检索结果-南通市图书馆

Ray tracing particle image velocimetry-Challenges in the application to a packed bed

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第1期84卷 194-208页

作者： Christin Velten Mirko Ebert Christian Lessig Katharina Zahringer Lehrstuhl für Strömungsmechanik und Strömungstechnik Otto-von-Guericke-Universität Magdeburg39106MagdeburgGermany institut für simulation und graphik Otto-von-Guericke-Universität Magdeburg39106MagdeburgGermany

Ray tracing Particle Image Velocimetry(RT-PIV)is an optical technique for high resolution velocity measurements in challenging optical systems,such as transparent packed beds,that uses ray tracing to correct for distortions introduced by transparent geometries in the light *** ray tracing based correction is a post processing step applied to the raw PIV particle images before classical PIV *** this study,RT-PIV is performed in the top layer of a body centred cubic(bcc)sphere packing with gaseous flow,where optical access is obtained by the use of transparent N-BK7 glass balls with a diameter of d=40 ***-PIV introduces new experimental and numerical challenges,for example a limited field of view,illumination difficulties,a very large required depth of field and high sensitivity to geometric parameters used in the ray tracing *** challenges and their implications are the main scope and discussed in the present ***,the validation of the ray tracing reconstruction step is presented and examples for the obtained corrected vector fields in a packed bed are *** results show the strength of the method in reconstructing velocity fields behind transparent spheres that would not have been accessible by optical measurement techniques without the ray tracing correction.

关键词： Ray tracing particle image velocimetry(RT-PIV) Transparent spherical particles Packed bed Distortion correction Gas flow

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

质子磁荷半径:新疑难?

Science Bulletin 2024年第4期69卷 419-421页

作者：林勇辉 Hans-Werner Hammer Ulf-G.Meiûner Helmholtz institut für Strahlen-und Kernphysik and Bethe Center for Theoretical Physics Universität BonnBonn D-53115Germany Technische Universität Darmstadt Department of PhysicsInstitut für KernphysikDarmstadt 64289Germany ExtreMe Matter institute EMMI and Helmholtz Forschungsakademie Hessen für FAIR GSI Helmholtzzentrum für Schwerionenforschung GmbHDarmstadt 64291Germany institute for advanced simulation and institut für Kernphysik Forschungszentrum JülichJülich D-52425Germany Tbilisi State University Tbilisi 0186Georgia

The electric radius,rE,and the magnetic radius,rM,of the proton are fundamental quantities of low-energy QCD,as they are a measure of the probe-dependent size of the proton.

关键词： radius quantities fundamental

Simultaneous enhancement in electrical conductivity and Seebeck coefficient by single-to double-valley transition in a Dirac-like band

在线全文

学校读者我要写书评

暂无评论

npj Computational Materials 2022年第1期8卷 2239-2246页

作者： Yu Dai Wenjiang Zhou Hyun-Jung Kim Qichen Song Xin Qian Te-Huan Liu Ronggui Yang School of Energy and Power Engineering Huazhong University of Science and TechnologyWuhanHubei430074China peter grünberg institut and institute for advanced simulation Forschungszentrum Jülich and JARAD-52425JülichGermany Department of Chemistry and Chemical Biology Harvard UniversityCambridgeMA02138USA

SnTe possesses a single-to double-valley transition in the conduction band minimum when a compressive strain is *** a tight-binding analysis,it is shown that the variation of the band structure is attributed to the strain-induced delocalization of both the Sn-5s orbitals and Te-5p orbitals with different angular *** effect can largely increase the electron density of states near the band edge and thus keep the Fermi level of the compressed SnTe closer to it,where the electrons have lower scattering *** strain-induced double valleys lead to simultaneous increases in the electrical conductivity and the Seebeck coefficient and thereby nearly four times the enhancement of the power factor at the doping concentration of 5×10^(19) cm^(–3).This work suggests a feasible concept that can be employed to promote the power factor of a Dirac semiconductor via manipulating the valley degeneracy in the conduction band minimum.

