改进的奇异摄动自适应移动网格方法

用等分弧长函数来控制网格剖分,用迎风有限差分格式来求解一类奇异摄动两点边值问题的自适应算法。本文用了的数值试验证明了算法的可行性和高效性。     

二维有限元网格自动自适应生成

为使有限元法能更有效地应用于日益复杂的科学和工程计算,提出一种自动自适应网格生成方法．该方法在结合推进波前法和法向偏移法的优势的基础上产生,改进了节点的生成方式,融入了简单灵活的密度控制方式和合理准确的边界离散方式．剖分实例显示,该方法能有效地生成高质量网格,自动化程度高,适应能力强;它已成功地应用于复杂海域下波浪与结构物相互作用的有限元计算,并取得了很好的效果．     

一种自适应运动目标检测算法及其应用

针对ViBe算法在动态背景下存在鬼影消除时间长、算法适应性差、前景检测噪声多的问题,本文提出一种基于ViBe算法框架的改进算法.该算法采用鬼影检测法标记第1帧中的鬼影区域,并向位于鬼影区域的背景模型中强制引入背景样本,从而快速抑制鬼影;在像素分类过程中,引入自适应分类阈值,解决全局阈值易受动态噪声干扰的问题;在背景模型...     

径向基函数及移动网格在Euler方程数值计算中的应用

基于二维Euler方程,在利用弹簧技术的移动非结构三角形网格上给出了一种基于紧支径向基函数重构的ENO型有限体积格式,方法的主要思想是先对每一个三角形单元构造插值径向基函数,而在计算交界面的流通量采用两点高斯积分公式以保证格式的整体精度,时间离散采用三阶TVD Runge-Kutta方法。最后用该格式对一些典型算例进行了数值模拟,结果表明该方法计算速度快,对间断有很好的分辨能力。     

Unconditionally stable high-order time integration for moving mesh finite difference solution of linear convection–diffusion equations

This paper is concerned with moving mesh finite difference solution of partial differential equations. It is known that mesh movement introduces an extra convection term and its numerical treatment has a significant impact on the stability of numerical schemes. Moreover, many implicit second and higher order schemes, such as the Crank–Nicolson scheme, will lose their unconditional stability. A strategy is presented for developing temporally high-order, unconditionally stable finite difference schemes for solving linear convection–diffusion equations using moving meshes. Numerical results are given to demonstrate the theoretical findings.     

Moving Mesh Method with Error-Estimator-Based Monitor and Its Applications to Static Obstacle Problem

The main objective of this work is to demonstrate that sharp a posteriori error estimators can be employed as appropriate monitor functions for moving mesh methods. We illustrate the main ideas by considering elliptic obstacle problems. Some important issues such as how to derive the sharp estimators and how to smooth the monitor functions are addressed. The numerical schemes are applied to a number of test problems in two dimensions. It is shown that the moving mesh methods with the proposed monitor functions can effectively capture the free boundaries of the elliptic obstacle problems and reduce the numerical errors arising from the free boundaries.     

On Time-Space Efficiency of Digital Trees with Adaptive Multidigit Branching

Parameters of time-space efficiency and sparseness of nodes in trees with adaptive multidigit branching are studied. Both precise and asymptotic expressions, describing average behavior of these parameters in a memoryless model, are obtained. These expressions are used to establish a relation between parameters. As a result, conditions of time-space optimality of trees constructed with the use of Nilsson and Tikkanen algorithm are obtained.