TY - CONF
AB - The creation of an RDF knowledge graph for a particular application commonly involves a pipeline of tools that transform a set ofinput data sources into an RDF knowledge graph in a process called dataset augmentation. The components of such augmentation pipelines often require extensive configuration to lead to satisfactory results. Thus, non-experts are often unable to use them. Wepresent an efficient supervised algorithm based on genetic programming for learning knowledge graph augmentation pipelines of arbitrary length. Our approach uses multi-expression learning to learn augmentation pipelines able to achieve a high F-measure on the training data. Our evaluation suggests that our approach can efficiently learn a larger class of RDF dataset augmentation tasks than the state of the art while using only a single training example. Even on the most complex augmentation problem we posed, our approach consistently achieves an average F1-measure of 99% in under 500 iterations with an average runtime of 16 seconds
AU - Dreßler, Kevin
AU - Sherif, Mohamed
AU - Ngonga Ngomo, Axel-Cyrille
ID - 31806
KW - 2022 RAKI SFB901 deer dice kevin knowgraphs limes ngonga sherif simba
T2 - Proceedings of the 33rd ACM Conference on Hypertext and Hypermedia
TI - ADAGIO - Automated Data Augmentation of Knowledge Graphs Using Multi-expression Learning
ER -
TY - JOUR
AU - Redder, Adrian
AU - Ramaswamy, Arunselvan
AU - Karl, Holger
ID - 32854
IS - 13
JF - IFAC-PapersOnLine
TI - Practical Network Conditions for the Convergence of Distributed Optimization
VL - 55
ER -
TY - CONF
AU - Hansmeier, Tim
AU - Brede, Mathis
AU - Platzner, Marco
ID - 33253
T2 - GECCO '22: Proceedings of the Genetic and Evolutionary Computation Conference Companion
TI - XCS on Embedded Systems: An Analysis of Execution Profiles and Accelerated Classifier Deletion
ER -
TY - CONF
AU - Chen, Wei-Fan
AU - Chen, Mei-Hua
AU - Mudgal, Garima
AU - Wachsmuth, Henning
ID - 33274
T2 - Proceedings of the 9th Workshop on Argument Mining (ArgMining 2022)
TI - Analyzing Culture-Specific Argument Structures in Learner Essays
ER -
TY - CONF
AU - Maack, Marten
AU - Pukrop, Simon
AU - Rasmussen, Anna Rodriguez
ED - Chechik, Shiri
ED - Navarro, Gonzalo
ED - Rotenberg, Eva
ED - Herman, Grzegorz
ID - 33491
T2 - 30th Annual European Symposium on Algorithms, ESA 2022, September 5-9, 2022, Berlin/Potsdam, Germany
TI - (In-)Approximability Results for Interval, Resource Restricted, and Low Rank Scheduling
VL - 244
ER -
TY - GEN
AB - We study the consequences of modeling asymmetric bargaining power in two-person bargaining problems. Comparing application of an asymmetric version of a bargaining solution to an upfront modification of the disagreement point, the resulting distortion crucially depends on the bargaining solution concept. While for the Kalai-Smorodinsky solution weaker players benefit from modifying the disagreement point, the situation is reversed for the Nash bargaining solution. There, weaker players are better off in the asymmetric bargaining solution. When comparing application of the asymmetric versions of the Nash and the Kalai-Smorodinsky solutions, we demonstrate that there is an upper bound for the weight of a player, so that she is better off with the Nash bargaining solution. This threshold is ultimately determined by the relative utilitarian bargaining solution. From a mechanism design perspective, our results provide valuable information for a social planner, when implementing a bargaining solution for unequally powerful players.
AU - Haake, Claus-Jochen
AU - Streck, Thomas
ID - 32106
KW - Asymmetric bargaining power
KW - Nash bargaining solution
KW - Kalai-Smorodinsky bargaining solution
TI - Distortion through modeling asymmetric bargaining power
VL - 148
ER -
TY - GEN
AU - Grynko, Yevgen
AU - Shkuratov, Yuriy
AU - Alhaddad, Samer
AU - Förstner, Jens
ID - 34136
KW - tet_topic_scattering
TI - Light backscattering from numerical analog of planetary regoliths
ER -
TY - JOUR
AB - How can Knowledge In/Equity be addressed in qualitative research by taking the idea of Open Science into account? Two projects from the Open Science Fellows Programme by Wikimedia Deutschland will be used to illustrate how Open Science practices can succeed in qualitative research, thereby reducing In/Equity. In this context, In/Equity is considered as a fair and equal representation of people, their knowledge and insights and comprehends questions about how epistemic, structural, institutional and personal biases generate and shape knowledge as guidance. Three questions guide this approach: firstly, what do we understand by In/Equity in the context of knowledge production in these projects? Secondly, who will be involved in knowledge generation and to what extent will they be valued or unvalued? Thirdly, how can data be made accessible for re-use to enable true participation and sharing?
