05 Fakultät Informatik, Elektrotechnik und Informationstechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6
Browse
272 results
Search Results
Item Open Access Modeling and timing analysis of micro-ROS application on an off-road vehicle control unit(2022) Bappanadu, Suraj RaoROS is known to be the most popular middleware for the development of software in modern day robots. It's next version, ROS 2 is highly modular and offers flexibility by supporting on microprocessors running desktop operating systems. Micro-ROS puts the major ROS 2 features on microcontrollers, i.e., highly resource-constrained computing devices running specialized real-time operating systems. ROS 2 is also of great importance for other domains, including autonomous driving and the off-road sector. Accordingly, there is significant interest in bringing micro-ROS to typical automotive control units. These embedded platforms support AUTOSAR Classic OSEK-like operating system which is very different in many aspects when compared to the platforms supported by micro-ROS. Some of the aspects have already been addressed in a previous work. This thesis mainly focuses on mapping the micro-ROS execution scheme to AUTOSAR scheme and dynamic memory management of the micro-ROS stack. From the micro-ROS architecture perspective, to successfully port the stack on an AUTOSAR-based ECU, the middleware and other layers of the stack are also analysed and adapted using a standard approach to support tasks-like execution model instead of threads-like execution model. Additionally, the support for standard CAN protocol based on custom transport configuration with the hardware CAN on the BODAS ECU is introduced. Model-based development methods have proven their utility in automotive industry. Therefore, we also focus on describing the timing properties of the micro-ROS stack in a model-based approach. We develop a generic model which is independent of a specific modeling language. In the next step, we realize the generic model using the widely used AMALTHEA language and analyse how well the developed model predicts the timing behavior of micro-ROS tasks. Finally, the effectiveness of the approach regarding timing and modeling is demonstrated with a micro-ROS test application first on Linux and then on the off-road vehicle control unit BODAS RC18-12/40 by Bosch Rexroth.Item Open Access Interdisciplinary composition of E-Learning platforms based on reusable low-code adapters(2022) Meißner, NiklasElectronic Learning (E-Learning) platforms or Learning Management Systems (LMSs) are becoming increasingly popular and, accordingly, are being used more and more by teachers at schools and university professors. They are used to digitally distribute educational material to students and provide the opportunity to, e.g., upload and collect assignments, solve tasks, and view grades. LMSs have been growing in popularity and are used alongside in-person lectures as an adjunct to self-study. Due to digital teaching during the COVID-19 pandemic, LMSs have increased in importance significantly. Even in after-pandemic times, with returning in-person lectures, it is hard to imagine teaching at universities without these platforms. The possibilities of working with the established LMSs are enormous. However, a closer look also reveals some negative aspects that were not considered in developing and using these platforms. The existing LMSs lack individualization for lecturers of their courses and a motivating design for students. Plugins attempt to remedy this, but they are complex and time-consuming to use. Thus, the underlying problems are, on the one hand, that lecturers are limited in the design of their courses and, on the other hand, that students experience disadvantages in terms of motivation and interactivity. This thesis aims to develop a concept for an e-learning platform that addresses these problems, supports lecturers in designing their courses, and motivates and assists students in learning. Under the aspect of generalization, a concept for a Software Product Line (SPL) was developed for the requirements of a wide variety of study programs, providing lecturers with a base platform and enabling them to use low-code adapters to design and modify their courses. In addition, the platform and a support team will assist lecturers in using the LMS and creating educational material. For the conceptual design of the LMS, some already existing solutions and approaches were examined to address a similar problem. However, similar problems have been insufficiently solved or overlap with the problem statement of this thesis only to a limited extent. After a requirements analysis, the requirements were gathered and listed so that solutions could then be developed. The prototypical implementation of the concept ’Interactive Training Remote Education Experience (IT-REX)’ was used to design the base e-learning platform and to include gamification aspects. However, since IT-REX was designed for computer science and software engineering students in the first semesters, it had to be modified for a broader range of uses. To evaluate the approach of the concept, a