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一种低声速沉积层海底参数声学反演方法
引用本文:李梦竹,李整林,周纪浔,张仁和.一种低声速沉积层海底参数声学反演方法[J].物理学报,2019,68(9):94301-094301.
作者姓名:李梦竹  李整林  周纪浔  张仁和
作者单位:1. 中国科学院声学研究所, 声场声信息国家重点实验室, 北京 100190; 2. 中国科学院大学电子电气与通信工程学院, 北京 100049; 3. 佐治亚理工学院机械工程学院, 亚特兰大 30332-0405
基金项目:国家自然科学基金(批准号:11434012,11874061)资助的课题.
摘    要:软泥底环境下沉积层参数的声学反演是国际水声领域的一个研究热点.浅海中,当高声速基底和海水之间存在一层低声速(小于海水声速)的沉积层时,小掠射角情况下不同频率声传播损失会出现周期性增大现象.基于此现象,提出一种适用于低声速沉积层的海底参数声学反演方法.首先,推导给出小掠射角情况下传播损失周期增大的频率间隔与沉积层声速、厚度及近海底海水声速之间的解析表达式;其次,利用一次黄海实验中软泥底环境下的宽带声传播信号,提取了小掠射角下传播损失增大的频率周期;再次,把该解析表达式作为约束条件,结合Hamilton密度与声速的经验公式,采用匹配场处理反演给出沉积层的声速、密度、厚度及基底的声速、密度;然后,利用声传播损失数据反演得到泥底环境下不同频率的声衰减系数,通过拟合发现泥底声衰减系数随频率近似呈线性关系;最后,给出了双层海底模型和半无限大海底模型等效性的讨论.反演结果为低声速沉积层海底声传播规律研究与应用提供了海底声学参数.

关 键 词:低声速沉积层海底  声学参数反演  匹配场处理  传播损失
收稿时间:2019-02-01

Geoacoustic inversion for acoustic parameters of sediment layer with low sound speed
Li Meng-Zhu,Li Zheng-Lin,Zhou Ji-Xun,Zhang Ren-He.Geoacoustic inversion for acoustic parameters of sediment layer with low sound speed[J].Acta Physica Sinica,2019,68(9):94301-094301.
Authors:Li Meng-Zhu  Li Zheng-Lin  Zhou Ji-Xun  Zhang Ren-He
Institution:1. State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China; 2. School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China; 3. School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332-0405, USA
Abstract:Acoustic inversion of sediment parameters in muddy bottom environment has received much attention in the field of underwater acoustics. In shallow water, when there is a low-speed layer of unconsolidated sediment, such as mud in which the sound speed is lower than that of the sea water, on the top of a high-speed bottom, the transmission losses at different frequencies will increase periodically under the condition of small grazing angles. Based on this phenomenon, an acoustic inversion method of seabed parameters for low speed sediments is proposed. Firstly, the analytical expressions between the frequency interval of the transmission loss (TL) periodical increasing and geoacoustic parameters, including the sound speed and the thickness of sediment layer and the sound speed of seawater near the bottom, are derived under the condition of small grazing angles. Secondly, using the broadband sound propagation signals received under the thermocline in the 2002 summer acoustic experiment conducted in the Yellow Sea, the TL at small grazing angles increases periodically with the frequency, and it is determined that the sediment of this sea area is a low-speed sediment. Then, taking the analytical expression as the constraint condition and combining with Hamilton's empirical formula, the sound speed, density, thickness of sediment layer and the sound speed and density of the seabed are inverted by matched field processing. Finally, the bottom attenuation coefficients at different frequencies are inverted by using the long-range TL, and the linear relationship between the attenuation coefficients and the frequencies is obtained. The equivalence between the two different bottom models is discussed in the end. The inversion results can provide seabed parameters for the study and application of the sound propagation law in shallow water with a low-speed sediment.
Keywords:low-speed sedimentary seabed  geoacoustic inversion  matched field processing  transmission loss
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