TY - JOUR AB - Due to the hydrolytic instability of LiPF6 in carbonate-based solvents, HF is a typical impurity in Li-ion battery electrolytes. HF significantly influences the performance of Li-ion batteries, for example by impacting the formation of the solid electrolyte interphase at the anode and by affecting transition metal dissolution at the cathode. Additionally, HF complicates studying fundamental interfacial electrochemistry of Li-ion battery electrolytes, such as direct anion reduction, because it is electrocatalytically relatively unstable, resulting in LiF passivation layers. Methods to selectively remove ppm levels of HF from LiPF6-containing carbonate-based electrolytes are limited. We introduce and benchmark a simple yet efficient electrochemical in situ method to selectively remove ppm amounts of HF from LiPF6-containing carbonate-based electrolytes. The basic idea is the application of a suitable potential to a high surface-area metallic electrode upon which only HF reacts (electrocatalytically) while all other electrolyte components are unaffected under the respective conditions. AU - Ge, Xiaokun AU - Huck, Marten AU - Kuhlmann, Andreas AU - Tiemann, Michael AU - Weinberger, Christian AU - Xu, Xiaodan AU - Zhao, Zhenyu AU - Steinrueck, Hans-Georg ID - 52372 JF - Journal of The Electrochemical Society KW - Materials Chemistry KW - Electrochemistry KW - Surfaces KW - Coatings and Films KW - Condensed Matter Physics KW - Renewable Energy KW - Sustainability and the Environment KW - Electronic KW - Optical and Magnetic Materials SN - 0013-4651 TI - Electrochemical Removal of HF from Carbonate-based LiPF6-containing Li-ion Battery Electrolytes VL - 171 ER - TY - JOUR AU - Boeddeker, Christoph AU - Subramanian, Aswin Shanmugam AU - Wichern, Gordon AU - Haeb-Umbach, Reinhold AU - Le Roux, Jonathan ID - 52958 JF - IEEE/ACM Transactions on Audio, Speech, and Language Processing KW - Electrical and Electronic Engineering KW - Acoustics and Ultrasonics KW - Computer Science (miscellaneous) KW - Computational Mathematics SN - 2329-9290 TI - TS-SEP: Joint Diarization and Separation Conditioned on Estimated Speaker Embeddings VL - 32 ER - TY - GEN AU - Banh, Ngoc Chi AU - Scharlau, Ingrid ID - 53069 TI - Effects of task difficulty on visual processing speed ER - TY - JOUR AB - In this work, we consider optimal control problems for mechanical systems with fixed initial and free final state and a quadratic Lagrange term. Specifically, the dynamics is described by a second order ODE containing an affine control term. Classically, Pontryagin's maximum principle gives necessary optimality conditions for the optimal control problem. For smooth problems, alternatively, a variational approach based on an augmented objective can be followed. Here, we propose a new Lagrangian approach leading to equivalent necessary optimality conditions in the form of Euler-Lagrange equations. Thus, the differential geometric structure (similar to classical Lagrangian dynamics) can be exploited in the framework of optimal control problems. In particular, the formulation enables the symplectic discretisation of the optimal control problem via variational integrators in a straightforward way. AU - Leyendecker, Sigrid AU - Maslovskaya, Sofya AU - Ober-Blöbaum, Sina AU - Almagro, Rodrigo T. Sato Martín de AU - Szemenyei, Flóra Orsolya ID - 53101 JF - Journal of Computational Dynamics KW - Optimal control problem KW - Lagrangian system KW - Hamiltonian system KW - Variations KW - Pontryagin's maximum principle. SN - 2158-2491 TI - A new Lagrangian approach to control affine systems with a quadratic Lagrange term ER - TY - BOOK AB - Tax evasion, tax avoidance and tax resistance are widespread phenomena in political, economic, social and fiscal history from antiquity through medieval, early modern and modern times. Histories of Tax Evasion, Avoidance and Resistance shows how different groups and individuals around the globe have succeeded or failed in not paying their due taxes, whether in kind or in cash, on their properties or on their crops. It analyses how, throughout history, wealthy and poor taxpayers have tried to avoid or reduce their tax burden by negotiating with tax authorities, through practices of legal or illegal tax evasion, by filing lawsuits, seeking armed resistance or by migration, and how state authorities have dealt with such acts of claim making, defiance, open resistance or elusion. It fills an important research gap in tax history, addressing questions of tax morale and fairness, and how social and political inequality was negotiated through taxation. It gives rich insights into the development of citizen-state relationships throughout the course of history. The book comprises case studies from Ancient Athens, Roman Egypt, Medieval Europe, Early Modern Mexico, the Ottoman Empire, Nigeria under British colonial rule, the United Kingdom of the early 20th century, Greece during the Second World War, as well as West Germany, Switzerland, Sweden and the United States in the 20th century, including transnational entanglements in the world of late-modern offshore finance and taxation. The authors are experts in fiscal, economic, financial, legal, social and/or cultural history. The book is intended for students, researchers and scholars of economic and financial history, social and world history and political economy. The Open Access version of this book, available at www.taylorfrancis.com, has been made available under a Creative Commons Attribution-Share Alike 4.0 license. AU - Schönhärl, Korinna AU - Hürlimann, Gisela AU - Rohde, Dorothea ID - 34544 KW - Tax History KW - Financial History SN - 9781003333197 TI - Histories of Tax Evasion, Avoidance and Resistance ER - TY - CHAP AB - Jean Bodin's list on how the absolutist monarchical state could raise its revenue ranked taxation only in seventh place. From a modern legal perspective, taxes are compulsory transfers of resources that households and enterprises pay to one or several government bodies without receiving an individual, specific benefit in return. Historians have dealt with not paying taxes in various contexts, such as analysing tax resistance and tax resistance movements in history. Tax law is best understood as an outcome of long-term, often conflictual, negotiations and as an expression of specific political mentalities and ideologies. As a consequence, tax law and sometimes even the tax juridical system have a strongly politicised character. Loopholes in tax legislation that enable or facilitate avoidance or evasion can thus be regarded as a result of the interest-driven politics of parliamentary majorities, as the success of concerted lobby pressure. AU - Schönhärl, Korinna AU - Hürlimann, Gisela AU - Rohde, Dorothea ED - Schönhärl, Korinna ED - Hürlimann, Gisela ED - Rohde, Dorothea ID - 34546 T2 - Histories of Tax Evasion, Avoidance and Resistance TI - The Ability and Intention of Not Paying Taxes in History. Some Introductory Observations ER - TY - CHAP AB - As a case study, this chapter examines two tax education films that were produced 11 years apart in the USA and Western Germany during and after World War II: “The New Spirit” and “Putzke wants to know”. In contrast to America's most popular cartoon character 11 years earlier, Erwin Putzke is in a terrible mood at the beginning of the short film “Putzke wants to know”. The family father and electrician with a workshop of his own is annoyed and upset by the duty of filling in his tax return, grumbling at his wife and daughter and even at their budgie. The film's tax morale message is conveyed to its audience against the backdrop of a sober post-war reality characterised by allied occupation and the Allies' say in West German tax policies during a period of laborious economic build-up after a lost war. AU - Schönhärl, Korinna ED - Schönhärl, Korinna ED - Hürlimann, Gisela ED - Rohde, Dorothea ID - 34547 T2 - Histories of Tax Evasion, Avoidance and Resistance TI - How to Create a Taxpaying Spirit. A Transnational Examination of an US American and a Western German Tax Education Film in and after World War II ER - TY - JOUR AB - As in almost every other branch of science, the major advances in data science and machine learning have also resulted in significant improvements regarding the modeling and simulation of nonlinear dynamical systems. It is nowadays possible to make accurate medium to long-term predictions of highly complex systems such as the weather, the dynamics within a nuclear fusion reactor, of disease models or the stock market in a very efficient manner. In many cases, predictive methods are advertised to ultimately be useful for control, as the control of high-dimensional nonlinear systems is an engineering grand challenge with huge potential in areas such as clean and efficient energy production, or the development of advanced medical devices. However, the question of how to use a predictive model for control is often left unanswered due to the associated challenges, namely a significantly higher system complexity, the requirement of much larger data sets and an increased and often problem-specific modeling effort. To solve these issues, we present a universal framework (which we call QuaSiModO: Quantization-Simulation-Modeling-Optimization) to transform arbitrary predictive models into control systems and use them for feedback control. The advantages of our approach are a linear increase in data requirements with respect to the control dimension, performance guarantees that rely exclusively on the accuracy of the predictive model, and only little prior knowledge requirements in control theory to solve complex control problems. In particular the latter point is of key importance to enable a large number of researchers and practitioners to exploit the ever increasing capabilities of predictive models for control in a straight-forward and systematic fashion. AU - Peitz, Sebastian AU - Bieker, Katharina ID - 21199 JF - Automatica TI - On the Universal Transformation of Data-Driven Models to Control Systems VL - 149 ER - TY - JOUR AB - Videografien eigenen Unterrichts sind ein mögliches methodisches Werkzeug zur Förderung der professionellen Kompetenz angehender Lehrkräfte, das allerdings innerhalb der Lehramtsausbildung noch nicht breit implementiert ist. Ein möglicher Grund hierfür könnte neben organisatorischen Herausforderungen auch in einer geringen Akzeptanz von Eigenvideografien durch Lehramtsstudierende liegen. Um besser abschätzen zu können, mit welchen Voraussetzungen affektiv-emotionaler Art bei einer breiteren Implementierung