Loading...

Table of Content

    25 August 2010, Volume 30 Issue 04 Previous Issue    Next Issue
    For Selected: Toggle Thumbnails
    Initial Orbit Determination with Space-based Angle Measurements Based on General Regularization Least Squares Estimation
    LIU Guang-Ming, LIAO Ying, CHEN Zhong-Gui
    2010, 30 (04):  1-8. 
    Abstract ( 2796 )   Save
    The main deficiencies of the traditional initial orbit determination with space-based angle measurements are due to that the systematic error observation data and the coefficient matrix is ill-posed or singular. Based on the analyses,the semi-parametric regression model of observation equations was established. The general regularization least squares estimation method based on penalized least squares estimation and ridge estimation was deduced,and the correlative characteristics of the method was proved. To improve the calculating efficiency,the column pivot element Givens-QR decomposition algorithm was introduced. Experimental computation indicates that the method is effective in achieving a satisfying result.
    Related Articles | Metrics
    Information Fusion and Localization for Wireless Multisensor Based on Optimal Geometrical Topology
    Yu Xiaolei1,2 Sun Yongrong1 Zeng Qinghua1 Liu Jianye1 (1 Navigation Research Center,Nanjing University of Aeronautics and Astronautics,Nanjing 210016) (2 Institute of Technology,Research & Innovation,Deakin University,Australia Vic 3217)
    2010, 30 (04):  9-15+22. 
    Abstract ( 2746 )   Save
    Considering the validity of received data,a novel information infusion and localization technology was presented for wireless multisensor based on optimal geometrical topology theory. The optimal sensor-target geometrical localization and topological characteristics were studied with three types of measurements including range-only,time of arrival,bearing-only. The results show that the sensor-target geometrical topology with optimal localization performance can be implemented by analyzing the sensor-target geometrical characteristics. And the optimal geometrical topology is usually not exclusive. Considerable research foundation was provided for understanding the essence of localization,tracking and navigation for wireless multisensor by intrinsic geometrical topology.
    Related Articles | Metrics
    Safety for Near Round Reference Orbit Satellites Formation
    Hu Min Zeng Guoqiang Yao Hong Li Xiaoming (Academy of Equipment Command & Technology,Beijing 101416)
    2010, 30 (04):  16-22. 
    Abstract ( 2479 )   Save
    The safety of close formation flying satellites was investigated. Aiming at the near round reference orbit satellites,the formation configuration was described based on the relative orbit elements,formulas of the minimize distance of formation flying satellites in the cross-track direction were proposed,and the influence of J2 perturbation to the safety of satellites formation was analyzed. The simulation results demonstrate that the phase difference in the orbital plane and the plane perpendicular to the orbital plane has great impact on the safety of the close formation flying satellites. The measures which can make the formation satellites safer have practical value for enabling the satellites formation.
    Related Articles | Metrics
    Genetic Arithmetic Based Dynamic Channel Allocation Algorithm for SOFDM System in Satellite Multimedia Broadcastings
    Yang Tong (China Academy of Space Technology,Beijing 100094)
    2010, 30 (04):  23-30+70. 
    Abstract ( 2645 )   Save
    The satellite orthogonal frequency division multiplexing (SOFDM) system is usually considered as an enormous amount of sub-carriers and large-scaled system architecture,as well as complicated channel transmitting characteristics,which makes some traditional dynamic channel resource allocation methods inefficient and induces to much power loss,such as the fixed group classification means. An improved method was proposed,which was designed to allot frequency and power resources via the genetic arithmetic with the survival of the fittest principle. The experimental results demonstrate that it can assign the sub-carriers and power in a more reasonably manner. Although its computational complex is equivalent in comparison with the genetic method,this novel means is able to save the system power almost 1dB,so as to remarkably spare the system resources and also improve the system package error rate (PER) performance.
