@inproceedings{4563, abstract = {{Routing is a challenging problem for wireless ad hoc networks, especially when the nodes are mobile and spread so widely that in most cases multiple hops are needed to route a message from one node to another. In fact, it is known that any online routing protocol has a poor performance in the worst case, in a sense that there is a distribution of nodes resulting in bad routing paths for that protocol, even if the nodes know their geographic positions and the geographic position of the destination of a message is known. The reason for that is that radio holes in the ad hoc network may require messages to take long detours in order to get to a destination, which are hard to find in an online fashion. In this paper, we assume that the wireless ad hoc network can make limited use of long-range links provided by a global communication infrastructure like a cellular infrastructure or a satellite in order to compute an abstraction of the wireless ad hoc network that allows the messages to be sent along near-shortest paths in the ad hoc network. We present distributed algorithms that compute an abstraction of the ad hoc network in $\mathcal{O}\left(\log ^2 n\right)$ time using long-range links, which results in $c$-competitive routing paths between any two nodes of the ad hoc network for some constant $c$ if the convex hulls of the radio holes do not intersect. We also show that the storage needed for the abstraction just depends on the number and size of the radio holes in the wireless ad hoc network and is independent on the total number of nodes, and this information just has to be known to a few nodes for the routing to work. }}, author = {{Jung, Daniel and Kolb, Christina and Scheideler, Christian and Sundermeier, Jannik}}, booktitle = {{Proceedings of the 14th International Symposium on Algorithms and Experiments for Wireless Networks (ALGOSENSORS) }}, keywords = {{greedy routing, ad hoc networks, convex hulls, c-competitiveness}}, location = {{Helsinki}}, publisher = {{Springer}}, title = {{{Competitive Routing in Hybrid Communication Networks}}}, year = {{2018}}, } @inproceedings{4565, author = {{Jung, Daniel and Kolb, Christina and Scheideler, Christian and Sundermeier, Jannik}}, booktitle = {{Proceedings of the 30th on Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, isbn = {{9781450357999}}, location = {{Wien}}, publisher = {{ACM Press}}, title = {{{Brief Announcement: Competitive Routing in Hybrid Communication Networks}}}, doi = {{10.1145/3210377.3210663}}, year = {{2018}}, } @misc{4576, author = {{Sprenger, Alexander and Hellebrand, Sybille}}, keywords = {{WORKSHOP}}, publisher = {{30. Workshop "Testmethoden und Zuverlässigkeit von Schaltungen und Systemen" (TuZ'18)}}, title = {{{Stochastische Kompaktierung für den Hochgeschwindigkeitstest}}}, year = {{2018}}, } @inproceedings{4579, abstract = {{Semi-guided waves confined in dielectric slab waveguides are being considered for oblique angles of propagation. If the waves encounter a linear discontinuity of (mostly) arbitrary shape and extension, a variant of Snell's law applies, separately for each pair of incoming and outgoing modes. Depending on the effective indices involved, and on the angle of incidence, power transfer to specific outgoing waves can be allowed or forbidden. In particular, critical angles of incidence can be identified, beyond which any power transfer to non-guided waves is forbidden, i.e. all radiative losses are suppressed. In that case the input power is carried away from the discontinuity exclusively by reflected semi-guided waves in the input slab, or by semi-guided waves that are transmitted into other outgoing slab waveguides. Vectorial equations on a 2-D cross sectional domain apply. These are formally identical to the equations that govern the eigenmodes of 3-D channel waveguides. Here, however, these need to be solved not as an eigenvalue problem, but as an inhomogeneous problem with a right-hand-side that is given by the incoming semi-guided wave, and subject to transparent boundary conditions. The equations resemble a standard 2-D Helmholtz problem, with an effective permittivity in place of the actual relative permittivity. Depending on the properties of the incoming wave, including the angle of incidence, this effective permittivity can become locally negative, causing the suppression of propagating outgoing waves. A series of high-contrast example configurations are discussed, where these effects lead to - in some respects - quite surprising transmission characteristics.