@inproceedings{39390, author = {{Lange, Sven and Schroder, Dominik and Hedayat, Christian and Kuhn, Harald and Hilleringmann, Ulrich}}, booktitle = {{2021 22nd IEEE International Conference on Industrial Technology (ICIT)}}, publisher = {{IEEE}}, title = {{{Development of Methods for Coil-Based Localization by Magnetic Fields of Miniaturized Sensor Platforms in Bioprocesses}}}, doi = {{10.1109/icit46573.2021.9453609}}, year = {{2021}}, } @inbook{39394, author = {{Hilleringmann, Ulrich}}, booktitle = {{Nanostructured Zinc Oxide}}, isbn = {{9780128189009}}, publisher = {{Elsevier}}, title = {{{ZnO nanoparticle films as active layer for thin film transistors}}}, doi = {{10.1016/b978-0-12-818900-9.00013-9}}, year = {{2021}}, } @inproceedings{39396, author = {{Reker, Julia and Meyers, Thorsten and Vidor, Fabio F. and Joubert, Trudi-Heleen and Hilleringmann, Ulrich}}, booktitle = {{2021 Smart Systems Integration (SSI)}}, publisher = {{IEEE}}, title = {{{Complementary Inverter Circuits on Flexible Substrates}}}, doi = {{10.1109/ssi52265.2021.9466966}}, year = {{2021}}, } @inproceedings{39388, author = {{Reker, Julia and Meyers, Thorsten and Vidor, Fabio F. and Joubert, Trudi-Heleen and Hilleringmann, Ulrich}}, booktitle = {{2021 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS)}}, publisher = {{IEEE}}, title = {{{Integration Process for Self-aligned Sub-µm Thin-Film Transistors for Flexible Electronics}}}, doi = {{10.1109/fleps51544.2021.9469764}}, year = {{2021}}, } @misc{41288, pages = {{219--237}}, publisher = {{Stauffenburg}}, title = {{{Entwicklung einer konstruktionsbasierten französischen Grammatik: ein Arbeitsbericht zum Adjektiv- und Nominalbandd }}}, year = {{2021}}, } @book{41221, author = {{Siepmann, Dirk and Bürgel, Christoph}}, publisher = {{Amazon}}, title = {{{Grammatik des gesprochenen und geschriebenen Französisch: Das Nomen, }}}, volume = {{2}}, year = {{2021}}, } @misc{41269, pages = {{10--17}}, title = {{{Lexiko-grammatische Konstruktionen als Kern der Spracharbeit im Spanischunterricht, in: Hispanorama }}}, year = {{2021}}, } @misc{41267, pages = {{197--214}}, title = {{{Hörverstehenskompetenz: Spanischstudierende auf dem Prüfstand der Abituraufgaben}}}, year = {{2021}}, } @article{43148, author = {{Burgfeld-Meise, Bianca and Dehmel, Lukas}}, journal = {{Zeitschrift MedienPädagogik 42}}, pages = {{237--258}}, title = {{{Subjektwissen als Bildungsperspektive junger Erwachsener. Self-Tracking-Apps als digitale Optimierungstechnologien im Spannungsgefüge von Kontrolle und Selbstermächtigung}}}, doi = {{https://doi.org/10.21240/mpaed/42/2021.06.21.X}}, year = {{2021}}, } @article{43159, author = {{Damm, Jannis and Albiez, Matthias and Göddecke, Johannes and Meschut, Gerson and Ummenhofer, Thomas}}, issn = {{1619-1919}}, journal = {{adhäsion KLEBEN & DICHTEN}}, keywords = {{Polymers and Plastics, General Chemical Engineering, General Chemistry}}, number = {{9}}, pages = {{14--23}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Dämpfungseigenschaften geklebter Verbindungen - Potenzialanalyse und Klebstoffcharakterisierung}}}, doi = {{10.1007/s35145-021-0520-8}}, volume = {{65}}, year = {{2021}}, } @article{43179, abstract = {{Der Beitrag referiert Ergebnisse studentischer Forschungsprojekte, die sich mit den Folgen der Corona-Pandemie für die berufliche Bildung, für Berufswahl, Berufsvorbereitung und Ausbildung befasst haben. Die Ergebnisse zeigen nicht nur, wie unterschiedlich Berufe und Branchen von der Krise betroffen waren und damit umgegangen sind, sondern geben auch Hinweise auf nötige Weiterentwicklungen zur Verbesserung der Resilienz von Branchen, Berufen, Betrieben und ihrer Ausbildung.}}, author = {{Heisler, Dietmar}}, issn = {{00059536}}, journal = {{Berufsbildung. Zeitschrift für Theorie-Praxis-Dialog}}, keywords = {{Pandemie, Distanzlernen, Berufswahl, Ausbildung}}, publisher = {{wbv, Eusl}}, title = {{{Berufsausbildung in der Corona-Pandemie. Befunde studentischer Forschungsprojekte}}}, volume = {{192}}, year = {{2021}}, } @inbook{43182, author = {{Heisler, Dietmar and Reißland, Jens and Müller, Claudia and Rühr, Laura and Gröger, Simon}}, booktitle = {{Berufsbildung für nachhaltige Entwicklung. Die Modellversuche 2015-2019 auf dem Weg vom Projekt zur Struktur}}, editor = {{Melzig, Christian and Kuhlmeier, Werner and Kretschmer, Susanne}}, isbn = {{978-3-8474-2951-7}}, pages = {{299 -- 319}}, publisher = {{Barbara Budrich}}, title = {{{Das Analyseraster zu Merkmalen eines nachhaltigen Lernortes für betriebliche Ausbilderinnen und Ausbilder.