 }
• A Fair Share for All: TCP-inspired Adaptation Logic for QoE Fairness among Heterogeneous HTTP Adaptive Video Streaming Clients. Seufert, Michael; Wehner, Nikolas; Casas, Pedro. In IEEE Transactions on Network and Service Management, 16(2), pp. 475–488. 2019.
  • [ BibTeX ]
  @article{info3-article-2019-4, author = {Seufert, Michael and Wehner, Nikolas and Casas, Pedro}, journal = {IEEE Transactions on Network and Service Management}, keywords = {net-man}, month = {06}, number = 2, pages = {475-488}, title = {A Fair Share for All: TCP-inspired Adaptation Logic for QoE Fairness among Heterogeneous HTTP Adaptive Video Streaming Clients}, volume = 16, year = 2019 }
• Not Alone Here?! Scalability and User Experience of Embodied Ambient Crowds in Distributed Social Virtual Reality. Latoschik, Marc Erich; Kern, Florian; Stauffert, Jan-Philipp; Bartl, Andrea; Botsch, Mario; Lugrin, Jean-Luc. In IEEE Transactions on Visualization and Computer Graphics (TVCG), 25(5), pp. 2134–2144. 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  This article investigates performance and user experience in Social Virtual Reality (SVR) targeting distributed, embodied, and immersive, face-to-face encounters. We demonstrate the close relationship between scalability, reproduction accuracy, and the resulting performance characteristics, as well as the impact of these characteristics on users co-located with larger groups of embodied virtual others. System scalability provides a variable number of co-located avatars and AI-controlled agents with a variety of different appearances, including realistic-looking virtual humans generated from photogrammetry scans. The article reports on how to meet the requirements of embodied SVR with today\u0027s technical off-the-shelf solutions and what to expect regarding features, performance, and potential limitations. Special care has been taken to achieve low latencies and sufficient frame rates necessary for reliable communication of embodied social signals. We propose a hybrid evaluation approach which coherently relates results from technical benchmarks to subjective ratings and which confirms required performance characteristics for the target scenario of larger distributed groups. A user-study reveals positive effects of an increasing number of co-located social companions on the quality of experience of virtual worlds, i.e., on presence, possibility of interaction, and co-presence. It also shows that variety in avatar/agent appearance might increase eeriness but might also stimulate an increased interest of participants about the environment.

  @article{latoschik2019alone, abstract = {This article investigates performance and user experience in Social Virtual Reality (SVR) targeting distributed, embodied, and immersive, face-to-face encounters. We demonstrate the close relationship between scalability, reproduction accuracy, and the resulting performance characteristics, as well as the impact of these characteristics on users co-located with larger groups of embodied virtual others. System scalability provides a variable number of co-located avatars and AI-controlled agents with a variety of different appearances, including realistic-looking virtual humans generated from photogrammetry scans. The article reports on how to meet the requirements of embodied SVR with today\u0027s technical off-the-shelf solutions and what to expect regarding features, performance, and potential limitations. Special care has been taken to achieve low latencies and sufficient frame rates necessary for reliable communication of embodied social signals. We propose a hybrid evaluation approach which coherently relates results from technical benchmarks to subjective ratings and which confirms required performance characteristics for the target scenario of larger distributed groups. A user-study reveals positive effects of an increasing number of co-located social companions on the quality of experience of virtual worlds, i.e., on presence, possibility of interaction, and co-presence. It also shows that variety in avatar/agent appearance might increase eeriness but might also stimulate an increased interest of participants about the environment.}, author = {Latoschik, Marc Erich and Kern, Florian and Stauffert, Jan-Philipp and Bartl, Andrea and Botsch, Mario and Lugrin, Jean-Luc}, journal = {IEEE Transactions on Visualization and Computer Graphics (TVCG)}, keywords = {vilearn}, month = {05}, number = 5, pages = {2134-2144}, title = {Not Alone Here?! Scalability and User Experience of Embodied Ambient Crowds in Distributed Social Virtual Reality}, volume = 25, year = 2019 }
• Online Power Consumption Estimation for Functions in Cloud Applications. Schmitt, Norbert; Iffländer, Lukas; Bauer, André; Kounev, Samuel. In Proceedings of the 16th IEEE International Conference on Autonomic Computing (ICAC). IEEE, 2019.
