Scheduling of depalletizing and truck loading operations in a food distribution system

This paper studies a scheduling problem arising in a beef distribution system where pallets of various types of beef products in the warehouse are first depalletized and then individual cases are loaded via conveyors to the trucks which deliver beef products to various customers. Given each customer's demand for each type of beef, the problem is to find a depalletizing and truck loading schedule that fills all the demands at a minimum total cost. We first show that the general problem where there are multiple trucks and each truck covers multiple customers is strongly NP‐hard. Then we propose polynomial‐time algorithms for the case where there are multiple trucks, each covering only one customer, and the case where there is only one truck covering multiple customers. We also develop an optimal dynamic programming algorithm and a heuristic for solving the general problem. By comparing to the optimal solutions generated by the dynamic programming algorithm, the heuristic is shown to be capable of generating near optimal solutions quickly. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003     

Analysis of a machine repair problem with an unreliable server and phase type repairs and services

In this paper we study a machine repair problem in which a single unreliable server maintains N identical machines. The breakdown times of the machines are assumed to follow an exponential distribution. The server is subject to failure and the failure times are exponentially distributed. The repair times of the machine and the service times of the repairman are assumed to be of phase type. Using matrix‐analytic methods, we perform steady state analysis of this model. The time spent by a failed machine in service and the total time in the repair facility are shown to be of phase type. Several performance measures are evaluated. An optimization problem to determine the number of machines to be assigned to the server that will maximize the expected total profit per unit time is discussed. An illustrative numerical example is presented. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 462–480, 2003     

基于Wigner-Ville时频幅值曲率的结构位置损伤识别

为探索既有明确物理意义又有良好实用性的结构损伤识别方法,利用Wigner-Ville时频分布（WVD）对结构自由振动响应进行解析,建立了WVD时频幅值与结构模态参数的函数关系,提出利用测点WVD时频幅值曲率来识别损伤。该方法物理意义明确,初始激励易于实施,且不需要模态参数识别,提高了损伤识别精度。算例分析结果表明,所提出的方法能较好地识别出结构单个或多个损伤位置,且数据易于获得,处理简便。     

基于定点剪出法抗滑桩滑坡推力分布形式的确定

针对现有滑坡推力分布假设为三角形、矩形或梯形等不合理现状,提出基于定点剪出假设确定滑坡推力分布的方法。在不平衡推力法的基础上,分析桩身若干点以上潜在滑体稳定性对滑坡推力的影响,然后在相邻段滑坡推力分布为线性的条件下,计算全桩若干点处滑坡推力的分布值。结果表明,定点剪出潜在滑体的稳定性对滑坡推力分布影响较大,若该稳定系数大于工程安全要求时,则无滑坡推力产生,若该稳定系数小于工程安全要求且相邻段稳定系数相差较大时,滑坡推力分布将会产生突变。最后通过一个边坡支护桩滑坡推力分布的工程实例,对该理论分析的合理性进行了说明。且在抗滑桩结构设计中,可根据桩身若干点滑坡推力分布值,采用变截面配筋,以节省工程投资。     

战区弹药保障敏捷供应链优化模型及实现算法

针对现有的供需矛盾,在分析战区弹药保障供应链管理任务需求的基础上,初步构建了战区弹药保障敏捷供应链管理框架及运行机制,分析了战区弹药保障敏捷供应链的供需协同机制,重点对多级库存优化控制模型、多级弹药配送决策优化模型及实现算法进行了研究,提出了战区弹药保障敏捷供应链建设的具体对策。     

雷达网实际探测概率分布模型与仿真算法

基于综合考虑各种外界因素影响的雷达实际平面探测区域,建立雷达网实际探测概率分布模型,是一个有待深入探讨的问题.考虑地物遮蔽、顶空和波瓣间盲区的具体影响,首先讨论了雷达单元实际平面探测威力模型,进而提出了一种雷达网实际探测概率分布模型与仿真算法.实例仿真结果表明该模型和算法实用高效.     

基于模糊聚类分析在炮兵战场目标打击排序中的应用

炮兵战场上经侦察得到的目标情况往往比较复杂,利用模糊聚类分析法确定目标区域内各种目标的先后打击次序,建立模糊相似关系矩阵,最后在给定阈值的基础上计算出目标的优先打击次序,为战场指挥员提供比较合理的火力分配,从而最大限度地发挥炮兵火力效能。     

装备再制造性指标分配

再制造性设计是装备再制造工程的重要组成部分,是实现退役装备易于再制造的可靠保证,而再制造性指标分配是再制造性设计的重要内容,它能够保证所要求的指标科学地分配到装备各零部件,实现装备再制造效益的最大化。探讨了再制造性指标分配的相关概念及其再制造性指标分配程序,并提出了几种可行的再制造性指标分配方法,为装备的再制造性设计提供了有效的技术支撑。     

基于分形理论的目标航路预测

电磁干扰条件下解决断续航路预测问题对防空兵有效抗击空中目标至关重要。针对包络灰预测方法预测精度较低和Verhulst灰色预测模型计算过程复杂的情况,提出了预测航路的分形方法。在分形理论的基础上,研究了其用于目标断续航路预测的基本思路,建立了基于分形的目标航路预测模型,并对模型进行了求解。最后,利用建立的分形模型对雷达丢失目标后的目标航路进行了预测,通过实例体现了分形方法在用于航路预测时的准确性、灵活性和易实现等特点。结果表明,用该法对断续目标航路的预测具有一定的借鉴意义。     

Insurgent courts in civil wars: the three pathways of (trans)formation in today’s Syria (2012–2017)

As part of research on the meso-foundations of conflict, the field of ‘rebel governance’ examines political institutions that regulate the affairs of civilians in wartime as well as their relations with armed actors. Judicial institutions play an important role in this and research has shown that they are widespread among both historical and current insurgencies. However, usually these bodies have been analysed in the context of one hegemonic faction like the Tamil Tigers in Sri Lanka and the Afghan Taliban. What is missing so far is an analysis of different pathways of (trans)formation of rebel courts. As exemplified by the three case studies of judicial institutions in Eastern Ghouta, Idlib and Aleppo, these are shaped by the distribution of power between ‘same-side’ groups, yielding unipolar, bipolar, or multipolar constellations. The analysis is located on the meso or movement level of insurgent social structures, complementing research on the micro and macro levels.