Time Reversal of Electromagnetic Waves in Randomly Layered Media PDF Download
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Author: Petr Glotov
Publisher:
ISBN:
Category :
Languages : en
Pages : 78
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Book Description
Time reversal is a general technique in wave propagation in inhomogeneous media when a signal is recorded at points of a device called time reversal mirror, gets time reversed and radiated back in the medium. The resulting field has a property of refocusing. Time reversal in acoustics has been extensively studied both experimentally and theoretically. In this thesis we consider the problem of time reversal of electromagnetic waves in inhomogeneous layered media. We use Markov process model for the medium parameters which allows us to exploit diffusion approximation theorem. We show that the field generated by the time reversal mirror focuses at a point of initial source inside of the medium. The size of the focusing spot is of the kind that it is smaller than the one that would be obtained if the medium were homogeneous meaning that the super resolution phenomenon is observed.
Author: Petr Glotov
Publisher:
ISBN:
Category :
Languages : en
Pages : 78
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Book Description
Time reversal is a general technique in wave propagation in inhomogeneous media when a signal is recorded at points of a device called time reversal mirror, gets time reversed and radiated back in the medium. The resulting field has a property of refocusing. Time reversal in acoustics has been extensively studied both experimentally and theoretically. In this thesis we consider the problem of time reversal of electromagnetic waves in inhomogeneous layered media. We use Markov process model for the medium parameters which allows us to exploit diffusion approximation theorem. We show that the field generated by the time reversal mirror focuses at a point of initial source inside of the medium. The size of the focusing spot is of the kind that it is smaller than the one that would be obtained if the medium were homogeneous meaning that the super resolution phenomenon is observed.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Time reversal is a general technique in wave propagation in inhomogeneous media when a signal is recorded at points of a device called time reversal mirror, gets time reversed and radiated back in the medium. The resulting field has a property of refocusing. Time reversal in acoustics has been extensively studied both experimentally and theoretically. In this thesis we consider the problem of time reversal of electromagnetic waves in inhomogeneous layered media. We use Markov process model for the medium parameters which allows us to exploit diffusion approximation theorem. We show that the field generated by the time reversal mirror focuses at a point of initial source inside of the medium. The size of the focusing spot is of the kind that it is smaller than the one that would be obtained if the medium were homogeneous meaning that the super resolution phenomenon is observed.
Author: Jean-Pierre Fouque
Publisher: Springer Science & Business Media
ISBN: 0387498087
Category : Science
Languages : en
Pages : 623
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Book Description
The content of this book is multidisciplinary by nature. It uses mathematical tools from the theories of probability and stochastic processes, partial differential equations, and asymptotic analysis, combined with the physics of wave propagation and modeling of time reversal experiments. It is addressed to a wide audience of graduate students and researchers interested in the intriguing phenomena related to waves propagating in random media. At the end of each chapter there is a section of notes where the authors give references and additional comments on the various results presented in the chapter.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
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Book Description
A time-reversal mirror is, roughly speaking, a device which is capable of receiving an acoustic signal in time, keeping it in memory and sending it back into the medium in the reversed direction of time. In this paper, we employ an accurate numerical method for simulating waves propagating in complex one-dimensional media. We use numerical simulations to reproduce the time-reversal self-averaging effect which takes place in randomly layered media. This is done in the regime where the inhomogeneities are smaller than the pulse, which propagates over long distances compared to its width. We show numerical evidence for possible use of an expanding window time-reversal technique for detecting anomalies buried in the medium.
Author: Jean-Pierre Fouque
Publisher: Springer
ISBN: 9780387511481
Category : Science
Languages : en
Pages : 0
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Book Description
The content of this book is multidisciplinary by nature. It uses mathematical tools from the theories of probability and stochastic processes, partial differential equations, and asymptotic analysis, combined with the physics of wave propagation and modeling of time reversal experiments. It is addressed to a wide audience of graduate students and researchers interested in the intriguing phenomena related to waves propagating in random media. At the end of each chapter there is a section of notes where the authors give references and additional comments on the various results presented in the chapter.
