@article{MaierSchlattlGuessetal., author = {Maier, Robert and Schlattl, Andreas and Guess, Thomas and Mottok, J{\"u}rgen}, title = {CausalOps - Towards an industrial lifecycle for causal probabilistic graphical models}, series = {Information and Software Technology}, journal = {Information and Software Technology}, publisher = {Elsevier}, issn = {0950-5849}, doi = {10.1016/j.infsof.2024.107520}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-73350}, abstract = {Context: Causal probabilistic graph-based models have gained widespread utility, enabling the modeling of cause-and-effect relationships across diverse domains. With their rising adoption in new areas, such as safety analysis of complex systems, software engineering, and machine learning, the need for an integrated lifecycle framework akin to DevOps and MLOps has emerged. Currently, such a reference for organizations interested in employing causal engineering is missing. This lack of guidance hinders the incorporation and maturation of causal methods in the context of real-life applications. Objective: This work contextualizes causal model usage across different stages and stakeholders and outlines a holistic view of creating and maintaining them within the process landscape of an organization. Method: A novel lifecycle framework for causal model development and application called CausalOps is proposed. By defining key entities, dependencies, and intermediate artifacts generated during causal engineering, a consistent vocabulary and workflow model to guide organizations in adopting causal methods are established. Results: Based on the early adoption of the discussed methodology to a real-life problem within the automotive domain, an experience report underlining the practicability and challenges of the proposed approach is discussed. Conclusion: It is concluded that besides current technical advancements in various aspects of causal engineering, an overarching lifecycle framework that integrates these methods into organizational practices is missing. Although diverse skills from adjacent disciplines are widely available, guidance on how to transfer these assets into causality-driven practices still need to be addressed in the published literature. CausalOps' aim is to set a baseline for the adoption of causal methods in practical applications within interested organizations and the causality community.}, language = {en} } @article{BauerSterner, author = {Bauer, Franz and Sterner, Michael}, title = {Impacts of lifestyle changes on energy demand and greenhouse gas emissions in Germany}, series = {Renewable and Sustainable Energy Reviews}, volume = {207}, journal = {Renewable and Sustainable Energy Reviews}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1364-0321}, doi = {10.1016/j.rser.2024.114944}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77682}, pages = {17}, abstract = {Most energy scenario studies typically focus on technological options and fuel substitution for decarbonising future energy systems. Lifestyle changes are rarely considered, although they can significantly reduce energy demand and climate change mitigation efforts. By using an energy system model, this study shows that it is possible to reduce final energy demand in Germany by 61 \% in 2050 relative to 2019 levels, resulting in an annual per capita energy demand of 44 GJ for a representative country of the Global North. This goal can be achieved through a combination of technological measures and lifestyle changes without sacrificing a decent standard of living. Societal chances can eliminate reliance on not-yet-established negative emission technologies, reduce energy dependency, and reduce the need for energy-intensive hydrogen and e-fuels. Downsizing the energy system provides an opportunity for strengthening climate change mitigation, decrease material demand and reduce land use.}, language = {en} } @article{EscherRueckJobstetal., author = {Escher, Lukas and R{\"u}ck, Thomas and Jobst, Simon and Pangerl, Jonas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Photodissociation-Driven Photoacoustic Spectroscopy with UV-LEDs for Ozone Detection}, series = {Photoacoustics}, volume = {43}, journal = {Photoacoustics}, publisher = {Elsevier BV}, issn = {2213-5979}, doi = {10.1016/j.pacs.2025.100718}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-80076}, pages = {16}, abstract = {This study presents the development and evaluation of a UV-LED based photoacoustic (PA) measurement system for ozone (O3) detection to demonstrate its potential for low-cost and accurate sensing while for the first time addressing the importance of photodissociation for PA signal generation for O3 in the UV range. With a detection limit of 7.9 ppbV, the system exhibits a significant advancement over state-of-the-art UV-PA O3 detection and is on par with laser-based setups. Following a novel discussion of the PA signal arising from photodissociation and its products, cross-sensitivity effects due to environmental factors such as temperature and gas composition were systematically analyzed. A digital twin driven compensation for these influences was implemented and evaluated. Despite the challenges associated with modeling the effects of H2O and CO2, the PA system shows considerable potential, though further studies in real world applications must be conducted.