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25 October 2005, Volume 25 Issue 05 Previous Issue    Next Issue

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Study on the Project Management Maturity Model of Shenzhou Spaceship Yuan Jiajun~(*) Ou Lixiong~(**) Wang Weidong~(*)(*China Academy of Space Technology,Beijing 100094)(**Northwestern Polytechnical University,Xi'an 710072) 2005, 25 (05):  1-9.  Abstract ( 1879 )   Save Based on the analysis of classical existing project management maturity models,(considering) the characteristics of Shenzhou spaceship programme and its related organization(environments),this paper proposes the Shenzhou spaceship project management maturity model(SZ-PMMM).This model includes two sub-models i.e.the enterprise-level organizationand(project-)level organization.The key areas such as "culture" are introduced into the SZ-PMMM,(promoting) the conceptual meanings of project management maturity practically. Related Articles | Metrics

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Research on FPGA Fault-tolerant Method by ISP Partial Reconstruction Du Wenzhi(China Academy of Space Technology,Beijing 100094) 2005, 25 (05):  10-16+51.  Abstract ( 1967 )   Save A new fault-tolerant method by ISP partial reconstruction is proposed,which can obviously reduce the reconfiguration data.The principle,arithmetic and characteristics of the new fault-tolerant method are described.In order to remove obstacle in the implement of the new fault-tolerant method,a new de-coupling circuit design method is presented.The new fault-tolerant method was employed in the telecommand data processing circuit for deep space exploration,and the implement process was demonstrated through Flash FPGA. Related Articles | Metrics

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The Control Method and Control Algorithm for Homing and Closing Phases of Space Rendezvous Zhu Renzhang~* Tang Yi~(**) Meng Wei~*(*Beijing University of Aeronautics and Astronautics,Beijing 100083)(**China Academy of Space Technology,Beijing 100094) 2005, 25 (05):  17-23+39.  Abstract ( 1742 )   Save The control method and control algorithm for homing and closing phases of space rendezvous are investigated.The transfer(from one holding point to another) control uses the(terminal) control method,and the position keeping in the holding points applies the trajectory(control) principle.The control aim of impulse guidance is the terminal position,while the control aim of continuous thrust guidance is the terminal position and velocity.The simulation results show that the control method and algorithm are effectual. Related Articles | Metrics

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A Nonlinear Control of Formation Flying Based on Mean Elements Liu Shaoran Zeng Guoqiang(Institute of Command and Technology of Equipment,Beijing 101416) 2005, 25 (05):  24-28+61.  Abstract ( 1900 )   Save A nonlinear control law of satellites formation flying is presented,which feeds back traditional Cartesian position and velocity tracing errors.The tracing errors are required based on mean elements.The asymptotic stability of the feedback system is proved with Lyapunov method.A numerical simulation is given to show the control effect.The conclusion shows that it can be used to maintain the satellites formation precisely. Related Articles | Metrics

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The Error Estimate to the Single Circle Observation Data of Satellite Zhu Zhuanmin~* Qiu Hongxing~(**) Xu Zongben~*(*Mathematical College of Xi′an Jiaotong University,Xi′an 710049)(**Nanjing Zijinshan Astronomical Observatory of China Academy of Sciences,Nanjing 210008) 2005, 25 (05):  29-33.  Abstract ( 1790 )   Save Through building up an exact dynamics model of the object,a method based on the orbit precise determination and forecast to distinguish and eliminate the error is proposed.It gets(over) the limitation of the polynomial(imitate) method which distinguish the error by error effectively. Related Articles | Metrics

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Design and Application of Immunized State Observer Luan Jiahui Jiang Xingwei(Harbin Institute of Technology,Harbin 150001) 2005, 25 (05):  34-39.  Abstract ( 1862 )   Save A design of novel immunized state observer is proposed.The method divides the(system) into measurable and unmeasurable part.The measurable part can be obtained through(output) without using the contaminative dynamic equation and the unmeasurable part can be obtained by the uncontaminative dynamic equation.This method overcomes the defect of the general observer that is affected by fault when estimating state. Related Articles | Metrics

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Study on Radiation Property of Dual Reflector Antenna Fed by Phased Array Wang Yu Yan Lubin(China Academy of Space Technology,Beijing 100086) 2005, 25 (05):  40-45.  Abstract ( 1709 )   Save Using Fourier-Bessel technique and ray optics,the radiation field of the dual(reflector) antenna fed by a phased array is analyzed.Relationship between the performance((especially) the gain and scan loss characteristic) and the system parameters is studied and graphs are offered,as a reference. Related Articles | Metrics

