05 Fakultät Informatik, Elektrotechnik und Informationstechnik

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6

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Publication Type: search.filters.UBSTyp.KonferenzbeitragStart date: 2010End date: 2019

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Now showing 1 - 10 of 51
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    Precise voltage measurement for power electronics with high switching frequencies
    (2018) Nitzsche, Maximilian; Zehelein, Matthias; Tröster, Nathan; Roth-Stielow, Jörg
    In this paper different approaches in precise measurement of gate voltages as well as drain-source voltages of modern SiC and GaN transistors are compared. An approach to calculate the necessary bandwidth of a voltage probe to reproduce the voltage slope is presented. Furthermore, state-of-the-art voltage probes are compared in means of bandwidth, common mode reduction and response on EMI.
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    Mining Java packages for developer profiles : an exploratory study
    (2017) Ramadani, Jasmin; Wagner, Stefan
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    Synchronisierung von digitalen Modellen mit realen Fertigungszellen auf Basis einer Ankerpunktmethode am Beispiel der Automobilindustrie
    (2017) Ashtari Talkhestani, Behrang; Schlögl, Wolfgang; Weyrich, Michael
    Die zunehmende Produktvielfalt und die Verkürzung der Produktlebenszyklen erfordern eine schnelle und kostengünstige Rekonfiguration bestehender Produktionssysteme [1]. Um diesen Herausforderungen zu begegnen, ist ein aktuelles digitales Modell der bestehenden Fertigungszelle, im Folgenden Digitaler Zwilling genannt, eine geeignete Lösung. Der Digitale Zwilling führt zu einer Kostenreduktion durch Verkürzung der Umrüstzeiten durch virtuelle Planung und Simulation basierend auf dem aktuellen Zustand der realen Produktionsanlage als auch durch eine frühzeitige Erkennung von Konstruktions- oder Prozessablauffehlern in der Produktionsanlage. Voraussetzung für die Verwendbarkeit des Digitalen Zwillings vom Produktionssystem ist allerdings, dass ein aktuelles (virtuelles) Anlagenmodell von den mechatronischen Bestandteilen der realen Anlage während der verschiedenen Phasen ihres Lebenszyklus existiert. In diesem Beitrag wird die domänenübergreifende, mechatronische Datenstruktur der virtuellen Fertigungszellen in der Automobilindustrie diskutiert. Es wird eine systematische Ankerpunktmethode vorgestellt, mithilfe derer die Abweichungen zwischen den virtuellen Modellen und der Realität detektiert und ermittelt werden können. Basierend darauf wird eine sogenannte regelbasierte Konsistenzprüfung zur durchgängigen, domänenübergreifenden Synchronisierung der aktuellen mechatronischen Ressourcenkomponenten der Produktionssysteme mit deren virtuellem Anlagemodell vorgestellt.
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    Scrum for cyber-physical systems: a process proposal
    (2014) Wagner, Stefan
    Agile development processes and especially Scrum are chang- ing the state of the practice in software development. Many companies in the classical IT sector have adopted them to successfully tackle various challenges from the rapidly changing environments and increasingly complex software systems. Companies developing software for embedded or cyber-physical systems, however, are still hesitant to adopt such processes. Despite successful applications of Scrum and other agile methods for cyber-physical systems, there is still no complete process that maps their specific challenges to practices in Scrum. We propose to fill this gap by treating all design artefacts in such a development in the same way: In software development, the final design is already the product, in hardware and mechanics it is the starting point of production. We sketch the Scrum extension Scrum CPS by showing how Scrum could be used to develop all design artefacts for a cyber physical system. Hardware and mechanical parts that might not be available yet are simulated. With this approach, we can directly and iteratively build the final software and produce detailed models for the hardware and mechanics production in parallel. We plan to further detail Scrum CPS and apply it first in a series of student projects to gather more experience before testing it in an industrial case study.
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    Dynamic ontology supported user interface for personalized decision support
    (2012) Bosch, Harald; Thom, Dennis; Heinze, Geoffrey-Alexeij; Wokusch, Stefan; Ertl, Thomas
    European citizens are increasingly aware of the influence of air quality and weather on their health and quality of life. At the same time, more environmental information is freely available through a plethora of websites, dedicated portals, and web services. In order to exploit these data for personal decisions one has to identify, retrieve, and combine the information that is relevant to one's personal situation, planned activity, and information need. Often, this task is hindered by different data formats, display styles and data resolutions. The PESCaDO system is a web-based decision support system addressing this issue. The inquiry to the system, as well as the system's result, can cover a broad range of environmental aspects and personal situations and is therefore quite complex. In this work we present a novel approach on how the system can actively assist users in all steps of the decision making process, especially by enhancing the user interaction. This approach combines an intelligent dialog steering method based on analyzing the domain ontology with flexible, dynamic data visualizations for a situation depending orchestration of data sources. Both aspects have been evaluated in on-line user studies, as well as with an expert evaluation of the whole system.
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    Maschinelles Lernen für intelligente Automatisierungssysteme mit dezentraler Datenhaltung am Anwendungsfall Predictive Maintenance
