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Li Y.-B.,Dalian Naval Academy | Zhang Y.-G.,Dalian Naval Academy | Wang H.-L.,National Key Laboratory of Science and Technology on Underwater Test and Control | Qi Y.,National Key Laboratory of Science and Technology on Underwater Test and Control
Hongwai Yu Haomibo Xuebao/Journal of Infrared and Millimeter Waves | Year: 2011

Based on air-sea flux algorithm and parabolic approximation method, mathematical model for the optical propagation tracing was established. Maximum Inter-Visvion Ranges(MIVR) was evaluated, and the root cause of Mirage was analyzed. Numerical analysis and sea experimental results showed that MIVR decreases with the reduction of the temperature difference (ΔT) between the air and sea when wind speed is kept constant. Under the invariant ΔT, MIVR decreases with the increase of wind speed. The decrement of MIVR decreases with ΔT decreasing. The values of MIVR decrease linearly with the height of the sensor-target. The experiment proved that evaluation of MIVR with the model has high accuracy.


Sun T.,National Key Laboratory of Science and Technology on Underwater Test and Control | Li G.,National Key Laboratory of Science and Technology on Underwater Test and Control | Li M.,National Key Laboratory of Science and Technology on Underwater Test and Control
Proceedings - 2010 IEEE Youth Conference on Information, Computing and Telecommunications, YC-ICT 2010 | Year: 2010

In order to solve the problem of broadband omnidirectional acoustic scattering computing for underwater elastic object, broadband acoustic scattering model of underwater elastic object is presented combining Finite-Difference Time-Domain (FDTD) method and the relation between scattering wave spectrum and form function. We simualted broadband acoustic scattering characteristic of elastic aluminum sphere using this method, and compared the result with the corresponding analytic solution, and they were in good agreement. Furthermore, we computed non-backscattering broadband characteristics, which were very difficult to gain using other methods, including bistatic angle 45 degree and 90 degree, and compared and analyzed them. The results showed that their formant position, vibration amplitude and resonance period existed distinct difference, that was to say, with the changing of bistatic angle, frequency domain scattering characteristic of the object brought great difference. © 2010 IEEE.


Liu H.,National Key Laboratory of Science and Technology on Underwater Test and Control | Chen S.,National Key Laboratory of Science and Technology on Underwater Test and Control | Qi Y.,National Key Laboratory of Science and Technology on Underwater Test and Control | Wang H.,National Key Laboratory of Science and Technology on Underwater Test and Control | Wang Y.,National Key Laboratory of Science and Technology on Underwater Test and Control
ICEOE 2011 - 2011 International Conference on Electronics and Optoelectronics, Proceedings | Year: 2011

The surface temperature distribution of stratified sea water is different from the surroundings disturbed by the propeller and it can express a particular infrared character. The surface temperature distribution disturbed by a propeller in the negative temperature gradient sea is studied by numerical simulation and infrared imaging. The experiment is carried out through infrared camera imaging and the temperature character of the sea surface is obtained. The results show that there is high comparability between the numerical simulation and the infrared imaging. The mechanism of the sea surface temperature difference is explained and the feasibility of monitoring the sea surface temperature by the infrared camera is also validated. © 2011 IEEE.


Sun B.Q.,National Key Laboratory of Science and Technology on Underwater Test and Control | Tian Z.X.,National Key Laboratory of Science and Technology on Underwater Test and Control
Applied Mechanics and Materials | Year: 2013

To detect week signal of underwater magnetic fields, we designed a negentropy maximization blind source separation algorithm based on the stochastic gradient descent algorithm by bring in a penalty factor. The simulation study demonstrates that the new algorithm is effective to separate the mixed-signal with high precision, to decrease the iterative calculation and to enhance the convergence rate. © (2013) Trans Tech Publications, Switzerland.


Wang H.,National Key Laboratory of Science and Technology on Underwater Test and Control | Qi Y.,National Key Laboratory of Science and Technology on Underwater Test and Control | Liu H.,National Key Laboratory of Science and Technology on Underwater Test and Control
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2013

Compared with the nearby undisturbed seawater the temperature difference in the ship wake is tiny and the ship wake presents obscure configuration. These induce the low contrast of the infrared ship wake image and the borders of the wake images are difficult to be extracted. According to the characters of ship wake and infrared wake image, a border detecting method by dynamic texture and mathematical morphology was proposed. Firstly, the infrared wake image sequence was pre-segmented by dynamic texture method, and then the edges in the wake area were extracted by Canny operator. The extracted edges were dilated, labeled and selected by the mathematical morphology and the true wake borders were extracted. The experimental results show that processing the wake images by the methods mentioned above can effectively extract the borders of the ship wake and get better results.


Li Y.,Dalian Naval Academy | Zhang Y.,Dalian Naval Academy | Wang H.,Dalian Naval Academy | Wang H.,National Key Laboratory of Science and Technology on Underwater Test and Control
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2011

Photoelectric equipments such as visible light and infrared can be affected by atmospheric refraction remarkable when detecting and tracking the low-sky targets. The distance to the apparent horizon from an observer can be lengthened or shortened, which especially presents the multi-objective phenomena, increases the false alarm probability and disturbs the targets detecting and tracking. A photoelectric propagation characteristics evaluation model based on air-sea flux algorithm and ray tracing algorithm was established. Using the photoelectric detection trial data of an area of sea in the northern Yellow Sea during December 2009, subrefraction characteristic height, the maximum detection range (MIVR) as well as some relevant photoelectric propagation parameters were real-time evaluated, the marine multi-objective image (mirage) was simulated, and the performance of the model was proved. The results show that the model can evaluate the MIVR, and simulate the mirage in different distance accurately. It provides the effective environment safeguard information for the marine photoelectric system.


Li Y.,Dalian Naval Academy | Zhang Y.,Dalian Naval Academy | Li G.,National Key Laboratory of Science and Technology on Underwater Test and Control | Wang H.,National Key Laboratory of Science and Technology on Underwater Test and Control
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2011

This paper established optical propagation tracing mathematical model based on geometrical optics and parabolic approximation method, extracting maximum inter-vision ranges(MIVR) to denote the absolute detection range limit imposed by refraction for a given sensor and target height, determining the appearance mechanism of mirage. When wind speed is constant, MIVR decreases with the increase of air-sea difference in temperature(ASTD); but MIVR decreases with the increase of wind speed under the constant ASTD; the MIVR decreases with ASTD increasing, the corresponding relationships of MIVR and the height position is a standard straight line, and MIVR reduces with the height parameter decreasing; the accuracy of MIVR is better.

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