@book{37273, abstract = {{How are activation programs for the young unemployed implemented? How do street-level bureaucrats deal with competing rationalities and demands for action? Transition policies increasingly aim at promoting self-regulation and constructing employable subjects. Stephan Dahmen explores the practical regulation of biographical transitions in activation programs for the young unemployed by focusing on the interactive accomplishment of activation work. The study reveals how the critical tensions of activation policies are continually re-interpreted and adapted to local contingencies and describes the various organisational technologies used for creating employable subjects.}}, author = {{Dahmen, Stephan}}, keywords = {{Youth, Welfare State, Transitions, Human Service Organizations, Institutional Ethnography, Activation, Sociology of Conventions, Work, Education, Educational Research, Sociology of Education, Social Pedagogy, History of Education, Bielefeld University Press}}, pages = {{312}}, publisher = {{Bielefeld University Press}}, title = {{{Regulating Transitions from School to Work. An Institutional Ethnography of Activation Work in Action}}}, doi = {{10.14361/9783839457061}}, year = {{2021}}, } @techreport{37136, abstract = {{This study examines the relation between voluntary audit and the cost of debt in private firms. We use a sample of 4,058 small private firms operating in the period 2006‐2017 that are not subject to mandatory audits. Firms decide for a voluntary audit of financial statements either because the economic setting in which they operate effectively forces them to do so (e.g., ownership complexity, export‐oriented supply chain, subsidiary status) or because firm fundamentals and/or financial reporting practices limit their access to financial debt, both reflected in earnings quality. We use these factors to model the decision for voluntary audit. In the outcome analyses, we find robust evidence that voluntary audits are associated with higher, rather than lower, interest rate by up to 3.0 percentage points. This effect is present regardless of the perceived audit quality (Big‐4 vs. non‐Big‐4), but is stronger for non‐Big‐4 audits where auditees have a stronger position relative to auditors. Audited firms’ earnings are less informative about future operating performance relative to unaudited counterparts. We conclude that voluntary audits facilitate access to financial debt for firms with higher risk that may otherwise have no access to this form of financing. The price paid is reflected in higher interest rates charged to firms with voluntary audits – firms with higher information and/or fundamental risk.}}, author = {{Ichev, Riste and Koren, Jernej and Kosi, Urska and Sitar Sustar, Katarina and Valentincic, Aljosa}}, keywords = {{private firms, voluntary audit, cost of debt, self‐selection bias, risk}}, title = {{{Cost of Debt for Private Firms Revisited: Voluntary Audits as a Reflection of Risk}}}, year = {{2021}}, } @article{34227, abstract = {{In order to reduce the fuel consumption and consequently the greenhouse emissions, the automotive industry is implementing lightweight constructions in the body in white production. As a result, the use of aluminum alloys is continuously increasing. Due to poor weldability of aluminum in combination with other materials, mechanical joining technologies like clinching are increasingly used. In order to predict relevant characteristics of clinched joints and to ensure the reliability of the process, it is simulated numerically during product development processes. In this regard the predictive accuracy of the simulated process highly depends on the implemented friction model. In particular, the frictional behavior between the sheet metals affects the geometrical formation of the clinched joint significantly. This paper presents a testing method, which enables to determine the frictional coefficients between sheet metal materials for the simulation of clinching processes. For this purpose, the correlation of interface pressure and the relative velocity between aluminum sheets in clinching processes is investigated using numerical simulation. Furthermore, the developed testing method focuses on the specimen geometry as well as the reproduction of the occurring friction conditions between two sheet metal materials in clinching processes. Based on a methodical approach the test setup is explained and the functionality of the method is proven by experimental tests using sheet metal material EN AW6014.