热电偶响应对激光脉冲法测量热扩散率的影响

用激光脉冲法测量热扩散率时，作为感温元件的热电偶总有一定的响应时间。试样达到最大温升的时间比较短时，热电偶响应时间所带来的测量误差就不能忽略不计。将热电偶处理为一阶测量环节，导出了考虑热电偶响应时间的试样背面温升表达式和修正关系曲线，并据此对实验结果进行修正。结果表明：经修正后的结果和文献［１］中提供的数据相吻合。     

外差干涉型光纤应变传感技术的研究

研究了一种采用高双折射纤模间干涉的应变传感器。传感器利用注入结电流直接调频的半导体激光（ＬＤ）产生外差干涉，从而实现了干涉相位的线性检测。实验结果显示干涉相位的分辨力为一个干涉条纹的２．５％，其相应的光纤应变是３６×１０－６ｍ。     

在横向气流中直射式喷嘴侧喷雾化细度的试验研究

应用激光散射测雾技术对均匀和不均匀横向气流中单个直射式喷嘴雾化细度作了试验研究。试验得出雾化细度 (索太尔平均直径) 随空气速度、供油压力、喷嘴孔径以及空气速度分布的变化规律。     

基于DSP+CPLD的射频源控制

采用数字信号处理器(DSP)和可编程逻辑器件(CPLD)技术，设计了射频信号源控制电路板。介绍了控制部分硬件和软件的组成，并给出了所设计软件的主程序。用线性调频和脉冲两种信号进行了仿真实验。结果表明，所设计的射频源的输出符合要求，控制灵活。     

高精度光栅干涉测量技术及仪器

在超精密测量和控制技术中，对测量精度提出了越来越高的要求，如尺寸精度１ｎｍ和角度０．００１。由于光栅具有精度高、抗干扰能力强、寿命长和价格便宜等优点，最近几年光栅干涉测量技术被广泛研究和使用。本文简单介绍几种在超精密测量和制造过程中常用的微纳米光栅干涉测量技术。     

飞机铆接电阻专用测量仪的研制

飞机铆接电阻专用测量仪是用于测量飞机铆接部件接触质量的专用仪器,它对保证飞机机载电子设备和通讯系统正常工作具有重要作用,在飞机维护中也常常要检测机体电阻是否符合要求.本文介绍了该测量仪的研制目的、工作原理和电路组成.     

激光干涉正弦法小角度测量中有关问题探讨

分析了小角度正弦激光干涉仪的有关特性，叙述了这种方法的测量原理，计算了几种因素对测量准确度的影响，指出提高测量准确度的解决办法。     

L׳ADROIT – A spaceborne ultraviolet laser system for space debris clearing

Small (1–10 cm) debris in low Earth orbit (LEO) are extremely dangerous, because they spread the breakup cascade. Pulsed laser active debris removal using laser ablation jets on target is the most cost-effective way to re-enter the small debris. No other solutions address the whole problem of large (~100 cm, 1 t) as well as small debris. Physical removal of small debris (by nets, tethers and so on) is uneconomical because of the energy cost of matching orbits. In this paper, we present a completely new proposal relative to our earlier work. This new approach uses rapid, head-on interaction in 10–40 s rather than 4 minutes, using 20–40 kW bursts of 100 ps, 355 nm UV pulses from a 1.5 m diameter aperture on a space-based station in LEO. The station employs “heat-capacity” laser mode with low duty cycle to create an adaptable, robust, dual-mode system which can lower or raise large derelict objects into less dangerous orbits, as well as clear out the small debris in a 400-km thick LEO band. Time-average laser optical power is less than 15 kW. The combination of short pulses and UV wavelength gives lower required fluence on target as well as higher momentum coupling coefficient. An orbiting system can have short range because of high interaction rate deriving from its velocity through the debris field. This leads to much smaller mirrors and lower average power than the ground-based systems we have considered previously. Our system also permits strong defense of specific assets. Analysis gives an estimated cost less than $1 k each to re-enter most small debris in a few months, and about 280 k$ each to raise or lower 1-ton objects by 40 km. We believe it can do this for 2000 such large objects in about four years. Laser ablation is one of the few interactions in nature that propel a distant object without any significant reaction on the source.     

Three dimensional investigation of the shock train structure in a convergent–divergent nozzle

Three-dimensional computational fluid dynamics analyses have been employed to study the compressible and turbulent flow of the shock train in a convergent–divergent nozzle. The primary goal is to determine the behavior, location, and number of shocks. In this context, full multi-grid initialization, Reynolds stress turbulence model (RSM), and the grid adaption techniques in the Fluent software are utilized under the 3D investigation. The results showed that RSM solution matches with the experimental data suitably. The effects of applying heat generation sources and changing inlet flow total temperature have been investigated. Our simulations showed that changes in the heat generation rate and total temperature of the intake flow influence on the starting point of shock, shock strength, minimum pressure, as well as the maximum flow Mach number.     

Spin parameters of Low Earth Orbiting satellites Larets and Stella determined from Satellite Laser Ranging data

Satellite Laser Ranging (SLR) measurements contain information about the spin parameters of the fully passive, geodetic satellites. In this paper we spectrally analyze the SLR data of 5 geodetic satellites placed on the Low Earth Orbits: GFZ-1, WESTPAC, Larets, Starlette, Stella, and successfully retrieve the frequency signal from Larets and Stella only. The obtained signals indicate an exponential increase of the spin period of Larets: T = 0.860499·exp(0.0197066·D) [s], and Stella: T = 13.5582·exp(0.00431232·D) [s], where D is in days since launch. The initial spin periods calculated from the first month of the SLR observations are: Larets: T_initial = 0.8239 s, Stella: T_initial = 13.2048 s. Analysis of the apparent effects indicates the counter-clockwise spin direction of the satellites. The twice more heavy Stella lost its rotational energy more than four times slower than Larets. Fitting the spin model to the observed spin trends allows determination of the spin axis orientation evolution for Larets and Stella before their rotational period becomes equal to the orbital period.