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281.
不同分散剂对纳米SiO_2水中分散的影响   总被引:1,自引:0,他引:1  
选取六偏磷酸钠(SHMP)、十二烷基苯磺酸钠(SDBS)及KCl作分散剂,并采用超声分散方法,制备纳米SiO2悬浮液,对纳米SiO2的水中分散性能进行研究。测试分散体系中纳米SiO2粒子的粒径及分布、Zeta电位及透光率,探讨了不同分散剂对纳米SiO2分散性能的影响。结果表明:不同分散剂对纳米SiO2的粒径都有明显影响,但粒径分布宽度差别较大;同在分散粒径较小的条件下,分别添加3种分散剂的悬浮液体系具有不同的稳定性,其中含SDBS的分散体系因静电和空间位阻的作用而表现出良好的分散稳定性。  相似文献   
282.
在分析应急通信系统特点及现有监控技术基础上,提出一种分布式多域监控组织模型,该模型具有扩展性好、高可靠性等特点,减小了网络时延,提高了系统吞吐率.并在此组织模型基础上提出了基于ART2神经网络模型的自适应域首选举方法,提高了域首选举的稳定性,减少了域首选举带来的网络开销,对系统的可靠性提供了保证.  相似文献   
283.
基于约束满足的多目标对地观测卫星成像调度   总被引:1,自引:0,他引:1       下载免费PDF全文
EOS(对地观测卫星)成像调度需要根据用户提出的成像任务需求确定卫星成像序列,是一个复杂的组合优化问题。考虑到成像侧视约束条件,建立EOS成像调度的多目标有向无环约束图模型。在此模型的基础上提出了基于SPEA2(strength pareto evolutionary algorithm 2)的多目标成像调度算法,采用约束控制技术设计遗传算子处理成像约束。经过三个实际的多目标成像调度问题测试,表明该算法可以有效地解决EOS成像调度问题。  相似文献   
284.
对C2系统仿真及评价而言,在网络中心战背景下构建一个良好的参考模型是目前C2领域研究中的瓶颈问题.以过程模型及MOM框架为核心构建了面向复杂网络的C2系统概念性模型框架.在构筑抽象的C2过程模型框架基础上,借鉴认知决策(RPD)模型的概念,从感知分析及参数估计、态势评估、模式匹配、行为确定四个方面对C2过程模型进行了形式化描述,同时从个体信息能力度量、个体态势感知能力度量、个体决策能力度量、个体指挥引导能力度量、信息共享能力度量、态势共享能力度量、协同决策能力度量、作战意图共享能力度量、作战意图同步能力度量9个方面对C2 MOM框架进行了分析.  相似文献   
285.
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   
286.
研究了一种基于含氟聚合物的聚合物锂离子电池,考察了SiO2纳米粉对聚合物电解质隔膜的机械性能、吸液量以及电导率的影响,用电镜分析探讨了纳米改性聚合物电解质膜的微观结构;并以此纳米改性聚合物隔膜组装了小型的聚合物锂电池,研究了其电性能.  相似文献   
287.
ABSTRACT

Despite its portrayal as something new, the concept of the ‘gray zone’ is not novel. It was the Cold War battleground in which the USA and the Soviet Union waged rival unconventional campaigns, and it was there that the newly formed Central Intelligence Agency (CIA) was given responsibility for operating. This was not the organization’s original purpose, but Cold War exigencies forced Washington to improvise and build an organization with unique capabilities. These early years shaped the CIA’s operations directorate, creating two distinct cultures within the larger agency, one focused on intelligence collection and the other focused on covert action.  相似文献   
288.
ABSTRACT

As the United States and North Korea pursue negotiations on a “denuclearization” agreement, the two countries should consider initiating cooperative measures as a way to build confidence and encourage finalization of a complete agreement. Based on lessons from the initial engagements carried out under the Cooperative Threat Reduction (CTR) program in states of the former Soviet Union (FSU), initial cooperation should focus on safety and security, training, and infrastructure elimination. By offering to implement these initiatives now while negotiations are underway, the United States could gain additional insights into North Korean intentions. These early initiatives could be proposed without compromising the US maximum-pressure campaign on North Korea by using the current authorities of the CTR program and carefully designing specific exemptions that may be required for any agreed measures. If North Korea is truly interested in pursuing disarmament efforts, the initial cooperative projects would enable them to begin reaping potential benefits while negotiations continue with sanctions still in place. These initial proposals could also be expanded to include additional international partners such as Russia, China, South Korea, and Japan. Such programs and initiatives would support and supplement longer-term strategies to address North Korean weapons-of-mass-destruction challenges.  相似文献   
289.
ABSTRACT

This article examines Chinese views of North Korea’s nuclear-weapon program during the Donald J. Trump administration. It shows that China has portrayed itself as a responsible country that promotes regional stability, unlike the United States, which has engaged in military brinkmanship with North Korea. Some Chinese foreign-policy experts have asserted that Beijing should back Pyongyang in the event of war because of their shared history of humiliation by great powers, while others have favored working with other regional partners. Another theme in Chinese discourse about North Korea is that Pyongyang is an impetuous, ungrateful regime that impedes Beijing’s ability to attain its core interests of regional stability, economic development, and heightened global influence. This negative assessment of North Korea drove Beijing’s endorsement of stricter UN sanctions in 2017. While Beijing has punished Pyongyang for its wayward policies, China responded favorably to North Korea’s decision in April 2018 to stop nuclear tests and partake in international dialogue. Beijing seeks to help Pyongyang gradually disarm and develop its economy within a Chinese-led East Asian order. The article concludes by explaining how Beijing’s recent, more positive view of Pyongyang is likely to affect its support for American efforts to dismantle North Korea’s nuclear-weapon program.  相似文献   
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