An experimental study of an optical burst switching network based on wavelength-selective optical switches

In this article we report the system structure and test results of an experimental optical burst switching network with three edge router's and one core node. Wavelength-selective switches developed for this system and their characteristics are depicted. The implementation and performance of our new scheme for the just-in-time protocol are described. We also report experimental results of FTP and VOD services on this system. Some parameters, including traffic rate, average burst data length, and assembly time, are studied.     

Nanoscale structural characteristics and electron field emission properties of transition metal–fullerene compound TiC60 films

Transition-metal compound TiC₆₀ thin films were grown by co-deposition from two separated sources of fullerene C₆₀ powder and titanium. Study of structural properties of the films, by Raman spectroscopy, atomic force microscopy, and scanning tunneling spectroscopy reveals that the films have a deformed C₆₀ structure with certain amount of sp³ bonds and a rough surface with a large number of nanoclusters. z–V tunnelling spectroscopic measurements suggest that several charge transport mechanisms are involved in as the tip penetrates into the thin film. Conventional field electron emission (FEE) measurements show a high emission current density of 10 mA/cm² and a low turn-on field less than 8 V/μm, with the field enhancement factors being 659 and 1947 for low-field region and high-field region, respectively. By exploiting STM tunneling spectroscopy, local FEE on nanometer scale has also been characterized in comparison with the conventional FEE. The respective field enhancement factors are estimated to be 99–355 for a gap varying from 36 to 6 nm. The enhanced FEE of TiC₆₀ thin films can be ascribed to structural variation of C₆₀ in the films and the electrical conducting paths formed by titanium nanocrystallites embedded in C₆₀ matrix.     

EFP战斗部参数优化设计

文中在大量数值仿真的基础上利用正交设计方法对EFP战斗部参数进行了优化设计,通过优化找出EFP飞行速度及长径比与三个影响因素(药型罩曲率半径、装药高度直径比和药型罩厚度)之间的关系,确定了最佳参数组合,在此参数组合下可达到EFP速度和长径比的良好匹配,有效地提高了EFP的飞行性能.     

二级倒立摆最优控制器的设计与实现

建立了一套完整的二级倒立摆的实物系统.使用力学分析中的拉格朗日方程完成了二级倒立摆系统的数学建模.基于LQR方法对此二级倒立摆系统设计了一个最优控制器,并给出了一种选择加权阵Q和R的经验方法.在Simulink环境下完成了二级倒立摆控制系统的仿真,并成功实现了二级倒立摆的长时间稳定控制.结果表明二级倒立摆控制器的设计是成功的,它对外部干扰及建模未考虑因素都有较强鲁棒稳定性能.     

CuMgAl类水滑石的制备和表征

用盐-碱制备法合成了CuMgAl三元类水滑石化合物。探讨了原料配比、合成方式、水热处理温度和时间对合成过程的影响,筛选出合成HTLcs的适宜条件,并对HTLcs结构的热稳定性进行初步研究。结果表明,制备HTLcs主要取决于pH值,同时由于Cu2+的姜-太勒效应,合成结构单一的CuMgAl类水滑石要求原料配比中n(Cu)∶n(Mg)不得超过1.0,CuMgAl-HTLcs热稳定性较差,300℃焙烧2h结构破坏,600℃开始烧结,在300~500℃之间,随焙烧温度提高所得复合氧化物比表面积增大,最高可达200 m2/g。     

过氧化甲乙酮合成研究

论述了过氧化甲乙酮的合成方法，用阳离子交换树脂催化剂代替传统的无机酸催化剂。考察了离子交换树脂用量、反应温度对反应产率、活性氧含量的影响及溶剂对产品稳定性的影响。     

Relating catalyst structure and composition to the water–gas shift activity of Cu–Zn-based mixed-oxide catalysts

In order to investigate the effect of cerium oxide on Cu–Zn-based mixed-oxide catalysts four catalyst samples were characterized by means of XRD, in situ XANES and thermogravimetric analysis. The activity of the catalyst samples was tested for the forward water–gas shift reaction. Cerium oxide was found to increase the crystallinity of the ZnO phase indicating a segregation of the Cu and ZnO phases. The TOF of the water–gas shift reaction based on chemisorption data was found to be independent of composition and preparation conditions of the four catalyst samples. In contrast, the catalyst stability depends on composition and preparation conditions. Cerium oxide impregnated before calcination of the hydrotalcite-based Cu–Zn precursors leads to a more stable water–gas shift catalyst.     

黄磷罐车防腐探讨

本文针对黄磷的生产工艺及其运输等特点,分析了黄磷罐车腐蚀的机理,在此基础上对罐体及其防腐提出了具体要求,并提出了防腐工艺.