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Predictions of decreased surface roughness after shot peening using controlled media dimensions

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journal of Materials Science & Technology 2020年第23期58卷 120-129页

作者： Siavash Ghanbari David F.bahr School of Materials Engineering Purdue UniversityWest LafayetteIN47907USA

Shot peening induces residual compressive stresses on metallic substrates, often used to decrease fatigue crack growth. The relationship between surface roughness and the magnitude of the stress can be affected by peening media size or the extent of peening. Generally, an ideal condition from shot peening would be a high compressive residual stress and a low surface roughness, but these tend to be inversely *** study proposes a method for decreasing roughness and increasing residual stress concurrently using a distribution of shot sizes in a single shot peening passage based on finite element modeling that has been calibrated using by experimental results. Numerical models predict mixed shot sizes will create a smoother surface than using monodispersed shot at 100 % coverage. The residual stress profile for mixed shot sizes showed a broad range of compressive residual stresses in comparison with the largest impact ball size. This newly proposed method can improve the surface quality and the extent of the compressive residual stresses in a single-shot peening passage.

关键词： Numerical analysis Shot peening Roughness

Ultrafast laser-driven topological spin textures on a 2D magnet

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npj Computational Materials 2022年第1期8卷 1630-1635页

作者： Mara Strungaru mathias Augustin Elton j.G.Santos Institute for Condensed Matter Physics and Complex Systems School of Physics and AstronomyThe University of EdinburghEdinburghEH93FDUK Donostia International Physics Center(DIPC) 20018Donostia-San SebastiánBasque CountrySpain Higgs Centre for Theoretical Physics The University of EdinburghEdinburghEH93FDUK

Ultrafast laser excitations provide an efficient and low-power consumption alternative since different magnetic properties and topological spin states can be triggered and manipulated at the femtosecond(fs)***,it is largely unknown whether laser excitations already used in data information platforms can manipulate the magnetic properties of recently discovered two-dimensional(2D)van der Waals(vdW)*** we show that ultrashort laser pulses(30−85 fs)can not only manipulate magnetic domains of 2D-XY CrCl_(3)ferromagnets,but also induce the formation and control of topological nontrivial meron and antimeron spin *** observed that these spin quasiparticles are created within~100 ps after the excitation displaying rich dynamics through motion,collision and annihilation with emission of spin waves throughout the *** findings highlight substantial opportunities of using photonic driving forces for the exploration of spin textures on 2D magnetic materials towards magneto-optical topological applications.

关键词： laser excitation topological

A discrete contact model for complex arbitrary-shaped convex geometries

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Particuology 2023年第9期80卷 180-191页

作者： jan E.Marquardt Ulrich j.Römer Hermann Nirschl mathias j.Krause Lattice Boltzmann Research Group Karlsruhe Institute of TechnologyStraße am Forum 8Karlsruhe76131Germany Institute for Mechanical Process Engineering and Mechanics Karlsruhe Institute of TechnologyStraße am Forum 8Karlsruhe76131Germany Institute of Engineering Mechanics Karlsruhe Institute of TechnologyKaiserstraße 10Karlsruhe76131Germany Institute for Applied and Numerical Mathematics Karlsruhe Institute of TechnologyEnglerstraße 2Karlsruhe76131Germany

The shape of particles has a significant influence on the behavior of suspensions,as the particle-fluid,particle-particle,and particle-wall interactions depend on ***,the simultaneous consideration of complex particle shapes and four-way coupling remains a major *** is mainly due to a lack of suitable contact *** models for complex shapes have been proposed in literature,and most limit the accuracy of the particle-fluid *** this reason,this paper presents a novel contact model for complex convex particle shapes for use with partially saturated methods,in which we propose to obtain necessary contact properties,such as the indentation depth,by a discretization of the contact *** goal of the proposed model is to enable comprehensive and accurate studies of particulate flows,especially with high volume fractions,that lead to new insights and contribute to the improvement of existing industrial *** ensure correctness and sustainability,we validate the model extensively by studying cases with and without *** the latter case,we use the homogenized lattice Boltzmann *** provided investigations show a great agreement of the proposed discrete contact model with analytical solutions and the literature.

