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25 February 1996, Volume 16 Issue 01 Previous Issue    Next Issue

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NUMERICAL CALCULATION OF FLEXIBLEMULTI-BODY DYNAMICS FOR LARGE DEPLOYABLEMECHANISMS OF SPACE STATION Wang Yi;Wu Delong(Beijing Institute of Astronautical Systems Engineering,Beijing 100076) 1996, 16 (01):  .  Abstract ( 1641 )   Save n this paper,some research works on numerical method and programto the mathematics model in reference[1]are presented.The local floating coordinatesystem is employed to describe the deployment motion of each component and the normal substructure modals is cut off to describe the flexibility of the components.Thenumerical integration method TREANOR and the mixed procedure are selected tosolve the differential-algebric equations obtained by Kane's method for flexible multibody dynamics of large deployable mechanisms of spqce station.Some discussions onthe establishment of the constraint equations,the selection of independent coordinatesand the ill-condition of the dynamics equations are given.Finally the computer software PFMBDAS is compiled and some numerical exapmples are illustrated. Related Articles | Metrics

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FUNDAMENTAL FACTOR INFLUENCING ON DEPLOYMENT TIME OF DOUBLE NESTED EXTENDED NOZZLE Wang Chengxuan;Zou Jinshu;Su Cheng(Huaihai Institute of Engineering,Lianyungang 222001) 1996, 16 (01):  .  Abstract ( 1793 )   Save his paper analysed deployment time of a double nested extendednozzle under the influence of gravity,inertial force,effective action force and theextended length.The computation results have a directive function to design ofthe nozzle and estimation of the deployment time. Related Articles | Metrics

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FREQUENCY AND ORBIT FOR DATA RELAY SATELLITES Chen Daoming(Chinese Academy of Space Technology,Beijing 100081) 1996, 16 (01):  .  Abstract ( 2007 )   Save n this paper,typical communication links in a data relay satellite system are described,the current and planned uses of the RF spectrum by such systemare presented.Factors affecting frequency selection of data relay satellite bands arealse discussed.In order to prevent from harmful interference from one system to another DRS system,various methods,such as frequency separation,polarization discrimination,longitude separations of neighboring DRS,even CN code discriminationcan be used. Related Articles | Metrics

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APPLICATION OF (HgCd) Te MATERIALS AND INFRARED DEVICES IN SPACE Yang Dequan;Chen Longzhi;Fan Chuizhen(Lanzhou Institute of Physics,Lanzhou 730000) 1996, 16 (01):  .  Abstract ( 2067 )   Save uring the past three decades,(HgCd)Te alloys have foundwidespread applications as infrared detectors,which are vital in a variety of militaryspace and industrial systems.In this paper, development and progress of(HgCd)Tematerials,process and infrared devices in recent years are reviewed.The applicationsof the(HgCd)Te devices,including photoconductive and photovoltaic infrared detectors and arrays in the military space,are descussed. Related Articles | Metrics

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APPLICATION OF GPS IN SPACE RENDEZVOUS AND DOCKING Zhang Zhi;Yuan Jianping(College of Astronautics,Northwestern Polytechnical University,Xi'an 710072) 1996, 16 (01):  .  Abstract ( 1527 )   Save ere in this paper,discussed the benefits that GPS can grant to thespace rendezvous and docking operation(RV&D)and the implementation problems inthe challenge.The implementation aspects of GPS application in the different phasesof RV&D are studied in detail.Finally,the discussion shows the result that GPS canbe used in every phase of RV&D;and the use of GPS can not only improve measuringaccuracy;but also be beneficial to autonomous navigation. Related Articles | Metrics

