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25 April 1999, Volume 19 Issue 02 Previous Issue    Next Issue

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Numerical Simulation of Stray Light in CCD Camera with the Monte Carlo Method Wang Pingyang Xia Xinlin Tan Heping (Harbin Institute of Technology,Harbin 150001) 1999, 19 (02):  .  Abstract ( 1804 )   Save The stray light level in CCD camera is calculated with the Monte Carlo method.The comparison of the stray light coefficient of the main section from the present study with that from the experiments using integral sphere shows both the results are of the same order of magnitude.It also shows that the method and software in this paper are reliable to a certain extent.The factors causing the dissent between the calculated result and the experiment value are analyzed.So it can be said that the effect of thermophysical property parameters on the numerical simulation is significant.The analysis included the effects of the length of sunshade and the angle of reflective mirror on the stray light coefficient.The result shows that if the length of sunshade is kept unchanged,the stray light coefficient arrives at minimum and the light entry proportion is the maximum when the scan angle is 45° Related Articles | Metrics

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A Study of Compound Control in Tracking and Pointing System of Flexible Antenna on Satellite Qi Chunzi Lü Zhenduo (Beijing Institute of Control Engineering,Beijing 100080) 1999, 19 (02):  .  Abstract ( 1771 )   Save Based on the study of restraining vibration and by the method of all coefficient adaptive control,the paper analyses and designs compound controllers on a tracking and pointing system of flexible antenna on satellite.The method also achieves good decoupling control results in this multivariable system.Finally,the paper gives the simulation results that meet the engineering demands. Related Articles | Metrics

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Analysis and Calculation of the Vapor Flow Resistance in the Wick of the Inverted Meniscus Type Evaporator Zhang Jiaxun Hou Zengqi (Beijing Institute of Spacecraft System Engineering,Beijing 100086) 1999, 19 (02):  .  Abstract ( 1756 )   Save With the analysis of the characteristics of the Capillary pumped Loop (CPL) during steady operation, it is concluded that the heat transfer mode of the inverted meniscus type evaporator, in this case, is surface-evaporation. In addition, the method to calculate the vapor flow resistance in the wick of the inverted meniscus type evaporator is also presented. With this method, the calculation of an actual CPL model is carried out, and it is obtained from the analysis that the vapor flow resistance in the wick should be taken into account during the CPL's design. Additionally, it is also known that the permeability of the wick has a great effect on the resistance. Related Articles | Metrics

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Control Structures Integrated Design of Space Deployable Mechanism Yan Shaoze Wu Delong Huang Tieqiu Zhang Yong (Beijing Institute of Astronautical System Engineering,Beijing 100076) 1999, 19 (02):  .  Abstract ( 1716 )   Save Through analysis of problems in the traditional sequencal design,the control structures integrated design of a space deployable mechanism is presented,in which parameters of structure and control are simultaneously selected as design parameters and systematically optimized,based on objective functions.A integrated design model of the space deployable mechanism is developed,and the analysis results show that the integrated design methodology is superior to the traditional sequencal one.The technology will provide theoretical base and design methods for new generation space spacecraft. Related Articles | Metrics

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A Study of Contoured Beam of Satellite Shaped Reflector Antenna Xia Wen Wang Huazhi Ma Wenhua (Beijing University of Posts and Telecommunications,Beijing 100876) 1999, 19 (02):  .  Abstract ( 1657 )   Save The optimization technique of the phase distribution of the apterture plane grid field is presented to contour China map by using shaped reflector with a single feed.In order to avoid the discontinuity of the reflector surface,a restraint is defined in the process of optimization.The contoured result of this antenna contrasted with that of array fed reflector proves that shaped reflector with a single feed is desirable and applicable for contoured beam. Related Articles | Metrics

