@article{28196, abstract = {{We show that narrow trenches in a high-contrast silicon-photonics slab can act as lossless power dividers for semi-guided waves. Reflectance and transmittance can be easily configured by selecting the trench width. At sufficiently high angles of incidence, the devices are lossless, apart from material attenuation and scattering due to surface roughness. We numerically simulate a series of devices within the full 0-to-1-range of splitting ratios, for semi-guided plane wave incidence as well as for excitation by focused Gaussian wave bundles. Straightforward cascading of the trenches leads to concepts for 1×M-power dividers and a polarization beam splitter.}}, author = {{Hammer, Manfred and Ebers, Lena and Förstner, Jens}}, issn = {{2578-7519}}, journal = {{OSA Continuum}}, keywords = {{tet_topic_waveguide}}, number = {{12}}, pages = {{3081}}, title = {{{Configurable lossless broadband beam splitters for semi-guided waves in integrated silicon photonics}}}, doi = {{10.1364/osac.437549}}, volume = {{4}}, year = {{2021}}, } @techreport{33854, abstract = {{Macrodiversity is a key technique to increase the capacity of mobile networks. It can be realized using coordinated multipoint (CoMP), simultaneously connecting users to multiple overlapping cells. Selecting which users to serve by how many and which cells is NP-hard but needs to happen continuously in real time as users move and channel state changes. Existing approaches often require strict assumptions about or perfect knowledge of the underlying radio system, its resource allocation scheme, or user movements, none of which is readily available in practice. Instead, we propose three novel self-learning and self-adapting approaches using model-free deep reinforcement learning (DRL): DeepCoMP, DD-CoMP, and D3-CoMP. DeepCoMP leverages central observations and control of all users to select cells almost optimally. DD-CoMP and D3-CoMP use multi-agent DRL, which allows distributed, robust, and highly scalable coordination. All three approaches learn from experience and self-adapt to varying scenarios, reaching 2x higher Quality of Experience than other approaches. They have very few built-in assumptions and do not need prior system knowledge, making them more robust to change and better applicable in practice than existing approaches.}}, author = {{Schneider, Stefan Balthasar and Karl, Holger and Khalili, Ramin and Hecker, Artur}}, keywords = {{mobility management, coordinated multipoint, CoMP, cell selection, resource management, reinforcement learning, multi agent, MARL, self-learning, self-adaptation, QoE}}, title = {{{DeepCoMP: Coordinated Multipoint Using Multi-Agent Deep Reinforcement Learning}}}, year = {{2021}}, } @misc{35066, author = {{Süßmann, Johannes}}, title = {{{Mariemont – Modernismus und Erinnerung. Videographierter Vortrag für den 5. Belgientag des Belgienzentrums Paderborn ›Belgien – Pralle Kunst des Lebens‹ am 18. Mai 2021}}}, year = {{2021}}, } @article{21265, abstract = {{Fast-growing energy demand of the world makes the researchers focus on finding new energy sources or optimizing already-developed approaches. For an efficient use of solar and wind energy in an energy system, correct design and sizing of a power system is of high importance and improving or optimizing the process of data obtaining for this purpose leads to higher performance and lower cost per unit of energy. It is essential to have the most precise possible estimation of solar and wind energy potential and other local weather parameters in order to fully feed the demand and avoid extra costs. There are various methods for obtaining local data, such as local measurements, official organizational data, satellite obtained, and reanalysis data. In this paper, the Modern-Era Retrospective analysis for Research and Applications dataset version 2 (MERRA-2) dataset provided by NASA is introduced and its performance is evaluated by comparison to various locally measured datasets offered by meteorological institutions such as Meteonorm and Deutscher Wetterdienst (DWD, or Germany’s National Meteorological Service) around the world. After comparison, correlation coefficients from 0.95 to 0.99 are observed for monthly global horizontal irradiance values. In the case of air temperature, correlation coefficients of 0.99 and for wind speed from 0.81 to 0.99 are observed. High correlation with ground measurements and relatively low errors are confirmed, especially for irradiance and temperature values, that makes MERRA-2 a valuable dataset, considering its world coverage and availability.