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     

National security,military spending and the business cycle

This paper develops a Dynamic Stochastic General Equilibrium model where national security is an argument in the agent’s utility function and the government chooses optimally the level of military spending to maximize social welfare. National defense depends on military expenditure and on the strategic environment reflecting a potential hostile external threat. We use aggregate data on consumption, investment, and military spending for the US economy to estimate the parameters of the model. Estimation results suggest that consumption and national defense are complements and that military spending variability is mainly explained by external threat shocks although it also depends on the macroeconomic conditions. We compute impulse response functions of the main macroeconomic variables to several shocks: a total factor productivity shock, a defense technology shock, and a strategic environment shock. Surprisingly, we find that the optimal response to an increase in the external threat (a worsening in the strategic environment) will rise output by reducing consumption and increasing investment.     

Attrition through a partially coordinated area defense

An area defense consists of several groups that act independently, i.e., do not communicate with each other. Each group has a fixed number of defenders and a controller that allocates these defenders optimally against the individual attackers comprising an attack. We analyze the effectiveness of this partially coordinated defense against a simultaneous attack of known size in which all attackers are considered to be equally lethal. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005.     

三维运动捕捉技术在消防模拟训练中的应用

从角色模型的创建、消防员个性化动作数据的捕捉和处理以及利用该数据对模拟训练场景里消防员的驱动,探讨了如何将三维运动捕捉技术应用于消防模拟训练中。结果表明：三维运动捕捉技术的应用为解决消防模拟训练场景中虚拟消防员实时动画问题,人员疏散的视景仿真问题等探索了道路,奠定了基础。     

着眼建设现代化武警需要创新新型指挥人才培养模式

胡主席关于“建设一支能够有效维护国家安全和社会稳定、保障人民安居乐业的现代化武装警察力量”的战略思想,深刻揭示了建设现代化武警与履行职责使命的内在关系。要建设现代化武警,有效履行职责使命,就需要新型的指挥人才。因此,我们必须高瞻远瞩,站在当今世界军事人才培养的“制高点”,注重实效,切实培养出大批高素质的新型军事指挥人才。     

改进的拉格朗日松弛数据关联算法

在多传感器多目标跟踪领域中,当传感器为被动式的,传统的多维分配算法利用拉格朗日松弛算法求解.拉格朗日乘子更新一般用次梯度方法,但每次迭代都要进行多次极小化运算来求对偶解,导致实时性差.针对这个问题,提出了一种改进的基于拉格朗日松弛的数据关联算法,通过代理修正次梯度方法更新拉格朗日乘子,并在允许时间内获得近似解.仿真实验...     

基于气动-弹道一体化模型的飞行器外形优化设计

为提升飞行器气动外形优化设计效果,研究了新型飞行器在大空域、宽速域范围的气动适应性问题,提出一种基于气动-弹道一体化模型的外形优化设计方法。通过考虑气动和弹道的耦合作用,综合利用类型函数/形状函数转换技术、气动工程估算方法和Radau伪谱法,建立飞行器气动-弹道一体化模型。基于该模型,通过明确优化目标和约束条件,给出基于Kriging的气动外形优化方法,实现在多参数约束条件下的飞行器气动外形高效全局优化。以升力体构型飞行器为例,开展气动外形优化设计,结果表明该方法能较好地描述大空域、宽速域的气动和弹道特征,有效提升飞行器气动外形设计精度和水平,可为新型飞行器总体设计提供技术支撑。     

舰载单脉冲跟踪雷达数学建模与仿真

根据典型舰载单脉冲跟踪雷达的组成及工作原理,介绍一种舰载单脉冲跟踪雷达仿真建模方法。重点描述了仿真原理及仿真模型组成,介绍了雷达信号特性仿真、雷达伺服系统仿真、雷达信号处理系统仿真等关键环节的数学仿真模型。结合仿真软件功能需求,给出了软件结构、软件运行流程等仿真软件设计要点。     

面向决策的一体化建模方法及其在兵力筹划中的应用

在对军事决策问题的主要特点进行分析的基础上,提出从军事概念模型到数学模型再到定性推理模型的一体化建模思想.以空军航空兵遂行直接航空火力支援任务为想定背景,根据EATI模板,利用基于UML的Rose工具依次对想定任务的实体、任务、交互等进行分析;对于兵力筹划中的结构化问题建立了机会约束多目标规划数学模型;对于非结构化问题则构造了推理机,推理机体现了定量与定性相结合的决策分析思想.最后,以一个实例验证文章思路的可行性.     

Do Military Expenditures Crowd-out Health Expenditures? Evidence from around the World, 2000–2013

Abstract

The paper examines the relationship between health and military expenditures using pooled cross-sectional (197 countries) and time series (2000–2013) data. Simultaneous equation models were employed to estimate the relationship between an array of public sector expenditures in order to address potential endogeneity. Our empirical findings strongly support the crowding-out hypothesis whereby increased military expenditures reduce the capacity of government to direct expenditures to health expenditures. These findings were robust to alternative specifications explored in the sensitivity analyses. Compared with upper-middle-income countries, the crowding-out effect became more pronounced among lower-middle-income countries. Consequently, this study shows that increased military expenditures negatively impacts health expenditures, and therefore poses as an important risk factor for population health and individual well-being. Moreover, it is the poorest of nations that are most sensitive to the negative effects of increased military expenditures.