This book presents the theory of room acoustical fields and revises the Mirror Source Methods for practical computational use, emphasizing the wave character of acoustical fields. The presented higher methods include the concepts of "Mirror Point Sources" and "Corner sources which allow for an excellent approximation of complex room geometries and even equipped rooms. In contrast to classical description, this book extends the theory of sound fields describing them by their complex sound pressure and the particle velocity. This approach enables accurate descriptions of interference and absorption phenomena.

Unlike other treatments of sensors or actuators, this book approaches the devices from the point of view of the fundamental coupling mechanism between the electrical and mechanical behaviour. The principles of operation of the solenoid are the same in both cases, and this book thus treats them together. It begins with a discussion of systems analysis as a tool for modelling transducers, before turning to a detailed discussion of transduction mechanisms. The whole is rounded off by an input/output analysis of transducers.

This book is the first in a set of forthcoming books focussed on state-of-the-art development in the VLSI Signal Processing area. It is a response to the tremendous research activities taking place in that field. These activities have been driven by two factors: the dramatic increase in demand for high speed signal processing, especially in consumer elec tronics, and the evolving microelectronic technologies. The available technology has always been one of the main factors in determining al gorithms, architectures, and design strategies to be followed. With every new technology, signal processing systems go through many changes in concepts, design methods, and implementation. The goal of this book is to introduce the reader to the main features of VLSI Signal Processing and the ongoing developments in this area. The focus of this book is on: * Current developments in Digital Signal Processing (DSP) pro cessors and architectures - several examples and case studies of existing DSP chips are discussed in Chapter 1. * Features and requirements of image and video signal processing architectures - both applications specific integrated circuits (ASICs) and programmable image processors are studied in Chapter 2. * New market areas for signal processing - especially in consumer electronics such as multimedia, teleconferencing, and movie on demand. * Impact of arithmetic circuitry on the performance of DSP pro cessors - several topics are discussed in Chapter 3 such as: number representation, arithmetic algorithms and circuits, and implementa tion.

Introduction to Digital Audio Coding and Standards provides a detailed introduction to the methods, implementations, and official standards of state-of-the-art audio coding technology. In the book, the theory and implementation of each of the basic coder building blocks is addressed. The building blocks are then fit together into a full coder and the reader is shown how to judge the performance of such a coder. Finally, the authors discuss the features, choices, and performance of the main state-of-the-art coders defined in the ISO/IEC MPEG and HDTV standards and in commercial use today. The ultimate goal of this book is to present the reader with a solid enough understanding of the major issues in the theory and implementation of perceptual audio coders that they are able to build their own simple audio codec. There is no other source available where a non-professional has access to the true secrets of audio coding.

The 105 theses contained in this book are selected from those whose authors were present at the 20th International Symposium on Acoustical Imaging. held at Southeast University. Nanjing. China. during September 12-14. 1992. It was the first time that the symposium had been held in China. Our efforts to host the conference goes back to the 15th International Symposium on Acoustical Imaging held in Halifax. Canada. in 1986. We are glad that the 20th symposium has been successfully held at last. We are ardent for the symposium not only because we attach much importance to the field of acoustical imaging. but also because we admire the tradition of the serious academic exploration and friendly cooperation of the scholars attending the symposium. The theses in this book are from 21 countries and those by Mr. G. Wade. Takuso Sato. J. F. Greenleaf. K. J. Langenberg. and Wencai Yang are the specially invited papers. These theses cover such important fields of acoustical imaging as follows: 1. Mathematics and physics of acoustical imaging; 2. Components and industry application; 3. Applications in medicine and biology; 4. Applications in nondestructive testing; 5. Applications in geophysics; 6. Underwater acoustical imaging. All these theses reflect the latest progress in theory and technology. We are very grateful to all the authors who have provided these theses.

The call for papers for the rUTAM-Symposium on Mechanics of Passive and Active Flow Control brought an overwhelming response of applications for contributions. Fi nally 12 invited lectures, 48 papers and 23 posters were selected by thc Scientific Com mittee to be presented in the conference. 58 papers are published in this volume. Due to the limited number of pages available, poster presentations could not be considered for publication. The editors would like to thank all the members of the Scientific Committee for their very valuable assistance. The papers presented at the rUT AM Symposium were classified under three groups de voted to * Passive Control Methods, * Active Control Methods and * Control Concepts. This was done to contrast at first between the passive techniques where the control power is mainly supplied by the flow itself and the active techniques where the power is pro vided by external sources; the third group was devoted to control concepts for presenting methods of control theory and new techniques of flow control.