    (2019) Maschler, Benjamin; Jazdi, Nasser; Weyrich, Michael
    Für eine hohe Ergebnisqualität sind Machine Learning Algorithmen auf eine breite Datenbasis angewiesen. Studien zeigen jedoch, dass viele Unternehmen nicht bereit sind, ihre Daten mit anderen Unternehmen, beispielsweise in Form einer gemeinsamen Daten-Cloud, zu teilen. Ziel sollte es daher sein, effizientes maschinelles Lernen mit einer dezentralen Datenhaltung, die den Verbleib vertraulicher Daten im jeweiligen Ursprungs-Unternehmen ermöglicht, zu ermöglichen. In diesem Artikel wird diesbezüglich ein neuartiges Konzept vorgestellt und hinsichtlich seiner Potentiale für intelligente Automatisierungssysteme am Beispiel des Anwendungsfalls Predictive Maintenance analysiert. Die Umsetzbarkeit des Konzepts unter Nutzung verschiedener bestehender Ansätze wird diskutiert, bevor schließlich auf potentielle Mehrwerte für Anlagenbetreiber sowie -hersteller unter besonderer Berücksichtigung der Perspektive kleiner und mittlerer Unternehmen eingegangen wird.
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    The Quamoco product quality modelling and assessment approach
    (2012) Wagner, Stefan; Lochmann, Klaus; Heinemann, Lars; Kläs, Michael; Trendowicz, Adam; Plösch, Reinhold; Seidl, Andreas; Goeb, Andreas; Streit, Jonathan
    Published software quality models either provide abstract quality attributes or concrete quality assessments. There are no models that seamlessly integrate both aspects. In the project Quamoco, we built a comprehensive approach with the aim to close this gap. For this, we developed in several iterations a meta quality model specifying general concepts, a quality base model covering the most important quality factors and a quality assessment approach. The meta model introduces the new concept of a product factor, which bridges the gap between concrete measurements and abstract quality aspects. Product factors have measures and instruments to operationalise quality by measurements from manual inspection and tool analysis. The base model uses the ISO 25010 quality attributes, which we refine by 200 factors and 600 measures for Java and C# systems. We found in several empirical validations that the assessment results fit to the expectations of experts for the corresponding systems. The empirical analyses also showed that several of the correlations are statistically significant and that the maintainability part of the base model has the highest correlation, which fits to the fact that this part is the most comprehensive. Although we still see room for extending and improving the base model, it shows a high correspondence with expert opinions and hence is able to form the basis for repeatable and understandable quality assessments in practice.
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    XSTAMPP: An eXtensible STAMP platform as tool support for safety engineering
    (2015) Abdulkhaleq, Asim; Wagner, Stefan
    STPA (Systems-Theoretic Processes Analysis) is a new hazard analysis technique based on STAMP. STPA is already being used in different industrial domains (e.g. space, aviation, medical or automotive). To support the application of STPA and make using STPA more efficient, we developed an open tool called A-STPA. However, the current usage of ASTPA by safety analysts in different areas shows a number of shortcomings in terms of documenting unsafe control actions, drawing different levels of control structure diagrams, documenting the causal factors in STPA Step 2 and supporting the application of STPA in different areas. In this paper, we present an extensible STAMP platform called XSTAMPP as tool support designed specifically to serve the widespread adoption and use of STPA in different areas, to facilitate STPA application to different systems and to be easily extended to include different requirements and features. Moreover, XSTAMPP has the potential to be extended in the future to support the application of CAST for accident analysis. We believe that XSTAMPP is a useful first step toward establishing a base platform to support the application of STAMP methodologies in different domains.
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    Mining valence, arousal, and dominance - possibilities for detecting burnout and productivity?
    (2016) Mäntylä, Mika; Adams, Bram; Destefanis, Giuseppe; Graziotin, Daniel; Ortu, Marco
    Similar to other industries, the software engineering domain is plagued by psychological diseases such as burnout, which lead developers to lose interest, exhibit lower activity and/or feel powerless. Prevention is essential for such diseases, which in turn requires early identification of symptoms. The emotional dimensions of Valence, Arousal and Dominance (VAD) are able to derive a person's interest (attraction), level of activation and perceived level of control for a particular situation from textual communication, such as emails. As an initial step towards identifying symptoms of productivity loss in software engineering, this paper explores the VAD metrics and their properties on 700,000 Jira issue reports containing over 2,000,000 comments, since issue reports keep track of a developer's progress on addressing bugs or new features. Using a general-purpose lexicon of 14,000 English words with known VAD scores, our results show that issue reports of different type (e.g., Feature Request vs. Bug) have a fair variation of Valence, while increase in issue priority (e.g., from Minor to Critical) typically increases Arousal. Furthermore, we show that as an issue's resolution time increases, so does the arousal of the individual the issue is assigned to. Finally, the resolution of an issue increases valence, especially for the issue Reporter and for quickly addressed issues. The existence of such relations between VAD and issue report activities shows promise that text mining in the future could offer an alternative way for work health assessment surveys.