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THERMAL STRUCTURAL DISORDER AND MELTING TRANSITION IN HIGH-ANGLE GRAIN-BOUNDARY: A MOLECULAR-DYNAMICS STUDY

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Acta Metallurgica Sinica(English Letters) 1998年第5期11卷 365-375页

作者： S.j.Zhao Y.C.Wang j.q.you q.B.Yang L.G.Zhou H.q.Ye Xiangtan Univ Xiangtan China

A structural transition in the fcc ∑=5 (120)/[001] high-angle tilt grain-boundary(GB)is investigated by molecular-dynamics simulation. The calculations have been performed at various temperutures and the thermodynamic melting point Tm of the model system is determined by using a many-body potential fitted to copper. A thermal disorder transition in the GB region occurs well below the melting point. Our results indicate that such a transition is a continuous process and there is no evidence of premelting, which is entirely in accord with experiment results and theoretical *** we also observed that melting initiated at the interface and then propagated into the bulk quickly at or above Tm.

关键词： moleculandynamics grainboundary structural transition

quantum Transport through Magnetic Bariers

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电子显微学报 1997年第4期 61-64页

作者： j.q.you 1,2 L.D.Zhang 1 q.B.Yang 2 ( 1Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, Anhui 230031) ( 2Department of Physics, Xiangtan University, Xiangtan, Hunan 411105)

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quantum Transport through Magnetic Barriers

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Quantum Transport through Magnetic Barriers

Towards a unified nonlocal, peridynamics framework for the coarse-graining of molecular dynamics data with fractures

1996年中国青年学者物理学讨论会

作者： j.q.you~(1,2) L.D.Zhang~1 q.B.Yang~2 ~1 Institute of Solid State Physics,Chinese Academy of Sciences,Hefei,Anhui 230031 ~2 Department of Physics,Xiangtan University,Xiangtan,Hunan 411105

＜正＞We study the electron transport through magnetic *** is found that the conductance exhibits resonant structures and shows a strong dependence on the shape of the magnetic barrier.

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Applied Mathematics and Mechanics(English Edition) 2023年第7期44卷 1125-1150页

作者： H.q.you X.XU Y.YU S.SILLING M.D'ELIA j.FOSTER Department of Mathematics Lehigh UniversityBethlehemPA 18015U.S.A Department of Petroleum and Geosystems Engineering The University of Texas at AustinTX 78712-1139U.S.A. Center for Computing Research Sandia National LaboratoriesCA 94551-0969U.S.A.

Molecular dynamics(MD)has served as a powerful tool for designing materials with reduced reliance on laboratory ***,the use of MD directly to treat the deformation and failure of materials at the mesoscale is still largely beyond *** this work,we propose a learning framework to extract a peridynamics model as a mesoscale continuum surrogate from MD simulated material fracture data ***,we develop a novel coarse-graining method,to automatically handle the material fracture and its corresponding discontinuities in the MD displacement data *** by the weighted essentially non-oscillatory(WENO)scheme,the key idea lies at an adaptive procedure to automatically choose the locally smoothest stencil,then reconstruct the coarse-grained material displacement field as the piecewise smooth solutions containing ***,based on the coarse-grained MD data,a two-phase optimizationbased learning approach is proposed to infer the optimal peridynamics model with damage *** the first phase,we identify the optimal nonlocal kernel function from the data sets without material damage to capture the material stiffness ***,in the second phase,the material damage criterion is learnt as a smoothed step function from the data with *** a result,a peridynamics surrogate is *** a continuum model,our peridynamics surrogate model can be employed in further prediction tasks with different grid resolutions from training,and hence allows for substantial reductions in computational cost compared with *** illustrate the efficacy of the proposed approach with several numerical tests for the dynamic crack propagation problem in a single-layer *** tests show that the proposed data-driven model is robust and generalizable,in the sense that it is capable of modeling the initialization and growth of fractures under discretization and loading settings that are different from the ones used during training.

关键词： nonlocal model machine learning homogenization peridynamics material fracture

Stability and optoelectronic property of low-dimensional organic tin bromide perovskites

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Chinese Physics B 2021年第3期30卷 483-487页

作者： j H Lei q Tang j He M q Cai School of Science Hunan University of TechnologyZhuzhou 412007China School of Physics and Electronics Science Hunan UniversityChangsha 410082China

The toxicity and degradation of hybrid lead-halide perovskites hinder their extensive *** is thus of great importance to explore non-toxic alternative materials with excellent stability and optoelectronic *** investigate the atomic structures and optoelectronic properties of non-toxic organic tin bromide perovskites(OTBP)with one/zerodimensional(1D/0D)structures by first-principles *** calculated atomic structures show that the 1D/0D OTBPs are stable and the structure of inorganic octahedra in 0D is higher order than that in ***,the origination of exceptional purity emitting light in experiments is explained based on the calculated electronic structure.

