Abstract:The research advance in infrared radiation characteristics of earth's atmosphere at abroad is presented in brief. Particularly, the domestic research status of infrared radiation characteristics of earth's atmosphere is overviewed in the following three aspects: the calculation with foreign mature software, the related research based on basic theory and the independent research and development of atmospheric infrared radiation calculation software. Finally, the relative content which need to be further studied is discussed.

Abstract:To ensure imaging quality, the optical and other subsystems of a large space camera need to be supported and fixed by using a structure with good mechanical property, low weight and small volume. The features of a hinge joint and a bolt-glue joint are analyzed and both joints are compared with each other in mechanical property. According to the performance of rod material and frame material used, the titanium alloy is selected as the material for joints. In view of the complexity of composite manufacturing processes and the high strength and stiffness requirements of bonding, a reasonable bonding process which can avoid and control the stress generated during bonding is established. Finally, the effectiveness of this joint design is verified in static and dynamic mechanical tests. The test results show that this bolt-glue joint design is an optimized and reasonable one.

Abstract:Currently, the aspheric mirrors used in space remote sensors are generally supported with a supporting structure containing a flexible link and a backboard. Because the supporting structure accounts for a large proportion in weight, its configuration and weight should be simplified and reduced respectively. According to the principle of three-point orientation and bipod flexure, three flexible link structures for simplifying the configuration of the support are designed. The design result is analyzed by using a finite element software. The result shows that this support configuration is able to adapt the mechanical and thermal environment in space. It can meet the required precision and can be used to support large diameter aspheric mirrors. Because the mirror backboard commonly used in the traditional configuration is removed, this support configuration is simplified. Its weight is reduced and its machining and assembling difficulties are also reduced.

Abstract:Since there may be a fatigue problem when a high volume fraction SiCp/Al-based composite material is used in the structure design of a space remote sensor, the fatigue failure behavior of the material is studied. Firstly, several fatigue testing methods are presented. A conventional testing method is selected to test the fatigue strength of the material. The fatigue test is planned. Then, a mathematic model of the key parameters in the S-N curve is established by using a three-parameter exponential function model to process the experimental data. A method for selecting vibration frequency in the vibration test is proposed. Finally, five specimens are tested on a vibrating table. The observed test data are fitted by using the three-parameter exponential function model. The result shows that the material has a fatigue strength of 161 MPa. This result is very helpful to the structure design of space remote sensors.

Abstract:According to the motion of the Al2O3 particles in a hybrid rocket engine, the inside and outside flow fields of the engine nozzle are simulated numerically and integrally. The parameters such as temperature, pressure, composition concentration and particle concentration are obtained. The gas spectral absorption coefficient is calculated by a line-by-line integration method based on the latest HITRAN and HITEMP databases. The radiation characteristic parameters of solid particles are calculated by using Mie's theory. The infrared radiation intensity of plume is calculated by using a model based on the discrete radiation transfer equation of the finite volume method. Through further solution, the spectral radiation intensity in particular wavebands are obtained. Finally, practical tests are carried out by using a thermal imager operating in the waveband from 8 μm to 14μm and are compared with the numerical calculation results. The result shows that this calculation model and method can simulate the infrared radiation characteristics of the exhaust plumes from hybrid rocket engines well.

Abstract:An infrared target location method based on a saliency map is proposed. That is, the target detection is implemented by using an improved Itti model to generate a saliency map and segmenting the target area in the saliency map. Firstly, the wavelet transformation other than the Gaussian filter in the Itti model is used to generate a multi-scale pyramid. Then, the center-surround operators are used to extract multi-scale saliency difference signatures and the generated saliency signature maps are combined into a saliency map. Finally, a threshold segmentation method is used to segment the target area. The original images are marked so as to implement target detection. The experimental result shows that compared with the traditional Otsu threshold segmentation method, this method can detect the target area more accurately.

Abstract:To further improve the ability of analyzing complex solution composition and extract more spectral information about absorption and scattering component, a multi-position and multi-optical path diffuse transmission spectroscopy is used to analyze complex solution composition quantitatively. 100 kinds of fixed solution containing different composition are formed in an experiment. The multi-position and multi-optical path transmission spectral distribution data of the near infrared light in the waveband from 650 nm to 1000 nm passing through the complex solution are simulated by using the Monte-Carlo (MC) method. A partial least square regression modeling method is used to model the spectral data at the central point in one optical path, the spectral data in multi-positions in one optical path and the spectral data in multi-positions and multi-optical paths with intralipid solution ingredients in the complex solution respectively. It is derived by comparison that the modeling accuracy and prediction of the composition in complex solution can be improved by increasing the spectral data in different radial positions and the spectral data in multi-optical paths.

Abstract:The infrared thermal images and leaf water potential (ψL) of two cotton cultivars named Xinluzao-33 and -13 were obtained at five growth stages after five different irrigation processes. The temperature values of the canopy sunlit leaves were extracted from the thermal images and the crop water stress indexes (CWSI) were calculated. The analysis result showed that the canopy CWSI and ψL of two cotton cultivars at five different irrigation levels changed inversely with the growth stage, and the ψL was consistent with the growth of cotton. Their change orders were all W5> W4> W3> W2> W1. The ψL of the tested samples was estimated by using the linear regression function between the CWSI and ψL of the modeled samples ($r=0.8903**, n=24, α=1%). The measured ψL had a significant linear correlation with the estimated ψL ($r=08971**,RMSE=0.1223, n=24,α=1%). The estimated ψL had a relative error of 0.0981. Its estimation accuracy was 90.2%. The result showed that the CWSI based on the infrared thermography could be used to estimate the leaf water potential of cotton rapidly and nondestructively in real time and could be used to predict the water potential accurately.