}}, author = {{Hammer, Manfred and Ebers, Lena and Hildebrandt, Andre and Alhaddad, Samer and Förstner, Jens}}, booktitle = {{2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET)}}, isbn = {{9781538654385}}, keywords = {{tet_topic_waveguides}}, publisher = {{IEEE}}, title = {{{Oblique Semi-Guided Waves: 2-D Integrated Photonics with Negative Effective Permittivity}}}, doi = {{10.1109/mmet.2018.8460455}}, year = {{2018}}, } @inproceedings{4581, author = {{Grynko, Yevgen and Förstner, Jens}}, booktitle = {{2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET)}}, isbn = {{9781538654385}}, keywords = {{tet_topic_numerics, tet_topic_shg}}, publisher = {{IEEE}}, title = {{{Application of the Discontinuous Galerkin Time Domain Method in Nonlinear Nanoplasmonics}}}, doi = {{10.1109/mmet.2018.8460261}}, year = {{2018}}, } @article{4831, abstract = {{Polarization of light is essential for some living organisms and many optical applications. Here, an orientation dependent polarization conversion effect is reported for light reflected from diamond‐structure‐based photonic crystals (D‐structure) inside the scales of a beetle, the weevil Entimus imperialis. When linearly polarized light propagates along its 〈100〉 directions, the D‐structure behaves analogous to a half‐wave plate in reflection but based on a different mechanism. The D‐structure rotates the polarization direction of linearly polarized light, and reflects circularly polarized light of both handednesses without changing it. This polarization effect is different from circular dichroism occurring in chiral biological photonic structures discovered before. The structural origin of this effect is symmetry breaking inside D‐structure's unit cell. This finding demonstrates that natural photonic structures can exploit multiple functionalities inherent to the design principles of their structural organization. Aiming at transferring the inherent polarization effect of the biological D‐structure to technically realizable materials, three simplified biomimetic structural models are derived and it is theoretically demonstrated that they retain the effect. Out of these structures, functioning woodpile structure prototypes are fabricated.}}, author = {{Wu, Xia and Rodríguez-Gallegos, Fernando L. and Heep, Marie-Christin and Schwind, Bertram and Li, Guixin and Fabritius, Helge-Otto and von Freymann, Georg and Förstner, Jens}}, issn = {{2195-1071}}, journal = {{Advanced Optical Materials}}, keywords = {{tet_topic_phc, tet_topic_bio}}, number = {{24}}, pages = {{1800635}}, publisher = {{Wiley}}, title = {{{Polarization Conversion Effect in Biological and Synthetic Photonic Diamond Structures}}}, doi = {{10.1002/adom.201800635}}, volume = {{6}}, year = {{2018}}, } @inproceedings{7570, author = {{Meyer auf der Heide, Friedhelm and Schaefer, Johannes Sebastian}}, booktitle = {{Proceedings of the 30th on Symposium on Parallelism in Algorithms and Architectures - SPAA '18}}, isbn = {{9781450357999}}, location = {{Vienna}}, publisher = {{ACM Press}}, title = {{{Brief Announcement: Communication in Systems of Home Based Mobile Agents}}}, doi = {{10.1145/3210377.3210662}}, year = {{2018}}, } @inbook{8573, author = {{Liebendörfer, Michael}}, booktitle = {{Beiträge zum Mathematikunterricht 2018}}, editor = {{Didaktik der Mathematik der Universität Paderborn, Fachgruppe}}, pages = {{1171--1174}}, publisher = {{WTM-Verlag}}, title = {{{Psychologische Grundbedürfnisse im frühen Mathematikstudium}}}, year = {{2018}}, } @inbook{8574, author = {{Liebendörfer, Michael and Kuklinski, Christiane and Hochmuth, Reinhard}}, booktitle = {{Beiträge zum Mathematikunterricht 2018}}, editor = {{Didaktik der Mathematik der Universität Paderborn, Fachgruppe}}, pages = {{1175--1178}}, publisher = {{WTM-Verlag}}, title = {{{Auswirkungen von innovativen Vorlesungen für Lehramtsstudierende in der Studieneingangsphase}}}, year = {{2018}}, } @book{8576, author = {{Liebendörfer, Michael}}, isbn = {{978-3-658-22506-3 978-3-658-22507-0}}, publisher = {{Springer Fachmedien Wiesbaden}}, title = {{{Motivationsentwicklung im Mathematikstudium}}}, doi = {{10.1007/978-3-658-22507-0}}, year = {{2018}}, } @inproceedings{8750, abstract = {{In this article we propose a descent method for equality and inequality constrained multiobjective optimization problems (MOPs) which generalizes the steepest descent method for unconstrained MOPs by Fliege and Svaiter to constrained problems by using two active set strategies. Under some regularity assumptions on the problem, we show that accumulation points of our descent method satisfy a necessary condition for local Pareto optimality. Finally, we show the typical behavior of our method in a numerical example.