带约束集合划分优化问题及其求解

文章介绍了一类带约束的集合划分优化问题,给出了这个一般问题的几个具体应用．提出了用遗传算法解决这类问题的一般方法,并针对其中的“处理机分配问题”设计了具体的算法。数值仿真实验结果表明,该算法比传统的启发式算法效果更好。     

计算机网络安全问题的解决途径

计算机网络得到日益广泛的应用,其重要性日益突出,同时,也面临着各种各样的安全威胁,危害网络用户的个人隐私及财产安全等。深入分析当前计算机网络所面临的安全问题,并制定相应的解决策略,对于提升计算机网络的应用安全程度具有十分重要的意义。笔者结合自身实际工作经验,探讨计算机网络所面对的安全问题以及相应的解决途径。     

Optimal Strategies of the Iterated Prisoner's Dilemma Problem for Multiple Conflicting Objectives

In this paper, we present a new paradigm of searching optimal strategies in the game of iterated prisoner's dilemma (IPD) using multiple-objective evolutionary algorithms. This method is more useful than the existing approaches, because it not only produces strategies that perform better in the iterated game but also finds a family of nondominated strategies, which can be analyzed to decipher properties a strategy should have to win the game in a more satisfactory manner. We present the results obtained by this new method and discuss sub-strategies found to be common among nondominated strategies. The multiobjective treatment of the IPD problem demonstrated here can be applied to other similar game-playing tasks.      

浅谈学校计算机网络常见故障及解决办法

随着社会的发展,计算机网络早已经进入了我们生活工作的方方面面,一旦计算机网络发生故障,对我们的工作和生活都会带来不同程度的影响.所以及时发现计算机网络的故障并做好修复处理的工作,保证网络的安全运行,就显得格外重要.本文对计算机网络的基本概念和常见的故障和解决的办法进行了详细的分析.     

A Market-based Solution to the Multiple Traveling Salesmen Problem

This paper describes a market-based solution to the problem of assigning mobile agents to tasks. The problem is formulated as the multiple depots, multiple traveling salesmen problem (MTSP), where agents and tasks operate in a market to achieve near-optimal solutions. We consider both the classical MTSP, in which the sum of all tour lengths is minimized, and the Min-Max MTSP, in which the longest tour is minimized. We compare the market-based solution with direct enumeration in small scenarios, and show that the results are nearly optimal. For the classical MTSP, we compare our results to linear programming, and show that the results are within 1 % of the best cost found by linear programming in more than 90 % of the runs, with a significant reduction in runtime. For the Min-Max case, we compare our method with Carlsson’s algorithm and show an improvement of 5 % to 40 % in cost, albeit at an increase in runtime. Finally, we demonstrate the ability of the market-based solution to deal with changes in the scenario, e.g., agents leaving and entering the market. We show that the market paradigm is ideal for dealing with these changes during runtime, without the need to restart the algorithm, and that the solution reacts to the new scenarios in a quick and near-optimal way.     

Modeling Mode and Route Similarities in Network Equilibrium Problem with Go-Green Modes

Environmental sustainability is a common requirement on the development of various real-world systems, especially on road transportation systems. Motorized vehicles generate a large amount of harmful emissions, which have adverse effects to the environment and human health. Environmental sustainability requires more promotions of ‘go-green’ transportation modes such as public transit and bicycle to realize the increasing travel demands while keeping the environmental expenses low. In this paper, we make use of recent advances in discrete choice modeling to develop equivalent mathematical programming formulations for the combined modal split and traffic assignment (CMSTA) problem that explicitly considers mode and route similarities under congested networks. Specifically, a nested logit model is adopted to model the modal split problem by accounting for mode similarity among the available modes, and a cross-nested logit model is used to account for route overlapping in the traffic assignment problem. This new CMSTA model has the potential to enhance the behavioral modeling of travelers’ mode shift between private motorized mode and ‘go-green’ modes as well as their mode-specific route choices, and to assist in quantitatively evaluating the effectiveness of different ‘go-green’ promotion policies.     

基于遗传算法的多人旅行商问题求解

旅行商问题是一个经典的XP完全问题,多人旅行商问题的求解则更具挑战性。以往对求解多人旅行商问题的研究局限于以所有成员路径总和最小为优化标准,面对以所有成员路径最大值最小为优化标准的另一类多人旅行商问题却未加注意。文章给出了这两类多人旅行商问题的形式化描述,探讨了利用遗传算法求解这两类多人旅行商问题的基本思想和具体方案,进行了仿真实验验证。仿真实验数据表明,这是一种高效而且适应性强的多人旅行商问题求解方法。     

多出口多寻址模式的网络设计

针对多出口园区网设计问题，将多出口网络中的用户归纳为单向寻址、双向寻址、部分双向寻址3种模式，提出了集中式、分布式、基于寻址模式的分布式路由控制模型，在实例中分析了合法IP与私有IP的共存方式和物理分叉结构替代路由逻辑的实现方法。为多出口园区网络设计提供了通用的参考模型。     

IP网络多组播流相互影响均衡问题研究

自从20世纪90年代初IP组播概念及试验网络出现以后,IP组播路由一直是互联网路由领域的研究热点,由于互联网规模的急速扩张带来的网络阻塞问题必须在新一代网络中得到较好解决.本文针对动态组播路由条件下多组播流相互影响问题展开研究,建立了多组播流优化均衡模型,并证明模型在总费用的最优解不但存在,而且唯一.简单的算例表明:相对静态组播路由,动态组播路由对网络性能有明显改善,为新一代网络和路由提供算法参考,并扩展到更加复杂网络的路由均衡研究.下一步将在典型的路由设备和具备一定规模的网络上进行验证和应用.     

