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25 August 2007, Volume 27 Issue 04 Previous Issue    Next Issue

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Dynamic-Measurement System Modeling of Spinning Spacecraft Attitude and Their Applications Hu Shaolin1,2 Chen Rushan1 Karl Meinke2 Huajiang Ouyang3(1 Nanjing University of Science &Technology,Nanjing 210094)(2 Sweden Royal Institute of Technology)(3 University of Liverpool) 2007, 27 (04):  1-6+20.  Abstract ( 2066 )   Save The modeling analysis technique is one of the most important approaches in space-flight mission.Based on the dynamical analysis,the copling models of the attitudes with angle velocities were successfully decoupled into two series independently differential equations.And,these two series models were integrated into an extended dynamic-measurement system with joint relationship equations. This new integrated model could be widely used in attitude determination,attitude control and attitude monitoring of the spinning spacecraft.Based on this integrated model,a series of practical algorithms were described to estimate attitude as well as spinning angles velocities with high precision. Related Articles | Metrics

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Investigation of Relative Orbit Determination Method for Tracking a Space Non-cooperative Target Che Rucai Zhang Honghua(Beijing Institute of Control Engineering,Beijing 100080) 2007, 27 (04):  7-13.  Abstract ( 1672 )   Save Firstly,the relative motion equation between the chaser and the non-cooperative target was presented in the form of orbit elements difference.Secondly,based on the measurement equations,a novel relative orbit determination method was proposed using two step estimation.The effectiveness of the proposed method was verified by the simulated experiment. Related Articles | Metrics

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Analysis of Unsaturated Heat and Mass Transfer in Porous Wick of CPL Evaporator based on Field Synergy Principle Huang Xiaoming Liu Wei(Huazhong University of Science and Technology School of Energy and Power Engineering,Wuhan 430074) 2007, 27 (04):  14-20.  Abstract ( 1952 )   Save The unsaturated heat and mass transfer characteristics in the porous wick of a CPL evaporator under different geometrical structures and heat flux have been numerically studied based on the field synergy principle.The calculation results indicated that the heat flux and geometrical structures,such as fin width and wick height,exerted great influence on the heat transfer of a CPL evaporator.It demonstrates that the field synergy principle can be applied to optimize the configuration of the evaporator and consequently to enhance the heat transfer in a CPL evaporator. Related Articles | Metrics

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Impact of Fin Parameters on Heat Rejection Performance of the Radiator of Straight Fins-Tube Ren Depeng Jia Yang Liu Qiang(China Academy of Space Technology,Beijing 100094) 2007, 27 (04):  21-27.  Abstract ( 1911 )   Save Radiation heat transfer between fins and tube wall of the radiator of straight fins-tube was calculated by Monte Carlo Method.The impact of quantity of fin,fin height,fin thickness and the temperature of tube wall on heat rejection performance of the radiator under the first boundary condition were analyzed by numerical simulation.The analysis shows that,under a certain fin mass,there is an optimum quantity of fin and fin height to get the highest heat rejection efficiency.Fixed the fin shape,adding the fin thickness is not an effective way to increase the efficiency.The heat rejection efficiency of the fin is decreased with the temperature of tube wall decreasing,and the necessity of fitting fin is reduced when the wall temperature is higher. Related Articles | Metrics

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Study on the Improved ACA-based Parameters Optimization of NLPID Controller for Flight Simulator Duan Haibin1 Wang Daobo2 Yu Xiufen3(1 Beijing University of Aeronautics and Astronautics,Beijing 100083)(2 Nanjing University of Aeronautics and Astronautics,Nanjing 210016)(3 Center for Space Science and Applied Research,Chinese Academy of Sciences, Beijing 100080) 2007, 27 (04):  28-33+43.  Abstract ( 2115 )   Save A novel NLPID optimization strategy for flight simulator was proposed.In order to enhance the global convergence performance of ACA,the basic ACA was improved by using meeting search strategy and trail decay coefficient self-adaptive adjusting ideology.Furthermore,an improved ACA-based NLPID parameters optimization structure for flight simulator was designed.ITAE performance criteria was adopted in the improved ACA.Finally,the optimized parameters using improved ACA were applied to a high performance flight simulator.The experimental results demonstrate that the NLPID controller has strong robustness against noise.This proposed ACA-based HLPID parameters optimization strategy can also be used to develope other simulation servo system′controllers. Related Articles | Metrics

