05 Fakultät Informatik, Elektrotechnik und Informationstechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6
Browse
10 results
Search Results
Item Open Access VisRecall++: analysing and predicting visualisation recallability from gaze behaviour(2024) Wang, Yao; Jiang, Yue; Hu, Zhiming; Ruhdorfer, Constantin; Bâce, Mihai; Bulling, AndreasQuestion answering has recently been proposed as a promising means to assess the recallability of information visualisations. However, prior works are yet to study the link between visually encoding a visualisation in memory and recall performance. To fill this gap, we propose VisRecall++ - a novel 40-participant recallability dataset that contains gaze data on 200 visualisations and five question types, such as identifying the title, and finding extreme values.We measured recallability by asking participants questions after they observed the visualisation for 10 seconds.Our analyses reveal several insights, such as saccade amplitude, number of fixations, and fixation duration significantly differ between high and low recallability groups.Finally, we propose GazeRecallNet - a novel computational method to predict recallability from gaze behaviour that outperforms several baselines on this task.Taken together, our results shed light on assessing recallability from gaze behaviour and inform future work on recallability-based visualisation optimisation.Item Open Access SalChartQA: question-driven saliency on information visualisations(2024) Wang, Yao; Wang, Weitian; Abdelhafez, Abdullah; Elfares, Mayar; Hu, Zhiming; Bâce, Mihai; Bulling, AndreasUnderstanding the link between visual attention and user’s needs when visually exploring information visualisations is under-explored due to a lack of large and diverse datasets to facilitate these analyses. To fill this gap, we introduce SalChartQA - a novel crowd-sourced dataset that uses the BubbleView interface as a proxy for human gaze and a question-answering (QA) paradigm to induce different information needs in users. SalChartQA contains 74,340 answers to 6,000 questions on 3,000 visualisations. Informed by our analyses demonstrating the tight correlation between the question and visual saliency, we propose the first computational method to predict question-driven saliency on information visualisations. Our method outperforms state-of-the-art saliency models, improving several metrics, such as the correlation coefficient and the Kullback-Leibler divergence. These results show the importance of information needs for shaping attention behaviour and paving the way for new applications, such as task-driven optimisation of visualisations or explainable AI in chart question-answering.Item Open Access Informationsmodelle mit intelligenter Auswertung für den Digitalen Zwilling(2020) Müller, Manuel; Ashtari Talkhestani, Behrang; Jazdi, Nasser; Rosen, Roland; Wehrstedt, Jan Christoph; Weyrich, MichaelDie zunehmende Komplexität hochautomatisierter Systeme bringt neue Herausforderungen bei der Verwaltung ihrer Modelle entlang des gesamten Lebenszyklus des Systems mit sich - von der Kundenakquise über Engineering und Rekonfiguration bis hin zum Systemrecycling. Der Digitale Zwilling ist ein Konzept, welches über den gesamten Lebenszyklus eines Assets hinweg das Management dieser Modelle sicherstellen kann. Es unterstützt jedoch nicht die automatisierte Modellerweiterung. Hier setzt diese Arbeit an. Die Anreicherung des Digitalen Zwillings um Modellverständnis und KI-Algorithmen zur eigenständigen Modellerweiterung bildet die Grundlager des vorgestellten Konzepts. Über die intelligente Auswertung der Informationsmodelle -angereichert mit aktuellen Prozessdaten- erkennt der Digitale Zwilling, wenn Modelle an ihre Grenzen stoßen. Zwei mögliche Ursachen für diesen Sachverhalt werden genauer betrachtet: (1) es fehlt eine Fähigkeit oder Information (2) der Gültigkeitsbereich des Modells wurde verlassen. Für beide Zustände wird ein Verfahren vorgeschlagen, welches auf Basis kooperativer Information aus dem Wertschöpfungsnetzwerk automatisiert eine Lösung findet. Die Evaluierung des Konzepts anhand eines Szenarios aus der Logistik und aus der Produktion liefert vielversprechende Ergebnisse.Item Open Access Mouse2Vec: learning reusable semantic representations of mouse behaviour(2024) Zhang, Guanhua; Hu, Zhiming; Bâce, Mihai; Bulling, AndreasThe mouse is a pervasive input device used for a wide range of interactive applications. However, computational