谈无线局域网的安全问题及解决方法

随着无线技术和网络技术的发展,无线网络正成为应用热点,然而随着黑客技术的提高,无线局域网(WLAN)受到越来越多的威胁.文中阐述了无线网络信息安全技术的特点,并针对该特点剖析了无线局域网中出现的安全问题及相应解决方法.     

Iterative Solution of the Quasicontinuum Equilibrium Equations with Continuation

We give an analysis of a continuation algorithm for the numerical solution of the force-based quasicontinuum equations. The approximate solution of the force-based quasicontinuum equations is computed by an iterative method using an energy-based quasicontinuum approximation as the preconditioner. The analysis presented in this paper is used to determine an efficient strategy for the parameter step size and number of iterations at each parameter value to achieve a solution to a required tolerance. We present computational results for the deformation of a Lennard-Jones chain under tension to demonstrate the necessity of carefully applying continuation to ensure that the computed solution remains in the domain of convergence of the iterative method as the parameter is increased. These results exhibit fracture before the actual load limit if the parameter step size is too large. This work was supported in part by DMS-0304326, by the University of Minnesota Supercomputing Institute and by the Department of Energy under Award Number DE-FG02-05ER25706.     

The Feedback Arc Set Problem with Triangle Inequality Is a Vertex Cover Problem

We consider the (precedence constrained) Minimum Feedback Arc Set problem with triangle inequalities on the weights, which finds important applications in problems of ranking with inconsistent information. We present a surprising structural insight showing that the problem is a special case of the minimum vertex cover in hypergraphs with edges of size at most 3.     

Abductive Explanation-Based Learning: A Solution to the Multiple Inconsistent Explanation Problem

One problem which frequently surfaces when applying explanation-based learning (EBL) to imperfect theories is themultiple inconsistent explanation problem. The multiple inconsistent explanation problem occurs when a domain theory produces multiple explanations for a training instance, only some of which are correct. Domain theories which suffer from the multiple inconsistent explanation problem can occur in many different contexts, such as when some information is missing and must be assumed: since such assumptions can be incorrect, incorrect explanations can be constructed. This paper proposes an extension of explanation-based learning, calledabductive explanation-based learning (A-EBL) which solves the multiple inconsistent explanation problem by using set covering techniques and negative examples to choose among the possible explanations of a training example. It is shown by formal analysis that A-EBL has convergence properties that are only logarithmically worse than EBL/TS, a formalization of a certain type of knowledge-level EBL; A-EBL is also proven to be computationally efficient, assuming that the domain theory is tractable. Finally, experimental results are reported on an application of A-EBL to learning correct rules for opening bids in the game of contract bridge given examples and an imperfect domain theory.     

网络制造系统网络结构设计解决方案研究

本文概述网络制造内容,分析其对网络结构设计的要求,经过分析对比,提出企业局域网、广域网解决方案,并给出一应用实例。     

基于GSO算法的最小连通支配集问题求解

经典的最小连通支配集(MCDS)计算是NP难问题。为此,提出一种利用萤火虫优化算法求解该难题的新方法。把网络中的每个节点当作一个萤火虫个体,以节点度为基础构成荧光素,通过概率选择和荧光素调节机制,使个体被吸引向邻接的高亮度个体,从而由所选出的个体组成网络的支配集。经连接和修剪处理后,得到MCDS的近似解。在无线传感器网络模型的单位圆盘图上进行模拟实验,结果表明,该算法得到的连通支配集规模较小,更接近集中式算法的结果。     

一种带约束的多目标服务质量路由算法

多约束服务质量(QoS)路由是要求在多个约束条件下计算满足所有独立限制条件的可行路径．将这种NPC问题转化为一种带约束条件的多目标优化问题,根据多目标遗传算法的智能优化原理,提出一种多目标QoS路由算法来产生一组最优非劣路由．理论分析和实验结果表明,使用带约束的多目标遗传算法是解决多约束QoS路由的有效途径,能对提高网络性能起到重要作用．     

Neural Network Solution for Forward Kinematics Problem of Cable Robots

Forward kinematics problem of cable robots is very difficult to solve the same as that of parallel robots and in the contrary to the serial manipulators’. This problem is almost impossible to solve analytically because of the nonlinearity and complexity of the robot’s kinematic equations. Numerical methods are the most common solutions for this problem of the parallel and cable robots. But, convergency of these methods is the drawback of using them. In this paper, neural network approach is used to solve the forward kinematics problem of an exemplary 3D cable robot. This problem is solved in the typical workspace of the robot. The neural network used in this paper is of the MLP type and a back propagation procedure is utilized to train the network. A simulation study is performed and the results show the advantages of this method in enhancement of convergency together with very small modeling errors.     

基于校园网的多机房管理系统的解决方案

利用现有的校园网络，通过软件实现对校园内多机房进行集中管理，统一计费，并做到实时查询。     

Doyle-Stein问题的鲁棒解*

本文用μ综合法对早期Ｈ∞文献中提出的一个具有输入不确定性的病态对象进行了鲁棒设计，给出了该例题的一个鲁棒解，进一步说明Ｈ∞／μ理论是鲁棒设计的有力工具，也为其它设计方法提供了一个可与之进行比较的结果。     

网络最大流求解算法的研究

近年来,随着各种网络的飞速发展,对最大流问题的研究也取得了很大的进展。文章简述了网络最大流问题的现状,提出了一种求解网络最大流与最小截问题的算法。此算法使得计算网络最大流变得简便,且具有很强的实用性。