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arXiv 2022年

作者： Cui, Chen Jiang, Kai Liu, Yun Shu, Shi Hunan Key Laboratory for Computation and Simulation in Science and Engineering Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education School of Mathematics and Computational Science Xiangtan University Hunan Xiangtan411105 China

Large sparse linear algebraic systems can be found in a variety of scientific and engineering fields, and many scientists strive to solve them in an efficient and robust manner. In this paper, we propose an interpretable neural solver, the Fourier Neural Solver (FNS), to address them. FNS is based on deep learning and Fast Fourier transform. Because the error between the iterative solution and the ground truth involves a wide range of frequency modes, FNS combines a stationary iterative method and frequency space correction to eliminate different components of the error. Local Fourier analysis reveals that the FNS can pick up on the error components in frequency space that are challenging to eliminate with stationary methods. Numerical experiments on the anisotropy diffusion equation, convection-diffusion equation, and Helmholtz equation show that FNS is more efficient and more robust than the state-of-the-art neural *** Codes 65F10 65N22 68T07 35Q68 Copyright © 2022, The Authors. All rights reserved.

关键词： Fourier analysis

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DLTree: efficient and accurate phylogeny reconstruction using the dynamical language method

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Bioinformatics (Oxford, England) 2017年第14期33卷 2214-2215页

作者： Qi Wu Zu-Guo Yu Jianyi Yang Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan University Hunan China. School of Mathematical Sciences Nankai University Tianjin China.

SUMMARY:A number of alignment-free methods have been proposed for phylogeny reconstruction over the past two decades. But there are some long-standing challenges in these methods, including requirement of huge computer memory and CPU time, and existence of duplicate computations. In this article, we address these challenges with the idea of compressed vector, fingerprint and scalable memory management. With these ideas we developed the DLTree algorithm for efficient implementation of the dynamical language model and whole genome-based phylogenetic analysis. The DLTree algorithm was compared with other alignment-free tools, demonstrating that it is more efficient and accurate for phylogeny reconstruction. AVAILABILITY AND IMPLEMENTATION:The DLTree algorithm is freely available at http://***. CONTACT:yuzuguo@*** or yangjy@***. SUPPLEMENTARY INFORMATION:Supplementary data are available at Bioinformatics online.

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A virtual element method with IMEX-SAV scheme for the incompressible magnetohydrodynamics equations

arXiv

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arXiv 2024年

作者： Dong, Xiaojing Huang, Yunqing Wang, Tianwen Hunan Key Laboratory for Computation and Simulation in Science and Engineering Key Laboratory of Intelligent Computing & Information Processing of Ministry of Education School of Mathematics and Computational Science Xiangtan University Hunan Xiangtan411105 China

This paper proposes a virtual element method (VEM) combined with a second-order implicit-explicit scheme based on the scalar auxiliary variable (SAV) method for the incompressible magnetohydrodynamics (MHD) equations. We employ the BDF2 scheme for time discretization and a conservative VEM for spatial discretization, in which the mass conservation in the velocity field is kept by taking advantage of the virtual element method’s adaptability and its divergence-free characteristics. In our scheme, the nonlinear terms are handled explicitly using the SAV method, and the magnetic field is decoupled from the velocity and pressure. This decoupling only requires solving a sequence of linear systems with constant coefficient at each time step. The stability estimate of the fully discrete scheme is developed, demonstrating the scheme is unconditionally stable. Moreover, rigorous error estimates for the velocity and magnetic field are provided. Finally, numerical experiments are presented to verify the valid of theoretical analysis. © 2024, CC BY-NC-ND.

