查询词典 boundary element method

This paper focuses on four important aspects as follows. The first one is the establishment of variational quations which provides the mathematics theories for the finite element method of HMT; the second one is for the study of scalar/node and vector/edge finite element method; the third one is about how to solve faster for the large-sacled matrix system of scalar/node and vector/edge finite element; and the last one is achieving the forward modeling with high precision of HMT method.

主要包括四部分：建立与高频大地电磁法边值问题相等价的变分问题，为有限元数值计算奠定数理基础；标量/矢量有限元方法的研究；加速标量/矢量有限元矩阵系统方程迭代求解技术的研究；实现高频大地电磁参数精确快速正演模拟的研究。

This article mainly simulates gradually damage destruction process of rock, major in determinationg the definition of rock three-dimensional damage tensor, simplify to the damage tensor and obtain its engineering calculation method, and obtains the basic expression form of equivalent stress by equivalent stress assumption, symmetrization to the actual stress, thus obtains construction relation of the festival principle of three-dimensional damage rock mass, finally couples elasticity- plasticity with damage in the finite element equation, with reference to elasticity-plasticity gradually degenerated method thought, simulates rock damage to advance gradually the destruction process in finite element method, draws up elasticity - plasticity and damage coupling two-dimension finite element procedure with the C language in the VC contact surface, by simulating experiment destroyed process, acquires destruction image and the axial load distortion curve of model, agreement with the experimental result.

本文主要模拟岩石渐进损伤破坏过程，确定岩石三维损伤张量的定义，对损伤张量进行简化计算并得出其工程计算方法，采用等效应力假设得出有效应力的基本表达形式，对有效应力进行对称化，得出节理损伤岩体的三维本构关系，在有限元方程中实现弹塑性和损伤耦合；借鉴弹塑性渐进退化方法的思想，采用有限元的方法模拟岩石损伤渐进破坏过程，用C++语言在VC界面编制了弹塑性和损伤耦合的二维有限元程序，通过模拟已有的实验破坏过程，得出模型的破坏图像和轴向荷载变形曲线，与实验结果基本一致。

Derive the requirement to strain and displacement of Patch Test. Give the relationship between weak form of continuity equation and the Patch Test, through which the hybrid element method and quasi-conform element method are analyzed. Refined direct stiffness method and generalized conforming elements are also analyzed about why they can pass patch test. At last, as an example of using the requirement of patch test for displacement, improved the BCIZ Element.

得出分片试验对位移函数和应变函数的要求，这些要求便是一个好的有限元法所应保证的；分析了几何方程弱形式与分片试验的关系，借此分析了杂交元、拟协调元如何满足这些要求，以及在满足这些要求的同时产生的对其他条件的影响；分析了精化直接刚度法、广义协调元和双参数法如何保证分片试验的满足；最后作为位移条件的应用例子，改进了BCIZ元。

Quadratic finite volume element method s for the air pollution model in one-dimensional;2. The two-grid algorithm of the finite volume element method for second-order indefinite elliptic problems;3. A fally discrete finite volume element method is given for one-dimensional two-phase incompressible flow in porous media.

在初始网格剖分上采取分段线性函数空间作为有限体积元方法的试探函数空间，在相应的对偶网格上采取分段常数函数空间作为其检验函数空间，对一维不可压缩两相渗流驱动问题提出了全离散有限体积元方法，并得到L2-模误差估计。

A finite element analysis on the new method is presented in this paper. Based on the finite element analysis, tension tests of 18 steel bars in different diameters and holes are carried out. The results of tests, which are according with that of finite element analysis, validate the new method to determine real stresses of steel bars by drilling/enlarging small holes. Furthermore, some suggestions in using of the new method are given.

本文针对该新方法进行了有限元分析，并在此基础上进行了18种不同钢筋直径和不同孔径的带孔短钢筋拉伸试验，试验结果与相应有限元计算结果一致，验证了钻／扩孔确定钢筋实际应力的新方法，并提出了若干工程适用建议。

Firstly, two examples, which belong to static analysis and dynamic analysis respectively, were given to show the effectiveness of discrete element method. Then the discrete element method was used to perform dynamic analysis of the Chinese 1 km deep-ocean mining system. The dynamic performance of the entire mining system under different current directions was discussed and compared with that from finite element method.

首先，从静态分析和动态分析两方面，给出2个典型算例，证明该方法的有效性；然后，将离散元方法用于中国1 km深海采矿系统的动力学分析，讨论不同海流方向下整体系统的联动性能，并与有限元方法进行对比。

The main problems researched in the dissertation and achievements are as follows: The dissertation explains the science background and the theoretical and actual meaning of the task. The progress and the problems of the flow imaging technique are briefly explained. The advantages of electrical capacitance tomography are discussed. The paper discusses the formation and operating principle of ECT, and builds up the definite mathematical model by detail theoretical analyse, and establishes the Finite Element Model of the system by changing the finite boundary value problem of ECT into equivalence variation problem according to variation principle. On the basis of the FEM of the system, the paper builds the finite element model of the capacitance sensitivity field distribution and programs its finite element simulation software and proves the validity of the FEM of the ECT from different aspects. With the FEM and the qualitative analyse of the effect of each structural parameter of the capacitance transducer on its capability, this paper optimizes the structural parameters of the capacitance transducer, and obviously improves its capability. The compare of the simulated result with the static experimental result shows that the error of them is less than 0.9%.

其主要研究内容包括：阐述课题研究的学术背景及其理论与实际意义，概括总结出流动层析成像技术的发展现状和存在的问题，指出电容层析成像技术的优点；讨论电容层析成像系统的组成及工作原理，进行详尽的理论分析，以变分原理为基础，将ECT的有限元边值问题转换为等价的变分问题，从而建立系统的有限元模型；在系统有限元模型的基础上，建立敏感场的数学模型，编制有限元的仿真软件，并从不同角度证明电容层析成像系统有限元模型的正确性；利用有限元模型，定性地分析电容传感器各结构参数对其性能的影响，并对传感器结构参数进行优化设计，使其性能得到明显的改善。8电极ECT系统的仿真和静态实验结果的比较表明，它们之间的相对误差小于0。

The nearly singular integral occurs in the boundary element formulation when a source point is close to the integration element but not on this element.

边界元法中存在几乎奇异积分的计算困难。引起边界单元上几乎奇异积分的因素是源点到其邻近单元的最小距离δ。

In the numerical computation, a two-dimensional numerical method integrating finite element method and difference method was employed, where the finite element method is used to calculate the magnetic field of the permanent magnetic guideway and the difference method is used to calculate the induced current in the superconductor, then the levitation force and the lateral force were calculated by Lorentz formula.

在数值计算部分，实现了一种集有限元法与差分法为一体的数值计算方法。

The present method is more accurate than the finite element and boundary element method.

将几组典型数据的计算结果与FEM-BEM组合法计算结果的比较表明，该方法是准确和快速的。

The statistical analysis of this large set of mutations has led us to propose a diagnostic strategy that should help with the molecular work-up of optic neuropathies.

这一大系列基因突变的统计学分析引导我们提出一个诊断策略，可以帮助我们对视神经病变进行分子学的诊断检查。

The results show that the pipe grouting changes the mechanical parameters of surrounding rocks to achieve the security of engineering objectives by reinforcing surrounding rocks and bolcking the water.

研究表明：小导管注浆一方面改变了围岩的力学参数，另一方面利用浆液的固结特性可以实现堵水和加固围岩的工程目标，使隧道在开挖过程中的安全得到保障。