A sound speed profile plays an important role in shallow water sound propagation.Concurrent with in-situ measurements,many inversion methods,such as matched-field inversion,have been put forward to invert the sound sp...A sound speed profile plays an important role in shallow water sound propagation.Concurrent with in-situ measurements,many inversion methods,such as matched-field inversion,have been put forward to invert the sound speed profile from acoustic signals.However,the time cost of matched-field inversion may be very high in replica field calculations.We studied the feasibility and robustness of an acoustic tomography scheme with matched-field processing in shallow water,and described the sound speed profile by empirical orthogonal functions.We analyzed the acoustic signals from a vertical line array in ASIAEX2001 in the East China Sea to invert sound speed profiles with estimated empirical orthogonal functions and a parallel genetic algorithm to speed up the inversion.The results show that the inverted sound speed profiles are in good agreement with conductivity-temperature-depth measurements.Moreover,a posteriori probability analysis is carried out to verify the inversion results.展开更多
The spatial correlations of acoustic field have important implications for underwater target detection and other applications in deep water. In this paper, the spatial correlations of the high intensity zone in the de...The spatial correlations of acoustic field have important implications for underwater target detection and other applications in deep water. In this paper, the spatial correlations of the high intensity zone in the deep-water acoustic field are investigated by using the experimental data obtained in the South China Sea. The experimental results show that the structures of the spatial correlation coefficient at different ranges and depths are similar to the transmission loss structure in deep water. The main reason for this phenomenon is analyzed by combining the normal mode theory with the ray theory. It is shown that the received signals in the high intensity zone mainly include one or two main pulses which are contributed by the interference of a group of waterborne modes with similar phases. The horizontal-longitudinal correlations at the same receiver depth but in different high intensity zones are analyzed. At some positions, more pulses are received in the arrival structure of the signal due to bottom reflection and the horizontal-longitudinal correlation coefficient decreases accordingly.The multi-path arrival structure of receiving signal becomes more complex with increasing receiver depth.展开更多
We simulated the temporal correlation of sound transmission using a two-dimensional advective frozen-ocean model with temperature data from a temperature sensor array on a propagation path in the South China Sea(SCS) ...We simulated the temporal correlation of sound transmission using a two-dimensional advective frozen-ocean model with temperature data from a temperature sensor array on a propagation path in the South China Sea(SCS) Experiment 2009,and investigated the relationships of temporal correlation length,source-receiver range,and maximal sound speed fluctuation mainly caused by the solitary internal waves.We found that the temporal correlation length is-1.2-power dependent on source-receiver range and-0.9-power dependent on maximal sound speed fluctuation.The empirical relationship is deduced from one-day environmental measurements in a limited area,needing more works and verification in the future with more acoustic data.But the relationship is useful in many applications in the area of SCS Experiment 2009.展开更多
We performed a long range acoustic propagation experiment in the South China Sea(SCS) in November 2004.The environment of the experiment was with an isothermal sound speed profile,where influence of water volume fluct...We performed a long range acoustic propagation experiment in the South China Sea(SCS) in November 2004.The environment of the experiment was with an isothermal sound speed profile,where influence of water volume fluctuation was small,meaning that bottom parameters can be well estimated from acoustic signals.We inverted the acoustic parameters of sediment by using a hybrid inversion scheme that combines the matched field processing inversion with Hamilton sediment empirical relationship and transmission loss data.The numerical results show excellent agreement with the experiment data,indicating validity of the inverted parameters.展开更多
The received shock waves produced by explosive charges are often polluted by bubble pulses in underwater acoustic experiments.A method based on warping operators is proposed to cancel the bubble pulses in the time-fre...The received shock waves produced by explosive charges are often polluted by bubble pulses in underwater acoustic experiments.A method based on warping operators is proposed to cancel the bubble pulses in the time-frequency domain.This is applied to the explosive data collected during the Yellow Sea experiment in November 2000.The original received signal is first transformed into a warped signal by warping operators.Then,the warped signal is analyzed in the time-frequency domain.Due to the different features between the shock waves and the bubble pulses in the time-frequency domain for the warped signal,the bubble pulses can be easily filtered out.Furthermore,the shock waves in the original time domain can be retrieved by the inverse warping transformation.The autocorrelation functions and the time-frequency representation show that the bubble pulses can be canceled effectively.展开更多
