@article{64979, abstract = {{We investigate homogeneous coupled cell systems with high-dimensional internal dynamics. In many studies on network dynamics, the analysis is restricted to networks with one-dimensional internal dynamics. Here, we show how symmetry explains the relation between dynamical behavior of systems with one-dimensional internal dynamics and with higher dimensional internal dynamics, when the underlying network topology is the same. Fundamental networks of homogeneous coupled cell systems (B. Rink, J. Sanders. Coupled Cell Networks and Their Hidden Symmetries. SIAM J. Math. Anal. 46.2 (2014)) can be expressed in terms of monoid representations, which uniquely decompose into indecomposable subrepresentations. In the high-dimensional internal dynamics case, these subrepresentations are isomorphic to multiple copies of those one computes in the one-dimensional internal dynamics case. This has interesting implications for possible center subspaces in bifurcation analysis. We describe the effect on steady state and Hopf bifurcations in l-parameter families of network vector fields. The main results in that regard are that (1) generic one-parameter steady state bifurcations are qualitatively independent of the dimension of the internal dynamics and that, (2) in order to observe all generic l-parameter bifurcations that may occur for internal dynamics of any dimension, the internal dynamics has to be at least l-dimensional for steady state bifurcations and 2l-dimensional for Hopf bifurcations. Furthermore, we illustrate how additional structure in the network can be exploited to obtain even greater understanding of bifurcation scenarios in the high-dimensional case beyond qualitative statements about the collective dynamics. One-parameter steady state bifurcations in feedforward networks exhibit an unusual amplification in the asymptotic growth rates of individual cells, when these are one-dimensional (S. von der Gracht, E. Nijholt, B. Rink. Amplified steady state bifurcations in feedforward networks. Nonlinearity 35.4 (2022)). As another main result, we prove that (3) the same cells exhibit this amplifying effect with the same growth rates when the internal dynamics is high-dimensional.}}, author = {{von der Gracht, Sören and Nijholt, Eddie and Rink, Bob}}, issn = {{0960-0779}}, journal = {{Chaos, Solitons & Fractals}}, keywords = {{Coupled cell systems, Network dynamics, Dimension reduction, Bifurcation theory, Symmetry, Monoid representation theory}}, publisher = {{Elsevier BV}}, title = {{{Homogeneous coupled cell systems with high-dimensional internal dynamics}}}, doi = {{10.1016/j.chaos.2026.118196}}, volume = {{208}}, year = {{2026}}, } @unpublished{58953, abstract = {{In this article, we investigate symmetry properties of distributed systems of mobile robots. We consider a swarm of n robots in the OBLOT model and analyze their collective Fsync dynamics using of equivariant dynamical systems theory. To this end, we show that the corresponding evolution function commutes with rotational and reflective transformations of R^2. These form a group that is isomorphic to O(2) x S_n, the product group of the orthogonal group and the permutation on n elements. The theory of equivariant dynamical systems is used to deduce a hierarchy along which symmetries of a robot swarm can potentially increase following an arbitrary protocol. By decoupling the Look phase from the Compute and Move phases in the mathematical description of an LCM cycle, this hierarchy can be characterized in terms of automorphisms of connectivity graphs. In particular, we find all possible types of symmetry increase, if the decoupled Compute and Move phase is invertible. Finally, we apply our results to protocols which induce state-dependent linear dynamics, where the reduced system consisting of only the Compute and Move phase is linear.