  • [ BibTeX ]
  @inproceedings{ScIfBaKo2019-ICAC-OnlinePowerEstimation, author = {Schmitt, Norbert and Iffländer, Lukas and Bauer, André and Kounev, Samuel}, booktitle = {Proceedings of the 16th IEEE International Conference on Autonomic Computing (ICAC)}, keywords = {Power}, month = {06}, publisher = {IEEE}, title = {Online Power Consumption Estimation for Functions in Cloud Applications}, year = 2019 }
• {Systematic Search for Optimal Resource Configurations of Distributed Applications}. Bauer, Andr{é}; Eismann, Simon; Grohmann, Johannes; Herbst, Nikolas; Kounev, Samuel. In 2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W), pp. 120–125. IEEE Computer Society, Los Alamitos, CA, USA, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  With the advent of the micro-service paradigm, applications are divided into small, distributed parts. Knowledge of optimal resource configurations of such applications is required both for autonomic resource management as well as its assessment. Due to the high-dimensional search space of all possible configurations, the systematic measuring of the optimal configurations is challenging. To this end, we introduce a search algorithm based on hill-climbing for finding all optimal configurations in a feasible time and integrate it in an existing measuring framework. This approach enables the assessment, comparison and optimization of autonomic resource management approaches for micro-service applications. The evaluation shows that our approach is able to find all optimal configurations in the considered scenarios, while state-of-the-art multi-objective search algorithms do not.

  @inproceedings{BaEiGrHeKo-ICAC-BUNGEE, abstract = {With the advent of the micro-service paradigm, applications are divided into small, distributed parts. Knowledge of optimal resource configurations of such applications is required both for autonomic resource management as well as its assessment. Due to the high-dimensional search space of all possible configurations, the systematic measuring of the optimal configurations is challenging. To this end, we introduce a search algorithm based on hill-climbing for finding all optimal configurations in a feasible time and integrate it in an existing measuring framework. This approach enables the assessment, comparison and optimization of autonomic resource management approaches for micro-service applications. The evaluation shows that our approach is able to find all optimal configurations in the considered scenarios, while state-of-the-art multi-objective search algorithms do not.}, address = {Los Alamitos, CA, USA}, author = {Bauer, Andr{\'e} and Eismann, Simon and Grohmann, Johannes and Herbst, Nikolas and Kounev, Samuel}, booktitle = {2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)}, keywords = {Optimization}, month = {06}, pages = {120–125}, publisher = {IEEE Computer Society}, title = {{Systematic Search for Optimal Resource Configurations of Distributed Applications}}, year = 2019 }
• {Utilizing Clustering to Optimize Resource Demand Estimation Approaches}. Grohmann, Johannes; Eismann, Simon; Bauer, Andre; Zuefle, Marwin; Herbst, Nikolas; Kounev, Samuel. In 2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W), pp. 134–139. IEEE, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  Resource demands are crucial parameters for modeling and predicting the performance of software systems. Direct measurement of these resource demands is usually infeasible due to instrumentation overheads causing measurement interferences and perturbation in production environments. Thus, a number of statistical estimation approaches (e.g., based on optimization, regression or Kalman filters) have been proposed in the literature. Most of these approaches are parameterized. These parameters influence the estimation quality and the required computation time. Existing work uses historical data as training sets to optimize those parameters and to minimize the estimation error of those approaches. However, if the data traces are fundamentally different, the optimal parameter settings are different as well. In this paper, we propose to use automated clustering in order to group training sets into groups of similar optimization behavior. This way, optimization can be specifically tailored to certain groups of traces in a self-aware manner. During run-time, every trace is first sorted into a cluster, where the respective cluster-wide parameter optimum can be applied. A preliminary case study shows that clustering can provide promising improvements.

