差分法

The finite-difference time-domain method is adopted to simulate the propagation of the optical wave in the beam splitter.

采用时域有限差分法模拟了光波在分束器中的传播行为，并计算了分束器的传输效率。

Tridiagonal block matrix elemination and sweep algorithm is successfully applied to solve the large matrix involved; central difference method is supplemented to Houbolt method to form a time integration method with estimation and correction, to solve the time integration of second order implicit non-linear equation; simplification of system equation by decoupling between the physical coordinates x and y further improves the calculation accuracy and speed.

其中：成功地引入块三对角矩阵追赶法求解上述问题构成的大型矩阵；提出中心差分法+Houbolt法的预估计—校正时间积分法，以解决二阶隐式非线性方程的时间积分问题；系统方程在物理坐标x和y上的"解耦"简化，使计算速度和计算精度得以进一步的提高。

Numerical examples show that the results are highly accurate in comparison with Newmark、Wilson-θ、Houbolt and central difference method.

算例表明解析逐步积分法和积分型直接积分法比中心差分法、Newmark、Wilson-θ、Houbolt法等有较高的精度。

More practical ray tracing methods currently include the wavefront method, the shortest path method, the travel time epenthesis method, the eikonal equation finite difference method, etc.

当前实用性较强的射线追踪方法，包括波前法，最短路径法，走时插值法，程函方程有限差分法等。

At present the numerical simulation of electromagnetic method of finite difference method, finite element method, boundary element law, integral equation method, and so on were commonly used in the exploration.

目前电磁法勘探中常用的数值模拟方法主要有：有限差分法、有限单元法、边界单元法和积分方程法等。

This section further presents three kinds of computation schemes, which are discretization schemes based on linear interpolation, locally quadratic interpolation and mixed quadratic and cubic interpolation.

吴微在[21]中使用三角剖分及外心对偶剖分给出了解双调和方程的基于Ciarlet-Raviart变分原理的混合广义差分法，理论分析部分采用了[26]中的有关思想。

The Rayleigh method, the Ritz method, the Galerkin method, and the finite difference method are extended to solve the engenvalue problem of the plates.

把瑞雷法、李兹法、伽勒金法和有限差分法推广到了这种板的特征问题的求解。

The major implementations of the developed model include: Pseudo-spectral and finite-difference schemes are employed to approximate the spatial-differential operators in the horizontal and vertical directions, respectively. A second-order Runge-Kutta method is adopted to integrate in time for the velocity field and the free-surface elevation. The solenoidal condition of the velocity field is satisfied by solving the transformed pressure Poisson equation. A modified secant method is used to accelerate the iterative solution of the non-separable Poisson equation.

模式的主要数值方法包括：分别以拟频谱法以及二阶有限差分法近似控制方程与边界条件中的水平与垂直导数；以二阶Runge-Kutta法进行非稳态的自由液面位移与流场速度的时间积分；利用改良式割线叠代法求解计算区间中不可分离的压力Poisson方程式，以满足不可压缩流条件。

The book covers one-, two- and three dimensional problems which are solved by using exact and approximate analytical methods and numerical methods such as: the finite difference method, the finite volume method, the finite element method and the boundary method.

书中涵盖一，二和三是利用精确和近似分析方法和数值方法，如：有限差分法求解二维问题，有限体积法，有限元法和边界法。

At present, the common numerical methods are finite difference, finite element , boundary element, integration equation and transmission line method.

目前，解决这类问题的数值方法主要有有限差分法、有限元法、边界元法、积分方程法、传输线法等。

Cynanchum Lingtai apricot production in the average weight 65 grams, the brightly-colored fruit, juicy rich, sweet-sour taste, sweet from the nucleolus, when the late Qing Dynasty famous Shaanxi, Gansu provinces, the Qing imperial court Tongzhi tribute for years.

灵台生产的牛心杏平均单果重65克，果实色泽鲜艳，汁多味浓，甜酸适口，离核仁甜，清末时就驰名陕、甘两省，清同治年间曾为朝廷贡品。

Chenopodium album,Solanum nigrum, and Amaranthus retroflexus were very susceptible to the herbicides. Polygonum persicaria and Abutilon theophrasti were relatively less susceptible to the herbicides, and Lycopersicon esculentum was not susceptible to it. The relationship between reduction rates of weed biomass and PPM values of weed leaves 2,4, and 6 days after treatment was established.

供试的6种杂草对该混剂的敏感性存在显著差异：红心藜Chenopodium album、龙葵Solanum nigrum和反枝苋Amaranthus retroflexus对该混剂最敏感，ED90值分别为47.65、71.67和29.17g/hm2；春蓼Polygonum persicaria和苘麻Abutilon theophrasti敏感，ED90值分别为96.91、114.20g/hm2；而番茄不敏感。