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25 February 2007, Volume 27 Issue 01 Previous Issue    Next Issue

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Study of Relative Navigation Based on Relative Differential Pseudo Range of GPS Liu Tao Xie Yongchun(Beijing Institute of Control Engineering,Beijing 100080) 2007, 27 (01):  1-8.  Abstract ( 1866 )   Save The method of RVD relative navigation based on relative differential pseudo range of GPS was studied.Firstly,the model error was analyzed when the measure model was linearized at the zero position of relative position,and the bias of relative navigation parameters caused by model error was also induced.Then two better methods that one of correction of model error and the other of nonlinear filter by Strong Tracking Filter were proposed.Finally,computer simulation shows the feasibility of these new methods. Related Articles | Metrics

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Intelligent Control and Physical Experiment Research for High Precision Attitude of Flexible Satellites Li Guangxing Zhou Jun Zhou Fengqi(College of Astronautics,Northwestern Polytechnical University,Xi'an 710072) 2007, 27 (01):  9-13.  Abstract ( 1764 )   Save Intelligent control scheme in view of engineering for flexible space structure was studied such as satellites with solar arrays.According to the requirement of high precision,intelligent control law composed of CMAC neural network and VSC with very simple algorithm and strong robustness was designed.With a physical simulation system based on a single axis air bearing table,the control scheme was realized successfully and high precision attitude was obtained.Results show that the method proposed in this paper is effective. Related Articles | Metrics

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Study on Approaching Strategies for On-Orbit Servicing of Satellites Zhu Yanwei Yang Leping(National University of Defense Technology,Changsha 410073) 2007, 27 (01):  14-20.  Abstract ( 1700 )   Save The approaching strategies for on-orbit servicing are investigated to solve how to approach the target vehicle for the servicer spacecraft.According to Hill′s equations,four fundamental relative motions were presented by analyzing the relative motion between two orbiting vehicles.And then,by combining the fundamental relative motions,four possible approaching strategies named Approaching from Different Plane,Approaching by Hovering,Approaching from All Directions and Approaching along the Same Orbit,were introduced and analyzed.The results show that the strategy of Approaching from Different Plane could save an amount of fuel while other strategies have wide range of application. Related Articles | Metrics

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Investigation of Deviation between Quasi-transient/Steady State and Transient Model Zhong Qi(China Academy of Space Technology,Beijing 100094) 2007, 27 (01):  21-26+46.  Abstract ( 2098 )   Save The temperature deviation based the periodically averaged was defined to evaluate the temperature differences between quasi-transient/steady stale and tansient spacecraft thermal models.The effects of various factors on the temperature deviation were investigated for a spacecraft thermal network model.It is revealed that the deviation approaches 0 for inner parts,thus hinting the substitution of periodically averaged heat source for transient one in thermal balance test does not result in the temperature deviation between test and flight. Related Articles | Metrics

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Using Modified-6S to Simulate the Remote Sensor Signal of Moon Zhao Wei~1 Tang Junwu~1 Yan Wei~2 Chen Guangming~1(1 National Satellite Ocean Application Service,State Oceanic Administration,Beijing 100081)(2 PLA Univercity of Science and Technology,Nanjing 211101) 2007, 27 (01):  27-32.  Abstract ( 1896 )   Save The radiative transfer softwares such as MODTRAN or 6S can be directly used to compute remote sensing radiances of the sensors which illuminated by the sun.But lunar irradiance must be integrated in the computation for the glimmer sensors which detect the lunar radiation reflected by the objects.The lunar surface albedo and extraterrestrial solar irradiance already been known and published were used to calculate the lunar irradiance.Till now only 6S can easily include the lunar irradiance in radiative transfer computation.By description of how to compute lunar irradiance in detail then obtained extraterrestrial moon surface irradiance in the range of 0.250μm~1.500μm. Related Articles | Metrics

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Ground-based Investigations of Vacuum Ultraviolet Radiation Behaviors of Organic Protective Coatings Zhang Lei~1 Yan Chuanwei~1 Chen Rongmin~1 Jin Yanli~2Sun Gang~3 Tong Jingyu~3 Pang Hewei~3(1 Institute of Metal Research,The Chinese Academy of Sciences,Shenyang 110016)(2 Navy Equipment Department,Militray Deputy Part to Shenyang,Shenyang 110031)(3 Beijing Institute of Spacecraft Environment Engineering,Beijing 100029) 2007, 27 (01):  33-40.  Abstract ( 1823 )   Save For the protected polymers in aerospace,the surface change of organic protective coatings in the vacuum ultraviolet radiation was investigated.The results show that VUV irradiation makes organic coatings produce mass loss,whose amount is in large quantity at initial stage and does not almost increase again as the extension of exposure.It is obviously that color of organic coatings except Siloxane have great change.So Siloxane is better in resistance to photo-aging than the others,VUV irradiation can case scission of various chemical bonds in polymers,for example,C-N,Si-CH_3,C-C,epoxy ring,but others such as SI-0,benzene ring,C=O are relatively stable under the environment of VUV irradiation. Related Articles | Metrics