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Probability Design Method of Margins of Safty for Reliability Characteristic Parameters of Space Mechanical Products Liu Zhiquan(China Academy of Space Technology,Beijing 100094) 2007, 27 (04):  34-43.  Abstract ( 1957 )   Save Quantitative relations among reliability requirments,margin coefficients and designed values of characteristic parameters were established.Probability design methods of MOS for mechanism transmissions,structure seals,structure thermal protections and pyrotechnic connecting/unlocking devices were respectively discussed.The work offers a technical approach for quantitative reliability design of space mechanical products. Related Articles | Metrics

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Heat Transfer of Air Forced Convection with Dropping Atmosphere Pressure in Manned Spacecraft Cabin Fu Shiming Pan Zengfu(China Academy of Space Technology,Beijing 100094) 2007, 27 (04):  44-47.  Abstract ( 1882 )   Save To estimate the capability of air forced convention heat transfer in thermal control of large manned spacecraft,the principle of air flow parameters and physical properties varying with the dropping pressure was studied.The relationship between the atmosphere pressure and the coefficient of air forced convection heat transfer in the empirical and practical relations was pressented,and a numerical example was provided to prove this relationship.The results indicate the heat transfer capability of air forced convection decreased with the atmosphere pressure in the cabin of manned spacecraft dropping,and the air forced convection contributed little to the equipment heat dissipation when the pressure was lower than 3.04×104Pa. Related Articles | Metrics

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Heat Transfer Efficiency of Cylindrical Space Radiators with Fluid Loop Zhang Ningli Jiang Jun(China Academy of Space Technology,Beijing 100094) 2007, 27 (04):  48-52.  Abstract ( 1699 )   Save A simple analytic formula for estimating the heat transfer efficiency of cylindrical space radiators with fluid loops was presented.It was found that the deviation between the results calculated by the formula and that obtained by numerical simulation was less than 5%.So,the hypothesis that inlet temperature Tfi substitutes for the mean temperature Tm is acceptable in engineering. Related Articles | Metrics

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Exact Fiducial and Bayesian Interval Estimation of Behrens-Fisher's Problem Zhou Yuanquan(Beijing Institute of Structure and Environment Engineering,Beijing 100076)Li Baosheng(Beijing Aerospace Propulsion Institute,Beijing 100076) 2007, 27 (04):  53-56+65.  Abstract ( 2309 )   Save The interval estimation of the difference of two sample's mean in normal populations has been studied.The exact fiducial and the exact Bayesian interval estimation,taking conjugate and noinformative prior,of Behrens-Fisher problem are presented.The computation method is discussed and illustrated. Related Articles | Metrics

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Research on SEU Mitigation of FPGA Based-on SRAM Huang Ying Zhang Chunyuan Liu Dong(School of Computer Science,National University of Defense Technology,Changsha 410073) 2007, 27 (04):  57-65.  Abstract ( 2537 )   Save A new method to mitigate SEU on FPGA based-on SRAM,named DMRC,was proposed by analyzing the influences of SEU on FPGA based-on SRAM and comparing with several common mitigation techniques: Scrubbing、ECC and TMR.By validation baced-on simulation software of On-Borad FPGA,it was proved that the new method mitigating SEU on the 64-taps LFSR saved 92% redundant logic elements and shortened 26% additional delay comparing with hardware-based TMR.Thus,the method reduced greatly the cost of fault-toletant design. Related Articles | Metrics

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Genetic Algorithm PID Self-tuning based on the Satellite Attitude Control Li Yuan1 Wu Hongyue2 Wu Jie3(1 China Academy of Space Technology,Beijing 100094)(2 China Ship Research and Development Academy,Beijing 100085)(3 Beijing Changcheng Institute of Metrology and Measurement,Beijing 100095) 2007, 27 (04):  66-71.  Abstract ( 2401 )   Save The satellite attitude dynamics equations considering satellite payload were set up for a new generation of earth resource satellite.The satellite attitude was controlled by using genetic algorithm PID self-tuning method.The method effectively elminated the influence of rotatable payloads on satellite attitude.Simulation results show that the control performance of the satellite attitude system is improved,and the difficulties of traditional PID parameter regulation can be avoided by this method. Related Articles | Metrics