@unpublished{63150, author = {{Cummings, Charley and Gratz, Sira and Kirkman, Ellen and Letz, Janina Carmen and Rock, J. Daisie and Špenko, Špela}}, pages = {{1--9}}, title = {{{An equivalence linking CM-types $A_\infty$ and $D_\infty$}}}, year = {{2025}}, } @unpublished{63149, author = {{Kekkou, Antonia and Letz, Janina Carmen and Stephan, Marc}}, pages = {{1--37}}, title = {{{Regular sequences for triangulated categories}}}, year = {{2025}}, } @unpublished{63148, author = {{Letz, Janina Carmen}}, pages = {{1--7}}, title = {{{The Rouquier dimension of the category of perfect complexes over a regular ring}}}, year = {{2025}}, } @article{59507, abstract = {{Differential equations posed on quadratic matrix Lie groups arise in the context of classical mechanics and quantum dynamical systems. Lie group numerical integrators preserve the constants of motions defining the Lie group. Thus, they respect important physical laws of the dynamical system, such as unitarity and energy conservation in the context of quantum dynamical systems, for instance. In this article we develop a high-order commutator free Lie group integrator for non-autonomous differential equations evolving on quadratic Lie groups. Instead of matrix exponentials, which are expensive to evaluate and need to be approximated by appropriate rational functions in order to preserve the Lie group structure, the proposed method is obtained as a composition of Cayley transforms which naturally respect the structure of quadratic Lie groups while being computationally efficient to evaluate. Unlike Cayley-Magnus methods the method is also free from nested matrix commutators.}}, author = {{Wembe Moafo, Boris Edgar and Offen, Cristian and Maslovskaya, Sofya and Ober-Blöbaum, Sina and Singh, Pranav}}, journal = {{J. Comput. Appl. Math}}, number = {{15}}, title = {{{Commutator-free Cayley methods}}}, doi = {{10.1016/j.cam.2025.117184}}, volume = {{477}}, year = {{2025}}, } @inproceedings{63157, abstract = {{Three-phase cascaded H-bridge converters (CHBs) in star configuration require reliable current controllers to evenly charge the module DC-link capacitors. Conventionally, a current control in dq-coordinates is utilized. At steady state, the resulting calculated reference arm voltages are sinusoidal, have identical amplitudes and show a phase shift of 120 degree to each other. For balanced grid inductors, the resulting grid currents also have the same amplitude. However, own simulations show that unbalanced grid inductors always lead to different grid current amplitudes (4% difference in this case). As a result, the averaged charging module powers differ and the peak DC-link capacitor voltage rises as well. In the first step, an adaptation of an existing zero-sequence voltage injection is proposed. For balanced grid inductors, it converges to the 3rd harmonic voltage injection which can reduce the peak-to-peak DC-link voltage ripple up by to 50% and balances the power between the phases. However, unbalanced grid inductors still lead to the same unbalanced grid currents of 4%. Therefore, a new method with 4 integrators based on linear regression is proposed to achieve sinusoidal grid currents for unbalanced inductors. The proposed method has a similar transient dynamic as the conventional dq control, but balances the grid currents nearly ideally. Simulation results of a 1MW cascaded H bridge and a scaled-down prototype verify the proposed method.}}, author = {{Unruh, Roland and Böcker, Joachim and Schafmeister, Frank}}, booktitle = {{2025 Energy Conversion Congress & Expo Europe (ECCE Europe)}}, keywords = {{Cascaded H-Bridge, Current Control, dq Transformation, Linear Regression, Unbalanced Inductors}}, location = {{Birmingham, United Kingdom}}, publisher = {{IEEE}}, title = {{{Three-Phase Instantaneous Current Controller for Unbalanced Grid Inductors Without DQ Transform for Cascaded H-Bridge Converters}}}, doi = {{10.1109/ecce-europe62795.2025.11238538}}, year = {{2025}}, } @unpublished{63187, author = {{Kidner, Arnott Jeffery Joel and Steffen, Eckhard and Yu, Weiqiang}}, booktitle = {{arXiv:2512.14285}}, title = {{{Edge-coloring 4- and 5-regular projective planar graphs with no Petersen-minor}}}, year = {{2025}}, } @inproceedings{60746, author = {{Jakobeit, Darius and Peña López, Mario and Schenke, Maximilian and Haucke-Korber, Barnabas and Wallscheid, Oliver}}, booktitle = {{2025 IEEE International Electric Machines & Drives Conference (IEMDC)}}, publisher = {{IEEE}}, title = {{{Structural Optimization of Meta-Reinforcement Learning-based Finite-Control-Set Direct Torque Control of Permanent Magnet Synchronous Motors}}}, doi = {{10.1109/iemdc60492.2025.11061179}}, year = {{2025}}, } @inproceedings{60745, author = {{Haucke-Korber, Barnabas and Aung, Nyi Nyi and