Author: Fernando González del Cueto
Publisher:
ISBN: 9780542041402
Category :
Languages : en
Pages : 50
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Book Description
Author: Leonid Brekhovskikh
Publisher: Elsevier
ISBN: 0323163246
Category : Technology & Engineering
Languages : en
Pages : 575
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Book Description
Waves in Layered Media focuses on the theory of the propagation of elastic and electromagnetic waves in layered media. This book presents a complete report of Soviet researches on wave propagation through layered media. Organized into six chapters, this book starts with an overview of the theory of wave reflection from layers and interfaces. This text then examines the some of the representations and methods, which are common to different branches of physics. Other chapters define the reflection reduction of optical waves as the lowering of the reflection coefficient at the air–glass boundaries by depositing thin layers of several materials on the glass. This book discusses as well the field of a concentrated source situated in a layered-inhomogeneous medium, which is one of the main problems in modern radiophysics, acoustics, and the physics of the Earth's crust. The final chapter deals with wave propagation in layered-inhomogeneous media. This book is a valuable resource for engineers, scientists, and physicists.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A time reversal mirror is a device capable of receiving a signal in time, keeping it in memory, and sending it back into the same medium in the reversed direction of time. The main effect is the fascinating refocusing of the scattered signal, which is formed by sending the pulse into a complex medium, after time reversal through the same medium. The refocused signal is a pulse with shape similar to the initial pulse along with some low amplitude noise. This surprising effect has a great potential for application in domains such as medical imaging, underwater acoustics and wireless communication. Time reversal is studied in reflection and transmission. In both cases, we demonstrate the self-averaging properties of the time reversed refocused pulse. An accurate numerical method for simulating waves propagating in complex one-dimensional media is employed. Numerical simulations are used to reproduce the time-reversal self-averaging effect which takes place in randomly layered media. The effect of refocusing is enhanced in a regime where the inhomogenities are smaller than the pulse, which propagates over long distances compared to its width. Time Reversal can be implemented using several numerical methods including Transfer Matrix, Finite Difference Time Domain (FDTD) & Boundary Integral Methods. This thesis includes a comprehensive comparison of the methods in terms of speed and accuracy. The most efficient method for implementing time reversal is then used to obtain numerical evidence for potential use of a sliding window time-reversal technique for detecting a buried cavity/object inside the medium. The numerical methods are well adapted for generalization to the multi-dimensional case.
Author: Gestur Ólafsson
Publisher: American Mathematical Soc.
ISBN: 0821839306
Category : Mathematics
Languages : en
Pages : 176
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Book Description
Since their emergence in 1917, tomography and inverse problems remain active and important fields that combine pure and applied mathematics and provide strong interplay between diverse mathematical problems and applications. The applied side is best known for medical and scientific use, in particular, medical imaging, radiotherapy, and industrial non-destructive testing. Doctors use tomography to see the internal structure of the body or to find functional information, such asmetabolic processes, noninvasively. Scientists discover defects in objects, the topography of the ocean floor, and geological information using X-rays, geophysical measurements, sonar, or other data. This volume, based on the lectures in the Short Course The Radon Transform and Applications to InverseProblems at the American Mathematical Society meeting in Atlanta, GA, January 3-4, 2005, brings together articles on mathematical aspects of tomography and related inverse problems. The articles cover introductory material, theoretical problems, and practical issues in 3-D tomography, impedance imaging, local tomography, wavelet methods, regularization and approximate inverse, sampling, and emission tomography. All contributions are written for a general audience, and the authors have includedreferences for further reading.
Author: Jean-Pierre Fouque
Publisher: Springer Science & Business Media
ISBN: 9401145725
Category : Science
Languages : en
Pages : 462
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Book Description
The NATO Advanced Study Institute on Diffuse Waves in Complex Media was held at the "Centre de Physique des Houches" in France from March 17 to 27, 1998. The Schools' scientific content, wave propagation in heterogeneous me dia, has covered many areas of fundamental and applied research. On the one hand, the understanding of wave propagation has considerably improved during the last thirty years. New developments and concepts such as, speckle correlations, weak and strong localization, time reversal, near-field propagation are under active research. On the other hand, wave propagation in random media is now being investigated in many different fields such as applied mathematics, acoustics, optics, atomic physics, geo physics or medical sciences. Each community often uses its own langage to describe the same phenomena. The aim of the School was to gather worldwide specialists to illuminate various aspects of wave propagation in random media. This volume presents fourteen expository articles corresponding to courses and seminars given during the School. They are arranged as follows. The first three articles deal with the phenomena of localization of waves: B. van Tiggelen (p. 1) gives a critical review of the physics of localization, J. Lacroix (p. 61) presents the mathematical theory and A. Klein (p. 73) describes recent results for randomized periodic media.