}, language = {en} } @article{KrieglKrenkelShamoninChamonine, author = {Kriegl, Raphael and Krenkel, Lars and Shamonin (Chamonine), Mikhail}, title = {Preservation of wetting ridges using field-induced plasticity of magnetoactive elastomers}, series = {Journal of Colloid and Interface Science}, volume = {683}, journal = {Journal of Colloid and Interface Science}, publisher = {Elsevier}, issn = {0021-9797}, doi = {10.1016/j.jcis.2024.12.132}, pages = {1019 -- 1027}, abstract = {Hypothesis. The presence of a wetting ridge is crucial for many wetting phenomena on soft substrates. Conventional experimental observations of a wetting ridge require permanent presence of a droplet. The magnetic field-induced plasticity effect (FIPE) of soft magnetoative elastomers (MAEs) allows one to overcome this limitation. Depositing a droplet onto an MAE surface and applying a magnetic field fixes the wetting ridge in place due to the FIPE. The droplet can be removed to investigate the ridge with ease using conventional optical methods. Experiments. The wetting ridge is observed on MAEs with different shear moduli and different material thicknesses by confocal laser scanning microscopy (LSM). The preservation quality of the ridge is analyzed for several values of magnetic field from 10 mT to 270 mT. To verify the plausibilty of results obtained, the measured shape is compared to a theoretical model by Style \& Dufresne. Findings. Upon removal of the sessile droplet, the deformation remains embossed onto the MAE surface as long as the magnetic field remains applied. The height of the ridge peak on soft samples (effective shear modulus kPa) is close to the theoretical prediction for a magnetic flux density of 50 mT. The magnitude of the external magnetic field magnifies the height of the wetting ridge.}, language = {en} } @article{KloiberAnetsbergerSchultheissetal., author = {Kloiber, Jessica and Anetsberger, Viktoria and Schultheiß, Ulrich and Hornberger, Helga}, title = {High quality surfaces of magnesium alloy AZ31 by adjusting appropriate electropolishing parameters}, series = {Electrochimica Acta}, volume = {513}, journal = {Electrochimica Acta}, publisher = {Elsevier}, doi = {10.1016/j.electacta.2024.145547}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-79298}, language = {en} } @article{KloiberSchultheissHornberger, author = {Kloiber, Jessica and Schultheiß, Ulrich and Hornberger, Helga}, title = {Impact of heat treatment on the surface quality of electropolished WE43 alloy}, series = {Materials Letters}, volume = {397}, journal = {Materials Letters}, publisher = {Elsevier BV}, issn = {0167-577X}, doi = {10.1016/j.matlet.2025.138821}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-83512}, pages = {5}, abstract = {In this study, the Mg alloy WE43 was solution annealed and precipitation hardened prior to electropolishing to evaluate the effects of different microstructures on the electropolishing result. While coarsely distributed precipitates led to surfaces showing wavy structures and dents after electropolishing, a uniform microstructure resulted in an even finish of the surface. The homogenization and refinement of the microstructure by heat treatment is a method to ensure improved electropolished surfaces of Mg materials}, language = {en} } @article{SternerHofrichterMeisingeretal., author = {Sterner, Michael and Hofrichter, Andreas and Meisinger, Alexander and Bauer, Franz and Pinkwart, Karsten and Maletzko, Annabelle and Dittmar, Felix and Cremers, Carsten}, title = {19 Import options for green hydrogen and derivatives - An overview of efficiencies and technology readiness levels}, series = {International Journal of Hydrogen Energy}, volume = {90}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2024.10.045}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77756}, pages = {1112 -- 1127}, abstract = {The import of hydrogen and derivatives forms part of many national strategies and is fundamental to achieving climate protection targets. This paper provides an overview and technical comparison of import pathways for hydrogen and derivatives in terms of efficiency, technological maturity and development and construction times with a focus on the period up to 2030. The import of hydrogen via pipeline has the highest system efficiency at 57-67 \% and