  @inproceedings{GrEiBaZuHeKo2019-ICAC-RDEClustering, abstract = {Resource demands are crucial parameters for modeling and predicting the performance of software systems. Direct measurement of these resource demands is usually infeasible due to instrumentation overheads causing measurement interferences and perturbation in production environments. Thus, a number of statistical estimation approaches (e.g., based on optimization, regression or Kalman filters) have been proposed in the literature. Most of these approaches are parameterized. These parameters influence the estimation quality and the required computation time. Existing work uses historical data as training sets to optimize those parameters and to minimize the estimation error of those approaches. However, if the data traces are fundamentally different, the optimal parameter settings are different as well. In this paper, we propose to use automated clustering in order to group training sets into groups of similar optimization behavior. This way, optimization can be specifically tailored to certain groups of traces in a self-aware manner. During run-time, every trace is first sorted into a cluster, where the respective cluster-wide parameter optimum can be applied. A preliminary case study shows that clustering can provide promising improvements.}, author = {Grohmann, Johannes and Eismann, Simon and Bauer, Andre and Zuefle, Marwin and Herbst, Nikolas and Kounev, Samuel}, booktitle = {2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)}, keywords = {Optimization}, month = {06}, pages = {134–139}, publisher = {IEEE}, title = {{Utilizing Clustering to Optimize Resource Demand Estimation Approaches}}, year = 2019 }
• Is QUIC becoming the New TCP? On the Potential Impact of a New Protocol on Networked Multimedia QoE. Seufert, Michael; Schatz, Raimund; Wehner, Nikolas; Gardlo, Bruno; Casas, Pedro. In 11th International Conference on Quality of Multimedia Experience (QoMEX). Berlin, Germany, 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-13, address = {Berlin, Germany}, author = {Seufert, Michael and Schatz, Raimund and Wehner, Nikolas and Gardlo, Bruno and Casas, Pedro}, booktitle = {11th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {ua-net}, month = {06}, title = {Is QUIC becoming the New TCP? On the Potential Impact of a New Protocol on Networked Multimedia QoE}, year = 2019 }
• To Share or Not to Share? How Exploitation of Context Data Can Improve In-Network QoE Monitoring of Encrypted YouTube Streams. Orsolic, Irena; Skorin-Kapov, Lea; Hoßfeld, Tobias. In 2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX) (QoMEX 2019). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  With the widespread use of encryption in Over the Top (OTT) traffic, Internet Service Providers (ISPs) for the most part lack insights into application performance, as well as into Quality of Experience (QoE) perceived by end users. Addressing challenges related to encryption, ISPs are looking into machine learning based solutions that can detect application performance solely from statistical properties of the traffic. On the other hand, OTT service providers are not willing to share service performance and content-related information with ISPs. While related work on OTT-ISP collaboration scenarios has addressed architectural aspects, business models, and to a certain extent incentives for sharing data, the focus of this paper is on the exchanged data itself. We investigate to what extent the performance of in-network machine learning based QoE estimation models for HTTP adaptive video streaming could be improved with the availability of certain context data provided by OTT providers. We motivate OTT-ISP collaboration through more accurate in-network QoE monitoring and potential improvement of user experience, which is of interest to both sides.

  @inproceedings{info3-article-2019-9, abstract = {With the widespread use of encryption in Over the Top (OTT) traffic, Internet Service Providers (ISPs) for the most part lack insights into application performance, as well as into Quality of Experience (QoE) perceived by end users. Addressing challenges related to encryption, ISPs are looking into machine learning based solutions that can detect application performance solely from statistical properties of the traffic. On the other hand, OTT service providers are not willing to share service performance and content-related information with ISPs. While related work on OTT-ISP collaboration scenarios has addressed architectural aspects, business models, and to a certain extent incentives for sharing data, the focus of this paper is on the exchanged data itself. We investigate to what extent the performance of in-network machine learning based QoE estimation models for HTTP adaptive video streaming could be improved with the availability of certain context data provided by OTT providers. We motivate OTT-ISP collaboration through more accurate in-network QoE monitoring and potential improvement of user experience, which is of interest to both sides.}, author = {Orsolic, Irena and Skorin-Kapov, Lea and Hoßfeld, Tobias}, booktitle = {2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX) (QoMEX 2019)}, keywords = {YouTube}, month = {06}, title = {To Share or Not to Share? How Exploitation of Context Data Can Improve In-Network QoE Monitoring of Encrypted YouTube Streams}, year = 2019 }
• {Methoden und Messverfahren f{ü}r Automatisches Skalieren in Elastischen Cloud Umgebungen}. Herbst, Nikolas. 2019, June.
