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Deng K.,University of Electronic Science and Technology of China | Wang B.-Z.,University of Electronic Science and Technology of China | Zhao G.-H.,Airforce Engineering University | Huang J.,University of Electronic Science and Technology of China | And 3 more authors.
Optics Express | Year: 2014

By integrating coherent tracking sensor functionality into a coherent communication receiver, a dual-function receiver with coherent boresight error sensing is developed for tracking in coherent free-space optical communication systems. The sensor principles are analyzed according to optical interference theory, and the boresight error detection algorithm and small signal linear model are derived. Analysis of local-oscillator beam nutation on system performance shows that the best nutation half-angle is 0.5-1μrad, the noise equivalent angle is less than 0.02μrad, and the communication sensitivity degradation is 0.2-0.6dB. This technology opens new avenues for free-space optical communication system design. ©2014 Optical Society of America.

Zhang Q.,Jiangsu University | Qian Y.,Jiangsu University | An Z.,Airforce Engineering University | Li X.,Jiangsu University | And 2 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

In order to study the effect of laser shock processing (LSP) on the electrochemical corrosion resistance of magnesium alloys, the electrochemical corrosion behaviors in 3.5% (mass fraction) NaCl solution of AZ31, AZ61 and AZ91 magnesium alloys are investigated by electrochemical method and Nd: glass laser with the wavelength of 1064 nm and pulse width of 20 ns. Its surface morphologies, microstructures, microhardness, self-corrosion potential and electrochemical impedance spectroscopy (EIS) are also examined and analyzed. The experimental results show that electrochemical corrosion resistance of magnesium alloys are improved after LSP. With the increasing of laser power density, the self-corrosion potential of magnesium alloy begins to move towards a positive direction, the corrosion current density decreases and the impedance arc becomes larger. When power density reaches to 0.7 GW/cm2, the current density increases and impedance arc becomes smaller. The effect of the Al content, solution and aging treatment on the corrosion potential and EIS of magnesium alloys by LSP are discussed and analyzed.

Zou K.,Airforce Engineering University
Proceedings of 2011 IEEE CIE International Conference on Radar, RADAR 2011 | Year: 2011

In this paper, we consider the adaptive subspace detector for partially homogeneous environments. In this environment, the clutter covariance matrix (CCM) of secondary data is equal to the CCM of the cell under test (CUT), except for a real constant factor. We also suppose that we have some prior knowledge of the CCM, which is controlled by the parameters of the statistics distribution of the CCM. Based on the Bayesian framework, a knowledge-aided adaptive subspace detector (KA-ASD) is given, and can be used to detect the subspace signal in partially homogeneous environments. The computer simulation is used to validate that KA-ASD is outperform the conventional subspace detector, and especially within a small number of training samples and coherent pulses. © 2011 IEEE.

Li H.,Changan University | Huang Y.,Airforce Engineering University | Huang H.,Changan University
Chang'an Daxue Xuebao (Ziran Kexue Ban)/Journal of Chang'an University (Natural Science Edition) | Year: 2014

Traditional search engines can't completely satisfy users' searching needs which will lead to declined refrieval quality and increased costs. The paper proposed a personalized vehicle image searching algorithm based on clustering analysis and user interest model. According to the characteristics of users' interested objects, Multi-feature sets were first selected for object representation. Then multi-kernel linear confusion was adopted to calculate the similarity. Then an optimal SVM was utilized to complement the multi-kernel clustering, build a specific user interest model and return the personalized searching results to the users. The analysis of experiment results indicates that compared with the traditional searching algorithm the improved algorithm can enhance participation methods of users and solve the gap problem between low-level vision feature and high-level semantics. It can increase the mean recall and precision ratio respectively by 9% and 24% compared with the traditional one based on color, and by 28% and 42. 6% compared with the traditional method based on terfure.

Huang Z.T.,National University of Defense Technology | Liu Z.M.,National University of Defense Technology | Liu J.,Airforce Engineering University | Zhou Y.Y.,National University of Defense Technology
IET Radar, Sonar and Navigation | Year: 2010

The mutual coupling effect in practical arrays is hard to eliminate completely, and such effect brings a deterministic bias into the direction-of-arrival (DOA) estimates for non-circular signals. The bias is analysed in this study and closed-form expressions for the biases in uniform linear arrays (ULA) and general linear arrays (GLA) are given. Numerical examples are carried out to verify the correctness of the theoretical biases in various signal environments. © 2010 The Institution of Engineering and Technology.

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