Download or read book ONR Postdoctoral Fellowship Geoacoustic Inversion and Source Localization in a Randomly Fluctuating Shallow Water Environment written by and published by . This book was released on 2009 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The long-term goal of this project is to understand and mitigate the uncertainties of shallow-water acoustic inversions caused by strong oceanic temporal and spatial variability. To achieve this goal, we need to investigate the connection between acoustic signal fluctuations and the water-column variability, and further incorporate this connection into the acoustic inversions for increasing the inversion performance.
Download or read book Modal Mapping Techniques for Geoacoustic Inversion and Source Localization in Laterally Varying Shallow Water Environments written by and published by . This book was released on 2009 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The long-term goal of this research is to increase our understanding of shallow water acoustic propagation and its relationship to the three-dimensionally varying geoacoustic properties of the seabed.
Download or read book Important Elements In Geoacoustic Inversion Signal Processing and Reverberation in Underwater Acoustics written by Alex Tolstoy and published by . This book was released on 2008-01-01 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains a number of papers by leading researchers discussing their work on either geoacoustic inversion (GI), signal processing (SP), or reverberation. It is intended for scientists entering these fields as well as for experienced researchers. Chapter 1 (Tolstoy) begins the section on GI. It is a review article covering the main topics of GI and mentions such subjects as matched field processing (MFP), improved source localization and tracking, array element localization, propagation and parameter modeling, search methods, the nature of the search spaces, improving efficiency, sensitivities and uncertainty, benchmarking, and applications to simulated and test data. It is intended as a resource for understanding the GI area as well as for locating key references. Chapter 2 (Dosso) describes one of the most successful and most applied methods for GI: a Bayesian approach using a hybrid simulated annealing (SA) variant for optimization and Gibbs sampling to characterize the posterior probability density. The formulation is discussed here in mathematical detail. The emphasis in this chapter is on rigorous uncertainty estimation where the unknowns are considered to be random variables constrained by the data and prior information. Errors are assumed to be Gaussian distributed for the derivation of some key equations, and statistical tests are presented to support this assumption. Data from the PROSIM 97 experiment at numerous frequencies are analyzed. Chapter 3 (Chapman & Jiang) discusses the interpretation of matched field inversion results, particularly their limitations, and illustrates their analysis using multifrequency experimental data from the New Jersey continental shelf site that was selected on the basis of high spatial and temporal coherence across the array. They are concerned with the impact of data errors due to parameter correlations in Bayesian inversions, and the effect of the bottom slope in three dimensions (they conclude that only two dimensions are needed for their inversions). Chapter 4 (Michalopoulou & Nolte) begins as a review of Bayesian source localization methods but is primarily concerned with one such approach which the authors developed: the Optimum Uncertain Field Processor (OUFP). This is an approach used for target localization and tracking which reduces sensitivity to environmental mismatch by incorporating prior information. The method also produces posterior distributions permitting the quantification of uncertainty and error estimation of calculated parameters including environmental properties. Moving and multiple sources are discussed. Chapter 5 (Taroudakis) discusses modal inversion techniques in shallow water. Modal observables such as modal phase, modal arrivals, and dispersion curves using both the time and frequency domains are incorporated into linear and non-linear inversion procedures. The methods are based on geophysical analysis using normal mode propagation. Good separation of modes is required which is affected by the nature of the array and the frequencies used for the inversions in a given scenario. Chapter 6 (Baxley) is a review of the use of GI primarily to: (1) show results of simplified approaches to GI, (2) review the SWellEX experiments of 1993-1999 as a good testbed of GI, and (3) perform inversion using horizontal as well as vertical line arrays. The intention was the optimization of system performance for the localization and tracking of undersea targets using a variety of arrays and the Bartlett processor. Range-independence was assumed so that a simple normal mode model could be used. A number of parameters were estimated using a number of frequencies (less than 200Hz) assuming a simplified bottom. Chapter 7 (Rajan et al.) is a complete and mathematical discussion of modal inverse techniques. The chapter presents a formulation of the inverse problem, an estimation of the modal eigenvalue, demonstrations in RI and RD waveguides with discussions of error sources, spectral estimation, modal attenuation coefficients, sediment characteristics determined from modal dispersion data, integral equations, matrix inversion, resolution and variation of estimates, further demonstrations of inversion success for simulated and test data, and more. A complete coverage of modal issues is presented here. Chapter 8 (Tolstoy) is the final chapter on GI and concerns a volumetric (tomographic) GI method. This approach combines individual 2-D (range and depth slice) inversions on multiple arrays and for distributed sources into a full consistent 3-D (range, depth, and azimuth) image of the region bottom. It is discussed within the context of the Haro Strait test and concludes that information about array geometry (phone depths and shape) is essential for successful inversion where success is defined as high MFP values (at any and all frequencies with good signal-to-noise) at a unique set of parameters. Additionally, 3-D resolution may be improved via regularization to counter scarcity of resources. Chapter 9 (Arvelo) starts the section on signal processing with a detailed discussion of the factors affecting system performance, particularly at low frequencies (below 1 kHz). These include noise, especially as it affects coherence (temporal and