The sensitivities of the normal modes arrival time to solitary internal waves(IWs) are analyzed by using the SW06 environments.Simulation results show that the arrival time of mode 1 is relatively stable.But,there are...The sensitivities of the normal modes arrival time to solitary internal waves(IWs) are analyzed by using the SW06 environments.Simulation results show that the arrival time of mode 1 is relatively stable.But,there are some higher-order normal modes which arrive earlier than mode 1,and fluctuate with the appearance of solitary IWs.Explanation of the phenomenon is given based on ray theory.It is shown that,when thermocline falls down to some depths,those higher-order modes with a group of definite grazing angles mainly propagate above the thermocline and arrive earlier.展开更多
It is better to use a simple configuration to enhance the applicability of ocean environment inversion in shallow water.A matched-field inversion method based on a horizontal line array(HLA)is used to retrieve the var...It is better to use a simple configuration to enhance the applicability of ocean environment inversion in shallow water.A matched-field inversion method based on a horizontal line array(HLA)is used to retrieve the variation of sound speed profile.The performance of the inversion method is verified in the South China Sea in June,2010.An HLA laid at bottom was used to receive signals from a bottom-mounted transducer.Inverted mean sound speed profiles from 9-hour long acoustic signals are in good agreement with measurements from two temperature chains at the sites of the source and receiver.The results show that an HLA can be used to monitor the variability of shallow-water sound speed profile.展开更多
In this paper,a modified warping operator for homogeneous shallow water based on the Beam-Displacement Ray-Mode(BDRM)theory is presented.According to the BDRM theory,the contribution of the beam displacement and the t...In this paper,a modified warping operator for homogeneous shallow water based on the Beam-Displacement Ray-Mode(BDRM)theory is presented.According to the BDRM theory,the contribution of the beam displacement and the time delay to the group velocity can be easily considered in a shallow water waveguide.A more accurate dispersion formula is derived by using the cycle distance formula to calculate the group velocity of normal modes.The derived dispersion formula can be applied to the homogeneous shallow water waveguide.Theoretically,the formula is related to the phase of the reflection coefficient and suitable for various bottom models.Furthermore,based on the derived dispersion relation,the modified warping operator is developed to obtain linear modal structures.For the Pekeris model,the formulae for the phase of the reflection coefficient are derived in this work.By taking account of the effect of the bottom attenuation on the reflection coefficient,the formula for the phase of the reflection coefficient including the bottom attenuation is obtained for the Pekeris model with a lossy bottom.Performance and accuracy of different formulae are evaluated and compared.The numerical simulations indicate that the derived dispersion formulae and the modified warping operator are more accurate.展开更多
In order to improve the ability to localize a source in an uncertain acoustic environment,a Bayesian approach,referred to here as Bayesian localization is used by including the environment in the parameter search spac...In order to improve the ability to localize a source in an uncertain acoustic environment,a Bayesian approach,referred to here as Bayesian localization is used by including the environment in the parameter search space.Genetic algorithms are used for the parameter optimization.This method integrates the a posterior probability density(PPD) over environmental parameters to obtain a sequence of marginal probability distributions over source range and depth,from which the most-probable source location and localization uncertainties can be extracted.Considering that the seabed density and attenuation are less sensitive to the objective function of matched field processing,we utilize the empirical relationship to invert those parameters indirectly.The broadband signals recorded by a vertical line array in a Yellow Sea experiment in 2000 are processed and analyzed.It was found that,the Bayesian localization method that incorporates the environmental variability into the processor,made it robust to the uncertainty in the ocean environment.In addition,using the empirical relationship could enhance the localization accuracy.展开更多
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCX1-YW-12-02)the National Natural Science Foundation of China (Nos.10974218,10734100)
