空投气垫船航行阻力和螺旋桨动力的数值模拟及匹配研究

全垫升气垫船动力和阻力的计算和匹配问题的研究是其设计前期阶段的关键。基于STAR-CCM+流体计算平台和滑移网格模型分别对空投气垫船水面航行过程和螺旋桨气动特性进行了数值模拟,得到不同航速下的航行阻力和螺旋桨推力数据,综合分析研究了两者的匹配性问题。研究结果表明：兴波阻力随航速变化趋势和阻力峰出现位置均与相关文献和试验数据吻合,验证螺旋桨的推力计算结果与试验误差在6%以内,验证了CFD方法对气垫船航行阻力及螺旋桨动力模拟计算的可行性与有效性;将2款待选用的四叶和三叶螺旋桨气动性能与航行阻力匹配分析后,在发动机极限性能转速下,三叶螺旋桨能达到更高的最大航速,以20节速率巡航时,三叶效率更高,同时质量轻15%,综合说明三叶螺旋桨性能更佳。研究结果为该型气垫船的设计和选型提供重要的理论依据与数据支撑。     

朝鲜不对称作战的利器——全垫升气垫船

随着韩国大力发展水面舰艇增强其海上作战能力,形成对朝鲜的海上优势,朝鲜则不得不采用不对称作战方式应对来自韩国的海上重重压力,大量建造全垫升气垫船。阐述了朝鲜装备全垫升气垫船类型、性能特点及基本部署情况,分析了朝鲜发展气垫船的缘由;剖析了朝鲜采用气垫船实施登陆输送、特种攻击、海上突击和布设水雷障碍的具体使用方法;研究了韩国在反击朝鲜气垫船采取击毁基地、以空制海、以面制点、以远制近、以精确应对粗放的5种战法应对举措。     

渡海作战急先锋——气垫登陆艇

1999年9月上旬,中国人民解放军在南海举行的渡海登陆作战演习中,特别引人注目的是搭乘气垫登陆艇的攻击部队,快如利剑,劈开敌防线,登上滩头,登陆部队快速地向各高地发起攻击。气垫登陆艇是渡海作战先锋。参加南海渡海作战演习的气势登陆艇是我国自行研制成功随全垫升气垫船。———．。气垫船是一种高速船舶。船上按有能产生升为的风扇,把空气压缩注入船体。一形成所整,“”使船体能腾空飞行。气垫船名字也由此而来。＿、气垫船根据作用原理分为两类;一类是全垫升气垫版另一类是侧壁句垫船——、＿。－—一全垫升气垫船压缩空气山…     

我国早期的气垫船研制

<正>早在60年代,国外就掀起了对"气垫"这种产生升力的方式的研究,英国设计了横渡英吉利海峡使用的气垫船,美国研制了想供美国陆军在越南水田地区使用的气垫运输工具。当然,我国那时也开始包括气垫船在内的几种非常规航空器的研究,由国内科研院所以及一些著名专家牵头,利用有限的课题经费开展艰辛的探索。60多年来,通过研究、试验和运用,基本掌握全垫升式和侧壁式气垫船技术,适应了军民特种需要,为船舶在浅水     

扁平潜器前进与倒航稳定性评估

基于现有条件和针对扁平潜器的特点,由拖曳水池模型试验确定了攻角、漂角水动力,用经验方法近似估算了旋转水动力.用所得到的线性水动力系数,按照线性稳定性理论方法评估了扁平潜器正航和倒航下水平面、垂直面内的运动稳定性.将正航下水平面、垂直面内的运动稳定性计算结果与资料中类似的扁平潜器进行了比对分析,结果表明两者具有相同的稳定性特征,即垂直面内具有运动稳定性,而水平面内不具有航向稳定性.最后采用主推进器PD控制方法,用非线性运动模型数值仿真计算了主推进器控制作用下扁平潜器的运动.仿真计算结果表明,除了水平面倒航运动外,垂直面正航与倒航、水平面正航运动都可以通过主推进器的控制实现扁平潜器的运动控制.仿真计算结果还表明,在相同的PD控制参数下,航速愈低倒航对深度响应时间愈长.     

