@inproceedings{RauchBrueckl, author = {Rauch, Johannes and Br{\"u}ckl, Oliver}, title = {Konzeptionierung netzplanerischer Prozessans{\"a}tze zur Ermittlung von Blindleistungskapazit{\"a}ten zum Ausgleich des Blindleistungsbedarfs in einer Netzregion}, series = {Tagungsband Tagung Zuk{\"u}nftige Stromnetze 26./27. Januar 2022 (online)}, booktitle = {Tagungsband Tagung Zuk{\"u}nftige Stromnetze 26./27. Januar 2022 (online)}, publisher = {Conexio-PSE GmbH}, address = {Pforzheim}, isbn = {978-3-948176-16-7}, doi = {10.35096/othr/pub-5866}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-58665}, pages = {117 -- 126}, abstract = {Um einen sicheren und zuverl{\"a}ssigen Stromnetzbetrieb zu gew{\"a}hrleisten, muss die Spannung im Grundfall als auch bei ungeplanten Ausf{\"a}llen in definierten Bereichen gehalten werden. Im {\"U}bertragungsnetz wird hierf{\"u}r bisher Blindleistung haupts{\"a}chlich aus Blindleistungskompensationsanlagen und konventionellen Großkraftwerken eingesetzt. Zuk{\"u}nftig wird nach \S12h EnWG eine marktgest{\"u}tzte Beschaffung dieser Dienstleistung zur Spannungsregelung vorgeschrieben. Zugleich ver{\"a}ndert sich der Blindleistungsbedarf der Netzbetriebsmittel durch die Integration erneuerbarer Energieanlagen und der Elektromobilit{\"a}t sowie durch den Netzausbau bei {\"U}bertragungs- und Verteilungsnetzbetreibern. Es bedarf somit angepasster Netzbetriebs- und Netzplanungskonzepte f{\"u}r ein technisch effizientes und wirtschaftlich g{\"u}nstiges Blindleistungsmanagement. Dieser Beitrag besch{\"a}ftigt sich damit, Prozessans{\"a}tze und Methodiken f{\"u}r ebendieses in der Netzplanung aufzuzeigen, um erforderliche Blindleistungskapazit{\"a}ten unter minimalen Gesamtkostenaufwand und unter Ber{\"u}cksichtigung einer effizienten Blindleistungsbedarfsdeckung zu bestimmen. Dabei liegt der Fokus verst{\"a}rkt in der Bedarfsanalyse.}, language = {de} } @inproceedings{RauchBrueckl, author = {Rauch, Johannes and Br{\"u}ckl, Oliver}, title = {Analysis of the correlation behavior between local available information to the overall reactive power of a medium-voltage grid group}, series = {Applied Research Conference - ARC 2017, 7 July 2017 M{\"u}nchen}, booktitle = {Applied Research Conference - ARC 2017, 7 July 2017 M{\"u}nchen}, address = {M{\"u}nchen}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-58712}, pages = {224 -- 230}, abstract = {The initiated energy transition leads to extensive changes in the supply of energy. The increasing use of renewable energy causes a shift of the produced power from centralized conventional power plants to decentralized energy plants. Because of this redistribution and the related change of load-flows, new challenges and problems for distribution system operators appear. This includes the integration of new loads and plants into the existing power grid and the guarantee of a high supply security and quality. It also includes strengthened requirements for the use and provision of reactive power. The project "SyNErgie" ("Systemoptimierendes Netz- und Energiemanagement f{\"u}r Verteilungsnetze der Zukunft") deals with the development of a new reactive power management, which gets embedded in grid planning and controlling processes. One focus of the project is on the integration of decentralized energy plants (DEPs) to the reactive power management. The aim is to develop a decentralized and self-sufficient reactive power control system, which only works with local available information (measures). Therefore is no necessity of a complex communication system to the grid control center. Self-controlled Q-controller in the DEPs get characteristic curves and control the reactive power sources with local measurements (e.g. current, voltage, effective power). This new reactive power control management aims for the reactive power compensation in order to increase the integration capacity of loads and plants in a grid [2]. In order to generate characteristic curves for DEPs, it is necessary to analyze the correlation behavior between the local available measurements at the DEPs and the overall-Q-behavior of the grid group at the transformer. In that regard, influencing quantities should be considered. The aim is to involve und evaluate all relevant influencing quantities in order to determine energy plants and certain operating points, in which the correlation behavior and the prediction for the overall-Q-behavior are sufficient. The next step is to develop a model that fits these correlation behaviors and generate characteristic curves. One method to generate characteristic curves for the Q-controllers is regression analysis. The developed Q-control-system with the characteristic curves will be tested, evaluated and optimized in a following field test in cooperation with distribution system operators.}, language = {de} } @inproceedings{SchweibererRauchBrueckl, author = {Schweiberer, Philipp and Rauch, Johannes and Br{\"u}ckl, Oliver}, title = {Entwicklung eines Regelkonzeptes f{\"u}r einen optimierten Blindleistungsabruf auf Basis von Blindleistungspotentialanalysen bei Industriebetrieben im Mittelspannungsnetz}, series = {Tagungsband Tagung Zuk{\"u}nftige Stromnetze 26./27. Januar 2022 (online)}, booktitle = {Tagungsband Tagung Zuk{\"u}nftige Stromnetze 26./27. Januar 2022 (online)}, publisher = {Conexio-PSE GmbH}, address = {Pforzheim}, isbn = {978-3-948176-16-7}, doi = {10.35096/othr/pub-5870}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-58704}, pages = {224 -- 233}, abstract = {Im Zuge der Energiewende ergibt sich ein Wandel in der Struktur des Elektrizit{\"a}tsversorgungsnetzes. Die Verschiebung der Erzeugungsleistung von konventionellen Großkraftwerken in h{\"o}heren Netzebenen hin zu dezentralen erneuerbaren Energieanlagen in niedrigeren Netzebenen resultiert sowohl in bidirektionalen Lastfl{\"u}ssen als auch in schwankenden Einspeisecharakteristiken. Des Weiteren folgen durch den Wegfall von Großkraftwerken als Blindleistungsquellen Leistungsdefizite in der {\"U}bertragungsnetzebene, die kompensiert werden m{\"u}ssen. Daraus resultieren Herausforderungen an einen sicheren und zuverl{\"a}ssigen Betrieb der Verteil- und {\"U}bertragungsnetze. Neue Konzepte m{\"u}ssen f{\"u}r die Erbringung von Blindleistung entwickelt werden, es soll mehr Blindleistung aus dem Verteilungsnetz zur Verf{\"u}gung gestellt werden, um die Systemstabilit{\"a}t zu wahren. Im Rahmen des Projektes Q-Integral wird das Thema „Blindleistung" (Q) ganzheitlich untersucht. Es werden dazu verschiedene Erbringungsoptionen f{\"u}r Blindleistung hinsichtlich technischer und wirtschaftlicher Potentiale untersucht, die in ein funktionales und effizientes Blindleistungsmanagement eingebracht werden. Die Untersuchungsans{\"a}tze daf{\"u}r sind sowohl spannungsebenen-{\"u}bergreifend als auch netzbetreiber-{\"u}bergreifend. Ein Ansatzpunkt des Projektes ist die Betrachtung der Blindleistungsbereitstellung von Industriebetrieben. Dazu wird das Potential von Betrieben, die an das Verteilnetz angeschlossen sind und Blindleistung durch Kompensations- oder Erzeugungsanlagen bereitstellen k{\"o}nnen, untersucht. Ziel ist es, das gesicherte und maximale induktive sowie kapazitive Potential zu bestimmen. Das gesicherte kapazitive Potential kann genutzt werden, um Aussagen dar{\"u}ber zu treffen, wie stark dem Spannungsfall im vorgelagerten Netz zu Starklastzeiten entgegengewirkt werden kann. Anhand des gesicherten induktiven Potentials kann ein Spannungsanstieg w{\"a}hrend Schwachlastzeiten ausgeglichen werden kann. In diesem Beitrag werden Ergebnisse aus dem Projekt Q-Integral vorgestellt. Dazu werden zuerst die Berechnungsgrundlagen der induktiven und kapazitiven Blindleistungspotentiale aufgezeigt und die Ergebnisse der Berechnungen vorgestellt. Die gewonnen Ergebnisse entstammen aus Messungen an einem Industriebetrieb mit Blindleistungskompensationsanlagen (BKA), den entsprechenden Reglern der Anlagen und einer installierten Kompensationsleistung von 1600 kvar. Sowohl die Lastg{\"a}nge als auch das Schaltverhalten der einzelnen Kompensationsanlagen liegen den Berechnungen zugrunde. Um den Austausch der Blindleistung an der {\"U}bergabestelle des Betriebs zum Mittelspannungsnetz netzdienlich einzustellen, bedarf es eines geeigneten Regelkonzepts, das neben den BKAs auch weitere Q-Quellen ber{\"u}cksichtigt. Deshalb wird abschließend ein Regelkonzept vorgestellt, das den technisch-optimierten Blindleistungsabruf unter Ber{\"u}cksichtigung mehrerer Blindleistungsquellen behandelt.}, language = {de} } @inproceedings{RauchBruecklEngel, author = {Rauch, Johannes and Br{\"u}ckl, Oliver and Engel, Bernd}, title = {Analysis and optimization of the steady state voltage deviation demand for reactive power planning using installed reactive power sources}, series = {NEIS 2022; Conference on Sustainable Energy Supply and Energy Storage Systems, 26-27 September 2022, Hamburg}, booktitle = {NEIS 2022; Conference on Sustainable Energy Supply and Energy Storage Systems, 26-27 September 2022, Hamburg}, editor = {Schulz, Detlef}, publisher = {VDE-Verlag}, address = {Berlin}, isbn = {978-3-8007-5983-5}, issn = {2510-6902}, pages = {175 -- 182}, abstract = {The provision of reactive power is one option for maintaining the grid voltage, that is defined as an ancillary service in Germany. This paper presents an approach for determining deficient voltage deviation demands within an electrical grid for long term reactive power planning investigations. In contrast to previous approaches, which evaluate the Q-behavior of extended ward elements or grid assets, voltage deviations are analyzed bus-specifically. So further reactive power planning investigations are able to scale and optimize additional reactive power sources directly on planning voltage limits using load flow sensitivity techniques. The focus lies on the analysis of the steady state demand at base case conditions. Therefore, a grid planning process is conceptualized. An optimal power flow algorithm based on Differential Evolution is used for an optimal reactive power dispatch of installed reactive power sources, e. g. reactive power compensation systems or (renewable) energy sources to minimize the total voltage deviation according to voltage limits of Transmission System Operators planning principles. Methodological and processuals specifications as well as an application use case with an exemplary transmission system are presented in this paper.