AU - Steinhardt, Isabel
AU - Kruschick, Felicitas
ID - 34132
JF - Research Ideas and Outcomes
KW - Open Science
KW - Knowledge Equity
KW - Qualitative Methods
SN - 2367-7163
TI - Knowledge Equity and Open Science in qualitative research – Practical research considerations
VL - 8
ER -
TY - JOUR
AB - Subwavelength dielectric resonators assembled into metasurfaces have become a versatile tool for miniaturizing optical components approaching the nanoscale. An important class of metasurface functionalities is associated with asymmetry in both the generation and transmission of light with respect to reversals of the positions of emitters and receivers. The nonlinear light–matter interaction in metasurfaces offers a promising pathway towards miniaturization of the asymmetric control of light. Here we demonstrate asymmetric parametric generation of light in nonlinear metasurfaces. We assemble dissimilar nonlinear dielectric resonators into translucent metasurfaces that produce images in the visible spectral range on being illuminated by infrared radiation. By design, the metasurfaces produce different and completely independent images for the reversed direction of illumination, that is, when the positions of the infrared emitter and the visible light receiver are exchanged. Nonlinearity-enabled asymmetric control of light by subwavelength resonators paves the way towards novel nanophotonic components via dense integration of large quantities of nonlinear resonators into compact metasurface designs.
AU - Kruk, Sergey S.
AU - Wang, Lei
AU - Sain, Basudeb
AU - Dong, Zhaogang
AU - Yang, Joel
AU - Zentgraf, Thomas
AU - Kivshar, Yuri
ID - 32088
JF - Nature Photonics
KW - Atomic and Molecular Physics
KW - and Optics
KW - Electronic
KW - Optical and Magnetic Materials
SN - 1749-4885
TI - Asymmetric parametric generation of images with nonlinear dielectric metasurfaces
VL - 16
ER -
TY - CONF
AB - In this paper, machine learning techniques will be used to classify different PCB layouts given their electromagnetic frequency spectra. These spectra result from a simulated near-field measurement of electric field strengths at different locations. Measured values consist of real and imaginary parts (amplitude and phase) in X, Y and Z directions. Training data was obtained in the time domain by varying transmission line geometries (size, distance and signaling). It was then transformed into the frequency domain and used as deep neural network input. Principal component analysis was applied to reduce the sample dimension. The results show that classifying different designs is possible with high accuracy based on synthetic data. Future work comprises measurements of real, custom-made PCB with varying parameters to adapt the simulation model and also test the neural network. Finally, the trained model could be used to give hints about the error’s cause when overshooting EMC limits.
AU - Maalouly, Jad
AU - Hemker, Dennis
AU - Hedayat, Christian
AU - Rückert, Christian
AU - Kaufmann, Ivan
AU - Olbrich, Marcel
AU - Lange, Sven
AU - Mathis, Harald
ID - 34140
KW - emc
KW - pcb
KW - electronic system development
KW - machine learning
KW - neural network
T2 - 2022 Kleinheubach Conference
TI - AI Assisted Interference Classification to Improve EMC Troubleshooting in Electronic System Development
ER -
TY - CHAP
AU - Hagengruber, Ruth Edith
ED - Banse, Gerhard
ED - Fuchs-Kittowski, Klaus
ID - 34108
T2 - Sitzungsberichte der Leibniz-Sozietät der Wissenschaften 150/151, Jahrgang 2022: „Cyberscience – Wissenschaftsforschung und Informatik. Digitale Medien und die Zukunft der Kultur wissenschaftlicher Tätigkeit. Arbeitskreis „Emergente Systeme/Informatik und Gesellschaft“ der Leibniz-Sozietät der Wissenschaften zu Berlin in Kooperation mit der Gesellschaft für Wissenschaftsforschung“
TI - Die „dritte Wissensdimension“. Eine Epistemologie für eine neue Wissenswelt
ER -
TY - CHAP
AB - This work addresses the automatic resolution of software requirements. In the vision of On-The-Fly Computing, software services should be composed on demand, based solely on natural language input from human users. To enable this, we build a chatbot solution that works with human-in-the-loop support to receive, analyze, correct, and complete their software requirements. The chatbot is equipped with a natural language processing pipeline and a large knowledge base, as well as sophisticated dialogue management skills to enhance the user experience. Previous solutions have focused on analyzing software requirements to point out errors such as vagueness, ambiguity, or incompleteness. Our work shows how apps can collaborate with users to efficiently produce correct requirements. We developed and compared three different chatbot apps that can work with built-in knowledge. We rely on ChatterBot, DialoGPT and Rasa for this purpose. While DialoGPT provides its own knowledge base, Rasa is the best system to combine the text mining and knowledge solutions at our disposal. The evaluation shows that users accept 73% of the suggested answers from Rasa, while they accept only 63% from DialoGPT or even 36% from ChatterBot.