关键词： Discrete element methods

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A preconditioned iteration method for solving saddle point problems

arXiv

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arXiv 2024年

作者： Zhang, Juan Luo, Yiyi Hunan Key Laboratory for Computation and Simulation in Science and Engineering Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education School of Mathematics and Computational Science Xiangtan University China

This paper introduces a preconditioned method designed to comprehensively address the saddle point system with the aim of improving convergence efficiency. In the preprocessor construction phase, a technical approach for solving the approximate inverse matrix of sparse matrices is presented. The effectiveness of the proposed method is demonstrated through numerical examples, emphasizing its efficacy in approximating the inverse matrix. Furthermore, the preprocessing technology includes a low-rank processing step, effectively reducing algorithmic complexity. Numerical experiments validate the effectiveness and feasibility of PSLR-GMRES in solving the saddle point system. © 2024, CC BY.

关键词： Iterative methods

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Maximum-norm error analysis of a difference scheme for the space fractional CNLS

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Applied Mathematics and computation 2015年 257卷 241-251页

作者： Dongling Wang Aiguo Xiao Wei Yang Department of Mathematics and Center for Nonlinear Studies Northwest University Xi’an Shaanxi 710127 PR China Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan University Xiangtan Hunan 411105 PR China

The difference method for the space fractional coupled nonlinear Schrödinger equations (CNLS) is studied. The fractional centered difference is used to approximate the space fractional Laplacian. This scheme conserves the discrete mass and energy. Due to the nonlocal nature of fractional Laplacian, in the classic Sobolev space, it is hard to obtain the error estimation in l ∞ . To overcome this difficulty, the fractional Sobolev space H α / 2 and a fractional norm equivalence in H α / 2 are introduced. Then the convergence of order O ( h 2 + τ 2 ) in l ∞ is proved by fractional Sobolev inequality, where h is the mesh size and τ is the time step. Numerical examples are given to illustrate the theoretical results at last.

关键词： Fractional Schrödinger equations Fractional centered difference Convergence analysis

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Preprocessed GMRES for fast solution of linear equations

arXiv

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arXiv 2024年

The article mainly introduces preprocessing algorithms for solving linear equation systems. This algorithm uses three algorithms as inner iterations, namely RPCG algorithm, ADI algorithm, and Kaczmarz algorithm. Then, it uses BA-GMRES as an outer iteration to solve the linear equation system. These three algorithms can indirectly generate preprocessing matrices, which are used for solving equation systems. In addition, we provide corresponding convergence analysis and numerical examples. Through numerical examples, we demonstrate the effectiveness and feasibility of these preprocessing methods. Furthermore, in the Kaczmarz algorithm, we introduce both constant step size and adaptive step size, and extend the parameter range of the Kaczmarz algorithm to α ∈ (0, ∞). We also study the solution rate of linear equation systems using different step sizes. Numerical examples show that both constant step size and adaptive step size have higher solution efficiency than the solving algorithm without preprocessing. © 2024, CC BY.

关键词： Linear equations

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Elliptical characteristics and numerical simulation of the PSEs of ferrofluid

Elliptical characteristics and numerical simulation of the P...

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中国力学大会（CCTAM2019）

作者： Li Mingjun Tang Shujiang Hiroshi Yamaguchi Jie Wu School of Mathematics and Computational Science Xiangtan University Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan University Department of Mechanical Engineering Doshisha University

Ferrofluid is a colloidal suspension system with magnetic nanoparticles, the overall field of study in ferrofluid has a highly interdisciplinary character in practical applications. In this paper a set of parabolized stability equations(PSEs)of ferrofluid is represented by Rosensweig equations. The characteristic analysis show that in subsonic region the nonlinear PSEs of ferrofluid are parabolical, and in supersonic region are elliptical. The PSEs of ferrofluid is solved numerically for heat conduction process and RT instability problem, respectively. The results of characteristic analysis and numerical simulation all verify that the basic characteristic of ferrofluid are not influenced by the external magnetic field, and the viscosity is the only reason for the variation of ellipticity of PSEs of ferrofluid. That is to say, the external magnetic field and the viscosity are essentially different.

关键词： Ferrofluid Magnetic nanoparticles Parabolized stability equations Ellipticity

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An improved functional dependency network model for information systems effectiveness analysis 2020

An improved functional dependency network model for informat...