im Lehramtsstudium gerechnet werden kann, wurden N = 938 Lehramtsstudierende im Masterstudium an der Universität Paderborn zu ihren Emotionen und Bereitschaften zur Arbeit mit Eigenvideografien befragt. Dabei wurde auch erfasst, wie sich diese je nach bestehenden Erfahrungen zur Arbeit mit Videografien unterscheiden. In den Ergebnissen zeigen sich kaum affektiv-emotionale Reaktionen zur Eigenvideografie, und wenn, vor allem Gefühle der Unsicherheit. Zu beachten ist, dass zwar bei gut der Hälfte der Studierenden eine eher hohe generelle Bereitschaft zur Eigenvideografie besteht, eine konkrete Intention bzw. eine konkrete Volition zur Videografie aber geringer ist. Die ca. 10 % der Studierenden mit Eigenvideografieerfahrung im Studium zeigen erwartungsgemäß höhere Bereitschaften, aber unerwartet keine signifikant positiveren Emotionen. Insgesamt verdeutlichen die Ergebnisse, dass bzgl. der Akzeptanz der Studierenden ein höheres Potenzial zur Implementation von Eigenvideografien im Studium vorliegt, als aktuell ausgeschöpft wird. AU - Vogelsang, Christoph AU - Pollmeier, Pascal AU - Gockeln, Theresa AU - Rogge, Tim ID - 35831 JF - Zeitschrift für Bildungsforschung KW - Lehrerbildung KW - Videografie KW - Praxissemester KW - Emotionen KW - Akzeptanz TI - Zu unangenehm, zu viel Aufwand oder keine Möglichkeit? – Emotionen und Bereitschaft von Lehramtsstudierenden zur Videografie eigenen Unterrichts ER - TY - JOUR AB - Abstract. The miniaturisation of components leads to new demands on measurement systems. One of these is the resolution. As a volumetric analysis method and method of non-destructive testing, industrial X-ray computed tomography (XCT) has the ability to measure geometrical features and their corresponding dimensions without destroying them and can therefore be used for quality assurance. However, the concept of resolution is not trivial for XCT and has not yet been finally clarified. In particular, the interface structural resolution, the detectability of two surfaces facing each other after surface segmentation, faces a lack of a test specimen, a corresponding measurand and a reliable method. Simulation-based XCT investigations of a method to determine this type of resolution are presented in this article using the geometry of a test specimen that contains several radially arranged holes of the same size. The borehole diameters correspond to the distance between the holes to investigate the resolvability of surfaces and interfaces. The evaluation is based on mean and extreme values of grey value profiles between the individual boreholes of the reconstructed volume. It is shown that the geometrical detectability of the test specimen surface and interface can be extended by a reasonable choice of the threshold value for surface segmentation within a defined interval. With regard to the resolving capability, a distinction is made between assured detectability and possible detectability, as well as the threshold value used when using the ISO50 threshold for surface segmentation and measurement chain completion. AU - Busch, Matthias AU - Hausotte, Tino ID - 36800 IS - 1 JF - Journal of Sensors and Sensor Systems KW - Electrical and Electronic Engineering KW - Instrumentation SN - 2194-878X TI - Simulation-based investigation of the metrological interface structural resolution capability of X-ray computed tomography scanners VL - 12 ER - TY - CONF AU - Richter, Cedric AU - Haltermann, Jan Frederik AU - Jakobs, Marie-Christine AU - Pauck, Felix AU - Schott, Stefan AU - Wehrheim, Heike ID - 35426 T2 - 37th IEEE/ACM International Conference on Automated Software Engineering TI - Are Neural Bug Detectors Comparable to Software Developers on Variable Misuse Bugs? ER - TY - CONF AU - Pauck, Felix ID - 35427 T2 - 37th IEEE/ACM International Conference on Automated Software Engineering TI - Scaling Arbitrary Android App Analyses ER - TY - JOUR AB - Chemical phenomena are only observable on a macroscopic level, whereas they are explained by entities on a non-visible level. Students often demonstrate limited ability to link these different levels. Augmented reality (AR) offers the possibility to increase contiguity by embedding virtual models into hands-on experiments. Therefore, this paper presents a pre- and post-test study investigating how learning and cognitive load are influenced by AR during hands-on experiments. Three comparison groups (AR, animation and filmstrip), with a total of N = 104 German secondary school students, conducted and explained two hands-on experiments. Whereas the AR group was allowed to use an AR app showing virtual models of the processes on the submicroscopic level during the experiments, the two other groups were provided with the same dynamic or static models after experimenting. Results indicate no significant learning gain for the AR group in contrast to the two other groups. The perceived intrinsic cognitive load was higher for the AR group in both experiments as well as the extraneous load in the second experiment. It can be concluded that AR could not unleash its theoretically derived potential in the present study. AU - Peeters, Hendrik AU - Habig, Sebastian AU - Fechner, Sabine ID - 37613 IS - 2 JF - Multimodal Technologies and Interaction KW - augmented reality KW - chemistry education KW - models KW - experiment KW - cognitive load SN - 2414-4088 TI - Does Augmented Reality Help to Understand Chemical Phenomena during Hands-On Experiments?–Implications for Cognitive Load and Learning VL - 7 ER - TY - THES AB - Für den Erwerb fachmethodischer Fähigkeiten stellen Laborpraktika eine zentrale Lerngelegenheiten des Physikstudiums dar. Trotz ihrer hohen Bedeutung fehlt ein hochschulfachdidaktischer Diskurs zu einer lehr-lerntheoretischen Fundierung. Zudem wird ihre Lernwirksamkeit aufgrund der bestehenden didaktischen Gestaltung kritisiert. Die weit verbreiteten engmaschigen Aufgabenstellungen enthalten keine Anreize zur tiefergehenden Auseinandersetzung mit den Inhalten. Um der Diskrepanz zwischen den Zielsetzungen und den von den Lernenden erworbenen Fähigkeiten entgegenzuwirken, liegen aktuell nur wenige und zudem nur punktuelle Grundlagen für eine evidenzbasierte Überarbeitung dieses Veranstaltungsformates vor. Ziel dieser Arbeit ist daher, einen Vorschlag für ein performanzorientiertes Kompetenzstrukturmodell auf universitärem Niveau zu entwickeln, das die Inhaltsbereiche, die experimentellen Fähigkeiten und Fertigkeiten sowie die Qualitätsausprägungen experimenteller Handlungen systematisiert.Die Modellierung ist auf Basis der Analyse videografierter experimenteller Performanz von 16 unterschiedlich fähigen Proband:innen realisiert worden. Für die Entwicklung der Dimensionen Fachmethodik und Qualitätsausprägung werden unter Nutzung der qualitativen Forschungsansätze Dokumentarische Methode und Typenbildung die charakteristischen Merkmale universitären Experimentierens identifiziert und anschließend systematisiert. Zur Prüfung der Passung des Modells zur Perspektive der Wissenschaft Physik ist ein Interrating mit einem Fachwissenschaftler durchgeführt worden, das sehr gute Übereinstimmungswerte liefert. Die Passung des Modells zur Perspektive der Praktikumsleiter:innen ist durch ein Expertenrating erfolgt. Ein Rangfolgen-Vergleich zeigt hohe Übereinstimmungswerte. AU - Bauer, Anna Brigitte ID - 37645 TI - Experimentelle Kompetenz Physikstudierender ER - TY - GEN AB - We consider the data-driven approximation of the Koopman operator for stochastic differential equations on reproducing kernel Hilbert spaces (RKHS). Our focus is on the estimation error if the data are collected from long-term ergodic simulations. We derive both an exact expression for the variance of the kernel cross-covariance operator, measured in the Hilbert-Schmidt norm, and probabilistic bounds for the finite-data estimation error. Moreover, we derive a bound on the prediction error of observables in the RKHS using a finite Mercer series expansion. Further, assuming Koopman-invariance of the RKHS, we provide bounds on the full approximation error. Numerical experiments using the Ornstein-Uhlenbeck process illustrate our results. AU - Philipp, Friedrich AU - Schaller, Manuel AU - Worthmann, Karl AU - Peitz, Sebastian AU - Nüske, Feliks ID - 38031 T2 - arXiv:2301.08637 TI - Error bounds for kernel-based approximations of the Koopman operator ER - TY - CONF AB - Jupyter notebooks enable developers to interleave code snippets with rich-text and in-line visualizations. Data scientists use Jupyter notebook as the de-facto standard for creating and sharing machine-learning based solutions, primarily written in Python. Recent studies have demonstrated, however, that a large portion of Jupyter notebooks available on public platforms are undocumented and lacks a narrative structure. This reduces the readability of these notebooks. To address this shortcoming, this paper presents HeaderGen, a novel tool-based approach that automatically annotates code cells with categorical markdown headers based on a taxonomy of machine-learning operations, and classifies and displays function calls according to this taxonomy. For this functionality to be realized, HeaderGen enhances an existing call graph analysis in PyCG. To improve precision, HeaderGen extends PyCG's analysis with support for handling external library code and flow-sensitivity. The former is realized by facilitating the resolution of function return-types. Furthermore, HeaderGen uses type information to perform pattern matching on code syntax to annotate code cells. The evaluation on 15 real-world Jupyter notebooks from Kaggle shows that HeaderGen's underlying call graph analysis yields high accuracy (96.4% precision and 95.9% recall). This is because HeaderGen can resolve return-types of external libraries where existing type inference tools such as pytype (by Google), pyright (by Microsoft), and Jedi fall short. The header generation has a precision of 82.2% and a recall rate of 96.8% with regard to headers created manually by experts. In a user study, HeaderGen helps participants finish comprehension and navigation tasks faster. All participants clearly perceive HeaderGen as useful to their task. AU - Shivarpatna Venkatesh, Ashwin Prasad AU - Wang, Jiawei AU - Li, Li AU - Bodden, Eric ID - 36522 KW - static analysis KW - python KW - code comprehension KW - annotation KW - literate programming KW - jupyter notebook TI - Enhancing Comprehension and Navigation in Jupyter Notebooks with Static Analysis ER - TY - JOUR AU - Pfeiffer, Jella AU - Gutschow, Julia AU - Haas, Christian AU - Möslein, Florian