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The improved element-free Galerkin method for three-dimensional transient heat conduction problems

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Science China(Physics,Mechanics & Astronomy) 2013年第8期56卷 1568-1580页

作者： ZHANG Zan WANG JianFei cheng yumin LIEW Kim Meow School of Science East China University of Science and Technology Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai University Department of Civil and Architectural Engineering City University of Hong Kong

With the improved moving least-squares (IMLS) approximation, an orthogonal function system with a weight function is used as the basis function. The combination of the element-free Galerkin (EFG) method and the IMLS approximation leads to the development of the improved element-free Galerkin (IEFG) method. In this paper, the IEFG method is applied to study the partial differential equations that control the heat flow in three-dimensional space. With the IEFG technique, the Galerkin weak form is employed to develop the discretized system equations, and the penalty method is applied to impose the essential boundary conditions. The traditional difference method for two-point boundary value problems is selected for the time discretization. As the transient heat conduction equations and the boundary and initial conditions are time dependent, the scaling parameter, number of nodes and time step length are considered in a convergence study.

关键词：无网格伽辽金法热传导问题三维瞬态本质边界条件瞬态热传导方程偏微分方程移动最小二乘边界值问题

IN-DEPTH DEVELOPMENT OF THE THEORY OF COMPREHENSION

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外语研究 1993年第1期10卷 34-38页

作者： cheng yumin

The predominant linguistic thought in the West for the most part of the century has been one of separating language from its content. This line was pursued at first for the sake of securing a place for linguistics as an independent discipline. For Saussurc, language was no longer identified with thought, but linguistic system itself was understood as consisting of signs which are combinations of form and content. Under the strong influence

关键词：外语研究

A Fast Element-Free Galerkin Method for 3D Elasticity Problems

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Computer Modeling in Engineering & Sciences 2022年第7期131卷 55-79页

作者： Zhijuan Meng Yanan Fang yumin cheng School of Applied Science Taiyuan University of Science and TechnologyTaiyuan030024China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China

In this paper,a fast element-free Galerkin(FEFG)method for three-dimensional(3D)elasticity problems is established.The FEFG method is a combination of the improved element-free Galerkin(IEFG)method and the dimension splitting method(DSM).By using the DSM,a 3D problem is converted to a series of 2D ones,and the IEFG method with a weighted orthogonal function as the basis function and the cubic spline function as the weight function is applied to simulate these 2D problems.The essential boundary conditions are treated by the penalty method.The splitting direction uses the finite difference method(FDM),which can combine these 2D problems into a discrete system.Finally,the system equation of the 3D elasticity problem is obtained.Some specific numerical problems are provided to illustrate the effectiveness and advantages of the FEFG method for 3D elasticity by comparing the results of the FEFG method with those of the IEFG method.The convergence and relative error norm of the FEFG method for elasticity are also studied.

关键词： Improved element-free Galerkin method dimension splitting method finite difference method fast element-free Galerkin method elasticity

The dimension splitting element-free Galerkin method for 3D transient heat conduction problems

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维普期刊数据库

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Science China(Physics,Mechanics & Astronomy) 2019年第4期62卷 45-56页

作者： ZhiJuan Meng Heng cheng LiDong Ma yumin cheng Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai University School of Applied Science Taiyuan University of Science and Technology Department of Civil Engineering Shanghai University School of Materials Science and Engineering Taiyuan University of Science and Technology

By transforming a 3D problem into some related 2D problems, the dimension splitting element-free Galerkin(DSEFG) method is proposed to solve 3D transient heat conduction problems. The improved element-free Galerkin(IEFG) method is used for 2D transient heat conduction problems, and the finite difference method is applied in the splitting direction. The discretized system equation is obtained based on the Galerkin weak form of 2D problem; the essential boundary conditions are imposed with the penalty method; and the finite difference method is employed in the time domain. Four exemplary problems are chosen to verify the efficiency of the DSEFG method. The numerical solutions show that the efficiency and precision of the DSEFG method are greater than ones of the IEFG method for 3D problems.

关键词： improved element-free Galerkin (IEFG) method dimension splitting method finite difference method dimension splitting element-free Galerkin (DSEFG) method transient heat conduction problem

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临安区古树名木保护现状分析及建议对策

农业技术与装备 2024年第3期 137-139页

作者：程育民王卫国厉亮付文燕梅爱君杭州市临安区林业局浙江杭州311300 杭州市临安区青山湖国家森林公园管理局浙江杭州311300

通过对杭州市临安区域内古树名木的全面普查,全面了解了全区古树名木的基本概况。在介绍临安区古树名木资源保护现状基础上,分析了临安区古树名木保护中存在的困境与问题,提出了临安区古树名木管理保护对策。

关键词：古树名木保护现状对策临安区

Effects of Doping Trace Sm^(3+) and Gd^(3+) on Luminescent Character of Y_2O_2S∶Eu^(3+)

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Journal of Rare Earths 2005年第4期23卷 410-410页

作者： Yuan Jianhui Yuan Honghui Zhang Zhenhua cheng yumin Wang Xiaojun Department of Physics and Electronic Science Changsha University of Science ＆ Technology Changsha 410077 China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai 200083 China Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences. Changchun 130022. China