}}}, year = {{2021}}, } @article{43178, abstract = {{Im Fokus steht das Problem der Durchlässigkeit von akademischer und beruflicher Bildung im Kontext aktueller Reformen. Die Erhöhung sozialer Mobilität als Reformziel gerät darin zugunsten der Attraktivitätssteigerung von Bildungsgängen aus dem Blick. Die geringe Durchlässigkeit von Bildungsgängen wird primär als Marketingproblem thematisiert.}}, author = {{Heisler, Dietmar}}, issn = {{00059536}}, journal = {{Berufsbildung. Zeitschrift für Theorie-Praxis-Dialog}}, keywords = {{allgemeine Bildung, berufliche BIldung, Durchlässigkeit im Bildungssystem}}, pages = {{6 -- 8}}, publisher = {{wbv, Eusl}}, title = {{{Berufsausbildung zwischen Attraktivitätsverlust und sozialer Ungleichheit Reformen für mehr Durchlässigkeit zwischen beruflicher und akademischer Bildung}}}, volume = {{191}}, year = {{2021}}, } @article{43465, abstract = {{We show the existence of ground states in the massless spin boson model without any infrared regularization. Our proof is non-perturbative and relies on a compactness argument. It works for arbitrary values of the coupling constant under the hypothesis that the second derivative of the ground state energy as a function of a constant external magnetic field is bounded.}}, author = {{Hasler, David and Hinrichs, Benjamin and Siebert, Oliver}}, issn = {{0010-3616}}, journal = {{Communications in Mathematical Physics}}, number = {{1}}, pages = {{419--433}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{On Existence of Ground States in the Spin Boson Model}}}, doi = {{10.1007/s00220-021-04185-w}}, volume = {{388}}, year = {{2021}}, } @misc{41089, author = {{Schroeter-Wittke, Harald}}, booktitle = {{Jahrbuch für Evangelische Kirchengeschichte des Rheinlandes}}, issn = {{0540–6226}}, pages = {{264--268}}, title = {{{Andrea Strübind / Klaas-Dieter Voß (Hgg.), Märtyrerbücher und ihre Bedeutung für konfessionelle Identität und Spiritualität in der Frühen Neuzeit. Interkonfessionelle und interdisziplinäre Beiträge zur Erforschung einer Buchgattung (SMHR 109), Tübingen 2019}}}, volume = {{70}}, year = {{2021}}, } @misc{41087, author = {{Schroeter-Wittke, Harald}}, booktitle = {{Jahrbuch für Evangelische Kirchengeschichte des Rheinlandes}}, issn = {{0540–6226}}, pages = {{245--249}}, title = {{{Stefan Alkier (Hg.), Sola Scriptura 1517-2017. Rekonstruktionen – Kritiken – Transformationen – Performanzen (CHTh 7), Tübingen 2019}}}, volume = {{70}}, year = {{2021}}, } @inproceedings{29138, author = {{Ahmed, Qazi Arbab}}, booktitle = {{2021 IFIP/IEEE 29th International Conference on Very Large Scale Integration (VLSI-SoC)}}, title = {{{Hardware Trojans in Reconfigurable Computing}}}, doi = {{10.1109/vlsi-soc53125.2021.9606974}}, year = {{2021}}, } @article{43389, author = {{Schulze, Johanna}}, journal = {{GGG-Magazin: DIE SCHULE für alle}}, pages = {{26 -- 27}}, title = {{{Einzelschulentwicklung gerecht und digital – Einblicke in die empirische Lage und Konsequenzen für die Praxis.}}}, volume = {{4}}, year = {{2021}}, } @book{43388, author = {{Schulze, Johanna}}, title = {{{Medienkonzepte zur chancengerechten Schulentwicklung. Fallstudien an Schulen mit besonders herausfordernden Schüler*innenkompositionen.}}}, doi = {{10.1007/978-3-658-34416-0}}, year = {{2021}}, } @article{26889, author = {{Luo, Kai Hong and Santandrea, Matteo and Stefszky, Michael and Sperling, Jan and Massaro, Marcello and Ferreri, Alessandro and Sharapova, Polina and Herrmann, Harald and Silberhorn, Christine}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, title = {{{Quantum optical coherence: From linear to nonlinear interferometers}}}, doi = {{10.1103/physreva.104.043707}}, year = {{2021}}, } @article{26283, author = {{Lüders, Carolin and Pukrop, Matthias and Rozas, Elena and Schneider, Christian and Höfling, Sven and Sperling, Jan and Schumacher, Stefan and Aßmann, Marc}}, issn = {{2691-3399}}, journal = {{PRX Quantum}}, title = {{{Quantifying Quantum Coherence in Polariton Condensates}}}, doi = {{10.1103/prxquantum.2.030320}}, year = {{2021}}, } @article{26284, author = {{Bagrets, Dmitry and Kim, Kun Woo and Barkhofen, Sonja and De, Syamsundar and Sperling, Jan and Silberhorn, Christine and Altland, Alexander and Micklitz, Tobias}}, issn = {{2643-1564}}, journal = {{Physical Review Research}}, title = {{{Probing the topological Anderson transition with quantum walks}}}, doi = {{10.1103/physrevresearch.3.023183}}, year = {{2021}}, } @article{21362, author = {{Xue, Yan and Chestnov, Igor and Sedov, Evgeny and Kiktenko, Evgeniy and Fedorov, Aleksey K. and Schumacher, Stefan