关键词： conductivity double coefficient

Electron–plasmon and electron–magnon scattering in ferromagnets from first principles by combining GW and GT self-energies

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2021年第1期7卷 1619-1632页

作者： Dmitrii Nabok Stefan Blügel Christoph Friedrich peter grünberg institut and institut for advanced simulation Forschungszentrum JülichJülich 52425Germany

This work combines two powerful self-energy techniques:the well-known GW method and a self-energy recently developed by us that describes renormalization effects caused by the scattering of electrons with magnons and Stoner *** GT selfenergy,which is fully k-dependent and contains infinitely many spin-flip ladder diagrams,was shown to have a profound impact on the electronic band structure of Fe,Co,and *** the present work,we refine the method by combining GT with the GW *** resulting GWT spectral functions exhibit strong lifetime effects and emergent dispersion *** are in an overall better agreement with experimental spectra than those obtained with GW or GT alone,even showing partial improvements over local-spin-density approximation dynamical mean-field *** performed analysis provides a basis for applying the GWT technique to a wider class of magnetic materials.

关键词： materials theory infinitely

The AiiDA-KKR plugin and its application to highthroughput impurity embedding into a topological insulator

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2021年第1期7卷 108-116页

作者： Philipp Rüßmann Fabian Bertoldoand Stefan Blügel peter grünberg institut and institute for advanced simulation Forschungszentrum Jülich and JARAD-52425 JülichGermany

The ever increasing availability of supercomputing resources led computer-based materials science into a new era of highthroughput ***,Pizzi et *** the AiiDA framework that provides a way to automate calculations while allowing to store the full provenance of complex workflows in a *** present the development of the AiiDA-KKR plugin that allows to perform a large number of ab initio impurity embedding calculations based on the relativistic full-potential Korringa-Kohn-Rostoker green function *** capabilities of the AiiDA-KKR plugin are demonstrated with the calculation of several thousand impurities embedded into the prototypical topological insulator *** results are collected in the JuDiT database which we use to investigate chemical trends as well as Fermi level and layer dependence of physical properties of *** includes the study of spin moments,the impurity’s tendency to form in-gap states or its effect on the charge doping of the *** properties depend on the detailed electronic structure of the impurity embedded into the host crystal which highlights the need for ab initio calculations in order to get accurate predictions.

关键词： method topological embedding

Production of the X(4014)as the Spin-2 Partner of X(3872)in e^(+)e^(-)Collisions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2024年第3期41卷 30-36页

作者： Pan-Pan Shi Vadim Baru Feng-Kun Guo Christoph Hanhart Alexey Nefediev CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Departamento de F′ısica Te′orica and IFIC Centro Mixto Universidad de Valencia-CSIC Institutos de Investigaci′on de PaternaAptdo.2208546071 ValenciaSpain institut fur Theoretische Physik II Ruhr-Universitat BochumD-44780 BochumGermany Peng Huanwu Collaborative Center for Research and Education Beihang UniversityBeijing 100191China institute for advanced simulation Institut fur Kernphysik and Julich Center for Hadron PhysicsForschungszentrum JulichD-52425 JulichGermany Jozef Stefan institute Jamova 391000LjubljanaSlovenia CeFEMA Center of Physics and Engineering of Advanced MaterialsInstituto Superior T′ecnicoAvenida Rovisco Pais 11049-001 LisboaPortugal

In 2021,the Belle collaboration reported the first observation of a new structure in theψ(2S)γfinal state produced in the two-photon fusion *** the hadronic molecule picture,this new structure can be associatedwith the shallow isoscalar D*D* bound state and as such is an excellent candidate for the spin-2 partner of the X(3872)with the quantum numbers J^(PC)=2^(++)conventionally named X_(2).

