Optimal burn‐in procedure for periodically inspected systems

Burn‐in is a widely used method to improve the quality of products or systems after they have been produced. In this paper, we study burn‐in procedure for a system that is maintained under periodic inspection and perfect repair policy. Assuming that the underlying lifetime distribution of a system has an initially decreasing and/or eventually increasing failure rate function, we derive upper and lower bounds for the optimal burn‐in time, which maximizes the system availability. Furthermore, adopting an age replacement policy, we derive upper and lower bounds for the optimal age parameter of the replacement policy for each fixed burn‐in time and a uniform upper bound for the optimal burn‐in time given the age replacement policy. These results can be used to reduce the numerical work for determining both optimal burn‐in time and optimal replacement policy. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

采用神经网络技术降低机电设备BIT虚警

机电设备 Ｂ Ｉ Ｔ 的突出问题是虚警率高，重要原因之一是 Ｂ Ｉ Ｔ 系统传感器通路故障。本文选取神经网络技术进行传感器通路故障诊断，剖析某大型船舶动力装置机电设备 Ｂ Ｉ Ｔ 系统中传感器通路的故障机理和类型，得到其故障样本数据，经过神经网络学习训练后对实际系统进行故障诊断和识别，实验结果表明该方法简洁、有效，能够有效地诊断故障并识别出故障类型，具有实用价值。     

身管内弹道性能改变量的静态标定研究

目前国内外静态标定火炮身管内弹道性能改变量的方法,都存在着原理和精度不高的缺陷。采用多特征截面的标定方法可取得满意的精度,本文论述了其理论基础、精度及应用领域。     

Think again – supplying war: reappraising military logistics and its centrality to strategy and war

This article argues that logistics constrains strategic opportunity while itself being heavily circumscribed by strategic and operational planning. With the academic literature all but ignoring the centrality of logistics to strategy and war, this article argues for a reappraisal of the critical role of military logistics, and posits that the study and conduct of war and strategy are incomplete at best or false at worst when they ignore this crucial component of the art of war. The article conceptualises the logistics–strategy nexus in a novel way, explores its contemporary manifestation in an age of uncertainty, and applies it to a detailed case study of UK operations in Iraq and Afghanistan since 2001.     

Numerical simulation of the blast wave of a multilayer composite charge

The numerical simulation of a blast wave of a multilayer composite charge is investigated. A calculation model of the near-field explosion and far-field propagation of the shock wave of a composite charge is established using the AUTODYN finite element program. Results of the near-field and far-field calculations of the shock wave respectively converge at cell sizes of 0.25–0.5 cm and 1–3 cm. The Euler––flux-corrected transport solver is found to be suitable for the far-field calculation after mapping. A numerical simulation is conducted to study the formation, propagation, and interaction of the shock wave of the composite charge for different initiation modes. It is found that the initiation mode obviously affects the shock-wave waveform and pressure distribution of the composite charge. Additionally, it is found that the area of the overpressure distribution is greatest for internal and external simultaneous initiation, and the peak pressure of the shock wave exponentially decays, fitting the calculation formula of the peak overpressure attenuation under different initiation modes, which is obtained and verified by experiment. The difference between numerical and experimental results is less than 10%, and the peak overpressure of both internal and external initiation is 56.12% higher than that of central single-point initiation.     

村民自治对农村社会稳定的双面效应

村民自治对农村社会稳定起着正面效应;异化的村民自治对农村社会稳定起着负面效应。鉴于此,为在农村社会发展中实现农村社会稳定,就要不断强化其正面效应,弱化其负面效应。     

群体性上访事件对警卫工作的影响及对策

在警卫工作中,群体性上访事件不仅威胁警卫对象、警卫目标、重要会议和重大活动的安全,而且处置不好还会损害党和国家的政治形象与国际形象。警卫工作中预防和处置群体性上访事件,首先要提高预警能力;其次要进行充分的处置准备,在具体处置时要注意运用正确的策略和方法,既要维护群众的根本利益,又要降低负面影响。     

毽球运动在新疆中小学推广的可行性分析

本文通过介绍毽球的特点,从新疆中小学体育教育现状出发,探讨毽球这项民族传统体育项目在新疆中小学体育教学中推广的必要性和可行性,为丰富当前中小学体育教学课程资源提供一些方法、手段和思路,并对民族传统体育项目的传承有积极意义。     

装备战斗恢复力模糊评判模型的建立与应用

针对装备战斗恢复力的评价具有随机性、模糊性和相关性的特点 ,提出了用模糊评判模型分析装备战斗恢复力的方法。最后 ,以雷达系统为例 ,对该模型进行了应用分析     

基于邻域灰度分布的IR弱小目标检测

图像中邻域内灰度起伏程度越大 ,各点灰度值占邻域内总灰度值的比率的平方和越大 ,由此提出了一种基于邻域灰度分布的弱小目标检测方法。同时考虑到复杂自然背景 ,特别是背景中含有大量边缘和高频点的情况 ,提出了目标检测的改进方法。最后 ,利用邻域判决法实现运动目标的进一步分离。实验表明该方法能够极大地减少候选目标点数 ,准确有效地检测复杂自然背景中的红外运动弱小目标 ,适合于实时和多目标的检测