大气层高层功能拦截器侧窗定向方位研究

大气层高层作战的动能拦截器多采用侧窗探测的结构布局,侧窗定向方位对其拦截效果有重要的影响,但定向方位的选择却受诸多因素制约.在一定理想化假设的基础上,研究了末段交战过程中视线转率的变化规律,从理论上分析了由侧窗定向产生的攻角对拦截结果的影响,得到了只考虑气动力影响下的最佳定向方位;然后综合考虑气动力、轨控系统、姿控系统的影响,给出了不同作战高度下侧窗定向方位的选择方法.数字仿真结果表明,此种方法能够满足侧窗探测的要求,且在大多数情况下只需一次定向即可完成拦截.     

Fixed‐interval joint‐replenishment policies for distribution systems with multiple retailers and stochastic demand

We consider a distribution system consisting of a central warehouse and a group of retailers facing independent stochastic demand. The retailers replenish from the warehouse, and the warehouse from an outside supplier with ample supply. Time is continuous. Most previous studies on inventory control policies for this system have considered stock‐based batch‐ordering policies. We develop a time‐based joint‐replenishment policy in this study. Let the warehouse set up a basic replenishment interval. The retailers are replenished through the warehouse in intervals that are integer multiples of the basic replenishment interval. No inventory is carried at the warehouse. We provide an exact evaluation of the long‐term average system costs under the assumption that stock can be balanced among the retailers. The structural properties of the inventory system are characterized. We show that, although it is well known that stock‐based inventory control policies dominate time‐based inventory control policies at a single facility, this dominance does not hold for distribution systems with multiple retailers and stochastic demand. This is because the latter can provide a more efficient mechanism to streamline inventory flow and pool retailer demand, even though the former may be able to use more updated stock information to optimize system performance. The findings of the study provide insights about the key factors that drive the performance of a multiechelon inventory control system. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 637–651, 2013     

The defence firm of the future

This paper offers the personal view of a senior executive in the Defence Procurement Agency about the future requirements of the defence industry’s principal UK customer. The focus here is on trying to identify the type of corporate behaviour and range of skill sets that the UK Government will need from defence suppliers, both primes and supply chain companies in the future. The concluding message from this ‘Customer View’ is that there is likely to be a continuing market for the company that specializes in delivering defence capability. It will be a company that will be looking for a long‐term relationship, with a specialist knowledge of its various national customers and a willingness to work openly and closely with them. It will be agile in its ability to bring together diverse technologies, to package them as a system and to deliver them either as hardware or as a service. Such suppliers will also need to innovate and to adapt at least as rapidly as the threats that they seek to counter.     

A 17th-century Pikeman's Armour from Antwerp

Abstract

A recent re-examination of the arms and armour collection at the British Museum has led to the identification of a 17th-century pikeman's armour clearly associated with the city of Antwerp in modern Belgium, the only example of its kind. The three pieces: a pot, breastplate and backplate, are part of a collection bequeathed to the museum by William Burges in 1881. All three pieces can be dated to circa 1635 and are stamped with the arms of Antwerp, a stylised depiction of Antwerp castle between two hands derived from the blazon of the Margrave of Antwerp. The armour is indistinguishable from contemporary Dutch production and it is unclear whether it was made in Antwerp or whether the addition of the arms simply suggests a use in the city.     

JXTA网络短链路由改进算法

JXTA为构建对等网络提供了标准化计算平台,制定一些协议和服务专门解决构建P2P网络所遇见的问题.为了改进JXTA路由查询效率低下问题,提出一种路由短链改进算法.在端点路由协议的基础上,根据小世界短链现象采用物理邻居策略将网络划分簇,簇内采用Pastry算法,簇间运用freePastry算法进行资源搜索,使长跳路由减少短链路由增加.通过仿真实验说明,算法可有效增加检索效率,减少节点间的通讯时延.     

Should firms conceal information when dealing with common suppliers?

A firm making quantity decision under uncertainty loses profit if its private information is leaked to competitors. Outsourcing increases this risk as a third party supplier may leak information for its own benefit. The firm may choose to conceal information from the competitors by entering in a confidentiality agreement with the supplier. This, however, diminishes the firm's ability to dampen competition by signaling a higher quantity commitment. We examine this trade‐off in a stylized supply chain in which two firms, endowed with private demand information, order sequentially from a common supplier, and engage in differentiated quantity competition. In our model, the supplier can set different wholesale prices for firms, and the second‐mover firm could be better informed. Contrary to what is expected, information concealment is not always beneficial to the first mover. We characterize conditions under which the first mover firm will not prefer concealing information. We show that this depends on the relative informativeness of the second mover and is moderated by competition intensity. We examine the supplier's incentive in participating in information concealment, and develop a contract that enables it for wider set of parameter values. We extend our analysis to examine firms' incentive to improve information. © 2014 Wiley Periodicals, Inc. 62:1–15, 2015     

装备项目型供应链风险控制策略

项目型供应链管理模式能有效实现装备研制过程中行为主体间的优势互补和资源的优化配置,利于供应链整体效益的提高,但各种不确定性因素会导致主体间风险传递行为的发生。为提供风险控制有效对策,通过考虑节点位置重要度和属性重要度,构建了项目型供应链节点重要度评估模型;通过衡量行为主体风险识别和风险控制的努力程度,给出了行为主体抗风险努力程度的评价方法,最后提出了一种基于节点重要度和抗风险努力程度的项目型供应链利益分配策略,该策略能有效促使行为主体主动进行风险识别和风险控制,是一种"风险共担、利益共享"的项目型供应链合作博弈策略。     

能量传递在弹丸致伤效应中的研究

为了寻求一种量化的方法,更好地评估轻武器对肌体的致伤效能,根据肌体特性,以经典外弹道理论[1]和创伤弹道学理论[2]为依据,建立弹丸在肌体组织内的运动模型。利用脉冲X射线照相得到相关实验数据,运用Matlab软件对弹丸运动模型进行编程[3],计算出弹丸侵彻距枪口某距离处肌体靶标后,在肌体内的速度变化规律,从而计算出弹丸传递给人体能量的大小,再以此为依据快速评价出弹丸的致伤效能。     

基于Petri网的指挥流程建模与优化

鉴于Petri网在企业业务流程优化与重组方面的成功运用,遂将Petri网原理应用于作战指挥流程的建模与优化,以期获得最优作战指挥流程.文中首先阐述Petri网基本原理,然后介绍指挥流程建模的Petri网模型,最后给出指挥流程优化的原则及基本模型,并利用Petri网对指挥流程进行建模和优化,结果表明Petri网理论能够明显优化作战指挥流程.提高作战指挥效率.     

舰舰协同制导下舰空导弹水平发射区研究

为增加舰空导弹拦截低空目标的发射时机,研究了舰舰协同制导下舰空导弹水平发射区.首先分别计算了单舰制导和雷达哨舰接力制导下水平发射区;然后在坐标系内合成得到舰舰协同制导下舰空导弹水平发射区.通过仿真比较,得出舰舰协同制导下比单舰制导下目标航路捷径增加了35%左右,舰空导弹水平发射区的纵深显著增加的结论,为舰艇作战指挥决策提供了较好的理论依据.