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分析研究卫星移动通信系统中上行链路波束分集接收的可行性和性能及联合TPC编码性能。分析了波束交叠、波束增益对多波束卫星通信系统的性能影响,建立了用于多波束分集处理的系统模型;引用基于MGF函数的性能分析方法,针对波束分集的研究,得到了Nakagami-m衰落信道条件下的多波束相干最大比合并(MRC)性能;利用计算机仿真验证算法的有效性,并进一步分析了联合Turbo乘积码(TPC)编码的性能。通过研究表明,在多波束卫星通信中采用分集接收处理不仅完全可行,而且可以有效提高上行链路的性能,降低地面终端的发送功率,解决上行链路发送能力不足的问题,联合TPC编码可以获得进一步的性能增益。 相似文献
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研究通过地基大功率干扰机干扰卫星通信上行链路,通过无人机干扰卫星通信的下行链路。通过载噪比和误码率对卫星通信链路的性能进行分析,对地基干扰大功率机干扰卫星通信上行链路进行了仿真分析,研究干扰机布放数量、干扰功率、干扰频率、通信数据传输速率和调制方式等因素对干扰效果的影响,并对无人机干扰卫星通信的下行链路进行了仿真分析,得出无人机和地基干扰机干扰卫星通信的一些作战使用结论。 相似文献
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本文研究随机访问多码CDMA(RAMC-CDMA)蜂房网在慢衰落信道中的下行链路容量性能,在建立了系统模型后,对该系统的下行链路容量进行分析及数值计算。分析表明RAMC-CDMA解决了普通CDMA系统用户可传信息速率受限的问题,能在不增加射频带宽的前提下为用户提供高峰值速率信息传送,而系统容量没有大的下降。 相似文献
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伴随着3G时代的到来,3G手机逐渐走进武警警营。然而它在给官兵带来视频通话、网络冲浪、导航定位、彩信即拍即发等方便与快捷享受的同时,也给安全保密工作敲响了警钟。通过对3G手机的概念及主要功能的分析,指出它对安全保密工作的影响,探讨解决问题的对策,能够为部队管理者有效消除3G手机给部队安全保密工作带来的不利影响提供参考。 相似文献
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“严密防范网络泄密‘十条禁令”’的出台,切断了军内涉密信息与互联网络之间的流通途径,及时遏制了我军网络失泄密案件频发的态势。然而,“十条禁令”是只堵不疏的措施,给广大官兵的工作和学习带来了诸多不便。针对“十条禁令”前提下的信息安全保密疏导策略,提出了一系列方法和措施,为广大官兵安全地共享互联网资源寻求途径,这些措施对消除部队信息安全保密隐患,从根本上保障我军信息安全保密具有现实意义。 相似文献
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增强高级指挥员的科技认知力、创新力、运用力是科技强军的必然要求。本文从战争演变、融合发展、应对威胁切入,对高级指挥员如何提升科技认知力层次、增强科技创新力效能、提高科技运用力水平谈了几点初步思考。 相似文献
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Abdur R. Chowdhury 《Defence and Peace Economics》2016,27(5):583-608
We examine the role of war in retarding state fiscal capacity in developing countries, measured by tax revenue ratios to GDP. We build a simple theoretical model of a factionalized state, where patronage substitutes for common interest public goods, along with violent contestation over a rent or prize. Our dynamic panel empirical analysis applied to 79 developing countries, during 1980–2010, indicates that war, especially civil war, retards fiscal capacity, along with imperfect democracy, political repression, poor governance, and dependence on oil and macroeconomic mismanagement. High intensity conflict is particularly destructive of state capacity. In countries experiencing low intensity wars, other institutional factors may matter more than war. The diminution of fiscal capacity due to war appears less pronounced after the end of the cold war. 相似文献
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文献[1]~[3]中研究了神经网络的能力—存储能力。但我们认为神经网络的能力应包括存储能力和计算能力两个方面。本文对神经网络的存储能力和计算能力进行定量分析,并得出了许多有益的结论。 相似文献
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一类带容量限制的运输问题 总被引:11,自引:2,他引:9
考虑一类带容量限制的运输问题.采用构造辅助网络的方法,将运输网络中的每个配送中心均拆分成两个节点,构造出新弧,形成新的网络,把此类运输问题转换为最小费用流问题来解决.并在此基础上,考虑运输网络中配送中心的容量扩张问题. 相似文献
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William P. Rogerson 《Defence and Peace Economics》2013,24(3):235-249
This paper analyzes a set of observations by the Congressional Budget Office (CBO) on individual weapons systems regarding whether large amounts of excess capacity exist and whether short run average cost (SRAC) appears to be severely decreasing. It is shown that the amount of excess capacity and steepness of SRAC are essentially independent of output rate. It is then argued that this suggests that production is occurring in inefficiently large plants—i.e.—off the long run cost curve. 相似文献
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Previous work has documented a negative correlation between internal conflict and state capacity. We attempt to shed light on mechanisms that underlie this relationship, using data for Colombian municipalities. We rely on identifying heterogeneous effects of different types of violent events on state capacity, taking advantage of variability across municipalities in the prevalence of specific manifestations of conflict and their intensity. Our findings suggest that events making civilians feel targeted affect the state’s capacity to collect taxes, while those reflecting a stronger military capacity of illegal armies, in particular their large-scale attacks, affect the state’s capacity to provide public goods. 相似文献
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李秋萍 《兵团教育学院学报》2006,16(4):11-12
编辑工作是整个出版工作的中心环节,编辑又是读者与作者之间不可或缺的桥梁与纽带。能否在编辑工作中贯彻“从读者出发,为读者服务”的指导方针,是整个编辑出版工作成败的关键所在。当代新闻出版业的急剧发展和演变,对编辑工作也提出了新的要求。 相似文献
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The quick response (QR) system that can cope with demand volatility by shortening lead time has been well studied in the literature. Much of the existing literature assumes implicitly or explicitly that the manufacturers under QR can always meet the demand because the production capacity is always sufficient. However, when the order comes with a short lead time under QR, availability of the manufacturer's production capacity is not guaranteed. This motivates us to explore QR in supply chains with stochastic production capacity. Specifically, we study QR in a two-echelon supply chain with Bayesian demand information updating. We consider the situation where the manufacturer's production capacity under QR is uncertain. We first explore how stochastic production capacity affects supply chain decisions and QR implementation. We then incorporate the manufacturer's ability to expand capacity into the model. We explore how the manufacturer determines the optimal capacity expansion decision, and the value of such an ability to the supply chain and its agents. Finally, we extend the model to the two-stage two-ordering case and derive the optimal ordering policy by dynamic programming. We compare the single-ordering and two-ordering cases to generate additional managerial insights about how ordering flexibility affects QR when production capacity is stochastic. We also explore the transparent supply chain and find that our main results still hold. 相似文献