An Ensemble of Iteratively Decodable Codes Constructed Based on a Superposition Method

In this paper, the construction of new families of error-correcting codes adapted from Boutros and Lentmaier's generalized low-density (GLD) codes, which we called generalized irregular low-density (GILD) codes, is investigated. By introducing irregular base matrices, significant improvements on Boutros and Lentmaier's results are achieved. Two cases are considered; in the first case, the same constituent code is used, and in the second case, different constituent codes are used. It is proved by an ensemble performance argument that these codes exist and are asymptotically good in the sense of the minimum-distance criterion. It is also proved that the performance of GILD codes approaches the binary symmetric channel capacity limit. Iterative decoding of GILD codes for communication over an additive white Gaussian noise channel is also studied. The high flexibility in selecting the parameters of GILD codes and their better performance and higher rate make them more attractive than GLD codes, and hence, suitable for small and medium block lengths forward-error-correcting schemes. Comparisons of simulation results between some GILD codes and some good low-density parity-check codes show very close performances     

一种快速判断非唯一可译码的方法

本文介绍了一种快速判断非唯一可译码的方法,该方法针对现存判别唯一可译码的方法(即:根据异前缀码来进行判断的方法以及A.A.Sardinas和G.W.patterson判断法)所存在的不确定性、大运算量等问题,提出一种方法对非唯一可译码作出准确判断.该方法具有判别简单,运算量小等特点,可以广泛应用于非唯一可译码的判断.该方法对于通信、信息论方面的研究具有一定的意义.     

一种确定Turbo乘积码迭代因子的方法

提出一种确定Turbo乘积码迭代因子的算法。建立信道模型,生成测试软信息R;生成一组备选迭代因子向量,在备选迭代因子空间里用MATLAB仿真Chase-Pyndiah迭代译码算法流程,选择最优的迭代因子;迭代因子优劣的判据为迭代译码器的误码率以及迭代次数。实验结果表明,最优迭代因子有效地加速了迭代译码器的收敛速度,降低了译码的功耗。     

Turbo乘积码在衰落信道中的应用

基于Turbo乘积码的编译码原理,利用Matlab仿真工具,对以(64,57,4)扩展汉明码为子码的Turbo乘积码进行迭代次数、量化比特数等不同参数的性能仿真,根据仿真结果选取最佳的设计参数,同时通过仿真给出了Turbo乘积码在衰落信道中的应用效果。结合Matlab仿真,在Quartus环境中完成编译码算法的硬件设计与调试,并将其应用到无线通信调制解调器中。测试结果表明,Turbo乘积码显著改善了调制解调器在衰落信道中的误码性能。     

设计模式在数据存储设计中的应用

基于设计模式设计了数据存储系统,将存储的过程分解为导出与保存两步,将导出与保存解耦,减少了设计类的数量,使设计能适应变化,具有良好的扩展性和易复用性。     

迭代译码的级联Reed-Solomon乘积码与卷积码

该文提出用Reed Solomon(RS)乘积码作为外码,卷积码作为内码的级联码方案并且内外码间用Congruential向量生成的交织图案对RS码符号进行重排列。对此级联码采用的迭代译码基于成员码的软译码算法。当迭代次数达到最大后,通过计算RS码的校正子,提出一种纠正残余错误的方法,进一步提高了系统的误比特性能。仿真结果表明,在AWGN信道中与迭代译码的级联RS/卷积码相比,当误比特率为1e-5时,新系统的编码增益大约有0.4 dB。     

一种基于张量积扩散的非监督极化SAR图像地物分类方法

针对相似度表达的困难性以及极化SAR图像中固有的相干斑噪声问题,该文提出了一种基于张量积(TPG)扩散的非监督极化SAR图像地物分类算法。张量积扩散一般用于光学图像的分割或检索,目前研究表明,其已可用于极化SAR(PolSAR)图像地物分类。基于张量积扩散可以稳健地度量数据点之间的测地线距离,因此能够更好地挖掘数据点之间内在的相似度信息。首先,将极化SAR图像进行分割,生成许多超像素;其次,基于超像素提取7种特征并生成一个特征向量,进而利用高斯核构建相似度矩阵;再次,基于已构建的相似度矩阵,利用张量积扩散沿着数据点的内在流形结构进行相似度的传播,实现全局的相似性度量,从而获得一个具有更强判别能力的相似度矩阵;最后,基于此相似度矩阵进行谱聚类以得到地物分类结果。该文在仿真和实测极化SAR图像上均进行了大量实验,并与4种经典算法进行对比,结果表明该方法可以有效地结合空间邻域相似度信息并取得更高的分类精度。      

Discovering Biclusters by Iteratively Sorting with Weighted Correlation Coefficient in Gene Expression Data

We propose a framework for biclustering gene expression profiles. This framework applies dominant set approach to create sets of sorting vectors for the sorting of the rows in the data matrix. In this way, the coexpressed rows of gene expression vectors could be gathered. We iteratively sort and transpose the gene expression data matrix to gather the blocks of coexpressed subset. Weighted correlation coefficient is used to measure the similarity in the gene level and the condition level. Their weights are updated each time using the sorting vector of the previous iteration. In this way, the highly correlated bicluster is located at one corner of the rearranged gene expression data matrix. We applied our approach to synthetic data and three real gene expression data sets with encouraging results. Secondly, we propose ACV (average correlation value) to evaluate the homogeneity of a bicluster or a data matrix. This criterion conforms to the intuitive biological notion of coexpressed set of genes or samples and is compared with the mean squared residue score. ACV is found to be more appropriate for both additive models and multiplicative models.