Schenke, Maximilian and Peña López, Mario and Jakobeit, Darius and Wallscheid, Oliver}}, booktitle = {{2025 IEEE International Electric Machines & Drives Conference (IEMDC)}}, publisher = {{IEEE}}, title = {{{Reinforcement Learning-based Direct Torque Control of Externally Excited Synchronous Motors: a Proof of Concept}}}, doi = {{10.1109/iemdc60492.2025.11061093}}, year = {{2025}}, } @inproceedings{60744, author = {{Peña López, Mario and Schenke, Maximilian and Jakobeit, Darius and Haucke-Korber, Barnabas and Wallscheid, Oliver}}, booktitle = {{2025 IEEE International Electric Machines & Drives Conference (IEMDC)}}, publisher = {{IEEE}}, title = {{{Reinforcement Learning Control of Three-Level Converter Permanent Magnet Synchronous Machine Drives}}}, doi = {{10.1109/iemdc60492.2025.11061032}}, year = {{2025}}, } @unpublished{63384, abstract = {{Two fundamental ways to represent a group are as permutations and as matrices. In this paper, we study linear representations of groups that intertwine with a permutation representation. Recently, D'Alconzo and Di Scala investigated how small the matrices in such a linear representation can be. The minimal dimension of such a representation is the \emph{linear dimension of the group action} and this has applications in cryptography and cryptosystems. We develop the idea of linear dimension from an algebraic point of view by using the theory of permutation modules. We give structural results about representations of minimal dimension and investigate the implications of faithfulness, transitivity and primitivity on the linear dimension. Furthermore, we compute the linear dimension of several classes of finite primitive permutation groups. We also study wreath products, allowing us to determine the linear dimension of imprimitive group actions. Finally, we give the linear dimension of almost simple finite $2$-transitive groups, some of which may be used for further applications in cryptography. Our results also open up many new questions about linear representations of group actions.}}, author = {{Devillers, Alice and Giudici, Michael and Hawtin, Daniel R. and Klawuhn, Lukas-André Dominik and Morgan, Luke}}, title = {{{Linear dimension of group actions}}}, year = {{2025}}, } @unpublished{63394, abstract = {{We study the statistics of the number of real eigenvalues in the elliptic deformation of the real Ginibre ensemble. As the matrix dimension grows, the law of large numbers and the central limit theorem for the number of real eigenvalues are well understood, but the probabilities of rare events remain largely unexplored. Large deviation type results have been obtained only in extreme cases, when either a vanishingly small proportion of eigenvalues are real or almost all eigenvalues are real. Here, in both the strong and weak asymmetry regimes, we derive the probabilities of rare events in the moderate-to-large deviation regime, thereby providing a natural connection between the previously known regime of Gaussian fluctuations and the large deviation regime. Our results are new even for the classical real Ginibre ensemble.}}, author = {{Byun, Sung-Soo and Jalowy, Jonas and Lee, Yong-Woo and Schehr, Grégory}}, booktitle = {{arXiv:2511.09191}}, title = {{{Moderate-to-large deviation asymptotics for real eigenvalues of the elliptic Ginibre matrices}}}, year = {{2025}}, } @unpublished{63393, abstract = {{We study the evolution of zeros of high polynomial powers under the heat flow. For any fixed polynomial $P(z)$, we prove that the empirical zero distribution of its heat-evolved $n$-th power converges to a distribution on the complex plane as $n$ tends to infinity. We describe this limit distribution $μ_t$ as a function of the time parameter $t$ of the heat evolution: For small time, zeros start to spread out in approximately semicircular distributions, then intricate curves start to form and merge, until for large time, the zero distribution approaches a widespread semicircle law through the initial center of mass. The Stieltjes transform of the limit distribution $μ_t$ satisfies a self-consistent equation and a Burgers' equation. The present paper deals with general complex-rooted polynomials for which, in contrast to the real-rooted case, no free-probabilistic representation for $μ_t$ is available.