中心差分

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。

Numerical examples show that the results are highly accurate in comparison with Newmark、Wilson-θ、Houbolt and central difference method.

算例表明解析逐步积分法和积分型直接积分法比中心差分法、Newmark、Wilson-θ、Houbolt法等有较高的精度。

Absorbing boundary condition ; wave equation ; spectral element ; central difference method

吸收边界条件；波动方程；谱元；中心差分法

Compared with the same wave problems with conventional Dirichlet boundary conditions, the absorbing boundary conditions can reduce the numerical reflection on boundaries and avoid solution distortion. In addition, the central differences method is economic in memory requirement and computing time compared with implicit integral method.

结果表明：该解法在空间上具有谱精度，在时间上达到二阶精度；与第一类边界条件相比，吸收边界有效地削弱了边界上的数值反射，避免了解的失真；使用中心差分的时间积分方法同隐式积分方法相比，适合波的传播特性，避免了矩阵求逆运算，并且占用的计算机内存小。

Fourth precision solution can be derived from two grid sets solution with a second precision central difference scheme by Richardson extrapolation. It reduces the amount of calculation. Uncertainty is determined from the discretization error analysis. A finer grid calculation is made to validate the extrapolation scheme.

对于2阶精度中心差分格式的2套网格数值解，用Richardson外推法可以得到4阶精度的解，其工作量比直接求解4阶离散方程的工作量减少许多；对于计算中的数值不确定度，用该方法分析了离散误差，并用逐次加密网格的方法探讨了外推法的合理性。

The truncation error of CSCD is derived and compared with some symmetric finite difference methods having the same order of accuracy,which shows that CSCD has the smallest coefficients in error terms.

从定性角度，得出同阶中心差分格式中，CSCD格式的截断误差系数最小的结论。

The convection of onflow mode with ROE format disperse, diffuse with the center difference divides format disperse, the control equation after dimensional disperse advances a format to seek solution with explicit time of much pace Runge-Kutta.

湍流模式的对流项用ROE格式离散，扩散项用中心差分格式离散，空间离散后的控制方程用多步Runge-Kutta显式时间推进格式求解。

Also the response amplitude will be changed with the initial conditions due to the nonlinear properties of the cables.Taking the bending stiffness, cable sag and cable inclination into consideration, the space vibration control of the cables using the visco-elastic dampers in cable-stayed bridges is investigated by joining the center difference method and the state space strategy. Both the maximum modal damping ration and the optimal damper size are obtained, then the practical suggestions are proposed for the design of the dampers. The space nonlinear vibration equations of the cable-damper system are derived, and anew hybrid method for solving the cable-damper system is presented by combing the Newmark method and Pseudo-force technology. According to the known properties of the cable-damper system, the nonlinear transient responses are analyzed under all kinds of excitations. Based on the transient response, the control effectiveness of the visco-elastic dampers is further demonstrated.

综合考虑了拉索抗弯刚度、垂度的影响，研究了粘弹性阻尼器对斜拉桥拉索的空间振动控制，联合中心差分方法及状态空间法，得出了拉索面内、外振动各阶模态可能达到的最大阻尼比及相应的最优阻尼器系数，并对斜拉桥拉索的阻尼器设计提出了参考建议：考虑拉索抗弯刚度、垂度及几何非线性，导出了索-阻尼器系统的空间振动非线性方程组，结合Newmark方法及伪力(Pseudo-Force)方法，创新地提出了求解非线性方程组的杂交方法，根据拉索-阻尼器系统的阻尼特性，在各种荷载作用下，对索-阻尼器系统的非线性瞬态振动响应进行了研究，从系统响应的角度更加直接地验证了阻尼器的控制效果。

Then, using the second-order central difference to discretize the time derivative of the displacement, and applying the quadrature formula to the mass matrix, a fully discrete lumped mass Morley element method i...

然后利用中心差分格式离散时间方向的二阶导数，再利用适当的求积公式得到薄板弯曲问题的集中质量Morley元全离散格式。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。