Construction of protograph LDPC codes with circular generator matrices

The application of protograph low density parity check(LDPC) codes involves the encoding complexity problem.Since the generator matrices are dense,and if the positions of "1" s are irregularity,the encoder needs to store every "1" of the generator matrices by using huge chip area.In order to solve this problem,we need to design the protograph LDPC codes with circular generator matrices.A theorem concerning the circulating property of generator matrices of nonsingular protograph LDPC codes is proposed.The circulating property of generator matrix of nonsingular protograph LDPC codes can be obtained from the corresponding quasi-cyclic parity check matrix.This paper gives a scheme of constructing protograph LDPC codes with circulating generator matrices,and it reveals that the fast encoding algorithm of protograph LDPC codes has lower encoding complexity under the condition of the proposed theorem.Simulation results in additive white Gaussian noise(AWGN) channels show that the bit error rate(BER) performance of the designed codes based on the proposed theorem is much better than that of GB20600 LDPC codes and Tanner LDPC codes.     

大学考试时间表问题的混合遗传算法求解

考试时间表问题是一类典型的组合优化问题,也是NP难问题。分析了大学考试时间表编排的特点,给出了一种解决考试时间冲突的自动生成考试时间表的可行时段-查找算法。为进一步解决时间间隔问题,将可行时段-查找算法嵌入到遗传算法中形成混合遗传算法。实验结果表明,本文提出的混合遗传算法能快速、有效的解决大学考试时间表问题。     

基于PLC-200的大功率直流电动机调速系统的设计

以大功率直流电动机调速系统为研究对象,采用西门子PLC-200作为主要控制器件,西门子6RA70作为执行单元,罗升触摸屏作为上位机,同时采用增量式PID控制算法实现大功率直流电动机自动直流调速系统的设计.     

求解频率指配问题改进的完全图算法

以四级预测模型为基础,提出改进的完全图算法,并推导出该算法计算量的解析式,从理论上证明了改进的完全图算法性能上的提高.四级预测模型来判断两电台之间的兼容性,而改进的完全图算法调用四级预测模型来搜索出多电台间的所有可用频组,进行了小规模电台数目电子信息系统的完整电磁兼容分析,完成了系统内的频率指配.实际工程应用的结果与理论一致.     

一种椭圆曲线标量乘法的快速算法

在经典3P快速算法的基础上,为避免复杂的求逆操作,提出了优化途径和措施,利用牺牲代价较低的乘法操作以换取求逆操作.给出了一个由椭圆曲线点P直接计算3kP的算法,新算法显著减少了计算量,提高了算法效率,并保证了计算结果的准确性.     

A Scalable Data-Distributed Algorithm for Volume Rendering on Parallel Virtual Machines

IntroductionVolume rendering is an essential method forexploring the inner structure of complex3- D data.One of the classic volume- rendering approaches isthe so- called ray- casting algorithm. In thisalgorithm,each image pixel is rendered accordingto a ray which is emitted from the pixel and isoriented towards the observation direction. Thecomputations along each ray consist of two typicalphases:resampling of the3- D data followed by thecolor composition. Unfortunately,both phases aretime c…     

矿井通风困难时期通风优化方案研究

针对陕煤澄合矿业有限公司二矿分公司矿井三水平延伸工程遇到的通风系统通风困难时期状况,文中在分析了矿井通风阻力分布特征和主要通风机性能特性的基础上,结合矿井三水平延伸工程即将完成主皮带斜井工程的情况,提出改善通风系统困难状况的2种方案,一是在东、西风井安装主通风机,进行双风机并联通风,二是利用主皮带斜井为回风井,其余井筒做进风井通风.经过分析发现,采用双风机并联通风存在有通风网络公共风路风阻大小与待选通风机风压之间存在相关性关系,澄合二矿风机并联工作不满足这一关系.经过通风网络解算,验证得出主皮带斜井回风可以改善通风系统困难状况,从而确定了这一较好方案,现场工程验证了所选择通风方案能够满足矿井安全生产要求.     

MA(2)序列的偏相关函数

首次用矩阵分解的简便方法求出了MA(2)序列的偏相关函数的精确解析表达式.     

Effects of fragmentation on genetic variation in populations of the terrestrial earthworm Drawida japonica Michaelsen, 1892 (Oligochaeta,Moniligastridae) in Shandong and Liaodong peninsulas,China

Earthworms are excellent indicators of landscape fragmentation due to their widespread distribution and poor dispersal abilities over water. Based on field studies conducted in the Shandong and Liaodong peninsulas and their associated islands during summer 2009, we analysed the genetic variation of Drawida japonica Michaelsen, 1892 (Oligochaeta, Moniligastridae) using DNA sequences of the 16S and 28S ribosomal genes in samples obtained from 13 localities, 12 of which were islands, one artificially connected to the mainland by man (Yangma SC). We identified 55 haplotypes among 79 samples, based on 1094 bp, including 47 unique haplotypes. The phylogenetic tree topologies showed two distinct clades. A multiple-apex Poisson distribution using a mismatch analysis of nucleotides was also detected. Results of a Tajima D neutral test were not significant (p > 0.05). Genetic divergence among populations was much larger than within populations. A positive relationship between genetic diversity and island area was revealed, but no significant correlation between genetic diversity and distance to the nearest larger landmass was found. These results indicate that the intraspecific genetic diversity of D. japonica has been influenced by geographic isolation (i.e. island habitat). Passive transport via anthropogenic activities or nonhuman vertebrates (birds or mammals) may also play a key role in dispersal.     

Chaotic Genetic Algorithm-Based Forest Harvest Adjustment

Forest harvesting adjustment is a decision-making, large and complex system. In this paper, we analysis the shortcomings of the traditional harvest adjustment problems, and establish the model of multi-target harvest adjustment. As intelligent optimization,chaotic genetic algorithm has the parallel mechanism and the inherent global optimization characteristics which are suitable for multi-objective planning the settlement of the issue, Specially in complex occasions where there are many objective functions and optimize variables. In order to solve the problem of forest harvesting adjustment, this paper introduces a genetic algorithm to the Forest Farm of Qiujia Liancheng Longyan for forest harvesting adjustment firstly. And the experimental result shows that the method is feasible and effective, and it can provide satisfactory solution for policy makers.