Electromagnetic Time Reversal

Electromagnetic Time Reversal
Author: Farhad Rachidi
Publisher: John Wiley & Sons
Total Pages: 298
Release: 2017-04-17
Genre: Science
ISBN: 1119142083

The aim of this book is to familiarize the reader with the concept of electromagnetic time reversal, and introduce up-to-date applications of the concept found in the areas of electromagnetic compatibility and power systems. It is original in its approach to describing propagation and transient issues in power networks and power line communication, and is the result of the three main editors' pioneering research in the area.

Modeling and Computations in Electromagnetics

Modeling and Computations in Electromagnetics
Author: Habib Ammari
Publisher: Springer Science & Business Media
Total Pages: 239
Release: 2008-01-12
Genre: Technology & Engineering
ISBN: 3540737782

This is nothing less than an essential text in what is a new and growing discipline. Electromagnetic modeling and computations is expanding as a result of the steadily increasing demand for designing electrical devices, modeling electromagnetic materials, and simulating electromagnetic fields in nanoscale structures. The aim of this volume is to bring together prominent worldwide experts to review state-of-the-art developments and future trends of modeling and computations in electromagnetics.

Reciprocity, Spatial Mapping and Time Reversal in Electromagnetics

Reciprocity, Spatial Mapping and Time Reversal in Electromagnetics
Author: C. Altman
Publisher: Springer Science & Business Media
Total Pages: 299
Release: 2013-03-09
Genre: Science
ISBN: 9401579156

The choice of topics in this book may seem somewhat arbitrary, even though we have attempted to organize them in a logical structure. The contents reflect the path of 'search and discovery' followed by us, on and off, for the in fact last twenty years. In the winter of 1970-71 one of the authors (C. A. ), on sah baticalleave with L. R. O. Storey's research team at the Groupe de Recherches Ionospheriques at Saint-Maur in France, had been finding almost exact symme tries in the computed reflection and transmission matrices for plane-stratified magnetoplasmas when symmetrically related directions of incidence were com pared. At the suggestion of the other author (K. S. , also on leave at the same institute), the complex conjugate wave fields, used to construct the eigenmode amplitudes via the mean Poynting flux densities, were replaced by the adjoint wave fields that would propagate in a medium with transposed constitutve tensors, et voila, a scattering theorem-'reciprocity in k-space'-was found in the computer output. To prove the result analytically one had to investigate the properties of the adjoint Maxwell system, and the two independent proofs that followed, in 1975 and 1979, proceeded respectively via the matrizant method and the thin-layer scattering-matrix method for solving the scattering problem, according to the personal preferences of each of the authors. The proof given in Chap. 2 of this book, based on the hindsight provided by our later results, is simpler and much more concise.

Time-Reversal for Electromagnetic Waves in Complex Media

Time-Reversal for Electromagnetic Waves in Complex Media
Author:
Publisher:
Total Pages: 16
Release: 2003
Genre:
ISBN:

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.

Computational Methods for Electromagnetic Inverse Scattering

Computational Methods for Electromagnetic Inverse Scattering
Author: Xudong Chen
Publisher: John Wiley & Sons
Total Pages: 325
Release: 2018-07-18
Genre: Science
ISBN: 1119311985

A comprehensive and updated overview of the theory, algorithms and applications of for electromagnetic inverse scattering problems Offers the recent and most important advances in inverse scattering grounded in fundamental theory, algorithms and practical engineering applications Covers the latest, most relevant inverse scattering techniques like signal subspace methods, time reversal, linear sampling, qualitative methods, compressive sensing, and noniterative methods Emphasizes theory, mathematical derivation and physical insights of various inverse scattering problems Written by a leading expert in the field

Time and Chance

Time and Chance
Author: David Z Albert
Publisher: Harvard University Press
Total Pages: 188
Release: 2003-02-28
Genre: Science
ISBN: 0674020138

This book is an attempt to get to the bottom of an acute and perennial tension between our best scientific pictures of the fundamental physical structure of the world and our everyday empirical experience of it. The trouble is about the direction of time. The situation (very briefly) is that it is a consequence of almost every one of those fundamental scientific pictures--and that it is at the same time radically at odds with our common sense--that whatever can happen can just as naturally happen backwards. Albert provides an unprecedentedly clear, lively, and systematic new account--in the context of a Newtonian-Mechanical picture of the world--of the ultimate origins of the statistical regularities we see around us, of the temporal irreversibility of the Second Law of Thermodynamics, of the asymmetries in our epistemic access to the past and the future, and of our conviction that by acting now we can affect the future but not the past. Then, in the final section of the book, he generalizes the Newtonian picture to the quantum-mechanical case and (most interestingly) suggests a very deep potential connection between the problem of the direction of time and the quantum-mechanical measurement problem. The book aims to be both an original contribution to the present scientific and philosophical understanding of these matters at the most advanced level, and something in the nature of an elementary textbook on the subject accessible to interested high-school students.

