@inproceedings{64787, abstract = {{This study proposes a fault diagnostics methodology that addresses the challenges posed by highly imbalanced datasets typical of railway applications, where faulty conditions constitute the minority class. Fault diagnostics is performed from the component level upward, considering each sensor’s proximity to its respective critical component. Advanced signal analysis, feature engineering, and automated data-driven model generation techniques were explored to achieve comprehensive diagnostics, such that the model development process accounts for variations in the operating conditions and differing levels of information availability. The proposed methodology is evaluated on datasets from the MONOCAB, for scenarios with limited faulty instances and on the Beijing 2024 IEEE PHM Conference data challenge, which focused on fault diagnostics of railway systems under various fault modes and operating conditions.}}, author = {{Aimiyekagbon, Osarenren Kennedy and Löwen, Alexander and Hanselle, Raphael and Rief, Thomas and Beck, Maximilian and Sextro, Walter}}, booktitle = {{PHM Society Asia-Pacific Conference}}, keywords = {{MONOCAB, Beijing Data Challenge, Diagnostics of railway systems}}, title = {{{Multilevel fault diagnostics for railway applications using limited historical data}}}, doi = {{10.36001/phmap.2025.v5i1.4449}}, volume = {{5}}, year = {{2025}}, } @inproceedings{64798, abstract = {{Lead-containing piezoelectric ceramics are still the base for today’s ultrasonic transducers used in broad applications. This is partly due to missing powerful lead-free piezoelectric ceramic parts in the commercial market. There has been much research on lead-free materials but developing them into marketable parts seems to be an ongoing process. The actual exemption of ROHS has expired, but as the new exemption has already been requested, ceramic suppliers keep on selling lead containing products. Nevertheless, these should be replaced by lead-free alternatives for environmental and health issues. This contribution focuses on exploring the technological readiness level of lead-free hard piezoceramics for prestressed ultrasonic transducers. A small series of bolted Langevin transducers was set up with standard PZT material and three commercial lead-free variants. Results of the building process from individual ring ceramic characteristics to transducer load tests are presented. The main finding of this study is that the lead-free materials technically can compete with the standard PZT for medium-power applications. Some adaptations in the ultrasonic system must be done: the geometry must be altered to fit resonance frequency, and higher voltages or thinner ceramics are needed to achieve the same vibration level at low load. For reaching same power, the volume of lead-free ceramics must be 1.5 to 3 times larger. As already promoted in literature, mechanical losses at high vibration levels are smaller for the lead-free materials. This might help to argument lead-free piezoelectric materials in some applications. References 1. Directive 2011/65/EU of the European Parliament and of the Council of 8 June 2011 on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment. EUR-Lex Document 02011L0065-20240801. Available online: http://data.europa.eu/eli/dir/2011/65/2024-08-01 (accessed on 24 January 2025). 2. Langevin, P. (1918) Method and Apparatus for Transmitting and Receiving Submarine Elastic Waves Using the Piezoelectric Properties of Quartz. French Patent Office; Patent No. FR505703. 3. Hemsel, T.; Twiefel, J. (2023) Piezoelectric Ultrasonic Power Transducers. In Encyclopedia of Materials: Electronics; Academic Press: Oxford, UK; pp. 276–285. https://doi.org/10.1016/b978-0-12-819728-8.00047-4. 