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Time reversal acoustics for small targets using decomposition of the time reversal operator.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Time reversal acoustics for small targets using decomposition of the time reversal operator./
Author:	Simko, Peter C.
Description:	1 online resource (139 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 70-08, Section: B, page: 5068.
Contained By:	Dissertation Abstracts International70-08B.
Subject:	Electrical engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9781109335200

Time reversal acoustics for small targets using decomposition of the time reversal operator.
Simko, Peter C.

Time reversal acoustics for small targets using decomposition of the time reversal operator. - 1 online resource (139 pages)

Source: Dissertation Abstracts International, Volume: 70-08, Section: B, page: 5068.

Thesis (Ph.D.)

Includes bibliographical references

The method of time reversal acoustics has been the focus of considerable interest over the last twenty years. Time reversal imaging methods have made consistent progress as effective methods for signal processing since the initial demonstration that physical time reversal methods can be used to form convergent wave fields on a localized target, even under conditions of severe multipathing. Computational time reversal methods rely on the properties of the so-called 'time reversal operator' in order to extract information about the target medium. Applications for which time reversal imaging have previously been explored include medical imaging, non-destructive evaluation, and mine detection. Emphasis in this paper will fall on two topics within the general field of computational time reversal imaging. First, we will examine previous work on developing a time reversal imaging algorithm based on the MUltiple SIgnal Classification (MUSIC) algorithm. MUSIC, though computationally very intensive, has demonstrated early promise in simulations using array-based methods applicable to true volumetric (three-dimensional) imaging. We will provide a simple algorithm through which the rank of the time reversal operator subspaces can be properly quantified so that the rank of the associated null subspace can be accurately estimated near the central pulse wavelength in broadband imaging. Second, we will focus on the scattering from small acoustically rigid two dimensional cylindrical targets of elliptical cross section. Analysis of the time reversal operator eigenmodes has been well-studied for symmetric response matrices associated with symmetric systems of scattering targets. We will expand these previous results to include more general scattering systems leading to asymmetric response matrices, for which the analytical complexity increases but the physical interpretation of the time reversal operator remains unchanged. For asymmetric responses, the qualitative properties of the time reversal operator eigenmodes remain consistent with those obtained from the more tightly constrained systems.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9781109335200Subjects--Topical Terms:

596380
Electrical engineering.
Index Terms--Genre/Form:

554714
Electronic books.

Time reversal acoustics for small targets using decomposition of the time reversal operator.
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100 1 $a Simko, Peter C. $3 1181015
245 1 0 $a Time reversal acoustics for small targets using decomposition of the time reversal operator.
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300 $a 1 online resource (139 pages)
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500 $a Source: Dissertation Abstracts International, Volume: 70-08, Section: B, page: 5068.
500 $a Adviser: Jafar Saniie.
502 $a Thesis (Ph.D.) $c Illinois Institute of Technology $d 2008.
504 $a Includes bibliographical references
520 $a The method of time reversal acoustics has been the focus of considerable interest over the last twenty years. Time reversal imaging methods have made consistent progress as effective methods for signal processing since the initial demonstration that physical time reversal methods can be used to form convergent wave fields on a localized target, even under conditions of severe multipathing. Computational time reversal methods rely on the properties of the so-called 'time reversal operator' in order to extract information about the target medium. Applications for which time reversal imaging have previously been explored include medical imaging, non-destructive evaluation, and mine detection. Emphasis in this paper will fall on two topics within the general field of computational time reversal imaging. First, we will examine previous work on developing a time reversal imaging algorithm based on the MUltiple SIgnal Classification (MUSIC) algorithm. MUSIC, though computationally very intensive, has demonstrated early promise in simulations using array-based methods applicable to true volumetric (three-dimensional) imaging. We will provide a simple algorithm through which the rank of the time reversal operator subspaces can be properly quantified so that the rank of the associated null subspace can be accurately estimated near the central pulse wavelength in broadband imaging. Second, we will focus on the scattering from small acoustically rigid two dimensional cylindrical targets of elliptical cross section. Analysis of the time reversal operator eigenmodes has been well-studied for symmetric response matrices associated with symmetric systems of scattering targets. We will expand these previous results to include more general scattering systems leading to asymmetric response matrices, for which the analytical complexity increases but the physical interpretation of the time reversal operator remains unchanged. For asymmetric responses, the qualitative properties of the time reversal operator eigenmodes remain consistent with those obtained from the more tightly constrained systems.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Electrical engineering. $3 596380
650 4 $a Acoustics. $3 670692
655 7 $a Electronic books. $2 local $3 554714
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710 2 $a Illinois Institute of Technology. $3 845498
773 0 $t Dissertation Abstracts International $g 70-08B.
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