考虑资源约束的复杂维修任务时间预计模型

在分析装备维修过程时间影响因素的基础上,研究了维修过程时间模型的建模要素关系。采用Petri网技术建立了反映子任务基本关系、资源约束和调度策略的典型维修过程模型,并对典型子任务执行过程进行了细化建模,研究了模型冲突和资源调度策略。针对典型实例进行了维修时间预计和资源利用率分析。     

具有时滞的比率型Chemostat模型的全局稳定性

研究一类具有时滞的比率型功能性反应的Chemostat模型。研究了模型的边界平衡点和正平衡点的局部稳定性以及Hopf分支的存在性;利用比较定理证明了边界平衡点的全局稳定性;通过构造Liapunov泛函给出了保证系统正平衡点全局稳定的充分条件;并通过数值模拟验证了理论结果。     

战术数据链网络设计优化方法

网络设计优化问题直接关系到战术数据链系统效能的发挥。在分析数据链系统中不同消息类别有不同系统响应时间要求的基础上,提出了一种新的网络设计优化方法。通过建立模型讨论了单个数据链轮询网络的轮询周期、网络成员容量、每个轮询周期内各成员的点名次数等因素间的数学关系。并以Link-11为例进行分析计算。结果表明,该分析方法有效可行,为解决战术数据链网络设计及优化问题提供了一种思路。     

Scheduling parallel machines with inclusive processing set restrictions

We consider the problem of assigning a set of jobs to different parallel machines of the same processing speed, where each job is compatible to only a subset of those machines. The machines can be linearly ordered such that a higher‐indexed machine can process all those jobs that a lower‐indexed machine can process. The objective is to minimize the makespan of the schedule. This problem is motivated by industrial applications such as cargo handling by cranes with nonidentical weight capacities, computer processor scheduling with memory constraints, and grades of service provision by parallel servers. We develop an efficient algorithm for this problem with a worst‐case performance ratio of + ε, where ε is a positive constant which may be set arbitrarily close to zero. We also present a polynomial time approximation scheme for this problem, which answers an open question in the literature. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Network design for time‐constrained delivery

To meet customer demand, delivery companies are offering an increasing number of time‐definite services. In this article, we examine the strategic design of delivery networks which can efficiently provide these services. Because of the high cost of direct connections, we focus on tree‐structured networks. As it may not be possible to identify a tree‐structured network that satisfies all of the delivery guarantees, we allow these guarantees to be violated but seek to minimize the sum of the violations. We establish the complexity of the problem and exploit an empirically identified solution structure to create new neighborhoods which improve solution values over more general neighborhood structures. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

靶场外测数据实时处理软件设计

根据靶场飞行试验任务需求,对外测数据实时处理软件所用到的测元参数、关键数学模型、算法、装订参数等进行了分析,综合运用了数据检择、滤波与平滑等技术,避免了＂台阶跳＂、＂死码＂等野值干扰,形成了实用、可靠的外测数据实时处理方法。软件设计采用多进程、多线程体系结构,合理地分解了系统的功能,建立了一套实时、高效、可靠的软件程序框架,并在该程序框架下设计了各软件功能模块。     

磁通门信号处理电路的数字化设计

针对目前某领域使用的磁通门传感器信号处理电路的一些缺点:如设备体积大、维护和升级困难、元件间容易出现感应和杂散效应等,提出了采用DSP的磁通门信号处理电路的数字化设计方案,给出了处理电路的硬件设计,并且对信号处理中的数字滤波进行了计算机模拟仿真。仿真结果表明,改造后的系统具有精度高、实时性好、升级方便等特点。     

A two‐echelon inventory‐location problem with service considerations

We study the problem of designing a two‐echelon spare parts inventory system consisting of a central plant and a number of service centers each serving a set of customers with stochastic demand. Processing and storage capacities at both levels of facilities are limited. The manufacturing process is modeled as a queuing system at the plant. The goal is to optimize the base‐stock levels at both echelons, the location of service centers, and the allocation of customers to centers simultaneously, subject to service constraints. A mixed integer nonlinear programming model (MINLP) is formulated to minimize the total expected cost of the system. The problem is NP‐hard and a Lagrangian heuristic is proposed. We present computational results and discuss the trade‐off between cost and service. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009     

To wait or not to wait: Optimal ordering under lead time uncertainty and forecast updating

There has been a dramatic increase over the past decade in the number of firms that source finished product from overseas. Although this has reduced procurement costs, it has increased supply risk; procurement lead times are longer and are often unreliable. In deciding when and how much to order, firms must consider the lead time risk and the demand risk, i.e., the accuracy of their demand forecast. To improve the accuracy of its demand forecast, a firm may update its forecast as the selling season approaches. In this article we consider both forecast updating and lead time uncertainty. We characterize the firm's optimal procurement policy, and we prove that, with multiplicative forecast revisions, the firm's optimal procurement time is independent of the demand forecast evolution but that the optimal procurement quantity is not. This leads to a number of important managerial insights into the firm's planning process. We show that the firm becomes less sensitive to lead time variability as the forecast updating process becomes more efficient. Interestingly, a forecast‐updating firm might procure earlier than a firm with no forecast updating. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

基于图像信息的跟踪算法分析

图像跟踪算法研究是电视跟踪系统的关键技术之一.对波门跟踪算法、相关跟踪算法、多模跟踪算法、基于提边的差分跟踪算法及微分线性拟合外推跟踪算法进行了分析,并指出了电视跟踪系统跟踪算法的发展趋势及其在武器系统中的重要作用.