}}, author = {{Gebken, Bennet and Peitz, Sebastian and Dellnitz, Michael}}, booktitle = {{Numerical and Evolutionary Optimization – NEO 2017}}, isbn = {{9783319961033}}, issn = {{1860-949X}}, title = {{{A Descent Method for Equality and Inequality Constrained Multiobjective Optimization Problems}}}, doi = {{10.1007/978-3-319-96104-0_2}}, year = {{2018}}, } @article{8751, abstract = {{Multiobjective optimization plays an increasingly important role in modern applications, where several criteria are often of equal importance. The task in multiobjective optimization and multiobjective optimal control is therefore to compute the set of optimal compromises (the Pareto set) between the conflicting objectives. The advances in algorithms and the increasing interest in Pareto-optimal solutions have led to a wide range of new applications related to optimal and feedback control, which results in new challenges such as expensive models or real-time applicability. Since the Pareto set generally consists of an infinite number of solutions, the computational effort can quickly become challenging, which is particularly problematic when the objectives are costly to evaluate or when a solution has to be presented very quickly. This article gives an overview of recent developments in accelerating multiobjective optimal control for complex problems where either PDE constraints are present or where a feedback behavior has to be achieved. In the first case, surrogate models yield significant speed-ups. Besides classical meta-modeling techniques for multiobjective optimization, a promising alternative for control problems is to introduce a surrogate model for the system dynamics. In the case of real-time requirements, various promising model predictive control approaches have been proposed, using either fast online solvers or offline-online decomposition. We also briefly comment on dimension reduction in many-objective optimization problems as another technique for reducing the numerical effort.}}, author = {{Peitz, Sebastian and Dellnitz, Michael}}, issn = {{2297-8747}}, journal = {{Mathematical and Computational Applications}}, number = {{2}}, title = {{{A Survey of Recent Trends in Multiobjective Optimal Control—Surrogate Models, Feedback Control and Objective Reduction}}}, doi = {{10.3390/mca23020030}}, volume = {{23}}, year = {{2018}}, } @inbook{8754, abstract = {{In this chapter, we combine a global, derivative-free subdivision algorithm for multiobjective optimization problems with a posteriori error estimates for reduced-order models based on Proper Orthogonal Decomposition in order to efficiently solve multiobjective optimization problems governed by partial differential equations. An error bound for a semilinear heat equation is developed in such a way that the errors in the conflicting objectives can be estimated individually. The resulting algorithm constructs a library of locally valid reduced-order models online using a Greedy (worst-first) search. Using this approach, the number of evaluations of the full-order model can be reduced by a factor of more than 1000.}}, author = {{Beermann, Dennis and Dellnitz, Michael and Peitz, Sebastian and Volkwein, Stefan}}, booktitle = {{Reduced-Order Modeling (ROM) for Simulation and Optimization}}, isbn = {{9783319753188}}, pages = {{47--72}}, title = {{{Set-Oriented Multiobjective Optimal Control of PDEs Using Proper Orthogonal Decomposition}}}, doi = {{10.1007/978-3-319-75319-5_3}}, year = {{2018}}, } @article{8755, abstract = {{Dynamic mode decomposition (DMD) is a recently developed tool for the analysis of the behavior of complex dynamical systems. In this paper, we will propose an extension of DMD that exploits low-rank tensor decompositions of potentially high-dimensional data sets to compute the corresponding DMD modes and eigenvalues. The goal is to reduce the computational complexity and also the amount of memory required to store the data in order to mitigate the curse of dimensionality. The efficiency of these tensor-based methods will be illustrated with the aid of several different fluid dynamics problems such as the von Kármán vortex street and the simulation of two merging vortices.