and Ma, Xuekai and Kavokin, Alexey}}, issn = {{2643-1564}}, journal = {{Physical Review Research}}, number = {{1}}, title = {{{Split-ring polariton condensates as macroscopic two-level quantum systems}}}, doi = {{10.1103/physrevresearch.3.013099}}, volume = {{3}}, year = {{2021}}, } @article{29747, author = {{Jurgen von Bardeleben, Hans and Cantin, Jean-Louis and Gerstmann, Uwe and Schmidt, Wolf Gero and Biktagirov, Timur}}, issn = {{1530-6984}}, journal = {{Nano Letters}}, keywords = {{Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}}, number = {{19}}, pages = {{8119--8125}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Spin Polarization, Electron–Phonon Coupling, and Zero-Phonon Line of the NV Center in 3C-SiC}}}, doi = {{10.1021/acs.nanolett.1c02564}}, volume = {{21}}, year = {{2021}}, } @article{29748, author = {{Slawig, Diana and Gruschwitz, Markus and Gerstmann, Uwe and Rauls, Eva and Tegenkamp, Christoph}}, issn = {{1932-7447}}, journal = {{The Journal of Physical Chemistry C}}, keywords = {{Surfaces, Coatings and Films, Physical and Theoretical Chemistry, General Energy, Electronic, Optical and Magnetic Materials}}, number = {{36}}, pages = {{20087--20093}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Adsorption and Reaction of PbPc on Hydrogenated Epitaxial Graphene}}}, doi = {{10.1021/acs.jpcc.1c06320}}, volume = {{125}}, year = {{2021}}, } @article{40250, author = {{Jain, Mitisha and Gerstmann, Uwe and Schmidt, Wolf Gero and Aldahhak, Hazem}}, issn = {{0192-8651}}, journal = {{Journal of Computational Chemistry}}, keywords = {{Computational Mathematics, General Chemistry}}, number = {{6}}, pages = {{413--420}}, publisher = {{Wiley}}, title = {{{Adatom mediated adsorption of N‐heterocyclic carbenes on Cu(111) and Au(111)}}}, doi = {{10.1002/jcc.26801}}, volume = {{43}}, year = {{2021}}, } @article{37331, abstract = {{High harmonic generation (HHG) from solids shows great application prospects in compact short-wavelength light sources and as a tool for imaging the dynamics in crystals with subnanometer spatial and attosecond temporal resolution. However, the underlying collision dynamics behind solid HHG is still intensively debated and no direct mapping relationship between the collision dynamics with band structure has been built. Here, we show that the electron and its associated hole can be elastically scattered by neighboring atoms when their wavelength approaches the atomic size. We reveal that the elastic scattering of electron/hole from neighboring atoms can dramatically influence the electron recombination with its left-behind hole, which turns out to be the fundamental reason for the anisotropic interband HHG observed recently in bulk crystals. Our findings link the electron/hole backward scattering with Van Hove singularities and forward scattering with critical lines in the band structure and thus build a clear mapping between the band structure and the harmonic spectrum. Our work provides a unifying picture for several seemingly unrelated experimental observations and theoretical predictions, including the anisotropic harmonic emission in MgO, the atomic-like recollision mechanism of solid HHG, and the delocalization of HHG in ZnO. This strongly improved understanding will pave the way for controlling the solid-state HHG and visualizing the structure-dependent electron dynamics in solids.}}, author = {{Zuo, Ruixin and Trautmann, Alexander and Wang, Guifang and Hannes, Wolf-Rüdiger and Yang, Shidong and Song, Xiaohong and Meier, Torsten and Ciappina, Marcelo and Duc, Huynh Thanh and Yang, Weifeng}}, issn = {{2765-8791}}, journal = {{Ultrafast Science}}, publisher = {{American Association for the Advancement of Science (AAAS)}}, title = {{{Neighboring Atom Collisions in Solid-State High Harmonic Generation}}}, doi = {{10.34133/2021/9861923}}, volume = {{2021}}, year = {{2021}}, } @article{37338, abstract = {{AbstractMethylammonium lead iodide perovskite (MAPbI3) is renowned for an impressive power conversion efficiency rise and cost-effective fabrication for photovoltaics. In this work, we demonstrate that polycrystalline MAPbI3s undergo drastic changes in optical properties at moderate field strengths with an ultrafast response time, via transient Wannier Stark localization. The distinct band structure of this material - the large lattice periodicity, the narrow electronic energy bandwidths, and the coincidence of these two along the same high-symmetry direction – enables relatively weak fields to bring this material into the Wannier Stark regime. Its polycrystalline nature is not detrimental to the optical switching performance of the material, since the least dispersive direction of the band structure dominates the contribution to the optical response, which favors low-cost fabrication. Together with the outstanding photophysical properties of MAPbI3, this finding highlights the great potential of this material in ultrafast light modulation and novel photonic applications.