Many research results show that ocean ambient noise and wind speed are highly relevant, and the surface wind speed can be effectively inverted using ocean noise data. In most deep-sea cases, the ambient noise of mediu...Many research results show that ocean ambient noise and wind speed are highly relevant, and the surface wind speed can be effectively inverted using ocean noise data. In most deep-sea cases, the ambient noise of medium frequency is mainly determined by the surface wind, and there is a conventional relationship between them. This paper gives an equation which shows this relationship firstly, and then a surface-wind inversion method is proposed. An efficient particle filter is used to estimate the speed distribution, and the results exhibit more focused close to the actual wind speed. The method is verified by the measured noise data, and analysis results showed that this approach can accurately give the trend of sea surface wind speed.展开更多
A vulcanized rubber layer is usually used on the head of an axisymmetric body to keep it streamlined and watertight.The elastic boundary condition is considered when the flow noise of an axisymmetric body is calculate...A vulcanized rubber layer is usually used on the head of an axisymmetric body to keep it streamlined and watertight.The elastic boundary condition is considered when the flow noise of an axisymmetric body is calculated,and we employ the mutual coupling method between the vulcanized rubber layer and the How around to solve the flow-noise field for an axisymmetric body in water.The results show that the deformation of the vulcanized rubber layer is reduced with the increase in Young's modulus.The Young's modulus of the rubber material should be large enough to keep it streamlined,and the noise power levels in the peak of the axisymmetric body are smaller than the other positions,which provides us with important theoretical support for laying acoustic arrays on the head of the body.展开更多
The problem of detecting an object in shallow water by observing changes in the acoustic field as the object passes between an acoustic source and receiver is addressed.A signal processing scheme based on forward scat...The problem of detecting an object in shallow water by observing changes in the acoustic field as the object passes between an acoustic source and receiver is addressed.A signal processing scheme based on forward scattering is proposed to detect the perturbed field in the presence of the moving object.The periodic LFM wideband signal is transmitted and a sudden change of field is acquired using a normalized median filter.The experimental results on the lake show that the proposed scheme is successful for the detection of a slowly moving object in the bistatic blind zone.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.11174235 and 61101192)
文摘Many research results show that ocean ambient noise and wind speed are highly relevant, and the surface wind speed can be effectively inverted using ocean noise data. In most deep-sea cases, the ambient noise of medium frequency is mainly determined by the surface wind, and there is a conventional relationship between them. This paper gives an equation which shows this relationship firstly, and then a surface-wind inversion method is proposed. An efficient particle filter is used to estimate the speed distribution, and the results exhibit more focused close to the actual wind speed. The method is verified by the measured noise data, and analysis results showed that this approach can accurately give the trend of sea surface wind speed.
基金Supported by the National Natural Science Foundation of China under Grant No 11174235the Science and Technology Development Project of Shaanxi Province(No 2010KJXX-02)+1 种基金the Program for New Century Excellent Talents in University(No NCET-08-0455)the Excellent Doctorate Foundation of Northwestern Polytechnical University.
文摘A vulcanized rubber layer is usually used on the head of an axisymmetric body to keep it streamlined and watertight.The elastic boundary condition is considered when the flow noise of an axisymmetric body is calculated,and we employ the mutual coupling method between the vulcanized rubber layer and the How around to solve the flow-noise field for an axisymmetric body in water.The results show that the deformation of the vulcanized rubber layer is reduced with the increase in Young's modulus.The Young's modulus of the rubber material should be large enough to keep it streamlined,and the noise power levels in the peak of the axisymmetric body are smaller than the other positions,which provides us with important theoretical support for laying acoustic arrays on the head of the body.
基金Supported by the National Natural Science Foundation of China under Grant No 10774119the Program for New Century Excellent Talents in University of China under Grant No NCET-08-0455+1 种基金the Natural Science Foundation of Shaanxi Province,under Grant No SJ08F07the Foundation of National Laboratory of Acoustics,and the Northwestern Polytechnical University Foundation for Fundamental Research(2007004).
文摘The problem of detecting an object in shallow water by observing changes in the acoustic field as the object passes between an acoustic source and receiver is addressed.A signal processing scheme based on forward scattering is proposed to detect the perturbed field in the presence of the moving object.The periodic LFM wideband signal is transmitted and a sudden change of field is acquired using a normalized median filter.The experimental results on the lake show that the proposed scheme is successful for the detection of a slowly moving object in the bistatic blind zone.
