一类平面微分系统的定性分析

本文利用微分方程对称法、形式级数和旋转向量场理论,对平面微分系统ｄｘ／ｄｔ＝－ｙ＋δｘ＋ａｘｙ＋ｂｘ＾２Ｆ（ｘ）,ｄｙ／ｄｔ＝Ｇ（ｘ）进行了全面分析,得出了较完整的定性分析结果。     

一类两种群竞争离散系统的持久性

讨论了密度制约的两种群竞争离散系统{x（n＋1）=x（n）exp｜r1-a1x（n）-b1y（n）｜ y（n＋1）=y9n）exp｜r2-a2x（n）-b2y（n）｜的初值解的有界性及系统的持久性。通过适当构造解的最终有界区域，证明了当b1/b2〈r1/r2/〈a1/a2时，系统是强持续生存的。这里ri,ai，bi（i=1，2）均为正的常数。     

CBM＋：航空维修保障新趋势

增强型基于状态的维修（CBM＋）是美国军方于本世纪初开始大力推行的一种维修方式，作为一种主动维修形式，它是航空维修的重要发展方向之一。文章通过详细介绍CBM＋方案，着重分析了CBM＋的关键技术及其对航空维修保障工作的影响，最后总结出CBM＋的应用趋势。     

强非线性系统响应的研究

讨论了如下形式ｕ＋２εηｕ＋ｕ＋ｕε＝２εｈｃｏｓ（ｔ）的强 ｄｕｆｆｉｎｇ系统,式中ｕ上方的圆点表示对时间ｔ的导数,η为系统阻尼系,ε不要求是一个小量。对系统进行了变换,用多尺度法求得了系统的二次近似解,分析了稳定性。     

线性分式规划原始单纯形算法有限性问题

本文用一个数值例子说明用[1] 和[2] 中的原始单纯形算法求解退化的线性分式规划(LFP) 可能会出现基循环,从而得不到最优解。于是就此情形引入了Bland规则,并建立了有限性算法。     

潜伏在深海的法兰西“神箭”——法国M51型潜射弹道导弹综述

M51型潜射弹道导弹是由法l国“欧洲航空航天防务系统”（EADS）公司制造的一种三级固体远程弹道导弹。长12米，弹径2．3米，发射重量48吨，比M45型潜射导弹重近50％，采用惯性制导方式。     

基于SAQ＋B消防模拟训练系统评估方法设计

采用专家打分法、AHP法和Matlab软件相结合，引入“处理时间”作为评估因素的方法，对基于“SAQ＋B”消防模拟训练系统的评估方法进行了系统地介绍，并计算了各级训练指标的权值。     

简约而不简单 美国“迷你追风”狙击步枪

美国EDM公司生产的M96“追风”狙击步枪是一种优秀的大口径远程反器材武器，它使用12．7毫米口径子弹，能远程摧毁包括轻装甲车在内的多种目标。不过，受美国国内法律限制，大口径狙击枪在多个州均不得向平民出售。所以，以M96为基础研发小口径狙击步枪就成为最好的选择。这不，美国复仇者武器公司就拿出了他的主打产品——“迷你追风”狙击步枪。     

俄总设计师揭苏-35S发展秘辛

日前,俄国防部机关报《红星报》采访了苏－35S歼击机总设计师伊格尔-德明,首度披露这款“4＋＋”代战机的发展历程、设计思想转变,以及上世纪80年代惊鸿一瞥的三翼面苏－35（最初称苏－27M）、苏－30MK和今天苏－35S之间的血缘关系。     

活性炭纤维负载TiO2的光催化性能

以水玻璃为粘结剂，活性炭纤维为载体，采用涂覆法制备出负载型TiO2／ACF光催化剂，考察了不同处理工艺条件下（UV，UV＋ACF，UV＋TiO2／ACF）TNT溶液的光催化降解率，同时探讨了初始质量浓度、TiO2负载量及光照强度等因素对TNT溶液去除率的影响。结果表明，利用涂覆法可以将TiO2很好地负载到活性炭纤维表面，在光照2h条件下，TiO2／ACF光催化剂对TNT溶液的降解率可达90．4％。     

A comparison of the primal-simplex and complementary pivot methods for linear programming

A comparison of the complementary pivot method of Lemke-Howson and the more commonly used primal-simplex method for solving linear programming problems in symmetric dual form has been made. In our tests the complementary pivot method shows a definite superiority over the simplex method both with regard to the number of iterations and computation time.     

目标规划的求解

目标规划的求解可采用图示法、单纯形法、分级法等,文中用Excel演示单纯形法和分级法。     

The simplex method for integral multicommodity networks

The simplex method is interpreted as a labeling procedure for certain classes of multicommodity flow problems in a manner similar to that for single commodity networks. As opposed to general multicommodity algorithms, no explicit matrix inversion is required; all simplex operations are performed graph-theoretically.     

