美国空军未来的装备与技术——2010"技术地平线"报告分析

介绍了美国空军2010年发布的"技术地平线"的出台背景、主要内容.并根据该研究报告浅析了美国空军未来的装备与技术趋向.     

热电制冷在激光器冷却系统中的应用

通过一种典型的冷却方案介绍热电制冷在激光器冷却系统中的应用,提出了以实验数据指导冷却方案设计,以热仿真手段进一步优化冷却方案,最终通过热测试技术验证冷却系统是否满足激光器的实际工作要求的三步走设计方法,该方法提高了热电制冷方案设计效率,为激光器冷却系统系列化、模块化打下基础。     

10 Years of LAGEOS-1 and 15 years of LAGEOS-2 spin period determination from SLR data

Satellite Laser Ranging (SLR) stations measure distance to the satellites equipped with Corner Cube Reflectors (CCRs). These range measurements contain information about spin parameters of the spacecraft. In this paper we present results of spin period determination of two passive satellites from SLR data only: 10 years of LAGEOS-1 (10426 values), and 15 years of LAGEOS-2 (15580 values). The measurements have been made by standard 10 Hz SLR systems and the first 2 kHz SLR system from Graz (Austria). The obtained data allowed calculation of the initial spin period of the satellites: 0.61 s for LAGEOS-1 and 0.906 s for LAGEOS-2. Long time series of the spin period values show that the satellite’s slowing down rate is not constant but is oscillating with a period of 846 days for LAGEOS-1 and 578 days for LAGEOS-2. The results presented here definitely prove that the SLR is a very efficient technique able to measure spin period of the geodetic satellites.     

Design and experiment of onboard laser time transfer in Chinese Beidou navigation satellites

High-precision time synchronization between satellites and ground stations plays the vital role in satellite navigation system. Laser time transfer (LTT) technology is widely recognized as the highest accuracy way to achieve time synchronization derived from satellite laser ranging (SLR) technology. Onboard LTT payload has been designed and developed by Shanghai Astronomical Observatory, and successfully applied to Chinese Beidou navigation satellites. By using the SLR system, with strictly controlling laser firing time and developing LTT data processing system on ground, the high precise onboard laser time transfer experiment has been first performed for satellite navigation system in the world. The clock difference and relative frequency difference between the ground hydrogen maser and space rubidium clocks have been obtained, with the precision of approximately 300 ps and relative frequency stability of 10E−14. This article describes the development of onboard LTT payload, introduces the principle, system composition, applications and LTT measuring results for Chinese satellite navigation system.     

精密钣金成形技术在航空制造领域的应用分析

介绍了钣金成形技术的发展和精密钣金成形技术的应用,并对精密钣金成形技术过程中的关键技术和发展方向进行了分析。     

有线/无线双网安防报警系统建设的研究

分析了传统的有线报警联网系统的使用缺陷，结合目前的无线通讯技术，提出了有线／无线和双无线两种改进方案。对有线／无线和双无线系统的组成结构、使用功能、适用范围、优缺点和经济性进行了论证，尤其对联网报警这一核心功能做了全面的分析，并给出了系统参考配置，对企业报警系统改造和工程设计施工具有普遍意义。     

633nm碘稳定激光器作为长度基(标)准的比对测量

简述作为长度基（标）准用的633nm碘稳定激光器的技术指标以及它的测量方法，文中以作者所进行的国际和国内比对中的测量结果为例，给出了这类激光器可以复现的频率或波长不确定度。     

基于多普勒效应的激光微位移测量系统

介绍了一种可进行动态微位移测量的激光微位移测量系统。该系统以多普勒效应为理论基础，以He-Ne激光器为光源，配置了判向变频系统、CCD视频信号的高速动态采集系统、微机处理系统及干涉图像处理软件包等，较传统测量方法其精度、误差、灵敏度及稳定度都有较大提高，并实现了微位移的全自动测量。     

高精度激光跟踪系统的综合设计

1.前言 激光跟踪系统是航空航天工程中的重要设备之一。要想建造高精度激光跟踪系统,除了提高有关部件的精度之外,系统的综合设计是一个关键步骤。对于这类系统的综合设计,目前都采用全连续或全离散控制方案,而且不考虑对象未建模动态和子系统间的耦合问题。     

1420铝锂合金薄板激光焊接头的撕裂韧性研究

对 1420铝锂合金及其激光焊接头的撕裂韧性进行了研究。试验按照美国材料试验学会ASTMB871—01《铝合金产品撕裂试验标准》进行。同时调查了铝合金及激光焊接接头的硬度分布及显微组织。撕裂试验表明,所有试样的启裂能均高于裂纹扩展能。不论启裂能还是裂纹扩展能,基材均高于焊缝及热影响区,基材L T方向高于T L方向。断口观察发现,基材的断口表面,特别是T L方向存在长而深的撕裂凹槽,焊缝及热影响区试样表面主要是沿晶或沿亚晶的脆性断口。由基材的高韧性到焊缝与热影响区的低韧性,是由于发生了断裂模式的转变,发生了由延性断裂向沿晶脆性断裂的转变。