spatial), waveguide variability (such as bathymetry), and scattering processes. A review of low-frequency coherence modeling and measurements is presented, and examples are provided to illustrate key points. Methods to circumvent the hard limits imposed by spatial coherence include the exploitation of multiple dimensions, such as the design of planar and volumetric arrays. Seismic coherence is also discussed. Chapter 10 (Sullivan & Candy) is a review of passive synthetic aperture processing (PASA). This approach to array processing utilizes the (towed) array motion to enhance its performance by explicitly incorporating this motion into the signal model. Historically, its name is based on the idea that the improved performance is equivalent to effectively having a longer array (the array appears to be larger when multiple phone locations can be combined coherently, and this approach is most effective for short aperture arrays). It is unique in that it treats the problem as a recursive estimation process rather than a beamforming process. Again, the primary interest here is system performance. Since it recursive in time, its application is limited to continuous signals (such as radiated noise) as opposed to short-term signals (such as pulses). The authors present the PASA development in mathematical detail (narrowband and broadband, single and multiple sources) including both simulated and experimental data. Chapter 11 (Zurk) completes the section on signal processing where concerns about waveguide mismatch are addressed by the development of more robust processing methods. Rather than attempting to determine ocean properties, many signal processors concentrate on the goal of devising techniques less dependent on the channel nature with the intent of improving system performance in uncertain environments. This can involve incorporating the statistics of the environment, using a calibration source, or developing invariant (robust) processors. These approaches are discussed here. Chapter 12 (Gauss) is the only chapter to concentrate on reverberation and presents a review of active sonar components coupled with signal processing for the purpose of detecting, localizing, and tracking undersea targets. Incomplete knowledge of the environment and clutter (reverberation from non-targets) are the primary limits on system performance. Clutter mechanisms include: bathymetry, the ocean surface roughness, fish, bubbles, and more. These mechanisms and methods to control their influence using frequencies 50 Hz to 5 kHz (single frequency and broadband), in deep and shallow water scenarios, are discussed. Deconvolution is critical to all reverberation efforts. Additionally, Doppler effects can be also used to separate signal contributions. The chapter concludes with a summary of contemporary issues and future trends. Finally, the observant reader will notice that this text is dedicated to Leon Sibul. Leon died quite unexpectedly early in 2007 with the intention of contributing a chapter to this book. We in the research community miss his mathematical insights and contributions to signal processing. We miss the chapter he would have given to us in this book. But most of all, we miss him.
Download or read book Geoacoustic Inversion in Laterally Varying Shallow water Environments Using High resolution Wavenumber Estimation written by Kyle M. Becker and published by . This book was released on 2002 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental method for extracting horizontal wavenumber spectra for point-source acoustic fields in laterally varying shallow water waveguides is discussed. The experiment was designed to provide input data for a perturbative inversion method for inferring the geoacoustic properties of the bottom. The input data are discrete values of horizontal wavenumbers that correspond the propagating modes in a shallow-water waveguide. Based on the asymptotic Hankel transform pair relationship between the complex pressure field and the depth-dependent Green's function, a high-resolution autoregressive (AR) spectral estimator is applied to extract wavenumber content. The estimator is characterized in terms of it performance on short-aperture noisy data. The estimator is then used on short-aperture synthetic acoustic data for extracting local horizontal wavenumber content for doing range-dependent geoacoustic inversion. Results are discussed in terms of discrete and continuous changes in the waveguide environment. The estimator is then applied to real data for a fixed receiver and towed source. For a source speed of 2 m/s, a shift was observed in the measured wavenumbers. Based on this observation, a method for measuring modal group velocity is presented from measurements of the shifted wavenumbers for a source towed out and back along the same track.
Download or read book Geoacoustic Inversions in a Very Shallow Water Environment written by Katherine Megan McArthur and published by . This book was released on 2002 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geoacoustic inversion in laterally varying shallow water environments using high resolution wavenumber estimation written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: I am especially grateful to ONR for providing the funding for me to do this work.
Download or read book Acoustic Sensing Techniques for the Shallow Water Environment written by Andrea Caiti and published by Springer. This book was released on 2017-04-30 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thisvolume contains thecollection of papers from the second workshop on Expe- mental Acoustic Inversion Techniques for Exploration of theShallow Water Environment. Theworkshopthemefollowedtheoriginalconceptofthe rstworkshop, heldinCarvoeiro, Portugal, in 1999, i.e., to focus on experiments and experimental techniques for acoustic sensing in the shallow ocean. More than forty leading international scientists were invited to meet in the picturesque town of St. Angelo on the island of Ischia, in June 2004, to discuss progress in the application of new experimental techniques for exploration and assessment of shallowwater environments. Acoustic techniques provide the most effective means for remote sensing of ocean and sea oor processes, and for probing the structure beneath the sea oor. No other energy propagates as ef ciently in the ocean: radio waves and visible light are severely limited in range because the ocean is a highly conductive medium. However, sound from bre- ing waves and coastal shipping can be heard throughout the ocean, and marine mammals communicate acoustically over basin scale distances.
