A componentwise index of service measurement in multi‐component systems

In this paper we present a componentwise delay measure for estimating and improving the expected delays experienced by customers in a multi‐component inventory/assembly system. We show that this measure is easily computed. Further, in an environment where the performance of each of the item delays could be improved with investment, we present a solution that aims to minimize this measure and, in effect, minimizes the average waiting time experienced by customers. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 50: 2003     

A parallel machine replacement model

This paper considers a finite horizon parallel machine replacement problem where a fixed number of machines is in operation at all times. The operating cost for a machine goes up as the machine gets older. An older machine may have to be replaced by a new one when its operating cost becomes too high. There is a fixed order cost associated with the purchase of new machines. Machine purchase prices and salvage values may depend on the period in which they were purchased. The objective is to find a replacement plan that minimizes the total discounted cost over the problem horizon. We believe that the costs in our model are more commonly observed in practice than those previously used in the literature. The paper develops properties of optimal solutions and an efficient forward‐time algorithm to find an optimal replacement plan. A dominance property is developed that further limits the options to be considered, and a simple forecast horizon result is also presented. Future research possibilities are mentioned. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 275–287, 2002; Published online in Wiley InterScience (http://www.interscience.wiley.com). DOI 10.1002/nav.10012     

运用跑道平面结构化线特征的固定翼无人机视觉导航算法

针对固定翼无人机在着陆阶段的位姿估计的问题,提出运用跑道平面结构化线特征的无人机视觉导航算法。利用单台固连在无人机上的前视相机对跑道区域进行成像,自动提取结构化线特征。在无人机降落前期利用完整的结构化线特征配置解算出无人机的六自由度位姿参数(偏航角、俯仰角、滚转角、纵向位置、横向位置、高度),并在无人机降落到较低高度时,利用退化的结构化线特征(跑道边缘)解算出无人机的关键位姿参数(偏航角、俯仰角、横向位置、高度)。三维实景仿真实验证明,在距离机场200 m处,无人机的距离参数精度小于0.5 m,角度参数精度小于0.1°。     

A model of supply-chain decisions for resource sharing with an application to ventilator allocation to combat COVID-19

We present a stochastic optimization model for allocating and sharing a critical resource in the case of a pandemic. The demand for different entities peaks at different times, and an initial inventory for a central agency are to be allocated. The entities (states) may share the critical resource with a different state under a risk-averse condition. The model is applied to study the allocation of ventilator inventory in the COVID-19 pandemic by FEMA to different U.S. states. Findings suggest that if less than 60% of the ventilator inventory is available for non-COVID-19 patients, FEMA's stockpile of 20 000 ventilators (as of March 23, 2020) would be nearly adequate to meet the projected needs in slightly above average demand scenarios. However, when more than 75% of the available ventilator inventory must be reserved for non-COVID-19 patients, various degrees of shortfall are expected. In a severe case, where the demand is concentrated in the top-most quartile of the forecast confidence interval and states are not willing to share their stockpile of ventilators, the total shortfall over the planning horizon (until May 31, 2020) is about 232 000 ventilator days, with a peak shortfall of 17 200 ventilators on April 19, 2020. Results are also reported for a worst-case where the demand is at the upper limit of the 95% confidence interval. An important finding of this study is that a central agency (FEMA) can act as a coordinator for sharing critical resources that are in short supply over time to add efficiency in the system. Moreover, through properly managing risk-aversion of different entities (states) additional efficiency can be gained. An additional implication is that ramping up production early in the planning cycle allows to reduce shortfall significantly. An optimal timing of this production ramp-up consideration can be based on a cost-benefit analysis.     

基于熵权理想解法的炮兵C~4ISR系统效能评估

炮兵C4ISR系统的效能评估是我军信息化联合作战效能评估的重要研究内容.依据系统效能评估的需要,结合我军炮兵C4ISR系统的实际情况,提出了确立评价指标的3个重要原则,建立了炮兵C4ISR系统效能评价的指标体系,讨论了熵权理想解法的基本思想和主要步骤,并给出了炮兵指挥系统的评估案例.通过MATLAB编程实现,得到了各评价系统的优劣,速度快,精度高,弱化了主观因素,使得评价更令人信服,以便指导部队的日常训练和考核.     

基于单片机的远程光纤通信在点对点安全验证系统上的应用

现有的点对点安全验证系统都是基于电缆连接实现系统信息传输的。电缆传输信号存在传输衰减大、抗干扰能力差、在雷暴天气易发生事故等缺点。通过将基于单片机89C2051的远程光纤通信应用到现有设备来改进控制信号的传输模式，将电信号转换为光信号，在数据传输中使用传输同步码加密、数据包CRC校验、串行数据编码以及光纤连通性定时自动监测等技术，可以从物理信号传输到数据接收处理的整个过程中保证系统的安全性和可靠性；同时，通过光纤通信方案，也能节省系统构建和维护的经费。     

基于一类弱连续T-模的模糊Hopfield神经网络研究

基于一般的弱连续T-模与取大（V）模糊算子的复合，建立了具有一般意义的动态模糊神经网络——模糊Hopfield神经网络，并系统分析了该动态系统的性能：在Hamming距离意义下证明了该网络是稳定的，而且其平衡点（吸引子）具有全局Lyapunov稳定性。最后，提供了一种有效的学习算法。     

有限数量机载雷达目标覆盖价值算法

针对有限数量机载雷达目标覆盖价值问题,建立了机载雷达载机待选轨道中心点(COCP)概念;分析了COCP和目标点之间的关系,给出了有限数量机载雷达目标覆盖价值问题的数学模型。通过分析有限规模COCP集合的方法,建立了多个机载雷达部署约束条件的数学模型。通过对COCP集合和目标点集合进行约束排除和聚类,简化了研究问题。总结出了有限数量机载雷达目标覆盖价值数学模型的最优解和启发式次优解,实例仿真结果表明该模型和算法的有效性。     

具有吞吐量和时延约束的软件无线电波形部署决策算法

针对当前具有吞吐量和时延约束的软件无线电波形部署决策算法在内存开销方面考虑的不足,提出一个更为通用的波形部署决策系统模型,将波形的处理开销、内存开销和通信带宽开销都纳入到波形部署决策过程中,并设计了一种基于动态规划的波形部署决策算法以最小化波形对平台各种计算资源的占用总和。仿真结果表明,内存对波形部署决策具有重要影响,与未考虑内存开销的解决方案相比,平台支持的平均最大波形数目和平均处理资源利用率均下降40%左右。     

A decomposition heuristic for the twin robots scheduling problem

This article provides an efficient heuristic based on decomposition for the twin robots scheduling problem (TRSP). TRSP concerns two moving robots executing storage and retrieval requests in parallel along a shared pathway. The depots are located at both ends of the line and a dedicated robot is assigned to each of them. While moving goods between their respective depots and some storage locations on the line, noncrossing constraints among robots need to be considered. Our heuristic uses a dynamic programming framework to determine the schedule of one robot while keeping the other one's fixed. It finds near‐optimal solutions even for large problem instances with hundreds of jobs in a short time span. © 2014 Wiley Periodicals, Inc. 62:16–22, 2015