一维粘弹性波动方程弹性系数的识别方法

本文就一维粘弹性波动方程弹性系数的求解问题，给出了一个新的求解方法．通过对算法进行分析可知，该方法具有较小的计算量，并且具较好的数值稳定性．数值模拟表明了该方法的可行性及有效性．     

求热传导方程数值解并行算法

本文对热传导方程的初边值问题进行了研究．利用区域分解法构造了高度并行的数值算法．并给出它的稳定性条件和算法精度．最后利用数值算例进一步说明该并行算法有效性和实用性．     

扩展型动网格的Chebyshev有限谱方法

给出了基于非均匀网格的Chebyshev有限谱方法．提出了可生成两种类型扩展型动网格的均布格式．一种类型的网格被用来提高波面附近的分辨率,另一种类型则用在梯度较大的流动区域．由于采用Chebyshev多项式作为基函数,该方法具有高阶精度．从上个时间步到当前时间步,两套不均匀网格间的物理量采用Chebyshev多项式插值．为使方法在时间离散方面保持高精度,采用了Adams-Bashforth预报格式和Adams-Moulton校正格式．为了避免由Korteweg-deVries(KdV)方程的弥散项引起的数值振荡,给出了一种非均匀网格下的数值稳定器．给出的方法与具有分析解的Burgers方程的非线性对流扩散问题和KdV方程的单孤独波和双孤独波传播问题进行了比较,结果非常吻合．     

椭圆型方程的重叠型区域分裂混合元方法

本文研究椭圆型方程的重叠型区域分解混合元方法，对第一边值和第二边值问题，分别给出了离散形式的区域分解混合元格式；证明了区域分裂格式解的存在唯一性和算法的收敛性，并给出数值算例．     

定常Stokes方程一种基于完全区域分解的有限元并行算法

基于完全区域分解技巧,提出了一种求解定常Stokes方程的有限元并行算法．该算法中,所有子问题都是定义在整个求解区域上,但绝大部分自由度来自其所负责的子区域,从而使得算法稍加修改现有的串行程序即可实现相应的并行计算,实现简单,通信需求少．数值结果验证了算法的高效性．     

一类非凸区域的拟法锥构造方法及其在非凸规划求解中的应用

本文给出基于球形的一类满足拟法锥条件区域的拟法锥构造方法,基于该可行域的拟法锥,建立求解在该类非凸区域上的规划问题的K-K-T点的部分凝聚同伦组合方程,并证明了该同伦内点法的整体收敛性,给出实现同伦内点法的具体数值跟踪算法步骤,并通过数值例子证明算法是可行的和有效的．     

Navier-Stokes方程的一种并行两水平有限元方法

基于区域分解技巧,提出了一种求解定常Navier-Stokes方程的并行两水平有限元方法．该方法首先在一粗网格上求解Navier-Stokes方程,然后在细网格的子区域上并行求解粗网格解的残差方程,以校正粗网格解．该方法实现简单,通信需求少．使用有限元局部误差估计,推导了并行方法所得近似解的误差界,同时通过数值算例,验证了其高效性．     

曲边区域上的多边形网格间断有限元离散及其多重网格算法

本文利用多边形网格上的间断有限元方法离散二阶椭圆方程,在曲边区域上,采用多条直短边逼近曲边的以直代曲的策略,实现了高阶元在能量范数下的最优收敛.本文还将这一方法用于带曲边界面问题的求解,同样得到高阶元的最优收敛.此外我们还设计并分析了这一方法的\linebreakW-cycle和Variable V-cycle多重网格预条件方法,证明当光滑次数足够多时,多重网格预条件算法一致收敛.最后给出了数值算例,证实该算法的可行性并验证了理论分析的结果.     

对流扩散方程区域分裂特征差分方法

1引言对流扩散方程是许多物理问题的数学模型,研究其稳定的数值解法具有重要的应用价值．而标准的差分法和有限元法通常会失效,出现数值振荡．80年代,Douglas和Russel提出了特征线方法,在一定程度上克服了数值振荡,保证了数值的稳定,尤其对“对流占优”问题,更能突出特征法的优越性,并有了大量的理论成果[1,2,3]．区域分裂是一种解决大规模的科学与工程计算问题的有效方法,Dawson,Du和Dupont对热传导方程给出了非重叠区域分裂格式及分析,由于内边界的显格式,需要一定的稳定性条件Δt≤CH2;而Du等在[5]给出了抛物方程的几种区域分裂格式,对区域分裂法的     

Hamilton-Jacobi-Bellman方程的区域分解算法

对离散Hamilton-Jacobi-Bellman方程提出了一类区域分解算法,并在合理的假设下证明了该算法的单调收敛性,数值结果表明该算法的有效性与准确性．     

Relative and absolute error control in a finite-difference method solution of Poisson's equation

An algorithm for error control (absolute and relative) in the five-point finite-difference method applied to Poisson's equation is described. The algorithm is based on discretization of the domain of the problem by means of three rectilinear grids, each of different resolution. We discuss some hardware limitations associated with the algorithm, which are mainly due to its second-order nature. A generalization of the algorithm for finite-difference methods of arbitrary order is presented. We believe that the algorithm is a valuable addition to typical textbook discussions of the five-point finite-difference method for Poisson's equation.     

