TY - JOUR
AB - AbstractWe consider the problem of maximization of metabolite production in bacterial cells formulated as a dynamical optimal control problem (DOCP). According to Pontryagin’s maximum principle, optimal solutions are concatenations of singular and bang arcs and exhibit the chattering or Fuller phenomenon, which is problematic for applications. To avoid chattering, we introduce a reduced model which is still biologically relevant and retains the important structural features of the original problem. Using a combination of analytical and numerical methods, we show that the singular arc is dominant in the studied DOCPs and exhibits the turnpike property. This property is further used in order to design simple and realistic suboptimal control strategies.
AU - Caillau, Jean-Baptiste
AU - Djema, Walid
AU - Gouzé, Jean-Luc
AU - Maslovskaya, Sofya
AU - Pomet, Jean-Baptiste
ID - 30861
JF - Journal of Optimization Theory and Applications
KW - Applied Mathematics
KW - Management Science and Operations Research
KW - Control and Optimization
SN - 0022-3239
TI - Turnpike Property in Optimal Microbial Metabolite Production
ER -
TY - GEN
AB - Algorithm configuration (AC) is concerned with the automated search of the
most suitable parameter configuration of a parametrized algorithm. There is
currently a wide variety of AC problem variants and methods proposed in the
literature. Existing reviews do not take into account all derivatives of the AC
problem, nor do they offer a complete classification scheme. To this end, we
introduce taxonomies to describe the AC problem and features of configuration
methods, respectively. We review existing AC literature within the lens of our
taxonomies, outline relevant design choices of configuration approaches,
contrast methods and problem variants against each other, and describe the
state of AC in industry. Finally, our review provides researchers and
practitioners with a look at future research directions in the field of AC.
AU - Schede, Elias
AU - Brandt, Jasmin
AU - Tornede, Alexander
AU - Wever, Marcel Dominik
AU - Bengs, Viktor
AU - Hüllermeier, Eyke
AU - Tierney, Kevin
ID - 30868
T2 - arXiv:2202.01651
TI - A Survey of Methods for Automated Algorithm Configuration
ER -
TY - JOUR
AU - Kobecki, Michal
AU - Scherbakov, Alexey V.
AU - Kukhtaruk, Serhii M.
AU - Yaremkevich, Dmytro D.
AU - Henksmeier, Tobias
AU - Trapp, Alexander
AU - Reuter, Dirk
AU - Gusev, Vitalyi E.
AU - Akimov, Andrey V.
AU - Bayer, Manfred
ID - 30880
IS - 15
JF - Physical Review Letters
KW - General Physics and Astronomy
SN - 0031-9007
TI - Giant Photoelasticity of Polaritons for Detection of Coherent Phonons in a Superlattice with Quantum Sensitivity
VL - 128
ER -
TY - JOUR
AU - Tuzgel, Firat
AU - Akbulut Irmak, Emine Fulya
AU - Guzel, Erkan
AU - Yucesoy, Atacan
AU - Sahin, Selim
AU - Tasdemirci, Alper
AU - Guden, Mustafa
ID - 30894
JF - Thin-Walled Structures
KW - Mechanical Engineering
KW - Building and Construction
KW - Civil and Structural Engineering
SN - 0263-8231
TI - Testing and modeling blast loading of a sandwich structure cored with a bio-inspired (balanus) core
VL - 175
ER -
TY - JOUR
AB - Federkraftbremsen sind weit verbreitete Komponenten der Antriebstechnik, ansteigend mit abnehmender Größe erreichen sie aktuell Drehzahlen von bis zu 5 000 min−1. Es besteht ein Trend zu schnell laufenden Antrieben, mit Drehzahlen von 10 000 min−1 und darüber. Bisher sind wenig Kenntnisse über das Verhalten des Reibwerts und -moments herkömmlicher Federkraftbremsen mit kostengünstigen organischen Reibbelägen bei diesen Einsatzbedingungen bekannt. Daher wurde ein Prüfstand entwickelt, der die Untersuchung bei Gleitgeschwindigkeiten von bis zu 50 m/s bei verschiedenen Lastträgheiten ermöglicht. Die Versuche zeigten, dass bei begrenzten Reibarbeiten die herkömmliche Federkraftbremse durchaus das Nennbremsmoment bei höheren Gleitgeschwindigkeiten erreicht.