AU - Maspfuhl, Oliver AU - Borgers, Frederik AU - Alpsancar, Suzana ID - 41874 JF - Business & Information Systems Engineering KW - Information Systems SN - 2363-7005 TI - Algorithmic Fairness in AI ER - TY - GEN AU - Süßmann, Johannes ID - 41948 T2 - wissen/leben. Die Zeitung der WWU Münster TI - Zu »wahrer Glückseligkeit« anleiten. WWU-Gründervater Franz von Fürstenberg wollte vor allem den Fortbestand des Landes sichern – ein Gastbeitrag VL - 17/1 ER - TY - JOUR AU - Matthias Philipper ID - 42154 JF - Quick And Easy Journal Title TI - New Quick And Easy Publication - Will be edited by LibreCat team ER - TY - GEN AB - The goal of this paper is to make a strong point for the usage of dynamical models when using reinforcement learning (RL) for feedback control of dynamical systems governed by partial differential equations (PDEs). To breach the gap between the immense promises we see in RL and the applicability in complex engineering systems, the main challenges are the massive requirements in terms of the training data, as well as the lack of performance guarantees. We present a solution for the first issue using a data-driven surrogate model in the form of a convolutional LSTM with actuation. We demonstrate that learning an actuated model in parallel to training the RL agent significantly reduces the total amount of required data sampled from the real system. Furthermore, we show that iteratively updating the model is of major importance to avoid biases in the RL training. Detailed ablation studies reveal the most important ingredients of the modeling process. We use the chaotic Kuramoto-Sivashinsky equation do demonstarte our findings. AU - Werner, Stefan AU - Peitz, Sebastian ID - 42160 T2 - arXiv:2302.07160 TI - Learning a model is paramount for sample efficiency in reinforcement learning control of PDEs ER - TY - JOUR AB - Regularization is used in many different areas of optimization when solutions are sought which not only minimize a given function, but also possess a certain degree of regularity. Popular applications are image denoising, sparse regression and machine learning. Since the choice of the regularization parameter is crucial but often difficult, path-following methods are used to approximate the entire regularization path, i.e., the set of all possible solutions for all regularization parameters. Due to their nature, the development of these methods requires structural results about the regularization path. The goal of this article is to derive these results for the case of a smooth objective function which is penalized by a piecewise differentiable regularization term. We do this by treating regularization as a multiobjective optimization problem. Our results suggest that even in this general case, the regularization path is piecewise smooth. Moreover, our theory allows for a classification of the nonsmooth features that occur in between smooth parts. This is demonstrated in two applications, namely support-vector machines and exact penalty methods. AU - Gebken, Bennet AU - Bieker, Katharina AU - Peitz, Sebastian ID - 27426 IS - 3 JF - Journal of Global Optimization TI - On the structure of regularization paths for piecewise differentiable regularization terms VL - 85 ER - TY - JOUR AU - Alhaddad, Samer AU - Förstner, Jens AU - Grynko, Yevgen ID - 43018 JF - Journal of Quantitative Spectroscopy and Radiative Transfer KW - tet_topic_scattering SN - 0022-4073 TI - Numerical study of light backscattering from layers of absorbing irregular particles larger than the wavelength VL - 302 ER - TY - CONF AU - Hoffmann, Max AU - Biehler, Rolf ED - Trigueros, Marı́a ED - Barquero, Berta ED - Hochmuth, Reinhard ED - Peters, Jana ID - 31849 KW - Teaching and learning of specific topics in university mathematics KW - Transition to KW - across and from university mathematics KW - Student Teachers KW - Geometry KW - Congruence KW - Double Discontinuity. T2 - Proceedings of the Fourth Conference of the International Network for Didactic Research in University Mathematics (INDRUM 2022, 19-22 October 2022) TI - Student Teachers ’ Knowledge of Congruence before a University Course on Geometry ER - TY - CONF AU - Florensa, Ignasio AU - Hoffmann, Max AU - Romo Vázquez, Avenilde AU - Zandieh, Michelle AU - Martínez-Planell, Rafael ED - Trigueros, Marı́a ED - Barquero, Berta ED - Hochmuth, Reinhard ED - Peters, Jana ID - 43097 T2 - Proceedings of the Fourth Conference of the International Network for Didactic Research in University Mathematics (INDRUM 2022, 19-22 October 2022) TI - Innovations in university teaching based on mathematic education research ER - TY - GEN AU - Süßmann, Johannes ID - 43186 TI - Pantheon ER - TY - JOUR AB - Lightweight design is a common approach to reduce energy demand in the use stage of vehicles. The production of lightweight materials is usually associated with an increase in energy demand, so the environmental impacts of lightweight structures need to be assessed holistically using a life cycle assessment. To estimate the life cycle environmental impacts of a product in its developmental stage, for example, by life cycle engineering, future changes in relevant influencing factors must be considered. Prospective life cycle assessment provides methods for integrating future scenarios into life cycle assessment studies. However, approaches for integrating prospective life cycle assessment into product development are limited. The objective of this work is to provide the methodological foundation for integrating future scenarios of relevant influencing factors in the development of lightweight structures. The applicability of the novel methodology is demonstrated by a case study of a structural component in a steel, aluminium, and hybrid design. The results show that appropriate decarbonisation measures can reduce the life cycle greenhouse gas emissions by up to 95 percent until 2050. We also found that shifts in the environmentally optimal design are possible in future scenarios. Therefore, the methodology and data provided contribute to improved decision-making in product development. AU - Ostermann, Moritz AU - Grenz, Julian AU - Triebus, Marcel AU - Cerdas, Felipe AU - Marten, Thorsten AU - Tröster, Thomas AU - Herrmann, Christoph ID - 43464 IS - 8 JF - Energies KW - Life Cycle Engineering KW - Life Cycle Assessment KW - Lightweight Design KW - Prospective LCA KW - Future-oriented LCA KW - Energy System KW - Material production KW - Sustainable production SN - 1996-1073 TI - Integrating Prospective Scenarios in Life Cycle Engineering: Case Study of Lightweight Structures VL - 16 ER - TY - JOUR AB - A relatively small body of research has been conducted on the near- and long-term effects of study abroad (SA) to date. This existing research suggests that SA effects on language skills tend to be volatile, while the impact on various aspects of learners’ personal, academic, and professional development may be longer-lasting. Yet, learner perspectives on the dynamics and durability of such effects, in particular in the context of short-term SA programs, remain largely unexplored. This study hence investigates the near-term impact of short-term SA programs as experienced by students within the first months and years following their sojourns. A qualitative case-study design is employed to examine the accounts of four American students of German, who studied abroad in Austria for four weeks and were interviewed repeatedly over a period of up to 40 months after their sojourns. The results suggest that, from the students’ perspective, many effects deteriorate in the near term, although the overall sojourn experience still appears influential. Abstract in German Nur wenige Forschungsvorhaben haben sich bislang den mittel- bis langfristigen Auswirkungen studentischer Auslandsaufenthalte gewidmet; die bisherige Datenlage deutet jedoch darauf hin, dass die Auswirkungen auf sprachliche Kompetenzen eher unbeständig sind, wohingegen die persönliche, studiums- und berufsbezogene Entwicklung der Lernenden länger von einem Auslandsaufenthalt beeinflusst wird. Die Dynamik und Beständigkeit derartiger Auswirkungen wurden jedoch kaum mit Blick auf kurze Auslandsaufenthalte (≤ acht Wochen) sowie aus der Perspektive der Studierenden erforscht, was die vorliegende Studie insbesondere hinsichtlich mittelfristiger Effekte fokussiert. Mittels eines qualitativen Fallstudiendesigns werden die Interviewdaten vier amerikanischer Deutschlernender untersucht, die sich vier Wochen in Österreich aufhielten und in einem Zeitraum von bis zu 40 Monaten nach ihrem Aufenthalt wiederholt befragt wurden. Die Ergebnisse zeigen, dass viele Auswirkungen eines solchen Aufenthalts aus studentischer Perspektive mittelfristig verblassen, auch wenn der Auslandsaufenthalt im Gesamten weiterhin als einflussreiche Erfahrung wahrgenommen wird. AU - Müller, Mareike ID - 44058 IS - 1 JF - Frontiers: The Interdisciplinary Journal of Study Abroad SN - 2380-8144 TI - Near-Term Effects of Short-Term Study Abroad: A Longitudinal Examination of Learner Perceptions VL - 35 ER - TY - JOUR AB - Die Wirtschaftlichkeit von Wärmemotoren wird maßgeblich durch die Rückführung von Wärme in Rekuperatoren beeinflusst. Beim isobaren Expansionsmotor vom Bush-Typ, einem Wärmemotor, welcher bereits mit Wärmequellen ab 60°C betrieben werden kann, steigt der thermische Wirkungsgrad durch den Einsatz von Rekuperatoren signifikant. Gleichzeitig wirken sich das Fluidvolumen des Wärmeübertragers sowie der beim Betrieb auftretende Druckverlust negativ auf den thermischen Wirkungsrad aus. In dieser Arbeit wird der Zusammenhang von Totvolumen, Druckverlust und Wärmerückgewinnung untersucht und Empfehlungen für den Betrieb von Rekuperatoren am isobaren Expansionsmotor gegeben. AU - Mügge, Nils AU - Kronberg, Alexander AU - Glushenkov, Maxim AU - Kenig, Eugeny Y. ID - 42252 IS - 5 JF - Chemie Ingenieur Technik KW - Isobarer Expansionsmotor KW - Dynamische Wärmeübertragungsmodellierung KW - Phasenwechsel KW - dichte Arbeitsmedien TI - Untersuchung überlagerter Effekte von Druckverlust und Totvolumen durch Rekuperation am isobaren Expansionsmotor VL - 95 ER - TY - JOUR AB - AbstractThe use of structured measuring systems to prevent wall slip is a common approach to obtain absolute rheological values. Typically, only the minimum distance between the measuring surfaces is used for further calculation, implying that no flow occurs between the structural elements. But this assumption is misleading, and a gap correction is necessary. To determine the radius correction $$\Delta r$$ Δ r for specific geometries, we conducted