大气层内复合控制拦截弹切换时间的探讨

大气层内拦截弹采用空气动力与燃气动力的复合控制方式是当今世界防空导弹的发展方向之一。复合控制技术的分析研究是当前急需解决的重要问题。在考虑目标机动加速度大小、目标机动时刻以及目标角闪烁的条件下 ,确定了拦截弹的控制方式由空气动力切换到复合控制时的切换时间。     

一类装甲车辆对不平路面的激励响应模型

研究内容为(轮式、履带)车辆在不平路面行驶和通过障碍时的平顺性问题。利用状态方程法建立了包括随机和确定路面轮廓、3维车体等较为通用的车辆行驶平顺性模型。并针对行驶振动中车轮与悬架的碰撞建立了专门模型。对某型装甲车辆进行了计算机仿真和验证,对模型的精度和有效性进行检验和评估。结果表明所建立的车辆-地面系统模型是有效的。该模型和建模采用的方法为装甲车辆的系统设计和动力学分析提供了一条途径。     

Designing and pricing menus of extended warranty contracts

Extended warranties provide “piece of mind” to a consumer in that product failures which occur after the base warranty expires are rectified at little or no cost. They also provide an additional source of revenue for manufacturers or third‐party providers, such as retailers or insurance providers, and help cultivate consumer loyalty. In this article, we analyze a number of extended warranty contracts which differ in design, including restrictions on deferrals and renewals. With the use of dynamic programming, we compute the optimal strategy for a consumer with perfect information and determine the optimal pricing policy for the provider given the consumer's risk characterization. We also provide insight into when different contracts should be issued. Finally, we illustrate how profits can be dramatically increased by offering menus of warranty contracts, as opposed to stand alone contracts, with the use of integer programming. Surprisingly, risk‐taking consumers provide the greatest benefit to offering menus. These insights can help a company develop a comprehensive warranty planning strategy for given products or product lines. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009     

基于系统动力学的协同决策模型性能分析

为探索信息化作战中指挥控制关键因素，提出改进作战指挥体制的对策措施，采用系统动力学理论，对协同决策的结构、参与者和信息反馈关系等关键因素进行了分析，在此基础上构建了基于系统动力学的协同决策模型并进行了模拟仿真。结果表明，增加指挥控制机构之间的信息共享可以有效提升协同决策的效率，为建立协同决策指挥控制体制提供了借鉴意义。     

Dynamic institutionalization: the foundations of Japan’s radioactive problem

Many have suggested that the true purpose behind Japan’s development of a closed nuclear-fuel cycle is to maintain the technical potential to develop nuclear weapons. However, closer examination of the development of Japan’s nuclear industry shows that, although Japan possesses advanced nuclear technologies, there has been no deliberate strategy to create a nuclear-weapon option. There is no “nuclear hedge.” To illustrate this point, this article presents a framework called “dynamic institutionalization” to explain the origins of Japan’s nuclear policies and the different sets of institutionalized pressures and constraints that have perpetuated these policies over time. Japan’s continued development of closed fuel-cycle technologies is primarily driven by domestic politics and the lack of a permanent spent-fuel management solution. On the other hand, Japan’s institutionalized nuclear forbearance is driven by the calculation that, as long as US extended deterrence remains credible, Japan’s security is best guaranteed through reliance on the US nuclear umbrella. By analytically untangling the policy of closed fuel-cycle development from the rationale for nuclear forbearance, this article provides a more nuanced view of the relationships between the domestic and international variables shaping Japan’s nuclear policies.     

制导航空子母炸弹高速抛撒分离数值仿真

制导航空子母炸弹在跨音速抛撒子弹药过程中，子弹药与母弹的分离伴随着复杂的流场和激波干扰，该过程中不仅存在着激波与激波的相互碰撞、部分激波的多次反射，而且由于受到多体运动的相互作用，其气流方向也发生变化，形成了变化复杂的压力、速度分布区域。采用数值模拟的方法对制导航空子母炸弹子弹药高速抛撒分离过程进行了数值仿真分析，应用嵌套网格技术，耦合多体动力学方程以及 N－S 方程求解子母炸弹高速分离过程，为工程设计、研究提供理论指导与计算依据。     

Military Spending,Conflict and External Debt in Sub-Saharan Africa

The damaging economic effects of the debt crises on Africa in the late 1980s encouraged considerable research on the determinants of external debt in developing economies. Although sub-Saharan Africa's (SSA) debt was cut by two-thirds by 2008, through two debt relief programmes, debt in the region has since been rising at an increasingly rapid pace. This study provides an empirical analysis of the determinants of external debt in SSA over the period 1960–2016, using dynamic panel methods. It also considers two potentially important factors that have received relatively little attention. One is military spending, rarely considered, despite a number of well-publicised scandals over the procurement of unnecessary and expensive high-tech weapons systems. A second, is the possibility that the countries studied have been involved in conflict. The empirical results point to a positive impact of military spending on external debt, but with some evidence of heterogeneity across the countries. Furthermore, findings indicate that the positive effect of military expenditure on debt becomes more marked in countries that have been affected by conflict. These results imply that policies to improve security and reduce military spending could be beneficial in reducing external debt and, potentially, improving economic performance in the region.     

Natural gas storage valuation and optimization: A real options application

In this article, we present an algorithm for the valuation and optimal operation of natural gas storage facilities. Real options theory is used to derive nonlinear partial‐integro‐differential equations (PIDEs), the solution of which give both valuation and optimal operating strategies for these facilities. The equations are designed to incorporate a wide class of spot price models that can exhibit the same time‐dependent, mean‐reverting dynamics, and price spikes as those observed in most energy markets. Particular attention is paid to the operational characteristics of real storage units. These characteristics include working gas capacities, variable deliverability and injection rates, and cycling limitations. We illustrate the model with a numerical example of a salt cavern storage facility that clearly shows how a gas storage facility is like a financial straddle with both put and call properties. Depending on the amount of gas in storage the relative influence of the put and call components vary. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009     

多轴越野车辆悬架部件结构优化设计

基于有限单元法、变密度方法和车辆动力学分析方法,对某型多轴越野车辆的典型部件(前悬架摆臂)主体进行了结构优化设计研究。结果表明:通过结构优化,降低了摆臂的质量,提高了摆臂的静态、动态结构刚度和强度。     

基于摆动式单线激光雷达的障碍物检测算法

基于无急回摆动机构,实现了单线激光雷达对周围区域环境的实时感知与建图。为了准确地检测障碍物,在讨论了摆动机构的安装标定及扫描帧与角度编码器对准方法的基础上,采用了一种生成可通行性代价地图(costmap)的算法。该算法以2-D栅格模型方式,通过综合高程信息、测量值个数、扫描帧个数和测量时间等信息,得到各栅格单元的代价值,生成一张关于环境可通行性代价地图。实车验证结果表明:基于该算法得到的地图能够较好地描述环境的可通行性,实现了对环境的实时感知。