the highest technological maturity with a technology readiness level (TRL) of 8-9. The import of ammonia and methanol via ship and of SNG via pipeline shows efficiencies in the range of 39-64 \% and a technological maturity of TRL 7 to 9 when using point sources. Liquid hydrogen, LOHC and Fischer-Tropsch products have the lowest efficiency and TRL in comparison. The use of direct air capture (DAC) reduces efficiency and TRL considerably. Reconversion of the derivatives to hydrogen is also associated with high losses and is not achievable for all technologies on an industrial scale up to 2030. In the short to medium term, import routes for derivatives that can utilise existing infrastructures and mature technologies are the most promising for imports. In the long term, the most promising option is hydrogen via pipelines.}, language = {en} } @article{PangerlSukulRuecketal., author = {Pangerl, Jonas and Sukul, Pritam and R{\"u}ck, Thomas and Escher, Lukas and Miekisch, Wolfram and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Photoacoustic trace-analysis of breath isoprene and acetone via interband- and Quantum Cascade Lasers}, series = {Sensors and Actuators: B. Chemical}, volume = {424}, journal = {Sensors and Actuators: B. Chemical}, publisher = {Elsevier}, doi = {10.1016/j.snb.2024.136886}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77024}, pages = {12}, abstract = {This research presents two laser-based photoacoustic approaches for analyzing exhaled breath isoprene and acetone. The integration of a PTR-ToF-MS as a reference device ensured the reliability and accuracy of the photoacoustic systems that is based on an ICL for isoprene and a QCL for acetone detection. The calibration yielded limits of detection of 26.9 ppbV and 1.7 ppbV, respectively, and corresponding normalized noise equivalent absorption coefficients (NNEAs) of 5.0E-9 Wcm 1Hz 0.5 and 4.9E-9 Wcm 1Hz 0.5. Laboratory as well as real breath sample measurements from alveolar breath revealed a robust system performance, with only one outlier within the static isoprene measurements. However, discrepancies emerged under dynamic breath sampling conditions, emphasizing the need for further optimization. Especially by knowing the dynamic nature and endogenous origin of exhaled isoprene our findings highlight the potential of breath analysis for non-invasive physio-metabolic and pathophysiological monitoring towards point-of-care devices}, language = {en} } @article{PutzSchirmerSattleretal., author = {Putz, Christoph and Schirmer, Maximilian and Sattler, Robert and Monkman, Gareth J.}, title = {Fabrication of Bisphenol-free Boron-Siloxane Polymers}, series = {Materials Chemistry and Physics}, journal = {Materials Chemistry and Physics}, edition = {Journal Pre-proof}, publisher = {Elsevier}, doi = {10.1016/j.matchemphys.2025.130567}, abstract = {Interest in the preparation of magnetoactive boron-siloxane polymers (MBP) has been stimulated by recent scientific developments. However, recent regulations have prohibited the inclusion of Bisphenol-A normally employed in the manufacture of commercially available products. In the following publication, two different routes for the preparation of magnetoactive borosiloxane polymers have been taken. First, the possibilities of obtaining homogeneous mixtures of magnetoactive polymers by mixing the magnetic particles with the polymer using solid CO2 (dry ice) and stirring (shearing) are investigated. In the course of the work, an approach for the preparation of reference materials of different viscosities was made to prove the transferability to other elastomers. This is then followed by a brief review of the reaction of the polymer with different solvents in relation to the mixing with particles. In manually kneaded compounds, dispersions ranging from 0.00004 to 0.004 particles per mm3 are common. The process described in this work resulted in agglomerations of no greater than 0.00004 particles per mm3 A possible synthesis route for bisphenol-free boron-siloxanes is then considered, in which for the polymer matrix, polydimethylsilanes (dichloro(methyl)silane), boric acid and iron(III)chloride are used for this purpose by polycondensation.