    Related Articles | Metrics
    Testable Designing Methods of Satellite Software
    Yuan Li Wang Lei (Beijing Institute of Control Engineering,Beijing 100190)
    2010, 30 (04):  31-37. 
    Abstract ( 2706 )   Save
    Satellite's on-board software is much more complex than before,so how to improve test efficiency of satellite software is very important for its quality.The effective testable software designing is the key for improving test efficiency of integrated on-board satellite software.Several testable designing methods were proposed including testable multi-layered software architecture used to restrict software defaults in a limited layer,task template in contract used to reduce the correlations between tasks,global status code series used to point out software flow dynamically,and task scheduling & stack records used to describe software flow statically.The data analysis indicates those testable designing methods mentioned are feasible and effective for improving test efficiency of satellite software.
    Related Articles | Metrics
    Modulation Transfer Function Compensation Technology of Optical Remote Sensing Imaging System
    Zeng Yong1 Chen Shiping2 Yu Jin1 (1 China Center for Resources Satellite Data and Application,Beijing 100094) (2 China Academy of Space Technology,Beijing 100081)
    2010, 30 (04):  38-43. 
    Abstract ( 4269 )   Save
    Modulation transfer function compensation (MTFC) is very important for optical remote sensing imaging system to promote image quality and optimize the imaging system modulation transfer function (MTF). Based on inverse filtering and Wiener filtering,the MTFC technology was studied and improved according to CBERS imaging system characteristics. The optimal design of MTFC was done from MTFC curve shape as follows:the middle frequency MTF was enhanced remarkably,and the high frequency part was enhanced moderately. It not only improved the image definition,but also controlled the noise involved. Compromise has been found between the image definition and noise for this technology. CBERS-02B HR imaging system is taken as an example,the result shows that MTFC can improve the image quality obviously,and at the same time,it increases some noises. Several suggestions are given to the applicability of MTFC finally.
    Related Articles | Metrics
    Axial Flexible Vibration Characteristics of High Speed Spoked Rotors in Inertia Actuator
    Deng Ruiqing1,3 Hu Gang2 Wang Quanwu1 (1 Beijing Institute of Control Engineering,Beijing 100190) (2 China Academy of Space Technology,Beijing 100094) (3 National Laboratory of Space Intelligent Control,Beijing 100190)
    2010, 30 (04):  44-51. 
    Abstract ( 2804 )   Save
    The disturbances generated from axial flexible vibration of the high speed rotor of the inertia actuator will have a bad effect on the precision and the stability of the spacecrate attitude control. The model of the flexible vibration must be set up to decrease the disturbances of the high speed rotor. The spoke of the rotor can be regarded as the cantilever beam with a fixed end and a lumped mass end. Thus the model of the flexible vibration was obtained,and the characteristics of the flexible vibration of the rotor were analyzed. The results show that the violent flexible vibration will happen if the motivation frequency equals to the natural frequency of the rotor. Moreover,the energy method can be used to increase the precision of the model.
    Related Articles | Metrics
    Passive Location Method of Beidou Geostationary Satellites Positioning System Aided by Pseudolites
    Liu Ruihua Zhang Fan (Institute of CNS/ATM,Civil Aviation University of China,Tianjin 300300)
    2010, 30 (04):  52-57. 
    Abstract ( 2900 )   Save
    At present,China's Beidou geostationary satellites positioning system can only achieve two-dimensional active location,which greatly limits its application. A passive location method was put forward by using pseudolites to aid Beidou Geostationary Satellites Positioning System. The positioning theory of this system was discussed and the system time synchronization problem was analyzed. The effects of number and layout of pseudolites on the system accuracy were researched by mathematical simulation. The results show that the proposed method is feasible,which can enhance the usability,reliability,stability and the location precision of the system.
