基于FPGA的李沙育图形在手持式示波表中的实现

本文介绍了一种利用FPGA在手持式数字示波表中实现李沙育图形的新方法.该设计方案不仅具备高精度显示能力,同时拥有可变的余辉,对被测信号的观察与测量具有极大的帮助.     

Effect of insulating oil covering electrodes on the characteristics of a dielectric barrier discharge

In this study, the effects of the fluid cooling and electric field line deformation were investigated in a dielectric barrier discharge (DBD) plasma source. The DBD plasma jet is improved by covering the ground electrode and a power electrode with insulating oil. We obtained positive results as insulating oil prevents arc formation, while it improved the supplied power and plasma jet length, and increased radical production. Radical production of this nonthermal plasma jet is studied with polyvinyl alcohol–potassium iodide liquid.     

基于光栅的贴片机对准系统的精度标定

贴片机对准系统的精度标定是视觉定位的关键环节,直接影响贴片精度与贴片质量。传统的标定方法往往需要进行大量的矩阵计算和分析,来确定相机的坐标系与世界坐标系和图像坐标系之间的关系,因此要掌握大量的三维几何知识与投影理论,并且计算繁杂。本文提出的基于光栅的精度标定方法,将光栅图像灰度值之和形成一组周期固定的准正弦信号,通过像元平移把图像条纹灰度值变为李萨如图。通过对李萨如图及其数据进行分析与处理,直接计算出光学系统的分辨率,实现光学系统的精度标定。实验结果表明这种标定方法的精度高,偏差小于0.2微米,精度达到亚微米级,满足贴片机的对准精度要求。     

一种应用标准刻线与CCD直接获取运动位移的方法

将标准刻线应用到对微细物体进行高精度定位的交流伺服驱动控制系统中,提出了一种新的直接获取运动位移的方法。调整光路使CCD获取清晰的光栅图像,对图像进行分析处理,计算出栅距与像素之间的映射关系,再对工作台移动前后的光栅图像进行对比,采用基于李萨如图的相位差比率算法获取它们的像素位置差,从而计算出工作台的实际运行位移。试验结果表明,该方法能简单快速地实现微电子加工领域亚像素级的测量。     

光栅在驱动控制系统运动位移测量中的应用

利用计量光栅的栅距作为基准刻线,对二维精密工作台的运动位移进行测量,提出了一种新的位移测量方法。通过CCD(charge coupled device)获取光栅刻线图像,对图像进行分析处理,计算出栅距与图像像素之间的映射系数,再通过对工作台移动前后光栅图像的对比,采用基于李萨如图的相位差比率算法获取它们的像素位置差,从而计算出工作台的实际运行位移量。     

基于等效鉴相频率的频率稳定度的检测方法

在对两个周期性信号之间相位差变化规律和相应的新概念深入研究的基础上，结合常用的频率稳定度的测量方法，提出了一种新的频率稳定度的判定方法——基于李沙育图形的频率稳定度的快速检验方法。该方法可以用于各种原子频标和频率源的频率稳定度的测量与判定。     

Large amplitude oscillatory shear rheology for nonlinear viscoelasticity in hectorite suspensions containing poly(ethylene glycol)

The effect of poly(ethylene glycol) (PEG) on the nonlinear viscoelasticity of Laponite suspensions containing NaCl was investigated with large amplitude oscillatory shear rheology. The molecular weight (M_w) of PEG was 4k, 10k and 35k, and the concentration of PEG was varied from 0.063 wt% to 2.4 wt%. The dynamic strain sweep showed that the nonlinearity appeared at γ₀ > 30% with a stress overshoot at γ₀ = 50-70%. The intensity ratio I_3/1 from Fourier-transform increased with γ₀ when entering the nonlinear regime and leveled off at γ₀ ≥ 100% with higher slope and constant value for the PEG of higher M_w or lower concentration. I_3/1 revealed the structure difference in the suspensions induced by adsorbing PEG in the nonlinear regime. The minimum- and large-strain rate viscosities η_M and η_L from the Lissajous curve were found to be sensitive to the nonlinear viscoelasticity and the peak of η_M and η_L appeared at lower γ₀ with higher maximum following the same dependency as I_3/1 on PEG M_w and concentration. The overall nonlinearity parameters N_E and N_V were proposed in this paper and demonstrated to reflect the difference in the Laponite suspensions with PEG more clearly and more effectively.     

MEMS摆镜在小型化激光成像雷达中的应用

研究了MEMS摆镜在未来小型化激光成像雷达的系统中的应用。首先介绍了MEMS摆镜自身的器件特性,结合脉冲成像激光雷达的应用背景,分析了系统设计时要注意的问题。进一步设计了MEMS摆镜的驱动模块,通过仿真和成像验证了李萨如扫描图形的应用。     

对电子示波器的使用实验的改进

应用频率锁定原理，对示波器的使用实验进行改进，获得稳定的利萨如图形，从而更好地实现利用利萨如图形测频率和相位差．