}, language = {en} } @article{RueckertRueckertPalm, author = {R{\"u}ckert, Tobias and R{\"u}ckert, Daniel and Palm, Christoph}, title = {Methods and datasets for segmentation of minimally invasive surgical instruments in endoscopic images and videos: A review of the state of the art}, series = {Computers in Biology and Medicine}, volume = {169}, journal = {Computers in Biology and Medicine}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.compbiomed.2024.107929}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-69830}, pages = {24}, abstract = {In the field of computer- and robot-assisted minimally invasive surgery, enormous progress has been made in recent years based on the recognition of surgical instruments in endoscopic images and videos. In particular, the determination of the position and type of instruments is of great interest. Current work involves both spatial and temporal information, with the idea that predicting the movement of surgical tools over time may improve the quality of the final segmentations. The provision of publicly available datasets has recently encouraged the development of new methods, mainly based on deep learning. In this review, we identify and characterize datasets used for method development and evaluation and quantify their frequency of use in the literature. We further present an overview of the current state of research regarding the segmentation and tracking of minimally invasive surgical instruments in endoscopic images and videos. The paper focuses on methods that work purely visually, without markers of any kind attached to the instruments, considering both single-frame semantic and instance segmentation approaches, as well as those that incorporate temporal information. The publications analyzed were identified through the platforms Google Scholar, Web of Science, and PubMed. The search terms used were "instrument segmentation", "instrument tracking", "surgical tool segmentation", and "surgical tool tracking", resulting in a total of 741 articles published between 01/2015 and 07/2023, of which 123 were included using systematic selection criteria. A discussion of the reviewed literature is provided, highlighting existing shortcomings and emphasizing the available potential for future developments.}, subject = {Deep Learning}, language = {en} } @article{CurrleHaugWeber, author = {Currle, Edda and Haug, Sonja and Weber, Karsten}, title = {Akzeptanz des Einsatzes von K{\"u}nstlicher Intelligenz im Anamneseprozess: Ergebnisse einer Bev{\"o}lkerungsbefragung in Deutschland}, series = {Zeitschrift f{\"u}r Evidenz, Fortbildung und Qualit{\"a}t im Gesundheitswesen}, volume = {198-199}, journal = {Zeitschrift f{\"u}r Evidenz, Fortbildung und Qualit{\"a}t im Gesundheitswesen}, publisher = {Elsevier}, doi = {10.1016/j.zefq.2025.10.003}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-86715}, pages = {9 -- 17}, abstract = {Hintergrund und Zielsetzung Zunehmend werden digitale Anamneseverfahren, wie z. B. Chatbots, entwickelt und evaluiert, sind jedoch in Arztpraxen in Deutschland noch nicht fl{\"a}chendeckend implementiert. Ziel dieser Arbeit ist die Erhebung der Akzeptanz der Bev{\"o}lkerung in Deutschland gegen{\"u}ber KI-gest{\"u}tzten Verfahren im Anamneseprozess, durch die es m{\"o}glich wird, R{\"u}ckschl{\"u}sse auf die Nutzung der Verfahren und ihre Eignung als Bestandteil von Digitalisierungsstrategien der Praxen zu ziehen. Methode Die Studie basiert auf einer Onlinebefragung der Bev{\"o}lkerung in Deutschland (Feldphase 18.-24.11.2024, n = 1.000). Zur{\"u}ckgehend auf die „Unified Theory of Acceptance and Use of Technology" (UTAUT) wurden drei zentrale Hypothesen zur Nutzung von K{\"u}nstlicher Intelligenz (KI) im Anamneseprozess aufgestellt und mit linearen Regressionsmodellen getestet. Ergebnisse Die Akzeptanz f{\"u}r die Nutzung von KI-gest{\"u}tzten Systemen f{\"a}llt in beiden untersuchten Szenarien, der Nutzung eines Chatbots zu Hause und der Nutzung eines Chatbots in einer Arztpraxis, hoch aus. Dabei best{\"a}tigen sich die erwarteten Zusammenh{\"a}nge von Leistungserwartung, Aufwandserwartung und erwartetem Sozialem Einfluss mit der Verhaltensabsicht, einen Chatbot in der Arztpraxis oder vor dem Besuch einer Arztpraxis zu nutzen. Die Einfl{\"u}sse von Alter, Geschlecht oder Erfahrung mit der Technologie zeigen jedoch nicht die vermuteten Zusammenh{\"a}nge. Diskussion und Schlussfolgerung Die Praktikabilit{\"a}t ist von entscheidender Bedeutung f{\"u}r eine positive Einstellung gegen{\"u}ber der Nutzung. Dabei zeigt sich kein Unterschied zwischen den Geschlechtern. Bei der Implementierung von Chatbots im Anamneseprozess sollten die Aspekte Praktikabilit{\"a}t, Datenschutz und Datensicherheit eine wesentliche Rolle spielen. Angesichts der Tatsache, dass ein großer Teil der {\"a}lteren Bev{\"o}lkerung in Deutschland nach wie vor {\"u}ber begrenzte Erfahrung mit digitalen Technologien verf{\"u}gt, ist Gebrauchstauglichkeit f{\"u}r diese Bev{\"o}lkerungsgruppe sowie f{\"u}r Menschen mit Beeintr{\"a}chtigungen von hoher Relevanz.