空间站平均力矩平衡姿态的气动力矩影响

为了研究空间站平均力矩平衡姿态的影响因素,建立了空间站的姿态运动模型,分析了气动力矩对空间站平均力矩平衡姿态的影响。建立了空间站的动力学与控制模型,采用典型的比例微分控制器,分别得出了两种条件下的24组平均力矩平衡姿态(Average Torque Equilibrium Attitude,ATEA),结果表明气动力矩对ATEA的影响显著。为了保持空间站ATEA,需要提供周期性的控制力矩。气动力矩引起的空间站角动量卸载和积累效应不能被忽视。     

Partitioning of biweighted trees

A districting problem is formulated as a network partitioning model where each link has one weight to denote travel time and another weight to denote workload. The objective of the problem is to minimize the maximum diameter of the districts while equalizing the workload among the districts. The case of tree networks is addressed and efficient algorithms are developed when the network is to be partitioned into two or three districts. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 143–158, 2002; DOI 10.1002/nav.10003     

Duality in constrained multi‐facility location models

We consider the ??_p‐norm multi‐facility minisum location problem with linear and distance constraints, and develop the Lagrangian dual formulation for this problem. The model that we consider represents the most general location model in which the dual formulation is not found in the literature. We find that, because of its linear objective function and less number of variables, the Lagrangian dual is more useful. Additionally, the dual formulation eliminates the differentiability problem in the primal formulation. We also provide the Lagrangian dual formulation of the multi‐facility minisum location problem with the ??_pb‐norm. Finally, we provide a numerical example for solving the Lagrangian dual formulation and obtaining the optimum facility locations from the solution of the dual formulation. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 410–421, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10010     

新型移动式野战加油站建设与运用

针对部队加油站建设标准不一、形式多样、改造周期长、费用高、效率低、耐候性差的问题,本文在明确新型移动式野战加油站的建设意义和建设目标的基础上,对移动式野战加油站的整体可移动性、储油罐与加油装置集成以及边海防等一线连队的油料保障模式和建设标准进行了研究,从工艺流程、建设选址和建设标准等方面提出了基于集装箱方舱框架设计新型移动式野战加油站的保障运用模式。这种模式不仅可填补大容量战储装备空白,还可以为热点方向实施定点保障,为加快推进部队储加油设施建设向集约化转型、保障向战场延伸提供借鉴。     

A stochastic gradual cover location problem

Covering models assume that a point is covered if it is within a certain distance from a facility and not covered beyond that distance. In gradual cover models it is assumed that a point is fully covered within a given distance from a facility, then cover gradually declines, and the point is not covered beyond a larger distance. Gradual cover models address the discontinuity in cover which may not be the correct approach in many situations. In the stochastic gradual cover model presented in this article it is assumed that the short and long distances employed in gradual cover models are random variables. This refinement of gradual cover models provides yet a more realistic depiction of actual behavior in many situations. The maximal cover model based on the new concept is analyzed and the single facility location cover problem in the plane is solved. Computational results illustrating the effectiveness of the solution procedures are presented. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

Equivalent accelerated life testing plans for log‐location‐scale distributions

Accelerated life testing (ALT) is widely used to determine the failure time distribution of a product and the associated life‐stress relationship in order to predict the product's reliability under normal operating conditions. Many types of stress loadings such as constant‐stress, step‐stress and cyclic‐stress can be utilized when conducting ALT. Extensive research has been conducted on the analysis of ALT data obtained under a specified stress loading. However, the equivalency of ALT experiments involving different stress loadings has not been investigated. In this article, a log‐location‐scale distribution under Type I censoring is considered in planning ALT. An idea is provided for the equivalency of various ALT plans involving different stress loadings. Based on this idea, general equivalent ALT plans and some special types of equivalent ALT plans are explored. For demonstration, a constant‐stress ALT and a ramp‐stress ALT for miniature lamps are presented and their equivalency is investigated. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

基于改进单亲遗传算法的军事物流中心选址问题研究

为了有效求解军事物流中心选址问题,在单亲遗传算法加入模拟退火选择操作,与倒位算子和非均匀变异操作相结合,构建了退火单亲遗传算法。在选择操作中,采用三复本锦标选择的方式,确保了种群的多样性。计算结果表明该方法可有效求解选址问题,取得较一般遗传算法更优的结果,算法的搜索效率和收敛概率均得到大幅度提高。     

H2O2对镁合金稀土转化膜性能的影响

选择AZ91D镁合金为实验材料,利用扫描电镜和能谱分析、Tafel曲线和阻抗谱等分析手段,研究了H2O2的添加量对铈转化膜的微观形貌以及耐蚀性能的影响。结果表明：随H2O2添加量的增多,转化膜表面状态越不均匀,自腐蚀电位降低,转化膜电阻Rf变小,较为合适的H2O2添加量为5 mL/L。     

基于遗传算法的应急物流多设施选址模型研究

在现有研究的基础上,建立了应急物流多设施选址模型。在模型建立过程中除了考虑距离这一基本要素,还考虑了流量与安全性等道路特性,并将其转换为道路的综合权值,使模型更具现实意义。采用遗传算法求解,使该问题的求解过程得到简化。最后用实例对模型进行了验证分析,说明该模型的合理性。     

The assignment of storage locations to containers for a container stack

Assigning storage locations to incoming or reshuffled containers is a fundamental problem essential to the operations efficiency of container terminals. The problem is notoriously hard for its combinatorial and dynamic nature. In this article, we minimize the number of reshuffles in assigning storage locations for incoming and reshuffled export containers. For the static problem to empty a given stack without any new container arrival, the optimum reshuffle sequence is identified by an integer program (IP). The integer program captures the evolution of stack configurations as a function of decisions and is of interest by itself. Heuristics based on the integer program are then derived. Their competitiveness in accuracy and time are established by extensive numerical runs comparing them with existing heuristics in literature and in practice as well as with extensions of the existing heuristics. Variants of the IP‐based heuristics are then applied to the dynamic problem with continual retrievals and arrivals of containers. Again, numerical runs confirm that the IP‐based heuristic is competitive. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009