The contents of this volume are the proceedings of the 23'd International Symposium on Acoustical Imaging which took place 13-16 April, 1997, in Boston, Massachusetts. The first Symposium met 25 years ago. Originally the Symposium met in California, then elsewhere within the United States but beginning in 1988 the Symposia began to meet outside of the United States as welL It is now being held about every eighteen months, alternately in the United States and then outside. The present pattern is to hold one meeting in East Asia, then in the USA, then in Europe and again in the USA However, for scheduling reasons the next Symposium will be in Santa Barbara, California, followed by England and then East Asia. It is to be noted that the Symposium is a free standing institution, not associated with any other organization. Each meeting is the total responsibility of its chairman with the advice of past chairmen. Papers are submitted in response to the call for them and reviewed by an International Scientific Advisory Board . . The quality depends entirely on the response to the calL It is gratifYing to note that the Symposium has attained the status that attracts high quality contributions despite (or perhaps because ot) the loose structure. Two factors that have appeal are that there is only one session and that there is time during the meeting for extensive discussion.

This volume presents selected papers from the IUTAM Symposium on Reynolds Number Scaling in Turbulent Flow, convened in Princeton, NJ, USA, September I1-13, 2002. The behavior ofturbulence at high Reynolds number is interesting from a fundamental point of view, in that most theories of turbulence make very specific predictions in the limit of infinite Reynolds number. From a more practical point of view, there exist many applications that involve turbulent flow where the Reynolds numbers are extremely large. For example, large vehicles such as submarines and commercial transports operate at Reynolds 9 numbers based on length ofthe order oft0 , and industrial pipe flows cover a 7 very wide range of Reynolds numbers up to 10 * Many very important applications of high Reynolds number flow pertain to atmospheric and other geophysical flows where extremely high Reynolds numbers are the rule rather than the exception, and the understanding of climate changes and the prediction of destructive weather effects hinges to some extent on our appreciation ofhigh-Reynolds number turbulence behavior. The important effects of Reynolds number on turbulence has received a great deal of recent attention. The objective of the Symposium was to bring together many of the world's experts in this area to appraise the new experimental results, discuss new scaling laws and turbulence models, and to enhance our mutual understanding of turbulence.

Blind Signal Separation (BSS) deals with recovering (filtered versions of) source signals from an observed mixture thereof. The term `blind' relates to the fact that there are no reference signals for the source signals and also that the mixing system is unknown. This book presents a new method for blind signal separation, which is developed to work on microphone signals. Acoustic Echo Cancellation (AEC) is a well-known technique to suppress the echo that a microphone picks up from a loudspeaker in the same room. Such acoustic feedback occurs for example in hands-free telephony and can lead to a perceived loud tone. For an application such as a voice-controlled television, a stereo AEC is required to suppress the contribution of the stereo loudspeaker setup. A generalized AEC is presented that is suited for multi-channel operation. New algorithms for Blind Signal Separation and multi-channel Acoustic Echo Cancellation are presented. A background is given in array signal processing methods, adaptive filter theory, and fast filtering in the frequency domain. The included CD-ROM can be played using any compact disc player to play the simulation results that are described in the text. When inserted into a computer, it furthermore gives Matlab implementations of the new algorithms along with audio data with which to experiment. This makes the book suited to researchers, engineers, and university students, who want to get acquainted with these emerging fields.

The Royal Society has initiated a series of meetings to discuss the effect advances in technology will have on our way of life in the next century. The two previous meetings have been concerned with housing and waste treat ment. The subject of the third meeting, communications, is no less critical to life, but it offers particular problems and uncertainties, especially in the forecasting of future trends. Indeed, some have doubted if there can be profitable debate on long-term development in such a fast-moving field. The importance of the topic justifies an attempt, and the reader will judge whether the authors have met the challenge. Communications today bears little resemblance to that of the 1970s. Then we knew about satellites and optical fibres, and we had seen lasers and silicon chips, but most of us could never imagine the potential of the new technologies within our grasp. We had also not assessed the thirst of the popUlation for more and better ways of talking and writing to each other. It was the combination of market need and technical capability that created the com munications revolution.