}, language = {de} } @article{HeberlHofrichterRanketal., author = {Heberl, Michael and Hofrichter, Andreas and Rank, Daniel and Bauer, Franz and Sterner, Michael}, title = {Influence of plant dimensioning and location on the ecology of PEM electrolysis}, series = {International Journal of Hydrogen Energy}, volume = {167}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2025.151039}, pages = {11}, abstract = {PV and wind systems with PEM electrolysis offer great potential for producing hydrogen with low emissions. Our research has identified the ecologically optimal size of PEM in relation to fixed PV/wind capacities. We calculate efficiencies and production volumes for PEM with 240 capacity and site variations. We analyse the global warming potential of all systems and draw conclusions about the optimal system design. The lowest GWP is achieved at the site with the highest full load hours with 1.32 kg CO2-eq/kg H2 (Wind, 28 MW electrolysis) and 4.24 kg CO2-eq/kg H2 (PV, 23 MW electrolysis). We have identified a clear trend: increasing PV/wind full load hours leads to higher ideal PEM capacities. However, there is a significant discrepancy between the ideal economic and ecological capacity. Furthermore, higher electrolysis capacities can achieve lower emissions as they increasingly operate at a more efficient partial load.}, language = {en} } @article{BedburKampsSchmiedt, author = {Bedbur, Stefan and Kamps, Udo and Schmiedt, Anja Bettina}, title = {A flexible model of ordered random variables for non-metallic inclusions in steels and related statistical inference}, series = {Applied Mathematical Modelling}, volume = {149}, journal = {Applied Mathematical Modelling}, publisher = {Elsevier}, issn = {0307-904X}, doi = {10.1016/j.apm.2025.116284}, pages = {15}, abstract = {In a data set of non-metallic inclusion sizes in samples from engineering steel, common order statistics fail to serve as a suitable model for ascendingly ordered measurements within single samples. Therefore, a flexible model of ordered random variables is proposed, which allows for changes of distributions described by model parameters. Joint maximum likelihood estimation of these parameters and the shape parameter of an underlying left-truncated Weibull distribution is considered, and a model test is developed for the null-hypothesis of common order statistics being an adequate model. To overcome small data situations, a link-function approach is examined in order to reduce the number of involved model parameters as well as to propose to use a link-function parameter as a material indicator. An asymptotic test is provided to check for the presence of a linear link function, and tests for hypotheses about two link-function parameters are studied. Moreover, the construction of simultaneous confidence regions for the link-function parameters as well as of confidence bands for the entire graph of the link function are presented. Throughout, the findings are applied to the real metallurgical data set. Similar problems and data structures arise in other fields of material science and applications such as geology.}, language = {en} } @article{WolfgrammAbbSampetal., author = {Wolfgramm, Alex and Abb, Valerius and Samp, Artur and Samp, Rafal and Hoffmann, Jens Christoph and M{\"u}ller, Rainer and Kammler, Martin}, title = {Structural and functional evolution of HKUST-1 nanoparticles induced by ball milling}, series = {Next Materials}, volume = {10}, journal = {Next Materials}, publisher = {Elsevier}, doi = {10.1016/j.nxmate.2025.101544}, pages = {7}, abstract = {In this study, the effect of post-synthetic ball milling on the structural and functional properties of as-synthesized nanoparticles of the copper-based metal-organic framework (MOF) HKUST-1 was investigated for the first time. Nanoparticles were synthesized using sodium formate as a capping agent. The crystalline particles were subjected to a controlled ball milling process, which induced significant structural changes. Powder X-ray diffraction (PXRD) revealed a reduction in crystallite size from 91 nm to 21 nm and the introduction of microstrain, partially disrupting the MOF's long-range crystalline order, as evidenced by peak broadening and the diminished intensity of high-angle reflections. Particle morphology pre- and post-milling was further studied with scanning electron microscopy (SEM) imaging, verifying a narrow particle size distribution of ± 22 nm after milling. Fourier-transform infrared spectroscopy (FTIR) indicated protonation of carboxylate groups in the larger pores of the framework, likely due to moisture incorporation during milling. Brunauer-Emmett-Teller (BET) surface area analysis showed a substantial decrease in specific surface area from 521 m²/g to 226 m²/g, suggesting a partial collapse of the porous framework. We discuss the applicability of ball milling as a versatile means of post-synthetic approach to reduce MOF particle sizes, a key element in the preparation of MOF-based thin films using inks or polymers.