TY - JOUR AB - Academics may actively respond to the expectations of the academic status market, which have largely been shaped by the World University Rankings (WURs). This study empirically examines how academics’ citation patterns have changed in response to the rise of an “evaluation environment” in academia. We regard the WURs to be a macro-level trigger for cementing a bibliometric-based evaluation environment in academia. Our analyses of citation patterns in papers published in two higher education journals explicitly considered three distinct periods: the pre-WURs (1990–2003), the period of WURs implementation (2004–2010), and the period of adaption to WURs (2011–2017). We applied the nonparametric Kaplan–Meier method to compare first-citation speeds of papers published across the three periods. We found that not only has first-citation speed become faster, but first-citation probability has also increased following the emergence of the WURs. Applying Cox proportional hazard models to first-citation probabilities, we identified journal impact factors and third-party funding as factors influencing first-citation probability, while other author- and paper-related factors showed limited effects. We also found that the general effects of different factors on first-citation speeds have changed with the emergence of the WURs. The findings expand our understanding of the citation patterns of academics in the rise of WURs and provide practical grounds for research policy as well as higher education policy. AU - Lee, Soo Jeung AU - Schneijderberg, Christian AU - Kim, Yangson AU - Steinhardt, Isabel ID - 33372 IS - 17 JF - Sustainability KW - world university rankings KW - citation KW - first-citation speed KW - Minerva KW - Studies in Higher Education SN - 2071-1050 TI - Have Academics’ Citation Patterns Changed in Response to the Rise of World University Rankings? A Test Using First-Citation Speeds VL - 13 ER - TY - JOUR AB - There is a distinct increase in the prevalence of depression with the onset of puberty. The role of peripubertal testosterone levels in boys in this context is insufficiently understood and may be modulated by a functional polymorphism of the androgen receptor gene (AR), a variable number of CAG repeats. Moreover, there is preliminary evidence that the relationship between testosterone, CAG repeat length, and the severity of depressive symptoms may differ between subclinical and overt depression, but this has neither been studied in a clinical sample of adolescents with depression nor compared between subclinical and overt depression in an adequately powered study. To investigate the relationship between free testosterone, CAG repeat length of the AR, depression status (subclinical vs. overt), and the severity of depressive symptoms, 118 boys treated as in- or daycare patients at a single psychiatric hospital were studied. Of these, 73 boys had at least mild depressive symptoms according to the Beck Depression Inventory-II (BDI-II > 13). Higher-order moderation analysis in the multiple regression framework revealed a constant relationship between free testosterone and depression severity irrespective of the number of CAG repeats in adolescents with a BDI-II score ≤ 13. In adolescents with a BDI-II score > 13, however, there was a significant negative relationship between free testosterone and BDI-II score in patients with <19 CAG repeats and a significant positive relationship regarding free testosterone and BDI-II score in those with more than 28 CAG repeats, even when considering important covariates. These results suggest that the effects of testosterone on mood in male adolescents with depression depend on the genetic make-up of the AR as well as on depression status. This complex relationship should be considered by future studies addressing mental health issues against an endocrine background and may, moreover, contribute to tailored treatment concepts in psychiatric medicine, especially in adults. AU - Hirtz, Raphael AU - Libuda, Lars AU - Hinney, Anke AU - Föcker, Manuel AU - Bühlmeier, Judith AU - Holterhus, Paul-Martin AU - Kulle, Alexandra AU - Kiewert, Cordula AU - Hebebrand, Johannes AU - Grasemann, Corinna ID - 27575 JF - Frontiers in Psychiatry SN - 1664-0640 TI - Size Matters: The CAG Repeat Length of the Androgen Receptor Gene, Testosterone, and Male Adolescent Depression Severity ER - TY - JOUR AB - (1) Background: Evidence has accumulated that patients with anorexia nervosa (AN) are at higher risk for vitamin D deficiency than healthy controls. In epidemiologic studies, low 25(OH) vitamin D (25(OH)D) levels were associated with depression. This study analyzed the relationship between 25(OH)D serum levels in adolescent patients and AN and depressive symptoms over the course of treatment. (2) Methods: 25(OH)D levels and depressive symptoms were analyzed in 93 adolescent (in-)patients with AN from the Anorexia Nervosa Day patient versus Inpatient (ANDI) multicenter trial at clinic admission, discharge, and 1 year follow up. Mixed regression models were used to analyze the relationship between 25(OH)D levels and depressive symptoms assessed by the Beck Depression Inventory (BDI-II). (3) Results: Although mean 25(OH)D levels constantly remained in recommended ranges (≥50 nmol/L) during AN treatment, levels decreased from (in)patient admission to 1 year follow up. Levels of 25(OH)D were neither cross-sectionally, prospectively, nor longitudinally associated with the BDI-II score. (4) Conclusions: This study did not confirm that 25(OH)D levels are associated with depressive symptoms in patients with AN. However, increasing risks of vitamin D deficiency over the course of AN treatment indicate that clinicians should monitor 25(OH)D levels. AU - Föcker, Manuel AU - Timmesfeld, Nina AU - Bühlmeier, Judith AU - Zwanziger, Denise AU - Führer, Dagmar AU - Grasemann, Corinna AU - Ehrlich, Stefan AU - Egberts, Karin AU - Fleischhaker, Christian AU - Wewetzer, Christoph AU - Wessing, Ida AU - Seitz, Jochen AU - Herpertz-Dahlmann, Beate AU - Hebebrand, Johannes AU - Libuda, Lars ID - 27571 JF - Nutrients SN - 2072-6643 TI - Vitamin D Level Trajectories of Adolescent Patients with Anorexia Nervosa at Inpatient Admission, during Treatment, and at One Year Follow Up: Association with Depressive Symptoms ER - TY - JOUR AB - AbstractAnorexia nervosa (AN) is a severe eating disorder and often associated with altered humoral immune responses. However, distinct B cell maturation stages in peripheral blood in adolescents with AN have not been characterized. Treatment effects and the relationship between clinical and B cell parameters are also not fully understood. Here we investigated the phenotype of circulating B cell subsets and the relationship with body composition in adolescents with AN before (T0, n = 24) and after 6 weeks (T1, n = 20) of treatment. Using multi-parameter flow cytometry, we found increased percentages of antigen-experienced B cells and plasmablasts in patients with AN compared to healthy controls (n = 20). In contrast, percentages of CD1d+CD5+ B cells and transitional B cells with immunoregulatory roles were reduced at T0 and T1. These B cell frequencies correlated positively with fat mass, fat mass index (FMI), free fat mass index, and body mass index standard deviation score. In addition, scavenger-like receptor CD5 expression levels were downregulated on transitional B cells and correlated with fat mass and FMI in AN. Our findings that regulatory B cell subgroups were reduced in AN and their strong relationship with body composition parameters point toward an impact of immunoregulatory B cells in the pathogenesis of AN. AU - Freff, Jana AU - Schwarte, Kathrin AU - Bröker, Lisa AU - Bühlmeier, Judith AU - Kraft, Isabelle AU - Öztürk, Dana AU - Hinney, Anke AU - Arolt, Volker AU - Dannlowski, Udo AU - Romer, Georg AU - Baune, Bernhard T. AU - Hebebrand, Johannes AU - Föcker, Manuel AU - Alferink, Judith ID - 26632 JF - Scientific Reports SN - 2045-2322 TI - Alterations in B cell subsets correlate with body composition parameters in female adolescents with anorexia nervosa ER - TY - JOUR AU - Hebebrand, Johannes AU - Antel, Jochen AU - Tan, Susanne AU - Wabitsch, Martin AU - Wiesing, Urban AU - Barth, Nikolaus AU - Ludwig, Christine AU - Bühlmeier, Judith AU - Libuda, Lars AU - Milos, Gabriella AU - Hinney, Anke ID - 26525 JF - Zeitschrift für Kinder- und Jugendpsychiatrie und Psychotherapie SN - 