先进激光测量技术在航空发动机燃烧室研发中的应用

在航空发动机燃烧室的研发过程中,传统的测量手段往往有时无法实施或不能满足精确捕捉流场信息的要求,发展新型、高精度测量以及先进诊断技术势在必行。重点介绍了适用于航空发动机燃烧室测量的先进激光测试技术,并与传统测量方法进行了比较。发动机燃烧室内的流场测量包括速度测量、温度和组分质量分数测量。氢氧根离子标记测速(HTV)方法适用于有化学反应流场的速度测量;而拉曼散射测量技术可以同时测量多种组分的质量分数和温度。利用这些激光测量技术的特点,可以使其在燃烧室的点火、贫油熄火及排放等性能的研究中发挥重要作用。     

SATI image processing and mesopause temperature determination

The Spectral Airglow Temperature Imager (SATI) instrument registers airglow coming from an annular mesopause segment. The temperatures of various points of this segment are retrieved by sectors of the registered images containing spectral information. A stage of SATI spectrogram processing connected with deriving spectral information from images and the determination of the rotational temperature of oxygen molecules emitting at the altitude of the mesopause is considered.     

HW/SW Co-design of the Instrument Control Unit for the Energetic Particle Detector on-board Solar Orbiter

ESA’s medium-class Solar Orbiter mission is conceived to perform a close-up study of our Sun and its inner heliosphere to better understand the behaviour of our star. The mission will provide the clues to discover how the Sun creates and controls the solar wind and thereby affects the environments of all the planets. The spacecraft is equipped with a comprehensive suite of instruments. The Energetic Particle Detector (EPD) is one of the in-situ instruments on-board Solar Orbiter. EPD is composed of five different sensors, all of them sharing the Instrument Control Unit or ICU that is the sole interface with the spacecraft. This paper emphasises on how the hardware/software co-design approach can lead to a decrease in software complexity and highlights the versatility of the toolset that supports the development process. Following a model-driven engineering approach, these tools are capable of generating the high-level code of the software application, as well as of facilitating its configuration control and its deployment on the hardware platforms used in the different stages of the development process. Moreover, the use of the Leon2ViP virtual platform, with fault injection capabilities, allows an early software-before-hardware verification and validation and also a hardware–software co-simulation. The adopted solutions reduce development time without compromising the whole process reliability that is essential to the EPD success.     

一种摄录设备的检测方法研究

摄录设备小型化完成后,移植到不会造成人员伤亡的无人机上,应用在军事或高危领域。为避免拍摄失败,需要大量且周全的飞行前检查测试。介绍了某摄录设备的结构原理,论述了地面检测的环境方法,通过地面与空中视频图像的对比,验证了检测方法的合理性。     

光电跟踪仪光轴一致性测量装置

设计了大口径离轴抛物面镜平行光管光学系统,研制了基于CCD图像采集处理的激光光斑中心坐标提取系统,研制了基于光栅尺的位移闭环控制系统,建立了光电跟踪仪光轴一致性参数测量装置。装置可用来测量光电跟踪仪激光发射轴、电视成像系统、红外成像跟踪系统三轴的一致性,测量不确定度为0.02mrad。     

基于小波阈值降噪和经验模态分解的高光谱图像分类算法

为了充分降低高光谱图像中的噪声以获得高精度的分类结果,本文结合小波阈值降噪(WTD)和经验模态分解(EMD)的优点,提出了一种基于小波阈值降噪-经验模态分解的高精度支持向量机(SVM)高光谱图像分类算法(WTD-EMD-SVM)。首先对高光谱图像进行小波阈值降噪,除去高光谱数据中的高频噪声;然后再对高光谱图像进行EMD,获得含有高光谱数据本质特征的内固模态函数(IMF)和含有低频噪声的残差;最后采用内固模态函数重构高光谱图像,并对高光谱图像进行SVM分类。将其应用到AVIRIS数据92AV3C,仿真结果表明该算法不仅提高了高光谱图像分类精度,同时可减少支持向量数目,以提高高光谱图像分类速度。     