}, language = {en} } @inproceedings{SchweibererRauchBrueckl, author = {Schweiberer, Philipp and Rauch, Johannes and Br{\"u}ckl, Oliver}, title = {Long-term analysis of industrial reactive power potentials with consideration of plant-internal grid restrictions using the example of an industrial plant in a distribution grid}, series = {NEIS 2022; Conference on Sustainable Energy Supply and Energy Storage Systems, 26-27 September 2022, Hamburg}, booktitle = {NEIS 2022; Conference on Sustainable Energy Supply and Energy Storage Systems, 26-27 September 2022, Hamburg}, editor = {Schulz, Detlef}, publisher = {VDE-Verlag}, address = {Berlin}, isbn = {978-3-8007-5983-5}, issn = {2510-6902}, pages = {51 -- 56}, abstract = {Since conventional generation plants provide a considerable share of reactive power but are gradually being shut down due to energy transition, leading to power deficits at the transmission grid level, new concepts for the supply of reactive power must be developed. As one possibility for the latter, industrial plants in the distribution grid are considered suitable, as their reactive power potentials can contribute to voltage maintenance and thus to a grid- or system-serving behavior. In this paper, the determination of reactive power potentials provided by industrial compensation systems (ICS) is presented. An industrial plant in the medium voltage grid, with three installed ICSs, is investigated. The potentials are determined and described based on their time characteristics, which provide information about the occurrence and distribution of inductive and capacitive potentials. A grid simulation of the investigated industrial grid is used to analyze the effects of retrieving the reactive power potentials regarding equipment utilizations and voltage limits.}, language = {en} } @techreport{BrixnerGnerlichJakobetal., author = {Brixner, Luis and Gnerlich, Patrick and Jakob, Jonas and Kiener, Johannes and Oberl{\"a}nder, Jonas and Pl{\"o}ßl, Moritz and Sch{\"a}chinger, Stefan and Stelz, Raphael and Wartner, Felix}, title = {FMS-Berichte Wintersemester 2023/24}, number = {1}, editor = {Fuhrmann, Thomas and Niemetz, Michael and Reindl, Andrea}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg / Fakult{\"a}t Elektro- und Informationstechnik}, doi = {10.35096/othr/pub-7779}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77796}, pages = {47}, abstract = {Dieser Bericht entstand urspr{\"u}nglich auf Initiative der Studierenden des damals neuen Masterstudiengangs „Elektro- und Informationstechnik (MEI)" an der OTH Regensburg, die an der Pflichtlehrveranstaltung „Forschungsmethoden und Seminar (FMS)" im Wintersemester 2020/21 teilnahmen. Diese Lehrveranstaltung hat das Ziel, systematisch an das wissenschaftliche Arbeiten, speziell die Wissenschaftskommunikation, heranzuf{\"u}hren. Daher ist im Laufe der Veranstaltung geeignete Literatur zu einem individuellen Thema zu recherchieren, sind Ver{\"o}ffentlichungen auf ihre Relevanz hin zu beurteilen und letztendlich gilt es eine eigene Ausarbeitung basierend auf der Literaturrecherche zu erstellen und diese in einem Vortrag zu pr{\"a}sentieren. Parallel dazu wird im Theorieteil die entsprechende Hinf{\"u}hrung zu den verschiedenen Elementen der Wissenschaftskommunikation vermittelt: • Bedeutung der Wissenschaftskommunikation f{\"u}r die Arbeit der Ingenieure in Forschung und Entwicklung • Literaturrecherche, Suchmaschinen, Sichtung und Analyse vorhandener Publikationen, Bewertung der Qualit{\"a}t aufgefundener Fachliteratur, Auswahl geeigneter Materialien f{\"u}r die eigene Arbeit • Aufbereitung und Darstellung der recherchierten technischer Inhalte in Form einer seitenanzahlbegrenzten wissenschaftlichen Ausarbeitung • Einhalten formaler Randbedingungen bzgl. Strukturierung, einschl. Bildnachweise und Zitationsstile • Peer-review-Prozess bei wertsch{\"a}tzender Beurteilung der Leistung anderer • Publikumsangepasstes Aufbereiten komplexer fachlicher Inhalte mit hochschul{\"o}ffentlicher Pr{\"a}sentation der Ergebnisse • F{\"u}hren m{\"u}ndlicher wissenschaftlicher Diskurse Die pr{\"a}sentierten Themen beruhen nicht auf eigener Forschungst{\"a}tigkeit, sondern sind als einf{\"u}hrende Reviewartikel zum jeweiligen vorgegebenen technischen oder gesellschaftspolitischen Forschungsthema zu verstehen.}, subject = {Elektrotechnik}, language = {mul} } @techreport{BloesserBranilovicMichaeletal., author = {Bl{\"o}ßer, Julia and Branilovic, Fabio and Michael, Bretz and Ebner, Andreas and Gleich, Ralf and Inderst, Christian and Kopp, Lorenz and M{\"u}ller, Markus and Sch{\"a}chiner, Michael and von Beerfelde, Rebekka}, title = {FMS-Berichte Sommersemester 2024}, series = {FMS-Berichte Sommersemester 2024}, journal = {FMS-Berichte Sommersemester 2024}, number = {1}, editor = {Fuhrmann, Thomas and Niemetz, Michael and Reindl, Andrea}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg / Fakult{\"a}t Elektro- und Informationstechnik}, doi = {10.35096/othr/pub-7780}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77801}, pages = {56}, abstract = {Dieser Bericht entstand urspr{\"u}nglich auf Initiative der Studierenden des damals neuen Masterstudiengangs „Elektro- und Informationstechnik (MEI)" an der OTH Regensburg, die an der Pflichtlehrveranstaltung „Forschungsmethoden und Seminar (FMS)" im Wintersemester 2020/21 teilnahmen. Diese Lehrveranstaltung hat das Ziel, systematisch an das wissenschaftliche Arbeiten, speziell die Wissenschaftskommunikation, heranzuf{\"u}hren. Daher ist im Laufe der Veranstaltung geeignete Literatur zu einem individuellen Thema zu recherchieren, sind Ver{\"o}ffentlichungen auf ihre Relevanz hin zu beurteilen und letztendlich gilt es eine eigene Ausarbeitung basierend auf der Literaturrecherche zu erstellen und diese in einem Vortrag zu pr{\"a}sentieren. Parallel dazu wird im Theorieteil die entsprechende Hinf{\"u}hrung zu den verschiedenen Elementen der Wissenschaftskommunikation vermittelt: • Bedeutung der Wissenschaftskommunikation f{\"u}r die Arbeit der Ingenieure in Forschung und Entwicklung • Literaturrecherche, Suchmaschinen, Sichtung und Analyse vorhandener Publikationen, Bewertung der Qualit{\"a}t aufgefundener Fachliteratur, Auswahl geeigneter Materialien f{\"u}r die eigene Arbeit • Aufbereitung und Darstellung der recherchierten technischer Inhalte in Form einer seitenanzahlbegrenzten wissenschaftlichen Ausarbeitung • Einhalten formaler Randbedingungen bzgl. Strukturierung, einschl. Bildnachweise und Zitationsstile • Peer-review-Prozess bei wertsch{\"a}tzender Beurteilung der Leistung anderer • Publikumsangepasstes Aufbereiten komplexer fachlicher Inhalte mit hochschul{\"o}ffentlicher Pr{\"a}sentation der Ergebnisse • F{\"u}hren m{\"u}ndlicher wissenschaftlicher Diskurse Die pr{\"a}sentierten Themen beruhen nicht auf eigener Forschungst{\"a}tigkeit, sondern sind als einf{\"u}hrende Reviewartikel zum jeweiligen vorgegebenen technischen oder gesellschaftspolitischen Forschungsthema zu verstehen.}, subject = {Elektrotechnik}, language = {mul} } @article{RadkovskayaSydorukShamoninChamonineetal., author = {Radkovskaya, Anna A. and Sydoruk, O. and Shamonin (Chamonine), Mikhail and Shamonina, Ekaterina and Stevens, C. J. and Faulkner, Grahame and Edwards, David J. and Solymar, L.}, title = {Experimental study of a bi-periodic magnetoinductive waveguide: comparison with theory}, series = {IET Microwaves, Antennas \& Propagation}, volume = {1}, journal = {IET Microwaves, Antennas \& Propagation}, number = {1}, publisher = {IET}, issn = {1751-8733}, doi = {10.1049/iet-map:20050289}, pages = {80 -- 83}, abstract = {Magnetoinductive waves propagating along a line consisting of two kinds of metamaterial elements are studied. Both elements are made up by the same metallic loop but are loaded by different capacitors resulting in different resonant frequencies. The dispersion characteristics are derived from phase and amplitude measurements for the cases when the line consists of (i) identical elements and (ii) of alternating elements. Both planar (elements in the same plane as the axis of the line) and axial (elements perpendicular to the axis of the line) configurations are investigated. It is shown that in the bi-periodic arrangement of the elements, the dispersion curves have a forward wave in the lower frequency branch and a backward wave in the upper frequency branch independent of the configuration whether it is planar or axial. Comparisons between theoretical and experimental results show good agreement.}, language = {en} } @misc{HirmerDanilovGiglbergeretal., author = {Hirmer, Marion and Danilov, Sergey N. and Giglberger, Stephan and Putzger, J{\"u}rgen and Niklas, Andreas and J{\"a}ger, Andreas and Hiller, Karl-Anton and Schmalz, Gottfried and Redlich, Britta and Monkman, Gareth J. and Ganichev, Sergey D.}, title = {Spectroscopic Study of Human Teeth and Blood from Visible to Terahertz Frequencies for Clinical Diagnosis of Dental Pulp Vitality}, series = {PACS, November 11, 2011}, journal = {PACS, November 11, 2011}, abstract = {Transmission spectra of wet human teeth and dentin slices, together with blood of different flow rates were investigated. The measurements carried out over a wide spectral range, from visible light down to terahertz radiation. The results make it possible to find the optimum light frequency for an all-optical determination of pulpal blood flow and, consequently, for clinically diagnosis of tooth vitality.}, language = {en} } @inproceedings{MayerForsterRabindranathetal., author = {Mayer, Matthias and Forster, Eva and Rabindranath, Raman and Bentz, Alexander and B{\"o}se, Holger and Shamonin (Chamonine), Mikhail and Monkman, Gareth J.}, title = {Highly compliant Magneto-Active Polymers (MAPs)}, series = {Actuator'11, Bremen, May 2011}, booktitle = {Actuator'11, Bremen, May 2011}, language = {en} } @incollection{HauserGrabingerEzeretal., author = {Hauser, Florian and Grabinger, Lisa and Ezer, Timur and Mottok, J{\"u}rgen and Gruber, Hans}, title = {Integrating deliberate practice in software engineering education}, series = {ICERI 2024 Proceedings, 17th annual International Conference of Education, Research and Innovation,11-13 November, 2024, Seville, Spain}, booktitle = {ICERI 2024 Proceedings, 17th annual International Conference of Education, Research and Innovation,11-13 November, 2024, Seville, Spain}, editor = {G{\´o}mez Chova, Luis and Gonz{\´a}lez Mart{\´i}nez, Chelo and Lees, Joanna}, publisher = {IATED}, doi = {10.21125/iceri.2024.1331}, pages = {5457 -- 5466}, language = {en} } @techreport{RankHeberlSterner, author = {Rank, Daniel and Heberl, Michael and Sterner, Michael}, title = {Die CO2-Bilanz der OTH [Ostbayerischen Technische Hochschule Regenburg]}, language = {de} } @incollection{SchrimerPutzMonkman, author = {Schrimer, M and Putz, Christoph and Monkman, Gareth J.