Focal depth shifting of a time reversal mirror in a range-independent waveguide

Roux, Philippe; Kuperman, W. A.

doi:10.1121/1.1940447

Cited by 13 publications

(4 citation statements)

References 15 publications

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“…and test many parameters over a wide range of magnitude. Several earth sciences laboratories have already decided to develop analogous experiments for methodological developments, as in San Diego-California [18], Colorado [19][20][21], Tsukuba-Japan [22], Paris-France [23,24] and more recently in Grenoble-France [25] to cite only a few. Our article presents some analogous ultrasonic experiments not only devoted to the study of the physics of wave propagation in heterogeneous media, but also to the development of new techniques applicable to seismic waves in geosciences.…”

Section: Seismic Noisementioning

confidence: 99%

Mesoscopics of ultrasound and seismic waves: application to passive imaging

Larose

2006

Ann. Phys. Fr.

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This manuscript deals with different aspects of the propagation of acoustic and seismic waves in heterogeneous media, both simply and multiply scattering ones. After a short introduction on conventional imaging techniques, we describe two observations that demonstrate the presence of multiple scattering in seismic records: the equipartition principle, and the coherent backscattering effect (Chap. 2). Multiple scattering is related to the mesoscopic nature of seismic and acoustic waves, and is a strong limitation for conventional techniques like medical or seismic imaging. In the following part of the manuscript (Chaps. 3-5), we present an application of mesoscopic physics to acoustic and seismic waves: the principle of passive imaging. By correlating records of ambient noise or diffuse waves obtained at two passive sensors, it is possible to reconstruct the impulse response of the medium as if a source was placed at one sensor. This provides the opportunity of doing acoustics and seismology without a source. Several aspects of this technique are presented here, starting with theoretical considerations and numerical simulations (Chaps. 3, 4). Then we present experimental applications (Chap. 5) to ultrasound (passive tomography of a layered medium) and to seismic waves (passive imaging of California, and the Moon, with micro-seismic noise).

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Section: Seismic Noisementioning

confidence: 99%

Mesoscopics of ultrasound and seismic waves: application to passive imaging

Larose

2006

Ann. Phys. Fr.

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“…19) In the method of vertically moving the focus, the depth of focus is moved by mode modulation. 20) Because this method changes depth using a mode ratio, the phase of modes is not preserved.…”

Section: Introductionmentioning

confidence: 99%

Focal Depth Shifting of Phase-Conjugate Wave in Pekeris Waveguide

Tsurugaya¹,

Kikuchi

Mizutani

2008

jjap

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We present a new numerical method of obtaining critical temperatures and exponents for ferromagnetic spin models and dynamical transitions. This method is based on the spreading of damage in a temperature gradient. We illustrate the method on the two-dimensional lsing model and present new results on the + king spin glass in two dimensions. We also obtain new critical exponents, describing the behaviour of the width and the length o f the damage front.

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“…It is shown in a time domain by the following equation though Eq. (1) is a presentation form in a frequency domain [2], The researches on time reversal increase it in the field of underwater acoustics [1][2][3][4][5][6][7][8][9]. The research that processed a time reversal to a reflected wave from an object has recently developed remarkably [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Time reversal processing to forward scattering waves of underwater targets

Tsurugaya

Kikuchi

Mizutani

2008

The Journal of the Acoustical Society of America

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This paper presents a detection of underwater targets using a time reversal. When a target exists between a sound source and a time reversal array in shallow water, the time reversal array receive sound waves from the sound source and waves scattered by the target. If a time reversal processing to them is carried out and they are re-transmitted from the time reversal array, it will be thought that they are converged at the position of the sound source and the target. However, since the waves converging at the sound source have a high level, the waves converging at the target position are usually masked by the high level sounds. Then, we cannot observe the waves converged at the target. We eliminate only the high level sounds from the sound fields. In each array element, the signals in case of non target are subtracted from the signals including the target. As a result of subtraction, the components of the scattering wave by the target are left on the array elements. The time reversal fields of the scattering wave are constructed by radiating the components of the scattered waves from each element again.

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Focal depth shifting of a time reversal mirror in a range-independent waveguide

Cited by 13 publications

References 15 publications

Mesoscopics of ultrasound and seismic waves: application to passive imaging

Mesoscopics of ultrasound and seismic waves: application to passive imaging

Focal Depth Shifting of Phase-Conjugate Wave in Pekeris Waveguide

Time reversal processing to forward scattering waves of underwater targets

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