case study was conducted in which a low-fidelity prototype of the concept was presented to lecturers and other experts in the field of higher education didactics, learning psychology, and vocational and technical pedagogy. Subsequently, a questionnaire was used to assess and evaluate the previously defined requirements. The result of this elaboration is the concept for the e-learning platform with the corresponding prototype. Based on the feedback of the lecturers and experts, improvements and revisions could be identified. Furthermore, the evaluation helped to investigate how the platform’s usability could be enhanced to improve the structuring and design of the courses by the lecturers. Finally, future developments and further investigations based on the concept were described.Item Open Access Anonymisierung von Daten : von der Literatur zum Automobilbereich(2023) Herkommer, JanDie Datenanonymisierung im Automobilbereich gewinnt immer mehr an Bedeutung. Jedoch gibt es kaum Literatur und Ansätze, die sich mit der Anonymisierung von Automobildaten beschäftigen. In dieser Arbeit werden deshalb mit Hilfe einer strukturierten Literaturrecherche die aktuell verbreitetsten Verfahren und Anwendungsbereiche erörtert und die wichtigsten Erkenntnisse der Recherche zusammengefasst. So werden bei den analysierten Paper der Anwendungsbereich, die Methodik sowie der zu anonymisierende Datentyp ermittelt. DesWeiteren werden die Metriken zum Vergleich von unterschiedlichen Ansätzen betrachtet. Mit Hilfe dieser Erkenntnisse wird im Anschluss auf die Anonymisierung von Fahrzeugdaten anhand verschiedener Anwendungsfälle eingegangen und Herausforderungen und Lösungsansätze skizziert. Zuletzt wird beispielhaft ein Ansatz zur Anonymisierung von Routen implementiert, um mit Hilfe eines GPS-Sensors aufgezeichnete Fahrzeugrouten zu anonymisieren. Dabei werden zusätzliche Probleme wie der Umgang mit Messungenauigkeiten und Messfehlern sowie die tatsächlichen Auswirkungen von reduzierter Datennutzbarkeit verdeutlicht.Item Open Access Development of an Euler-Lagrangian framework for point-particle tracking to enable efficient multiscale simulations of complex flows(2023) Kschidock, HelenaIn this work, we implement, test, and validate an Euler-Lagrangian point-particle tracking framework for the commercial aerodynamics and aeroacoustics simulation tool ultraFluidX, which is based on the Lattice Boltzmann Method and optimized for GPUs. Our framework successfully simulates one-way and two-way coupled particle-laden flows based on drag forces and gravitation. Trilinear interpolation is used for determining the fluid's macroscopic properties at the particle position. Object and domain boundary conditions are implemented using a planar surface approximation. The whole particle framework is run within three dedicated GPU kernels, and data is only copied back to the CPU upon output. We show validation for the velocity interpolation, gravitational acceleration, back-coupling forces and boundary conditions, and test runtimes and memory requirements. We also propose the next steps required to make the particle framework ready for use in engineering applications.Item Open Access Migration monolithischer Anwendungen in Microservices-basierte Architekturen : Fallstudie einer Service/Sales-Applikation(2023) Knodel, MarvinViele Altsysteme in der Industrie sind heutzutage in einer monolithischen Architektur implementiert. Manche Unternehmen setzen darauf ihre großen Applikationen in eine Microservices-Architektur zu migrieren, da sie sich hiervon viele Vorteile versprechen. So ist auch das Unternehmen L-mobile aus Sulzbach an der Murr dazu gewillt ihre Service/Sales-Applikation auf einen möglichen Microservices-Betrieb hin zu führen. Da es viele Ansätze gibt einen Monolithen in eine Microservices Applikation zu migrieren, hat die Abteilung Empirical Software Engineering des Institute of Software Engineering der Universität Stuttgart ein Framework für die Microservices Migration entwickelt, welches insbesondere Ansätze aus dem wissenschaftlichen Umfeld beinhaltet. Mithilfe dieses Frameworks wird in dieser Arbeit eine Teilmigration der Service/Sales-Applikation von L-mobile im Rahmen eines Proof of Concept durchgeführt. Dafür wurde zuerst eine Literaturrecherche durchgeführt um die Grundlagen von Monolithen, Microservices und dahingehende Migrationen im Allgemeinen zu erörtern. Anschließend wurde das Framework für Microservices Migration, für eine Teilmigration der Service/Sales-Applikation, durchgeführt. In dieser Durchführung wurde ein Service-Identifikationsansatz und eine Migrationsstrategie für die Applikation von L-mobile durch das Framework empfohlen. Während der Migration sind auch Herausforderungen aufgetreten. Einige der aufgetretene Herausforderungen wie die Migration der Datenbank werden auch in der wissenschaftlichen Literatur genannt, andere Herausforderungen, wie mangelnde Erfahrung mit Architekturbewertungen und der Implementierung von Microservices sind L-mobile spezifische Herausforderungen. Durch das Erheben strukturierter Feldnotizen während der Anwendung des Frameworks und durch verschiedene Reviews nach der