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Effects Of The Sea Bed On Acoustic Propagation
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Book Synopsis Effects of the Sea-Bed on Acoustic Propagation by : T. Akal
Download or read book Effects of the Sea-Bed on Acoustic Propagation written by T. Akal and published by . This book was released on 1983 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The sea-bed is known to be the controlling factor in low-frequency shallow-water acoustics. In lossy sea-beds waterborne sound is attenuated both the compressional-wave attenuation in the bottom and by the coupling of sound into shear waves. The complicated frequency-dependent effect of the sea-bed on propagation has been studied theoretically, and it is found that bottom loss increases with decreasing frequency down to near the cut-off frequency of the ocean waveguide, at which frequency seismic propagation by interface waves on the sea floor becomes more important than acoustic propagation. It is also found that while propagation losses in the water column are strongly dependent on bottom type, a feature such as the optimum frequency of acoustic propagation in the water column is only slightly dependent on sea-bed properties. Broadband propagation data collected in different areas of the Mediterranean Sea and the eastern North Atlantic are shown to support these theoretical findings. (Author).
Book Synopsis Sound Propagation in the Sea by : Robert J. Urick
Download or read book Sound Propagation in the Sea written by Robert J. Urick and published by . This book was released on 1979 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Computational Ocean Acoustics by : Finn B. Jensen
Download or read book Computational Ocean Acoustics written by Finn B. Jensen and published by Springer Science & Business Media. This book was released on 2011-06-10 with total page 808 pages. Available in PDF, EPUB and Kindle. Book excerpt: Senior level/graduate level text/reference presenting state-of-the- art numerical techniques to solve the wave equation in heterogeneous fluid-solid media. Numerical models have become standard research tools in acoustic laboratories, and thus computational acoustics is becoming an increasingly important branch of ocean acoustic science. The first edition of this successful book, written by the recognized leaders of the field, was the first to present a comprehensive and modern introduction to computational ocean acoustics accessible to students. This revision, with 100 additional pages, completely updates the material in the first edition and includes new models based on current research. It includes problems and solutions in every chapter, making the book more useful in teaching (the first edition had a separate solutions manual). The book is intended for graduate and advanced undergraduate students of acoustics, geology and geophysics, applied mathematics, ocean engineering or as a reference in computational methods courses, as well as professionals in these fields, particularly those working in government (especially Navy) and industry labs engaged in the development or use of propagating models.
Book Synopsis Fundamentals of Ocean Acoustics by : L.M. Brekhovskikh
Download or read book Fundamentals of Ocean Acoustics written by L.M. Brekhovskikh and published by Springer Science & Business Media. This book was released on 2006-04-10 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an up-to-date introduction to the theory of sound propagation in the ocean. The text treats both ray and wave propagation and pays considerable attention to stochastic problems such as the scattering of sound at rough surfaces and random inhomogeneities. An introductory chapter that discusses the basic experimental data complements the following theoretical chapters. New material has been added throughout for this third edition. New topics covered include: - inter-thermocline lenses and their effect on sound fields - weakly divergent bundles of rays - ocean acoustic tomography - coupled modes - sound scattering by anisotropic volume inhomogeneities with fractal spectra - Voronovich's approach to sound scattering from the rough sea surface. In addition, the list of references has been brought up to date and the latest experimental data have been included.
Book Synopsis Ocean and Seabed Acoustics by : George V. Frisk
Download or read book Ocean and Seabed Acoustics written by George V. Frisk and published by Pearson Education. This book was released on 1994-01-02 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Respected scientist and educator George V. Frisk draws on his extensive professional experience to demonstrate how the ocean environment provides an excellent setting in which to display general principles of wave propagation that are also applicable to other areas of wave physics. Ocean and Seabed Acoustics proceeds with a derivation of elementary solutions to the wave equation in free space and then progressively addresses problems of increasing complexity. This book concludes with a discussion of acoustic wave propagation due to a point source in an inhomogeneous waveguide with lossy boundaries.