}, title = {Boron-Silicone-Oxide Polymers}, series = {Boron: advances in research and applications}, booktitle = {Boron: advances in research and applications}, editor = {McConnell, Lynn}, publisher = {Nova Science Publishers}, address = {New York, NY}, isbn = {9781685072315}, doi = {10.52305/AFKU5564}, pages = {117 -- 179}, language = {en} } @article{UnterreitmeierNaglerPfitzneretal., author = {Unterreitmeier, M. and Nagler, Oliver and Pfitzner, L. and Weigel, R. and Holmer, Rainer}, title = {An acoustic emission sensor system for thin layer crack detection}, series = {Microelectronics Reliability}, volume = {88-90}, journal = {Microelectronics Reliability}, number = {September}, publisher = {Pergamon-Elsevier}, doi = {10.1016/j.microrel.2018.07.015}, pages = {16 -- 21}, abstract = {We present a new method for semiconductor layer characterization enabling simultaneous crack generation and detection based on the established acoustic emission testing. In this paper, we explain the test concept and failure mechanism of diamond tip indentation with acoustic wave measurement on oxide layers by analytical modeling and computer-aided simulations. For this purpose, an innovative design of a sensor-indenter system was developed and experimentally verified. In further tests, the new acoustic crack detection method is correlated with proven optical inspection methods and the good reproducibility of the measurement is demonstrated. The high sensitivity and resolution of this method offer new opportunities for thin layer characterization at lower time and cost. The new high-efficient method can be used especially for process qualification for semiconductor wafer test, where oxide cracks can be induced by sharp probes causing electrical failure of the chip.}, language = {en} } @inproceedings{SchiekSetzpfandtPertschetal., author = {Schiek, Roland and Setzpfandt, Frank and Pertsch, Thomas and Baronio, Fabio and de Angelis, Costantino}, title = {Spatial Rogue Waves in Quadratic Optical Slab Waveguides}, series = {Advanced Photonics 2018 (BGPP, IPR, NP, NOMA, Sensors, Networks, SPPCom, SOF), OSA Techncail Digest (online) (Optica Publishing Group, 2018), paper NpTh1H.7}, booktitle = {Advanced Photonics 2018 (BGPP, IPR, NP, NOMA, Sensors, Networks, SPPCom, SOF), OSA Techncail Digest (online) (Optica Publishing Group, 2018), paper NpTh1H.7}, publisher = {OSA}, address = {Washington D.C.}, isbn = {978-1-943580-43-9}, doi = {10.1364/np.2018.npth1h.7}, abstract = {Spatial optical breather solutions of the Nonlinear Schr{\"o}dinger Equation have been observed for the first time. The experiment was performed in an optical slab waveguide with the cascaded quadratic nonlinearity in second-harmonic generation.}, language = {en} } @article{ZimmermannChavezVegaBeckeretal., author = {Zimmermann, Klaus and Chavez Vega, Jhohan Harvey and Becker, Tatiana I. and Witte, Hartmut and Schilling, Cornelius and K{\"o}hring, Sebastian and B{\"o}hm, Valter and Monkman, Gareth J. and Prem, Nina and Sindersberger, Dirk and Lutz, I. I. and Merker, Lukas}, title = {An approach to a form-adaptive compliant gripper element based on magneto-sensitive elastomers with a bioinspired sensorized surface}, series = {Problems of Mechanics}, volume = {75}, journal = {Problems of Mechanics}, number = {2}, publisher = {Georgian Technical University}, address = {Tbilisi}, issn = {1512-0740}, pages = {23 -- 38}, language = {en} } @misc{StarkSchreistetterReuteretal., author = {Stark, T. and Schreistetter, Stefan and Reuter, Rebecca and Hauser, Florian and Holmqvist, Kenneth and Mottok, J{\"u}rgen and Gruber, Hans}, title = {Learning from Gaze: Eye Movement Modeling Examples in Software Engineering Education}, series = {Earli Book of Abstracts}, journal = {Earli Book of Abstracts}, publisher = {Earli}, pages = {291}, language = {en} } @inproceedings{SetzpfandtSchiekSohleretal., author = {Setzpfandt, Frank and Schiek, Roland and Sohler, Wolfgang and Pertsch, Thomas}, title = {Nonlinear Nearest-Neighbor Coupling in Quadratic Waveguide Arrays}, series = {Nonlinear Optics : Proceedings Nonlinear Optics 26-31 July 2015, Kauai, Hawaii, United States}, booktitle = {Nonlinear Optics : Proceedings Nonlinear Optics 26-31 July 2015, Kauai, Hawaii, United States}, publisher = {OSA}, address = {Washington, D.C.}, isbn = {978-1-55752-001-2}, doi = {10.1364/nlo.2015.nm3b.6}, abstract = {We investigate nonlinear coupling between neighboring waveguides in waveguide arrays with second-order nonlinearity. Using mode symmetries to suppress local nonlinearities, we experimentally show the profound effect of such nonlinear nearest-neighbor interactions on second-harmonic generation.}, language = {en} } @inproceedings{AlFaloujiPrestelScharfenbergetal., author = {Al-Falouji, Ghassan and Prestel, Dietmar and Scharfenberg, Georg and Mandl, Roland and Deinzer, Arnulf and Halang, W. and Margraf-Stiksrud, Jutta and Sick, B. and Deinzer, Renate}, title = {SMART-iBrush - Individuelle Unterst{\"u}tzung der Zahnreinigung durch Messung von Bewegung und Druck mit einer intelligenten Zahnb{\"u}rsten}, series = {Transdisziplin{\"a}re Konferenz Technische Unterst{\"u}tzungssysteme, die die Menschen wirklich wollen, 1, 2014, Gießen}, booktitle = {Transdisziplin{\"a}re Konferenz Technische Unterst{\"u}tzungssysteme, die die Menschen wirklich wollen, 1, 2014, Gießen}, publisher = {Helmut-Schmidt-Universit{\"a}t, Universit{\"a}t der Bundeswehr}, address = {Hamburg}, isbn = {978-3-86818-073-2}, pages = {315 -- 327}, abstract = {Der Forschungsansatz der intelligenten Zahnb{\"u}rste (SMART-iBrush) verfolgt das Ziel, dass Menschen die f{\"u}r sie effektivste Zahnputzmethode unter individueller Anleitung der Zahnb{\"u}rste interaktiv trainieren k{\"o}nnen. Hierzu wurde eine Zahnb{\"u}rste entwickelt, die Bewegung und Druckverlauf erfasst. Daten werden an ein Smart Device {\"u}bertragen und k{\"o}nnen dort in Echtzeit visualisiert werden, z.B. in eher spielerischer Form f{\"u}r Jugendliche oder sachlich n{\"u}chterner Form f{\"u}r Erwachsene. In einem Feldversuch wurden Daten von 100-Probanden erfasst. Zuk{\"u}nftig soll mit der SMART-iBrush Technologie, bei deren Entwicklung Wissenschaftler in den Bereichen Psychologie, Zahnmedizin, Embedded Systems und Machine Learning kooperieren, auch die G{\"u}te des Putzvorgangs bewertet werden, um die Putzenden aktiv anzuleiten. Intelligent toothbrush research (SMART-iBrush) aims to support humans in learning their individual, most effective tooth brushing technique. Therefore, a toothbrush was developed that measures motion and force applied to its tip. Measurements are transferred to a smart device where they can be visualized in real-time, for example in a more playful fashion for children or a-more factual fashion for adults. Field trials were conducted with 100 participants. Future features of SMART-iBrush 'will include interactive guidance and training techniques. To achieve these goals, researchers from the fields of psychology, dentistry, embedded systems, and machine learning cooperate in SMART-iBrush project.}, language = {de} } @article{SydorukShamoninChamonineRadkovskayaetal., author = {Sydoruk, O. and Shamonin (Chamonine), Mikhail and Radkovskaya, Anna A. and Zhuromskyy, Oleksandr and Shamonina, Ekaterina and Trautner, Ralph and Stevens, C. J. and Faulkner, Grahame and Edwards, David J. and Solymar, L.}, title = {Mechanism of subwavelength imaging with bilayered magnetic metamaterials: Theory and experiment}, series = {Journal of Applied Physics}, volume = {101}, journal = {Journal of Applied Physics}, number = {7}, publisher = {AIP}, doi = {10.1063/1.2714782}, abstract = {We present a theoretical and experimental study of a bilayered metamaterial structure for subwavelength imaging of magnetic field. The simplest version of such a structure consists of one or two linear arrays of capacitively loaded split pipe resonators. Its subwavelength physics is governed by strongly anisotropic magnetic coupling between individual resonators and by propagation of magnetoinductive waves with wavelength much shorter than the wavelength of the electromagnetic radiation in free space. It is shown that magnetoinductive waves propagating in the lateral direction are undesirable because they spread the image. Good subwavelength imaging is achieved when, due to the strong interlayer coupling, a stop band in the vicinity of the resonant frequency appears in the dispersion characteristics. The imaging properties of the single and double lens are compared and it is shown that the double lens has a superior performance. Excellent agreement is obtained between experimental and theoretical results for the magnetic field in the image plane in the operation frequency range of 30-60 MHz. It is shown that the same mechanism is responsible for image formation using bilayered planar metamaterial structures and a design of such a lens comprising two planar layers with a total of 542 elements is provided. The conclusions are not restricted to the radio frequency region because the elements can be scaled down.}, language = {en} } @article{HofrichterRankHeberletal., author = {Hofrichter, Andreas and Rank, Daniel and Heberl, Michael and Sterner, Michael}, title = {Determination of the optimal power ratio between electrolysis and renewable energy to investigate the effects on the hydrogen production costs}, series = {International Journal of Hydrogen Energy}, volume = {48}, journal = {International Journal of Hydrogen Energy}, number = {5}, publisher = {Elsevier}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2022.09.263}, pages = {1651 -- 1663}, abstract = {Green hydrogen via renewable powered electrolysis has a high relevance in decarbonization and supply security. Achieving economically competitive hydrogen production costs is a major challenge in times of an energy price crisis. Our objective is to show the economically optimal installed capacity of electrolysers in relation to wind and solar power so swift and credible statements can be made regarding the system design. The ratio between renewable generation and electrolysis power as well as scaling effects, operating behaviour and development of costs are considered. Hydrogen production costs are calculated for four exemplary real PV and wind sites and different ratios of electrolysis to renewable power for the year 2020. The ideal ratio for PV systems is between 14\% and 73\% and for wind between 3.3\% and 143\% for low and high full load hours. The lowest hydrogen production costs are identified at 2.53 €/kg for 50 MW wind power and 72 MW electrolysis power. The results provide plant constructors the possibility to create a cost-optimized design via an optimum ratio of electrolysis to renewable capacity. Therefore, the procedures for planning and dimensioning of selected systems can be drastically simplified.