Multigrid technique for biharmonic interpolation with application to dual and multiple reciprocity method

A biharmonic-type interpolation method is presented to solve 2D and 3D scattered data interpolation problems. Unlike the methods based on radial basis functions, which produce a large linear system of equations with fully populated and often non-selfadjoint and ill-conditioned matrix, the presented method converts the interpolation problem to the solution of the biharmonic equation supplied with some non-usual boundary conditions at the interpolation points. To solve the biharmonic equation, fast multigrid techniques can be applied which are based on a non-uniform, non-equidistant but Cartesian grid generated by the quadtree/octtree algorithm. The biharmonic interpolation technique is applied to the multiple and dual reciprocity method of the BEM to convert domain integrals to the boundary. This makes it possible to significantly reduce the computational cost of the evaluation of the appearing domain integrals as well as the memory requirement of the procedure. The resulting method can be considered as a special grid-free technique, since it requires no domain discretisation. This revised version was published online in June 2006 with corrections to the Cover Date.     

热方程紧差分格式重叠型区域分解算法（英文）

In this paper, a modified additive Schwarz finite difference algorithm is applied in the heat conduction equation of the compact difference scheme. The algorithm is on the basis of domain decomposition and the subspace correction. The basic train of thought is the introduction of the units function decomposition and reasonable distribution of the overlap of correction. The residual correction is conducted on each subspace while the computation is completely parallel. The theoretical analysis shows that this method is completely characterized by parallel.     

A Domain Embedding Method Using the Optimal Distributed Control and a Fast Algorithm

We propose a domain embedding method to solve second order elliptic problems in arbitrary two-dimensional domains. The method is based on formulating the problem as an optimal distributed control problem inside a disc in which the arbitrary domain is embedded. The optimal distributed control problem inside the disc is solved rapidly using a fast algorithm developed by Daripa et al. [3,7,10–12]. The arbitrary domains can be simply or multiply connected and the proposed method can be applied, in principle, to a large number of elliptic problems. Numerical results obtained for Dirichlet problems associated with the Poisson equation in simply and multiply connected domains are presented. The computed solutions are found to be in good agreement with the exact solutions with moderate number of grid points in the domain.     

Pseudospectral time-domain method for pressure-release rough surface scattering using a surface transformation and image method

When numerically analyzing acoustic scattering at a pressure-release rough surface, the conventional pseudospectral time domain (PSTD) method using Fourier transform requires rigorous stability conditions in order to solve the spatial derivative in the wave equation on the irregular boundaries between the two media due to the Gibbs phenomenon and short wavelength in air. To eliminate such disadvantages, a new algorithm is proposed based on the Fourier PSTD method utilizing a surface boundary transformation and an image method. Irregular surface boundaries are flattened by transformation and then an image method is applied to the half-space domain. The efficiency and accuracy of the proposed PSTD method are better than the conventional Fourier PSTD method. Numerical results are presented for a sloped and a sinusoidal pressure-release surface.     

On a numerical algorithm for the solution of the radial Loewner equation

The Loewner partial differential equation provides a one‐parametric family of conformal maps on the unit disk. The images describe a flow of an expanding simply‐connected domain, called the Loewner flow, on the complex plane. In this paper, we present a numerical algorithm for solving the radial Loewner partial differential equation. The algorithm is applied to visualization of Loewner flows with the performance and precision. From the theoretical point of view, our algorithm is based on a recursive formula for determining coefficients of polynomial approximations. We prove that each coefficient converges to true values with reasonable regularity.     

A fast finite difference method for biharmonic equations on irregular domains and its application to an incompressible Stokes flow

Biharmonic equations have many applications, especially in fluid and solid mechanics, but is difficult to solve due to the fourth order derivatives in the differential equation. In this paper a fast second order accurate algorithm based on a finite difference discretization and a Cartesian grid is developed for two dimensional biharmonic equations on irregular domains with essential boundary conditions. The irregular domain is embedded into a rectangular region and the biharmonic equation is decoupled to two Poisson equations. An auxiliary unknown quantity Δu along the boundary is introduced so that fast Poisson solvers on irregular domains can be used. Non-trivial numerical examples show the efficiency of the proposed method. The number of iterations of the method is independent of the mesh size. Another key to the method is a new interpolation scheme to evaluate the residual of the Schur complement system. The new biharmonic solver has been applied to solve the incompressible Stokes flow on an irregular domain.      

An improved time domain linear sampling method for Robin and Neumann obstacles

We consider inverse obstacle scattering problems for the wave equation with Robin or Neumann boundary conditions. The problem of reconstructing the geometry of such obstacles from measurements of scattered waves in the time domain is tackled using a time domain linear sampling method. This imaging technique yields a picture of the scatterer by solving a linear operator equation involving the measured data for many right-hand sides given by singular solutions to the wave equation. We analyse this algorithm for causal and smooth impulse shapes, we discuss the effect of different choices of the singular solutions used in the algorithm, and finally we propose a fast FFT-based implementation.     

解与HJB方程相关的拟变分不等式的松弛法

本文对关于HJB方程的拟变分不等式提出了松弛算法，也给出了基于上述算法的区域分解方法，并建立了相应的收敛性定理。     

交替方向的扩散方程精细积分并行算法

给出了交替方向的二维扩散方程的精细积分算法，将一个时间步积分分为两个方向，使大规模矩阵的计算转化为一些小矩阵的计算，减小了每一步求解的计算量．对于方形区域的齐次方程，计算结果与全城精细积分完全相同，而计算量和存储量都要小得多．算例表明了算法具有较高的并行计算加速比和计算效率．