近似法

An analysis for the intensity of light and diffraction angle of bright fringes of the single -slit Fraunhofer diffraction is developed from qualitative to quantitative discussion,basing on the method of Fresnel s half-band and its extention,and on the obrvation for the amplitute vector features of wave band and sub-band on screen.

由菲涅耳半波带法思路出发，加以延伸扩展，结合观察屏上波带与子波带的振幅矢量图象，对单缝夫琅禾费衍射的明纹光强与明纹衍射角作了由定性到定量的讨论，剖析了半波带法明纹公式的近似性。

For composite foundation with compressible piles, based on displacement harmony condition, and combining with load transfer method and approximate solution of differential equation, analysis methods of linear and nonlinear interaction between piles and surrounding soil were suggested.

对柔性桩复合地基，是基于位移协调条件，并结合荷载传递法与微分方程的近似解法——子域法，提出了变截面自由单桩与地基土、刚性承台下柔性单桩和变截面柔性单桩与地基土、刚性承台下柔性群桩与地基土线性及非线性相互作用的分析方法，并得到有效桩长、桩与基土的荷载分配及刚性承台下各桩桩项荷载分配、荷载—沉降关系、荷载传递规律等有意义的结果。

Homotopy perturbation method; MOL method; nonlinear partial differential equation; approximate solution

基础科学，数学，数学分析同伦摄动法；直线法；非线性偏微分方程；近似解

For composite foundation with compressible piles, based on displacement harmony condition, and combining with load transfer method and approximate solution of differential equation, analysis methods of linear and nonlinear interaction between piles and surrounding soil were suggested. A lot of significative results, for example availability pile length, load distribution between piles and surrounding soil, load distribution among all piles under rigidity pile-cap, load-settlement relation etc, were obtained.

对柔性桩复合地基，是基于位移协调条件，并结合荷载传递法与微分方程的近似解法—子域法，提出了变截面自由单桩与地基土、刚性承台下柔性单桩和变截面柔性单桩与地基土、刚性承台下柔性群桩与地基土线性及非线性相互作用的分析方法，并得到有效桩长、桩与基土的荷载分配及刚性承台下各桩桩顶荷载分配、荷载一沉降关系、荷载传递规律等有意义的结果。

This paper explorates the method of nonlinear approximate equation root of" secant line rule"in theory,and disusses two vertexes of secant line rule and one vertex of secant line rule with two kinds of different thought methods and in order to clear some suspicions of learners,which is used as a reference.

现对"割线法"求解非线性方程近似根的方法，从理论上进行了探讨，并用两种不同的思维方式双点割线法和单点割线法进行讨论，来澄清学习者的一些疑惑，以供参考。

In the article, the Shape Function in the Finite Element Method is used. And a surface is evatuated by integral using the Gauss Legendre Quadrature over a triangle.

在这两种模拟中，使用线性分布法会比近似声源法及高阶分布法好，故在此方法的比较里较推荐使用线性分布声源法。

Since any approximations, such as numerical Laplace inversion, backward differentiation formula, nonlinear model of switch, do not exist, the new algorithms are accurate.

由于该方法不存在任何极限近似问题（数值拉普拉斯反变换法，后向差分法，非线性开关模型法等），因而它是一种精确计算方法。

Recently, there are some methods are utilized to study it, such as the modified Lindstedt-Poincare method, frequency-incremental method, stroboscopic method etc.

目前主要的近似求解方法有改进L-P方法、频率增量法、改进的谐波平衡法、频闪法等等。

The advantages and disadvantages of balanced truncation, singular perturbational method and generalized singular perturbation are analyzed. A quasi-generalized singular perturbational model reduction method is proposed.

分析了平衡截断法、平衡奇异摄动法和广义平衡奇异摄动法存在的优缺点，提出了一种近似广义奇异摄动模型降阶算法。

The finite difference time-domain method is stable and easy to be used, but due to the fact that it approximates the space derivatives in Maxwells curlequations by central difference, FDTD usually requires more than 20 grids perwavelength to achieve acceptable accuracy. As a contrast, pseudospectraltime-domain method approximates the space derivatives by pseudospectralmethod, which guarantees the accuracy, theoretically requiting only 2 grids perwavelength.

传统的电磁场数值算法——时域有限差分法稳定而易于实现，但由于FDTD采用中心差分近似Maxwell旋度方程的微分，每个波长上需要取的网格数通常较多，而时域伪谱法采用伪谱法求微分，理论上每个波长只需要取两个网格便可以达到较高的精度。

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。