Specialization in defence forces

The choice between balanced and specialized defence forces depends on the technology of defence output (e.g. whether a force scope multiplier is present), the existence of scope and scale economies, the platform customization costs and, of course, the level of defence budgets. Minimum force element levels (thresholds), and scale economies facilitate specialization as opposed to scope economies (e.g. platform‐sharing), scale diseconomies and the force scope multiplier (e.g. defence weakest‐link technology). When a balanced force is not optimal, the option value of a non‐optimally maintained force element must also include the opportunity cost arising from suboptimal force elements. Shrinking defence budgets may produce two surprising phenomena. If some force elements are shut down as a result of thresholds, the surviving ones may increase in platform numbers as well as enjoying closer‐to‐most‐desirable platforms. Furthermore, if heritage force elements are shut down within the budget contraction environment, overall defence capability might rise.     

Military expenditure and employment in South Africa*

Previous research into the impact of military expenditure on employment finds considerable variation across countries. This paper adds to the debate by examining the long run relationship between military burden and manufacturing employment in South Africa. Such an analysis provides an opportunity to test for crowding‐out effects and the impact of the marked decline in military spending on the South African economy. The paper finds evidence supporting the view that military expenditure will have a detrimental impact on long term manufacturing employment, adversely affecting industrial structure and efficiency.     

二阶阶跃模型下导航信号畸变对接收机载噪比估计影响分析

载噪比作为评估导航信号质量的重要指标,直接影响着接收机的捕获、跟踪和电文解调性能。推导了基于国际民航组织二阶阶跃信号畸变模型下导航接收机采用相关、非相关处理时载噪比估计与畸变模型参数之间的解析表达式,并分析了畸变参数对导航接收机载噪比估计误差的影响。理论分析及仿真结果表明:数字畸变参数变化范围下导航信号载噪比变化在10-2量级,增大模拟畸变的振荡频率或者减小衰减频率将会提高载噪比估计值,模拟畸变参数变化引起的载噪比损耗可达0.1d BHz,畸变参数对载噪比估计的影响整体上都较小,因此导航接收机的载噪比输出不能作为监测导航信号是否异常的完备检测量。     

小子样条件下战斗部爆炸仿真数据可信性分析

高效毁伤战斗部试验次数受到严格控制,如何在小子样条件下分析仿真数据的可信性非常有必要。通过均匀试验得到了战斗部在地下目标腔室内部爆炸某点冲击波最大超压峰值,利用normplot及Lilliefors函数分析了仿真数据的分布特征,而后在已有检验方法的基础上,结合顺序统计量和均匀分布的特点提出了一种新的相容性验证思路。研究表明:该方法不受样本容量的限制,利用MATLAB程序编程可以快速判断仿真数据的可信性。     

基于单变量多目标规划的装甲车辆冷却系统智能化控制

根据新一代装甲车辆推进系统热部件散热特点及其冷却系统调控原理,提出了一种单变量多目标数学规划与模糊智能控制相结合的控制算法。该算法将冷却系统抽象为单变量多目标数学规划问题,采用加权的方法将多个目标函数转化为综合目标函数,输入到模糊智能控制器中进行冷却控制。仿真结果表明:该控制算法具有良好的控制效果,能够有效地解决新型推进系统热源多、目标温度范围广而可调参数单一的问题。     

屋面太阳能电池布设优化模型

以光伏电池接受太阳能辐射强度最大化为目标,建立了太阳能电池板倾角和朝向优化模型,以确定太阳能电池板的最佳布设方式。根据发电量最大化、单位发电费用最小化原则,以净经济效益为目标函数,建立了光伏电池优选模型,对光伏电池进行优选排序从而选出性价比最高的光伏电池,并对模型进行了检验。结果表明：在山西省大同市地区铺设太阳能光伏电池,架空布设电池板的最佳倾角为36°,朝向为南偏西26.5°,光伏电池板最佳布设方式及电池优选模型与实际情况基本相符。     

A mathematical formulation and efficient heuristics for the dynamic container relocation problem

The container relocation problem (CRP) is concerned with emptying a single yard‐bay which contains J containers each following a given pickup order so as to minimize the total number of relocations made during their retrieval process. The CRP can be modeled as a binary integer programming (IP) problem and is known to be NP‐hard. In this work, we focus on an extension of the CRP to the case where containers are both received and retrieved from a single yard‐bay, and call it the dynamic container relocation problem. The arrival (departure) sequences of containers to (from) the yard‐bay is assumed to be known a priori. A binary IP formulation is presented for the problem. Then, we propose three types of heuristic methods: index based heuristics, heuristics using the binary IP formulation, and a beam search heuristic. Computational experiments are performed on an extensive set of randomly generated test instances. Our results show that beam search heuristic is very efficient and performs better than the other heuristic methods.Copyright © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 101–118, 2014     

Bicriteria multiresource generalized assignment problem

In this study, we consider a bicriteria multiresource generalized assignment problem. Our criteria are the total assignment load and maximum assignment load over all agents. We aim to generate all nondominated objective vectors and the corresponding efficient solutions. We propose several lower and upper bounds and use them in our optimization and heuristic algorithms. The computational results have shown the satisfactory behaviors of our approaches. © 2014 Wiley Periodicals, Inc. Naval Research Logistics, 61: 621–636, 2014     

Improved bounds for batch scheduling with nonidentical job sizes

Here, we revisit the bounded batch scheduling problem with nonidentical job sizes on single and parallel identical machines, with the objective of minimizing the makespan. For the single machine case, we present an algorithm which calls an online algorithm (chosen arbitrarily) for the one‐dimensional bin‐packing problem as a sub‐procedure, and prove that its worst‐case ratio is the same as the absolute performance ratio of . Hence, there exists an algorithm with worst‐case ratio , which is better than any known upper bound on this problem. For the parallel machines case, we prove that there does not exist any polynomial‐time algorithm with worst‐case ratio smaller than 2 unless P = NP, even if all jobs have unit processing time. Then we present an algorithm with worst‐case ratio arbitrarily close to 2. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 351–358, 2014     

基于EVALPSN的循环式多轿厢电梯避撞设计与实现

多轿厢电梯系统作为垂直运输的新方式,避免轿厢之间的碰撞成为了其安全运行急需解决的重要问题。根据循环式多轿厢电梯控制系统的轿厢安全运行准则,分析了循环式多轿厢电梯系统的避撞控制问题,研究了基于带有强否定的扩展矢量注解的逻辑规划方法,设计一种电梯轿厢安全避障方法。通过建立了禁止轿厢危险运行的EVALPSN算式,避免了派梯中所选轿厢在井道中发生碰撞,保证电梯控制系统的安全运行,实验结果表明:所设计的方法针对循环式多轿厢断电梯避撞问题有较好的效果,可有效地保证多轿厢运行的安全性。