海底地形变化对声传播具有很大影响,在南海深海区域海底斜坡环境下进行了一次声传播实验,实验显示倾斜海底环境下声传播损失出现了一些不同于平坦海底环境下的现象,分析并解释了海底地形变化对产生声传播差异的原因.结果表明,海底斜坡...海底地形变化对声传播具有很大影响,在南海深海区域海底斜坡环境下进行了一次声传播实验,实验显示倾斜海底环境下声传播损失出现了一些不同于平坦海底环境下的现象,分析并解释了海底地形变化对产生声传播差异的原因.结果表明,海底斜坡对声波的反射增强作用可使斜坡上方的声传播损失减少约5 d B.当声波第一次入射到达的海底位置有较小幅度的山丘(凸起高度小于1/10海深)时,海底小山丘即可对声波有反射遮挡作用,导致在其反射区特定传播距离和深度上出现倒三角声影区,比平坦海底环境下相同影区位置处的传播损失增大约8 d B,影响深度可达海面以下1500 m.而海底斜坡对声波的反射阻挡作用使得从海面反射及水体向下折射的会聚区结构消失,只剩下从水体向上折射的会聚结构.因此,海底地形对深海声传播影响较大,在水下目标探测和性能评估等应用中应予以重视.展开更多
为了验证现有模型的精度,导出了全反射下边界双层波导中简正波耦合矩阵的解析表达式,并将其应用到全局矩阵耦合简正波模型(Direct global matrix coupled-mode)中,使得该模型可以提供水平变化双层波导问题的标准解。文中首先利用COUPLE...为了验证现有模型的精度,导出了全反射下边界双层波导中简正波耦合矩阵的解析表达式,并将其应用到全局矩阵耦合简正波模型(Direct global matrix coupled-mode)中,使得该模型可以提供水平变化双层波导问题的标准解。文中首先利用COUPLE的简正波及耦合矩阵数值解验证了该简正波及耦合矩阵解析表达式的正确性;其次,采用改进的DGMCM模型求解了双层波导海山声传播损失,结果表明,改进后的DGMCM模型可以非常精确地求解水平变化双层波导问题,可作为求解此类问题的标准模型使用。展开更多
An ocean-acoustic joint model is developed for research of acoustic propagation uncertainty in internal wave environments.The internal waves are numerically produced by tidal forcing over a continental slope using an ...An ocean-acoustic joint model is developed for research of acoustic propagation uncertainty in internal wave environments.The internal waves are numerically produced by tidal forcing over a continental slope using an ocean model.Three parameters(i.e.,internal wave,source depth,and water depth)contribute to the dynamic waveguide environments,and result in stochastic sound fields.The sensitivity of the transmission loss(TL)to environment parameters,statistical characteristics of the TL variation,and the associated physical mechanisms are investigated by the Sobol sensitivity analysis method,the Monte Carlo sampling,and the coupled normal mode theory,respectively.The results show that the TL is most sensitive to the source depth in the near field,resulted from the initial amplitudes of higher-order modes;while in middle and far fields,the internal waves are responsible for more than 80%of the total acoustic propagation contribution.In addition,the standard deviation of the TL in the near field and the shallow layer is smaller than those in the middle and far fields and the deep layer.展开更多
We present a passive geoacoustic inversion method using two hydrophones, which combines noise interferometry and time reversal mirror （TRM） techniques. Numerical simulations are firstly performed, in which strong fo...We present a passive geoacoustic inversion method using two hydrophones, which combines noise interferometry and time reversal mirror （TRM） techniques. Numerical simulations are firstly performed, in which strong fo- cusing occurs in the vicinity of one hydrophone when Green＇s function （GF） is back-propagated from the other hydrophone, with the position and strength of the focus being sensitive to sound speed and density in the bottom. We next extract the GF from the noise cross-correlation function measured by two hydrophones with 8025-m distance in the Shallow Water ＇06 experiment. After realizing the TRM process, sound speed and density in the bottom are inverted by optimizing focusing of the back-propagated GF. The passive inversion method is inherently environmentally friendly and low-cost.展开更多
A coupled-mode method for three-dimensional acoustic propagation and scattering in two-dimensional waveguides is presented.This method synthesizes the three-dimensional field solution by using Fourier transform techni...A coupled-mode method for three-dimensional acoustic propagation and scattering in two-dimensional waveguides is presented.This method synthesizes the three-dimensional field solution by using Fourier transform techniques based on a sequence of two-dimensional problems,each of which is solved by a numerical model recently developed by Luo et al.[Chin.Phys.Lett.29(2012)014302].Numerical results indicate that the present model is remarkably accurate,and thus can serve as benchmark against other numerical models.In addition,this model can be applied to realistic problems,and can also be used to analyze horizontal refraction in some range-dependent waveguides in reality,such as the continental shelf environment,ridge-like bathymetry,and underwater trenches.展开更多