}, language = {en} } @article{RadkovskayaSydorukShamoninChamonineetal., author = {Radkovskaya, Anna A. and Sydoruk, O. and Shamonin (Chamonine), Mikhail and Stevens, C. J. and Faulkner, Grahame and Edwards, David J. and Shamonina, Ekaterina and Solymar, L.}, title = {Transmission properties of two shifted magnetoinductive waveguides}, series = {Microwave and Optical Technology Letters}, volume = {49}, journal = {Microwave and Optical Technology Letters}, number = {5}, publisher = {Wiley}, doi = {10.1002/mop.22344}, pages = {997 -- 1230}, abstract = {Transmission properties of magnetoinductive waves propagating in two coupled one-dimensional metamaterial arrays are studied both experimentally and theoretically for the case when one of the arrays is shifted relative to the other one. Two different kinds of resonant metamaterial elements, split-pipe and spiral resonators, are investigated in the frequency bands centred at 46.2 and 586 MHz, respectively. It is shown that within a certain frequency range close to the resonant frequencies the transmission is strongly dependent on the shift. Theoretical calculations based on the impedance matrix show good agreement with the experimental results}, language = {en} } @inproceedings{DeNiklasBradaetal., author = {De, Sangita and Niklas, Michael and Brada, Premek and Mottok, J{\"u}rgen}, title = {Model Transformation of Application Software Component from Classic to Adaptive AUTOSAR: An Approach to Migrate Software Components}, series = {SEAA 2018, the 44th EUROMICRO Conference on Software Engineering and Advanced Applications, August 29 - 31 2018, Prague, Czech Republic}, booktitle = {SEAA 2018, the 44th EUROMICRO Conference on Software Engineering and Advanced Applications, August 29 - 31 2018, Prague, Czech Republic}, isbn = {978-3-902457-50-9}, language = {en} } @inproceedings{ReindlLangNiemetzetal., author = {Reindl, Andrea and Lang, Andreas and Niemetz, Michael and Meier, Hans}, title = {Switching and Averaging Models of a Bidirectional, Half-Bridge Based DC-DC converter with Load Distribution}, series = {Proceedings of the 15th International Modelica Conference 2023, Aachen, October 9-11}, booktitle = {Proceedings of the 15th International Modelica Conference 2023, Aachen, October 9-11}, publisher = {OJS}, doi = {10.3384/ecp204683}, abstract = {Batteries are used in numerous applications such as mobile devices, electric vehicles, home storage systems and islanded microgrids. Bidirectional DC-DC converters are vital for the integration of batteries, for the power conversion during (dis)charge and the battery management. Modeling of these is helpful, especially for the design of larger, more complex systems consisting of multiple DC-DC converters in parallel. Due to the high switching frequencies, the simulation of DC-DC converters is associated with increased computational time and effort. In this paper, three models of different complexity and accuracy are proposed for a bidirectional DC-DC converter consisting of two phase-shifted half-bridges. Two switching models, which differ mainly in the way the mosfets are driven, account for the individual switching operations and exhibit high accuracy. An averaging model replaces the switching elements with current and voltage sources providing the mean values. It is particularly suitable for multiple components and longer simulation durations. The dynamic behavior of the models is analyzed using the step responses of the load current. For validation, these are compared with the theoretical transfer function. The three models are analyzed comparatively in terms of computational time and effort. The calculation time of the averaging model has been reduced by two thirds compared to the strictly complementary switching model and by 96\% relative to the model with diode emulation mode. The averaging model requires only one third of the computation time of the complementary switching model and only 3.5\% of that of the model with diode emulation. Recommendations for the use of the models are given and a possible use case is shown. Two parallel connected DC-DC converters with load current sharing between them are simulated using the averaging model.}, language = {en} } @inproceedings{BugertStauferBittneretal., author = {Bugert, Flemming and Staufer, Susanne and Bittner, Dominik and Nadimpalli, Vamsi Krishna and Ezer, Timur and Hauser, Florian and Grabinger, Lisa and Mottok, J{\"u}rgen}, title = {Ariadne's Thread for Unravelling Learning Paths: Identifying Learning Styles via Hidden Markov Models}, series = {2024 IEEE Global Engineering Education Conference (EDUCON), 08-11 May 2024, Kos Island, Greece}, booktitle = {2024 IEEE Global Engineering Education Conference (EDUCON), 08-11 May 2024, Kos Island, Greece}, publisher = {IEEE}, issn = {2165-9567}, doi = {10.1109/EDUCON60312.2024.10578825}, pages = {1 -- 7}, abstract = {Modern education through Learning Management Systems (LMSs) provides learners with personalized learning paths. This is achieved by first querying the learning style according to the theory of Felder and Silverman to recommend suitable learning content. However, a rigid learning style representation is lacking of adaptability to the learners' choices. Therefore, the present study evaluates the idea of providing adaption to the representation of learning styles by using Hidden Markov Models (HMMs). Thus, data is collected from participants out of the Higher Education Area. The Index of Learning Styles questionnaire is used to obtain the learning style based on the theory of Felder and Silverman. Also, a questionnaire that asks the respondents to create a preferred learning path with the sequence length of nine learning elements is provided. From the given data, we initially evaluate the probability relationships between learning styles and learning elements. Then, we use the Viterbi algorithm in HMMs to identify alterations in learning styles from the provided learning paths. The alignment is then quantified by introducing a metric called support value. The findings imply that our concept can be used to adapt the learning style based on the user's real choice of learning elements. Thus, the proposed model also offers a way to integrate a feedback loop within LMSs leading to an improvement of learning path recommendation algorithms.}, language = {en} } @misc{ChavezVegaBoehmYinetal., author = {Chavez Vega, Jhohan Harvey and B{\"o}hm, Valter and Yin, J. and Becker, Tatiana I. and K{\"o}hring, Sebastian and Monkman, Gareth J. and Odenbach, Stefan and Zimmermann, Klaus}, title = {Field induced plasticity of magneto-sensitive elastomers for gripping technology applications}, series = {6th Colloquium of SPP 1681, Benediktbeuern, 26. - 28.09.2018 : Book of Abstracts}, journal = {6th Colloquium of SPP 1681, Benediktbeuern, 26. - 28.09.2018 : Book of Abstracts}, pages = {16 -- 17}, language = {en} } @inproceedings{SehrYoshiokaDelcroixetal., author = {Sehr, Armin and Yoshioka, Takuya and Delcroix, Marc and Kinoshita, Keisuke and Nakatani, Tomohiro and Maas, Roland and Kellermann, Walter}, title = {Conditional emission densities for combining speech enhancement and recognition systems}, series = {Proceedings of the Annual Conference of the International Speech Communication Association, INTERSPEECH, 25 - 29 August 2013, Lyon, France}, booktitle = {Proceedings of the Annual Conference of the International Speech Communication Association, INTERSPEECH, 25 - 29 August 2013, Lyon, France}, publisher = {ISCA}, doi = {10.21437/Interspeech.2013-265}, pages = {3502 -- 3506}, abstract = {A novel framework based on conditional emission densities for hidden Markov models (HMMs) is proposed in this contribution to integrate speech enhancement systems with automatic speech recognition systems. In the training phase, the observed feature vectors, corrupted by background noise and reverberation, together with estimates for the interference as provided by the speech enhancement system are used for training joint densities of the observations and the interference estimates. In the decoding phase, the joint densities are transformed to conditional densities of the observed features given the interference estimates. Thus, front end processing can be exploited for obtaining interference estimates, and the estimation errors can be modeled very effectively in a data-driven way. Connected digit recognition experiments in a simulated reverberant environment show the potential of the proposed approach: HMMs with the proposed conditional densities outperform various configurations of conventional HMMs in the logarithmic melspectral domain. This is a first step towards using conditional densities for creating synergies between front end and back end. Index Terms: speech enhancement, robust speech recognition, dereverberation, conditional HMM emission densities, frame- by-frame model adaptation.}, language = {en} } @inproceedings{DrexlerHirmerDanilovetal., author = {Drexler, C. and Hirmer, Marion and Danilov, Sergey N. and Giglberger, Stephan and Putzger, J{\"u}rgen and Niklas, Andreas and J{\"a}ger, Andreas and Hiller, Karl-Anton and L{\"o}ffler, S. and Schmalz, Gottfried and Redlich, Britta and Schulz, Irene and Monkman, Gareth J. and Ganichev, Sergey D.}, title = {Infrared spectroscopy for clinical diagnosis of dental pulp vitality}, series = {37th International Conference on Infrared, Millimetre, and Terahertz Waves (IRMMW-THz 37), 23-28 September 2012 , Wollongong, Australia}, booktitle = {37th International Conference on Infrared, Millimetre, and Terahertz Waves (IRMMW-THz 37), 23-28 September 2012 , Wollongong, Australia}, publisher = {IEEE}, address = {Piscataway, NJ}, doi = {10.1109/IRMMW-THz.2012.6380091}, abstract = {Transmission spectra of wet human teeth and dentin slices, together with blood of different flow rates were investigated over a wide spectral range, from visible to terahertz (THz) light. The results make it possible to find the optimum light frequency for an all-optical determination of pulpal blood flow and, consequently, for clinically diagnosis of tooth vitality.}, language = {en} } @inproceedings{ForsterRabindranathMayeretal., author = {Forster, Eva and Rabindranath, Raman and Mayer, Matthias and Bentz, Alexander and B{\"o}se, Holger and Shamonin (Chamonine), Mikhail and Monkman, Gareth J.