文摘A sound speed profile plays an important role in shallow water sound propagation.Concurrent with in-situ measurements,many inversion methods,such as matched-field inversion,have been put forward to invert the sound speed profile from acoustic signals.However,the time cost of matched-field inversion may be very high in replica field calculations.We studied the feasibility and robustness of an acoustic tomography scheme with matched-field processing in shallow water,and described the sound speed profile by empirical orthogonal functions.We analyzed the acoustic signals from a vertical line array in ASIAEX2001 in the East China Sea to invert sound speed profiles with estimated empirical orthogonal functions and a parallel genetic algorithm to speed up the inversion.The results show that the inverted sound speed profiles are in good agreement with conductivity-temperature-depth measurements.Moreover,a posteriori probability analysis is carried out to verify the inversion results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11434012 and 41561144006)
文摘The spatial correlations of acoustic field have important implications for underwater target detection and other applications in deep water. In this paper, the spatial correlations of the high intensity zone in the deep-water acoustic field are investigated by using the experimental data obtained in the South China Sea. The experimental results show that the structures of the spatial correlation coefficient at different ranges and depths are similar to the transmission loss structure in deep water. The main reason for this phenomenon is analyzed by combining the normal mode theory with the ray theory. It is shown that the received signals in the high intensity zone mainly include one or two main pulses which are contributed by the interference of a group of waterborne modes with similar phases. The horizontal-longitudinal correlations at the same receiver depth but in different high intensity zones are analyzed. At some positions, more pulses are received in the arrival structure of the signal due to bottom reflection and the horizontal-longitudinal correlation coefficient decreases accordingly.The multi-path arrival structure of receiving signal becomes more complex with increasing receiver depth.
基金Supported by Knowledge Innovation Program of the Chinese Academy of Sciences under Grant No KZCX1-YW-12-2, and the National Natural Science Foundation of China under Grant No 10734100.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No.KZCX1-YW-12-02)the National Natural Science Foundation of China (Nos.10974218,10734100)
文摘We simulated the temporal correlation of sound transmission using a two-dimensional advective frozen-ocean model with temperature data from a temperature sensor array on a propagation path in the South China Sea(SCS) Experiment 2009,and investigated the relationships of temporal correlation length,source-receiver range,and maximal sound speed fluctuation mainly caused by the solitary internal waves.We found that the temporal correlation length is-1.2-power dependent on source-receiver range and-0.9-power dependent on maximal sound speed fluctuation.The empirical relationship is deduced from one-day environmental measurements in a limited area,needing more works and verification in the future with more acoustic data.But the relationship is useful in many applications in the area of SCS Experiment 2009.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCX1-YW-12-02)the National Natural Science Foundation of China (Nos.10974218 and 10734100)
文摘We performed a long range acoustic propagation experiment in the South China Sea(SCS) in November 2004.The environment of the experiment was with an isothermal sound speed profile,where influence of water volume fluctuation was small,meaning that bottom parameters can be well estimated from acoustic signals.We inverted the acoustic parameters of sediment by using a hybrid inversion scheme that combines the matched field processing inversion with Hamilton sediment empirical relationship and transmission loss data.The numerical results show excellent agreement with the experiment data,indicating validity of the inverted parameters.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11174312 and 11074269.
文摘The received shock waves produced by explosive charges are often polluted by bubble pulses in underwater acoustic experiments.A method based on warping operators is proposed to cancel the bubble pulses in the time-frequency domain.This is applied to the explosive data collected during the Yellow Sea experiment in November 2000.The original received signal is first transformed into a warped signal by warping operators.Then,the warped signal is analyzed in the time-frequency domain.Due to the different features between the shock waves and the bubble pulses in the time-frequency domain for the warped signal,the bubble pulses can be easily filtered out.Furthermore,the shock waves in the original time domain can be retrieved by the inverse warping transformation.The autocorrelation functions and the time-frequency representation show that the bubble pulses can be canceled effectively.