}}, author = {{Berghoff, Daniel and Bühler, Johannes and Bonn, Mischa and Leitenstorfer, Alfred and Meier, Torsten and Kim, Heejae}}, issn = {{2041-1723}}, journal = {{Nature Communications}}, keywords = {{General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry, Multidisciplinary}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Low-field onset of Wannier-Stark localization in a polycrystalline hybrid organic inorganic perovskite}}}, doi = {{10.1038/s41467-021-26021-4}}, volume = {{12}}, year = {{2021}}, } @article{23477, author = {{Thong, Le Huu and Ngo, Cong and Duc, Huynh Thanh and Song, Xiaohong and Meier, Torsten}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, pages = {{085201}}, title = {{{Microscopic analysis of high harmonic generation in semiconductors with degenerate bands}}}, doi = {{10.1103/physrevb.103.085201}}, volume = {{103}}, year = {{2021}}, } @article{21946, abstract = {{Lithium niobate (LiNbO3), a material frequently used in optical applications, hosts different kinds of polarons that significantly affect many of its physical properties. In this study, a variety of electron polarons, namely free, bound, and bipolarons, are analyzed using first-principles calculations. We perform a full structural optimization based on density-functional theory for selected intrinsic defects with special attention to the role of symmetry-breaking distortions that lower the total energy. The cations hosting the various polarons relax to a different degree, with a larger relaxation corresponding to a larger gap between the defect level and the conduction-band edge. The projected density of states reveals that the polaron states are formerly empty Nb 4d states lowered into the band gap. Optical absorption spectra are derived within the independent-particle approximation, corrected by the GW approximation that yields a wider band gap and by including excitonic effects within the Bethe-Salpeter equation. Comparing the calculated spectra with the density of states, we find that the defect peak observed in the optical absorption stems from transitions between the defect level and a continuum of empty Nb 4d states. Signatures of polarons are further analyzed in the reflectivity and other experimentally measurable optical coefficients.}}, author = {{Schmidt, Falko and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt, Wolf Gero and Schindlmayr, Arno}}, issn = {{2073-4352}}, journal = {{Crystals}}, pages = {{542}}, publisher = {{MDPI}}, title = {{{Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response}}}, doi = {{10.3390/cryst11050542}}, volume = {{11}}, year = {{2021}}, } @inproceedings{43746, abstract = {{Population/mixing-time-dependent two-dimensional coherent spectra are presented for exciton-polaritons in a microcavity. Theory based on dynamically-controlled truncation reveals coherent and incoherent contributions to the decay dynamics.}}, author = {{Meier, Torsten and Paul, Jagannath and Rose, Hendrik and Wahlstrand, Jared K and Bristow, Alan D}}, booktitle = {{Frontiers in Optics}}, isbn = {{978-1-55752-308-2}}, location = {{Washington, DC United States}}, publisher = {{Frontiers in Optics}}, title = {{{Coherent and incoherent contribution of population dynamics of semiconductor exciton-polaritons}}}, doi = {{10.1364/FIO.2021.FW5C.6}}, year = {{2021}}, } @inproceedings{23474, author = {{Reichelt, Matthias and Rose, Hendrik and Kosarev, Alexander N. and Poltavtsev, Sergey V. and Bayer, Manfred and Akimov, Ilya A. and Schneider, Christian and Kamp, Martin and Höfling, Sven and Meier, Torsten}}, booktitle = {{Ultrafast Phenomena and Nanophotonics XXV}}, editor = {{Betz, Markus and Elezzabi, Abdulhakem Y.}}, title = {{{Controlling the emission time of photon echoes by optical freezing of exciton dephasing and rephasing in quantum-dot ensembles}}}, doi = {{10.1117/12.2576887}}, volume = {{11684}}, year = {{2021}}, } @article{29749, author = {{Murzakhanov, F. F. and Yavkin, B. V. and Mamin, G. V. and Orlinskii, S. B. and von Bardeleben, H. J. and Biktagirov, Timur and Gerstmann, Uwe and Soltamov, V. A.