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    25 August 1998, Volume 18 Issue 04 Previous Issue    Next Issue
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    MODAL CONTROL METHOD AND OPTIMAL PLACEMENT OF ACTIVE MEMBERS IN SMART TRUSS STRUCTURES
    Sun Dongchang (Hebei University of Technology,Tianjin 300132) Wang Dajun (Peking University,Beijing 100871) Xu Zhongling (The University of Texas at Brownsville TX 78520 U.S.A)
    1998, 18 (04):  . 
    Abstract ( 1439 )   Save
    A modal control scheme for smart truss structures is presented which includes a designing method of the modal sensor,a designing method of the modal actuator as well as the independent modal space control method.A simple criteria of optimal placement of active members is also given.
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    ON CHARACTERISTICS OF MODAL ANALYSIS FOR FLEXIBLE APPENDAGE OF A TYPICAL RIGID FLEXIBLE COUPLING SYSTEM
    Xiao Shifu (Southwest Institute of Structure Mechanics,Chengdu 610003) Chen Bin (Peking University,Beijing 100871)
    1998, 18 (04):  . 
    Abstract ( 1487 )   Save
    This paper deals with modal analysis of the flexible appendage of a typical rigid flexible coupling system based on the method of continuum mechanics.The analytical and numerical results presented in the paper represent more comprehensive coupling characteristics for the small deformation modes of the flexible appendage and can be taken for a reference for comparing the computational accuracy with that of the various approximative methods using the discretization of the flexible elements of the flexible multibody system .
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    THERMAL ANALYSIS OF VACUUM CONCENTRIC TUBE ANNULUS
    Zhong Qi Xu Jiwan (Beijing Institute of Spacecraft System Engineering,Beijing 100086)
    1998, 18 (04):  . 
    Abstract ( 1660 )   Save
    Thermal behavior of vacuum concentric tube annulus is a process involving combined heat transfer mode,in which the thermal conduction of low pressure gas plays an important role.Accurate description is proposed for thermal radiation and gas conduction in the annulus under various heat insulation conditions and theoretic model is derived.With vacuum outgassing taken into acount,the equivalent conductivity of annulus is analyzed in detail.The method and technique employed is applicable to similar circumstances in the fields including space thermal physics.
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    NONLINEAR MODEL AND CONTROL FOR LARGE ANGLE RAPID MANEUVERING OF A FLEXIBLE SPACECRAFT
    Li Yong (Beijing Institute of Control Engineering,Beijing 100080)
    1998, 18 (04):  . 
    Abstract ( 1468 )   Save
    This paper is concerned with the dynamics and control for planar,large angle rapid slew maneuvering of a flexible multi body spacecraft,consisting of a rigid central body and a flexible beam.Nonlinear infinite dimensional model of the system is derived by employing the Hamilton's principle.By using the measurements of the attitude angle of the rigid central body and its velocity only,a kind of linear feedback control law is presented.Based upon LaSalle's invariance principle,it is shown that the implementation of the control algorithm results in asymptotic stability of the closed loop system.
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    MODEL BASED DIAGNOSIS USING QUALITATIVE MODEL AND POLYNOMIAL ALGORITHM
    Yu Baisheng Huang Wenhu Wang Wei (Harbin Institute of Technology,Harbin 150001)
    1998, 18 (04):  . 
    Abstract ( 1729 )   Save
    In the model based diagnosis method,Reiter proposed firstly a method to calculate diagnosis from first principle,but it is difficult toapply to the complex physical domain.Afterward,Mikito Iwamasa et.al.presented a model based diagnosis using qualitative causal model and set covering,Which is improved greatly,but set covering calculating is complicated and needs long time.In the paper,a model based diagnosis using qualitative causal model and polynomial algorithm is presented,which has less computation burden and the correctness of this new algorithm is proved.
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    COHERENT INTERFERENCE SUPPRESSION AND MUTUAL COUPLING COMPENSATION IN ADAPTIVE CIRCULAR ARRAY
    Yang Chao (Southwest China Research Institute of Electronic Equipment,Chengdu 610036)
    1998, 18 (04):  . 
    Abstract ( 1801 )   Save
    The mechanism of the performance degradation due to coherent interference and mutual coupling between elements in conventional adaptive arrays is investigated based on decorrelating the incoming coherent interference signals and modifying the weight vector of conventional adaptive antennas,a technique of coherent interferences suppression and mutual coupling compensation in adaptive circular array is proposed.Theoretical analysis and computer simulation results prove that the technique is correct and easy to be implemented without adding any hardwares.
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    COST ESTIMATION OF SMALLSATS
    Zhu Yilin (Chinese Academy of Space Technology,Beijing 100081)
    1998, 18 (04):  . 
    Abstract ( 1925 )   Save
    Most of the CERs(Cost Estimation relationship)available for satellites have been unsuited for smallsats,with the estimated costs being much higher than the actual ones,because of great reduction of the smallsat costs.The paper describes the SSCM (Small Satellite Cost Model) of CER derived on the basis of the history data of the costs of 29 small satellites developed and launched in recent years and gives a calculated example,in which the unit of cost is converted into yuan (RMB).Finally,some CERs with two independent variables are given.