modelling of mouse behaviour typically requires time-consuming design and extraction of handcrafted features, or approaches that are application-specific. We instead propose Mouse2Vec - a novel self-supervised method designed to learn semantic representations of mouse behaviour that are reusable across users and applications. Mouse2Vec uses a Transformer-based encoder-decoder architecture, which is specifically geared for mouse data: During pretraining, the encoder learns an embedding of input mouse trajectories while the decoder reconstructs the input and simultaneously detects mouse click events. We show that the representations learned by our method can identify interpretable mouse behaviour clusters and retrieve similar mouse trajectories. We also demonstrate on three sample downstream tasks that the representations can be practically used to augment mouse data for training supervised methods and serve as an effective feature extractor.Item Open Access Saliency3D: a 3D saliency dataset collected on screen(2024) Wang, Yao; Dai, Qi; Bâce, Mihai; Klein, Karsten; Bulling, AndreasWhile visual saliency has recently been studied in 3D, the experimental setup for collecting 3D saliency data can be expensive and cumbersome. To address this challenge, we propose a novel experimental design that utilizes an eye tracker on a screen to collect 3D saliency data. Our experimental design reduces the cost and complexity of 3D saliency dataset collection. We first collect gaze data on a screen, then we map them to 3D saliency data through perspective transformation. Using this method, we collect a 3D saliency dataset (49,276 fixations) comprising 10 participants looking at sixteen objects. Moreover, we examine the viewing preferences for objects and discuss our findings in this study. Our results indicate potential preferred viewing directions and a correlation between salient features and the variation in viewing directions.Item Open Access Layered symbolic security analysis in DY*(2023) Bhargavan, Karthikeyan; Bichhawat, Abhishek; Hosseyni, Pedram; Küsters, Ralf; Pruiksma, Klaas; Schmitz, Guido; Waldmann, Clara; Würtele, TimWhile cryptographic protocols are often analyzed in isolation, they are typically deployed within a stack of protocols, where each layer relies on the security guarantees provided by the protocol layer below it, and in turn provides its own security functionality to the layer above. Formally analyzing the whole stack in one go is infeasible even for semi-automated verification tools, and impossible for pen-and-paper proofs. The DY* protocol verification framework offers a modular and scalable technique that can reason about large protocols, specified as a set of F* modules. However, it does not support the compositional verification of layered protocols since it treats the global security invariants monolithically. In this paper, we extend DY* with a new methodology that allows analysts to modularly analyze each layer in a way that compose to provide security for a protocol stack. Importantly, our technique allows a layer to be replaced by another implementation, without affecting the proofs of other layers. We demonstrate this methodology on two case studies. We also present a verified library of generic authenticated and confidential communication patterns that can be used in future protocol analyses and is of independent interest.Item Open Access Designing for noticeability: understanding the impact of visual importance on desktop notifications(2022) Müller, Philipp; Staal, Sander; Bâce, Mihai; Bulling, AndreasDesktop notifications should be noticeable but are also subject to a number of design choices, e.g. concerning their size, placement, or opacity. It is currently unknown, however, how these choices interact with the desktop background and their influence on noticeability. To address this limitation, we introduce a software tool to automatically synthesize realistically looking desktop images for major operating systems and applications. Using these images, we present a user study (N=34) to investigate the noticeability of notifications during a primary task. We are first to show that visual importance of the background at the notification location significantly impacts whether users detect notifications. We analyse the utility of visual importance to compensate for suboptimal design choices with respect to noticeability, e.g. small notification size. Finally, we introduce