}}, author = {{Rossel, Moritz Sebastian and Böhnke, Max and Bielak, Christian Roman and Bobbert, Mathias and Meschut, Gerson}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, pages = {{81--88}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{Development of a Method for the Identification of Friction Coefficients in Sheet Metal Materials for the Numerical Simulation of Clinching Processes}}}, doi = {{10.4028/www.scientific.net/kem.883.81}}, volume = {{883}}, year = {{2021}}, } @inproceedings{30675, abstract = {{In many areas of product manufacturing constructions consist of individual components and metal sheets that are joined together to form complex structures. A simple and industrial common method for joining dissimilar and coated materials is clinching. During the joining process and due to the service load cracks can occur in the area of the joint, propagate due to cyclic loading and consequently lead to structural failure. For the prevention of these damage cases, first of all knowledge about the fracture mechanical material parameters regarding the original material state of the sheet metals used within the clinching process are essential.Within the scope of this paper experimental and numerical preliminary investigations regarding the fracture mechanical behavior of sheet metals used within the clinching process are presented. Due to the low thickness of 1.5 mm of the material sheets, the development of a new specimen is necessary to determine the crack growth rate curve including the fracture mechanical parameters like the threshold against crack growth ΔKI,th and the fracture toughness KIC of the base material HCT590X. For the experimental determination of the crack growth rate curve the numerical calculation of the geometry factor function as well as the calibration function of this special specimen are essential. After the experimental validation of the numerically determined calibration function, crack growth rate curves are determined for the stress ratios R = 0.1 and R = 0.3 to examine the mean stress sensitivity. In addition, the different rolling directions of 0° and 90° in relation to the initial crack are taken into account in order to investigate the influence of the anisotropy due to rolling.}}, author = {{Weiß, Deborah and Schramm, Britta and Kullmer, Gunter}}, booktitle = {{Key Engineering Materials}}, issn = {{1662-9795}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, location = {{online}}, pages = {{127--132}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{Numerical and Experimental Fracture Mechanical Investigations of Clinchable Sheet Metals Made of HCT590X}}}, doi = {{10.4028/www.scientific.net/kem.883.127}}, volume = {{883}}, year = {{2021}}, } @article{40434, author = {{Klement, Philip and Dehnhardt, Natalie and Dong, Chuan-Ding and Dobener, Florian and Bayliff, Samuel and Winkler, Julius and Hofmann, Detlev M. and Klar, Peter J. and Schumacher, Stefan and Chatterjee, Sangam and Heine, Johanna}}, issn = {{0935-9648}}, journal = {{Advanced Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, number = {{23}}, publisher = {{Wiley}}, title = {{{Atomically Thin Sheets of Lead‐Free 1D Hybrid Perovskites Feature Tunable White‐Light Emission from Self‐Trapped Excitons}}}, doi = {{10.1002/adma.202100518}}, volume = {{33}}, year = {{2021}}, } @article{34226, abstract = {{The increasing use of multi-material constructions lead to a continuous increase in the use of mechanical joining techniques due to the wide range of joining possibilities as well as the high load-bearing capacities of the joints. Nevertheless, the currently rigid tool systems are not able to react to changing boundary conditions, like changing the material-geometry-combination. Therefore research work is crucial with regard to versatile joining systems. In this paper, a new approach for a versatile self-piercing riveting process considering the joining system as well as the auxiliary joining part is presented.}}, author = {{Kappe, Fabian and Bobbert, Mathias and Meschut, Gerson}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, pages = {{3--10}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{New Approach for Versatile Self Piercing Riveting: Joining System and Auxiliary Part}}}, doi = {{10.4028/www.scientific.net/kem.883.3}}, volume = {{883}}, year = {{2021}}, } @article{41511, author = {{Hein, Maxwell and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{0933-5137}}, journal = {{Materialwissenschaft und Werkstofftechnik}}, keywords = {{Mechanical Engineering, Mechanics of Materials, Condensed Matter Physics, General Materials Science}}, number = {{7}}, pages = {{703--716}}, publisher = {{Wiley}}, title = {{{Additively processed TiAl6Nb7 alloy for biomedical applications}}}, doi = {{10.1002/mawe.202000288}}, volume = {{52}}, year = {{2021}}, } @article{41512, author = {{Andreiev, Anatolii and Hoyer, Kay-Peter and Dula, Dimitri and Hengsbach, Florian and Grydin, Olexandr and Frolov, Yaroslav and Schaper, Mirko}}, issn = {{0921-5093}}, journal = {{Materials Science and Engineering: A}}, keywords = {{Mechanical Engineering, Mechanics of Materials, Condensed Matter Physics, General Materials Science}}, publisher = {{Elsevier BV}}, title = {{{Laser beam melting of functionally graded materials with application-adapted tailoring of magnetic and mechanical performance}}}, doi = {{10.1016/j.msea.2021.141662}}, volume = {{822}}, year = {{2021}}, } @article{41510, author = {{Pramanik, Sudipta and Andreiev, Anatolii and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{0142-1123}}, journal = {{International Journal of Fatigue}}, keywords = {{Industrial and Manufacturing Engineering, Mechanical Engineering, Mechanics of Materials, General Materials Science, Modeling and Simulation}}, publisher = {{Elsevier BV}}, title = {{{Quasi in-situ analysis of fracture path during cyclic loading of double-edged U notched additively manufactured FeCo alloy}}}, doi = {{10.1016/j.ijfatigue.2021.106498}}, volume = {{153}}, year = {{2021}}, } @article{41509, author = {{Krüger, Jan Tobias and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{0167-577X}}, journal = {{Materials Letters}}, keywords = {{Mechanical Engineering, Mechanics of Materials, Condensed Matter Physics, General Materials Science}}, publisher = {{Elsevier BV}}, title = {{{Bioresorbable AgCe and AgCeLa alloys for adapted Fe-based implants}}}, doi = {{10.1016/j.matlet.2021.130890}}, volume = {{306}}, year = {{2021}}, } @article{41517, abstract = {{AbstractWithin this research, the multiscale microstructural evolution before and after the tensile test of a FeCo alloy is addressed. X-ray µ-computer tomography (CT), electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM) are employed to determine the microstructure on different length scales. Microstructural evolution is studied by performing EBSD of the same area before and after the tensile test. As a result, $$\langle$$ ⟨ 001$$\rangle$$ ⟩ ||TD, $$\langle$$ ⟨ 011$$\rangle$$ ⟩ ||TD are hard orientations and $$\langle$$ ⟨ 111$$\rangle$$ ⟩ ||TD is soft orientations for deformation accommodation. It is not possible to predict the deformation of a single grain with the Taylor model. However, the Taylor model accurately predicts the orientation of all grains after deformation. {123}$$\langle$$ ⟨ 111$$\rangle$$ ⟩ is the most active slip system, and {112}$$\langle$$ ⟨ 111$$\rangle$$ ⟩ is the least active slip system. Both EBSD micrographs show grain subdivision after tensile testing. TEM images show the formation of dislocation cells. Correlative HRTEM images show unresolved lattice fringes at dislocation cell boundaries, whereas resolved lattice fringes are observed at dislocation cell interior. Since Schmid’s law is unable to predict the deformation behavior of grains, the boundary slip transmission accurately predicts the grain deformation behavior.}}, author = {{Pramanik, Sudipta and Tasche, Lennart and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{1059-9495}}, journal = {{Journal of Materials Engineering and Performance}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, number = {{11}}, pages = {{8048--8056}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Correlation between Taylor Model Prediction and Transmission Electron Microscopy-Based Microstructural Investigations of Quasi-In Situ Tensile Deformation of Additively Manufactured FeCo Alloy}}}, doi = {{10.1007/s11665-021-06065-9}}, volume = {{30}}, year = {{2021}}, } @article{41514, author = {{Krüger, Jan Tobias and Hoyer, Kay-Peter and Filor, Viviane and Pramanik, Sudipta and Kietzmann, Manfred and Meißner, Jessica and Schaper, Mirko}}, issn = {{0925-8388}}, journal = {{Journal of Alloys and Compounds}}, keywords = {{Materials Chemistry, Metals and Alloys, Mechanical Engineering, Mechanics of Materials}}, publisher = {{Elsevier BV}}, title = {{{Novel AgCa and AgCaLa alloys for Fe-based bioresorbable implants with adapted degradation}}}, doi = {{10.1016/j.jallcom.2021.159544}}, volume = {{871}}, year = {{2021}}, } @article{51202, abstract = {{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.}}, author = {{Köhler, Daniel and Sadeghian, Behdad and Kupfer, Robert and Troschitz, Juliane and Gude, Maik and Brosius, Alexander}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, pages = {{89--96}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{A Method for Characterization of Geometric Deviations in Clinch Points with Computed Tomography and Transient Dynamic Analysis}}}, doi = {{10.4028/www.scientific.net/kem.883.89}}, volume = {{883}}, year = {{2021}}, } @article{51198, author = {{Köhler, D. and Sadeghian, B. and Troschitz, J. and Kupfer, R. and Gude, M. and Brosius, A.