AU - Kersting, Joschka
AU - Ahmed, Mobeen
AU - Geierhos, Michaela
ED - Stephanidis, Constantine
ED - Antona, Margherita
ED - Ntoa, Stavroula
ID - 32179
KW - On-The-Fly Computing
KW - Chatbot
KW - Knowledge Base
SN - 1865-0929
T2 - HCI International 2022 Posters
TI - Chatbot-Enhanced Requirements Resolution for Automated Service Compositions
VL - 1580
ER -
TY - CONF
AU - Otroshi, Mortaza
AU - Meschut, Gerson
ID - 34152
TI - Methodenentwicklung zur Verbesserung der Schädigungsmodellierung in der numerischen 3D-Belastungssimulation mechanischer Fügeverfahren unter Berücksichtigung der fügeinduzierten Vorbeanspruchung
ER -
TY - CONF
AU - Krauter, Stefan
AU - Bendfeld, Jörg
ID - 34155
T2 - Proceedings of the 8th World Conference on Photovoltaik Energy Conversion
TI - Microinverter PV Systems: New Efficiency Rankings and Formula for Energy Yield Assessment for any PV Panel Size at different Microinverter types
ER -
TY - CONF
AU - Kakande, Josephine Nakato
AU - Philipo, Godiana Hagile
AU - Krauter, Stefan
ID - 34156
T2 - Proceedings of the 8th World Conference on Photovoltaik Energy Conversion
TI - Optimal Design of a Semi Grid-Connected PV System for a Site in Lwak, Kenya Using HOMER
ER -
TY - GEN
AU - Otroshi, Mortaza
AU - Meschut, Gerson
ID - 34153
TI - Schädigungsmodellierung von Hilfsfügeelementen beim mechanischen Fügen von Stahlwerkstoffen
ER -
TY - THES
AB - Wettstreit zwischen der Entwicklung neuer Hardwaretrojaner und entsprechender Gegenmaßnahmen beschreiten Widersacher immer raffiniertere Wege um Schaltungsentwürfe zu infizieren und dabei selbst fortgeschrittene Test- und Verifikationsmethoden zu überlisten. Abgesehen von den konventionellen Methoden um einen Trojaner in eine Schaltung für ein Field-programmable Gate Array (FPGA) einzuschleusen, können auch die Entwurfswerkzeuge heimlich kompromittiert werden um einen Angreifer dabei zu unterstützen einen erfolgreichen Angriff durchzuführen, der zum Beispiel Fehlfunktionen oder ungewollte Informationsabflüsse bewirken kann. Diese Dissertation beschäftigt sich hauptsächlich mit den beiden Blickwinkeln auf Hardwaretrojaner in rekonfigurierbaren Systemen, einerseits der Perspektive des Verteidigers mit einer Methode zur Erkennung von Trojanern auf der Bitstromebene, und andererseits derjenigen des Angreifers mit einer neuartigen Angriffsmethode für FPGA Trojaner. Für die Verteidigung gegen den Trojaner ``Heimtückische LUT'' stellen wir die allererste erfolgreiche Gegenmaßnahme vor, die durch Verifikation mittels Proof-carrying Hardware (PCH) auf der Bitstromebene direkt vor der Konfiguration der Hardware angewendet werden kann, und präsentieren ein vollständiges Schema für den Entwurf und die Verifikation von Schaltungen für iCE40 FPGAs. Für die Gegenseite führen wir einen neuen Angriff ein, welcher bösartiges Routing im eingefügten Trojaner ausnutzt um selbst im fertigen Bitstrom in einem inaktiven Zustand zu verbleiben: Hierdurch kann dieser neuartige Angriff zur Zeit weder von herkömmlichen Test- und Verifikationsmethoden, noch von unserer vorher vorgestellten Verifikation auf der Bitstromebene entdeckt werden.
AU - Ahmed, Qazi Arbab
ID - 29769
KW - FPGA Security
KW - Hardware Trojans
KW - Bitstream-level Trojans
KW - Bitstream Verification
TI - Hardware Trojans in Reconfigurable Computing
ER -
TY - CONF
AB - Within innovation management, choosing the best fitting product idea is the most important decision point. The future existence and success of the organization is depending on selected product ideas. To find the best fitting idea for an organization, it needs evaluation criteria representing the organizations mission Therefore, this study focuses on a holistic overview about evaluation criteria and on supporting organizations in the process to select its individual evaluation criteria. Based on a literature study, existing approaches regarding evaluation criteria in product idea selection are identified and a list of evaluation criteria is reworked. Using the list of evaluation criteria, a prioritization method is created. Within an interview with experts in innovation management, the method is discussed regarding usability and the level of assistance in product idea selection. The developed criteria can be used directly by innovation manager and industrial practitioners to evaluate potential product ideas.
AU - Gräßler, Iris
AU - Koch, Anna-Sophie
ID - 34166
KW - innovation management
KW - evaluation criteria
KW - idea selection
KW - idea evaluation
KW - meta-study
SN - 978-952-335-694-8
T2 - XXXIII Proceedings of the ISPIM Innovation Conference
TI - Evaluation Criteria in Product Idea Selection Decisions
ER -
TY - THES
AB - Anforderungsänderungen sind ein wesentlicher Grund für Ineffizienzen und Projektfehlschläge in der Entwicklung komplexer technischer Systeme. Proaktives Management von Anforderungsänderungen hat das Potenzial, den Umgang mit Anforderungsänderungen effizienter zu gestalten. Dafür ist ein systematischer Ansatz erforderlich, der eine ganzheitliche Bewertung und Handhabung des Änderungsrisikos im industriellen Entwicklungskontext ermöglicht. Im Rahmen dieser Dissertation wird mit der ProMaRC-Methodik ein neuartiger Ansatz für das proaktive Management von Anforderungsänderungen vorgestellt. Die Methodik wurde in enger Zusammenarbeit mit Industrieanwender:innen aus der Automobilindustrie entwickelt und anhand von fünf Fallstudien validiert. Mittels automatisierter Abhängigkeitsanalyse auf Grundlage künstlicher Intelligenz wird der Anwendungsaufwand gegenüber bestehenden Ansätzen reduziert. Die teilautomatisierte Bewertung und Handhabung der Änderungswahrscheinlichkeit und -auswirkung erfolgt anhand eines modifizierten PageRank-Algorithmus und umfasst erstmalig alle für die Risikoanalyse relevanten Einflussfaktoren. Die Validierung belegt, dass durch die ProMaRC-Methodik eine überzeugende Kombination aus praxistauglichem Anwendungsaufwand und Vollständigkeit der Analyse erzielt wird. Damit erschließt diese Dissertation das bisher kaum beachtete Forschungsfeld des proaktiven Managements von Anforderungsänderungen und fördert eine effizientere Produktentwicklung.