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, pages = {{245203}}, publisher = {{American Physical Society (APS)}}, title = {{{Hyperfine and nuclear quadrupole splitting of the NV− ground state in 4H-SiC}}}, doi = {{10.1103/physrevb.103.245203}}, volume = {{103}}, year = {{2021}}, } @article{22010, author = {{Aldahhak, Hazem and Hogan, Conor and Lindner, Susi and Appelfeller, Stephan and Eisele, Holger and Schmidt, Wolf Gero and Dähne, Mario and Gerstmann, Uwe and Franz, Martin}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, pages = {{035303}}, title = {{{Electronic structure of the Si(111)3×3R30∘−B surface from theory and photoemission spectroscopy}}}, doi = {{10.1103/physrevb.103.035303}}, volume = {{103}}, year = {{2021}}, } @article{23478, author = {{Rose, Hendrik and Popolitova, D. V. and Tikhonova, O. V. and Meier, Torsten and Sharapova, Polina}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, title = {{{Dark-state and loss-induced phenomena in the quantum-optical regime of Λ-type three-level systems}}}, doi = {{10.1103/physreva.103.013702}}, volume = {{103}}, year = {{2021}}, } @article{23473, author = {{Belobo, Didier Belobo and Meier, Torsten}}, issn = {{1367-2630}}, journal = {{New Journal of Physics}}, title = {{{Approximate nonlinear wave solutions of the coupled two-component Gross–Pitaevskii equations with spin–orbit interaction}}}, doi = {{10.1088/1367-2630/abf3ed}}, volume = {{23}}, year = {{2021}}, } @article{22881, author = {{Nguyen, T. T. Nhung and Sollfrank, T. and Tegenkamp, C. and Rauls, E. and Gerstmann, Uwe}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, pages = {{L201408}}, title = {{{Impact of screening and relaxation on weakly coupled two-dimensional heterostructures}}}, doi = {{10.1103/physrevb.103.l201408}}, volume = {{103}}, year = {{2021}}, } @article{21635, abstract = {{Modern forming processes often allow today the efficient production of complex parts. In order to increase the sustainability of forming processes it would be favorable if the forming of workpieces becomes possible using production waste. At the Chair of Forming and Machining Technology of the Paderborn University (LUF) research is presently conducted with the overall goal to produce workpieces directly from secondary aluminum (e.g., powder and chips). Therefore, friction-based forming processes like friction spinning (or cognate processes) are used due to their high efficiency. As a pre-step, the production of semi-finished parts was the subject of accorded research work at the LUF. Therefore, a friction-based hot extrusion process was used for the full recycling or rework of aluminum chips into profiles. Investigations of the recycled semi-finished products show that they are comparable to conventionally produced semi-finished products in terms of dimensional stability and shape accuracy. An analysis of the mechanical properties of hardness and tensile strength shows that a final product with good and homogeneously distributed properties can be produced. Furthermore, significant correlations to the friction spinning process could be found that are useful for the above-mentioned direct part production from secondary aluminum.}}, author = {{Borgert, Thomas and Homberg, Werner}}, issn = {{2075-4701}}, journal = {{Metals}}, title = {{{Friction-Induced Recycling Process for User-Specific Semi-Finished Product Production}}}, doi = {{10.3390/met11040663}}, year = {{2021}}, } @inproceedings{23746, author = {{Moritzer, Elmar and Flachmann, Felix}}, booktitle = {{SPE ANTEC 2021: The Annual Technical Conference for Plastic Professionals}}, isbn = {{978-1-7138-3075-7}}, location = {{Online}}, pages = {{536--540}}, title = {{{Influence of Chemical Blowing Agents on the Filling Behavior of Wood-Plastic-Composite Melts}}}, year = {{2021}}, } @article{23789, author = {{Bolenz, Lukas and Ehlert, Thomas and Dechert, Christopher and Bertling, René and Kenig, Eugeny}}, issn = {{0263-8762}}, journal = {{Chemical Engineering Research and Design}}, pages = {{99--108}}, title = {{{Modelling of a continuous distillation process with finite reflux ratio using the hydrodynamic analogy approach}}}, doi = {{10.1016/j.cherd.2021.05.025}}, year = {{2021}}, } @inproceedings{34222, abstract = {{Driven by the CO2-emission law by the European government and the increasing costs for raw materials as well as energy, the automotive industry is increasingly using multi-material constructions. This leads to a continuous increase in the use of mechanical joining techniques and especially the self-piercing riveting is of particular importance. The reason