查询词典 calculus of finite difference

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。

It is shown that in Jameson's algorithm is not an orthogonal stream-lines coordinate system, but a local stream-lines coordinate system instead. Nevetheless, because of the finite-difference discretization in Jameson's scheme is not carried out along the direction of s and n, but along the Cartesian coordinates, the analysis on all terms of the full potential equation in Cartesian coordinates reveals that his scheme does take a back-ward difference along the streamwise exactly at all points in the supersonic flow region.

表明其所采用的坐标系不是真正的正交流线坐标系，而是局部流线坐标系；同时由于Jameson方法并不对s，n进行差分离散，而是在原笛卡尔坐标系下作差分离散，对笛卡尔坐标系下的全位势方程中的各项的分析表明，Jameson方法恰好能做到在超音速点沿真正的流线方向作后差分。

The difference between the differential and the finite-difference operator is however a primitive error source in the numerics.

然而，解析性微分算子和离散性差分算子的差异却是造成数值计算的原始误差源。

This model used the finite—difference approximation to the advection— dispersion equation. The spatial derivatives in the flow equation are approximated by central difference written about grid—block boundaries and time derivatives are approximated by a fully implicit backward scheme.

水流方程的空间导数采用中心差分格式离散，时间导数采用隐式差分格式离散，建立了土壤水分和污染物在各种饱和度的条件下迁移转化方程耦合求解的二维数值计算模型。

In this paper, a high order accuracy difference method is presented for solving unsteady convection diffusion equation by using Implicit Perturbation Finite Difference scheme.

本文利用摄动差分思想，对定常对流扩散方程中的空间微商系数进行摄动展开，展开幂级数系数通过消去摄动格式修正微分方程的截断误差项求出，由此获得方程的隐式摄动差分格式，将此方法应用于非定常对流扩散方程，并加以修正，得到该方程的修正隐式摄动差分格式。

Magnetic field method is used to analysis the distribution of multi-medium, complex boundary, large difference in dimension, non-linear and forced axial symmetry magnetic field in magnetic fluid seal, the data is derived by unequally spaced net finite difference, and the results of different structure are showed by magnetogram.

利用变步长有限差分法对磁场法描述的磁流体密封中磁介质多、边界复杂、尺寸差别大、非线性的强磁场进行求解，得到了多种形式密封结构磁力线和磁感应强度等值线的分析结果。

But the finite difference methods require that computational domain is regular, and usually people construct the difference scheme for one dimension and then extend it to two or three dimensions in a dimension by dimension fashion.

有限差分方法要求计算区域比较规则，而且人们往往是对一维方程构造差分格式，再用分裂方法将其推广到多维。

A combined super compact finite difference scheme is proposed.Numerical characteristics of CSCD is analysed and compared with other symmetric difference schemes.

提出一族组合型超紧致差分格式，对CSCD的数值特性作了分析，并同其他中心型差分格式进行比较。

In the method of numerical analysis, the spatial part of equation system in strong conservation form is first discretized by conventional central finite-difference approximation and then the system of partial differential equations becomes a system of ordinary difference equations.

本文所建数值方法的基本空间离散格式是中心差分，并用源于Jameson的标量耗散模型抑制数值波动；采用经典四阶龙格—库塔法积分经过空间离散后得到的常微分方程组当残差足够小时的解为稳态解。

FLAC~(3D) is for the analysis of the Lagrange explicit finite difference procedure for the timely steps to solve the dynamic relaxation, for when the difference method based on the show, less memory, faster solution. This paper discusses the usage of model FLAC create certainty and mixed model approach and to a dam seepage stability analysis as the research object, the establishment of a certainty piezometric level model, and further establish hybrid model, and the permeability coefficient for inversion analysis.

本文探讨了利用FLAC建立确定性模型和混合模型的方法，并以某土坝渗流稳定分析为研究对象，建立了测压管水位的确定性模型，进一步建立混合模型。

You can snipe the second and third union leaders from this position.

您可以鹬第二和第三工会领袖从这一立场出发。

Aiming at the currently shortage of XML streams quality detecting, this paper proposes a new forecasting method of XML streams quality by least squares support vector machines, which is used the method of XML keys' vector matrix as windows, and vector product wavelet transform to multilevel decompose and refactor the XML streams series, that can fulfill real-time checking demand of XML quality, and ensure constraint, consist- ency and integrality. For even more adapting net load, it proposes a control strategy by weight and adaptive adjustment to ensure XML streams quality.

针对当前XML数据流质量检测存在的不足，提出构建XML键的矢量矩阵作为窗口，利用矢量积小波变换多级分解与重构XML数据流，再结合最小二乘支持向量机对XML数据流质量进行预测的一种方法，满足XML数据流质量重构时实时检测的要求，保证XML数据的约束性、一致性与完整性；为了更好的适应网络负载，采取加权与自适应窗口调整等调度策略充分保证XML数据流的质量检测。