基于遗传算法的导管-气室系统参数优化研究

导管-气室系统可以引发水力共振,提高脉冲射流的强度。影响水力共振的 主要因素有导管长度、导管内径、喷嘴出口内径、调制频率和气室初始容积等,采用搜寻的方 法无法获得最优解。遗传算法具有隐合并行性和全局解空间搜索的特点,利用遗传算法能 有效地对导管-气室系统的主要参数进行优化设计,获得最优解来指导实验装置的设计。     

基于模糊理论的空袭目标威胁判断模型

对空袭目标威胁度进行合理排序是提高防空效能的重要因素。分析了影响空袭目标威胁度的各种因素,利用模糊综合评判的思想,建立了一种进行目标威胁判断的模型,并根据具体情况给出了排序的合理方法。通过实例,给出了具体的计算过程,并将此方法得出的结果与文献中的方法得出的结果进行了比较,充分说明了模型的可行性。     

The Afghan model in northern Iraq

In Operation ‘Iraqi Freedom’, as the Coalition's heavy forces fought in the South, in the North a handful of special operations forces, working with Kurdish rebels, clashed with the Iraqi army along the Green Line. In operations reminiscent of those used a year earlier to defeat the Taliban in Afghanistan, the lightly armed and heavily outnumbered Coalition forces called in air strikes to defeat Iraq's regular and Republican Guard army divisions. This article tells the story of these operations and discusses some of their implications for future US military policy. The success of the Afghan model in Iraq goes a long way toward demonstrating the efficacy of new air-heavy tactics and shows the strategic value of using light indigenous allies to replace heavy US land forces in both conventional combat and occupation operations.     

The 1950 ‘Ambassador's agreement’ on USAF bases in the UK and British fears of US atomic unilateralism

The article explores the 1950 ‘Ambassador's Agreement’ (named after US Ambassador Lewis Douglas) about establishing long-term US air bases in the UK. During the discussions British representatives expressed resentment of American pressure and were concerned about the expense that developing the bases for American purposes might entail. There were even fears that Washington might use the airfields to launch an atomic bomb attack on the USSR without regard to the views of the UK government. The British consented to providing the bases because they wanted to enmesh the US further in UK and Western European defence. For their part American negotiators had wanted to further US atomic strategy without delay. Although the agreement imposed no restriction on the use of the airfields, some US officials believed that in a crisis the UK government might try to prevent them being used for atomic bombing missions.     

Analysis of the finite‐source multiclass priority queue with an unreliable server and setup time

In this article, we study a queueing system serving multiple classes of customers. Each class has a finite‐calling population. The customers are served according to the preemptive‐resume priority policy. We assume general distributions for the service times. For each priority class, we derive the steady‐state system size distributions at departure/arrival and arbitrary time epochs. We introduce the residual augmented process completion times conditioned on the number of customers in the system to obtain the system time distribution. We then extend the model by assuming that the server is subject to operation‐independent failures upon which a repair process with random duration starts immediately. We also demonstrate how setup times, which may be required before resuming interrupted service or picking up a new customer, can be incorporated in the model. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

基于动网格的翼型设计优化

针对传统基于代理模型的翼型优化的缺陷,提出采用基于动网格的翼型优化;针对基本Hicks-Henne方法后缘不光滑情况进行了改进;采用自编程序实现动网格生成,通过集成商业软件Pointwise和CFD计算软件Fluent完成边界条件生成和流场解算,并实现上述程序和软件间的数据交互和自动化,整个优化流程在iSIGHT平台下执行,优化算例表明基于动网格的翼型优化方法能大幅提高翼型性能,节省大量的重复性操作,增加优化结果的鲁棒性和可信度,是翼型优化中的一种有效方法。     

The use of undercover military units in counter-terrorist operations: a historical analysis with reference to contemporary anti-terrorism

This article examines the use of specialised plain-clothes military units in counter-terrorism, concentrating on examples involving liberal-democratic states. It analyses the benefits and problems arising from clandestine military activity, focusing in particular on British army units (notably 14 Intelligence Company and the Force Research Unit in Northern Ireland). The article concludes by arguing that such formations have a clear utility – notably in gathering intelligence on terrorist groups – but other aspects of their role are inherently controversial (notably in cases where undercover soldiers use deadly force against suspected terrorists). It also states that plain-clothes military operations need to be conducted on the basis of accountability, both for strategic reasons, and also in accordance with the norms of liberal democracy.     

Exporting professionalism: US efforts to reform the armed forces in the Dominican Republic and Nicaragua, 1916–1933

Why did the United States, a country notorious for supporting coups and military dictatorships in Latin America during the Cold War, seek to depoliticize security forces in the Caribbean basin during the early twentieth century? Drawing from primary sources, I argue that this emphasis on military non-partisanship abroad stemmed from Progressive Era reforms popular at home. These reforms, which stressed bureaucratic efficiency via nonpartisan expertise, had become institutionalized within the US military and State Department and then channelled into the imperial administration of Nicaragua and the Dominican Republic. The State Department and Marine Corps attempted to replace local partisan armies with the kind of professional, nonpartisan armed forces that the US's own military had come to exemplify. That these civil-military reform efforts ultimately backfired should serve as a reminder of the difficulties inherent in using military interventions to transform coercive apparatuses and their societies.     

Lessons in airpower projection: Indochina and Algeria

The lessons from the two French counterinsurgencies, Indochina and Algeria, give rise to a new understanding of the projection of airpower in remote and hostile environments and the purpose, design, and use of aircraft in counterinsurgency. In both Indochina and Algeria, the campaigns were ones of poverty, and it is their imaginative management under severe resource constraints that provides thoughtful and applicable lessons for today. In both cases, airpower held the promise of delivering victory and solving the resource issue. In Indochina, acquisition of the needed aircraft, operating knowledge, and experience came too slowly to realize this promise. In Algeria, the French embraced the lessons from Indochina and were quite successful and innovative in the use of airpower. The lessons can be reduced to four requirements: (1) a network of airfields for liaison, ground-support, and intra-theater airlift to enable effective air support of ground forces; (2) a solid, reliable, and simple ground-support aircraft capable of operating from forward airfields within range of ground engagements; (3) a capable intra-theater heavy-lift transport to supply the extended ground forces; and (4) helicopter capability to enhance tactical troop mobility and support.     

The missing dimension: IDF special operations forces and strategy in the Second Lebanon War

In the course of the 2006 Lebanon War the Israel Defense Forces (IDF) employed special operations forces (SOF) for raids against Hizb'allah's command and control structure. This article argues that a faulty conceptualization of the value of special operations and misguided expectations determined by the new IDF concept of operations impacted adversely on the employment of SOF for this kind of operations. Both these elements contributed in turn to substantially degrade SOF performance in the context of the war.