Hochschule Bonn-Rhein-Sieg
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Sensory Monitoring and Analytical Study of Laser InitiatedGraphite-Coated TATP Using PTR-ToF-MS and Microphone
No full textZuverlässigkeitsbewertung metallischer Drahtverbindungen der Leistungselektronik
No full textOb in Windkraft-, Photovoltaikanlagen oder in der Elektromobilität – überall dort wo hohe Spannungen und Ströme transportiert werden müssen, sind Drahtverbindungen aus hochreinem Aluminium (Al-Gehalt mind. 99,99%) mit Durchmessern zwischen 125 μm und 500 μm unverzichtbar. Jährlich werden über 15 Trillionen Drahtbrücken in elektrischen Modulen verarbeitet. Im Betrieb müssen die Drähte wechselnde mechanische wie auch thermische Belastungen ertragen, die auf Dauer zu einem Ermüden der Drähte und damit zu einem Ausfall des Moduls führen können. Ziel der Promotion ist es daher ein Lebensdauermodell zu entwickeln mit dem die Zuverlässigkeit der Drähte vorhergesagt werden kann
Semantic composition of robotic solver algorithms on graph structures
No full textThis article introduces a model-based design, implementation, deployment, and execution methodology, with tools supporting the systematic composition of algorithms from generic and domain-specific computational building blocks that prevent code duplication and enable robots to adapt their software themselves. The envisaged algorithms are numerical solvers based on graph structures. In this article, we focus on kinematics and dynamics algorithms, but examples such as message passing on probabilistic networks and factor graphs or cascade control diagrams fall under the same pattern. The tools rely on mature standards from the Semantic Web. They first synthesize algorithms symbolically, from which they then generate efficient code. The use case is an overactuated mobile robot with two redundant arms
Zwischen Trends und Todesfällen: Eine explorative Analyse der Suchvorschläge auf TikTok
No full textDie vorliegende Masterarbeit untersucht die Funktion von TikTok als Suchmaschine und analysiert, welche Themen sich in den Suchvorschlägen der Plattform widerspiegeln. Ausgehend von der These, dass sich die Suchvorschläge aus tatsächlich getätigten Suchanfragen der Nutzer:innen ergeben, wird der Frage nachgegangen, welche Rückschlüsse sich aus diesen Vorschlägen auf Nutzer:inneninteressen und Plattformstrategien ziehen lassen. Der theoretische Teil der Arbeit gibt einen fundierten Überblick über relevante Konzepte aus der Informationswissenschaft und Suchmaschinenforschung. Dabei werden die Besonderheiten von TikTok als Plattform und Suchmaschine herausgearbeitet und im Kontrast zu klassischen Websuchmaschinen beleuchtet. Methodisch basiert die Untersuchung auf einer explorativen Analyse von 10.341 Suchvorschlägen mit 1.388 einzigartigen Begriffen, die über einen Zeitraum von zehn Wochen mithilfe einer TikTok-API erhoben wurden. Für die qualitative Auswertung wurde induktiv ein Kategoriensystem mit zwölf Oberkategorien entwickelt. Die Ergebnisse zeigen, dass die Nutzer:inneninteressen auf TikTok stark von Aktualität, Trendthemen und emotionalen Aspekten geprägt sind. Gleichzeitig gibt es Hinweise auf eine aktive Plattformsteuerung durch Hervorhebung oder Zurückhaltung bestimmter Themen.This Master's thesis examines the function of TikTok as a search engine and analyzes which topics are reflected in the platform's search suggestions. Based on the hypothesis that the search suggestions result from actual user queries, the question is explored as to what conclusions can be drawn from these suggestions about user interests and platform strategies. The theoretical part of the thesis provides a well-founded overview of relevant concepts from information science and search engine research. In the process, the specifics of TikTok as a platform and search engine are elaborated and examined in contrast to classical web search engines. Methodologically, the study is based on an exploratory analysis of 10,341 search suggestions with 1,388 unique terms collected over a period of ten weeks using a TikTok API. For the qualitative evaluation, a category system with twelve top-level categories was developed inductively. The results show that user interests on TikTok are strongly influenced by topicality, trending themes, and emotional aspects. At the same time, there are indications of active platform control through the emphasis or restraint of certain topics
Sensory Monitoring for Breakthrough Detection in Mobile Laser Cutting of Various Materials in the Context of Improvised Explosive Device Disposal
No full textUnattended luggage or containers in public areas, such as railway stations and buildings, like airports, may trigger bomb disposal operations. While these instances frequently involve harmless forgotten bags, they can also signal the presence of unconventional explosives and incendiary devices, which may include chemical, biological, radiological, nuclear, and explosive (CBRNe) elements. Research aspects of this work include the development of a mobile laser cutting system (LCS) to enhance the capabilities of police bomb disposal units in neutralizing improvised explosive devices (IEDs) and forensic evidence collection, thereby improving the safety of the public and defusing experts. This article presents the results of the development of a breakthrough detection system using an appropriate sensor technology. Parameters are determined by means of sensory monitoring to cut through various materials without interacting with the layer behind them. The investigation includes real cutting tests with the mobile LCS on various materials. For example, breakthrough times for polystyrene ranged from 75 to 250 s depending on geometry, while sensor accuracy in detecting cutting progress exceeded 90%. Additionally, explosive residues as low as 10 ng were successfully detected post-cutting, highlighting the system’s forensic compatibility. The results show that sensor-based breakthrough detection is feasible for the laser cutting of IED-relevant objects
Yeast complementation assays provide limited informationon functional features of K+ channels
No full textWe investigate to what extent yeast complementation assays, which in principle can provide large amounts of training data for machine learning models, yield quantitative correlations between growth rescue and single channel recordings. If this were the case, yeast complementation results could be used as surrogate data for machine learning-based channel design. Therefore, we mutated position L94 at the cavity entry of the model K+ channel KcvPBCV1 to all proteinogenic amino acids. The function of the WT channel and its mutants was investigated by reconstituting them in planar lipid bilayers and by their ability to rescue the growth of a yeast strain deficient in K+ uptake. The single channel data show a distinct effect of mutations in this critical position on unitary conductance and open probability, with no apparent causal relationship between the two functional parameters. We also found that even conservative amino acid replacements can alter the unitary conductance and/or open probability and that most functional changes show no systematic relationship with the physicochemical nature of the amino acids. This emphasizes that the functional influence of an amino acid on channel function cannot be reduced to a single chemical property. Mutual comparison of single channel data and yeast complementation results exhibit only a partial correlation between their electrical parameters and their potency of rescuing growth. Hence complementation data alone are not sufficient for enabling functional channel design; they need to be complemented by additional parameters like the number of channels in the plasma membrane
Comparison of Analytical and Finite Element Based Parameter Identification Methods for Electrical Machines
No full textProperties of Selenium under Tensile Stretch: A Molecular Dynamics Simulation
No full textSelenium is the third element of the group of chalcogens and is especially used in electrotechnical applications. Since many manufacturing processes use thin films of the material, knowledge of the mechanical properties is important for the detailed process layout. During the studies, the mechanical properties of trigonal selenium were determined. Therefore simulations of a uniaxial tensile test with a constant strain rate of 4.2⋅10–6/fs using molecular dynamic methods were performed. Finally a great dependency of the mechanical properties on temperature, direction and strain was observed. In particular, anisotropy in fracture behavior can be demonstrated. This can be explained by the anisotropy of trigonal selenium. In addition, a density distribution was calculated, showing that the mechanical properties are influenced by diffusion processes occurring at increased temperatures. The changes in dynamic processes point to a ductile-brittle transition
