A study on the self-adaptive focusing of acoustical beam in the solid by Time Reversal (TR) method is presented. The theoretical analyses and experiments show that TR can compensate the path difference of sound pulse ...A study on the self-adaptive focusing of acoustical beam in the solid by Time Reversal (TR) method is presented. The theoretical analyses and experiments show that TR can compensate the path difference of sound pulse in solid, and generate the self-focusing of longitudinal and shear waves at the same time. The experimental values of the focusing processing gain agree with the theoretical values.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
With the spatial-temporal focusing of acoustic energy,time reversal processing(TRP) shows the potential application for active target detection in shallow water.To turn the ‘potential’ into a reality,the TRP based o...With the spatial-temporal focusing of acoustic energy,time reversal processing(TRP) shows the potential application for active target detection in shallow water.To turn the ‘potential’ into a reality,the TRP based on a model source(MS) instead of a physical probe source(PS) is investigated.For uncertain ocean environments,the robustness of TRP is discussed for the narrowband and broadband signal respectively.The channel transfer function matrix is first constructed in the acoustic perturbation space.Then a steering vector for time reversal transmission is obtained by singular value decomposition(SVD) of the matrix.For verification of the robust TRP,the tank experiments of time reversal transmission focusing and its application for active target detection are undertaken.The experimental results have shown that the robust TRP can effectively detect and locate a small bottom target.展开更多
基金This project is supported by National Natural Science Foundation of China and the President Foundationof Institute of Acoustic
文摘A study on the self-adaptive focusing of acoustical beam in the solid by Time Reversal (TR) method is presented. The theoretical analyses and experiments show that TR can compensate the path difference of sound pulse in solid, and generate the self-focusing of longitudinal and shear waves at the same time. The experimental values of the focusing processing gain agree with the theoretical values.
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Project (Nos.60702022 and 60872066) supported by the National Natural Science Foundation of China
文摘With the spatial-temporal focusing of acoustic energy,time reversal processing(TRP) shows the potential application for active target detection in shallow water.To turn the ‘potential’ into a reality,the TRP based on a model source(MS) instead of a physical probe source(PS) is investigated.For uncertain ocean environments,the robustness of TRP is discussed for the narrowband and broadband signal respectively.The channel transfer function matrix is first constructed in the acoustic perturbation space.Then a steering vector for time reversal transmission is obtained by singular value decomposition(SVD) of the matrix.For verification of the robust TRP,the tank experiments of time reversal transmission focusing and its application for active target detection are undertaken.The experimental results have shown that the robust TRP can effectively detect and locate a small bottom target.
