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基于循环迭代的LDPC码环长扩展算法
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作者 沈良 陈其先 +1 位作者 程云鹏 马绪 《解放军理工大学学报(自然科学版)》 EI 北大核心 2010年第1期1-6,共6页
为了易于DSP的硬件实现,提出了一种简单的较高码率的无4-环准规则LDPC(low-density parity-check)码的母矩阵构造方法,从理论上给出了母矩阵扩展因子L的下限值,并在此基础上通过循环迭代的环长扩展算法,使母矩阵大量的短环得到了消除,... 为了易于DSP的硬件实现,提出了一种简单的较高码率的无4-环准规则LDPC(low-density parity-check)码的母矩阵构造方法,从理论上给出了母矩阵扩展因子L的下限值,并在此基础上通过循环迭代的环长扩展算法,使母矩阵大量的短环得到了消除,并且它们的编码复杂度和码长成线性关系。仿真结果表明,经过环长扩展的LDPC码略好于M ackay的随机构造同码率的码字性能,而比一次扩展的码字有0.4 dB左右的性能增益。采用循环迭代的环长扩展算法非常有利于硬件实现。 展开更多
关键词 直接下三角型LDPC码 转置单位矩阵 重叠环 迭代算法
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几种多环负反馈放大电路模式与浅析
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作者 王东民 王保玉 《河南师范大学学报(自然科学版)》 CAS CSCD 2001年第2期102-104,共3页
实际的负反馈放大电路 ,并非都是由基本放大电路和反馈网络构成一个闭环系统 <1>,还有由多个基本放大电路和多个反馈网络构成的多环系统 (多环负反馈电路 ) <2 >.给出几种多环负反馈放大电路的一般方框图和“闭环”增益 (... 实际的负反馈放大电路 ,并非都是由基本放大电路和反馈网络构成一个闭环系统 <1>,还有由多个基本放大电路和多个反馈网络构成的多环系统 (多环负反馈电路 ) <2 >.给出几种多环负反馈放大电路的一般方框图和“闭环”增益 (传输函数 )一般表达式 。 展开更多
关键词 负反馈放大电路 系统 反馈深度 反馈网络 传输函数 交叉式 重叠
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颈椎张口位摄片方法的改良
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作者 刘丽伟 《实用医技杂志》 2005年第05B期1367-1367,共1页
关键词 颈椎张口位摄片方法 诊断 椎齿状突根部骨折 重叠
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All-solid-state ultraviolet laser based on frequency doubling in an external ring cavity
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作者 SHEN Gao WANG Bao-shan +3 位作者 TAN Hui-ming PENG Ji-ying FU Xi-hong ZHAO Yu-huan 《Optoelectronics Letters》 EI 2007年第6期448-450,共3页
An all-solid-state ultraviolet laser based on frequency doubling in an external ring cavity with low input pump power is reported. Both second harmonic generation (SHG) and fourth harmonic generation (PRIG) occurr... An all-solid-state ultraviolet laser based on frequency doubling in an external ring cavity with low input pump power is reported. Both second harmonic generation (SHG) and fourth harmonic generation (PRIG) occurred in an external threemirrors ring cavity. The need for impedance matching of this cavity to the input radiation was eliminated and the cavity adaptation was simplified, because the mirrors were not highly reflecting at 1064 nm and the cavity resonates only at 532 rim. Experiment results demonstrate that the conversion efficiency of this external cavity is higher than that of the singlepass condition. 展开更多
关键词 固体 激光器 外部空腔 频率重叠
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Consumption and Leisure Patterns of Youth in Turke
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作者 Guliz Mugan Akinci 《Journalism and Mass Communication》 2012年第11期1073-1083,共11页
Consumption-oriented daily life resulted in new forms of consumption spaces in many cities. Among these spaces, shopping malls are significant with their improved physical and social environments for consumption and l... Consumption-oriented daily life resulted in new forms of consumption spaces in many cities. Among these spaces, shopping malls are significant with their improved physical and social environments for consumption and leisure for all the family. One of the important marginalized groups, to whom the mall appeals, are young people. Within this framework, the main purpose of this study is to investigate the consumption and leisure practices and experiences of young people in Turkey from their point of view. Migros, a shopping mall in Ankara, was chosen as the site for this research, where both consumption and leisure practices are overlapping within the same space. The research was carried out through observation and in-depth interviews with 104 teenagers. The results indicated that shopping malls were the main leisure and consumption site for teenagers. Teenagers' choice of malls as their favorite leisure and consumption space were found to be the result of some factors such as restrictions which were provoked by their parents, security concerns, location of the mall, and accessibility and limited financial resources. These factors seemed to lead to restrictions in the choice of places to spend their leisure time and limit the use of leisure spaces other than malls. As a consumer group in the mall space, teenagers had some complaints about the prices of facilities which seemed to be influential on their choices of consumption and leisure practices in the mall environment. 展开更多
关键词 CONSUMPTION LEISURE shopping malls Turkish youth social and physical factors in the mall space
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