}, title = {Characterization of ultra soft Magneto-Active Polymers (MAPs)}, series = {Conference proceedings / INDUCTICA 2011, Berlin, Germany, 24 - 26 May}, booktitle = {Conference proceedings / INDUCTICA 2011, Berlin, Germany, 24 - 26 May}, language = {en} } @inproceedings{NerlichMonkmanFuechtmeieretal., author = {Nerlich, Michael and Monkman, Gareth J. and F{\"u}chtmeier, Bernd and Egersd{\"o}rfer, Stefan}, title = {Development of a Robotic Navigation and Fracture Fixation System}, series = {1. Jahrestagung der Deutschen Gesellschaft f{\"u}r Computer- und Roboterassistierte Chirurgie (CURAC), Leipzig, 2002}, booktitle = {1. Jahrestagung der Deutschen Gesellschaft f{\"u}r Computer- und Roboterassistierte Chirurgie (CURAC), Leipzig, 2002}, language = {en} } @inproceedings{GaertnerRankHeberletal., author = {G{\"a}rtner, Sebastian and Rank, Daniel and Heberl, Michael and Gaderer, Matthias and Sterner, Michael}, title = {Integration of Power-To-Methane into Glass Melting Processes}, series = {Proceedings of the International Renewable Energy Storage Conference (IRES 2022)}, volume = {16}, booktitle = {Proceedings of the International Renewable Energy Storage Conference (IRES 2022)}, publisher = {Atlantis Press}, issn = {2589-4943}, doi = {10.2991/978-94-6463-156-2_12}, pages = {147 -- 161}, abstract = {The glass industry is facing increased challenges regarding climate protection targets and rising energy costs. The integration of renewable energy including conversion and storage is a key for both challenges in this energy-intensive industrial sector, which has been mainly relying on fossil gas so far. The options considered to this point for reducing CO2 emissions and switching to a renewable energy supply involve far-reaching changes of the established melting processes. This entails significant risks in terms of influences on glass quality and stable production volumes. The presented approach for the integration of a Power-to-Methane (PtM) system into the glass industry is a completely new concept and has not been considered in detail before. It allows the use of established oxyfuel melting processes, the integration of fluctuating renewable energy sources and a simultaneous reduction of CO2 emissions by more than 78\%. At the same time, natural gas purchases become obsolete. A techno-economic evaluation of the complete PtM process shows, that 1,76 €/m3 or 1,26 €/kg synthetic natural gas are possible with renewable energy supply. Using electricity from the energy grid would require electricity prices < 0,126 €/kWh to allow cost competitive PtM processes in the glass industry. Such electricity prices could be achieved by electricity market-based optimization and operation of the PtM system. This operation strategy would require AI-based algorithms predicting availabilities and prices on future-based markets.}, language = {en} } @inproceedings{HauserGrabingerMottoketal., author = {Hauser, Florian and Grabinger, Lisa and Mottok, J{\"u}rgen and Jahn, Sabrina and Nadimpalli, Vamsi Krishna}, title = {The Expert's View: Eye Movement Modeling Examples in Software Engineering Education}, series = {Proceedings of the 5th European Conference on Software Engineering Education, Seeon/Germany, June 19 - 21, 2023}, booktitle = {Proceedings of the 5th European Conference on Software Engineering Education, Seeon/Germany, June 19 - 21, 2023}, publisher = {ACM}, isbn = {978-1-4503-9956-2}, doi = {10.1145/3593663.3593683}, pages = {148 -- 152}, abstract = {This study investigates the impact of eye movement modeling examples in Software Engineering education. Software Engineering is a highly visual domain. The daily tasks of a software engineer (e.g., formulating requirements, creating UML diagrams, or conducting a code review) require in many cases the use of certain visual strategies. Although these strategies can be found for experts, it has been observed in different eye tracking studies that students have difficulties in learning and applying them. To familiarize students with these visual strategies and to provide them with a better understanding for the cognitive processes involved, a total of seven eye movement modeling examples was created. The seven eye movement modeling examples cover relevant parts of an introductory Software Engineering lecture; they are focused on typical situations in which visual strategies are applied. The results of a questionnaire-based evaluation shows that students consider the eye movement modeling examples as useful, feel supported in their learning process, and would like to see more use of them in the Software Engineering lecture. Furthermore, the students suggested that eye movement modeling examples should also be used in other lectures.}, language = {en} } @inproceedings{BugertGrabingerBittneretal., author = {Bugert, Flemming and Grabinger, Lisa and Bittner, Dominik and Hauser, Florian and Nadimpalli, Vamsi Krishna and Staufer, Susanne and Mottok, J{\"u}rgen}, title = {Towards Learning Style Prediction based on Personality}, series = {Proceedings of the 5th European Conference on Software Engineering Education, Seeon/Germany, June 19 - 21, 2023}, booktitle = {Proceedings of the 5th European Conference on Software Engineering Education, Seeon/Germany, June 19 - 21, 2023}, publisher = {ACM}, isbn = {978-1-4503-9956-2}, doi = {10.1145/3593663.3593682}, pages = {48 -- 55}, abstract = {This paper assesses the relation between personality, demographics, and learning style. Hence, data is collected from 200 participants using 1) the BFI-10 to obtain the participant's expression of personality traits according to the five-factor model, 2) the ILS to determine the participant's learning style according to Felder and Silverman, and 3) a demographic questionnaire. From the obtained data, we train and evaluate a Bayesian network. Using Bayesian statistics, we show that age and gender slightly influence personality and that demographics as well as personality have at least a minor effect on learning styles. We also discuss the limitations and future work of the presented approach.}, language = {en} } @inproceedings{BittnerHauserNadimpallietal., author = {Bittner, Dominik and Hauser, Florian and Nadimpalli, Vamsi Krishna and Grabinger, Lisa and Staufer, Susanne and Mottok, J{\"u}rgen}, title = {Towards Eye Tracking based Learning Style Identification}, series = {Proceedings of the 5th European Conference on Software Engineering Education, Seeon/Germany, June 19 - 21, 2023}, booktitle = {Proceedings of the 5th European Conference on Software Engineering Education, Seeon/Germany, June 19 - 21, 2023}, publisher = {ACM}, isbn = {978-1-4503-9956-2}, doi = {10.1145/3593663.3593680}, pages = {138 -- 147}, abstract = {The dropout rate at universities has been very high for years. Thereby, the inexperience and lack of knowledge of students in dealing with individual learning paths in various courses of study plays a decisive role. Adaptive learning management systems are suitable countermeasures, in which learners' learning styles are classified using questionnaires or computationally intensive algorithms before a learning path is suggested accordingly. In this paper, a study design for student learning style classification using eye tracking is presented. Furthermore, qualitative and quantitative analyses clarify certain relationships between students' eye movements and learning styles. With the help of classification based on eye tracking, the filling out of questionnaires or the integration of computationally or cost-intensive algorithms can be made redundant in the future.}, language = {en} } @inproceedings{NadimpalliBugertBittneretal., author = {Nadimpalli, Vamsi Krishna and Bugert, Flemming and Bittner, Dominik and Hauser, Florian and Grabinger, Lisa and Staufer, Susanne and Mottok, J{\"u}rgen}, title = {Towards personalized learning paths in adaptive learning management systems: bayesian modelling of psychological theories}, series = {Proceedings of the 16th annual International Conference of Education, Research and Innovation (ICERI 2023), Seville, Spain, 11/13/2023 - 11/14/2023}, booktitle = {Proceedings of the 16th annual International Conference of Education, Research and Innovation (ICERI 2023), Seville, Spain, 11/13/2023 - 11/14/2023}, editor = {G{\´o}mez Chova, Luis and Gonz{\´a}lez Mart{\´i}nez, Chelo and Lees, Joanna}, publisher = {IATED}, doi = {10.21125/iceri.2023.1144}, pages = {4593 -- 4603}, abstract = {In educational research, non-personalized learning content increases learners' cognitive load, causing them to lower their performance and sometimes drop out of the course. Personalizing learning content with learners' unique characteristics, like learning styles, personality traits, and learning strategies, is being suggested to improve learners' success. Several theories exist for assessing learners' unique characteristics. By the end of 2020, 71 learning style theories have been formulated, and research has shown that combining multiple learning style theories to recommend learning paths yields better results. As of the end of 2022, there is no single research that demonstrates a relationship between the Index of Learning Styles (ILS) based Felder-Silverman learning style model (FSLSM) dimensions, Big Five (BFI-10) based personality traits, and the Learning strategies in studying (LIST-K) based learning strategies factors for personalizing learning content. In this paper, an innovative approach is proposed to estimate the relationship between these theories and map the corresponding learning elements to create personalized learning paths. Respective questionnaires were distributed to 297 higher education students for data collection. A three-step approach was formulated to estimate the relationship between the models. First, a literature search was conducted to find existing studies. Then, an expert interview was carried out with a group of one software engineering education research professor, three doctoral students, and two master's students. Finally, the correlations between the students' questionnaire responses were calculated. To achieve this, a Bayesian Network was built with expert knowledge from the three-step approach, and the weights were learned from collected data. The probability of individual FSLSM learning style dimensions was estimated for a new test sample. Based on the literature, the learning elements were mapped to the respective FSLSM learning style dimensions and were initiated as learning paths to the learners. The next steps are proposed to extend this framework and dynamically recommend learning paths in real time. In addition, the individual levels of learning style dimensions, personality traits, and learning strategies can be considered to improve the recommendations. Further, using probabilities for mapping learning elements to learning styles can increase the chance of initiating multiple learning paths for an individual learner.