Time Reversal of Electromagnetic Waves in Randomly Layered Media

Time Reversal of Electromagnetic Waves in Randomly Layered Media
Author:
Publisher:
Total Pages:
Release: 2003
Genre:
ISBN:

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.

Time-Reversal Symmetry

Time-Reversal Symmetry
Author: Ion I. Geru
Publisher: Springer
Total Pages: 362
Release: 2018-12-31
Genre: Science
ISBN: 3030012107

This book introduces new developments in the field of Time-Reversal Symmetry presenting, for the first time, the Wigner time-reversal operator in the form of a product of two- or three time-reversal operators of lower symmetry. The action of these operators leads to the sign change of only one or two angular momentum components, not of all of them. It demonstrates that there are six modes of time-reversal symmetry breaking that do not lead to the complete disappearance of the symmetry but to its lowering. The full restoration of the time-reversal symmetry in the six cases mentioned is possible by introducing six types of metaparticles. The book also confirms the presence of six additional time-reversal operators using a group-theoretical method. The problem is only where to seek these metaparticles. The book discusses time-reversal symmetry in classical mechanics, classical and relativistic electrodynamics, quantum mechanics and theory of quantized fields, including dynamical reversibility and statistical irreversibility of the time, Wigner’s and Herring’s criteria, Kramers theorem, selection rules due to time-reversal symmetry, Onsager’s relations, Poincaré recurrence theorem, and CPT theorem. It particularly focuses attention on time-reversal symmetry violation. It is proposed a new method of testing the time-reversal symmetry, which is confirmed experimentally by EPR spectroscopy data. It shows that the traditional black-white point groups of magnetic symmetry are not applicable to magnetic systems with Kramers degeneration of energy levels and that magnetic groups of four-color symmetry are adequate for them. Further, it addresses the predicted structural distortions in Kramers three-homonuclear magnetic clusters due to time-reversal symmetry that have been identified experimentally. Lastly, it proposes a method of synthesis of two-nuclear coordination compounds with predictable magnetic properties, based on the application of the time-reversal transformation that was confirmed experimentally.

Time Reversal of Electromagnetic Waves in Randomly Layered Media

Time Reversal of Electromagnetic Waves in Randomly Layered Media
Author: Petr Glotov
Publisher:
Total Pages: 78
Release: 2006
Genre:
ISBN:

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.

Electromagnetic Wave Propagation, Radiation, and Scattering

Electromagnetic Wave Propagation, Radiation, and Scattering
Author: Akira Ishimaru
Publisher: John Wiley & Sons
Total Pages: 1045
Release: 2017-08-09
Genre: Science
ISBN: 1119079535

One of the most methodical treatments of electromagnetic wave propagation, radiation, and scattering—including new applications and ideas Presented in two parts, this book takes an analytical approach on the subject and emphasizes new ideas and applications used today. Part one covers fundamentals of electromagnetic wave propagation, radiation, and scattering. It provides ample end-of-chapter problems and offers a 90-page solution manual to help readers check and comprehend their work. The second part of the book explores up-to-date applications of electromagnetic waves—including radiometry, geophysical remote sensing and imaging, and biomedical and signal processing applications. Written by a world renowned authority in the field of electromagnetic research, this new edition of Electromagnetic Wave Propagation, Radiation, and Scattering: From Fundamentals to Applications presents detailed applications with useful appendices, including mathematical formulas, Airy function, Abel’s equation, Hilbert transform, and Riemann surfaces. The book also features newly revised material that focuses on the following topics: Statistical wave theories—which have been extensively applied to topics such as geophysical remote sensing, bio-electromagnetics, bio-optics, and bio-ultrasound imaging Integration of several distinct yet related disciplines, such as statistical wave theories, communications, signal processing, and time reversal imaging New phenomena of multiple scattering, such as coherent scattering and memory effects Multiphysics applications that combine theories for different physical phenomena, such as seismic coda waves, stochastic wave theory, heat diffusion, and temperature rise in biological and other media Metamaterials and solitons in optical fibers, nonlinear phenomena, and porous media Primarily a textbook for graduate courses in electrical engineering, Electromagnetic Wave Propagation, Radiation, and Scattering is also ideal for graduate students in bioengineering, geophysics, ocean engineering, and geophysical remote sensing. The book is also a useful reference for engineers and scientists working in fields such as geophysical remote sensing, bio–medical engineering in optics and ultrasound, and new materials and integration with signal processing.