On the use of characteristic‐based split meshfree method for solving flow problems

This study presents characteristic‐based split (CBS) algorithm in the meshfree context. This algorithm is the extension of general CBS method which was initially introduced in finite element framework. In this work, the general equations of flow have been represented in the meshfree context. A new finite element and MFree code is developed for solving flow problems. This computational code is capable of solving both time‐dependent and steady‐state flow problems. Numerical simulation of some known benchmark flow problems has been studied. Computational results of MFree method have been compared to those of finite element method. The results obtained have been verified by known numerical, analytical and experimental data in the literature. A number of shape functions are used for field variable interpolation. The performance of each interpolation method is discussed. It is concluded that the MFree method is more accurate than FEM if the same numbers of nodes are used for each solver. Meshfree CBS algorithm is completely stable even at high Reynolds numbers. Copyright © 2007 John Wiley & Sons, Ltd.     

A 2-approximation algorithm for interval data minmax regret sequencing problems with the total flow time criterion

In this paper we discuss a minmax regret version of the single-machine scheduling problem with the total flow time criterion. Uncertain processing times are modeled by closed intervals. We show that if the deterministic problem is polynomially solvable, then its minmax regret version is approximable within 2.     

The variance equity measure in locational decision theory

Classical location theories and models were initially developed for the private sector, so that the related operational research literature has emphasized performance measures of efficiency and effectiveness. For public sector applications, measures of equity become important, yet such measures have received little formal treatment. This paper suggests a locational equity measure, the variance measure, and investigates its properties for tree networks. A fast algorithm (O(M)) to locate the minimum variance point on a tree network is developed, and some numerical results illustrate the variance optimal location.This work is dedicated to the memory of Professor Jonathan Halpern     

Number-theoretic interpretation and construction of a digital circle

This paper presents a new interpretation of a digital circle in terms of the distribution of square numbers in discrete intervals. The number-theoretic analysis that leads to many important properties of a digital circle succinctly captures the original perspectives of digital calculus and digital geometry for its visualization and characterization. To demonstrate the capability and efficacy of the proposed method, two simple algorithms for the construction of digital circles, based on simple number-theoretic concepts, have been reported. Both the algorithms require only a few primitive operations and are completely devoid of any floating-point computation. To speed up the computation, especially for circular arcs of high radii, a hybridized version of these two algorithms has been given. Experimental results have been furnished to elucidate the analytical power and algorithmic efficiency of the proposed approach. It has been also shown, how and why, for sufficiently high radius, the number-theoretic technique can expedite a circle construction algorithm.     

A Smoothing-Type Algorithm for Solving Linear Complementarity Problems with Strong Convergence Properties

In this paper, we construct an augmented system of the standard monotone linear complementarity problem (LCP), and establish the relations between the augmented system and the LCP. We present a smoothing-type algorithm for solving the augmented system. The algorithm is shown to be globally convergent without assuming any prior knowledge of feasibility/infeasibility of the problem. In particular, if the LCP has a solution, then the algorithm either generates a maximal complementary solution of the LCP or detects correctly solvability of the LCP, and in the latter case, an existing smoothing-type algorithm can be directly applied to solve the LCP without any additional assumption and it generates a maximal complementary solution of the LCP; and that if the LCP is infeasible, then the algorithm detect correctly infeasibility of the LCP. To the best of our knowledge, such properties have not appeared in the existing literature for smoothing-type algorithms. This work was partially supported by the National Natural Science Foundation of China (Grant No. 10571134), the Natural Science Foundation of Tianjin (Grant No. 07JCYBJC05200), and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.     

用基于空间平滑的正交化算法分离相干信号

正交化超分辨算法在大信噪比时性能优良且运算量小,但由于正交化算法是一种信号子空间方法,因而在干扰相干时失效,而空间平滑方法已广泛应用于自适应阵列相干信号的分离.文中提出了3种基于空间平滑的改进正交化算法并给出了计算机仿真结果.第1种方法具有较小的运算量,但当信噪比降低时,性能会严重下降.第2种和第3种方法在运算量增加不多的情况下性能比第1种方法有所改善,尤其是当信噪比较小时.理论分析和计算机仿真结果表明这3种方法是有效的.     

基于资源受限的软硬件划分方法

本文提出了一种在硬件资源受限的情况下进行软硬件划分的一种方法。以贪婪算法(greedy)作为划分的核心，并对所抽取的划分图进行结点的预先分类，减小贪婪算法探索的设计空间，加速算法的执行。通过反复地迭代，获得了最终的软硬件划分选择。实验证明，这种软硬件划分的方法具有高效率及高面积利用率的特点。     

粒子滤波算法中浮点指数函数的FPGA设计实现

浮点指数运算是粒子滤波算法中的关键运算之一,在信号处理等诸多领域有着十分重要的应用,通过分析Table-driven算法,给出基于Table-driven算法实现浮点指数运算的硬件结构,并以Verilog HDL进行建模仿真及综合,同时将仿真结果与浮点DSP C6701运算结果进行比较。结果表明基于FPGA的浮点指数运算在保持一定精度的条件下,可以获得更快的运算速度。     

The apolar bilinear form in geometric modeling

Some recent methods of Computer Aided Geometric Design are related to the apolar bilinear form, an inner product on the space of homogeneous multivariate polynomials of a fixed degree, already known in 19th century invariant theory. Using a generalized version of this inner product, we derive in a straightforward way some of the recent results in CAGD, like Marsden's identity, the expression for the de Boor-Fix functionals, and recursion schemes for the computation of B-patches and their derivatives.

     

半无限规划的一阶最优性条件和牛顿型算法

在Fischer-Burmeister非线性互补函数的基础上,得到了半无限规划问题的一个新的一阶必要条件,并将半无限规划问题转化成一个光滑的无约束优化问题,给出了适合该问题的一个Damp-Newton算法,数值例子表明:算法结构简单,数值计算有效.