}, language = {en} } @article{SchummHaasPeeretal., author = {Schumm, Leon and Haas, Jannik and Peer, Rebecca and Sterner, Michael}, title = {The role of hydrogen offtaker regulation in highly renewable electricity systems}, series = {Energy}, volume = {342}, journal = {Energy}, publisher = {Elsevier}, doi = {10.1016/j.energy.2025.139513}, pages = {13}, abstract = {The growing demand for green hydrogen necessitates a rapid scale-up of production and exports to meet decarbonization targets globally. However, current ramp-up efforts remain insufficient, calling for policies that unlock the potential of hydrogen as a low-carbon energy carrier. A key lever is the offtaker regulation, which impacts the pace and sustainability of export projects. This study investigates minimum renewable share requirements for hydrogen exports in countries with high renewable electricity shares. Using New Zealand as a case study, we develop a fully sector-coupled capacity expansion and dispatch model, integrating hydrogen and electricity network planning based on PyPSA-Earth. The model optimizes New Zealand's energy system under varying export scenarios, renewable electricity shares, and resulting system impacts. We find that domestic electricity demand and renewable expansion rates dominate long-term outcomes, while progressive regulation enables short-term hydrogen and Power-to-X exports. Relaxing the renewable threshold from 80\% to 60\% triples export volumes from 2.5 TWh to 8.2 TWh by 2030. We propose a two-stage requirement: an initially progressive threshold to attract investment with low consequential emissions, followed by stricter regulation to prevent high emissions, rising domestic electricity prices, and declining hydrogen competitiveness. This framework, demonstrated for New Zealand, can guide hydrogen-exporting countries worldwide.}, language = {en} } @article{HollweckLeidingerHartmannetal., author = {Hollweck, Christoph and Leidinger, Lukas and Hartmann, Stefan and Wagner, Marcus and W{\"u}chner, Roland}, title = {An analysis of the critical time step size for explicit dynamics using trimmed B-splines, LR-splines, and THB-splines}, series = {Computer Methods in Applied Mechanics and Engineering}, volume = {450}, journal = {Computer Methods in Applied Mechanics and Engineering}, publisher = {Elsevier}, issn = {0045-7825}, doi = {10.1016/j.cma.2025.118656}, pages = {36}, abstract = {Isogeometric analysis (IGA) combined with explicit dynamics is increasingly used in academia and has already been successfully applied in industrial simulations, including crash and sheet-metal forming. Since explicit schemes are only conditionally stable, accurate estimation of the critical time step is essential for both stability and efficiency. Adaptive mesh refinement is widely used to balance accuracy and computational cost. In IGA, THB- and LR-splines break the tensor-product structure of standard B-splines and enable local refinement, but their effect on the critical time step under trimming has not been systematically studied - a key requirement for reliable time step estimation. We investigate the critical time step in explicit dynamic simulations using trimmed B-splines, LR-splines, and THB-splines, based on a lumped mass matrix obtained by simple row summation. One-dimensional bar, two-dimensional membrane, and trimmed shell models are analyzed to determine how trimming and local refinement influence element and system eigenfrequencies, which directly control the stable time step. Refined boundary elements in open knot vectors are identified as the main bottleneck. Trimming these elements can increase the stable time step, though certain trimming configurations introduce new restrictions. Results show that LR- and THB-splines impose time step constraints similar to B-splines, making them equally suitable for explicit simulations. We also present a general method for computing element-wise B{\´e}zier extraction operators for LR- and THB-splines, enabling straightforward integration into standard finite element solvers. The findings are validated through nonlinear sheet-metal forming simulations in LS-DYNA using shells discretized with trimmed B-, LR-, and THB-splines. This represents the first such application and demonstrates their practical feasibility for industrial use.}, language = {en} } @article{RueckertRauberMaerkletal., author = {Rueckert, Tobias and Rauber, David and Maerkl, Raphaela and Klausmann, Leonard and Yildiran, Suemeyye R. and Gutbrod, Max and Nunes, Danilo Weber and Moreno, Alvaro Fernandez and Luengo, Imanol and Stoyanov, Danail and Toussaint, Nicolas and Cho, Enki and Kim, Hyeon Bae and Choo, Oh Sung and Kim, Ka Young and Kim, Seong Tae and Arantes, Gon{\c{c}}alo and Song, Kehan and Zhu, Jianjun and Xiong, Junchen and Lin, Tingyi and Kikuchi, Shunsuke and Matsuzaki, Hiroki and Kouno, Atsushi and Manesco, Jo{\~a}o Renato Ribeiro and Papa, Jo{\~a}o Paulo and Choi, Tae-Min and Jeong, Tae Kyeong and Park, Juyoun and Alabi, Oluwatosin and Wei, Meng and Vercauteren, Tom and Wu, Runzhi and