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
It is better to use a simple configuration to enhance the matched-field inversion method based on a horizontal line applicability of ocean environment inversion in shallow water. A array （HLA） is used to retrieve th...It is better to use a simple configuration to enhance the matched-field inversion method based on a horizontal line applicability of ocean environment inversion in shallow water. A 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
Time-reversal processing(TRP) is an implementation of matched-field processing(MFP) where the ocean itself is used to construct the replica field.This paper introduces virtual time-reversal processing(VTRP) that is im...Time-reversal processing(TRP) is an implementation of matched-field processing(MFP) where the ocean itself is used to construct the replica field.This paper introduces virtual time-reversal processing(VTRP) that is implemented electronically at a receiver array and simulates the kind of processing that would be done by an actual TRP during the reciprocal propagation stage.MFP is a forward propagation process,while VTRP is a back-propagation process,which exploits the properties of reciprocity and superposition and is realized by weighting the replica surface with the complex conjugate of the data received on the corresponding element,followed by summation of the processed received data.The number of parabolic equation computational grids of VTRP is much smaller than that of MFP in a range-dependent waveguide.As a result,the localization surface of VTRP can be formed faster than its MFP counterpart in a range-dependent waveguide.The performance of VTRP for source localization is validated through numerical simulations and data from the Mediterranean Sea.展开更多
This paper presents an approach to the challenging is- sue of passive source localization in shallow water using a mobile short horizontal linear array with length less than ten meters. The short array can be convenie...This paper presents an approach to the challenging is- sue of passive source localization in shallow water using a mobile short horizontal linear array with length less than ten meters. The short array can be conveniently placed on autonomous underwa- ter vehicles and deployed for adaptive spatial sampling. However, the use of such small aperture passive sonar systems makes it difficult to acquire sufficient spatial gain for localizing long-range sources. To meet the requirement, a localization approach that employs matched-field based techniques that enable the short ho- rizontal linear array is used to passively localize acoustic sources in shallow water. Furthermore, the broadband processing and inter-position processing provide robustness against ocean en- vironmental mismatch and enhance the stability of the estimation process. The proposed approach＇s ability to localize acoustic sources in shallow water at different signal-to-noise ratios is examined through the synthetic test cases where the sources are located at the endfire and some other bearing of the mobile short horizontal linear array. The presented results demonstrate that the positional parameters of the estimated source build up over time as the array moves at a low speed along a straight line at a constant depth.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 matched-field inversion method based on a horizontal line applicability of ocean environment inversion in shallow water. A 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 (10774119)the Program for New Century Excellent Talents in University (NCET-08-0455)the Natural Science Foundation of Shaanxi Province,China (SJ08F07)
文摘Time-reversal processing(TRP) is an implementation of matched-field processing(MFP) where the ocean itself is used to construct the replica field.This paper introduces virtual time-reversal processing(VTRP) that is implemented electronically at a receiver array and simulates the kind of processing that would be done by an actual TRP during the reciprocal propagation stage.MFP is a forward propagation process,while VTRP is a back-propagation process,which exploits the properties of reciprocity and superposition and is realized by weighting the replica surface with the complex conjugate of the data received on the corresponding element,followed by summation of the processed received data.The number of parabolic equation computational grids of VTRP is much smaller than that of MFP in a range-dependent waveguide.As a result,the localization surface of VTRP can be formed faster than its MFP counterpart in a range-dependent waveguide.The performance of VTRP for source localization is validated through numerical simulations and data from the Mediterranean Sea.
基金supported by the State Scholarship Fund(2011611091)supported by China Shipbuilding Industry Corporation
文摘This paper presents an approach to the challenging is- sue of passive source localization in shallow water using a mobile short horizontal linear array with length less than ten meters. The short array can be conveniently placed on autonomous underwa- ter vehicles and deployed for adaptive spatial sampling. However, the use of such small aperture passive sonar systems makes it difficult to acquire sufficient spatial gain for localizing long-range sources. To meet the requirement, a localization approach that employs matched-field based techniques that enable the short ho- rizontal linear array is used to passively localize acoustic sources in shallow water. Furthermore, the broadband processing and inter-position processing provide robustness against ocean en- vironmental mismatch and enhance the stability of the estimation process. The proposed approach＇s ability to localize acoustic sources in shallow water at different signal-to-noise ratios is examined through the synthetic test cases where the sources are located at the endfire and some other bearing of the mobile short horizontal linear array. The presented results demonstrate that the positional parameters of the estimated source build up over time as the array moves at a low speed along a straight line at a constant depth.
