@article{SchulzVoglGeigeretal., author = {Schulz, Carsten and Vogl, Yannick and Geiger, Benjamin and Schaeffer, Thomas}, title = {Vor- und Nachteile einer Lumped-Mass-Modellierung von F{\"o}rderb{\"a}ndern am Beispiel eines Zwei-Walzensystems}, series = {Forschung im Ingenieurwesen}, volume = {88}, journal = {Forschung im Ingenieurwesen}, number = {1}, publisher = {Springer Vieweg}, address = {Belrin ; Heidelberg}, issn = {0015-7899}, doi = {10.1007/s10010-024-00736-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-72891}, pages = {9}, abstract = {Im Betrieb von F{\"o}rderb{\"a}ndern auftretende Ph{\"a}nomene sind das Bandwandern in Achsrichtung der Walzen und die Bandverformung in der Bandebene [1, S. 142]. Das Bandwandern ist bisher detailliert untersucht [2-4], w{\"a}hrend die Bandverformung Gegenstand weniger Ver{\"o}ffentlichungen ist. Deshalb wird in diesem Artikel eine Methode zur Berechnung der sich im dynamischen Betrieb einstellenden Verformung eines elastischen F{\"o}rderbandes vorgestellt. Dazu wird ein Mehrk{\"o}rpersimulations-Modell basierend auf der Lumped-Mass-Modellierung verwendet. Als Untersuchungsbeispiel dient ein Zwei-Walzensystem mit flexiblen und zylindrischen Walzen, sowie ein flexibles F{\"o}rderband. Es zeigt sich, dass mit der Lumped-Mass-Modellierung eine dynamische Bandverformung, die von der gew{\"a}hlten Diskretisierung abh{\"a}ngt, berechnet werden kann. Aufgrund dieser Abh{\"a}ngigkeit ist es notwendig eine Konvergenzanalyse durchzuf{\"u}hren. Zus{\"a}tzlich ist darauf zu achten, dass die k{\"u}nstliche Anregung aufgrund der Lumped-Mass-Modellierung nicht mit einer Eigenfrequenz des Modells zusammenf{\"a}llt.}, language = {de} } @article{SchudererRillSchaefferetal., author = {Schuderer, Matthias and Rill, Georg and Schaeffer, Thomas and Schulz, Carsten}, title = {Friction modeling from a practical point of view}, series = {Multibody System Dynamics}, journal = {Multibody System Dynamics}, publisher = {Springernature}, issn = {1384-5640}, doi = {10.1007/s11044-024-09978-0}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-72513}, pages = {18}, abstract = {AbstractRegularized static friction models have been used successfully for many years. However, they are unable to maintain static friction in detail. For this reason, dynamic friction models have been developed and published in the literature. However, commercial multibody simulation packages such as Adams, RecurDyn, and Simpack have developed their own specific stick-slip models instead of adopting one of the public domain approaches. This article introduces the fundamentals of these commercial models and their behavior from a practical point of view. The stick-slip models were applied to a simple test model and a more sophisticated model of a festoon cable system using their standard parameters.}, language = {en} } @article{RillSchaefferSchuderer, author = {Rill, Georg and Schaeffer, Thomas and Schuderer, Matthias}, title = {LuGre or not LuGre}, series = {Multibody System Dynamics}, journal = {Multibody System Dynamics}, publisher = {Springer}, doi = {10.1007/s11044-023-09909-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-65653}, pages = {28}, abstract = {The LuGre model is widely used in the analysis and control of systems with friction. Recently, it has even been made available in the commercial multibody dynamics simulation software system Adams. However, the LuGre model exhibits well-known drawbacks like too low and force rate-dependent break-away forces, drift problems during sticking periods, and significant differences in non-stationary situations between the pre-defined friction law and the one produced by the LuGre model. In the present literature, these problems are supposed to come from the model dynamics or its nonlinear nature. However, most of these drawbacks are not simple side effects of a dynamic friction model but are caused in the LuGre approach, as shown here, by a too simple and inconsistent model of the bristle dynamics. Standard examples and a more practical application demonstrate that the LuGre model is not a "what you see is what you get" approach. A dynamic friction model with accurate bristle dynamics and consistent friction force is set up here. It provides insight into the physical basis of the LuGre model dynamics. However, it results in a nonlinear and implicit differential equation, whose solution will not be easy because of the ambiguity of the friction characteristics. The standard workaround, a static model based on simple regularized characteristics, produces reliable and generally satisfactory results but definitely cannot maintain a stick. The paper presents a second-order dynamic friction model, which may serve as an alternative. It can maintain a stick and produces realistic and reliable results.