}}, author = {{Khatibi, Arash and Krauter, Stefan}}, issn = {{1996-1073}}, journal = {{Energies}}, keywords = {{Solar irradiance, MERRA 2, Meteonorm, DWD}}, number = {{4}}, publisher = {{MDPI}}, title = {{{Validation and Performance of Satellite Meteorological Dataset MERRA-2 for Solar and Wind Applications}}}, doi = {{10.3390/en14040882}}, volume = {{14}}, year = {{2021}}, } @article{26987, abstract = {{Optical metasurfaces are perfect candidates for the phase and amplitude modulation of light, featuring an excellent basis for holographic applications. In this work, we present a dual amplitude holographic scheme based on the photon sieve principle, which is then combined with a phase hologram by utilizing the Pancharatnam–Berry phase. We demonstrate that two types of apertures, rectangular and square shapes in a gold film filled with silicon nanoantennas are sufficient to create two amplitude holograms at two different wavelengths in the visible, multiplexed with an additional phase-only hologram. The nanoantennas are tailored to adjust the spectral transmittance of the apertures, enabling the wavelength sensitivity. The phase-only hologram is implemented by utilizing the anisotropic rectangular structure. Interestingly, such three holograms have quantitative mathematical correlations with each other. Thus, the flexibility of polarization and wavelength channels can be utilized with custom-tailored features to achieve such amplitude and phase holography simultaneously without sacrificing any space-bandwidth product. The present scheme has the potential to store different pieces of information which can be displayed separately by switching the wavelength or the polarization state of the reading light beam.}}, author = {{Frese, Daniel and Sain, Basudeb and Zhou, Hongqiang and Wang, Yongtian and Huang, Lingling and Zentgraf, Thomas}}, issn = {{2192-8614}}, journal = {{Nanophotonics}}, number = {{18}}, pages = {{4543--4550}}, publisher = {{De Gruyter}}, title = {{{A wavelength and polarization selective photon sieve for holographic applications}}}, doi = {{10.1515/nanoph-2021-0440}}, volume = {{10}}, year = {{2021}}, } @article{16294, abstract = {{Model predictive control is a prominent approach to construct a feedback control loop for dynamical systems. Due to real-time constraints, the major challenge in MPC is to solve model-based optimal control problems in a very short amount of time. For linear-quadratic problems, Bemporad et al. have proposed an explicit formulation where the underlying optimization problems are solved a priori in an offline phase. In this article, we present an extension of this concept in two significant ways. We consider nonlinear problems and - more importantly - problems with multiple conflicting objective functions. In the offline phase, we build a library of Pareto optimal solutions from which we then obtain a valid compromise solution in the online phase according to a decision maker's preference. Since the standard multi-parametric programming approach is no longer valid in this situation, we instead use interpolation between different entries of the library. To reduce the number of problems that have to be solved in the offline phase, we exploit symmetries in the dynamical system and the corresponding multiobjective optimal control problem. The results are verified using two different examples from autonomous driving.