Molecular correlations in sheared thermotropic copolyesters showing banded textures

Banded textures produced in a thermotropic liquid crystal polymer by shearing between glass slides are examined by using both transmission electron and polarized light microscopy. The periodic variation in director orientation about the shear axis, as measured by light microscopy, is shown to be distinctly different from that indicated by electron diffraction. Measurements of birefringence and observation of Zernicke phase contrast indicate periodic variations in optical properties of the polymer, in step with the bands. Such effects are accounted for in terms of a synchronous rotation of the planar aromatic groups about the molecular chain axes. Evidence for an out-of-plane component of molecular orientation is also presented.     

开关磁阻电机调速系统在煤矿井下的应用

随着开关磁阻电机的调速控制系统日臻完善，因其优越性能使得在各行业得到迅速推广，但在煤矿井下的特定环境中使用该调速系统仍存在着诸多问题有待分析研究。     

基于数字信号处理器的直流电机控制系统

介绍了定点数字信号处理器（DSP）TMS320F240的一般性能及其在永磁无刷直流电机控制上的应用，给出了硬件设计方案、软件策略及输出结果。     

轴向磁场无铁心无刷永磁盘式电机的设计

介绍了轮用轴向磁场无铁心无刷永磁盘式电机的结构形式，探讨了这种新电机的设计特点，重点解决了电机主要尺寸确定和磁路分析计算问题，最后给出了一种磁极形状和线圈形状的优选方案。     

直线式电机在有杆抽油设备中的应用

通过对游梁式抽油机的效率、启动特性与直线式电机驱动的有杆抽油机特性的对比，论述了直线抽油机的优越性及应用前景。     

测距仪中新型的脉冲激光光源

针对现有测距仪中脉冲激光器存在寄生多脉冲的问题，提出并实现新型的采用同步泵浦声光调Q方法的测距仪用激光器、消除了寄生脉冲并提高了激光器的峰值功率。     

Trace elements in particles of motor vehicle exhaust in Shanghai

A nuclear microprobe with high spatial resolution and high analytical sensitivity was applied to analyze trace elements,especially lead,in vehicle exhaust of Shanghai city.The result shows that the chemical composition and its corresponding x-ray relative intensity are different among different vehicle exhausts.There are many kinds of metal elements in particles of vehicle exhaust.most are harmful to people,such as Ti,Cr,Mn,Pb,etc.We found that the lead concentration was 6820μg/g and the bromine concentration was 5300μg/g in the exhaust from Santana using leaded gasoline(SULG).which is higher than any other kinds of vehicle exhausts.We have also detected the minimum lead in the particles of unleaded gasoline and its content varies from one to another.Its mean concentration was 450μg/g and the highest reached 6210μg/g.The unleaded gasoline‘s Pb existed in the whole particle while the leaded gasoline‘s enriched in the surface of the particle and was more harmful to the human beings.     

复合材料超声波直线电机的运动控制

针对复合材料超声直线电机振动体具有两个固有频率的特点，设计了具有频率跟踪特性的超声直线电机驱动器，利用激励信号频率变化改变电机运动方向，实现了超声直线电机的运动控制。     

机械结构动态改进技术在电动机振动噪声防治中的应用

本文介绍了结构实验模态分析、灵敏度分析和局部结构改进分析等先进的结构动态改进技术的基本原理,并由此对Y112M-4型电动机的机座进行了计算和分析,确定出一个结构改进方案.经实际改进试验验证,这一改进可有效地抑制电动机电磁振动和电磁噪声的传递,具有明显的减振降噪作用.     

浅析异步电机电子软起动器的现状和展望

本文在分析异步电机电子软起动器的现状和展望的基础上，以一个当前正在设计完善的电子软起动器为例，基本说明新型电子软起动器的特点和结构功能。