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在采用空时码的无线通信系统中,收发2端较差的路径会降低系统的性能.提出了多速率线性离散码(LDC),并对其进行了分析,给出了一种基于矩阵扩展方法的设计算法.多速率LDC是传统LDC和LDC-TAS的BER性能的折中.进而提出了一种性能优于传统LDC-A-TAS算法的多速率LDC自适应发送天线选择(A.TAS)算法. 相似文献
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TCP/IP是Internet广域互联网络一组最重要的协议,是网络环境下的现代信息服务的核心,TCP/IP及其服务的安全问题也是现代信息服务的安全问题,选择合适的安全对策是保证现代信息服务安全的关键。 相似文献
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Inrecent years ,IEEE802.11 wirelesslocal area net-work (WLAN) has emerged as a prevailing technology forthe (indoor) broadband wireless access to internet for themobile/portable devices . In IEEE 802.11 standards ,802.11b has become the most widely used v… 相似文献
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INTRODUCTIONTomeettherequirementsofEMIstandard ,switchingmodeconvertersshouldlimititsswitchingrippleofinputcurrenttoalowlevel.OneofthetypicaltraditionalmethodsistoplaceacostlyandbulkyEMIfilterattheinputcircuitoftheconverter.ForAC DCconverterstheinputfi… 相似文献
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在采用空时码的无线通信系统中,收发2端较差的路径会降低系统的性能.提出了多速率线性离散码(LDC),并对其进行了分析,给出了一种基于矩阵扩展方法的设计算法.多速率LDC是传统LDC和LDC-TAS的BER性能的折中.进而提出了一种性能优于传统LDC-A-TAS算法的多速率LDC自适应发送天线选择(A-TAS)算法. 相似文献
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测定水葫芦对宁德市东湖塘水体中总氮(TN)、总磷(11P)的清除作用;结果表明:经过25d的净化,水体中总氮的含量由3.45mg,L降至0.64mg/L,总去除率达80.2%;而总磷的浓度由原来的1.12mg/L降为0.26mg/L,总去除率为76.8%,这说明水葫芦对污水具有较强的净化能力. 相似文献
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文章探讨了有PEN线的TN系统接地安全性问题,说明了等电位联结在防止间接触电方面更加有效,阐明了接地和等电位联结的关系,介绍了等电位联结的实施办法。 相似文献
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A novel topology for ripple-free input current circuit is put forward in the paper. Compared to traditional EMI (electromagnetic
interference) filter consisting of choke and capacitor, the ripple-free topology can reduce the converter's ripple current
with the use of smaller component. The new ripple-free topology proposed in this paper does not need elaborate adjustment
of the coupling coefficient as required by conventional ripple-free techniques, and is ripple voltage cancellation or isolation
mode, which can attenuate the ripple further if the line impedance is considered. The theoretical prediction is confirmed
by experimental results.
Project supported by the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry 相似文献