边界元法

The main objective of this dissertation was to develop methodologies with capability of engineering application for simulating flow in fractured rock using discontinuum models. The study work includes three parts. In the first part, numerical methodology of three-dimensional discrete fracture network model casing on hybrid BEM-channel was presented, and the technique for improve the model's computing efficiency was also studied. Firstly in this part, computer simulation methodology based on the Baechermodel for generating network of discrete fractures was presented, which includes the follow details: probability distributions of fracture density,orientation, trace length, size, and aperture and estimation of their statistical parameters; stochastic models of fracture network; Monte-Carlo's simulation method; numerical simulation procedure and technicality.

给出了离散裂隙网络模型所依据的基本假定；发展了基于Baecher模型的离散裂隙网络计算机随机生成技术：详细地推导了单裂隙渗流和多裂隙相交网络渗流的边界单元法公式，发展了离散裂隙网络中稳态渗流的边界元数值技术，并且讨论了相关的具体数值技术细节，如角点的处理方法，单元的自动剖分等：描述了混合边界元—管流模拟方法及其数值实现；研究了裂隙网络的简化方法，并针对裂隙网络边界元法的特点提出了一种改进的分块三角分解法。

In sphere approximate, GPS/Gravity-BVP is Neumann problem over exterior spherical domains. Then the natural boundary reduction, suggested by Feng and Yu, is applied to deal with the three dimensional problems. By expansion in spherical harmonics, the natural integral equations of harmonic problems over exterior spherical domains are obtained. Meanwhile, a numerical method for solving geodetic BVP is developed.

在球近似下将GPS-边值问题转化为Neumann外问题，用自然边界元法进行自然边界归化，得到自然边界积分方程，再求自然边界积分方程的数值解，与其他边界元方法相比，自然边界元法的计算量大大减小，并且具有很好的逼近性质，能有效地处理奇异积分，是求解GPS-边值问题有效方法。

The direct problem was solved by DRBEM, which eliminated the drawback of domain integral for classical boundary element method and resulted in pure boundary integral calculation.

正问题采用双倒易边界元法求解，该法避免了传统边界元法需进行区域积分的缺点，仅需纯边界积分计算。

Based on the additional information such as displacements or stresses provided at several internal or boundary points in the structure,combined with stochastic boundary element method and optimization technique,the basic model of the prediction of the structural reliability by inverse analysis of boundary element method is presented in this p.

本文利用随机边界元法与非线性优化技术相结合，根据弹性体内或边界上的位移、应力等附加信息，建立了结构可靠性预测的边界元逆分析法的基本模型，算例证明了该理论的有效

Aimed at increasing the accuracy and speed of BEM, meanwhile decreasing taken up memory, this dissertation has studied singular integrals and nearly singular integrals of BEM, surface BEM character and multipole BEM delaminating and storing technology, and put forward high precision fast BEM. And appling this method the electric potential and electric field intensities distribution of the UHV insulators are calculated preliminarily.

本论文以提高边界元的精度和计算速度，降低计算机内存占用为目标，研究了边界元的奇异积分和接近奇异积分计算方法、曲面边界元特性以及多极子边界元分层和存储技术，提出了高精度快速边界元法，并运用该方法初步计算了特高压绝缘子上电位和电场强度分布。

Aimed at increasing the accuracy and speed of BEM , meanwhile decreasing taken up memory, this dissertation has studied singular integrals and nearly singular integrals of BEM , surface BEM character and multipole BEM delaminating .

本论文以提高边界元的精度和计算速度，降低计算机内存占用为目标，研究了边界元的奇异积分和接近奇异积分计算方法、曲面边界元特性以及多极子边界元分层和存储技术，提出了高精度快速边界元法，并运用该方法初步计算了特高压绝缘子上电位和电场强度分布。

In Chapter two, it is given of the three-dimensional boundary element and the boundary element space, Sobolev space for the contact boundary element problem with friction; it is proved of existence and uniqueness of the solution by variation inequality for the contact Boundary Element Method matrix equation under two kinds of condition that the contact zone is fixed and the contact zone is increasing along with the load; it is given of the expressionfor the error of the exact solution and the boundary element solution.

第2章，给出三维边界单元及边界元空间、有摩擦接触边界元问题的Sobolev空间，利用变分不等式证明了不变接触区和随载荷可变接触区两种情况下的接触边界元法矩阵方程解的存在唯一性，给出了准确解与边界元解的误差表达式，还证明了三维弹塑性摩擦接触问题凝缩矩阵解的存在唯一性，为三维弹塑性摩擦接触边界元法奠定数学基础。

In the new method for two-dimensional problems the line integrals onboundary elements are converted into the evaluation of potentialfunctions at the ends of these elements.For three-dimensional cases,thesurface integrals on the usual boundary elements are transformed,through an application of Stokes'theorem,into line integrals on thebounding contours of these elements.

边界轮廓法是刚刚出现的一种新型的边界元法，该方法的核心是利用边界积分方程被积函数散度为零的特性，对二维问题，原积分方程中沿边界单元的线积分被化为单元两端点势函数之差计算，对三维问题，将边界单元上的面积分转变为沿单元轮廓的线积分，它是一种十分简便有效的边界元新技术。

According to GBEM,a fullysymmetric Galerkin multi-zone boundary element methodisproposed in this paper.Based on regarding the coefficient matrix as thesum of a symmetric part and a non-symmetric one,this problem is solvedby adopting a proper assembly.Following this treatment,GBEM will beextended for a wide scope.

针对这一问题，(1)本文在单域伽辽金边界元的基础上，采用先生成各子域的方程，将系数矩阵表达为对称部分与非对称部分之和，通过恰当的集成方式，消除非对称部分的方法，提出了一种完全对称的伽辽金边界元子域法，拓宽了伽辽金边界元法的使用范围。

It is proved that the method using the BEM to calculate the load distributions on the contact lines of involute gear pair, in which the applied load is taken in the form of a concentrated one at a single node, is not suitable. A method in which the tractions of the BEM are made to imitate the Hertzian pressure of the gear using 8 nodes isoparametric elements is introduced.

本文解决了边界元法在空间啮合副计算中存在的系数矩阵的存储，奇异单元积分的计算、表面不连续点处面力一点多值和求解未知量的线性方程组矩阵元素的计算等问题，编制了比不采用上述处理方法的一般边界单元法节省近一半内存和计算时间的适合空间啮合副的三维边界元法计算程序。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。