装备寿命周期备件供应网络优化方法

针对现有备件供应优化方法未从寿命周期角度考虑备件供应优化问题,将寿命周期不同阶段的备件需求特征融入备件供应网络设计中,实施动态需求特征下的寿命周期整体优化。深入分析寿命周期不同阶段的备件需求特征;建立备件供应响应时间转移方程,在此基础上,构建使寿命周期备件保障效益最大的多目标混合整数规划模型。通过仿真案例证明了多种备件保障模式的组合能够显著提高寿命周期保障效益,寿命周期整体优化可以实施更高效的备件供应。     

Partitioning of biweighted trees

A districting problem is formulated as a network partitioning model where each link has one weight to denote travel time and another weight to denote workload. The objective of the problem is to minimize the maximum diameter of the districts while equalizing the workload among the districts. The case of tree networks is addressed and efficient algorithms are developed when the network is to be partitioned into two or three districts. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 143–158, 2002; DOI 10.1002/nav.10003     

多目标的分布式协同进化MDO算法

通过引入非优超排序和排挤的多目标处理机制 ,将分布式协同进化MDO算法的能力扩展到多目标的多学科设计优化问题。多目标的分布式协同进化MDO算法在保持各学科充分自治和各学科并行设计优化协同的基础上 ,通过一次运行即可获得具有良好分布的多个Pareto最优解 ,逼近整个Pareto最优前沿。应用于导弹气动 /发动机 /控制三学科两目标设计优化问题 ,与约束法计算结果的对比表明算法能够有效逼近该问题的Pareto最优前沿 ,为设计决策提供了丰富的信息     

稳态随机过程激励下基于首次超越破坏的结构优化设计

把结构系统动力可靠性分析与最优化设计结合起来 ,以结构系统的最小质量为目标函数 ,给出了考虑在平稳随机过程激励下多自由度线性系统总的可靠性的结构优化设计方法。运用谱分析理论 ,推导了结构系统在平稳随机过程激励下响应的统计特征 ,同时结合首次超越破坏的Possion模型计算结构系统的可靠性 ,最终采用广义乘子法得到结构系统设计变量的最优值。计算结果表明该方法是可行的     

Balancing a one‐way corridor capacity and safety‐oriented reliability: A stochastic optimization approach for metro train timetabling

In urban rail transit systems of large cities, the headway and following distance of successive trains have been compressed as much as possible to enhance the corridor capacity to satisfy extremely high passenger demand during peak hours. To prevent train collisions and ensure the safety of trains, a safe following distance of trains must be maintained. However, this requirement is subject to a series of complex factors, such as the uncertain train braking performance, train communication delay, and driver reaction time. In this paper, we propose a unified mathematical framework to analyze the safety‐oriented reliability of metro train timetables with different corridor capacities, that is, the train traffic density, and determine the most reliable train timetable for metro lines in an uncertain environment. By employing a space‐time network representation in the formulations, the reliability‐based train timetabling problem is formulated as a nonlinear stochastic programming model, in which we use 0‐1 variables to denote the time‐dependent velocity and position of all involved trains. Several reformulation techniques are developed to obtain an equivalent mixed integer programming model with quadratic constraints (MIQCP) that can be solved to optimality by some commercial solvers. To improve the computational efficiency of the MIQCP model, we develop a dual decomposition solution framework that decomposes the primal problem into several sets of subproblems by dualizing the coupling constraints across different samples. An exact dynamic programming combined with search space reduction strategies is also developed to solve the exact optimal solutions of these subproblems. Two sets of numerical experiments, which involve a relatively small‐scale case and a real‐world instance based on the operation data of the Beijing subway Changping Line are implemented to verify the effectiveness of the proposed approaches.     

加权模糊C均值聚类算法实现BDS三频组合观测值优选

在对BDS三频载波相位组合观测值进行误差分析的基础上,确定了优选载波相位线性组合系数的筛选标准。针对传统聚类算法在高维多频混合数据集分类中存在的不足,采用一种基于加权的模糊C均值聚类算法,通过对同一维度在不同簇上赋予不同的权重值,对传统遍历搜索法所获得的部分BDS三频载波相位组合观测值进行了优化分类选取,有效解决了传统全球导航卫星系统载波相位观测值选取方法效率低的问题,同时为多系统多频数据组合观测值系数的优化选取提供了一种新的思路。对分类结果进行分析,确定了各类组合观测量的适用范围,并结合实测数据,利用无几何层叠模糊度解算方法对优选组合进行了整周模糊度的解算,结果验证了该方法的可行性。     

辐射叶加载的短波宽带鞭状天线优化设计

提出一款具有多层辐射叶结构的新型鞭状天线,在10 m鞭状天线体上设置不同的辐射叶层数、半径、长度、分支数、仰角及其分布情况,研究其对天线辐射性能的影响,综合考虑选择一套最合适的辐射叶结构,并为天线进行双加载和宽带匹配网络的算法优化。仿真结果表明,与现有的普通宽带鞭状天线相比,增益和效率得到了普遍提高,在低频段增益最高提高了3 dB,效率最高提高了5%;在高频段增益最高提高了5 dB,效率最高提高了35%,方向图上翘也得到了一定的抑制,为改善现有的宽带鞭状天线提供一种新的结构设计方法。     

电磁发射系统以太网拓扑结构建模优化

拓扑结构优化模型是网络中的一类重要模型,可以有效地优化系统整体链路性能。针对电磁发射系统以太网拓扑结构中部分节点和链路的负载过大,一旦发生堵塞,将会影响网络中关键链路性能的问题,建立网络拓扑结构优化的多目标规划模型,并提出一套基于基因环操作的遗传算法对其进行求解,通过仿真得出最优的网络拓扑结构。根据仿真结果修改实际网络节点默认配置参数,结果显示该模型和算法能有效均衡负载,降低网络冲突率,且不需要改变电磁发射系统以太网的物理链路,不会增加额外成本,对电磁发射类系统具有普适性的意义。     

C2组织鲁棒性信息交互结构设计及分析

介绍了C2组织的信息交互结构及其设计约束,讨论了C2组织鲁棒性信息交互结构的设计问题。提出了基于启发式嵌套遗传算法的鲁棒性信息交互结构设计方法:外层遗传算法对信息交互结构的拓扑及链路容量进行优化搜索;内层嵌套遗传算法依据对路由的搜索优化出多个使命邻域下最小延时集合,将其依概率平均化后返回外层来对链路容量的鲁棒性进行评价。案例分析和对比试验表明该方法可以实现鲁棒性较强的组织信息交互结构。     

Adaptive random search for continuous simulation optimization

We present, analyze, and compare three random search methods for solving stochastic optimization problems with uncountable feasible regions. Our adaptive search with resampling (ASR) approach is a framework for designing provably convergent algorithms that are adaptive and may consequently involve local search. The deterministic and stochastic shrinking ball (DSB and SSB) approaches are also convergent, but they are based on pure random search with the only difference being the estimator of the optimal solution [the DSB method was originally proposed and analyzed by Baumert and Smith]. The three methods use different techniques to reduce the effects of noise in the estimated objective function values. Our ASR method achieves this goal through resampling of already sampled points, whereas the DSB and SSB approaches address it by averaging observations in balls that shrink with time. We present conditions under which the three methods are convergent, both in probability and almost surely, and provide a limited computational study aimed at comparing the methods. Although further investigation is needed, our numerical results suggest that the ASR approach is promising, especially for difficult problems where the probability of identifying good solutions using pure random search is small. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010