4. ATHENA Technologie Beratung GmbH (2025) Description of Ultrasound Generator. Available online: http://shop.myathena.de/epages/12074748.sf/de_DE/?ObjectPath=/Shops/12074748/Products/AM200 (accessed on 13 January 2025). 5. Littmann, W.; Hemsel, T.; Kauczor, C.; Wallaschek, J.; Sinha, W. (2003) Load-adaptive phase-controller for resonant driven piezoelectric devices. Proc. World Congr. Ultrason. 2003, 48, 547–550. 6. Scheidemann, C., Bornmann, P., Littmann, W., & Hemsel, T. (2025). Lead-Free Ceramics in Prestressed Ultrasonic Transducers. Actuators, 14(2), 55. https://doi.org/10.3390/act14020055 }}, author = {{Scheidemann, Claus and Bornmann, Peter and Littmann, Walter and Hemsel, Tobias}}, keywords = {{lead free piezoelectric ceramics, bolted Langevin transducer, medium power ultrasound.}}, location = {{Vilnius, Lithuania}}, title = {{{Bolted Langevin transducers with leadfree piezoelectric ceramics}}}, year = {{2025}}, } @inproceedings{64800, abstract = {{Intensive ultrasonic cleaning of surfaces by means of a lead-free ultrasonic transducer with focusing sonotrode Ultrasonic cleaning baths are probably a coincidental development: After underwater sonars had already been successfully used to detect submarines before 1920, it was probably observed in this environment that the ultrasonic oscillators not only showed a self-cleaning effect but also cavitation damage. At the beginning of the 1950s, the first ultrasonic cleaning devices finally came onto the market. Today, the range of applications ranges from household appliances for jewellery and eyewear cleaning to classic cleaning baths for metal parts and systems for cleaning highly sensitive electronic components. There is a certain gap in handheld, mobile cleaning equipment. Although devices for spot cleaning of textiles are known, the cleaning effect is usually low. Due to the directive 2011/65/EU on the restriction of the use of hazardous substances in electrical and electronic equipment (RoHS) [1] lead should no longer be used in technical devices. As today’s standard ceramics for medium and high-power ultrasonic transducers typically contain lead, there is a need to explore the use of lead-free ceramics in this field. Honda [2] already offers a cleaning transducer based on lead-free piezoelectric ceramics, but it is designed to be used in cleaning baths. This article presents the model-based development of a highly innovative ultrasonic cleaner. On the one hand, lead-free piezoelectric ceramics are used, and on the other hand, a special sonotrode has been developed that concentrates the sound in such a way that a strong cavitation and thus cleaning effect is achieved with comparatively low power in a short time. Coupled field finite element method was used to find an appropriate geometry for the focussing sonotrode. The comparison of simulation and measurement results shows that the lead-free piezoceramics used do their job well and can keep up with standard ceramics, but more ceramic volume is needed to achieve same power. An advanced control concept was elaborated to ensure continuous hard cavitation at varying distances between the sonotrode and the part to be cleaned. Cleaning results for different surfaces and contaminations are presented. The concept of the focusing sonotrode shows that a convincing cleaning result can be achieved even with low power and in short time, provided that the oscillation system and control electronics are suitably coordinated. References [1] http://data.europa.eu/eli/dir/2011/65/2024-08-01 [2] https://en.honda-el.co.jp/product/ceramics/lineup/lead_off/lead-off }}, author = {{Hemsel, Tobias and Scheidemann, Claus and Bornmann, Peter and Littmann, Walter and Sextro, Walter}}, location = {{Paderborn, Germany}}, title = {{{Intensive ultrasonic cleaning of surfaces