近似计算

A Study on Fraunhofer Double-Slit Diffraction by Applying Simulation Technology;2. Based on Kirchhoffs theory,the approximate intensity formulas of double-slit diffraction of Gaussian Beam is derived under paraxial approximation with power series expansion methods.

依据基尔霍夫衍射理论，利用幂级数展开的方法推导出旁轴条件下高斯光束双缝衍射的近似光强计算公式，并通过数值计算对双缝衍射的基本特性进行了讨论，得出了与其他文献一致的结论，得出了高斯光束下的双缝衍射极小值点比平行光束双缝衍射的极小值点向外移，观察屏中心光能变小；光强分布可由激光斑在衍射屏处的参数调制的结论。

Highly precise quadra order non-linear formula is set up, which gives the satisfactory density value of highly pure aluminum (99.999~99.99999 %) at 20 oC.Linear approximate formula for the density calculation of 99.75% primary aluminum (molten point in the range of 658.7℃～1100℃) derived f...

以Jagrangian插值的二次多项式和一次多项式导出的 99.75 %原铝(熔点 6 5 8.7℃～ 1 1 0 0℃)的密度计算的线性近似式、该式子较文献〔1〕所述的还要简单，而数值计算结果却高度吻合。

In consideration of large computational efforts of Deodatis simulation,a modified spectral representation method was proposed for simulating the fluctuating wind field of long span bridges.

针对现有Deodatis方法模拟大跨度桥梁空间脉动风场中存在的计算量问题，通过对谱分解矩阵引入插值近似，减少谱分解的次数，从而提高该谐波合成法的计算效率，并节省内存花费，实现了对三维空间脉动风场的有效模拟。

A variational method with differential forms gives better precision for numerical solution of transport critical problem based on spherical geometry, and its computation seems simple than other approximate methods.

对于球几何问题，讨论了一种基于微分方程的变分形式求解方法，数值计算显示达到了较满意的精度，而且计算过程比起其他近似方法要简单

In CFD the stress tensor terms are often approximated by a turbulence model.

在计算流体力学中的应力计算，往往是近似由湍流模型。

Structural natural period s are important indexes to reflect on absorbed seismic energy, a formula for structural frequency is deducted according to variation principle in this paper, various ap.

结构自振周期是直接反映结构吸收地震能量多少的重要指标，本文基于能量变分原理推导了结构频率的计算公式，介绍了工程中计算结构自振周期常用的几种近似方法，讨论了影响结构自振周期的主要因素。

By using tangent plane as local approximation of the security region boundary, computational cost for voltage stability online monitoring was greatly reduced on the premise of precision guarantee.

应用切平面作为该域边界的局部近似，进行电压稳定性的实时监控，从而在保证计算精度的前提下节约计算代价。

According to a semi-infinite truncated cone model, in Laplace space the approximate analytical solutions of the bottom surface of rigid circular plate and semi-infinite viscoelastic medium are obtained and the calculating model and formulae of seismic forces are presented.

根据半无限截头圆锥模型，在拉氏空间中获得刚性圆板底面与半无限弹性介质相互作用的近似分析解，提出了刚性圆板地震力计算模型及计算公式。

This method is not necessary to solve a complex unlined partial differential equation so that the computational cost is reduced.

本文在温度场的模拟计算中，将铸件中同时发生的连续的传导传热和对流传热，用在微小时间间隔内独立的传导传热和对流传热近似表达，完成充型过程中流场与温度场的耦合计算。

The voltage drops on two terminals and the total self-impedances of the feeder remain unvaried before and after using the T-BVDM.

文中给出了一些算例，并与严格潮流计算方法进行了比较，结果表明提出的简化方法的近似精度高，并且在应用到基于遗传算法和模拟退火算法等随机优化算法的配电网络重构时，可大大提高潮流计算效率。

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。