05 Fakultät Informatik, Elektrotechnik und Informationstechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6
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Item Open Access Performance measurements for personalizable route planning for uncorrelated edge costs(2021) Bühler, FelixNowadays, ordinary route planners compute paths by choosing the shortest or fastest route. However, there exist additional metrics from which users with varying preferences could benefit. Personalized route planning offers the possibility to combine different metrics with personal preferences. Nevertheless, personalized route planning has mainly been tested with correlated metrics. But when including uncorrelated metrics, the computing time increases significantly. Previous work found that the speedup technique “Customizable Route Planning” can lead to feasible speedups for single metric calculations. Thus, in this work, we investigate how this speedup technique for Dijkstra improves the query performances of “Personalizable Route Planning” compared to “Personalizable Contraction Hierarchies”. Furthermore, we study the performances on uncorrelated metrics. We introduce a graph structure to compare the personalized speedup techniques “Personalizable Contraction Hierarchies”, “Personalizable Customizable Route Planning” and “Personalizable Route Planning”. Three graph partitioning algorithms have been implemented to realize “Customizable Route Planning”: K-means, Gonzales, and Merge. Our experiments show that Merge works well in combination with “Personalizable Contraction Hierarchies” preprocessing. We found that “Personalizable Customizable Route Planning” is a good alternative, as it uses much fewer edges for finding the costs of the shortest path. For uncorrelated metrics, “Personalizable Customizable Route Planning” and “Personalizable Route Planning” achieved speedups higher than “Personalizable Contraction Hierarchies”. Our contribution comprises a novel graph structure for comparing different Dijkstra variants. With our experiments, we provide a deeper understanding of the personalized route planning problem. Additionally, we propose improvements for “Personalizable Contraction Hierarchies” for less contracted graphs with uncorrelated metrics.Item Open Access Developing a multimodal feedback motion guidance system in VR for people with motion disabilities(2021) Wennrich, KevinMotion is an important aspect in the area of physiotherapy. The correctness of those motions is even more important, especially in the home exercises. In this thesis, the prototype of a multimodal guidance system in virtual reality, which tracks the movements of the users and compares it to the correct position in the field of physiotherapy exercises was created. The get the requirements for the system, people who needed to go to physiotherapy, because of an injury or a disability (stroke, MS, NPC), were interviewed, as well as a physiotherapist. Based on the results, we have implemented a virtual physiotherapist and the auditory guidance as two modalities. Further modalities have been the ghostarm and the haptic guidance as vibration bands. The prototype in which the user can choose and combine the guidances have been developed. The system, the modalities and its limits have been evaluated in a online study and a pilot study, with the results, that until now the ghostarm and virtual physiotherapist are the most liked guidances. A user study is planned for the future.Item Open Access A systematic mapping study on development and use of AI planning tools(2021) Philippsohn, RobertArtificial intelligence (AI) planning is a big area in the AI field with many needs and special problems. Therefore, it needs tools to suit these special problems and request, as well as for trends in the AI planning community. Since 1971 there has been an influx of many tools that assist insolving planning problems and making plans. To give a better overview of the available landscape of AI planning tools this systematic mapping study was conducted and try also to shows what software engineering principles are used in creating the tools. We also try to depict in which industry domains the AI planning tools are used and how many papers mention the tools being used in the industry. In the end, we conclude that there are at least 106 different tools out there, with only a fraction being used in the industry. While only a small part of the tools are talked about being used in the industry, this small part is covering a wide array of industry domains.Item Open Access Auslegung und Inbetriebnahme eines leistungsstarken und kompakten SiC Wechselrichters(2021) Volz, FredericDie vorliegende Arbeit befasst sich mit der Konzipierung, dem Aufbau und der Inbetriebnahme eines dreiphasigen Wechselrichters mit Leistungs-MOSFETs aus Siliziumkarbid, welcher die Lebensdaueruntersuchung unter realen Betriebsbedingungen ermöglichen soll. Der SiC Wechselrichter wird hierfür mit einem speziell für Lebensdaueruntersuchungen abgestimmten Kühlsystem ausgestattet. Im Rahmen der vorliegenden Masterarbeit findet die Integration des SiC Wechselrichters in einen Prüfstand mit einem ein- und ausgangsseitig gekoppelten Wechselrichter statt, welcher künftig als aktiver Power Cycling Prüfstand betrieben