}, language = {en} } @inproceedings{TremmelNaglerKutteretal., author = {Tremmel, Florian and Nagler, Oliver and Kutter, Christoph and Holmer, Rainer}, title = {Smart Cantilever Probe with Integrated Force and Acoustic Emission Sensor}, series = {2023 IEEE SENSORS, Vienna, Austria, 10/29/2023 - 11/1/2023}, booktitle = {2023 IEEE SENSORS, Vienna, Austria, 10/29/2023 - 11/1/2023}, publisher = {IEEE}, isbn = {979-8-3503-0387-2}, doi = {10.1109/SENSORS56945.2023.10325021}, pages = {1 -- 4}, abstract = {Acoustic emission (AE) testing recently found its application in the wafer testing sector of the semiconductor industry. To find out the mechanical robustness of semiconductor devices, contact pads on the chip surface are intentionally overstressed with an indenter tip and the appearing oxide cracks are detected with help of the generated AE signals. This is done in a customized test bench with a patented sensor-indenter system. This paper presents an improved version of the measurement setup that solves certain disadvantages of it and can be used in a standard wafer prober. The main components of the developed sensor system are a strain gauge for contact force measurement and a piezoelectric sensor element for AE signal detection. Both components are integrated on a cantilever beam which has an exchangeable indenter tip at its free end. The cantilever probe is electrically conductive to enable electrical tests via the indenter tip. This smart sensor-cantilever combination (SCC) can be mounted with several adapter components on a carrier plate to place it in a wafer prober. For both sensor elements amplifier circuits are developed to enhance their signal-to-noise ratios (SNRs). A prototype setup is shown together with simulated and experimental results to demonstrate its performance. The mechanical properties of the cantilever, as well as the force sensor and the AE crack signals, already fulfill the requirements for an implementation in a wafer prober. To further improve the sensor resolutions and detection limits, several optimizations regarding the design of the SCC are in progress.}, language = {en} } @unpublished{HeberlWithelmKauletal., author = {Heberl, Michael and Withelm, Christian and Kaul, Anja and Rank, Daniel and Sterner, Michael}, title = {Prospective Life Cycle Assessment of Biological Methanation in a Trickle-Bed Pilot Plant and a Potential Scale-Up}, publisher = {SSRN}, doi = {10.2139/ssrn.4635066}, abstract = {In this study, a pilot-scale trickle-bed reactor for biological methanation and various scale-up scenarios for 2023 and 2050 were investigated using LCA. A best- and worst-case scenario for technology development until 2050 was evolved using cross consistency analysis and morphological field, based on which the data for the ecological models were determined.The results show that the plant scale-up has a very positive effect on the ecological consequences of methanation. In the best-case scenario, the values are a factor of 23-780 lower than those of the actual plant today. A hot-spot analysis showed that especially electrolysis operation has a large impact on total emissions. The final Monte-Carlo simulation shows that the technology is likely to achieve a low GWP with a median of 104.0 kg CO2-eq / MWh CH4.}, language = {en} } @inproceedings{EzerPloesslGrabingeretal., author = {Ezer, Timur and Pl{\"o}ßl, Moritz and Grabinger, Lisa and Bittner, Dominik and Staufer, Susanne and Nadimpalli, Vamsi Krishna and Bugert, Flemming and Hauser, Florian and Mottok, J{\"u}rgen}, title = {Deep learning for eye movement classification}, series = {ICERI 2024 Proceedings, 17th annual International Conference of Education, Research and Innovation,11-13 November, 2024, Seville, Spain}, booktitle = {ICERI 2024 Proceedings, 17th annual International Conference of Education, Research and Innovation,11-13 November, 2024, Seville, Spain}, editor = {G{\´o}mez Chova, Luis and Gonz{\´a}lez Mart{\´i}nez, Chelo and Lees, Joanna}, publisher = {IATED}, doi = {10.21125/iceri.2024.1028}, pages = {4056 -- 4065}, language = {en} } @unpublished{GaubeJussupowKokjeetal., author = {Gaube, Susanne and Jussupow, Ekaterina and Kokje, Eesha and Khan, Jowaria and Bondi-Kelly, Elizabeth and Schicho, Andreas and Kitamura, Felipe Campos and Koch, Timo Kevin and Ezer, Timur and Mottok, J{\"u}rgen and Lermer, Eva and Ghassemi, Marzyeh and Colak, Errol}, title = {Underreliance Harms Human-AI Collaboration More Than Overreliance in Medical Imaging}, publisher = {OSFPreprints}, doi = {10.31219/osf.io/4wv8j}, abstract = {Importance: The use of artificial intelligence (AI) to support clinicians in diagnostic decision-making holds significant potential; however, evidence regarding its clinical utility remains mixed. In many cases, the interaction between healthcare professionals and AI systems does not improve collaborative performance compared to the standalone performance of humans or AI. Currently, the underlying mechanisms that limit human-AI collaboration are poorly understood. Objective: To examine the impact of AI advice on diagnostic decision-making among experts and novices, focusing on understanding the role of explainability (XAI) on users' reliance on advice. Design, Setting, and Participants: A mixed-methods design combining a crossover experimental design with a think-aloud and an eye-tracking study arm was conducted in 2023. Participants were task experts (radiologists) and novices (non-radiologist physicians and medical trainees) from 10 countries, with the think-aloud and eye-tracking conducted in Germany. Intervention: Participants reviewed 50 patient cases containing head CT scans and patient information. Every case was reviewed in three time-separate sessions in randomized order. In each session, participants were exposed to a different experimental condition: (a) control, i.e., no AI prediction presented; (b) basic advice, i.e., AI prediction without annotations; and (c) XAI advice, i.e., AI prediction with annotations. For each case, participants had to determine if the patients had an intracranial hemorrhage (ICH), rate their confidence, and, if applicable, the usefulness of the AI advice. Main Outcome(s) and Measure(s): Diagnostic performance, confidence in the diagnosis, case reading time, and AI advice usefulness ratings. Results: The data analysis included 125 participants. The mean age was 28.5 years (SD = 6.72), and 55.2\% identified as female. Underreliance on correct AI advice was associated with high uncertainty and had a more detrimental impact on diagnostic performance than overreliance on incorrect advice. XAI advice reduced underreliance and improved performance and confidence, particularly when reviewing more difficult cases with ICH. AI advice, particularly XAI, did not reduce reading time. XAI was perceived as more useful than basic AI advice, especially among novices. Conclusions and Relevance: Our findings indicate that underreliance on AI might be more harmful than overreliance, highlighting the need to develop efficient counterstrategies beyond current XAI methods.}, language = {en} } @inproceedings{BittnerHauserEngletal., author = {Bittner, Dominik and Hauser, Florian and Engl, Fabian and Mottok, J{\"u}rgen}, title = {Eye Movement Modelling Examples on Usability Heuristics}, series = {Proceedings of the 6th European Conference on Software Engineering Education : ECSEE 2025, Seeon Germany, June 02-04, 2025}, booktitle = {Proceedings of the 6th European Conference on Software Engineering Education : ECSEE 2025, Seeon Germany, June 02-04, 2025}, editor = {Mottok, J{\"u}rgen and Hagel, Georg}, publisher = {ACM}, isbn = {9798400712821}, doi = {10.1145/3723010.3723035}, pages = {106 -- 114}, abstract = {The user interface (UI) and user experience (UX) design is of crucial importance for human-computer interaction (HCI), particularly in the context of web applications. In light of the high expectations of users and the competitive nature of the market, it is imperative to employ usability measurement techniques to avoid losing users. Heuristic evaluation (HE) is a cost- and resource-efficient method for evaluating the usability of websites in which evaluators are guided by heuristics. However, the level of expertise of the evaluators has a significant impact on the results, with experts identifying up to 50\% more usability issues than novices. To address this gap, this paper proposes Eye Movement Modeling Examples (EMMEs) to demonstrate Jakob Nielsen's ten usability heuristics in an easy-to-understand format for all levels of experience while also incorporating expert knowledge. In particular, the eye movements and verbal feedback of a usability expert are recorded as the expert analyses the usability of a simple website application in terms of Jakob Nielsen's ten usability heuristics. This reveals the strategies and cognitive processes of the expert when assessing the usability of a website and makes them more tangible for non-experts or novices. The findings of a questionnaire-based assessment indicate that EMMEs are perceived as beneficial and supportive during the learning process. Ultimately, this comprehensive analysis not only enables a deeper understanding of heuristics for usability novices, but could also lead to EMMEs being applied more efficiently in diverse domains.}, language = {en} } @unpublished{MeisingerHofrichterBaueretal., author = {Meisinger, Alexander and Hofrichter, Andreas and Bauer, Franz and Sterner, Michael}, title = {Unlocking Potential Energy Partnerships in Europe: a Case Study on the Way to a Franco-German Energy Transition}, publisher = {SSRN}, doi = {10.2139/ssrn.5251699}, pages = {23}, abstract = {Global warming is already causing global destabilization. Geopolitical challenges fuel this instability and highlight the need for trusted energy partnerships to ensure energy security. To limit global warming and increase energy security, it is essential to take joint action on an international and global scale. The European Green Deal contributes to this. However, specific national actions are still needed. This research presents a way forward for a Franco-German energy transition and unlocks the potential of energy partnerships within Europe, using a cost-based, sector-coupled optimization model. Both countries are coupled via an isolated country optimization approach. Thus, the focus is on the development of each national energy system. The results highlight the increase of energy security in line with the European Green Deal. The main pillars of the energy transition are solar energy (32- 33\%), wind energy (25-38\%) and biogenic energy sources (13-27\%). Nuclear power is being phased out in Germany and France. The results show that a Franco-German energy partnership has great potential. Overall, France can cost-effectively cover 25\% of Germany's hydrogen import needs (122 TWh) in 2050. At the same time, France can also benefit from the energy partnership in terms of economic growth and joint action to mitigate climate crisis.