P2D-5 Time-Reversal of Photo-Acoustic Waves Generated by Optical Contrasts in an Optically Diffusive Tissue Phantom

2006 ◽  
Author(s):  
M. Tanter ◽  
M. Fink ◽  
E. Bossy ◽  
K. Daoudi ◽  
A.-C. Boccara
Keyword(s):  
Time Reversal ◽  
Acoustic Waves ◽  
Tissue Phantom

Backscattering time‐reversal of acoustic waves in random media

1999 ◽  
Vol 105 (2) ◽  
pp. 956-956
Author(s):  
Arnaud Tourin ◽  
Arnaud Derode ◽  
Mathias Fink
Keyword(s):  
Time Reversal ◽  
Acoustic Waves ◽  
Random Media

Dynamic time reversal of randomly backscattered acoustic waves

1999 ◽  
Vol 47 (2) ◽  
pp. 175-181 ◽  
Author(s):  
A Tourin ◽  
A Derode ◽  
M Fink
Keyword(s):  
Time Reversal ◽  
Acoustic Waves ◽  
Dynamic Time

Experimental investigation of time-reversal of photo-acoustic waves

2006 ◽  
Author(s):  
Emmanuel Bossy ◽  
Gabriel Montaldo ◽  
Michael Tanter ◽  
Benoit Forget ◽  
François Ramaz ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Time Reversal ◽  
Acoustic Waves

scholarly journals Partial Discharge Localization Using Time Reversal: Application to Power Transformers

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1419 ◽  
Author(s):  
Hamidreza Karami ◽  
Mohammad Azadifar ◽  
Amirhossein Mostajabi ◽  
Marcos Rubinstein ◽  
Hossein Karami ◽  
...  
Keyword(s):  
Time Reversal ◽  
Acoustic Waves ◽  
Partial Discharge ◽  
Back Propagation ◽  
Cost Effective ◽  
Power Transformers ◽  
Proof Of Concept ◽  
Single Sensor ◽  
First Time ◽  
The Waves

In this work, we present a novel technique to locate partial discharge (PD) sources based on the concept of time reversal. The localization of the PD sources is of interest for numerous applications, including the monitoring of power transformers, Gas Insulated Substations, electric motors, super capacitors, or any other device or system that can suffer from PDs. To the best of the authors’ knowledge, this is the first time that the concept of time reversal is applied to localize PD sources. Partial discharges emit both electromagnetic and acoustic waves. The proposed method can be used to localize PD sources using either electromagnetic or acoustic waves. As a proof of concept, we present only the results for the electromagnetic case. The proposed method consists of three general steps: (1) recording of the waves from the PD source(s) via proper sensor(s), (2) the time-reversal and back-propagation of the recorded signal(s) into the medium using numerical simulations, and (3) the localization of focal spots. We demonstrate that, unlike the conventional techniques based on the time difference of arrival, the proposed time reversal method can accurately localize PD sources using only one sensor. As a result, the proposed method is much more cost effective compared to existing techniques. The performance of the proposed method is tested considering practical scenarios in which none of the former developed methods can provide reasonable results. Moreover, the proposed method has the unique advantage of being able to locate multiple simultaneous PD sources and doing so with a single sensor. The efficiency of the method against the variation in the polarization of the PDs, their length, and against environmental noise is also investigated. Finally, the validity of the proposed procedure is tested against experimental observations.

NUMERICAL AND EXPERIMENTAL TIME-REVERSAL OF ACOUSTIC WAVES IN RANDOM MEDIA

2001 ◽  
Vol 09 (03) ◽  
pp. 993-1003 ◽  
Author(s):  
ARNAUD DERODE ◽  
MICKAËL TANTER ◽  
ARNAUD TOURIN ◽  
LAURENT SANDRIN ◽  
MATHIAS FINK
Keyword(s):  
Time Reversal ◽  
Acoustic Waves ◽  
Random Media ◽  
Initial Conditions ◽  
Classical Mechanics ◽  
High Sensitivity ◽  
Amount Of Information ◽  
Simulation Based ◽  
Initial Source ◽  
Time Invariant

In classical mechanics, a time-reversal experiment with a large number of particles is impossible. Because of the high sensitivity to initial conditions, one would need to resolve the positions and velocities of each particle with infinite accuracy. Thus, it would require an infinite amount of information, which is of course out of reach. In wave physics however, the amount of information required to describe a wave field is limited and depends on the shortest wavelength of the field. Thus we can propose an acoustic equivalent of the experiment we mentioned above. We start with a coherent transient pulse, let it propagate through a disordered highly scattering medium, then record the scattered field and time-reverse it: surprisingly, it travels back to its initial source, which is not predictable by usual theories for random media. Indeed, to study waves propagation in disordered media theoreticians, who find it difficult to deal with one realization of disorder, use concepts defined as an average over the realizations, which naturally leads to the diffusion approximation. But the corresponding equation is not time-reversal invariant and thus fails in describing our experiment. Then, to understand our experimental results and try to predict new ones, we have developed a finite elements simulation based on the real microscopic time-invariant equation of propagation. The experimental and numerical results are found to be in very good agreement.

scholarly journals Self-Navigated 3D Acoustic Tweezers in Complex Media Based on Time Reversal

Research ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Ye Yang ◽  
Teng Ma ◽  
Sinan Li ◽  
Qi Zhang ◽  
Jiqing Huang ◽  
...  
Keyword(s):  
Time Reversal ◽  
Acoustic Waves ◽  
Heterogeneous Media ◽  
Ex Vivo ◽  
Particle Manipulation ◽  
Practical Applications ◽  
Wide Range ◽  
Acoustic Tweezers ◽  
Human Skulls ◽  
Ultrasonic Images

Acoustic tweezers have great application prospects because they allow noncontact and noninvasive manipulation of microparticles in a wide range of media. However, the nontransparency and heterogeneity of media in practical applications complicate particle trapping and manipulation. In this study, we designed a 1.04 MHz 256-element 2D matrix array for 3D acoustic tweezers to guide and monitor the entire process using real-time 3D ultrasonic images, thereby enabling acoustic manipulation in nontransparent media. Furthermore, we successfully performed dynamic 3D manipulations on multiple microparticles using multifoci and vortex traps. We achieved 3D particle manipulation in heterogeneous media (through resin baffle and ex vivo macaque and human skulls) by introducing a method based on the time reversal principle to correct the phase and amplitude distortions of the acoustic waves. Our results suggest cutting-edge applications of acoustic tweezers such as acoustical drug delivery, controlled micromachine transfer, and precise treatment.

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