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25 October 1999, Volume 19 Issue 05 Previous Issue    Next Issue

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Optimization of Satellite Power System Topologies Wang Yongqian Hu Qizheng Han Guojing Fu Qiang (Beijing Institute of Spacecraft System Engineering,Beijing 100086) 1999, 19 (05):  .  Abstract ( 1631 )   Save Optimization of satellite power system topologies is an important way for reducing the weight.In terms of the sun synchronous orbit satellite,the energy transferring charts of four typical Direct Energy Transferring(DET)power systems are developed and the energy balance equations are derived.The optimal model is built up via minimizing the weight power ratio,which is based on the energy balance equations.An optimal analysis for the four kinds of DET power system topology is performed by taking the Descending Node Local Time,the ratio of the loads' peak energy consumption and long term energy consumption,the loads' power ratio in the orbit day and night as the design variables.An examples is calculated and the conclusions of the optimization are drawn. Related Articles | Metrics

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The Conditions and Relative Trajectories for Astronaut Departing From Large Size Space Station Zhang Xiaomin Xiao Yelun (Beijing University of Aeronautics and Astronautics, Beijing 100083) 1999, 19 (05):  .  Abstract ( 1794 )   Save By using dynamical equations of short distance relative motion with consi deration of the size of space station, the conditions and relative motion trajectories for astronaut departing from large size space station are studied. At the positions on up outside, down outside, downward fore outside or upward back outside, 1) when not bound, the astronaut will drift freely without power, his relative motion mode in orbit plane is ellipse with drifting center; 2) the relative motion mode in orbit plane for powered departure is straight line, steady ellipse or ellipse with drifting center. These results are essentially different from those based on the model of space station as mass point. Depending on departure positions or departure velocities, different extravehicular relative trajectories could be achieved in order to satisfy various requirements. Related Articles | Metrics

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Periodically Time Varying PD Controller Design for Small Satellite with Magnetic Control System Wang Ping Li Tieshou Wu Hongxin (Beijing Institute of Control Engineering,Beijing 100080) 1999, 19 (05):  .  Abstract ( 1813 )   Save The magnetic control system for polar orbiting,nadir pointing small satellite is studied in this paper.It is shown that the dynamics with magnetic control system is a linear periodic system.Taking into account properties of the geomagnetic field,a new PD magnetic control law using the feedback information of attitude angle and attitude rate is developed.The PD controller has periodically time varying gains to ensure the control system for required transient and steady performance. Related Articles | Metrics

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A Study on Using Three Station United Measured Iteration to Solve Spacecraft Position Cao Xueyong Liu Chengjun (Beijing Command Center,Beijing 100094) 1999, 19 (05):  .  Abstract ( 1642 )   Save Using three station united measured data to determinate spacecraft position by iteration is studied.The convergence property of iteration is analysed based on matrix iterative solution and field and tensor theory.A reasonable explanation is given that iterative convergence point is under the ground. Related Articles | Metrics

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A Study of Space Technology System Wang Xiji (Chinese Academy of Space Technology,Beijing 100081) 1999, 19 (05):  .  Abstract ( 1712 )   Save With development of social demands and satisfaction of space mission goals,on the basis of general systematology,a new conception of space technology system is presented.The space technology system is composed of four subsystems.They are spacecraft entry space technology,space functional applying technology,space protection technology and space weapon technology.It is different from the other space technology system which is centred on development of carries and spacecrafts. Related Articles | Metrics

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A Study on Dynamics Modeling of Flexible Spacecraft Miao Bingqi (Zhejiang University of Technology,Hangzhou 310014) Qu Guangji Cheng Daosheng (Beijing Institute of Spacecraft System Engineering,Beijing 100086) 1999, 19 (05):  .  Abstract ( 1567 )   Save Some review literatures on dynamics modeling of flexible spacecraft are presented. The difficulties in modeling large flexible spacecraft are discussed. The problems on deformation description of flexible body, selection of floating reference frame, derivation of dynamic equations and model reduction are analysed. Related Articles | Metrics