}}, issn = {{2666-3309}}, journal = {{Journal of Advanced Joining Processes}}, keywords = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}}, publisher = {{Elsevier BV}}, title = {{{Characterisation of lateral offsets in clinch points with computed tomography and transient dynamic analysis}}}, doi = {{10.1016/j.jajp.2021.100089}}, volume = {{5}}, year = {{2021}}, } @article{23431, abstract = {{As an effective and accurate method for modelling composite materials, mean-field homogenization is still not well studied in modelling non-linear and damage behaviours of UD composites. Investigated micro FE-simulations show that the matrix of UD composites exhibits different average plastic behaviour, named as average asymmetric matrix plasticity (AAMP), when the composite behaves different under shear, longitudinal and transverse loadings. In this study, a non-linear mean-field debonding model (NMFDM) combining a mean-field model and a fibre–matrix interface debonding model, is developed to simulate UD composites under consideration of AAMP, fibre–matrix interface damage and progressive failure. AAMP is considered by using so-called stress mode factor, which is expressed in terms of basic invariants of the matrix deviatoric stress tensor and is used as an indicator for detection of differences in the loading mode. The material behaviour of UD composites with imperfect interface is assumed identical as for perfect interface and stiffness reduced fibres. Progressive failure criteria are established with consideration of fibre breakage and matrix crack for different fibre orientations. As a representative example for the NMFDM, a C30/E201 UD composite is studied. To verify the model, experiments are conducted on polymers, carbon fibres and UD CFRPs. Finally, the model is applied to simulate a perforated CFRP laminate, which shows excellent prediction ability on deformation, debonding and progressive failure.}}, author = {{Cheng, C. and Wang, Z. and Jin, Z. and Ju, X. and Schweizer, Swetlana and Tröster, Thomas and Mahnken, Rolf}}, issn = {{1359-8368}}, journal = {{Composites Part B: Engineering}}, keywords = {{Non-linear mean-field homogenization Average asymmetric plasticity of matrix Fibre–matrix interface debonding Micro-mechanical FE-simulation Progressive failure}}, title = {{{Non-linear mean-field modelling of UD composite laminates accounting for average asymmetric plasticity of the matrix, debonding and progressive failure}}}, doi = {{10.1016/j.compositesb.2021.109209}}, volume = {{224}}, year = {{2021}}, } @article{41508, author = {{Camberg, Alan Adam and Andreiev, Anatolii and Pramanik, Sudipta and Hoyer, Kay-Peter and Tröster, Thomas and Schaper, Mirko}}, issn = {{0921-5093}}, journal = {{Materials Science and Engineering: A}}, keywords = {{Mechanical Engineering, Mechanics of Materials, Condensed Matter Physics, General Materials Science}}, publisher = {{Elsevier BV}}, title = {{{Strength enhancement of AlMg sheet metal parts by rapid heating and subsequent cold die stamping of severely cold-rolled blanks}}}, doi = {{10.1016/j.msea.2021.142312}}, volume = {{831}}, year = {{2021}}, } @article{57971, abstract = {{Repetitive TMS (rTMS) with a frequency of 5-10~Hz is widely used for language mapping. However, it may be accompanied by discomfort and is limited in the number and reliability of evoked language errors. We, here, systematically tested the influence of different stimulation frequencies (i.e., 10, 30, and 50 Hz) on tolerability, number, reliability, and cortical distribution of language errors aiming at improved language mapping. 15 right-handed, healthy subjects (m~=~8, median age: 29 yrs) were investigated in two sessions, separated by 2-5 days. In each session, 10, 30, and 50 Hz rTMS were applied over the left hemisphere in a randomized order during a picture naming task. Overall, 30 Hz rTMS evoked significantly more errors (20 $\pm$ 12{%}) compared to 50 Hz (12 $\pm$ 8{%}; p {\textless}.01), whereas error rates were comparable between 30/50 and 10~Hz (18 $\pm$ 11{%}). Across all conditions, a significantly higher error rate was found in Session 1 (19 $\pm$ 13{%}) compared to Session 2 (13 $\pm$ 7{%}, p {\textless}.05). The error rate was poorly reliable between sessions for 10 (intraclass correlation coefficient, ICC~=~.315) and 30 Hz (ICC~=~.427), whereas 50 Hz showed a moderate reliability (ICC~=~.597). Spatial reliability of language errors was low to moderate with a tendency toward increased reliability for higher frequencies, for example, within frontal regions. Compared to 10~Hz, both, 30 and 50 Hz were rated as less painful. Taken together, our data favor the use of rTMS-protocols employing higher frequencies for evoking language errors reliably and with reduced discomfort, depending on the region of interest.