}}, author = {{Gerlach, Raphael and von der Gracht, Sören}}, booktitle = {{arXiv:2503.07576}}, keywords = {{dynamical systems, coupled systems, distributed computing, robot swarms, autonomous mobile robots, symmetry, equivariant dynamics}}, pages = {{23}}, title = {{{Analyzing Symmetries of Swarms of Mobile Robots Using Equivariant Dynamical Systems}}}, year = {{2025}}, } @article{57472, abstract = {{In this paper we introduce, in a Hilbert space setting, a second order dynamical system with asymptotically vanishing damping and vanishing Tikhonov regularization that approaches a multiobjective optimization problem with convex and differentiable components of the objective function. Trajectory solutions are shown to exist in finite dimensions. We prove fast convergence of the function values, quantified in terms of a merit function. Based on the regime considered, we establish both weak and, in some cases, strong convergence of trajectory solutions toward a weak Pareto optimal solution. To achieve this, we apply Tikhonov regularization individually to each component of the objective function. This work extends results from single objective convex optimization into the multiobjective setting.}}, author = {{Bot, Radu Ioan and Sonntag, Konstantin}}, journal = {{Journal of Mathematical Analysis and Applications}}, keywords = {{Pareto optimization, Lyapunov analysis, gradient-like dynamical systems, inertial dynamics, asymptotic vanishing damping, Tikhonov regularization, strong convergence}}, title = {{{Inertial dynamics with vanishing Tikhonov regularization for multobjective optimization}}}, year = {{2025}}, } @article{32447, abstract = {{We present a new gradient-like dynamical system related to unconstrained convex smooth multiobjective optimization which involves inertial effects and asymptotic vanishing damping. To the best of our knowledge, this system is the first inertial gradient-like system for multiobjective optimization problems including asymptotic vanishing damping, expanding the ideas previously laid out in [H. Attouch and G. Garrigos, Multiobjective Optimization: An Inertial Dynamical Approach to Pareto Optima, preprint, arXiv:1506.02823, 2015]. We prove existence of solutions to this system in finite dimensions and further prove that its bounded solutions converge weakly to weakly Pareto optimal points. In addition, we obtain a convergence rate of order \(\mathcal{O}(t^{-2})\) for the function values measured with a merit function. This approach presents a good basis for the development of fast gradient methods for multiobjective optimization.}}, author = {{Sonntag, Konstantin and Peitz, Sebastian}}, issn = {{1095-7189}}, journal = {{SIAM Journal on Optimization}}, keywords = {{multiobjective optimization, Pareto optimization, Lyapunov analysis, gradient-likedynamical systems, inertial dynamics, asymptotic vanishing damping, fast convergence}}, number = {{3}}, pages = {{2259 -- 2286}}, publisher = {{Society for Industrial and Applied Mathematics}}, title = {{{Fast Convergence of Inertial Multiobjective Gradient-Like Systems with Asymptotic Vanishing Damping}}}, doi = {{10.1137/23M1588512}}, volume = {{34}}, year = {{2024}}, } @article{59171, abstract = {{To model dynamical systems on networks with higher-order (non-pairwise) interactions, we recently introduced a new class of ordinary differential equations (ODEs) on hypernetworks. Here, we consider one-parameter synchrony breaking bifurcations in such ODEs. We call a synchrony breaking steady-state branch ‘reluctant’ if it is tangent to a synchrony space, but does not lie inside it. We prove that reluctant synchrony breaking is ubiquitous in hypernetwork systems, by constructing a large class of examples that support it. We also give an explicit formula for the order of tangency to the synchrony space of a reluctant steady-state branch.}}, author = {{von der Gracht, Sören and Nijholt, Eddie and Rink, Bob}}, issn = {{1364-5021}}, journal = {{Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences}}, keywords = {{higher-order interactions, synchrony breaking, network dynamics, coupled cell systems}}, number = {{2301}}, publisher = {{The Royal Society}}, title = {{{Higher-order interactions lead to ‘reluctant’ synchrony breaking}}}, doi = {{10.1098/rspa.2023.0945}}, volume = {{480}}, year = {{2024}}, } @inproceedings{29934, abstract = {{Tire and road wear are a major source of emissions of nonexhaust particulate matter (PM) and make up the largest share of microplastics in the environment. To reduce tire wear through numerical optimization of a vehicle's suspension system, fast simulations of the representative usage of a vehicle are needed. Therefore, this contribution evaluates if instead of a full simulation of a representative test drive, only specific driving maneuvers resulting from a clustering of the driving data can be used to predict tire wear. As a measure for tire wear, the friction work between tire and road is calculated. It is shown that enough clusters result in negligible deviations between the total friction work of the full simulation and the cluster simulations as well as between the distributions of the friction work over the tire width. The calculation time can be reduced to about 1% of the full simulation.