AU - Oleff, Christian
ID - 34174
TI - Proaktives Management von Anforderungsänderungen in der Entwicklung komplexer technischer Systeme
VL - 406
ER -
TY - CONF
AB - This paper aims at discussing past limitations set in sentiment analysis research regarding explicit and implicit mentions of opinions. Previous studies have regularly neglected this question in favor of methodical research on standard-datasets. Furthermore, they were limited to linguistically less-diverse domains, such as commercial product reviews. We face this issue by annotating a German-language physician review dataset that contains numerous implicit, long, and complex statements that indicate aspect ratings, such as the physician’s friendliness. We discuss the nature of implicit statements and present various samples to illustrate the challenge described.
AU - Kersting, Joschka
AU - Bäumer, Frederik Simon
ED - Kersting, Joschka
ID - 31054
KW - Sentiment analysis
KW - Natural language processing
KW - Aspect phrase extraction
T2 - Proceedings of the Fourteenth International Conference on Pervasive Patterns and Applications (PATTERNS 2022): Special Track AI-DRSWA: Maturing Artificial Intelligence - Data Science for Real-World Applications
TI - Implicit Statements in Healthcare Reviews: A Challenge for Sentiment Analysis
ER -
TY - JOUR
AU - Hoyer, Britta
AU - De Jaegher, Kris
ID - 31881
JF - International Journal of Game Theory
TI - Network Disruption and the Common-Enemy Effect
ER -
TY - GEN
AB - BloKK-Beitrag für das ZeKK, 03.12.2022
AU - Lebock, Sarah
ID - 34187
TI - Blogpost "Von der Grundstimmung als philosophischer Ausgangspunkt"
ER -
TY - JOUR
AB - Far-field multi-speaker automatic speech recognition (ASR) has drawn increasing attention in recent years. Most existing methods feature a signal processing frontend and an ASR backend. In realistic scenarios, these modules are usually trained separately or progressively, which suffers from either inter-module mismatch or a complicated training process. In this paper, we propose an end-to-end multi-channel model that jointly optimizes the speech enhancement (including speech dereverberation, denoising, and separation) frontend and the ASR backend as a single system. To the best of our knowledge, this is the first work that proposes to optimize dereverberation, beamforming, and multi-speaker ASR in a fully end-to-end manner. The frontend module consists of a weighted prediction error (WPE) based submodule for dereverberation and a neural beamformer for denoising and speech separation. For the backend, we adopt a widely used end-to-end (E2E) ASR architecture. It is worth noting that the entire model is differentiable and can be optimized in a fully end-to-end manner using only the ASR criterion, without the need of parallel signal-level labels. We evaluate the proposed model on several multi-speaker benchmark datasets, and experimental results show that the fully E2E ASR model can achieve competitive performance on both noisy and reverberant conditions, with over 30% relative word error rate (WER) reduction over the single-channel baseline systems.
AU - Zhang, Wangyou
AU - Chang, Xuankai
AU - Boeddeker, Christoph
AU - Nakatani, Tomohiro
AU - Watanabe, Shinji
AU - Qian, Yanmin
ID - 33669
JF - IEEE/ACM Transactions on Audio, Speech, and Language Processing
SN - Print ISSN: 2329-9290 Electronic ISSN: 2329-9304
TI - End-to-End Dereverberation, Beamforming, and Speech Recognition in A Cocktail Party
ER -
TY - JOUR
AB - AbstractComprehensive data understanding is a key success driver for data analytics projects. Knowing the characteristics of the data helps a lot in selecting the appropriate data analysis techniques. Especially in data-driven product planning, knowledge about the data is a necessary prerequisite because data of the use phase is very heterogeneous. However, companies often do not have the necessary know-how or time to build up solid data understanding in connection with data analysis. In this paper, we develop a methodology to organize and categorize and thus understand use phase data in a way that makes it accessible to general data analytics workflows, following a design science research approach. We first present a knowledge base that lists typical use phase data from a product planning view. Second, we develop a taxonomy based on standard literature and real data objects, which covers the diversity of the data considered. The taxonomy provides 8 dimensions that support classification of use phase data and allows to capture data characteristics from a data analytics view. Finally, we combine both views by clustering the objects of the knowledge base according to the taxonomy. Each of the resulting clusters covers a typical combination of analytics relevant characteristics occurring in practice. By abstracting from the diversity of use phase data into artifacts with manageable complexity, our approach provides guidance to choose appropriate data analysis and AI techniques.
AU - Panzner, Melina
AU - von Enzberg, Sebastian
AU - Meyer, Maurice
AU - Dumitrescu, Roman
ID - 34197
JF - Journal of the Knowledge Economy
KW - Economics and Econometrics
SN - 1868-7865
TI - Characterization of Usage Data with the Help of Data Classifications
ER -
TY - JOUR
AB - Mounting sensors in disk stack separators is often a major challenge due to the operating conditions. However, a process cannot be optimally monitored without sensors. Virtual sensors can be a solution to calculate the sought parameters from measurable values. We measured the vibrations of disk stack separators and applied machine learning (ML) to detect whether the separator contains only water or whether particles are also present. We combined seven ML classification algorithms with three feature engineering strategies and evaluated our model successfully on vibration data of an experimental disk stack separator. Our experimental results demonstrate that random forest in combination with manual feature engineering using domain specific knowledge about suitable features outperforms all other models with an accuracy of 91.27 %.
