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Complete Solution of Large Plastic Deformation of Square Plates Under Exponentially Decaying Pulse Loading

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Acta Mechanica Solida Sinica 2021年第6期34卷 922-936页

作者： Faliang Chen Lanren Tian T.X.Yu Ling Zhu Institute of Applied Physics and Computational Mathematics BeijingChina Key Laboratory of High Performance Ship Technology(Wuhan University of Technology) Ministry of EducationWuhanChina Departments of Naval Architecture Ocean and Structural Engineering School of TransportationWuhan University of TechnologyWuhanChina Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina

The rigid-plastic assumption has greatly simplified the theoretical analysis of dynamic plastic response of *** this framework,a common tool is the modal technique using approximate independent yield criteria,which leads to upper-and lower-bound solutions,but usually with poor *** this paper,by utilizing the membrane factor method(MFM),the large-deflection dynamic plastic response of square plates subjected to exponentially decaying pulse loading is analyzed by taking both the transient response phase and the exact yield criterion into *** on the combination of saturation analysis(SA)and MFM,the complete solutions and regressive formulae of saturated deflection and saturated impulse are *** the dynamic behavior of plates under rectangular pulse loading serves as a benchmark of pulse-equivalent techniques,the large plastic deformation of square plates under short-duration rectangular pulse is also analyzed in ***,by comparing the SA results of pulse-loaded square plates with different boundary conditions,it is found that the saturated deflection and saturated impulse of the fully clamped and simply supported square plates both increase linearly with the pulse amplitude,and the slopes are approximately the same,so the conversion between the SA quantities of plates with different boundary conditions can be easily achieved.

关键词： Exponentially decaying(ED)pulse loading Rectangular pulse loading Membrane factor method(MFM) Saturation analysis(SA) Complete solution

Orbital Origin of the Intrinsic Planar Hall Effect

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Physical Review Letters 2024年第5期132卷 056301-056301页

作者： Hui Wang Yue-Xin Huang Huiying Liu Xiaolong Feng Jiaojiao Zhu Weikang Wu Cong Xiao Shengyuan A. Yang Research Laboratory for Quantum Materials Singapore University of Technology and Design Singapore 487372 Singapore Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore School of Sciences Great Bay University Dongguan 523000 China Great Bay Institute for Advanced Study Dongguan 523000 China School of Physics Beihang University Beijing 100191 China Max Planck Institute for Chemical Physics of Solids Nöthnitzer Strasse 40 D-01187 Dresden Germany Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of Education Shandong University Jinan 250061 China Institute of Applied Physics and Materials Engineering University of Macau Macau China Department of Physics The University of Hong Kong Hong Kong China HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong Hong Kong China

Recent experiments reported an antisymmetric planar Hall effect, where the Hall current is odd in the in plane magnetic field and scales linearly with both electric and magnetic fields applied. Existing theories rely exclusively on a spin origin, which requires spin-orbit coupling to take effect. Here, we develop a general theory for the intrinsic planar Hall effect (IPHE), highlighting a previously unknown orbital mechanism and connecting it to a band geometric quantity—the anomalous orbital polarizability (AOP). Importantly, the orbital mechanism does not request spin-orbit coupling, so sizable IPHE can occur and is dominated by an orbital contribution in systems with weak spin-orbit coupling. Combined with first-principles calculations, we demonstrate our theory with quantitative evaluation for bulk materials TaSb2, NbAs2, and SrAs3. We further show that AOP and its associated orbital IPHE can be greatly enhanced at topological band crossings, offering a new way to probe topological materials.

关键词： Anomalous Hall effect Transport phenomena Topological materials First-principles calculations

Enhanced Thermoelectric Properties of 2D Janus Ferromagnetic LaBrI with Strain-induced Valley Degeneracy

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arXiv 2024年

作者： Kumari, Anuja Nag, Abhinav Maiti, Santanu K. Kumar, Jagdish Physics and Applied Mathematics Unit Indian Statistical Institute 203 Barrackpore Trunk Road Kolkata700 108 India Department of Physics GGDSD college Palampur Rajpur176061 India Department of Computational Sciences Central University of Punjab Bhatinda151 401 India Department of Physics Central University of Himachal Pradesh Dharamshala176 215 India

