@inproceedings{34208, abstract = {{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.}}, author = {{Pivovarov, Dmytro and Mergheim, Julia and Willner, Kai and Steinmann, Paul}}, booktitle = {{PAMM}}, issn = {{1617-7061}}, number = {{1}}, publisher = {{Wiley}}, title = {{{Parametric FEM for computational homogenization of heterogeneous materials with random voids}}}, doi = {{10.1002/pamm.202000071}}, volume = {{20}}, year = {{2021}}, } @article{35303, abstract = {{Abstract Purpose Studies about effects of lunch dietary Glycemic Index (GI) on cognition of schoolchildren are scarce. Our previous CogniDo GI study found no changes of cognition in the early postprandial phase after consumption of two rice types with medium vs. high dietary GI for lunch (i.e., 45 min after starting lunch). This study investigated whether the dietary GI of lunch has an impact on cognition of schoolchildren in the late postprandial phase, 90 min after lunch. Methods A randomized, 2 × 2 crossover intervention study was conducted at a comprehensive school with 5th and 6th grade students. Participants (n = 212) were randomly assigned to either sequence 1 or 2. In the first period, participants of sequence 1 received a dish with high GI rice (GI: 79), those of sequence 2 with medium GI rice (GI: 64)—in the second period, 1 week later, vice versa. Computer-based cognitive testing was performed 90 min after lunch examining tonic alertness, visual search and task switching, and working memory. Treatment effects and treatment effects adjusted for estimated lunch glycemic load (GL) were analyzed using a linear mixed model. Results The selected cognitive parameters were not affected by the GI of lunch 90 min after lunch, neither after intention-to-treat nor in the per-protocol analysis. Adjustment for GL also did not change results. Conclusion The present study revealed no notable differences after the consumption of two rice types with medium vs. high dietary GI for lunch in children’s cognitive function in the late postprandial phase, 90 min after lunch. Clinical trial registration German Clinical Trials Register (DRKS00013597); date of registration: 16/04/2018, retrospectively registered. }}, author = {{Drozdowska, Alina and Sinningen, Kathrin and Falkenstein, Michael and Rudolf, Henrik and Libuda, Lars and Buyken, Anette and Lücke, Thomas and Kersting, Mathilde}}, issn = {{1436-6207}}, journal = {{European Journal of Nutrition}}, keywords = {{Nutrition and Dietetics, Medicine (miscellaneous)}}, number = {{3}}, pages = {{1637--1647}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Impact of lunch with carbohydrates differing in glycemic index on children's cognitive functioning in the late postprandial phase: a randomized crossover study}}}, doi = {{10.1007/s00394-021-02766-y}}, volume = {{61}}, year = {{2021}}, } @article{35575, author = {{Schulze Darup, Moritz and Alexandru, Andreea B. and Quevedo, Daniel E. and Pappas, George J.}}, issn = {{1066-033X}}, journal = {{IEEE Control Systems}}, keywords = {{Electrical and Electronic Engineering, Modeling and Simulation, Control and Systems Engineering, Electrical and Electronic Engineering, Modeling and Simulation, Control and Systems Engineering}}, number = {{3}}, pages = {{58--78}}, publisher = {{Institute of Electrical and Electronics Engineers (IEEE)}}, title = {{{Encrypted Control for Networked Systems: An Illustrative Introduction and Current Challenges}}}, doi = {{10.1109/mcs.2021.3062956}}, volume = {{41}}, year = {{2021}}, } @inbook{35774, author = {{Albers, Timm and Filipiak, Agnes and Franzen, Katja and Hellmich, Frank}}, booktitle = {{Grenzen. Gänge. Zwischen. Welten. Kontroversen – Entwicklungen – Perspektiven der Inklusionsforschung}}, editor = {{Schimek, Bernhard and Kremsner, Gertraud and Proyer, Michelle and Grubich, Rainer and Paudel, Florentine and Grubich-Müller, Regina}}, pages = {{207–214}}, publisher = {{Verlag Julius Klinkhardt}}, title = {{{Kompetenzentwicklung im inklusiven Unterricht (KinU) – eine internationale Perspektive}}}, doi = {{10.35468/5924-22}}, year = {{2021}}, } @article{22528, abstract = {{Due to the ad hoc nature of wireless