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431.
超音速等离子制备Al/Ni涂层的性能特点 总被引:3,自引:0,他引:3
以超音速等离子喷涂系统(HEPJet)为平台,采用铝包镍(Al/Ni)自粘结粉末,借助Spray Watch2i在线监测系统、扫描电子显微镜(SEM)、X射线衍射仪(XRD)和WE-10A万能拉伸试验机,研究了超音速等离子喷涂Al/Ni粒子的速度、温度及涂层的组织性能。研究结果表明:超音速等离子喷涂Al/Ni自粘结粉末时,与普通火焰喷涂不同,射流中无明显的放热反应特征,涂层中也未发现Al-Ni化合物;超音速等离子的喷涂功率、喷涂距离等参数对Al/Ni喷涂粒子的状态和涂层组织性能影响显著,当功率为54.6kW、喷涂距离为150mm时,Al/Ni涂层组织致密,与基体的结合强度高达56MPa。 相似文献
432.
Beatrice Heuser 《Small Wars & Insurgencies》2014,25(4):741-753
When twentieth-century authors wrote about ‘partisan warfare’, they usually meant an insurgency or asymmetric military operations conducted against a superior force by small bands of ideologically driven irregular fighters. By contrast, originally (i.e. before the French Revolution) ‘partisan’ in French, English, and German referred only to the leader of a detachment of special forces (party, partie, Parthey, détachement) which the major European powers used to conduct special operations alongside their regular forces. Such special operations were the classic definition of ‘small war’ (petite guerre) in the late seventeenth and in the eighteenth centuries. The Spanish word ‘la guerrilla’, meaning nothing other than ‘small war’, only acquired an association with rebellion with the Spanish War of Independence against Napoleon. Even after this, however, armies throughout the world have continued to employ special forces. In the late nineteenth century, their operations have still been referred to as prosecuting ‘la guerrilla’ or ‘small war’, which existed side by side with, and was often mixed with, ‘people's war’ or popular uprisings against hated regimes. 相似文献
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Maria Ryan 《Small Wars & Insurgencies》2014,25(1):41-68
This article examines the evolution of US irregular warfare (IW) doctrine and practice from 2001 onwards. It argues that, after 9/11, top-tier civilian policymakers in the US Department of Defense (DoD) and across the US government developed a heightened awareness of asymmetric threats and non-conventional forms of warfare, especially those shaped by contemporary globalisation. The result was a gradual turn towards irregular warfare, led by Rumsfeld and the DoD, designed to ensure ‘full spectrum dominance’ across all modes of conflict. This pre-dated the insurgency in Iraq and the promotion of counterinsurgency in the US Army by General David Petraeus and others. Policymakers' reluctance to acknowledge the insurgency in Iraq was not down to a failure to understand the concept of IW, but because they had viewed Iraq in conventional terms for so many years and were reluctant to admit their mistake. 相似文献
434.
This article is devoted to the study of an M/G/1 queue with a particular vacation discipline. The server is due to take a vacation as soon as it has served exactly N customers since the end of the previous vacation. N may be either a constant or a random variable. If the system becomes empty before the server has served N customers, then it stays idle until the next customer arrival. Such a vacation discipline arises, for example, in production systems and in order picking in warehouses. We determine the joint transform of the length of a visit period and the number of customers in the system at the end of that period. We also derive the generating function of the number of customers at a random instant, and the Laplace–Stieltjes transform of the delay of a customer. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 646–658, 2015 相似文献
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分析了一种ZCS半桥式DC DC变流器时域工作特性.通过研究其工作各阶段的特性建立了其状态空间模型,采用Matlab语言进行编程仿真,得到其输出电压时域仿真波,与实测吻合,证明了所建状态空间模型的正确性,得到变流器工作的一些有用结论,有助于指导下一步变流器的传导干扰分析和抑制. 相似文献
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为了能够更加高效地利用太阳能资源,在重庆地区设计并搭建了实验平台,对不同季节复合抛物面聚光型PV/T系统(CPC-PV/T)进行了实验研究。结果表明:尽管重庆地区太阳能资源匮乏,但加入复合抛物面聚光器后,PV/T系统的整体光电转换效率最高可达到17.07%,系统全天光热转换效率达到58.2%。因此,该地区在夏季进行太阳能光电热综合利用是完全可行的,春、秋季太阳较好的天气也可利用。 相似文献