组合时间序列ARMA模型在经济预测中的应用——内蒙古十一五期间GDP预测

2006—2010年是内蒙古"十一五"规划的重要时期.利用组合ARMA时间序列模型,对内蒙古2006—2010年GDP进行预测,得出的结果能够帮助我们把握"十一五"期间经济运行的变动趋势,并寻求最佳的调控办法.     

有限变形弹性理论随机变量变分原理及有限元法

本文将材料、载荷、结构几何形状、力和位移边界条件的随机性,直接引入有限变形弹性理论的泛函变分表达式中,应用小参数摄动法,建立了统一的随机变量变分原理及非线性随机有限元法,并将其应用于结构可靠性分析。算例表明,应用此方法处理随机变量的力学问题,具有使程序实施简便,计算效率高等优点。     

基于参数变分原理的非均质材料弹塑性有限元分析的Voronoi单元法

在非均质材料的有限元数值模拟中,采用了Voronoi单元(VCFEM)以克服经典位移元的局限性．基于参数变分原理和二次规划法进行了Voronoi单元的二维弹塑性分析A·D2推导了有限元列式并形成最终的二次规划求解模型．研究了非均质材料微观夹杂对整体力学性能的影响．数值算例证明了该方法的正确和可行性．     

组合杂交有限元方法对等参双线性Q4-平板元的粗网格精度改进

组合杂交有限元法具有增强低阶位移格式粗网格精度的内在机制，能量误差为零的组合杂交格式可获得改进的粗网络精度，而其中组合参数起着极其重要的作用，采用最简便的四边形位移＼应力模式作为对协调双线性Q4—平板元的改进：协调等参双线性位移插值和纯粹常应力模式，通过调整组合参数，得到了组合杂交元的优化型，数值试验表明这种参数一调整型显改进了协调Q4—元，达到粗网格高精度，由于应力参数可在单元水平消去，这种组合杂交改进型的计算量与协调Q4—元相当。     

结构模糊有限元平衡方程的一种新解法*

本文将区间数方程组解的定义与结构有限元平衡方程的力学意义结合起来,针对由于材料性能的模糊性、结构边界条件的模糊性和载荷的模糊性而得到的模糊有限元平衡方程组.提出了一种快速而准确的解法,其计算量与普通有限元法几乎相等.     

Discrete Maximum Principle and a Delaunay-Type Mesh Condition for Linear Finite Element Approximations of Two-Dimensional Anisotropic Diffusion Problems

A Delaunay-type mesh condition is developed for a linear finite element approximation of two-dimensional anisotropic diffusion problems to satisfy a discrete maximum principle.The condition is weaker than the existing anisotropic non-obtuse angle condition and reduces to the well known Delaunay condition for the special case with the identity diffusion matrix.Numerical results are presented to verify the theoretical findings.     

Recognition of Finite Simple Groups S 4(q) by Their Element Orders

It is proved that among simple groups $S_4(q)$ in the class of finite groups, only the groups $S_4(3^n)$, where $n$ is an odd number greater than unity, are recognizable by a set of their element orders. It is also shown that simple groups $U_3(9)$, ${^3D}_4(2)$, $G_2(4)$, $S_6(3)$, $F_4(2)$, and ${^2E}_6(2)$ are recognizable, but $L_3(3)$ is not.     

交替方向法在保结构的有限元模型修正问题中的应用

本文应用交替方向法处理二次特征值反问题,并要求同时保持对称性,半正定性和稀疏性等结构性质.实验表明我们提出的方法是可行的.     

三维守恒律有限元方法逼近光滑解的误差估计

我们对一个三维守恒律的显式有限元方法证明了H^1范数的二阶误差估计。     

一类非线性Schr(o)dinger方程的非协调有限元分析

在半离散格式下研究一类带幂次非线性项的Schr(o)dinger方程的非协调矩形EQrot1元方法.直接利用插值技巧和该单元的两个特殊性质(相容误差比插值误差高一阶及其插值算子与传统的Ritz投影是一致的),给出相应的收敛性分析及误差估计.     

The Finite Element Method for Computing the Stationary Distribution of an SRBM in a Hypercube with Applications to Finite Buffer Queueing Networks

This paper proposes an algorithm, referred to as BNAfm (Brownian network analyzer with finite element method), for computing the stationary distribution of a semimartingale reflecting Brownian motion (SRBM) in a hypercube. The SRBM serves as an approximate model of queueing networks with finite buffers. Our BNAfm algorithm is based on the finite element method and an extension of a generic algorithm developed by Dai and Harrison [14]. It uses piecewise polynomials to form an approximate subspace of an infinite-dimensional functional space. The BNAfm algorithm is shown to produce good estimates for stationary probabilities, in addition to stationary moments. This is in contrast to the BNAsm algorithm (Brownian network analyzer with spectral method) of Dai and Harrison [14], which uses global polynomials to form the approximate subspace and which sometimes fails to produce meaningful estimates of these stationary probabilities. Extensive computational experiences from our implementation are reported, which may be useful for future numerical research on SRBMs. A three-station tandem network with finite buffers is presented to illustrate the effectiveness of the Brownian approximation model and our BNAfm algorithm.