The Fourth USA-USSR Symposium. on The Physics of Optical Phenomena and Their Use as Probes of Matter, was held in Irvine, California, January 23-27, 1990. Participating in the Symposium were 22 scientists from the USSR and 29 from the USA. In addition, to provide an international dimension to this Symposium without, however, compromising significantly its essentially binational character, 7 non-US and non-USSR scientists were invited to take part in it. The present volume is the proceedings of that Symposium, and contains all manuscripts received prior to August 1, 1990, representing. scientific contributions presented. A few manuscripts were not received, but for completeness the corresponding abstract is printed.. Three previous USA/USSR Binational Symposia on related topics have been held, viz. "Theory of Light Scattering in Condensed Matter" (Moscow, 1975), "Light Scattering in Solids" (New York, 1979), and "Laser Optics of Condensed Matter" (Leningrad, 1987). These meetings were evaluated by the participants as highly successful and provided invaluable oppor tunities for researchers to exchange information and to initiate colla borative work which led to research visits by US physicist to Soviet laboratories, and vice versa, and which continue to the present day.

Digital Signal Processing for Communication Systems examines the plans for the future and the progress that has already been made, in the field of DSP and its applications to communication systems. The book pursues the progression from communication and information theory through to the implementation, evaluation and performance enhancing of practical communication systems using DSP technology. Digital Signal Processing for Communication Systems looks at various types of coding and modulation techniques, describing different applications of Turbo-Codes, BCH codes and general block codes, pulse modulations, and combined modulation and coding in order to improve the overall system performance. The book examines DSP applications in measurements performed for channel characterisation, pursues the use of DSP for design of effective channel simulators, and discusses equalization and detection of various signal formats for different channels. A number of system design issues are presented where digital signal processing is involved, reporting on the successful implementation of the system components using DSP technology, and including the problems involved with implementation of some DSP algorithms. Digital Signal Processing for Communication Systems serves as an excellent resource for professionals and researchers who deal with digital signal processing for communication systems, and may serve as a text for advanced courses on the subject.

Based on a NATO Advanced Study Institute held in 1993, this book addresses recent advances in automatic speech recognition and speech coding. The book contains contributions by many of the most outstanding researchers from the best laboratories worldwide in the field. The contributions have been grouped into five parts: on acoustic modeling; language modeling; speech processing, analysis and synthesis; speech coding; and vector quantization and neural nets. For each of these topics, some of the best-known researchers were invited to give a lecture. In addition to these lectures, the topics were complemented with discussions and presentations of the work of those attending. Altogether, the reader is given a wide perspective on recent advances in the field and will be able to see the trends for future work.

An almost complete collection of the papers given at the International Workshop on Imaging in High Energy Astronomy (Anacapri, Italy, 1994). These proceedings, which concentrate on imaging above 10 keV, represent the state of the art in the field, resulting from the success of many missions (I.C. Granat and CGRO) carrying detectors for high energy astronomy with imaging capabilities. The main topics of the book are Bragg concentrators, coded mask-modulation collimators, double Compton telescopes, the occultation method, tracking chambers, and new experimental techniques. The book also contains some papers dealing with image reconstruction and processing, with an emphasis on the above techniques.

Rapid advances in Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) of turbulence provide opportunities for improved prediction of incompressible and compressible turbulent flows. The book includes five invited and thirty-eight contributed papers presented at the Second AFOSR International Conference on DNS and LES held at Rutgers - The State University of New Jersey, on June 7-9, 1999. A broad range of topics in DNS and LES are presented, including new developments in LES modeling, numerical algorithms for LES and DNS, DNS and LES of reacting flows, and DNS and LES for supersonic and hypersonic boundary layers. The book provides a extensive view of the state of the art in DNS and LES.

This book contains the lectures delivered at the NATO Advanced Research Workshop on the "Intersubband Transistions in Quantum Wells" held in Cargese, France, between the t 9 h and the 14th of September 1991. The urge for this Workshop was justified by the impressive growth of work dealing with this subject during the last two or three years. Indeed, thanks to recent progresses of epitaxial growth techniques, such as Molecular Beam Epitaxy, it is now possible to realize semiconductor layers ( e.g. GaAs) with thicknesses controlled within one atomic layer, sandwiched between insulating layers (e.g. AlGaAs). When the semiconducting layer is very thin, i.e. less than 15 nm, the energy of the carriers corresponding to their motion perpendicular to these layers is quantized, forming subbands of allowed energies. Because of the low effective masses in these semiconducting materials, the oscillator strengths corresponding to intersubband transitions are extremely large and quantum optical effects become giant in the 5 - 20 ~ range: photoionization, optical nonlinearities, ... Moreover, a great theoretical surprise is that - thanks to the robustness of the effective mass theory - these quantum wells are a real life materialization of our old text book one-dimensional quantum well ideal. Complex physical phenomena may then be investigated on a simple model system.

