DCT- and DST-based splitting methods for Toeplitz systems

New splitting iterative methods for Toeplitz systems are proposed by means of recently developed matrix splittings based on discrete sine and cosine transforms due to Kailath and Olshevsky [Displacement structure approach to discrete-trigonometric transform-based preconditioners of G. Strang type and of T. Chan type, SIAM J. Matrix Anal. Appl. 26 (2005), pp. 706–734]. Theoretical analysis shows that new splitting iterative methods converge to the unique solution of a symmetric Toeplitz linear system. Moreover, an upper bound of the contraction factor of our new splitting iterations is derived. Numerical examples are reported to illustrate the effectiveness of new splitting iterative methods.     

系数矩阵含参数分裂形式的SOR迭代法收敛性分析

给出预条件方后线性方程组的系数矩阵的一类含参数的分裂形式,使系数矩阵的分裂更加一般化,同时讨论在该形式下的SOR迭代法的收敛性,并与一般的预条件方法进行比较分析,说明这种方法收敛性更好,最后找到参数的最优选取.     

A Review of ABO3 Perovskite Photocatalysts for Water Splitting

Photocatalysts with perovskites for hydrogen production from aqueous solution were reviewed. Among the most of metal oxide photocatalysts, the family of ABO3 Perovskite-type oxide shows higher photocatalytie activity, especially alkaline earth titanate and alkali tantalate. Therein, sodium tantalate showed the highest activity for water splitting. The reasons for the high photocatalytic activity of ABO3 perovskties are considered to the diverse and flexible crystal structure. The photocatalytic activity of ABO3 perovskties can be improved by doping other element at A site, B site or O site and loading CO-catalysts such as NiO and Pt. In this paper, the mechanism of photocatalytic water splitting, the structure of ABO3 perovsktie, and Perovskite-type photocatalysts were reviewed.     

利用偏光分束棱镜测定波片的延迟量

在文〔３〕的基础上,提出了波片延迟量测量精度较高的方法。     

重质塔河原油的减粘裂化工艺

塔河原油是一种劣质、重质原油,该原油通过减粘裂化装置加工可得半成品的轻油,还可以得到合格的燃料油。     

Metal oxide photoelectrodes for hydrogen generation using solar radiation-driven water splitting

Metal oxide semiconductors are today the most promising materials for photoelectrochemical production of hydrogen by the method of the photoelectrolysis of water as the problems of the stability of photoelectrodes are basically solved only for such materials. The aim of this short review paper is the presentation of results in this field obtained both worldwide and by the authors of this paper. The factors determining the efficiency of photoelectrolysis and possible ways to increase the photocatalytic activity of semiconductor photoelectrodes are analyzed. It is shown that the development of new photoelectrodes made of solid solutions and more complicated multicomponent compositions are most promising. Possibilities to use porous and nanocrystalline oxide photoelectrodes in photoelectrochemistry are also discussed. Photoelectrolysis setups for the photoelectrochemical conversion of solar energy into hydrogen are briefly described.     

非线性平衡布尔函数及其构造方法

介绍了抗密码分析能力强的布尔函数的两个重要特性:平衡性和非线性,并研究了三种可产生具有高非线性的布尔函数的方法,即链接、分裂、修改序列。最后指出通过修改序列获得的平衡布尔函数比通过以往任何构造方法获得的具有更高的非线性。     

基于层叠遗传算法的配电网多层级无源光网络优化

对于配用电光通信网中无源光网络多层级、多节点网络规划问题,首次提出采用基本遗传算法实现多层级的循环继承的层叠遗传算法。其采用外层分光网络继承内层网络基因用于本层网络的适应度函数选择,该算法解决了多层级无源光(PON)网络各层级分光优化的问题,并且通过仿真证明了其可行性,实现了四层级网络星形结构拓扑优化。优化后的网络获得了最优的星形网络拓扑和通信建设成本的降低。     

Highly Porous Materials as Tunable Electrocatalysts for the Hydrogen and Oxygen Evolution Reaction

The facile preparation of highly porous, manganese doped, sponge‐like nickel materials by salt melt synthesis embedded into nitrogen doped carbon for electrocatalytic applications is shown. The incorporation of manganese into the porous structure enhances the nickel catalyst's activity for the hydrogen evolution reaction in alkaline solution. The best catalyst demonstrates low onset overpotential (0.15 V) for the hydrogen evolution reaction along with high current densities at higher potentials. In addition, the possibility to alter the electrocatalytic properties of the materials from the hydrogen to oxygen evolution reaction by simple surface oxidation is shown. The surface area increases up to 1200 m²g^?1 after mild oxidation accompanied by the formation of nickel oxide on the surface. A detailed analysis shows a synergetic effect of the oxide formation and the material's surface area on the catalytic performance in the oxygen evolution reaction. In addition, the synthesis of cobalt doped sponge‐like nickel materials is also delineated, demonstrating the generality of the synthesis. The facile salt melt synthesis of such highly porous metal based materials opens new possibilities for the fabrication of diverse electrode nanostructures for electrochemical applications.