1422-4917 TI - Kurzzeitige Behandlung von Patient_innen mit Anorexia nervosa mit rekombinant hergestelltem Human-Leptin (Metreleptin): Rasch einsetzende positive Effekte auf Stimmung, Kognition und Verhalten ER - TY - JOUR AU - Kißling, Magdalena ID - 33410 JF - Der Deutschunterrich (2) TI - Vom ‚Komaglotzen‘ zum literar- und medienästhetischen Lernen. Konzeptualisierung eines fernsehseriellen Lehr-Lern-Settings am Beispiel des Teen Dramas ANNE WITH AN E. ER - TY - CHAP AU - Kißling, Magdalena ED - Dembeck, Till ED - Pavlik, Jennifer ID - 33419 T2 - Medienwissenschaften und Mediendidaktik im Dialog – Zum Status Quo von Medienbildung im Deutschunterricht TI - Intermedialer Literaturunterricht. Ein medienintegratives Differenzierungskonzept zur Förderung literarästhetischen Lernens am Beispiel ausgewählter Kinderromane für die Sekundarstufe I ER - TY - CHAP AU - Kißling, Magdalena ID - 33420 T2 - Kinder- und Jugendliteratur intermedial. Unterrichtsanregungen und -materialien zum literarischen Lernen im Medienverbund anhand von Emil und die Detektive (Gym/Ge) und Jakob der Lügner (BK). Erstellt von Masterstudierenden der Universität Paderborn TI - Einleitung ER - TY - CHAP AU - Öhlschläger, Claudia AU - Schneider, Martin ED - Steigerwald, Jörn ID - 32898 T2 - Komparatistik heute. Aktuelle Positionen der Vergleichenden Literatur- und Kulturwissenschaft TI - Passivität als Widerstand gegen die Macht der Verhältnisse? "Bartleby, the scrivener" aus literaturwissenschaftlicher und ökonomischer Perspektive ER - TY - CHAP AU - Knickenberg, Margarita AU - Stöcker, A AU - Zurbriggen, Carmen ED - Resch, K ED - Lindner, K.-T. ED - Streese, B ED - Proyer, M ED - Schwab, S ID - 33433 T2 - Inklusive Schule und Schulentwicklung Theoretische Grundlagen, empirische Befunde und Praxisbeispiele aus Deutschland, Österreich und der Schweiz. TI - Inklusives Klassenklima. Zur Bedeutung der sozialen Dimension des Klassenklimas unter Berücksichtigung von Heterogenität ER - TY - CHAP AU - Knickenberg, Margarita AU - Zurbriggen, Carmen ED - Hagenauer, G ED - Raufelder, D ID - 33434 T2 - G. Hagenauer & D. Raufelder (Hrsg.), Soziale Eingebundenheit. Sozialbeziehungen im Fokus von Schule und Lehrer*innenbildung TI - Die Bedeutsamkeit von Peers für Jugendliche in der Sekundarstufe und in der Freizeit ER - TY - JOUR AU - Martin, A. AU - Herzig, Bardo ID - 33465 IS - 1 JF - Pädagogik Unterricht: Die Fachzeitschrift für die pädagogische Fächergruppe TI - Pädagogikunterricht und Digitalisierung: fachliches Lernen digital und digitales Lernen fachlich denken ER - TY - BOOK AU - Tulodziecki, G. AU - Herzig, Bardo AU - Grafe, S. ID - 33464 SN - 978-3-825-257460 TI - Medienbildung in Schule und Unterricht ER - TY - JOUR AU - Herzig, Bardo ID - 33462 IS - 23 JF - SchulVerwaltung spezial TI - Wie wirksam ist das Lernen mit digitalen Medien? Einblicke in den Stand der Forschung ER - TY - GEN AU - Bothe, Mike AU - Lutters, Nicole AU - Kenig, Eugeny Y. ID - 28212 TI - Examination of hazardous situations in industrial closed-loop processes using dynamic simulations ER - TY - GEN AU - Bothe, Mike AU - Lutters, Nicole AU - Kenig, Eugeny Y. ID - 22461 TI - Dynamic simulation of hazardous situations in industrial closed loop processes considering chemical absorption ER - TY - CONF AU - Markewitz, Friedrich ED - Hünecke, Rainer ID - 32701 T2 - Intertextualität. Vom Zitat zur Anspielung in Texten der deutschen Sprache vom 8. bis zum 19. Jahrhundert TI - Die Bedeutung von Intertextualität für die Beschreibung der historischen Textsorte Schulprogramm. Zu Text-Text- sowie Text-Textwelt-Beziehungen ER - TY - JOUR AU - Glowania, M AU - Lassmann, I AU - Ulrich, Tanja ID - 33314 IS - 2 JF - Praxis Sprache TI - Umsetzbarkeit des Wortschatzsammler-Therapiekonzepts bei Kindern mit Trisomie 21. Eine qualitative Einzelfallstudie VL - 66 ER - TY - JOUR AU - Ulrich, Tanja AU - Thater, S AU - Mennicken, S ID - 33313 IS - 2 JF - Logos TI - Kasusfähigkeiten mehrsprachiger Achtjähriger. Eine explorative Pilotstudie in Regelgrundschulen VL - 29 ER - TY - JOUR AB - While 2D Gibbsian particle systems might exhibit orientational order resulting in a lattice-like structure, these particle systems do not exhibit positional order if the interaction between particles satisfies some weak assumptions. Here we investigate to which extent particles within a box of size may fluctuate from their ideal lattice position. We show that particles near the center of the box typically show a displacement at least of order . Thus we extend recent results on the hard disk model to particle systems with fairly arbitrary particle spins and interaction. Our result applies to models such as rather general continuum Potts type models, e.g. with Widom–Rowlinson or Lenard-Jones-type interaction. AU - Richthammer, Thomas AU - Fiedler, Michael ID - 33481 JF - Stochastic Processes and their Applications TI - A lower bound on the displacement of particles in 2D Gibbsian particle systems VL - 132 ER - TY - GEN AB - Consider a set of jobs connected to a directed acyclic task graph with a fixed source and sink. The edges of this graph model precedence constraints and the jobs have to be scheduled with respect to those. We introduce the Server Cloud Scheduling problem, in which the jobs have to be processed either on a single local machine or on one of many cloud machines. Both the source and the sink have to be scheduled on the local machine. For each job, processing times both on the server and in the cloud are given. Furthermore, for each edge in the task graph, a communication delay is included in the input and has to be taken into account if one of the two jobs is scheduled on the server, the other in the cloud. The server can process jobs sequentially, whereas the cloud can serve as many as needed in parallel, but induces costs. We consider both makespan and cost minimization. The main results are an FPTAS with respect for the makespan objective for a fairly general case and strong hardness for the case with unit processing times and delays. AU - Maack, Marten AU - Meyer auf der Heide, Friedhelm AU - Pukrop, Simon ID - 27778 T2 - arXiv:2108.02109 TI - Full Version -- Server Cloud Scheduling ER - TY - BOOK ED - Schlieper, Hendrik ED - Tönnies, Merle ID - 33093 TI - Gattung und Geschlecht. Konventionen und Transformationen eines Paradigmas ER - TY - CHAP AU - Süwolto, Leonie ED - Schlieper, Hendrik ED - Tönnies, Merle ID - 33163 T2 - Gattung und Geschlecht. Konventionen und Transformationen eines Paradigmas TI - Gattung und Geschlecht. Weibliche Tragödienheldinnen in Lessings Emilia Galotti? ER - TY - CHAP AU - Süwolto, Leonie ID - 33174 T2 - blog interdisziplinäre geschlechterforschung TI - Moderne Heldin im antiken Gewand? Anne Webers „Annette, ein Heldinnenepos“ ER - TY - CHAP AU - Süwolto, Leonie ED - Benthien , Claudia ED - von Flemming, Victoria ID - 33162 T2 - Vanitas und Gesellschaft TI - Topographien der Vergänglichkeit. Vanitas, Alter und Gesellschaft bei Monika Maron und Martin Walser ER - TY - CHAP AU - Schlieper, Hendrik ID - 33133 T2 - Komparatistik heute. Aktuelle Positionen der Vergleichenden Literatur- und Kulturwissenschaft TI - Einleitung ER - TY - CHAP AU - Schlieper, Hendrik ID - 33132 T2 - Komparatistik heute. Aktuelle Positionen der Vergleichenden Literatur- und Kulturwissenschaft TI - Genealogische Spuren in Racines Phèdre ER - TY - CHAP AU - Schlieper, Hendrik ED - Tönnies, Merle ID - 33131 T2 - Gattung und Geschlecht. Konventionen und Transformationen eines Paradigmas. (culturae, 21) TI - Helden-Geschlechter: Die Bérénice-Tragödien Corneilles und Racines ER - TY - CHAP AU - Schlieper, Hendrik ED - Gallo , Pierino ED - Mullet-Blandin, Isabelle ID - 33128 T2 - Amérique(s) poétique(s) entre Ancien et Nouveau Monde. L’espace américain comme nouveau territoire de la fiction de Fontenelle à Chateaubriand. Révolutions et Romantismes, 27) TI - Tendres conquêtes: l’Amérique galante selon Rameau et Fuzelier (Les Indes galantes, 1735) ER - TY - CHAP AU - Schlieper, Hendrik ED - Tönnies, Merle ID - 33129 T2 - Gattung und Geschlecht. Konventionen und Transformationen eines Paradigmas TI - Gattung und Geschlecht: Überlegungen zu einem kulturstiftenden Paradigma ER - TY - JOUR AU - Schlieper, Hendrik ID - 33104 JF - Corneille présent, 1 TI - Sophonisbe: alea et agôn, genre tragique et gender. Les en-jeux diversifiés de la politique et de l’amour ER - TY - BOOK ED - Schlieper, Hendrik ID - 33094 TI - Komparatistik heute. Aktuelle