A PURCHASING DECISION： SELECTING A SUPPLIER FOR A CONSTRUCTION COMPANY

1. Introduction Since the purchasing function has become vital in determining the profitability and survival of business organizations, it has been receiving considerable attention. As Sarkis and Talluri (2002) indicated, buyer-supplier relationships based solely on price are no longer acceptable. The increasing importance of supplier selection decisions is forcing organizations to rethink their purchasing and evaluation strategies because a successful purchasing decision directly depends on …     

A 2－FACTORIZATION ORTHOGONAL TO A STAR IN A GRAPH

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A NECESSARY AND SUFFICIENT CONDITION FOR A POINT TO BE A GLOBAL MAXIMIZER OF A CONSTRAINED OPTIMIZATION

It is difficult to judge whether a given point is a global maximizer of an unconstrained optimization problem. This paper deals with this problem by considering global information via integral and gives a necessary and sufficient condition judging whether a given point is a global maximizer of an unconstrained optimization problem. An algorithm is offered under such a condition and finally two test problems are verified via the offered algorithm.     

A MUCLTI-PARAMETER SPLITTING EXTRAPOLATION AND A PARALLEL ALGORITHM

1.IntroductionConsidertheone-dimensionalDirichletproblemwherethecoefficientsoftheproblemaresmoothandsatisfyp(x)2c>0,q(x)30,xE(0,1).Let[0,1]bedividedintopsubintervalsT={(aj--1,aj):j=1,2,'',p},ac=0,ap--1.Oneach(aj--1)aj),auniformmeshrefinementwithsizehiisi…     

A k-HAMILTON-NICE SEQUENCE

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COURSE TIMETABLING AT A TUNISIAN UNIVERSITY： A CASE STUDY

This paper deals with the Course Timetabling Problem at an institution in a Tunisian University. We introduce a heuristic procedure to construct a feasible timetable for all lectures and tutorials taken by different groups of each sub-section of any section. We describe the timetabling problem using a list of all specific hard and soft constraints. We formulate the problem as a set of linear constraints using two sets of binary variables corresponding to lectures and tutorials, respectively. This heuristic is illustrated with real data for a sub-section of the Faculty of Economics and Management Sciences of Sfax in Tunisia, and the resulting timetables are compared with those generated manually. The results of another full section have confirmed the good quality of the proposed heuristic when compared with the hand made solution.     

A ROBUST DECOMPOSITION OF LINEAR PROGRAMMING USING A GOAL-PARTITIONING METHOD

The Dantzig/Wolfe linear programming decomposition algorithm has had important economicinterpretations as well as a widespread impact on solving large scale linear programming problem.Inthis paper we consider a similar underlying structure,where however there is only one couplinginequality or equation.With this simplification,we demonstrate how to achieve an equitable partitionof the overall coupling resource to individual subproblem constraints through a simple iterationprocedure which appears to be very efficient.     

CORRECTED PROOF OF A THEOREM CONCERNING A CONJECTURE OF SINGH

A theorem concerning a conjecture of Singh is formulated in[2].But the argumentin [2] contains a serious gap which is in fact the essential point of the proof.A correct proofis presented here.     

OBSERVING THE HEAT EQUATION ON A TORUS ALONG A DENSE GEODESIC

Several authors have considered observability problems for the heat equation and relatedpartial differential equations.A basic problem is to determine what kinds of sampling providesufficient information to uniquely determine the initial heat distribntion.We address the case wherethe temperature is measured while travelling along a curve.We consider the special case where the space is a flat torus(of arbitrary dimension)and thecurve is a geodesic.It is shown that,in this case,the observed temperature is sufficient informationto uniquely determine the initial heat distribution if and only if the geodesic is dense in the torus.In the case of a torus,Fourier analysis techniques can be used to write down the solution of theheat equation.This allows us to derive an explicit representation of the observed temperature interms of the initial distribution.We use this representation and some ideas from the theory ofalmost periodic functions to show that the Fourier coefficients of the initial distribution can berecovered from the observation.     

A Problem in Combinatorics

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A NEW HIERARCHY OF LAX AND LIOUVILLE INTEGRABLE EVOLUTION EQUATIONS ASSOCIATED WITH AN ISOSPECTRAL PROBLEM IN THE LOOP ALGEBRA■

In this paper,an isospectral problem with five potentials is investigated in loop algebra A_2such that a new hierarchy of evolution equations with five arbitrary functions is obtained.And then byfixing the five arbitrary functions to be certain functions and using the trace identity,the generalizedHamiltonian structure of the hierarchy of evolution equations is given.It is shown that this hierarchyof equations is Liouville integrable.Finally some special cases of the isospectral problem are also given.     