Book Synopsis Acoustics and the Sea-bed by : N. G. Pace
Download or read book Acoustics and the Sea-bed written by N. G. Pace and published by . This book was released on 1983 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Progress in Underwater Acoustics by : Harold Merklinger
Download or read book Progress in Underwater Acoustics written by Harold Merklinger and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 815 pages. Available in PDF, EPUB and Kindle. Book excerpt: IMAGE TRACKS AT HALIFAX by L.B. Felsen All living kind much effort spend Some model modes, some model rays, To cope with their environment Some feel that spectra all portrays. Some use their eyes, some use their nose Then there are those who with despatch, To sense where other things repose. Take refuge in the ocean wedge. For one group, nothing's more profound Than to explore the world with sound. If things get messy, randomize. These audio diagnosticians What's partly smooth, determinize. You ponder, is it this or that? Go by the name of acousticians. And wish you were a lowly bat They regularly meet to check Whether their sonogram's on track. The meeting's hosts did treat us well. With images stored in their packs, They let the climate cast its spell. This year they came to Halifax. No weath'ry hope was placed in vain. There they combined with ocean types We were exposed to wind and rain, And each could hear the other's gripes. We glimpsed blue sky through clouds dispersed. A meeting naturally does start But rainy sequence was reversed: Reviewing present state of art. The ocean types would like it wet What we found out is where it's at: Yet they got stuck with sun instead. We cannot hope to match the bat Each confrence has the same refrain: Computer printouts by the reams It has been fun to meet again.
Book Synopsis Springer Handbook of Acoustics by : Thomas Rossing
Download or read book Springer Handbook of Acoustics written by Thomas Rossing and published by Springer Science & Business Media. This book was released on 2007-06-21 with total page 1179 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an unparalleled modern handbook reflecting the richly interdisciplinary nature of acoustics edited by an acknowledged master in the field. The handbook reviews the most important areas of the subject, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest research and applications are incorporated throughout, including computer recognition and synthesis of speech, physiological acoustics, diagnostic imaging and therapeutic applications and acoustical oceanography. An accompanying CD-ROM contains audio and video files.
Download or read book Ocean Acoustics written by J.A. DeSanto and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Topics volume is devoted to a study of sound propagation in the ocean. The effect of the interior of the ocean on underwater sound is analogous to the effect of a lens on light. The oceanic lens is related, as in light propagation, to the index of refraction of the medium. The latter is giv~n by the ratio of the sound frequency to the speed of sound in water, typi ca lly about 1500 m s -1. It is the vari ation of the sound speed due to changing temperature, density, salinity, and pres sure in the complex ocean environment which creates the lens effect. Many oceanic processes such as currents, tides, eddies (circulating, translating regions of wa ter), and internal waves (the wave-like structure of the oceanic density variabil ity) contri bute in turn to the changes in sound speed'. The net effect of the ocean lens is to trap and guide sound waves in a channel created by the lens. The trapped sound can then propagate thousands of miles in this oceanic waveguide. In addition to the propagation in the interior of the ocean, sound can propagate into and back out of the ocean bottom as well as scatter from the ocean surface. Just as the sound produced by a loudspeaker in a room is affected by the walls of the room, so the ocean boundaries and the material properties below the ocean bottom are essential ingredients in the problem.
Download or read book Ocean Seismo-Acoustics written by T. Akal and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 898 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seafloor investigation has long been a feature of not only seismology but also of acoustics. Indeed it was acoustics that produced depth sounders, giving us the first capability of producing both global and local maps of the seafloor. Subsequently, better instrumentation and techniques led to a clearer, more quantitative picture of the seabed itself, which stimulated new hypotheses such as seafloor spreading through the availability of more reliable data on sediment thickness over ocean basins and other bottom features. Geologists and geophysicists have used both acoustic and seismic methods to study the seabed by considering the propagation of signals arising from both natural seismic events and man-made impulsive sources. Although significant advances have been made in instrumentation, such as long towed geophysical arrays, ai r guns and ocean bot tom seismometers, the pic ture of the seafloor is still far from complete. Underwater acoustics concerns itself today with the phenomena of propagation and noise at frequencies and ranges that require an understanding of acoustic interaction at both of its boundaries, the sea surface and seafloor, over depths ranging from tens to thousands of meters. Much of the earlier higher frequency (>1 kHz) work included the characterization of the seafloor in regimes of reflection coefficients which were empirically derived from surveys. The results of these studies met with only limited success, confined as they were to those areas where survey data existed and lacking a physical understanding of the processes of reflection and scattering.
