查询词典 boundary element method

In image processing, method as follows will be introduced in this paper: a method combining image threshold iterative segmentation with threshold interpolation, edge detection operator Sobel and LoG, edge linking method using delation operator based on mathematical morphology, using boundary tracking and projection method in edge distill process. Through this method, measurement of wheelset will be met precision demand.

本文阐明了图像的分通道自动采集过程，以及对采集到的原始图像进行预处理过程，达到图像去噪声的目标，本课题采用了阈值分割中迭代阈值和阈值插值相结合的方法，Sobel算子、LoG算子边缘检测算法，基于数学形态学的膨胀运算子进行边缘断点连接以及目标提取中的投影法和边缘跟踪方法，使得提取轮对图像边缘达到测量精度的要求。

Next the discussion in this study, about an ellipse with an angle of attack and two circular cylinders with different diameters in the flow, the aim of this study is investigated for the ability of the present numerical method by solving the suppression of the vortex shedding flow behind the two-cylinder system which was kind of difficult to reach by a Cartesian grid method. In this study, the suppression of the vortex shedding flow is tested to solve a uniform flow past through two different diameter cylindrical in the flow field with Fractional Step Method and Immersed Boundary Method.The numerical method which we investigated is showed that the results of the problem is appropriable in other literatures.

接著探讨流过具攻角之椭圆柱体流场及流过圆柱抑制涡漩逸出之流场，目的是要研究利用控制圆柱来抑制下游涡流的流场行为，本文采用分步法配合内嵌边界法数值解析一均匀流流经两不同直径的圆柱流场，来测试抑制涡流逸出的问题，根据现有的数值结果发现试验运用了合适的方法且得到令人满意的结果。

In this paper the defect of the traditionary boundary layer methods (including the method of matched asymptotic expansions and the method of Visik-Lyusternik) is noted, from those methods we cannot construct the asymptotic expansion of boundary layer term really.

本文指出传统的边界层方法包括匹配法和Vi(？ik—Lyusternik方法的不足：不能作出边界层项的渐近展开式。提出多重尺度构造边界层项的方法，得到符合实情的结果。

In this paper we study the method of interpolation by radial basis functions in H~k(k ≥ 1) and give some error estimates. By means of such interpolation with a special kind of radial basis function, we construct a basis in H~k(k ≥ 1). Combined with the Galerkin method, this theory can be applied to solve boundary value problems for elliptic partial differential equations (such as the third boundary value problem for Poisson equation and the corresponding problem for the biharmonic equation), and some numerical experiments are also given.

本文从求解偏微分方程的角度出发，在被逼近函数u属于一般的Sobolev空间H~k(k≥1)的情形，引入了一种径向基函数插值方法，并建立了相应的误差估计；再利用这种插值性质，从一类特殊径向基函数出发构造Sobolev空间的一组基，针对Poisson方程第三类边值问题和重调和方程类似边值问题，为用无网格算法求解偏微分方程边值问题建立了相应的理论，并通过算例来验证了这一算法。

Based on the analysis of the characteristics of the compensation directions for boundary curves in rapid prototyping direct slicing, a new method, which can determinate the compensation direction by converting the boundary curve to beeline polygon, is proposed. The geometric signification of the polygonal method is demonstrated.

在分析快速成型制造中直接切片真实边界曲线补偿方向特点的基础上，提出了一种将曲线边界转化为直线多边形进行补偿方向判定的方法，幷阐述了该判定方法的几何意义。

The method uses Cartesian grid for the majority of flow field with special treatment to cells cut by the solid boundary, thus not only retains the advantage of Cartesian grid's high solving speed, but also ensures the high precision near the boundary, which avoids the distortion coming from scalariform mesh with traditional difference method.

该方法在流场主要区域采用笛卡尔网格，而对与固体边界相交处的单元采用特殊的处理。这样既保留了笛卡尔网格求解速度快的优点，同时在边界处又保证了精度，避免了传统差分法处理该类问题需采用阶梯形网格逼近而导致的失真问题。

The primary objective of this thesis is to use multigrid method for solving nonseparable elliptic equations with Dirichlet boundary condition on a rectangle. Of course, this method can be applied with any boundary conditions.

这篇论文主要之目的是使用多重网格法来解一些不可分离的椭圆方程式有著Dirichlet条件在矩形的区域上(当然这种方法也可应用在其他的边界条件下)。

Compared with the same wave problems with conventional Dirichlet boundary conditions, the absorbing boundary conditions can reduce the numerical reflection on boundaries and avoid solution distortion. In addition, the central differences method is economic in memory requirement and computing time compared with implicit integral method.

结果表明：该解法在空间上具有谱精度，在时间上达到二阶精度；与第一类边界条件相比，吸收边界有效地削弱了边界上的数值反射，避免了解的失真；使用中心差分的时间积分方法同隐式积分方法相比，适合波的传播特性，避免了矩阵求逆运算，并且占用的计算机内存小。

The method involves an iterative procedure, which incrementally flattens a 3D triangular mesh by region growing and obtains a parameterization with free boundary. The result is then converted to a parameterization with regular boundary by conformal mapping. Our method accounts for both the angle and area distortion during parameterization, it yields a parameterization with less global distortion and no triangular flipping.

采用区域增长算法逐层展平空间三角网格，得到空间三角网格曲面的自由边界的参数化结果，并利用保形变换将自由边界的参数化结果变换为规则边界的参数化结果；同时兼顾了参数化的角度变形和面积变形，使得参数化结果具有整体变形较小的特点，并能够避免三角形折叠的现象。

Firstly, the equation for stress intensity factors under static uniform pressure is used as the reference case, and then the weight function for a thick-walled cylinder containing a radial edge crack can be worked out. Secondly, the dynamic stresses in uncracked thick-walled cylinders are solved under internal impulsive pressure by using mode shape function method. The solution consists of a quasi-static solution satisfying inhomogeneous boundary conditions and a dynamic solution satisfying homogeneous boundary conditions, and the history and distribution of dynamic stresses in thick-walled cylinders are derived in terms of Fourier–Bessel series. Finally, the dynamic stress intensity factor equations for thick-walled cylinder containing a radial edge crack subjected to internal impulsive pressure are given by dynamic weight function method.

首先采用静态内压下的应力强度因子作为参考解，得到了带径向边裂纹厚壁圆筒的权函数；然后用振型函数方法推导无裂纹厚壁圆筒在冲击内压下的动应力响应，分析中将相应的弹性动力学方程解分为满足非齐次边界条件的准静态解和满足齐次边界条件的动态解的叠加，利用傅立叶-贝塞尔级数展开，推导出了厚壁圆筒内动应力的响应历程和分布规律；最后由动应力权函数方法导出带径向边裂纹厚壁筒在冲击内压下的动态应力强度因子计算公式。

I hope that this success is just the first in a long series.

我希望这只是成功的开始。

Three dimensional stresses on the interface of tire and soil, tire deflection and soil sinkage are measured.

测试轮胎——沙土界面上的三向应力、轮胎变形和沙土沉陷；建立考虑剪切应力对沙土承载特性产生影响的车轮牵引性能预测模型；分析车轮作用下土壤的纵向稳定性。