The symposium on Acoustical Signal Processing in the Central Auditory System which was held in Prague on September 4--7, 1996 was the third in a series organized in Prague, after the Neuronal Mechanisms of Hearing symposium in 1980 and Auditory Pathway - Structure and Function symposium in 1987. Approximately 100 scientists regis tered for the symposium and presented 82 separate papers and posters. The present vol ume contains 53 of these contributions, mostly presented at the symposium as invited review papers. Several essential changes occurred since the previous meeting in 1987. In auditory neuroscience, recently developed methods opened new horizons in the investigation of the structure and function of the central auditory pathway. Methods like c-fos tracing tech niques and monoclonal antibodies for neurotransmitters and their receptors, like the intro duction of electrophysiological recording from brain slices have made possible new insights into the function of individual neurons and their interconnections, particularly in the cochlear nuclei and in the superior olivary complex. Integrative approaches towards understanding the central auditory function started to dominate in the field. It is not easy at the present time to differentiate between purely morphological and neurochemical ap proaches; similarly electrophysiological approaches are accompanied inevitably by behav ioral and psychophysical studies. The understanding of human brain function advanced significantly during the last several years. mainly due to the contribution of magneto encephalography. positron emission tomography and functional nuclear magnetic reso nance imaging.

The inverse scattering problem is central to many areas of science and technology such as radar and sonar, medical imaging, geophysical exploration and nondestructive testing. This book is devoted to the mathematical and numerical analysis of the inverse scattering problem for acoustic and electromagnetic waves. In this third edition, new sections have been added on the linear sampling and factorization methods for solving the inverse scattering problem as well as expanded treatments of iteration methods and uniqueness theorems for the inverse obstacle problem. These additions have in turn required an expanded presentation of both transmission eigenvalues and boundary integral equations in Sobolev spaces. As in the previous editions, emphasis has been given to simplicity over generality thus providing the reader with an accessible introduction to the field of inverse scattering theory.

Review of earlier editions:

"Colton and Kress have written a scholarly, state of the art account of their view of direct and inverse scattering. The book is a pleasure to read as a graduate text or to dip into at leisure. It suggests a number of open problems and will be a source of inspiration for many years to come."

SIAM Review, September 1994

"This book should be on the desk of any researcher, any student, any teacher interested in scattering theory."

Mathematical Intelligencer, June 1994"

Surface Acoustic Waves in Inhomogeneous Media covers almost all important problems of the interaction of different types of surface acoustic waves with surface inhomogeneities. The problems of surface acoustic wave interaction with periodic topographic gratings widely used in filters and resonators are under careful consideration. The most important results of surface wave scattering by local defects such as grooves, random roughness, elastic wedges are given. Different theoretical approaches and practical rules for solving the surface wave problems are presented.

The Advanced Study Institute (AS!) considered a number offacets of the very rapidly advancing field of theoretical and experimental aspects of ultrashort processes in condensed matter. Common threads exist between a series of example cases. One major subgroup of topics involves the ultrashort dynamics of excitations of various "particles" produced through the interactions of condensed matter with ultrashort duration laser light. Examples ofthe excitations include electronic and hole carriers, electron-hole plasma, phonons, vibrons and rotons, two phonon states, and excitons. Experimentation on the dynamics of such excitations, are carried out in the bulk, at surfaces, in thin films, and in quantum wells. The dynamical steps which the excitations usually undergo include photo-excitation, local thermalization, particle-particle interaction, particle phonon interactions and eventual return to true thermal equilibrium. This ASI was organized to benefit particularly advanced graduate students, specifically, those near the end of their Ph.D. thesis projects, and also for postdoctoral scholars already active in the field. The overall organizational goal was centered around a set oftutorially based lectures intermingled with full scale discussion periods of equal time and importance as the lectures. The general discussion periods were designed to offer to the participants ample time to ask detailed questions and to make comments and contributions of their own. In order to complete the involvement of the participants a full length poster session was also held. A representative set of abstracts of these posters appear as an Appendix to the lectures.

This eagerly awaited follow-up to Nonlinear Control Systems incorporates recent advances in the design of feedback laws, for the purpose of globally stabilizing nonlinear systems via state or output feedback. The author is one of the most prominent researchers in the field.

