检索结果-内蒙古大学图书馆

26th International Conference on Parallel computational Fluid Dynamics, ParCFD 2013

作者： Yue, Xiaoqiang Zhang, Hao Luo, Congshu Shu, Shi Feng, Chunsheng School of Mathematics and Computational Science Xiangtan University 411105 Hunan China Heat and Mass Transfer Technological Center Technical University of Catalonia 08222 Terrassa Spain Hunan Key Laboratory for Computation and Simulation in Science and Engineering Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education Xiangtan University 411105 Hunan China

ISBN: (纸本)9783642539619

Particulate flows are commonly encountered in both engineering and environmental applications. The discrete element method (DEM) has attracted plentiful attentions since it can predict the whole motion of the particulate flow by monitoring every single particle. However the computational capability of the method relies strongly on the numerical scheme as well as the hardware environment. In this study, a parallelization of a DEM based code titled Trubal was implemented. Numerical simulations were carried out to show the benefits of this research. It is shown that the final parallel code gave a substantial acceleration on the Trubal. By simulating 6,000 particles using a NVIDIA Tesla C2050 card together with Intel Core-Dual 2.93 GHz CPU, an average speedup of 4.69 in computational time was obtained. © Springer-Verlag Berlin Heidelberg 2014.

关键词： Finite difference method

来源：评论

学校读者我要写书评

暂无评论

Fast solution to the free return orbit's reachable domain of the manned lunar mission by deep neural network

引用

Journal of Systems engineering and Electronics 2024年第2期35卷 495-508页

作者： YANG Luyi LI Haiyang ZHANG Jin ZHU Yuehe College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China China Astronauts Research and Training Center Beijing 100094China Hunan Key Laboratory of Intelligent Planning and Simulation for Aerospace Missions Changsha 410073China

It is important to calculate the reachable domain(RD)of the manned lunar mission to evaluate whether a lunar landing site could be reached by the spacecraft. In this paper, the RD of free return orbits is quickly evaluated and calculated via the classification and regression neural networks. An efficient databasegeneration method is developed for obtaining eight types of free return orbits and then the RD is defined by the orbit’s inclination and right ascension of ascending node(RAAN) at the perilune. A classify neural network and a regression network are trained respectively. The former is built for classifying the type of the RD, and the latter is built for calculating the inclination and RAAN of the RD. The simulation results show that two neural networks are well trained. The classification model has an accuracy of more than 99% and the mean square error of the regression model is less than 0.01°on the test set. Moreover, a serial strategy is proposed to combine the two surrogate models and a recognition tool is built to evaluate whether a lunar site could be reached. The proposed deep learning method shows the superiority in computation efficiency compared with the traditional double two-body model.

关键词： manned lunar mission free return orbit reachable domain(RD) deep neural network computation efficiency

来源：评论

学校读者我要写书评

暂无评论

Anisotropic mesh generation methods based on ACVT and natural metric for anisotropic elliptic equation

引用

science CHINA Mathematics 2013年第12期56卷 2615-2630页

作者： HUANG YunQing SU YiFan WEI HuaYi YI NianYu Hunan Key Laboratory for Computation and Simulation in Science and Engineering School of Mathematics and Computational Science Xiangtan University Xiangtan 411105 China

Anisotropic meshes are known to be well-suited for problems which exhibit anisotropic solution features. Defining an appropriate metric tensor and designing an efficient algorithm for anisotropic mesh generation are two important aspects of the anisotropic mesh methodology. In this paper, we are concerned with the natural metric tensor for use in anisotropic mesh generation for anisotropic elliptic problems. We provide an algorithm to generate anisotropic meshes under the given metric tensor. We show that the inverse of the anisotropic diffusion matrix of the anisotropic elliptic problem is a natural metric tensor for the anisotropic mesh generation in three aspects: better discrete algebraic systems, more accurate finite element solution and superconvergence on the mesh nodes. Various numerical examples demonstrating the effectiveness are presented.

关键词： anisotropic mesh metric tensor superconvergence anisotropic elliptic equation

来源：评论

学校读者我要写书评

暂无评论

Finite element methods for fractional diffusion equations

引用

International Journal of Modeling, simulation, and Scientific Computing 2020年第4期11卷 32-52页

作者： Yue Zhao Chen Shen Min Qu Weiping Bu Yifa Tang LSEC ICMSECAcademy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190P.R.China School of Mathematical Sciences University of Chinese Academy of Sciences Beijing 100049 P.R.China School of Mathematics and Computational Science&Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan University Hunan 411105P.R.China

Due to the successful applications in engineering,physics,biology,finance,etc.,there has been substantial interest in fractional diffusion equations over the past few decades,and literatures on developing and analyzing efficient and accurate numerical methods for reliably simulating such equations are vast and fast *** paper gives a concise overview on finite element methods for these equations,which are divided into time fractional,space fractional and time-space fractional diffusion ***,we also involve some relevant topics on the regularity theory,the well-posedness,and the fast algorithm.

关键词： Fractional diffusion equation finite element method regularity theory well-posedness fast algorithm.

