TY - JOUR AB - The proton conduction properties of a phosphonato-sulfonate-based coordination polymer are studied by impedance spectroscopy using a single crystal specimen. Two distinct conduction mechanisms are identified. Water-mediated conductance along the crystal surface occurs by mass transport, as evidenced by a high activation energy (0.54 eV). In addition, intrinsic conduction by proton ′hopping′ through the interior of the crystal with a low activation energy (0.31 eV) is observed. This latter conduction is anisotropic with respect to the crystal structure and seems to occur through a channel along the c axis of the orthorhombic crystal. Proton conduction is assumed to be mediated by sulfonate groups and non-coordinating water molecules that are part of the crystal structure. AU - Javed, Ali AU - Wagner, Thorsten AU - Wöhlbrandt, Stephan AU - Stock, Norbert AU - Tiemann, Michael ID - 25900 JF - ChemPhysChem SN - 1439-4235 TI - Proton Conduction in a Single Crystal of a Phosphonato‐Sulfonate‐Based Coordination Polymer: Mechanistic Insight ER - TY - JOUR AB - This Special Issue on “Functional Nanoporous Materials” in the MDPI journal nanomaterials features seven original papers ... AU - Weinberger, Christian AU - Tiemann, Michael ID - 25902 JF - Nanomaterials SN - 2079-4991 TI - Functional Nanoporous Materials ER - TY - GEN AU - Kraft, Kerstin ID - 42870 TI - Kleider in Bewegung. Frauenmode seit 1850 ER - TY - CONF AU - Petrov, Dmitry AU - Hilleringmann, Ulrich ID - 39405 T2 - 2020 IEEE SENSORS TI - Water-based primary cell for powering of wireless sensors ER - TY - BOOK AB - Die h-Moll-Messe und die Johannes-Passion sind unzweifelhaft zwei Hauptwerke Johann Sebastian Bachs. Der vorliegende Band versammelt die Vorträge aus zwei Symposien, die im Oktober 2017 und März 2019 in Essen abgehalten worden sind. Im Dialog zwischen Theologie und Musikwissenschaft werden in den Beiträgen unterschiedliche Aspekte fokussiert, die je nach Werk zum einen eher auf dem Gebiet der Genese, Rezeption und Edition (h-Moll-Messe), zum anderen eher auf dessen theologischem oder musikgeschichtlichem Kontext (Johannes-Passion) liegen. In dieser interdisziplinären Zusammenstellung werden zahlreiche neue Facetten der Werke und ihrer Kontexte erhellt. ED - Höink, Dominik ED - Jacob, Andreas ID - 36432 SN - 978-3-487-15916-4 TI - Musikwissenschaft und Theologie im Dialog - Johann Sebastian Bachs "h-Moll-Messe" und "Johannes-Passion" VL - 20 ER - TY - CHAP AU - Höink, Dominik ED - Höink, Dominik ED - Jacob, Andreas ID - 36461 SN - 9783487159164 T2 - Musikwissenschaft und Theologie im Dialog - Johann Sebastian Bachs "h-Moll-Messe" und "Johannes-Passion" TI - Die h-Moll-Messe szenisch: Rosamund Gilmore (1986), Achim Freyer (1996) und Jochen Biganzoli (2017) VL - 20 ER - TY - CHAP AU - Dehmel, Lukas AU - Gerhardts, Lara AU - Meister, Dorothee M. ED - Meister, Dorothee M. ED - Mindt, Ilka ID - 43144 T2 - Mobile Medien im Schulkontext TI - Zur Stabilisierung medienbezogener Handlungsroutinen im Lehrer*innenberuf. Längsschnittliche Betrachtungen zur Integration von Tablets in den Arbeitsalltag ER - TY - GEN AU - Bohnenkamp, Björn AU - Burkhardt, Marcus AU - Grashöfer, Katja AU - Hlukhovych, Adrianna AU - Krewani, Angela AU - Matzner, Tobias AU - Missomelius, Petra AU - Shnayien, Marie-Luise ID - 42912 TI - Online-Lehre 2020 – Eine medienwissenschaftliche Perspektive. Diskussionspapier Nr. 10 ER - TY - BOOK ED - Burkhardt, Marcus ED - Grashöfer, Katja ED - Shnayien, Marie-Luise ID - 42916 TI - Explorations in Digital Cultures ER - TY - CHAP AB - Jeder Wissenschaftsdisziplin hilft ein Bewusstsein ihrer Geschichte und die Kenntnis ihrer Vielfalt, Paradigmen und Entwicklungsmöglichkeiten. Darauf basierend