}, language = {en} } @article{SchwarzPastoetterTranetal., author = {Schwarz, Tobias and Past{\"o}tter, Angelina and Tran, T. H. and Schlosser, Marc and Kaulen, Corinna and Lechner, Alfred and Slabon, A. and Kammler, Martin}, title = {Effect of temperature on the growth of Cupric and Cuprous Nanoparticles in a wet chemical synthesis}, series = {Materials Letters}, volume = {381}, journal = {Materials Letters}, publisher = {Springer Nature}, doi = {10.1016/j.matlet.2024.137672}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-79279}, abstract = {Cuprous oxide (Cu2O) and cupric oxide (CuO) particles were synthesized using a wet chemical surfactant free method at different synthesis temperatures from 25 °C to 60 °C. Morphology, size, and chemical composition of the prepared Cu2O particles were analyzed by FESEM, PXRD, and UV-vis. We discovered that the chemical composition of the Cu2O particles remained unaffected by the synthesis temperature. However, morphology and size of the particles showed a strong temperature dependency. This could be attributed to the temperature induced formation of CuO species from the copper hydroxide (Cu(OH)2) precursor which also functions as copper precursor for the Cu2O particle growth. The cupric oxide species was determined to be the main cause for the formation of micrometer sized particles, whereas with the Cu(OH)2 precursor species for the Cu2O particles nanocubes with smaller edge lengths as well as octahedrons were obtained.}, language = {en} } @article{VoglSchulzSchaefferetal., author = {Vogl, Yannick and Schulz, Carsten and Schaeffer, Thomas and Geiger, Benjamin}, title = {Prediction of the wear behavior of a conveyor belt with flexible rollers}, series = {Multibody System Dynamics}, journal = {Multibody System Dynamics}, publisher = {Springer}, address = {Cham}, issn = {1384-5640}, doi = {10.1007/s11044-025-10097-7}, pages = {16}, abstract = {This paper introduces a method to predict wear behavior in conveyor belt systems using a lumped mass modeling approach. While previous research has focused primarily on lateral belt walking, this study shifts attention to belt deformation and its associated wear. Both significantly affect system efficiency and component lifespan. The authors propose using local frictional power as a wear indicator, leveraging its direct relation to frictional work in established wear models. To solely demonstrate the method, the study simulates a conveyor belt with three flexible rollers and a deformable belt modeled through rigid spheres connected by spring-damper elements. The authors visualize frictional power density across the belt width, distinguishing between running and transverse directions. The results demonstrate that the frictional power distribution depends heavily on discretization quality, particularly due to the polygon effect inherent in the lumped mass approach. A convergence analysis reveals the minimum necessary discretization of the belt, ensuring reliable qualitative results. To support the credibility of the work, this study compares theoretical expectations and initial wear observations from a real belt with the results from the shown approach. The plausibility check already shows promising results. The proposed methodology provides an adaptable framework to evaluate wear in belt-like structures. It can be readily adapted to a variety of multibody dynamics applications and integrated into larger MBS models that include the overall drivetrain and engine control. Future work will focus on refining discretization strategies and contact models, as well as validation of the wear model to enable quantitative predictions.}, language = {en} } @article{MaerklRueckertRauberetal., author = {Maerkl, Raphaela and Rueckert, Tobias and Rauber, David and Gutbrod, Max and Weber Nunes, Danilo and Palm, Christoph}, title = {Enhancing generalization in zero-shot multi-label endoscopic instrument classification}, series = {International Journal of Computer Assisted Radiology and Surgery}, volume = {20}, journal = {International Journal of Computer Assisted Radiology and Surgery}, publisher = {Springer Nature}, doi = {10.1007/s11548-025-03439-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-85674}, pages = {1577 -- 1587}, abstract = {Purpose Recognizing previously unseen classes with neural networks is a significant challenge due to their limited generalization capabilities. This issue is particularly critical in safety-critical domains such as medical applications, where accurate classification is essential for reliability and patient safety. Zero-shot learning methods address this challenge by utilizing additional semantic data, with their performance relying heavily on the quality of the generated embeddings. Methods This work investigates the use of full descriptive sentences, generated by a Sentence-BERT model, as class representations, compared to simpler category-based word embeddings derived from a BERT model. Additionally, the impact of z-score normalization as a post-processing step on these embeddings is explored. The proposed approach is evaluated on a multi-label generalized zero-shot learning task, focusing on the recognition of surgical instruments in endoscopic images from minimally invasive cholecystectomies. Results The results demonstrate that combining sentence embeddings and z-score normalization significantly improves model performance. For unseen classes, the AUROC improves from 43.9\% to 64.9\%, and the multi-label accuracy from 26.1\% to 79.5\%. Overall performance measured across both seen and unseen classes improves from 49.3\% to 64.9\% in AUROC and from 37.3\% to 65.1\% in multi-label accuracy, highlighting the effectiveness of our approach. Conclusion These findings demonstrate that sentence embeddings and z-score normalization can substantially enhance the generalization performance of zero-shot learning models. However, as the study is based on a single dataset, future work should validate the method across diverse datasets and application domains to establish its robustness and broader applicability.