基于地声模型的浅海混响地声反演研究

Geoacoustic inversion of reverberation data by applying a geoacoustic model in shallow water

利用浅海混响数据反演海底参数和海底散射常数.混响形成过程中声波多次与海底发生相互作用,因此海底参数之间以及它们与海底散射常数之间的耦合非常严重,未知参数之间的耦合使得常规地声反演方法很难获得海底参数.文中首先利用相对混响强度消除了混响数据中的海底散射常数项,然后利用Hamilton地声模型,分别将海底声速、密度和衰减系数表示成孔隙率的函数,采用自适应下山模拟退火混合反演算法,对单个未知数(孔隙率)进行反演,最后再分别获得海底参数和海底反向散射常数.理论分析和数值模拟表明,该方法可以快速准确获得海底参数,同时具有很好的抗噪声干扰能力.

Reverberations make it difficult to detect objects underwater.To overcome reverberation effects,a method for extracting both geoacoustic parameters and a bottom back-scattering constant from reverberation data was developed.There are many interactions between sound and the sea floor in the process of ocean reverberation.This causes the coupling of geoacoustic and back-scattering parameters to become severe.It is difficult to invert geoacoustic parameters using traditional inversion methods due to this severe coupling.In this paper,relative reverberation levels were used as a first step to eliminate the back-scattering constant.Then sound speed,density and attenuation in sediment were expressed as a function of porosity.Each was separately expressed,and this was based on the Hamilton geoacoustic model.The only unknown parameter（porosity） was easily extracted from relative reverberation data using an adaptive hybrid algorithm.The final step allowed bottom parameters and a bottom back-scattering constant to be deduced using inversed porosity.Theoretical and numerical simulation results showed that geoacoustic parameters and the bottom back-scattering constant can remove reverberation data easily using the proposed method.In addition,this reverberation inversion method resisted noise well.