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891.
对频率选择表面进行了研究,通过研究不同结构的频率选择表面,在现有介质材料的基础上设计了一种具有带通特性的频率选择表面,并用Ansoft HFSS进行了仿真设计.在20%带宽内实现了垂直照射传输损耗小于-2 dB,并研究了电磁波在不同入射角度下的传输特性.  相似文献   
892.
通过简单复制转发被保护目标信号可对三星时差定位系统进行欺骗干扰.目前对于三星时差定位系统欺骗干扰效能评估的研究鲜有公开资料发表.分析了针对三星时差定位系统的转发式欺骗干扰原理,提出了将假目标数量和虚假目标干扰分布熵2个评估指标结合的干扰评估方法.通过仿真分析对转发式欺骗干扰效能进行了评估,实验结果验证了所提方法的有效性.  相似文献   
893.
An availability‐oriented approach has been developed to decide when to replace an aging system. For an existing system, it is optimal to operate another year if and only if the incremental cost per available year is less than the lifetime average cost per available year of a new aircraft. We illustrate our approach using United States Air Force KC‐135 tanker data. In demonstrating our approach, we find it will be optimal to replace the KC‐135 by the end of the decade.  相似文献   
894.
The 17th Conference of the Parties (COP17) had been anticipated as the ‘African COP’, not only due to the African venue but also due to the opportunity it would afford African countries – with South Africa at the helm – to steer the debate on a global climate change regime. With the conference now over, lobby groups, international organisations, negotiators, observers and commentators alike have been taking stock of its outcome. Despite the litany of developmental and security implications of climate change, COP17 got underway with little hope that much might actually be achieved. In light of the discouraging condition of the global economy, with leading developed economies suffering financially, states were hardly in a mood to be making concessions that would impact their fiscal health. Nonetheless, an agreement was reached. Questions remain, however, about the significance of the outcome of the African COP for the world at large, but ultimately also for Africa.  相似文献   
895.
Boko Haram terrorism has been recognized by Nigerian President Jonathan as the most threatening and complex security issue in Nigeria since independence. In response, the Federal Government of Nigeria has committed itself to different counterterrorism measures, which are largely dominated by “hard politics” and military mobilization. Spending heavily on defense to upgrade military hardware and train personnel in a counterterrorism role, Nigeria has also boosted its strategic importance in the “Global War on Terror”. However, this attempt has become unpopular as it has failed to contain Boko Haram within a short time frame and has made insufficient headway against unabated terror, with human rights costs among the host communities and amidst a surge of stakeholders' discordance. As a matter of concern, this article seeks to assess Boko Haram as an opponent in Nigeria's war on terror (WOT) and to ascertain the challenges the country faces, the alternative measures open to it, and possible ways forward.  相似文献   
896.
采用胞外聚合物作为生物絮凝剂,开展胞外聚合物复合絮凝剂强化混凝处理微污染原水的研究.研究结果表明,蛋白质是胞外聚合物最主要的成分,多糖次之,腐殖酸和脱氧核糖核酸的含量最低;胞外聚合物含有大量带负电荷的官能团,单独投加胞外聚合物不能有效絮凝和吸附去除原水中的污染物.聚合氯化铝混凝处理微污染水的效果优于氯化铝和聚合硫酸铁,药品较优投加质量浓度为70~80 mg/L.胞外聚合物和聚合氯化铝复合使用能提高对细小颗粒物的去除效果,增强去除有机污染物和氯化消毒副产物前驱体的能力,降低聚合氯化铝的质量浓度.胞外聚合物复合絮凝剂的较优配方:胞外聚合物质量浓度为5 mg/L,聚合氯化铝质量浓度为60 mg/L.  相似文献   
897.
指挥自动化系统是集指挥控制、情报侦察、预警探测、通信、电子对抗和其他作战信息保障功能于一体的完整体系,其综合效能评估是衡量系统整体作战能力的重要方法。该文结合指挥自动化系统对抗仿真的实现方法,对指挥自动化系统体系效能评估的指标体系、仿真评估的功能结构和实现步骤及指标的分析与评估方法等作了具体研究。  相似文献   
898.
分析了美军与北约等外军对指挥控制能力成熟度模型的研究现状,借鉴软件生产能力成熟度模型(CMM)的相关方法,提出了我军指挥控制能力成熟度的研究思路和指挥控制能力成熟度模型总体架构与评价方法,阐述和展望了该模型的应用。  相似文献   
899.
《Arms and Armour》2013,10(2):101-153
Abstract

The Sword of Honour (RA IX.1841) presented in 1856 by the Province of Nova Scotia to its native son, General Sir William Fenwick Williams, Bart. for his deeds at Kars, Turkey, is described, illustrated, discussed and placed both in its historical and its design context. Other notable British swords of the Victorian Age (1837–1901), the Age of Empire, are also examined and the various and influential aspects of their designs, ornament and iconography discussed.  相似文献   
900.
界面热阻对金刚石/银复合材料导热率的影响   总被引:2,自引:0,他引:2       下载免费PDF全文
研究了金刚石/银复合材料的导热率与金刚石的含量、粒度等之间的关系,着重讨论了界面热阻对复合材料导热率的影响。并阐述了金刚石表面镀钛,能有效改善金刚石对银的润湿性,降低界面热阻,从而提高金刚石/银复合材料的导热率。  相似文献   
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