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.     

烧结工序的物质流和能量流(火用)分析

本文讨论了烧结工序开展物质流和能量流的(火用)分析意义,应用物质流分析方法,建立了烧结工序的物质流和能量流(火用)分析模型.应用该模型,分析了烧结工序的(火用)效率、(火用)损失,指出了烧结工序的节能方向和途径.     

On the Equivalent Keys in Multivariate Cryptosystems

The number of equivalent keys in multivariate cryptosystem is closely related to the scheme security. This study analyzes the structure of the private key space in some multivariate schemes.The result gives the lower bounds on the number of equivalent keys of some variants of the hidden field equation (HFE) scheme including plus, minus-plus, embedding, and internal perturbation. This method estimates the number of invertible transformations which maintain the form of the central map invariant. Furthermore,a formal proof shows that the two modifications of fixing and embedding are equivalent in security analyses of multivariate schemes. Also this paper corrects previous proofs in Wolf’s work on the number of equivalent keys in HFEv,the unbalanced oil and vinegar (UOV) scheme, and the stepwise triangular systems (STS).     

一类二阶奇异微分方程初值问题解的唯一性

讨论了一类二阶奇异微分方程的初值问题,运用等价的非线性变换,把奇异微分方程转换成非奇异微分方程,从而进一步得到了在一定条件下该初值问题解的唯一性结果.     

铬（Ⅲ）-乳酸配合物的合成与结构表征

利用溶液法合成了[Cr2(HLact)6]配合物,同时对该配合物进行红外光谱、X-衍射等表征,结果表明:该配合物为三斜晶系,空间群为P-1,a =9.496(3) (A),b = 12.239(3)(A), c = 15.017(4)(A), (α= 96.873(5)0, (β=91.189(5)0, (γ= 92.312(6)0, V=1730.7(8)(A)3, Z=2.     

一类带奇性的椭圆型方程的正解

通过山路引理，研究一类带奇性的椭圆型方程正解的存在性问题。利用变分方法，得出在α的某一条件下此方程存在正解。     

型A-(￡)-宽广半群的平移壳

证明了型A-(￡)-宽广半群的平移壳仍为型A-(￡)-宽广半群.     

双十二烷基二甲基溴化铵对羟基磷灰石粒度的影响

在沉淀法生成的纳米羟基磷灰石(HA)胶体中加入阳离子表面活性剂双十二烷基二甲基溴化铵(DDAB)制备纳米级HA粉体,研究其在制备过程中对颗粒大小的作用,分别用激光粒度分析仪、SEM和TEM检测了HA粉体的粒度、形态和相组成,结果表明,表面活性剂可以得到粒度小,但分布较宽的纯羟基磷灰石。     

活性炭负载纳米零价铁去除溴酸盐的研究

实验采用液相还原法制备活性炭负载纳米零价铁材料(nZVI/AC),并利用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等对其结构进行表征.考察了不同反应条件下nZVI/AC对BrO3-的去除效率,并研究其去除机理.结果表明nZVI/AC具有很高的表面反应活性,且nZVI和活性炭(AC)之间存在协同作用. BrO3-的去除效率随 pH 值的减小而增大, 共存离子NO3-和SO42-对其去除率影响不大但降低了去除速率.机理分析表明BrO3-被nZVI/AC吸附而使局部BrO3-浓度升高,并被nZVI迅速还原为无毒的Br-.     

阿达玛对弗雷歇关于线性泛函表示的影响

目的研究阿达玛(J.Hadamard,1865—1963)对弗雷歇(Maurice Fréchet,1878—1973)关于线性泛函表示思想的影响。方法历史分析和文献考证。结果弗雷歇受到阿达玛在线性泛函表示方面的影响,对阿达玛1903年的表示形式进行了改进,使其应用范围更加广泛。结论弗雷歇在线性泛函表示方面的工作是对阿达玛相关工作的继承和发展。