AU - Schadomsky, Magnus
AU - Zimmer, Detmar
ID - 30903
IS - 04
JF - Konstruktion
KW - Federkraftbremse
KW - Gleitgeschwindigkeit
SN - 0720-5953
TI - Betrieb von Federkraftbremsen bei hohen Gleitgeschwindigkeiten
ER -
TY - JOUR
AU - Ma, Lin
AU - Pollard, Travis P.
AU - Zhang, Yong
AU - Schroeder, Marshall A.
AU - Ren, Xiaoming
AU - Han, Kee Sung
AU - Ding, Michael S.
AU - Cresce, Arthur V.
AU - Atwater, Terrill B.
AU - Mars, Julian
AU - Cao, Longsheng
AU - Steinrück, Hans-Georg
AU - Mueller, Karl T.
AU - Toney, Michael F.
AU - Hourwitz, Matt
AU - Fourkas, John T.
AU - Maginn, Edward J.
AU - Wang, Chunsheng
AU - Borodin, Oleg
AU - Xu, Kang
ID - 30910
IS - 4
JF - One Earth
KW - Earth and Planetary Sciences (miscellaneous)
KW - General Environmental Science
SN - 2590-3322
TI - Ammonium enables reversible aqueous Zn battery chemistries by tailoring the interphase
VL - 5
ER -
TY - JOUR
AB - Context: The implementation of successful measures to support immigrants' integration in cultural, social, and economic life can be considered as one of today's greatest challenges for many societies. This is especially true for adolescent immigrants who have not yet been able to finish education or gain qualifications relevant to joining the labour market. That is why many receiving countries have developed and implemented special programmes that aim at supporting immigrants' integration by facilitating their employability. Unfortunately, not much is known about the process of implementing these programmes or about how education systems, schools, and teachers are dealing with the new situation and target group. In this contribution, the implementation, development, and challenges of German Vocational Integration Classes (VIC), as an example of comparable programmes in the EU, are investigated to address this research gap. The paper considers the following exploratory research questions: (a) What challenges have been experienced by teachers and social workers in the implementation of VIC as well as in the integration of immigrants into the labour market in recent years? (b) How can these challenges be met in the long run and how should VIC be developed to better achieve its aims?
Methods: To answer these questions, a sequential qualitative study containing questionnaire and interview elements was conducted. First, teachers and social workers involved in VIC filled in a questionnaire about their experiences and experienced challenges in implementing VIC (N = 46). Then, supplementing interviews were conducted with participants from the first sample in order to generate further insights and to contextualise the findings from the first study part (N = 14).
Findings: From the respondents' answers, it appears that the VIC programme is well implemented. The results show, however, that central challenges continue to exist. This concerns, for example, legal regulations or the development of adequate curricula, but also the scope and quality of language education. In addition, problems have also been identified with regard to students' culture-specific education and their individual attitudes. These prevailing problems seem to affect schooling and educational processes. In addition, respondents report feeling left alone to deal with problems and that their experiences from their daily work in VIC and with immigrants are not sufficiently taken into account in policy and school-related decisions.
Conclusions: Although VIC seems well implemented, key challenges remain in the view of the participants. It was found that teachers cannot solve many of the identified problems themselves, as they require action at the level of policy or school organisation. For staff, this can be accompanied by increased stress and demotivation. For the young immigrants, the existing challenges can have a long-term impact on school success and transition to vocational education and training. The study thus highlights the importance of targeted and holistic strategies to support immigrant integration through education.