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2020 International Conference on Wireless Communication and Sensor Networks, icWCSN 2020

作者： Luo, Aimin Yi, Shuanghui Liu, Junxian Kou, Yuxiao Gao, Lanlan Zhang, Mengmeng Science and Technology on Information Systems Engineering Laboratory National University of Defense Technology Changsha Hunan410073 China National Key Laboratory for Complex System Simulation Beijing China Academy of Military Science of the PLA Beijing100000 China

ISBN: (纸本)9781450377638

To address the limitations of the FDNA approach, in this paper, we analyze the dependency of the receiver node on the feeder nodes as well as the impact of the node's operability level on the system effectiveness, and improve the FDNA approach. We also propose a computing method for system effectiveness based on an improved FDNA model, and conduct relevant case verification. © 2020 ACM.

关键词： Information systems

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Highly regioselective 1,3-dipolar cycloaddition of diphenylnitrilimine to Sc₃N@I_h-C₈₀ affording a very stable, unprecedented pyrazole-ring fused derivative of endohedral metallofullerenes

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Chemical Communications 2014年第84期50卷 12710-12713页

作者： Liu, Bin Cong, Hailin Li, Xiaofang Yu, Bing Bao, Lipiao Cai, Wenting Xie, Yunpeng Lu, Xing Key Laboratory of Theoretical Chemistry and Molecular Simulation Ministry of Education Hunan Province College Key Laboratory of QSAR/QSPR School of Chemistry and Chemical Engineering Hunan University of Science and Technology Xiangtan 411201 China Lab for New Fiber Materials and Modern Textile-Growing Base State Key Laboratory College of Chemical and Environmental Engineering Qingdao University Qingdao 266071 China State Key Laboratory of Materials Processing and Die and Mold Technology School of Materials Science and Engineering Huazhong University of Science and Technology (HUST) Wuhan 430074 China

Formation of a very stable, unprecedented pyrazole-ring fused derivative of endohedral metallofullerenes was achieved by the first 1,3-dipolar cycloaddition reaction of Sc3N@C80 with diphenylnitrilimine in a highly re...

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Particle shape effect on hydrodynamics and heat transfer in spouted bed:A CFD-DEM study

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Particuology 2022年第10期20卷 10-21页

作者： Dianyu E Peng Zhou Suya Guo Jia Zeng Jiaxin Cui Youyuan Jiang Yuanxiang Lu Zeyi Jiang Zhengquan Li Shibo Kuang Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems Jiangxi University of Science and TechnologyGanzhou 341000China Ironmaking Plant Xiangtan Iron and Steel Corporation of Hunan HualingXiangtan 411101China School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China ARC Research Hub for Computational Particle Technology Department of Chemical EngineeringMonash UniversityClaytonVIC 3800Australia

Spouted bed has drawn much attention due to its good heat and mass transfer efficiency in many chemical *** the flow patterns and heat and mass transfer inside a spouted bed can help optimize the spouting ***,in this study,the effects of particle shape on the hydrodynamics and heat transfer in a spouted bed are *** is done by using a validated computational fluid dynamics-discrete element method(CFD-DEM)model,considering volume-equivalent spheres and oblate and prolate *** results are analysed in detail in terms of the flow pattern,microstruc-ture,and heat transfer *** numerical results show that the prolate spheroids(Ar=2.4)form the largest bubble from the beginning of the spouting process and rise the highest because the fluid drag forces can overcome the interlocking and particle-particle frictional *** with spherical particles,ellipsoidal spheroids have better mobility because of the stronger rotational kinetic energy resulting from the rough surfaces and nonuniform *** addition,the oblate spheroid system exhibits better heat transfer performance benefiting from the larger surface area,while prolate spheroids have poor heat transfer efficiency because of their orientation *** findings can serve as a reference for optimizing the design and operation of complex spouted beds.

关键词： Spouted bed Gas-solid flow Particle shape CFD-DEM Heat transfer

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