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25 December 1998, Volume 18 Issue 06 Previous Issue    Next Issue

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A NEW SET OF GENERALIZED COORDINATES FOR TETHERED SYSTEMS Zhu Renzhang (Beijing University of Astronautics and Aeronautics,Beijing 100083) Lin Huabao (Chinese Academy of Space Technology,Beijing 100081) 1998, 18 (06):  .  Abstract ( 1988 )   Save A new formulation is presented in this paper,where the following vari ables are taken as a set of generalized coordinates:the radial distance,the latitude and the right ascension of the centre of mass(CM)of the tethered system as well as the tether length and two Euler angles,in the meridian plane and out of the meridian plane,of the tether line relative to the radial vector from the centre of the Earth to the CM.The equations of motion are derived by using the Lagrangian formulas,where the tether is modelled as an elastic continuum with mass but remains straight.The Earth's gravitational potential perturbation and atmospheric drag are taken into account.All classic orbital elements and usual angular motion parameters can be calculated with the new set of generalized coordinates and their rates. Related Articles | Metrics

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RESEARCH OF CALCULATION ERROR PROPERTY OF HILL EQUATION IN SPACE RENDEZVOUS AND DOCKING He Yan (Beijing Institute of Systems Engineering,Beijing 100101) Tan Xichun (Institute of Command and Technology,Beijing 101416) 1998, 18 (06):  .  Abstract ( 1902 )   Save This paper has analyzed all kinds of perturbation forces affecting spacecraft in space in detail,and got a precise model of orbit calculation of spacecraft,and has set up a precise model of relative movement between two spacecraft in space rendezvous and docking.With this error scaling criterion,this paper has analyzed the calculation error of Hill equation in the end. Related Articles | Metrics

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SEMI PHYSICAL SIMULATION DESIGN FOR TRACKING AND POINTING SYSTEM OF FLEXIBLE ANTENNA Qi Chunzi Lü Zhenduo (Beijing Institute of Control Engineering,Beijing 100080) 1998, 18 (06):  .  Abstract ( 1645 )   Save To evaluate the performance of the tracking and pointing control system of the large flexible antenna on satellite,the paper gives two semi physical simulation designs,which put emphasis on how to simulate the base modal vibrations of the flexible antenna by using a two degree of freedom platform with holding springs.Finally,the paper gives the remark by analyzing and comparing the performance of the designs. Related Articles | Metrics

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STUDY OF PROCESSING METHOD OF RANDOM ERROR IN MEASURE DATA OF CONTINUOUS WAVE RADAR Yi Dongyun Zhu Jubo Wang Zhengming (National University of Defense Tecnology, Changsha 410073) 1998, 18 (06):  .  Abstract ( 1741 )   Save No correspondence of processing results in both LS and difference methods is always difficulty to explain clearly in practical. In this paper, first prove that k order difference has the same frequency response as (k 1) order polynomial smoothing of (k+1) data, which reveals the inner connection of two methods. Second, produce the computation formula of correlation interval. Finally, present the new method of separating random error from measure data. Theory and practical processing results show that the new method has high precision. Related Articles | Metrics

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NON METAL MATERIALS OUTGASSING CHARACTERISTIC TIME CONSTANTS Wang Xianrong (Lanzhou Institute of Physics,Lanzhou 730000) 1998, 18 (06):  .  Abstract ( 1610 )   Save The paper presents the concept of non metal materials outgassing characteristic time constant and discusses its use and significance.Test data and their analysis are provided in addition. Related Articles | Metrics

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EVALUATION METHOD OF SHIELDING CONCEPTS FOR SPACECRAFT AGAINST SPACE DEBRIS Zhang Wei Pang Baojun Zhang Zehua Zou Jingxiang (Harbin Institute of Technology,Harbin 150001) 1998, 18 (06):  .  Abstract ( 1677 )   Save This paper, based on the summary of evaluation method of shielding concepts adopted and developed in the world for spacecraft protection from meteoroid and space debris hypervelocity impact, analyzes and discusses the evaluation method of shielding concepts, and provides ballistic limit curves and ballistic limit equations of various types of shielding concepts. Related Articles | Metrics