An approximative algorithm for the fixed charge problem

This paper describes an approximate solution method for solving the fixed charge problem. This heuristic approach is applied to a set of test problems to explore the margin of error. The results indicate that the proposed fixed charge simplex algorithm is capable of finding optimal or near optimal solutions to moderate sized fixed charge problems. In the absence of an exact method, this heuristic should prove useful in solving this fundamental nonlinear programming problem.     

A primal simplex algorithm to solve a rectilinear distance facility location problem

This paper considers the problem of locating m new facilities in the plane so as to minimize a weighted rectangular distance between the new facilities and n existing facilities. A special purpose primal simplex algorithm is developed to solve this problem. The algorithm will maintain at all times a basis of dimension m by m; however, because of the triangularity of the basis matrix, it will not be necessary to form a basis inverse explicitly.     

伺服系统直流调速系统的改进型内模PD-I控制方法

为提高直流调速系统的控制性能,提出了一种改进型内模PD-I控制器的设计方法。根据直流电机的运行原理,建立了电机输出转速与输入电压变化率之间的数学模型,基于内模控制(Internal Model Control,IMC)原理和Taylor级数展开,设计了一种内模PD控制器,且可通过选择系统的截止频率实现控制器参数的整定。为了获得系统调节所需的控制作用,可将内模PD控制器与积分环节相串联构成改进型内模PD-I控制器,仿真和实验结果表明本方法可使系统获得更好的控制性能。     

An M/M/1 queue with a general bulk service rule

A model of an M/M/1, bulk queue with service rates dependent on the batch size is developed. The operational policy is to commence service when at least L customers are available with a maximum batch size of K. Arriving customers are not allowed to join in-process service. The solution procedure utilizes the matrix geometric methodology and reduces to obtaining the inverse of a square matrix of dimension K + 1 - L. For the case where the service rates are not batch size dependent, the limiting probabilities can be written in closed form. A numerical example illustrates the variability of the system cost as a function of the minimum batch service size L.     

A forward network simplex algorithm for solving multiperiod network flow problems

An optimization model which is frequently used to assist decision makers in the areas of resource scheduling, planning, and distribution is the minimum cost multiperiod network flow problem. This model describes network structure decision-making problems over time. Such problems arise in the areas of production/distribution systems, economic planning, communication systems, material handling systems, traffic systems, railway systems, building evacuation systems, energy systems, as well as in many others. Although existing network solution techniques are efficient, there are still limitations to the size of problems that can be solved. To date, only a few researchers have taken the multiperiod structure into consideration in devising efficient solution methods. Standard network codes are usually used because of their availability and perceived efficiency. In this paper we discuss the development, implementation, and computational testing of a new technique, the forward network simplex method, for solving linear, minimum cost, multiperiod network flow problems. The forward network simplex method is a forward algorithm which exploits the natural decomposition of multiperiod network problems by limiting its pivoting activity. A forward algorithm is an approach to solving dynamic problems by solving successively longer finite subproblems, terminating when a stopping rule can be invoked or a decision horizon found. Such procedures are available for a large number of special structure models. Here we describe the specialization of the forward simplex method of Aronson, Morton, and Thompson to solving multiperiod network network flow problems. Computational results indicate that both the solution time and pivot count are linear in the number of periods. For standard network optimization codes, which do not exploit the multiperiod structure, the pivot count is linear in the number of periods; however, the solution time is quadratic.     

Computing bounds for the optimal value in linear programming

Consider a standard linear programming problem and suppose that there are bounds available for the decision variables such that those bounds are not violated at an optimal solution of the problem (but they may be violated at some other feasible solutions of the problem). Thus, these bounds may not appear explicitly in the problem, but rather they may have been derived from some prior knowledge about an optimal solution or from the explicit constraints of the problem. In this paper, the bounds on variables are used to compute bounds on the optimal value when the problem is being solved by the simplex method. The latter bounds may then be used as a termination criteria for the simples iterations for the purpose of finding a “sufficiently good” near optimal solution. The bounds proposed are such that the computational effort in evaluating them is insignificant compared to that involved in the simplex iterations. A numerical example is given to demonstrate their performance.     

多传感器任务分派的快速启发式规划新算法

在多目标多传感器管理中经常采用的线性规划算法中,随着传感器个数和目标个数的增加,计算量会爆炸式增长,使得跟踪系统不能实时计算,为此,根据传感器管理中线性规划的特点,提出了一种快速启发式算法,考虑组合中的传感器个数将组合的分配效用转化为权重,递推分配权重最大的组合,逐步减小组合和目标的个数.证明了权重最大的组合分派能实现组合中的传感器的最大效用.仿真结果表明该算法在与采用线性规划方法的跟踪精度相当的情况下,能有效地减小计算量.