  • [ BibTeX ]
  @misc{talk-Herbst-GIAwardNomination-Dagstuhl, author = {Herbst, Nikolas}, howpublished = {GI Dissertationspreis: Seminar f{\"u}r Nominierte Doktoranden, Dagstuhl, Germany, June 28, 2019}, keywords = {t_bookchapter}, month = {06}, title = {{Methoden und Messverfahren f{\"u}r Automatisches Skalieren in Elastischen Cloud Umgebungen}}, year = 2019 }
• {Autonomic Forecasting Method Selection: Examination and Ways Ahead}. Z{ü}fle, Marwin; Bauer, Andr{é}; Lesch, Veronika; Krupitzer, Christian; Herbst, Nikolas; Kounev, Samuel; Curtef, Valentin. In Proceedings of the 16th {IEEE} International Conference on Autonomic Computing (ICAC). IEEE, 2019.
  • [ BibTeX ]
  @inproceedings{ZuBaLeKrHeKoCu2019-ICAC-Autonomic, author = {Z{\"u}fle, Marwin and Bauer, Andr{\'e} and Lesch, Veronika and Krupitzer, Christian and Herbst, Nikolas and Kounev, Samuel and Curtef, Valentin}, booktitle = {Proceedings of the 16th {IEEE} International Conference on Autonomic Computing (ICAC)}, keywords = {PRISMA}, month = {06}, publisher = {IEEE}, title = {{Autonomic Forecasting Method Selection: Examination and Ways Ahead}}, year = 2019 }
• {Systematic Search for Optimal Resource Configurations of Distributed Applications}. Bauer, Andr{é}; Eismann, Simon; Grohmann, Johannes; Herbst, Nikolas; Kounev, Samuel. In 2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W), pp. 120–125. IEEE Computer Society, Los Alamitos, CA, USA, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  • [ URL ]
  With the advent of the micro-service paradigm, applications are divided into small, distributed parts. Knowledge of optimal resource configurations of such applications is required both for autonomic resource management as well as its assessment. Due to the high-dimensional search space of all possible configurations, the systematic measuring of the optimal configurations is challenging. To this end, we introduce a search algorithm based on hill-climbing for finding all optimal configurations in a feasible time and integrate it in an existing measuring framework. This approach enables the assessment, comparison and optimization of autonomic resource management approaches for micro-service applications. The evaluation shows that our approach is able to find all optimal configurations in the considered scenarios, while state-of-the-art multi-objective search algorithms do not.

  @inproceedings{BaEiGrHeKo-ICAC-BUNGEE, abstract = {With the advent of the micro-service paradigm, applications are divided into small, distributed parts. Knowledge of optimal resource configurations of such applications is required both for autonomic resource management as well as its assessment. Due to the high-dimensional search space of all possible configurations, the systematic measuring of the optimal configurations is challenging. To this end, we introduce a search algorithm based on hill-climbing for finding all optimal configurations in a feasible time and integrate it in an existing measuring framework. This approach enables the assessment, comparison and optimization of autonomic resource management approaches for micro-service applications. The evaluation shows that our approach is able to find all optimal configurations in the considered scenarios, while state-of-the-art multi-objective search algorithms do not.}, address = {Los Alamitos, CA, USA}, author = {Bauer, Andr{\'e} and Eismann, Simon and Grohmann, Johannes and Herbst, Nikolas and Kounev, Samuel}, booktitle = {2019 IEEE 4th International Workshops on Foundations and Applications of Self* Systems (FAS*W)}, keywords = {Optimization}, month = {06}, pages = {120–125}, publisher = {IEEE Computer Society}, title = {{Systematic Search for Optimal Resource Configurations of Distributed Applications}}, year = 2019 }
• User Behavior and Engagement of a Mobile Video Streaming User from Crowdsourced Measurements. Moldovan, Christian; Wamser, Florian; Hoßfeld, Tobias. In 2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX). 2019.
  • [ Abstract ]
  • [ BibTeX ]
  Mobile video streaming has gained a lot of popularity in recent year with the introduction of large data plans for mobile phones. While users in non-mobile scenarios have become accustomed to high quality and few stalling events, this is not the case in mobile environments. People are more likely to tolerate stalling since they know high throughput coverage cannot always be guaranteed. Their behavior and their engagement are drastically different when watching videos on mobile devices. In this paper, we characterize mobile phone users who use a video streaming application. We present a data set of over 6,000 video views from a crowdsourced video measurement study. We investigate user activity and engagement during video streaming and how such metrics are correlated with each other. This is the first study that goes beyond user engagement and investigates the direct behavior of mobile video users outside the lab which is an important step towards mobile QoE management.

