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25 February 1994, Volume 14 Issue 01 Previous Issue    Next Issue

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A SPATIAL SPECTRUM ESTIMATION ALGORITHM BASED ON ONE-DIMENSION NOISE SUB-SPACE Luo Lichun(China Electronic Equipment System Engineering Company, Beijing100083) 1994, 14 (01):  .  Abstract ( 1962 )   Save A new spatial spectrum estimation algorithm is presented.The basic idea of the algorithm is that only the smallest eigenvalue of R is a noise eigenyalue and so is the eigenvector.So the dimension of noise space is always one.The accuracy and the resolution.of estimation of DOA by the use of the new algorithm are higher than those from MUSIC in the actual condition that some energy of signals eigenvalues leak to noise eigenvalues.The new concept can also be used to modify other spatial spectrum estimation algorithms such as spatial smooth algorithm used for dealing with coherent sources. Related Articles | Metrics

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PERFORMANCE AND APPLICATION OF FLEXIBLE CONDUCTIVE TYPE SECONDARY SURFACE MIRROR WITH KAPTON SUBSTRATE Lu Yusun(Lanzhou Institute of Physics,Lanzhou730000)Jiang Jingshan;Chen Guozhen(Beijing Institute of Spacecraft System Engineering, Beijing100086) 1994, 14 (01):  .  Abstract ( 1748 )   Save The preparation of the conductive secondary surface mirror with flexible Kapton substrate has been briefly discussed in this paper.The structure of multilayer insulation and the grounding method have also been illustrated. The measured data show f that te solar absorptivity and emittance of the SSM coated TO film are almost not changed. So the TO film on SSM surface will have no influence on its performance of thermal control.According to the application of multilayer structure on satellite and in order to compare the difference of controlling chargingperformance,the conductive and non-conductive type SSM have been used on outside of the structure for test.In simulated substorm environment the test results of seven samples indicate that the antistatic perfo rmance of SSM With To film is excellent compared with uncoated TO film SSM. When the sample with TO film is grounded, its surface potential. can be controlled below 100 volts and the discharging phenomena on surface are also repressed effectually.The experiment proves that the surface modification in combination with the grounding technology can provide the best effect on preventing satellite surface from charging/discharging. Related Articles | Metrics

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ON EFFECT OF PHASE QUANTIZATION UPON PEAK SIDELOBE LEVEL IN PHASEDARRAY ANTENNAS Gao Tie;Li Jianxin;Guo Yanchang(Nanjing Research Institute of Elec.Tech,Nanjing210013) 1994, 14 (01):  .  Abstract ( 1897 )   Save In this paper,tile peak sidelobe degradation due to the phase quantization in scanning phased array antenna is described.Several computation formulas used to estimate the peak sidelobe level degradation are given.It is shown that the theoretical analysis are in good agreement with the simulated computation results. Related Articles | Metrics

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A RESEARCH ON APPLICATION OF VIDEO IMAGE REDUCTION TECHNIQUE Deng Guanglin;Ji Zaogen;Dong Shuhong(Beijing Satellite Station,Beijing 100094) 1994, 14 (01):  .  Abstract ( 1823 )   Save Video image reduction technique is the important problem of multimedia system. The article is divided into two parts:①Study on trans formation coding,motion compensation, quantization and variable length entropy coding.②The computer analysis of real-time transmission videoimage.The experiences were summed up and the suggestions were made at the end of this paper. Related Articles | Metrics

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INFORMATION PROCESSING AND ANALYSIS OF SPACE IMAGING SPECTROMETRY Zhang Fu(Shanghai Shiner Optoelectronics Company,Shanghai Institute of Mechanical Engineering, Shanghai 200093) 1994, 14 (01):  .  Abstract ( 1536 )   Save Information processing and analysis are two important steps relating to finally acquired surface object recognition results in space imaging spectrometry.According to the flow of information processing,this Paper describes some key techniques,such as archiving processing,data compression, retrieval processing, radiometric and geometric correction etc.;and on the basis of remarking image restoration and enhancement processing and multispectral data information analysis methods, the techniques of artificial visual interpretation and computer analysis interpretation for imaging spectrum data are also studied and discussed. Related Articles | Metrics