}}, author = {{Muth, Lars and Noll, Christian and Sextro, Walter}}, booktitle = {{Advances in Dynamics of Vehicles on Roads and Tracks II - Proceedings of the 27th Symposium of the International Association of Vehicle System Dynamics, IAVSD 2021}}, editor = {{Orlova, Anna and Cole, David}}, isbn = {{978-3-031-07304-5}}, keywords = {{Tire Wear, Vehicle Dynamics, Clustering, Virtual Test}}, location = {{Saint Petersburg, Russia}}, publisher = {{Springer}}, title = {{{Generation of a Reduced, Representative, Virtual Test Drive for Fast Evaluation of Tire Wear by Clustering of Driving Data}}}, doi = {{10.1007/978-3-031-07305-2_92}}, year = {{2022}}, } @inproceedings{36462, abstract = {{The conduction of structure-borne sound through joints causes energy dissipation. The sound reduction index describes this energy loss as a level decrease in the particle velocity across series-connected damping elements for which the superposition principle applies. This simple model can help to develop a testing method for joints based on this characteristic energy loss. In this paper, this model is experimentally evaluated for multiple in-series clinched aluminium sheets. Samples connected by several clinch points arranged in parallel are investigated experimentally, and the results are discussed.}}, author = {{Stephan, Richard and Brosius, Alexander}}, booktitle = {{The 28th Saxon Conference on Forming Technology SFU and the 7th International Conference on Accuracy in Forming Technology ICAFT}}, keywords = {{clinching, mechanical joining, damping, model, evaluation, dynamics}}, publisher = {{MDPI}}, title = {{{Experimental Measurement Method and Evaluation of an Analytical Approach for Sound Conduction through Multiple Clinched Sheets}}}, doi = {{10.3390/engproc2022026025}}, year = {{2022}}, } @article{63948, abstract = {{In this work, the behavior of four different commercially available polarizing agents is investigated employing the non-ionic model surfactant 1-octanol as analyte. A relative method for the comparison of the proportion of the direct and indirect polarization transfer pathways is established, allowing a direct comparison of the polarization efficacy for different radicals and different parts of the 1-octanol molecule despite differences in radical concentration or sample amount. With this approach, it could be demonstrated that the hydrophilicity is a key factor in the way polarization is transferred from the polarizing agent to the analyte. These findings are confirmed by the determination of buildup times Tb, illustrating that the choice of polarizing agent plays an essential role in ensuring an optimal polarization transfer and therefore the maximum amount of enhancement possible for DNP enhanced NMR measurements.}}, author = {{Döller, Sonja C. and Gutmann, Torsten and Hoffmann, Markus and Buntkowsky, Gerd}}, journal = {{Solid State Nuclear Magnetic Resonance}}, keywords = {{DNP NMR, Dynamics, Low temperature NMR, Octanol, Solid state NMR, Surfactants}}, pages = {{101829}}, title = {{{A case study on the influence of hydrophilicity on the signal enhancement by dynamic nuclear polarization}}}, volume = {{122}}, year = {{2022}}, } @inbook{34707, abstract = {{Of the many outstanding female philosophers of the European Enlightenment, Emilie Du Châtelet excelled as a physicist, a philosopher, and a mathematician, as well as a Bible critic. She was famous in her lifetime and was not completely forgotten thereafter. Among her admirers, correspondents and friends were the most acknowledged scholars of her time, including Voltaire, Clairault, Maupertuis, Diderot, Helvetius, La Mettrie, Buffon, Christian Wolff, Leonard Euler, and Johann II Bernoulli. Her philosophical work enjoyed high reputation and her opus magnum, the Institutions physiques, was translated into Italian and German and proved her to be an intellectual of European stature. Its defense of living forces and its implied forecast into dynamics as well as her methodological grounding of scientific knowledge as hypothetical, impacted philosophy and science. Reality must by nature escape us. What we perceive are phenomena. Du Châtelet explains the function of space and time to trace us back to the origin of phenomena. Her