investigations on three Newtonian fluids (two silicon oils and one suspension considered to be Newtonian in the relevant shear rate range). The results show that $$\Delta r$$ Δ r is not only shear- and material-independent, but geometry-dependent, providing a Newtonian flow behaviour in a similar viscosity range. Therefore, a correction value can be determined with only minute deviations in different Newtonian fluids. As the conducted laboratory measurements are very time-consuming and expensive, a CFD-approach with only very small deviations was additionally developed and compared for validation purposes. Therefore, simulation is an effective and resource-efficient alternative to the presented laboratory measurements to determine $$\Delta r$$ Δ r for the correction of structured coaxial geometries even for non-Newtonian fluids in the future. AU - Josch, Sebastian AU - Jesinghausen, Steffen AU - Dechert, Christopher AU - Schmid, Hans-Joachim ID - 36983 JF - Rheologica Acta KW - rheology KW - rheometry KW - suspension KW - coaxial KW - correction SN - 0035-4511 TI - Experimental and simulative determination and correction of the effective gap extension in structured coaxial measuring systems ER - TY - CONF AB - We present an approach for guaranteed constraint satisfaction by means of data-based optimal control, where the model is unknown and has to be obtained from measurement data. To this end, we utilize the Koopman framework and an eDMD-based bilinear surrogate modeling approach for control systems to show an error bound on predicted observables, i.e., functions of the state. This result is then applied to the constraints of the optimal control problem to show that satisfaction of tightened constraints in the purely data-based surrogate model implies constraint satisfaction for the original system. AU - Schaller, Manuel AU - Worthmann, Karl AU - Philipp, Friedrich AU - Peitz, Sebastian AU - Nüske, Feliks ID - 30125 IS - 1 T2 - IFAC-PapersOnLine TI - Towards reliable data-based optimal and predictive control using extended DMD VL - 56 ER - TY - JOUR AB - AU - Heck, Tamara AU - Steinhardt, Isabel AU - Rahal, Rima-Maria AU - Schubotz, Moritz AU - Scholl, Dominik AU - Behrens, Sarah ID - 43094 JF - Research Ideas and Outcomes KW - Open Science SN - 2367-7163 TI - Bootstrapping the Open Science culture: The fellowship approach VL - 9 ER - TY - GEN ED - Meine, Sabine ED - Otto, Arnold ED - Süßmann, Johannes ID - 35062 SN - 978-3-8260-7218-5 TI - Musiklandschaften zwischen Rhein und Weser. Pluralisierung und Verflechtung entlang des Hellwegs in der Frühen Neuzeit. Unter Mitarbeit v. Markus Lauert VL - 13 ER - TY - JOUR AB - High-contrast slab waveguide Bragg gratings with 1D periodicity are investigated. For specific oblique excitation by semi-guided waves at sufficiently high angles of incidence, the idealized structures do not exhibit any radiative losses, such that reflectance and transmittance for the single port mode add strictly up to one. We consider a series of symmetric, fully and partly etched finite gratings, for parameters found in integrated silicon photonics. These can act as spectral filters with a reasonably flattop response. Apodization can lead to more box shaped reflectance and transmittance spectra. Together with a narrowband Fabry–Perot filter, these configurations are characterized by reflection bands, or transmittance peaks, with widths that span three orders of magnitude. AU - Hammer, Manfred AU - Farheen, Henna AU - Förstner, Jens ID - 43245 IS - 4 JF - Journal of the Optical Society of America B KW - tet_topic_waveguide SN - 0740-3224 TI - How to suppress radiative losses in high-contrast integrated Bragg gratings VL - 40 ER - TY - GEN AU - Meier, Torsten AU - Grisard, S. AU - Trifonov, A.V. AU - Rose, Hendrik AU - Reichhardt, R. AU - Reichelt, Matthias AU - Schneider, C. AU - Kamp, M. AU - Höfling, S. AU - Bayer, M. AU - Akimov, I.A ID - 43132 T2 - arxiv:2302.02480 TI - Temporal sorting of optical multi-wave-mixing processes in semiconductor quantum dots ER - TY - JOUR AB - We present strong enhancement of third harmonic generation in an amorphous silicon metasurface consisting of elliptical nano resonators. We show that this enhancement originates from a new type of multi-mode Fano mechanism. These ‘Super-Fano’ resonances are investigated numerically in great detail using full-wave simulations. The theoretically predicted behavior of the metasurface is experimentally verified by linear and nonlinear transmission spectroscopy. Moreover, quantitative nonlinear measurements are performed, in which an absolute conversion efficiency as high as ηmax ≈ 2.8 × 10−7 a peak power intensity of 1.2 GW cm−2 is found. Compared to an unpatterned silicon film of the same thickness amplification factors of up to ~900 are demonstrated. Our results pave the way to exploiting a strong Fano-type multi-mode coupling in metasurfaces for high THG in potential applications. AU - Hähnel, David AU - Golla, Christian AU - Albert, Maximilian AU - Zentgraf, Thomas AU - Myroshnychenko, Viktor AU - Förstner, Jens AU - Meier, Cedrik ID - 44097 IS - 1 JF - Light: Science & Applications KW - tet_topic_meta SN - 2047-7538 TI - A multi-mode super-fano mechanism for enhanced third harmonic generation in silicon metasurfaces VL - 12 ER - TY - BOOK AU - Bauer, Anna Brigitte ID - 44083 SN - 978-3-8325-5625-9 TI - Experimentelle Kompetenz Physikstudierender. Entwicklung und erste Erprobung eines performanzorientierten Kompetenzstrukturmodells unter Nutzung qualitativer Methoden VL - 352 ER - TY - GEN AU - Schürmann, Patrick ID - 43374 TI - A Formal Comparison of Advanced Digital Signature Primitives ER - TY - JOUR AB - Microcellular wood fiber reinforced polymers offer the possibility to reduce the use of fossil raw materials. In particular, thick-walled structures with thicknesses greater than 6 mm offer a high potential for weight savings. This study investigates the cell structures and mechanical properties of injection-molded test specimens. The influence of different thicknesses (6–10 mm) along with different chemical blowing agents (endothermic, exothermic) with varying dosages (0–2 wt%) is analyzed. The investigations reveal that exothermic chemical blowing agents form finer cells consistently to thin-walled structures than endothermic ones. Higher foaming agent content leads to higher pore fractions, with many small cells coalescing into a large open-pore cell network. The mechanical properties depend mainly on the pore content of the sample. The specific tensile properties deteriorate with the use of chemical blowing agents (CFA), whereas the sandwich structure produced with compact edge layers has a positive influence on the specific flexural properties. AU - Moritzer, Elmar AU - Flachmann, Felix ID - 42515 IS - 3 JF - Journal of Cellular Plastics KW - Materials Chemistry KW - Polymers and Plastics KW - General Chemistry SN - 0021-955X TI - Morphological and mechanical properties of foamed thick-walled Wood-Plastic-Composite structures VL - 59 ER - TY - JOUR AU - Burmeister, Sascha Christian AU - Schryen, Guido ID - 42179 JF - Energy Systems TI - Distribution Network Optimization: Predicting computation times to design scenario analysis for network operators ER - TY - JOUR AB - Abstract The accessibility to rheological parameters for concrete is becoming more and more relevant. This is mainly related to the constantly emerging challenges, such as not only the development of high-strength concretes is progressing very fast but also the simulation of the flow behaviour is of high importance. The main problem, however, is that the rheological characterisation of fresh concrete is not possible via commercial rheometers. The so-called concrete rheometers provide valuable relative values for comparing different concretes, but they cannot measure absolute values. Therefore, we developed an adaptive coaxial concrete rheometer (ACCR) that allows the measurement of fresh concrete with particles up to d max = 5.5 mm {d}_{{\rm{\max }}}=5.5\hspace{.5em}{\rm{mm}} . The comparison of the ACCR with a commercial rheometer showed very good agreement for selected test materials (Newtonian fluid, shear thinning fluid, suspension, and yield stress fluid), so that self-compacting concrete was subsequently measured. Since these measurements showed a very high reproducibility, the rheological properties of the fresh concrete could be determined with high accuracy. The common flow models (Bingham (B), Herschel–Bulkley, modified Bingham (MB) models) were also tested for their applicability, with the Bingham and the modified Bingham model proving to be the best suitable ones. AU - Josch, Sebastian AU - Jesinghausen, Steffen AU - Schmid, Hans-Joachim ID - 43034 IS - 1 JF - Applied Rheology KW - Condensed Matter Physics KW - General Materials Science SN - 1617-8106 TI - Development of an adaptive coaxial concrete rheometer and rheological characterisation of fresh concrete VL - 33 ER - TY - CHAP AB - State education in honest tax payment can be understood as a facet of training in citizenship, i.e. as an attempt by the modern state to standardize the behavior of its citizens and to prevent deviations. Based on this Foucauldian understanding, this exploratory article examines tax education in the United States, Spain, and West Germany from the mid-1940s to the late 1980s. During this period, the USA asserted itself as the champion of tax education and Spain consistently tried to emulate this example, albeit with more modest means and different semantic strategies from as early as the 1960s, when it was still under a autoritarian regime. The FRG, however, completely discontinued its few early attempts at tax education from the mid-1950s onwards. Even during the economic crises and tax scandals of the 1970s, there was no relaunch of the programs. The article locates the reasons for this highly uneven development in the different ideal images of the citizen in the three states. AU - Schönhärl, Korinna AU - Düll, Nasrin AU - Ramírez Lugo , Nadya Melina ED - Sébastien, Guex ED - Hadrien, Buclin ID - 44249 T2 - Tax Evasion and Tax Havens since the Nineteenth Century TI - Tax Education After WWII: How Spain, the USA, and West Germany Tried to Make Their Citizens Pay Honestly ER - TY - JOUR AU - Neumann, Phillip ID - 44321 IS - 5 JF - Zeitschrift für Heilpädagogik KW - Inklusion KW - Sonderpädagogik KW - Bildung KW - Bildungsstudien KW - Integration SN - 0513-9066 TI - Studien zu Schulleistungen und ihre Aufbereitung VL - 74 ER - TY - CHAP AU - Meine, Sabine AU - Otto, Arnold AU - Süßmann, Johannes