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25 June 1999, Volume 19 Issue 03 Previous Issue    Next Issue

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A Study on Kinematics and Dynamics Modeling of Differential Damping Mechanism in Space Docking Yang Fang Qü Guangji Yang Lei (Beijing Institute of Spacecraft System Engineering,Beijing 100086) 1999, 19 (03):  .  Abstract ( 1759 )   Save Concerning the peripheral docking system of Russian Soyuz spacecraft in ASTP,the paper first studies the structure and basic motion relations of the differential damping mechanism and builds a simplified motion model.Then,by using Kinematics Influence Coefficients(KIC) method,the first and second order of Kinematics Influence Coefficients matrix which can describe each part motion are given.On the basis of kinematics modeling,it discusses the kinetic energy of transmission parts in the differential mechanism,the potential energy of springs connecting with screw rods or gear differential units,and the Rayleigh dissipative function of electromagnetical dampers and friction damper while the dissipative force is considered as being linear with velocity.By means of the Second Lagrange Equation,the mechanism movement differential equations are given and gets the mechanism dynamics modeling is got.Finally the expression of system stiffness coefficient and system damping coefficient in arbitrary docking mode are reached. Related Articles | Metrics

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Dynamic Simulation of A Deployable Truss Structure with Clearances Huang Tieqiu Wu Delong Yan Shaoze Zhang Yong (Beijing Institute of Astronautical Systems Engineering,Beijing 100076) 1999, 19 (03):  .  Abstract ( 1452 )   Save The characteristics of nonlinear equations for a deployable truss structure with clearances are analyzed,numerical solution method for such equations is studied.Nonlinear dynamic responses of a beam and a deployable truss structure are acquired through computer simulation.conclusions are given at last. Related Articles | Metrics

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Error Analysis of Computer Focus For CCD Camera Yang Hua Fu Ruimin Guo Yue (Beijing Institute of Space Machine and Electricity,Beijing 100076) 1999, 19 (03):  .  Abstract ( 1489 )   Save Computer is used to measure the focal plane of CCD camera in order to fix the CCD in it.It's called Computer Focus.The artificial error is minimized by this method.Therefore,both environment and devices are the main sources of measurement error,which can effect the accuracy of measurement.In this paper,We discuss and analyse the error of Computer Focus according to the error theory. Related Articles | Metrics

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Design of Constant Pressure Flowmeter Zhang Dixin Meng Yang Lü Shiliang (Lanzhou Institute of Physics, Lanzhou 730000) 1999, 19 (03):  .  Abstract ( 1712 )   Save A constant pressure flowmeter is a kind of calibration apparatus of gas throughput. The calibration range is (17.1～1×10 -5 )PaL/s with the uncertainty less than 2%. It can calibrate the standard leaking hole with the direct method of meassurement and the comparison method of measurement. In the paper, the design method, the structure parameters selection for the constant pressure flowmeter are introduced. Related Articles | Metrics

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SAR Motion Compensation Requirement Concerning Complicated Line of Sight Motion Errors Cao Fuxiang Yuan Jianping (Northwestern Polytechnical University,Xian 710072) 1999, 19 (03):  .  Abstract ( 1604 )   Save Synthetic Aperture Radar(SAR)relies on knowledge of the relative motion between the flight vehicle(strictly is Antenna Phase Center)and the target.If the flight path of the flight vehicle is not accurately known or the SAR processor is limited in its ability to take the flight data into account,the SAR image will be degraded.This paper studies stripmap SAR Motion Compensation(SARMC)requirement to two types of line of sight(LOS)complicated motion errors of fligtht vehicle,gives analytical equations of SARMC quantitative requirement to LOS comphicated motion errors expressed as allowable maximum value of the mainlobe shift,quadratic phase error,cubic phase error and the Integrated Sidelobe Ratio (ISLR). Related Articles | Metrics