}}, author = {{Klus, Stefan and Gelß, Patrick and Peitz, Sebastian and Schütte, Christof}}, issn = {{0951-7715}}, journal = {{Nonlinearity}}, number = {{7}}, pages = {{3359--3380}}, title = {{{Tensor-based dynamic mode decomposition}}}, doi = {{10.1088/1361-6544/aabc8f}}, volume = {{31}}, year = {{2018}}, } @inproceedings{8757, abstract = {{A framework for set‐oriented multiobjective optimal control of partial differential equations using reduced order modeling has recently been developed [1]. Following concepts from localized reduced bases methods, error estimators for the reduced cost functionals are utilized to construct a library of locally valid reduced order models. This way, a superset of the Pareto set can efficiently be computed while maintaining a prescribed error bound. In this article, this algorithm is applied to a problem with non‐smooth objective functionals. Using an academic example, we show that the extension to non‐smooth problems can be realized in a straightforward manner. We then discuss the implications on the numerical results.}}, author = {{Beermann, Dennis and Dellnitz, Michael and Peitz, Sebastian and Volkwein, Stefan}}, booktitle = {{PAMM}}, issn = {{1617-7061}}, pages = {{51--54}}, title = {{{POD-based multiobjective optimal control of PDEs with non-smooth objectives}}}, doi = {{10.1002/pamm.201710015}}, year = {{2018}}, } @misc{8844, author = {{Jovanovikj, Ivan and Güldali, Baris}}, title = {{{Presentation: Who Guards the Guards? On the Validation of Test Case Migration}}}, year = {{2018}}, } @article{9606, author = {{Liu, Jia and Jager, Tibor and Kakvi, Saqib and Warinschi, Bogdan}}, issn = {{0925-1022}}, journal = {{Designs, Codes and Cryptography}}, pages = {{2549--2586}}, title = {{{How to build time-lock encryption}}}, doi = {{10.1007/s10623-018-0461-x}}, year = {{2018}}, } @article{4165, abstract = {{Metal nanoparticles host localized plasmon excitations that allow the manipulation of optical fields at the nanoscale. Despite the availability of several techniques for imaging plasmons, direct access into the symmetries of these excitations remains elusive, thus hindering progress in the development of applications. Here, we present a combination of angle-, polarization-, and space-resolved cathodoluminescence spectroscopy methods to selectively access the symmetry and degeneracy of plasmonic states in lithographically fabricated gold nanoprisms. We experimentally reveal and spatially map degenerate states of multipole plasmon modes with nanometer spatial resolution and further provide recipes for resolving optically dark and out-of-plane modes. Full-wave simulations in conjunction with a simple tight-binding model explain the complex plasmon structure in these particles and reveal intriguing mode-symmetry phenomena. Our approach introduces systematics for a comprehensive symmetry characterization of plasmonic states in high-symmetry nanostructures.}}, author = {{Myroshnychenko, Viktor and Nishio, Natsuki and García de Abajo, F. Javier and Förstner, Jens and Yamamoto, Naoki}}, issn = {{1936-0851}}, journal = {{ACS Nano}}, keywords = {{tet_topic_plasmonics}}, number = {{8}}, pages = {{8436--8446}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Unveiling and Imaging Degenerate States in Plasmonic Nanoparticles with Nanometer Resolution}}}, doi = {{10.1021/acsnano.8b03926}}, volume = {{12}}, year = {{2018}}, } @inproceedings{4236, author = {{Wachsmuth, Henning and Stede, Manfred and El Baff, Roxanne and Al Khatib, Khalid and Skeppstedt, Maria and Stein, Benno}}, booktitle = {{Proceedings of the 27th International Conference on Computational Linguistics}}, keywords = {{argument}}, pages = {{3753--3765}}, title = {{{Argumentation Synthesis following Rhetorical Strategies}}}, year = {{2018}}, } @article{4324, abstract = {{We study the dependence of the intensity and linear polarization of light scattered by isolated particles with the compact irregular shape on their size using the discontinuous Galerkin time domain numerical method. The size parameter of particles varies in the range of X = 10 to 150, and the complex refractive index is m = 1.5 + 0i. Our results show that the backscattering negative polarization branch weakens monotonously, but does not disappear at large sizes, up to the geometrical optics regime, and can be simulated without accounting for wave effects. The intensity backscattering surge becomes narrower with increasing particle size. For X = 150, the surge width is several degrees.}}, author = {{Grynko, Yevgen and Shkuratov, Yuriy and Förstner, Jens}}, issn = {{0146-9592}}, journal = {{Optics Letters}}, keywords = {{tet_topic_scattering}}, number = {{15}}, pages = {{3562}}, publisher = {{The Optical Society}}, title = {{{Intensity surge and negative polarization of light from compact irregular particles}}}, doi = {{10.1364/ol.43.003562}}, volume = {{43}}, year = {{2018}}, }