Time-reversal focusing of elastic waves in inhomogeneous media: an application to an elastic-wave landmine detection system

Norville, Pelham D.; Scott, Waymond R.

doi:10.1117/12.603980

Cited by 2 publications

(1 citation statement)

References 9 publications

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“…This desire stems from the use of time reversal to enhance the response of buried objects by focusing seismic energy in time and space. [7][8][9][10] Norville and Scott 11 report an experimental study of time-reversal focusing of elastic surface waves scattered by a buried object. In that work, they also describe an algorithm for estimating the surface motion detected by the LDVs by iterative convolution of an appropriate Green's function with the response due to each source.…”

Section: Introductionmentioning

confidence: 99%

Green’s functions for a volume source in an elastic half-space

Zabolotskaya¹,

Ilinskii²,

Hay³

et al. 2012

The Journal of the Acoustical Society of America

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Green's functions are derived for elastic waves generated by a volume source in a homogeneous isotropic half-space. The context is sources at shallow burial depths, for which surface (Rayleigh) and bulk waves, both longitudinal and transverse, can be generated with comparable magnitudes. Two approaches are followed. First, the Green's function is expanded with respect to eigenmodes that correspond to Rayleigh waves. While bulk waves are thus ignored, this approximation is valid on the surface far from the source, where the Rayleigh wave modes dominate. The second approach employs an angular spectrum that accounts for the bulk waves and yields a solution that may be separated into two terms. One is associated with bulk waves, the other with Rayleigh waves. The latter is proved to be identical to the Green's function obtained following the first approach. The Green's function obtained via angular spectrum decomposition is analyzed numerically in the time domain for different burial depths and distances to the receiver, and for parameters relevant to seismo-acoustic detection of land mines and other buried objects.

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Section: Introductionmentioning

confidence: 99%

Green’s functions for a volume source in an elastic half-space

Zabolotskaya¹,

Ilinskii²,

Hay³

et al. 2012

The Journal of the Acoustical Society of America

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Wideband nonlinear time reversal seismo-acoustic method for landmine detection

Sutin

Libbey

Fillinger

et al. 2009

The Journal of the Acoustical Society of America

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Acoustic and seismic waves provide a method to localize compliant mines by vibrating the top plate and a thin soil layer above the mine. This vibration is mostly linear, but also includes a small nonlinear deviation. The main goal of this paper is to introduce a method of processing that uses phase-inversion to observe nonlinear effects in a wide frequency band. The method extracts a nonlinear part of surface velocity from two similar broadcast signals of opposite sign by summing and cancelling the linear components and leaving the nonlinear components. This phase-inversion method is combined with time reversal focusing to provide increased seismic vibration and enhance the nonlinear effect. The experiments used six loudspeakers in a wood box placed over sand in which inert landmines were buried. The nonlinear surface velocity of the sand with a mine compared to the sand without a mine was greater as compared to a linear technique.

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Time-reversal focusing of elastic waves in inhomogeneous media: an application to an elastic-wave landmine detection system

Cited by 2 publications

References 9 publications

Green’s functions for a volume source in an elastic half-space

Green’s functions for a volume source in an elastic half-space

Wideband nonlinear time reversal seismo-acoustic method for landmine detection

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