随机起伏界面声散射的实验与理论研究
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摘要
进行了二维粗糙海面声波散射特性的水池实验,测量了不同入射角、散射角以及方位角条件下所对应的散射强度。实验通过不同位置风扇对水面的吹拂获得粗糙水面,分别对水平面上互相垂直的两个方向上的水面波高变化进行了测量,利用周期图法估计出这两个方向上的空间功率谱,验证了实验中的粗糙水面是各向同性的。利用改进的空间域处理技术去除了总声波信号中的直达波和其他固定位置散射体的散射信号,获得了粗糙水面的声波散射信号。利用小斜率近似方法计算了二维粗糙海面的声散射特性。实验与模拟计算结果比较,证实了计算二维粗糙海面声波散射特性的小斜率近似方法的有效性与准确性,相互印证了实验与理论。
An experiment about acoustic scattering strength of rough sea surface has been conducted at pool. The variation of the scattering strength with different incident angles, scattering angles, and azimuth angles are measured. In the experiment, fans at different positions are used to obtain the rough sea surface. And the rough sea surface's spatial power spectrum density is obtained with the method of period gram method. The horizontal spatial power spectrum density is compared with the vertical one, and the result shows that the rough sea surface is isotropic. In order to eliminate the direct signal and the scattering signals from the scatters at other fixed positions in the total rough surface scattering signal, a spatial domain processing method is introduced. Acoustic scattering from the 2-D rough surface by the small slope approximation theory is studied, and the scattering strength of the rough sea surfaces is calculated. The comparison of the results between the experiment and the simulative calculation validates that the small slope approximation theory is effective and correct. And so, the validity of both the experiment and the theory is verified.
An experiment about acoustic scattering strength of rough sea surface has been conducted at pool. The variation of the scattering strength with different incident angles, scattering angles, and azimuth angles are measured. In the experiment, fans at different positions are used to obtain the rough sea surface. And the rough sea surface's spatial power spectrum density is obtained with the method of period gram method. The horizontal spatial power spectrum density is compared with the vertical one, and the result shows that the rough sea surface is isotropic. In order to eliminate the direct signal and the scattering signals from the scatters at other fixed positions in the total rough surface scattering signal, a spatial domain processing method is introduced. Acoustic scattering from the 2-D rough surface by the small slope approximation theory is studied, and the scattering strength of the rough sea surfaces is calculated. The comparison of the results between the experiment and the simulative calculation validates that the small slope approximation theory is effective and correct. And so, the validity of both the experiment and the theory is verified.
引文
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[12]吴本玉,莫喜平,崔证.非消声水池中低频换能器测量的空间域处理方法[J].声学学报,2010,35(4):434-440.WU Benyu,MO Xiping,CUI Zheng.A spatial domain processing method for low frequency transducer measurement in a reverberant tank[J].Acta Acustica,2010,35(4):434-440.
[2]Holford R L.Scattering of sound waves at a periodic pressure release surface:An exact solution[J].J.Acoust.Soc.Am,1981 70(4):1116-1128.
[3]Harper E Y,Labianca F M.Perturbation theory for scattering of Sound from a point source by a moving rough surface in the presence of refraction[J].J.Acoust.Soc.Am,1975,57(5):1044-1051.
[4]Thorsos E I,Jackson D R.The validity of the perturbation approximation for rough surface scattering using a Gaussian roughness spectrum[J].J.Acoust.Soc.Am,1989,86(1):261-277.
[5]Kuperman.Coherent component of specular reflection and transmission at a randomly rough two-fluid interface[J].J.Acoust.Soc.Am,1975,58(2):365-370.
[6]Voronovich.Small slope-approximation in wave scattering by rough surfaces[J].Sov.Phys.JETP,1985,62(1):65-70.
[7]YANG Taiqian,Broschat.Acoustic scattering from a fluid-elastic-solid interface using the small slope approximation[J].J.Acoust.Soc.Am,1994,96(3):1796-1804.
[8]Thorsos E L.An investigation of the small slope approximation for scattering from rough surfaces[J].J.Acoust.Soc.Am,1995,97(4):2082-2093.
[9]Daniel Wurmser.Stochastic cross-sections based on the small slope approximation:theory[R].Washington DC,Naval Research Laboratory.
[10]王伟.图像复原中的模糊参数估计[J].智能系统学报,2012,7(4):1-6.WANG Wei,Estimation of blur parameters in image restoration[J].CAAI Transactions on Intelligent Systems,2012,7(4):1-6.
[11]姚武川,姚天任.经典谱估计方法的Matlab分析[J].华中理工大学学报,2000,28(4):45-47.YAO Wuchuan,YAO Tianren.Analyzing classical spectral estimation by MATLAB[J].Journal of Huazhong University of Science and Technology,2000,28(4):45-47.
[12]吴本玉,莫喜平,崔证.非消声水池中低频换能器测量的空间域处理方法[J].声学学报,2010,35(4):434-440.WU Benyu,MO Xiping,CUI Zheng.A spatial domain processing method for low frequency transducer measurement in a reverberant tank[J].Acta Acustica,2010,35(4):434-440.