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25 August 2001, Volume 21 Issue 04 Previous Issue    Next Issue

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Identification Based Wavelets for Closely Spaced Modes' Parameters of Flexible Space Structures Liu Yiwu Zhang Honghua Wu Hongxin(Beijing Institute of Control Engineering,Beijing 100080) 2001, 21 (04):  .  Abstract ( 1705 )   Save An approach for identification of dense modes' parameters of flexible space structures is studied.Based on wavelet transformation of the system impulse response,when the selected wavelet's analysis frequency is enough high,the closely spaced low frequencies of flexible space structures can be accurately separated and mode parameters be estimated.Simulation results are given to demonstrate the effectiveness of the proposed approach. Related Articles | Metrics

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An Improved Algorithm for the Rejection of Outlier Data Tong Li Zhou Haiyin(National University of Defense Technology,Changsha 410073) 2001, 21 (04):  .  Abstract ( 1788 )   Save The recognition of massive outlier data is a problem with a large number of operations in data processing.As for a large-scaled linear regression model,a fast algorithm to pick out outliers is presented based on the one-by-one method.This algorithm can not only improve the recognition of outliers,especially for massive outliers,but also reduce the computational operations remarkably. Related Articles | Metrics

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Study of GPS-SINS Integrated System With Centimeter Level Cao Fuxiang Bao Zheng(Key Laboratory for Radar Signal Processing,Xidian University,Xi'an 710071) Yuan Jianping(College of Astronautics,Northwestern Polytechnical University,Xi'an 710072) 2001, 21 (04):  .  Abstract ( 1479 )   Save On the premises of concerning position error,the precise model of GPS-SINS integrated system using GPS double differential phase and double differential phase rate measurements derived in this paper.Simulation results show that the positioning accuracy of system is centimeter level and the attitude accuracy is better than 10″ Related Articles | Metrics

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A Study on Singularity Escapable Determining Method of SGCMG System Zhang Jinjiang(Beijing Institute of Control Engineering,Beijing 100080) 2001, 21 (04):  .  Abstract ( 1699 )   Save Single Gimbal Control Moment Gyro system is the best choose of large spacecraft attitude control system.But the phenomenon of singularity exists in this system.This increases difficulty in designing steering law.The singularity states of SGCMG system on the base of singularity analysis are researched,which have redundancy.The construction method of a new redundant SGCMG zero motion differential dynamic equation is established.The character of SGCMG system in the form of zero motion differential dynamic equation is given.The criterion of singularity escapable from reference 4 is improved. Related Articles | Metrics

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Calculation of Radiation Patterns for Satellite Antennas Zhang Zhengguang Ye Yunshang(Beijing Institute of Spacecraft System Engineering,Beijing 100086) 2001, 21 (04):  .  Abstract ( 1839 )   Save The impact of the satellite body and solar panel on the antenna radiation pattern is studied by means of geometrical theory of diffraction (GTD).A numerical simulation software is developed and used to calculate radiation patterns of X-band data transmission antenna (DTA) of the earth resource satellite developed by CAST.The simulation results demonstrate the validity and effectiveness of the simulation algorithm and software. Related Articles | Metrics

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Hydrodynamics Analyses of Working Fluid in Loop Heat Pump Miao Jianyin Hou Zengqi Cao Jianfeng(Beijing Institute of Spacecraft System Engineering,Beijing 100086) 2001, 21 (04):  .  Abstract ( 1818 )   Save Loop Heat Pump (LHP) has great application potentiality in spacecraft thermal control field due to its high efficiency and long distance in heat transfer,good performance in thermal control and flexibility and convenience in installation.Pressure drop of working fluid in LHP is calculated and analyzed.The maximum heat transfer capacity based on LHP capillary structure is forecasted.And combined with experimental research,influence of the capillary structure on LHP characteristics is discussed. Related Articles | Metrics

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A Fast Two Steps Method for Radio Wave Refraction Correction of Range High Trajectory Measurement Zhu Zhuanmin * Yang Yikang * Li Hengnian * Li Jisheng ** Huang Yongxuan *(*Xi'an Jiaotong University,Xi'an 710049) (**Xi'an Satellite Control Centre,Xi'an 710043) 2001, 21 (04):  .  Abstract ( 1931 )   Save Assessing the accuracy of guidance system,especially controlling of missile's attitude and station keeping maneuver and landing point forecasting all rely on the reliable trajectory measurement.The refraction error is main error source among the factors effecting measure data accuracy.Among those different refraction error correction approaches applied currently,one is accurate,but its calculation in real-time is very slow.The other is quicker,but its accuracy is unsatisfied because the simplified model of high precision trajectory is used.The fast two-step method of radio wave refraction correction is proposed in this paper.The simulation demonstrates the method meets the requirement of accuracy and speed in project entirely. Related Articles | Metrics

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The Study of Mass Spectrometer Analysis Leak Detection for Multi-system Spacecraft Yan Rongxin Liu Ping Feng Qi Hong Xiaopeng Li Rui(Beijing Spacecraft,Beijing 100080) 2001, 21 (04):  .  Abstract ( 1779 )   Save Circularly compared measure of search gas sample data,end data and beginning data is used.The standard search quantity gas is directly injected into cumulating room to calibrate the leak rate of multi-system spacecraft.The problems of the linearity and repeat in long time for quadrupole mass spectrometer (QMS) measure are avoided.The apparatus of leak detection of multi-system spacecraft with GAM500 mass spectrometer was manufactured.In the air environment the sensitivity of minimum leak detection is 10 -6Pa·m 3/s.The leak detection results of new multi-system spacecraft are introduced.The reliability is increased.The leak detection time and the leak detection cost are cut down. Related Articles | Metrics

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Behaviors of Addition Type Silicone Thermal Control Coatings in Space Environment Simulated Tan Bien(Beijing Institute of Aeronautic Materials,Beijing 100095)Zeng Yibing Shi Suxing Zhang Lianzheng (Institute of Aerospace Materials and Processing,Beijing 100076) 2001, 21 (04):  .  Abstract ( 1609 )   Save The behaviors of thermal control coating in a simulated space environment are determined.The property changes of silicone thermal control coatings during the UV exposed process and electron exposed process are monitored in-situ.The property changes of different materials are compared.SEM observes the morphology of coatins.ZnO covered with K 2SiO 3 has different effects on property of coatings for both silicone rubber adhesives and silicone resin adhesives,and different bleach phenomenon is observed and its reason is discussed in briefly. Related Articles | Metrics

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Microsatellite Passivity Attitude Control Using Aerodynamic Torque and Gravity Gradient Li Taiyu Zhang Yulin(Inst.of Aerospace and Material Engineering,National Univ. of Defense Technology,Changsha 410073) 2001, 21 (04):  .  Abstract ( 2060 )   Save A scheme of three axis passivity stabilization realized by using two main environmental torque (aerodynamic torque and gravity gradient) for low orbit microsat is presented.Restore torque for pitch and roll orientation is provided by gravity gradient. Restore torque for yaw and pitch orientation is provided by aerodynamic torque.The attitude stability analyses are presented and the simulations are also provided.The result shows that the satellite has simple structure and excellent control precision. Related Articles | Metrics