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AN APPROACH FOR ACTIVE ABERRATION CORRECTION BY USING INTEGRATED MICROMIRROR DEVICE Fu Danying Wu Chongde (Beijing Institute of Space Machine and Electricity,Beijing 100076) Yin Chunyong (Tsinghua University,Beijing 100084) 1998, 18 (06):  .  Abstract ( 1769 )   Save In this paper,a new approach for active aberration correction on spaceborne high resolution camera,by using integrated micromirror device fabricated in MEMS processes,is proposed.Summarization and analysis in general about the features and characteristics of various modern developed micromirror devices in the world are presented. Related Articles | Metrics

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SIMULATION OF ASTRONAUT’S SELF ROTATION Ji Baihua Wen Wenbiao Yuan Xiugan (Beijing University of Aeronautics and Astronautics, The Institute of Man Machine Environment,Beijing 100083) 1998, 18 (06):  .  Abstract ( 1680 )   Save During space performance,proficiency in self rotation may conceivably serve as a criterion for crew selection.By using a body model of 15 segments and dynamics of rigid bodies,the astronaut's self rotation is modeled.The model suits for programming and computation in real time.An animation system has been built to simulate the astronaut's self rotation in real time.only anthropometric data and limbs' rotations are required as input.The system works interactively and draws dynamically. Related Articles | Metrics

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DESIGN OF A MULTI SEARCH GASES LEAK DETECTOR Yan Rongxin (Beijing Spacecraft,Beijing 100080) Xiao Xiangzheng Chen Guangfeng Zhang Jiazhu (Lanzhou Institute of Physics,Lanzhou 730000) 1998, 18 (06):  .  Abstract ( 1776 )   Save The technical measures and the main principle of the European Space Agency leak detector are used for reference.The high vacuum system of mechanical pump and molecular pump is used to get high vacuum.The titanium sublimation pump is designed to hold high vacuum.The high sensitive quadrupole mass spectrometer analyzes the multi search inert gases.The leak detector principle,design character and design calculation are introduced in the paper.The many experiments show that the leak detection limit under the air environment for CF 4 and He is 5×10 -8 ,while the limit for Ne is 5×10 -7 . Related Articles | Metrics

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PREDICTION OF SINGLE EVENT UPSET(SEU) RATES INDUCED BY HEAVY IONS Yu Qingkui Zhao Dapeng Tang Ming (Beijing Institute of Satellite Environment Engineering,Beijing 100029) 1998, 18 (06):  .  Abstract ( 2167 )   Save This paper presents the space radiation environment model of heavy ions and gives the method to calculate the SEU rates of ICs on orbit.SEU rates of a 80C31 microcontroller on board satellites in three different orbits are predicted on the basis of the experimental results utilizing Tandem Van De Graff accelerator. Related Articles | Metrics

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STUDIES ON SPACE FLIGHT TREATMENT TO ULTRASTRUCTURE OF CELLS OF YOUNG LEAVES IN MAIZE Li Sherong,Liu Yanan,Liu Min,Zhang Chunhua,Xue Huai,Zeng Mengqian (Institute of Genetics,Academia Sinica.Beijing 100101) 1998, 18 (06):  .  Abstract ( 1779 )   Save Dried seeds of maize were carried on board recoverable satellite under space conditions of 176km to 354km from sea level.Various ultrastructure changes of maize cells of young leaves were observed,including plasmolysis,expansion of vacuoles and cell walls,proliferation of plasmadesmi,variations of grana disc and stroma thylakoids,breath of nuclear membranes and chloroplast,inscrease in number and enlargement of endoplasm reti culums and variations of other endomembranes. Related Articles | Metrics