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Demonstration in Fatigue Life and Reliability of Carbon-Fiber Overwrapped Helium Tanks with Titanic Liner Zhang TianpingYang FuquanWang XiaoyongLiu Zhidong(Lanzhou Institute of Physics,Lanzhou 730000) 2007, 27 (01):  41-46.  Abstract ( 1798 )   Save Failure models and fatigue life of composite pressure vessels with titanic lined and carbon fiber overwrapped were introduced breifly.Based on stress and strain data resulted from finite element analysis,the low cycle fatigue life and the reliability,which associated with stress rupture failure,of a real helium tank were presented in details.A qualification test demonstration of the helium tank's reliability applicable to the propulsion subsystem of satellites was identified as well. Related Articles | Metrics

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Effect of the Correlated Interferences to the Eigen-space Decomposition Adaptive Algorithms Wang Yongfang Tan Zhanzhong(School of Electronics and Information Engineering,Beijing University of Aeronautics & Astronautics,Beijing 100083) 2007, 27 (01):  47-54.  Abstract ( 1798 )   Save When the interferences are correlated,the signal-eigenvector may shift to the noise space.At this situation,adopting the eigen-space decomposition adaptive algorithms,will not suppress the correlated interferences except the direction vectors of the interferences are same.When the uncorrelated interferences come from same direction,the eigen-space decomposition adaptive algorithms just detect one interference,but the algorithms will suppress the interferences.The simulation result of the MUSIC and Min-norm algorithms are same as the theory. Related Articles | Metrics

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Study on the Quality Evaluation of Satellite Remote Sensing Image Data Compression System Zhang Hao(National University of Defense Technology,Changsha 410073)Zhang Yulin(Jiu Quan Launch Center of Satellite,Jiuquan 732750) 2007, 27 (01):  55-60.  Abstract ( 1921 )   Save Combing the method of the subjective evaluation and the external evaluation,the thesis studyed deeply on the quality evaluation of satellite remote sensing image data compression.By four tests and analysis,the thesis drives that the subjective evaluation was high external,and was the most basic and valid method on the quality evaluation of satellite remote sensing image data compression now,designing it properly is important.The external evaluation was useful,and PSNR was a good criterion when improving a compression method.The consistency in the subjective evaluation and the extemal evalution,mainly on the parameter of PSNR,XSD and LME. Related Articles | Metrics

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Numerical Simulation of Flow Field of the Parachute Fully Developed Liu Wei Kou Baohua Ge Jianquan Yang Tao Zhang Xiaojin Zhang Qingbin(College of Aerospace and Material Engineering,NUDT,Changsha 410073) 2007, 27 (01):  61-64.  Abstract ( 1731 )   Save The dynamic behavior of parachute system is an extremely complex phenomenon.By applying the Computational Fluid Dynamics(CFD),the flow field of the parachute fully developed is computed based on the three dimension Navier-Stodes equations closed with S-A turbulence model.The simulation results are agreement with the experiment dates,which verifies that the accuracy of the numerical simulation model is ensured.The methods used in this paper can also be used in the design of other parachute systems. Related Articles | Metrics

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Size Optimization of Thermal Protection Systems for Hypersonic Aircraft Xu Chao Zhang Duo(University of Northwest Polytechnical,Xi'an 710072) 2007, 27 (01):  65-69.  Abstract ( 1940 )   Save An engineering method for sizing the thermal protection system(TPS) of hypersonic vehicles was built.Complex optimization method was used to seek optimal thickness with the aim to minimize the TPS weight and limit the aircraft main-structure temperature under acceptable bound.A general purpose finite element(FE) analysis tool NASTRAN was used to get time-variable temperature field at given TPS size.An interface code was created to relate and combine the FE thermal analysis and optimization solving.Details of data exchange between them are present.Finally a numerical example was given and optimization results were discussed detailed. Related Articles | Metrics