}, language = {en} } @article{SavelevGlavanBelanetal., author = {Savelev, Dmitrii V. and Glavan, Gašper and Belan, Viktoria O. and Belyaeva, Inna A. and Fetisov, Leonid Y. and Shamonin (Chamonine), Mikhail}, title = {Resonant Magnetoelectric Effect at Low Frequencies in Layered Polymeric Cantilevers Containing a Magnetoactive Elastomer}, series = {Applied Sciences}, volume = {12}, journal = {Applied Sciences}, number = {4}, publisher = {MPDI}, doi = {10.3390/app12042102}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-30637}, pages = {1 -- 13}, abstract = {In this work, the resonance enhancement of magnetoelectric (ME) coupling at the two lowest bending resonance frequencies was investigated in layered cantilever structures comprising a magnetoactive elastomer (MAE) slab and a commercially available piezoelectric polymer multilayer. A cantilever was fixed at one end in the horizontal plane and the magnetic field was applied horizontally. Five composite structures, each containing an MAE layer of different thicknesses from 0.85 to 4 mm, were fabricated. The fundamental bending resonance frequency in the absence of a magnetic field varied between roughly 23 and 55 Hz. It decreased with the increasing thickness of the MAE layer, which was explained by a simple theory. The largest ME voltage coefficient of about 7.85 V/A was measured in a sample where the thickness of the MAE layer was ≈2 mm. A significant increase in the bending resonance frequencies in the applied DC magnetic field of 240 kA/m up to 200\% was observed. The results were compared with alternative designs for layered multiferroic structures. Directions for future research were also discussed.}, language = {en} } @techreport{Marschall, author = {Marschall, Felix}, title = {HEKATE - Implementierung eines Dashboards zur Visualisierung von Auswertungen des HASKI Konzepts f{\"u}r einen umfassenden Einblick in den Lernprozess}, publisher = {Regensburg}, doi = {10.35096/othr/pub-7922}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-79221}, pages = {XXV, 24 S.}, abstract = {In der gegenw{\"a}rtigen Bildungslandschaft erf{\"a}hrt die adaptive Hochschullehre eine zunehmende Relevanz, da traditionelle Lehrmethoden vielfach nicht mehr hinreichend sind, um den individuellen Bed{\"u}rfnissen der Studierenden zu entsprechen. Das Projekt HEKATE zielt darauf ab, die Erkenntnisse aus dem HASKI-System, einem innovativen Ansatz f{\"u}r personalisierte Lernunterst{\"u}tzung basierend auf KI und maschinellem Lernen, effektiv zu visualisieren. HEKATE erg{\"a}nzt das HASKI-System durch die Entwicklung eines Dashboards, welches eine transparente und nachvollziehbare Darstellung der Lernstildaten erm{\"o}glicht. Das Ziel des Projekts besteht in der Umsetzung einer Visualisierungsl{\"o}sung, die sich durch eine hohe Benutzerfreundlichkeit sowie Leistungsf{\"a}higkeit auszeichnet und alle relevanten Lern- und Nutzungsdaten Studierender ad{\"a}quat abbildet. Die funktionalen Anforderungen umfassten die pr{\"a}zise Darstellung von Lernstil-Ergebnissen, Quiz- und {\"U}bungsergebnissen sowie die Integration des ARIADNE-Konzepts. Des Weiteren werden nichtfunktionale Ziele definiert, welche eine hohe Benutzerfreundlichkeit, Systemsicherheit, kurze Ladezeiten sowie eine verl{\"a}ssliche Datenverarbeitung umfassten. Hekate bietet sowohl f{\"u}r Studierende als auch f{\"u}r Lehrende einen erheblichen Mehrwert, indem es Lern- und Nutzungsmuster auf einfache und intuitive Weise visualisiert. Die Integration in die HASKI-Umgebung und Moodle gew{\"a}hrleistet eine nahtlose Einbindung der Anwendung in bestehende Lernumgebungen, wodurch sich der Nutzen weiter steigert. In k{\"u}nftigen Entwicklungsstufen k{\"o}nnten zus{\"a}tzliche Visualisierungsoptionen und Funktionen integriert werden, um das System weiter zu optimieren und an die Bed{\"u}rfnisse der Nutzer anzupassen.}, language = {de} } @inproceedings{HauserStauferGrabingeretal., author = {Hauser, Florian and Staufer, Susanne and Grabinger, Lisa and R{\"o}hrl, Simon and Mottok, J{\"u}rgen}, title = {On the analysis of student learning strategies: using the LIST-K questionnaire ro generate ai-based individualized learning paths}, series = {Proceedings of the 16th annual International Conference of Education, Research and Innovation (ICERI 2023), Seville, Spain, 11/13/2023 - 11/14/2023}, booktitle = {Proceedings of the 16th annual International Conference of Education, Research and Innovation (ICERI 2023), Seville, Spain, 11/13/2023 - 11/14/2023}, editor = {G{\´o}mez Chova, Luis and Gonz{\´a}lez Mart{\´i}nez, Chelo and Lees, Joanna}, publisher = {IATED}, doi = {10.21125/iceri.2023.1147}, pages = {4611 -- 4620}, abstract = {This paper presents the results of a data collection with the LIST-K questionnaire. This questionnaire measures students' learning strategies and shows which strategies are particularly dominant or rather weak. Learning strategies have long been a major area of research in educational science and psychology. In these disciplines, learning strategies are understood as intentional behaviors and cognitive skills that learners employ to effectively complete learning tasks, by selecting, acquiring, organizing, and integrating information into their existing knowledge for long-term retention. The LIST-K, developed by Klingsieck in 2018, was chosen for accessing learning strategies due to its thematic suitability, widespread use, and test economy. It covers a total of four main categories (i.e., cognitive strategies, metacognitive strategies, management of internal resources, and management of external resources), each of which are subdivided into further subscales. With a total of 39 items answered via a 5-step Likert scale, the LIST-K can cover the topic relatively comprehensively and at the same time be completed in a reasonable amount of time of approximately 10 minutes. The LIST-K was used as part of a combined data collection along with other questionnaires on their personal data, their preferences regarding certain learning elements, their learning style (i.e. the ILS), and personality (i.e. the BFI-10). A total of 207 students from different study programs participated via an online survey created using the survey tool "LimeSurvey". Participation in the study was voluntary, anonymously, and in compliance with the GDPR. Overall, the results of the LIST-K show that students are willing to work intensively on relevant topics intensively and to perform beyond the requirements of the course seeking additional learning material. At the same time, however, it is apparent that the organization of their own learning process could still be improved. For example, students start repeating content too late (mean=2.70; SD=0.92) and do not set goals for themselves and do not create a learning plan (mean=3.19; SD=0.90). They also learn without a schedule (mean=2.23; SD=0.97) and miss opportunities to learn together with other students (mean=3.17; SD=0.94). The findings of the data collection will be used to create an AI-based adaptive learning management system that will create individualized learning paths for students in their respective courses. From the results of the LIST-K, it appears that the adaptive learning management system should primarily support organizational aspects of student learning. Even small impulses (an individual schedule of when to learn what or a hierarchical structuring of the learning material) could help students to complete their courses more successfully and improve their learning.}, language = {en} } @article{FetisovChashinSavelevetal., author = {Fetisov, Yuri K. and Chashin, Dmitri V. and Savelev, Dmitrii V. and Fetisov, Leonid Y. and Shamonin (Chamonine), Mikhail}, title = {Anisotropic Magnetoelectric Effect in a Planar Heterostructure Comprising Piezoelectric Ceramics and Magnetostrictive Fibrous Composite}, series = {Materials}, volume = {12}, journal = {Materials}, number = {19}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/ma12193228}, pages = {1 -- 13}, abstract = {The direct magnetoelectric (ME) effect is investigated in a planar structure comprising mechanically coupled layers of a magnetostrictive fibrous composite (MFC) and a piezoelectric ceramics (lead zirconate titanate, PZT). The MFC is an array of Ni-wires with a diameter of 200 mu m that are aligned parallel to each other in a single layer. The wires are separated by a distance of 250 or 500 mu m and fixed in a polyamide matrix. The structure was placed in a tangential constant field H and was excited by an alternating magnetic field h parallel to H, while the voltage generated by the PZT layer was measured. The resulting field dependences of the magnetization M(H) and the magnetostriction lambda(H) were determined by the orientation of the field H in the plane of the structure and the distance between the Ni-wires. The ME coupling coefficient of the structure decreased from 4.8 to 0.25 V/A when the orientation of H was changed from parallel to perpendicular to Ni-wires. With an increase in the excitation field amplitude h, a nonlinear ME effect in the output voltage, namely frequency doubling, was observed. The frequency and field dependences of the efficiency of the ME transduction in the MFC-piezoelectric heterostructure are well described by the existing theory.}, language = {en} } @techreport{RabindranathBoeseProbstetal., author = {Rabindranath, Raman and B{\"o}se, Holger and Probst, J{\"o}rn and Schlunck, G{\"u}nther and Mayer, Matthias and Forster, Eva and Bentz, Alexander and Shamonin (Chamonine), Mikhail and Monkman, Gareth J.}, title = {EAP mit magnetisch steuerbarer Elastizit{\"a}t zur Interaktion mit Bindegewebszellen MagElan}, address = {Regensburg}, organization = {Hochschule f{\"u}r Angewandte Wissenschaften Regensburg / Fachbereich Elektro- und Informationstechnik}, pages = {37}, language = {de} } @article{SavelevChashinFetisovetal., author = {Savelev, Dmitrii V. and Chashin, Dmitri V. and Fetisov, Leonid Y. and Shamonin (Chamonine), Mikhail and Fetisov, Yuri K.