AU - Merkelbach, Silke
AU - Afroze, Lameya
AU - Janssen, Nils
AU - von Enzberg, Sebastian
AU - Kühn, Arno
AU - Dumitrescu, Roman
ID - 34196
JF - Vibroengineering PROCEDIA
KW - General Medicine
SN - 2345-0533
TI - Using vibration data to classify conditions in disk stack separators
VL - 46
ER -
TY - CHAP
AU - Hobscheidt, Daniela
AU - Menzefricke, Jörn Steffen
AU - Gabriel, Stefan
AU - Kühn, Arno
AU - Dumitrescu, Roman
ID - 34195
SN - 9783658383787
T2 - Praxishandbuch Robotic Process Automation (RPA)
TI - Soziotechnische Herausforderungen bei der Einführung von RPA managen
ER -
TY - CHAP
AU - Bansmann, Michael
AU - Dumitrescu, Roman
AU - Fechtelpeter, Christian
ID - 34193
SN - 2523-3637
T2 - Gestaltung digitalisierter Arbeitswelten
TI - Transfer von Arbeit 4.0-Anwendungsszenarien
ER -
TY - CHAP
AU - Brock, Jonathan
AU - von Enzberg, Sebastian
AU - Kühn, Arno
AU - Dumitrescu, Roman
ID - 34194
SN - 9783658383787
T2 - Praxishandbuch Robotic Process Automation (RPA)
TI - Nutzung von Process Mining in RPA-Projekten
ER -
TY - JOUR
AB - Praxeologische Kompetenzansätze verstehen Kompetenz als sozial erlernt und folglich als relativ zum sozialen Kontext. Damit einher geht die Frage, wie solche praxeologisch gerahmten Kompetenzen eigentlich unabhängig von der sie hervorbringenden Praxis evaluiert werden können – und eben dadurch erst für einen breiteren Kompetenzdiskurs fruchtbar sind. Die Dokumentarische Evaluationsforschung bietet hierzu erste Anhaltspunkte, offenbart aber auch Grenzen, die mit dem Evaluationsverständnis zusammenhängen, sich jedoch in der Forschungspraxis so nicht finden lassen. Aus der Differenz zwischen Methode und Praxis dokumentarischer Evaluation lässt sich formulieren, wie eine praxeologische Evaluation gestaltet werden könnte. Dabei spielt die Formulierung von Referenzrahmen eine zentrale Rolle, welche einerseits der zu evaluierenden Praktik external sein, andererseits praktisch formuliert werden müssen, damit sie soziale Praktiken jenseits ihrer eigenen Sinnhaftigkeit evaluativ (er-)fassen können.
AU - Bloh, Thiemo
ID - 34200
IS - 02
JF - Zeitschrift für Evaluation
KW - Strategy and Management
KW - Applied Psychology
KW - Social Sciences (miscellaneous)
KW - Education
KW - Communication
KW - Statistics and Probability
SN - 1619-5515
TI - Rekonstruktive Evaluationsforschung im Kontext praxeologischer Kompetenzdiskurse. Kritische Reflexionen und konzeptionelle Überlegungen zur Dokumentarischen Evaluationsforschung
VL - 2022
ER -
TY - JOUR
AU - Bloh, Thiemo
AU - Caruso, Carina
ID - 34198
JF - die hochschullehre
TI - Ein kritisch-multiperspektivischer Blick auf Forschendes Lernen in der Lehrkräftebildung. Fragen, Erwägungen und Rekonstruktionen.
VL - 8
ER -
TY - JOUR
AU - Bloh, Thiemo
ID - 34199
IS - 6
JF - Zeitschrift für Pädagogik
TI - Grundlagentheoretische Differenzen in der Lehrkräftekooperationsforschung
VL - 68
ER -
TY - JOUR
AB - AlSi casting alloys combine excellent castability with high strength. Hence, this group of alloys is often used in the automotive sector. The challenge for this application is the brittle character of these alloys which leads to cracks during joint formation when mechanical joining technologies are used. A rise in ductility can be achieved by a considerable increase in the solidification rate which results in grain refinement. High solidification rates can be realized in twin–roll casting (TRC) by water-cooled rolls. Therefore, a hypoeutectic EN AC–AlSi9 (for European Norm - aluminum cast product) is manufactured by the TRC process and analyzed. Subsequently, joining investigations are performed on castings in as-cast and heat-treated condition using the self-piercing riveting process considering the joint formation and the load-bearing capacity. Due to the fine microstructure, the crack initiation can be avoided during joining, while maintaining the joining parameters, especially by specimens in heat treatment conditions. Furthermore, due to the extremely fine microstructure, the load-bearing capacity of the joint can be significantly increased in terms of the maximum load-bearing force and the energy absorbed.
AU - Neuser, Moritz
AU - Kappe, Fabian
AU - Ostermeier, Jakob
AU - Krüger, Jan Tobias
AU - Bobbert, Mathias
AU - Meschut, Gerson
AU - Schaper, Mirko
AU - Grydin, Olexandr
ID - 34207
IS - 10
JF - Advanced Engineering Materials
KW - Condensed Matter Physics
KW - General Materials Science
SN - 1438-1656
TI - Mechanical Properties and Joinability of AlSi9 Alloy Manufactured by Twin‐Roll Casting
VL - 24
ER -
TY - CONF
AU - Bloh, Thiemo
ID - 34203
TI - Was bedeutet Post-Digitalität? – Universitäre Lehrpraktiken zwischen situativer Anforderung und habitueller Prägung
ER -
TY - CONF
AU - Bloh, Thiemo
ID - 34201
TI - AussteigerInnen – Fluchtbewegungen in der LehrerInnenbiographie
ER -
TY - CONF
AU - Bloh, Thiemo
ID - 34202
TI - „Referenzrahmen“ als gewinnbringendes Konstrukt im Kontext Dokumentarischer Evaluationsforschung!?