文摘海底地形变化对声传播具有很大影响,在南海深海区域海底斜坡环境下进行了一次声传播实验,实验显示倾斜海底环境下声传播损失出现了一些不同于平坦海底环境下的现象,分析并解释了海底地形变化对产生声传播差异的原因.结果表明,海底斜坡对声波的反射增强作用可使斜坡上方的声传播损失减少约5 d B.当声波第一次入射到达的海底位置有较小幅度的山丘(凸起高度小于1/10海深)时,海底小山丘即可对声波有反射遮挡作用,导致在其反射区特定传播距离和深度上出现倒三角声影区,比平坦海底环境下相同影区位置处的传播损失增大约8 d B,影响深度可达海面以下1500 m.而海底斜坡对声波的反射阻挡作用使得从海面反射及水体向下折射的会聚区结构消失,只剩下从水体向上折射的会聚结构.因此,海底地形对深海声传播影响较大,在水下目标探测和性能评估等应用中应予以重视.
文摘为了验证现有模型的精度,导出了全反射下边界双层波导中简正波耦合矩阵的解析表达式,并将其应用到全局矩阵耦合简正波模型(Direct global matrix coupled-mode)中,使得该模型可以提供水平变化双层波导问题的标准解。文中首先利用COUPLE的简正波及耦合矩阵数值解验证了该简正波及耦合矩阵解析表达式的正确性;其次,采用改进的DGMCM模型求解了双层波导海山声传播损失,结果表明,改进后的DGMCM模型可以非常精确地求解水平变化双层波导问题,可作为求解此类问题的标准模型使用。
基金the National Key Research and Development Program of China(Grant No.2020YFA0607900)the National Natural Science Foundation of China(Grant Nos.42176019 and 11874061)the Youth Innovation Promotion Association CAS(Grant No.2021023).
文摘An ocean-acoustic joint model is developed for research of acoustic propagation uncertainty in internal wave environments.The internal waves are numerically produced by tidal forcing over a continental slope using an ocean model.Three parameters(i.e.,internal wave,source depth,and water depth)contribute to the dynamic waveguide environments,and result in stochastic sound fields.The sensitivity of the transmission loss(TL)to environment parameters,statistical characteristics of the TL variation,and the associated physical mechanisms are investigated by the Sobol sensitivity analysis method,the Monte Carlo sampling,and the coupled normal mode theory,respectively.The results show that the TL is most sensitive to the source depth in the near field,resulted from the initial amplitudes of higher-order modes;while in middle and far fields,the internal waves are responsible for more than 80%of the total acoustic propagation contribution.In addition,the standard deviation of the TL in the near field and the shallow layer is smaller than those in the middle and far fields and the deep layer.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11434012 and 41561144006
文摘We present a passive geoacoustic inversion method using two hydrophones, which combines noise interferometry and time reversal mirror （TRM） techniques. Numerical simulations are firstly performed, in which strong fo- cusing occurs in the vicinity of one hydrophone when Green＇s function （GF） is back-propagated from the other hydrophone, with the position and strength of the focus being sensitive to sound speed and density in the bottom. We next extract the GF from the noise cross-correlation function measured by two hydrophones with 8025-m distance in the Shallow Water ＇06 experiment. After realizing the TRM process, sound speed and density in the bottom are inverted by optimizing focusing of the back-propagated GF. The passive inversion method is inherently environmentally friendly and low-cost.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11125420 and 11174312the Knowledge Innovation Project of the Chinese Academy of Sciences.
文摘A coupled-mode method for three-dimensional acoustic propagation and scattering in two-dimensional waveguides is presented.This method synthesizes the three-dimensional field solution by using Fourier transform techniques based on a sequence of two-dimensional problems,each of which is solved by a numerical model recently developed by Luo et al.[Chin.Phys.Lett.29(2012)014302].Numerical results indicate that the present model is remarkably accurate,and thus can serve as benchmark against other numerical models.In addition,this model can be applied to realistic problems,and can also be used to analyze horizontal refraction in some range-dependent waveguides in reality,such as the continental shelf environment,ridge-like bathymetry,and underwater trenches.