for this is the wide range of joining possibilities as well as the high load-bearing capacities of the joints. To be able to react to changing boundary conditions, like material thickness or strength variation of the sheets, research work is crucial with regard to the increase of versatility. In this paper, a numerical study of the influences on the selfpiercing riveting process is presented. For this purpose, the influence of different process parameters such as rivet length and die depth on various quality-relevant characteristics were investigated. With the help of the design of experiment, significant influences were determined and interactions between the individual parameters are shown.}}, author = {{Kappe, Fabian and Bielak, Christian Roman and Sartisson, Vadim and Bobbert, Mathias and Meschut, Gerson}}, booktitle = {{ESAFORM 2021}}, publisher = {{University of Liege}}, title = {{{Influence of rivet length on joint formation on self-piercing riveting process considering further process parameters}}}, doi = {{10.25518/esaform21.4277}}, year = {{2021}}, } @inproceedings{30675, abstract = {{In many areas of product manufacturing constructions consist of individual components and metal sheets that are joined together to form complex structures. A simple and industrial common method for joining dissimilar and coated materials is clinching. During the joining process and due to the service load cracks can occur in the area of the joint, propagate due to cyclic loading and consequently lead to structural failure. For the prevention of these damage cases, first of all knowledge about the fracture mechanical material parameters regarding the original material state of the sheet metals used within the clinching process are essential.Within the scope of this paper experimental and numerical preliminary investigations regarding the fracture mechanical behavior of sheet metals used within the clinching process are presented. Due to the low thickness of 1.5 mm of the material sheets, the development of a new specimen is necessary to determine the crack growth rate curve including the fracture mechanical parameters like the threshold against crack growth ΔKI,th and the fracture toughness KIC of the base material HCT590X. For the experimental determination of the crack growth rate curve the numerical calculation of the geometry factor function as well as the calibration function of this special specimen are essential. After the experimental validation of the numerically determined calibration function, crack growth rate curves are determined for the stress ratios R = 0.1 and R = 0.3 to examine the mean stress sensitivity. In addition, the different rolling directions of 0° and 90° in relation to the initial crack are taken into account in order to investigate the influence of the anisotropy due to rolling.}}, author = {{Weiß, Deborah and Schramm, Britta and Kullmer, Gunter}}, booktitle = {{Key Engineering Materials}}, issn = {{1662-9795}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, location = {{online}}, pages = {{127--132}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{Numerical and Experimental Fracture Mechanical Investigations of Clinchable Sheet Metals Made of HCT590X}}}, doi = {{10.4028/www.scientific.net/kem.883.127}}, volume = {{883}}, year = {{2021}}, } @article{30674, abstract = {{AbstractIn addition to the classical strength calculation, it is important to design components with regard to fracture mechanics because defects and cracks in a component can drastically influence its strength or fatigue behavior. Cracks can propagate due to operational loads and consequently lead to component failure. The fracture mechanical analysis provides information on stable or unstable crack growth as well as about the direction and the growth rate of a crack. For this purpose, sufficient information has to be available about the crack location, the crack length, the component geometry, the component loading and the fracture mechanical material parameters. The fracture mechanical properties are determined experimentally with standardized specimens as defined by the guidelines of the American Society for Testing and Materials. In practice, however, especially in the context with damage cases or formed material fracture mechanical parameters directly for a component are of interest. However, standard specimens often cannot be extracted at all due to the complexity of the component geometry. Therefore, the development of special specimens is required whereby certain arrangements have to be made in advance. These arrangements are presented in the present paper in order to contribute to a holistic investigation chain for the experimental determination of fracture mechanical material parameters with special specimens.