检索结果-内蒙古大学图书馆

arXiv 2018年

作者： Li, Huan Wang, Zhi-Yong Zheng, Xiao-Jun Liu, Yu Zhong, Yin College of Science Guilin University of Technology Guilin541004 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Software Center for High Performance Numerical Simulation China Academy of Engineering Physics Beijing100088 China Center for Interdisciplinary Studies & Key Laboratory for Magnetism and Magnetic Materials of the MoE Lanzhou University Lanzhou730000 China

By using an extended slave-boson method, we draw a global phase diagram summarizing both magnetic phases and paramagnetic (PM) topological insulating phases (TIs) in three-dimensional topological Kondo insulator (TKI). By including electron hopping (EH) up to third neighbor, we identify four strong topological insulating (STI) phases and two weak topological insulating (WTI) phases, then the PM phase diagrams characterizing topological transitions between these TIs are depicted as functions of EH, f-electron energy level and hybridization constant. We also find an insulator-metal transition from a STI phase which has surface Fermi rings and spin textures in qualitative agreement to TKI candidate SmB6. In weak hybridization regime, anti-ferromagnetic (AF) order naturally arises in the phase diagrams, and depending on how the magnetic boundary crosses the PM topological transition lines, AF phases are classified into AF topological insulator (AFTI) and non-topological AF insulator (nAFI), according to their Z2 indices. In two small regions of parameter space, two distinct topological transition processes between AF phases occur, leading to two types of AFTI, showing distinguishable surface dispersions around their Dirac points. Copyright © 2018, The Authors. All rights reserved.

关键词： Phase diagrams

来源：评论

学校读者我要写书评

暂无评论

A structural modeling approach to the solid-solution materials based on the similar atomic environment

arXiv

引用

arXiv 2018年

作者： Tian, Fuyang Lin, De-Ye Song, Hongquan Gao, Xingyu Zhao, Ya-Fan Song, Hai-Feng Institute for Applied Physics University of Science and Technology Beijing Beijing100083 China Software Center for High Performance Numerical Simulation China Academy of Engineering Physics Beijing100088 China Institute of Applied Physics and Computational Mathematics Beijing100088 China School of Physics Normal University of Zhoukou Zhoukou Henan province466001 China

Solid solution is an important way to enhance the structural and functional performances of materials. In this work, we develop a new structural modeling approach to solid-solution materials. Firstly, the description of atomic environment (AE) of an atom on sublattice in solid solution is introduced based on the concepts of atom cluster and lattice cluster. The average atomic environment of elements in the same sublattice for a certain supercell configuration could be calculated and the similarity to the desired fully disordered or short-range ordered (SRO) structure could be quantitatively evaluated. Based on the assumption that the structure model should have similar atomic environment (SAE) of the desired structure, the SAE approach is proposed by transferring the structural modeling for solid solution to an optimization problem in the configuration space. A new type of SRO parameter based on AE is introduced and the SRO could be naturally included in the SAE objective function, which could offer finer description of SRO in solid solution. Secondly, we pay efforts to enhance the practicality and functionality of this approach, including appropriate weight functions for atom clusters, implementation techniques in Metropolis Monte Carlo sampling, and support for all 230 space groups. Furthermore, the newly introduced SRO parameters are treated as constraints of the optimization problem to construct solid solution. Taking the typical quinary CoCrFeMnNi high-entropy alloy, continuous solid-solution binary TaW alloy and ternary CoCrNi medium-entropy alloy with SRO as prototypes, we apply our method in combination with ab initio calculations to investigate the structural properties and compare the calculated results with experiments. Copyright © 2018, The Authors. All rights reserved.

