@inbook{33466, abstract = {{We review our results of numerical simulations of light scattering from different systems of densely packed irregular particles. We consider spherical clusters, thick layers and monolayers with realistic topologies and dimensions much larger than the wavelength of light. The maximum bulk packing density of clusters is 0.5. A numerically exact solution of the electromagnetic problem is obtained using the Discontinuous Galerkin Time Domain method and with application of high- performance computing. We show that high packing density causes light localization in such structures which makes an impact on the opposition phenomena: backscattering intensity surge and negative linear polarization feature. Diffuse multiple scattering is significantly reduced in the case of non-absorbing particles and near-field interaction results in a percolation-like light transport determined by the topology of the medium. With this the negative polarization feature caused by single scattering gets enhanced if compared to lower density samples. We also confirm coherent double scattering mechanism of negative polarization for light scattered from dense absorbing slabs. In this case convergent result for the scattering angle polarization dependency at backscattering can be obtained for a layer of just a few tens of particles if they are larger than the wavelength.}}, author = {{Grynko, Yevgen and Shkuratov, Yuriy and Alhaddad, Samer and Förstner, Jens}}, booktitle = {{Springer Series in Light Scattering - Volume 8: Light Polarization and Multiple Scattering in Turbid Media}}, editor = {{Kokhanovsky, Alexander}}, isbn = {{9783031102974}}, issn = {{2509-2790}}, keywords = {{tet_topic_scattering}}, publisher = {{Springer International Publishing}}, title = {{{Light Scattering by Large Densely Packed Clusters of Particles}}}, doi = {{10.1007/978-3-031-10298-1_4}}, volume = {{8}}, year = {{2022}}, } @inproceedings{36335, abstract = {{Transformation of Fe- and Cu-rich primary phase particles was studied in an Al-Li-based alloy prepared by twin-roll casting. Thin foils for combined STEM and SEM experiments were prepared by electrolytic twin-jet polishing. They were in-situ heated in a TEM heating stage and observed at 200 kV in the JEOL JEM 2200FS electron microscope equipped with STEM HAADF and BF detectors and SEM BSE and SE detectors working both in composition and topographic modes. The resulting structures were combined with EDS mapping performed directly in the heating holder. Dissolution and transformation of Cu- and Fe-rich particles occur above 500 °C. EDS maps acquired on the foil cooled down to room temperature show that Cu and Fe are both still present in newly formed particles, most likely indicating the presence of the Al7Cu2Fe phase.}}, author = {{CIESLAR, Miroslav and KŘIVSKÁ, Barbora and KRÁLÍK, Rostislav and BAJTOŠOVÁ, Lucia and Grydin, Olexandr and STOLBCHENKO, Mykhailo and Schaper, Mirko}}, booktitle = {{METAL 2022 Conference Proeedings}}, issn = {{2694-9296}}, keywords = {{Al-Li-based alloy, in-situ TEM, homogenization, phase transformation}}, location = {{Brno}}, publisher = {{TANGER Ltd.}}, title = {{{HOMOGENIZATION OF TWIN-ROLL CAST Al-Li-BASED ALLOY STUDIED BY IN-SITU ELECTRON MICROSCOPY}}}, doi = {{10.37904/metal.2022.4438}}, year = {{2022}}, } @techreport{36413, author = {{Becker, Rieke and Lauert, Markus and Fischer, Jessica and Kirchhoff, Hannah and Kornbach, Alina and Januschewski, Katharina}}, title = {{{Tagungsbericht: Unverfügbarkeit – Widmung – Latenz: Das Heilige in der Kultur. Interdisziplinäre Tagung vom 16. bis 18. November 2021 an der Universität Paderborn}}}, 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}}, } @inproceedings{36473, abstract = {{Destructive micrograph analysis (MA) is the standard method for the assessment of clinched joints. However, during the joint preparation for the MA, geometric features of the joint can change due to elastic effects and closing cracks. X-ray computed tomography (CT) is a promising alternative to investigate the joint non-destructively. However, if the material properties of similar joining partners are the same, the CT is not able to correctly resolve surfaces in the joint that are close to or pressing onto each other. These surfaces are relevant for the determination of characteristic dimensions such as neck thickness and undercut. By placing a thin, highly radiopaque tin layer between the joining partners, the interfacial area in the reconstructed volume can be highlighted. In this work, a method for the localisation of the tin layer inside the joint as well as threshold value procedures for the outer joint contour in cross section images are investigated. The measured characteristic dimensions are compared with measured values from MA of the same samples and of samples without tin layer. In addition, possible effects of the tin layer on the joining point characteristics as well as problems of the MA are discussed.