können Forschende ihr spezifisches Potential, Wissen und Handlungsrepertoire entfalten. Dabei ist Geschichtsschreibung und historische Berufsbildungsforschung immer zugleich selbst gefangen in ihrer je eigenen Zeit, beschränkt durch die Perspektiven der Personen, die sich an dem Rückblick beteiligen. Das macht Geschichte auch immer zur Geschichte der Herrschenden, die eine spezifische Perspektive und die mit ihr verbundene Forschung schreibend tradieren. Deshalb ist Vielfalt für die historische Berufsbildungsforschung so wertvoll, weil sie sich gegen verengte, eindimensionale Retrospektive stellt, gewissermaßen in die Ritzen und Fugen der Zeit schauen lässt. Basierend auf einer Tagung der Herausgeber im September 2019 zu „Retrospektiven, Perspektiven & Synergien einer Historischen Berufsbildungs- und Wissenschaftsforschung" an der Universität Rostock, entfaltet sich die Bandbreite der historischen Berufsbildungsforschung. Der Band vereint paradigmatische, mal stärker biografischen Zugänge sowie systemisch-gesellschaftspolitische und schließlich Analysen zur Genese der Wissenschaftsdisziplin. In den Beiträgen wird dem Einfluss von Einzelpersönlichkeiten und Forschungsparadigmen ebenso wie dem von Bildungssystemen am Beispiel der DDR, Skandinaviens und der bundesdeutschen Bildungspolitik nachgegangen. Vereint sind sowohl Beiträge zur Entstehung der Berufs- und Wirtschaftspädagogik, zur Rekonstruktion der Benachteiligtenförderung, Soziökonomie, Pflegedidaktik und Frauenforschung als auch Analysen berufsspezifischer Betrachtungen am Beispiel des Druckgewerbes, der Offiziere und der Ausbilder*innen. AU - Heisler, Dietmar ED - Kaiser, Franz ED - Götzel, Mathias ID - 37004 KW - Benachteiligtenförderung KW - historische Berufsbildungsforschung KW - berufliche Förderung KW - Sozialpädagogik T2 - Historische Berufsbildungsforschung Perspektiven auf Wissenschaftsgenese und -dynamik. TI - Reparaturbetrieb, Inklusion und Fachkräftesicherung Transformation der Benachteiligtenförderung in Deutschland. ER - TY - JOUR AU - Hälterlein, Jens ID - 43352 IS - 1 JF - TATuP TI - (Un)Sicherheitsproduktion im Cyberspace. Cybersecurity-Architekturen in Deutschland und der Schweiz VL - 29 ER - TY - JOUR AU - Hälterlein, Jens ID - 43351 JF - Soziopolis TI - Die Simulation der Pandemie..Ein Beitrag zur Reihe "Sicherheit in der Krise". ER - TY - CONF AU - Engemann, Mario ID - 43411 TI - Lehrerkooperation und Digitalisierung - Gestaltung digital-kooperativer Arbeitsbeziehungen und der Stellenwert einer Fachlichkeitskonzeption von Lehrenden der Fächergruppe Erziehungswissenschaft ER - TY - GEN AU - Schroeter-Wittke, Harald ID - 41071 SN - 0540–6226 T2 - Jahrbuch für Evangelische Kirchengeschichte des Rheinlandes TI - Gero Fuchs: Gewinn als Umbruch der Ordnung? Der Fall des Siegburger Töpfers Peter Knütgen im 16. Jahrhundert, Tübingen 2019 VL - 69 ER - TY - GEN AU - Schroeter-Wittke, Harald ID - 41072 SN - 0540–6226 T2 - Jahrbuch für Evangelische Kirchengeschichte des Rheinlandes TI - Laura Schmidt: Weihnachtliches Theater. Zur Entstehung und Geschichte einer bürgerlichen Fest- und Theaterkultur, Bielefeld 2017 VL - 69 ER - TY - JOUR AB - Dieser Beitrag basiert auf den Ergebnissen eines im Jahr 2019 abgeschlossenen Promotionsvorhabens im Rahmen des interventiv angelegten, in Dortmund angesiedelten, Forschungsprojekts KidSmart – Medienkompetent zum Schulübergang zu den Mediensozialisationsbedingungen von deutschen, deutsch-türkischen und deutsch-anderen vier und fünf Jahre alten Mädchen und Jungen in den sozialen Feldern Familie und Kita. Im vorliegenden Beitrag wird auf die Befragung der ErzieherInnen fokussiert, die mittels halbstandardisierter Fragebögen durchgeführt wurde. Untersucht wurde, wie sich der