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ON SUMMARY OF APPLICATION OF PLATELET INJECTORS TO ENGINES FOR SPACECRAFT Shi Shaoping;Lu Zhenglin;Zhuang Fengchen(National University of Defense Technology,Changsha 410073) 1994, 14 (01):  .  Abstract ( 1863 )   Save In this paper,summarize the application of platelet injectors in liquid propellant engines for spacecraft. Attention is focused on the performance and usefulness of platelet injectors used in space shuttle orbital maneuvering engines,small thrust attitude control engines and gas generators which are higher than those of conventional ones.Analyses are also made on the effect of platelet injectors used in small thrust liquid engines on decreasing exhaust plume contamination. Finally, the tasks are gi yen for further studying and desinging platelet injector. Related Articles | Metrics

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SELECTING ALTITUDE OF COMBUSTION INITIATION AND EVALUATING ATTENUATION EFFECT FOR IMPACT ATTENUATION ROCKET Li Dayao(Beijing Institute of Space Machine and Electricity,Beijing 100076) 1994, 14 (01):  .  Abstract ( 1896 )   Save The solutions of recoverable vehicle-parachute system motion equations during the work period of an impact attenuation rocket are given in the general form first.Then,according to the solutions, all factors which influence the altitude of combustion initiation and the attenuation effect for the impact attenuation rocket are analyzed.The formulas of calculating the altitude of combustion initiation and evaluating the attenuation effect are obtained. Related Articles | Metrics

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FIRE PREVENTION AND EXTINGUISHING TECHNOLOGY FOR MANNED SPACECRAFT Shen Xuefu(Institute of Space Medico-Engineering, Beijing100094) 1994, 14 (01):  .  Abstract ( 1929 )   Save his paper analyses the characteristic of firing and flaming simply,describes fire detectors for different fire condition and how to make decision properly about the kinds, number and distribution of fire detectors and build effective subsystem of fire detecting and warning. This paper also introduces three kinds of extinguishant which can be used for spacecraft, discusses how to suppress the fire and put it off,make postfire cleanup in spacecraft cabin.Howevcr in manned spacecraft the first thing we must do is how to prevent infrom firing.Finally,this paper introduces the fire detection and fire fighting system in foreign spacecraft. Related Articles | Metrics

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BURNOUT CHARACTERISTICS OF MICROWAVE GaAs POWER FET Yang Dequan;Yuan Zeliang;Ye Qingshan;Fan Chuizhen(Lanzhou Institute of Physics,Lanzhou 730000) 1994, 14 (01):  .  Abstract ( 2446 )   Save urnout characteristics of C band GaAs power MESFET are studied by-means of Scanning Auger Microprobe(SAM),Secondary Electron Microscope(SEM),Electron Probe Microarea Analysis (EPMA),X-ray Transmission Microscope,etc.in this paper. The burn out modes are suggested and discussed with the presentation of the associate distribution graph of failure rate and their surface topography. The results indicate that the source-drain burnout is the primary failure mode ill GaAs power BET, with the other failure modes including the“air-bridge”burnout,heat-spot burnout, and that caused by“thorn”at drain or source edge, defect and contamination“particle”in the chip and the imperfect during the process of material and device. The failure mechanisms are also discussed. Related Articles | Metrics

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CALCULATION FORMULAS FOR ELASTIC CONSTANTS OF M40 GRAPHITE FIBER/ EPOXY648 COMPOSITE MATERIAL Wo Xiyuan(Beijing Institute of Space Machine and Electricity,Beijing 100076) 1994, 14 (01):  .  Abstract ( 1674 )   Save he M40 graphite fiber/eposy 648 composite material is the main structural material of applied satellite in China recently.In this paper,the experimental data of this material are compared with the calculated results by means of various formulas and the formulas suitable for calculation of elastic constants of this material are suggested. Related Articles | Metrics

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PERFORMANCES FEATURES AND APPLIED RELIABILITY OF SATELLITE-USED CAPACITORS Peng Baoxia(Beijing Institute of Satellite Environmental Engineering,Beijing 100029)Xue Renjing(Beijing Institute of Control Engineering, Beijing 100080) 1994, 14 (01):  .  Abstract ( 1821 )   Save This paper presents the selection rules of satellite-used capacitors failure examples and the methods of raising applied reliability of tantalum capacitors.Four viewpoints are put forward:①Solid state tantalum capacitors should not he used in power supply filters;②The reliability of solid state tantalum capacitors is related to the serial resistance in a circuit;③Liquid state tantalum capacitors are susceptible to vibration, and it is possible to produce transient electric potential;④ There is low voltage failure in multi-lager ceramic capacitors.Finally by analysing the special failure phenomenon and mechanism of capacitors, some available screening methods are proposed. Related Articles | Metrics