After trace Sm^3＋ ions and Gd^3＋ ions doping, the emission intensity of red phosphors Y2O2S： Eu^3 ＋ was enhanced and the voltage character （relation between emission intensity and excitation voltage） was improved while the other properties of physics and chemistry were not changed. The origins of enhancement and improvement are discussed. Probably the distortion and the defect of crystals are decreased by the substitution of Gd^3＋ for Y^3＋ instead of Eu^3＋ for Y^3＋ , and thus the Eu^3＋ crystal field is improved, and radiationless process and energy loss resulted from crystal defect are weakened, which leads to increased luminescence intensity and voltage character improvement. The overlapping fluorescent spectra of Y2O2S： Sm^3＋ emission and Y2O2S：Eu^3＋ excitation as well as Eu^3 ＋ excitation spectra transitions spectra lead to energy transfer from Sm^3 ＋ sensitization of Sm^3＋ ions fectively. containing Sm^3＋ excitation the possibility of resonance ions to Eu^3＋ ions, and the to Eu^3＋ ions is achieved effectively.

关键词： luminescence Sm^3 ＋ , Gd^3 ＋ eodoped Y2O2S ： Eu^3＋ enhancement of emission intensity improvement of voltage resistance character rare earths

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求解三维弹性力学问题的快速耦合方法

力学季刊 2023年第4期44卷 793-802页

作者：程珩梁冬琼刘燕彭飘飘程玉民太原科技大学应用科学学院山西太原030024 山西大学电力与建筑学院山西太原030006 上海大学力学与工程科学学院上海200072

将多种数值方法耦合,充分利用各种方法的优点建立新的数值方法,是求解三维复杂问题的有效途径之一.本文将无单元Galerkin(Element-Free Galerkin,EFG)方法、有限元法和维数分裂法耦合,提出了求解三维弹性力学问题的快速耦合方法(Fast Hy... 详细信息

将多种数值方法耦合,充分利用各种方法的优点建立新的数值方法,是求解三维复杂问题的有效途径之一.本文将无单元Galerkin(Element-Free Galerkin,EFG)方法、有限元法和维数分裂法耦合,提出了求解三维弹性力学问题的快速耦合方法(Fast Hybrid Method,FHM).将三维弹性力学问题分裂为若干个二维平面问题,对于每个二维问题采用罚函数法施加边界条件,并推导其相应的积分弱形式,引入Shepard基函数的移动最小二乘法建立形函数,进而推导二维平面问题的离散方程.第三个方向上采用有限元法将这些二维离散方程进行耦合,可以得到原三维弹性力学问题的快速耦合方法数值解的求解公式.通过数值算例验证了本文快速耦合方法求解三维弹性力学问题的收敛性,将数值解与解析解对比,说明了本文方法求解三维弹性力学问题的有效性.

关键词：无单元Galerkin方法 Shepard基函数维数分裂法有限元法弹性力学

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实证视角下的未成年人犯罪动因机制研究

中国监狱学刊 2022年第4期37卷 16-23页

作者：程玉敏浙江警官职业学院刑事司法系浙江杭州市310018

未成年人犯罪是多因素作用的结果,在未成年罪犯和正常未成年人这两个群体的对比研究中,发现二者的家庭成长状况、学校情况和社区交友情况存在显著差异。家庭成长环境是造成未成年人犯罪的核心因素,它不仅对未成年人犯罪有直接的作用机制... 详细信息

未成年人犯罪是多因素作用的结果,在未成年罪犯和正常未成年人这两个群体的对比研究中,发现二者的家庭成长状况、学校情况和社区交友情况存在显著差异。家庭成长环境是造成未成年人犯罪的核心因素,它不仅对未成年人犯罪有直接的作用机制,同时,它还影响着未成年人个人素质、社区交友和学校表现等其他未成年人犯罪因素。

关键词：未成年犯罪家庭环境社会支持罪犯矫治

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基于径向基函数的局部边界积分方程方法

机械工程学报 2006年第11期42卷 150-155页

作者：戴保东程玉民上海大学上海市应用数学和力学研究所

将基于径向基函数构造的具有插值特性的逼近函数应用于弹性力学问题的局部边界积分方程,推导出相应离散方程的计算公式,建立基于径向基函数的局部边界积分方程方法。与原有的局部边界积分方程方法相比,该方法不需要虚拟节点变量,而是采... 详细信息

将基于径向基函数构造的具有插值特性的逼近函数应用于弹性力学问题的局部边界积分方程,推导出相应离散方程的计算公式,建立基于径向基函数的局部边界积分方程方法。与原有的局部边界积分方程方法相比,该方法不需要虚拟节点变量,而是采用节点变量的真实解作为基本未知量,是局部边界积分方程无网格法的直接解法。由于形函数及其导数的构造相对简单,并且满足Delta函数性质,故该方法具有计算量小、精度高,可以像有限元法一样直接施加边界条件等优点。算例证明了该方法的有效性。

关键词：径向基函数多项式基函数紧支域无网格法局部边界积分方程