近似计算

Integral of one variable functions, improper integral and its convergence properties.

本课程的主要内容包括：1 各种极限运算，其中包括数列极限、函数极限以及上、下极限；2 一元函数的微分学，包括微分和导数的运算法则、微分中值定理及其应用等；3 一元函数的积分和广义积分及其收敛性；4 级数及其收敛性，包括数值级数的收敛性和函数项级数的各种运算和性质；5 多元函数的微分学及其应用，其中很多方面与一元函数的微分学近似，需要注意它们之间的区别；6 多元函数的积分学，包括多重积分的性质与计算，多重积分的的应用等；7 曲线、曲面积分及其应用；8 含参变量积分的计算与性质；9 Fourier 级数及其应用，等等。

An approximate equivalent model for the calculation of coil inductance of eddy-current sensor has been suggested and so a satisfactory formula deri- ved forpractical evaluation.

本文为计算电涡流传感器线圈的自感而提出了近似的等效模型并得出了较为理想的计算公式。

The computing plots of the solutions from the two methods were inconsistent under the specified boundary-initial conditions, which stirred up the debate of the effectiveness of Maxwell's equations in lossy medium. It is found that the differences between the two numerical curves can be viewed as the Gibbs phenomenon caused by cutting off the high frequency components in computing the infinite integral of the numerical curve of Harmuth's solution.

通过比较两种解析解的数值曲线得出：两者的差异在于求解Harmuth解的数值曲线时，采取无穷积分的高频截断近似产生了吉布斯现象；在计算Harmuth解的数值曲线时不断增大积分上限，其数值曲线的振荡不断向不连续点处收缩，而且衰减加快，因此在求解Harmuth解的数值曲线时，若积分区间取为理想无限大，则可以预见相同计算精度下两种方法的电场解的数值曲线是一致的。

So, the approximate calculating formula of parabola and the length of ellipse arc is developed by the method of finding experience formula from point of view of simplifying the calculating process and getting certain accura...

本文从既能简化计算又能达到一定精度的设想，通过找经验公式的方法给出了计算机抛物线及椭圆弧长的近似公式，并给出了常用区间上计算抛物线和椭圆弧长的一次式和二次式。

Starting from the steady-state performance of three-phase fully-controlled rectified circuit, which is with large inductive load, we take the front two items of the Maclaurin series of the DC voltage average as approximate formula, with considering of the effect of the AC-side inductance first, and further effect of AC resistance on DC voltage and commutation angle.

本文从带有高感性直流负载的三相全控整流电路稳态工作的物理情况出发，首先考虑了交流侧电感的影响，进而考虑交流侧电阻对直流电压、换相角的影响，将直流电压的平均值用麦克劳林级数表示，取前两项作近似，得出了实用的解析计算公式，并给出了计算步骤，实验证明该结果具有较高的精度。

Algebraic formulas for calculation of modal field with given approximate value of propagation constant are also presented .

导出了用微扰法计算渐变折射率平面波导传播常数各级近似值的代数递推公式，并给出了由传播常数近似值计算模场近似表达式的代数公式。

Then based on the results, the characteristics of radar stealth of a naval vessel were analyzed.

建立以某舰船为参照的艏向与正横向的近似二维模型，基于二维时域有限差分法计算舰船的艏向与正横向在不同频率入射波情况下的雷达散射截面，并根据计算结果对某舰船的雷达隐身特性进行分析。

All backscattering field s intensity from conducting plate can be calculated by complex ray method ,especially complex ray paraxial approximation in angle domain through modeling the conducting plate.

本文通过建立导电平板反射场分析模型，利用复射线方法特别是角域中的复射线近轴近似方法，有效地实现了导电平板在整个后向范围内散射场的计算，同时计算精度可以由复射线展开参数ξ来加以控制。

Therefore,it is necessary to research diffusion equation for suspended sediment because it describes the sediment move process in the water body.The equation is a various coefficients second-order linear partial differential equa-tion,such equation under complex boundary condition is very difficult to get its analytical solution,while its numerical solution relative analytical solution is more easier and has the obvious superiority:simple,the computation convenience.but to get a kind of difference format which is good accuracy and stability is not easy.

泥沙扩散方程实际上是一个变系数的二阶线性偏微分方程，这样的方程在各种复杂边界条件下求解是十分困难的，求它的解析解在数学上存在着难以克服的障碍，无法求出其精确解，因此常用数值方法求它的近似解，相比较而言，数值方法有着明显的优势：即简单灵活、计算方便快捷，但要寻找一种精度高、稳定性好、计算方便的差分格式也并非易事。

In the numerical calculation of the tunneling transmission probability we adopt the multistep approximation to approximate the whole potential barrier.

在电子穿隧机率的数值计算上，使用多阶近似的方式成就整个位能障的穿隧机率之计算。

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。