Positionen der Vergleichenden Literatur- und Kulturwissenschaft ER - TY - CHAP AU - Steigerwald, Jörn ID - 32747 T2 - Komparatistik heute. Aktuelle Positionen der vergleichenden Literatur- und Kulturwissenschaft TI - James Bond - mit Vergil gesehen: "Dr. No" (1962) ER - TY - CHAP AU - Steigerwald, Jörn ED - Ubbidiente, Roberto ID - 32729 T2 - L’“Adone“ di Giovan Battista Marino. Mito - Movimento - Maraviglia. Atti del convegno internazionale (Humboldt-Universität zu Berlin, 1-2 luglio 2019) TI - La tragedia amorosa dell'"Adone" ossia il nuovo ordinamento dell’amore ER - TY - JOUR AU - Steigerwald, Jörn ID - 32622 JF - Corneille présent n° 1, 2021, Corneille: un théâtre où la vie est un jeu TI - Corneille maître du jeu ou la dramatologie novatrice de „Rodogune" ER - TY - JOUR AU - Steigerwald, Jörn ID - 32623 JF - Literaturwissenschaftliches Jahrbuch 62 TI - Von der Liebestragödie zur Tragödie der Liebe: Jean Racines „Phèdre" ER - TY - BOOK ED - Rezat, Sara ED - Feilke, Helmuth ID - 33530 TI - Erklärtexte lesen und schreiben. Praxis Deutsch 285 ER - TY - JOUR AU - Rezat, Sara AU - Feilke, Helmuth ID - 33569 JF - Sprach(en)erwerb. Der Deutschunterricht. Koch, Nikolas/Kozikowski, Barbara (Hrsg.) TI - Textprozeduren und der Erwerb literaler Kompetenz ER - TY - JOUR AB - Abstract We performed a virtual materials screening to identify promising topological materials for photocatalytic water splitting under visible light irradiation. Topological compounds were screened based on band gap, band edge energy, and thermodynamics stability criteria. In addition, topological types for our final candidates were computed based on electronic structures calculated usingthe hybrid density functional theory including exact Hartree–Fock exchange. Our final list contains materials which have band gaps between 1.0 and 2.7 eV in addition to band edge energies suitable for water oxidation and reduction. However, the topological types of these compounds calculated with the hybrid functional differ from those reported previously. To that end, we discuss the importance of computational methods for the calculation of atomic and electronic structures in materials screening processes. AU - Ranjbar, Ahmad AU - Mirhosseini, Hossein AU - Kühne, Thomas D ID - 33587 IS - 1 JF - Journal of Physics: Materials KW - Condensed Matter Physics KW - General Materials Science KW - Atomic and Molecular Physics KW - and Optics SN - 2515-7639 TI - On topological materials as photocatalysts for water splitting by visible light VL - 5 ER - TY - CHAP AU - Rezat, Sara ED - Schicker, Stephan ED - Schmölzer-Eibinger, Sabine ID - 33588 T2 - ar|gu|men|tie|ren. Eine zentrale Sprachhandlung im Fach- und Sprachunterricht TI - Zur makrostrukturellen Prägung argumentierender Textprozeduren ER - TY - JOUR AU - Rezat, Sara AU - Arnold, Cynthia ID - 33591 JF - Praxis Deutsch 285 TI - Digitale Desinformation und Fake News. Schülerinnen und Schüler erklären, warum Fake News sich so gut verbreiten ER - TY - JOUR AU - Rezat, Sara AU - Feilke, Helmuth ID - 33590 JF - Praxis Deutsch 285 TI - Erklärtexte lesen und schreiben. Basisartikel ER - TY - JOUR AB - The origin of strong interactions between water molecules and porous C2N surfaces is investigated by using a combination of model materials, volumetric physisorption measurements, solid-state NMR spectroscopy, and DFT calculations. AU - Heske, Julian Joachim AU - Walczak, Ralf AU - Epping, Jan D. AU - Youk, Sol AU - Sahoo, Sudhir K. AU - Antonietti, Markus AU - Kühne, Thomas AU - Oschatz, Martin ID - 33643 IS - 39 JF - Journal of Materials Chemistry A KW - General Materials Science KW - Renewable Energy KW - Sustainability and the Environment KW - General Chemistry SN - 2050-7488 TI - When water becomes an integral part of carbon – combining theory and experiment to understand the zeolite-like water adsorption properties of porous C2N materials VL - 9 ER - TY - JOUR AB - AbstractVibrational sum-frequency generation (vSFG) spectroscopy allows the study of the structure and dynamics of interfacial systems. In the present work, we provide a simple recipe, based on a narrowband IR pump and broadband vSFG probe technique, to computationally obtain the two-dimensional vSFG spectrum of water molecules at the air–water interface. Using this technique, to study the time-dependent spectral evolution of hydrogen-bonded and free water molecules, we demonstrate that at the interface, the vibrational spectral dynamics of the free OH bond is faster than that of the bonded OH mode. AU - Ojha, Deepak AU - Kühne, Thomas ID - 33645 IS - 1 JF - Scientific Reports KW - Multidisciplinary SN - 2045-2322 TI - Hydrogen bond dynamics of interfacial water molecules revealed from two-dimensional vibrational sum-frequency generation spectroscopy VL - 11 ER - TY - JOUR AU - Pylaeva, Svetlana AU - Marx, Patrick AU - Singh, Gurjot AU - Kühne, Thomas AU - Roemelt, Michael AU - Elgabarty, Hossam ID - 33644 IS - 3 JF - The Journal of Physical Chemistry A KW - Physical and Theoretical Chemistry SN - 1089-5639 TI - Organic Mixed-Valence Compounds and the Overhauser Effect in Insulating Solids VL - 125 ER - TY - JOUR AU - Kessler, Jan AU - Calcavecchia, Francesco AU - Kühne, Thomas ID - 33649 IS - 4 JF - Advanced Theory and Simulations KW - Multidisciplinary KW - Modeling and Simulation KW - Numerical Analysis KW - Statistics and Probability SN - 2513-0390 TI - Artificial Neural Networks as Trial Wave Functions for Quantum Monte Carlo VL - 4 ER - TY - JOUR AU - Ghasemi, Alireza AU - Kühne, Thomas ID - 33648 IS - 7 JF - The Journal of Chemical Physics KW - Physical and Theoretical Chemistry KW - General Physics and Astronomy SN - 0021-9606 TI - Artificial neural networks for the kinetic energy functional of non-interacting fermions VL - 154 ER - TY - JOUR AB - Abstract Dual-ion batteries are considered to be an emerging viable energy storage technology owing to their safety, high power capability, low cost, and scalability. Intercalation of anions into a graphite positive electrode provides high operating voltage and improved energy density to such dual-ion batteries. In this work, we have performed a combinatorial study of graphite intercalation compounds considering four anions, namely hexafluorophosphate (PF 6 ), perchlorate (ClO 4 ), bis(fluorosulfonyl)imide (FSI), and bis(trifluoromethanesulfonyl)imide (TFSI), via first-principles calculations. The structural properties and energetics of the intercalation compounds are compared based on different sizes, geometries, and the physical and chemical properties of the intercalated anions. The staging mechanism of anion intercalation into graphite and the specific capacities, and voltage profiles of the intercalated compounds are investigated. A comparison regarding battery electrochemistry is also done with available experimental observations. Our calculated intercalation energies and voltage profiles show that the initial anion intercalation into graphite is less favorable than subsequent ones for all the anions considered in this study. Although the effect of the size of anions in a graphite cathode on various properties of the intercalated compounds is not as significant as the size of cations in a graphite anode, some distinction between the studied anions can still be made. Among the studied anions, the intercalation compounds based on PF 6 are the most stable ones. These PF 6 anions cause relatively small structural deformations of the graphite and have the highest oxidative ability, highest onset voltage, and highest diffusion barrier along the graphene sheets. The overall small diffusion barriers of the anions within graphite explain the high rate capability of dual-ion batteries. AU - Chugh, Manjusha AU - Jain, Mitisha AU - Wang, Gang AU - Nia, Ali Shaygan AU - Mirhosseini, Hossein AU - Kühne, Thomas ID - 33655 IS - 8 JF - Materials Research Express KW - Metals and Alloys KW - Polymers and Plastics KW - Surfaces KW - Coatings and Films KW - Biomaterials KW - Electronic KW - Optical and Magnetic Materials SN - 2053-1591 TI - A combinatorial study of electrochemical anion intercalation into graphite VL - 8 ER - TY - JOUR AB - We demonstrate how to fully ascribe Raman peaks simulated using ab initio molecular dynamics to specific vibrations in the structure at finite temperatures by means of Wannier functions. Here, we adopt our newly introduced method for the simulation of the Raman spectra in which the total polarizability of the