A simple channel estimator for space-time coded OFDM systems in rapid fading channels

A simple channel estimator for space-time coded orthogonal frequency division multiplexing (OFDM) systems in rapid fading channels is proposed. The channels at the training bauds are estimated using the EM (expectation-maximization) algorithm, while the channels at the data bauds are estimated based on the method for modelling the time-varying channel as the linear combination of several time-invariant "Doppler channels". Computer simulations showed that this estimator outperforms the decision-directed tracking in rapid fading channels and that the performance of this method can be improved by iteration.     

一种基于零树的树形扫描图像压缩编码方法

嵌入式零树编码被认为是目前国际上最先进的图像编码方法之一，但该算法在编“孤立零”码时会造成比特位冗余．因此本文提出了基于零树的树形扫描的图像压缩编码方法．实验结果表明该方法在保证恢复图像具有良好视觉效果的前提下，提高了压缩比，缩短了编码时间．     

一种快速、有效的量化与基于小波的图像压缩

量化是利用小波变换的图像压缩编码技术的关键环节之一。矢量量化和标量量化各有长短,二者有机地结合起来,称为混合量化(HQ—Hybrid Quantization)。它既有矢量量化的高效率,又具有标量量化的简单性,不需要进行码书训练,不要做乘除法。     

Wavelets: Applications to image compression-II

We explain here, the wavelet based thresholding procedure, one of the key factors behind the successful application of wavelets in image compression. We then elaborate on quantization and go on to outline the basic ideas underlying Huffman coding, the other important tool for data compression.     

Local curve fitting based Lagrange multiplier selection for Id-slice in multi-view video coding

The rate and distortion of Id-slice do not fit the globally linear relationship on a logarithmic scale. Lagrange multiplier selection methods based on the globally linear approximate relationship are neither efficient nor optimal for multi-view video coding （MVC）. To improve the coding efficiency of MVC, a local curve fitting based Lagrange multiplier selection method is proposed in this paper, where Lagrange multipliers are selected according to the local slopes of the approximate curves. Experimental results showed that the proposed method improves the coding efficiency. Up to 2.5 dB gain was achieved at low bitrates.     

基于扎根方法的IT外包企业创新空间的研究

 IT外包中接包方越来越多地参与创新活动,而与之相应的问题是IT外包企业如何拥有一定的创新空间。对此我们于2010年对16家IT外包公司进行走访及高层访谈,并利用建构型扎根方法对其中9家面向欧美客户提供离岸IT服务的企业的访谈文稿进行分析,对这一问题进行探索性研究。我们使用了适合于质性研究的内容分析软件NVIVO8,获得了IT外包企业创新空间的模型。本研究结果表明：拥有创新空间的IT外包企业具备以下三个能力：知识获取能力、质量控制能力、传统竞争能力。在个人影响力、与客户维持良好关系的伴随影响下,IT外包企业的知识获取能力、质量控制能力和传统竞争能力促进其沟通能力和文化交融能力的形成,再加上比客户在某些技术领域成熟的IT外包技术优势,这三者共同促进IT外包企业创新空间的形成。本研究可为IT外包企业创新空间的定量研究提供基础。     

A Fast Fractal Image Compression Coding Method

Fast algorithms for reducing encoding complexity of fractal image coding have recently been an important research topic.Serach of the bast matched domain block is the most computation intensive part of the fractal encoding process.In this paper,a fast fractal approximation coding scheme implemented on a personal computer based on matching in range block‘s neighbours is presented.Experimental results show that the proposed algorithm is very simple in implementation,fast in encoding time and high in compression ratio while PSNR is almost the same as compared with Barnsley‘s fractal block coding.     

瑞利衰落信道下空时分组码的性能分析

空时分组码是利用多输入-多输出（MIMO）无线通信系统的本质特征。给出在瑞利衰落信道下正交空时分组码瞬时接收信噪比的一般表达式,在此基础上推导出正交空时分组码在M—PSK和M—OAM调制下误符号率的闭式表达式,并给出数值分析结果。结果表明,空时分组码是一种适于高速无线通信系统的优选方案。     

关于字典编纂创新的思考和作为

字典编纂势须与时俱进,开拓创新,适应社会需要和时代发展水平。本研究主要着意和致力于将文字学、信息学、教学论、教育学,特别是心理学的有关观点、概念应用于字典的查字及输入方法和正文本体的编纂中,以增进字典的确切性、实用性和速检性实效(本研究的要领可见之于《汉字信息教学与输入字典》,知识产权出版社,2005)。     

引进企业管理系统的应用适应性改造

以对一英国公司管理系统立项改造并用于电厂管理为例,说明了引进企业管理系统的应用适应性改造的方法及内容。