视情维修模式下威布尔比例故障率模型

视情维修在提高装备的使用可用度、减少生命周期费用和提高维修保障效率等方面发挥了重要作用.在视情维修模式下,采用威布尔比例故障率模型描述了系统状态与故障率之间的关系,对伴随变量进行了相关性分析,以最大可用度为目标,建立视情维修的最优维修策略模型,并根据系统当前状态信息来判断装备是否已经达到最佳的维修时机.最后,对某型陀螺仪故障数据进行了实例分析,表明该方法在视情维修中的合理性和有效性.     

基于CBM的航空装备保障费用动态分析

目前航空装备的保障普遍存在保障费用高和装备可用度低的问题。针对视情维修(Condition-based Maintenance,简称CBM)在新一代航空装备中的应用,以保证航空装备的战备完好性,降低维修保障费用为目标,应用系统动力学原理,建立基于视情维修的航空装备保障费用的动态反馈结构模型。仿真结果表明,将视情维修方法应用到航空装备保障,可有效降低保障费用,提高战备完好率。     

基于历史数据的相控阵雷达T/R单元维修模型

为了减少大型相控阵雷达的停机维修次数,提高天线阵面T/R单元的保障能力,对累计故障数据进行建模,分析其故障分布规律,提出了一种多情况下的两级视情维修策略。建立了以天线阵面使用可用度为约束条件,单位时间维修费用为优化目标的视情维修模型,最后利用边际效能算法对参数进行求解。实例应用表明,该模型可以优化换件维修时机,换件维修人数等对天线阵面分系统保障效能的影响,为T/R单元维修策略提供理论支撑。     

不完备检测下视情维修的多级劣化系统性能评估

视情维修是改善多级劣化系统性能表现的重要措施,然而在实际中检测不完备问题会制约视情维修的有效开展,从而影响劣化系统性能评估结果。针对这一问题,将多级劣化系统检测维修马尔科夫链模型中的状态转移进行调整,建立其在不完备检测下进行视情维修的性能评估模型,给出系统性能参数的求解方法。实例验证表明:在实际工作中,虚警和漏检对于系统瞬态可用度的影响是随时间变化而不定的,但对于系统可靠度的影响则是确定的,即在任意时刻虚警提高系统可靠度,而漏检降低系统可靠度。     

视情工作间隔期的确定

针对大量设备的故障不会瞬间发生,为减少故障后果造成的损失并降低修复性维修的费用,采取了视情工作,检测费用随之增加。为使总费用最少,对检测间隔期进行了优化并给出简要的算法。同时对不同故障类型的视情工作的实施策略进行了讨论。     

多任务条件下地空导弹武器装备视情维修策略

针对地空导弹武器装备传统的维修方案难以预防装备故障的问题,提出采用视情维修策略,首先扩展了视情维修模型的研究范围,假设系统寿命服从威布尔分布,其次,给出了三种维修方案,在此基础上以系统可靠性最优为目标,建立了视情维修模型.仿真算例说明了该方法的可行性.     

考虑时间延迟的k/N(G)系统视情维修策略优化与仿真

针对传统的视情维修决策模型对时间延迟考虑不足的问题,建立了(m,L)视情维修策略下k/N(G)系统维修优化模型,提出了一种求解模型的数值迭代算法。通过仿真分析,得到了最优的视情维修阈值m和延误时间L,由此证明了该模型与算法的可行性。     

定期维护产品的维修策略研究

定期维护产品的视情维修策略往往没有考虑产品的维护特点,导致处理结果无法准确反映工程需要。为此,首先根据定期维护特点,应用非齐次泊松过程描述产品失效过程,在此基础上,提出了与实际过程更为相符的维修策略;然后,通过分析定期维护产品的工作时间和维修费用,以产品生存风险为约束,平均维修费用率最低为优化目标,建立了该策略下的维修优化模型,给出了优化模型的求解算法,并进行了实例验证分析。结果表明:该维修策略可以有效地延长产品寿命并降低维修费用。     

引入区域量化的相控阵天线维修优化模型

针对大型相控阵天线维修成本高、多部件维修时机难以确定、模型仿真计算困难等问题,提出一种引入区域量化的维修优化模型。建立天线阵列的区域量化模型,将天线阵列维修问题转化成一个由不同区域阵元组成的k/n系统维修优化问题。以使用可用度为约束条件,以单位时间维修费用最小为优化目标,建立引入区域量化的大型相控阵天线多部件视情维修决策优化模型,并通过算例仿真与分析进行了模型验证。结果表明:提出的维修优化模型真实有效,能够很好地解决分布不均匀的相控阵天线维修优化问题。     

相控阵天线阵面T/R单元维修模型

为了提高相控阵天线阵面T/R单元的保障能力,提出了一种多情况下的两级维修保障策略。当天线阵面T/R故障单元达到一定阈值时,雷达停机开始维修。建立了以天线阵面使用可用度为约束条件,单位时间维修费用最少为目标的视情维修模型,最后利用边际效能算法对参数进行了求解。实例应用表明,该模型可以优化换件维修时机,换件维修人数等对天线阵面分系统保障效能的影响,为T/R单元维修策略提供理论支撑。     

An Unlikely Alliance: Portuguese and South African Airpower in Angola, 1968–1974

The war that Portugal was obliged to fight in Africa began in 1961 and immediately stretched the resources of its armed forces. Nowhere was this thinness more apparent than in policing the vast territory of Angola. The east and southeast of Angola were particularly vulnerable, as the area was a vast, sparsely populated region characterised by enormous featureless plains or chanas covered in tall grass and broken by an extensive river system and mountainous forests. The only military solution to policing these immense spaces was aviation and specifically the helicopter that could carry troops into battle, protect them with a gunship and bring them home when the operation was concluded. The immediate problem for the Portuguese Air Force (Força Aérea Portuguesa or FAP) in Angola and elsewhere was a scarcity of helicopters. The solution was an alliance with South Africa, which had a strong inventory of Alouette IIIs, to help in policing the east. This move was likewise in the interest of South Africa, as its threat came from Zambia through south-eastern Angola. This article examines the strategic and tactical development of this unusual, cross-cultural alliance and the symbiotic relationship that resulted in destruction of the enemies of both in Angola.     