This book had its conception when Dr. Gudkov visited me in Austin in the Fall of 1995 and urged me to join him in writing a review of the field of magnetoacoustic polarization phenomena. I protested that, although my students and I had done some early work on this topic, most of the later work was done by researchers at the Institute for Metal Physics and by other investigators in the former Soviet Union. He eventually persuaded me that my initial contribution and general experience with magnetoacoustic phenomena qualified me to serve as a co-author. When I considered the fact that the extensive exploration of magnetoacoustic phenomena in the former Soviet Union was relatively unknown to Western scientists, I agreed to work with him on this project. In order to make the material more accessible to nonspecialists, we have adopted consistent notation throughout the text and redrawn the figures from published papers in a consistent fashion. Because our two institutions lie on opposite sides of the world, we needed some financial support to bring the book to fruition. We are very grateful to the Science Program for International Collaboration of the North Atlantic Treaty Organization for financial support through Grant No. HTECH. CRG 951549. I have dedicated this book to my wife, Janie, in recognition of the support she has given me throughout my professional career. J. D.

Quantum mechanics and the Schrodinger equation are the basis for the de scription of the properties of atoms, molecules, and nuclei. The development of reliable, meaningful solutions for the energy eigenfunctions of these many is a formidable problem. The usual approach for obtaining particle systems the eigenfunctions is based on their variational extremum property of the expectation values of the energy. However the complexity of these variational solutions does not allow a transparent, compact description of the physical structure. There are some properties of the wave functions in some specific, spatial domains, which depend on the general structure of the Schrodinger equation and the electromagnetic potential. These properties provide very useful guidelines in developing simple and accurate solutions for the wave functions of these systems, and provide significant insight into their physical structure. This point, though of considerable importance, has not received adequate attention. Here we present a description of the local properties of the wave functions of a collection of particles, in particular the asymptotic properties when one of the particles is far away from the others. The asymptotic behaviour of this wave function depends primarily on the separation energy of the outmost particle. The universal significance of the asymptotic behaviour of the wave functions should be appreciated at both research and pedagogic levels. This is the main aim of our presentation here."

The papers in this Volume were given at a two-day Conference on the subject of Optoelectronics in Medicine. The meeting was held in Florence, and promoted by the Consortium Centro di Eccellenza Optronica (C.E.O.). It represented the first of a series of Meetings on Optoelectronics that C.E.O. is organizing in order to stimulate new developments in this field and more efficient cooperation among local, national, and international research centers, industries, utilizers, etc .. Italian scientists have contributed consistently to the development of laser sources and to their applications to Medicine. A significant role has also been played by research institutes and industries in Florence. However, in this Conference, and in the Proceadings only a few Italian scientists were invited to present a lecture, thus offering the local and national communities as wide an international view as possible. Many more were present, however, as chairmen, and contributed successfully to making the discussions stimulating and fruitful. AB Editor, I had to substitute last-minute missing manuscripts with papers of my own, in order to keep the scheduled index of papers. The contributions presented at the Conference are written as extended, review like papers to provide a broad and representative coverage of the fields of light sources, optoelectronic systems for medical diagnosis, and light and laser applications to Medicine."

Microphone arrays have attracted a lot of interest over the last few decades since they have the potential to solve many important problems such as noise reduction/speech enhancement, source separation, dereverberation, spatial sound recording, and source localization/tracking, to name a few. However, the design and implementation of microphone arrays with beamforming algorithms is not a trivial task when it comes to processing broadband signals such as speech. Indeed, in most sensor arrangements, the beamformer output tends to have a frequency-dependent response. One exception, perhaps, is the family of differential microphone arrays (DMAs) who have the promise to form frequency-independent responses. Moreover, they have the potential to attain high directional gains with small and compact apertures. As a result, this type of microphone arrays has drawn much research and development attention recently. This book is intended to provide a systematic study of DMAs from a signal processing perspective. The primary objective is to develop a rigorous but yet simple theory

for the design, implementation, and performance analysis of DMAs. The theory includes some signal processing techniques for the design of commonly used first-order, second-order, third-order, and also the general "N"th-order DMAs. For each order, particular examples are given on how to form standard directional patterns such as the dipole, cardioid, supercardioid, hypercardioid, subcardioid, and quadrupole. The study demonstrates the performance of the different order DMAs in terms of beampattern, directivity factor, white noise gain, and gain for point sources. The inherent relationship between differential processing and adaptive beamforming is discussed, which provides a better understanding of DMAs and why they can achieve high directional gain. Finally, we show how to design DMAs that can be robust against white noise amplification.