wird. Hierdurch wird eine gezielte Bauteilalterung unter realen Betriebsbedingungen ermöglicht.Item Open Access Development of an infrastructure for creating a behavioral model of hardware of measurable parameters in dependency of executed software(2021) Schwachhofer, DenisSystem-Level Test (SLT) gains traction not only in the industry but as of recently also in academia. It is used to detect manufacturing defects not caught by previous test steps. The idea behind SLT is to embed the Design Under Test (DUT) in an environment and running software on it that corresponds to its end-user application. But even though it is increasingly used in manufacturing since a decade there are still many open challenges to solve. For example, there is no coverage metric for SLT. Also, tests are not automatically generated but manually composed using existing operating systems and programs. This master thesis introduces the foundation for the AutoGen project, that will tackle the aforementioned challenges in the future. This foundation contains a platform for experiments and a workflow to generate Systems-on-Chip (SoCs). A case study is conducted to show an example on how on-chip sensors can be used in SLT applications to replace missing detailed technology-information. For the case study a “power devil” application has been developed that aims to keep the temperature of the Field Programmable Gate Array (FPGA) it runs on in a target range. The study shows an example on how software and parameters influence the extra-functional behavior of hardware.Item Open Access Question answering on knowledge bases : A comparative study(2021) Kanjur, VishnudathaQuestion Answering intends to automatically extract accurate and relevant information as the answer to a particular question. A large amount of data from the Web is stored as Knowledge bases in a structured way. Question answering on Knowledge bases is a research field that involves multiple branches of computer science like natural language processing, information retrieval and artificial intelligence. Knowledge Base Question Answering (KBQA) research involves various challenges to be solved in multiple aspects. This thesis aimed to compare several state-of-the-art methods for single relation KBQA. The widely used standard single relation dataset, SimpleQuestions dataset was used in the study against Freebase Knowledge Base (KB). A comprehensive analysis of the underlying models and their architecture was performed. Furthermore, to identify the drawbacks and possible enhancements, several approaches for evaluating the models were explored. The results show how the models were performed and the suitability of considering them for solving real-world problems in question answering.Item Open Access Top‐down approach to study chemical and electronic properties of perovskite solar cells : sputtered depth profiling versus tapered cross‐sectional photoelectron spectroscopies(2021) Das, Chittaranjan; Zia, Waqas; Mortan, Claudiu; Hussain, Navid; Saliba, Michael; Ingo Flege, Jan; Kot, MałgorzataA study of the chemical and electronic properties of various layers across perovskite solar cell (PSC) stacks is challenging. Depth‐profiling photoemission spectroscopy can be used to study the surface, interface, and bulk properties of different layers in PSCs, which influence the overall performance of these devices. Herein, sputter depth profiling (SDP) and tapered cross‐sectional (TCS) photoelectron spectroscopies (PESs) are used to study highly efficient mixed halide PSCs. It is found that the most used SDP‐PES technique degrades the organic and deforms the inorganic materials during sputtering of the PSCs while the TCS‐PES method is less destructive and can determine the chemical and electronic properties of all layers precisely. The SDP‐PES dissociates the chemical bonding in the spiro‐MeOTAD and perovskite layer and reduces the TiO2, which causes the chemical analysis to be unreliable. The TCS‐PES revealed a band bending only at the spiro‐MeOTAD/perovskite interface of about 0.7 eV. Both the TCS and SDP‐PES show that the perovskite layer is inhomogeneous and has a higher amount of bromine at the perovskite/TiO2 interface.Item Open Access Flutter on Windows Desktop: a use case based study(2021) Zindl, StefanIn the last years, the number of different computer platforms increased from Desktop, mobile devices, tablets to the Web. Among others, cross-platform frameworks enable to target all platforms. One of those cross-platform frameworks is Flutter which is developed by Google and targets Windows Desktop in beta stage since 2020. Because of this early stage, it is relevant to verify how well Flutter already works on Windows Desktop. In the first part of this bachelor thesis, we compare a simple image gallery in Flutter and WPF with .NET 5. The implementation in both frameworks worked well with similar kind of realization. Our comparison concentrates on metrics such as code, startup time, and packaged size. In addition, we measure RAM usage and CPU usage. We measure these in two scenarios which we automated with a simulation script. In the second part, we focus on the available third-party extensions and the current missing functionalities of the Flutter framework. Our results indicate that we could implement