by means of lead-free ultrasonic transducer with focussing sonotrode}}}, year = {{2025}}, } @inproceedings{61755, author = {{Scheidemann, Claus and Hemsel, Tobias and Sextro, Walter}}, location = {{Vilnius, Lithuania}}, title = {{{Time dependent material characteristics of prestressed piezoelectric ceramics in langevin transducers}}}, year = {{2025}}, } @inproceedings{61757, author = {{Scheidemann, Claus and Porzenheim, Julius and Hemsel, Tobias and Sextro, Walter}}, location = {{Paderborn, Germany}}, title = {{{Investigation of the Setting Behaviour of Mechanically Biased Piezoelectric Ultrasonic Transducers}}}, year = {{2025}}, } @inbook{62988, author = {{Amakor, Augustina C. and Berkemeier, Manuel B. and Wohlleben, Meike Claudia and Sextro, Walter and Peitz, Sebastian}}, booktitle = {{Lecture Notes in Computer Science}}, isbn = {{9783032045546}}, issn = {{0302-9743}}, publisher = {{Springer Nature Switzerland}}, title = {{{Surrogate-Assisted Multi-objective Design of Complex Multibody Systems}}}, doi = {{10.1007/978-3-032-04555-3_21}}, year = {{2025}}, } @inproceedings{64812, author = {{Hofmann, Julia and Teutenberg, Dominik and Meschut, Gerson}}, booktitle = {{25. Kolloquium: Gemeinsame Forschung in der Klebtechnik}}, location = {{Köln}}, title = {{{Methodenentwicklung zur numerischen Auslegung von Klebverbindungen mit lackierten Fügeteilen}}}, year = {{2025}}, } @inproceedings{64611, abstract = {{Für die Aufrechterhaltung der natürlichen Ressourcen ist eine effiziente Nutzung dieser essenziell. Vor diesem Hintergrund untersucht das vorliegende Paper die Rolle der Kreislaufwirtschaft als wegweisendes Wirtschaftsmodell, das von der Europäischen Union gefördert wird. Ziel der Kreislaufwirtschaft ist es, den Ressourcenverbrauch und die Abfallproduktion zu minimieren, indem ein kontinuierlicher Kreislauf aus Nutzung, Wiederverwendung und Recycling von Materialien geschaffen wird. Ein zentraler Aspekt dabei ist der Produktentwicklungsprozess (PEP) - ein vielschichtiger Prozess mit zahlreichen Einflussfaktoren und theoretisch unbegrenzten Gestaltungsmöglichkeiten. Diese Vielfalt führt jedoch zu erheblichen Entscheidungsunsicherheiten, die die Umsetzung von Kreislaufwirtschaftsprinzipien erschweren können. Um diese Herausforderungen zu adressieren, wird ein methodischer Prozess vorgestellt, der eine systematische Klassifizierung im Zusammenhang mit umliegenden Bauteilen ermöglicht. Die Methodik basiert auf einer strukturierten Bewertung von Bauteilen hinsichtlich ihrer Relevanz für die Kreislaufwirtschaft. Dabei werden zentrale Aspekte wie Wiederverwendbarkeit, Recyclingfähigkeit und Ressourceneffizienz berücksichtigt, darunter: • Handelt es sich um ein Gebrauchs- oder Verbrauchsprodukt? • Ist das Bauteil eine Wiederverwendung oder eine Neufertigung? • Ist das Bauteil standardisiert, zugekauft oder individuell ausgerichtet? • Welche primäre Funktion nimmt das Bauteil ein? Diese strukturierte Klassifizierung unterstützt die Entscheidungsfindung bereits früh im PEP. Sie ermöglicht es Produktentwickelnden, Potenziale für die Kreislaufwirtschaft frühzeitig zu erkennen und gezielt nachhaltige Maßnahmen zu ergreifen. Die entwickelte Methodik bildet somit eine Grundlage für die Integration kreislaufwirtschaftlicher Prinzipien in den Entwicklungsprozess. Insbesondere im Kontext moderner Anforderungen des Mobility Management zeigt sich ihr Potenzial, nachhaltige Innovationen gezielt zu fördern und die Umsetzung der Kreislaufwirtschaft in der industriellen Praxis zu erleichtern.