有限维的

Because the diffusive term is discretized with divided forward difference or divided backward difference according to the sign of convection velocity, these methods keep first order accuracy for diffusive term.

3.2考虑规则网格上的一维和二维定常型对流占优扩散问题，离散方法采用了有限体积方法及普通的有限差分方法，基本离散思想是将对流项提高到二阶精度，扩散项则根据对流速度的方向决定采用向前或向后差商离散。

We present linear codes over finite fields with Mannheim weight and prove that those codes can correct one error taken from a cyclic subgroup of the multiplicative group of finite fields, which provide an algebraic approach in coding modulation.

最后讨论了有限域上的Mannheim线性纠错码，证明了当错误取值于有限域乘群的一个循环子群时，面向多维信号的线性分组码可以纠单个错并为码调制提供了一种代数渐进方法。

There is the Cauchy problem of hyperbolic system with weak damping in Chapter4. In the space of dimension N=1,3, exploiting the semigroup method, the global existence and the decay behavior of the solution with small initial data to problem (about problem with small initial data) is put forward.

当空间维数N=1，3和初值充分小时，利用半群理论得到问题整体解的存在性，并对于整体解给出一致衰减估计；当空间维数N=1 时，利用试验函数方法讨论解在有限时刻爆破的条件。

The discrete velocity ordinate method in the kinetic theory of gases is developed and applied to discretize the correspo

借助非定常时间分裂法和无波动无自由参数的NND耗散格式，建立直接求解微观分子速度分布函数的有限差分数值格式；研究并发展可用于离散速度坐标点选取和离散速度空间宏观取矩的高斯─埃尔米特无穷积分方法、等均间隔的牛顿─柯斯复合积分法、以勒让德多项式的根为积分结点的高斯─勒让德数值积分法，并应用于不同马赫数绕流模拟；通过对不同流域一维激波管问题、二维圆柱绕流问题和三维球体绕流的计算研究，并将计算结果与其他途径得到的研究结果诸如DSMC模拟值、N-S解及有关实验数据进行比较分析，创建了一套能有效模拟稀薄流到连续流不同流域气体流动问题简化的统一数值算法研究框架

In order to analyze vertical bearing behavior of large diameter belled pile in soft substratum, three-dimensional non-linear finite-difference numeric models are established with finite-difference program, calculated and measured results are contrasted, and it proves that the calculation models and the chosen parameters are rational.

为分析存在软弱下卧层的大直径扩底桩的竖向承载性状，本文利用有限差分程序建立三维非线性有限差分数值模型，将计算结果与实测数据进行对比，验证了计算模型与参数选取的合理性。

In this paper,by the matrix method,a necessary and sufficient condition for two n-dimensional synclastic simplexes to be able embedded in the n-dimensional Euclidean space is obtained,as well as for two group finite point sets.

该文利用矩阵的方法，获得了两个同向的n维单形同时等距嵌入E~n维欧氏空间的一个充分必要条件是：对于预给(n+1)~2个距离，满足一组具有行列式形式的不等式组det，由此可以得到两组等数量的有限点集合到E~n维欧氏空间中等长嵌入的一个充分必要条件。

Firstly, the basic principle of Finite-Difference Time-Domain is introduced and the 2-dimensional FDTD equation is derived from the Maxwells equations, calculated by setting up the appropriate excitation source, cell size, the interval of space and time.

首先，介绍了时域有限差分法的基本原理，从麦克斯韦方程出发，建立二维空间中的时域有限差分方程，通过设置合适的激励源、网格尺寸、空间和时间步长进行计算。

First, we introduce the linearly distributed stress tensors as the source and by means of two-dimensional finite-difference scheme to obtain the response of this source, then the point source response is generated by correcting both the wave forms and geometrical spreadings for the linear respons.

但在理论地震学，工程地震学和勘探地震学中横向不均匀介质中的波传播问题非常重要，此时使用有限差分法和有限元法等离散数值方法比较有效。鉴于目前计算工具的限制，三维模型的有限差分计算虽然在理论上是可行的，但很少能用于实际。

A numerical solution of the isothermal EHL problem for finite line contacts has been pressnted which is convergence in moderate load and material parameters.

二。用差分格式离散二维Reynolds方程，通过间接求解的方法，推出了中等载荷和材料参数下收敛的等温有限长线接触弹流数值计算方法，有效地克服了等温有限长线接触Reynolds方程的强各向异性所产生的数值计算易发散问题。

In this paper, the finite-difference time-domain formation of Maxwell's equation is deduced and coded in perfectly matched layer in three-dimension cylindrical complex coordinates.

在三维柱坐系下推导了完全匹配层吸收边界条件的时域有限差分表达式，从而把 FDTD方法推广到完全三维柱坐标系中。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。