差分法

In particular, the time-domain electric integral equation of second-order time differential coefficient is calculated by an explicit MOT solution.

本文利用时域矩量法及其与时域有限差分方法的混合法分析计算目标电磁辐射与散射问题。

Fourth precision solution can be derived from two grid sets solution with a second precision central difference scheme by Richardson extrapolation. It reduces the amount of calculation. Uncertainty is determined from the discretization error analysis. A finer grid calculation is made to validate the extrapolation scheme.

对于2阶精度中心差分格式的2套网格数值解，用Richardson外推法可以得到4阶精度的解，其工作量比直接求解4阶离散方程的工作量减少许多；对于计算中的数值不确定度，用该方法分析了离散误差，并用逐次加密网格的方法探讨了外推法的合理性。

The time-marching method and explicit finite volume difference scheme are employed to solve the flow inside the turbo-machinery.

教授的粘性体积力法来模拟粘性对叶轮机械内部流动的影响，采用时间推进法和有限体积差分格式对叶轮机械内部的流动进行求解。

The application of reflected optical difference system in surface crack of aluminum detection is also discussed. By analyzing the experimental data, we found that the reflected pulsed wave techniques could be used to measure the position of crack precisely and depth imprecisely. Transmitted wave contain much size information of the crack, despite without position information. The spectrum of transmitted is sensitive to the depth of crack. The deeper the crack is, the narrower the spectrum bandwidth is.

使用自建的光偏转差分检测系统，对铝样品中多种表面缺陷进行了检测，对表面波直达波，反射波，透射波波形及频谱进行了分析，讨论超声表面波与各种缺陷相互作用后的变化，通过对实验结果的分析，发现缺陷脉冲发射法可以精确测定缺陷位置，粗略估计缺陷深度；而透射法测的波形无法定出缺陷位置，但包含了缺陷大小信息，透射波频谱对缺陷深度非常敏感，随缺陷深度的加深，频谱不断的左移。

In this paper, we study the initial value problem of Duffing equation in the difference form with multiple-scale method, which is one of the perturbation method.

本文以摄动法中的多重尺度法为基础，讨论差分形式的Duffing方程的初值问题。

The differential equation methods, integral equation method used for analysis of scattering are reviewed in this thesis.

本文先回顾了用于散射分析的差分方程法和积分方程法等。

This thesis is divided into six parts. The first chapter is preface, the current status of research in the inverse problems for parabolic partial differential equations is reported; the second chapter is "regularization methods for numerical differentiation and their applications ", in this chapter we investigate many regularization methods from a viewpoint of regularization theory and algorithm, some applications in the inverse problems for parabolic partial differential equations are given; the third chapter is "spectral regularization methods". Based on Fourier analysis, within the framework of regularization theory, we apply the spectral methods to some ill-posed problems. Many numerical experiments are done in order to show the validity of the methods; the fourth chapter is devoted to wavelet dual least squares method and a revised wavelet method; in the fifth chapter,we combine finite difference method with method of lines and apply it to the backward heat conduction problem in time; in the sixth chapter "identification problems for unknown source ", the essence and the degree of two problems related to source identification are pointed out, at the same time, some numerical methods are reported.

本文分为六个部分，第一章前言简要分析了国内外抛物型偏微分方程反问题的研究现状；第二章数值微分的正则化及其应用从正则化理论和算法的角度出发，考察了许多正则化方法，还给出了数值微分在抛物型偏微分方程反问题的一些应用；第三章谱正则化方法是在Fourier分析的基础上，在一般正则化理论的框架下，给出了这种方法在各种不适定问题中的应用，数值实验表明谱方法是有效的；第四章研究了小波对偶最小二乘方法和改进的小波方法；第五章主要研究了有限差分方法结合线方法在时间反向热传导问题中的应用；第六章是未知源识别问题，主要指出了两类未知源问题的不适定程度和不适定本质，同时报告了一些数值方法。

The methods used here are proved be correct therefore are useful for the numerical simulation in unsteady incompressible flow with dual time step and preconditioning . Simulation to the sand saltation is carried.

文中所采用的双时间法的数值求解方法、边界条件的提法、差分格式的选取经验证是成功的，为双时间法与预处理方法的结合对低马赫数流动的数值计算积累了宝贵的经验。

One combines the initial value computing method of system of ordinary differential equations (Runge-Kutta Method) with optimization method, another co...

1是将常微分方程组初值的龙格-库塔法与最优化计算方法相结合；2是将常微分方程组边值差分解法与最优化计算方法及 3点插值法相结合。

The mechanism of linear regression analysis, decomposing of Shukla interactive variance method, and AMMI model were introduced as crop varieties stability analysis methods in crop regional trials.

介绍和比较了直线回归法、Shukla互作方差分解法和AMMI模型法在作物区域试验中分析品种稳定性的原理和方法，并以长江流域棉花品种区域试验的产量数据为实例，研究了3种方法对品种稳定性分析的效果。

Singer Leona Lewis and former Led Zeppelin guitarist Jimmy Page emerged as the bus transformed into a grass-covered carnival float, and the pair combined for a rendition of "Whole Lotta Love".

歌手leona刘易斯和前率领的飞艇的吉他手吉米页出现巴士转化为基层所涵盖的嘉年华花车，和一双合并为一移交&整个lotta爱&。

This is Kate, and that's Erin.

这是凯特，那个是爱朗。