数值微分法

The grid generation technique for body_fitted coordinate system by means of numerical solution of biharmonic equations is studied, then the topical H_type grid and the flow field is generated and simulated numerically, respectively.

本文对利用双调和方程微分法生成贴体坐标网格的技术进行了探讨和尝试，生成了典型的H型网格，并对流场进行了数值模拟。

Based on the modal superposition method and the exact solution of beam nature vibration, the motion equations of the simply supported and continuo...

基于模态叠加法和梁固有振动的精确解，建立了移动荷载作用下简支梁和连续梁的运动方程；利用样条最小二乘法逼近桥梁应变响应，由样条数值微分求得响应导数；再通过Tikhonov正则化方法结合奇异值分解技术得到了荷载识别的正则解。

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。

A global gravity field recovery based on energy balance approach using CHAMP kinematic orbits is presented. A method combining the Newton's numerical differential formula and the remove_restore procedure for determining kinematic velocities is developed.

介绍了利用CHAMP几何法轨道恢复地球重力场模型的基本原理和算法，提出了基于牛顿数值微分公式并辅助移去-恢复方法计算卫星速度的算法。

Differential Quadrature Method, one of numerical methods of solving boundary problem of differential equation is introduced in this paper. By using DQM, the dynamic stability of pipes conveying fluid and rectangular plates under the action of non-conservative force is studied. The main research work is as follows.

本文首先介绍了求解微分方程边值问题的一种数值方法—微分求积法，然后采用微分求积法分别对输流管道和非保守矩形薄板的稳定性问题进行了分析研究，具体有如下三方面的研究内容。

This paper presents a study on modeling the stability of dump slope using the techniques of limit equilibrium, numerical simulation, and numerical differentiation.

针对废渣场的废渣材料软硬比例发生了不利于堆放边坡稳定的特殊情况，应用极限平衡法、数值模拟及数值微分对渣场稳定进行分析计算。

In the numerical differentiation matlab, useful midpoint formula, adaptive method, Richardson extrapolation methods such as France seek the derivative of the function, the algorithm of the program implementation in the document have been given.

详细说明： matlab中的数值微分，有用中点公式，自适应法，理查森外推算法等方法求函数的导数，算法的程序实现在文件中都已经给出了。

The general principle and the applications of numerical derivative zero crossing method is described for resolving overlapped spectra of binary system.

在简述数值微分零交点法分辨重叠谱的原理基础上，研究了该方法对不同分离度的两组分重叠谱图的分辨效果。

CFD-fluent simulation software and measurement are applied to establish the math models of exhaust gas concentration distribution and boundary conditions. Finite volume methods and PISO are used to solve the differential equations of exhaust gas distribution in a kitchen. After the adjustment and comparison with those from the practical measure, the simulation results of CO2 and CO concentration distributions accord with experimental ones.

运用CFD-fluent模拟软件和实测相结合的方法，建立废气的浓度和扩散分布的数学模型与边界条件，利用数值分析法中的有限体积法和PISO算法对厨房内废气分布的微分方程进行离散和求解，对模拟结果进行校正并与实际测试结果进行比较。

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。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。