}}, author = {{Busch, Matthias and Köhler, Daniel and Hausotte, Tino and Kupfer, Robert and Troschitz, Juliane and Gude, Maik }}, title = {{{Approach to Determine the Characteristic Dimensions of Clinched Joints by Industrial X-ray Computed Tomography}}}, year = {{2022}}, } @article{36524, abstract = {{How can Knowledge In/Equity be addressed in qualitative research by taking the idea of Open Science into account? Two projects from the Open Science Fellows Programme by Wikimedia Deutschland will be used to illustrate how Open Science practices can succeed in qualitative research, thereby reducing In/Equity. In this context, In/Equity is considered as a fair and equal representation of people, their knowledge and insights and comprehends questions about how epistemic, structural, institutional and personal biases generate and shape knowledge as guidance. Three questions guide this approach: firstly, what do we understand by In/Equity in the context of knowledge production in these projects? Secondly, who will be involved in knowledge generation and to what extent will they be valued or unvalued? Thirdly, how can data be made accessible for re-use to enable true participation and sharing?}}, author = {{Steinhardt, Isabel and Kruschick, Felicitas}}, issn = {{2367-7163}}, journal = {{Research Ideas and Outcomes}}, keywords = {{Open Science, Knowledge Equity, Qualitative Methods}}, pages = {{e86387}}, publisher = {{Pensoft Publishers}}, title = {{{Knowledge Equity and Open Science in qualitative research – Practical research considerations}}}, doi = {{10.3897/rio.8.e86387}}, volume = {{8}}, year = {{2022}}, } @article{36538, abstract = {{Der Beitrag beschäftigt sich mit dem Gebrauch von sogenannten Open Educational Resources (OER) innerhalb der deutschsprachigen Soziologie. OER sind Lehr-und Lernmaterialien, die öffent-lich und frei von Kosten zugänglich sind sowie unter einer offenen Lizenz stehen, die es erlaubt, das Material frei zu nutzen, zu vervielfältigen und zu bearbeiten. Um diese Form der Bereitstellung von Lehr-und Lernmaterial zu fördern, sind im deutschen Sprachraum in den letzten Jahren verschie-dene digitale Infrastrukturen entstanden, die an einzelnen Hochschulstandorten, aber auch hochschulübergreifend Lehrenden zur Verfügung stehen, um dort ihr Material zu veröffentlichen. Es wurden 37 dieser Repositorien untersucht. Darüber hinaus wurde auch die Videoplattform YouTube nach soziologischem Lehr-und Lernmaterial durchforstet. Der Beitrag stellt den Zeitverlauf und die Akteur:innen der OER-Veröffentlichungen dar. Anschließend soll mithilfe eines praxistheoretischen Vokabulars die Lehre innerhalb der Soziologie aufgeschlüsselt und ein möglicher Bezug zu den empirischen Ergebnissen hergestellt werden.}}, author = {{Hiebl, Johannes and Steinhardt, Isabel and Bigos, Michael}}, issn = {{2199-8825}}, journal = {{die hochschule}}, keywords = {{Soziologie, Praxistheorie, Repositorien, Open Educational Resources, OER}}, number = {{8}}, pages = {{379--394}}, title = {{{Die (Un-)Sichtbarkeit von (offenen) Bildungsmaterialien in der Soziologie}}}, doi = {{10.3278/HSL2227W}}, year = {{2022}}, } @inbook{36526, abstract = {{Der Beitrag geht der Frage nach, welchen Herausforderungen Lehrende durch die digitale Lehre im ersten Corona-Semester 2020 begegnet sind und welche Strategien sie für deren Bewältigung gewählt haben. Als Datengrundlage dienendazu sechs autoethnographische Stories, entstanden im Projekt AEDiL. Diese haben sich als wertvolles Material erwiesen, um unmittelbare Einblicke in das Lehrhandeln und die -planung zu erhalten und die weiterführende Analyse zu ermöglichen. Dabei offenbarte sich der gemeinsame Anspruch der studierenden-zentrierten Lehre als wiederkehrendes Muster. Die mehrstufige Analyse legt offen, wie Lehrpersonen mit den Themen Beziehungsaufbau, Schaffung eines (digitalen) Raums sowie Sicherheit für Studierende umgehen und sich daraus Handlungsmuster entwickeln.