noticeability maps - 2D maps encoding the predicted noticeability across the desktop and inform designers how to trade-off notification design and noticeability.Item Open Access A review of electromagnetic simulation and modelling approaches for the research on axial flux synchronous machines(2024) Schäfer, Adrian; Pecha, Urs; Parspour, Nejila; Kampker, Achim; Born, Henrik; Hartmann, Sebastian; Franke, Jörg; Baader, Marcel; Hahn, RomanExtensive electromagnetic (EMAG) studies are necessary to fully realize the potential of axial flux machines (AFMs). However, the disc-shaped air gap and the complex three-dimensional path of magnetic flux pose challenges in modelling AFMs compared to conventional radial flux machines. This study reviews current research on EMAG modelling and simulation of AFMs, highlighting the need for tools that address AFM-specific effects. Existing approaches are analysed based on the requirements composed by fundamental objectives of EMAG simulations and AFM-specific effects, revealing limitations in flexibility and the ability to capture emerging trends in the field of AFMs. While computationally expensive 3D finite element analysis (FEA) offers comprehensive flexibility in EMAG modelling, it lacks efficiency to carry out extensive studies on such trends. Therefore, there is a need to either further accelerate 3D FEA or to increase the flexibility of existing alternatives to facilitate and thereby promote research in the field of AFM and other 3D flux machines. While the integration of some production-specific effects, such as manufacturing tolerances, already is investigated for EMAG simulations of AFMs the future research on the early estimation of manufacturability based on EMAG simulations is crucial for evaluating designs and anticipating manufacturing influences.Item Open Access PrivacyScout: assessing vulnerability to shoulder surfing on mobile devices(2022) Bâce, Mihai; Saad, Alia; Khamis, Mohamed; Schneegass, Stefan; Bulling, AndreasOne approach to mitigate shoulder surfing attacks on mobile devices is to detect the presence of a bystander using the phone’s front-facing camera. However, a person’s face in the camera’s field of view does not always indicate an attack. To overcome this limitation, in a novel data collection study (N=16), we analysed the influence of three viewing angles and four distances on the success of shoulder surfing attacks. In contrast to prior works that mainly focused on user authentication, we investigated three common types of content susceptible to shoulder surfing: text, photos, and PIN authentications. We show that the vulnerability of text and photos depends on the observer’s location relative to the device, while PIN authentications are vulnerable independent of the observation location. We then present PrivacyScout – a novel method that predicts the shoulder-surfing risk based on visual features extracted from the observer’s face as captured by the front-facing camera. Finally, evaluations from our data collection study demonstrate our method’s feasibility to assess the risk of a shoulder surfing attack more accurately.Item Open Access Optimal transistor dimensioning in T-type topology for reduced quasi-2-level switching loss(2025) Söllner, Adrian; Jie, Chengcong; Mönch, StefanA quasi-2-level switching T-type topology reduces hard-switching loss compared to half-bridges, but requires more semiconductor area. This work shows that the middle transistor can be dimensioned smaller than the high/low-side transistors, which further reduces both the switch node capacitance and switching loss. The paper also presents a scalable transistor model, which is used in simulations of inductive-load hard-switching to determine switching losses and reveal a loss-optimal transistor dimensioning. Furthermore a double pulse setup (600 V-rated GaN HEMTs in a T-type topology) with 2 ground referenced shunts is proposed to determine switching energy of middle and low side transistors simultaneously. To verify the concept of loss-optimal transistor dimensioning in Q2L T-type topology, switching energy was measured at 200 V and 1 A, with the middle transistors area reduced by half compared to high/low side, resulting in a measured reduction from 4.44 µJ to 2.18 µJ (-51%) which is similar to the simulated reduction (2.39 µJ to 1.43 µJ, -40%). This method allows reduction of Q2L switching-loss with optimal transistor area and can be used for a wide range of applications.