}}, author = {{Ober-Blöbaum, Sina and Peitz, Sebastian}}, journal = {{International Journal of Robust and Nonlinear Control}}, pages = {{380--403}}, title = {{{Explicit multiobjective model predictive control for nonlinear systems with symmetries}}}, doi = {{10.1002/rnc.5281}}, volume = {{31(2)}}, year = {{2021}}, } @misc{29549, abstract = {{Als Griechenland 1830 seine Unabhängigkeit erlangte, war das Land wirtschaftlich wenig entwickelt und von der Industrialisierung noch kaum berührt. Kredite für die Gründung oder den Ausbau von Unternehmen waren auf Grund des Kapitalmangels entweder unmöglich oder extrem teuer – ein für die wirtschaftliche Entwicklung ernst zu nehmendes Hemmnis. Das Land brauchte zur wirtschaftlichen Entwicklung also Investitionen aus dem Ausland. Jedoch hielten sich die europäischen Banken und Anleger mit solchen Investitionen vor den 1870er Jahren zurück. Warum diese Scheu der Kapitalanleger vor Griechenland, obwohl sie anderswo keineswegs vor risikoreichen Investitionen zurückschreckten, wenn nur entsprechend hohe Erträge lockten? Dieser Frage möchte der Beitrag anhand eines Beispiels nachgehen: der bayerisch-französischen Bankiersfamilie von Eichthal, die in den 1830er Jahren enge Geschäftsbeziehungen nach Griechenland aufbaute und zeitweilig sehr interessiert an Investitionen war – bevor das Bankhaus sich von diesen Plänen schließlich unverrichteter Dinge wieder abwandte. Das kulturelle Interesse an Griechenland überdauerte dagegen bis in die 1880er Jahre. Die Eichthals eignen sich hervorragend, um paradigmatisch zu untersuchen, auf welcher Grundlage und wie europäische Bankiers ihre Investitionsentscheidungen für oder gegen Griechenland trafen.}}, author = {{Schönhärl, Korinna}}, title = {{{Finanzielle Netze. Die bayerisch–französische Familienbank von Eichthal und ihre Investitionspläne in Griechenland in den 1830er Jahren/ Οικονομικά δίκτυα. Η βαυαρογαλλική οικογενειακή τράπεζα των Άιχταλ και τα επενδυτικά σχέδιά της στην Ελλάδα κατά τη δεκαετία του 1830}}}, year = {{2021}}, } @unpublished{22764, abstract = {{Robotics applications process large amounts of data in real-time and require compute platforms that provide high performance and energy-efficiency. FPGAs are well-suited for many of these applications, but there is a reluctance in the robotics community to use hardware acceleration due to increased design complexity and a lack of consistent programming models across the software/hardware boundary. In this paper we present ReconROS, a framework that integrates the widely-used robot operating system (ROS) with ReconOS, which features multithreaded programming of hardware and software threads for reconfigurable computers. This unique combination gives ROS2 developers the flexibility to transparently accelerate parts of their robotics applications in hardware. We elaborate on the architecture and the design flow for ReconROS and report on a set of experiments that underline the feasibility and flexibility of our approach.}}, author = {{Lienen, Christian and Platzner, Marco}}, booktitle = {{arXiv:2107.07208}}, pages = {{19}}, title = {{{Design of Distributed Reconfigurable Robotics Systems with ReconROS}}}, year = {{2021}}, } @inproceedings{25880, author = {{Hetkämper, Tim and Dreiling, Dmitrij and Claes, Leander and Henning, Bernd}}, booktitle = {{Fortschritte der Akustik - DAGA 2021}}, title = {{{Tomographie des Schallfelds von Ultraschallwandlern mittels Schlierentechnik}}}, year = {{2021}}, } @misc{31385, author = {{Hoffmann, Max}}, booktitle = {{Mathematische Semesterberichte}}, pages = {{295–297}}, title = {{{Rezension: Hendrik Kasten und Denis Vogel: Grundlagen der ebenen Geometrie – Eine zugängliche aber exakte Einführung in die ebene Geometrie}}}, doi = {{10.1007/s00591-021-00299-3}}, volume = {{68}}, year = {{2021}}, } @article{24955, author = {{Woitkowski, David and Rochell, Leonie and Bauer, Anna}}, issn = {{2469-9896}}, journal = {{Physical Review Physics Education Research}}, title = {{{German university students’ views of nature of science in the introductory phase}}}, doi = {{10.1103/physrevphyseducres.17.010118}}, year = {{2021}}, } @inproceedings{21726, author = {{Triebus, Marcel and Tröster, Thomas}}, booktitle = {{9th NRW Nano Conference - Innovations in Materials and Applications}}, location = {{Web}}, title = {{{HyOpt - Optimization-Based Development of Hybrid Materials}}}, year = {{2021}}, } @inproceedings{28988, author = {{Kirchhoff, Jonas}}, booktitle = {{The 1st Early Career Researchers Workshop Co-Located with ECSS 2021}}, location = {{Madrid}}, title = {{{Providing Decision Makers with Tailored Decision Support Systems}}}, year = {{2021}}, } @article{32558, abstract = {{With the rapid progress of technological development, self-efficacy in reference to digital devices (i.e., information and computer technology [ICT] self-efficacy) is an important driver that helps students to deal with technological problems and support their lifelong learning processes. Schools, peers, and home learning environments are important sources for the development of positive self-efficacy. Expanding on previous research, we investigated the associations between different aspects of the digital home learning environment and students’ ICT self-efficacy. The moderation effects of gender were also tested. A total of 651 children answered a questionnaire about different digital home learning environment dimensions and estimated their ICT self-efficacy using an adapted scale—Schwarzer and Jerusalem’s (1999) general self-efficacy scale. Using the structural equation modeling technique, a digital home learning environment containing six different qualities of parental support was investigated. Families’ cultural capital, parents’ attitudes toward the Internet, and shared Internet activities at home contributed positively to ICT self-efficacy. We observed small gender differences, with the moderation effect being nonsignificant. The results help researchers and practitioners to understand how different dimensions of the digital home learning environment support ICT self-efficacy. We will discuss how parents can enhance the home learning environment and how teachers can integrate this knowledge into formal education.}}, author = {{Bonanati, Sabrina and Buhl, Heike M.}}, issn = {{1387-1579}}, journal = {{Learning Environments Research}}, keywords = {{Digital media use, Gender, Home learning environment, ICT self-efcacy, Motivation, Parental involvement}}, number = {{2}}, pages = {{485--505}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{The digital home learning environment and its relation to children’s ICT self-efficacy}}}, doi = {{10.1007/s10984-021-09377-8}}, volume = {{25}}, year = {{2021}}, } @article{32560, abstract = {{Several methods are available to answer questions regarding similarity and accuracy, each of which has specific properties and limitations. This study focuses on the Latent Congruence Model (LCM; Cheung, 2009), because of its capacity to deal with cross-informant measurement invariance issues. Until now, no cross-national applications of LCM are present in the literature, perhaps because of the difficulty to deal with both cross-national and cross-informant measurement issues implied by those models. This study presents a step-by-step procedure to apply LCM to dyadic cross-national research designs controlling for both cross-national and cross-informant measurement invariance. An illustrative example on parent–child support exchanges in Italy and Germany is provided. Findings help to show the different possible scenarios of partial invariance, and a discussion related to how to deal with those scenarios is provided. Future perspectives in the study of parent–child similarity and accuracy in cross-national research will be discussed.}}, author = {{Tagliabue, Semira and Zambelli, Michela and Sorgente, Angela and Sommer, Sabrina and Hoellger, Christian and Buhl, Heike M. and Lanz, Margherita}}, issn = {{1664-1078}}, journal = {{Frontiers in Psychology}}, keywords = {{latent congruence model, measurement invariance, similarity, accuracy, cross-national, cross-informant, parent-child relationship, support exchanges}}, publisher = {{Frontiers Media SA}}, title = {{{Latent Congruence Model to Investigate Similarity and Accuracy in Family Members' Perception: The Challenge of Cross-National and Cross-Informant Measurement (Non)Invariance}}}, doi = {{10.3389/fpsyg.2021.672383}}, volume = {{12}}, year = {{2021}}, } @article{32561, abstract = {{This investigation concentrates on the association of intergenerational value similarity and adult children’s and parents’subjective well-being, on the linkage between relationship quality and subjective well-being. Mediation effects of the relationship