ID - 35063 SN - 978-3-8260-7218-5 T2 - Musiklandschaften zwischen Rhein und Weser. Pluralisierung und Verflechtung entlang des Hellwegs in der Frühen Neuzeit. Unter Mitarbeit v. Markus Lauert TI - Musiklandschaften zwischen Rhein und Weser – Einführung ER - TY - CONF AU - Gharibian, Sevag AU - Watson, James AU - Bausch, Johannes ID - 20841 T2 - Proceedings of the 40th International Symposium on Theoretical Aspects of Computer Science (STACS) TI - The Complexity of Translationally Invariant Problems beyond Ground State Energies VL - 254 ER - TY - GEN AB - For open world applications, deep neural networks (DNNs) need to be aware of previously unseen data and adaptable to evolving environments. Furthermore, it is desirable to detect and learn novel classes which are not included in the DNNs underlying set of semantic classes in an unsupervised fashion. The method proposed in this article builds upon anomaly detection to retrieve out-of-distribution (OoD) data as candidates for new classes. We thereafter extend the DNN by $k$ empty classes and fine-tune it on the OoD data samples. To this end, we introduce two loss functions, which 1) entice the DNN to assign OoD samples to the empty classes and 2) to minimize the inner-class feature distances between them. Thus, instead of ground truth which contains labels for the different novel classes, the DNN obtains a single OoD label together with a distance matrix, which is computed in advance. We perform several experiments for image classification and semantic segmentation, which demonstrate that a DNN can extend its own semantic space by multiple classes without having access to ground truth. AU - Uhlemeyer, Svenja AU - Lienen, Julian AU - Hüllermeier, Eyke AU - Gottschalk, Hanno ID - 44512 T2 - arXiv:2305.00983 TI - Detecting Novelties with Empty Classes ER - TY - JOUR AB - With enhancing digitalization, condition monitoring is used in an increasing number of application fields across various industrial sectors. By its application, increased reliability as well as reduced risks and costs can be achieved. Based on different approaches, technical systems are monitored and measured data is analyzed to enable condition-based or predictive maintenance. To this end, machine learning approaches are usually implemented to diagnose the health states or predict the health index of the monitored system. However, these trained models are often black-box models, not intuitively explainable for a human. To overcome this shortcoming, a model-based approach based on physics is developed for piezoelectric bending actuators. Such a model enables a transparent representation of the system. Moreover, the model-based approach is extended by a parameter-estimation to account for sudden changes in behavior e. g. caused by occurring cracks. AU - Bender, Amelie ID - 44672 JF - Sensors and Actuators A: Physical KW - Condition Monitoring KW - Model-based approach Diagnostics KW - Varying conditions KW - Explainability KW - Piezoelectric bending actuators SN - 0924-4247 TI - Model-based condition monitoring of piezoelectric bending actuators VL - 357 ER - TY - CONF AU - Ahmed, Qazi Arbab AU - Awais, Muhammad AU - Platzner, Marco ID - 44194 T2 - The 24th International Symposium on Quality Electronic Design (ISQED'23), San Francisco, Califorina USA TI - MAAS: Hiding Trojans in Approximate Circuits ER - TY - JOUR AB - Dispersion is present in every optical setup and is often an undesired effect, especially in nonlinear-optical experiments where ultrashort laser pulses are needed. Typically, bulky pulse compressors consisting of gratings or prisms are used to address this issue by precompensating the dispersion of the optical components. However, these devices are only able to compensate for a part of the dispersion (second-order dispersion). Here, we present a compact pulse-shaping device that uses plasmonic metasurfaces to apply an arbitrarily designed spectral phase delay allowing for a full dispersion control. Furthermore, with specific phase encodings, this device can be used to temporally reshape the incident laser pulses into more complex pulse forms such as a double pulse. We verify the performance of our device by using an SHG-FROG measurement setup together with a retrieval algorithm to extract the dispersion that our device applies to an incident laser pulse. AU - Geromel, René AU - Georgi, Philip AU - Protte, Maximilian AU - Lei, Shiwei AU - Bartley, Tim AU - Huang, Lingling AU - Zentgraf, Thomas ID - 44044 IS - 8 JF - Nano Letters KW - Mechanical Engineering KW - Condensed Matter Physics KW - General Materials Science KW - General Chemistry KW - Bioengineering SN - 1530-6984 TI - Compact Metasurface-Based Optical Pulse-Shaping Device VL - 23 ER - TY - JOUR AB - Hydrothermal carbonization (HTC) is an efficient thermochemical method for the conversion of organic feedstock to carbonaceous solids. HTC of different saccharides is known to produce microspheres (MS) with mostly Gaussian size distribution, which are utilized as functional materials in various applications, both as pristine MS and as a precursor for hard carbon MS. Although the average size of the MS can be influenced by adjusting the process parameters, there is no reliable mechanism to affect their size distribution. Our results demonstrate that HTC of trehalose, in contrast to other saccharides, results in a distinctly bimodal sphere diameter distribution consisting of small spheres with diameters of (2.1 ± 0.2) μm and of large spheres with diameters of (10.4 ± 2.6) μm. Remarkably, after pyrolytic post-carbonization at 1000 °C the MS develop a multimodal pore size distribution with abundant macropores > 100 nm, mesopores > 10 nm and micropores < 2 nm, which were examined by small-angle X-ray scattering and visualized by charge-compensated helium ion microscopy. The bimodal size distribution and hierarchical porosity provide an extraordinary set of properties and potential variables for the tailored synthesis of hierarchical porous carbons, making trehalose-derived hard carbon MS a highly promising material for applications in catalysis, filtration, and energy storage devices. AU - Wortmann, Martin AU - Keil, Waldemar AU - Diestelhorst, Elise AU - Westphal, Michael AU - Haverkamp, René AU - Brockhagen, Bennet AU - Biedinger, Jan AU - Bondzio, Laila AU - Weinberger, Christian AU - Baier, Dominik AU - Tiemann, Michael AU - Hütten, Andreas AU - Hellweg, Thomas AU - Reiss, Günter AU - Schmidt, Claudia AU - Sattler, Klaus AU - Frese, Natalie ID - 44837 IS - 21 JF - RSC Advances KW - General Chemical Engineering KW - General Chemistry SN - 2046-2069 TI - Hard carbon microspheres with bimodal size distribution and hierarchical porosity via hydrothermal carbonization of trehalose VL - 13 ER - TY - CONF AU - Dreiling, Dmitrij AU - Itner, Dominik AU - Hetkämper, Tim AU - Birk, Carolin AU - Gravenkamp, Hauke AU - Henning, Bernd ID - 45205 SN - 978-3-9819376-8-8 T2 - SMSI 2023 Conference TI - Improved determination of viscoelastic material parameters using a pulse-echo measurement setup ER - TY - GEN AU - Koch, Angelina ID - 43375 TI - Privacy-Preserving Collection and Evaluation of Log Files ER - TY - JOUR AU - Schryen, Guido AU - Sperling, Martina ID - 44361 IS - September JF - Computers & Operations Research TI - Literature Reviews in Operations Research: A New Taxonomy and a Meta Review VL - 157 ER - TY - JOUR AB - Dielectric metasurfaces provide a unique platform for efficient harmonic generation and optical wavefront manipulation at the nanoscale. Tailoring phase and amplitude of a nonlinearly generated wave with a high emission efficiency using resonance-based metasurfaces is a challenging task that often requires state-of-the-art numerical methods. Here, we propose a simple yet effective approach combining a sampling method with a Monte Carlo approach to design the third-harmonic wavefront generated by all-dielectric metasurfaces composed of elliptical silicon nanodisks. Using this approach, we theoretically demonstrate the full nonlinear 2π phase control with a uniform and highest possible amplitude in the considered parameter space, allowing us to design metasurfaces operating as third harmonic beam deflectors capable of steering light into a desired direction with high emission efficiency. The TH beam deflection with a record calculated average conversion efficiency of 1.2 × 10–1 W–2 is achieved. We anticipate that the proposed approach will be widely applied as alternative to commonly used optimization algorithms with higher complexity and implementation effort for the design of metasurfaces with other holographic functionalities. AU - Hähnel, David AU - Förstner, Jens AU - Myroshnychenko, Viktor ID - 45596 JF - ACS Photonics KW - tet_topic_meta SN - 2330-4022 TI - Efficient Modeling and Tailoring of Nonlinear Wavefronts in Dielectric Metasurfaces ER - TY - CHAP AU - Freymuth, Nina ED - Balz, HHans-Jürgen ED - Huneke, Annika ED - Kuhlmann, Carola ED - Römisch, Kathrin ID - 45606 T2 - Diskriminierungsprozesse und Teilhabeperspektiven - Herausforderungen für die Praxis der Inklusion. Ausgewählte Master-Thesen 2018-2022 des Masterstudiengangs "Soziale Inklusion: Gesundheit und Bildung" der Evangelischen Hochschule Rheinland-Westfalen-Lippe TI - Alternative für alle? Inklusionsspezifische Analyse der AfD und ihrer Wähler*innen ER - TY - JOUR AU - Dieter, Peter AU - Caron, Matthew AU - Schryen, Guido ID - 44383 IS - 1 JF - European Journal of Operational Research (EJOR) TI - Integrating driver behavior into last-mile delivery routing: Combining machine learning and optimization in a hybrid decision support framework VL - 311 ER - TY - JOUR AU - Meier, Jana AU - Janzen, Thomas AU - Wotschel, Philipp AU - Vogelsang, Christoph ID - 45672 JF - die hochschullehre TI - Rollenspielbasierte Simulationen als Übungs- und Prüfungsformate im Lehramtsstudium. Eine explorative Studie zu Erfahrungen und Einschätzungen aus Studierendensicht. VL - 9 ER - TY - CONF AU - Hotegni, Sedjro Salomon AU - Mahabadi, Sepideh AU - Vakilian, Ali ID - 45695 KW - Fair range clustering T2 - Proceedings of the 40th International Conference on Machine Learning, Honolulu, Hawaii, USA. PMLR 202, 2023. TI - Approximation Algorithms for Fair Range Clustering ER - TY - CONF AU - Hebrok, Sven Niclas AU - Nachtigall, Simon AU - Maehren, Marcel AU - Erinola, Nurullah AU - Merget, Robert AU - Somorovsky, Juraj AU - Schwenk, Jörg ID - 43060 T2 - 32nd USENIX Security Symposium TI - We Really Need to Talk About Session Tickets: A Large-Scale Analysis of Cryptographic Dangers with TLS Session Tickets ER - TY - JOUR