ER -
TY - CONF
AU - Bloh, Thiemo
ID - 34204
TI - The Deconstruction of Professionalism
ER -
TY - CHAP
AB - Nowadays, clinching is a widely used joining technique, where sheets are joined by pure deformation to create an interlock without the need for auxiliary parts. This leads to advantages such as reduced joining time and manufacturing
costs. On the other hand, the joint strength solely relies on directed material deformation, which renders an accurate material modelling essential to reliably predict the joint forming. The formation of the joint locally involves large plastic strains and possibly complex non-proportional loading paths, as typical of many metal forming applications. Consequently, a finite plasticity formulation is utilised incorporating a Chaboche–Rousselier kinematic hardening law to capture the Bauschinger effect. Material parameters are identified from tension–compression tests on miniature spec-
imens for the dual-phase steel HCT590X. The resulting material model is implemented in LS-Dyna to study the locally diverse loading paths and give a quantitative statement on the importance of kinematic hardening for clinching. It turns out that the Bauschinger effect mainly affects the springback of the sheets and has a smaller effect on the joint forming itself.
AU - Friedlein, Johannes
AU - Mergheim, Julia
AU - Steinmann, Paul
ID - 34211
KW - Clinching
KW - Material modelling
KW - Kinematic hardening
KW - Parameter identification
KW - Bauschinger effect
SN - 2367-1181
T2 - The Minerals, Metals & Materials Series
TI - Influence of Kinematic Hardening on Clinch Joining of Dual-Phase Steel HCT590X Sheet Metal
ER -
TY - JOUR
AB - In this paper, a study based on experimental and numerical simulations is performed to analyze fatigue cracks in clinched joints. An experimental investigation is conducted to determine the failure modes of clinched joints under cyclic loading at different load amplitudes with single-lap shear tests. In addition, numerical FEM simulations of clinching process and subsequent shear loading are performed to support the experimental investigations by analyzing the state of stresses at the location of failure. An attempt is made to explain the location of crack initiation in the experiments using evaluation variables such as contact shear stress and maximum principal stress.
AU - Ewenz, L.
AU - Bielak, Christian Roman
AU - Otroshi, Mortaza
AU - Bobbert, Mathias
AU - Meschut, Gerson
AU - Zimmermann, M.
ID - 34213
IS - 2-3
JF - Production Engineering
KW - Industrial and Manufacturing Engineering
KW - Mechanical Engineering
SN - 0944-6524
TI - Numerical and experimental identification of fatigue crack initiation sites in clinched joints
VL - 16
ER -
TY - CHAP
AB - Force–displacement measurements and micrograph analyses are commonly used methods to validate numerical models of clinching processes. However, these methods often lead to resetting of elastic deformations and crack-
closing after unloading. In contrast, the in situ computed tomography (CT) can provide three-dimensional images of the clinch point under loading conditions. In this paper, the potential of the in situ investigation of a clinching process as validation method is analyzed. For the in situ testing, a tailored test set-up featuring a beryllium cylinder for load-bearing and clinching tools made from ultra-high-strength titanium and Si3N4 are used. In the experiments, the clinching of two aluminum sheets is interrupted at specific process steps in order to perform the CT scans. It is shown that in situ CT visualizes the inner geometry of the joint at high precision and that this method is suitable to validate numerical models.
AU - Köhler, Daniel
AU - Kupfer, Robert
AU - Troschitz, Juliane
AU - Gude, Maik
ID - 34212
KW - Clinching
KW - Non-destructive testing
KW - Computed tomography
KW - In situ CT
SN - 2367-1181
T2 - The Minerals, Metals & Materials Series
TI - Clinching in In Situ CT—A Novel Validation Method for Mechanical Joining Processes
ER -
TY - JOUR
AB - Resource-saving and sustainable production is becoming increasingly important regarding social, political and economic aspects, thus making the use of lightweight-construction technologies a current trend. For this reason, multi-material-systems made of high-strength steel and aluminium as well as metal and fibre-reinforced plastics gain in importance. However, different material properties, e.g. stiffness, thermal expansion coefficients or chemical incompatibilities, are challenging for conventional joining technologies. Joining by cold formed pin structures has shown to have high potential for joining multi-material-systems. These pins can be joined either by direct pin pressing into an unperforated joining partner or by caulking, where the pins are inserted through a pre-punched joining partner and the pin head is upset, resulting in a form-fit joint. Usually, cylindrical pins are used for joining. However, non-rotationally symmetrical pin geometries offer the possibility of introducing a predetermined breaking point or reinforcing a connection in the principal force direction. In this work, cylindrical pins as well as non-rotationally symmetrical pin geometries, such as polygonal and oval pin structures, are cold extruded from the sheet metal plane of an HCT590X+Z dual phase steel and joined in the next step with an EN AW-6014 aluminium using direct pin pressing. Since the formation of an undercut has an crucial influence on the joint strength, the investigations will be focused on the resulting joint geometry. In addition, the effect of different pin heights will be examined to analyse the joint formation at different levels of compression of the pin structures. Finally, the joints are evaluated regarding their joint strength in tensile shear tests and cross tension tests. Here the flow resistance of the geometry used as well as the pin height and thus the strain hardening of the pin base during the extrusion of the pins play a decisive role for the shear strength.