the Flutter application with 55% less code and with a 70 times faster startup time. Surprisingly, Flutter uses less RAM most of the time, but instead, it needs more CPU to process the images. Nevertheless, there are some missing important functionalities for Desktop applications such as adding icons in the system tray or adding a menubar to the application. We show that some functionality is still missing in the current stage of the Flutter framework, but it has a good chance to become a well established framework for new developers. Keywords: Desktop, WPF, Windows, Cross-Platform, Flutter, Use-Case StudyItem Open Access Automatic resource scaling in cloud applications - case study in cooperation with AEB SE(2021) Weiler, SimonAs an increasing number of applications continue to migrate into the cloud, the implementation of automatic scaling for computing resources to meet service-level objectives in a dynamic load environment is becoming a common challenge for software developers. To research how this problem can be tackled in practice, a state-of-the-art auto-scaling solution was developed and implemented in cooperation with AEB SE as a part of their application migration to a new Kubernetes cluster. Requirement elicitation was done via interviews with their development and IT operations staff, who put a strong focus on fast response times for automated requests as the main performance goal, with CPU, memory and response times being the most commonly used performance indicators for their systems. Using the collected knowledge, a scaling architecture was developed using their existing performance monitoring tools and Kubernetes' own Horizontal Pod Autoscaler, with a special adapter used for communicating the metrics between the two components. The system was tested on a deployment of AEB's test product using three different scaling approaches, using CPU utilization, JVM Memory usage and response time quantiles respectively. Evaluation results show that scaling approaches based on CPU utilization and memory usage are highly dependent on the type of requests and the implementation of the tested application, while response time-based scaling provides a more aggregated view on system performance and also reflects the actions of the scaler in its metrics. Overall though, the resulting performance was mostly the same for all scaling approaches, showing that the described architecture works in practice, but a more elaborate evaluation on a larger scale in a more optimized cluster would be needed to clearly distinguish between performances of different scaling strategies in a production environment.Item Open Access Neural Networks on Microsoft HoloLens 2(2021) Lazar, LéonThe goal of the present Bachelor thesis is to enable comparing different approaches of integrating Neural Networks in HoloLens 2 applications in a quantitative and qualitative manner by defining highly diagnostic criteria. Moreover, multiple different approaches to accomplish the integration are proposed, implemented and evaluated using the aforementioned criteria. Finally, the work gives an expressive overview of all working approaches. The basic requirements are that Neural Networks trained by TensorFlow/Keras can be used and executed directly on the HoloLens 2 without requiring an internet connection. Furthermore, the Neural Networks have to be integrable in Mixed/Augmented Reality applications. In total four approaches are proposed: TensorFlow.js, Unity Barracuda, TensorFlow.NET, and Windows Machine Learning which is an already existing approach. For each working approach a benchmarking application is developed which runs a common reference model on a test datatset to measure inference time and accuracy. Moreover, a small proof of concept application is developed in order to show that the approach also works with real Augmented Reality applications. The application uses a MobileNetV2 model to classify image frames coming from the webcam and displays the results to the user. All the feasible approaches are evaluated using the aforementioned evaluation criteria which include ease of implementation, performance, accuracy, compatibility with Machine Learning frameworks and pre-trained models, and integrability with 3D frameworks. The Barracuda, TensorFlow.js and WinML approaches turned out to be feasible. Barracuda, which only can be integrated in Unity applications, is the most performant framework since it can make use of GPU inference. After that follows TensorFlow.js which can be integrated in JavaScript Augmented Reality frameworks such as A-Frame. Windows ML can currently only use CPU inference on the HoloLens 2 and is therefore the slowest one. It can be integrated in Unity projects with some difficulties as well as plain Win32 and UWP apps. Barracuda and Windows Machine Learning are also integrated in a biomechanical visualization application based on Unity for performing simulations. The results of this thesis make the different approaches for integrating Neural Networks on the HoloLens 2 comparable. Now an informed decision which approach is the best for a specific application can be made. Furthermore, the work shows that the use of Barracuda or TensorFlow.js on the HoloLens 2 is feasible and superior compared to the existing WinML approach.