Science

Electromagnetic Time Reversal

Author: Farhad Rachidi

Publisher: John Wiley & Sons

ISBN:

Category: Science

Page: 304

View: 396

"This book is intended to give the theoretical foundation of the electromagnetic time reversal theory. Special emphasis is given on real applications in the fields of EMC and power systems"--
Science

Reciprocity, Spatial Mapping and Time Reversal in Electromagnetics

Author: C. Altman

Publisher: Springer Science & Business Media

ISBN:

Category: Science

Page: 287

View: 893

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.
Signal processing

Time Reversal Based Signal Processing Techniques for Ultrawideband Electromagnetic Sensing in Random Media

Author: Mehmet Emre Yavuz

Publisher:

ISBN:

Category: Signal processing

Page:

View: 887

Abstract: This dissertation focuses on the application and development of time reversal (TR) based signal processing techniques for ultrawideband (UWB) electromagnetic (EM) waves in random media. TR techniques exploit the TR invariance of the wave equation to take advantage of the retransmitted (time-reversed) fields for improved imaging and focusing. This is because retransmitted signals propagate backwards through the same medium and undergo similar reflection, refraction and multiple scattering that they underwent during the forward propagation, resulting in focusing around the initial source locations. If multiple scattering occurs in the intervening media, refocusing resolution can overcome the classical diffraction limit characterizing superresolution, a somewhat counterintuitive result. With the success of initial TR experiments in acoustics, there has been a strong interest in the application of TR methods using radio frequency EM waves. It is also our motivation here to develop TR techniques for UWB electromagnetic waves. We start by investigating superresolution effects of TRed UWB EM waves under continuous random background media and examine their dependency on medium statistics. In contrast to the acoustic case, polarimetric TR exploiting EM polarization is also analyzed to observe depolarization effects on the refocusing of TRed EM waves. We continue with the application of TR in dispersive media (such as soil or biological tissues) where TR invariance is broken and yields performance degradation. We introduce a physical compensation technique based upon both space and frequency dependent inverse filters to improve the performance of TR techniques for homogeneous and random dispersive media. We also develop a physical full time-domain selective focusing method on the desired scatterers in the presence of others. Both narrowband and UWB TR-based imaging techniques for detection and localization of distinct scatterers in inhomogeneous background media are investigated under several perturbations. Specifically, we investigate the effects due to clutter, noise, dispersion and losses. Moving TRAs and restrictions on array elements on these TR-based imaging methods are also considered. Finally, we introduce a new TR-based imaging functional based on the simultaneous utilization of spatial and UWB frequency data to obtain a novel method for UWB imaging of embedded scatterers in homogeneous and random media.

Electromagnetic Time-reversal Imaging and Tracking Techniques for Inverse Scattering and Wireless Communications

Author: Ahmed Elsayed Fouda

Publisher:

ISBN:

Category:

Page:

View: 748

Abstract: Time-reversal (TR) was originated in acoustics as a technique for re-focusing waves around their source location. Under certain conditions, the wave equation is invariant under TR, therefore, waves emanated from a source or scattered from a passive target, and recorded by a transceivers array, will retrace their forward path and automatically focus at the source/target location if back propagated in a time-reversed (last-in first-out) fashion from that array. Focusing resolution of time-reversed back propagation in rich scattering environments beats that in free space, yielding what is known as 'superresolution'. Moreover, under ultrawideband (UWB) operation, TR exhibits the distinctive property of 'statistical stability', which makes it an attractive technique for imaging in disordered media whose characteristics are not known deterministically (random media). Over the past few years, TR has been exploited in a variety of electromagnetic sensing and imaging applications such as ground penetrating radar, breast cancer detection, nondestructive testing, and through-wall imaging. In addition, TR has been extensively applied in UWB wireless communication providing myriad of advantages including reduced receiver complexity, power saving, increased system capacity, and enhanced information secrecy.
Science

The Search for the Meaning of Space, Time, and Matter

Author: Kai Woehler

Publisher: Xlibris Corporation

ISBN:

Category: Science

Page: 447

View: 841

The book gives a comprehensive introduction for interested general readers, into the development and structure of concepts, ideas and theory formation about the elementary building blocks of matter, the forces with which these particles interact and about the fundamental nature of space itself. Einsteins theory of the cosmos and the recent discovery of the presence of a dark energy which leads to an accelerated expansion of cosmic space, provide the background for the most astonishing recent developments in the search for the origin of space and matter. The String-Theory revolution has led to the notion that nature may not follow one unique set of laws to build worlds, but that innumerable many possible universes may exist, that worlds may be emerging and disappearing like biological species and that our existence may be extraordinarily rare and therefore precious. An introduction to the concept of emergence in self-organizing systems is given to make the connection to the idea that Emergence may be the inherent creative property of space and matter at the quantum level.
Science