influence on Kant is evident. Next to her writings in physics, mathematics, philosophy, language, and logic, she contributed to morality and ethics. Du Châtelet left an opus of quite systematic breadth. This impressive publishing activity excels in the amount of its scientific and philosophical production to which a vast collection of manuscripts must be added.She argued against prejudice and idolatry in philosophy and science. Science is a cooperative undertaking over history and beyond nations. Her moral writings align with ideas of the French materialists. Du Châtelet translated and commented on Newton’s Principia, preparing thus the fertile soil of the generation of physicists to come in France.}}, author = {{Hagengruber, Ruth}}, booktitle = {{Encyclopedia of Early Modern Philosophy and the Sciences}}, isbn = {{9783319207919}}, keywords = {{aura Bassi Luise Gottsched Immanuel Kant Dourtous de Mairan Johann II Bernoulli Algarotti Buffon d’Alembert La Mettrie Principle of contradiction Hypotheses Enlightenment Leibniz-Clarke Correspondence Living forces Dead forces, happiness Space Imaginary beings Monads Epicurus Ethics Women philosophers Newton’s laws Principia Motion inertia Active force Vis viva Vis mortua Hypothetic reasoning Hypotheses, a priori principles, Experience, Dead forces, Living forces, Energy Dynamics}}, publisher = {{Springer International Publishing}}, title = {{{Du Châtelet, Émilie (1706–1749)}}}, doi = {{10.1007/978-3-319-20791-9_410-1}}, year = {{2021}}, } @article{6542, abstract = {{Transient changes of the optical response of WS2 monolayers are studied by femtosecond broadband pump–probe spectroscopy. Time-dependent absorption spectra are analyzed by tracking the line width broadening, bleaching, and energy shift of the main exciton resonance as a function of time delay after the excitation. Two main sources for the pump-induced changes of the optical response are identified. Specifically, we find an interplay between modifications induced by many-body interactions from photoexcited carriers and by the subsequent transfer of the excitation to the phonon system followed by cooling of the material through the heat transfer to the substrate.}}, author = {{Ruppert, Claudia and Chernikov, Alexey and Hill, Heather M. and Rigosi, Albert F. and Heinz, Tony F.}}, issn = {{1530-6984}}, journal = {{Nano Letters}}, keywords = {{Atomically thin 2D materials, carrier and phonon dynamics, ultrafast spectroscopy}}, number = {{2}}, pages = {{644--651}}, publisher = {{American Chemical Society (ACS)}}, title = {{{The Role of Electronic and Phononic Excitation in the Optical Response of Monolayer WS2 after Ultrafast Excitation}}}, doi = {{10.1021/acs.nanolett.6b03513}}, volume = {{17}}, year = {{2017}}, } @article{13241, abstract = {{The accuracy of water models derived from ab initio molecular dynamics simulations by means on an improved force-matching scheme is assessed for various thermodynamic, transport, and structural properties. It is found that although the resulting force-matched water models are typically less accurate than fully empirical force fields in predicting thermodynamic properties, they are nevertheless much more accurate than generally appreciated in reproducing the structure of liquid water and in fact superseding most of the commonly used empirical water models. This development demonstrates the feasibility to routinely parametrize computationally efficient yet predictive potential energy functions based on accurate ab initio molecular dynamics simulations for a large variety of different systems. © 2016 Wiley Periodicals, Inc.}}, author = {{Köster, Andreas and Spura, Thomas and Rutkai, Gábor and Kessler, Jan and Wiebeler, Hendrik and Vrabec, Jadran and Kühne, Thomas D.}}, journal = {{Journal of Computational Chemistry}}, keywords = {{liquid water, force matching, ab initio, molecular dynamics, Monte Carlo}}, number = {{19}}, pages = {{1828--1838}}, title = {{{Assessing the accuracy of improved force-matched water models derived from Ab initio molecular dynamics simulations}}}, doi = {{10.1002/jcc.24398}}, volume = {{37}}, year = {{2016}}, } @inproceedings{17660, author = {{Polevoy, Gleb and de Weerdt, Mathijs M.