Xu, Mengya and Wang, An and Bai, Long and Ren, Hongliang and Yamlahi, Amine and Hennighausen, Jakob and Maier-Hein, Lena and Kondo, Satoshi and Kasai, Satoshi and Hirasawa, Kousuke and Yang, Shu and Wang, Yihui and Chen, Hao and Rodr{\´i}guez, Santiago and Aparicio, Nicol{\´a}s and Manrique, Leonardo and Palm, Christoph and Wilhelm, Dirk and Feussner, Hubertus and Rueckert, Daniel and Speidel, Stefanie and Nasirihaghighi, Sahar and Al Khalil, Yasmina and Li, Yiping and Arbel{\´a}ez, Pablo and Ayobi, Nicol{\´a}s and Hosie, Olivia and Lyons, Juan Camilo}, title = {Comparative validation of surgical phase recognition, instrument keypoint estimation, and instrument instance segmentation in endoscopy: Results of the PhaKIR 2024 challenge}, series = {Medical Image Analysis}, volume = {109}, journal = {Medical Image Analysis}, publisher = {Elsevier}, issn = {1361-8415}, doi = {10.1016/j.media.2026.103945}, pages = {31}, abstract = {Reliable recognition and localization of surgical instruments in endoscopic video recordings are foundational for a wide range of applications in computer- and robot-assisted minimally invasive surgery (RAMIS), including surgical training, skill assessment, and autonomous assistance. However, robust performance under real-world conditions remains a significant challenge. Incorporating surgical context - such as the current procedural phase - has emerged as a promising strategy to improve robustness and interpretability. To address these challenges, we organized the Surgical Procedure Phase, Keypoint, and Instrument Recognition (PhaKIR) sub-challenge as part of the Endoscopic Vision (EndoVis) challenge at MICCAI 2024. We introduced a novel, multi-center dataset comprising thirteen full-length laparoscopic cholecystectomy videos collected from three distinct medical institutions, with unified annotations for three interrelated tasks: surgical phase recognition, instrument keypoint estimation, and instrument instance segmentation. Unlike existing datasets, ours enables joint investigation of instrument localization and procedural context within the same data while supporting the integration of temporal information across entire procedures. We report results and findings in accordance with the BIAS guidelines for biomedical image analysis challenges. The PhaKIR sub-challenge advances the field by providing a unique benchmark for developing temporally aware, context-driven methods in RAMIS and offers a high-quality resource to support future research in surgical scene understanding.}, language = {en} } @article{WeindlerLehnerEcksteinetal., author = {Weindler, Jeremy and Lehner, Hannes and Eckstein, J. and Dawoud, Belal}, title = {Performance assessment of a green hydrogen-based household energy system supported by a battery storage at different resolutions of the electrical load profile}, series = {International Journal of Hydrogen Energy}, volume = {144}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2025.04.431}, pages = {30 -- 41}, abstract = {Hydrogen deems quite suitable for medium- and long-term energy storage of surplus renewable electricity. Nowadays, all-in-one solutions consisting of an electrolyzer, a compressor, pressurized hydrogen storage tanks, a fuel cell (FC) and the necessary peripheral components are available for single family houses. This work presents a comparative assessment of the system's key performance indicators in a household system with three market available FCs with the nominal powers of 0.8, 1.4 and 7.8 kW. The design tool developed for the assessment of the hybrid energy system along with two energy management system configurations are introduced. An electrochemical and thermal model widely applied in the literature is used to model the FCs, which is validated against the available experimental data in the literature for all three FCs. The influence of the FCs' nominal power, their power dynamic operation range, the use of a battery storage with different capacities and the load profile's resolution have been technically assessed regarding the system's self-sufficiency (SS), the FC's efficiency, full-load operating hours, and number of on/off cycles. It turned out that, the system performance is strongly dependent on the nominal power of the FC and its power dynamic operation range. If no battery-storage is applied, the complete grid independence is not possible, and a high resolution of the load profile is indispensable in the assessment of the system design. A hybrid energy system comprising the 1.4 kW FC, a PV system of 10 kW peak power and a battery of 15 kW storage capacity showed a degree of SS of 98\%. The number of the full-load operating hours and on/off cycles of that FC amount to 768 and 116 cycles, respectively. Such promising results are referred to the high dynamic operation range of the battery, and its high discharge power capacity, which makes it more suitable to cover a remarkably higher fraction of the load deficit, if compared to a system without a battery.