用于激光吸收光谱二维重建的光谱优化选择方法研究

光谱组合对多光谱重建技术的重建结果有很大影响,不合理的光谱组合会降低光谱测量的有效性,加大重建误差。为了从海量的光谱数据库中选出适用于被测流场参数范围的最优光谱组合,提出了一种基于向量组线性相关性的光谱选择方法,采用数值仿真的方法开展研究,仿真结果验证了方法的可行性与可靠性。分析了测量信号无噪声和存在噪声时,光谱数量与重建结果的关系。研究发现最优光谱组合的线性相关指数小于0.01时,该组合存在光谱的冗余。保证测量有效性的同时光谱数量最少的光谱组合为线性相关指数不小于0.01的最优光谱组合。测量存在噪声时,光谱数量越多,噪声的抑制效果越好,重建结果精度更高。通过重复测量法可以有效降低噪声影响,用最少数量的光谱实现更多光谱的测量效果。     

激光切割喷嘴及流场分析综述

介绍了国外为提高激光切割效率和切削质量所采用的各种类型喷嘴,并利用空气动力学原理,对各种喷嘴产生的流场进行研究和分析,以便为提高激光切割效率和质量提出相应措施。     

LY12,TC4,30CrMnSiA激光冲击处理疲劳断口分析

从疲劳断口形貌特征分析了激光冲击处理对铝合金ＬＹ１２、钛合金ＴＣ４、高强钢３０ＣｒＭｎＳｉＡ疲劳行为的影响。     

激光冲击强化研究现状与展望

激光冲击强化是一种新型的表面改性技术,相比于传统的喷丸强化技术有诸多突出优势.对激光冲击强化技术原理进行分析,总结激光冲击强化技术的各个工艺参数,并对激光冲击强化后材料表层性能变化进行阐述.讨论激光冲击强化技术的发展与现状,并对该技术在未来的运用进行展望.     

激光增材制造技术的研究现状及发展趋势

增材制造技术能够快速将复杂结构的三维数据模型直接转化为实体零部件,是一种快速发展的数字化制造技术.激光增材制造技术是增材制造技术中最具代表性的一类,在增材制造技术领域扮演着重要的角色.主要介绍了两种典型的激光增材制造技术:激光选区熔化(Selective Laser Melting,SLM)技术和激光金属直接成形(Laser Metal Direct Forming,LMDF)技术的原理与特点,归纳了其发展和研究现状,指出了激光增材制造技术的发展趋势.     

A novel intelligent adaptive control of laser-based ground thermal test

Laser heating technology is a type of potential and attractive space heat flux simulation technology, which is characterized by high heating rate, controlled spatial intensity distribution and rapid response. However, the controlled plant is nonlinear, time-varying and uncertainty when implementing the laser-based heat flux simulation. In this paper, a novel intelligent adaptive controller based on proportion–integration–differentiation(PID) type fuzzy logic is proposed to improve the performance of laser-based ground thermal test. The temperature range of thermal cycles is more than 200 K in many instances. In order to improve the adaptability of controller,output scaling factors are real time adjusted while the thermal test is underway. The initial values of scaling factors are optimized using a stochastic hybrid particle swarm optimization(H-PSO)algorithm. A validating system has been established in the laboratory. The performance of the proposed controller is evaluated through extensive experiments under different operating conditions(reference and load disturbance). The results show that the proposed adaptive controller performs remarkably better compared to the conventional PID(PID) controller and the conventional PID type fuzzy(F-PID) controller considering performance indicators of overshoot, settling time and steady state error for laser-based ground thermal test. It is a reliable tool for effective temperature control of laser-based ground thermal test.     

陶瓷热障涂层的研究进展

综述了陶瓷热障涂层的材料体系研究进展，分析了陶瓷热障涂层的制备工艺、组织特点及其对涂层性能的影响，并指出了热障涂层今后的发展方向。     

激光干涉法在扭摆法测量微冲量中的应用

介绍了激光干涉法测微小转角的原理及测量方法,提出了采用激光干涉测量微冲量的方法,将激光与靶作用产生的微冲量转化为扭摆的转动角度,通过激光干涉法测量此微小转角从而计算出冲量。相同单脉冲能量下,以PVC+2%C为工质,用扭摆法测量了激光与工质作用产生的微冲量,结果表明该测试系统分辨率为2×10-8N.s,量程为2×10-7～0.8×10-5N.s。     

激光合成金属间化合物基复合材料研究进展

对激光合成颗粒增强金属间化合物基复合材料进行了研究,包括Ni3Al/WC、NiAl/TiC、Ti3Al/TiC和MoSi2/SiC,用扫描电镜、能谱仪和X射线衍射仪对材料成分和组织特征进行了分析,提出并讨论了影响激光合成金属间化合物基复合材料的关键问题.激光合成具有多种强韧化方法协同、提高金属间化合物强度和塑性的特点,有利于金属间化合物性能的综合改善.     

Design and performances of laser retro-reflector arrays for Beidou navigation satellites and SLR observations

Beidou is the regional satellite navigation system in China, consisting of three kinds of orbiting satellites, MEO, GEO and IGSO, with the orbital altitudes of 21500–36000 km. For improving the accuracy of satellites orbit determination, calibrating microwave measuring techniques and providing better navigation service, all Beidou satellites are equipped with laser retro-reflector arrays (LRAs) to implement high precision laser ranging. The paper presents the design of LRAs for Beidou navigation satellites and the method of inclined installation of LRAs for GEO satellites to increase the effective reflective areas for the regional ground stations. By using the SLR system, the observations for Beidou satellites demonstrated a precision of centimeters. The performances of these LRAs on Beidou satellites are very excellent.