国内外结构钢焊条研究的现状与发展

本文主要介绍了国外焊条的现状和发展趋势,包括焊条的高韧性、高效率、低尘低毒和耐吸潮性能,为国内的焊条研究提供了参考依据。     

A Sign of Victory?: ‘Scottish Swords’ and Other Weapons in the Possession of the ‘Auld Innemie’

Many late medieval documents, notably inventories of arms and armour, of Englishmen contain references to ‘Scottish swords’ and other weapons. What did the compilers of these documents mean when they described a weapon as ‘Scottish’? How did such weapons come to be in the possession of these men? This article will attempt to explain this phenomenon drawing on primary documentary sources and surviving material culture from Glasgow Museums’ collections and others, as well as artworks from the period.     

Helping hands: civil–military cooperation and Italy's military operation abroad

In the Post-Bipolar Era the growing complexity of the military operations requires a new approach for the resolution of international crises. Since the end of the Cold War, peace support operations (PSO) have become the mainstay and principal occupation of most Western armies. At the same time, Italy has been one of the most important actors in such an area. The article focuses on the cooperation between military and civil components (a process called CIMIC) as a key variable in the Italian PSOs. We will analyse in detail the main lessons learned from past military interventions as well as the general context in which new tendencies are taking place. The maintaining of a minimum security frame becomes essential to fulfil activities ‘collateral’ to the mission: reconstructing services and infrastructure, food distribution, water and medication, law and order, de-mining, training of local forces, and supporting local institutions. These are the main tasks to obtain thrust and support from the population.     

Terrorism,insurgency, kidnapping,and security in Africa's energy sector

Energy continues to serve as the bedrock of modern economies and the main driver of modern society. For Africa, the production and supply of energy resources such as crude oil, natural gas, uranium, coal, biomass, biofuels and other renewables are an important source of employment, rents, taxes, royalties and profits. This sector brings in several tens of billions of dollars of revenue annually. The production and delivery of such resources, however, depend on critical infrastructures such as pipelines, refineries, processing plants, terminals, rigs, electrical energy pylons, substations, pump stations, vessels, and tankers. These infrastructures have been attacked by terrorists, insurgents, vandals and saboteurs, all of whom see them as targets against which to register their grievances and extract concessions from the state. This paper is a chronological account of some of the documented incidents of terrorism, insurgency, kidnapping, destruction, sabotage, and human casualties suffered in the oil and gas sectors in Africa between 1999 and 2012. It is based on data extracted from the databases of the RAND Database of World Terrorism Incidents and the University of Maryland's Global Terrorism Database (GTD).     

Cyberpower in Strategic Affairs: Neither Unthinkable nor Blessed

Abstract

This article explores the effect of connectivity on strategic affairs. It argues that the effect on war's character is potentially, although not yet shown in practice, considerably large. Its effect upon the distribution of power among states in the international system is small, contrary to the claims of ‘cyberwar’ alarmists. All told, however, its effect upon strategic affairs is complex. On the one hand, it represents a significant advance in the ‘complexification’ of state strategies, understood in the sense of the production of intended effects. On the other hand, strategists today – still predominantly concerned with the conflicts and confrontations of states and organised military power – are generally missing the power which non-traditional strategic actors, better adapted to the network flows of the information age, are beginning to deploy. These new forms of organization and coercion will challenge the status quo.     

Tacit support for terrorism: The rapprochement between the USSR and Palestinian guerrilla organizations following the 1967 war

This article demonstrates the inconsistent and wavering Soviet attitude towards national liberation movements in general and the Palestinian organizations in particular. Until the late 1960s, the Soviets viewed these organizations with suspicion, hesitating to engage in political dialogue with them. However, in the 1970s, political and military events in the region, as well as modifications in the Kremlin's Cold War strategies, led to a general shift towards the Middle East in Soviet foreign policy. Soviet leaders showed increased willingness to provide certain Palestinian organizations with arms with which to conduct terrorist activities against Israeli, pro-Israeli, Jewish and Western targets. The article explores the complex relations between Palestinian organizations and the USSR in the field of international terror. The study also exposes and analyzes the nature and content of Soviet–Palestinian arms dialogues and transactions. It provides clear evidence that Soviet policymakers and other luminaries were fully informed of, and sometimes directly involved in, these transactions and dialogues at the highest levels.     

A1 Qaeda and the radical Islamic challenge to western strategy

The September 11 global crisis prompted by the attacks on the World Trade Center and the Pentagon raises major questions concerning the nature and trajectory of terrorism in the post-Cold War global order. Hitherto, terrorism has been largely debated by analysts at the level of nation states. Terrorist and insurgent movements have also been largely anchored in nationalist and ethnic power bases even when they have sought to mobilise a transnational ideological appeal on religious or class grounds. There have been a few exceptions to this pattern such as the alliance between the German Baader-Meinhof group and the Japanese Red Army Faction, but even such international alliances as this did not, until at least the 1980s, presage anything like a global terrorist network necessitating a global strategic response. This study examines terrorism and global strategic responses.