acoustic sensor networks, the position of the sensor nodes is typically unknown. This contribution proposes a technique to estimate the position and orientation of the sensor nodes from the recorded speech signals. The method assumes that a node comprises a microphone array with synchronously sampled microphones rather than a single microphone, but does not require the sampling clocks of the nodes to be synchronized. From the observed audio signals, the distances between the acoustic sources and arrays, as well as the directions of arrival, are estimated. They serve as input to a non-linear least squares problem, from which both the sensor nodes’ positions and orientations, as well as the source positions, are alternatingly estimated in an iterative process. Given one set of unknowns, i.e., either the source positions or the sensor nodes’ geometry, the other set of unknowns can be computed in closed-form. The proposed approach is computationally efficient and the first one, which employs both distance and directional information for geometry calibration in a common cost function. Since both distance and direction of arrival measurements suffer from outliers, e.g., caused by strong reflections of the sound waves on the surfaces of the room, we introduce measures to deemphasize or remove unreliable measurements. Additionally, we discuss modifications of our previously proposed deep neural network-based acoustic distance estimator, to account not only for omnidirectional sources but also for directional sources. Simulation results show good positioning accuracy and compare very favorably with alternative approaches from the literature.}}, author = {{Gburrek, Tobias and Schmalenstroeer, Joerg and Haeb-Umbach, Reinhold}}, issn = {{1687-4722}}, journal = {{EURASIP Journal on Audio, Speech, and Music Processing}}, title = {{{Geometry calibration in wireless acoustic sensor networks utilizing DoA and distance information}}}, doi = {{10.1186/s13636-021-00210-x}}, year = {{2021}}, } @article{47977, abstract = {{Orange-colored crystals of the oxoferrate tellurate K12+6xFe6Te4−xO27 [x=0.222(4)] were synthesized in a potassium hydroxide hydroflux with a molar water–base ratio n(H2O)/n(KOH) of 1.5 starting from Fe(NO3)3 ⋅ 9H2O, TeO2 and H2O2 at about 200 °C. By using (NH4)2TeO4 instead of TeO2, a fine powder consisting of microcrystalline spheres of K12+6xFe6Te4−xO27 was obtained. K12+6xFe6Te4−xO27 crystallizes in the acentric cubic space group Iurn:x-wiley:09476539:media:chem202102464:chem202102464-math-0001 3d. [FeIIIO5] pyramids share their apical atoms in [Fe2O9] groups and two of their edges with [TeVIO6] octahedra to form an open framework that consists of two loosely connected, but not interpenetrating, chiral networks. The flexibility of the hinged oxometalate network manifests in a piezoelectric response similar to that of LiNbO3.The potassium cations are mobile in channels that run along the <111> directions and cross in cavities acting as nodes. The ion conductivity of cold-pressed pellets of ball-milled K12+6xFe6Te4−xO27 is 2.3×10^(−4) S ⋅ cm^(−1) at room temperature. Magnetization measurements and neutron diffraction indicate antiferromagnetic coupling in the [Fe2O9] groups.}}, author = {{Albrecht, Ralf and Hoelzel, Markus and Beccard, Henrik and Rüsing, Michael and Eng, Lukas and Doert, Thomas and Ruck, Michael}}, issn = {{0947-6539}}, journal = {{Chemistry – A European Journal}}, keywords = {{General Chemistry, Catalysis, Organic Chemistry}}, number = {{57}}, pages = {{14299--14306}}, publisher = {{Wiley}}, title = {{{Potassium Ion Conductivity in the Cubic Labyrinth of a Piezoelectric, Antiferromagnetic Oxoferrate(III) Tellurate(VI)}}}, doi = {{10.1002/chem.202102464}}, volume = {{27}}, year = {{2021}}, } @inproceedings{28095, abstract = {{Simulations are a prime performance evaluation technique for new Vehicle to Everything (V2X) methods and approaches. However, after decades of simulation-backed research, comparability and reproducibility of simulation studies is still low. In this work, we first survey road traffic simulation parameters (that is, scenarios) employed in recent