sprachlich-kulturelle Hintergrund der Kinder für das Kommunikationsverhalten der ErzieherInnen mit den Kindern in pädagogischer Anschlusskommunikation und in Gesprächen mit den Eltern der Kinder auswirkt. Hier wurde auch eine intersektionale Perspektive eingenommen und parallel zur Herkunftskultur auch das biologische Geschlecht der Kinder in die Auswertung einbezogen. Es stellte sich heraus, dass die Kommunikation sowohl mit den Kindern als auch mit den Eltern in Abhängigkeit der Herkunftskultur der Kinder und auch ihres Geschlechtes erfolgt. Pädagogisch ist zu fragen, inwiefern es den pädagogischen Fachkräften gelingt, benachteiligende Ausgangslagen auch tatsächlich auszugleichen und Partizipation im Sinne von Inklusion zu ermöglichen. Ausgehend von diesen Ergebnissen wird in diesem Beitrag die Bedeutung und Relevanz der Überschneidungen und Interdependenzen von Ungleichheitsdimensionen für eine inklusionsorientierte Qualifikation pädagogischer Fachkräfte in institutionell-frühkindlichen Medienbildungskontexten diskutiert. Konkret richtet sich der Blick auf die sprachlich-kulturelle Ein- und Vielfalt in den frühkindlichen Einrichtungen sowie die Wahrnehmungen und Einschätzungen der pädagogischen Fachkräfte, die sie in Hinblick auf die Kooperationswilligkeit der Eltern, die Anschlusskommunikation mit den Kindern und schließlich die medialen Fähig- und Fertigkeiten der Kinder äußern. AU - Günesli, Habib ID - 44057 IS - 3 JF - QfI - Qualifizierung für Inklusion Online-Zeitschrift zur Forschung über Aus-, Fort- und Weiterbildung pädagogischer Fachkräfte TI - Inklusion und Intersektionalität im Kontext frühkindlicher Medienbildungsforschung. Sprachkulturelle Homogenität und Diversität sowie ihre Auswirkungen auf pädagogische Kommunikation in der Frühen Bildung VL - 2 ER - TY - CONF AU - Chadha, Gavneet Singh AU - Meydani, Elnaz AU - Schwung, Andreas ID - 44074 T2 - Recent Advances in Big Data and Deep Learning: Proceedings of the INNS Big Data and Deep Learning Conference INNSBDDL2019, held at Sestri Levante, Genova, Italy 16-18 April 2019 TI - Regularizing neural networks with gradient monitoring ER - TY - JOUR AB - We devise a method to certify nonclassical features via correlations of phase-space distributions by unifying the notions of quasiprobabilities and matrices of correlation functions. Our approach complements and extends recent results that were based on Chebyshev's integral inequality \cite{BA19}. The method developed here correlates arbitrary phase-space functions at arbitrary points in phase space, including multimode scenarios and higher-order correlations. Furthermore, our approach provides necessary and sufficient nonclassicality criteria, applies to phase-space functions beyond s-parametrized ones, and is accessible in experiments. To demonstrate the power of our technique, the quantum characteristics of discrete- and continuous-variable, single- and multimode, as well as pure and mixed states are certified only employing second-order correlations and Husimi functions, which always resemble a classical probability distribution. Moreover, nonlinear generalizations of our approach are studied. Therefore, a versatile and broadly applicable framework is devised to uncover quantum properties in terms of matrices of phase-space distributions. AU - Bohmann, Martin AU - Agudelo, Elizabeth AU - Sperling, Jan ID - 26290 JF - Quantum SN - 2521-327X TI - Probing nonclassicality with matrices of phase-space distributions ER - TY - JOUR AU - Sperling, Jan AU - Walmsley, I A ID - 26292 JF - Physica Scripta SN - 0031-8949 TI - Classical evolution in quantum systems ER - TY - JOUR AB - Semiconductor microcavities are frequently studied in the context of semiconductor lasers and