关键词： Partially saturated cells method Homogenized lattice Boltzmann method Arbitrarily shaped particle Discrete contact model Particle-resolved simulation OpenLB

Particle flow simulations with homogenised lattice Boltzmann methods

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Particuology 2017年第5期15卷 1-13页

作者： mathias j. Krause Fabian Klemens Thomas Henn Robin Trunk Hermann Nirschl Institute for Applied and Numerical Mathematics Karlsruhe Institute of Technology 76021 Karlsruhe Germany Institute for Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology 76021 Karlsruhe Germany

An alternative approach to simulating arbitrarily shaped particles submersed in viscous fluid in two dimensions is proposed, obtained by adapting the velocity parameter of the equilibrium distribution function of a standard lattice Boltzmann method （LBM）. Comparisons of exemplifying simulations to results in the literature validate the approach as well as the convergence analysis. Pressure fluctuations occurring in Ladd＇s approach are greatly reduced. In comparison with the immersed boundary method, this approach does not require cost intensive interpolations. The parallel efficiency of LBM is retained. An intrinsic momentum transfer is observed during particle-particle collisions. To demonstrate the capa- bilities of the approach, sedimentation of particles of several shapes is simulated despite omitting an explicit particle collision model.

关键词： Particulate flow simulationsArbitrarily shaped particlesLattice Boltzmann methodsValidationSedimentation processes

Parallel boron nitride nanoribbons and etch tracks formed through catalytic etching

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Nano Research 2018年第9期11卷 4874-4882页

作者： Armin Ansary Mohsen Nasseri mathias j. Boland Douglas R. Strachan Department of Physics &Astronomy University of Kentucky Lexington KY40506 USA

One-dimensional （1D） catalytic etching was investigated in few-layer hexagonal boron nitride （hBN） films. Etching of hBN was shown to share a number of similarities with that of graphitic films. As in graphitic films, etch tracks in hBN commenced at film edges and occurred predominantly along certain crystal directions of its lattice, though it was shown that the tracks were generally narrower than those of few-layer graphene under similar processing conditions. It was also shown that catalytic hydrogenation can occur completely through a few-layer hBN film, demonstrating that this process can be used in the formation of isolated low-dimensional nanoscale structures from other layered 2D materials beyond graphene. This ability for thin hBN films to be etched completely through allowed for a crystalline substrate to guide the etching process, which was demonstrated with the successful etch track formation of few-layer hBN on single-crystalline sapphire substrates. The substrate-guided etching resulted in parallel few-layer hBN nanoribbons having an average width of 32 nm and spacing of 13 nm.

关键词： hexagonal(hBN) one-dimensional catalytic etching hydrogenation etch tracks nanoribbons

Fine-Tuning by the Touch of Big Dudes: SUMOs Role in Light Signaling

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Molecular Plant 2020年第7期13卷 943-945页

作者： mathias Zeidler Institute of Plant Physiology Justus-Liebig-University GiessenSenckenbergstrasse 335390 GiessenGermany

Protein posttranslational modifications(PTM)are recognized to be important regulators for protein function,activity,localization,and/or stability and are a substantial component in the cell’s proteome *** the possible PTMs,the small ubiquitin-related modifiers(SUMO)have long had inferior standing to phosphorylation and ubiquitination.