}}, author = {{Weiß, Deborah and Schramm, Britta and Kullmer, Gunter}}, issn = {{0944-6524}}, journal = {{Production Engineering}}, keywords = {{Industrial and Manufacturing Engineering, Mechanical Engineering}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Holistic investigation chain for the experimental determination of fracture mechanical material parameters with special specimens}}}, doi = {{10.1007/s11740-021-01096-6}}, year = {{2021}}, } @article{25894, abstract = {{Powder X-ray diffraction (XRD) patterns of ordered mesoporous CMK-8 and CMK-9 carbon materials are simulated by geometric modeling. The materials are amorphous at the atomic length scale but exhibit highly symmetric gyroidal structures at the nanometer scale, corresponding to regular, continuous nanopore systems with cubic symmetry. Their structures lead to characteristic low-angle XRD signatures. We introduce a model based on geometrical considerations to simulate CMK-8 and CMK-9 structures with variable volume fraction of carbon (vs. pore volume, i.e., variable 'pore wall thickness'). In addition, we also simulate carbon materials with variable amounts of guest species (e.g., sulfur) residing in their pores. The corresponding XRD patterns are calculated. The carbon volume fraction turns out to have a significant impact on the relative diffraction peak intensities, especially in case of CMK-9 carbon that features a bimodal porosity. Likewise, the presence of guest species in the pores may also strongly affect the relative peak intensities. Our study suggests that careful evaluation of experimental low-angle XRD patterns of (real) CMK-8 or CMK-9 materials offers an opportunity to obtain detailed information about the nanostructural properties in addition to the mere identification of the pore systems geometry.}}, author = {{Schwind, Bertram and Smått, Jan-Henrik and Tiemann, Michael and Weinberger, Christian}}, issn = {{1387-1811}}, journal = {{Microporous and Mesoporous Materials}}, title = {{{Modeling of gyroidal mesoporous CMK-8 and CMK-9 carbon nanostructures and their X-Ray diffraction patterns}}}, doi = {{10.1016/j.micromeso.2020.110330}}, year = {{2021}}, } @article{25897, abstract = {{A comparison of infrared spectroscopic analytical approaches was made in order to assess their applicability for internal structure characterization of SiO2 thin films. Markers for porosity and/or disorder based on the analysis of the asymmetric stretching absorption band of SiO2 between 900−1350 cm−1 were discussed. The shape of this band, which shows a well-defined LO–TO splitting, depends not only on the inherent characteristics of the film under analysis but also on the particular geometry of the IR experiment and the specific surface selection rules of the substrate. Three types of SiO2 thin films with clearly defined porosity ranging from dense films to mesoporous films were investigated by transmission (at different incidence angles), direct specular reflection (at different angles), and diffuse reflection. Two different types of substrate, metallic and semiconducting, were used. The combined effect of substrate and specific technique in the final shape of the band, was discussed, and the efficacy for their applicability to the determination of porosity in thin SiO2 films was critically evaluated.}}, author = {{de los Arcos, Teresa and Müller, Hendrik and Wang, Fuzeng and Damerla, Varun Raj and Hoppe, Christian and Weinberger, Christian and Tiemann, Michael and Grundmeier, Guido}}, issn = {{0924-2031}}, journal = {{Vibrational Spectroscopy}}, title = {{{Review of infrared spectroscopy techniques for the determination of internal structure in thin SiO2 films}}}, doi = {{10.1016/j.vibspec.2021.103256}}, year = {{2021}}, } @phdthesis{42812, author = {{Olenberg, Alexander}}, isbn = {{9783843947855}}, title = {{{Untersuchung und Optimierung von strukturierten Packungen mittels CFD-Simulationen }}}, year = {{2021}}, } @article{25893, abstract = {{Tailor-made ordered mesoporous materials bear great potential in numerous fields of application where large interfaces are required. However, the inherent surfacechemical properties of conventional materials, such as silica, carbon or organosilica, poses some limitations with respect to their application. Surface manipulation by functionalization with chemically more