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A Research on Effects of Geomagnetics and Wakes on Spacecraft Surface Charging Xu Yanhou Zhou Jianjun Yu Songgeng Fu Ceji Wu Qingsong (University of Science & Technology of China,Hefei 230026) 1999, 19 (03):  .  Abstract ( 1716 )   Save This paper presents the effects of geomagnatics and wakes on spacecraft surface charging in low orbit.According to the charging mechanism,a numerical simulation is set up by using current collection and “inside out”method of particle tracing,the surface equilibrium potentials of the conductor and non conductor surface of spacecraft are given.The numerical calculation,results agree with the observation and the theoretical analysis. Related Articles | Metrics

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Reliability Analysis of Space Station DMS Based on FDDI Liu Qiang Zhang Zhongzhao Zhang Naitong (Communication Research Center Harbin Institute of Technology,Harbin 150001) 1999, 19 (03):  .  Abstract ( 1701 )   Save This paper first introduces the structure of space station DMS.By analysing of the fault tolerance ability and the reliability of the FDDI、IEEE802 4、MIL-STD-1553B in each case,may be obtained the reliability mathematics models with probability analysis.It also illustrates the DMS reliability variation with the variation of station's quantity and link failure probability,and this provides the foundation of the reliability design of the space station DMS. Related Articles | Metrics

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A Method of CCD Star Image Simulation Zhang Junping Lin Tao Zhou Jianlin Qian Guohui (Harbin Institute of Technology,Harbin 150001) 1999, 19 (03):  .  Abstract ( 2083 )   Save Star identification algorithm is necessary for autonomous attitude determination systems of spacecraft.Being the input of the algorithm,the star pictures imaged by CCD on a star sensor are indispensable for the software debugging,for ground experiments as well as for the evaluation of various star identification algorithms.This paper presents a method of CCD sky map simulation for star sensors,which includes the following procedures:extraction of the observed stars,transformation of position coordinates and grey ness normalization according to CCD camera's parameters,and acquirement of the simulated star pictures.The method has been showed to be feasible by using star identification algorithms. Related Articles | Metrics

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Study on Sampling Test and Reliability Evaluation of Pyrotechnical Devices Guo Weichang (Beijing Institute of Spacecraft System Engineering,Beijing 100086) 1999, 19 (03):  .  Abstract ( 1854 )   Save Wald seqential binomial random sampling plan and Bayes reliability evaluation method are suggested to demonstrate and decide the reliability of Pyrotechnical devices.The calculations indicate,that these methods are suitable for solving small sample sampling problem and will be helpful to save the considerable expenses of test. Related Articles | Metrics

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Experimental Investigation on Flowrate Characteristics of Tripropellant Injectors Shen Chibing Tong Rongyu Zhou Jin Wang Zhenguo (National University of Defense Technology,Changsha,410073) 1999, 19 (03):  .  Abstract ( 1651 )   Save A GH 2/LO 2/RP-1 injector is an important component of a tripropellant rocket engine.Four types of tripropellant injector were employed to conduct the flowrate characteristics test.The regularities of the injectors' mass flowrate variation with each propellant injection pressure drop were studied;the effects of the injectors' configuration on the flowrate coefficient were analyzed,the injectors' flowrate characteristics in tripropellant operating condition were compared with those in bipropellant operating condition;the pressure of the dual-fuel premixed cavity of the swirl injector with premixed fuel injection was measured and the flowrate characteristics of the injector were analyzed.The conclusions obtained in this paper provide an important reference for the optimization design of the tripropellant injectors and the gas/liquid coaxial injectors. Related Articles | Metrics

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A Study of Propellant Consumption of Impulsive Maneuvers in Space Rendezvous Xiang Kaiheng Xiao Yelun (Beijing University of Aeronautics and Astronautics,Beijing 100083) 1999, 19 (03):  .  Abstract ( 1749 )   Save A general solution for multi impulse maneuvers in space rendezvous is derived.On the basis of the solution,the propellant consumption of two impulse maneuvers is studied,the “unreachable point”and “high consumption area”nearby are presented.A physical explanation of the terms is also given.Finally,a comparison between two impulse and multi impulse maneuvers is introduced. Related Articles | Metrics