来源：评论

学校读者我要写书评

暂无评论

Underlying scaling relationships between solar activity and geomagnetic activity revealed by multifractal analyses

引用

Journal of Geophysical Research: Space Physics 2014年第9期119卷 7577-7586页

作者： Yu, Zu-Guo Anh, Vo Eastes, Richard Hunan Key Laboratory for Computation and Simulation in Science and Engineering Ministry of Education Xiangtan University Xiangtan Hunan China School of Mathematical Sciences Queensland University of Technology Brisbane QLD Australia Florida Space Institute University of Central Florida Orlando FL United States

This paper identifies some scaling relationships between solar activity and geomagnetic activity. We examine the scaling properties of hourly data for two geomagnetic indices (a_p and AE), two solar indices (solar X-rays X_l and solar flux F10.7), and two inner heliospheric indices (ion density Ni and flow speed Vs) over the period 1995-2001 by the universal multifractal approach and the traditional multifractal analysis. We found that the universal multifractal model (UMM) provides a good fit to the empirical K(q) and τ(q) curves of these time series. The estimated values of the Lévy index α in the UMM indicate that multifractality exists in the time series for a_p, AE, X_l, and Ni, while those for F10.7 and Vs are monofractal. The estimated values of the nonconservation parameter H of this model confirm that these time series are conservative which indicate that the mean value of the process is constant for varying resolution. Additionally, the multifractal K(q) and τ(q) curves, and the estimated values of the sparseness parameter C₁ of the UMM indicate that there are three pairs of indices displaying similar scaling properties, namely a_p and X_l, AE and Ni, and F10.7 and Vs. The similarity in the scaling properties of pairs (a_p,X_l) and (AE,Ni) suggests that a_p and X_l, AE and Ni are better correlated - in terms of scaling - than previous thought, respectively. But our results still cannot be used to advance forecasting of a_p and AE by X_l and Ni, respectively, due to some reasons. key Points The scaling properties of the geomagnetic and the solar indices are examinedThe results suggest that multifractality exists in a_p, AE, Xl, and ion densityThe scaling similarity of the a_p and Xl data suggests flare-storm dependence ©2014. American Geophysical Union. All Rights Reserved.

关键词： geomagnetic indices multifractal analysis scaling property solar indices universal multifractal model

来源：评论

学校读者我要写书评

暂无评论

Spring pair method of finding saddle points using the minimum energy path as a compass

引用

Physical Review E 2024年第6期110卷 064123-064123页

作者： Gang Cui Kai Jiang 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 Xiangtan Hunan 411105 China

Finding index-1 saddle points is crucial for understanding phase transitions. In this work, we propose a simple yet efficient approach, the spring pair method (SPM), to accurately locate saddle points. Without requiring the Hessian information, the SPM evolves a single pair of spring-coupled particles on an energy surface. By designing complementary drifting and climbing dynamics based on gradient decomposition, the spring pair converges onto the minimum energy path (MEP) and spontaneously aligns its orientation with the MEP tangent, providing a reliable ascent direction for efficient convergence to saddle points. The SPM fundamentally differs from traditional surface walking methods that rely on the eigenvectors of the Hessian, which may deviate from the MEP tangent and potentially lead to convergence failure or undesired saddle points. The efficiency of the SPM for finding saddle points is verified by ample examples, including Lennard-Jones clusters, Morse clusters, water clusters, and the Landau energy functional involving quasicrystal phase transitions.

关键词： Lennard-Jones potential

来源：评论

学校读者我要写书评

暂无评论

Analysis of Two-Grid Methods for Nonlinear Parabolic Equations by Expanded Mixed Finite Element Methods

引用

Advances in Applied Mathematics and Mechanics 2009年第6期1卷 830-844页

作者： Yanping Chen Peng Luan Zuliang Lu School of Mathematical Science South China Normal UniversityGuangzhou 510631GuangdongChina Mathematics Teaching and Research Group Sanshui Experimental High School of Zhongshan UniversityFoshan 528145GuangdongChina Hunan Key Lab for Computation and Simulation in Science and Engineering Department of MathematicsXiangtan UniversityXiangtan 411105HunanChina

In this paper,we present an efficient method of two-grid scheme for the approximation of two-dimensional nonlinear parabolic equations using an expanded mixed finite element *** use two Newton iterations on the fine grid in our ***,we solve an original nonlinear problem on the coarse nonlinear grid,then we use Newton iterations on the fine grid *** two-grid idea is from Xu's work[SIAM ***.,33(1996),pp.1759–1777]on standard finite *** also obtain the error estimates for the algorithms of the two-grid *** is shown that the algorithm achieve asymptotically optimal approximation rate with the two-grid methods as long as the mesh sizes satisfy h=O(H^((4k+1)/(k+1))).

