数值方法

Some concepts about the reliability are described, and the method for calculating the reliability of system is provided by making linear substitution. While taking Stochastic Finite Element Method into the reliability calculation, a Nonlinear SFEM model is founded, and methods to resolve some problems in SFEM calculation are given. So as to the calculation of the force boundary, a method in FEM is provided for sabot pressure calculation, base of this, the numerical calculation model is carried out.

给出了弹丸发射强度可靠性计算中的一些理论和概念；给出了串联系统可靠性的逐步线性等效计算方法；将随机有限元方法引入可靠性计算中，建立了弹丸发射时的非线性随机有限元计算模型，并给出了计算中的一些问题的处理方法；在随机有限元的载荷边界的计算中，提出了弹带压力的有限元计算方法和在有限元求解思想上的数值计算模型。

Except the same characteristic as the conventional boundary element method, this method avoids the nearly singular integral , so it is one of effect numerical calculation methods.

该方法继承了传统边界方法的优点，而避免了传统边界元方法遇到的边界积分奇异性问题，是该问题一个十分有效的数值求解方法。

In this paper, a new numerical method, the coupling method of spherical harmonic function spectral and streamline diffusion finite element method for unsteady Boltzmann equation in the neutron logging field is discussed, and the convegrence and error estimations of this scheme are proved.

针对中子测井问题，研究非定常Boltamann中子输运方程的确定型数值求解方法，给出了求解Boltzmann方程的球谐函数展开和流线扩散有限元耦合方法，证明了这种耦合方法的收敛性和误差估计·实际算例表明此方法是有效

This thesis investigates the profile extraction and shape optimization on the result of topology optimization of planar compliant mechanisms. The main context includes the following work:(1) summarizing and analyzing the recent research status, some harvest and unsolved problems;(2) analyzing the conceptual design of planar path-generating compliant mechanisms and its mathematical model and tools;(3) Modifying the method of density contour as the method of profile extraction, and developing a method to optimize the density function in the profile extraction according to the requirement of the design of compliant mechanism;(4) developing a method to abstract the compliant mechanism into a form of links and joints by using the principle of connectivity on topology;(5) developing a method of shape optimization of planar path-generating compliant mechanisms, by representing the profile of the abstracted compliant mechanism as simple curves such as straight lines and arcs, establishing the models of the size optimization of the parameters of these curves, so that the compliant mechanism has a machinable shape;(6) At last, proving the feasibleness and effectiveness of the design method by making simulation design and validating it in FEA software.

主要工作包括：(1)分析了柔顺机构拓扑优化和形状优化的研究现状，分析了目前柔顺机构的研究重点、主要成果和尚未解决的问题；(2)分析了基于SIMP的柔顺机构概念设计方法及其相关工具和模型；(3)针对柔顺机构轮廓提取的特殊要求，提出了密度等值线法的改进方案，对密度函数插值点密度值进行优化，提出优化模型和选择优化算法；(4)根据轨迹输出平面全柔顺机构自身的形状特点，提出了轨迹输出平面全柔顺机构的抽象方法，即应用拓扑学上的连通性原理将柔顺机构抽象成杆件和结点形式，并对相应的数学原理进行了证明；(5)提出了平面全柔顺机构的形状还原和尺寸优化方法，对抽象的柔顺机构进行还原，将其轮廓还原成简单曲线的连接，从而建立尺寸优化模型，对机构进行尺寸优化设计，在得到可加工的机构轮廓的同时又能对关键部位进行特别处理；(6)进行了柔顺机构的数值仿真设计，并将所得设计结果导入商用有限元软件中进行仿真实验，证明了设计方法的可行性和有效性。

Z2Bn z$e0A0 Meshless method is a new numerical computation method that is developed rapidly in recent years. Without element mesh and based on the dispersed nodes to form approximate interpolative function dynamically, meshless method has distinct difference with traditional finite element method. Meshless method conquers the problems caused by mesh generation, mesh aberration and mesh move. With provides a new effective means to engineering problem, meshless method obtain highly recognition in international compute mechanics domain and engineering field.