关键词： process X(3872) Collisions

Evolution of N=20,28,50 shell closures in the 20≤Z≤30 region in deformed relativistic Hartree-Bogoliubov theory in continuum

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2024年第1期48卷 144-153页

作者：郑茹尤孙向向申国防耿立升 School of Physics Beihang UniversityBeijing102206China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China institut für Kernphysik Institute for Advanced Simulation and Jülich Center for Hadron PhysicsForschungszentrum JülichD-52425 JülichGermany CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China Peng Huanwu Collaborative Center for Research and Education Beihang UniversityBeijing 100191China Beijing Key Laboratory of advanced Nuclear Materials and Physics Beihang UniversityBeijing 102206China Southern Center for Nuclear-Science Theory(SCNT) Institute of Modern PhysicsChinese Academy of SciencesHuizhou 516000China

Magicity,or shell closure,plays an important role in our understanding of complex nuclear *** this work,we employ one of the state-of-the-art density functional theories,the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc)with the density functional PC-PK1,to investigate the evolution of the N=20,28,50 shell closures in the 20≤Z≤30 *** show how these three conventional shell closures evolve from the proton drip line to the neutron drip line by studying the charge radii,two-neutron separation energies,two-neutron gaps,quadrupole deformations,and single-particle *** particular,we find that in the 21≤Z≤27 region,the N=50 shell closure disappears or becomes quenched,mainly due to the deformation ***,both experimental data and theoretical predictions indicate that the N=28 shell closure disappears in the Mn isotopic chain,mainly due to the deformation *** DRHBc theory predicts the existence of the N=20 shell closure in the Ca,Sc,and Ti isotopic chains,but the existing data for the Ti isotopes suggest the contrary,and therefore further research is needed.

关键词： shell evolution covariant density functional theories magic numbers

Sparse identification-assisted exploration of the atomic-scale deformation mechanism in multiphase CoCrFeNi high-entropy alloys

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第4期67卷 1124-1132页

作者： XIAO Lu GUO XiaoXiang SUN YuTong WANG Gang LONG WeiMin LIAW peter K. REN JingLi School of Mathematics and Statistics Zhengzhou UniversityZhengzhou 450001China Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China institute of Materials Shanghai UniversityShanghai 200444China SKL of advanced Brazing Metals&Technology Zhengzhou Research Institute of Mechanical EngineeringZhengzhou 450001China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996USA

This study investigated the atomic-scale deformation mechanism of multiphase CoCrFeNi high-entropy alloys(HEAs)at liquid helium,liquid nitrogen,and room temperatures.A million-atom multiphase HEA was prepared using molecular dynamics simulation involving melt and quench *** HEA exhibited high-density dislocations and some twins,consistent with experimental *** analysis revealed an inconsistent evolution of the microstructure under tensile *** particular,the elastic and initial plastic stages exhibited an increase in the disordered structure at the expense of the face-centered cubic and hexagonal close-packed structures,followed by a subsequent transformation involving multiple structural ***,through sparse identification,a model depicting microstructural evolution during tension was extracted for the CoCrFeNi HEA at three typical temperatures and three tensile *** model highlighted the importance of the body-centered cubic structure in the evolutionary process.

关键词： high-entropy alloy data-driven method microstructure evolution multiphase structure molecular dynamics simulation

Electric-field driven stability control of skyrmions in an ultrathin transition-metal film

在线全文

学校读者我要写书评

暂无评论

npj Computational Materials 2022年第1期8卷 992-1000页

作者： Souvik Paul Stefan Heinze peter grünberg institut and institute for advanced simulation Forschungszentrum Jülich and JARA52425JülichGermany institute of Theoretical Physics and Astrophysics Christian-Albrechts-Universität zu KielLeibnizstrasse 1524098KielGermany

To realize future spintronic applications with magnetic skyrmions—topologically nontrivial swirling spin structures—it is essential to achieve efficient writing and deleting capabilities of these ***-field assisted nucleation and annihilation is a promising route,however,the understanding of the underlying microscopic mechanisms is still ***,we show how the stability of individual magnetic skyrmions in an ultrathin transition-metal film can be controlled via external electric *** demonstrate based on density functional theory that it is important to consider the changes of all interactions with electric field,i.e.,the pair-wise exchange,the Dzyaloshinskii–Moriya interaction,the magnetocrystalline anisotropy energy,and the higher-order exchange *** energy barriers for electric-field assisted skyrmion writing and deleting obtained via atomistic spin simulations vary by up to a factor of three more than the variations of the interactions calculated from *** surprising effect originates from the electric-field dependent size of metastable skyrmions at a fixed magnetic *** large changes in lifetimes allow the possibility of electric-field assisted thermally activated writing and deleting of skyrmions.

关键词： field stability film