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    PERFORMANCE OF SATELLITE BORNE ScanSAR
    Yuan Xiaokang (Shanghai Institute of Satellite Engineering,Shanghai 200240)
    1998, 18 (04):  . 
    Abstract ( 1776 )   Save
    In this paper,the properties of scanning coverage for a satellite borne ScanSAR have been analyzed in detail.It is shown that the maximun width of observing zone for a satellite borne ScanSAR is independent of radar wavelength and real shape of antenna aperture if the restraint conditions for far range ambiguity are met in design.The antenna design shall be trade off between allowable size and beam number.The average and peak transmitting power of satellite borne ScanSAR and quantitative relationship of restraint condition of ambiguity are explained.The numerical examples about performance computation of a satelliee borne ScanSAR are given finally.
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    A NEW CONDUCTIVE THERMAL CONTROL MATERIAL WITH KAPTON SUBSTRATE FOR SATELLITE
    Lu Yusun Feng Yudong Zhai Houming (Lanzhou Institute of Physics,Lanzhou 730000)
    1998, 18 (04):  . 
    Abstract ( 1647 )   Save
    In this article,a new conductive thermal control material with Kapton substrate has been described.Its conductive coating is TO (Tin Oxide) film.The TO film has an excellent transmittance in the visual and near infrared range and its surface resistance is from10 4 to 10 6Ω.After being UV radiated for 8200h,the solar absorbance α s of the TO/Kapton/Al thermal control material displays a little change and its relative change Δ α s/α s is 6 7%.After the TO/Kapton and Kapton was radiated for 8000 hours in UV radiation,the results indicate that the TO film has the ability to resist UV radiation.It is shown that our TO films deposited in special deposition condition have an ability to resist UV radiation.After cycling 100 times from -196℃ to +100℃,the change of α s can be neglected and R s increases to about double the past value.The sample had been put down for 24h under R H >95%、(50±2)℃,the film of Al and TO has no change and is not peeled off the Kapton.These results thoroughly indicate that the new thermal control materials have the excellent environmental stability.At the end of the paper,the measurements of uniformity of α s on a product with a width of 0 5m and a length of 6m have been given.
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    DYNAMIC COMPARISON METHODS FOR CALIBRATING LEAK RATE OF PRESSURE LEAKS
    Meng Yang Zhang Dixin Lü Shiliang Gong Yueli (Lanzhou Institute of Physics,Lanzhou 730000)
    1998, 18 (04):  . 
    Abstract ( 2086 )   Save
    In the paper,two dynamic comparison methods were introduced.The me thods can be used to calibrate the leak rate from 1×10 -4 to 1×10 -7 Pa·m 3/s with the lower pressure of leak being atmospheric pressure.In dynamic comparison method with reference leak,firstly,test gas through unknown leak or reference leak was accumulated for different times to increase about the same quantity in a vessel which was filled with atmosphere.Secondly the mixed gas was expanded.Thirdly the expanded gas was introduced to a dynamic flow system and the dynamic balance partial pressure of test gas was measured and compared.In dynamic comparison method with quantitative gas,the quantitative gas takes the place of the accumulated test gas through reference leak.
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    STUDY AND APPLICATION OF FREQUENCY PREMIUM ANALYSIS FOR FOCUSING OF VISSR OF THE GEOSTATIONARY METEOROLOGICAL SATELLITE ON ORBIT
    Wei Caiying Jin Chunping (National Satellite Meteorological Center,Beijing 100081) Chen Jun (Beijing Institute of Satellite Information Engineering,Beijing 100080)
    1998, 18 (04):  . 
    Abstract ( 1696 )   Save
    By using Fourier analysis method to decide how to focus satellite radiometer on orbit quickly and accurately,decide to focus forward or backward and the steps of control command if focus is necessary.It prevents focusing so much along a direction that destroy radiometer forever.The 2 D frequency premium analysis method provided first time in this paper can be used also correctly even the position of image is not accurate,we can also get good result.
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    ATTENTION POINTS ON LINEAR CHARGE COUPLED DEVICE USED IN ON BOARD CAMERA
    Liu Fuan (Xi'an Institute of Space Radio Technology,Xi'an 710000) Cao Haiyi (Beijing Institute of Spacecraft System Engineering,Beijing 100086) Ye Peijian (Chinese Academy of Space Technology,Beijing 100081)
    1998, 18 (04):  . 
    Abstract ( 1973 )   Save
    The reliability and the ability of anti irradiation of CCD is concerned in the lifetime of CCD camera.The drive method and the restrain method of output DC level are concerned in whether or not the capacity of CCD is made well.In this paper use the data acquired from the speeding up lifetime test,estimating the reliability of CCD,analyzing the influence of high energy irradiation on CCD device.On the other hand,analyse the analogy and digital drive,compare the two methods of restraining output DC level and raise an anti electrostatic method.
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