system is expressed as a sum over Wannier polarizabilities. The assignment is then based on the calculation of partial Raman activities arising from self- and/or cross-correlations between different types of Wannier functions in the system. Different types of Wannier functions can be distinguished based on their spatial spread. To demonstrate the predictive power of this approach, we applied it to the case of a cyclohexane molecule in the gas phase and were able to fully assign the simulated Raman peaks. AU - Partovi-Azar, Pouya AU - Kühne, Thomas ID - 33658 IS - 10 JF - Micromachines KW - Electrical and Electronic Engineering KW - Mechanical Engineering KW - Control and Systems Engineering SN - 2072-666X TI - Full Assignment of Ab-Initio Raman Spectra at Finite Temperatures Using Wannier Polarizabilities: Application to Cyclohexane Molecule in Gas Phase VL - 12 ER - TY - JOUR AU - Sahoo, Sudhir K. AU - Teixeira, Ivo F. AU - Naik, Aakash AU - Heske, Julian Joachim AU - Cruz, Daniel AU - Antonietti, Markus AU - Savateev, Aleksandr AU - Kühne, Thomas ID - 33651 IS - 25 JF - The Journal of Physical Chemistry C KW - Surfaces KW - Coatings and Films KW - Physical and Theoretical Chemistry KW - General Energy KW - Electronic KW - Optical and Magnetic Materials SN - 1932-7447 TI - Photocatalytic Water Splitting Reaction Catalyzed by Ion-Exchanged Salts of Potassium Poly(heptazine imide) 2D Materials VL - 125 ER - TY - JOUR AU - Mirhosseini, Hossein AU - Tahmasbi, Hossein AU - Kuchana, Sai Ram AU - Ghasemi, Alireza AU - Kühne, Thomas ID - 33657 JF - Computational Materials Science KW - Computational Mathematics KW - General Physics and Astronomy KW - Mechanics of Materials KW - General Materials Science KW - General Chemistry KW - General Computer Science SN - 0927-0256 TI - An automated approach for developing neural network interatomic potentials with FLAME VL - 197 ER - TY - CONF AU - Balos, Vasileios AU - Elgabarty, Hossam AU - Wolf, Martin AU - Kühne, Thomas AU - Netz, Roland AU - Bonthuis, Douwe Jan AU - Kaliannan, Naveen AU - Loche, Philip AU - Kampfrath, Tobias AU - Sajadi, Mohsen ED - Razeghi, Manijeh ED - Baranov, Alexei N. ID - 33654 T2 - Terahertz Emitters, Receivers, and Applications XII TI - Ultrafast solvent-to-solvent and solvent-to-solute energy transfer driven by single-cycle THz electric fields ER - TY - JOUR AU - Wang, Mengying AU - Ranjbar, Ahmad AU - Kühne, Thomas AU - Belosludov, Rodion V. AU - Kawazoe, Yoshiyuki AU - Liang, Yunye ID - 33656 JF - Carbon KW - General Chemistry KW - General Materials Science SN - 0008-6223 TI - A theoretical investigation of topological phase modulation in carbide MXenes: Role of image potential states VL - 181 ER - TY - JOUR AB - Abstract We performed a virtual materials screening to identify promising topological materials for photocatalytic water splitting under visible light irradiation. Topological compounds were screened based on band gap, band edge energy, and thermodynamics stability criteria. In addition, topological types for our final candidates were computed based on electronic structures calculated usingthe hybrid density functional theory including exact Hartree–Fock exchange. Our final list contains materials which have band gaps between 1.0 and 2.7 eV in addition to band edge energies suitable for water oxidation and reduction. However, the topological types of these compounds calculated with the hybrid functional differ from those reported previously. To that end, we discuss the importance of computational methods for the calculation of atomic and electronic structures in materials screening processes. AU - Ranjbar, Ahmad AU - Mirhosseini, Hossein AU - Kühne, Thomas ID - 33659 IS - 1 JF - Journal of Physics: Materials KW - Condensed Matter Physics KW - General Materials Science KW - Atomic and Molecular Physics KW - and Optics SN - 2515-7639 TI - On topological materials as photocatalysts for water splitting by visible light VL - 5 ER - TY - JOUR AB - AbstractVaccinations, lockdowns and testing strategies are three potential elements of an effective anti-coronavirus, and in particular Covid-19, health policy. The following analysis considers - within a simple model - the potentially crucial role of a Corona testing approach in combination with a quarantine approach which is shown herein to be a substitute for broad lockdown measures. The cost of lockdowns/shutdowns are rather high so that – beyond progress in terms of a broad vaccination program – a rational testing strategy should also be carefully considered. Testing has to be organized on the basis of an adequate testing infrastructure which could largely be implemented in firms, schools, universities and public administration settings. As regards the cost of a systematic broad Covid-19 testing strategy, these could come close to 0.5% of national income if there are no vaccinations. The Testing & Quarantine approach suggested here – with tests for symptomatic as well as asymptomatic people - is based on a random sampling and would require rather broad and frequent testing; possibly one test per person every 7–10 days. At the same time, one should consider that the cost of further lockdowns/shutdowns of a duration of 1 month could be very high, such that a standard cost benefit analysis supports the testing approach suggested herein. Also, an optimal policy mix could be designed where both vaccinations and testing play a crucial role. As of late January 2021, no further lockdowns in Germany and other OECD countries would be necessary if a broad testing infrastructure can be established rather quickly. This in turn will reinforce economic optimism and help to jumpstart economic growth in Europe, the US and Asia in a solid way. The basic logic of the testing approach pointed out here for industrialized countries could also be applied in developing countries. The approach presented is complementary to the IMF analysis of Cherif/Hasanov. AU - Gries, Thomas AU - Welfens, Paul J. J. ID - 33668 IS - 1 JF - International Economics and Economic Policy KW - Economics and Econometrics SN - 1612-4804 TI - Testing as an approach to control the Corona epidemic dynamics and avoid lockdowns VL - 18 ER - TY - JOUR AB - AbstractIn light of the COVID-19 pandemic, we scrutinize what has been established in the literature on whether entrepreneurship can cause and resolve extreme events, the immediate and long-run impacts of extreme events on entrepreneurship, and whether extreme events can positively impact (some) entrepreneurship and innovation. Based on this, we utilize a partial equilibrium model to provide several conjectures on the impact of COVID-19 on entrepreneurship, and to derive policy recommendations for recovery. We illustrate that while entrepreneurship recovery will benefit from measures such as direct subsidies for start-ups, firms’ revenue losses, and loan liabilities, it will also benefit from aggregate demand-side support and income redistribution measures, as well as from measures that facilitate the innovation-response to the Keynesian supply-shock caused by the pandemic, such as access to online retail and well-functioning global transportation and logistics. AU - Gries, Thomas AU - Naudé, Wim ID - 33667 IS - 3 JF - Economics of Disasters and Climate Change KW - General Medicine SN - 2511-1280 TI - Extreme Events, Entrepreneurial Start-Ups, and Innovation: Theoretical Conjectures VL - 5 ER - TY - JOUR AU - da Silva, Marcos A.R. AU - Silva, Ingrid F. AU - Xue, Qi AU - Lo, Benedict T.W. AU - Tarakina, Nadezda V. AU - Nunes, Barbara N. AU - Adler, Peter AU - Sahoo, Sudhir K. AU - Bahnemann, Detlef W. AU - López-Salas, Nieves AU - Savateev, Aleksandr AU - Ribeiro, Caue AU - Kühne, Thomas AU - Antonietti, Markus AU - Teixeira, Ivo F. ID - 33681 JF - Applied Catalysis B: Environmental KW - Process Chemistry and Technology KW - General Environmental Science KW - Catalysis SN - 0926-3373 TI - Sustainable oxidation catalysis supported by light: Fe-poly (heptazine imide) as a heterogeneous single-atom photocatalyst VL - 304 ER - TY - JOUR AB - The influence of different polymer side chains on the vapor phase infiltration with TMA is investigated and supported by DFT-calculations. AU - Mai, Lukas AU - Maniar, Dina AU - Zysk, Frederik AU - Schöbel, Judith AU - Kühne, Thomas AU - Loos, Katja AU - Devi, Anjana ID - 33675 IS - 4 JF - Dalton Transactions KW - Inorganic Chemistry SN - 1477-9226 TI - Influence of different ester side