AU - Römisch, David
AU - Kraus, Martin
AU - Merklein, Marion
ID - 34219
IS - 6
JF - Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
KW - Mechanical Engineering
KW - General Materials Science
SN - 1464-4207
TI - Investigation of the influence of formed, non-rotationally symmetrical pin geometries and their effect on the joint quality of steel and aluminium sheets by direct pin pressing
VL - 236
ER -
TY - JOUR
AB - In this study, quasi-unidirectional continuous fiber reinforced thermoplastics (CFRTs) are joined with metal sheets via cold formed cylindrical, elliptical and polygonal pin structures which are directly pressed into the CFRT component after local infrared heating. In comparison to already available studies, the unique novelty is the use of non-rotational symmetric pin structures for the CFRT/metal hybrid joining. Thus, a variation in the fiber orientation in the CFRT component as well as a variation in the non-rotational symmetric pins’ orientation in relation to the sample orientation is conducted. The created samples are consequently mechanically tested via single lap shear experiments in a quasi-static state. Finally, the failure behavior of the single lap shear samples is investigated with the help of microscopic images and detailed photographs. In the single lap shear tests, it could be shown that non-rotational symmetric pin structures lead to an increase in maximum testing forces of up to 74% when compared to cylindrical pins. However, when normalized to the pin foot print related joint strength, only one polygonal pin variation showed increased joint strength in comparison to cylindrical pin structures. The investigation of the failure behavior showed two distinct failure modes. The first failure mode was failure of the CFRT component due to an exceedance of the maximum bearing strength of the pin-hole leading to significant damage in the CFRT component. The second failure mode was pin-deflection due to the applied testing load and a subsequent pin extraction from the CFRT component resulting in significantly less visible damage in the CFRT component. Generally, CFRT failure is more likely with a fiber orientation of 0° in relation to the load direction while pin extraction typically occurs with a fiber orientation of 90°. It is assumed that for future investigations, pin structures with an undercutting shape that creates an interlocking joint could counteract the tendency for pin-extraction and consequently lead to increased maximum joint strengths.
AU - Popp, Julian
AU - Römisch, David
AU - Merklein, Marion
AU - Drummer, Dietmar
ID - 34223
IS - 10
JF - Applied Sciences
KW - Fluid Flow and Transfer Processes
KW - Computer Science Applications
KW - Process Chemistry and Technology
KW - General Engineering
KW - Instrumentation
KW - General Materials Science
SN - 2076-3417
TI - Joining of CFRT/Steel Hybrid Parts via Direct Pressing of Cold Formed Non-Rotational Symmetric Pin Structures
VL - 12
ER -
TY - JOUR
AB - Thermoplastic composites (TPCs) are predestined for use in lightweight structures, especially for high-volume applications. In many cases, joining is a key factor for the successful application of TPCs in multi-material systems. Many joining processes for this material group are based on warm forming the joining zone. This results in a change of the local material structure characterised by modified fibre paths, as well as varying fibre contents, which significantly influences the load-bearing behaviour. During the forming process, many different phenomena occur simultaneously at different scales. In this paper, the deformation modes and flow mechanisms of TPCs during forming described in the literature are first analysed. Based on this, three different joining processes are investigated: embedding of inserts, moulding of contour joints, and hotclinching. In order to identify the phenomena occurring in each process and to describe the characteristic resulting material structure in the joining zones, micrographs as well as computed tomography (CT) analyses are performed for both individual process stages and final joining zones.
AU - Troschitz, Juliane
AU - Gröger, Benjamin
AU - Würfel, Veit
AU - Kupfer, Robert
AU - Gude, Maik
ID - 34225
IS - 15
JF - Materials
SN - 1996-1944
TI - Joining Processes for Fibre-Reinforced Thermoplastics: Phenomena and Characterisation
VL - 15
ER -
TY - JOUR
AB - Unter dem Begriff der Auflösung wird für gewöhnlich das kleinste messbare Merkmal eines Messsystems verstanden. In der dimensionellen Computertomografie hingegen haben sich in den vergangenen Jahren mehrere Auflösungskonzepte etabliert, die aufgrund der fehlenden Normung zueinander im Kontrast stehen. In diesem Beitrag werden die drei häufigsten Konzepte, die Voxelgröße, die Ortsauflösung und die metrologische Strukturauflösung in Kürze vorgestellt. Anschließend wird eine Abgrenzung zwischen den Konzepten getroffen und ein Integration der bestehenden Konzepte in ein gemeinsames Amplituden-Wellenlängen Diagramm diskutiert.
AU - Binder, Felix
AU - Hausotte, Tino
ID - 34221
IS - s1
JF - tm - Technisches Messen
KW - Electrical and Electronic Engineering
KW - Instrumentation
SN - 2196-7113
TI - Über die Abgrenzung von Auflösungskonzepten in der industriellen Computertomografie
VL - 89
ER -
TY - JOUR
AB - Die Erkennbarkeit von Rissen und geometrischen Qualitätskennwerten von Fügeverbindungen mittels Computertomografie ist von der Interfacestrukturauflösung abhängig, welche mittels geeigneter Prüfkörper untersucht wird. Die Reduktion von Abbildungsartefakten im Bereich von Bauteilzwischenräumen und -oberflächen verbessert deren dimensionelle Erfassbarkeit.
