差分法

We posed the concept of sufficient intersection about s(1≤s≤n) algebraic hypersurfaces in n-dimensional space and proved the dimension of polynomial space Pm(which denotes the space of all multivariate polynomials of total degree≤m) on the algebraic manifold S=s(f1,…, fs) where f1(X=0,…, f s=0denote s algebraic hypersurfaces of sufficient intersection, then gave a convenient expression for dimension calculation by using the backw ard difference operator.

给出了n维空间中s(1≤s≤n)个代数超曲面充分相交的概念，证明了n元m次多项式空间Pm在充分相交的代数流形S=s(f1，…， fs)（f1=0，…， fs=0表示s个代数超曲面）上的维数，并利用倒差分算子给出一个方便计算的表达式；构造了沿代数流形上插值适定结点组的叠加插值法；证明了在充分相交的代数流形上任意次插值适定结点组的存在性；给出代数流形上插值适定结点组的性质和判定条件。

A numerical simulation technique based on the stable alternating direction implicit method and the upper bound element technique is presented and applied to simulations of extrusion directly following liquid infiltration which involves infiltration,solidification, and large plastic deformation in one process.

采用稳定的交替方向隐式有限差分方法、上限元法等数值计算方法模拟了融浸渗、凝固和大塑性变形为一体的液态浸渗后直接挤压的工艺过程。

Basing on the nonatationary linear mild-slope equation developed by Hong Guangwen in 1995, a complete wave model is built considering the bottom friction, nonlinear dispersion relation, and allied reflection and diffraction of several islands. Integrating with corresponding physical and imaginary boundaries, it is solved through Alternating Direction Implicit difference method.

本文以洪广文(1995)推导的非定常线性波缓坡方程为基础，建立考虑底摩阻项，非线性弥散关系，及多岛屿绕射反射作用的缓坡方程求解模式，采用经典的ADI法差分格式，结合物理和虚拟边界条件进行求解。

The control volume integration was applied to deduce the discrete expressions of the convection-diffusion equations. The staggered grid and SIMPLE algorithm were introduced to deal with coupling between pressure and velocity, and then the numerical computation expressions of such variables as fluid flow velocity and pressure were deduced. Using the backward difference method and incremental theory to discretize the governing equations for fields of chemical reaction, material structure and chemorheology, the numerical computation expressions of variables such as the monomer conversion, average molecular weight and fluid viscosity were constructed.

应用控制容积积分法导出了对流—扩散方程的离散表达式，引入交错网格技术与SIMPLE算法，实现了耦合的压力场与速度场的分离式求解，推导得到了流体的流动速度、压力等物理量的数值计算式；采用向后差分方法和增量方法，实现了化学反应场、材料结构场、化学流变场控制方程的离散，获得了反应转化率、聚合物平均相对分子质量、流体黏度等物理量的数值计算式。

Those equations are dispersed in space by iso-parameter elementmethod and in time by using backward difference. A numerical simulator is established byFortran, the ideas of high part make the of structure program clear, maintain easy, calculationeffective.

在此基础上利用Fortran语言编制了有限元方法的油藏模拟器，采用等参元对渗流方程在空间上离散，采用向后差分在时间上离散，线性方程组的求解采用变带宽高斯消去法，该方法充分利用刚度矩阵呈条带状和其对称性的特点，大大减少了所需存储空间。

This paper presents a fast algorithm based on the measured equation of invariance.Conformal meshes are made along the surface of two-dimensional scatterer.Renumbering of nodes changed the original sparse matrix into band one,and the consumption of computer memory and CPU time decrease from O(N2) to O.Via this new algorithm,electrically large problem can now be rapidly solved.

提要 本文基于不变性测试方程法提出一种快速算法，在二维散射体表面建立共形差分网格后，通过对节点的重新排序，将原问题中的稀疏矩阵变换为带状稀疏阵，从而使占用的计算机内存和计算时间均由O(N2)下降为O，可以解决原来无法计算的问题。

Numerical simulations of the three dimension viscous flow over the SUBOFF-1 model provided by DARPA and other two models are processed by solving RANS equations withκ-εtwo-equation turbulence model and finite volume method, and with SIMPLEC method for pressure-linked terms, central difference shemes for temporal derivative terms, and second-order upwind schemes for convective and diffusive terms.

本文基于RANS方程，采用κ-ε两方程湍流模型来封闭控制方程，采用有限体积法离散控制方程，对于速度压力关联方程，应用协调一致的SIMPLEC算法求解，变化率项用中心差分，对流扩散项采用二阶迎风格式，分别对DARPA提出的裸艇体SUBOFF-1模型以及另外两种回转体模型进行了数值模拟计算。

On detailed study of the central difference finite volume method proposed by Jameson, discrete formulae of 3-D Euler equations and N-S equations are presented.

详细研究了Jameson的中心差分有限体积法，推导了Euler方程和N-S方程的空间和时间离散公式。

By central difference in time and space and boundary conditions, equilibrium equations of warp are transformed into the definite equations and solved by Newton\'s iteration.

通过在时间和空间上对拖网曳纲平衡方程组进行中心差分以及首尾边界条件的处理，将该方程组转换为定解代数方程组，并采用牛顿迭代法求解。

Electrocatalysis of carbon atom wire modified electrode to the electrochemical reaction of uric acid was investigated by using cyclic voltammetry and differential pulse voltammetry.

通过循环伏安法和差分脉冲伏安法研究了碳原子线修饰电极对尿酸电化学反应的催化作用。

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。