非线性等重码的广义Hamming重量

根据非线性码的广义Hamming重量的定义,讨论了非线性等重码的广义Hamming重量的一些性质,同时给出了第2,第3广义Hamming重量的表达式。     

论网络中的一种差错检测技术--CRC

CRC是目前网络中普遍采用的一种检测码 ,只有真正了解和掌握它 ,才能选择合适的CRC ,使传输帧达到冗余位少、漏检率低的目的 ,从而提高传输效率。本文从CRC的理论基础、冗余位的产生方法、性能分析及实现手段等方面作了全面的剖析     

DS-CDMA的MIMO系统中的空时多用户检测

Space-time signal processing based on multiple-input multiple-output（MIMO） systems is an active research field in which interfering signals are cancelled and multiuser detection is achieved using space diversity. In a Rayleigh fading channel, space-time block cedes using multiple transmitting antennas can improve system performance and reduce bit-error-rate for multiuser detection. In this paper, several antenna configurations are designed for DS-CDMA communication in MIMO systems. Space-time linear multinser detection and space-time serial interference cancellation multiuser detection are simulated. Bit-error-rate and computation complexities of the two methods are compared. Conclusions are given in the end.     

利用一种新LDPC码的编码OFDM系统性能分析

提出了一种新的构造LDPC码的方法, 并把用该方法产生的LDPC码应用到编码正交频分复用(OFDM)系统中进行了研究. 该方法拓展了单位阵移位构造的LDPC码, 它利用简单的不等式可确保在置换单位阵构造中不会产生Tanner图中的短圈, 使得产生的LDPC码的Tanner图最小圈长为8. 由于该类码是准循环码以及其校验矩阵所固有的分层结构, 编码器和解码器都易于实现, 它们分别是线性可编和线性可译的. 所提出的LDPC码码率范围较大, 可以灵活选取. 利用迭代解码进行计算机仿真, 发现新的LDPC码比其他的规则LDPC码在编码OFDM系统中具有更好的性能.     

一种具有可分级转码能力的空时OFDM视频传输方法

结合空时OFDM和转换编码技术,提出了一种无线衰落信道下具有可分级转码能力的鲁棒视频传输方法.采用可分级转码器将高质量的MPEG-2压缩视频转换为低码率、低分辨率MPEG-4可分级码流来满足网络带宽和终端设备显示的要求.在接收端采用一种层干扰抑制算法,使得分层空时OFDM系统不同层的传输性能存在差异,从而使系统具有不对等保护能力.根据分级码流的重要程度不同,将转码输出的可分级码流分别由分层空时编码OFDM系统的不同层来实现视频的鲁棒传输.实验结果表明:在典型的随机突发错误的无线环境下,提出的具有可分级转码能力的系统的视频传输性能优于传统的非分级转码的视频传输系统.     

Faculty and Academic Integrity: The Influence of Current Honor Codes and Past Honor Code Experiences

This survey of faculty at honor code and non-honor code institutions investigated the influence of honor codes on faculty attitudes and behaviors. As hypothesized, we found that honor code faculty have more positive attitudes toward their schools' academic integrity policies and are more willing to allow the system to take care of monitoring and disciplinary activities. Faculty in noncode institutions have less positive attitudes and are more likely to take personal actions designed to both catch and deal with cheaters. We also investigated the potential influence of a student honor code experience on faculty attitudes. We found that, in noncode environments, faculty who had an honor code experience as a student were more likely to believe that students should be held responsible for peer monitoring and to say that they deal personally with cheating. Implications for higher education institutions are discussed.     

利用集合论构造一类Cartesion认证码

利用集合论构造了一个Cartesion认证码 ,并计算了码参数 ,敌方假冒、替换成功的概率和r阶欺骗成功的概率 ,并推广了王永传、杨义先等人的结果     

先秦两汉现实女性题材赋研究

先秦两汉现实女性题材赋经历了漫长曲折的发展历程,根据赋家之创作主旨和表达内容,将其概括为“言志”、“抒情”和“其他”三类进行分析论述。联系当时的社会文化环境,试图对其发展状况与嬗变轨迹给予较为合理的解释。     

《兄弟》:从寓言到"写真"

《兄弟》暗示了余华小说艺术发生的新变。其《兄弟》之前的作品多是寓言性的,《兄弟》逐步走向了"写真",作品因而消解了隐喻性和荒诞性色彩;人物也不再是小说叙事结构中的符号和工具,而是具备了性格特征且具有个性魅力的形象;小说的主题内容也从"闹剧"走了出来,而成为描绘人物命运、揭示历史真相的正剧,其中也透露出作家的情感和价值立场。     

In defence of speech codes

It has been strongly maintained that speech codes at universities interfere with academic freedom, and also, to the contrary, that such speech codes must be developed to restrain appeals to academic freedom that function to restrain the freedom of marginalized groups to participate fully in the university. This essay argues that forms of speech can in fact constrain the freedom, including legitimate academic freedom, of many persons, not only, but importantly including, marginalized groups; that speech codes have always existed; and that reasonable ones can be developed which do not interfere with freedom of teaching, learning, and research in the university; and in particular that definitions of academic freedom such as that developed by the Canadian Association of University Teachers (CAUT) are compatible with such speech codes.