}}, author = {{Nettekoven, Charlotte and Pieczewski, Julia and Neuschmelting, Volker and Jonas, Kristina and Goldbrunner, Roland and Grefkes, Christian and Weiss Lucas, Carolin}}, journal = {{Human brain mapping}}, keywords = {{Adult, Brain Mapping, Cerebral Cortex/diagnostic imaging/physiology, Female, Humans, Magnetic Resonance Imaging, Male, Pattern Recognition, Psycholinguistics, Reproducibility of Results, Speech/physiology, Transcranial Magnetic Stimulation, Visual/physiology, Young Adult}}, number = {{16}}, pages = {{5309–5321}}, title = {{{Improving the efficacy and reliability of rTMS language mapping by increasing the stimulation frequency}}}, doi = {{10.1002/hbm.25619}}, volume = {{42}}, year = {{2021}}, } @misc{23796, author = {{Bernemann, Sören Antonius}}, keywords = {{CFD, landwirtschaftliche Abfälle, Volume-of-Fluid}}, title = {{{Erstellung eines CFD-Modells für die Entwicklung eines innovativen Trennapparates zur Stickstoffrückgewinnung aus landwirtschaftlichen Abfällen}}}, year = {{2020}}, } @article{16249, abstract = {{Timing plays a crucial role in the context of information security investments. We regard timing in two dimensions, namely the time of announcement in relation to the time of investment and the time of announcement in relation to the time of a fundamental security incident. The financial value of information security investments is assessed by examining the relationship between the investment announcements and their stock market reaction focusing on the two time dimensions. Using an event study methodology, we found that both dimensions influence the stock market return of the investing organization. Our results indicate that (1) after fundamental security incidents in a given industry, the stock price will react more positively to a firm’s announcement of actual information security investments than to announcements of the intention to invest; (2) the stock price will react more positively to a firm’s announcements of the intention to invest after the fundamental security incident compared to before; and (3) the stock price will react more positively to a firm’s announcements of actual information security investments after the fundamental security incident compared to before. Overall, the lowest abnormal return can be expected when the intention to invest is announced before a fundamental information security incident and the highest return when actual investing after a fundamental information security incident in the respective industry.}}, author = {{Szubartowicz, Eva and Schryen, Guido}}, journal = {{Journal of Information System Security}}, keywords = {{Event Study, Information Security, Investment Announcements, Stock Price Reaction, Value of Information Security Investments}}, number = {{1}}, pages = {{3 -- 31}}, publisher = {{Information Institute Publishing, Washington DC, USA}}, title = {{{Timing in Information Security: An Event Study on the Impact of Information Security Investment Announcements}}}, volume = {{16}}, year = {{2020}}, } @article{27117, abstract = {{Through co-occurrence analysis of 1139 documents (1964-2018) we identified trends in the discussions about the implementation of student teaching evaluation (SET). We found that: (1) Attention to SET originated in the US in the 1970s, spreading to German-speaking countries in the mid-1990s and continuing in China and Latin America in the early 2000s. (2) SET is commonly viewed as a control tool deserving methodological improvement, while bias is debated in the US. We also found local trajectories: (3) Whereas in the US and Latin America SET is primarily seen as a management tool, German-speaking and Chinese authors reflect more on improving teaching. Chinese scholars consider SET a valid instrument for state control associated with artificial intelligence. Also, (4) SET is commonly used in medical education in the US and the German-speaking region and in physical education in China. We conclude that SET is discussed cross-nationally but affected by national path dependencies.}}, author = {{Pineda, Pedro and Steinhardt, Isabel}}, issn = {{1356-2517}}, journal = {{Teaching in Higher Education}}, keywords = {{academic discourse, bibliometric review, quality assurance, student evaluation of teaching, teaching evaluation}}, pages = {{1--21}}, title = {{{The Debate on student evaluations of teaching: global convergence confronts higher education traditions}}}, doi = {{10.1080/13562517.2020.1863351}}, year = {{2020}}, }