关键词： one/zero dimensional non-toxic organic tin bromide perovskites first principle calculation stability Optoelectronic property

Effects of the Reversely Rotating Assisted Shoulder on Microstructures During the Reverse Dual-rotation Friction Stir Welding

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journal of Materials Science & Technology 2015年第4期31卷 375-383页

作者： j.q.Li H.j.Liu State Key Laboratory of Advanced Welding and joining Harbin Institute of Technology Capital Aerospace Machinery Company

The reverse dual-rotation friction stir welding(RDR-FSW) has the capability to adjust the heat generation because of the separately designed tool shoulder and tool *** welding torque exerted on the workpiece by the reversely rotating shoulder is opposite to that exerted by the rotating tool pin,so the total welding torque is reduced,which is beneficial to reducing the clamping requirement of *** the present paper,a RDR-FSW joint was welded in a condition similar to the optimal welding condition of conventional FSW,and microstructures in various zones were investigated by comparison,aiming to highlight effects of the reversely rotating assisted *** to the heat conduction of the middle cylinder and the bottom end cover on which the assisted shoulder was machined,the thermal effect of RDR-FSW was smaller than that of the conventional ***,the effect of assisted shoulder on the plastic flow or deformation of material or was constrained in a thin layer near the weld top surface,and thus the flow of material especially along the thickness direction was clearly decreased in the *** the heat-affected zone(HAZ),the precipitate coarsening was the main evolution and was completed through the dissolution of small precipitates and the continuous growth of large *** contrast,the dissolution degree of precipitates increased significantly in the thermomechanically affected zone(TMAZ),and a small amount of original meta-stable precipitates transformed to block-shaped stable *** evolutions in the shoulder affected zone(SAZ)and the weld nugget zone were similar,*** majority of original meta-stable precipitates dissolved into the matrix and the remainder transformed to stable precipitates,though the dissolution degree was greater in the *** with the conventional FSW joint,the coarsening degrees of precipitates in the HAZ and TMAZ of RDR-FSW joint were much smaller,as well as the dissolution degrees of p

关键词： Friction stir welding Reverse dual-rotation fricti

Bayesian Deep Learning for Dynamic Power System State Prediction Considering Renewable Energy Uncertainty

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journal of Modern Power Systems and Clean Energy 2022年第4期10卷 913-922页

作者： Shiyao Zhang james j.q.Yu Academy for Advanced Interdisciplinary Studies Southern University of Science and TechnologyShenzhen 518055China Department of Computer Science and Engineering Southern University of Science and TechnologyShenzhen 518055China

Modern power systems are incorporated with distributed energy sources to be environmental-friendly and ***,due to the uncertainties of the system integrated with renewable energy sources,effective strategies need to be adopted to stabilize the entire power ***,the system operators need accurate prediction tools to forecast the dynamic system states *** this paper,we propose a Bayesian deep learning approach to predict the dynamic system state in a general power ***,the input system dataset with multiple system features requires the data pre-processing ***,we obtain the dynamic state matrix of a general power system through the Newton-Raphson power flow ***,by incorporating the state matrix with the system features,we propose a Bayesian long short-term memory(BLSTM)network to predict the dynamic system state variables *** results show that the accurate prediction can be achieved at different scales of power systems through the proposed Bayesian deep learning approach.

关键词： Bayesian deep learning data analytics NewtonRaphson power flow renewable energy source system state

A brief review：experimental investigation of zonal flows and geodesic acoustic modes in fusion plasmas

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Plasma Science and Technology 2018年第9期20卷 72-84页

作者： K j ZHAO j q DONG j q LI L W YAN Southwestern Institution of Physics Chengdu 610041People＇s Republic of China

Zonal flows self-generated by turbulence play an important role in regulating turbulence,reducing transport level,and thus improve plasma confinement in fusion *** zonal flows and geodesic acoustic modes have been identified in various *** related issues,such as the poloidal and toroidal symmetries,coupling to turbulence,effects on turbulence and transport,nonlinear energy transfer between turbulence and zonal flows,dependence of the plasma parameters,roles in the confinement regime transitions etc are overviewed briefly in this *** interaction between zonal flows and magnetic islands is emphasized.

关键词： zona flow tokamak turbulence fusion plasma

A hybrid multi-degree-of-freedom vibration isolation platform for spacecrafts by the linear active disturbance rejection control

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Applied Mathematics and Mechanics(English Edition) 2020年第5期41卷 805-818页

作者： Weichao CHI S.j.MA j.q.SUN College of Science Northeastern UniversityShenyang 100819China Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines Northeastern UniversityShenyang 100819China Department of Mechanical Engineering School of EngineeringUniversity of CaliforniaMercedCA 95343U.S.A.

The hybrid vibration isolation, which takes advantages of both the passive and active approaches, has been an important solution for space missions. The objective of this paper is to design a vibration isolation platform for payloads on spacecrafts with the robust, wide bandwidth, and multi-degree-of-freedom(MDOF). The proposed solution is based on a parallel mechanism with six voice-coil motors(VCMs) as the actuators. The linear active disturbance resistance control(LADRC) algorithm is used for the active control. Numerical simulation results show that the vibration isolation platform performs effectively over a wide bandwidth, and the resonance introduced by the passive isolation is eliminated. The system robustness to the uncertainties of the structure is also verified by simulation.

关键词： hybrid vibration isolation Stewart platform linear active disturbance rejection control(LADRC) stability robustness