Migration wurde das Framework hinsichtlich seiner Eignung für die Migration der Service/Sales-Applikation geprüft. Diese Evaluation ergab, dass sich das Framework für die Migration im Rahmen des Proof of Concept geeignet hat, da es umfangreich durch die Migration führt, eine Architekturbewertung berücksichtigt, geeignete Methoden für die Service-Identifizierung und Migration vorschlägt und durch das Vorschlagen von Patterns und Best Practices bei der Erstellung der Architektur unterstützt. Das Framework eignet sich auch für die komplette Migration der Service/Sales-ApplikationItem Open Access Migrating monolithic architectures to microservices : a study on software quality attributes(2022) Koch, DanielEs gibt viele Beweggründe für die Migration von einer monolithischen zu einer Microservice-Architektur, z. B. hohe Skalierbarkeit oder verbesserte Wartbarkeit. Dabei müssen jedoch mehrere Faktoren im Migrationsprozess berücksichtigt werden, darunter auch Qualitätsmerkmale. Da die Migration zu einer Microservice-Architektur keine einfache Aufgabe ist, können definierte Qualitätsziele dabei helfen, einen geeigneten Migrationsansatz auszuwählen und anschließend geeignete Architekturentscheidungen zu treffen. Ziel dieser Arbeit ist es, zu untersuchen, wie Qualitätsattribute in den Migrationsprozess eingebunden werden können, um Praktiker und Softwarearchitekten dabei zu unterstützen. Ebenso wird untersucht, welche Rolle sie im Migrationsprozess spielen. Dazu wurde zunächst eine Literaturrecherche durchgeführt, um die Qualitätsattribute zu identifizieren, die für eine Microservice-Architektur relevant sind. Anschließend wurden die Qualitätsattribute den Migrationsansätzen zugeordnet, die sie in Richtung der Zielarchitektur optimieren. Ebenso wurden die Qualitätsattribute den Architekturmustern und Best Practices zugeordnet. Auf der Grundlage der zuvor gesammelten Ergebnisse wurde ein Qualitätsmodell erstellt, das auch die Interdependenzen und Kompromisse zwischen ihnen berücksichtigt. Auf diese Weise soll das Qualitätsmodell als Leitfaden dienen, der die Auswahl geeigneter Techniken und architektonischer Entscheidungen auf der Grundlage der definierten Qualitätsziele erleichtert. Das entwickelte Qualitätsmodell wurde anschließend in ein Tool integriert, das Praktiker durch den Migrationsprozess leiten sollte. Um die Nutzbarkeit des Werkzeugs in Bezug auf das Qualitätsmodell zu untersuchen, wurde eine Evaluierung in Form einer Umfrage mit vier Praktikern aus der Industrie durchgeführt. Das Ergebnis der Evaluation zeigt, dass das integrierte Qualitätsmodell den Migrationsprozess auf Basis der definierten Qualitätsziele in der Praxis unterstützen kann und die Erweiterung des Tools eine hohe Usability aufweist.Item Open Access Bimodal taint analysis for detecting unusual parameter-sink flows(2022) Chow, Yiu WaiFinding vulnerabilities is a crucial activity, and automated techniques for this purpose are in high demand. For example, the Node Package Manager (npm) offers a massive amount of software packages, which get installed and used by millions of developers each day. Because of the dense network of dependencies between npm packages, vulnerabilities in individual packages may easily affect a wide range of software. Taint analysis is a powerful tool to detect such vulnerabilities. However, it is challenging to clearly define a problematic flow. A possible way to identify problematic flows is to incorporate natural language information like code convention and informal knowledge into the analysis. For example, a user might not find it surprising that a parameter named cmd of a function named execCommand is open to command injection. Thus this flow is likely unproblematic as the user will not pass untrusted data to cmd. In contrast, a user might not expect a parameter named value of a function named staticSetConfig to be vulnerable to command injection. Thus this flow is likely problematic as the user might pass untrusted data to value, since the natural language information from the parameter and function name suggests a different security context. To effectively exploit the implicit information in code, we introduce a bimodal taint analysis tool, Fluffy. The first modality is code: Fluffy uses a mining analysis implemented in CodeQL to find examples of flows from parameters to vulnerable sinks. The second modality is natural language: Fluffy uses a machine learning model that, based on a corpus of such examples, learns how to distinguish unexpected flows from expected flows using natural language information. We instantiate four neural models, offering different trade-offs between manual efforts required and accuracy of predictions. In our evaluation, Fluffy is able to achieve a F1-score of 0.85 or more on four common vulnerability types. In addition, Fluffy is able to flag eleven previously unknown vulnerabilities in real-life projects, of which six are confirmed.Item Open Access Industry practices and challenges of using AI planning : an interview-based study(2024) Vashisth, DhananjayIn the rapidly evolving landscape of industrial applications, AI planning systems have emerged as critical tools for