6L！y6K1Q6h0k0 无网格方法是近年来迅速发展起来的一类新型数值计算方法，它们不借助单元网格而是基于离散结点动态构造近似插值函数，与传统的有限元方法有着显著的区别，克服了网格生成、网格畸变和网格移动引起的问题并为工程问题提供了一种新的有效分析方法，受到了国际计算力学界和工程界的高度重视。

Chapter 8: We discuss the acceleration of multigrid by Krylov subspace approaches, and recognize the reason for slow convergence of algebraic multigrid methods is that error reduction is significantly less efficient for some very specific error components which may cause a few eigenvalues of the algebraic multigrid iteration matrix to be considerably closer to 1 than all the rest. However, the eigenvectors belonging to the few isolated eigenvalues can be expected to be typically captured after only a few conjugate gradient iterations, which accelerate algebraic multigrid algorithms. Theoretical analysis and numerical results of some practical problems show the iterant recombination accelerates algebraic multigrid convergence.

第八章：先介绍用Krylov子空间迭代法加速一般多重网格方法收敛的基本框架，然后紧紧抓住引起代数多重网格方法收敛减慢的根本原因往往是误差减小对几个特别的误差分量不明显，这导致代数多重网格方法的迭代矩阵的几个特征值接近于1，而共轭梯度方法则能比较典型地捕捉属于孤立特征值的特征向量，从而推导出有效的共轭梯度加速算法和程序实现，不仅从一些具体的实际应用例子的数值结果去验证迭代复合加速收敛的效果，而且还从理论上分析了预处理共轭梯度法加速代数多重网格法收敛的机理。

Based on Born approximationmethod and the local principles of wave function in inhomogeneous medium and theray theory and the integral equation theory,this dissertation researches the theory andsimulation of the inversion method of large perturbational medium parameters andbreaks through the approximation condition of the small perturbational parametersand the weak scattering in traditional inversion method.

本文在Born近似方法的基础之上，基于非均匀介质中波函数局部理论和射线理论及积分方程等理论方法，对大扰动参数反演方法的理论和数值模拟进行了研究，突破了传统反演方法要求的参数小扰动和弱散射条件。

Fortunately, the modern geodetic measurements such as the Global Positioning System technique can overcome the shortage of the geological and seismographic methods in the time dimension; and yet, the coverage of the geodetic survey stations is not sufficient. As a result, it is necessary to employ numerical simulation to investigate the continuous deformation of the crust.

而以全球定位系统等技术为主的大地测量方法弥补了地质和地震学方法在时间维上的不足，但大地测量方法存在测点覆盖不足及测点地理分布不均匀的缺点，因此，要得到连续的地壳形变场有必要借助数值模拟方法。

The wavelet time-frequency properties of the uncracked rotor and the cracked rotor were discussed by the continuous wavelet time-frequency analysis algorithm. A new algorithm using the wavelet time-frequency analysis algorithm to detect the crack was proposed. The influence of the sampling frequency on the wavelet time-frequency analysis algorithm was analyzed through the numerical simulation research; the valid sampling frequency was presented.

利用连续小波时频分析方法，讨论了裂纹转子与无裂纹转子的小波时频特性，提出了利用小波时频分析方法识别裂纹的新方法；数值仿真研究了采样频率对小波时频分析方法的准确性和有效性的影响，并给出了建议性的采样频率。

With B-spline basis set, a new method for double-electron atomic systems in uniform intermediated magnetic fields is given.

运用B样条方法，我们发展了一套适合处理中等强度磁场下的双电子原子体系的新方法，在这一方法中，所有的矩阵元计算都只包括解析积分和一维数值积分，使得计算变得简单，所得到的结果比普遍的球坐标和柱坐标中的展开方法所得的结果要好。

They weren't aggressive, but I yelled and threw a rock in their direction to get them off the trail and away from me, just in case.

他们没有侵略性，但我大喊，并在他们的方向扔石头让他们过的线索，远离我，以防万一。

In slot 2 in your bag put wrapping paper, quantity does not matter in this case.

在你的书包里槽2把包装纸、数量无关紧要。