scientific publications, revealing that many publications still do not adequately describe simulation scenarios to make the results comprehensible. As just one example, over 40% of the simulations using either a Manhattan Grid or Chicago Grid do not provide information about the number of lanes. At the same time, our survey reveals that, even though employed road traffic scenarios are very use case specific, there exist many commonalities. We therefore advocate basing research on use case specific variants of a set of these common standard road traffic scenarios. We accompany this recommendation with Simple Synthetic Scenarios for Sumo (SSS4S), a simple reference implementation to generate such variants.}}, author = {{Hardes, Tobias and Logan, Dalisha and Sommer, Christoph and Klingler, Florian}}, booktitle = {{13th IEEE Vehicular Networking Conference (VNC 2021)}}, isbn = {{978-1-66544-450-7}}, location = {{Virtual}}, publisher = {{IEEE}}, title = {{{Poster: Enabling Comparable and Reproducible Simulations for V2X Research}}}, doi = {{10.1109/VNC52810.2021.9644677}}, year = {{2021}}, } @article{47569, abstract = {{AbstractThe trend of increasing product diversity and decreasing production amounts led to the requirement of higher flexibility of production processes of specialty chemicals. Conventional distillation columns, mostly equipped with structured packings, lack the flexibility to handle product changeovers and throughput. Thus, a newly designed distillation column for specialty chemicals is presented. A numerical model was implemented to analyze the potential of the wetted‐wall column. The simulation of the distillation of a binary methanol/water mixture demonstrated that the wetted‐wall column can generate the desired concentration and temperature profiles. Furthermore, analyses of the pressure drop and separation efficiency with the test system chlorobenzene/ethylbenzene were conducted.}}, author = {{Reitze, Arnulf and Grünewald, Marcus and Riese, Julia}}, issn = {{0930-7516}}, journal = {{Chemical Engineering & Technology}}, keywords = {{Industrial and Manufacturing Engineering, General Chemical Engineering, General Chemistry}}, number = {{7}}, pages = {{1327--1335}}, publisher = {{Wiley}}, title = {{{Concept of a Flexible Wetted‐Wall Column for the Distillation of Specialty Chemicals}}}, doi = {{10.1002/ceat.202000468}}, volume = {{44}}, year = {{2021}}, } @article{47564, author = {{Reitze, Arnulf and Grünewald, Marcus and Riese, Julia}}, issn = {{0888-5885}}, journal = {{Industrial & Engineering Chemistry Research}}, keywords = {{Industrial and Manufacturing Engineering, General Chemical Engineering, General Chemistry}}, number = {{1}}, pages = {{740--746}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Characterization of Liquid-Phase Distribution in 3D Printed Structured Packings with an Enclosed Column Wall}}}, doi = {{10.1021/acs.iecr.1c03931}}, volume = {{61}}, year = {{2021}}, } @inproceedings{21811, 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}}, booktitle = {{Sheet Metal 2021}}, keywords = {{Tribology, Sheet Metal, Simulation}}, 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}}, } @phdthesis{52665, author = {{Hillebrand, Michael}}, isbn = {{978-3-947647-22-4}}, title = {{{Entwicklungssystematik zur Integration von Eigenschaften der Selbstheilung in Intelligente Technische Systeme }}}, volume = {{Band 403}}, year = {{2021}}, } @article{35744, author = {{Biehler, Rolf and Weigand, Hans-Georg}}, journal = {{mathematik lehren}}, number = {{228}}, pages = {{2–5}}, publisher = {{Friedrich Verlag}}, title = {{{3D-Geometrie–virtuell und real}}}, volume = {{2021}}, year = {{2021}}, } @article{35761, author = {{Höper, Lukas and Malin, Leah and Biehler, Rolf}}, journal = {{mathematik lehren}}, number = {{228}}, pages = {{19–22}}, publisher = {{Friedrich Verlag}}, title = {{{Schatten von 3D-Objekten: Modellierung mit GeoGebra 3D und Anwendungen in der Computergrafik}}}, volume = {{2021}}, year = {{2021}}, } @article{35763, author = {{Hüsing, Sven and Weiser, Niklas and Biehler, Rolf}}, journal = {{mathematik lehren}}, number = {{228}}, pages = {{23–27}}, publisher = {{Friedrich Verlag}}, title = {{{Faszination 3D-Film: Entwicklung einer 3D-Konstruktion}}}, volume = {{2021}}, year = {{2021}}, } @article{53875, author = {{Gheisariha, Elmira and Tavana, Madjid and Jolai, Fariborz and Rabiee, Meysam}}, issn = {{0378-4754}}, journal = {{Mathematics and Computers in Simulation}}, pages = {{152--178}}, publisher = {{Elsevier BV}}, title = {{{A simulation–optimization model for solving flexible flow shop scheduling problems with rework and transportation}}}, doi = {{10.1016/j.matcom.2020.08.019}}, volume = {{180}}, year = {{2021}}, } @article{27508, abstract = {{To analyze the influence of suspension kinematics on tire wear, detailed simulation models are required. In this study, a non-linear, flexible multibody model of a rear axle system is built up in the simulation software MSC Adams/View. The physical model comprises the suspension kinematics, compliance, and dynamics as well as the non-linear behavior of the tire using the FTire model. FTire is chosen because it has a separate tire tread model to compute the contact pressure and friction force distribution in the tire contact patch. To build up the simulation model, a large amount of data is needed. Bushings, spring, and damper characteristics are modeled based on measurements. For the structural components (e.g., control arms), reverse engineering techniques are used. The components are 3D-scanned, reworked, and included as a modal reduced finite element (FE)-model using component mode synthesis by Craig–Bampton. Finally, the suspension model is validated by comparing the simulated kinematic and compliance characteristics to experimental results. To investigate the interaction of suspension kinematics and tire wear, straight line driving events, such as acceleration, driving with constant velocity, and deceleration, are simulated with different setups of wheel suspension kinematics. The influence of the setups on the resulting friction work between tire and road is examined, and an exemplarily calculation of tire wear based on a validated FTire tire model is carried out. The results demonstrate, on the one hand, that the chosen concept of elasto-kinematic axle leads to a relatively good match with experimental results and, on the other hand, that there are significant possibilities to reduce tire wear by adjusting the suspension kinematics.}}, author = {{Schütte, Jan and Sextro, Walter}}, issn = {{2624-8921}}, journal = {{Vehicles}}, pages = {{233--256}}, title = {{{Tire Wear Reduction Based on an Extended Multibody Rear Axle Model}}}, doi = {{10.3390/vehicles3020015}}, year = {{2021}}, } @article{45844, abstract = {{Abstract Abductive reasoning is a non-monotonic formalism stemming from the work of Peirce. It describes the process of deriving the most plausible explanations of known facts. Considering the positive version, asking for sets of variables as explanations, we study, besides the problem of wether there exists a set of explanations, two explanation size limited variants of this reasoning problem (less than or equal to, and equal to a given size bound). In this paper, we present a thorough two-dimensional classification of these problems: the first dimension is regarding the parameterized complexity under a wealth of different parameterizations, and the second dimension spans through all possible Boolean fragments of these problems in Schaefer’s constraint satisfaction framework with co-clones (T. J. Schaefer. The complexity of satisfiability problems. In Proceedings of the 10th Annual ACM Symposium on Theory of Computing, May 1–3, 1978, San Diego, California, USA, R.J. Lipton, W.A. Burkhard, W.J. Savitch, E.P. Friedman, A.V. Aho eds, pp. 216–226. ACM, 1978). Thereby, we almost complete the parameterized complexity classification program initiated by Fellows et al. (The parameterized complexity of abduction. In Proceedings of the Twenty-Sixth AAAI Conference on Articial Intelligence, July 22–26, 2012, Toronto, Ontario, Canada, J. Homann, B. Selman eds. AAAI Press, 2012), partially building on the results by Nordh and Zanuttini (What makes propositional abduction tractable. Artificial Intelligence, 172, 1245–1284, 2008). In this process, we outline a fine-grained analysis of the inherent parameterized intractability of these problems and pinpoint their FPT parts. As the standard algebraic approach is not applicable to our problems, we develop an alternative method that makes the algebraic tools partially available again.