关键词： Calculations

来源：评论

学校读者我要写书评

暂无评论

Evaluating the Origin Intensity Factor in the Singular Boundary Method for Three-Dimensional Dirichlet Problems

引用

Advances in Applied Mathematics and Mechanics 2017年第6期9卷 1289-1311页

作者： Linlin Sun Wen Chen Alexander H-D.Cheng State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering International Center for Simulation Software in Engineering and SciencesCollege of Mechanics and MaterialsHohai UniversityNanjing 210098China Department of Computational Science and Statistics School of ScienceNantong UniversityNantongJiangsu 226019China School of Engineering University of MississippiUniversityMS 38677USA

In this paper,a new formulation is proposed to evaluate the origin intensity factors(OIFs)in the singular boundary method(SBM)for solving 3D potential problems with Dirichlet boundary *** SBM is a strong-form boundary discretization collocation technique and is mathematically simple,easy-to-program,and free of *** crucial step in the implementation of the SBM is to determine the OIFs which isolate the singularities of the fundamental ***,the inverse interpolation technique(IIT)is adopted to calculate the OIFs on Dirichlet boundary,which is time consuming for large-scale *** recent years,the new methodology has been developed to efficiently calculate the OIFs on Neumann boundary,but the Dirichlet problem remains an open *** study employs the subtracting and adding-back technique based on the integration of the fundamental solution over the whole boundary to develop a new formulation of the OIFs on 3D Dirichlet *** problems with varied domain shapes and boundary conditions are carried out to validate the effectiveness and feasibility of the proposed scheme in comparison with the SBM based on inverse interpolation technique,the method of fundamental solutions,and the boundary element method.

关键词： Origin intensity factors singular boundarymethod boundary-typemeshlessmethod potential problem fundamental solution

来源：评论

学校读者我要写书评

暂无评论

A Homogenized Function to Recover Wave Source by Solving a Small Scale Linear System of Differencing Equations

引用

Computer Modeling in engineering & sciences 2016年第5期111卷 421-435页

作者： Chein-Shan Liu Wen Chen Ji Lin Center for Numerical Simulation Software in Engineering and Sciences College of Mechanics and MaterialsHohai UniversityNanjingJiangsu 210098China Department of Civil Engineering National Taiwan UniversityTaipei 106-17Taiwan

In order to recover unknown space-dependent function G(x)or unknown time-dependent function H(t)in the wave source F(x;t)=G(x)H(t),we develop a technique of homogenized function and differencing equations,which can significantly reduce the difficulty in the inverse wave source recovery problem,only needing to solve a few equations in the problem domain,since the initial condition/boundary conditions and a supplementary final time condition are satisfied *** a consequence,the eigenfunctions are used to expand the trial solutions,and then a small scale linear system is solved to determine the expansion coefficients from the differencing *** the ill-posedness of the inverse wave source problem is greatly reduced,the present method is accurate and stable against a large noise up to 50%,of which the numerical tests confirm the observation.

关键词： Wave source recovery problem Eigenfunctions Homogenized function Differencing equations

来源：评论

学校读者我要写书评

暂无评论

Z2classification for a novel antiferromagnetic topological insulating phase in three-dimensional topological Kondo insulator

arXiv

引用

arXiv 2018年

作者： Li, Huan Zhong, Yin Liu, Yu Luo, Hong-Gang Song, Hai-Feng College of Science Guilin University of Technology Guilin541004 China Center for Interdisciplinary Studies Key Laboratory for Magnetism and Magnetic Materials of the MoE Lanzhou University Lanzhou730000 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Software Center for High Performance Numerical Simulation China Academy of Engineering Physics Beijing100088 China Beijing Computational Science Research Center Beijing100084 China

Antiferromagnetic topological insulator (AFTI) is a topological matter that breaks time-reversal symmetry. Since its proposal, explorations of AFTI in strong-correlated systems are still lacking. In this paper, we show for the first time that a novel AFTI phase can be realized in three-dimensional topological Kondo insulator (TKI). In a wide parameter region, the ground states of TKI undergo a second-order transition to antiferromagnetic insulating phases which conserve a combined symmetry of time reversal and a lattice translation, allowing us to derive a Z2-classification formula for these states. By calculating the Z2index, the antiferromagnetic insulating states are classified into (AFTI) or non-topological antiferromagnetic insulator (nAFI) in different parameter regions. On the antiferromagnetic surfaces in AFTI, we find topologically protected gapless Dirac cones inside the bulk gap, leading to metallic Fermi rings exhibiting helical spin texture with weak spin-momentum locking. Depending on model parameters, the magnetic transitions take place either between AFTI and strong topological insulator, or between nAFI and weak topological insulator. By varying some model parameters, we find a topological transition between AFTI and nAFI, driving by closing of bulk gap. Our work may account for the pressure-induced magnetism in TKI compound SmB6, and helps to explore richer AFTI phases in heavyfermion systems as well as in other strong-correlated systems. Copyright © 2018, The Authors. All rights reserved.

