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Table of Content

    25 April 2002, Volume 22 Issue 02 Previous Issue    Next Issue
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    Application of Negative-selection Algorithm of Immune-System for Fault Diagnosis
    Gu Jihai Jiang Xingwei Liu Shulin Song Lihui (Harbin Institute of Technology,Harbin 150001)
    2002, 22 (02):  . 
    Abstract ( 1674 )   Save
    The main task of the immune system is to detect and eliminate the non self materials called antigens such as virus and cancer cells which come from inside and outside of the living system The negative selection algorthm proposed which is inspired by the negative selection mechanism of the immune system is able to detect any change The algorithm is improved to make it suitable for the fault diagnosis of spacecraft Moreover,based on the improved algorithm a new method of fault diagnosis of satellite power system is proposed and its feasibility is proved by on line fault diagnosis of satellite power system successfully
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    GPS Circularly Polarized Microstrip Antenna With Single Feedpoint
    Ye Yunshang Li Quanming Yang Xiaoyong (Beijing Institute of Spacecraft System Engineering,Beijing 100086)
    2002, 22 (02):  . 
    Abstract ( 1735 )   Save
    Based on cavity mode theory,GPS microstrip antenna with single feedpoint is analyzed and designed by using perturbation method.The test results show that the antenna can provide excellent circular hemisphere beam,better wide angle circular polarization and better impedance match.It's one kind of good GPS receiving antenna.
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    Progress of the Solar Calibration Technique for Space-borne Multispectral Sensors
    Gu Mingli (Beijing Institute of Space Mechanics & Electricity, Beijing 100076)
    2002, 22 (02):  . 
    Abstract ( 2296 )   Save
    The solar is selected generally as a standard source on the on board solar calibrator of satellite multispectral sensors. The solar radiation is leaded into the space borne remote sensors and adjusted within the sensor's dynamic range by means of the solar calibrator. It is used to provide absolute radiometric calibration to the sensors and may be used to monitor and correct for possible performance changes of the sensors. Some solar calibrators used for space borne multispectral sensors are introduced and analysed, in order to reflect the present state and development of the solar calibration techniques.At present, the use of a solar diffuser is a desirable approach to the on board absolute radiometric calibration. It provides a full aperture, full field and end to end calibration. A serious drawback is that the diffuser's reflectance may change with time. In order to solve the problem a kind of ratioing radiometer or reflectance calibration assembly used to monitor the radiance and reflectance of the diffuser and solar constant is designed. Now the approach comes into use on some advanced space board multispectral sensors. The paper also puts forward some key techniques during the development of the solar diffuser after analyzing this aproach.
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    Attitude Determination Based on Combination of GPS and Magnetometer
    Wang Jianqi Cao Xibin Sun Zhaowei (Harbin Institute of Technology, Harbin 150001)
    2002, 22 (02):  . 
    Abstract ( 1598 )   Save
    An attitude determination approach based on information fusion for attitude determination is presented. Using the two sensors of on board GPS receiver and magnetometer and based on extended Kalman filtering and information fusion theory, the global optimal fusion estimating algorithm which determinates the attitude and rate of satellites is developed. Designs and simulations are processed and contrasted to the algorithm using GPS only. Results show the advantage of this algorithm.
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    A Highly Efficient Method for Calculating the Satellite Orbit Lifetime
    Xiao Yelun Chen Shaolong (Beijing University of Aeronautics and Astronautics, School of Astronautics, Beijing 100083)
    2002, 22 (02):  . 
    Abstract ( 2234 )   Save
    Regarding the evaluation of satellite orbit lifetime under effect of atmospheric drag, a highly efficient numerical method called differentiation integration method is proposed. The essence of this method is a group of differential equations based on the average change rate of orbit elements, and the right sides of these equations contain definite integrals. The calculation comparison between this method and the traditional ones proves its correctness and displays its high efficiency. This method is very powerful especially for problems concerning space debris mitigation that require a large amount of calculation of the satellite orbit lifetime.
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    Discussion of Data Security Implementation Options of CCSDS Recommedations
    Liu Yong Dong Yong (Shandong Institute of Aerospace Electronic Technology, Yantai 264000) Li Zehui (Naval Engineering College of Aeronoutics,Yantai 264001)
    2002, 22 (02):  . 