  @inproceedings{info3-inproceedings-2019-21, abstract = {Mobile video streaming has gained a lot of popularity in recent year with the introduction of large data plans for mobile phones. While users in non-mobile scenarios have become accustomed to high quality and few stalling events, this is not the case in mobile environments. People are more likely to tolerate stalling since they know high throughput coverage cannot always be guaranteed. Their behavior and their engagement are drastically different when watching videos on mobile devices. In this paper, we characterize mobile phone users who use a video streaming application. We present a data set of over 6,000 video views from a crowdsourced video measurement study. We investigate user activity and engagement during video streaming and how such metrics are correlated with each other. This is the first study that goes beyond user engagement and investigates the direct behavior of mobile video users outside the lab which is an important step towards mobile QoE management.}, author = {Moldovan, Christian and Wamser, Florian and Hoßfeld, Tobias}, booktitle = {2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {can}, month = {06}, title = {User Behavior and Engagement of a Mobile Video Streaming User from Crowdsourced Measurements}, year = 2019 }
• Online Detection of Stalling and Scrubbing in Adaptive Video Streaming. Maggi, Lorenzo; Leguay, Jeremy; Seufert, Michael; Casas, Pedro. In 17th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks (WiOpt). Avignon, France, 2019.
  • [ BibTeX ]
  @inproceedings{info3-inproceedings-2019-12, address = {Avignon, France}, author = {Maggi, Lorenzo and Leguay, Jeremy and Seufert, Michael and Casas, Pedro}, booktitle = {17th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks (WiOpt)}, keywords = {net-man}, month = {06}, title = {Online Detection of Stalling and Scrubbing in Adaptive Video Streaming}, year = 2019 }
• Computing Height-Optimal Tangles Faster. Firman, Oksana; Kindermann, Philipp; Ravsky, Alexander; Wolff, Alexander; Zink, Johannes. In Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD’19), Vol. 11904 of Lecture Notes in Computer Science, D. Archambault, C. D. T{ó}th (eds.), pp. 203–215. Springer-Verlag, 2019.
  • [ Abstract ]
  • [ BibTeX ]
  We study the following combinatorial problem. Given a set of n y-monotone wires, a tangle determines the order of the wires on a number of horizontal layers such that the orders of the wires on any two consecutive layers differ only in swaps of neighboring wires. Given a multiset L of swaps (that is, unordered pairs of numbers between 1 and n) and an initial order of the wires, a tangle realizes L if each pair of wires changes its order exactly as many times as specified by L. The aim is to find a tangle that realizes L using the smallest number of layers. We show that this problem is NP-hard, and we give an algorithm that computes an optimal tangle for n wires and a given list L of swaps in O((2|L|/n^2+1)^(n^2/2)phi^n n) time, where phi~1.618 is the golden ratio. We can treat lists where every swap occurs at most once in O(n! phi^n) time. We implemented the algorithm for the general case and compared it to an existing algorithm.

  @inproceedings{fkrwz-cotf-gd19, abstract = {We study the following combinatorial problem. Given a set of n y-monotone wires, a tangle determines the order of the wires on a number of horizontal layers such that the orders of the wires on any two consecutive layers differ only in swaps of neighboring wires. Given a multiset L of swaps (that is, unordered pairs of numbers between 1 and n) and an initial order of the wires, a tangle realizes L if each pair of wires changes its order exactly as many times as specified by L. The aim is to find a tangle that realizes L using the smallest number of layers. We show that this problem is NP-hard, and we give an algorithm that computes an optimal tangle for n wires and a given list L of swaps in O((2|L|/n^2+1)^(n^2/2)phi^n n) time, where phi 1.618 is the golden ratio. We can treat lists where every swap occurs at most once in O(n! phi^n) time. We implemented the algorithm for the general case and compared it to an existing algorithm.}, author = {Firman, Oksana and Kindermann, Philipp and Ravsky, Alexander and Wolff, Alexander and Zink, Johannes}, booktitle = {Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD'19)}, editor = {Archambault, Daniel and T\'{o}th, Csaba D.}, keywords = {myown}, pages = {203–215}, publisher = {Springer-Verlag}, series = {Lecture Notes in Computer Science}, title = {Computing Height-Optimal Tangles Faster}, volume = 11904, year = 2019 }