groups in polymers on the vapor phase infiltration with trimethyl aluminum VL - 51 ER - TY - GEN AU - Wiecher, Carsten AU - Fischbach, Jannik AU - Greenyer, Joel AU - Vogelsang, Andreas AU - Wolff, Carsten AU - Dumitrescu, Roman ID - 27058 T2 - arXiv preprint TI - Integrated and Iterative Requirements Analysis and Test Specification: A Case Study at Kostal ER - TY - CONF AU - Zahera, Hamada Mohamed Abdelsamee AU - Heindorf, Stefan AU - Ngonga Ngomo, Axel-Cyrille ID - 29291 T2 - Proceedings of the 11th on Knowledge Capture Conference TI - ASSET: A Semi-supervised Approach for Entity Typing in Knowledge Graphs ER - TY - CHAP AU - Feldhans, Robert AU - Wilke, Adrian AU - Heindorf, Stefan AU - Shaker, Mohammad Hossein AU - Hammer, Barbara AU - Ngonga Ngomo, Axel-Cyrille AU - Hüllermeier, Eyke ID - 29292 SN - 0302-9743 T2 - Intelligent Data Engineering and Automated Learning – IDEAL 2021 TI - Drift Detection in Text Data with Document Embeddings ER - TY - CONF AB - Knowledge graph embedding research has mainly focused on the two smallest normed division algebras, $\mathbb{R}$ and $\mathbb{C}$. Recent results suggest that trilinear products of quaternion-valued embeddings can be a more effective means to tackle link prediction. In addition, models based on convolutions on real-valued embeddings often yield state-of-the-art results for link prediction. In this paper, we investigate a composition of convolution operations with hypercomplex multiplications. We propose the four approaches QMult, OMult, ConvQ and ConvO to tackle the link prediction problem. QMult and OMult can be considered as quaternion and octonion extensions of previous state-of-the-art approaches, including DistMult and ComplEx. ConvQ and ConvO build upon QMult and OMult by including convolution operations in a way inspired by the residual learning framework. We evaluated our approaches on seven link prediction datasets including WN18RR, FB15K-237 and YAGO3-10. Experimental results suggest that the benefits of learning hypercomplex-valued vector representations become more apparent as the size and complexity of the knowledge graph grows. ConvO outperforms state-of-the-art approaches on FB15K-237 in MRR, Hit@1 and Hit@3, while QMult, OMult, ConvQ and ConvO outperform state-of-the-approaches on YAGO3-10 in all metrics. Results also suggest that link prediction performances can be further improved via prediction averaging. To foster reproducible research, we provide an open-source implementation of approaches, including training and evaluation scripts as well as pretrained models. AU - Demir, Caglar AU - Moussallem, Diego AU - Heindorf, Stefan AU - Ngonga Ngomo, Axel-Cyrille ID - 29287 T2 - The 13th Asian Conference on Machine Learning, ACML 2021 TI - Convolutional Hypercomplex Embeddings for Link Prediction ER - TY - CONF AU - Nickchen, Tobias AU - Heindorf, Stefan AU - Engels, Gregor ID - 29294 T2 - 2021 IEEE Winter Conference on Applications of Computer Vision (WACV) TI - Generating Physically Sound Training Data for Image Recognition of Additively Manufactured Parts ER - TY - GEN AU - Heindorf, Stefan ID - 33733 TI - Automatically generating instructions from tutorials for search and user navigation ER - TY - CONF AU - Piskachev, Goran AU - Krishnamurthy, Ranjith AU - Bodden, Eric ID - 26407 T2 - 2021 IEEE 21st International Working Conference on Source Code Analysis and Manipulation (SCAM) TI - SecuCheck: Engineering configurable taint analysis for software developers ER - TY - CONF AU - Luo, Linghui AU - Schäf, Martin AU - Sanchez, Daniel AU - Bodden, Eric ID - 22463 T2 - Proceedings of the 29th ACM Joint Meeting on European Software Engineering Conference and Symposium on the Foundations of Software Engineering TI - IDE Support for Cloud-Based Static Analyses ER - TY - CONF AU - Karakaya, Kadiray AU - Bodden, Eric ID - 33840 T2 - 2021 IEEE 21st International Working Conference on Source Code Analysis and Manipulation (SCAM) TI - SootFX: A Static Code Feature Extraction Tool for Java and Android ER - TY - JOUR AB - We demonstrate the integration of amorphous tungsten silicide superconducting nanowire single-photon detectors on titanium in-diffused lithium niobate waveguides. We show proof-of-principle detection of evanescently coupled photons of 1550 nm wavelength using bidirectional waveguide coupling for two orthogonal polarization directions. We investigate the internal detection efficiency as well as detector absorption using coupling-independent characterization measurements. Furthermore, we describe strategies to improve the yield and efficiency of these devices. AU - Höpker, Jan Philipp AU - Verma, Varun B AU - Protte, Maximilian AU - Ricken, Raimund AU - Quiring, Viktor AU - Eigner, Christof AU - Ebers, Lena AU - Hammer, Manfred AU - Förstner, Jens AU - Silberhorn, Christine AU - Mirin, Richard P AU - Woo Nam, Sae AU - Bartley, Tim ID - 23728 JF - Journal of Physics: Photonics SN - 2515-7647 TI - Integrated superconducting nanowire single-photon detectors on titanium in-diffused lithium niobate waveguides VL - 3 ER - TY - GEN AU - Müller, Stefanie Jutta Marianne AU - Kundisch, Dennis ID - 21509 TI - Gesellschaftliche Transformationen durch die Steigerung (popmusik)kultureller Teil-habe mittels innovativer Preiskonzepte – ein interdisziplinärer Literaturüberblick ER - TY - JOUR AB - Heat-assisted forming processes are becoming increasingly important in the manufacturing of sheet metal parts for body-in-white applications. However, the non-isothermal nature of these processes leads to challenges in evaluating the forming limits, since established methods such as Forming Limit Curves (FLCs) only allow the assessment of critical forming strains for steady temperatures. For this reason, a temperature-dependent extension of the well-established GISSMO (Generalized Incremental Stress State Dependent Damage Model) fracture indicator framework is developed by the authors to predict forming failures under non-isothermal conditions. In this paper, a general approach to combine several isothermal FLCs within the temperature-extended GISSMO model into a temperature-dependent forming limit surface is investigated. The general capabilities of the model are tested in a coupled thermo-mechanical FEA using the example of warm forming of an AA5182-O sheet metal cross-die cup. The obtained results are then compared with state of the art of evaluation methods. By taking the strain and temperature path into account, GISSMO predicts greater drawing depths by up to 20% than established methods. In this way the forming and so the lightweight potential of sheet metal parts can by fully exploited. Moreover, the risk and locus of failure can be evaluated directly on the part geometry by a contour plot. An additional advantage of the GISSMO model is the applicability for low triaxialities as well as the possibility to predict the materials behavior beyond necking up to ductile fracture. AU - Camberg, Alan Adam AU - Erhart, Tobias AU - Tröster, Thomas ID - 33895 IS - 17 JF - Materials KW - General Materials Science SN - 1996-1944 TI - A Generalized Stress State and Temperature Dependent Damage Indicator Framework for Ductile Failure Prediction in Heat-Assisted Forming Operations VL - 14 ER - TY - BOOK ED - Famula, Marta ED - Otto Eke, Norbert ID - 33894 TI - Ästhetik im Vormärz. Jahrbuch Forum Vormärz Forschung 2020 ER - TY - CHAP AU - Famula, Marta ED - Röskau-Ryde, Isabel ED - Kubacki, Artur ID - 33905 T2 - Literatur und Kultur zwischen West und Ost. Imagination, Kommunikation und Wahrnehmung in regionalen Kulturräumen. Festschrift für Paul Martin Langner zum 65. Geburtstag TI - Die Landstraße jenseits der Bedeutung. Peter Handkes spätes Drama Die Unschuldigen, ich und die Unbekannte am Rand der Landstraße ER - TY - CHAP AU - Famula, Marta ED - Otto Eke, Norbert ED - Famula, Marta ID - 33904 T2 - Ästhetik im Vormärz. Jahrbuch Forum Vormärz Forschung TI - Von der auf den Kopf gestellten Schönheit oder die Verneinung der Negation im Hässlichen. Zur dialektischen Funktion des Erhabenen und des Hässlichen bei Christian Hermann Weiße ER - TY - JOUR AU - Famula, Marta ID - 33902 JF - Kosmos Dürrenmatt. Eine Annäherung an den Denker, Dichter und Maler. Berner Zeitschrift für Geschichte, H. 3. Sonderdruck Spiezer Tagung, in: Annelise Hüssy, Stefanie Leuenberger (Hgg.) TI - Vom Entschluss, die Welt zu bestehen. Dürrenmatts Ethik des ‚à la bande‘ ER - TY - CHAP AU - Famula, Marta AU - Otto Eke, Norbert