Classical geopolitics,realism and the balance of power theory

Since the end of World War II, classical geopolitics as a particular form of realism has been disengaged from the development of mainstream realist theories. This disengagement has not only concealed the value of classical geopolitics as a framework of analysis for policy and strategy, but also created an increasing rift between theory and policy in contemporary realist theories. This paper seeks to reengage classical geopolitics with mainstream realist theories by clarifying its realist traits and analytical characteristics, (re)stating its core propositions and probing into its potential contribution to the development of mainstream realist theories. This paper contends that classical geopolitics, while having a distinctive pedigree, can arguably be considered an integral part of the family of realist theories in view of its basic theoretical assumptions concerning international anarchy, the unit of analysis and power politics. As a framework of analysis, classical geopolitics incorporates three interrelated strategic propositions. Those three propositions not only constitute the theoretical core of classical geopolitics, but also manifest a peculiar balance-of-power conception that is essentially distinct from those proposed by mainstream realist theories. This paper argues that those three propositions combined promise to fill in prominent lacuna in the balance-of-power research programme, and also have significant implications for contemporary world politics.     

电磁轨道发射中内弹道动力响应特性分析

将轨道简化为移动载荷作用下固定在弹性支撑上的Bernoulli-Euler梁,通过静态电磁-结构耦合有限元模型求得外围封装的等效刚度,计算得到发射器的临界速度。另外,利用混合有限元/边界元法建立电磁-结构-运动多物理场耦合的动力学模型,求得枢轨动态接触压力和轨道的应力应变分布特性。通过在轨道背面布置光纤光栅应变传感器,利用测量数据验证了动力响应特性,并分析了弹丸在内弹道的稳定性。针对典型30 mm × 30 mm矩形口径发射器,分析及试验结果表明：C型电枢对轨道的电磁挤压力在平顶沿起始时刻达到最大值,之后随着时间推移逐渐减小;电枢通过引起的应力波在高速段容易与轨道中反射应力波发生共振,并且轨道在电枢运动的中间高速段区域受力最为集中,应力集中水平约是起始低速段区域的2.44倍;电枢运动高速段会出现晃动现象,进而引起上下轨道受力的不对称性。分析及试验结果对研究电磁轨道发射器内弹道动力响应特性和发射器结构设计具有重要指导意义。     

动态武器目标分配问题的马尔可夫性

动态武器目标分配(weapon target assignment,WTA)问题是军事运筹学研究的重要理论问题,也是作战指挥决策中迫切需要解决的现实问题。在对动态WTA问题进行描述分析的基础上,运用随机过程理论证明了动态WTA过程的马尔可夫性;给出了该马尔可夫决策过程的状态转移概率的解析表达式,并对其状态特点进行了简要分析。研究结果可以为动态WTA及相关问题的研究提供理论和方法依据。     

深度神经网络指导下的无线覆盖预测算法

为保证新一代移动无线网络能够根据实时覆盖情况动态地调节小区天线参数,需要实现高效且准确的无线覆盖预测。传统的求解方法通过精确的场强预测判断天线参数的优劣,虽然精度很高但需要大量的计算资源,无法满足5G和后5G移动网络通过实时覆盖预测进行射频参数动态调整的实际需求。现采用基于深度神经网络的算法对给定天线参数的覆盖效果进行预测,以取代对目标区域的精确场强预测。数值结果表明:该方法能够在保持计算准确性的同时显著减少计算量,为5G动态网络规划提供基础性参考数据。     

Novel approach for active vibration control of a flexible missile

This paper investigates the feasibility of using an active dynamic vibration absorber (ADVA) for active vibration control of a flexible missile system through simulation. Based on the principles of a dynamic vibration absorber (DVA), a ring-type ADVA is first designed to attenuate the elastic vibration of the flexible missile, and the design of the active controller adopts the proportional-integral-derivative (PID) control algorithm. The motion equations of a flexible missile with an ADVA, which is subjected to follower thrust at its aft end, are derived using the Lagrangian approach. Taking the minimum of the root mean square (RMS) of the lateral displacement response of the center of mass as the objective function, a genetic algorithm (GA) is used to optimize the parameter of the DVA and PID controller. The numerical calculations show that the ADVA and DVA are effective in suppressing the vibration and provide approximately 41.2% and 17.6% improvement, respectively, compared with the case of no DVA. The ADVA has better performance than the DVA. When the missile is subjected to follower thrust, the effect of vibration reduction is more effective than the case without follower thrust. It is feasible to reduce vibration and improve the stability of flexible missiles by means of the ADVA.     

Replacing nonidentical vital components to extend system life

We consider a system that depends on a single vital component. If this component fails, the system life will terminate. If the component is replaced before its failure then the system life may be extended; however, there are only a finite number of spare components. In addition, the lifetimes of these spare components are not necessarily identically distributed. We propose a model for scheduling component replacements so as to maximize the expected system survival. We find the counterintuitive result that when comparing components' general lifetime distributions based on stochastic orderings, not even the strongest ordering provides an a priori guarantee of the optimal sequencing of components. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

A parallel machine replacement model

This paper considers a finite horizon parallel machine replacement problem where a fixed number of machines is in operation at all times. The operating cost for a machine goes up as the machine gets older. An older machine may have to be replaced by a new one when its operating cost becomes too high. There is a fixed order cost associated with the purchase of new machines. Machine purchase prices and salvage values may depend on the period in which they were purchased. The objective is to find a replacement plan that minimizes the total discounted cost over the problem horizon. We believe that the costs in our model are more commonly observed in practice than those previously used in the literature. The paper develops properties of optimal solutions and an efficient forward‐time algorithm to find an optimal replacement plan. A dominance property is developed that further limits the options to be considered, and a simple forecast horizon result is also presented. Future research possibilities are mentioned. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 275–287, 2002; Published online in Wiley InterScience (http://www.interscience.wiley.com). DOI 10.1002/nav.10012     

磁悬挂天平的变结构控制

鉴于磁悬挂天平系统强烈的非线性特性及存在的多种不确定性 ,针对非匹配不确定性情况设计了变结构控制器。根据对悬浮时模型受力图的分析及其模型两端电磁力、电流和电压的平衡关系 ,并以Y轴方向受力为例 ,讨论了磁悬挂天平的非线性变结构设计过程。该设计的目的是使镇定误差趋近于 0 ,其设计步骤包括期望性能到期望力的传递、满足滑动模态可达条件的控制力到控制电压的传递、控制电压的求解。同时对设计的结果进行了仿真分析 ,仿真结果表明磁悬挂天平的变结构控制系统具有良好的动态性能     

某型小口径高炮动态跟踪系统误差分析

在该型小口径高炮系统的指标中,对于高炮动态射击精度、火控跟踪精度和随动系统精度都是既有随机误差要求,又有系统误差要求.将火控动态跟踪系统误差作为非常重要的考核指标,却与外场测试结果有差别.从动态跟踪系统误差的产生、分类和内涵出发,通过建立动态跟踪数学模型,并结合作图对其原由进行了深刻的分析.     

基于Petri网的近程防空武器射击建模

提出一种扩展时延Petri网,新提出的Petri网与以往高级时延Petri网的不同之处在于它允许个体的个性与共性同样得到考虑。这种方法被用来对装备多跟踪装置、多种对空武器的防空系统对多目标进行射击过程进行建模、分析、模型的正确性在文章最后的仿真中得到了验证。