optimizing processes and decision-making. However, implementing and integrating these systems present significant challenges that can hinder their effectiveness. This thesis addresses the urgent need to understand the best practices and challenges involved in designing, integrating, and deploying AI planning systems in industrial settings. Without this understanding, industries risk inefficient implementation, leading to poor performance and resistance from end-users. This research employs a methodology that includes a literature review and interviews with industry professionals and researchers to identify common strategies and obstacles practitioners face. The study examines existing literature to uncover reported best practices and challenges in AI planning systems. Interviews provide additional perspectives, enriching the data collected and ensuring a thorough analysis. The findings reveal best practices, including the importance of cross-disciplinary collaboration, robust data management strategies, and iterative development processes. Additionally, recurring challenges such as integration complexities, scalability issues, and the need for continuous system evaluation are identified. These insights highlight critical areas for improvement and offer practical recommendations for enhancing the effectiveness of AI planning systems in industrial applications.Item Open Access Adaptive robust scheduling in wireless Time-Sensitive Networks (TSN)(2024) Egger, SimonThe correct operation of upper-layer services is unattainable in wireless Time-Sensitive Networks (TSN) if the schedule cannot provide formal reliability guarantees to each stream. Still, current TSN scheduling literature leaves reliability, let alone provable reliability, either poorly quantified or entirely unaddressed. This work aims to remedy this shortcoming by designing an adaptive mechanism to compute robust schedules. For static wireless channels, robust schedules enforce the streams' reliability requirements by allocating sufficiently large wireless transmission intervals and by isolating omission faults. While robustness against omission faults is conventionally achieved by strictly isolating each transmission, we show that controlled interleaving of wireless streams is crucial for finding eligible schedules. We adapt the Disjunctive Graph Model (DGM) from job-shop scheduling to design TSN-DGM as a metaheuristic scheduler that can schedule up to one hundred wireless streams with fifty cross-traffic streams in under five minutes. In comparison, we demonstrate that strict transmission isolation already prohibits scheduling a few wireless streams. For dynamic wireless channels, we introduce shuffle graphs as a linear-time adaptation strategy that converts reliability surpluses from improving wireless links into slack and reliability impairments from degrading wireless links into tardiness. While TSN-DGM is able to improve the adapted schedule considerably within ten seconds of reactive rescheduling, we justify that the reliability contracts between upper-layer services and the infrastructure provider should specify a worst-case channel degradation beyond which no punctuality guarantees can be made.Item Open Access Analysis of political positioning from politician’s tweets(2023) Maurer, Maximilian MartinSocial media platforms such as Twitter have become important communication channels for politicians to interact with the electorate and communicate their stances on policy issues. In contrast to party manifestos, which lay out curated, compromised positions, the full range of positions within the ideological bounds of a party can be found on social media. This begs the question of how aligned the ideological positions of parties on social media are with their respective manifesto. To assess the alignment of social media and manifesto positions, we correlate the positions automatically retrieved from the tweets with manifesto-based positions for the German federal elections of 2017 and 2021. Additionally, we assess whether the change in positions over time is aligned between social media and manifestos. We retrieve ideological positions by aggregating distances between parties from sentence representations of their members' tweets from a corpus containing >2M individual tweets of 421 German politicians. We leverage domain-specific information by training a sentence embedding model such that representations of tweets with co-occurring hashtags are closer to each other than ones without co-occurring hashtags, following the assumption that hashtags approximate policy-related topics. Our experiments compare this political social media domain-specific model with other political domain and general domain sentence embedding models. We find high, significant correlations between the Twitter-retrieved positions and manifesto positions, especially for our domain-specific fine-tuned model. Moreover, for this model, we find overlaps in terms of how the positions change over time. These results indicate that the ideological positions of parties on Twitter correspond to the ideological positions as laid out in the manifestos to a large extent.