}}, author = {{Ternes, Doris and Bernhard, Nadine and Gewinner, Irina and Goller, Antje and Lohner, David and König, Karsten and Röwert, Ronny and Steinhardt, Isabel and Thielsch, Angelika}}, booktitle = {{Hochschulen in der Pandemie. Impulse für eine nachhaltige Entwicklung von Studium und Lehre}}, editor = {{Angenent, Holger and Petri, Jörg and Zimenkova, Tatiana}}, isbn = {{ 978-3-8376-5984-9}}, pages = {{400--414}}, publisher = {{transkript}}, title = {{{Dem eigenen Anspruch auf der Spur}}}, doi = {{10.5445/IR/1000145819 }}, year = {{2022}}, } @misc{47538, author = {{Lammer, Christina}}, keywords = {{Kathleen Vereecken, Kinder- und Jugendliteratur, Krieg, Belgien}}, publisher = {{www.kibum.de (Thomas Boyken und Jörn Brüggemann)}}, title = {{{Die Kraft der Bilder. Funktionen neuer Illustrationen bei Übersetzungen. Kathleen Vereecken – Alles komt goed, altijd (2018) | Alles wird gut, immer (2021)}}}, year = {{2022}}, } @inproceedings{27531, abstract = {{The Quantum Singular Value Transformation (QSVT) is a recent technique that gives a unified framework to describe most quantum algorithms discovered so far, and may lead to the development of novel quantum algorithms. In this paper we investigate the hardness of classically simulating the QSVT. A recent result by Chia, Gily\'en, Li, Lin, Tang and Wang (STOC 2020) showed that the QSVT can be efficiently "dequantized" for low-rank matrices, and discussed its implication to quantum machine learning. In this work, motivated by establishing the superiority of quantum algorithms for quantum chemistry and making progress on the quantum PCP conjecture, we focus on the other main class of matrices considered in applications of the QSVT, sparse matrices. We first show how to efficiently "dequantize", with arbitrarily small constant precision, the QSVT associated with a low-degree polynomial. We apply this technique to design classical algorithms that estimate, with constant precision, the singular values of a sparse matrix. We show in particular that a central computational problem considered by quantum algorithms for quantum chemistry (estimating the ground state energy of a local Hamiltonian when given, as an additional input, a state sufficiently close to the ground state) can be solved efficiently with constant precision on a classical computer. As a complementary result, we prove that with inverse-polynomial precision, the same problem becomes BQP-complete. This gives theoretical evidence for the superiority of quantum algorithms for chemistry, and strongly suggests that said superiority stems from the improved precision achievable in the quantum setting. We also discuss how this dequantization technique may help make progress on the central quantum PCP conjecture.}}, author = {{Gharibian, Sevag and Gall, François Le}}, booktitle = {{Proceedings of the 54th ACM Symposium on Theory of Computing (STOC)}}, pages = {{19--32}}, title = {{{Dequantizing the Quantum Singular Value Transformation: Hardness and Applications to Quantum Chemistry and the Quantum PCP Conjecture}}}, year = {{2022}}, } @article{47984, abstract = {{Recent analyses by polarization resolved second-harmonic (SH) microscopy have demonstrated that ferroelectric (FE) domain walls (DWs) can possess non-Ising wall characteristics and topological nature. These analyses rely on locally analyzing the properties, directionality, and magnitude of the second-order nonlinear tensor. However, when inspecting FE DWs with SH microscopy, a manifold of different effects may contribute to the observed signal difference between domains and DWs, i.e., far-field interference, Čerenkov-type phase-matching (CSHG), and changes in the aforementioned local nonlinear optical properties. They all might be present at the same time and, therefore, require careful interpretation and separation. In this work, we demonstrate how the particularly strong Čerenkov-type contrast can selectively be blocked using dark- and bright-field SH microscopy. Based on this approach, we show that other contrast mechanisms emerge that were previously overlayed by CSHG but can now be readily selected through the appropriate experimental geometry. Using the methods presented, we show that the strength of the CSHG contrast compared to the other mechanisms is approximately 22 times higher. This work lays the foundation for the in-depth analysis of FE DW topologies by SH microscopy.