The thesis also involves some detailed techniques come across in the numerical simulation process of elastic dynamic fem analysis , and remarks the theoretical foundation and applications to them , which covers mass scaling , hourglass deformation mode and dimensional compatibility 本文还对弹性动力学有限元数值计算过程中遇到的若干技术细节进行了深入分析与探讨。这包括质量缩放技术对时间步长的影响、单位制对计算速度的影响以及单元刚度单点数值积分的沙漏模态控制技术等。
In this paper , a 3d finite element analysis software ( fzfx3d ) was compiled to simulate the construction process of mass concrete structures constructed with sequence method . based on the practical project xiluodu arch dam , the dam ' s construction process was simulated by a small time step size , 0 . 5 or 1 days . the environmental temperature change , hydration heat rise , artificial cooling , creep , volume deformatio 运用laplace变换方法将温度的求解表示为只与空间坐标及浇筑时间有关的函数，从而避免了用隐式差分法、有限元法求解时需求解联立方程的因而对测点选择的依赖，也避免了显式差分法求解稳定性受时间步长，测点间距大小限制的缺点，因而具有测点布置灵活的特点。
Then the explicit finite - volume method for the two - dimensional steady navier - stocks equations is studied . in order to prevent odd - even decoupling of the solution and oscillations near the shock waves , artificial dissipation is added . local time step , residue averaging , enthalpy damping and multi - grid method are used to accelerate the convergence during the five - step runge - kutta explicit time marching 在计算中，采用五步runge - kutta显式时间推进，引进人工耗散项以克服中心差分固有的奇偶不关联性和抑制激波附近解的振荡，应用了当地时间步长、残值光顺、焓阻尼、多重网格法等措施加速计算收敛。
In fluid field solving , the numerical flux is estimated using high - accuracy roe scheme with limiter . in time marching , we use dual - time stepping together with implicit lu - sgs scheme and get reasonable results efficiently . the difference of the fluid computation between single grid and overset grids lies in the dispose of the computation boundary 流场解算时,对流场数值通量的求解采用的是带限制器的高阶精度roe格式,时间推进采用了含双时间步长的隐式lu - sgs ( lower - uppersymmetricgauss - seidel )格式,提高了求解的效率。
The explicit method is widely used for its simpleness and little memory consumed with local time step and variable coefficients implicit residual smooth to accelerate the convergence procedure . according to yoon and jameson ' s ideas , an efficient implicit lu - sgs algorithm is carefully constructed by combing the advantages of lu factorization and symmetric - gauss - seidel technique in such a way to make use the l and u operators scalar diagonal matrices , thus the numeric algorithm requires only scalar inversion . the computational efficiency is greatly improved with this scheme 显式方法具有简单，消耗内存小等优点，并采用当地时间步长、变系数隐式残值光顺等加速收敛措施，在定常流动的模拟中得到了广泛的应用;根据yoon和jameson提出的简化正、负矩阵分裂，构造的l 、 u算子只需进行标量对角阵求逆，极大提高了流场数值求解过程的计算效率;采用newton类型的伪时间子迭代技术使时间推进精度提高至二阶。
Based upon the forward simulation principle of ground penetrating radar , this article analyzes the realization method of the half grid spacing and the half time increment in difference format , at the same time analyzed the produce of the numerical frequency dispersion , then deduced the ideal frequency dispersion relationship and the super absorbing boundary condition 摘要本文从地质雷达正演原理著手，分析了差分格式中半空间步长与半时间步长的实现方法，同时通过分析数值频散的产生，进而推导出了理想频散关系和超吸收边界条件。
Hence this method can improve accuracy and efficiency of the calculation . c . based on these work upwards , an adaptively wavelet precise time - invariant integration method was proposed in this paper . in this method , an adaptive multilevel interpolation wavelet collocation method for partial difference equations ( pdes ) was conducted , in which the time complexity is less than oleg v ' s method , and then the adaptive precise integration method was combined with , so that in this method the adaptively discretes both in time domain and physical domain were realized 该方法将外推法引入求解结构动力方程的精细时程积分法中，从而使该方法在求解非线性动力方程中可以自适应选取时间步长；需要指出的是，由于考虑了矩阵指数精细算法和外推法算法在时间离散方法上的一致性，在外推过程中，计算工作量基本没有增加；因此，两种方法的结合有效提高了算法的效率和精度。
In this paper , the upwind scheme and the central scheme are presented for solving 3 - d n - s equations using the cell - center finite volume spatial discretization and four - stage runge - kutta time stepping scheme , with standard convergence acceleration techniques such as local time stepping and implicit residual smoothing 在n - s方程的数值计算上，采用了中心差分格式和迎风格式，用格心格式的有限体积法进行了空间离散，用四步龙格?库塔法作显式时间推进，并采用了当地时间步长和隐式残差光顺等加速收敛措施。
Secondly , basic model of one - stage investment decision is provided and the effects of the parameters , including the capacity step , time step etc on the simulation are understood at the same time , the algorithm ( monte carlo method ) of basic model is given and the basic model is studied in order to find how the three parameters of demand affect the investment decisions 其次，在一系列假设的基础上，提出了单阶段投资决策的基本模型，分析了规模步长、时间步长、样本数量等参数对模拟结果的影响，给出了该模型的蒙特卡洛模拟算法，并对该模型进行了系统研究，明确了需求的3个参数(需求漂移率、需求的波动率和初始需求)如何对投资决策结果产生影响。
Because of continuity of load effects in time and space , displacement effects of previous time period in the latter time period and effects in various places have been taken into accounts . it is on these basis that the paper puts forward the dispersed counting way discrete algorithm based on such relationship , takes time - stepping integration to calculate rails " dynamic response , uses fortran language to write counting program , and conducts computer mock tests about rails " power response 由于荷载作用在时间和空间上的连续性，因此考虑了前一时间段所产生的位移对后一时间段的影响以及不同位置的相互影响，在此基础上提出了基于车轮、轨道、枕木相互关系的离散化算法，采用时间步长积分计算了轨道的动力响应，使用fortran语言编制计算程序对轨道动力响应进行了模拟。