in application-oriented fundamental research on topics such as linear and nonlinear polariton systems, polariton lasers, polariton pattern formation, and polaritonic Bose–Einstein condensates. A commonly used approach to describe theoretical properties includes a phenomenological single-mode equation that complements the equation for the nonlinear optical response (interband polarization) of the semiconductor. Here, we show how to replace the single-mode equation by a fully predictive transfer function method that, in contrast to the single-mode equation, accounts for propagation, retardation, and pulse-filtering effects of the incident light field traversing the distributed Bragg reflector (DBR) mirrors, without substantially increasing the numerical complexity of the solution. As examples, we use cavities containing GaAs quantum wells and transition-metal dichalcogenides (TMDs). AU - Carcamo, M. AU - Schumacher, Stefan AU - Binder, R. ID - 40438 IS - 22 JF - Applied Optics KW - Atomic and Molecular Physics KW - and Optics KW - Engineering (miscellaneous) KW - Electrical and Electronic Engineering SN - 1559-128X TI - Transfer function replacement of phenomenological single-mode equations in semiconductor microcavity modeling VL - 59 ER - TY - JOUR AU - Ma, Xuekai AU - Kartashov, YV AU - Kavokin, A AU - Schumacher, Stefan ID - 20586 IS - 20 JF - Optics Letters SN - 0146-9592 TI - Chiral condensates in a polariton hexagonal ring. VL - 45 ER - TY - JOUR AU - von Bardeleben, H. J. AU - Rauls, E. AU - Gerstmann, Uwe ID - 40444 IS - 18 JF - Physical Review B SN - 2469-9950 TI - Carbon vacancy-related centers in 3C-silicon carbide: Negative-U properties and structural transformation VL - 101 ER - TY - JOUR AB -

EPR spectroscopy reveals the universality class and dynamic effects of the [NH4][Zn(HCOO)3] hybrid formate framework.

AU - Navickas, Marius AU - Giriūnas, Laisvydas AU - Kalendra, Vidmantas AU - Biktagirov, Timur AU - Gerstmann, Uwe AU - Schmidt, Wolf Gero AU - Mączka, Mirosław AU - Pöppl, Andreas AU - Banys, Jūras AU - Šimėnas, Mantas ID - 17070 JF - Physical Chemistry Chemical Physics SN - 1463-9076 TI - Electron paramagnetic resonance study of ferroelectric phase transition and dynamic effects in a Mn2+ doped [NH4][Zn(HCOO)3] hybrid formate framework VL - 22 ER - TY - JOUR AU - Biktagirov, Timur AU - Gerstmann, Uwe ID - 29745 IS - 2 JF - Physical Review Research KW - General Engineering SN - 2643-1564 TI - Spin-orbit driven electrical manipulation of the zero-field splitting in high-spin centers in solids VL - 2 ER - TY - JOUR AB - Density-functional theory calculations of (TiO2)n clusters (n = 1–5) in the gas phase and adsorbed on pristine graphene as well as graphene quantum dots are presented. The cluster adsorption is found to be dominated by van der Waals forces. The electronic structure and in particular the excitation energies of the bare clusters and the TiO2/graphene composites are found to vary largely in dependence on the size of the respective constituents. This holds in particular for the energy and the spatial localization of the highest occupied and lowest unoccupied molecular orbitals. In addition to a substantial gap narrowing, a pronounced separation of photoexcited electrons and holes is predicted in some instances. This is expected to prolong the lifetime of photoexcited carriers. Altogether, TiO2/graphene composites are predicted to be promising photocatalysts with improved electronic and photocatalytic properties compared to bulk TiO2. AU - Badalov, Sabuhi AU - Wilhelm, René AU - Schmidt, Wolf Gero ID - 19189 JF - Journal of Computational Chemistry SN - 0192-8651 TI - Photocatalytic properties of graphene‐supported titania clusters from density‐functional