Model Versions and Fast Algorithms for Network Epidemiology

Network epidemiology has become a core framework for investigating the role of human contact patterns in the spreadingof infectious diseases. In network epidemiology, one represents the contact structure as a network of nodes（individuals） connected bylinks（sometimes as a temporal network where the links are not continuously active） and the disease as a compartmental model（whereindividuals are assigned states with respect to the disease and follow certain transition rules between the states）. In this paper, we discussfast algorithms for such simulations and also compare two commonly used versions,one where there is a constant recovery rate（the numberof individuals that stop being infectious per time is proportional to the number of such people）;the other where the duration of the diseaseis constant. The results show that, for most practical purposes, these versions are qualitatively the same.     

具有分布时滞的随机反应扩散细胞神经网络的几乎必然指数稳定性

研究一类具有分布时滞和反应扩散的随机细胞神经网络的稳定性。通过构造Lyapunov泛函,并利用It公式、半鞅收敛定理以及不等式技巧,得到了系统几乎必然指数稳定的充分条件。     

A note on necessary and sufficient conditions for ordering properties of coherent systems with exchangeable components

We give necessary and sufficient conditions based on signatures to obtain distribution‐free stochastic ordering properties for coherent systems with exchangeable components. Specifically, we consider the stochastic, the hazard (failure) rate, the reversed hazard rate, and the likelihood ratio orders. We apply these results to obtain stochastic ordering properties for all the coherent systems with five or less exchangeable components. Our results extend some preceding results. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

考虑有损伤测量条件下的设备剩余寿命的建模分析

在有损测量的情况下,仅从退化数据本身出发所建的模型不能反映设备的真实退化过程.尤其在测量导致的设备性能退化量不可忽略时,不考虑测量耗损量将不能有效进行预测和评估.为解决这个问题,首先基于维纳过程建立有损测量的设备退化过程,进一步给出了相应模型的参数估计方法和基于贝叶斯理论的设备剩余寿命的实时更新方法,最后通过一个仿真示...     

舰船经济寿命分析方法

针对舰船系统经济寿命的确定问题,介绍了舰船经济寿命分析5个阶段和舰船寿命周期费用的组成,给出了确定舰船经济寿命的方法。为装备更新决策提供依据,对武器装备的全寿命管理有一定参考价值。     

基于功率控制的水下声学传感器网络部署

目前对在传感器网络部署优化的研究中,主要集中在二维传感器部署优化的研究上,对水下三维传感器网络的部署研究特别是以优化网络资源、延长网络寿命为目的水下传感器网络非均匀部署的研究较少。改进了现有传感器探测模型,建立探测功率与传感半径的关系,结合体心立方格覆盖方案,建立了水下传感器网络非均匀部署模型,仿真实验表明,非均匀部署模型有效地控制了节点部署密度,平衡了网络能量,相对于均匀部署模型显著提高了网络寿命。     

随机理论雷达探测地面目标模型

雷达对地面目标的搜索效能是直升机对地作战效能评估的基础,建立雷达对地面目标搜索的数学模型,并分析几个因素对发现目标概率的影响,以及提高目标发现概率的方法,进而提高直升机的作战效能.模型有效地提高了雷达探测地面目标效能评估的准确性,对于指挥决策部门和设计单位有一定的参考意义.     

基于结构随机跳变系统的制导误差预测

针对空中目标作大机动时导弹制导误差难以预测的缺点,将导弹和目标视为一个结构随机跳变系统,并将目标作大机动当作系统的外部扰动输入,建立了该系统的数学模型,应用结构随机跳变系统理论对脱靶量的数学期望和方差进行了计算。通过仿真表明,该方法可对大机动目标进行制导误差预测,还可为变系数导引律的设计提供依据。     

基于遗传算法的装备使用保障费用灰色组合预测

针对目前对武器装备寿命周期费用估算建模难以实施的情况,以准确预测武器装备寿命周期费用的主要组成部分—装备使用保障费用为出发点,依据装备使用保障费用的特点建立了装备使用保障费用的灰色组合预测模型,指出了用蚁群算法优化组合权系数的不足,并提出了新的优化方法—遗传算法。最后,结合实例验证说明了该模型的预测效果优于蚁群优化的方法,为准确估算武器装备寿命周期费用提供了依据。     

On the first come–first served rule in multi‐echelon inventory control

A two‐echelon distribution inventory system with a central warehouse and a number of retailers is considered. The retailers face stochastic demand and replenish from the warehouse, which, in turn, replenishes from an outside supplier. The system is reviewed continuously and demands that cannot be met directly are backordered. Standard holding and backorder costs are considered. In the literature on multi‐echelon inventory control it is standard to assume that backorders at the warehouse are served according to a first come–first served policy (FCFS). This allocation rule simplifies the analysis but is normally not optimal. It is shown that the FCFS rule can, in the worst case, lead to an asymptotically unbounded relative cost increase as the number of retailers approaches infinity. We also provide a new heuristic that will always give a reduction of the expected costs. A numerical study indicates that the average cost reduction when using the heuristic is about two percent. The suggested heuristic is also compared with two existing heuristics. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007