AU - Goller, Michael
ID - 30913
IS - 1
JF - International Journal for Research in Vocational Education and Training
KW - Immigration
KW - Educational Policy
KW - Employability
KW - Mixed Methods
KW - VET
KW - Vocational Education and Training
KW - Transitions From Education and Training to Employment
TI - Supporting Young Immigrants in Their Transition From School to Work? A Staff Perspective on Challenges of Vocational Integration Classes
VL - 9
ER -
TY - JOUR
AB - We study lobby group formation in a two-stage model where the players rst form lobby
groups that then engage in a rent-seeking contest to inuence the legislator. However, the
outcome of the contest aects all players according to the ideological distance between the
implemented policy and the players' preferences. The players can either lobby by themselves,
form a coalition of lobbyists or free ride. We nd that free coalition formation is reasonable
if either players with moderate preferences face lobby groups with extreme preferences, or if
there are two opposing coalitions with an equal number of members. Otherwise, there are
always free riders among the players.
AU - Block, Lukas
ID - 30917
JF - Quick And Easy Journal Title
KW - Group formation
KW - Rent-seeking
KW - Free riding
TI - Coalition formation versus free riding in rent-seeking contests
ER -
TY - CONF
AU - Nicolai, Marcel
AU - Zeipert, Henning
AU - Lugovtsova, Yevgeniya
AU - Bulling, Jannis
AU - Johannesmann, Sarah
AU - Prager, Jens
AU - Henning, Bernd
ID - 6590
T2 - Fortschritte der Akustik - DAGA 2022
TI - Quantification of the adhesive coupling of layered structures using guided ultrasonic waves
ER -
TY - JOUR
AB - Abstract
Batteries capable of extreme fast-charging (XFC) are a necessity for the deployment of electric vehicles. Material properties of electrodes and electrolytes along with cell parameters such as stack pressure and temperature have coupled, synergistic, and sometimes deleterious effects on fast-charging performance. We develop a new experimental testbed that allows precise and conformal application of electrode stack pressure. We focus on cell capacity degradation using single-layer pouch cells with graphite anodes, LiNi0.5Mn0.3Co0.2O2 (NMC532) cathodes, and carbonate-based electrolyte. In the tested range (10 – 125 psi), cells cycled at higher pressure show higher capacity and less capacity fading. Additionally, Li plating decreases with increasing pressure as observed with scanning electron microscopy (SEM) and optical imaging. While the loss of Li inventory from Li plating is the largest contributor to capacity fade, electrochemical and SEM examination of the NMC cathodes after XFC experiments show increased secondary particle damage at lower pressure. We infer that the better performance at higher pressure is due to more homogenous reactions of active materials across the electrode and less polarization through the electrode thickness. Our study emphasizes the importance of electrode stack pressure in XFC batteries and highlights its subtle role in cell conditions.
AU - Cao, Chuntian
AU - Steinrück, Hans-Georg
AU - Paul, Partha P
AU - Dunlop, Alison R.
AU - Trask, Stephen E.
AU - Jansen, Andrew
AU - Kasse, Robert M
AU - Thampy, Vivek
AU - Yusuf, Maha
AU - Nelson Weker, Johanna
AU - Shyam, Badri
AU - Subbaraman, Ram
AU - Davis, Kelly
AU - Johnston, Christina M
AU - Takacs, Christopher J
AU - Toney, Michael
ID - 30920
JF - Journal of The Electrochemical Society
KW - Materials Chemistry
KW - Electrochemistry
KW - Surfaces
KW - Coatings and Films
KW - Condensed Matter Physics
KW - Renewable Energy
KW - Sustainability and the Environment
KW - Electronic
KW - Optical and Magnetic Materials
SN - 0013-4651
TI - Conformal Pressure and Fast-Charging Li-Ion Batteries
VL - 169
ER -
TY - JOUR
AB - AbstractPure iron is very attractive as a biodegradable implant material due to its high biocompatibility. In combination with additive manufacturing, which facilitates great flexibility of the implant design, it is possible to selectively adjust the microstructure of the material in the process, thereby control the corrosion and fatigue behavior. In the present study, conventional hot-rolled (HR) pure iron is compared to pure iron manufactured by electron beam melting (EBM). The microstructure, the corrosion behavior and the fatigue properties were studied comprehensively. The investigated sample conditions showed significant differences in the microstructures that led to changes in corrosion and fatigue properties. The EBM iron showed significantly lower fatigue strength compared to the HR iron. These different fatigue responses were observed under purely mechanical loading as well as with superimposed corrosion influence and are summarized in a model that describes the underlying failure mechanisms.