theory ER - TY - JOUR AB - AbstractSemiconductor quantum dots are excellent candidates for ultrafast coherent manipulation of qubits by laser pulses on picosecond timescales or even faster. In inhomogeneous ensembles a macroscopic optical polarization decays rapidly due to dephasing, which, however, is reversible in photon echoes carrying complete information about the coherent ensemble dynamics. Control of the echo emission time is mandatory for applications. Here, we propose a concept to reach this goal. In a two-pulse photon echo sequence, we apply an additional resonant control pulse with multiple of 2π area. Depending on its arrival time, the control slows down dephasing or rephasing of the exciton ensemble during its action. We demonstrate for self-assembled (In,Ga)As quantum dots that the photon echo emission time can be retarded or advanced by up to 5 ps relative to its nominal appearance time without control. This versatile protocol may be used to obtain significantly longer temporal shifts for suitably tailored control pulses. AU - Kosarev, Alexander N. AU - Rose, Hendrik AU - Poltavtsev, Sergey V. AU - Reichelt, Matthias AU - Schneider, Christian AU - Kamp, Martin AU - Höfling, Sven AU - Bayer, Manfred AU - Meier, Torsten AU - Akimov, Ilya A. ID - 20773 IS - 1 JF - Communications Physics SN - 2399-3650 TI - Accurate photon echo timing by optical freezing of exciton dephasing and rephasing in quantum dots VL - 3 ER - TY - JOUR AB - Vortices are topological objects representing the circular motion of a fluid. With their additional degree of freedom, the vorticity, they have been widely investigated in many physical systems and different materials for fundamental interest and for applications in data storage and information processing. Vortices have also been observed in non-equilibrium exciton-polariton condensates in planar semiconductor microcavities. There they appear spontaneously or can be created and pinned in space using ring-shaped optical excitation profiles. However, using the vortex state for information processing not only requires creation of a vortex but also efficient control over the vortex after its creation. Here we demonstrate a simple approach to control and switch a localized polariton vortex between opposite states. In our scheme, both the optical control of vorticity and its detection through the orbital angular momentum of the emitted light are implemented in a robust and practical manner. AU - Meier, Torsten AU - Ma, Xuekai AU - Berger, Bernd AU - Aßmann, Marc AU - Driben, Rodislav AU - Schneider, Christian AU - Höfling, Sven AU - Schumacher, Stefan ID - 43747 IS - 1 JF - Nature communications TI - Realization of all-optical vortex switching in exciton-polariton condensates VL - 11 ER - TY - CONF AU - Hannes, Wolf-Rüdiger AU - Meier, Torsten ED - Betz, Markus ED - Elezzabi, Abdulhakem Y. ID - 20770 SN - 9781510633193 T2 - Ultrafast Phenomena and Nanophotonics XXIV TI - k.p-based multiband simulations of non-degenerate two-photon absorption in bulk GaAs VL - 11278 ER - TY - JOUR AU - Hannes, W.-R. AU - Trautmann, Alexander AU - Stein, M. AU - Schäfer, F. AU - Koch, M. AU - Meier, Torsten ID - 20563 IS - 7 JF - Physical Review B TI - Strongly nonresonant four-wave mixing in semiconductors VL - 101 ER - TY - JOUR AU - Song, Xiaohong AU - Yang, Shidong AU - Zuo, Ruixin AU - Meier, Torsten AU - Yang, Weifeng ID - 20772 JF - Physical Review A SN - 2469-9926 TI - Enhanced high-order harmonic generation in semiconductors by excitation with multicolor pulses VL - 101 ER - TY - JOUR AU - Bocchini, Adriana AU - Eigner, Christof AU - Silberhorn, Christine AU - Schmidt, Wolf Gero AU - Gerstmann, Uwe ID - 20682 JF - Phys. Rev. Materials TI - Understanding gray track formation in KTP: Ti^3+ centers studied from first principles VL - 4 ER - TY - CONF AU - Müller, Inez ID - 44159 SN - 978-3-86205-600-2 TI - Generationelle und gesellschaftliche Differenzen im wiedervereinigten Deutschland - "Der neunzigste Geburtstag. Ein ländliches Idyll" von Günter de Bruyn in postkolonialer Lesart. VL - 11 ER - TY - JOUR AU - Müller, Inez ID - 44160 JF - Peter Weiss Jahrbuch SN - 978-3-86110-748-4 TI - Transmediale und transkulturelle Schreibweisen im Exil der Gegenwart - Prosa und Lyrik syrischer Autoren in Europa VL - 28 ER - TY - CHAP AU - Moritzer, Elmar AU - Hüttner, M. AU - Henning, Bernd AU - Webersen, Manuel ID - 24479 T2 - Advances in Polymer Processing 2020 TI - The Influence of Hydrothermal Aging on the Material Properties of Continuous Fiber-Reinforced Thermoplastics and its Non-Destructive Characterization ER - TY - JOUR AU - Grabo, Matti AU - Staggenborg, Christoph AU - Philippi, Kai Alexander AU - Kenig, Eugeny ID - 22266 JF - Frontiers in Energy Research SN - 2296-598X TI - Modeling and Optimization of Rectangular Latent Heat Storage Elements in an Air-Guided Heat Storage System VL - 8 ER - TY - JOUR AB - The influence of latent heat storage elements on the cooling performance and the temperature rise time of household refrigerating appliances is studied experimentally in the context of the “new global refriger- ator standard”IEC 62552:2015. In addition to the daily energy consumption, this international standard- ization introduced performance tests for cooling capacity and temperature rise time. While the cooling capacity has long been anchored in various test procedures of consumer organizations, the temperature rise time, which has only been tested on freezers so far, will be a decisive factor in the future. Moreover, the need for so-called "smart appliances" that may balance power consumption is increasing since such devices may compensate the volatility of renewable energies and thus stabilize the power grid. Against this background, eight commercial household refrigerators and refrigerator-freezers are equipped with polymer-bound phase change materials (PCM) and their performance is determined under the new stan- dard test conditions. The results show that the introduction of PCM increases the cooling capacity by up to 33 % and also increases the temperature rise time by up to 145 %, without affecting power consump- tion, as compared to the unmodified refrigeration appliances. AU - Sonnenrein, Gerrit AU - Baumhögger, Elmar AU - Elsner, Andreas AU - Morbach, A. AU - Neukötter, Moritz AU - Paul, Andreas AU - Vrabec, J. ID - 21514 JF - International Journal of Refrigeration SN - 0140-7007 TI - Improving the performance of household refrigerating appliances through the integration of phase change materials in the context of the new global refrigerator standard IEC 62552:2015 VL - 119 ER - TY - JOUR AB - Despite the omnipresence of household refrigeration appliances, there is still a lack of knowledge about their agerelated efficiency loss over time. Past studies provide basic evidence for increasing electricity consumption of cooling appliances with ageing but fail to investigate the associated technical wear. Concentrating on the degradation of the thermal insulation, we first determined the ageing process of sealed samples of polyurethane rigid foam by investigating changes in cell gas composition and thermal conductivity over time. Simultaneously, the main challenge was to develop an approach that investigates the age-related efficiency loss of the insulation without its destruction. This testing procedure is referred to as the Bonn method. The non-destructive Bonn method was applied to varying refrigerator models