}, language = {en} } @article{WeindlerDawoud, author = {Weindler, Jeremy and Dawoud, Belal}, title = {Experimental investigation of a small-scale continuous flow ohmic heating reactor for a highly effective conversion of renewable electricity surpluses into heat}, series = {Applied Thermal Engineering}, volume = {242}, journal = {Applied Thermal Engineering}, publisher = {Elsevier}, issn = {1359-4311}, doi = {10.1016/j.applthermaleng.2024.122401}, pages = {15}, abstract = {Sector coupling is expected to play a decisive role as a key technology to realize the energy transition towards green energy supply. This work introduces, therefore, a comprehensive experimental study on a new power-to-heat system based on the continuous-flow, ohmic heating principle, which aims at utilizing renewable electricity in green processes. The ohmic heating technology, which is widely applied in the food industry, has been adapted and evaluated for delivering heat and domestic hot water to a single-family house. The introduced prototype is designed to convert renewable electricity into heat in the power range between 1000 and 3000 W with a typical electrical household installation (230 V, 50 Hz and 16 A fuse). A dedicated test rig has been developed and a comprehensive experimental campaign has been carried out to investigate the performance of the introduced system under typical operating conditions of a single-family house. Both the conversion efficiency and the dynamics of the thermal response of the introduced system have been assessed. It turned out that, the temperature lift between the return and supply of the reactor, and consequently, the conversion efficiency of electrical into thermal energy, are independent on the return temperature, for a fixed value of the volume flow rate of the electrolyte solution. A remarkable steady-state conversion efficiency of 97.5\% has been measured. In addition, the dynamic response of the ohmic heating system has been found to be strongly dependent on the desired temperature lift. By an implemented controller, 95\% of the steady state temperature lift of 44.5 K can be realized in 50 s, which marks an exceptionally rapid thermal response. The obtained results pave the way towards a field test study of the developed technology in a real household installation as well as to extend the focus on new fields such as green chemical processes.}, language = {en} } @article{SittlMarburgDeckersetal., author = {Sittl, Christopher and Marburg, Steffen and Deckers, Elke and Wagner, Marcus}, title = {Model order reduction for unbounded second-order vibroacoustic systems using infinite elements and Dirichlet-to-Neumann map}, series = {Computer Methods in Applied Mechanics and Engineering}, volume = {453}, journal = {Computer Methods in Applied Mechanics and Engineering}, publisher = {Elsevier}, doi = {10.1016/j.cma.2026.118846}, pages = {22}, abstract = {This work addresses the efficient numerical simulation of time-harmonic vibroacoustic problems in unbounded domains, with a focus on fluid-structure interaction. The underlying mathematical model is a second-order dynamical system arising from the coupling of structural and acoustic domains, incorporating material damping effects, relevant in structural acoustics and noise control applications. A central novelty of the proposed method is its unified computational framework that supports two distinct strategies for treating unbounded fluid domains: (1) non-local absorbing boundary conditions based on Dirichlet-to-Neumann map, and (2) infinite elements, which extend the computational domain rather than truncate it. Both approaches are integrated into a consistent formulation that enables flexible and accurate modeling of exterior wave propagation. To efficiently evaluate frequency-domain transfer functions, the method employs model order reduction using the Pad{\´e}-via-Lanczos technique. While this algorithm typically targets first-order systems, the present approach uses a Schur complement strategy to reduce the second-order system in a way that maintains computational efficiency and storage requirements comparable to first-order formulations. Importantly, the framework seamlessly embeds both interior structural damping and the additional dissipation introduced by the acoustic-domain truncation into the model-order reduction process. The exterior acoustic field is represented via spherical harmonic expansions, with expansion coefficients computed from the reduced system. Numerical results demonstrate the method's accuracy, efficiency, and scalability, making it well-suited for high-fidelity vibroacoustic analysis in unbounded domains.}, language = {en} }