空间数据存储技术及其应用

文章介绍了GIS中空间数据礅储的特点，并讨论了传统的空间数据存储技术，和当前较为先进的基于RDBMS，面向对向的空间数据存储技术，以及空间数据仓库等前沿技术，并从数据存储角度介绍了GROW平台的结构和特点，以及在GROW系统中应用的G－A和S－R数据模型及其数据存储技术的特点和实现。     

存储虚拟化技术在双活数据中心中的应用

主要结合存储虚拟化技术在前期容灾方案的基础上,构建一个真正意义上的双活数据中心方案,并根据IT系统的实际部署架构对方案涉及的各个层面的改造进行分析,以作为IT系统双活数据中心建设的参考。     

数字全息数据存储系统中的格雷映射等重调制码的设计

在数字全息数据存储系统的记录通道中,使用二进制映射等重调制码有利于信号的检测.本文作者提出了6:8格雷映射等重调制码的编码方案,将每6比特数据视为一个格雷码字,而相应的等重码设计为具有2单位距离特性.当检测到的8比特码字中发生一个2码元交换错误时,该方案具有一定的容错能力.误码性能的仿真结果表明,在系统的信噪比较低时6:8格雷映射等重调制码优于6:8二进制映射等重调制码.     

数据存储技术在卫星广播电视监测中的应用

本文主要介绍卫星广播电视监测系统对存储技术的要求、存储技术方案的选择、设计思路以及存储局域网技术在卫星电视监测系统中的具体应用.     

水蓄冷空调系统在数据中心工程中的应用

介绍了水蓄冷空调系统的特点和优势,举例说明其在某数据中心工程的应用,并通过与常规空调方案在设备初投资、节能等方面的分析比较,说明水蓄冷空调系统在数据中心工程中的应用具有广阔的前景。     

改进的MSK在曼彻斯特码数据传输中的应用

本文介绍了MSK(最小频移键控)调制解调的基本原理及设计方法，并对用Costas环提取载波的解调方案进行了改进，解决了载波提取和定时提取相互干扰的问题。最后通过仿真将它与常用的4PSK(四相绝对相移健控)的抗噪声及频谱性能进行了比较，得出MSK调制可用于测井技术来提高传输速率的重要结论。     

A New Unitary Space-Time Code with High Diversity Product

In this paper, we propose new full diversity unitary space-time codes based on Hamiltonian constellation designs. Our proposed constellations can be used for any number of antennas and for any data rate. For two transmitter antennas, the constellations are constructed from cyclic group codes. For a larger number of transmitter antennas, the design employs the direct sum of 2 times 2 Hamiltonian matrices and roots of unity. We give some examples of proposed constellations, and also show that they outperform known design techniques in the literature     

An Optimal Transform Trellis Code with Applications to Speech

This paper presents a rate-distortion derived transform trellis coding (TTC) scheme with applications to Gaussian AR sources and speech data. The optimal encoder consists of a Karhunen-Loeve transform (KLT) on the source output, followed by a search on a trellis structured random code, where the decoder is a time-variant nonlinear filter. The scheme is implementable and applicable to stationary Gaussian sources with a bounded and continuous power spectrum and the squared error distortion measure. The code construction is based on the power or eigenvalue spectrum of the source with no restriction on the coding rate. The TTC scheme is first applied to encode a Gaussian AR source often used to model speech. Simulations were conducted at several rates, using an optimal KLT and the suboptimal discrete cosine transform (DCT). Results demonstrate that the DCT performs as well as the KLT, and both yield average distortions very close to the distortion-rate function. For speech data, an adaptive version of the DCT TTC scheme is applied to encode two speech sentences at several coding rates. The adaptation is controlled by an estimate of the short-term eigenvalue spectrum which is transmitted as side information to the receiver. The proposed scheme is a very efficient speech waveform coder that provides reconstructed speech with very high signal-to-noise ratio values and very good perceptual quality at low bit rates.     

现场总线技术在汽车生产物流系统中的应用

本文介绍了现场总线技术在汽车生产物流系统中的应用，文中阐明了采用INTERBUS总线构成的汽车生产物流信息系统的功能和特点，该系统实现了汽车生产物流中的管控一体化，取得了良好的经济效益。     

事务模型在网络存储数据备份中的应用

大型数据库可能会同时使用多个磁盘.文章引入了全新的原子中断组模型,使得多个磁盘上的数据在备份/恢复时,能够保持其完整性和一致性,从而维护了数据的可靠性、整合性,大大提高了存储管理的性能和效率.     

数据存储管理技术研究与应用

阐述了数据集中管理技术的研究内容,并从数据库集中管理技术和一体化数据存储模型技术两个方面分别阐述了数据集中管理技术的研究以及应用效果.通过建立满足油田公司勘探与生产主要专业的数据整合技术管理体系,实现数据统一集中管理和应用共享.     

Turbo乘积码的软译码研究

Turbo码作为一种新型的纠错编码类型备受通信界的注目,它的纠错能力接近Shannon极限。阐述了Tur-bo乘积码的软译码原理及其算法。