近似法

In this paper, on the base of paraxial approximations, we present a set of absorbing boundary conditions of 3D elastic wave equations and apply to the 3D elastic wave numerical modeling in isotropic medium.

本文基於傍轴近似法提出了计算三维弹性波方程的吸收边界条件公式，表示了各边界面、边棱和角点处波场所满足的单程波方程，并在三维弹性波数值模拟中进行了应用。

We divide it into four sub-problems, and use boundary approximation method to solve each sub-problem.

我们将其分成四个子问题，使用边界近似法解每一个子问题。

This type of approximation is made at a finite number of points.

这种近似法是在有限数目的节点处来进行的。

In chapter 3, the linear approximate method of Bessel function for measuring nanometer vibration is studied. The error of linear approximate is analyzed and the theoretical measurement range of this method is given.

在此基础上，首次提出了一种双光路DSPI振动测量系统，利用退敏感光路使贝塞尔函数线性近似法的测量范围扩大了24倍，由近50nm增至1150nm。

Chapter 2 studied Monte Carlo methods for solving three special classes of the stochas-tic smooth convex programming.

第2章研究了三种随机光滑凸规划问题的Monte Carlo近似法。

In this paper, the stray light and ghost image caused by multi-reflection in high power infrared optical systems are analyzed and discussed, and the comprehensive method incorporating paraxial approximation and real ray trace is presented; the data structure of binary tree is used in the storage of interdata so that the storage problem of huge-size data is resolved.

本文主要研究了大功率红外光学系统中光学表面多重反射而形成的杂散光及其数学模型与计算方法，提出了将近轴近似法和有限光线追迹法相结合的综合分析方法；同时在数据存储方式上采用二叉树这种数据结构，巧妙地解决了鬼像分析中海量的中间数据存储的问题。

There are two kinds of method in common use. One is numerical method, and the another one is analytic approximation which is represented by perturbation method.

常见的方法有两种：一种是数值方法，二是以摄动法为代表的解析近似法。

Based on the theorems of holography and linear system,the numerical reconstructing methods of the off-axis lensless Fourier transform hologram by Fresnel diffraction formula and by the convolution method based on Rayleigh-Sommerfeld diffraction integral and by angular spectrum theorem are studied.

根据全息理论和线性系统理论，采用离轴无透镜傅里叶变换全息记录光路，对利用菲涅耳近似法、基于瑞利—索末菲衍射积分的卷积法以及角谱理论方法数值重建全息图进行了比较研究，并做了计算机模拟验证。

Then 4 approaches are used for solving semiconductor thermoelectric problems are proponed:(1) solve basic semiconductor equations directly,(2) solve heat transfer equation with the fitting expressions of thermoelectric transport,(3) approximation of relaxation interval time,(4) characteristic temperature of thermoelectric-pile method.

随后，提出了求解半导体热电问题的4种方法：①直接求解半导体方程组②驰豫时间近似法③利用温差电输运系数的拟合式来求解导热方程④热电堆特征温度法。

Calculation of integrated emissivities of diffuse cavities with lids "The integrated emissivities of diffuse cavities with lids have not been able to be calculated precisely up to now."

作者提出的&矩形区域近似法&与Bedford法计算精度相同，但避开了奇点处理问题，使问题得到充分简化。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。