AU - Wackenrohr, Steffen
AU - Torrent, Christof Johannes Jaime
AU - Herbst, Sebastian
AU - Nürnberger, Florian
AU - Krooss, Philipp
AU - Ebbert, Christoph
AU - Voigt, Markus
AU - Grundmeier, Guido
AU - Niendorf, Thomas
AU - Maier, Hans Jürgen
ID - 30922
IS - 1
JF - npj Materials Degradation
KW - Materials Chemistry
KW - Materials Science (miscellaneous)
KW - Chemistry (miscellaneous)
KW - Ceramics and Composites
SN - 2397-2106
TI - Corrosion fatigue behavior of electron beam melted iron in simulated body fluid
VL - 6
ER -
TY - JOUR
AB - Additive manufacturing (AM) processes are not solely used where maximum design freedom meets low lot sizes. Direct microstructure design and topology optimization can be realized concomitantly during processing by adjusting the geometry, the material composition, and the solidification behavior of the material considered. However, when complex specific requirements have to be met, a targeted part design is highly challenging. In the field of biodegradable implant surgery, a cytocompatible material of an application-adapted shape has to be characterized by a specific degradation behavior and reliably predictable mechanical properties. For instance, small amounts of oxides can have a significant effect on microstructural development, thus likewise affecting the strength and corrosion behavior of the processed material. In the present study, biocompatible pure Fe was processed using electron powder bed fusion (E-PBF). Two different modifications of the Fe were processed by incorporating Fe oxide and Ce oxide in different proportions in order to assess their impact on the microstructural evolution, the mechanical response and the corrosion behavior. The quasistatic mechanical and chemical properties were analyzed and correlated with the final microstructural appearance.
AU - Torrent, Christof J. J.
AU - Krooß, Philipp
AU - Huang, Jingyuan
AU - Voigt, Markus
AU - Ebbert, Christoph
AU - Knust, Steffen
AU - Grundmeier, Guido
AU - Niendorf, Thomas
ID - 30923
IS - 1
JF - Alloys
SN - 2674-063X
TI - Oxide Modified Iron in Electron Beam Powder Bed Fusion—From Processability to Corrosion Properties
VL - 1
ER -
TY - JOUR
AU - Schall, Christoph Wilhelm Theodor
AU - Schöppner, Volker
ID - 29947
IS - 3
JF - Polymer Engineering and Science
KW - Computing Resources Provided by the Paderborn Center for Parallel Computing
TI - Measurement of material degradation in dependence of shear rate, temperature, and residence time
VL - 62
ER -
TY - JOUR
AB - The presented paper aims to characterize the damage and fracture behavior of HX340LAD Micro-Alloyed steels using small punch test. Variations with respect to punch geometries and cutting clearance are made to describe the damage behavior of the material under different loading conditions. Experimental investigations are conducted to identify the crack initiation in the specimens. Furthermore, the numerical FEM simulations are performed to identify the stress state at crack initiation. It is shown that different stress states from shear to biaxial tension can be achieved by changing the geometries of punch and varying the cutting clearance. Moreover, it is presented how changing the configurations can influence the stress state variables: Triaxiality and lode angle parameter.
