Inventory policies for a make‐to‐order system with a perishable component and fixed ordering cost

We consider a make‐to‐order production system where two major components, one nonperishable (referred to as part 1) and one perishable (part 2), are needed to fulfill a customer order. In each period, replenishment decisions for both parts need to be made jointly before demand is realized and a fixed ordering cost is incurred for the nonperishable part. We show that a simple (s_n,S,S) policy is optimal. Under this policy, S along with the number of backorders at the beginning of a period if any and the availability of the nonperishable part (part 1) determines the optimal order quantity of the perishable part (part 2), while (s_n,S) guide when and how much of part 1 to order at each state. Numerical study demonstrates that the benefits of using the joint replenishment policy can be substantial, especially when the unit costs are high and/or the profit margin is low. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

联合火力毁伤下炮兵连阵地配置与被毁伤概率

现代战场威胁炮兵的火力与弹药种类更加丰富,如何根据它们的特点选择恰当的阵地配置队形与火炮间隔,以最大限度地降低被毁伤概率就显得尤为重要.以自行炮兵连为研究对象,依据射击效率评定理论.结合几种典型的配置队形和红蓝双方的主要装备,对不同攻击方式下的被毁伤概率进行了模拟分析,得到了在阵地地形允许的情况下,应采用半圆形配置;普通榴弹射击时火炮配置间隔以200 m为宜,子母弹射击时如果要避免一半以上的火炮被毁伤,配置间隔也应至少达到200 m的结论.     

改进的联合Kalman滤波及其在组合导航中的应用

以组合导航为应用背景,对联合Kalman滤波进行了改进,每循环Ⅳ次,就用主滤波器的估计值来修正子滤波器的值,以改善滤波器的性能,提高组合导航系统精度,并且大大减小收敛时间,提高其效率.最后将该方法应用于GPS/INS/LORAN-C组合导航系统中,仿真结果表明该方法是有效的.     

面向第四代战斗机的超视距空战

面对第四代战斗机的列装服役,其先进的技战术性能使得未来空战中超视距空战这种模式越来越占据主导地位,超视距空战具有其特殊的战术特点和影响其空战效果的因素,尤其是机载雷达和空空导弹的性能差异对超视距空战影响很大,因此要充分掌握战斗机的主要性能,做到取长补短.但是,空战中情况瞬息万变,任何时候也离不开飞行员和指挥员的灵活处置.只有在战斗机性能的不断提升的基础上,研究出相应的超视距空战战术,才能在未来高技术空战中真正具备打赢能力.     

火箭子母弹对行进中炮兵连射击的毁伤概率

炮兵实施机动是提高其生存能力与作战能力的重要手段之一,而从集结地域至待机阵地机动阶段由于距离对方近、暴露时间长,是对方毁伤火力种类最为丰富和威胁最大的阶段.以行进中的自行与牵引炮兵连为研究对象,分析了该阶段火箭子母弹攻击时的毁伤概率,计算了相应条件下的毁伤概率值,描述了毁伤概率与航路角、行进速度之间的基本关系和变化规律.     

Clustered coverage orienteering problem of unmanned surface vehicles for water sampling

This study investigates a clustered coverage orienteering problem (CCOP), which is a generalization of the classical orienteering problem. The problem is widely motivated by the emerging unmanned techniques (eg, unmanned surface vehicles and drones) applied to environmental monitoring. Specifically, the unmanned surface vehicles (USVs) are used to monitor reservoir water quality by collecting samples. In the CCOP, the water sampling sites (ie, the nodes) are grouped into clusters, and a minimum number of nodes must be visited in each cluster. With each node representing a certain coverage area of the water, the objective of the CCOP is to monitor as much as possible the total coverage area in one tour of the USV, considering that overlapping areas provide no additional information. An integer programming model is first formulated through a linearization procedure that captures the overlapping feature. A two-stage exact algorithm is proposed to obtain an optimal solution to the problem. The efficiency and effectiveness of the two-stage exact algorithm are demonstrated through experiments on randomly generated instances. The algorithm can effectively solve instances with up to 60 sampling sites.     

On competitive analysis for polling systems

Polling systems have been widely studied, however most of these studies focus on polling systems with renewal processes for arrivals and random variables for service times. There is a need driven by practical applications to study polling systems with arbitrary arrivals (not restricted to time-varying or in batches) and revealed service time upon a job's arrival. To address that need, our work considers a polling system with generic setting and for the first time provides the worst-case analysis for online scheduling policies in this system. We provide conditions for the existence of constant competitive ratios, and competitive lower bounds for general scheduling policies in polling systems. Our work also bridges the queueing and scheduling communities by proving the competitive ratios for several well-studied policies in the queueing literature, such as cyclic policies with exhaustive, gated or l-limited service disciplines for polling systems.     

灵活的多层嵌套拉丁超立方体设计构造

计算机试验的设计方法越来越受到重视,嵌套拉丁超立方体设计是计算机试验设计中的一种新型方法,其在多种精度试验中有广泛的应用。但多数嵌套拉丁超立方体设计要求低精度试验次数需为高精度试验次数的倍数,这在应用中会有很大的局限性。通过对其构造方法的改进,得到一种结构更加灵活的多层嵌套拉丁超立方体设计,使得不同精度试验的次数可以更加灵活选取。该设计方法在一维投影上可以达到很好的均匀性。仿真结果表明,该方法较若干相关方法能够达到更小的均方误差。     

指挥引导模型的自动生成

介绍了传统指挥引导模型的建立方法,并分析了其不足;提取出战法属性并分析总结了战法的共同点;作为使用数据库技术进行引导解算的基础,引入了敌我相对态势表、飞行方式表、战法属性表的概念;结合实例,在传统指挥引导建模的基础上,给出了一种新的建模方法,提出了通用模型建立的初步思想,有利于指挥引导模型自动生成的实现.