查询词典 BEM

Aimed at spherical, cylindrical, conical and toroidal electrodes in electrical engineering, based on the corresponding coordinate transformation the randomly meshing surface BEM is put forward.

针对电气工程中常见的球、柱、锥和圆环形电极，建立相应的坐标系，提出了基于坐标变换，适用于任意网格剖分的曲面边界元方法。

The multitooth contact problem of the crown gear coupling is analysed by using 3 D BEM. Actual measurements on a specially designed test bed are made.

本文首先应用三维弹性边界元方法对一鼓形齿联轴器的多齿接触问题进行了数值计算分析，然后在专用试验台架上作了相关实测研究。

Crown gear coupling ; mesh ; contact teeth number ; BEM ; measurement

鼓形齿联轴器；啮合；接触齿对；边界元；测试

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。

The physical meanings of BEM are extended by the FBEM and FPFM. On the basis of solving plane problems sueessfully with FBEM and FPFM, the article recommends the fictitious boundary element method and fictitious point force method to solve three dimensions problem in solid mechanics.

本文对边界单元法进行了改进，提出了使用方便、灵活、物理意义清晰的虚边界单元法和点载荷法，较好地解决了局部数值解精度不高的问题，并将所提出的方法推广应用到求解三维问题，减少了问题的复杂性。

The mathematical programming formulation and related solution procedure are established by the traditional BEM. Through the discretization of space and time, the elastoplastic stress simulation method and reduce-basis technique are adopted to construct the self-equilibrium stress field. The numbers of variables and constraint equations in the resulting mathematical programming formulation are reduced greatly and then the dimension obstacle of computation in 3-D limit and shakedown analysis is overcome.

采用常规边界元方法建立了三维结构极限与安定分析的数学规划格式，通过对时间和空间的离散化，并采用弹塑性模拟法构造自平衡应力场和引入减缩基技术，大大减少了所形成的数学规划格式中的未知变量和约束方程的数目，有效地克服了三维结构极限与安定分析中的维数障碍问题。

Differing from the general BEM that is attributed from the general boundary integral equation, The natural boundary element method attributed from the natural BIE has not only the advantage of the dimensionality, but is confirmed and gain the only NBIE from the original problem.

无网格方法仅仅需要节点信息，克服了有限元等传统数值方法对网格有较强依赖性的缺点，摆脱了网格的束缚，避免了大量的网格分划、复杂的网格生成及重新划分的工作，减少了因网格畸变而引起的困难，而且收敛快、精度高、易于实现和进行后处理工作。

According to the studied results at present, the studied objects are mainly thin plate and beam about sound radiation mode, a method computed sound radiation mode of complex structure is presented in this dissertation, according to the results of the previous two chapter, a theoretical method to solve acoustical radiation mode and acoustical radiation efficiency of complex structure by boundary element method and acoustical radiation theory is posed, the acoustical radiation power is expressed as a Hermitian quadratic form, while the radiation modes is determined by general eigenvalue decomposing, and then the radiation efficiency is computed via the orthodoxy of radiation modes with regard to impedance matrix and average velocity matrix; lastly, the validity of the method is proved by pulsating sphere and radiating cube with analytical results. According to results of the form three chapter, the structure sound radiation sensitivity is studied in detail, the sound radiation power of structure can be expressed as positive Hermitian quadratic form, the sound radiation sensitivity can be expressed as two parts by partial differential with respect to design variable, which are sensitivity of boundary velocity and impedance matrix, combined with the theory of FEM and BEM, the structure sound radiation can be translated to the analysis of structure dynamic sensitivity and impedance matrix sensitivity. The theory posted in this dissertation is tested by the FEM software ANSYS and the software AAS programmed by author.

在前几章的基础上，通过结构声辐射的模态理论对结构的声辐射的机理进行了深入地探讨，针对目前声辐射模态的研究对象主要是简单的板和梁类结构，提出了一种计算复杂结构声辐射模态的方法，利用前两章研究所得的结论，将边界元方法与广义特征值的理论结合起来研究了复杂结构的声辐射模态与声辐射效率，先将结构的声辐射功率表示为一个正定的厄米特二(来源：ABb7C论文0909网www.abclunwen.com)次型，运用广义特征值分解求解了复杂结构的声辐射模态，然后利用声辐射模态关于阻抗矩阵与均方速度耦合矩阵的正交性，求解了复杂结构的声辐射效率，最后用具有解析解的脉动球与辐射立方体验证了该方法的有效性。

To provide theory foundation for inverted deduction work, numerical simulation for propagating in highway-surface with exceptional block and inanition and crack has been performed. The numerical simulation results show that the BEM is an effective method for the elastic-waves propagating in highway-surface concrete medium.

利用边界元法能够很好的描述弹性波在砼介质中传播的特性，正演模拟异常石块、脱空和裂缝对波的传播的影响，为进一步的反演工作提供理论依据。

Considering the effect of load and helical angle on the instaneous width of contact area, this paper uses the BEM program for calculating the deformations at different place along the width of convex tooth and concave tooth of W-N gear and gets the relevant deformation curves.

并首次应用三维边界元方法，在计入齿面瞬时接触迹宽度随外载、螺旋角而变化的条件下，计算了双圆弧齿轮凸齿面端部和凹齿面端部的变形。

In the days of sailing vessels the crew were afraid they would be becalmed on the ocean.

在使用帆船的时代，船员们担心他们会因为无风而无法在海洋上航行。

As long as foreign donors pay the PA's salary bill, few expect a new intifada.

只要外国继续为巴权力机构的薪水买单，希望发动新暴动的人便寥寥无几。