}, title = {Ceramic-Heterostructure-Based Magnetoelectric Voltage Transformer with an Adjustable Transformation Ratio}, series = {Materials}, volume = {13}, journal = {Materials}, number = {18}, publisher = {MDPI}, doi = {10.3390/ma13183981}, pages = {1 -- 13}, abstract = {A voltage transformer employing the magnetoelectric effect in a composite ceramic heterostructure with layers of a magnetostrictive nickel-cobalt ferrite and a piezoelectric lead zirconate-titanate is described. In contrast to electromagnetic and piezoelectric transformers, a unique feature of the presented transformer is the possibility of tuning the voltage transformation ratio K using a dc magnetic field. The dependences of the transformer characteristics on the frequency and the amplitude of the input voltage, the strength of the control magnetic field and the load resistance are investigated. The transformer operates in the voltage range between 0 and 112 V, and the voltage transformation ratio K is tuned between 0 and 14.1 when the control field H changes between 0 and 6.4 kA/m. The power at the transformer output reached 63 mW, and the power conversion efficiency was 34\%. The methods for calculation of the frequency response, and the field and load characteristics of the transformer are proposed. The ways to improve performance characteristics of magnetoelectric transformers and their possible application areas are discussed.}, language = {en} } @article{RomeisKostrovKramarenkoetal., author = {Romeis, Dirk and Kostrov, Sergei A. and Kramarenko, Elena Yu and Stepanov, Gennady V. and Shamonin (Chamonine), Mikhail and Saphiannikova, Marina}, title = {Magnetic-field-induced stress in confined magnetoactive elastomers}, series = {Soft Matter}, volume = {16}, journal = {Soft Matter}, number = {39}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, doi = {10.1039/D0SM01337D}, pages = {9047 -- 9058}, abstract = {We present a theoretical approach for calculating the state of stress induced by a uniform magnetic field in confined magnetoactive elastomers of arbitrary shape. The theory explicitly includes the magnetic field generated by magnetizable spherical inclusions in the sample interior assuming a non-linear magnetization behavior. The initial spatial distribution of particles and its change in an external magnetic field are considered. This is achieved by the introduction of an effective demagnetizing factor where both the sample shape and the material microstructure are taken into account. Theoretical predictions are fitted to the stress data measured using a specifically designed experimental setup. It is shown that the theory enables the quantification of the effect of material microstructure upon introducing a specific microstructural factor and its derivative with respect to the extensional strain in the undeformed state. The experimentally observed differences between isotropic and anisotropic samples, compliant and stiff elastomer matrices are explained.}, language = {en} } @article{SnarskiiShamoninChamonineYuskevichetal., author = {Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Yuskevich, Pavel and Savelev, Dmitrii V. and Belyaeva, Inna A.}, title = {Induced anisotropy in composite materials with reconfigurable microstructure: Effective medium model with movable percolation threshold}, series = {Physica A: Statistical Mechanics and its Applications}, volume = {560}, journal = {Physica A: Statistical Mechanics and its Applications}, number = {December}, publisher = {Elsevier}, doi = {10.1016/j.physa.2020.125170}, abstract = {In composite materials, with field-dependent restructuring of the filler material (changes in the mutual arrangement of inclusions), the presence of an external magnetic field induces anisotropy of the dielectric properties, even if the composite is isotropic in the absence of an external field. A modified effective medium approximation is proposed for the calculation of the components of effective permittivity within a class of composites with reconfigurable microstructure, where both phases (the filler and the matrix) are isotropic and the inclusions have spherical shape. The effective physical properties are calculated in the parallel and perpendicular directions to an applied field. The appearance of the anisotropy of the permittivity is simulated by the introduction of two not-equal, possibly variable (field-dependent) percolation thresholds. The implications, of the proposed theoretical approach, are demonstrated for the case of the dielectric properties of magnetoactive elastomers (MAEs). In MAEs with soft polymer matrices, the mutual arrangement of micrometer-sized magnetic inclusions can significantly change in an applied magnetic field. A reasonable agreement between theory and experiment at a measurement frequency of 1 kHz is found, and is improved in comparison to the previous models. The components of the effective permittivity tensor, characterizing the dielectric properties along the direction of the applied magnetic field and in the orthogonal direction, grow with an increasing field. This growth is more pronounced for the permittivity component in the field direction. The possible extensions of the theoretical model and future directions of research are discussed. The presented theoretical approach can be useful for the application-driven development of a number of smart materials, in particular electro- and magnetorheological gels, elastomers and fluids.}, language = {en} } @article{GlavanBelyaevaRuwischetal., author = {Glavan, Gašper and Belyaeva, Inna A. and Ruwisch, Kevin and Wollschlaeger, Joachim and Shamonin (Chamonine), Mikhail}, title = {Magnetoelectric Response of Laminated Cantilevers Comprising a Magnetoactive Elastomer and a Piezoelectric Polymer, in Pulsed Uniform Magnetic Fields}, series = {Sensors}, volume = {21}, journal = {Sensors}, number = {19}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/s21196390}, pages = {1 -- 19}, abstract = {The voltage response to pulsed uniform magnetic fields and the accompanying bending deformations of laminated cantilever structures are investigated experimentally in detail. The structures comprise a magnetoactive elastomer (MAE) slab and a commercially available piezoelectric polymer multilayer. The magnetic field is applied vertically and the laminated structures are customarily fixed in the horizontal plane or, alternatively, slightly tilted upwards or downwards. Six different MAE compositions incorporating three concentrations of carbonyl iron particles (70 wt\%, 75 wt\% and 80 wt\%) and two elastomer matrices of different stiffness are used. The dependences of the generated voltage and the cantilever's deflection on the composition of the MAE layer and its thickness are obtained. The appearance of the voltage between the electrodes of a piezoelectric material upon application of a magnetic field is considered as a manifestation of the direct magnetoelectric (ME) effect in a composite laminated structure. The ME voltage response increases with the increasing total quantity of the soft-magnetic filler in the MAE layer. The relationship between the generated voltage and the cantilever's deflection is established. The highest observed peak voltage around 5.5 V is about 8.5-fold higher than previously reported values. The quasi-static ME voltage coefficient for this type of ME heterostructures is about 50 V/A in the magnetic field of approximate to 100 kA/m, obtained for the first time. The results could be useful for the development of magnetic field sensors and energy harvesting devices relying on these novel polymer composites.}, language = {en} } @article{SavelevBelyaevaChashinetal., author = {Savelev, Dmitrii V. and Belyaeva, Inna A. and Chashin, Dmitri V. and Fetisov, Leonid Y. and Romeis, Dirk and Kettl, Wolfgang and Kramarenko, Elena Yu and Saphiannikova, Marina and Stepanov, Gennady V. and Shamonin (Chamonine), Mikhail}, title = {Giant extensional strain of magnetoactive elastomeric cylinders in uniform magnetic fields}, series = {Materials}, volume = {13}, journal = {Materials}, number = {15}, publisher = {MDPI}, address = {Basel}, issn = {1996-1944}, doi = {10.3390/ma13153297}, pages = {1 -- 17}, abstract = {Elongations of magnetoactive elastomers (MAEs) under ascending-descending uniform magnetic fields were studied experimentally using a laboratory apparatus specifically designed to measure large extensional strains (up to 20\%) in compliant MAEs. In the literature, such a phenomenon is usually denoted as giant magnetostriction. The synthesized cylindrical MAE samples were based on polydimethylsiloxane matrices filled with micrometer-sized particles of carbonyl iron. The impact of both the macroscopic shape factor of the samples and their magneto-mechanical characteristics were evaluated. For this purpose, the aspect ratio of the MAE cylindrical samples, the concentration of magnetic particles in MAEs and the effective shear modulus were systematically varied. It was shown that the magnetically induced elongation of MAE cylinders in the maximum magnetic field of about 400 kA/m, applied along the cylinder axis, grew with the increasing aspect ratio. The effect of the sample composition is discussed in terms of magnetic filler rearrangements in magnetic fields and the observed experimental tendencies are rationalized by simple theoretical estimates. The obtained results can be used for the design of new smart materials with magnetic-field-controlled deformation properties, e.g., for soft robotics.}, language = {en} } @article{SavelevFetisovChashinetal., author = {Savelev, Dmitrii V. and Fetisov, Leonid Y. and Chashin, Dmitri V. and Fetisov, Yuri K. and Khon, Anastasia and Shamonin (Chamonine), Mikhail}, title = {Effects of ferromagnetic-material thickness on magnetoelectric voltage transformation in a multiferroic heterostructure}, series = {Smart Materials and Structures}, volume = {30}, journal = {Smart Materials and Structures}, number = {6}, publisher = {IOP PUBLISHING}, doi = {10.1088/1361-665X/abf6c0}, abstract = {A magnetoelectric (ME) voltage transformer is fabricated on the basis of a ferromagnetic (FM)-piezoelectric (PE) heterostructure comprising two equally thick laminated layers of an amorphous FM alloy and a piezoceramic lead zirconate-titanate layer sandwiched between them. The structure, placed inside an excitation coil, is electrically poled and magnetized in the direction of the long axis. The primary voltage is applied to the coil and the secondary voltage is measured between the electrodes of the PE material. It is shown for the first time that the change in the total thickness of magnetic layers significantly influences the transformer ' s characteristics. At the largest total thickness of FM layers of 138 mu m, the open-circuit voltage transformation ratio K has a maximum value of about 20, and the power transfer efficiency eta at a matched resistive load of about 20 k omega reaches 45\%. The variation of the control magnetic field in the range of 0-21.6 kA m(-1) makes it possible to change the voltage transformation ratio K from zero to the maximum value. A simple model allows one to calculate the dependence of the characteristics of the ME transformer on the frequency of the primary voltage, thickness of the FM layers, control magnetic field, and the load.}, language = {en} }