AU - Busch, Matthias
AU - Butzhammer, Lorenz
AU - Hausotte, Tino
ID - 34220
IS - s1
JF - tm - Technisches Messen
KW - Electrical and Electronic Engineering
KW - Instrumentation
SN - 2196-7113
TI - Herausforderungen bei computertomografischen Untersuchungen von Fügeverbindungen
VL - 89
ER -
TY - CONF
AU - Marx, Julian
AU - Rieskamp, Jonas
AU - Mirbabaie, Milad
ID - 33519
T2 - Proceedings of the 33rd Australasian Conference on Information Systems
TI - ‘Just a Normal Day in the Metaverse’ – Distraction Conflicts of Knowledge Work in Virtual Environments
ER -
TY - CONF
AU - Alshomary, Milad
AU - Rieskamp, Jonas
AU - Wachsmuth, Henning
ID - 32247
T2 - Proceedings of the 9th International Conference on Computational Models of Argument
TI - Generating Contrastive Snippets for Argument Search
ER -
TY - THES
AB - Das Ultraschall-Dickdrahtbonden mit Aluminiumdraht ist ein Standardverfahren zur elektrischenKontaktierung von Leistungshalbleitermodulen. Die steigenden Anforderungen an die Effizienzund Zuverlässigkeit der Module haben zu technologischen Weiterentwicklungen geführt und eswerden vermehrt Kupferdrähte mit wesentlich besseren elektrischen und thermischen Eigenschafteneingesetzt. Hieraus resultieren durch höhere Prozesskräfte und Ultraschallleistung neueHerausforderungen bei der Prozessentwicklung; hierfür wird ein Simulationsmodell zur Verbesserungder Prozessentwicklung entwickelt.In Ultraschall-Drahtbondversuchen mit 400 m Aluminium und Kupfer Drähten wurde der Einflussder Prozessparameter auf die Bondqualität untersucht; diese Ergebnisse und zusätzliche Messungender Drahtdeformation und Schwingungen wurden für die Formulierung der Anforderungenund zur Validierung der Ergebnisse des Simulationsmodells genutzt.Es wurde ein Prozessmodell, basierend auf einer Co-Simulation zwischen MATLAB und ANSYS,entwickelt; hierbei wurden die phyiskalischen Phänomene wie die Ultraschall Werkstoffentfestigung,der Verbindungsaufbau und die dynamischen Systemeigenschaften abgebildet.Basierend auf einer Zug-Druck-Prüfmaschine wurde ein Prüfstand zur Identifikation der Modellparameterentwickelt. In zusätzlichen Druckversuchen mit den Bonddrähten mit und ohneUltraschallanregung wurde die Reduktion der Umformkräfte unter Ultraschalleinfluss untersucht.Mit dem entwickelten Prozessmodell wurden die Parameterstudien aus den Ultraschall-Drahtbondversuchensimuliert und direkt mit den experimentellen Ergebnissen verglichen, wobei sich einerelativ gute Übereinstimmung zwischen Simulation und Messung sowohl für Aluminium, als auchfür Kupfer, erzielen ließ.
AU - Schemmel, Reinhard
ID - 34272
SN - 978-3-8440-8527-3
TI - Enhanced process development by simulation of ultrasonic heavy wire bonding
VL - 13
ER -
TY - JOUR
AU - Gutt, Jana Kim
AU - Thommes, Kirsten
ID - 34283
IS - 1
JF - Academy of Management Proceedings
KW - Microbiology
SN - 0065-0668
TI - Speaking of Performance: Evaluating Team Members’ Performance with Open-Ended Audio Comments
VL - 2022
ER -
TY - CONF
AU - Trentinaglia, Roman
ID - 34298
T2 - Proceedings of the 25th International Conference on Model Driven Engineering Languages and Systems: Companion Proceedings
TI - Deriving model-based safety and security assurance cases from design rationale of countermeasure patterns
ER -
TY - JOUR
AB - Eines der Lernziele des Physikstudiums stellt der Erwerb literaler Fähigkeiten für das Verfassen wissenschaftlicher Arbeiten dar. Die Student:innen werden allerdings im Rahmen ihres Studiums bisher kaum systematisch beim Erwerb dieser Fähigkeiten unterstützt. Eine Übungsgelegenheit für das Verfassen von Texten nach wissenschaftlichem Vorbild stellt das Laborpraktikum dar, in dem die Student:innen zu den absolvierten Experimenten Laborberichte verfassen. Im Paderborner Physik Praktikum 3P wurden in den letzten Jahren vier unterschiedliche Unterstützungsangebote für das Erlernen des wissenschaftlichen Schreibens entwickelt und mittels Zufriedenheitswerten evaluiert. In dem Beitrag werden die vier Angebote auf inhaltlicher Ebene hinsichtlich der Lernwirksamkeit mittels einer schriftproduktbasierten Evaluation analysiert. Durch die vergleichende Analyse können Potenziale und Grenzen der Angebote diskutiert und Implikationen für die Gestaltung von Unterstützungsangeboten zum Erlernen des wissenschaftlichen Schreibens in der Physik abgeleitet werden.
AU - Bauer, Anna Brigitte
AU - Lahme, Simon Zacharias
AU - Sacher, Marc
ID - 34316
IS - 1
JF - PhyDid A - Physik und Didaktik in Schule und Hochschule
KW - Laborpraktikum
KW - Schreiben
TI - Potenziale und Grenzen von Unterstützungsmaßnahmen zum wissenschaftlichen Schreiben im Paderborner Physik Praktikum 3P
VL - 21
ER -