基于SAR景象不变特征点的匹配定位技术研究

针对精确制导领域中的SAR景象匹配定位技术中由于实时图与基准图可能存在形变、分辨率不一致,图像旋转及雷达视角变化及噪声的影响下差异较大情况时直接利用基于灰度的规则正交二维信息匹配算法适应性差的问题,将不变特征点匹配方法(Scale Invariant Feature Transform,SIFT)应用到SAR景象匹配中,通过仿真实验取得了满意的效果,试验结果表明SIFT特征是图像的局部特征,其对旋转、尺度缩放、亮度变化保持不变性,对视角变化、噪声也保持一定程度的稳定性,对提高匹配概率和对不同图像的适应性,降低应用风险具有借鉴意义。     

复杂背景中红外弱小目标检测技术研究

对复杂背景中红外弱小目标检测识别的一种图像处理技术进行了研究。用最大中值滤波进行预处理以抑制孤立噪声影响,采用时域方差滤波抑制背景信息,对滤波后的图像根据直方图信息进行自适应二值化处理,由多帧轨迹确定目标。用实验与基于形态学算子滤波的目标检测算法进行了比较,结果表明该算法能获得较满意的目标检测结果,两种滤波方法的组合可有效提高信噪比。     

Comprehensive optimization design of aerodynamic and electromagnetic scattering characteristics of serpentine nozzle

Comprehensive optimization design of serpentine nozzle with trapezoidal outlet was studied to improve its aerodynamic and electromagnetic scattering performance. Serpentine nozzles with different center offsets and different ratios of the bases of the trapezoidal outlet were generated based on curvature control regulation. Computational Fluid Dynamics (CFD) simulations have been conducted to obtain the flow field in the nozzle, and Forward-Backward Iterative Physical Optics (FBIPO) method was applied to study the electromagnetic scattering characteristics of the nozzle. Guarantee Convergence Particle Swarm Optimization (GCPSO) algorithm based on Radial Basis Function (RBF) neural network was used to optimize the geometry of the nozzle in consideration of its aerodynamic and electromagnetic scattering characteristics. The results show that the GCPSO method based on RBF can be used to optimize the aerodynamic characteristics of the internal flow and the scattering characteristics of the cavity of the serpentine nozzle with irregular outlet. The optimized model has a higher center offset and a lower ratio of the bases of the trapezoidal outlet after optimization compared to the original model. The optimized model leads to a slight change in aerodynamic performance, with a total pressure recovery coefficient increase of 0.31% and a discharge coefficient increase of 0.41%. In addition, the Radar Cross Section (RCS) decreases also by around 83.33% and the overall performance is significantly improved, with a decrease of the optimized objective function by around 38.74%.     

Construction of lunar DEMs based on reflectance modelling

Existing lunar DEMs obtained based on laser altimetry or photogrammetric image analysis are characterised by high large-scale accuracies while their lateral resolution is strongly limited by noise or interpolation artifacts. In contrast, image-based photometric surface reconstruction approaches reveal small-scale surface detail but become inaccurate on large spatial scales. The framework proposed in this study therefore combines photometric image information of high lateral resolution and DEM data of comparably low lateral resolution in order to obtain DEMs of high lateral resolution which are also accurate on large spatial scales. Our first approach combines an extended photoclinometry scheme and a shape from shading based method. A novel variational surface reconstruction method further increases the lateral resolution of the DEM such that it reaches that of the underlying images. We employ the Hapke IMSA and AMSA reflectance models with two different formulations of the single-particle scattering function, such that the single-scattering albedo of the surface particles and optionally the asymmetry parameter of the single-particle scattering function can be estimated pixel-wise. As our DEM construction methods require co-registered images, an illumination-independent image registration scheme is developed. An evaluation of our framework based on synthetic image data yields an average elevation accuracy of the constructed DEMs of better than 20 m as long as the correct reflectance model is assumed. When comparing our DEMs to LOLA single track data, absolute elevation accuracies around 30 m are obtained for test regions that cover an elevation range of several thousands of metres. The proposed illumination-independent image registration method yields subpixel accuracy even in the presence of 3D perspective distortions. The pixel-wise reflectance parameters estimated simultaneously with the DEM reflect compositional contrasts between different surface units. Specifically, the detected variations of the parameter of the single-particle scattering function indicate small-scale variations of the regolith particle size, possibly as a result of differences in soil maturity.