AB - Faradaic reactions including charge transfer are often accompanied with diffusion limitation inside the bulk. Conductive two-dimensional frameworks (2D MOFs) with a fast ion transport can combine both - charge transfer and fast diffusion inside their porous structure. To study remaining diffusion limitations caused by particle morphology, different synthesis routes of Cu-2,3,6,7,10,11-hexahydroxytriphenylene (Cu3(HHTP)2), a copper-based 2D MOF, are used to obtain flake- and rod-like MOF particles. Both morphologies are systematically characterized and evaluated for redox-active Li+ ion storage. The redox mechanism is investigated by means of X-ray absorption spectroscopy, FTIR spectroscopy and in situ XRD. Both types are compared regarding kinetic properties for Li+ ion storage via cyclic voltammetry and impedance spectroscopy. A significant influence of particle morphology for 2D MOFs on kinetic aspects of electrochemical Li+ ion storage can be observed. This study opens the path for optimization of redox active porous structures to overcome diffusion limitations of Faradaic processes. AU - Wrogemann, Jens Matthies AU - Lüther, Marco Joes AU - Bärmann, Peer AU - Lounasvuori, Mailis AU - Javed, Ali AU - Tiemann, Michael AU - Golnak, Ronny AU - Xiao, Jie AU - Petit, Tristan AU - Placke, Tobias AU - Winter, Martin ID - 44116 IS - 26 JF - Angewandte Chemie International Edition KW - General Chemistry KW - Catalysis SN - 1433-7851 TI - Overcoming Diffusion Limitation of Faradaic Processes: Property‐Performance Relationships of 2D Conductive Metal‐Organic Framework Cu3(HHTP)2 for Reversible Lithium‐Ion Storage VL - 62 ER - TY - GEN ED - Eckel, Julia ED - Ernst, Christoph ED - Schröter, Jens ID - 36842 IS - 1 KW - tech demo KW - technology demonstration KW - demo or die SN - 1619-1641 T2 - Navigationen - Zeitschrift für Medien- und Kulturwissenschaften TI - Navigationen: Tech | Demo VL - 23 ER - TY - CONF AU - Abbas, Nilab AU - Bauer, Anna Brigitte AU - Reinhold, Peter ED - van Vorst, Helena ID - 45759 T2 - Lernen, Lehren und Forschen in einer digital geprägten Welt TI - PSΦ: Entwicklung von Unterstützungsmaßnahmen für Theoretische Physik ER - TY - CONF AU - Bauer, Anna Brigitte AU - Reinhold, Peter ED - van Vorst, Helena ID - 45758 T2 - Lernen, Lehren und Forschen in einer digital geprägten Welt TI - PSФ: Entwicklung einer abgestimmten Studieneingangsphase (Physik) ER - TY - JOUR AB - A series of new organic donor–π–acceptor dyes incorporating a diquat moiety as a novel electron-acceptor unit have been synthesized and characterized. The analytical data were supported by DFT calculations. These dyes were explored in the aerobic thiocyanation of indoles and pyrroles. Here they showed a high photocatalytic activity under visible light, giving isolated yields of up to 97 %. In addition, the photocatalytic activity of standalone diquat and methyl viologen through formation of an electron donor acceptor complex is presented. AU - Meier, Armin AU - Badalov, Sabuhi AU - Biktagirov, Timur AU - Schmidt, Wolf Gero AU - Wilhelm, René ID - 43827 IS - 22 JF - Chemistry – A European Journal KW - General Chemistry KW - Catalysis KW - Organic Chemistry SN - 0947-6539 TI - Diquat Based Dyes: A New Class of Photoredox Catalysts and Their Use in Aerobic Thiocyanation VL - 29 ER - TY - JOUR AB - As a benchmark, the structural, electronic and optical properties of the three main phases of TiO$\rm{_2}$ crystals have been calculated using Hubbard U correction and hybrid functional methods in density-functional theory. These calculations are compared concerning the available experimental observations on pristine TiO$\rm{_2}$ crystals. Modified hybrid functionals, particularly the PBE0 functional with 11.4% fraction of exact exchange, are shown to provide highly accurate atomic structures and also accurate electronic structure data, including optical excitation energies. With $\rm{DFT+U}$, accurate optical spectra are also possible, but only if the Hubbard U is applied on the O $\rm2p$ electrons exclusively. Furthermore, both methods, the 11.4%-PBE0 hybrid functional and the $\rm{DFT+U_p}$ scheme have been used to study TiO$\rm{_2}$ amorphous ultra-thin films, confirming the agreement of the two methods even with respect to small details of the optical spectra. Our results show that the proposed $\rm{DFT+U_p}$ methodology is computationally efficient, but still accurate. It can be applied to well-ordered TiO$\rm{_2}$ polymorphs as well as to amorphous TiO$\rm{_2}$ and will allow for the calculations of complex titania-based structures. AU - Badalov, Sabuhi AU - Bocchini, Adriana AU - Wilhelm, Rene AU - Kozub, A. L. AU - Gerstmann, Uwe AU - Schmidt, Wolf Gero ID - 45764 JF - Materials Research Express TI - Rutile, anatase, brookite and titania thin film from Hubbard corrected and hybrid DFT ER - TY - JOUR AB - The development of automotive components with reduced greenhouse gas (GHG) emissions is needed to reduce overall vehicle emissions. Life Cycle Engineering (LCE) based on Life Cycle Assessment (LCA) supports this by providing holistic information and improvement potentials regarding eco-efficient products. Key factors influencing LCAs of automotive components, such as material production, will change in the future. First approaches for integrating future scenarios for these key factors into LCE already exist, but they only consider a limited number of parameters and scenarios. This work aims to develop a method that can be practically applied in the industry for integrating prospective LCAs (pLCA) into the LCE of automotive components, considering relevant parameters and consistent scenarios. Therefore, pLCA methods are further developed to investigate the influence of future scenarios on the GHG emissions of automotive components. The practical application is demonstrated for a vehicle component with different design options. This paper shows that different development paths of the foreground and background system can shift the ecological optimum of design alternatives. Therefore, future pathways of relevant parameters must be considered comprehensively to reduce GHG emissions of future vehicles. This work contributes to the methodological and practical integration of pLCA into automotive development processes and provides quantitative results. AU - Grenz, Julian AU - Ostermann, Moritz AU - Käsewieter, Karoline AU - Cerdas, Felipe AU - Marten, Thorsten AU - Herrmann, Christoph AU - Tröster, Thomas ID - 45782 IS - 13 JF - Sustainability KW - prospective LCA KW - life cycle engineering (LCE) KW - lightweight design KW - automotive components KW - body parts KW - circular economy KW - steel KW - aluminum KW - hybrid materials KW - fiber metal laminates SN - 2071-1050 TI - Integrating Prospective LCA in the Development of Automotive Components VL - 15 ER - TY - CONF AB - The notion of neural collapse refers to several emergent phenomena that have been empirically observed across various canonical classification problems. During the terminal phase of training a deep neural network, the feature embedding of all examples of the same class tend to collapse to a single representation, and the features of different classes tend to separate as much as possible. Neural collapse is often studied through a simplified model, called the unconstrained feature representation, in which the model is assumed to have "infinite expressivity" and can map each data point to any arbitrary representation. In this work, we propose a more realistic variant of the unconstrained feature representation that takes the limited expressivity of the network into account. Empirical evidence suggests that the memorization of noisy data points leads to a degradation (dilation) of the neural collapse. Using a model of the memorization-dilation (M-D) phenomenon, we show one mechanism by which different losses lead to different performances of the trained network on noisy data. Our proofs reveal why label smoothing, a modification of cross-entropy empirically observed to produce a regularization effect, leads to improved generalization in classification tasks. AU - Nguyen, Duc Anh AU - Levie, Ron AU - Lienen, Julian AU - Kutyniok, Gitta AU - Hüllermeier, Eyke ID - 31880 T2 - International Conference on Learning Representations, ICLR TI - Memorization-Dilation: Modeling Neural Collapse Under Noise ER - TY - GEN AB - Label noise poses an important challenge in machine learning, especially in deep learning, in which large models with high expressive power dominate the field. Models of that kind are prone to memorizing incorrect labels, thereby harming generalization performance. Many methods have been proposed to address this problem, including robust loss functions and more complex label correction approaches. Robust loss functions are appealing due to their simplicity, but typically lack flexibility, while label correction usually adds substantial complexity to the training setup. In this paper, we suggest to address the shortcomings of both methodologies by "ambiguating" the target information, adding additional, complementary candidate labels in case the learner is not sufficiently convinced of the observed training label. More precisely, we leverage the framework of so-called superset learning to construct set-valued targets based on a confidence threshold, which deliver imprecise yet more reliable beliefs about the ground-truth, effectively helping the learner to suppress the memorization effect. In an extensive empirical evaluation, our method demonstrates favorable learning behavior on synthetic and real-world noise, confirming the effectiveness in detecting and correcting erroneous training labels. AU - Lienen, Julian AU - Hüllermeier, Eyke ID - 45814 T2 - arXiv:2305.13764 TI - Mitigating Label Noise through Data Ambiguation ER - TY - CONF AB - Many applications require explainable node classification in knowledge graphs. Towards this end, a popular ``white-box'' approach is class expression learning: Given sets of positive and negative nodes, class expressions in description logics are learned that separate positive from negative nodes. Most existing approaches are search-based approaches generating many candidate class expressions and selecting the best one. However, they often take a long time to find suitable class expressions. In this paper, we cast class expression learning as a translation problem and propose a new family of class expression learning approaches which we dub neural class expression synthesizers. Training examples are ``translated'' into class expressions in a fashion akin to machine