}}, author = {{Rohde, Katharina and Ott, Manuel and Budde, Finn Lukas and Mozgova, Iryna}}, booktitle = {{Solving Conflicts on the Way to Sustainable Mobility: Technische und betriebswirtschaftliche Aspekte}}, editor = {{Proff, Heike}}, location = {{Duisburg}}, publisher = {{Springer Nature Meteor}}, title = {{{Optimierung modularer Produkte für die Mobilität: Ein Klassifizierungsrahmen für zirkuläre Produkte}}}, year = {{2025}}, } @inproceedings{64804, abstract = {{Das Ultraschallschweißen ist in der Verpackungs-, Halbleiter- und Automobilindustrie weit verbreitet. Neben dem Schweißen von Blechen bietet es die Möglichkeit, Folien oder Hülsen zu verschweißen. Konventionelle Schweißsysteme arbeiten mit Längs- oder Biegeschwingungen, deren Hauptanteil in der Schweißebene liegt. Der orthogonale Anteil verursacht zusätzliche Belastungen im Schweißgut. Bei der Verwendung von Torsionsschwingungen wird die orthogonale Komponente der Schwingung nahezu eliminiert. In diesem Beitrag wird ein System vorgestellt, bei dem die Torsionsschwingung durch tangentiale Polarisation der Piezokeramiken erzeugt wird. Der Transducer ist axial oberhalb des Schweißpunktes platziert, sodass die Normalkraft momentfrei aufgebracht wird. Das Schweißwerkzeug weicht beim Schweißvorgang daher seitlich nicht aus. Zudem wird das Schweißen an schwer zugänglichen Positionen vereinfacht, da der Systemaufbau deutlich schlanker ist als konventionelle Ultraschallschweißsysteme. Die Auslegung des Torsionsschwingsystems stellt eine Herausforderung dar. Insbesondere muss die Lagerung des Schwingers betrachtet werden, da diese die Normalkraft übertragen und zugleich die Schwingung nicht beeinträchtigen soll. Der Schweißprozess bewirkt eine Verschiebung von Schwingungsknoten und Resonanzfrequenzen. Im Rahmen des Vortrags wird ein Finite-Elemente-Simulationsmodell vorgestellt, das in Kombination mit einem Lastmodell das Systemverhalten während des Schweißprozesses abbildet. Die Geometrie des Transducers wurde schrittweise so angepasst, dass die Schwingamplitude im Lagerungspunkt minimiert wird. }}, author = {{Dohmen, Markus Daniel and Bornmann, Peter and Littmann, Walter and Hemsel, Tobias and Sextro, Walter}}, title = {{{Modellgestützte Optimierung eines Ultraschall-Torsionsschweißsystems}}}, year = {{2025}}, } @article{61223, abstract = {{Contemporary debates about artificial intelligence (AI) still treat automation as a straightforward substitution of human labor by machines. Drawing on Goffman’s dramaturgical sociology, this paper reframes AI in the workplace as supplementary rather than substitutive automation. We argue that the central—but routinely overlooked—terrain of struggle is symbolic-interactional: workers continuously stage, conceal, and re-negotiate what counts as “real” work and professional competence. Large language models (LLMs) such as ChatGPT exemplify this dynamic. They quietly take over the invisible, routinised tasks that underpin cognitive occupations (editing, summarizing, first-draft production) while leaving humans to enact the highly visible or relational facets that sustain occupational prestige. Drawing on diverse sources to illustrate our theoretical argument, we show how individual workers, dramaturgical teams, and entire professional fields manage impressions of expertise in order to counter status threats, renegotiate fees, or obscure the extent of AI assistance. The paper itself, having been intentionally written with the ‘aid’ of all presently available frontier AI models, serves as a meta-reflexive performance of professional self-staging. The dramaturgical framework clarifies why utopian tales of friction-free augmentation and dystopian narratives of total displacement both misread how automation is actually unfolding. By foregrounding visibility, obfuscation, and impression management, the article presents a differentiated case for AI’s impact on the performative structure of work, outlines diagnostic tools for assessing real-world AI exposure beyond hype-driven headlines, and argues for a more human-centered basis for evaluating policy responses to the ‘fourth industrial revolution.’ In short, AI enters the labor process not as an autonomous actor, but as a prop within an ongoing social performance—one whose scripts, stages, and audiences remain irreducibly human.}}, author = {{Klowait, Nils and Erofeeva, Maria}}, issn = {{2297-7775}}, journal = {{Frontiers in Sociology}}, publisher = {{Frontiers Media SA}}, title = {{{The presentation of self in the age of ChatGPT}}}, doi = {{10.3389/fsoc.2025.1614473}}, volume = {{10}}, year = {{2025}}, } @inbook{61226, author = {{Erofeeva, Maria and Klowait, Nils and Belov, Mikael and Soulié, Yoann}}, booktitle = {{Communications in Computer and Information Science}}, isbn = {{9783031980794}}, issn = {{1865-0929}}, publisher = {{Springer Nature Switzerland}}, title = {{{Leveraging VR Tools for Inclusive Education: Implications from Sign Language Learning in VRChat}}}, doi = {{10.1007/978-3-031-98080-0_10}}, year = {{2025}}, } @inproceedings{61341, author = {{Beimdiek, Janis and Schmid, Hans-Joachim}}, location = {{Paderborn}}, title = {{{SFS-gestützte Synthese von Katalysatorpartikeln zur selektiven katalytischen Reduktion von NOx}}}, year = {{2025}}, } @inproceedings{61343, author = {{Beimdiek, Janis and Schmid, Hans-Joachim}}, location = {{Nürnberg}}, title = {{{Influence of surface impurities on the catalytic activity of nanoparticles synthesized by a spray flame synthesis (oral presentation)}}}, year = {{2025}}, } @inproceedings{59566, author = {{Beimdiek, Janis and Schmid, Hans-Joachim}}, location = {{Clausthal-Zellerfeld}}, title = {{{Selektive katalytische Reduktion von NOx an gasphasensynthetisierten Katalysatorpartikeln (Vortrag)}}}, year = {{2025}}, } @misc{61346, author = {{El Gabbouhi, Abderazzak and Massopo, Orlando and Jesinghausen, Steffen and Schmid, Hans-Joachim}}, title = {{{Untersuchung des Einflusses der Zusammensetzung von Lösungsmitteln und Gasen bei der Herstellung nanoskaliger Eisenoxide mittels Sprühflammensynthese}}}, year = {{2025}}, } @inproceedings{61396, author = {{Nölle, Florian and Schmid, Hans-Joachim and Bentrup, Leon Alexander and Temmen, Katrin}}, booktitle = {{MINT-Symposium}}, location = {{Nürnberg}}, title = {{{Erfolgreich Studieren - sinnvolle Lernstrategien erlernen (Posterbeitrag)}}}, year = {{2025}}, } @misc{61271, author = {{Tschöpe, Cedric}}, title = {{{Entwicklung flammgeschützter Kunststoffpulver für das Lasersintern: Einfluss von Phosphor-, Füllstoffanteilen und Belichtungsparametern}}}, year = {{2025}}, } @misc{61485, author = {{Frye, Thomas}}, title = {{{Untersuchung der Wechselwirkungen zwischen Aluminiumdiethylphosphinat und zinkbasierten Füllstoffen als synergistische Flammschutzmittel in Polyamid 12 für das selektive Lasersintern}}}, year = {{2025}}, } @article{61526, author = {{Olfert, Viktoria and Bähr, Philipp and Schuster, Lilia and Westhoff, Julia and Yang, Keke and Ibeski, Enes and Hein, David and Sommer, Silke and Meschut, Gerson}}, journal = {{Journal of Manufacturing Processes}}, pages = {{311--331}}, publisher = {{Elsevier}}, title = {{{Failure behavior prediction for resistance spot-welded three-layered dissimilar joints with advanced high-strength steel}}}, doi = {{https://doi.org/10.1016/j.jmapro.2025.09.077}}, volume = {{154}}, year = {{2025}}, } @article{61138, author = {{Zhan, Yingjie and Caylak, Ismail and Ostwald, Richard and Barth, Enrico and Uhlmann, Eckart}}, issn = {{2520-8160}}, journal = {{Multiscale and Multidisciplinary Modeling, Experiments and Design}}, number = {{10}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Damage-incorporated four-step mean-field method for simulating CFRP machining: a novel algorithmic approach}}}, doi = {{10.1007/s41939-025-01026-4}}, volume = {{8}}, year = {{2025}}, }