in a series of successive experiments to evaluate the insulation degradation over time. Subsequently, the physical relationship between the test value of the Bonn method and the heat transfer through the multi-layered compartment walls of domestic refrigeration appliances was established, ultimately characterising the degrading insulation in terms of increasing heat transfer. Our results give substantiated evidence that the efficiency loss of cooling appliances is greatly influenced by insulation degradation over time. The ageing of sealed samples of polyurethane rigid foam indicates a large initial increase of thermal conductivity by 15% within the first year, corresponding to a change in cell gas composition. These results are in line with those of the Bonn method, emphasising an increasing heat flow through the multi-layered compartment walls of domestic refrigerators with ageing. Therewith, the present study is of significance to a wide range of stakeholders and forms the basis for future research. AU - Hueppe, Christian AU - Geppert, Jasmin AU - Stamminger, Rainer AU - Wagner, Hendrik AU - Hoelscher, Heike AU - Vrabec, Jadran AU - Paul, Andreas AU - Elsner, Andreas AU - Becker, Wolfgang AU - Gries, Ulrich AU - Freiberger, Alfred ID - 21512 JF - Applied Thermal Engineering SN - 1359-4311 TI - Age-related efficiency loss of household refrigeration appliances: Development of an approach to measure the degradation of insulation properties VL - 173 ER - TY - GEN AB - Due to the trend towards lightweight design in car body development mechanical joining technologies become increasingly important. These techniques allow for the joining of dissimilar materials and thus enable multi-material design, while thermic joining methods reach their limits. Semi-tubular self-piercing riveting is an important mechanical joining technology. The rivet production, however, is costly and time-consuming, as the process consists of several process steps including the heat treatment and coating of the rivets in order to achieve an adequate strength and corrosion resistance. The use of high nitrogen steel as rivet material leads to the possibility of reducing process steps and hence increasing the efficiency of the process. However, the high tool loads being expected due to the high strain hardening of the material are a major challenge during the rivet production. Thus, there is a need for appropriate forming strategies, such as the manufacturing of the rivets at elevated temperatures. Prior investigations led to the conclusion that forming already at 200 °C results in a distinct reduction of the yield strength. To create a deeper understanding of the forming behaviour of high nitrogen steel at elevated temperatures, compression tests were conducted in a temperature range between room temperature and 200 °C. The determined true stress – true strain curves are the basis for the further process and tool design of the rivet production. Another key factor for the rivet manufacturing at elevated temperatures is the influence of the process temperature on the tribological conditions. For this reason, ring compression tests at room temperature and 200 °C are carried out. The friction factors are determined on the basis of calibration curves resulting from the numerical analysis of the ring compression process. The investigations indicate that the friction factor at 200 °C is significantly higher compared to room temperature. This essential fact has to be taken into account for the process and tool design for the rivet production using high nitrogen steel. ED - Kuball, Clara-Maria ED - Jung, R ED - Uhe, Benedikt ED - Meschut, Gerson ED - Merklein, Marion ID - 19974 KW - High nitrogen steel KW - Self-piercing