}}, author = {{Höfert, Antonia and Jalowy, Jonas and Kabluchko, Zakhar}}, booktitle = {{arXiv:2512.17808}}, title = {{{Zeros of polynomial powers under the heat flow}}}, year = {{2025}}, } @unpublished{63403, abstract = {{Stateful signatures like the NIST standardized signature schemes LMS and XMSS provide an efficient and mature realization of post-quantum secure signature schemes. They are recommended for long-term use cases like e.g. firmware signing. However, stateful signature schemes require to properly manage a so-called state. In stateful signature schemes like LMS and XMSS, signing keys consist of a set of keys of a one-time signature scheme and it has to be guaranteed that each one-time key is used only once. This is done by updating a state in each signature computation, basically recording which one-time keys have already been used. While this is straightforward in centralized systems, in distributed systems like secure enclaves consisting of e.g. multiple hardware security modules (HSMs) with limited communication keeping a distributed state that at any point in time is consistent among all parties involved presents a challenge. This challenge is not addressed by the current standardization processes. In this paper we present a security model for the distributed key management of post-quantum secure stateful signatures like XMSS and LMS. We also present a simple, efficient, and easy to implement protocol proven secure in this security model, i.e. the protocol guarantees at any point in time a consistent state among the parties in a distributed system, like a distributed security enclave. The security model is defined in the universal composabilty (UC) framework by Ran Canetti by providing an ideal functionality for the distributed key management for stateful signatures. Hence our protocol remains secure even if arbitrarily composed with other instances of the same or other protocols, a necessity for the security of distributed key management protocols. Our main application are security enclaves consisting of HSMs, but the model and the protocol can easily be adapted to other scenarios of distributed key management of stateful signature schemes.}}, author = {{Blömer, Johannes and Bröcher, Henrik and Krummel, Volker and Porzenheim, Laurens Alexander}}, keywords = {{distributed state, hash-based signature, stateful hash-based signature, universal composability, secure enclave}}, pages = {{22}}, title = {{{Secure Distributed State Management for Stateful Signatures with a Practical and Universally Composable Protocol}}}, year = {{2025}}, } @inproceedings{63434, author = {{Hoffmann, Max}}, booktitle = {{Proceedings of the Fourteenth Congress of the European Society for Research in Mathematics Education (CERME14)}}, editor = {{Bosch, Marianna and Bolondi, Giorgio and Carreira, Susana and Michael, Gaidoschik and Camilla, Spagnolo}}, keywords = {{hoffmann, reviewed, proceedings}}, title = {{{Using scriptwriting as a response format for interface tasks: Exemplary analyses in the context of symmetry}}}, year = {{2025}}, } @article{63433, author = {{Hoffmann, Max}}, journal = {{mathematik lehren}}, number = {{253}}, pages = {{39--44}}, title = {{{Digitale Perspektiven auf das Heron-Verfahren}}}, doi = {{https://doi.org/10.5555/ml-253-2025_07}}, year = {{2025}}, } @article{62000, author = {{Claes, Leander and Koch, Kevin and Friesen, Olga and Meihost, Lars}}, issn = {{2681-4617}}, journal = {{Acta Acustica}}, number = {{65}}, publisher = {{EDP Sciences}}, title = {{{Machine Learning-Supported Inverse Measurement Procedure for Broadband, Temperature Dependent Piezoelectric Material Parameters}}}, doi = {{10.1051/aacus/2025044}}, volume = {{9}}, year = {{2025}}, } @article{54837, author = {{Claes, Leander and Lankeit, Johannes and Winkler, Michael}}, issn = {{1793-6314}}, journal = {{Mathematical Models and Methods in Applied Sciences}}, number = {{11}}, pages = {{2465--2512}}, publisher = {{World Scientific Pub Co Pte Ltd}}, title = {{{A model for heat generation by acoustic waves in piezoelectric materials: Global large-data solutions}}}, doi = {{10.1142/s0218202525500447}}, volume = {{35}}, year = {{2025}}, } @inproceedings{62299, author = {{Friesen, Olga and Scheidemann, Claus and Claes, Leander and Hemsel, Tobias and Henning, Bernd}}, booktitle = {{2025 International Congress on Ultrasonics}}, pages = {{138–141}}, publisher = {{AMA Service GmbH}}, title = {{{Sensitivity Analysis and Material Parameter Estimation of a Pre-Stressed Langevin Transducer}}}, doi = {{10.5162/ultrasonic2025/a18-a4}}, year = {{2025}}, } @inproceedings{62298, author = {{Kuess, Raphael and Friesen, Olga and Henning, Bernd and Walther, Andrea}}, booktitle = {{2025 International Congress on Ultrasonics}}, pages = {{134–137}}, publisher = {{AMA Service GmbH}}, title = {{{Identification of temperature-dependent material parameter functions in piezoelectricity}}}, doi = {{10.5162/ultrasonic2025/a18-a3}}, year = {{2025}}, } @inproceedings{59689, author = {{Friesen, Olga and Meihost, Lars and Koch, Kevin and Claes, Leander and Henning, Bernd}}, location = {{Copenhagen}}, title = {{{Estimation of piezoelectric material parameters under varying electric field conditions}}}, doi = {{10.71568/DASDAGA2025.078}}, year = {{2025}}, }