Acoustic Time-Reversal Mirrors

Fink, Mathias; Prada, Claire

doi:10.1007/3-540-44680-x_2

Cited by 144 publications

(154 citation statements)

References 33 publications

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“…However, it may be found in several alternative forms. For example, in [15] it is stated that one may force either just the field variable or the field variable and its first derivative recorded in the forward process. In the case of elastic wave propagation, a similar formulation is found in [25] where displacements' reversed time history is imposed on points of sensors that record the response.…”

Section: The Time Reversal Processmentioning

confidence: 99%

“…Wave paths that were traversed in the forward propagation step are now reproduced in the backward one [3]. Ideal conditions for the time reversal process would be those corresponding to the case where receivers fill the whole medium (or its entire boundary), recording the field and its derivatives [15], without any noise [16]. The time reversibility is based on the spatial reciprocity (symmetry in engineering) and the time reversal invariance (under the transformation t→ − t) of linear wave equations.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Time Reversal in Elastodynamics and Applications to Structural Health Monitoring

Panagiotopoulos¹,

Petromichelakis²,

Tsogka³

2015

Proceedings of the 5th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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Abstract. In structural health monitoring, detection of localized damage can be achieved by exploiting recorded signals at a limited number of sensors within the structure. Here we propose the localization of damage using an array of sensors as a computational time-reversal mirror (TRM). Time reversal (TR) is a physical process that exploits the time reversibility of wave equations and achieves re-focusing of the wave on the source of its origin by sending back, reversed in time, the signals recorded on an array of transducers. TR was originally introduced by Mathias Fink and his group and has several applications ranging from medical imaging to telecommunications [14].In the present work, we perform time reversal numerically in order to effectively detect and localize defects in a bounded two-dimensional elastic domain. This is a generalization of a respective time-reversal implementation in an acoustic medium [12]. The solid contains a number of N r sensors which can act as sources as well. Our data is the response matrix of the scattered field, that is, the difference between the total field obtained in the damaged structure and the incident field corresponding to the response in the healthy structure.Numerical solution of the wave propagation problem is performed using a mixed finite element formulation in terms of the velocity and stress fields [6]. In order to dissociate the response caused by N d different defects, we apply the singular value decomposition (SVD) of the response matrix, while back-propagation of the projection of each singular vector corresponding to a non-zero singular value is performed in order to highlight each defect separately.

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Section: The Time Reversal Processmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Time Reversal in Elastodynamics and Applications to Structural Health Monitoring

Panagiotopoulos¹,

Petromichelakis²,

Tsogka³

2015

Proceedings of the 5th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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show abstract

“…TRM algorithm performs coherent summation of sensor data to obtain an image. It was first used in acoustic by M. Fink [26]. The application of TRM in MITAT was initially suggested by Xu and Wang [27].…”

Section: Numerical Simulationsmentioning

confidence: 99%

An Integrated Simulation Approach and Experimental Research on Microwave Induced Thermo-Acoustic Tomography System

Song¹,

Zhao²,

Wang³

et al. 2013

PIER

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Abstract-Microwave induced thermo-acoustic tomography (MI-TAT) has great potential in early breast cancer detection because it utilizes the advantages of both microwave imaging and ultrasound imaging. In this paper, a fast and efficient simulation approach based on a hybrid method which combines finite integration time domain (FITD) method and pseudo-spectral time domain (PSTD) method is developed. By using this approach, energy deposition of biology tissue illuminated by electromagnetic fields can be accurately simulated. Meanwhile, acoustic properties of the tissue can be efficiently simulated as well. Based on this approach, a MITAT model is created and some simulated results are analyzed. Furthermore, some real breast tissues are adopted to perform the thermo-acoustic imaging experiment. Comparisons between experimental and simulated results are made. The feasibility and effectiveness of the proposed approach are demonstrated by both numerical simulations and experimental results.

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“…Since M. Fink and his group proposed the time reversal techniques in acoustics [15][16][17], research has been carried out in a variety of fields, from electromagnetism to underwater acoustics. Significant theoretical and experimental efforts have been made to improve the detection and imaging algorithms in a considerable scattering environment [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Performance of Time Reversal Based Underwater Target Detection in Shallow Water

Seo

2017

Applied Sciences

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Abstract:In this paper, a scheme based on the time reversal technique is proposed to improve the detection performance for detecting a cylindrical object bottoming at the seafloor in shallow water. When the time reversal technique is applied to the response of the clutter with the strong time-varying characteristic of shallow water, it is difficult to obtain a high peak response. However, in the case where a cylindrical object is placed on the seafloor because the time-invariant property of the target response is stronger than the time-varying property of the reverberation by the clutters, the time reversal technique can be applied to enhance the target signal. In this paper, it is demonstrated that the peak due to the target that is contacted at the seabed becomes higher when applying the time reversal technique. The performance is investigated by using numerical computation of the probability of detection for various probabilities of false alarm and computer simulation.

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Acoustic Time-Reversal Mirrors

Cited by 144 publications

References 33 publications

Time Reversal in Elastodynamics and Applications to Structural Health Monitoring

Time Reversal in Elastodynamics and Applications to Structural Health Monitoring

An Integrated Simulation Approach and Experimental Research on Microwave Induced Thermo-Acoustic Tomography System

Performance of Time Reversal Based Underwater Target Detection in Shallow Water

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