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261.
刘念光 《国防科技》2018,39(6):001-004
习主席在庆祝改革开放40周年大会上的重要讲话,是新时代改革开放再出发的宣言书和动员令。学习贯彻习主席重要讲话精神,关键要全面推进学校深化改革创新,深刻认清弘扬改革创新精神对于建设世界一流高等教育院校的重大意义,牢牢扭住全面深化改革创新的主攻方向,科学处理深化改革创新的重大关系,既以顽强的战略定力坚定不移深化改革,又运用科学的工作方法积极稳妥地推进改革。  相似文献   
262.
针对具有反作用控制系统(Reaction Control System,RCS)和气动舵两类控制机构的再入飞行器,提出一种基于脉宽脉频(Pulse-Width Pulse-Frequency,PWPF)调节器的最优控制分配方法。将RCS的输入信号转化为连续变化量,RCS与气动舵的控制分配问题被描述为二次规划问题,并采用有效集方法对其求解。采用离散法和PWPF调节器将优化结果转化为RCS的开关机状态。与混合整数规划问题相比,连续二次规划问题更容易求解,计算速度更快。通过对二次规划问题的重构,该算法能有效地应对故障情况。  相似文献   
263.
驱动器并联方式能有效扩大驱动容量,但该方式容易引入环流。为了抑制环流,分析了两个独立电源供电的两台驱动器并联结构系统,阐述了环流的特性,并提出了基于环流反馈的控制结构。这种控制结构通过环流的反馈,只需要控制调整其中一台驱动器,就可减小两台驱动器输出电压的差异,实现环流抑制。仿真结果表明:这种控制结构降低了控制的复杂性,能够抑制环流,实现独立电源供电的无刷直流电机驱动器并联。  相似文献   
264.
为了得到发射装置设计因素和超高速碎片性能间的关系,考虑了药型罩的材料、炸药种类、装药长径比、药型罩的锥角、药型罩的厚度、药型罩顶部靠近装药侧的曲率半径等设计因素,采用AUTODYNTM,结合正交试验,对超高速碎片的发射过程进行数值模拟。结果表明,3种发射装置结构分别可以提供质量为1. 533 g的紫铜碎片、速度为11. 649 km/s的铝碎片、动能为85. 6 k J的铝碎片; 2种发射装置结构均可以提供质量大于1 g、速度高于11 km/s的密实结构圆柱状碎片。验证了仿真方法的可信性,对影响碎片性能的设计因素进行了分析、排序,并得到了这些设计因素与碎片质量、速度、动能的关系。  相似文献   
265.
Abstract

Libya in 2011 witnessed a real process of political change, though different from all the policy-oriented jargon equating transition with a teleological transition to democracy. Due to the resilience of the Qadhafi regime in power and with the essential role of NATO intervention, the process was eased out by a eight-month civil war. Governance in post-Qadhafi Libya was not done through the rebuilding of centralized authorities. But it took the specific form of the emergence of multiple non-state actors embedded in local dynamics and then connected with weakened central authorities that had access to the huge Libyan resources. That raised complex questions about the quality of this mode of governance, especially at a time of pressing problems for Libya and its neighbors, whether direct ones (Tunisia, Egypt, Mali) or farther countries across the Mediterranean sea: terrorism with the expansion of Da’esh into the country and flows of refugees crossing Libya’s uncontrolled borders and flowing into Italy and then Europe by thousands.  相似文献   
266.
Since the fall of the Taliban in late 2001, the Islamic Republic of Afghanistan (GIRoA), the United States, the United Nations, and the International Security Assistance Force (ISAF) have funded and led three different Disarmament, Demobilization, and Reintegration (DDR) programs. Despite a significant investment in time and treasure, all of them have failed to significantly reduce the number of insurgents or arbaki (militia). This article explores why these programs failed despite incorporating ideas from the prominent DDR schools of thought. Utilizing Stathis Kalyvas’ theory of The Logic of Violence in Civil War as a lens, this article argues that GIRoA and ISAF did not have sufficient control of territory to entice insurgents or arbaki to reconcile and/or reintegrate with the government. Further, in areas GIRoA nominally controlled in northern and western Afghanistan, regional powerbrokers who controlled these areas balked at these programs.  相似文献   
267.
可展开遮阳罩一般是由多层轻质柔性高精度无褶皱薄膜和展开支撑臂及其控制装置组成,在轨后展开支撑臂有序展开多层大面积薄膜实现光控制和热控制性能,能有效改善和防护空间航天器。针对可展开遮阳罩结构,依据一维轴向、二维平面与三维周向的展开方式分类总结国内外可展开遮阳罩技术的研究进展,并对不同遮阳罩结构形状、薄膜材料、层数与展开方式等进行对比分析;梳理出遮阳罩在杂光抑制、折叠与展开变形机理、极端环境下薄膜多场耦合、低温热控、太阳辐射光压力矩及其计算方法等方面的关键科学问题,并给出了中国研究遮阳罩的发展建议。  相似文献   
268.
There has been near-universal condemnation of the use of chemical weapons in the Syrian conflict. The international community has nevertheless struggled to make progress on holding the perpetrators to account. This article reviews developments at the international level in terms of Syrian chemical weapon justice between 2011 and 2017. It argues that there have been substantive disagreements between states on the rationale and means of justice in the Syrian case. It also argues that international initiatives have been tightly intertwined with developments in chemical disarmament and conflict resolution processes as well as the broader war. The article describes progress and challenges to chemical weapon justice in a number of distinct formal international mechanisms during the period studied. The analysis concludes by contextualizing international responses—including the U.S. tomahawk strikes against a Syrian airbase—to the Khan Shaykhun chemical attacks of April 2017.  相似文献   
269.
Some U.S. military leaders have asserted that the United States, Japan, Australia, and India and the Republic of Korea are developing multilateral defense cooperation to deter aggression and uphold norms much like North Atlantic Treaty Organization (NATO) has in Europe. Frequent military exercises and China’s threats to freedom of navigation (FoN) and North Korea’s nuclear missiles comprise the motive force for such cooperation. However, cooperation thus far has been trilateral and minimal, given divergent national interests and dispersed geopolitical locations. Cooperation among Japan, Republic of Korea (ROK), and the United States is increasing given the threat, but ROK’s public opinion is divided about Japan. Australia, Japan, and India have increased cooperation with the United States but are reluctant to conduct FoN operations with the United States to challenge China’s expansionism in the South China Sea. If China becomes more aggressive and blocks FoN or seizes territory, development toward an Asian NATO is possible.  相似文献   
270.
设我方m艘战舰,对方n个来袭目标.运用灰色局势决策求得目标对各个战舰产生的威胁值排序;再用模拟退火算法,参考目标威胁,单舰根据自身装载的火力发射进行初步武器分配;最后将分配结果传送至融合中心,应用大系统理论的分解协调法,协调武器分配,使得我方武器对本批目标的打击概率最大.仿真基于VC++编程实现,具体分析了算法及思想的可行性.  相似文献   
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