translation. Consequently, our synthesizers are not subject to the runtime limitations of search-based approaches. We study three instances of this novel family of approaches based on LSTMs, GRUs, and set transformers, respectively. An evaluation of our approach on four benchmark datasets suggests that it can effectively synthesize high-quality class expressions with respect to the input examples in approximately one second on average. Moreover, a comparison to state-of-the-art approaches suggests that we achieve better F-measures on large datasets. For reproducibility purposes, we provide our implementation as well as pretrained models in our public GitHub repository at https://github.com/dice-group/NeuralClassExpressionSynthesis AU - KOUAGOU, N'Dah Jean AU - Heindorf, Stefan AU - Demir, Caglar AU - Ngonga Ngomo, Axel-Cyrille ED - Pesquita, Catia ED - Jimenez-Ruiz, Ernesto ED - McCusker, Jamie ED - Faria, Daniel ED - Dragoni, Mauro ED - Dimou, Anastasia ED - Troncy, Raphael ED - Hertling, Sven ID - 33734 KW - Neural network KW - Concept learning KW - Description logics T2 - The Semantic Web - 20th Extended Semantic Web Conference (ESWC 2023) TI - Neural Class Expression Synthesis VL - 13870 ER - TY - GEN AB - Label noise poses an important challenge in machine learning, especially in deep learning, in which large models with high expressive power dominate the field. Models of that kind are prone to memorizing incorrect labels, thereby harming generalization performance. Many methods have been proposed to address this problem, including robust loss functions and more complex label correction approaches. Robust loss functions are appealing due to their simplicity, but typically lack flexibility, while label correction usually adds substantial complexity to the training setup. In this paper, we suggest to address the shortcomings of both methodologies by "ambiguating" the target information, adding additional, complementary candidate labels in case the learner is not sufficiently convinced of the observed training label. More precisely, we leverage the framework of so-called superset learning to construct set-valued targets based on a confidence threshold, which deliver imprecise yet more reliable beliefs about the ground-truth, effectively helping the learner to suppress the memorization effect. In an extensive empirical evaluation, our method demonstrates favorable learning behavior on synthetic and real-world noise, confirming the effectiveness in detecting and correcting erroneous training labels. AU - Lienen, Julian AU - Hüllermeier, Eyke ID - 45244 T2 - arXiv:2305.13764 TI - Mitigating Label Noise through Data Ambiguation ER - TY - JOUR AB - Perfect vector vortex beams (PVVBs) have attracted considerable interest due to their peculiar optical features. PVVBs are typically generated through the superposition of perfect vortex beams, which suffer from the limited number of topological charges (TCs). Furthermore, dynamic control of PVVBs is desirable and has not been reported. We propose and experimentally demonstrate hybrid grafted perfect vector vortex beams (GPVVBs) and their dynamic control. Hybrid GPVVBs are generated through the superposition of grafted perfect vortex beams with a multifunctional metasurface. The generated hybrid GPVVBs possess spatially variant rates of polarization change due to the involvement of more TCs. Each hybrid GPVVB includes different GPVVBs in the same beam, adding more design flexibility. Moreover, these beams are dynamically controlled with a rotating half waveplate. The generated dynamic GPVVBs may find applications in the fields where dynamic control is in high demand, including optical encryption, dense data communication, and multiple particle manipulation. AU - Ahmed, Hammad AU - Ansari, Muhammad Afnan AU - Li, Yan AU - Zentgraf, Thomas AU - Mehmood, Muhammad Qasim AU - Chen, Xianzhong ID - 45868 IS - 1 JF - Nature Communications KW - General Physics and Astronomy KW - General Biochemistry KW - Genetics and Molecular Biology KW - General Chemistry KW - Multidisciplinary SN - 2041-1723 TI - Dynamic control of hybrid grafted perfect vector vortex beams VL - 14 ER - TY - CHAP AU - Götte, Thorsten AU - Knollmann, Till AU - Meyer auf der Heide, Friedhelm AU - Scheideler, Christian AU - Werthmann, Julian ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45875 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Capabilities and Limitations of Local Strategies in Dynamic Networks VL - 412 ER - TY - CHAP AU - Karl, Holger AU - Maack, Marten AU - Meyer auf der Heide, Friedhelm AU - Pukrop, Simon AU - Redder, Adrian ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45895 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - On-The-Fly Compute Centers II: Execution of Composed Services in Configurable Compute Centers VL - 412 ER - TY - CHAP AU - Blömer, Johannes AU - Bobolz, Jan AU - Eidens, Fabian AU - Jager, Tibor AU - Kramer, Paul ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45901 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Practical Cryptograhic Techniques for Secure and Privacy-Preserving Customer Loyalty Systems VL - 412 ER - TY - CHAP AU - Boschmann, Alexander AU - Clausing, Lennart AU - Jentzsch, Felix AU - Ghasemzadeh Mohammadi, Hassan AU - Platzner, Marco ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45899 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Flexible Industrial Analytics on Reconfigurable Systems-On-Chip VL - 412 ER - TY - CHAP AU - Wehrheim, Heike AU - Platzner, Marco AU - Bodden, Eric AU - Schubert, Philipp AU - Pauck, Felix AU - Jakobs, Marie-Christine ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45888 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Verifying Software and Reconfigurable Hardware Services VL - 412 ER - TY - CHAP AU - Gottschalk, Sebastian AU - Vorbohle, Christian AU - Kundisch, Dennis AU - Engels, Gregor AU - Wünderlich, Nacy V. ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45897 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Architectural Management of OTF Computing Markets VL - 412 ER - TY - CHAP AU - Blömer, Johannes AU - Eidens, Fabian AU - Jager, Tibor AU - Niehues, David AU - Scheideler, Christian ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45891 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Robustness and Security VL - 412 ER - TY - CHAP AU - Bäumer, Frederik Simon AU - Chen, Wei-Fan AU - Geierhos, Michaela AU - Kersting, Joschka AU - Wachsmuth, Henning ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45882 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Dialogue-based Requirement Compensation and Style-adjusted Data-to-text Generation VL - 412 ER - TY - CHAP AU - Hanselle, Jonas Manuel AU - Hüllermeier, Eyke AU - Mohr, Felix AU - Ngonga Ngomo, Axel-Cyrille AU - Sherif, Mohamed AU - Tornede, Alexander AU - Wever, Marcel Dominik ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45884 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Configuration and Evaluation VL - 412 ER - TY - CHAP AU - Haake, Claus-Jochen AU - Hehenkamp, Burkhard AU - Polevoy, Gleb ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45878 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - The Market for Services: Incentives, Algorithms, Implementation VL - 412 ER - TY - CHAP AU - Wehrheim, Heike AU - Hüllermeier, Eyke AU - Becker, Steffen AU - Becker, Matthias AU - Richter, Cedric AU - Sharma, Arnab ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45886 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Composition Analysis in Unknown Contexts VL - 412 ER - TY - GEN AB - Label noise poses an important challenge in machine learning, especially in deep learning, in which large models with high expressive power dominate the field. Models of that kind are prone to memorizing incorrect labels, thereby harming generalization performance. Many methods have been proposed to address this problem, including robust loss functions and more complex label correction approaches. Robust loss functions are appealing due to their simplicity, but typically lack flexibility, while label correction usually adds substantial complexity to the training setup. In this paper, we suggest to address the shortcomings of both methodologies by "ambiguating" the target information, adding additional, complementary candidate labels in case the learner is not sufficiently convinced of the observed training label. More precisely, we leverage the framework of so-called superset learning to construct set-valued targets based on a confidence threshold, which deliver imprecise yet more reliable beliefs about the ground-truth, effectively helping the learner to suppress the memorization effect. In an extensive empirical evaluation, our method demonstrates favorable learning behavior on synthetic and real-world noise, confirming the effectiveness in detecting and correcting erroneous training labels. AU - Lienen, Julian AU - Hüllermeier, Eyke ID - 45911 T2 - arXiv:2305.13764 TI - Mitigating Label Noise through Data Ambiguation ER - TY - CHAP AU - Elrich, Alina AU - Kaimann, Daniel AU - Fahr, René AU - Kundisch, Dennis AU - Mir Djawadi, Behnud AU - Müller, Michelle AU - Poniatowski, Martin AU - Schäfers, Sabrina AU - Frick, Bernd ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45880 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Empirical Analysis in Markets for OTF Services VL - 412 ER - TY - JOUR AB - Intending to counteract Klein’s second discontinuity in teacher education, we explored and applied the innovation of “interface ePortfolio” in the context of a geometry course for preservice teachers (PSTs). The tool offers the possibility of implementing the design principle of profession orientation. In the article, we theoretically clarify what we understand by this principle and locate our innovative concept against this theoretical background. We empirically investigate the extent to which counteraction against the second discontinuity is successful by analyzing reflection texts created in the interface ePortfolio, focusing on PSTs’ perspectives. Our qualitative content analysis shows that most of them perceive the innovation as helpful in the intended sense and indicates that the course concept, in general, and the interface ePortfolio, in particular, have helped establish relevant links between the course content and their later work as teachers. AU - Hoffmann, Max AU - Biehler, Rolf ID - 45786 JF - ZDM – Mathematics Education KW - General Mathematics KW - Education SN - 1863-9690 TI - Implementing profession orientation as a design