Estimating failure time distribution and its parameters based on intermediate data from a Wiener degradation model

Instead of measuring a Wiener degradation or performance process at predetermined time points to track degradation or performance of a product for estimating its lifetime, we propose to obtain the first‐passage times of the process over certain nonfailure thresholds. Based on only these intermediate data, we obtain the uniformly minimum variance unbiased estimator and uniformly most accurate confidence interval for the mean lifetime. For estimating the lifetime distribution function, we propose a modified maximum likelihood estimator and a new estimator and prove that, by increasing the sample size of the intermediate data, these estimators and the above‐mentioned estimator of the mean lifetime can achieve the same levels of accuracy as the estimators assuming one has failure times. Thus, our method of using only intermediate data is useful for highly reliable products when their failure times are difficult to obtain. Furthermore, we show that the proposed new estimator of the lifetime distribution function is more accurate than the standard and modified maximum likelihood estimators. We also obtain approximate confidence intervals for the lifetime distribution function and its percentiles. Finally, we use light‐emitting diodes as an example to illustrate our method and demonstrate how to validate the Wiener assumption during the testing. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Supply chain coordination with shelf‐space and retail price dependent demand and heterogeneous retailers

We consider supply chain coordination in which a manufacturer supplies some product to multiple heterogeneous retailers and wishes to coordinate the supply chain via wholesale price and holding cost subsidy. The retail price is either exogenous or endogenous. The market demand is described by the market share attraction model based on all retailers'shelf‐spaces and retail prices. We obtain optimal solutions for the centralized supply chain, where the optimal retail pricing is a modified version of the well‐known cost plus pricing strategy. We further get feasible contracts for the manufacturer to coordinate the hybrid and decentralized supply chains. The manufacturer can allocate the total profit free to himself and the retail market via the wholesale price when the retail price is exogenous, but otherwise he cannot. Finally, we point out that different characteristics of the retail market are due to different powers of the manufacturer, and the more power the manufacturer has, the simpler the contract to coordinate the chain will be. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

硅整流无刷发电机供电系统动态性能的研究

分析了坦克的供电系统中采用硅整流无刷发电机时的工作特点,建立了这种系统的数学模型,举例说明了计算方法,并在文章的最后进行了评价.     

装甲车辆起动电动机综合试验台

采用较先进的磁粉制动器作为电机的负载,使电机加载平稳、可靠、恒定,并可连续调节负载大小;同时采用高精度的ZJ型转矩转速传感器并配合转矩转速仪,不但能测量电机稳态时的转矩、转速和功率,同时还可测试电机某一过渡过程中转矩、电流、转速随时间变化的数值并贮存或打印.     

弹药保障决策模型的研究

从弹药保障的工作入手 ,论述了弹药消耗预计算法 ,提出了基于存储论的弹药补充决策模型。给出了战时弹药保障的 3种策略     

综合飞行/火力控制系统性能评价

详细介绍了综合飞行 /火力控制系统 (IFFCS)性能评价的方法。该方法把评价过程分为单元评价、组合评价和系统性能评价 ,将系统性能指标逐层分解 ,以保证闭合系统最终能完成自动攻击任务。以高性能控制系统仿真软件MATTRIXX6 .0为平台 ,按此方法开发的评价软件获得了用户的认可     

Optimal material control in an assembly system with component commonality

Allocation of scarce common components to finished product orders is central to the performance of assembly systems. Analysis of these systems is complex, however, when the product master schedule is subject to uncertainty. In this paper, we analyze the cost—service performance of a component inventory system with correlated finished product demands, where component allocation is based on a fair shares method. Such issuing policies are used commonly in practice. We quantify the impact of component stocking policies on finished product delays due to component shortages and on product order completion rates. These results are used to determine optimal base stock levels for components, subject to constraints on finished product service (order completion rates). Our methodology can help managers of assembly systems to (1) understand the impact of their inventory management decisions on customer service, (2) achieve cost reductions by optimizing their inventory investments, and (3) evaluate supplier performance and negotiate contracts by quantifying the effect of delivery lead times on costs and customer service. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48:409–429, 2001     

高原环境对军用油料装备柴油动力性能影响分析

针对青藏高原特殊地理环境和气候条件特点,通过某大型群车加油车在高原地区的训练使用,分析海拔高度与大气压力、空气密度和温度的对应关系,探讨了在高原环境条件下使用油料装备其柴油动力的动力性、经济性及低温起动性能受到的影响,提出了相应的改进措施。     

Applying a bootstrap approach for setting reorder points in military supply systems

This paper develops and applies a nonparametric bootstrap methodology for setting inventory reorder points and a simple inequality for identifying existing reorder points that are unreasonably high. We demonstrate that an empirically based bootstrap method is both feasible and calculable for large inventories by applying it to the 1st Marine Expeditionary Force General Account, an inventory consisting of $20–30 million of stock for 10–20,000 different types of items. Further, we show that the bootstrap methodology works significantly better than the existing methodology based on mean days of supply. In fact, we demonstrate performance equivalent to the existing system with a reduced inventory at one‐half to one‐third the cost; conversely, we demonstrate significant improvement in fill rates and other inventory performance measures for an inventory of the same cost. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 459–478, 2000     

窄带假设对GNSS天线阵抗干扰性能评估的影响分析

传统方法基于窄带假设条件下的模型对天线阵抗干扰性能进行评估,存在分析精度低的问题.新一代全球卫星导航信号带宽的增加使得宽带效应更为明显,影响将更为严重.因此,窄带假设所造成的影响需要重新审视.论文结合当前普遍采用的数字域加权处理方式,推导出天线阵处理频率响应的精确模型,得出阵列处理响应在频域上可表示为空域导向矢量与时间...