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25 December 2003, Volume 23 Issue 06 Previous Issue    Next Issue

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Analysis on Mutant in Maize induced by Space Special Environment Zeng Mengqian Zengzhi Ji Hailian (Beijing Tianxing Space Breeding Technology R&D.Center,Beijing 100081) 2003, 23 (06):  .  Abstract ( 1785 )   Save In our previous paper it has been described that the space flight of maize seeds has significant influence on its photosynthetic pigment contents and young leaf ultrastructure (Zea mays L.).This paper deals with the different mutant types of space induced variation and their distribution in maize. Mutants obtained from Sp2(second generation by space treatment) to Sp3 show that amplitude of variability for space induced variations is large enough. Five type mutants for space induced variation are obtained,they are:1)Special high plant and dwarf plant mutants,resistance to B.maydis and E.turcicum all;2)Leaf-blade mutant;3)ear length mutant;4)multi-ear mutant;5)kernel type mutant.Eleven mutants are obtained,i.e.Mut1,Mut2,Mut3,Mut4,Mut5,Mut6,Mut7,Mut8,Mut9,Mut10,Mut11 etc.Mutant element probrem are discussed. Related Articles | Metrics

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The Minimal Parameter Solution for the Quaternion Differential Equation Liu Ruihua (College of ATM, Civil Aviation University of China, Tianjin 300300) 2003, 23 (06):  .  Abstract ( 1898 )   Save A new method of 3 rd order minimal parameter solution for the orthogonal matrix differential equation is modified and used to solve the quaternion differential equation, and the numerical simulation is done in the Strap-down Inertial Navigation System(SINS). The result shows that when the new algorithm is used, the precision of the solved attitude angle is about 3 to 5 times higher than that by using the classical method, but the floating-point operations is only about half of the old one. So it is an important method to improve the precision of SINS. Related Articles | Metrics

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The Bayes Analysis for Liquid Rocket Engine Performance Reliability Liu Qi Feng Jing Zhou Jinglun (Systems Engineering Institute, National University of Defence Technology, Changsha 410073) 2003, 23 (06):  .  Abstract ( 1836 )   Save Based on the condition that the performance test data of liquid rocket engine is subject to normal distribution with constant standard deviation, the Bayes method is used to analyze the environment factor of ground and space performance test. First, according to the history test data and expert's information, the prior distribution of environment factor is presented. Then, combined with limited space test data, the Bayes formula is used to calculate the environment factor. Finally,the method for performance reliability analysis under space test environment is presented. An example is given to illustrate the validity of this method. Related Articles | Metrics

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Study on Human Errors in Manned Space Flight and Their Solution Zhou Qianxiang Jing Zhongliang (Institute of Aerospace Information and Control, Shanghai Jiao Tong Unversity, Shanghai 200030) Jiang Shizhong (Institute of Space Medico-Engineering, Beijing 100094) 2003, 23 (06):  .  Abstract ( 1854 )   Save In this paper, fault which result in human errors in manned space flight are divided into three categories: the design defect of man-machine interface, astronaut's operation errors and system assembiling errors. On the basis, some methods to prevent human errors are expounded in detail. Finally, some points of view are put forward for discussion. Related Articles | Metrics

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Analysis of Meteoroids and Space Debris Environment and Risk for Spacecraft in LEO Zhang Wei * Huang Wenbo ** Guan Gongshun * Pang Baojun * (*Harbin Institute of Technology,Harbin 150001) (**Mudanjiang Oil Refinery, Mudanjiang 157000) 2003, 23 (06):  .  Abstract ( 1803 )   Save High-velocity impacts of the micro-meteoriods and space debris threaten the safety operation of the long life and large size spacecraft,that can in turn lead to significant damage and catastrophic failure.Inorder to investigate the risk of spacecraft operation in LEO,the meteoroids and space debris environment are analyzed in this paper The probability distribution of impact incident angle is obtained,the effect of shielding of the meteoroids by the earth is also be taken into consideration.Then the program of risk analysis is developed,taking the cylindrical spacecraft in LEO as an example,the risk analysis is performed for single bumper structure. The analysis result is presented Related Articles | Metrics