principle for overcoming Klein’s second discontinuity – preservice teacher’s perspectives on interface activities in the context of a geometry course ER - TY - JOUR AU - Dieter, Peter AU - Stumpe, Miriam AU - Ulmer, Marlin Wolf AU - Schryen, Guido ID - 45816 JF - Transportation Research Part D TI - Anticipatory Assignment of Passengers to Meeting Points for Taxi-Ridesharing VL - 121 ER - TY - GEN AU - Leineweber, Jonas ID - 46102 TI - Tagungsbericht: 10/20 Jahre UNESCO-Konvention zum Erhalt des Immateriellen Kulturerbes – Auftaktveranstaltung zum Doppeljubiläum ER - TY - CHAP AU - Janzen, Thomas AU - Gabel, Stephan AU - Gampert, Martha AU - Matz, Frauke AU - Reckermann, Julia ED - Mrohs, Lorenz ED - Hess, Miriam ED - Lindner, Konstantin ED - Schlüter, Julia ED - Overhage, Sven ID - 46154 T2 - Digitalisierung in der Hochschullehre – Perspektiven und Gestaltungsoptionen TI - Das DigitELE Tutorial: Eine digitale Lernumgebung in der Englischdidaktik ER - TY - JOUR AB - While FPGA accelerator boards and their respective high-level design tools are maturing, there is still a lack of multi-FPGA applications, libraries, and not least, benchmarks and reference implementations towards sustained HPC usage of these devices. As in the early days of GPUs in HPC, for workloads that can reasonably be decoupled into loosely coupled working sets, multi-accelerator support can be achieved by using standard communication interfaces like MPI on the host side. However, for performance and productivity, some applications can profit from a tighter coupling of the accelerators. FPGAs offer unique opportunities here when extending the dataflow characteristics to their communication interfaces. In this work, we extend the HPCC FPGA benchmark suite by multi-FPGA support and three missing benchmarks that particularly characterize or stress inter-device communication: b_eff, PTRANS, and LINPACK. With all benchmarks implemented for current boards with Intel and Xilinx FPGAs, we established a baseline for multi-FPGA performance. Additionally, for the communication-centric benchmarks, we explored the potential of direct FPGA-to-FPGA communication with a circuit-switched inter-FPGA network that is currently only available for one of the boards. The evaluation with parallel execution on up to 26 FPGA boards makes use of one of the largest academic FPGA installations. AU - Meyer, Marius AU - Kenter, Tobias AU - Plessl, Christian ID - 38041 JF - ACM Transactions on Reconfigurable Technology and Systems KW - General Computer Science SN - 1936-7406 TI - Multi-FPGA Designs and Scaling of HPC Challenge Benchmarks via MPI and Circuit-Switched Inter-FPGA Networks ER - TY - CHAP AU - Hansmeier, Tim AU - Kenter, Tobias AU - Meyer, Marius AU - Riebler, Heinrich AU - Platzner, Marco AU - Plessl, Christian ED - Haake, Claus-Jochen ED - Meyer auf der Heide, Friedhelm ED - Platzner, Marco ED - Wachsmuth, Henning ED - Wehrheim, Heike ID - 45893 T2 - On-The-Fly Computing -- Individualized IT-services in dynamic markets TI - Compute Centers I: Heterogeneous Execution Environments VL - 412 ER - TY - CONF AU - Opdenhövel, Jan-Oliver AU - Plessl, Christian AU - Kenter, Tobias ID - 46190 T2 - Proceedings of the 13th International Symposium on Highly Efficient Accelerators and Reconfigurable Technologies TI - Mutation Tree Reconstruction of Tumor Cells on FPGAs Using a Bit-Level Matrix Representation ER - TY - CONF AU - Faj, Jennifer AU - Kenter, Tobias AU - Faghih-Naini, Sara AU - Plessl, Christian AU - Aizinger, Vadym ID - 46188 T2 - Proceedings of the Platform for Advanced Scientific Computing Conference TI - Scalable Multi-FPGA Design of a Discontinuous Galerkin Shallow-Water Model on Unstructured Meshes ER - TY - CONF AU - Prouveur, Charles AU - Haefele, Matthieu AU - Kenter, Tobias AU - Voss, Nils ID - 46189 T2 - Proceedings of the Platform for Advanced Scientific Computing Conference TI - FPGA Acceleration for HPC Supercapacitor Simulations ER - TY - JOUR AU - Demir, Caglar AU - Ngonga Ngomo, Axel-Cyrille ID - 46243 JF - ECML-PKDD TI - Clifford Embeddings – A Generalized Approach for Embedding in Normed Algebras ER - TY - JOUR AU - Demir, Caglar AU - Ngonga Ngomo, Axel-Cyrille ID - 46251 JF - International Joint Conference on Artificial Intelligence TI - Neuro-Symbolic Class Expression Learning ER - TY - JOUR AB - The non-orthogonal local submatrix method applied to electronic structure–based molecular dynamics simulations is shown to exceed 1.1 EFLOP/s in FP16/FP32-mixed floating-point arithmetic when using 4400 NVIDIA A100 GPUs of the Perlmutter system. This is enabled by a modification of the original method that pushes the sustained fraction of the peak performance to about 80%. Example calculations are performed for SARS-CoV-2 spike proteins with up to 83 million atoms. AU - Schade, Robert AU - Kenter, Tobias AU - Elgabarty, Hossam AU - Lass, Michael AU - Kühne, Thomas AU - Plessl, Christian ID - 45361 JF - The International Journal of High Performance Computing Applications KW - Hardware and Architecture KW - Theoretical Computer Science KW - Software SN - 1094-3420 TI - Breaking the exascale barrier for the electronic structure problem in ab-initio molecular dynamics ER - TY - THES AU - Tornede, Alexander ID - 45780 TI - Advanced Algorithm Selection with Machine Learning: Handling Large Algorithm Sets, Learning From Censored Data, and Simplyfing Meta Level Decisions ER - TY - CONF AB - The article shows how to learn models of dynamical systems from data which are governed by an unknown variational PDE. Rather than employing reduction techniques, we learn a discrete field theory governed by a discrete Lagrangian density $L_d$ that is modelled as a neural network. Careful regularisation of the loss function for training $L_d$ is necessary to obtain a field theory that is suitable for numerical computations: we derive a regularisation term which optimises the solvability of the discrete Euler--Lagrange equations. Secondly, we develop a method to find solutions to machine learned discrete field theories which constitute travelling waves of the underlying continuous PDE. AU - Offen, Christian AU - Ober-Blöbaum, Sina ED - Nielsen, F ED - Barbaresco, F ID - 42163 KW - System identification KW - discrete Lagrangians KW - travelling waves T2 - Geometric Science of Information TI - Learning discrete Lagrangians for variational PDEs from data and detection of travelling waves VL - 14071 ER - TY - JOUR AB - The principle of least action is one of the most fundamental physical principle. It says that among all possible motions connecting two points in a phase space, the system will exhibit those motions which extremise an action functional. Many qualitative features of dynamical systems, such as the presence of conservation laws and energy balance equations, are related to the existence of an action functional. Incorporating variational structure into learning algorithms for dynamical systems is, therefore, crucial in order to make sure that the learned model shares important features with the exact physical system. In this paper we show how to incorporate variational principles into trajectory predictions of learned dynamical systems. The novelty of this work is that (1) our technique relies only on discrete position data of observed trajectories. Velocities or conjugate momenta do not need to be observed or approximated and no prior knowledge about the form of the variational principle is assumed. Instead, they are recovered using backward error analysis. (2) Moreover, our technique compensates discretisation errors when trajectories are computed from the learned system. This is important when moderate to large step-sizes are used and high accuracy is required. For this, we introduce and rigorously analyse the concept of inverse modified Lagrangians by developing an inverse version of variational backward error analysis. (3) Finally, we introduce a method to perform system identification from position observations only, based on variational backward error analysis. AU - Ober-Blöbaum, Sina AU - Offen, Christian ID - 29240 JF - Journal of Computational and Applied Mathematics KW - Lagrangian learning KW - variational backward error analysis KW - modified Lagrangian KW - variational integrators KW - physics informed learning SN - 0377-0427 TI - Variational Learning of Euler–Lagrange Dynamics from Data VL - 421 ER - TY - JOUR AB - The numerical solution of an ordinary differential equation can be interpreted as the exact solution of a nearby modified equation. Investigating the behaviour of numerical solutions by analysing the modified equation is known as backward error analysis. If the original and modified equation share structural properties, then the exact and approximate solution share geometric features such as the existence of conserved quantities. Conjugate symplectic methods preserve a modified symplectic form and a modified Hamiltonian when applied to a Hamiltonian system. We show how a blended version of variational and symplectic techniques can be used to compute modified symplectic and Hamiltonian structures. In contrast to other approaches, our backward error analysis method does not rely on an ansatz but computes the structures systematically, provided that a variational formulation of the method is known. The technique is illustrated on the example of symmetric linear multistep methods with matrix coefficients. AU - McLachlan, Robert AU - Offen, Christian ID - 29236 IS - 1 JF - Journal of Geometric Mechanics KW - variational integrators KW - backward error analysis KW - Euler--Lagrange equations KW - multistep methods KW - conjugate symplectic methods TI - Backward error analysis for conjugate symplectic methods VL - 15 ER - TY - JOUR AB - Recently, Hamiltonian neural networks (HNN) have been introduced to incorporate prior physical knowledge when learning the dynamical equations of Hamiltonian systems. Hereby, the symplectic system structure is preserved despite the data-driven modeling approach. However, preserving symmetries requires additional attention. In this research, we enhance the HNN with a Lie algebra framework to detect and embed symmetries in the neural network. This approach allows to simultaneously learn the symmetry group action and the total energy of the system. As illustrating examples, a pendulum on a cart and a two-body problem from astrodynamics are considered. AU - Dierkes, Eva AU - Offen, Christian AU - Ober-Blöbaum, Sina AU - Flaßkamp, Kathrin ID - 37654 IS - 6 JF - Chaos SN - 1054-1500 TI - Hamiltonian Neural Networks with Automatic Symmetry Detection VL - 33 ER -