关键词： Antiferromagnetism

来源：评论

学校读者我要写书评

暂无评论

Theory of thin-film-mediated exfoliation of van der Waals bonded layered materials

引用

Physical Review Materials 2018年第9期2卷 094004-094004页

作者： Haoye Sun Eric W. Sirott James Mastandrea Hannah M. Gramling Yuzhi Zhou Max Poschmann Hayden K. Taylor Joel W. Ager D. C. Chrzan Department of Materials Science and Engineering University of California Berkeley California 94720 USA Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Department of Mechanical Engineering University of California Berkeley California 94720 USA Laboratory of Computational Physics Huayuan Road 6 Beijing 100088 People's Republic of China Institute of Applied Physics and Computational Mathematics Fenghao East Road 2 Beijing 100094 People's Republic of China CAEP Software Center for High Performance Numerical Simulation Huayuan Road 6 Beijing 100088 People's Republic of China

Tape-mediated mechanical exfoliation of layered materials is known to require multiple exfoliation steps and to produce small, irregularly shaped monolayer samples. Recently, it has been demonstrated experimentally that deposition of a thin layer of Au on the layer to be exfoliated prior to application of the tape can yield large monolayer samples of transition metal dichalcogenides in one exfoliation step. Here the mechanism underlying these improvements is explored using atomic scale total energy calculations to study thin-film-assisted mechanical exfoliation of both MoS2 and graphene. This study focuses on the influence of epitaxially induced biaxial strain on the exfoliated layer and how this impacts monolayer selectivity during exfoliation. For graphite modeled with a reactive empirical bond order (REBO) plus a Lennard-Jones potential, tensile biaxial strain favors monolayer exfoliation, whereas compressive strain favors multilayer exfoliation. For graphite modeled with a more accurate registry-dependent potential and for MoS2 modeled with a REBO plus a Lennard-Jones potential, both compressive and tensile biaxial strains favor monolayer exfoliation. A simple model based on the interlayer potential is introduced to explain these observations, and a linear stability analysis of this model shows that the differences between the thin-film-assisted exfoliation of the considered materials arise from the stacking structure of the layered material and the details of the interlayer potential. The potential for using this simple model to screen suitable metal films for exfoliation of other 2D materials is discussed.

关键词： 2-dimensional systems Transition metal dichalcogenides

来源：评论

学校读者我要写书评

暂无评论

Experiments in Routing Vehicles for Municipal Services

Experiments in Routing Vehicles for Municipal Services

引用

International Conference on High Performance Computing and simulation

作者： Imran Mahmood Sahar Idwan Junaid Ahmed Zubairi Izzeddin Matar Center for Research in Modeling & Simulation School of Electrical Engineering and Computer Science National University of Sciences and Technology CS and Engineering Department School of Engineering American U of Ras Al Khaimah Ras al Khaimah UAE and Comp Sci & Apps Dept Hashemite University Computer and Information Sciences Department College of Liberal Arts and Sciences State University of New York at Fredonia Faculty of Information Technology Software Engineering Department University of Petra

ISBN: (纸本)9781538678800

In this paper, route planning of waste collection trucks using R&R (Ruin and Recreate) approach is explored. We assume the trucks are guided by the central depot in selecting the optimal route for waste collection. Heuristic algorithms are simulated to find the optimal routes for the waste management fleet. Through the use of smart dumpsters that can communicate the current level of waste using sensors and communication modules, we aim to reduce the number of trucks used, the total time taken and total distance traveled by the fleet in a day. Our work is based on variations of CVRPTW (Capacitated Vehicle Routing Problem with Time Window Constraint). The central management system selects the dumpsters, based on their waste levels, in descending order, and dispatches appropriate number of trucks, with path assignments using Ruin and Recreate (R&R) approach of the VRPTW strategy. The municipal authority saves transit time, fuel cost and service time by using our approach, through a simulation of smart waste collection.

