核翼比法进行表面粗糙度的标定及测量

介绍了一种表面粗糙度标定及测量的新方法。通过标定一组标准样块的核翼比，可以实现该标定范围内待检样块的粗糙度测量，该方法稳定可靠，试验装置简单，数据处理方便，为表面粗糙度的非接触测量提供了较好的方案。     

球形表面粗糙度测量中两种干涉图像处理方法

讨论了用带有数字图像处理和计算系统的麦克尔逊干涉涉显微镜测量像人工关节这样的球形表面粗糙度的方法，用数字图像处理方法处理等倾干涉和等厚干扰这两种干扰图像，并萃取出反映被测球面微观不平度信息的干涉带的边界线。本文推导了用最小二乘拟合原理计算标准最小二乘圆和圆弧的算法以及用获取的被测表面的微面不平度偏差计算表面粗糙度参数的方法。     

碳/碳复合材料与硬铝切削表面三维测量对比研究

针对各向异性复合材料切削表面粗糙度的测量与评定是国内外急待解决的问题，采用Talyscan150表面粗糙度测试仪对C／C复合材料和硬铝（LY12）切削表面粗糙度进行三维非接触测量。通过三维评定参数的对比，研究了C／C与LY12的切削表面粗糙度。结果表明：采用二维评定参数评定C／C的切削表面粗糙度将丢失表面的许多信息，三维评定参数可以更全面、更真实地表达复合材料切削表面粗糙度的特征。C／C切削表面和LY12切削表面在峰态分布以及表面纹理方面具有较大的差别。与LY12切削表面相比较，C／C切削表面有更多的深谷，而且表面没有明显的切削进给波纹。5q参数比5a参数能更好地表达复合材料切削时的纤维拔出与纤维露头的特征。     

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。     

事件时间测量系统及其在绝对重力仪中的应用

绝对重力仪通常采用真空腔中自由落体的方法,通过测量激光干涉条纹信号的过零时间来计算绝对重力加速度(g)。针对绝对重力仪的使用,依托电子计数法的基本原理,基于数字信号处理器(Digital Signal Processor,DSP)设计实现了事件时间测量系统,精确测量干涉条纹过零时间。首先介绍了事件时间测量的基本原理,然后具体介绍在以DSP为核心的硬件上的实现方法。根据理论计算和MATLAB~?数值仿真实验,评价系统测时误差以及对重力加速度测值的影响。最后分别通过硬件模拟实验和FG5X型高精度绝对重力仪上的对比实验进行验证。实验证明,该系统对重力加速度测量真值影响小于1μGal(1μGal=1×10~(-8) m/s~2),标准差影响小于5μGal。该系统体积小、成本低,尤其对于小型化、野外使用的绝对重力仪,完全符合其使用需求。     

显微PIV系统与实现

显微PIV系统可用于流体微观层次以及微流体流动的测量，可获得流体速度的场信息以及其中颗粒的场信息。本文主要介绍显微PIV系统所涉及的显微图像获取技术以及图像处理算法。该系统由硬件与相应软件系统组成。其中，硬件主要包括放大倍数为1000倍的光学显微镜以及最大拍摄速度为10000帧／秒的高速摄像系统；IMPACT软件为自行开发的基于C 系统的面向对象程序，其中内嵌多种数据处理与分析算法。通过对尺寸为1μm颗粒运动的测量，对不同数据处理算法进行了检验，结果表明：建立的显微PIV系统可有效获得微观流体流动的图像并可准确进行数据的处理，该系统完全可用于微观流体流动的测量。     

纳秒激光构造锡青铜粗糙表面的工艺研究

为了在考虑表面粗糙度条件下,对表面织构影响润滑性能的理论计算结果进行试验验证,提出了一种通过纳秒紫外激光在锡青铜样片表面构造不同粗糙度参数的方法.通过改变激光加工参数制备了不同表面粗糙形貌,并采用白光干涉共聚焦显微镜以及粗糙度仪对表面粗糙形貌进行表征.试验结果表明,表面粗糙度随激光扫描速度的增大而减小;扫描间距等于光斑直径50μm、扫描速度300mm/s时,表面粗糙纹理方向清晰,便于粗糙度方向参数的控制.通过控制粗糙度方向参数以及微织构方向控制,实现了与表面粗糙方向成规定角度的微织构阵列的制备.     