ED - Otto Eke, Norbert ED - Famula, Marta ID - 33903 T2 - Ästhetik im Vormärz. Jahrbuch Forum Vormärz Forschung 2020 TI - Ästhetik im Vormärz – Zur Einführung ER - TY - GEN AU - Famula, Marta ID - 33939 T2 - Jahrbuch für internationale Germanistik, Jahrgang LIII – Heft 1 (2021) TI - Lukas Bärfuss: Malinois. Erzählungen. Wallstein: Göttingen 2019 ER - TY - JOUR AU - Meer, Philipp AU - Hartmann, Johanna AU - Rumlich, Dominik ID - 21914 IS - 2 JF - European Journal of Applied Linguistics SN - 2192-9521 TI - Folklinguistic perceptions of Global Englishes among German learners of English VL - 9 ER - TY - CHAP AU - Famula, Marta ED - Langner, Paul Martin ED - Majkiewicz, Anna ED - Mirecka, Agata ID - 33906 T2 - Wiederholung im Theater. Zur deutschsprachigen Gegenwartsdramatik und ihrer Inszenierung, (= Gesellschaftskritische Literatur – Texte Autoren – Debatten 9) TI - Das Unveränderliche und die Wiederholung. Die Rolle der Kontingenz in Max Frischs letztem Drama Triptychon ER - TY - BOOK ED - Famula, Marta ED - Mirecka, Agata ED - Langner, Paul Martin ID - 33899 TI - Drama zwischen Text und Bühne (Schriftenreihe seit 2021) ER - TY - JOUR AB - While increasing digitalization enables multiple advantages for a reliable operation of technical systems, a remaining challenge in the context of condition monitoring is seen in suitable consideration of uncertainties affecting the monitored system. Therefore, a suitable prognostic approach to predict the remaining useful lifetime of complex technical systems is required. To handle different kinds of uncertainties, a novel Multi-Model-Particle Filtering-based prognostic approach is developed and evaluated by the use case of rubber-metal-elements. These elements are maintained preventively due to the strong influence of uncertainties on their behavior. In this paper, two measurement quantities are compared concerning their ability to establish a prediction of the remaining useful lifetime of the monitored elements and the influence of present uncertainties. Based on three performance indices, the results are evaluated. A comparison with predictions of a classical Particle Filter underlines the superiority of the developed Multi-Model-Particle Filter. Finally, the value of the developed method for enabling condition monitoring of technical systems related to uncertainties is given exemplary by a comparison between the preventive and the predictive maintenance strategy for the use case. AU - Bender, Amelie ID - 25046 IS - 10 JF - Machines KW - prognostics KW - RUL predictions KW - particle filter KW - uncertainty consideration KW - Multi-Model-Particle Filter KW - model-based approach KW - rubber-metal-elements KW - predictive maintenance SN - 2075-1702 TI - A Multi-Model-Particle Filtering-Based Prognostic Approach to Consider Uncertainties in RUL Predictions VL - 9 ER - TY - JOUR AU - Gröger, B. AU - Köhler, D. AU - Vorderbrüggen, J. AU - Troschitz, J. AU - Kupfer, R. AU - Meschut, G. AU - Gude, M. ID - 30698 JF - Production Engineering TI - Computed tomography investigation of the material structure in clinch joints in aluminium fibre-reinforced thermoplastic sheets ER - TY - JOUR AU - Weiß, D. AU - Schramm, B. AU - Kullmer, G. ID - 30699 JF - Production Engineering TI - Holistic investigation chain for the experimental determination of fracture mechanical material parameters with special specimens ER - TY - JOUR AU - Zirngibl, C. AU - Schleich, B. AU - Wartzack, S. ID - 30696 JF - Proceedings of the Design Society TI - Approach for the automated and data-based design of mechanical joints VL - 1 ER - TY - JOUR AU - Zirngibl, C. AU - Dworschak, F. AU - Schleich, B. AU - Wartzack, S. ID - 30700 JF - Production Engineering TI - Application of reinforcement learning for the optimization of clinch joint characteristics ER - TY - JOUR AU - Römisch, D. AU - Popp, J. AU - Drummer, D. AU - Merklein, M. ID - 30701 JF - Production Engineering TI - Joining of CFRT-steel hybrid parts via hole-forming and subsequent pin caulking ER - TY - JOUR AU - Lafarge, R. AU - Wolf, A. AU - Guilleaume, C. AU - Brosius, A. ID - 30697 JF - Minerals, Metals and Materials Series TI - A New Non-destructive Testing Method Applied to Clinching ER - TY - JOUR AB - Due to stricter emission targets in the mobility sector and the resulting trend towards lightweight construction in order to reduce weight and consequently emissions, multi-material systems that allow a material to be placed in the right quantity and in the right place are becoming increasingly important. One major challenge that is holding back the rapid and widespread use of multi-material systems is the lack of adequate joining processes that are suitable for joining dissimilar materials. Joining processes without auxiliary elements have the advantage of a reduced assembly effort and no additional added weight. Conventional joining processes without auxiliary elements, such as welding, clinching, or the use of adhesives, reach their limits due to different mechanical properties and chemical incompatibilities. A process with potential in the field of joining dissimilar materials is joining without an auxiliary element using pin structures. However, current pin manufacturing processes are mostly time-consuming or can only be integrated barely into existing industrial manufacturing processes due to their specific properties. For this reason, the present work investigates the production of single- and multi-pin structures from high-strength dual-phase steel HCT590X + Z (DP600, t0 = 1.5 mm) by cold extrusion directly out of the sheet metal. These structures are subsequently joined with an aluminium sheet (EN AW-6014-T4, t0 = 1.5 mm) by direct pin pressing. For a quantitative evaluation of the joint quality, tensile shear tests are carried out and the influence of different pin heights, pin number, and pin arrangements, as well as different joining strategies on the joint strength is experimentally evaluated. It is proven that a single pin structure with a diameter of 1.5 mm and an average height of 1.86 mm achieves a maximum tensile shear force of 1025 N. The results reveal that the formation of a form-fit during direct pin pressing is essential for the joint strength. By increasing the number of pins, a linear increase in force could be demonstrated, which is independent of the arrangement of the pin structures. AU - Römisch, D. AU - Kraus, M. AU - Merklein, M. ID - 30684 JF - Journal of Manufacturing and Materials Processing TI - Experimental study on joining by forming of hct590x + z and en-aw 6014 sheets using cold extruded pin structures VL - 5 ER - TY - JOUR AB - Lightweight constructions become more and more important, especially in the mobility sector. In this industry, the increasingly strict regulations regarding the emissions of carbon dioxide can be achieved to a certain extent by reducing the vehicle weight. Thus, multi-material systems are used. Conventional joining techniques reach their limits when joining different materials due to different thermal expansion, unequal stiffness or chemical incompatibilities. This is why additional joining elements or adhesives are used. These must be viewed critically regarding a lightweight and resource-efficient production, since they add weight or complicate the recycling process of these components. Consequently, there is a great and growing need for new versatile joining technologies in order to overcome these challenges and to be able to react to changing process parameters and boundary conditions. Joining without an auxiliary element using pin structures formed directly from the sheet metal plane is one approach to meet these challenges. These pin structures are then joined by direct pressing into the joining partner. This is possible with a variety of material combinations, but is advantageous with regard to continuous fibre-reinforced thermoplastic composites (CFRTP), as the fibres do not have to be cut when joining CFRTP using pin structures. In this paper, the formability of pin structures made of a dual-phase steel DP600 (HCT590X + Z) is investigated. The extruded pin structures are joined by direct pin pressing with an EN AW-6014 to form tensile shear specimens. Different joining strategies are investigated to compare their influence on the joint strength. The results have shown that it is feasible to form suitable pins from a DP600 dual-phase steel to produce reliable connections with an aluminium sheet joined