Book Synopsis Impact of Littoral Environmental Variability on Acoustic Predictions and Sonar Performance by : Nicholas G. Pace
Download or read book Impact of Littoral Environmental Variability on Acoustic Predictions and Sonar Performance written by Nicholas G. Pace and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 592 pages. Available in PDF, EPUB and Kindle. Book excerpt: The limiting influence of the environment on sonar has long been recognised as a major challenge to science and technology. As the area of interest shifts towards the lit toral, environmental influences become dominant both in time and space. The manyfold challenges encompass prediction, measurement, assessment and adaptive responses to maximize the effectiveness of systems. Although MCM and ASW activities are dom inated in different ways and scales by the environment, both warfare areas have had to consider the significantly changing requirements posed by operations in the littoraL The fundamental scientific issues involved in developing models relating acoustics to the environment are matched in difficulty by the need for data for their validation and eventual practical use for prediction. In many instances the need is for on-line adaptation of systems to changing circumstances whilst other needs are for the Ionger term planning activities. This book and the attached full-color CD are the proceedings of a conference organ ised by the SACLANT Undersea Research Centre, held at Villa Marigola, Lerici, Italy, on 16-20 September 2002. The fundamental problems associated with environmental 1 variability and sonar were explored at a previous SACLANTCEN conference in 1990. These problems have not gone away but, on the one hand are exaggerated by the move to the littoral and on the other hand, are open to treatrnent in new ways that advances in technology and computer power allow.
Book Synopsis Ocean Variability & Acoustic Propagation by : J. Potter
Download or read book Ocean Variability & Acoustic Propagation written by J. Potter and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 599 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fifteen years ago NATO organised a conference entitled 'Ocean Acoustic Modelling'. Many of its participants were again present at this variability workshop. One such participant. in concluding his 1975 paper, quoted the following from a 1972 literature survey: ' ... history presents a sad lack of communications between acousticians and oceanographers' Have we done any better in the last 15 years? We believe so, but only moderately. There is still a massive underdeveloped potential for acousticians and oceanographers to make significant progress together. Currently, the two camps talk together insufficiently even to avoid simple misun derstandings. such as those in Table 1. Table 1 Ocsanographic and acoustic jargon (from an idea by Pol/ardi Jargon Oceanographic use Acoustic use dbordB decibar (depth in m) decibel (energy level) PE primitive equations parabolic equations convergence zone converging currents converging rays (downwelling water) (high energy density) front thermohaline front wave, ray or time front speed water current speed sound propagation speed 1 The list goes on.
Book Synopsis Bottom-Interacting Ocean Acoustics by : William A. Kuperman
Download or read book Bottom-Interacting Ocean Acoustics written by William A. Kuperman and published by Springer Science & Business Media. This book was released on 2013-03-13 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: vi These categories seem to represent the basic breakdown by field of present-day research in this area. Though each paper has been classified into one of these categories (for conference organization purpose), many papers overlapped two or three areas. It is also interesting to note that not only are scientific results being communicated, but the latest techniques and the state-of-the-art tools of the trade (existing and in development) are also being presented. The forty-six papers presented at this conference represent the work of seventy scientists working at universities, government laboratories, and industrial laboratories in seven different countries . We would like to thank the contributors for their efforts and especially for their promptness in providing the editors with their final manuscripts. William A. Kuperman Finn B. Jensen La Spezia, Italy July 1980 CONTENTS GEOACOUSTIC PROPERTIES OF MARINE SEDIMENTS Attenuation of Sound in Marine Sediments . • 1 J. M. Hovem Directivity and Radiation Impedance of a Transducer 15 Embedded in a Lossy Medium . •• •••••• G. H. Ziehm Elastic Properties Related to Depth of Burial, Strontium Content and Age, and Diagenetic Stage in Pelagic Carbonate Sediments . . • • . • • • . 41 M. H. Manghnani, S. O. Schianger, and P. D. Milholland Application of Geophysical Methods 'and Equipment to Explore the Sea Bottom . •• •••. • 53 H. F. Weichart The Acoustic Response of Some Gas-Charged Sediments in the Northern Adriatic Sea • • • • . • • • • 73 A.