FRACTIONAL ORDER EVOLUTION EQUATIONINTERPOLATING BOTH HEAT AND WAVE EQUATION

1.IntroductionInthispaperweconsidertheCauchyproblemforthefollowingintegrodifferentialequationHerewedenotebyrtheGammafunction,byb(t)theDiracfunction.Equation(1.1)describestheheatconductionwithmemory12'3'4].Wesaythatacolltinuousfunction*Thisresearchissuppor…     

Fractal Solitons,Arbitrary Function Solutions,Exact Periodic Wave and Breathers for a Nonlinear Partial Differential Equation by Using Bilinear Neural Network Method

This paper extends a method, called bilinear neural network method(BNNM), to solve exact solutions to nonlinear partial differential equation. New, test functions are constructed by using this method. These test functions are composed of specific activation functions of single-layer model,specific activation functions of "2-2" model and arbitrary functions of "2-2-3" model. By means of the BNNM, nineteen sets of exact analytical solutions and twenty-four arbitrary function solutions of the dimensionally reduced p-gB KP equation are obtained via symbolic computation with the help of Maple. The fractal solitons waves are obtained by choosing appropriate values and the self-similar characteristics of these waves are observed by reducing the observation range and amplifying the partial picture. By giving a specific activation function in the single layer neural network model, exact periodic waves and breathers are obtained. Via various three-dimensional plots, contour plots and density plots,the evolution characteristic of these waves are exhibited.     

坡面水蚀与细沟发育过程模拟研究

为了分析次降雨过程中的细沟发育规律,提出从二维浅水方程和泥沙输移方程出发建立坡面水蚀模型,利用有限体积法模拟坡面径流与侵蚀产沙的时空分布及微地貌发育过程的方法。模型由二维浅水方程、Green-Ampt入渗模型、Gash林冠截留模型以及经验侵蚀与沉积公式组成,具有易于实现的优点。通过对摩阻源项进行点隐式处理,提高了数值稳定性,可处理干床面和微小水深。结果表明,模型能够模拟复杂坡面在次降雨过程中的径流侵蚀及细沟发育规律。     

复杂虚拟环境下的实时碰撞检测算法

提出了一种共享存储系统的并行碰撞检测算法。利用AABB包围盒的优点来构建任意物体的混合包围盒层次,利用并行模型来并行遍历混合包围盒层次,进一步加速碰撞检测算法。实验结果表明,与现有的经典算法相比,该算法在效率、精确性方面具有明显优势,能够满足交互式复杂虚拟环境的实时性和精确性的要求。     

基于核密度估计的层次聚类算法

聚类分析是统计、模式识别和数据挖掘等领域中一个非常基础且非常重要的研究课题，具有广泛的应用前景。在众多的聚类方法中，基于密度的方法是一种相当有效的聚类方法，能够发现任意形状的聚类，对噪声数据不敏感，但是聚类结果严重依赖于用户参数的合理选择。以DENCLUE算法为基础，一种基于核密度估计的层次聚类算法被提出，该算法首先优选窗宽σ产生较好的核密度估计结果，然后以密度函数的局部极大值点为聚类中心形成数据的初始划分，最后根据密度函数的鞍点递归合并初始聚类产生不同层次的划分模式。理论分析和仿真实验结果显示，该算法能够发现任意形状、大小和密度的聚类，能够有效处理噪声数据，而且聚类结果不依赖于用户参数的仔细选择。     

三维空间中圆锥、圆柱和平面交线的绘制

在三维空间中,要绘出任意圆锥、圆柱和任意平面的交线,一般先选取适当坐标系,得到交线的标准型方程,绘出后,再经过一组坐标变换,显示在当前屏幕上。本文通过分析圆柱、圆锥和平面的几何关系,推导出它们的交线的显式表示,从而给出在三维空间中直接绘制这类交线的方法。     

ANTI-PERIODIC SOLUTIONS FOR FIRST AND SECOND ORDER NONLINEAR EVOLUTION EQUATIONS IN BANACH SPACES

In this paper, a new existence theorem of anti-periodic solutions for a class ofstrongly nonlinear evolution equations in Banach spaces is presented. The equations con-tain nonlinear monotone operators and a nonmonotone perturbation. Moreover, throughan appropriate transformation, the existence of anti-periodic solutions for a class of second-order nonlinear evolution equations is verified. Our abstract results are illustrated by anexample from quasi-linear partial differential equations with time anti-periodic conditionsand an example from quasi-linear anti-periodic hyperbolic differential equations.     

层次分析法在水资源工程环境影响评价中的应用

水资源工程环境影响评价是由众多指标组成层次结构的复杂系统,其关键问题是如何合理确定各评价指标的权重。为此,探讨了把层次分析法(AHP)作为确定指标权重的实现过程,并提出用加速遗传算法(AGA)修正判断矩阵的一致性,且同时计算判断矩阵各要素的排序权值的新方法(AGA-CAHP)。研究结果表明,AGA-CAHP方法直观、简便,计算结果稳定、精度高,在工程项目环境影响评价中具有推广应用价值。