近似计算

It enlarges the range of quasi-linear Born approximation, and makes the prestack depth migration method based on quasi-linear Born approximation to be able to adapt strong lateral velocity variation.

在散射波场计算中，使用了一个更稳定的散射波场计算公式，扩大了拟线性Born近似的应用范围，使基于拟线性Born近似的叠前深度偏移方法能够适应更强的横向速度变化。

In order to validate the correctness, the absolute differential cross sections of e-Ar scattering with multi-photon exchange in some special scattering geometries are calculated with Yukawa potential by applying the Second-order Born approximation and low-frequency approximation theory, respectively.

为了验证该计算方法的有效性，在入射电子的动量平行于激光场的极化方向这种特殊的散射模式下，利用Yukawa势，分别应用二阶玻恩近似方法和低频近似理论方法对激光场中电子—氩原子交换不同光子数的散射截面都进行了计算。

We use the Taylor series expansion method to get the second-order approximate expression of the confidence region of the parameters, and then according to the principle of minimizing the volume of the confidence region, this paper carries out experimental design for the regression model, and then fixes the point range in the domain of definition of design variable for the model function so as to select the designing point, which can minimize the volume of the confidence region.

文章首先计算指数族非线性模型的回归参数β在1-α置信水平下的置信域的体积，为了便于计算，需把置信域投影到切空间中去，投影后的置信域是一个椭球体，用Taylor展开方法对此椭球体的体积进行二阶近似，推出原参数置信域的体积的近似表达式，然后对回归模型进行试验设计，根据置信域体积最小准则，在模型函数的设计变量的定义域上确定点列，选取使置信域体积达到最小的设计点。

In order to solve the problem,starting from the analysis of the simplest plane wave numerical theory,we derived the formula of relative phase velocity and group velocity under the condition of arbitrary high-order finite-difference approximation,and gave the computational method for acquiring the optimum Courant number,and then analyzed the anisotropic effects due to finite difference approximation.

针对此，从最简单的平面波数值理论分析出发，推导了任意高阶有限差分近似条件下相对相速度和相对群速度的计算公式，给出了求解最佳Courant数的计算方法，分析了差分近似造成的各向异性效应。

If average values before or after catastrophe point when the pressure at both ends reduces exceed the threshold value, judging that there is leak and positioning: calculating approximate wavelet transformation coefficient of pressure data at both ends, initializing searching interval, calculating a signal time delay value corresponding to approximate wavelet transformation coefficient in the searching interval from maximal scale N; converting the time delay value under scale N to that under N-1 by geometric proportion relation; updating the searching interval, repeating above processes until the scale is 0 and positioning based on the time delay value.

若两端压力下降突变点前后的均值变化均超过阈值，判定有泄漏并进行定位：计算两端压力数据的近似小波变换系数，初始化搜索区间，从最大尺度N开始在搜索区间内计算对应近似小波变换系数的信号时延值，利用等比关系将尺度N下的时延估计值转换为N-1下时延估计值，以该值更新搜索区间，重复以上过程至尺度为0，以此时延估计值进行定位。

Algorithm for determining the lower limit of the iterated times in IFSP;2. Stratigraphical division and lower limit of the Quaternary in Hunan;3. At present, the approximate solution of Voigt and Reuss's upper limit or lower limit and the calculating formula of Hashin and Shtrikman's upper limit or lower limit are accurate.

计算复合材料有效弹性模量上、下限的方法中，Voigt和Reuss的上、下限近似解及Hashin和Shtrikman的上、下限计算公式较为精确，但Voigt-Reuss近似解通常忽略了各向异性非均匀体的研究，是一个不全面的结果。

At first, an approximated mathematical model is presented. Then, the system manager can compute the optimal control policy via the method of successive approximation. Based on the above-mentioned algorithm, we design an intelligent system with feedback control to regulate the allocation of limited channels of trunk circuit. This system will continuously detect the status of whole cellular network. Once the system parameters cross the predefined threshold, the recomputing mechanism will be activated.

首先针对系统的近似数学模型先將其定义出来，然后就可以用连续逼近法將最佳控管决策计算出来，这样的最佳决策演算法我们把它设计在一个有迴授机制的智慧型决策系统裹，此决策系统將不断地侦测行动通讯网路运作的情形，一旦网路参数变化超过某个预定的临界值时，整个最佳决策演算法將被启动，系统的近似数学模型將依新的参数重新定义，接下来同样地写出最佳方程式並用连续逼近法计算出新的最佳控管决策。

This method corrected the Wien approximate based on the mathematical principle, and calculated the spectral shape using ADE to identify the band which had the maximum and minimum emissivity, then deduced the relationship of each band's emissivity after the correction of Wien approximate and derived the actual emissivity using this relationship and MMD model.

对维恩近似从基本原理上进行修正，利用ADE计算光谱大致形状以确定发射率最大最小的波段，推导出了在修正维恩近似后各个波段发射率的关系，再利用这个关系以及最大最小值差模型计算实际的发射率。

In this paper, Newton iteration formula for computing normal depth and critical depth was put forward by mathematical transformation of uniform flow equation and critical flow equation of circular section tunnel. Then, the relationship between the corresponding central angle and the introduced parameters was analyzed. An approximate formula for angle was obtained according to optimal uniform approximation principle. Using this approximate formula as initial value of iteration formula, a direct formula for calculating normal depth and critical depth of circular section tunnel was established after its first iterative.

该文通过对圆形断面均匀流方程与临界流方程的数学变换，分别得到其正常水深与临界水深的牛顿迭代公式，同时，通过对正常水深与临界水深对应的中心角与引入参数之间关系的分析及数值计算，利用最优一致逼近原理分别得到了正常水深与临界水深对应中心角的近似计算式，并以此近似计算式为初值，用迭代方程进行一次迭代得到了圆形断面均匀流水深与临界流水深的直接计算公式。

Paraxial approximation absorption boundary condition based on acoustic wave equation can obtain better absorption results by increasing paraxial approximation order of Taylor series. However, this kind of operation will increase the complexity of difference computation, and result in instability of computation process.

基于声波波动方程的旁轴近似吸收边界条件可以通过提高泰勒级数展开的旁轴近似阶数获得更好的吸收效果，但这样不仅增加了差分计算的复杂性，同时还导致计算过程不稳定。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。