Time filter

Source Type

Lin L.,National University of Defense Technology | Lin L.,94810th Unit of Peoples Liberation Army | Xu H.,National University of Defense Technology | Long Y.,National University of Defense Technology | And 2 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2011

The essentiality of cluster tracking for midcourse ballistic target group by low earth orbit(LEO) optical constellation is analyzed. And an improved method of cluster tracking is presented. The probability hypothesis density filter is used to track multi-target on the focal plane, filter out clutter, and estimate target number and state. Then for improving the stability of focal plane target tracking, an image registration method is adopted to adjust interframes target state estimation. Finally, the focal plane 2D centroid measurement of target group is computed based on the focal plane tracking results, and unscented Kalman filter(UKF) is adopted to track the 3D centroid of target group through multi-sensor fusion in sequence. Simulation results show that, the proposed method works well under different clutter rates, and gains a better precision than the traditional one. Meanwhile, it successfully realizes the tracking of each target on the space-based infrared focal plane.

Wang G.,CAS Anhui Institute of Optics and Fine Mechanics | Wang G.,Artillery Academy of Peoples Liberation Army | Sun D.,Anhui University of Science and Technology | Duan L.,Artillery Academy of Peoples Liberation Army | Shu Z.,CAS Anhui Institute of Optics and Fine Mechanics
Guangxue Xuebao/Acta Optica Sinica | Year: 2011

Fabry-Pérot etalon is usually employed as discriminating frequency unit in direct detection Doppler wind lidar, and performance of Fabry-Pérot etalon and design of state of incident light beam are important factors in measurement error of the whole systems. The fundamental theory of the Doppler wind lidar based on a triple Fabry-Pérot etalon is introduced. After deep analysis of free spectral range (FSR) and full width at half maximum (FWHM) and peak value interval in two edge channels, the project of parameters design is obtained. The state of incident light beam has an obvious effect on transmission curve of Fabry-Pérot etalon. According to the correlative equation, the effects of incident angle, divergence angle and partial facula permeating through etalon channel designed on transmission curve are provided, and corresponding measurement error is calculated and simulated.

Yuan H.,Chinese Academy of Sciences | Yuan H.,University of Chinese Academy of Sciences | Yuan H.,Artillery Academy of Peoples Liberation Army | Mei H.,Chinese Academy of Sciences | And 2 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2011

Considering the influences of atmospheric refraction on the satellite laser ranging, an algorithm for calculating the optical path differences based on ray tracing is studied. Firstly, the annual mean atmospheric refractivity modulus height profiles of 46 typical regions in China are fitted by using meteorological sounding datum and high level model datum synthetically. Secondly, the results calculated by the Marini-Murray model and ray tracing which is based on the monthly average model and the annual mean model are compared and analyzed. Then, the national distribution of the optical path difference of satellite laser ranging is presented. Finally, the relations between the optical path difference with the height above sea level of ranging site and the elevation of satellite are numerically investigated.

Wang B.,National University of Defense Technology | An W.,National University of Defense Technology | Xie K.,Artillery Academy of Peoples Liberation Army | Zhou Y.,National University of Defense Technology
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2010

To deal with the problem of sensor resource scheduling for continual multi-object tracking with low earth orbit constellation, the object tracking tasks are first classified into two sets, i.e., the higher precision task set and the lower precision task set, and their state transition procedures are analyzed. Then, a sensor scheduling model for each task set is established based on the dynamic priority theory. Furthermore, a novel real-time sensor scheduling algorithm based on a multi-model is proposed. Simulations executed in diverse scenarios indicate that the applicability of the proposed algorithm exceeds that of the traditional methods which consider the dilution of precision as the optimal objective or threshold constraint. This is especially true in the case of multi-object scenarios of centralized distribution. The drop-out ratio of the proposed method is greatly reduced as compared with that of the traditional methods, although a few objects show slightly larger tracking errors.

Zhou P.-C.,Artillery Academy of Peoples Liberation Army | Zhang H.-K.,Artillery Academy of Peoples Liberation Army | Xue M.-G.,Artillery Academy of Peoples Liberation Army
Guangzi Xuebao/Acta Photonica Sinica | Year: 2011

To overcome shortcomings of current polarization image fusion methods, a novel false-color imagery fusion approach based on color transfer and clustering-based segmentation was proposed. Firstly, the images by polarization information analysis were mapped into HSI color space, thus the initial false-color fused image was obtained. Then, the fused image was transformed into YIQ color space, and the chromatic characteristics each channel was modified using those of the reference image. After that, the modified image was transformed into HSI color space, and the segmentation result of the image of degree of linear polarization using fuzzy C-means clustering algorithm was used to adjust its hue component and saturation component. Finally, the resultant image was transformed back into RGB color space, so the final fused image was obtained. Experimental results show that, the proposed method has the merit that the fused result is consistent with the habit of human vision perception, and makes the contrast of artificial targets within the cluttered background more outstanding.

Zhou H.,Nanjing University of Aeronautics and Astronautics | Huang Z.,Nanjing University of Aeronautics and Astronautics | Zhu Y.,Nanjing University of Aeronautics and Astronautics | Zhu Y.,Xuzhou Normal University | And 2 more authors.
Jisuanji Yanjiu yu Fazhan/Computer Research and Development | Year: 2012

Time Petri net is widely used to model real-time control systems. Contacts are important behaviors of Petri net and these expansion models. To solve the contacts is a key of analyzing models dynamic behaviors. Because the time constraints are adhibited, time Petri net enabling and triggering semantics are becoming more complex than Petri net, and contacts checking and resolution are getting more difficult. Time intervals of transitions are defined when these transitions are durably enabled, and this definition correctness is discussed. An approach is proposed to check contacts of time Petri net and a contacts resolution approach based on changing time constraints of transitions is defined and proved. The approach availability is verified by an example analysis. The results show that applying our approach to check the resource contacts of time Petri net is feasible.

Wang J.-D.,South China Normal University | Wei Z.-J.,South China Normal University | Zhang H.,Artillery Academy of Peoples Liberation Army | Qin X.-J.,Guangzhou University | And 4 more authors.
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2010

We propose a scheme for quantum key distribution, in which single photons are encoded with polarization states and then divided and delayed to encode phase differences between two sequential pulses. In an example, the BB84 and DPS (differential phase shift) protocols are combined to achieve single-photon two-qubit quantum key distribution. This scheme can increase the key generation efficiency up to 7/6, higher than that of the conventional single-photon one-qubit quantum key distribution scheme. © 2010 IOP Publishing Ltd.

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