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    25 December 1996, Volume 16 Issue 06 Previous Issue    Next Issue
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    SUMMARY OF SATELLITE CONSTELLATION DESIGN
    She Mingsheng;Dai Chao(Beijing Institute of Spacecraft System Engineering, Beijing 100086)
    1996, 16 (06):  . 
    Abstract ( 1418 )   Save
    This paper investigates the current external and internal situation and progress of the satellite constellation design and introduces the net forming method of ideal satellite constellation and actual application satellite constellation in brief. It also introduces satellite constellation's stability and the method for keeping it.
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    EFFECT OF LIQUID PROPELLANT SPACE ENGINES SYSTEM ON CENTROID DRIFT
    Wang Zhongwei; Zhang Weihua; Hu Xiaoping;Wang Zhenguo(National University of Defense Technology, Changsha 410073)
    1996, 16 (06):  . 
    Abstract ( 1581 )   Save
    ffect of arrangements of a pressure-feed, liquid propellant space engines system on centroid drift of a spacecraft was studied in this paper. A mathmematical model for calculation of the centroid drift was given.Some important conclusions of the arrangements for a liquid propellant space engines system were obtained.
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    TEST AND ANALYSIS OF OUTGASSING PROPERTY OF ADHESIVES
    Wang Xianrong; Chai Qiang; Zeng Keren (Lanzhou Institute of Physics, Lanzhou 730000)
    1996, 16 (06):  . 
    Abstract ( 1729 )   Save
    The outgassing properties of 13 different adhesives for spacecraft are measured with Micro-VCM equipment in Standard ASTM E595-90. The measurements include standard tests, and the standard test with sample prepared before (Vacuum baking at 10-3Pa, 40℃ or 60℃, 48hours). The results indicate that: 1. This vaccum baking and time can obviously decrease Total Mass Loss (TML) of the adhesives. 2. This vaccum baking (at 40℃ or 60℃ ) and time cannot change the property of Water Vapor Regain of the adhesives obviously.
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    FLOW ANALYSIS AND NUMERICAL COMPUTATION OF THERMAL ENVIRONMENT IN GAPS
    Tang Gongyue; Wu Guoting(Beijing Institute of Spacecraft System Engineering,Beijing 100086)Jiang Guiqing (Beijing Institute of Aerodynamics,Beijing 100074)
    1996, 16 (06):  . 
    Abstract ( 1994 )   Save
    Based on different outer flow conditions of the gaps, someresearch on theflow and its mechanism have been discussed respectively in thispaper. A model of flow construction in deep gaps has been given. After interpreting the process of gas heat transfer in gaps in detail, a simple flow model and its computational model within the gap have been given,and its border conditions,relation curves between effected depth and outer flow parameter and certification of the computational result in light of mechanism are presented.Finally, on the basis of the result of computation certified by experiment, comparative relation curves between computational results and experimental results are given, and the mechanism causing the differences is analyzed.
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    EFFECT OF IMPACT LOAD ON DEPLOYMENT PARTICULARITY OF DOUBLE NESTED EXTENDED NOZZLE
    Wang Chengxuan;Bi Xunyin;Su Cheng (Huaihai Institute of Engineering, Lianyungang 222005)
    1996, 16 (06):  . 
    Abstract ( 1624 )   Save
    This paper analysed the effect of impact load on deployment particularity of a double extended nozzle.The computation method presented has a directive function to design of the nozzle and the actuator.
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    A COMPUTATION METHOD FOR ACTIVE ADMITTANCE OF WAVEGUIDE SLOT IN SIMULATED ARRAY ENVIRONMENT
    Yang Jisong(Xi'an Institude of Space Radio Technology, Xi'an 710000)Fu Junmei (Xi'an Jiaotong University, Xi' an 710049)
    1996, 16 (06):  . 
    Abstract ( 1566 )   Save
    By analyzing and synthesizing the advantages and disadvantages of the two generally used design methods for slotted waveguide antenna array (the esperimentally measuring method and the theoretically computing method), the idea and practical method are presented in this Paper, that the aetive admittance and the resonant length of waveguide slot in simulated array environment are computed by theoretically analyzing method. Thus, it can not only leave out the machining of the iest components and the procedure of measurement, but also make full use of the characteristic that theoretically computing method is suitable for the analyzing the small slotted waveguide antenna arrays. So the works for design a slotted waveguide antenna array can be reduced greatly.
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    CURRENT SPACE DEBRIS ENVIRONMENT
    Zhu Yilin(Chinese Academy of Space Technology, Beijing, 100081)
    1996, 16 (06):  . 
    Abstract ( 1517 )   Save
    On the basis of the recent tracking, observation and statistic analysis of space debris and the analysis and study of the recovered experimental devices and samples from orbits, the latest data on number, mass and distribution of the space debris around the Earth are presented.
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    AN OUTLOOK FOR 21ST CENTURY SATELLITE COMMUNICATIONS
    Chen Shiping(Xi'an Institute of Space Radio Technology, Xi'an 710000)
    1996, 16 (06):  . 
    Abstract ( 1527 )   Save
    This paper, in the light of both society service needs and technical progress driving telecommunications technology and industry development, presents the concept of "Information Infrastructure" as well as the strengths and weaknesses in satellite communications firstly, then gives an outlook for satellite communications development, finally introduces some new ideas and new techniques, which are driving and will continually drive satellite communications forwards.
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    SOME PROBLEMS ON THE DYNAMICS OF LARGE DEPLOYABLE MECHANISMS FOR SPACE STATION
    Wu Delong;Wang Yi; Wen Rong (Beijing Institute of Astronautical Systems Engineering, Beijing 100076)
    1996, 16 (06):  . 
    Abstract ( 1724 )   Save
    Due to time-variant or unsteady structure in large deployable mechanisms,the topological configurations and number of degrees of freedom are changable with motion. This unsteady dynamics is more complex than the dynamics of steady mechanical systems. In this paper,deployable mechanisms for space station are classified, their kinematic pairs are defined, constraint characters and equations, geometric and kinematic representations of orbit, attitude and deployment motion, and mathematical model of dynamics considering the flexibility and thermal deformation of structures are presented; the disturbances caused by joint gap, friction,or internal impact within limited distance, gravity and aerodynamic drag are discussed. Finally,some conclusions of experimental study are also discussed.
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    ROCKET ENGINE FAULT DETECTION BASED ON NONLINEAR IDENTIFICATION OF NEURAL NETWORK
    Huang Minchao;Wang Kechang; Chen Qizhi (National University of Defense Technology, Changsha 410073)
    1996, 16 (06):  . 
    Abstract ( 1854 )   Save
    sing the method of an artificial neural network, a real-time algorithm is proposed for the fault detection of a liquid propellant rocket engine in this paper. Neural network used for fault detection can approximate the working process of rocket engine by the way of nonlinear identification technology,and it can also generate an identified residual signal that contains the engine fault message at the same time. If the identified residual signal becomes bigger than a given threshold, then there occurs an engine fault. Neural network can be trained for off-lime condition in all flight or for on-line condition in the stabilizing process of the rocket engine running. The experimental research has shown that the artificial neural network has been successful employed in the fault detection of the large turbo-pump liquid rocket engine.
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