by direct pin pressing. AU - Römisch, D. AU - Kraus, M. AU - Merklein, M. ID - 30682 JF - Key Engineering Materials TI - Investigation of Different Joining by Forming Strategies when Connecting Different Metals without Auxiliary Elements VL - 883 ER - TY - JOUR AB - The growing demands of resource-saving processes and products are leading to increasing importance of lightweight construction for the automotive industry. One approach is multi-material design, which uses high-strength steels and aluminium alloys in the production of vehicle bodies. Therefore, reliable processes for joining components with different mechanical properties and geometries are necessary. As conventional joining processes reach their limits, new versatile processes and methods are required which can adapt to different process conditions and disturbance variables. A widely used joining process to join different materials is self-piercing riveting as a joining by forming method, however it is characterised as inflexible to changing process conditions due to a linear process kinematic and rigid dies. An approach to extend the process limits is the application of a tumbling kinematic for the punch. Thus, an adapted tumbling strategy can be used to influence the joining process and to achieve a controlled material flow in order to manufacture tailored joints. For the fundamental investigation of the process, numerical investigations are necessary. In order to achieve high model quality a precise material modelling is crucial. Therefore, a characterisation of the materials HCT590X+Z and EN AW-6014 as typical materials of multi-material mixes and the rivet material 38B2 is performed. Due to the different stress conditions during tumbling self-piercing riveting suitable characterisation methods are selected and carried out. AU - Wituschek, S. AU - Lechner, M. ID - 30718 JF - ESAFORM 2021 TI - Material characterisation methods for a tumbling self-piercing riveting process ER - TY - JOUR AB - When joining lightweight parts of various materials, clinching is a cost efficient solution. In a production line, the quality of a clinch point is primarily controlled by measurement of dimensions, which are accessible from outside. However, methods such as visual testing and measuring the bottom thickness as well as the outer diameter are not able to deliver any information about the most significant geometrical characteristic of the clinch point, neck thickness and undercut. Furthermore, ex-situ destructive methods such as microsectioning cannot detect elastic deformations and cracks that close after unloading. In order to exceed the current limits, a new non-destructive in-situ testing method for the clinching process is necessary. This work proposes a concept to characterize clinch points in-situ by combining two complementary non-destructive methods, namely, computed tomography (CT) and ultrasonic testing. Firstly, clinch points with different geometrical characteristics are analysed experimentally using ex-situ CT to get a highly spatially resolved 3D-image of the object. In this context, highly X-ray attenuating materials enhancing the visibility of the sheet-sheet interface are investigated. Secondly, the test specimens are modelled using finite element method (FEM) and a transient dynamic analysis (TDA) is conducted to study the effect of the geometrical differences on the deformation energy and to qualify the TDA as a fast in-situ non-destructive method for characterizing clinch points at high temporal resolution. AU - Köhler, D. AU - Sadeghian, B. AU - Kupfer, R. AU - Troschitz, J. AU - Gude, M. AU - Brosius, A. ID - 30683 JF - Key Engineering Materials TI - A Method for Characterization of Geometric Deviations in Clinch Points with Computed Tomography and Transient Dynamic Analysis VL - 883 ER - TY - JOUR AB - The use of clinch joints, e.g. vehicle structures, is determined by the reliability of the joint and its strength properties - in particular the fatigue strength. Clinch connections offer the advantage over form-closure and force-closure processes that they can also be used for hybrid material combinations. In order to be able to evaluate the influence of the geometry parameters such as e.g. undercut, neck thickness or also base thickness on the fatigue behavior, three clinch connections (in optimum and compromise design) with different tool parameters were designed and examined using the example of a joining task with aluminum sheet material. For this purpose, fatigue curves (F-N curves) in the range of high to very high numbers of load cycles (N = 105 to 107) were determined. In this load cycle range, a so-called "neck fracture" is mainly to be expected as the type of failure, whereas for quasi-static tests, a “buckling” is more likely to occur. The tests were carried out on single-cut overlapping shear tensile specimens. Metallographic and scanning electron microscopic examinations of the joints and the fracture surfaces served to identify the crack initiation site and to clarify the respective type of failure. Significant differences in the damage behaviour of the three clinching variants could be shown. This observation enables one step into the direction of fully understanding the relationship along the causal chain "joint requirements - joining process - fatigue strength". Thus the adaptability of the clinching process can be improved. AU - Ewenz, L. AU - Kalich, J. AU - Zimmermann, M. AU - Füssel, U. ID - 30663 JF - Key Engineering Materials TI - Effect of Different Tool Geometries on the Mechanical Properties of Al-Al Clinch Joints VL - 883 ER - TY - JOUR AB - Thermally supported clinching (Hotclinch) is a novel promising process to join dissimilar materials. Here, metal and fibre-reinforced thermoplastics (FRTP) are used within this single step joining process and without the usage of auxiliary parts like screws or rivets. For this purpose, heat is applied to improve the formability of the reinforced thermoplastic. This enables joining of the materials using conventional clinching-tools. Focus of this work is the modelling on mesoscopic scale for the numerical simulation of this process. The FTRP-model takes the material behaviour both of matrix and the fabric reinforced organo-sheet under process temperatures into account. For describing the experimentally observed phenomena such as large deformations, fibre failure and the interactions between matrix and fibres as well as between fibres themselves, the usage of conventional, purely Lagrangian based FEM methods is limited. Therefore, the combination of contact-models with advanced modelling approaches like Arbitrary-Lagrangian-Eulerian (ALE), Coupled-Eulerian-Lagrangian (CEL) and Smooth-ParticleHydrodynamics (SPH) for the numerical simulation of the clinching process are employed. The different approaches are compared with regard to simulation feasibility, robustness and results accuracy. It is shown, that the CEL approach represents the most promising approach to describe the clinching process. AU - Gröger, B. AU - Hornig, A. AU - Hoog, A. AU - Gude, M. ID - 30688 JF - ESAFORM 2021 - 24th International Conference on Material Forming TI - Modelling of thermally supported clinching of fibre-reinforced thermoplastics: Approaches on mesoscale considering large deformations and fibre failure ER - TY - JOUR AB - Joints are an essential part of modern (lightweight) structures in a broad variety of applications. The reason for this is the rapidly increasing number of different material combinations needing to be joined in application areas like the automotive industry. It is currently common to use numerous auxiliary or standardized elements instead of individually adapted joining elements. This leads to a large number of different joining elements per product and thus to high costs. An innovative approach to overcoming this issue is the design, manufacture and setting of joint-specific joining elements. A good candidate for the manufacture of adapted joining elements of this type is the so-called friction spinning process. The joining elements formed in this way can be specifically adapted to the application in question in terms of both shape and mechanical properties. The part geometry required for the properties of a given joint is formed using a universal forming tool. This makes it possible to form a wide variety of sub geometries for the auxiliary joining part as a function of the prevailing joint