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25 August 1999, Volume 19 Issue 04 Previous Issue    Next Issue

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Hill Guidance Error in Rendezvous and Docking Zhou Di Mu Chundi( Tsinghua University, Beijing 100084) 1999, 19 (04):  .  Abstract ( 1982 )   Save In the autom atic hom ing phase ofautom ated rendezvous and docking, theaccuracy of Hillguidance is concerned w ith severalerror factors. The error factors consid ered here are navigation and actuation errors. Basic analytic form ulas correlating targetingerror to navigation error and actuation error are given. Based on the form ulas, how to de sign a rendezvous trajectory to reduce the influence ofthe error factors on term inaltarget ing accuracy is studied. Fora typical V bar approaching path, sim ulation results are pre sented. The results in this paper also suit R bar approaching path. Related Articles | Metrics

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Num erical Study of Ventilation and Heat Transferunder Micro-gravity Environment Wu Qungang Liang Xingang Guo Zengyuan Ren Jianxun( Tsinghua University, Beijing 100084) 1999, 19 (04):  .  Abstract ( 1779 )   Save In order to sim ulate the airflow and heattransfer in a space station cabin,num erical analyses of heat transfer and ventilation in a com plicated cabin under m icro gravity environm entare carried outin w hich cases w ith slotair inletatthe top corners andoutletin thebottom corners arediscussed. Fourrepresentative casesw hich are em pty cabinand cabins w ith adiabatic/isotherm alobstacles are studied. The num ericalresults ofheattransfer and ventilation under various m odel scales in each configuration are elucidated. The research enunciates that shot inlet is m ore effective to suppress natural convection. Even for com plicated configuration problem s, naturalconvection can be dram atically de pressed w hen the m odelsize is properly reduced. How everthe concrete m odelsize com pa ratively depends on the given configuration. As far as the slot inlet ofventilation is con cerned, the appropriate m odelscale can be chosen as 1v5 in engineering applications. Related Articles | Metrics

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Implem entation of R S Code with FPGA Yu Wei Li Wen Ju Dehang( Xi'an Institute of Space Radio Technology, Xi'an 710000) 1999, 19 (04):  .  Abstract ( 1623 )   Save A high speed Reed Solom on ( R S) encoder prototype is im plem ented w ith F P G A ( Field Program m able Gate Array). Som e key points in the design ofthe R Sencoderhardw are are discussed. The results obtained by test and tim ing sim ulation show that thethroughput of the prototype can be up to 200 Mbit/s. Related Articles | Metrics

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Diagnosis Approaches for Abrupt Faultsof Tracking and Telem etry System Hu Feng Sun Guoji( System Engineering Institute, Xi'an Jiaotong University, Xi'an 710049) 1999, 19 (04):  .  Abstract ( 1858 )   Save Itis im portantto detect and diagnose allkinds ofabruptfaultcom ing fromtracking and telem etry system . Based on fault tolerance techniques, three new approachesare given in this paper. One is a fault tolerance sm oother w ithoutm odeling, the second isa fault tolerance estim ator based on m odelfitting and the third is a bounded filter underthe state space m odel. These new approaches can be used notonly after the eventbut alsoon line or on tim e. Sim ulation show s thatthese new approaches can detectisolated faultsw ith 100% accuracy and diagnose correlative faults very efficiently. Related Articles | Metrics

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Analysis of the Orbitand its Form ation of Adjoint Satellite for Space Station Luo Jianjun Yuan Jianping( Northw estern Polytechnic University, Xi'an 710072) 1999, 19 (04):  .  Abstract ( 1718 )   Save The space station adjoint satellite, w hich m oves Periodically around spacestation, is a spacecraft providing specialservice for space station. The conceptofthe spacestation adjointsatelliteis described. The adjointorbitand its form ation ofthe spacestationadjointsatellite are analyzed. The form ation conditions ofan idealadjointorbitare presented. Related Articles | Metrics

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Theoretical Calculation of Molecular Flow Fieldfor the Concave Hem ispherical W ake Shield Facility Ma Shengge Da Daoan Zhang Dixin( Lanzhou Institute of Physics, Lanzhou 730000) 1999, 19 (04):  .  Abstract ( 1835 )   Save In this paper, the concave hem isphericalw ake shield facility ( C H W S F) isstudied w hich is in the state of steady, non uniform w ith the closed sphericaltheoreticalm odel. The distribution ofthe m olecularnum berdensity ofthe experim entalzone is calcu lated and the m ain effect factors are discussed. The result show s thatthe C H W S Fcan ob tain extrem e high vacuum levelw hose m olecular num ber density is about 108m - 3,the m aincontribution to the m olecular num ber density com es from the outgas ofthe C H W S F, andthe increasem ent of the coherent coefficient of the C H W S F can't effectively im prove thevacuum levelon occasion of absence ofgasload. Related Articles | Metrics

