无侧向支撑钢结构变电构架的二阶效应分析

针对无侧向支撑的两跨人字形钢结构变电构架,进行了考虑结构二阶效应的受力性能分析。分析中考虑了构架柱的初始几何缺陷,加载过程分别考虑了几何非线性、材料非线性以及两种非线性因素共同存在对变电构架受力性能的影响。通过分析对比斜向、水平及竖向荷载作用下的二阶弹性、一阶弹塑性和二阶弹塑性3条荷载—位移曲线,得到了这种变电构架的二阶效应特点及影响因素:在斜向和水平荷载作用下,虽然受材料非线性的影响更大,但受到二阶效应的影响较早;在竖向荷载作用下,则受二阶效应的影响更大,而塑性效应的影响不很明显。     

在LiCl-KCl-CeCl3熔盐中铝电极上欠电位沉积制备Al-Ce合金

在843K LiCl-KCl-CeCl3熔盐中活性铝电极上,研究了Ce(III)离子的电化学行为和欠电位沉积Al-Ce合金。对比循环伏安曲线发现,在Al电极上Ce(III)/Ce反应的氧化还原电势比在Mo惰性电极上更正;开路计时电位在金属铝和铈的沉积平台之间出现两个平台,这表明Ce(III)在Al活性电极上可以生成两种金属间化合物。以上结果在电化学机理上说明Ce(III)离子可以在Al电极上欠电位沉积形成金属间化合物。在该实验条件下通过恒电位电解,在Al电极上得到了Al-Ce合金,验证了理论分析的结果。经XRD表征,证实了形成AlCe和AlCe3两种合金;经SEM和EDS表征,证明了铈分布在Al电极表面厚度均一的合金镀层中（厚度28?m）。 关键词：LiCl-KCl熔盐;欠电位沉积;铝电极;Al-Ce合金     

Noncovalent functionalization of multi-walled carbon nanotubes with amphiphilic polymers containing pyrene pendants

A novel noncovalent approach was developed for the functionalization of multiwalled carbon nanotubes (MWNTs) using an amphiphilic copolymer of PVP-co-PAH containing pyrene pendants. A homogeneous polymer layer was formed on the surface of MWNTs, and the wrapped copolymer layer with a thickness of about 17.7 nm was found. The noncovalent modified MWNTs were dispersed very well in solvent of dimethylformamide (DMF), water and chloroform (CHCl₃), and the high stability of dispersed suspensions could be maintained for more than 2 months without observed MWNT precipitation. In addition, the dispersing behavior of the noncovalent functionalized MWNTs by PVP-co-PAH in a solvent mixture of water/CHCl₃ was also investigated, and it was found that a carbon nanotube layer was formed at the water/CHCl₃ interface.     

PROFIBUS现场总线技术与PC控制

由于PROFIBUS现场总线优良的特性，灵活的配置和安装成本低等特点，以及目前世界范围内应用成功的经验证明和发展势头，较其它几种总线具有明显的优势，本文扼要地叙述了其技术特点、结合PC控制应用及在中国的发展前景。