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为保证网络流媒体传输质量,在流媒体的传输中需要采用有效的拥塞控制策略.结合流媒体数据对时延敏感的特点,提出了一种基于累积时延的模糊拥塞控制算法,该算法在流媒体数据流传输过程中检测和跟踪其时延,在转发分组数据前,根据容忍时延阈值,丢弃超时数据包,减少不必要的带宽浪费,并且对所到达的数据流按照累积时延进行优先级分类,把全局性缓冲区和各队列的局部性缓冲区按照正常、拥塞避免和拥塞的规则划分为3个具有交叉过渡域的阶段,然后采用整体和局部相结合的拥塞控制方法,实现队列调度过程中的模糊处理,从而对网络拥塞进行有效的控制.理论分析和实验结果表明,使用基于累积时延的模糊拥塞控制算法,能有效改善流媒体的传输性能,是解决流媒体传输拥塞控制的有效途径,并能对提高网络性能起到重要作用. 相似文献
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文章介绍了一种采用分布式架构的软交换应用服务器(Application Server,AS)系统,它是由多个功能独立的单一服务器构成的一个结构清晰的服务器群,并可根据用户的需求进行业务功能的组合,完成各种复杂的呼叫处理.在采用了分布式架构以后,系统的灵活性配置得以体现,可用性也有了很大的提高,满足服务器级别的性能要求.文章同时描述了一种实用于工程实践中的系统实现方法. 相似文献
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本文详细地讨论了光纤通信的光源——半导体激光器(LD)和发光管(LED)的可靠性;重点论述了长波长光源的可靠性以及筛选方法。 相似文献
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《机械与工业》2000,1(2):151-164
Catalysts support extrusion: the problem of rheological characterization of high concentrated mineral pastes. To exhibit a large specific surface (up to several hundred square meter per gram), catalysts are often porous materials. Their manufacturing involves a powder forming process. This process is achieved in several steps: (i) mixing a powder with an aqueous or polymeric binder to form a paste, (ii) extruding the paste to form the product, (iii) drying it and finally (iv) slightly sintering it. The paste which is studied in this paper is made of titanium oxide and aqueous acidic binder (nitric acid). The role of the acid is to disperse “at best” the T i O 2 powder by colloidal action. This kind of manufacturing process is old but remains however difficult to control because of many different difficulties: e.g., dies design, the balancing of several hole paths and more generally explicit what could be a “paste extrudability”. In this paper, first, we show experimentally that this type of material can present a heterogeneity induced by its flow. Second, we propose a modelization of the behavior of this product in the framework of the mixture theory. Third, we present a complete identification methodology based on squeezing tests. 相似文献
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详细描述了240Gbit/s OFDM(正交频分复用)实时光通信系统的设计与实现。采用多载波发生装置产生3×15个相互正交的光子载波,并对每个光子载波调制4Gbaud/s速率OFDM信号,采用4QAM(二阶正交幅度调制)信号格式。在接收端,分别用对应的本征光子载波解调各路光OFDM信号,使用FPGA(现场可编程门阵列)对采样信号进行实时处理。总有效数据速率达到240Gbit/s。文章报道的传输速率为已报道实时OFDM传输的最高记录。 相似文献
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PMD compensation using birefringence photonic crystal fiber in 40Gbit/s optical communication system
CHEN Ming YANG Si-gang LI Jin-yan CHEN Wei XIE Shi-zhong 《光电子快报》2008,4(1):30-32
A birefringence photonic crystal fiber is used for PMD compensation in a single-channel 40Gbil/s-speed optical communication system with CSRZ format. The experimental results of transmission show that the PMD compensation system works effectively. 相似文献
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