Author: Edwin Lee Hamilton Publisher: ISBN: Category : Marine sediments Languages : en Pages : 28
Book Description
The general objectives of this investigation were to determine and study those characteristics of the sea floor that affect sound propagation and the prediction of sonar performance; to support underwater acoustics' experiments and theory by furnishing information on the mass physical properties of sediments and rocks in the form of geoacoustic models of the sea floor; and to develop models of the sea floor which include gradients of sound velocity and attenuation, density, and elastic properties. Specifically, the minor objectives were to revise and review earlier work on the relations between frequency and attenuation of compressional (sound) waves in marine sediments and on the relations between attenuation and sediment porosity. The major objectives were to determine and predict variations of the attenuation of sound waves with depth in the sea floor.
Author: Edwin L. Hamilton Publisher: ISBN: Category : Languages : en Pages : 34
Book Description
Measurements of the velocity of shear waves at various depths in common watersaturated sediments were collected from published studies. Because measurements in marine sediments are rare, most of this information came from land geology and geophysics. This report considered the two end-member sediments types: sand and silt-clays, including turbidites which are alternating layers of silt-clay with thinner layers of silt and sand. The shear velocity measurements in sands were 29 selected, in situ values at depths to 12m. Data from laboratory and field studies indicate that shear wave velocity is proportional to the 1/3 to 1/6 power of pressure or depth in sands; that the 1/6 power is not reached until very high pressures are applied; and that for most sand bodies the exponent is between 3/10 and 1/4. Data from laboratory studies allow prediction of compressional wave (sound) as a function of depth in sands. The shear velocity measurements in silt-clays and turbidites used in this report include 47 measurements to depths of 650 m. Three linear equations were used to characterize the data. The shear velocity gradient in the upper 40m(4.65/sec) is 4-5 times greater than is the compressional wave (sound) velocity gradient in comparable sediments. At deeper depths, shear velocity and compressional velocity gradients are comparable. This report concludes with methods for prediction of shear wave velocity profiles and gradients in sea-floor sediments. This result will be of immediate use in a sophisticated model that determines sound energy losses when an acoustic wave interacts with the sea floor.
Author: Darrell Jackson Publisher: Springer Science & Business Media ISBN: 0387369457 Category : Science Languages : en Pages : 634
Book Description
This book is a research monograph on high-Frequency Seafloor Acoustics. It is the first book in a new series sponsored by the Office of Naval Research on the latest research in underwater acoustics. It provides a critical evaluation of the data and models pertaining to high-frequency acoustic interaction with the seafloor, which will be of interest to researchers in underwater acoustics and to developers of sonars. Models and data are presented so as to be readily usable, backed up by extensive explanation. Much of the data is new, and the discussion in on two levels: concise descriptions in the main text backed up by extensive technical appendices.
Author: Edwin L. Hamilton Publisher: ISBN: Category : Languages : en Pages : 50
Book Description
The general objectives of this investigation were (1) to determine and study those characteristics of the sea floor that affect the propagation of sound and the prediction of sonar performance; (2) to support underwater acoustic experiments and theory by furnishing information on the mass physical properties of sediments and rocks in the form of geoacoustic models of the sea floor; and (3) to develop models of the sea floor which include gradients of sound velocity and attenuation, density, and elastic properties. The specific objectives of this particular report were to determine and predict density profiles and gradients in common sediment and rock layers of the sea floor.
Author: George M. Bryan Publisher: ISBN: Category : Languages : en Pages : 15
Book Description
The overall objective of this research is an understanding of the relationship between the physical structure of the sea floor and its acoustic response, so that knowledge of one can be used to make inferences about the other. Inferences in both directions are important: the use of acoustics to investigate the physical and geophysical nature of the ocean floors is well known. Equally important is the ability to predict the acoustic response of the sea floor on the basis of its measurable physical properties.
Author: E. L. Hamilton Publisher: ISBN: Category : Bering Sea Languages : en Pages : 58
Book Description
The information and technology necessary to derive a valid geological-geophysical-acoustic model of the sea floor are presented. Two contrasting models are detailed and discussed: one in the Bering Sea which has a shallow-water, high-velocity, hard-sand bottom; and the Mohole (Guadalupe Site) model which has a deep-water, low-velocity, soft-clay bottom. Other models are to be reported in a continuing series. (Author).
Author: William A. Kuperman Publisher: Springer Science & Business Media ISBN: 1468490516 Category : Science Languages : en Pages : 700
Book Description
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: T. Akal Publisher: Springer Science & Business Media ISBN: 1461322014 Category : Science Languages : en Pages : 898
Book Description
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: Edwin Lee Hamilton
Author: Edwin L. Hamilton
Author: Darrell Jackson
Author: Edwin L. Hamilton
Author: Edwin Lee Hamilton
Author: George M. Bryan
Author: E. L. Hamilton
Author: William A. Kuperman
Author: T. Akal
Author: Laura Maraschi