排序方式: 共有90条查询结果,搜索用时 375 毫秒
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利用有一定间距的两部声纳基阵提供的目标方位和时延差的信息,实现对目标的被动测距。建立了测距物理模型,给出了后置距离滤波算法。通过仿真实验验证了模型的有效性,并通过分析两阵间距及时延差均方误差对测距的影响,表明了由于声场环境及特性的影响,选择适当的阵间距和时延差均方误差在实际测距试验中是非常重要的。 相似文献
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Charles Esdaile 《Small Wars & Insurgencies》2019,30(4-5):734-749
ABSTRACT The brief war that took place between Spain and Portugal in 1762 is one of the least known episodes in the latter’s military history, whereas, thanks to Wellington’s construction of the Lines of Torres Vedras, the French invasion of 1810–11 is right at the other end of the spectrum. Yet the two episodes are closely linked to one another. At the very least, they are uncannily reminiscent in terms of their details – in both cases substantial foreign armies were vanquished through a combination of irregular resistance, scorched-earth tactics and the clever use of field fortifications – and the article therefore argues that Wellington based the plan that defeated the forces of Marshal Massena on the strategy used by the Portuguese half a century earlier. 相似文献
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George Joffé 《Small Wars & Insurgencies》2016,27(1):1-21
Although the Islamic State in Iraq and al-Sham (ISIS) is seen as a novel manifestation of Islamic extremism, it is in fact the latest, albeit perhaps the most effective, of a long line of revivalist movements in the Islamic and the Arab worlds. Its motivations – hisba and jihad – differ little from its predecessors and its ambitions – to create a state organised in accordance with the precepts of the Islamic caliphate – reflect a long-standing Islamic ambition. It differs, of course, in terms of the sophistication of its political and military strategies, which mirror the contemporary complexities of the world in which it operates, but its objectives recall long-standing Islamic ideals, even if articulated in radically brutal and extremist ways. More importantly, perhaps, ISIS or Da’ish, to give it its Arabic sobriquet, reflects the enormous degree of resentment inside the Middle East at the ways in which Western powers have intervened in regional affairs over recent years, particularly their support for regimes and economic systems there that have betrayed, in the popular imaginary, the essential principles of social justice that lie at the root of Islamic vision of ideal social order. Indeed, in many respects, its analysis of the world in which it operates and of the objectives it seeks differ little in essence from those any other resistance and rejectionist movement, whether religious or sectarian. More specifically, it has been the sectarian conflict that resulted from the reversal of political order in Iraq as a result of the 2003 American-led invasion that has driven the success of the movement in capturing widespread Sunni support. Whether it can manage the complexities of the administration of a state remains open to question. 相似文献
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建立了横观各向同性压电材料中的共线非等长多裂纹模型。将裂纹模拟为连续分布的广义位错,推导了单点广义位错的格林函数,并基于此得到了共线非等长多裂纹的奇异积分方程组,最后由数值计算给出了裂纹尖端的能量释放率。对奇异积分方程组的退化分析和对称条件下的数值结果的讨论,验证了本文结果的正确性。研究表明:当共线裂纹间距小于裂纹长度时,裂纹尖端场存在显著的干涉效应;裂纹越长,干涉效应越显著;电载荷系数越大,能量释放率也越大;相对于外侧尖端而言,共线裂纹内侧尖端对电载荷系数更为敏感。 相似文献
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Mohammad Hossein Sabouri 《Journal of Military Ethics》2016,15(3):227-245
For more than a decade, Iran has been referring to a fatwa issued by its Supreme Leader, Ali Khamenei, proscribing nuclear weapons. The fatwa, however, not only failed to influence the process that led to the resolution of Iran’s nuclear crisis, but also has been met with a good deal of skepticism. The most commonly held suspicions about the credibility of the fatwa can be summed up in five central questions: (1) Has the nuclear fatwa actually been issued? (2) Does the fatwa apply to all the aspects of nuclear weapons including their production, possession and use? (3) What is the juridical status of the fatwa? (4) Was the nuclear fatwa issued only to deceive other nations? (5) Is the fatwa really irreversible? This article tries to answer these questions by providing a chronological review of the fatwa and analyzing all the relevant statements by Khamenei. The analysis is conducted against the background of Islamic principles, Shi’a jurisprudence and the history of the Islamic Republic of Iran. The article concludes that the fatwa is a credible religious decree and could indeed contribute to the cause of nuclear disarmament. 相似文献
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结合次声波的特点和性质,建立了适用于动态环境下的基于次声波和电磁波的非同步TDOA测距模型。同时,将精确的测距信息与历史位置信息结合起来,提出并推导了信标节点稀疏分布下的三维测距解析定位算法,并根据有限的定位时刻位置信息采用内插法恢复出节点随机运动轨迹图。仿真结果表明:该算法具有较好的鲁棒性,可实现分米级以下的定位精度。 相似文献
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