Since the successful synthesis of the MoSSe monolayer, which violated the out-of-plane mirror symmetry of TMDs monolayers, considerable and systematic research has been conducted on Janus monolayer materials. By systematically analyzing the LaBrI monolayer, we are able to learn more about the novel Janus material by focusing on the halogen family next to group VIA (S, Se, Te). The structural optimizations have been carried out using the FP-LAPW (Full Potential Linear Augmented Plane Wave) basis, as implemented in the ELK using tb-mBJ exchange correlation potential. Computed structural parameters are in good comparison with literature reports. Further, optimized crystal structures were used for computing effect of strain on electronic and thermoelectric properties using pseudo potential based Quantum espresso code. Dynamical stability predicts material can withstand strain upto 10% strain. Computed electronic structure reveals material to be indirect wide bandgap ferromagnetic material with magnetic moment 1μB. With increase in the biaxial tensile strain the band gap increases. Furthermore, the computed magneto-thermoelectric properties predicts high Seebeck coefficient of ~ 400 μV/K and low thermal conductivity of ~ 1.13 X 1014 W/msK in LaBrI which results high ZT of ~ 1.92 with 8% strain at 800 K with p-type doping. Thus, present study supports the fact that tensile strain on ferromagnetic LaBrI material can further enhance TE properties and making it to be a promising material for TE applications at higher temperature. © 2024, CC BY.

关键词： Density functional theory

Non-Abelian Braiding of Topological Edge Bands

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Physical Review Letters 2024年第23期132卷 236401-236401页

作者： Yang Long Zihao Wang Chen Zhang Haoran Xue Y. X. Zhao Baile Zhang Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link Singapore 637371 Singapore National Laboratory of Solid State Microstructures and Department of Physics Nanjing University Nanjing 210093 China Department of Physics The Chinese University of Hong Kong Shatin Hong Kong SAR China Department of Physics and HKU-UCAS Joint Institute for Theoretical and Computational Physics at Hong Kong The University of Hong Kong Hong Kong China HK Institute of Quantum Science and Technology The University of Hong Kong Hong Kong China Centre for Disruptive Photonic Technologies Nanyang Technological University Singapore 637371 Singapore

Braiding is a geometric concept that manifests itself in a variety of scientific contexts from biology to physics, and has been employed to classify bulk band topology in topological materials. Topological edge states can also form braiding structures, as demonstrated recently in a type of topological insulators known as Möbius insulators, whose topological edge states form two braided bands exhibiting a Möbius twist. While the formation of Möbius twist is inspiring, it belongs to the simple Abelian braid group B2. The most fascinating features about topological braids rely on the non-Abelianness in the higher-order braid group BN (N≥3), which necessitates multiple edge bands, but so far it has not been discussed. Here, based on the gauge enriched symmetry, we develop a scheme to realize non-Abelian braiding of multiple topological edge bands. We propose tight-binding models of topological insulators that are able to generate topological edge states forming non-Abelian braiding structures. Experimental demonstrations are conducted in two acoustic crystals, which carry three and four braided acoustic edge bands, respectively. The observed braiding structure can correspond to the topological winding in the complex eigenvalue space of projective translation operator, akin to the previously established point-gap winding topology in the bulk of the Hatano-Nelson model. Our Letter also constitutes the realization of non-Abelian braiding topology on an actual crystal platform, but not based on the “virtual” synthetic dimensions.

关键词： Acoustic metamaterials Topological phases of matter

Deep Potentials for Materials Science

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arXiv 2022年

作者： Wen, Tongqi Zhang, Linfeng Wang, Han Weinan, E. Srolovitz, David J. Department of Mechanical Engineering The University of Hong Kong Hong Kong DP Technology Beijing China AI for Science Institute Beijing China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing China HEDPS CAPT College of Engineering Peking University Beijing China School of Mathematical Sciences Peking University Beijing China Department of Mathematics and Program in Applied and Computational Mathematics Princeton University Princeton United States Shenzhen China

To fill the gap between accurate (and expensive) ab initio calculations and efficient atomistic simulations based on empirical interatomic potentials, a new class of descriptions of atomic interactions has emerged and been widely applied;i.e., machine learning potentials (MLPs). One recently developed type of MLP is the Deep Potential (DP) method. In this review, we provide an introduction to DP methods in computational materials science. The theory underlying the DP method is presented along with a step-by-step introduction to their development and use. We also review materials applications of DPs in a wide range of materials systems. The DP Library provides a platform for the development of DPs and a database of extant DPs. We discuss the accuracy and efficiency of DPs compared with ab initio methods and empirical potentials. Copyright © 2022, The Authors. All rights reserved.