关键词： Nonlinear parabolic equations two-grid scheme expanded mixed finite element methods Gronwall’s Lemma

来源：评论

学校读者我要写书评

暂无评论

Synergistic Microchannel Design and Oxygen Functionalization Electrode for High-Performance Vanadium Redox Flow Batteries

引用

Energy and Fuels 2025年第19期39卷 9170-9179页

作者： Zhang, Tao Deng, Junhai Huang, Zhifeng Xu, Ye Deng, Huafeng Zhou, Yefeng Long, Peng Liu, Li Wang, Xianyou National Base for International Science & Technology Cooperation National Local Joint Engineering Laboratory for Key Materials of New Energy Storage Battery Hunan Province Key Laboratory of Electrochemical Energy Storage and Conversion Key Laboratory of Environmentally Friend Chemistry and Applications Ministry of Education School of Chemistry Xiangtan University Xiangtan411105 China National & Local United Engineering Research Centre for Chemical Process Simulation and Intensification Chemical Process Simulation and Optimization Engineering Research Center Ministry of Education Xiangtan University Xiangtan411105 China KBC Corporation Ltd Yiyang413000 China

Vanadium redox flow batteries (VRFBs) show significant potential for grid-scale energy storage, yet face challenges due to sluggish electrode kinetics and inefficient electrolyte transport. To address these limitations, we present a dual-functional graphite felt (K-GF) electrode that synergistically integrates engineered microflow channels with oxygen-containing functional groups. The K-GF electrode is synthesized through a sustainable thermal and water vapor activation process using polyacrylonitrile (PAN) fibers, which eliminates toxic chemical treatments and minimizes water waste, thus aligning with green manufacturing principles. The engineered microflow channels enhance electrolyte dynamics, while the functional groups improve electrocatalytic activity, collaboratively addressing the existing limitations. Consequently, VRFBs equipped with K-GF electrodes demonstrate an energy efficiency of 85% at 100 mA cm-2 and a power density of 495 mW cm-2. Additionally, the battery operates consistently for 600 cycles at 300 mA cm-2 with an impressive energy efficiency of 72%. computational fluid dynamics (CFD) simulations validate that the microflow channels optimize electrolyte dynamics, ensuring uniform reactant distribution and maximizing active-site utilization. Therefore, this work provides a transformative pathway for VRFBs in practical grid storage. © 2025 American Chemical Society.

关键词： Flow batteries

来源：评论

学校读者我要写书评

暂无评论

SATURATION AND RELIABLE HIERARCHICAL A POSTERIORI MORLEY FINITE ELEMENT ERROR CONTROL

引用

Journal of computational Mathematics 2018年第6期36卷 833-844页

作者： Carsten Carstensen Dietmar Gallistl Yunqing Huang Humboldt-Universitat zu Berlin Institut fiir Mathematik Unter den Linden 6 10099 Berlin Germany Department of Applied Mathematics University of Twente P.O. Box 217 7500 AE Enschede Institute for Computational and Applied Mathematics and Hunan Key Laboratory for Computation & Simulation in Science & Engineering Xiangtan University Xiangtan 411105 China

This paper proves the saturation assumption for the nonconforming Morley finite ele- ment discretization of the biharmonic equation. This asserts that the error of the Morley approximation under uniform refinement is strictly reduced by a contraction factor smaller than one up to explicit higher-order data approximation terms. The refinement has at least to bisect any edge such as red refinement or 3-bisections on any triangle. This justifies a hierarchical error estimator for the Morley finite element method, which simply compares the discrete solutions of one mesh and its red-refinement. The related adaptive mesh-refining strategy performs optimally in numerical experiments. A remark for Crouzeix-Raviart nonconforming finite element error control is included.

关键词： Saturation Hierarchical error estimation Finite element Nonconforming Biharmonie Morley Kirchhoff plate Crouzeix-Raviart

来源：评论

学校读者我要写书评

暂无评论

Effects of substituent and solvent on the UV absorption energy of 4,4'-disubstituted stilbenes

引用

science China Chemistry 2011年第2期54卷 1735-1744页

作者： CAO ChenZhong CHEN GuanFan WU YaXin Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education Hunan Provincial University Key Laboratory of QSAR/QSPRSchool of Chemistry and Chemical EngineeringHunan University of Science and TechnologyXiangtan 411201China

Twenty five samples of 4,4'-disubstituted stilbene derivatives were synthesized, and their UV absorption max wavelengths were determined in over 10 kinds of solvents including cyclohexane, ether, chloroform, acetonitrile and ethanol, in which 242 experimental data were recorded. The effects of substituents and solvents on the energy of their UV absorption max wavelengths were discussed. The research results showed: the energy of UV absorption max wavelengths of 4,4'-disubstituted stilbenes was mainly affected by their intramolecular structure (substituent effect) in a given solvent, that is, the energy is dominated by both of excited-state substituent parameter o-~c and polar substituent constant crp. While their energy was dominated by the substituent effect and solvent effect in different kinds of solvents. An equation quantifying the energy of UV absorption max wavelengths of 4,4'-disubstituted stilbenes was developed. In addition, it is found that the n-octanol/water partition coefficient (logP) is more effective than the solvatochromic dye (ET(30)) in scaling the solvent effect. The equation employed the parameter logP has a better correlation and more specific physical meaning. Further, the energies of UV absorption max wavelengths of some reported compounds were predicted by the obtained equation, which are in agreement with their experimental values.

关键词： 4,4'-disubstituted stilbene UV absorption energy excited-state substituent parameter solvent effect

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：