Ultra-Wideband Short-Pulse Electromagnetics 8

Author: Carl E. Baum

Publisher: Springer Science & Business Media

ISBN:

Category: Science

Page: 260

View: 878

The purpose of the Ultra-Wideband Short-Pulse Electromagnetics Conference series is to focus on advanced technologies for the generation, radiation and detection of ultra-wideband short pulse signals, taking into account their propagation and scattering from and coupling to targets of interest. This Conference series reports on developments in supporting mathematical and numerical methods and presents current and potential future applications of the technology. Ultra-Wideband Short-Pulse Electromagnetics 8 is based on the American Electromagnetics 2006 conference held from June 3-7 in Albuquerque, New Mexico. Topical areas covered in this volume include pulse radiation and measurement, scattering theory, target detection and identification, antennas, signal processing, and communications.
Science

The Oxford Handbook of Philosophy of Time

Author: Craig Callender

Publisher: OUP Oxford

ISBN:

Category: Science

Page: 704

View: 177

As the study of time has flourished in the physical and human sciences, the philosophy of time has come into its own as a lively and diverse area of academic research. Philosophers investigate not just the metaphysics of time, and our experience and representation of time, but the role of time in ethics and action, and philosophical issues in the sciences of time, especially with regard to quantum mechanics and relativity theory. This Handbook presents twenty-three specially written essays by leading figures in their fields: it is the first comprehensive collaborative study of the philosophy of time, and will set the agenda for future work.
Mathematics

Inverse Problems and Imaging

Author: Luis L. Bonilla

Publisher: Springer Science & Business Media

ISBN:

Category: Mathematics

Page: 192

View: 279

In the CIME Summer School on Imaging, experts in mathematical techniques and applications presented useful introductions to many aspects of the field. This volume contains updated lectures as well as additional contributions on other related topics.
Philosophy

A Companion to the Philosophy of Time

Author: Adrian Bardon

Publisher: John Wiley & Sons

ISBN:

Category: Philosophy

Page: 600

View: 918

A Companion to the Philosophy of Time presents the broadest treatment of this subject yet; 32 specially commissioned articles - written by an international line-up of experts – provide an unparalleled reference work for students and specialists alike in this exciting field. The most comprehensive reference work on the philosophy of time currently available The first collection to tackle the historical development of the philosophy of time in addition to covering contemporary work Provides a tripartite approach in its organization, covering history of the philosophy of time, time as a feature of the physical world, and time as a feature of experience Includes contributions from both distinguished, well-established scholars and rising stars in the field
Science

Classical Electromagnetism in a Nutshell

Author: Anupam Garg

Publisher: Princeton University Press

ISBN:

Category: Science

Page: 712

View: 816

This graduate-level physics textbook provides a comprehensive treatment of the basic principles and phenomena of classical electromagnetism. While many electromagnetism texts use the subject to teach mathematical methods of physics, here the emphasis is on the physical ideas themselves. Anupam Garg distinguishes between electromagnetism in vacuum and that in material media, stressing that the core physical questions are different for each. In vacuum, the focus is on the fundamental content of electromagnetic laws, symmetries, conservation laws, and the implications for phenomena such as radiation and light. In material media, the focus is on understanding the response of the media to imposed fields, the attendant constitutive relations, and the phenomena encountered in different types of media such as dielectrics, ferromagnets, and conductors. The text includes applications to many topical subjects, such as magnetic levitation, plasmas, laser beams, and synchrotrons. Classical Electromagnetism in a Nutshell is ideal for a yearlong graduate course and features more than 300 problems, with solutions to many of the advanced ones. Key formulas are given in both SI and Gaussian units; the book includes a discussion of how to convert between them, making it accessible to adherents of both systems. Offers a complete treatment of classical electromagnetism Emphasizes physical ideas Separates the treatment of electromagnetism in vacuum and material media Presents key formulas in both SI and Gaussian units Covers applications to other areas of physics Includes more than 300 problems
Science

Topological Foundations of Electromagnetism

Author: Terence W. Barrett

Publisher: World Scientific

ISBN:

Category: Science

Page: 185

View: 679

Topological Foundations of Electromagnetism seeks a fundamental understanding of the dynamics of electromagnetism; and marshals the evidence that in certain precisely defined topological conditions, electromagnetic theory (Maxwell''s theory) must be extended or generalized in order to provide an explanation and understanding of, until now, unusual electromagnetic phenomena. Key to this generalization is an understanding of the circumstances under which the so-called A potential fields have physical effects. Basic to the approach taken is that the topological composition of electromagnetic fields is the fundamental conditioner of the dynamics of these fields. The treatment of electromagnetism from, first, a topological perspective, continuing through group theory and gauge theory, to a differential calculus description is a major thread of the book. Suggestions for potential new technologies based on this new understanding and approach to conditional electromagnetism are also given. Sample Chapter(s). Chapter 1: Electromagnetic Phenomena Not Explained by Maxwell''s Equations260 (437 KB). Contents: Electromagnetic Phenomena Not Explained by Maxwell''s Equations; The Sagnac Effect: A Consequence of Conservation of Action Due to Gauge Field Global Conformal Invariance in a Multiply Joined Topology of Coherent Fields; Topological Approaches to Electromagnetism. Readership: Physicists; advanced undergraduate and graduate students in physics; electrical engineers.
Science

Ultra-Wideband, Short Pulse Electromagnetics 9

Author: Frank Sabath

Publisher: Springer Science & Business Media

ISBN:

Category: Science

Page: 500

View: 692

Ultra-wideband (UWB), short-pulse (SP) electromagnetics are now being used for an increasingly wide variety of applications, including collision avoidance radar, concealed object detection, and communications. Notable progress in UWB and SP technologies has been achieved by investigations of their theoretical bases and improvements in solid-state manufacturing, computers, and digitizers. UWB radar systems are also being used for mine clearing, oil pipeline inspections, archeology, geology, and electronic effects testing. Ultra-wideband Short-Pulse Electromagnetics 9 presents selected papers of deep technical content and high scientific quality from the UWB-SP9 Conference, which was held from July 21-25, 2008, in Lausanne, Switzerland. The wide-ranging coverage includes contributions on electromagnetic theory, time-domain computational techniques, modeling techniques, antennas, pulsed-power, UWB interactions, radar systems, UWB communications, broadband systems and components. This book serves as a state-of-the-art reference for scientists and engineers working in these applications areas.
Technology & Engineering

Guided Electromagnetic Waves

Author: Michał Mrozowski

Publisher: Research Studies PressLtd

ISBN:

Category: Technology & Engineering

Page: 370

View: 267

The development of efficient techniques for the rigorous modelling of electromagnetic phenomena is a key factor in determining the progress in many technical area from microwave engineering to X-Ray technology. This book presents a class of numerical techniques for the analysis of discrete spectra of electrodynamic operators, highlights their advantages and drawbacks, and discusses their potential for solving practical problems. Examples of the application of some of the methods to solve both field theory and engineering problems are included.
Antennas (Electronics)

Digest

Author: IEEE Antennas and Propagation Society. International Symposium

Publisher:

ISBN:

Category: Antennas (Electronics)

Page:

View: 421

Science

Electromagnetic Noise and Quantum Optical Measurements

Author: Hermann A. Haus

Publisher: Springer Science & Business Media

ISBN:

Category: Science

Page: 562

View: 284

From the reviews: "Haus’ book provides numerous insights on topics of wide importance, and contains much material not available elsewhere in book form. [...] an indispensable resource for those working in quantum optics or electronics." Optics & Photonics News
Technology & Engineering

Magnetophotonics

Author: Mitsuteru Inoue

Publisher: Springer Science & Business Media

ISBN:

Category: Technology & Engineering

Page: 228

View: 311

This book merges theoretical and experimental works initiated in 1997 from consideration of periodical artificial dielectric structures comprising magneto-optical materials. Modern advances in magnetophotonics are discussed giving theoretical analyses and demonstrations of the consequences of light interaction with non-reciprocal media of various designs. This first collection of foundational works is devoted to light-to-artificial magnetic matter phenomena and related applications. The subject covers the physical background and the continuing research in the field of magnetophotonics.
Science

Relativistic Quantum Mechanics

Author: Paul Strange

Publisher: Cambridge University Press

ISBN:

Category: Science

Page: 594

View: 617

This graduate text introduces relativistic quantum theory, emphasising its important applications in condensed matter physics. Relativistic quantum theory is the unification into a consistent theory of Einstein's theory of relativity and the quantum mechanics of Bohr, Schrödinger, and Heisenberg, etc. Beginning with basic theory, the book then describes essential topics. Many worked examples and exercises are included along with an extensive reference list. This clear account of a crucial topic in science will be valuable to graduates and researchers working in condensed matter physics and quantum physics.