}}, author = {{Hegarty, Peter A. and Beccard, Henrik and Eng, Lukas M. and Rüsing, Michael}}, issn = {{0021-8979}}, journal = {{Journal of Applied Physics}}, keywords = {{General Physics and Astronomy}}, number = {{24}}, publisher = {{AIP Publishing}}, title = {{{Turn all the lights off: Bright- and dark-field second-harmonic microscopy to select contrast mechanisms for ferroelectric domain walls}}}, doi = {{10.1063/5.0094988}}, volume = {{131}}, year = {{2022}}, } @article{47989, abstract = {{Thin-film materials from μm thickness down to single-atomic-layered 2D materials play a central role in many novel electronic and optical applications. Coherent, nonlinear optical (NLO) μ-spectroscopy offers insight into the local thickness, stacking order, symmetry, or electronic and vibrational properties. Thin films and 2D materials are usually supported on multi-layered substrates leading to (multi-)reflections, interference, or phase jumps at interfaces during μ-spectroscopy, which all can make the interpretation of experiments particularly challenging. The disentanglement of the influence parameters can be achieved via rigorous theoretical analysis. In this work, we compare two self-developed modeling approaches, a semi-analytical and a fully vectorial model, to experiments carried out in thin-film geometry for two archetypal NLO processes, second-harmonic and third-harmonic generation. In particular, we demonstrate that thin-film interference and phase matching do heavily influence the signal strength. Furthermore, we work out key differences between three and four photon processes, such as the role of the Gouy-phase shift and the focal position. Last, we can show that a relatively simple semi-analytical model, despite its limitations, is able to accurately describe experiments at a significantly lower computational cost as compared to a full vectorial modeling. This study lays the groundwork for performing quantitative NLO μ-spectroscopy on thin films and 2D materials, as it identifies and quantifies the impact of the corresponding sample and setup parameters on the NLO signal, in order to distinguish them from genuine material properties.<}}, author = {{Amber, Zeeshan H. and Spychala, Kai J. and Eng, Lukas M. and Rüsing, Michael}}, issn = {{0021-8979}}, journal = {{Journal of Applied Physics}}, keywords = {{General Physics and Astronomy}}, number = {{21}}, publisher = {{AIP Publishing}}, title = {{{Nonlinear optical interactions in focused beams and nanosized structures}}}, doi = {{10.1063/5.0125926}}, volume = {{132}}, year = {{2022}}, } @article{47987, abstract = {{AbstractPure samples of colorless, air‐stable Ba(BO2OH) crystals were obtained from Ba(NO3)2 and H3BO3 under the ultra‐alkaline conditions of a KOH hydroflux at about 250 °C. The product formation depends on the water‐base molar ratio and the molar ratio of the starting materials. B(OH)3 acts as a proton donor (Brønsted acid) rather than a hydroxide acceptor (Lewis acid). Ba(BO2OH) crystallizes in the non‐centrosymmetric orthorhombic space group P212121. Hydrogen bonds connect the almost planar (BO2OH)2− anions, which are isostructural to HCO3−, into a syndiotactic chain. IR and Raman spectroscopy confirm the presence of hydroxide groups, which are involved in weak hydrogen bonds. Upon heating in air to about 450 °C, Ba(BO2OH) dehydrates to Ba2B2O5. Moreover, the non‐centrosymmetric structure of Ba(BO2OH) crystals was verified with power‐dependent confocal Second Harmonic Generation (SHG) microscopy indicating large conversion efficiencies in ambient atmosphere.}}, author = {{Li, Yuxi and Hegarty, Peter A. and Rüsing, Michael and Eng, Lukas M. and Ruck, Michael}}, issn = {{0044-2313}}, journal = {{Zeitschrift für anorganische und allgemeine Chemie}}, keywords = {{Inorganic Chemistry}}, number = {{21}}, publisher = {{Wiley}}, title = {{{Ba(BO2OH) – A Monoprotonated Monoborate from Hydroflux Showing Intense Second Harmonic Generation}}}, doi = {{10.1002/zaac.202200193}}, volume = {{648}}, year = {{2022}}, } @article{47988, abstract = {{Second harmonic (SH) microscopy represents a powerful tool for the investigation of crystalline systems, such as ferroelectrics and their domain walls (DWs). Under the condition of normal dispersion, i.e., the refractive index at the SH wavelength is larger as compared to the refractive index at the fundamental wavelength, n(2ω)>n(ω), bulk crystals will generate no SH signal. Should the bulk, however, contain DWs, an appreciable SH signal will still be detectable at the location of DWs stemming from the Čerenkov mechanism. In this work, we demonstrate both how SH signals are generated in bulk media and how the Čerenkov mechanism can be inhibited by using anomalous dispersion, i.e., n(ω)