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General Strategies for Orbital Rendezvous Zhu Renzhang Yu Nanjia (Beijing University of Astronautics and Aeronautics,Beijing 100083) Li Yili (Chinese Acadeny of Space Technology,Beijing 100081) 1999, 19 (02):  .  Abstract ( 1501 )   Save Manoeuvres strategies for orbital rendezvous are discussed in terms of general architecture and processing algorithms,where impulsive thrust as well as “N boosts” and continuous boost with small thrust are considered. Related Articles | Metrics

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Development of Thermal/Structural/Optical Analysis of Space Remote Sensor Fu Danying Wu Chongde (Beijing Institute of Space Machine and Electricity,Beijing 100076) Yin Chunyong (Tsinghua University,Beijing 100084) 1999, 19 (02):  .  Abstract ( 1721 )   Save The development,methods and applications of Thermal/Structural/Optical (TSO) analysis of space sensor are discussed.TSO analysis is affirmed as an important approach to enhance the reliability of long lifetime space remote sensor.In order to perform TSO analysis of a whole fuselage of space optical camera,the scheme,flow process,keypoints and intentional solution method are proposed and described. Related Articles | Metrics

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A Study of Relation to Leak Rate and Pressure Yan Zhiping Huang Shuying (Beijing Spacecraft,Beijing 100080) 1999, 19 (02):  .  Abstract ( 2533 )   Save A relationship between leak rate and pressure in a seald system at high pressure is studies.In this paper,the theoretical analysis and the leaking experiment are presented.The experiment was accomplished with various physical leaking holes at varied pressure.The experimental results show that the relationship is correct and the exponent of the gas pressure increases with the decreasing length of leaking hole. Related Articles | Metrics

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Initial Value Method of Orbit Determination Using Two GPS Satellites Liu Yanfang Ju Tao (Beijing Institute of Satellite Information Engineering,Beijing 100080) Hong Bingrong (Harbin Institute of Technology,Harbin 150001) 1999, 19 (02):  .  Abstract ( 1654 )   Save Based on the research of orbit determination by using two GPS satellites,this paper discusses the initial value problem and provides an effective method of getting initial value.Computer simulation shows this approach can give a certain and practical initial value.As a result,the amount of calculation is cut down consumedly and the convergence performance of the algorithm is improved.This technique is superior to the traditional guess method in the engineering area. Related Articles | Metrics

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Analysis of Pressure Variety of Inert Gas in Fully shielded Welding Chamber Chen Guangfeng Guo Fenying (Lanzhou Institute of Physics,Lanzhou 730000) 1999, 19 (02):  .  Abstract ( 1687 )   Save In the light of more and more titanium alloy material being used to produce important components of spacecrafts and problems existing in traditional jointing process,a fully shielded welding equipment has been developed.The protection reliability is greatly relative to purity of inert gas in welding chamber.While using the economic and effective way by increasing the gas pressure of the welding chamber,which is used to maintain the purity of the inert gas,the chamber pressure becomes the focus to which we must pay attention.This paper analyses the behavior of inert gas pressure in the fully shielded welding chamber,the influences produced by welding operations upon the pressure of inert gas in the welding chamber are discussed,the measures which should be adopted to avoid conta minating the shielded environment in the welding chamber are pointed out. Related Articles | Metrics

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Design of Bit Parallel Reed Solomon Encoder Yu Wei Li Wen Ju Dehang (Xi'an Institute of Space Radio Technology,Xi'an 710000) 1999, 19 (02):  .  Abstract ( 1835 )   Save Reed Solomon (RS) codes,which have been adopted by several international standards,have found increasing application in such areas as satellite and mobile communications,data storage and transmission,video systems,etc.The development of efficient encoding scheme is thus of great importance especially for high speed applications. The dual basis is considered as the suitable basis for the RS encoder to operate over.This paper is concerned with the RS encoder over the extended dual basis.First,the method of obtaining the optimal dual basis is introduced and the optimal dual basis is calculated for the CCSDS RS code.Then,instead of the bit serial encoder,a bit parallel dual basis RS encoder is designed for high speed applications.The proposed RS encoder has the advantages of high throughput,low hardware requirements and is suitable for VLSI implementation. Related Articles | Metrics