condition, using a single forming tool and starting from the same semi-finished bar material. By applying different process strategies for the rotational speed and feed rate during the forming operation, the same part geometry can even be given different local mechanical properties. The following contribution presents the results of ongoing research work and includes the process concept, process properties, tooling and the results of experimental investigations into the joining of two sheet metal parts with help of this new joining process. AU - Wiens, E. AU - Wischer, C. AU - Homberg, W. ID - 30685 JF - ESAFORM TI - Development of a novel adaptive joining technology employing friction-spun joint connectors (FSJC) ER - TY - JOUR AB - Corrosion is a major cause for the failure of metallic components in various branches of the industry. Depending on the corrosion severity, the time until failure of the component varies. On the contrary, a study has shown that certain riveted metal joints, exposed to a short period of mechanical loading and corrosion, have greater fatigue limits. This study gives rise to the question how different corrosion exposure times affect joint metallic components. In the present research, a theoretical approach is developed in order to evaluate the influence of galvanic corrosion on joint integrity of clinched metal joints. At first, the framework for modeling galvanic corrosion is introduced. Furthermore, a simulative investigation of a clinching point is carried out based on the assumption that corrosion leads to a reduction of the contact area which leads to a local increase in contact pressure. For this purpose, the stiffness values of individual elements in a finite element model are reduced locally in the contact area of the undercut and the contact stress along a path is evaluated. Summarizing, a modeling approach is introduced to investigate corrosion effects on load-bearing behavior of clinched joints. AU - Harzheim, S. AU - Steinfelder, C. AU - Wallmersperger, T. AU - Brosius, A. ID - 30664 JF - Key Engineering Materials TI - A First Approach for the Treatment of Galvanic Corrosion and of Load-Bearing Capacity of Clinched Joints VL - 883 ER - TY - JOUR AB - In recent years, clinching has gathered popularity to join sheets of different materials in industrial applications. The manufacturing process has some advantages, as reduced joining time, reduced costs, and the joints show good fatigue properties. To ensure the joint strength, reliable simulations of the material behaviour accounting for process-induced damage are expected to be beneficial to obtain credible values for the ultimate joint strength and its fatigue limit. A finite plasticity gradient-damage material model is outlined to describe the plastic and damage evolutions during the forming of sheet metals, later applied to clinching. The utilised gradient-enhancement cures the damage-induced localisation by introducing a global damage variable as an additional finite element field. Both, plasticity and damage are strongly coupled, but can, due to a dual-surface approach, evolve independently. The ability of the material model to predict damage in strongly deformed sheets, its flexibility and its regularization properties are illustrated by numerical examples. AU - Friedlein, J. AU - Mergheim, J. AU - Steinmann, P. ID - 30694 JF - Key Engineering Materials TI - A finite plasticity gradient-damage model for sheet metals during forming and clinching VL - 883 KEM ER - TY - JOUR AB - Joining and local forming processes for fibre-reinforced thermoplastics (FRTP) like hole-forming or variations of the clinching process require an in-depth understanding of the process induced effects on meso-scale. For numerical modelling with a geometrical description of a woven fabric, adequate material models for a representative unit cell are identified. Model calibration is achieved employing a mesoscopic finite-element-approach using the embedded element method based on tensile tests of the consolidated organo-sheets and a phenomenological evaluation of photomicrographs. The model takes temperature dependent stiffness and fibre tension failure into account. AU - Gröger, B. AU - Hornig, A. AU - Hoog, A. AU - Gude, M. ID - 30689 JF - Key Engineering Materials TI - Temperature dependent modelling of fibre-reinforced thermoplastic organo-sheet material for forming and joining process simulations VL - 883 KEM ER - TY - JOUR AB - Predicting the durability of components under mechanical loading combined with environmental conditions leading to corrosion is one of the most challenging tasks in mechanical engineering. Precise predictions are neccesary for lightweight design in transportation due to environmental protection. During corrosion often hydrogen is produced by electrochemical reactions. Hydrogen embrittlement is one of the most feared damage mechanisms for metal constructions leading to early and unexpected failure. Until now predictions are mostly done through costly experiments. In the present research, a first simple simulation model based on the fundamentals of electrochemistry and continuum damage mechanics is developed to couple the damage induced by the mechanical stress with the hydrogen embrittlement. Results of the durability are presented for the case of uniaxial cyclic loading for varying testing frequency. AU - Hofmann, M. AU - Shi, Y. AU - Wallmersperger, T. ID - 30720 JF - PAMM TI - A first Model of Fatigue Corrosion of a Metal through Hydrogen Embrittlement VL - 20 ER - TY - JOUR AB - Due to their cost-efficiency and environmental friendliness, the demand of mechanical joining processes is constantly rising. However, the dimensioning and design of joints and suitable processes are mainly based on expert knowledge and few experimental data. Therefore, the performance of numerical and experimental studies enables the generation of optimized joining geometries. However, the manual evaluation of the results of such studies is often highly time-consuming. As a novel solution, image segmentation and machine learning algorithm provide methods to automate the analysis process. Motivated by this, the paper presents an approach for the automated analysis of geometrical characteristics using clinching as an example. AU - Zirngibl, C. AU - Schleich, B. ID - 30695 JF - Key Engineering Materials TI - Approach for the automated analysis of geometrical clinch joint characteristics VL - 883 KEM ER - TY - CONF AB - Computational homogenization is a powerful tool which allows to obtain homogenized properties of materials on the macroscale from the simulation of the underlying microstructure. The response of the microstructure is, however, strongly affected by variations in the microstructure geometry. The effect of geometry variations is even stronger in cases when the material exhibits plastic deformations. In this work we study a model of a steel alloy with arbitrary distributed elliptic voids. We model one single unit cell of the material containing one single void. The geometry of the void is not precisely known and is modeled as a variable orientation of an ellipse. Large deformations applied to the unit cell necessitate a finite elasto-plastic material model. Since the geometry variation is parameterized, we can utilize the method recently developed for stochastic problems but also applicable to all types of parametric problems — the isoparametric stochastic local FEM (SL-FEM). It is an ideal tool for problems with only a few parameters but strongly nonlinear dependency of the displacement fields on parameters. Simulations demonstrate a strong effect of parameter variation on the plastic strains and, thus, substantiate the use of the parametric computational homogenization approach. AU - Pivovarov, Dmytro AU - Mergheim, Julia AU - Willner, Kai AU - Steinmann, Paul ID - 34208 IS - 1 SN - 1617-7061 T2 - PAMM TI - Parametric FEM for computational homogenization of heterogeneous materials with random voids VL - 20 ER - TY - JOUR AU - Knust, Steffen AU - Ruhm, Lukas AU - Kuhlmann, Andreas AU - Meinderink, Dennis AU - Bürger, Julius AU - Lindner, Jörg AU - de los Arcos de Pedro, Maria Teresa AU - Grundmeier, Guido ID - 34087 IS - 7 JF - Journal of Raman Spectroscopy KW - Spectroscopy KW - General Materials Science SN - 0377-0486 TI - In situ backside Raman spectroscopy of zinc oxide nanorods in an atmospheric‐pressure dielectric barrier discharge plasma VL - 52 ER -