查询词典 finite difference approximation

But it demands the higher computational accuracy. Time-dependent LU-SGS method and close coupled full implicit finite volume scheme are used. The AUSMPW+ based on the three-order MUSCL difference scheme is used for the inviscid operator, and the maximum eigenvalue splitting method is used to convert matrix operation to algebraic operation in order to shorten the computing time.

运用时间相关的LU-SGS方法，采用强耦合的全隐式有限体积进行离散，其中无粘对流项采用三阶MUSCL型差分的AUSMPW+格式，并应用最大特征值分裂，将矩阵运算转化为代数运算，大大缩短了计算时间。

The finite difference is used to approximate differential operation; the reflectance map equation described by the first order nonlinear differential equation is transformed into an algebraic equation about the unknown surface heights, and then the objective equation is constructed by the reflectance map equation and gradient information of image. Moreover, the Newton iterative algorithm is utilized to obtain the numerical solution and 3D shape of the surface.

采用有限差分近似微分运算，将一阶非线性微分方程所描述的反射图方程转化为关于未知表面高度的代数方程，再由反射图方程和图像梯度信息构造目标方程，进而用Newton迭代算法求出该方程的数值解，得到表面三维形状。

The technique of boundary-fitted coordinate system is used to overcome the difficulties resulting from the complicated shapes of natural river boundaries;the method of alternating direction implicit finite difference scheme is used to solve the partial differential equations in the transformed plane;and the technique of moving boundary is used to deal with the river bed exposed to water surface.

用适体坐标技术克服天然河道复杂的几何边界给有限差分法所带来的困难；用交替方向隐式有限差分格式求解变换平面上的偏微分方程；用动边界技术处理河床的淹露。

To reduce the large numerical dispersion error for the alternating direction implicit finite-difference time-domain method, an isotropic ADI-FDTD method with low numerical dispersion error was presented.

针对交替方向隐式时域有限差分方法数值色散严重的缺点，提出了一种低数值色散的各向同性ADI-FDTD方法。

In the fourth chapter, we build the model of coefficient on one dimension partial differential equation and adopt finite element method to discrete partial differential equation and in the fifth chapter, we employ GP to identify and build the model of right-side function and adopt over-relaxation or alternating direction implicit method to solute difference equation.

在求解这些偏微分方程连续系数反演或右端连一一一~武卫1里鱼立二大一至」夔里匕崖匕位止透二立一一一一续函数的适应值评价中，我们都采用H'一范数正则化来解决连续参数的识别问题。

State Key Laboratory of Millimeter Waves, Southeast University , Nanjing 210096, ChinaIn this paper, it is proven that the divergence relationship of electric-field and magnetic-field is non-zero even in charge-free regions, when the electric-field and magnetic-field are calculated with Alternating Direction Implicit Finite-Difference Time-Domain method, and the concrete expression of the divergence relationship is derived.

摘要该文证明了即使在无源区域，交替方向隐式时域有限差分法所给出的电磁场量不满足零散度关系，同时推导出了该散度关系的具体表达式。

In this paper, we investigate the light intensity-dependent superprism phenomenon in the two-dimensional Kerr nonlinear photonic crystal by nonlinear finite-difference time-domain technique. We show that when the intensity of the self-pumping beam is increased from 70 to 300 W/μm , the refraction angle of the beam can be tuned about 10 degree.

基于非线性时域有限差分法，我们模拟了克尔非线性光子晶体中的光敏超棱镜现象，结果发现，当光强变化230W/μm时，两束光在空间上能被分开10o，选取较大的基本功率将有助于提高其光强分辨率，。

Tilt angle and twist angle of director with applied voltage at certain δ/λ are calculated with finite-difference iterative method.

根据这些方程和边界条件，利用差分迭代方法计算出指向矢倾角和扭曲角对应某一个δ/λ值在不同电压下的分布。

The main works include: In this thesis, we use Finite Difference Time Domain method to study the relationship between diffraction efficiency, angular dispersion and grating constant, to discuss how the grating figure influence the diffraction efficiency, and to research the frequency spectrum characteristic.

主要工作包括：本文分别在垂直入射和自准直入射（光垂直于光栅刻槽面入射）情况下，采用时域有限差分方法，利用商业数值计算软件OptiFDTD对二维闪耀光栅进行了矢量电磁场数值计算，研究了光栅的衍射效率和角色散随光栅常数的变化情况，研究了光栅形状对光栅衍射效率的影响，还讨论了各种光栅的频谱特性。

The result shows that the mixed boundary condition can greatly reduce the calculation area without affecting accuracy of the solution.It is followed by the higher accuracy of Dirichlet boundary condition which makes the boundary error greater when measured points is near the boundary, so we must take a sufficiently large border region.The homogeneous boundary condition has relatively large error, but the use of non-triangle poles devices makes apparent resistivity calculation error become small, because of elimination of the effect on potential difference for the infinite boundary. In inversion, in order to save computing time, homogeneous boundary conditions are often used to perform finite element forward calculation.

结果表明，混合边界条件精度最高，可大大缩小求解区域而不影响计算精度，其次是Dirichlet边界条件精度较高，但测点越靠边界误差会越大，必须取足够大的边界区域，齐次边界条件的误差比较大，但如果采用非二极装置，通过电位差计算得到的视电阻率，由于无穷远边界对电位差的影响基本消除，视电阻率计算误差与混合边界条件下的接近，在反演中，为了节省计算时间，经常使用齐次边界条件进行有限元正演。

We have something to do in the new stage.

在这段崭新的时期中，我们有一些要做的。

The difference between tourism decision-making under uncertainty and risky tourism decision-making is indistinctive.

其中不确定性旅游决策和风险旅游决策的界线比较模糊，两者的区分是相对的。