Most Read

Published in last 1 year |  In last 2 years |  In last 3 years |  All
Please wait a minute...
  • Research Progress of Lossless Compression for Hyperspectral ImageUsing Distributed Source Coding
  • NIAN Yong-jian, WAN Jian-wei, HE Mi, XIN Qin
  • 2012, 33 (7): 860-869. doi: 10.3873/j.issn.1000-1328.2012.07.002
  • Abstract ( 2466 ) PDF (1766KB)( 1366 )
    An effective compression technique for hyperspectral images has become one of the focuses in the field of space hyperspectral remote sensing. The lossless compression technique of hyperspectral images based on distributed source coding (DSC) is studied in this paper. First, the theoretical foundation, realizable manner of DSC and its advantages in lossless compression of hyperspectral images are introduced. Then the research progress of lossless compression of hyperspectral images based on DSC is summarized, a distributed lossless compression algorithm of hyperspectral images based on multiband prediction is proposed. Experimental results show that the proposed algorithm has low encoding complexity, its compression performance is also better than that of the existing distributed compression algorithms. Finally, the problems which need further research on DSC application in hyperspectral images compression are pointed out.
  • Related Articles | Metrics
  • Jason2 Precise Orbit Determination with DORIS/SLR Tracking Data
  • PENG Dong-ju, WU Bin, QU Wei-jing
  • 2012, 33 (10): 1391-1400. doi: 10.3873/j.issn.1000-1328.2012.10.005
  • Abstract ( 1908 ) PDF (1587KB)( 1067 )
    The DORIS instrument called DGXX on Jason2 satellite is the first of the third generation. Compared to the previous two generations, both data efficiency and tracking capability of DGXX have been improved significantly. Firstly, transformation between phase data of DGXX and traditional Doppler data is described in this paper, and then the accuracies of orbits determined by using DORIS data only and DORIS data combined with SLR data are assessed through various methods including postfit RMS comparison, orbit overlapping validation, independent orbit comparison and SLR validation. In addition, considering if real meteorological data of some stations are not available or inaccurate, that the accuracy of the troposhperic delay correction model can be affected the use of a new Global Pressure and Temperature (GPT) model in DORIS precise orbit determination (POD) is therefore discussed in this paper. It is demonstrated that the orbit accuracy with GPT model and real meteorological data is at the same level, therefore GPTderived data is an eligible substitute once some real meteorological data are missing. Apart from that, Both orbit solutions with DORIS only data and DORIS combined with SLR data can reach 1 cm accuracy level at radial direction, the one with both DORIS and SLR data is slightly better than that with DORIS data only. The main contribution of SLR data to DORIS+SLR POD is to reduce the correlation between those two types of parameters of zenith tropospheric delay and DORIS frequency drift; longstable POD can benefit from this particular advantage.
  • Related Articles | Metrics
  • Novel Cubature Kalman Particle Filter for Airborne Passive Location
  • LIU Xue, JIAO Shu-hong
  • 2011, 32 (7): 1478-1485. doi: 10.3873/j.issn.1000-1328.2011.07.007
  • Abstract ( 1889 ) PDF (904KB)( 1064 )
    In order to solve the question of airborne passive location of multi\|dimensional nonlinear filtering, a novel Particle filter algorithm is proposed by using three order Cubature Kalman filter to generate the importance density function. The new algorithm adopts Spherical rule and Radial rule to calculate the quadrature points and determine the corresponding weights with the final quadrature points only twice the state dimension, which considerably provide a systematic solution for the computational complexity problems encountered in the Quadrature Kalman filter under high\|dimensional nonlinear filtering, and the new algorithm also sets scale factor to integrate the latest observations with the figured importance density function on the basis of the system state transition density,thus increasing diversity of particles, and improving the approximation to the system posterior density. Simulation results indicate that the Cubature Kalman Particle filter only consumes about 15% the computing time required by the Quadrature Kalman particle filter, while the stability and location accuracy is kept.

  • Related Articles | Metrics
  • A Polynomial Interpolation Based Particle Swarm Optimization Algorithm
    for Trajectory Planning of Free-Floating Space Robot
  • SHI Zhong, WANG Yong-zhi, HU Qing-lei
  • 2011, 32 (7): 1516-1521. doi: 10.3873/j.issn.1000-1328.2011.07.012
  • Abstract ( 1875 ) PDF (923KB)( 1131 )
    A nonholonomic motion planning methodology for Free\|Floating Space Robot (FFSR) is proposed by using polynomial interpolation combined with particle swarm optimization algorithm. More specifically, under the nonholonomic constrained conditions of system, the optimal control technique is applied for FFSR trajectory planning, in which the dissipative energy of the manipulator joint angles is considered as an objective function. Moreover, the high order polynomial is used to approach the trajectories of the joint angles, and set the coefficients of the interpolation polynomial as optimization parameters. The particle swarm optimization is implemented to achieve the optimal trajectory, such that the planned joint angle trajectories are smooth and continuous, and the angular velocities and the accelerations of joints at the initial and final equal to zero. Numerical simulation results demonstrate that the proposed method is effective and available for solving the Free\|Floating trajectory planning problem.
  • Related Articles | Metrics