查询词典 finite difference approximation

When discrete characteristic of digital images is considered, finite difference approximates differential operator.

考虑数字图像离散化特征，用有限差分近似微分运算，将由PDE描述的反射图方程转化为关于未知高度的代数方程，然后使用迭代算法求解，得到新的SFS算法。

A new prestack depth migration method that is based on wave field continuation has been developed by combining physical model of plane wave synthesizing with Fourier finite difference operator for wave field continuation.

本文将平面波合成的物理模型与傅里叶有限差分波场延拓算子相结合，提出了一种新的基于波场延拓的叠前深度偏移方法。

Based on finite difference method and stereolithography file schema, the key techniques of mesh generation in foundry computer aided engineering system have been studied, including the technique for fast generating outlines of cross-section, the technique for handling error tolerance and the technique for rapidly generating mesh from cross-section.

基于有限差分法和标准模板库，研究铸造计算机辅助工程系统中的网格剖分关键技术，具体包括STL实体截面轮廓快速生成、容错处理，以及截面网格信息的快速提取等技术。

The distribution of temperature stress was calculated by finite element analysis. The results showed when the surface temperature of concrete was higher than 110℃, the temperature stress was more than 4 MPa without regard to the creep. This might be lead to the damage of the surface of concrete. At the same time, a lot of microstructure analysiss such as XRD, SEM, IR, HSA etc. were done to analysis the difference of the component and microstructre of concrete before and after corrosion. The results indicated that the decomposion of CSH gel and calcium hydroxide and the creation of dilatability calcium oxide were the internal reason of the deterioration of concrete in the corrosion form of high heat.

该文通过有限元方法计算了由于温度而产生的结构应力分布，计算结果表明当混凝土表面温度超过110℃时，如不考虑徐变时表层混凝土受到的温度应力将超过4MPa，这使得表层混凝土很容易因温度应力而破坏；同时通过X射线衍射分析、扫描电子显微分析和混凝土孔结构分析等多种微观结构测试手段，分析了混凝土受热前后的宏观性能以及微观组成和结构的变化，指出混凝土原水化产物如水化硅酸钙凝胶和氢氧化钙的分解以及膨胀性产物氧化钙的产生是高热腐蚀形式下混凝土破坏的内在原因。

The authors studied carefully two numerical differential methods, finite difference method and rational polynomial technique, and pointed that FDM is the special ease of RPT when the limit state function is linear. Accordingly, FDM3 can be used for the continuous linear limit state function and RPT5 for the continuous nonlinear limit state function. For the discontinuous limit state function, RPT should be used because of the large error of FDM.

对于可靠度分析中常用的有限差分法及有理多项式法这两种数值微分方法，本文详细研究了二者间的异同及其求导结果与步长的关系，指出了对于相同的步长控制系数及取样方式，FDM是RPT在线性情况下的特例；对于连续的线性功能函数，可直接用3点FDM求导；对于连续的非线性功能函数，可用5点RPT求导；对于非连续的功能函数，应采用RPT求导。

In this paper, a method based on finite-difference time-domain arithmetic is used to analyze the dispersive characteristic of PS.

这种算法在继承普通FDTD算法的优越性的同时，由于周期边界条件的引入，使得计算效率大为提高。

Finite-Difference Time-Domain method is a kind of simple and reliable method which is widely used for solving problems related to electromagnetics.

时域有限差分法(Finite-Difference Time-Domain Method，FDTD)是目前较为成熟的应用于电磁计算的时域方法之一。

The finite- difference method is used in calculations on electronegativity and hardness of 103 elements.

并用有限差分方法计算了这 103种元素的电负性和硬度。计算中考虑了相对论效应。

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。

The finite difference method is employed to discretize the governing equations and the projection method is used to derive a pressure Poisson equation that can ensure the satisfaction of continuity equation.

控制方程式采用有限差分法求解，并利用投影法导出压力的波松方程，使得能自动满足连续方程式。

We were cousins—his grandfather was King of Scots,and his great-grandfather was Henry VII of England.

我们是堂姐弟——他的祖父曾是苏格兰国王，他的曾祖父是英格兰的亨利二世。

I do want to help you, but I am in a quandary now!

我是想帮你，但是我现在左右为难啊！