AU - Otroshi, Mortaza
AU - Meschut, Gerson
ID - 27186
IS - c
JF - Engineering Failure Analysis
KW - Ductile damage
KW - stress state
KW - small punch test
KW - triaxiality
KW - lode angle parameter
SN - 1350-6307
TI - Influence of cutting clearance and punch geometry on the stress state in small punch test
VL - 136
ER -
TY - CONF
AU - Chudalla, Nick
AU - Teutenberg, Dominik
AU - Meschut, Gerson
AU - Schneider, Miriam
AU - Smart, Dominik
ID - 30004
T2 - 22. Kolloquium: Gemeinsame Forschung in der Klebtechnik
TI - Systematisierung einer rechnergestützten Auswertemethode zur Versagensanalyse geklebter Verbindungen
ER -
TY - JOUR
AU - Reineke Matsudo, Bernhard
AU - Sain, Basudeb
AU - Carletti, Luca
AU - Zhang, Xue
AU - Gao, Wenlong
AU - Angelis, Costantino
AU - Huang, Lingling
AU - Zentgraf, Thomas
ID - 29902
IS - 12
JF - Advanced Science
KW - General Physics and Astronomy
KW - General Engineering
KW - Biochemistry
KW - Genetics and Molecular Biology (miscellaneous)
KW - General Materials Science
KW - General Chemical Engineering
KW - Medicine (miscellaneous)
SN - 2198-3844
TI - Efficient Frequency Conversion with Geometric Phase Control in Optical Metasurfaces
VL - 9
ER -
TY - JOUR
AU - Vorderbrüggen, Julian
AU - Köhler, Daniel
AU - Grüber, Bernd
AU - Troschitz, Juliane
AU - Gude, Maik
AU - Meschut, Gerson
ID - 30911
JF - Composite Structures
KW - Civil and Structural Engineering
KW - Ceramics and Composites
SN - 0263-8223
TI - Development of a rivet geometry for solid self-piercing riveting of thermally loaded CFRP-metal joints in automotive construction
VL - 291
ER -
TY - JOUR
AB - The process chain for the manufacturing of sheet metal components in mass production includes various cutting and forming operations, which influence the resulting properties of the parts and therefore subsequent manufacturing steps, such as clamping and joining. It is shown that clamping of the components leads to superimposed residual stresses and geometry changes. Therefore, the part properties differ from the initial state of the semifinished products, which has to be considered in the design of clinched joints. This paper presents an approach for coupled determination of the properties of semifinished and finished parts during deep drawing and clamping as well as their effects on the joint quality during clinching. One method for the effective and efficient determination of the properties of semifinished products and components during production is using process data from the preceding manufacturing processes, which is concretely presented in this work. In addition to the interconnection of the entire production chain, it is necessary to define relevant process data for each individual manufacturing step and to correlate the data with the material properties reliably. Therefore, the cross-process interactions of different steps of the process chain for the manufacturing of sheet metal components and the effect of process variations on subsequent manufacturing steps are investigated. Consequently, the boundary conditions for a mechanical joining process based on data from preceding process steps can be predicted.
AU - Heyser, Per
AU - Wiesenmayer, S
AU - Frey, P
AU - Nehls, T
AU - Scharr, C
AU - Flügge, W
AU - Merklein, M
AU - Meschut, Gerson
ID - 30904
JF - Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
KW - Mechanical Engineering
KW - General Materials Science
SN - 1464-4207
TI - Consideration of the manufacturing history of sheet metal components for the adaptation of a clinching process
ER -
TY - CHAP
AU - Yigitbas, Enes
AU - Sauer, Stefan
AU - Engels, Gregor
ED - Vogel-Heuser, Birgit
ED - Wimmer, Manuel
ID - 29928
T2 - Digital Transformation: Core Technologies and Emerging Topics from a Computer Science Perspective
TI - Self-Adaptive Digital Assistance Systems for Work 4.0
ER -
TY - JOUR
AU - Gao, Wenlong
AU - Sain, Basudeb
AU - Zentgraf, Thomas
ID - 30964
IS - 4
JF - Physical Review Applied
KW - General Physics and Astronomy
SN - 2331-7019
TI - Spin-Orbit Interaction of Light Enabled by Negative Coupling in High-Quality-Factor Optical Metasurfaces
VL - 17
ER -