基于压缩感知的短波多天线分集合并接收方法     

徐婷  彭亚红  罗建宝  刘俞伯 《大众科技》2012,14(4):82-83,88

在短波通信中,为了克服信道中的多径干扰、衰落和多普勒频移等对接收信号的影响,实现低信噪比下,信号高速传输,文章提出了一种基于压缩感知的短波多天线分集合并接收系统设计方法。该系统有效地将OFDM调制方式和压缩感知相结合,充分利用了OFDM调制方式频谱效率高、抗多径衰落能力强等优势以及压缩感知抗干扰能力强、能以低采样率高精度重建待测信号的特性。实验结果表明:与现有的短波通信系统相比,在信号受强噪声干扰且高速传输的情况下,重建性能最优。  相似文献   

浅谈数字图像压缩编码技术     

阴躲芬  李一民  王英妹  王林 《科技广场》2008,(1):138-139

本文论述了数字图像压缩编码技术的必要性和可行性.介绍了三种压缩编码方式(信息保持编码、保真度编码、特征提取),并对具体的编码方法进行了分类(平均信息法、预测编码法、变换编码方法等),最后对图像压缩编码技术的发展方向进行了展望。  相似文献   

基于MPEG-4的视频点播系统(VOD)的设计     

韩红宇  吴雪毅 《漯河职业技术学院学报》2007,(2)

新一代的音视频压缩标准MPEG-4不断走向成熟,成为视频应用的不可或缺的一个基础标准,具有的高压缩率、强交互能力和灵活分级能力,使之在网络媒体特别是视频点播中拥有广阔的应用前景。本文针对视频点播系统的应用,提出了MPEG-4视频点播系统的结构,实现了MPEG-4视频点播服务器的构建。  相似文献   

An approach to offline handwritten Chinese character recognition based on segment evaluation of adaptive duration     

李国宏  施鹏飞 《浙江大学学报(A卷英文版)》2004,5(11):1392-1397

This paper presents a methodology for off-line handwritten Chinese character recognition based on mergence of consecutive segments of adaptive duration. The handwritten Chinese character string is partitioned into a sequence of consecutive segments,which are combined to implement dissimilarity evaluation within a sliding window whose durations are determined adaptively by the integration of shapes and context of evaluations. The average stroke width is estimated for the handwritten Chinese character string,and a set of candidate character segmentation boundaries is found by using the integration of pixel and stroke features. The final decisions on segmentation and recognition are made under minimal arithmetical mean dissimilarities. Experiments proved that the proposed approach of adaptive duration outperforms the method of fixed duration,and is very effective for the recognition of overlapped,broken,touched,loosely configured Chinese characters.  相似文献   

An approach to offline handwritten Chinese character recognition based on segment evaluation of adaptive duration     

李国宏  施鹏飞 《Journal of Zhejiang University. Science. B》2004,(11)

  相似文献   

冰雹灾害对黑龙江农业的影响及防御措施   总被引：1，自引：0，他引：1  

高维霖  徐宝磊 《黑龙江科技信息》2013,(5):7-7

冰雹是危害农业的主要自然灾害之一。冰雹灾害是一种局部地区性强、季节性明显、来势急、持续时间短、以砸伤为主的气象灾害,常伴有大风、暴雨,常给农牧业生产,尤其是给丰收在望的农作物带来重大损失,甚至颗粒无收。冰雹对农作物的危害特点,冰雹灾害的防御补救措施。  相似文献   

Innovation and business survival: A long-term approach     

José M. Ortiz-Villajos  Sonia Sotoca 《Research Policy》2018,47(8):1418-1436

This paper explores the influence of innovation on the probability of survival of two hundred top British firms founded throughout the nineteenth and twentieth centuries. To this end, we have collected the firms’ significant innovations and classified them by Schumpeterian types, patented and non-patented and domestic and imported. The number of patents registered by the firms throughout their lifetime ?a rough measure of their incremental innovation activity– has also been recorded. In addition, twelve control variables ?five characteristics of the firms and seven of their business leaders– have been included. Both log-normal and gamma duration models have been used in the analysis. They have been estimated, firstly for the whole set of firms and, secondly, for the manufacturing and the service firms separately to control for industry differences. The results of the log-normal and gamma estimations are highly coincident, with some nuances. The significant innovations ?particularly new processes, non-patented and domestic ones– have been found to positively influence the probability of business survival. The number of patent applications seems to increase the survival probability of the manufacturing firms, but not of the service ones. Among the control variables, the firm’s size, its international dimension, and the age of the business leader at entry seem to be the most influential ones on business survival, although there are some differences between manufacturing and services. The main results are robust to the division of the sample by entry period.  相似文献   

分布式网络系统日志的安全性研究   总被引：3，自引：0，他引：3  

黄文  文春生  欧红星 《零陵学院学报》2004,(5)

日志文件分析是系统安全检测的重要内容;同时日志文件也是计算机取证的重要依据;本文针对分布式网络日志文件的安全性隐患,从几个关键问题着手,提出了分布式网络日志文件自身的安全管理模型并给出了具体的实现方案。  相似文献   

对分形图像压缩编码方法的探讨     

王芳  赵德平  李井永 《和田师范专科学校学报》2007,27(4):4-5

分形图像压缩编码是图像压缩领域中一种全新的编码算法,具有潜在的高压缩比、高信噪比以及任意尺度上的精细放大等特性。本文论述了分形图像压缩的背景、编码方法、改进方法和发展趋势。  相似文献   

基于BWC的XML文本数据索引技术研究     

仲志平  刘渝妍  孙建洪 《昆明师范高等专科学校学报》2011,(3):60-63

在XML文档中,相当大的部分是由文本数据组成的,针对XML文本数据占用空间较大、对压缩文本数据有效搜索效率较低的难点,基于BWC提出了压缩XML文本数据索引的技术,通过构造全文本数据模型,并利用整体压缩自索引存储XML文档的文本数据,实验结果表明,该技术不仅有效支持XPath查询语言文本搜索,而且内存消耗相对较小,实现了中小规模数据的内存搜索.  相似文献