关键词： SUMO phosphorylation stability

Auxin-Oxylipin Crosstalk:Relationship of Antagonists

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journal of Integrative Plant Biology 2011年第6期53卷 429-445页

作者： Maik Hoffmann mathias Hentrich Stephan Pollmann Centro de Biotecnología y Genómica de Plantas(U.P.M.-I.N.I.A.) Parque Científico y Tecnológico de la U.P.M. Campus de Montegancedo Ruhr-Universitt Bochum Lehrstuhl fr PflanzenphysiologieUniversittsstrasse

Phytohormones regulate a wide array of developmental processes throughout the life cycle of plants. Herein, the various plant hormones may interact additively, synergistically, or antagonistically. By their cooperation they create a delicate regulatory network whose net output largely depends on the action of specific phytohormone combinations rather than on the independent activities of separate hormones. While most classical studies of plant hormonal control have focused mainly on the action of single hormones or on the synergistic interaction of hormones in regulating various developmental processes, recent work is beginning to shed light on the crosstalk of nominally antagonistic plant hormones, such as gibberellins and auxins with oxylipins or abscisic acid. In this review, we summarize our current understanding of how two of the first sight antagonistic plant hormones, i.e. auxins and oxylipins, interact in controlling plant responses and development.

关键词： Auxin biosynthesis crosstalk hormone jasmonic acid.

Blockchain Energy: Blockchain in Future Energy Systems

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journal of Electronic Science and Technology 2019年第4期17卷 317-331页

作者： Bernd Teufel Anton Sentic mathias Barmet international institute of management in technology University of Fribourg

The ongoing,in-depth transformation of the electricity sector towards increased use of alternative,renewable energy sources extends beyond a simple decentralisation drive in the electricity *** transformation process is characterised by the interplay of old and new technologies from the energy sector as well as structural coupling with other sectors,such as the information and communications technology(ICT),enabling the technology transfer as well as market entry by information technology(IT)***-based technologies have the potential to play a key role in this transition by offering decentralised interfaces and systems as well as an alternative approach to the current organisation form of the energy *** paper discusses the applicability and prospects for blockchain-based technologies in the energy sector,which are described using the term“blockchain energy”.For the purposes of this study,blockchain energy encompasses all socio-technical and organisational configurations in the energy sector based on the utilisation of the blockchain principle for energy trading,information storage,and/or increased transparency of energy flows and energy *** the following chapters,the authors present and discuss the current transformation in the electricity market,followed by a review of the different utilisation possibilities for blockchain technologies in the energy sector and a discussion of the barriers and potential for blockchain energy using a transition studies ***,the opportunities and risks of blockchain energy are discussed.

关键词： Blockchain energy management crowd energy transition research.

Sedimentation acceleration of remanent iron oxide by magnetic flocculation

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China Particuology 2007年第1期5卷 145-150页

作者： mathias Stolarski Christian Eichholz Benjamin Fuchs Hermann Nirschl Institute of Mechanical Process Engineering and Mechanics (MVM) University of Karlsruhe 76131 Karlsruhe Germany DuPont Experimental Station Building E304 Wilmington DE 19880 USA

Sedimentation based processes are widely used in industry to separate particles from a liquid phase. Since the advent of the ＂Nanoworld＂ the demand for effective separation technologies has rapidly risen, calling for the development of new separation concepts, one of which lies in hybrid separation using the superposition of a magnetic field for magnetic particles. Possible product portfolio of such separation consists of pigment production, nanomagnetics production for electronics and bio separation, A promising step in that direction is magnetic field enhanced cake filtration, which has by now progressed from batch to continuous ooeration. In sedimentation processes in a mass force field the settling behaviour of particles strongly depends on physico-chemical properties, concentration and size distribution of the particles. By adjusting the pH, the interparticle forces, in particular the electrostatic repulsion, can be manipulated. For remanent magnetic particles such as magnetite, pre-treatment in a magnetic field could lead to a change of interparticle interactions. By magnetizing the particles apart from van der Waals attraction and electrostatic repulsion, an additional potential is induced, the magnetic attraction, which could easily dominate the other potentials and result in agglomeration in the primary minimum. By sedimentation analysis, a wide spectrum of parameters like pH, magnetic field strength and concentration have been investigated. The results show a strong increase of sedimentation velocity by magnetic flocculation of the raw suspension. This leads to a rise in throughput due to the acceleration of sedimentation kinetics by imparting a non-chemical interaction to the physico-chemical properties in the feed stream of the separation apparatus.

关键词： Magnetic flocculation Field enhanced separation Cake filtration Magnetic structuring Magnetic separation