Book Synopsis Ocean Acoustic Propagation by Finite Difference Methods by : D. Lee
Download or read book Ocean Acoustic Propagation by Finite Difference Methods written by D. Lee and published by Elsevier. This book was released on 2014-06-28 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: A concise guide to the theory and application of numerical methods for predicting ocean acoustic propagation, also providing an introduction to numerical methods, with an overview of those methods presently in use. An in-depth development of the implicit-finite-difference technique is presented together with bench-mark test examples included to demonstrate its application to realistic ocean environments. Other applications include atmospheric acoustics, plasma physics, quantum mechanics, optics and seismology.
Book Synopsis Effects of Tidally-Varying Sound Speed on Acoustic Propagation Over a Sloping Ocean Bottom by : W. L. Siegmann
Download or read book Effects of Tidally-Varying Sound Speed on Acoustic Propagation Over a Sloping Ocean Bottom written by W. L. Siegmann and published by . This book was released on 1979 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: The influence of sound-speed fluctuations on propagation of a CW signal in an ocean with a uniformly-sloping bottom and a horizontal surface is analyzed using ray theory. The mean sound-speed structure is modeled as bilinear, with bottomed source and receiver above and below the SOFAR axis, respectively. The horizontally-independent fluctuations oscillate with a 12-h period in the upper ocean. An examination is made of possible types of rays for down-slop propagation that might exist, depending on bottom-slope angle and source-receiver separation. The total acoustic field is investigated for its dependence on these parameters and time. For certain conditions when up to three rays comprise the mean total field, three patterns of time evolution are described, each of which may have significant amplitude variations. Numerically-computed examples of each type are presented. The linear relationships between phase variations of individual rays and the sound-speed fluctuations are derived. Then, formulas are developed to explain the most frequent behavior of the relative amplitude and phase of the multipath total field. Predictions from the formulas show very good agreement with the numerical calculations. (Author).
Book Synopsis In Situ High-frequency Acoustic Propagation Measurements in Marine Sediments in the Santa Barbara Shelf, California by : Y. Igarashi
Download or read book In Situ High-frequency Acoustic Propagation Measurements in Marine Sediments in the Santa Barbara Shelf, California written by Y. Igarashi and published by . This book was released on 1973 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements were made of sound speed and attenuation in marine sediments at 15, 30, and 60kHz by means of in situ acoustic probe instrumentation in conjunction with CURV II. These experiments were conducted in silty sand and sandy silt Continental Shelf areas of the Santa Barbara Channel, California. The main conclusions are: (1) attenuation was found to be about 3, 10, and 20 dB per meter at 15, 30, and 60 kHz, respectively; (2) for the attenuation equation, alpha = K(f to the nth power) (where alpha is sound attenuation in dB per meter, K is a dimensional material parameter, and f is frequency in kHz), the exponent, n, was found to be about 1.2, and K varied from approximately 0.1 to 0.2; (3) no significant sound-speed dispersion was found, in agreement with many other investigations; and (4) individual acoustic measurements made in close proximity to one another in a nominally homogeneous bottom can vary appreciably, although their average values may be in close agreement. (Author).
Book Synopsis European Conference on Underwater Acoustics by : M. Weydert
Download or read book European Conference on Underwater Acoustics written by M. Weydert and published by CRC Press. This book was released on 2004-01-14 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book represents the proceedings of the Conference on Underwater Acoustics, held in September 1992, to bring together all the various disciplines involved in a forum to present the latest research on all aspects of marine acoustics.