reactive groups is one way to improve materials for their desired purpose. Another approach is the design of high surface-area composite materials. The surface manipulation, either by functionalization or by introducing guest species, can be performed selectively. This means that when several distinct, i.e. , hierarchical, types of surfaces or pore systems exist in a material, each of them may be chosen for manipulation. Several strategies can be identified to achieve this goal. Molecules or molecule assemblies can be utilized to temporarily protect pores or surfaces (soft protection), while manipulation occurs at the accessible sites. This approach is a recurring motive in this review and can also be applied to rigid template matrices (hard protection). Furthermore, the size of functionalization agents (size protection) and their reactivity/diffusion (kinetic protection) into the pores can also be utilized to achieve selectivity. In addition, challenges in the synthesis and characterization of selectively manipulated ordered mesoporous materials are discussed.}}, author = {{Tiemann, Michael and Weinberger, Christian}}, issn = {{2196-7350}}, journal = {{Advanced Materials Interfaces}}, title = {{{Selective Modification of Hierarchical Pores and Surfaces in Nanoporous Materials}}}, doi = {{10.1002/admi.202001153}}, year = {{2021}}, } @article{41431, author = {{Fuchs, Christian}}, journal = {{tripleC: Communication, Capitalism & Critique}}, number = {{1}}, pages = {{1--194}}, title = {{{Engels@200: Friedrich Engels in the Age of Digital Capitalism}}}, doi = {{https://doi.org/10.31269/triplec.v19i1.1233}}, volume = {{19}}, year = {{2021}}, } @article{41599, author = {{Fuchs, Christian and Dyer-Witheford, Nick}}, journal = {{国际社会科学杂志 (Journal of International Social Sciences) 2021 (9)}}, pages = {{66--76}}, title = {{{卡尔·马克思与互联网研究}}}, year = {{2021}}, } @article{25896, abstract = {{In this report, a flame spray pyrolysis setup has been examined with various in situ extraction methods of particle samples along the flame axis. First, two precursor formulations leading to the formation of iron oxide nanoparticles were used in a standardized SpraySyn burner system, and the final particle outcome was characterized by a broad range of established powder characterization techniques (TEM/HRTEM, SAXS, XRD, BET). The characterization of the powder products evidenced that mostly homogeneous gas-to-particle conversion takes place when applying an acidic precursor solution, whereas the absence of the acid leads to a dominant droplet-to-particle pathway. Our study indicates that a droplet-to-particle-pathway could be present even when processing the acidic formulation. However, even if a secondary pathway might take place in this case as well, it is not dominant and nearly negligible. Subsequently, the in situ particle structure evolution was investigated for the dominant gas-to-particle pathway, and particles were extracted along the flame axis for online SMPS and offline TEM/HRTEM analysis. Due to the highly reactive conditions within the flame (high temperatures, turbulent flow field, high particle number concentrations), the extraction of representative samples from spray flames is challenging. In order to handle the reactive conditions, two extraction techniques were tailored in this report. To extract an aerosol sample within the flame for SMPS measurement, a Hole in a Tube probe was adjusted. Thus, the mobility particle diameter as well as the corresponding distribution widths were obtained at different heights above the burner along the flame axis. For TEM/HRTEM image analysis, particle samples were collected thermophoretically by means of a tailored shutter system. Since all sampling grids were protected until reaching the flame axis and due to the low sampling time, momentary captures of local particle structures could be extracted precisely. The particle morphologies have clearly shown an evolution from spherical and paired particles in the flame center to fractal and compact agglomerates at later synthesis stages.}}, author = {{Tischendorf, R. and Simmler, M. and Weinberger, Christian and Bieber, M. and Reddemann, M. and Fröde, F. and Lindner, J. and Pitsch, H. and Kneer, R. and Tiemann, Michael and Nirschl, H. and Schmid, H.-J.}}, issn = {{0021-8502}}, journal = {{Journal of Aerosol Science}}, title = {{{Examination of the evolution of iron oxide nanoparticles in flame spray pyrolysis by tailored in situ particle sampling techniques}}}, doi = {{10.1016/j.jaerosci.2020.105722}}, year = {{2021}}, }