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 -