}}, author = {{Mahmood, Yasir and Meier, Arne and Schmidt, Johannes}}, issn = {{0955-792X}}, journal = {{Journal of Logic and Computation}}, keywords = {{Logic, Hardware and Architecture, Arts and Humanities (miscellaneous), Software, Theoretical Computer Science}}, number = {{1}}, pages = {{266--296}}, publisher = {{Oxford University Press (OUP)}}, title = {{{Parameterized complexity of abduction in Schaefer’s framework}}}, doi = {{10.1093/logcom/exaa079}}, volume = {{31}}, year = {{2021}}, } @article{37822, author = {{Han, Daxin and Yang, Keke and Meschut, Gerson}}, issn = {{0924-0136}}, journal = {{Journal of Materials Processing Technology}}, keywords = {{Industrial and Manufacturing Engineering, Metals and Alloys, Computer Science Applications, Modeling and Simulation, Ceramics and Composites}}, publisher = {{Elsevier BV}}, title = {{{Mechanical joining of glass fibre reinforced polymer (GFRP) through an innovative solid self-piercing rivet}}}, doi = {{10.1016/j.jmatprotec.2021.117182}}, volume = {{296}}, year = {{2021}}, } @inproceedings{36845, author = {{Kruse, Anne and Ott, Manuel and Risse, Lena and Koch, Rainer}}, location = {{Berlin}}, publisher = {{Deutscher Verband für Materialforschung und -prüfung e.V.}}, title = {{{3D-Druck - Eine Technologie als Schlüssel zur Steigerung der Teilhabe}}}, doi = {{10.48447/Add-2021-016}}, year = {{2021}}, } @article{25556, abstract = {{AbstractIn order to reduce fuel consumption and thus pollutant emissions, the automotive industry is increasingly developing lightweight construction concepts that are accompanied by an increasing usage of aluminum materials. Due to poor weldability of aluminum in combination with other materials, mechanical joining methods such as clinching were developed and established in series production. In order to predict the 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 as well as between the sheet metal and clinching tools has a significant impact on the geometrical formation of the clinched joint. No testing methods exist that can sufficiently investigate the frictional behavior in sheet materials, especially under high interface pressures, different relative velocities, and long friction paths, while allowing a decoupled consideration of the test parameters. This paper describes the development of further testing concepts based on a proven tribo-torsion test method for determining friction 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 and steel sheet material in clinching processes is investigated using numerical simulation. Based on these findings, the developed concepts focus on determining friction coefficients at interface pressures of the above materials, yield stress, as well as the reproduction of the occurring friction conditions between sheet metal materials and tool surfaces in clinching processes using tool substitutes. Furthermore, wear investigations between sheet metal material and tool surface were carried out in the friction tests with subsequent EDX analyses of the frictioned tool surfaces. The developed method also allows an optical deformation measurement of the sheet metal material specimen by means of digital image correlation (DIC). Based on a methodological approach, the test setups and the test systems used are explained, and the functionality of the concepts is proven by experimental tests using different sheet metal materials.}}, author = {{Böhnke, Max and Rossel, Moritz Sebastian and Bielak, Christian Roman and Bobbert, Mathias and Meschut, Gerson}}, issn = {{0268-3768}}, journal = {{The International Journal of Advanced Manufacturing Technology}}, title = {{{Concept development of a method for identifying friction coefficients for the numerical simulation of clinching processes}}}, doi = {{10.1007/s00170-021-07986-4}}, year = {{2021}}, }