中国“鲸莎”Ⅱ级气垫登陆艇

在《现代舰船》2002年第2期“每月一舰”栏目中,提到了气垫艇作为登陆工具的优势,并谈到了中国也具有此类装备。中国于20世纪60年代起开始研制和开发气垫船,现已有侧壁式和全垫升式气垫船多型,其中民用产品较多,在军事运用方面仅限于作为交通艇和登陆工具。在军用气垫船中,值得一提的是“鲸莎”Ⅱ级气垫登陆艇,该级艇不但吨位较大,还是中国海军中首批采用燃气轮机作为动     

潜艇规避被动声自导鱼雷的航速和航向问题

研究了潜艇高频段辐射噪声、传播损失、鱼雷的干扰噪声级等影响鱼雷被动声纳方程的因素,定量分析了潜艇航速和航向对鱼雷被动声自导作用距离的影响,对潜艇规避处于被动声自导状态鱼雷的过程进行了模拟仿真,讨论了潜艇规避航速和航向对潜艇纯机动被动声自导鱼雷成功概率的影响,根据仿真统计得出了潜艇规避航速和航向的最优取值范围.     

全垫升式气垫船水压场数值模拟

提出了任意分布的气垫压力所产生的水压场的计算方法 ,对椭圆域上均匀分布的气垫压力产生的水压场进行了数值模拟 ,并将计算结果与实验进行了比较 .结果表明 ,用数值模拟的方法研究全垫升式气垫船水压场是可行的     

潜艇规避反潜潜艇平行航向法再搜索研究

对反潜游艇使用平行航向法再搜索进行了分析、建模,针对不同的初始距离、延迟时间对我潜艇采取不同的规避航向、航速进行了计算机仿真,得到了我潜艇机动规避成功概率较高的航向航速设置;并深入分析了初始距离和延迟时间对敌潜艇采用平行航向法再搜索发现我潜艇概率的影响,对我潜艇再搜索方法研究也有一定的参考价值.     

风作用下缆船拖带非线性系统运动数值模拟

基于船舶操纵性运动方程和拖缆的三维动力学运动方程,提出了被拖点位置匹配的方法,建立了拖船—拖缆—被拖船系统的非线性整体拖带动力学模型.为了考察被拖船航向稳定性与横向稳性的关系以及风载荷作用的影响,被拖船采用水平面四自由度运动方程,并引入了风的作用力和力矩.拖船采用PD控制方法较真实地模拟了拖船航向改变的运动过程.对一个拖船—拖缆—被拖船系统(5 000 t的拖船和3 000 t的被拖船)在时域内进行了风作用下拖带运动的模拟.计算结果表明,风力增大拖带航向稳定性降低,拖带航向稳定是横向稳的必要条件.数值计算结果归纳出判别被拖带船航向稳定性的极坐标图,该极坐标图表明顶风航行较顺风具有较强拖带航向稳定能力,但是拖带航向稳定性区域很小,而顺风和顺斜风拖带比顶斜风具有更大的拖带航向稳定性区域.     

Putin – the masked nemesis of the strategy of ambiguity

Recent events demonstrate the complex and adaptive approach employed by Russia to reassert influence in Europe. The changing face of Russia’s strategy commenced in 2007 when it launched a crippling cyber-attack against Estonia. This was followed by a large Russian conventional attack against Georgia in 2008, occupying two large areas of the nation. 2014 witnessed the Russian annexation of Crimea where in just a week, Russia seized control of Crimea “without firing a shot.” The annexation of Crimea was rapidly followed by a Russian inspired and led subversive war in eastern Ukraine. The common thread among these diverse Russian operations is its use of ambiguity to confound and confuse decision makers in the West.     

India's counter-insurgency experience: the ‘trust and nurture’ strategy

The Indian Army, a force trained primarily for conventional warfare, has been engaged in internal counter-insurgency operations since the 1950s. Despite such a long innings on a counter-insurgency mode, little attention has been accorded within military circles to doctrinal innovation for waging sub-conventional warfare in India's democratic political context. At best, the Army continues to view counter-insurgency duty as secondary to its primary duty of defending India from external conventional threats. By conceptualizing a counter-insurgency strategy of ‘trust and nurture’, this article aims to fill this critical doctrinal gap in India's military policy. The author argues that a counter-insurgency strategy of ‘trust and nurture’ based on democratic political culture, measured military methods, special counter-insurgency forces, local social and cultural awareness and an integrative nation-building approach will result in positive handling of India's internal security problems. The author utilizes India's counter-insurgency experiences in Assam, Mizoram, Nagaland, Punjab, and Operation ‘Sadhbhavana’ in Jammu and Kashmir as illustrative empirical indicants in order to validate the ‘trust and nurture’ strategy.     

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.