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Research on Model Reduction of Flexible Spacecraft Using Modal Cost Xu Xiaosheng Yu Dengyun Qu Guangji (Chinese Academy of Space Technology, Beijing 100086) 2003, 23 (06):  .  Abstract ( 1559 )   Save Modal Cost Analysis (MCA) is an important method of model reduction, which unifies the essential characters of the models and the requirements of control systems and the disturbances. The general formulation of MCA is presented . Then MCA is applied to the model reduction of flexible spacecrafts. Finally an numerical example is illustrated to indicate the efficiency of MCA. Related Articles | Metrics

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The LOS Measurement Error Modeling of Space Early Warning System Zhang Ping Tong Li Wu Yi Yi Dongyun (National University of Defense Technology, Changsha 410073) 2003, 23 (06):  .  Abstract ( 1904 )   Save As a kind of space-based measurement system, because of the inaccuracy of datum mark and the influence of correlated factors, big LOS error exits in the measurement data. Firstly the error soures of the system are divided into two types: the early warning satellite orientation and infrared sensosrs revise. Then analyze the error reasons concretely, construct the submodel. Finally based on the child error model, construct the integrate system error model, and the model is verified by simulation. Related Articles | Metrics

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Robot Assisted Teleoperation of Space Scientific Experiment Chou Wusheng Meng Cai (Robotics Institute, Beijing University of Aeronautics and Astronantics, Beijing 100083) Chen Jianxin Li Cheng (Beijing Institute of Control Engineering, Beijing 100080) 2003, 23 (06):  .  Abstract ( 1659 )   Save A telerobotic system is set up for the simulation of the operation of experiment space in cabin. The negative effect of time delay is overcome by using predictive display based on virtual reality. Virtual environment is calibrated by superimposing the real video over virtual display to improve the accuracy of the predictive display. Combining the master-slave mode and autonomous mode with the global and local vision, the operator can interactively control the virtual robot and the real robotic system by space mouse and successfully perform the task of changing the material rod of crystal growth stove. Related Articles | Metrics

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Error-Control Coding Schemes for Ka-Band Satellite ATM Systems Yang Hongming Cao Zhigang (Tsinghua University, Beijing 100084) 2003, 23 (06):  .  Abstract ( 1642 )   Save Ka-band communication is a hot topic in satellite communications, and the satellite ATM technology represents the research trends of wideband digital satellite communication networks. This paper studied the schemes of error-control coding in Ka-band satellite ATM systems. At first, we analyzed the characteristics of satellite communication systems and their impacts on the transfer of ATM cells, and then presented some simulation results about the cell loss ratio (CLR) under burst-error circumstances. To resolve the problem of high CLR, six kinds of error-control coding schemes are discussed and compared according to the property of Ka-band satellite communications. Among them, CASI/ALA and RM-Turbo schemes are better candidates. Related Articles | Metrics

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Research on Leakage Theory of Dual Sealing Structure and Application Liu Yang Cui Zhanpeng Sun Chong Liu Xiquan (Beijing Special Engineering Design Institute, Beijing 100028) 2003, 23 (06):  .  Abstract ( 1747 )   Save The mathematical model of dual sealing structure system is formulated. The conclusions of the relationship of the leakage rate, amount of leakage and time, and their influence factors are disclosed by theoretical analysis and numerical computation. These research results can be used as a guiding principle in design, leakage detection and leakage safety evaluation of the dual sealing system, to direct practice. Related Articles | Metrics

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Simulation of Sensor Failure Detection Using BP Neural Network Qiu Hao Wang Daobo Zhang Huanchun (Nanjing University of Aeronautics and Astronautics, Nanjing 210016) 2003, 23 (06):  .  Abstract ( 1681 )   Save This paper put forward a new extended Back-Propagation neural network based on the standard Back-Propagation neural network, which can get rid of the shortcoming of slow convergence speed and is easy to enter local maximum. A structure of a main neural network (MNN) and three decentralized neural networks (DNN) are designed. The parameter estimations are given by on-line learning of neural network. The fault can be fount out by comparing the estimators to the actual data acquired by sensors, and the examples of simulation are given. Related Articles | Metrics