自由立体显示器的光学性能测量与研究

为了评价自由立体显示器的光学性能,以八视点狭缝光栅自由立体显示器为例,针对不同的视点图像,测量了不同视角下的亮度值与色度值,研究自由立体显示器的光学性能,其光学性能包括自由立体显示器的最佳观看位置、串扰、可视范围、亮度均匀性、色度均匀性和莫尔条纹。结果表明,这种测量及分析方法实现了对多视点立体显示器光学性能的定量评估,增强了评估立体显示器性能的客观性,对自由立体显示器的设计具有指导意义。     

一种新型陀螺经纬仪平稳快速锁放方法

锁放环节是影响摆式陀螺寻北速度及陀螺灵敏部下放后限幅难度的关键环节。为解决现有摆式陀螺寻北仪锁放时间较长且陀螺灵敏部下放后摆幅较大的问题,以一种能够进行匀速运动的锁放装置为例,通过对原有控制电路进行I2C总线扩展,针对锁放过程中各阶段特点合理控制锁放电机转速,实现平稳快速锁放要求。经实验验证,新的锁放控制方法完全可行,锁放时间控制到25s内,下方后摆幅不超过1°30′,具有可行性和实用价值。     

Effects of pointing errors and channel fading on the performance of free‐space optically‐preamplified PPM systems

In this paper, we study the impact of pointing errors and channel fading on the performance of free‐space, optically preamplified, M ‐ary PPM systems. We consider two types of free‐space optical links: (i) inter‐satellite links and (ii) inter‐building links. For inter‐satellite links, only pointing error is considered. Starting with a Rayleigh model for the pointing error angle, we derive analytically the PDF for the pointing error parameter and for the signal‐to‐noise ratio (SNR) per bit. For inter‐building links, we derive the density function for the SNR per bit that includes the combined effects of pointing errors and channel fading, assuming Rayleigh‐distributed pointing errors. The channel fading models considered in this study for inter‐buildings links are the log‐normal and gamma–gamma models. We provide the error probability as a function of the average SNR per bit for both types of links. To cover systems with and without forward error correction, we compute the average SNR per bit required to achieve a bit error rate of 10^?4 and 10^?9. The corresponding power penalties are computed for different symbol sizes, scintillation indexes, and pointing jitters. Copyright © 2016 John Wiley & Sons, Ltd.     

电液伺服系统的同步控制研究

设计了一个同步控制电液伺服系统,系统中4个油缸同时支撑一个质量为900 t的箱形梁。为使运输与吊装过程中箱形梁严格保持水平,设计中综合采用了位置同步控制和力跟踪控制算法,实现了4个油缸同步运动且受力平均。最后,仿真结果验证了该控制方法的有效性。     

基于初始载波频移的孤子互作用抑制方法

介绍了一种基于孤子初始载波频移抑制孤子相互作用的方法.通过分析,发现孤子串最外层的两个孤子受相互作用影响最大,提出将孤子串中最外层的两个孤子进行初始的频率移动,较好地抑制了孤子相互作用.分析了频移量对传输距离的影响,结果表明对于具体的系统,存在最佳频移量.     

连铸板坯宏观偏析特性

应用金属原位分析仪,对铸坯的成分偏析状况进行了分析.铸坯试样为120 mm中等厚度连铸坯.分析结果发现:铸坯中心偏析成岛状出现在中心线附近,且彼此孤立,中心成分起伏波动大,最大偏析一般在中心位置;正偏析元素(k＜1)在整个中心等轴枝晶区域内含量均比较高(即偏析值较大);柱状晶组织向等轴状晶的过渡区为严重偏析的高发区域.     

数字滤波在圆柱体要素提取中的应用

圆柱体截面轮廓要素的测量与提取是圆柱体直径、形位误差和表面粗糙度评价的基础.在介绍2RC滤波、高斯滤波和样条滤波原理的基础上,给出了2RC和高斯滤波的算法的流程图和编制样条滤波程序的思路.对所测10个截面轮廓的要素分别用所编制的2RC、高斯和样条滤波程序依据不同的截止频率(15,50,100和150)进行处理,并对不同滤波方法和不同截止频率下提取要素的质量和速度进行分析,结果表明,在被测截面轮廓要素的滤波方面,样条滤波与2RC和高斯滤波相比,具有明显的优势,2RC滤波存在较明显的非线性相位偏移,运算速度慢且随截止频率变化,而高斯滤波则存在明显的边界效应,且比样条滤波的运行速度慢.     

高速公路行驶时电动汽车风冷散热性能研究

对高速公路行驶时,不同运行工况和电池组位置的电动汽车风冷散热性能进行了研究,研究表明:电池单体充放电发热功率随着环境温度升高而降低,随着充放电倍率的提高而升高;电动汽车动力舱自然进风散热性能随着车速的提高、环境温度的升高及充放电倍率的降低而提高;电动汽车动力舱自然进风散热性能随着电池组与动力舱后壁距离增加,先改善,再变差,满足最佳散热性能的距离为230 mm.上述结论为高速公路行驶时,电动汽车风冷散热分析和电池组位置选择提供了参考依据。     

位相板在大型几何量形位误差测量中的应用

介绍了利用位相板技术进行准直的工作原理和特点,以及如何利用该项技术有效地确定激光准直光束的几何基准,并介始了以此技术为基础的光学基准在大型几何量形位误差测量中的应用。     

An automatic self-installation and calibration method for a 3D position sensing system using ultrasonics

This work addresses 3D position sensing systems that estimate the location of a wave source by triangulating its position based on the time-of-flights (TOFs) to various receivers fixed to an inertial frame of reference. Typical applications of such systems are finding the location of the transmitter that may be fixed to an autonomously guided vehicle (AGV) operating in an enclosed work environment, a robot end-effector, or virtual reality environments. These environments constitute a large working volume, and the receivers have to be fixed in this environment and their locations known exactly. This is a major source of problems in the installation/calibration stage since the receivers are usually distributed in space and finding their exact location entails using a separate 3D calibrating device which may or may not be as accurate as the location system itself. This paper presents a method to use the system itself to set up an inertial frame of reference and find out the locations of the receivers within this frame by simply using an accurate ID positioning system, e.g. an accurate ruler or a simple distance measuring system that uses ultrasonic or infrared sensors. The method entails moving the transmitter to known locations on a single plane, and using the TOFs to estimate the location of the receivers. A typical application would be that an AGV carries a set of receivers to a hazardous environment such as a nuclear power plant, places the receivers arbitrarily, carries out the self-installation/calibration procedure, maps out the environment, and begins to function autonomously, the whole procedure being done without human intervention or supervision.