Hot-pressing of magnesium aluminate spinel—II. Microstructure development

The microstructure of hot-pressed MgAl₂O₄ spinel has been analysed by TEM. The dislocation substructure evidently supports that densification occurs by the dislocation mechanism as suggested from kinetic results. Dislocations are generated predominantly at the beginning of hot-pressing due to high effective stresses concentrated in the neck region. When powder compact is being densified, strain-hardening and recovery iteratively occur resulting in both the hardened and recovery microstructure. Subgrain boundary and dislocation network are characteristic of hot-pressed samples of the three compositions studied. The dislocation network grows its link-length as hot-pressing proceeds. The increase of the link-length in the dislocation network suggests a network growth model similar to the steady-state creep of aluminium and MgO. The corresponding stages of its development in the hot-pressing kinetic curve are designated on the basis of microstructure observations. A schematic illustration of microstructure development upon hot-pressing is proposed and its correlation to the densification kinetics attempted.     

模糊综合评价法在粉尘燃爆风险中的运用

针对目前粉尘爆炸发生增大的危险性,介绍了模糊综合评判法及其在风险分析中的应用,给出了模糊综合评判法在风险决策分析中的具体应用步骤。应用了模糊综合评判,建立了粉尘燃爆的风险决策数学模型。并结合实例,建立了具体的粉尘燃爆的风险决策分析模型,以期指导安全生产。     

顶空气相色谱法测定丙烯腈-苯乙烯(AS)塑料中残留的7种单体

建立了顶空气相色谱法测定丙烯腈-苯乙烯(AS)塑料中7种残留单体的分析方法。以N,N-二甲基甲酰胺为溶剂溶解AS塑料,于顶空装置中平衡后,进样进行气相分析。通过实验得到了优化的气相色谱分离条件及顶空条件,其中优化的顶空条件为溶剂使用量3mL,加热温度120℃,平衡时间40min。7种残留单体的平均回收率为95.71%～106.89%,检出限为0.25～1.0mg/kg。该方法既提高了检测效率,又降低了检测成本。同时,此方法还具有简便、快速、灵敏、准确等优点。     

Crystal structure and luminescent properties of new rare earth complexes with a flexible Salen-type ligand

A novel Salen-type ligand and its four complexes, [LnL(NO₃)₃] [Ln = La (1), Nd (2), Eu (3), Tb (4)], were synthesized. The X-ray single-crystal diffraction analysis indicates that the ML type complexes [LaL(NO₃)₃] and [NdL(NO₃)₃] are isomorphous. With a proton migration (or transfer) from the phenol function to the imine function, coordination of Ln to the ligand gives the ligand a zwitterionic phenoxo-iminium form. The luminescent property of the Tb(III) complex is described and some factors that influence the luminescent intensity were also discussed.     

贝塔斯瑞db系列远程有源定向强声扩声系统

对贝塔斯瑞db系列远程有源定向强声扩声系统进行了介绍,并对其系统进行了详细的测试,测试的目的一是验证是否满足立项需求;二是验证是否满足国标和欧盟安全标准;三是得出实际使用中的数据结果.测试结果表明,db系列产品的实测数据和功能符合立项与设计标准.     

锂离子电池快速充电及高倍率放电性能

就正极中导电剂含量和功能电解液对电池的快速充电及高倍率放电性能的影响进行了研究,同时重点考察了导电剂和功能电解液对电池的高倍率放电性能和快速充电高倍率放电循环性能的协同效应。结果表明,增加正极中导电剂含量和使用功能电解液,可以提高电池的快速充电及高倍率放电性能;正极中导电剂含量和功能电解液对电池高倍率放电性能和快速充电高倍率放电循环性能具有良好的协同效应。通过优化组合,得到的电池20 C放电容量可达1 C放电容量的95.1%;4.5 C充电9 C放电循环300周后,电池容量仍然保持在89%以上,具有优异的快速充电高倍率放电循环性能。     

基于ADS的新型硬盘磁头折片组合设计及仿真

提出了一种具有低特性阻抗,低功耗,高带宽的新型硬盘磁头折片组合Flexure的设计,结合流行电磁仿真软件ADS,重点对其电磁性能进行了设计,仿真及验证。该设计为新一代硬盘的设计与生产打下基础。     

新型硬盘磁头折片组合Flexure设计

针对大容量、高速硬盘的需要,提出了一种低特性阻抗,低功耗,高带宽的新型硬盘磁头折片组合Flexure的设计,重点说明了该Flexure的结构、工作原理及其主要技术特性。并结合流行电磁仿真软件ADS对其电磁性能进行了设计,仿真及验证。     

Capacitance performance enhancement of TiO<Subscript>2</Subscript> doped with Ni and graphite

Nano-amorphous TiO₂ was prepared by a sol-gel method. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that the composite electrode material (TiO₂-NiO-C) is made of powder with a grain size of 36.2 nm. Doping of nickel and graphite can increase the electrical conductivity and the specific surface area of nano-amorphous TiO₂. The electrochemical properties of TiO₂-NiO-C, such as self-discharge, leakage current, and cycle life, were studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge-discharge test. With a charge-discharge current density of 500 mA/g, the specific capacity of the TiO₂-NiO-C composite material reaches 12.88 mAh/g. Also, the expense of capacity is only 3.88% after 500 cycles. The electrochemical capacitor with the electrode material of TiO₂-NiO-C shows excellent capacity and cycling performance.     

框支剪力墙中框支梁对多遇地震反应的影响

分析多遇地震作用下框支梁截面高度对其自身地震反应的影响规律,表明降低框支梁截面高度能减小框支梁的多遇地震内力,且框支楼层侧移随框支梁截面高度的减小而增加不大,由此提出适当减小框支梁截面高度对抵抗多遇地震有利。