riveting KW - Joining by forming KW - Bulk forming KW - Strain hardening TI - Influence of the process temperature on the forming behaviour and the friction during bulk forming of high nitrogen steel VL - 1 ER - TY - JOUR AB - As a result of lightweight design, increased use is being made of high-strength steel and aluminium in car bodies. Self-piercing riveting is an established technique for joining these materials. The dissimilar properties of the two materials have led to a number of different rivet geometries in the past. Each rivet geometry fulfils the requirements of the materials within a limited range. In the present investigation, an improved rivet geometry is developed, which permits the reliable joining of two material combinations that could only be joined by two different rivet geometries up until now. Material combination 1 consists of high-strength steel on both sides, while material combination 2 comprises aluminium on the punch side and high-strength steel on the die side. The material flow and the stress and strain conditions prevailing during the joining process are analysed by means of numerical simulation. The rivet geometry is then improved step-by-step on the basis of this analysis. Finally, the improved rivet geometry is manufactured and the findings of the investigation are verified in experimental joining tests. AU - Uhe, Benedikt AU - Kuball, Clara-Maria AU - Merklein, Marion AU - Meschut, Gerson ID - 19973 JF - Production Engineering KW - Self-piercing riveting KW - Joining technology KW - Rivet geometry KW - Multi-material design KW - High-strength steel KW - Aluminium TI - Improvement of a rivet geometry for the self-piercing riveting of high-strength steel and multi-material joints VL - 14 ER - TY - JOUR AU - Tinkloh, Steffen Rainer AU - Wu, Tao AU - Tröster, Thomas AU - Niendorf, Thomas ID - 15945 JF - Composite Structures SN - 0263-8223 TI - A micromechanical-based finite element simulation of process-induced residual stresses in metal-CFRP-hybrid structures VL - 238 ER - TY - JOUR AU - Martin, Sven AU - Camberg, Alan A. AU - Tröster, Thomas ID - 16859 JF - Procedia Manufacturing SN - 2351-9789 TI - Probability Distribution of Joint Point Loadings in Car Body Structures under Global Bending and Torsion ER - TY - CONF AU - Bertling, René AU - Hack, Mathias AU - Ausner, Ilja AU - Kenig, Eugeny ID - 23409 TI - CFD Simulation of Film and Rivulet Flows on Microstructured Surfaces ER - TY - CONF AU - Rozo Vasquez, Julian AU - Arian, Bahman AU - Riepold, Markus AU - Homberg, Werner AU - Trächtler, Ansgar AU - Walther, Frank ID - 22965 T2 - 54. Metallographie-Tagung TI - Microstructural investigation on phase transformation during flow forming of the metastable austenite AISI 304 ER - TY - JOUR AU - Ma, Xuekai AU - Berger, B AU - Aßmann, M AU - Driben, R AU - Meier, Torsten AU - Schneider, C AU - Höfling, S AU - Schumacher, Stefan ID - 20580 IS - 1 JF - Nature Communications SN - 2041-1723 TI - Realization of all-optical vortex switching in exciton-polariton condensates VL - 11 ER - TY - JOUR AU - Ahrens, Stephan ID - 44371 IS - Nr. 1 JF - Journal of Italian Cinema & Media Studies 9, Nr. 1 TI - Federico Fellini’s Sanctifying Effect. ER - TY - BOOK AU - Ahrens, Stephan ID - 44365 TI - Vom Klang bewegt. Das Kino und Ludwig van Beethoven. ER - TY - JOUR AU - Ahrens, Stephan ID - 44393 JF - Dschungel (jungle World) TI - Offensive Sensation. Ein Porträt von Melina Mercouri ER - TY - GEN AU - Ahrens, Stephan ID - 44395 T2 - in die tageszeitung TI - Glücklich ohne Happy End ER - TY - GEN AU - Ahrens, Stephan ID - 44396 T2 - Dschungel (Jungle World) TI - Das Stadtgespräch ER - TY - GEN AU - Ahrens, Stephan ID - 44394 TI - In memoriam Sarah Maldoror ER -