7.3 Suggestions for Future Work The research for this thesis has provided predictions that should lead to the implementation of a time-reversing array in the shallow ocean for practical applications, such as the communication method ...
These methods are combined with existing time - reversal techniques to produce a high resolution acoustic focus at an arbitrary location in the shallow ocean waveguide . Simulation , laboratory and at sea experiments support the theory ...
A cheap, easy single mode generator for field work would be a rather welcome advance in shallow water acoustics. The topic of time reversal (and its narrowband cousin, phase conjugation) mirroring has become a vibrant and lively one in ...
Author: Boris Katsnelson
Publisher: Springer Science & Business Media
Shallow water acoustics (SWA), the study of how low and medium frequency sound propagates and scatters on the continental shelves of the worlds oceans, has both technical interest and a large number of practical applications. Technically, shallow water poses an interesting medium for the study of acoustic scattering, inverse theory, and propagation physics in a complicated oceanic waveguide. Practically, shallow water acoustics has interest for geophysical exploration, marine mammal studies, and naval applications. Additionally, one notes the very interdisciplinary nature of shallow water acoustics, including acoustical physics, physical oceanography, marine geology, and marine biology. In this specialized volume the authors, all of whom have extensive at-sea experience in US and Russian research efforts, have tried to summarize the main experimental, theoretical, and computational results in shallow water acoustics, with an emphasis on providing physical insight into the topics presented.
4 Conclusions Two theories for the uncertainty of time domain propagation and reverberation in the presence of waveguide variability have been derived based on the method of normal modes , the narrow band approximation , perturbation ...
Author: N. G. Pace
Publisher: Springer Science & Business Media
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 littoral, environmental influences become dominant both in time and space. The manifold challenges encompass prediction, measurement, assessment, and adaptive responses to maximize the effectiveness of systems. Although MCM and ASW activities are dominated 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 the longer term planning activities. This book and the enclosed CD-ROM are the proceedings of a conference organised by the SACLANT Undersea Research Centre, and held at the Villa Marigola, Lerici, Italy, on 16-20 September 2002. CD-ROM Included: This volume contains a CD-ROM which in addition to an electronically searchable version of the proceedings, has full colour versions of figures which are printed in black and white in the book.
The theoretical narrow - band performance of TRAs in the presence of static and dynamic random media is presented in ( 63 ) ... Their computations predicted the azimuthal extent of a TRA's retrofocus in shallow water sound channels either ...
Author: Acoustical Society of AmericaPublish On: 2001
Computed narrow - band azimuthal time - reversing array retrofocusing in shallow water Michael R. Dungan and David R. ... revised 29 November 2000 ; accepted 25 June 2001 ) The process of acoustic time reversal sends sound waves back to ...
Devaney A 2004 Superresolution processing of multi-static data using time reversal and MUSIC to appear in J. Acoust. Soc. ... D R and Jackson D R 1992 Narrow band performance of phase conjugate arrays in dynamic random media J. Acoust.
Author: Luis L. Bonilla
Nowadays we are facing numerous and important imaging problems: nondestructive testing of materials, monitoring of industrial processes, enhancement of oil production by efficient reservoir characterization, emerging developments in noninvasive imaging techniques for medical purposes - computerized tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), X-ray and ultrasound tomography, etc. In the CIME Summer School on Imaging (Martina Franca, Italy 2002), leading experts in mathematical techniques and applications presented broad and useful introductions for non-experts and practitioners alike to many aspects of this exciting field. The volume contains part of the above lectures completed and updated by additional contributions on other related topics.
In this thesis , predictions are made for how a simple omni - directional noise field influences the probability that the signal amplitude from a narrow - band TRA will exceed the noise at the TRA's retrofocus .
ÅDD9994060 Dungan , Michael Robert . Predictions of narrow- The University of Alabama in Huntsville Oregon State University band'acoustic time reversal in the shallow ocean . Giblin , Timothy William . A temporal and specPh.D. 2000 .
2A18 and horizontal wave numbers in shallow water at noise on heart rate and cardiac arrhythmia during CASTROGIOVANNI , A : Numerical modeling and - Time - stable boundary conditions for finite - differlow frequencies using parabolic ...
... amorphous silicon multijunction modules ( DE91-015002 ] N92-12335 AMPLIFICATION Narrow - bandwidth diffraction ... A standard test set for numerical approximations to the shallow water equations in spherical geometry ( DE92-000385 ) ...
We show here that it is also stable for narrowband pulses , provided that the time - reversal mirror is large ... this leads to a version of the shallow - water equations which has an exact solution that corresponds to the edge wave .
Complex synthetic aperture radar imageries at C band and X band acquired during March 1989 in the Greenland Sea are ... ( 1 ) newly forming ice inside a tongue - shaped region called the Odden and ( 2 ) open water adjacent to the Odden .
AD - A061 514 GRA & I Long - Range Shallow - Water Bottom Reverberation , AD - A066 890 GRA & I The Statistical Properties of the Envelope of a Narrowband Reverberation Process . AD - A069 145 GRA & I Reverberation Spectrum Prediction ...
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At the same time it is an enclave of the modern, in that area of the Middle East which seems peculiarly wedded to the past. Wherever one travels in Israel one is overwhelmed by this contrast between the past and the modern.
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CORPS OF ENGINEERS - Blast Phenomena from Explosions at the Water Surface , by A. Sakurai , J. M. Pinkson Jr. and ... Large Nonsymmetric Deflections of Thin Shallow tion , by Philip Houser , Picatinny Arsenal ; and Shells , by John F.
ISMIC DATA PROCESSING - Conunuod VORWEGIAN SEA MODEL BASED DEPTH CONVERSION AND PROCESSING - A CASE STUDY OFFSHORE MID ... D AND 3 - D PHYSICAL ELASTIC MODELS USING PRESTACK REVERSE TIME MIGRATION SEISMIC REFLECTION METHOD SEISMIC ...
The time - varying , three- ( details below ) . dimensional subsurface hydrographic and velocity fields This paper ... and data analysis methods are described in lating vehicle and a shipboard acoustic Doppler current the next section .