关键词： Calculations

Suprathermal electrons from the anti-Stokes Langmuir decay instability cascade

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Physical Review E 2022年第4期105卷 045208-045208页

作者： Q. S. Feng R. Aboushelbaya M. W. von der Leyen B. T. Spiers R. W. Paddock I. Ouatu R. Timmis R. H. W. Wang L. H. Cao Z. J. Liu C. Y. Zheng X. T. He P. A. Norreys Department of Physics Atomic and Laser Physics sub-Department University of Oxford Clarendon Laboratory Oxford OX1 3PU United Kingdom Institute of Applied Physics and Computational Mathematics Beijing 100094 China HEDPS Center for Applied Physics and Technology Peking University Beijing 100871 China John Adams Institute Denys Wilkinson Building Oxford OX1 3RH United Kingdom

The study of parametric instabilities has played a crucial role in understanding energy transfer to plasma and, with that, the development of key applications such as inertial confinement fusion. When the densities are between 0.11nc≲ne≲0.14nc and the electron temperature is in inertial confinement fusion-relevant temperatures, anomalous hot electrons with kinetic energies above 100keV are generated. Here a new electron acceleration mechanism—the anti-Stokes Langmuir decay instability cascade of forward stimulated Raman scattering—is investigated. This mechanism potentially explains anomalous energetic electron generation in indirectly driven inertial confinement fusion experiments, it also provides a new way of accelerating electrons to higher energy for applications such as novel x-ray sources.

关键词： Inertial confinement fusion Laser driven electron acceleration Laser-plasma interactions Stimulated Brillouin & Raman scattering in plasmas Wave-wave, wave-particle interactions

Enhancing thermoelectric performance of 2D Janus ISbTe by strain engineering: A first principle study

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arXiv 2024年

Recent developments in the 2D materials laid emphasis on finding the materials with robust properties for variety of applications including the energy harvesting. The recent discovery of Janus monolayers with broken symmetry has opened up new options for engineering the properties of 2D layered materials. Present study focuses on enhancing thermoelectric properties of 2H-ISbTe 2D Janus monolayer. All the calculations have been performed using fully relaxed unit cell and employing the pseudo potential based quantum espresso code. Calculated structural parameters are in good agreement with previous literature reports. The lattice dynamics calculations predicts this monolayer can withstand a strain of up to 4% beyond which imaginary frequencies appear in the phonon dispersion curves. Computed electronic structure reveals that the monolayer is an indirect wide bandgap material and the bandgap decreases with tensile strain. Furthermore, the computed thermoelectric properties show that the studied monolayer has high Seebeck coefficient of ~ 300 μV/K and low thermal conductivity which yields reasonably high ZT of ~ 1.31 for a strain of 2% at 300 K with p-type doping. Therefore, our study signifies the fact that tensile strain and p-type doping of 2D Janus monolayer ISbTe can enhance ZT from 0.87 to 1.31 at room temperature which makes it a promising candidate for thermoelectric applications. © 2024, CC BY.

关键词： Monolayers

A General Positivity-Preserving Algorithm for Implicit High-Order Finite Volume Schemes Solving the Euler and Navier-Stokes Equations

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SSRN

SSRN 2023年

作者： Huang, Qian-Min Ren, Yu-Xin Wang, Qian Department of Engineering Mechanics Tsinghua University Beijing100084 China CAEP Software Center for High Performance Numerical Simulation Beijing100088 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Beijing Computational Science Research Center Beijing100193 China

This paper presents a general positivity-preserving algorithm for implicit high-order finite volume schemes solving Euler and Navier-Stokes equations. Previous positivity-preserving algorithms are mainly based on mathematical analyses, being highly dependent on the existence of low-order positivity-preserving numerical schemes for specific governing equations. This dependency poses serious restrictions on extending these algorithms to temporally implicit schemes, since it is difficult to know if a low-order implicit scheme is positivity-preserving. The present positivity-preserving algorithm is based on an asymptotic analysis of the solutions near local vacuum minimum points. The asymptotic analysis shows that the solutions decay exponentially with time to maintain non-negative density and pressure at a local vacuum minimum point. In its neighborhood, the exponential evolution leads to a modification of the linear evolution process, which can be modelled by a direct correction of the linear residual to ensure positivity. This correction however destroys the conservation of the numerical scheme. Therefore, a second correction procedure is proposed to recover conservation. The proposed positivity-preserving algorithm is considerably less restrictive than existing algorithms. It does not rely on the existence of low-order positivity-preserving baseline schemes and the convex decomposition of volume integrals of flow quantities. It does not need to reduce the time step size for maintaining the stability either. Furthermore, it can be implemented iteratively in the implicit dual time-stepping schemes to preserve positivity of the intermediate and converged states of the sub-iterations. It is proved that the present positivity-preserving algorithm is accuracy-preserving. Numerical results demonstrate that the proposed algorithm preserve the positive density and pressure in all test cases, and considerably improve the robustness of the numerical schemes. © 2023, The Author

关键词： Finite volume method

A general positivity-preserving algorithm for implicit high-order finite volume schemes solving the Euler and Navier-Stokes equations

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arXiv 2023年

关键词： Finite volume method