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STUDY OF THE LD-CELP VOICE CODING ALGORITHM AND ITS COMPUTER SIMULATION Wang Zhengbing;Deng Guanglin(NO.1 International Satellite Communication Earth Staton,Beijing 100094) 1996, 16 (01):  .  Abstract ( 1995 )   Save The CCITT LD-CELP algorithm(CCITT Recommendation G.728)forcoding of speech at 16 kbit/s is a low delay and high efficiency algorithm.Comparedwith traditional CELP algorithm.It shortens coding delay from 2ms to 0.625ms andreduces computation complexity.This paper describes its principle on speech linearprediction and speech vector quantization.By simulation its float algorithm oncomputer,quite good quality of restored speech has been obtained. Related Articles | Metrics

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COUPLED VIBRATION ANALYSIS OF LIQUID COMBUSTIBLE AND STRUCTURE IN SATELLITE Sun Guojiang(Beijing Institute of Spacecraft System Engineering,Beijing 100086) 1996, 16 (01):  .  Abstract ( 1727 )   Save his paper presents the coupled vibration finite element equations ofliquid combustible and structure,according to the control equations in fluid field,thestructure dynamics equations and the conditions of liquid and structure interface.Some examples are given. According to the results of calculation,the coupled vibration problem of liquid combustible and structure in satellites with large quantities ofliquid combustible and the importance of coupled vibration analysis of liquid combustible and structure during the development stage of satellite are discussed. Related Articles | Metrics

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A PRELIMINARY STUDY ON MOTION STABILITY OF BODY-PARACHUTE SYSTEM Li Dayao(Beijing Institute of Space Machine and Electricity,Beijing 100076)Li Dazhi(Nantong College of Medicine,Nantong 326001) 1996, 16 (01):  .  Abstract ( 1619 )   Save he ballistic-lifting reentry vehicle usually is a revolution bodywith its off-axis mass center.This vehicle uses parachute as a principal deceleration means in the last stage of its returning trip to the ground.A study of the motion stability of the combined system that consists of a revolution body with itsoff-axis mass center and a parachute is of practical significance in engineering.Asa preliminary discussion,the system's stability around its equilibrium is examinedand the criteria of the motion stability are given with rigid body model ofparachute assumed and based upon the system's equation of plane motion. Related Articles | Metrics

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STUDY OF CORROSION RESISTANCE OFTiB_2 THIN FILMS ON COPPER BY ION BEAM ENHANCEMENT DEPOSITION Bai Xinde;Wang Sheguan;Fan Yudian(Tsinghua University,Beijing 100084)Kuang Yuanzhu;You Dawei(Space Science and Application Research Center,Academia Sinica,Beijing 100080) 1996, 16 (01):  .  Abstract ( 1508 )   Save iB2 films are deposited onto copper and silicon substrates byIon Beam Enhancement Deposition.The oxidation resistance in air at 600 C,700℃ and 800 C and the electrochemical corrosion resistance in 1N H12So4 aqueous solution of these films are measured.SEM,AES and XRD are employed toinvestigate the morphology,the chemical composition distribution and the microstructure.It is concluded that,1)the TiB2 films by IBED are of good oxidation resistance in high temperature air and of good corrosion resistance in 1NH2SO4 aqueous solution;2)the oxidation and corrosion resistance of the filmsdeposited under the bombardment of enbancement ion beam are better than thatdeposited without the bombardment;3)the bombardment of enhancement ionbeam promotes the formation of TiB2 crystalline particles in their amorphousfilms. Related Articles | Metrics

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ESTIMATION OF CONSTANT SYSTEMATIC ERRORSOF CONTINUOUS WAVE RADAR SYSTEM Wang Zhengming(National University of Defense Technology,Changsha 410073) 1996, 16 (01):  .  Abstract ( 1758 )   Save n this paper,the author presents a nonlinear estimation method of theconstant systematic errors and orbit parameters of continuous wave radar systems.This method processes data in a long time interval altogether,using splines to describeorbit parameters,thus establishing a high precision nonlinear model with fewerparameters.The systematic errors and orbit parameters are thus estimated byapplying this model.Compared with the traditional EMBET method,this method hasthe advantages of much fewer parameters,small model errors, and high accuracy. Related Articles | Metrics