An Investigation Of Acoustic Interaction With The Ocean Bottom From Experimental Time Series Generated By Explosive Sources PDF Download
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Author | : David Paul Knobles |
Publisher | : |
Total Pages | : 106 |
Release | : 1983 |
Genre | : Ocean bottom |
ISBN | : |
Download An Investigation of Acoustic Interaction with the Ocean Bottom from Experimental Time Series Generated by Explosive Sources Book in PDF, ePub and Kindle
Received time series from explosive sources in an abyssal plains ocean environment are compared to simulated time series calculated by a ray theory model. The comparisons yield information concerning the geoacoustic profile with a single sediment layer. The comparisons are made in various frequency bands to aid in identifying sediment penetrating arrivals by taking advantage of the frequency dependence of the absorption of the sediment. For shorter ranges, the sediment penetrating rays reflect off the basement. Also, as the range decreases, the fraction of received energy due to reflections at the water-sediment interface increases. Discrepancies between the experimental and simulated time series are interpreted in terms of reflections from thin layers within the sediment and scattered basement reflections
Author | : Paul Vidmar (J.) |
Publisher | : |
Total Pages | : 128 |
Release | : 1986 |
Genre | : Ocean bottom |
ISBN | : |
Download Synopsis of Recent Bottom Interaction Research at ARL:UT Book in PDF, ePub and Kindle
Author | : William A. Kuperman |
Publisher | : Springer Science & Business Media |
Total Pages | : 700 |
Release | : 2013-03-13 |
Genre | : Science |
ISBN | : 1468490516 |
Download Bottom-Interacting Ocean Acoustics Book in PDF, ePub and Kindle
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.
Author | : |
Publisher | : |
Total Pages | : 1532 |
Release | : 1984 |
Genre | : Science |
ISBN | : |
Download Government Reports Announcements & Index Book in PDF, ePub and Kindle
Author | : National Research Council |
Publisher | : National Academies Press |
Total Pages | : 220 |
Release | : 2003-05-22 |
Genre | : Science |
ISBN | : 0309133157 |
Download Ocean Noise and Marine Mammals Book in PDF, ePub and Kindle
For the 119 species of marine mammals, as well as for some other aquatic animals, sound is the primary means of learning about the environment and of communicating, navigating, and foraging. The possibility that human-generated noise could harm marine mammals or significantly interfere with their normal activities is an issue of increasing concern. Noise and its potential impacts have been regulated since the passage of the Marine Mammal Protection Act of 1972. Public awareness of the issue escalated in 1990s when researchers began using high-intensity sound to measure ocean climate changes. More recently, the stranding of beaked whales in proximity to Navy sonar use has again put the issue in the spotlight. Ocean Noise and Marine Mammals reviews sources of noise in the ocean environment, what is known of the responses of marine mammals to acoustic disturbance, and what models exist for describing ocean noise and marine mammal responses. Recommendations are made for future data gathering efforts, studies of marine mammal behavior and physiology, and modeling efforts necessary to determine what the long- and short-term impacts of ocean noise on marine mammals.
Author | : |
Publisher | : |
Total Pages | : 1332 |
Release | : 1984 |
Genre | : Government reports announcements & index |
ISBN | : |
Download Government Reports Annual Index Book in PDF, ePub and Kindle
Author | : Salvatore R. Santaniello |
Publisher | : |
Total Pages | : 39 |
Release | : 1972 |
Genre | : |
ISBN | : |
Download Digital Processing of Explosive-Source Ocean-Bottom-Reflected Acoustic Signals Book in PDF, ePub and Kindle
Low-frequency (100-Hz to 800-Hz) measurements of bottom-reflection losses in the North Pacific Ocean are discussed with respect to processing and modeling techniques. The data were acquired using shallow-depth (500-foot) explosive sound sources and a deep-depth (11,000-foot) hydrophone and were first processed on a total energy basis in 1/3-octave bands. An inverse filtering technique (deconvolution) for improving the ability to resolve sub-bottom reflections was successfully implemented and is also described. A multi-layered, absorbing, ocean bottom model was constructed and gave fair to good prediction of bottom loss. The structure of the model was determined mainly by acoustic methods where the composition was estimated from geological descriptions for the area. The model's inadequacies, particularly the importance of attenuation in low-frequency bottom-reflection prediction, are discussed. (Author).
Author | : Hiroshi Kawahara |
Publisher | : |
Total Pages | : 177 |
Release | : 1984 |
Genre | : Fluids |
ISBN | : |
Download Asymptotic Analysis of Ocean Bottom Reflected Acoustic Fields Book in PDF, ePub and Kindle
It has been observed in the deep ocean that the total acoustic field generated by a harmonic point source placed in the water column near the ocean bottom is characterized by strong interference between the field reflected off the bottom and the direct field through the water column. The amplitude of this total field thus shows a distinct spatial interference pattern with horizontal range. This thesis involves the analytic computation of the bottom reflected acoustic field using assumed geoacoustic models in order to understand the mechanism of propagating waves in ocean bottom sediments. The analytic results obtained are based on asymptotic approximations valid in the far field and characterize different types of rays which contribute to the total reflected field. Therefore, they provide physical insight into the understanding of energy partitioning in the sediments. The methods developed in this thesis are applied both to the examination of the fields generated by various canonical geoacoustic models and to actual experimental pressure field measurements made by Frisk and his co-workers. Extensive tests to determine which major ray paths contribute to the total reflected field are performed throughout horizontal range as well as an investigation of the effects of geoacoustic parameters on such rays.
Author | : T. Akal |
Publisher | : Springer |
Total Pages | : 0 |
Release | : 2012-07-27 |
Genre | : Science |
ISBN | : 9781461292937 |
Download Ocean Seismo-Acoustics Book in PDF, ePub and Kindle
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.
Author | : |
Publisher | : |
Total Pages | : 1528 |
Release | : 1984 |
Genre | : Government reports announcements & index |
ISBN | : |
Download Government Reports Annual Index: Keyword A-L Book in PDF, ePub and Kindle