关键词： Smart Dumpster Capacitated Vehicle Routing Problem with Time Window Constraint Ruin & Recreate Search heuristic Waste management simulation

来源：评论

学校读者我要写书评

暂无评论

Solving the Inverse Problems of Wave Equation by a Boundary Functional Method

引用

Journal of Shipping and Ocean engineering 2017年第6期7卷 233-249页

作者： Chein-Shan Liu Yung-Wei Chen Center for Numerical Simulation Software in Engineering and Sciences College of Mechanics and Materials Hohai UniversityJiangsu 210098 China Department of Mechanical and Mechatronic Engineering National Taiwan Ocean University Keelung 20224 Taiwan Department of Marine Engineering National Taiwan Ocean University Keelung 20224 Taiwan

The inverse problems of wave equation to recover unknown space-time dependent functions of wave speed and wave source are solved in this paper, without needing of initial conditions and no internal measurement of data being required. After a homogenization technique, a sequence of spatial boundary functions at least the fourth-order polynomials are derived, which satisfy the homogeneous boundary conditions. The boundary functions and the zero element constitute a linear space, and then a new boundary functional is proved in the linear space, of which the energy is preserved for each dynamic energetic boundary function. The linear systems and iterative algorithms used to recover unknown wave speed and wave source functions with the dynamic energetic boundary functions as bases are developed, which converge fast at each time step. The input data are parsimonious, merely the measured boundary strains and the boundary values and slopes of unknown functions to be recovered. The accuracy and robustness of present methods are confirmed by comparing exact solutions with estimated results under large noises up to 20%.

关键词： Space-time dependent wave speed space-time dependent wave source dynamic energetic boundary functions BFM（boundary functional method） iterative method.

来源：评论

学校读者我要写书评

暂无评论

Automatic Sizing Functions for 3D Unstructured Mesh Generation

引用

Procedia engineering 2017年 203卷 245-257页

作者： Jianjun Chen Zhiwei Liu Yao Zheng Peng Zheng Jianjing Zheng Zhoufang Xiao Chuang Yu Center for Engineering and Scientific Computation Zhejiang University Hangzhou 310027 China CAEP Software Center for High Performance Numerical Simulation Beijing 100088 China College of Mathematics and Information Science Wenzhou University Wenzhou 325035 China

We present a novel algorithm to automatically create high-quality sizing functions for unstructured volume mesh generation. Firstly, appropriate techniques are proposed to create a tetrahedral background mesh, in which an initial sizing function is defined by considering geometrical factors and user-specified parameters. Then, a convex nonlinear programming problem is formulated and solved efficiently to obtain a smoothed sizing function. This function corresponds to a mesh satisfying necessary gradient constraint conditions and containing reduced number of elements. Finally, the smoothed sizing function is used by an advancing front surface mesher and a Delaunay tetrahedralization based volume mesher. With the aid of a walk-through algorithm, efficient sizing-value query schemes are developed. Various meshing experiments are presented to demonstrate that the proposed approach enables an accurate and fully automatic unstructured mesh generation pipeline.

关键词： Mesh generation Tetrahedra Element Sizing Adaptive Nonlinear programming

来源：评论

学校读者我要写书评

暂无评论

Guaranteed eigenvalue bounds for the steklov eigenvalue problem

arXiv

引用

arXiv 2018年

作者： You, Chun Guang Xie, Hehu Liu, Xuefeng CAEP Software Center for High Performance Numerical Simulation NO. 6 Huayuan Road Haidian District Beijing100088 China LSEC ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences NO. 55 Zhongguancun East Road Beijing100190 China School of Mathematical Sciences University of Chinese Academy of Sciences Beijing100049 China Graduate School of Science and Technology Niigata University 8050 Ikarashi 2-no-cho Nishi-ku Niigata City Niigata950-2181 Japan

To provide mathematically rigorous eigenvalue bounds for the Steklov eigenvalue problem, an enhanced version of the eigenvalue estimation algorithm developed by the third author is proposed, which removes the requirements of the positive definiteness of bilinear forms in the formulation of eigenvalue problems. In practical eigenvalue estimation, the Crouzeix-Raviart finite element method (FEM) along with quantitative error estimation is adopted. numerical experiments for eigenvalue problems defined on a square domain and an L-shaped domain are provided to validate the precision of computed eigenvalue bounds.65N30, 65N25, 65L15, 65B99 Copyright © 2018, The Authors. All rights reserved.

关键词： Finite element method

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：