点焊质量控制方法的研究

利用光栅位移传感器和压电石英力传感器 ,建立了热膨胀位移和动态电极压力点焊质量微机监控系统 ,并对这两种监控方法的控制原理、控制性能和控制效果进行了分析比较。试验结果表明 ,此类单参数质量控制系统能够实现点焊过程质量监控 ,并具有自适应特性 ,可用于构造多参数点焊质量控制系统     

动态因素对星敏感器测星影响的分析

在捷联惯导系统中,星敏感器直接固定在弹体上,在动态环境下工作.本文根据光学成像原理、快门速度和图像传感器上星点移动速度等,建立了动态条件下星敏感器所获星点光斑的数学模型.通过计算机仿真得出了曝光时间与动态星点像元能量最大值的关系、不同曝光时间下的动态星点定位精度.仿真结果表明,动态星点像元能量最大值不能随着曝光时间的延长始终增大,动态星点形变对星点定位精度的影响可以忽略.     

Analysis of the brightness temperature features of the lunar surface using 37 GHz channel data from the Chang'E-2 microwave radiometer

Compared with other remote observations, brightness temperatures (T_B) derived from microwave emission measurements provide a unique means to characterize the physical properties of the lunar surface. Using Chang’E-2 microwave radiometer data, we produced 12 global T_B images of the lunar surface during a diurnal cycle with different local times separated by approximately 2?h. There are two types of remarkable T_B units on the lunar surface, the “hot regions” occurring during the lunar day in the lunar Maria regions and the “microwave cold spots” occurring during the nighttime typically related to young craters. Compared with their surroundings, the hot regions are much warmer during the lunar day and slightly colder at night, while the microwave cold spots are much colder during the lunar night and slightly warmer in the daytime. Moreover, the T_B heating and cooling rates of these two units are larger than others at the same average latitude where they are located during the lunar day, especially after sunrise and before sunset. The hot regions have a good agreement with the mare regions with high TiO₂ abundance. Besides, brightness temperatures in the lunar Maria correlate closely with their TiO₂ abundance. For most microwave cold spots, they agree with the young craters, and their brightness temperature distributions have a significant negative correlation with the lunar surface nighttime temperature and rock abundance.     

异形光斑的高精度光束偏转角度测量

大气湍流通常会造成激光光斑畸变为不规则的异形光斑,针对目前四象限探测器(QD)对空间光通信中不规则光斑偏转角度测量精度不足的问题,提出了一种基于多源信息融合的高精度光束偏转角度测量方法.该方法通过对QD及电荷耦合元件(CCD)的数据信息进行融合分析,在保持QD高分辨率和高响应速度的基础上,提高QD对不规则光斑偏转角的测...     

Investigation of Surface Integrity on TC17 Titanium Alloy Treated by Square-spot Laser Shock Peening

Laser shock peening(LSP) is an innovative surface treatment method,which has been shown to greatly improve the fatigue life of many metallic components.This work investigates surface integrity of TC17 titanium alloy treated by LSP with innovative square laser spot.Nd:glass laser with duration of 30 ns and spot size of 4 mm×4 mm is applied.The surface morphology and surface residual stress of the TC17 titanium alloy,treated with varying peening parameters such as laser power density and overlapping ratio,have been studied in detail.The results show that laser pulse energy greatly influences surface morphology and surface residual stress around single-spot treated areas,and compressive residual stresses are saturated as laser pulse energy is over 55 J.There are significantly different surface morphologies and residual stress distributions at the overlapped areas with different overlapping ratios.A relative smooth surface is produced with uniform compressive residual stress distribution at an overlapping ratio of 8 %.The experiment of residual stress relaxation is implemented by measuring residual stress at the center of four overlapped spots and by four point bending fatigue test at the frequency of 105 Hz.The compressive residual stresses induced by LSP are found to relax quite slowly under cyclic fatigue loading.     

黄金周热点景区拥堵现象分析与对策研究

2012年中秋国庆黄金周期间,国内大部分热点景区接待的游客数量不仅大大超过了景区最佳承载量,也严重超过了景区的最大承载量,出现了游客严重拥堵的现象,在一定程度上影响了游客的旅游质量,破坏了景区的自然环境和人文环境,并带来一系列安全隐患。文章旨在探究此现象形成的机理及后果,并对解决这一问题提出相应对策。     

压力传感器静态校准方法改进

对目前发动机试验采用的压力传感器校准方法存在的问题进行了分析,针对这些问题,提出了一种压力传感器自动静态现场校准方法,该方法能减少对于压力标准源精度的依赖以及检定循环次数并提高校准工作效率。     

一种变结构自适应中制导律设计

应用广义预测拦截点的概念,基于变结构自适应理论,以相对速度偏角为滑模面,设计了一种新颖实用的变结构自适应中制导律并进行了仿真分析,结果显示导弹各项指标均很好地满足要求,验证了该中制导律的可行性与有效性。     

高校图书馆采访方式的整合及采访质量监控

高校图书馆的采访工作是保证馆藏图书质量的重要关口,通过对高校图书馆常用采访方式的分析,提出了现采与预定,网上采访,建立学科馆员采访制度的整合和互融,只有一切从实际出发,满足师生需求,同时,建立起质量评价监控体系,才是提高馆藏图书质量的有效方法。     

Resistance Spot Welding Method for Metal-Based Fiber Bragg Grating Sensors

Aiming at the requirements of installation and work environment of metal-based fiber Bragg grating(FBG)sensor,a resistance spot welding method is presented.Firstly,the effect of welding parameters on welding quality is discussed theoretically,and a suitable resistance spot welding method for the metal-based FBG sensor is proposed for the first time.Then through serial resistance spot welding tests,the feasibility and practicability of the method are verified,and optimal welding parameters for two different tested metals are obtained.Fatigue performance test validates FBG sensors installed by the proposed method with good fatigue properties and long-term stable measurement performance.The research results can provide technical guidance for engineering structure long-term safety monitoring.