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Space Station Internal Com m unication System w ith the A T M Network Liu Qiang Zhang Zhongzhao Zhang Naitong( Harbin Institute of Technology, Com m unication Research Center, Harbin 150001) 1999, 19 (04):  .  Abstract ( 2131 )   Save First, the requirem ent of the space station is introduced. Based on this, the space stationinternalcom m unication system is constructed w ith the A T M netw ork and the A T M , M I L S T D 1553 B and I E E E802 4 netw orks analyzed in detail. At last,the sim ulation m odelis builtup using the sim ulation plat form and the results are given as the basis of the space station internalcom m unication system . Related Articles | Metrics

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Measurem ent of Spectral Em issivity of Ablators and Calculation of Total High Tem perature Em issivity Jiang Weihui Xiao Xingcheng Hu Xingfang( Shanghai Institute of Ceram ics, C A S, Shanghai200050) Wu Guoting( Beijing Institute of Spacecraft System Engineering, Beijing 100086) 1999, 19 (04):  .  Abstract ( 2144 )   Save Medium tem perature spectral em issivity of three kinds of ablators w erem easured by using radiom etry. The m ethod for com puting totalhigh tem perature em issivi ty ofthe ablators according to theirm edium tem perature spectralem issivity presented. Inaddition, a form ula w as derived to calculate totalem issivity on the basis of em issivity invarious ranges of w avelength. Related Articles | Metrics

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Mechanism of Degradation of Zn O Pigm ent Induced by Ultraviolet Irradiation in Vacuum Liu Chaofeng Wang Zhenhong Hu Xingfang( Shanghai Institute of Ceram ics, Chinese Academ y of Sciences, Shanghai 200050) 1999, 19 (04):  .  Abstract ( 1917 )   Save The degradation of Zn O caused by Ultraviolet irradiation in vacuum is studied in this pa per. The objective ofthis study to understand the degradation process in order to produce coatings that arem ore resistant to radiation dam age. The absorption of free carriers produced due to the change of photocon ductivity under the vacuum ultraviolet irradiation is discussed and analyzed. A degradation m echanism in Zn O is proposed in this paper. It can be related to the desorption ofchem isorbed oxyen. The desorption ofchem isorbed oxygen leads to the production of oxygen vacancies in Zn O w hich produce free electrons inconduction band. The degradation of optical properties of Zn O can be attribu ted to the absorption offreeelectrons in near infrared region. Related Articles | Metrics

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Portable Gas Leakage Monitor with Mass Spectrom eter and Film Technology Zhao Zhong Wang Rongzong Sun Tianhui( Lanzhou Institute of Physics, Lanzhou 730000) 1999, 19 (04):  .  Abstract ( 1821 )   Save The traditionalgas leak detecting m ethods alw ays adopt single m ethod or M S/ G Ctechnique. The instrum ents are bulky and it's difficultto operate them . With therapid developm ent of m odern industry, m onitors w ith sm all size and lightw eight are ingreatneed. In addition,the m onitors m usthave high sensitivity,strong differentiate abilityand excellent security. Com bined the m ass spectrom eter and sensitive thin film together,m anufacture and perform ance is discussed experim entofthe portable gas leak m onitor. Itsapplications in spaceflightare introduced also. Related Articles | Metrics

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Research of Shield Structure w ith the Oblique Impact Ma Wenlai Pang Baojun Zhang Wei Zhang Zehua( Harbin Institute of Technology, Harbin 150001) 1999, 19 (04):  .  Abstract ( 1748 )   Save In this paper, characteristics of the oblique im pactofcylindricalprojectileonto L Y12 alum inum Whipple shielding Conceptw ithin the firstdoorsillvalue are studiedw ith an exam ple of Whipple shield structure through experim ental investigation. So, Shielding Concept dam age behaviors w ith projectile velocity and different im pact angle ofincidence are presented. There exists a criticalangle ofincidence w ithin the first doorsillvalue ofoblique im pact. In the condition ofangle ofincidence m ore than thatofthe criticalangle, projectile ricochet debris clouds are. Oblique im pacthas the characteristic thatcanbreak up energy. It is the advantage of the shield structure. Related Articles | Metrics

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Whole Field Deform ation Measurem ent Techniquefor a Satellite Antenna in Heat-Vacuum Testing Zhao Yang Wu Xiaoping( University of Science and Technology of China, Hefei230026) Li Liqiang( Beijing Institute of Satellite Environm ent Engineering, Beijing 100029) 1999, 19 (04):  .  Abstract ( 2607 )   Save The heat deform ations of a real satellite antenna m ust be detected inground. A sim ulative testing on a sm allm odelof antenna using Electron Speckle Pattern Interferom er is reported. The w hole field dynam ic deform ation caused by heatis obtainedw ithoutspecialvibration isolation. The results show that it is possible thatthe E S P Iandthe inform ation treatm ent m ethods are used for realtim e m easure of a realsatellite anten na. Related Articles | Metrics