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A Study of the Antistatic Technology for Satellite Antenna Ding Xiaolei Lu Yusun (Lanzhou Institute of Physics,Lanzhou 730000) 1999, 19 (05):  .  Abstract ( 1657 )   Save The prime space plasma environment of the satellite and its antenna in the geosynchronous orbit and low altitude polar orbit is introduced.The charging on the surface of satellite antenna is dangerous to the satellite electronics.The compound configurations of the antistatic film coating the white paint to the inner surface of the Kapton,the conductive film to the outer surface of the Kapton,and the soluble polyimide with tinoxide are developed.The environment effectiveness test,the effect of antistatic film on the antenna performance test and charging-discharging review test under the charging environment are presented.The results of the tests show that the antistatic methods can satisfy the frequency requirements of antenna and prevent the surface of antenna from charging. Related Articles | Metrics

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Thermal Analysis of an Intravehicular Space Suit Yu Xuejun Wu Jianmin Chang Shaoyong Qiu Man Wen Jifu Yang Tiande (Institute of Space Medico Engineering,Beijing 100094) 1999, 19 (05):  .  Abstract ( 1598 )   Save The mathematical relationship between heat dissipation from a intravehi cular space suit and air ventilating parameters(air temperature,air flow rate and relative humidity) as well as metabolic state(at rest or exercise) of man is founded by calculating the data from 24 tests performed on 6 young male subjects wearing space suit at sea level.Combined second design is employed to arrange the tests.The thermal characteristics of the suit and their influences are figured out according to the mathematical model. Related Articles | Metrics

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An Optimal Allocation Model of the Partial Satellite System Design Specification Cao Xibin Zhang Fan (Harbin Institute of Technology,Harbin 150001)$$$$ 1999, 19 (05):  .  Abstract ( 1943 )   Save Allocating properly the system specification plays an important role in the satellite system design.In the paper,satellite system design specification including error,mass,power and reliability are optimally allocated with nonlinear optimization and Multiobjective and Multidisciplinary Design Optimization (MMDO).The result shows that the optimization models and the optimization methods,nonlinear optimization and multiobjective and multidisciplinary design optimization,are both feasible and effective. Related Articles | Metrics

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The Simple Algorithm of Electromagnetic Refraction Error Due to Atmosphere Refractivity Dry Component Zhang Yu (China Research Institute of Radiowave Propagation,Xinxiang 453003))$$$$ 1999, 19 (05):  .  Abstract ( 1634 )   Save The simple algorithm of electromagnetic refraction error due to atmosphere refractivity dry component is presented.It puts emphasis on the method to obtain the practical model of the equivalent height of atmosphere refractivity dry component and ground temperature under existing conditions with the example of the model cofficient in a certain area of China. Related Articles | Metrics

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Experimental Investigation on Correction of Thermal and Gravitational Distortion of Mirrorswith Adaptive Optics Zhang Zhiwei (Beijing Institute of Space Science & Technology Information,Beijing 100086) Yu Xin (Beijing Institute of Technology,Beijing 100081) Yang Bingxin (Beijing Institute of Space Mechanics and Electronics,Beijing 100076)$$$$ 1999, 19 (05):  .  Abstract ( 1719 )   Save The paper presents the necessity of employing adaptive optics on high resolution space mirror.The experimental setup of the correction of mirror thermal and gravitational distortion using adaptive optics is introduced.The experiment result is compared with that of the finite element analysis.A reflective plane mirror is used as a model of the primary mirror of the space camera to simulate its thermal and gravitational distortion.A close loop experiment with the 61 unit adaptive optics system is done,the corrective effect of the aberration of the Zernike polynomial is analyzed,and the biggest distortion (P V) value and RMS value of the wavefront after close loop correction is λ/4 and λ/30 seperately.This experiment greatly support the application of adaptive optics on space camera. Related Articles | Metrics