}}, booktitle = {{Proceedings of the 2014 International Conference on Autonomous Agents and Multi-agent Systems}}, isbn = {{978-1-4503-2738-1}}, keywords = {{dynamics, emotion modeling, negotiation, network interaction, shared effort game}}, pages = {{1741--1742}}, publisher = {{International Foundation for Autonomous Agents and Multiagent Systems}}, title = {{{Improving Human Interaction in Crowdsensing}}}, year = {{2014}}, } @article{6088, abstract = {{An attended stimulus reduces the perceptual latency of a later stimulus at the same location, leading to the intriguing finding that the perceived order between the two is often reversed. This prior-entry effect has been well established in a number of different cueing paradigms, mostly involving spatial attentional shifts. Here we assess the time-course of prior entry when all stimuli appear in rapid serial presentation at one location. Our findings indicate that the size of the attentional enhancement is strongly affected by the stimulus onset asynchrony between cue and target, with a rapid early peak, followed by decay. When task-irrelevant cues are used, the cueing effect on prior entry is short-lived and peaks as early as 50 ms. The benefit extends to about 100 ms when task-relevant cues are employed. These results fit with a straightforward computational model of transient attentional enhancement, peaking about 80 100 ms after stimulus detection. (PsycINFO Database Record (c) 20}}, author = {{Hilkenmeier, Frederic and Scharlau, Ingrid and Weiß, Katharina and Olivers, Christian N. L.}}, issn = {{1350-6285}}, journal = {{Visual Cognition}}, keywords = {{serial visual processing, prior entry dynamics, cueing paradigms, Cues, Visual Perception, Visual Search}}, number = {{1}}, pages = {{48 -- 76}}, title = {{{The dynamics of prior entry in serial visual processing.}}}, volume = {{20}}, year = {{2012}}, } @inproceedings{11939, abstract = {{In this paper a switching linear dynamical model (SLDM) approach for speech feature enhancement is improved by employing more accurate models for the dynamics of speech and noise. The model of the clean speech feature trajectory is improved by augmenting the state vector to capture information derived from the delta features. Further a hidden noise state variable is introduced to obtain a more elaborated model for the noise dynamics. Approximate Bayesian inference in the SLDM is carried out by a bank of extended Kalman filters, whose outputs are combined according to the a posteriori probability of the individual state models. Experimental results on the AURORA2 database show improved recognition accuracy.}}, author = {{Windmann, Stefan and Haeb-Umbach, Reinhold}}, booktitle = {{IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP 2008)}}, keywords = {{a posteriori probability, AURORA2 database, Bayesian inference, Bayes methods, channel bank filters, extended Kalman filter banks, hidden noise state variable, Kalman filters, noise dynamics, speech enhancement, speech feature enhancement, speech feature trajectory, switching linear dynamical model approach}}, pages = {{4409--4412}}, title = {{{Modeling the dynamics of speech and noise for speech feature enhancement in ASR}}}, doi = {{10.1109/ICASSP.2008.4518633}}, year = {{2008}}, } @inproceedings{39403, abstract = {{The Unified Modeling Language (UML) has received wide acceptance as a standard language in the field of software specification by means of different diagram types. In a recent version of UML, the textual Object Constraint Language (OCL) was introduced to support specification of constraints for UML models. But OCL currently does not provide sufficient means to specify constraints over the dynamic behavior of a model. This article presents an OCL extension that is consistent with current OCL and enables modelers to specify state-related time-bounded constraints. We consider the case study of a flexible manufacturing system and identify typical real-time constraints. The constraints are presented in our temporal OCL extension as well as in temporal logic formulae. For general application, we define a semantics of our OCL extension by means of a time-bounded temporal logic based on Computational Tree Logic (CTL).}}, author = {{Flake, Stephan and Müller, Wolfgang}}, booktitle = {{Proceedings of HICSS-35}}, isbn = {{0-7695-1435-9}}, keywords = {{Unified modeling language, Logic, Formal verification, Real time systems, Programming profession, Vehicle dynamics, Software standards, Flexible manufacturing systems, Electronics industry, Protocols}}, location = {{Big Island, HI, USA }}, title = {{{Specification of Real-Time Properties for UML Models}}}, doi = {{10.1109/HICSS.2002.994469}}, year = {{2002}}, }