查询词典 finite difference approximation

In the forward aspect, the advantages and disadvantages of such methods as finite difference, finite element and integral equation as well as their development trend are discussed. In the inversion aspect, mainly linear and nonlinear inversions are analyzed, with a detailed discussion on the linear inversion methods both in the time domain and in the frequency domain as well as a prediction of their future development trend.

正演方面主要讨论了有限差分、有限元和积分方程法，分析了各种方法的优缺点、适用范围，并指出了未来发展趋势；反演方面主要讨论了线性反演和非线性反演，根据井间电磁波成像的性质，对时间域和频率域线性反演方法分别做了详细论述，并给出了未来发展趋势。

Up to now, finite difference method, finite element method and boundary element method are common numerical methods to obtain numerical solutions of parabolic partial differential equation.

目前求解抛物型偏微分方程的数值方法有有限差分法、有限元法和边界元法等。

Meshless method is a kind of method with good prospection, it can deal with many problems which can not be resolved by traditional method (finite element method, finite difference method).

无网格法是一种前景广阔的方法，能够解决许多其他传统方法（如有限元方法、有限差分法等）所不能解决的问题。

Axial temperature and pressure drop are calculated by finite difference. Radial temperature field is calculated by finite element.

采用有限差分方法求解了轴向温降及压降，采用有限元方法求解了径向温度场。

In theory, firstly, the numerical simulation methods, such as the boundary element method, the finite difference method and the finite element method, were utilized to calculate the distribution of electric field intensity and potential of the electron-gun system, the focusing system and the whole equipment, respectively. Then, the trajectories of the electron-beam were traced by using of the Runge-Kutta method and the Monte-Carlo method associatively. The point spread function was also calculated.

在理论分析中，先后采用边界元方法、差分方法、有限元方法等科学数值计算方法，编制程序，对X射线源的电子枪发射系统、聚焦系统以及发射系统与聚焦系统的组合系统等的电场分布进行了严格的计算，在准确求得各系统电场内各个剖分点的电场场强、偏导数等参量的基础上，采用蒙特-卡罗模拟方法和不等距龙格-库塔方法相结合，追踪由LaB_6单晶阴极表面发射出的大量电子束在电场内的运动轨迹，求出点扩展函数，并根据点扩展函数的优劣，反复调节、大量计算对比，挑选出X射线源最佳的电极结构及其组合。

For example, a regenerative reheating furnace fluid flow and heat transfer is researched, which has simplified the flow and heat transfer of hot air stove according to its real operating conditions.The fluid flow and heat transfer of a hot air stove are numerically simulated by using finite volume method or finite difference method,which bases on the heat transfer equation,flow equation of the gas and heat balance equation.

根据热风炉的实际运行状况对蓄热式热风炉内的流动换热过程进行了合理的简化，并基于热传导方程、气体流动方程和气体的热平衡方程，建立了蓄热体的非稳态传热模型，在对模型利用有限差分法和有限容积法得到离散方程的基础上，采用C 语言编制了模拟计算程序。

To this end, a numerical approach combined by the finite element method for magnetic fields and the finite difference method for deflection of the microsensor is proposed to analyze quantitatively the deflection under magnetoelastic interaction.

为此，建立了由有限元方法分析磁场与有限差分法计算挠曲变形相结合来计算其结构在磁场中产生磁弹性变形的定量分析程序。

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。

However,most of the current numerical implementation are based on a hybrid finite - element/finite - difference/control - volume solution with the middle - plane model. This kind of model leads to great inconvenience in applications..

但目前的流动模拟软件都是采用基于&中性层&模型的有限元/有限差分/控制体积法来分析z1，所谓中性层是假想的位于模具型腔和型芯中间的层面，其模拟过程如图1所示。

Firstly, the isotropic difference templates were introduced to approximate the differential in the ADI-FDTD method, and the weighting coefficients of difference terms were determined for implementing isotropic numerical dispersion; Then the permittivity and permeability were adjusted manually to reduce the numerical dispersion error in any directions. Therefore the simulation accuracy and efficiency can be improved effectively for time domain problems with some finite bandwidths.

该方法在ADI-FDTD方法的差分近似微分中引入各向同性差分模板，并通过确定各向同性差分的加权系数来近似实现各向同性，然后人为修正空间的介质参数来减少各个方向上的数值色散误差，因此在模拟一定带宽的时域问题时可有效提高计算精度和计算效率。

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！