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A Kind of Wavelet Image Coding Based on SPIHT Algorithm Chen Hongwei Zhang Huanchuan(College of Automation Engineering,Nanjing University of Aeronautics & Astronautics,Nanjing 210016)Huang Guojian(College of Electronics and Information,Jiangsu University of Science and Technology,Zhenjiang 212003) 2005, 25 (05):  46-51.  Abstract ( 1679 )   Save After the studying of image wavelet decomposing coefficients and SPIHT algorithm,a wavelet image coding algorithm is introduced based on SPIHT,which aims at solving the(redundance) problem existing in three link tables coding of SPIHT even processed by same mode.The algorithm adopt different coding mode according to different coefficients range in three link(table) LIP、LIS and LSP.When threshold value decrease,the number of significant coefficients with same quantization level increase greatly in four domain,the absolute values of coefficients are close to each other,so only the averages of these significant coefficients are saved in coding process.The experiment results of the algorithm are compared with SPIHT algorithm,and show that the(algorithm) is excelled in PSNR and bpp. Related Articles | Metrics

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The Dynamic Simulation of the Virtual Prototype of the Two-axes Position Mechanism for Satellite Antennas Li Changjiang(China Academy of Space Technology,Beijing 100086)Liao Ying Liao Chaowei Feng Xiangjun(Institute of Aerospace and Material Engineering,National University of Defense Technology,Changsha 410073) 2005, 25 (05):  52-56.  Abstract ( 1861 )   Save Firstly,the work principle of the two-axes position mechanism for(satellite) antennas is indicated.A solid model of the two-axes position mechanism is built based on the(analysis) and simplification to the system.Then,the method of building the virtual prototype model based on the solid model is brought forth.Finally,the simulation results and the deep-going(analyzing)(conclusions) are showed,which provided the useful suggestions to the optimal design of the physical prototype of the two-axes position mechanism for satellite antennas. Related Articles | Metrics

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A Novel Modeling Method of Suspension System Song Xumin Peng Yong Cheng Wenke Qin Zizeng(National University of Defense Technology,Changsha 410073) 2005, 25 (05):  57-61.  Abstract ( 1707 )   Save In view of the disadvantages of the present modeling methods for parachutes(suspension) systems,a novel method based on static equilibrium of the middle points is presented.The method is more universal,robust and efficiency than the present methods,and it has been used to simulate the recovery scenario of some parachute recovery systems successfully. Related Articles | Metrics

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One Sort of Finite Element Mesh Size Criteria for Structural High-frequency Random Response Analysis Wang Yueyu(China Academy of Space Technology,Beijing 100094) 2005, 25 (05):  62-65+71.  Abstract ( 1897 )   Save According to wave motion theory,finite element mesh size satisfying the needs of engineering calculating precision is relevant to the upper limit of frequency range of random(response) problems.A new criterion of finite element mesh size——one third mesh size criterion——is(presented) according to wave motion theory.Taking high-frequency acceleration response analysis of simple support square plate as an example,the contrast between NASTRAN numerical results and the closed form solution reveals the effectiveness of this criterion in the high frequency random(response) finite element analysis. Related Articles | Metrics

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Application of Immune Genetic Algorithm to the Optimal Thermal Design of Louvered Panels Zhang Weiqing Xuan Yimin Han Yuge(Nanjing University of Science and Technology,Nanjing 210094) 2005, 25 (05):  66-71.  Abstract ( 2320 )   Save To improve the thermal performance,based on the theory of heat transfer and(optimal) algorithm,a computational method is presented to optimize thermally louverd panels.(Considering) the particularity possessed by radiative energy transfer throughout the optimization of louvered panels,accelerating the optimal process,radiative energy transfer of louvered panels is(resolved) by the introduction of the relation between radiative transfer coefficient and angle factor,which only could be applied to the diffuse system.At the same time,to overcome the limitations(inherit) in traditional optimal algorithms,an immune genetic algorithm is developed,and in(addition),it is applied to the optimal thermal design of louvered panels.It reveals that,in contrast to standard genetic algorithm,the immune genetic algorithm performs better,in the aspects of search speed as well as global search ability.And it could be well applied to thermal design. Related Articles | Metrics