}, language = {en} } @article{WeihererEigenbergerEggeretal., author = {Weiherer, Maximilian and Eigenberger, Andreas and Egger, Bernhard and Br{\´e}bant, Vanessa and Prantl, Lukas and Palm, Christoph}, title = {Learning the shape of female breasts: an open-access 3D statistical shape model of the female breast built from 110 breast scans}, series = {The Visual Computer}, volume = {39}, journal = {The Visual Computer}, number = {4}, publisher = {Springer Nature}, doi = {10.1007/s00371-022-02431-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-30506}, pages = {1597 -- 1616}, abstract = {We present the Regensburg Breast Shape Model (RBSM)—a 3D statistical shape model of the female breast built from 110 breast scans acquired in a standing position, and the first publicly available. Together with the model, a fully automated, pairwise surface registration pipeline used to establish dense correspondence among 3D breast scans is introduced. Our method is computationally efficient and requires only four landmarks to guide the registration process. A major challenge when modeling female breasts from surface-only 3D breast scans is the non-separability of breast and thorax. In order to weaken the strong coupling between breast and surrounding areas, we propose to minimize the variance outside the breast region as much as possible. To achieve this goal, a novel concept called breast probability masks (BPMs) is introduced. A BPM assigns probabilities to each point of a 3D breast scan, telling how likely it is that a particular point belongs to the breast area. During registration, we use BPMs to align the template to the target as accurately as possible inside the breast region and only roughly outside. This simple yet effective strategy significantly reduces the unwanted variance outside the breast region, leading to better statistical shape models in which breast shapes are quite well decoupled from the thorax. The RBSM is thus able to produce a variety of different breast shapes as independently as possible from the shape of the thorax. Our systematic experimental evaluation reveals a generalization ability of 0.17 mm and a specificity of 2.8 mm. To underline the expressiveness of the proposed model, we finally demonstrate in two showcase applications how the RBSM can be used for surgical outcome simulation and the prediction of a missing breast from the remaining one. Our model is available at https://www.rbsm.re-mic.de/.}, language = {en} } @article{BrebantWeihererNoisseretal., author = {Br{\´e}bant, Vanessa and Weiherer, Maximilian and Noisser, Vivien and Seitz, Stephan and Prantl, Lukas and Eigenberger, Andreas}, title = {Implants Versus Lipograft: Analysis of Long-Term Results Following Congenital Breast Asymmetry Correction}, series = {Aesthetic Plastic Surgery}, volume = {46}, journal = {Aesthetic Plastic Surgery}, publisher = {Springer Nature}, doi = {10.1007/s00266-022-02843-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-32404}, pages = {2228 -- 2236}, abstract = {Aims Congenital breast asymmetry represents a particular challenge to the classic techniques of plastic surgery given the young age of patients at presentation. This study reviews and compares the long-term results of traditional breast augmentation using silicone implants and the more innovative technique of lipografting. Methods To achieve this, we not only captured subjective parameters such as satisfaction with outcome and symmetry, but also objective parameters including breast vol-ume and anthropometric measurements. The objective examination was performed manually and by using the Vectra H2 photogrammetry scanning system. Results Differences between patients undergoing either implant augmentation or lipograft were revealed not to be significant with respect to patient satisfaction with surgical outcome (p= 0.55) and symmetry (p= 0.69). Furthermore, a breast symmetry of 93 \% was reported in both groups. Likewise, no statistically significant volume difference between the left and right breasts was observed in both groups (p\0.41). However, lipograft patients needed on average 2.9 procedures to achieve the desired result, compared with 1.3 for implant augmentation. In contrast, patients treated with implant augmentation may require anumber of implant changes during their lifetime. Conclusion Both methods may be considered for patients presenting with congenital breast asymmetry.