quality on the associations between value similarity and subjective well-being were focused. The sample consisted of 600 adult German children (53.8% women) and their parents. Dyadic correlations were constructed to determine the value similarity. In this study, the general value orientation and the family values were objects of research. We measured the subjective well-being with the Satisfaction with Life Scale and we used the Network of Relationships Inventory (NRI) to measure the relationship quality. Associations between subjective well-being and value similarity, and between subjective well-being and relationship quality, as well as mediation effects, were found. All effects depend on gender and perspective.}}, author = {{Hoellger, Christian and Sommer, Sabrina and Buhl, Heike M.}}, issn = {{0192-513X}}, journal = {{Journal of Family Issues}}, keywords = {{adult child–parent dyads, relationship quality, life satisfaction, parent–child relationship, intergenerational stake hypothesis, mediation analyses}}, publisher = {{SAGE Publications}}, title = {{{Intergenerational Value Similarity and Subjective Well-Being}}}, doi = {{10.1177/0192513x211054470}}, year = {{2021}}, } @inproceedings{23758, author = {{Peeters, Hendrik and Habig, Sebastian and Fechner, Sabine}}, booktitle = {{Naturwissenschaftlicher Unterricht und Lehrerbildung im Umbruch?}}, editor = {{Habig, Sebastian}}, keywords = {{digitale Medien}}, pages = {{613--616}}, title = {{{Augmented Reality als Experimentierhilfe bei Beobachtung und Deutung}}}, volume = {{41}}, year = {{2021}}, } @phdthesis{21502, abstract = {{Die vollständige Beschreibung fluiddynamischer und akustischer Vorgänge setzt voraus, dass die Eigenschaften des Fluids hinlänglich bekannt sind.Während Fluidkenngrößen, wie etwa die Schallgeschwindigkeit oder die Scherviskosität, für viele Flüssigkeiten über weite Bereiche des thermodynamischen Zustandsraums bekannt sind, existieren für die Volumenviskosität nur eine geringe Anzahl Messdaten.In dieser Arbeit wird daher ein Messverfahren zur selektiven Bestimmung der Volumenviskosität von Flüssigkeiten, basierend auf der Absorption von Ultraschallwellen, entwickelt und realisiert.Schwerpunkte bilden dabei der simulationsgestützte Entwurf von Algorithmen zur Auswertung der Messsignale sowie die Analyse und Weiterentwicklung einer Messanordnung, basierend auf dem Puls-Echo-Verfahren. Neben der Absorption im Fluid treten dabei weitere Effekte (zum Beispiel Beugung oder unvollständige Reflexion) auf, die das akustische Signal schwächen oder anderweitig beeinflussen. Die Entwicklung von Verfahren zur Trennung dieser Effekte von der akustischen Absorption bildet daher einen weiteren Schwerpunkt dieser Arbeit.Abschließend wird die Volumenviskosität aus der gemessenen akustischen Absorption für unterschiedliche Fluide in verschiedenen thermodynamischen Zuständen unter Zuhilfenahme anderer bekannter Fluidkenngrößen bestimmt sowie eine Unsicherheitsbetrachtung durchgeführt.}}, author = {{Claes, Leander}}, pages = {{223}}, publisher = {{Universiät Paderborn}}, title = {{{Messverfahren für die akustische Absorption in reinen Fluiden zur Bestimmung der Volumenviskosität}}}, doi = {{10.17619/UNIPB/1-1104}}, year = {{2021}}, } @article{33278, abstract = {{The kinetic Brownian motion on the sphere bundle of a Riemannian manifold M is a stochastic process that models a random perturbation of the geodesic flow. If M is an orientable compact constantly curved surface, we show that in the limit of infinitely large perturbation the L2-spectrum of the infinitesimal generator of a time-rescaled version of the process converges to the Laplace spectrum of the base manifold.}}, author = {{Kolb, Martin and Weich, Tobias and Wolf, Lasse}}, journal = {{Annales Henri Poincaré }}, number = {{4}}, pages = {{1283--1296}}, publisher = {{Springer Science + Business Media}}, title = {{{Spectral Asymptotics for Kinetic Brownian Motion on Surfaces of Constant Curvature}}}, volume = {{23}}, year = {{2021}}, } @unpublished{32099, author = {{Weich, Tobias and Budde, Julia}}, booktitle = {{arXiv:2103.02968v1}}, title = {{{Wave Front Sets of Nilpotent Lie Group Representations}}}, year = {{2021}}, }