Wollaston棱镜方位对激光干涉测量精度的影响

在双频激光干涉测量系统中,Ｗｏｌｌａｓｔｏｎ棱镜是不可缺少的重要光学元件,它可将双频激光按偏振方向分为测量光和参考光,从而实现高精度测量;但是,如果Ｗｏｌｌａｓｔｏｎ棱镜的安装方位相对入射光线方向以及与聚集透镜距离不同时,测量结果将会不同。本文结合表面粗糙度激光测量系统,从理论上定量分析了Ｗｏｌｌａｓｔｏｎ棱镜的安装方位对测量精度的影响。     

零部件外形非接触测量方法探讨

探讨了一种新的适合于零部件外形非接触测量的方法，包括相应测量系统组成，测量原理，测量点数据信息的采集、传输和处理。     

调频激光干涉绝对距离测量技术及其信号处理

最最的绝对距离测量方法是非相干飞行时间测量法。随后，在小数重合法的基础上，产生了多波长干波绝对距离测量技术。随着半导体激光器的发展，８０年代又出现了调频干涉绝对距离测量方法，并很快成为一种新的测长技术。本文在综述绝对距离技术及方法的基础上，着重介绍了调频激光干涉绝对距离测量技术的一些新发展及其几种不同的信号处理。     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis

Aerospace relay is one kind of electronic components which is used widely in national defense system and aerospace system. The existence of remainder particles induces the reliability declining, which has become a severe problem in the development of aerospace relay. Traditional particle impact noise detection (PIND) method for remainder detection is ineffective for small particles, due to its low precision and involvement of subjective factors. An auto-detection method for PIND output signals is proposed in this paper, which is based on direct wavelet de-noising (DWD), cross-correlation analysis (CCA) and homo-filtering (HF), the method enhances the affectiv-ity of PIND test about the small particles. In the end, some practical PIND output signals are analysed, and the validity of this new method is proved.     

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl4 and SbCl3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using: (1) an ion-exchange hydrolysis to remove chlorine ions, and (2) isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.     

Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters

The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it at- tains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions (from 500-750 ℃).     

超声速燃烧数值模拟中的湍流与化学反应相互作用模型

高精度数值模拟有助于理解超声速湍流燃烧中湍流与化学反应的相互作用,可为发动机燃烧室等工程应用设计提供可靠的预测模型。除直接数值模拟外,目前在湍流燃烧应用中使用的大涡模拟和雷诺平均Navier-Stokes模拟均需要借助模型模化发生在湍流小尺度上的流动与化学反应过程对湍流大尺度运动的影响。现有的湍流与化学反应相互作用模型大致可分为:火焰面类模型和概率密度函数类模型,2类模型在不同的应用中各自具有优势和局限性。此外,现有模型大都基于低马赫数燃烧,而超声速燃烧中通常会伴随快速混合、局部熄火和再着火以及激波等复杂过程,这为发展其中的湍流与化学反应相互作用模型提出了更多的挑战。     

适于低轨卫星IP网络的单核共享树组播算法(英文)

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法。CCST 算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。     

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.     

Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession

The slewing motion control of a truss arm driven by a V-gimbaled control-moment-gyro (CMG) is a nonlinear control problem. The V-gimbaled CMG consists of a pair of gyros that must precess synchronously. The moment of inertia of the system, the angular momentum of the gyros and the external disturbances are not exactly known. With the help of feedback linearization and recursive Lyapunov design method, an adaptive nonlinear controller is designed to deal with the unknown items. Performance of the proposed controller is verified by simulation.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.