}, language = {en} } @article{SafiBandicNiedermeieretal., author = {Safi, Hila and Bandic, Medina and Niedermeier, Christoph and Almudever, Carmen G. and Feld, Sebastian and Mauerer, Wolfgang}, title = {Stacking the odds: full-stack quantum system design space exploration}, series = {EPJ Quantum Technology}, volume = {12}, journal = {EPJ Quantum Technology}, publisher = {Springer}, address = {Heidelberg}, doi = {10.1140/epjqt/s40507-025-00413-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-85157}, pages = {31}, abstract = {Design space exploration (DSE) plays an important role in optimising quantum circuit execution by systematically evaluating different configurations of compilation strategies and hardware settings. In this paper, we conduct a comprehensive investigation into the impact of various layout methods, qubit routing techniques, and optimisation levels, as well as device-specific properties such as different variants and strengths of noise and imperfections, the topological structure of qubits, connectivity densities, and back-end sizes. By spanning through these dimensions, we aim to understand the interplay between compilation choices and hardware characteristics. A key question driving our exploration is whether the optimal selection of device parameters, mapping techniques, comprising of initial layout strategies and routing heuristics can mitigate device induced errors beyond standard error mitigation approaches. Our results show that carefully selecting software strategies (e.g., mapping and routing algorithms) and tailoring hardware characteristics (such as minimising noise and leveraging topology and connectivity density) significantly improve the fidelity of circuit execution outcomes, and thus the expected correctness or success probability of the computational result. We provide estimates based on key metrics such as circuit depth, gate count and expected fidelity. Our results highlight the importance of hardware-software co-design, particularly as quantum systems scale to larger dimensions, and along the way towards fully error corrected quantum systems: Our study is based on computationally noisy simulations, but considers various implementations of quantum error correction (QEC) using the same approach as for other algorithms. The observed sensitivity of circuit fidelity to noise and connectivity suggests that co-design principles will be equally critical when integrating QEC in future systems. Our exploration provides practical guidelines for co-optimising physical mapping, qubit routing, and hardware configurations in realistic quantum computing scenarios.}, language = {en} } @article{HantschWestnerMatschi, author = {Hantsch, Carolin and Westner, Markus and Matschi, Markus}, title = {IT/OT-Konvergenz: Status-Quo und Umsetzungsempfehlungen}, series = {HMD Praxis der Wirtschaftsinformatik}, journal = {HMD Praxis der Wirtschaftsinformatik}, publisher = {Springer Nature}, doi = {10.1365/s40702-024-01111-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77937}, pages = {16}, abstract = {Organisationen machen große Anstrengungen zur Verbesserung ihrer Ambidextrie, d. h. ihrer F{\"a}higkeit sowohl Exploitationsziele (z. B. Effizienz, Vorhersagbarkeit) als auch Explorationsziele (z. B. Anpassbarkeit, Innovation) zu erreichen. Obwohl gem{\"a}ß der Praxisliteratur Technologie in Software-Projekten dabei eine zentrale Rolle spielen kann, gibt es kaum Forschung dazu, wie technologische Faktoren Ambidexterie in Software-Projekten beeinflussen. In dieser Studie untersuchen wir die Rolle dreier technologischer Faktoren: kontinuierliche Integration, Standardisierung und Microservice-Architektur. Die Ergebnisse einer Mehrinformanten-Umfrage in 95 Projekten in der Schweiz und D{\"a}nemark zeigen, dass kontinuierliche Integration und Standardisierung mit h{\"o}herer Ambidexterie einhergehen, w{\"a}hrend der Zusammenhang zwischen Microservice-Architektur und Ambidextrie nicht signifikant ist. Unser Artikel geht {\"u}ber die existierende Forschung hinaus, indem er zeigt, dass kontinuierliche Integration und Standardisierung nicht nur Exploitation, sondern auch Exploration f{\"o}rdern k{\"o}nnen. Wir diskutieren auch Gr{\"u}nde f{\"u}r den insignifikanten Zusammenhang zwischen Microservice-Architektur und Ambidextrie.}, language = {de} } @article{SchummBrownAbdelKhaleketal., author = {Schumm, Leon and Brown, Tom and Abdel-Khalek, Hazem and Ueckerdt, Falko and Sterner, Michael and Fioriti, David and Parzen, Max}, title = {The impact of temporal hydrogen regulation on hydrogen exporters and their domestic energy transition}, series = {Nature Communications}, volume = {16}, journal = {Nature Communications}, publisher = {Nature}, address = {London}, doi = {10.1038/s41467-025-62873-w}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-84857}, pages = {13}, abstract = {As global demand for green hydrogen rises, potential hydrogen exporters move into the spotlight. While exports can bring countries revenue, large-scale on-grid hydrogen electrolysis for export can profoundly impact domestic energy prices and energy-related emissions. Our investigation explores the interplay of hydrogen exports, domestic energy transition and temporal hydrogen regulation, employing a sector-coupled energy model in Morocco. We find substantial co-benefits of domestic carbon dioxide mitigation and hydrogen exports, whereby exports can reduce market-based costs for domestic electricity consumers while mitigation reduces costs for hydrogen exporters. However, increasing hydrogen exports in a fossil-dominated system can substantially raise market-based costs for domestic electricity consumers, but surprisingly, temporal matching of hydrogen production can lower these costs by up to 31\% with minimal impact on exporters. Here, we show that this policy instrument can steer the welfare (re-)distribution between hydrogen exporting firms, hydrogen importers, and domestic electricity consumers and hereby increases acceptance among actors.}, language = {en} }