基金supported by the National Natural Science Foundation of China(11174312,11125420)the Office of Naval Research,USA
文摘The sensitivities of the normal modes arrival time to solitary internal waves(IWs) are analyzed by using the SW06 environments.Simulation results show that the arrival time of mode 1 is relatively stable.But,there are some higher-order normal modes which arrive earlier than mode 1,and fluctuate with the appearance of solitary IWs.Explanation of the phenomenon is given based on ray theory.It is shown that,when thermocline falls down to some depths,those higher-order modes with a group of definite grazing angles mainly propagate above the thermocline and arrive earlier.
基金supported by the National Natural Science Foundation of China(Grant Nos.11434012,11404366,11125420 and 11074269)
文摘It is better to use a simple configuration to enhance the applicability of ocean environment inversion in shallow water.A matched-field inversion method based on a horizontal line array(HLA)is used to retrieve the variation of sound speed profile.The performance of the inversion method is verified in the South China Sea in June,2010.An HLA laid at bottom was used to receive signals from a bottom-mounted transducer.Inverted mean sound speed profiles from 9-hour long acoustic signals are in good agreement with measurements from two temperature chains at the sites of the source and receiver.The results show that an HLA can be used to monitor the variability of shallow-water sound speed profile.
基金supported by the National Natural Science Foundation of China(Grant Nos.11174312 and 11074269)
文摘In this paper,a modified warping operator for homogeneous shallow water based on the Beam-Displacement Ray-Mode(BDRM)theory is presented.According to the BDRM theory,the contribution of the beam displacement and the time delay to the group velocity can be easily considered in a shallow water waveguide.A more accurate dispersion formula is derived by using the cycle distance formula to calculate the group velocity of normal modes.The derived dispersion formula can be applied to the homogeneous shallow water waveguide.Theoretically,the formula is related to the phase of the reflection coefficient and suitable for various bottom models.Furthermore,based on the derived dispersion relation,the modified warping operator is developed to obtain linear modal structures.For the Pekeris model,the formulae for the phase of the reflection coefficient are derived in this work.By taking account of the effect of the bottom attenuation on the reflection coefficient,the formula for the phase of the reflection coefficient including the bottom attenuation is obtained for the Pekeris model with a lossy bottom.Performance and accuracy of different formulae are evaluated and compared.The numerical simulations indicate that the derived dispersion formulae and the modified warping operator are more accurate.
基金supported by the National Natural Science Foundation of China(11434012,41561144006,10974218,11174312)the Key Laboratory of Marine Surveying and Charting in Universities of Shandong(Shandong University of Science and Technology)(2013A02)+3 种基金the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents under Grant(2014RCJJ004)the Project of the Public Science and Technology Research Funds Projects of Ocean(201305034)the National Key Technology R&D Program(2012BAB16B01)State Key Laboratory of Acoustics,Chinese Academy of Sciences(SKLA201407)
文摘In order to improve the ability to localize a source in an uncertain acoustic environment,a Bayesian approach,referred to here as Bayesian localization is used by including the environment in the parameter search space.Genetic algorithms are used for the parameter optimization.This method integrates the a posterior probability density(PPD) over environmental parameters to obtain a sequence of marginal probability distributions over source range and depth,from which the most-probable source location and localization uncertainties can be extracted.Considering that the seabed density and attenuation are less sensitive to the objective function of matched field processing,we utilize the empirical relationship to invert those parameters indirectly.The broadband signals recorded by a vertical line array in a Yellow Sea experiment in 2000 are processed and analyzed.It was found that,the Bayesian localization method that incorporates the environmental variability into the processor,made it robust to the uncertainty in the ocean environment.In addition,using the empirical relationship could enhance the localization accuracy.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX1-YW-12-2)the National Natural Science Foundation of China(10974218 and 10734100)