Download or read book Special Issue on Geoacoustic Inversion in Range dependent Shallow water Environments written by N. Ross Chapman and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sound Transmission Through a Fluctuating Ocean written by Roger Dashen and published by Cambridge University Press. This book was released on 2010-06-10 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 1979 book attempts to connect the known structure of the ocean volume with experimental results in long-range sound transmission through the theory of wave propagation and the path-integral approach. The book is written at the post-graduate level, but has been carefully organised to give experimenters a grasp of important results without undue mathematics.
Download or read book Stochastic Differential Equations written by Peter H. Baxendale and published by World Scientific. This book was released on 2007 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first paper in the volume, Stochastic Evolution Equations by N V Krylov and B L Rozovskii, was originally published in Russian in 1979. After more than a quarter-century, this paper remains a standard reference in the field of stochastic partial differential equations (SPDEs) and continues to attract attention of mathematicians of all generations, because, together with a short but thorough introduction to SPDEs, it presents a number of optimal and essentially non-improvable results about solvability for a large class of both linear and non-linear equations.
Download or read book Communication Acoustics written by Jens Blauert and published by Springer Science & Business Media. This book was released on 2005-05-20 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: - Speech Generation: Acoustics, Models and Applications (Arild Lacroix). - The Evolution of Digital Audio Technology (John Mourjopoulos). - Audio-Visual Interaction (Armin Kohlrausch) . - Speech and Audio Coding (Ulrich Heute) . - Binaural Technique (Dorte Hammerhoei, Henrik Moeller). - Auditory Virtual Environment (Pedro Novo). - Evolutionary Adaptions for Auditory Communication (Georg Klump). - A Functional View on the Human Hearing Organ (Herbert Hudde). - Modeling of Binaural Hearing (Jonas Braasch). - Psychoacoustics and Sound Quality (Hugo Fastl). - Semiotics for Engineers (Ute Jekosch). - Quality of Transmitted Speech for Humans and Machines (Sebastian Möller).
Download or read book Handbook of Signal Processing in Acoustics written by and published by Springer Science & Business Media. This book was released on 2008 with total page 1932 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Acoustic Communication written by Andrea Simmons and published by Springer Science & Business Media. This book was released on 2002-10-04 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to communicate, animals send and receive signals that are subject to their particular anatomical, psychological, and environmental constraints. This SHAR volume discusses both the production and perception of acoustic signals. Chapters address the information that animals communicate, how the communication is developed and learned, and how communication systems have adapted and evolved within species. The book will give examples from a variety of species.
Download or read book Wind Energy and Wildlife Interactions written by Johann Köppel and published by Springer. This book was released on 2017-01-23 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a selection of new insights in understanding and mitigating impacts on wildlife and their habitats. Topics such as, species behaviour and responses; collision risk and fatality estimation; landscape features and gradients, are considered. Other chapters in the book cover the results of current research on mitigation; compensation; effectiveness of measures; monitoring and long-term effects; planning and siting. Examples are given of current research on shutdown on demand and curtailment algorithms. By identifying what we have learned so far, and which predominate uncertainties and gaps remain for future research, this book contributes to the most up to date knowledge on research and management options. This book includes presentations from the Conference on Wind Energy and Wildlife impacts (CWW15), March 2015, hosted by the Berlin Institute of Technology, which offered a platform to national and international participants to showcase the current state of knowledge in wind energy’s wildlife implications.
Download or read book Psychological Acoustics written by Earl D. Schubert and published by Hutchinson Ross Publishing Company. This book was released on 1979 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Introduction to Acoustical Holography written by B. P. Hildebrand and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the first papers by E. N. Leith and J. Upatnieks on the subject of holography appeared in 1961, there has been a virtual explosion of research activity in the field. More than SOO papers and articles on holo graphy have appeared in the last ten years. Many applications of holo graphy have been proposed, and some of these are beginning to enter the realm of usefulness. One of the applications that appears to hold great promise is acoustic imaging by means of holography. The first papers on this subject appeared in 1966. but already research activity in the field is burgeoning. Tbree symposia whoUy devoted to acoustical holography have been held and tbe papers published in book form. The purpose of this book is to bring together the results of research in acoustical holography, some of it as yet unpublished, under one cover so that workers in holography, nondestructive testing, medical imaging, underwater imaging, and seismic exploration can decide whether this new technique can be useful to them.
Download or read book Computational Acoustics written by Manfred Kaltenbacher and published by Springer. This book was released on 2017-07-10 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book presents a state-of-art overview of numerical schemes efficiently solving the acoustic conservation equations (unknowns are acoustic pressure and particle velocity) and the acoustic wave equation (pressure of acoustic potential formulation). Thereby, the different equations model both vibrational- and flow-induced sound generation and its propagation. Latest numerical schemes as higher order finite elements, non-conforming grid techniques, discontinuous Galerkin approaches and boundary element methods are discussed. Main applications will be towards aerospace, rail and automotive industry as well as medical engineering. The team of authors are able to address these topics from the engineering as well as numerical points of view.
