A partial characterization of the optimal ordering/rationing policy for a periodic review system with two demand classes and backordering

We consider a finite horizon periodic review, single product inventory system with a fixed setup cost and two stochastic demand classes that differ in their backordering costs. In each period, one must decide whether and how much to order, and how much demand of the lower class should be satisfied. We show that the optimal ordering policy can be characterized as a state dependent (s,S) policy, and the rationing structure is partially obtained based on the subconvexity of the cost function. We then propose a simple heuristic rationing policy, which is easy to implement and close to optimal for intensive numerical examples. We further study the case when the first demand class is deterministic and must be satisfied immediately. We show the optimality of the state dependent (s,S) ordering policy, and obtain additional rationing structural properties. Based on these properties, the optimal ordering and rationing policy for any state can be generated by finding the optimal policy of only a finite set of states, and for each state in this set, the optimal policy is obtained simply by choosing a policy from at most two alternatives. An efficient algorithm is then proposed. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

在求“变”中推进西南边防部队转型发展

西南边防部队驻防于我国西南边境地区,西起西藏自治区的日土县,东至广西壮族自治区的防城港市,担负着边防管控和边境防御作战等重要职能,在捍卫国家主权和安全中地位作用十分特殊。随着军队调整改革的深入落实,西南边防部队正处于转型重塑的关键时期,必须紧紧围绕新形势、新体制、新职能,着眼应急指挥、军事训练、边境管控、内外环境等关键要素和现实问题,在求"变"中推进创新发展,不断提升履职能力,切实为捍卫国家领土主权完整和维护边境稳定提供坚强保证。     

Approximation results for min‐max path cover problems in vehicle routing

This article studies a min‐max path cover problem, which is to determine a set of paths for k capacitated vehicles to service all the customers in a given weighted graph so that the largest path cost is minimized. The problem has wide applications in vehicle routing, especially when the minimization of the latest service completion time is a critical performance measure. We have analyzed four typical variants of this problem, where the vehicles have either unlimited or limited capacities, and they start from either a given depot or any depot of a given depot set. We have developed approximation algorithms for these four variants, which achieve approximation ratios of max{3 ‐ 2/k,2}, 5, max{5 ‐ 2/k,4}, and 7, respectively. We have also analyzed the approximation hardness of these variants by showing that, unless P = NP , it is impossible for them to achieve approximation ratios less than 4/3, 3/2, 3/2, and 2, respectively. We have further extended the techniques and results developed for this problem to other min‐max vehicle routing problems.© 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

试析新中国成立初期人民解放军学习苏军活动

新中国成立初期，人民解放军展开了学苏军活动。这次学苏军活动，经历了全面学习、有分析有批判地学习以及确立“以我为主”方针等三个历史阶段。通过学习、借鉴苏军经验，人民解放军技战术水平和协同作战能力有了很大提高，正规化现代化革命化建设取得显著成绩，同时也积累了许多值得借鉴的经验教训。     

论斯大林军事理论的几大亮点(下)

斯大林是苏联共产党和国家主要领导人、武装力量最高统帅，在领导苏联国防建设和反侵略战争的长期实践中，形成了具有自己特色的军事理论。其中，国家要进行积极防御的准备，必须建立和建设一支无产阶级常备军，大力发展国民经济、建立雄厚的国防经济基础，建立和巩固反侵略同盟，经常保持、正确使用战略预备队和用大规模围歼战役歼灭敌军重兵集团，是最引人注目的6个方面。斯大林军事理论总体上适合于他所处的历史条件和实践提出的要求，反映了苏联进行国内战争、军队建设、国防建设和反侵略战争的基本规律，为巩固苏维埃政权，特别是为取得卫国战争的胜利发挥了重要作用。     

坦克分队战术仿真训练系统的设计与实现

分布交互式作战仿真系统通过网络把不同的模拟单元连接在一起,为受训人员提供虚拟的作战训练环境,系统的运行成本低,能提供比实战演习更多的训练环境和内容.为了满足我军坦克兵部队战术训练的实际需要,设计开发了坦克分队战术仿真训练系统.讨论了该系统的设计与开发,首先介绍系统的总体结构和功能,然后详细讨论系统具体设计和实现.该系统已推广部队使用,应用效果良好.     

VC++和MATCOM结合在飞机基本飞行性能程序开发中的应用

简要分析了Matlab语言在科学工程计算中的优缺点;针对飞机飞行性能计算过程中的一些问题,介绍了一种调用Matcom语言对M文件进行编译,从而与VC 结合编程的新方法.并用实例说明该方法在飞机飞行性能科学计算和计算结果图形绘制中的应用,拓展了软件的应用范围和使用价值.     

都市圈石漠化区域采石场的生态恢复方法与措施探讨

都市圈石漠化区域采石场往往由于过度开发且未采取有效的恢复措施,致使生态环境破坏严重,严重影响了都市圈的生态环境和经济发展.在分析都市圈石漠化区域采石场生态恢复特点的基础上,论述了其生态恢复的基本方法及工程技术措施,指出都市圈石漠化区域采石场生态恢复应依据都市圈发展总体规划和景观生态学、景观建筑学及美学原理,采用开发性治理方法,综合运用多种工程技术措施恢复植被、整治水土流失并进行景观再造,从而满足都市圈对于景观的要求,提高土地利用价值,促进都市圈社会经济发展和城市生态环境建设.     

铁磁材料裂纹漏磁信号的定量检测

针对无损探伤难于实现定量检测的问题,探讨了基于模式识别进行铁磁材料裂纹漏磁信号定量分析的原理和方法,通过在标准试件上的大量实验及在具有自然裂纹的工件上实际检测,取得了满意效果。     

升降法数据的可靠性评定

针对目前升降法数据可靠性评定方法的不足,在火工品可靠性评定模型基础上,重点探讨了用正态容许限法对升降法数据进行可靠性评定的方法。