    Related Articles | Metrics
    Dual-path Quasi-optical System for Space Remote Sensing
    Yu Junsheng1 Chen Xiaodong2 Miao Jungang3 Liu Shaohua1 Xu Liang2 Liu Xiaoming1 Su Hansheng1 Wei Qin'gang1 Mai Yuan1 Liu Hairui1 Bai Ming3 (1 Beijing University of Posts and Telecommunications,Beijing 100876) (2 Queen Mary,University of London,London E1 4NS) (3 Beihang University,Beijing 100191)
    2010, 30 (04):  58-63. 
    Abstract ( 3632 )   Save
    Quasi-optical networks (QON) were widely used in the remote sensing radiometry system embedded in the satellite platform. Beijing University of Posts and Telecommunications,Queen Mary University of London in collaboration with Beihang University had designed a dual-path QON by using the diffractive Gaussian beam analysis (DGBA) method developed at Queen Mary. The system required an output beamwidth of 20 degrees at-8.68dB with a side lobe below-25dB. Good agreement is achieved between simulation and experiment.
    Related Articles | Metrics
    Stability of the Condensing Interface in a Capillary Loop with Phase Change
    Tu Zhengkai1 Liu Wei2 Liu Zhichun2 Fan Aiwu2 (1 State Key Laboratory of Advanced Technology for Materials Synthesis and Progressing,Wuhan University of Technology,Wuhan 430070) (2 College of Energy and Power Engineering,Huazhong University of Science and Technology,Wuhan 430074)
    2010, 30 (04):  64-70. 
    Abstract ( 3093 )   Save
    A mathematical model based on the Lucas-Washburn equation was developed to address the relations of the capillary height,capillary radius and the heat flux in a capillary column and the equation was extended to a capillary loop for investigating the stability of the condensing interface with phase change by some simplifications. The stability of the condensing interface was studied by introducing a small disturbance into capillary height. The dynamics performances of the condensing interface under three different operating conditions were discussed. The results show that there is avibration with a certain amplitude on the condensing interface due to the periodic oscillation of the pressure in the system.
    Related Articles | Metrics
    Uncertainty Evaluation on the Sniffing Probe Method of Helium Mass Spectrometer Leak Detector for Spacecraft
    Wang Yong Yan Rongxin (China Academy of Space Technology,Beijing 100094)
    2010, 30 (04):  71-75. 
    Abstract ( 2802 )   Save
    Helium mass spectrometer sniffing probe method is widely used in the process of the single point leak testing on the spacecraft. So it is important to study the uncertainty evaluation of this method. First,the method of uncertainty evaluation was studied based on the basic theory about uncertainty. Secondly,the detail evaluation steps were also given through a example. The presented evaluation method may provide a reference for evaluating the uncertainty about the total leak rate method of spacecraft and vacuum leak testing method.
    Related Articles | Metrics
    Numerical Simulation on the Damage of Front Side of Gas-filled Pressure Vessels due to Hypervelocity Impact
    Pang Baojun Gai Fangfang Guan Gongshun (Hypervelocity Impact Research Center,Harbin Institute of Technology,Harbin 150080)
    2010, 30 (04):  76-82. 
    Abstract ( 2593 )   Save
    The Lagrange methods in AUTODYN-2D were used to investigate the perforation of the front side of gas-filled pressure vessels. The static stress wall resulting from the inner pressure was simulated by applying a stress boundary along the inner wall. A better correlation between experimental and numerical results was obtained. The numerical simulation was performed to analyze the effects of the projectile diameter,the impact velocity and gas pressure on the perforation of the front wall. The simulation result shows that the effect of gas pressure on the perforation can be neglected. While impact velocity is higher than 3.0 km/s,some micro-crack are initiated at the edge of the circular hole in the vessel wall. Both hole diameter and crack diameter are increased with an increase of the impact velocity and projectile diameters. The critical stress curves with different impact parameters were obtained. While impact velocity is higher than 3.0 km/s,cracks and hole in the vessel walls will lead to a catastrophic failure of vessels.
    Related Articles | Metrics