损伤铝合金表面超声焊接界面断口分析与结合机理

采用超声焊接铝合金箔材的工艺修复处理表面腐蚀受损的2A12CZ基体,并利用Quanta200型环境扫描电子显微镜分析了截面形貌及箔材与基体之间界面表面断口的微观形貌。结果表明：从截面来看,箔材与基体之间大部分发生了焊合,界面分界线大部分消失;从机械脱开的界面断口来看,其表面微观形貌表现为鳞片状及韧窝状的典型金属型断口形貌。这说明在给定条件下,焊接部位大部分呈冶金结合。最后对铝台金箔材与铝合金基体之间超声焊接机理进行了探讨。     

黏结剂和纤维对石蜡微胶囊保温砂浆抗裂性影响

采用黏结剂增强石蜡微胶囊保温砂浆内部微粒间的结合力,分析了黏结剂类型和掺量对石蜡微胶囊保温砂浆抗折强度、黏结强度和韧性的影响;采用纤维增韧技术提高保温砂浆的抗裂能力,分析了纤维类型和掺量对石蜡微胶囊保温砂浆力学性能和抗裂性能的影响;确定了配制石蜡微胶囊保温砂浆使用乙烯—乙酸乙烯酯共聚乳胶粉黏结剂和聚丙烯纤维,其最佳掺量...     

微胶囊型自修复碳纤维增强复合材料性能研究

为了分析内嵌环氧树脂基微胶囊的碳纤维增强复合材料(CFRP)的力学性能,开展了材料在准静态载荷条件下力学性能试验研究,对比分析了有、无微胶囊时碳纤维增强复合材料的静态力学性能,详细探究了微胶囊的质量分数对碳纤维增强复合材料的力学性能和自修复性能的影响,分析了材料的拉伸强度,弹性模量,断裂伸长率以及自修复性能情况。在相同冲击能量下,采用落锤法对不同微胶囊含量的层合板进行冲击试验,研究其在冲击载荷作用下的动态力学响应。结果表明,微胶囊具有增韧效果和自修复能力。随着微胶囊质量分数的增加,自修复碳纤维增强复合材料的拉伸强度降低,弹性模量先略微升高后降低,断裂伸长率先降低后升高,但总体变化不大,修复效率随微胶囊含量的增加而升高。在相同冲击能量下,微胶囊含量越大,最大冲击力越小,材料的冲击力-位移曲线斜率越小,抗冲击性能越差。研究结果可以为推动自修复型CFRP材料的实际工程应用和理论研究提供相关参考。     

低熔点石蜡微胶囊的中试及热性能

为寻找能适应环境温度的相变材料,选择低熔点石蜡作为芯材,制备微胶囊并进行中试生产。对同一样品进行了26次DSC热循环测试和TGA热失重测试,结果表明：中试产品的相变温度始终保持在25~60℃,相变极值和相变热焓均未发生明显变化,分别为42℃和72 J/g;产品能耐受150℃以内的高温而不分解,且在相变温度范围内基本无失重。证明低熔点石蜡微胶囊能在环境温度内发挥调节作用,同时具备较长的热循环寿命和较好的热稳定性,是一种具备良好应用前景的相变材料。     

圆柱壳受水下爆炸冲击波作用的壁压分析

本文首先对圆柱壳受水下爆炸冲击波作用下的流体与结构的相互作用进行了分析,导出了在近距离、小药量爆炸条件下圆柱壳表面实际壁压的近似公式。在此基础上对圆柱壳爆炸实验的实测壁压进行了分析。结合壳体在冲击波作用下弹塑性响应的计算结果,对实测壁压给出了合理的解释。为进一步进行壳体响应分析打下了基础。     

微胶囊技术简介

微胶囊技术能够使物质产生物态变化,实现物质的固化,在医药、农药、食品、饲料、涂料、油墨、黏合剂、洗涤剂、感光材料、纺织等行业,都得到了广泛的应用。介绍了微胶囊技术的发展史,微胶囊的组成与制备方法,微胶囊的性质及应用．     

脊状表面近壁区湍流度分布规律

通过对不同风速下,不同形状、尺寸脊状表面及光滑平板表面边界层内湍流度的测试,对比分析了脊状表面近壁区湍流度的分布规律。试验在小型直流风洞中开展,流场测试中使用恒温式IFA 300智能型流动分析仪,测试模型则采用有机玻璃及铝两种材质的平板模型。在脊状表面理论零点及壁面摩擦速度的计算中,采用了基于紊流边界层对数律区流速分布公式同时计算壁面理论零点和壁面摩擦速度的改进方法。最终测试结果表明:脊状表面边界层过渡区和对数律区内湍流度与平板相比显著下降,最大降幅超过10%,证明脊状结构的存在有效减弱了壁面近壁区内"猝发现象"的发生。     

一步法制备石蜡微胶囊的中试研究及性能表征

采用一步法在100L反应釜内进行石蜡微胶囊制备的中试，表征了石蜡微胶囊的微胶囊化率、粒径和热性能，探讨了中试工艺对产品性能的影响。结果表明中试产品与实验室小试产品的性能基本接近。中试石蜡微胶囊的微胶囊化率为70％，平均粒径为54．0μm，相变范围为40～80℃，相变峰值和热焓分别为65℃，114J／g，分解温度达250℃。     

氙原子在铂表面散射的分子动力论方法

运用分子动力论方法研究气体分子 (Xe)在固壁表面 (Pt)的散射。在构造了合理的气体分子与固壁表面相互作用势模型之后 ,运用随机经典轨道方法求解气体分子及固壁原子的运动方程 ,得到气体分子运动轨迹及散射后的运动状态。结果表明 ,气体分子散射后的角度分布与Maxwellian模型存在较大差异 ,而速度基本服从半空间的Maxwellian分布。     

微胶囊化红磷及其应用

微胶囊化红磷是一种无卤、无毒、低烟、高效和普适的新型阻燃剂。本文讨论微胶囊化红磷的几种制备方法,分析该阻燃剂的优异性能及在橡胶、塑料等阻燃制品中的特殊作用。     

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.     

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).     

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.     

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.