    Abstract ( 1876 )   Save
    Information security about the CCSDS(Consultative Committee for Space Data System)recommendations is addressed, and the protection of spacecraft emphasized. The generic space mission security threats is simply analyzed. On the basis of the charac teristics of different security implementation options, benefits and shortcomings of dif ferent security implementation are obtained through comparing the impact on the CCSDS data architectures and services. The conclusion is useful to solve information security problems when space data system standards of CCSDS are applied.
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    Development of Anti-Static Thermal Control Coating and Test of Its Related Performance in Simulated Space Environment
    Zeng Yibing Xiong Chunxiao Wang Hui Liu Wenyan (Aerospace Reserch Institute of Materials and Technology,Beijing 100076)
    2002, 22 (02):  . 
    Abstract ( 1903 )   Save
    By diffusion of heavy metal ion into zinc oxide crystal,ACR-1 white antistatic thermal control coating is developed with acrylic resin.The space environment effects on the solar absorbtance of the coating and comparison with silicon white thermal control coating are investigated.It is demonstrated that ACR-1 white anti static thermal control coating shows good space stability in ground based simulated environment.
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    Research on Complete GPS/INS Integration Based on H_∞ Filter
    Zhao Wei Yuan Xin (Nanjing University of Aeronautics & Astronautics, Nanjing 210016)
    2002, 22 (02):  . 
    Abstract ( 1658 )   Save
    Based on the theory of H ∞ robust filter, a tightly integrated GPS/INS system is presented using H ∞ filter. The variable state includes position error, velocity error and attitude error and measurement is composed of pseudorange, pseudorange rate and carrier phase. In order to improve the robust of the complete integrated navigation system, H ∞ robust filter is adopted. The dynamic simulation is carried out and the result shows that the simplified system can work with better precision and excellent robustness. The scheme can put into practice easily.
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    The Description of Satellite Formations and Its Analysis to Disturbance
    Yang Yu Han Chao (Beijing University of Aeronautics and Astronautics, Beijing100083)
    2002, 22 (02):  . 
    Abstract ( 1582 )   Save
    A set of parameters for relative motion of satellite formations and the method to design the formation is dofined. On the basis of the relative parameters, how the non center Earth Gravitational Potential affect these parameters is analyzed and the velocity impulse to eliminate the secular effect of disturbance is given. Moreover, the design method of some relative parameters to reduce the effect of gravitational disturbance is proposed.
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    Analysis of Spacecraft Relative Motion and Applicability of Hill's Solution
    Zhang Zhenmin (Harbin University of Technology,Harbin 150001) Xu Bin Zhang Heng Sun Lan Pan Lijun (Institute of Mechanics Chinese Academy of Sciences, Beijing 100080)
    2002, 22 (02):  . 
    Abstract ( 1686 )   Save
    One of the most fundamental problems on spacecraft formation flying, i. e., the analytic solution of spacecraft relative motion and applicability of Hill's equation is proposed in detail. By using necessary geometry mapping, general expression is built up, and then the relative motions under different initial conditions are so comprehensively characterized that the applicability condition of Hill's approximation is obtained. Furthermore, a new simplified formula for formation design is provided in low elliptic orbits.
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    Investigation into Velocity Characterization of Debris Cloud Created by Projectile Impact on Bumper
    Zhang Wei Pang Baojun Ma Wenlai Zhang Zehua (Harbin Institute of Technology,Harbin 150001)
    2002, 22 (02):  . 
    Abstract ( 1562 )   Save
    High velocity impact on long duration and large size spacecraft by meteoroid and space debris is a threat to spacecraft safety operation,Which can in turn lead to significant damage and catastrophic failure.In order to conduct an accurate assessment of spacecrat module wall damage impacted by debris cloud created by meteoroids and space debris high velocity impact on bumper,the velocity characterization of debris cloud must be known.Based on the principles of momentum and energy conservation,the analysis model of debris cloud velocity characterization is presented in this paper.The velocity characterization of debris cloud is calculated,the travel velocity and spread angle of debris cloud material is obtained.
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