Download or read book Sound Speed Profile Inversion in the Ocean written by Linda Boden and published by . This book was released on 1985 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Modal WKB Inversion Method for Determining Sound Speed Profiles in the Ocean and Ocean Bottom written by Kevin D. Casey and published by . This book was released on 1988 with total page 770 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two approaches to determining the ocean sound profile using measured acoustic modal eigenvalues are examined. Both methods use measured eigenvalues and mode dependent assumed values of the WKB phase integral as input data and use the WKB phase integral as a starting point for relating the index of refraction to depth. Inversion method one is restricted to monotonic or symmetric sound speed profiles and requires a measurement of the sound speed at one depth to convert the index of refraction profile to a sound speed profile. Inversion method two assumes that the sound speed at the surface and the minimum sound speed in the profile are known and is applicable to monotonic profiles and to general single duct sound speed profiles. For asymmetric profiles, inversion method two gives the depth difference between two points of equal sound speed in the portion of the profile having two turning points, and in the remainder of the profile it gives sound speed versus depth directly. A numerical implementation of the methods is demonstrated using idealized ocean sound speed profiles numerical experiments used to test the performance of the inversions using noisy data. The two methods are used to determine the sediment sound speed profiles in two shallow water waveguide models, and inversion method one is used to find the sediment sound speed profile using data from an experiment performed in the Gulf of Mexico. Theses. (edc).

Download or read book Project Review on Geophysical and Ocean Sound Speed Profile Inversion written by N. Bleistein and published by . This book was released on 1984 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes the status of the research projects on inverse problems at the Colorado School of Mines. We are engaged in two major projects in inverse problems: (I) inverse methods for reflector imaging; and (II) inverse methods for profile inversion in the ocean. In the first project we use 'high frequency' methods to invert backscatter (monostatic) observations. Our primary applications are to seabed mapping and seismic exploration although we have also implemented our method to image flaws in solids. Computer implementation of the current algorithm is discussed, and some indication of directions for extending the method is given. A unique feature of the second project is that the direction of variation of the sound speed profile (depth) is orthogonal to the direction of propagation (range). Again, high frequency methods are used and computer implementation is briefly discussed. Keywords include: velocity inversion Born Inversion, migration, stationary phase, singular function, and reflectivity function.

Download or read book Full Field Inversion Methods in Ocean and Seismo Acoustics written by Orest Diachok and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent advances in the power of inversion methods, the accuracy of acoustic field prediction codes, and the speed of digital computers have made the full field inversion of ocean and seismic parameters on a large scale a practical possibility. These methods exploit amplitude and phase information detected on hydrophone/geophone arrays, thereby extending traditional inversion schemes based on time of flight measurements. Full field inversion methods provide environmental information by minimising the mismatch between measured and predicted acoustic fields through a global search of possible environmental parameters. Full Field Inversion Methods in Ocean and Seismo-Acoustics is the formal record of a conference held in Italy in June 1994, sponsored by NATO SACLANT Undersea Research Centre. It includes papers by NATO specialists and others. Topics covered include: · speed and accuracy of acoustic field prediction codes · signal processing strategies · global inversion algorithms · search spaces of environmental parameters · environmental stochastic limitations · special purpose computer architectures · measurement geometries · source and receiving sensor technologies.

Download or read book Inverting for the Ocean Sound Speed Structure written by Michael Gregory Brown and published by . This book was released on 1982 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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:

Download or read book Inverse Methods for Sound Speed Estimation in the Ocean written by Tao Lin and published by . This book was released on 2014 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents theoretical and computational approaches for estimating sound-speed in the ocean under different conditions. The first part of the dissertation discusses a fast approach for solving the inverse problem of estimating sediment sound-speed based on the Deift-Trubowitz trace formula. Under certain assumptions, this algorithm can recover the sound speed profile in the seabed using pressure field measurements in the water column at low frequencies. The inversion algorithm requires solving a non-linear integral equation. In the past, Stickler and Zhou employed a first order Born approximation for solving the integral equation. This work introduces two new methods. The first is a modified Born approximation that improves upon a standard first order approximation, yet it is easy to implement; the second one is an approximation based on interpolating the integrand. It is shown that these methods work well with synthetic data in the numerical simulations. Results are compared to those of previously developed methods and demonstrate improvement especially at sharp changes in sound speed. Although the methods are stable and effective with noise-free data, problems arise when noise is considered. Regularization methods are developed to remedy this problem. Finally, we recognize that some assumptions necessary for this algorithm to work may not be realistic; several possibilities are presented to relax these limitations. In the second part, a method is developed for the estimation of source location and sound speed in the water column relying on linearization. The Jacobian matrix, necessary for the proposed linearization approach, includes derivatives with respect to Empirical Orthogonal Function coefficients instead of sound speed directly. First, the inversion technique is tested on synthetic arrival times, using Gaussian distributions for the errors in the considered arrival times. The approach is efficient, requiring a few iterations, and produces accurate results. Probability densities of the estimates are calculated for different levels of noise in the arrival times. Subsequently, particle filtering is employed for the estimation of arrival times from signals recorded during the Shallow Water 06 experiment. It has been shown in the past that particle filtering can be employed for the successful estimation of multipath arrival times from short-range data and, consequently, in geometry, bathymetry, and sound speed inversion. Here, probability density functions of arrival times computed via particle filtering are propagated backwards through the proposed inversion process. Inversion estimates are consistent with values reported in the literature for the same quantities. Lastly, it is shown that the results and estimates from fast simulated annealing applied to the same arrival times are very similar.

Download or read book Inference of the Ocean Sound Speed Profile Using Ambient Vertical Beam Noise written by Robert Thomas Taylor (Ph. D.) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation introduces a novel passive acoustic method for estimating the water column sound speed using the directionality of the ambient noise field measured with a vertical line array. In the absence of anthropogenic and biological sources, wind/wave sea surface interaction is the dominant source of mid-frequency noise insonifying the undersea environment. The resulting vertical noise field is anisotropic, with the directionality of the noise environment dependent on the paths of noise from the surface to the receiver. Changes in receiver depth, and associated sound speed, affect the level of ambient vertical noise at shallow elevation angles, providing the sensitivity necessary to acoustically estimate the in situ sound speed profile. Application of a clustering algorithm to an historical set of measured sound speed profiles allows for the characterization of common regional profiles. The scale and resulting undersampled nature of the ocean environment prompts the development of a novel interpolation scheme that retains acoustically important sound speed features in the region between available measurements. Motivated by the vertical stratification and motion of the water column, the interpolation scheme determines an appropriate vertical shift in depth to align sound speed features, enabling persistent features in the interpolated range between measurements. The developed method for inferring the sound speed profile combines sparse measurements of the vertical noise environment with an historical set of measured sound speed profiles and the vertical shifting method to provide an estimate of the in situ sound speed profile, with modeled results having error on the order of common active acoustic inversion methods. Finally, the method is applied to a low-frequency vertical line array data set, with results suggesting the array aperture was insufficient, and that further experimentation is needed

Download or read book Experimental Acoustic Inversion Methods for Exploration of the Shallow Water Environment written by Andrea Caiti and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, research on acoustic remote sensing of the ocean has evolved considerably, especially in studying complex physical and biological processes in shallow water environments. To review the state of the art, an international workshop was held at Carvoeiro, Portugal, in March 1999, bringing together leading international researchers in the field. In contrast to much of the recent theoretical work, emphasis was placed on the experimental validation of the techniques. This volume, based on presentations at this workshop, summarizes a range of diverse and innovative applications. The invited contributions explore the use of acoustics to measure bottom properties and morphology, as well as to probe buried objects within the sediment. Within the water column, sound is applied to imaging of oceanographic features such as currents and tides or monitoring of marine life. Another key theme is the use of sound to solve geometric inverse problems for precise tracking of undersea vehicles. Audience: This volume should be useful both to the novice seeking an introduction to the field and to advanced researchers interested in the latest developments in acoustic sensing of the ocean environment. The workshop was sponsored by the Fundação para a Ciêcia e a Tecnologia (Portuguese Foundation for Science and Technology).

Download or read book Three dimensional Inversion Technique in Ocean Acoustics Using the Parabolic Equation Method written by Camilo Carlos Roa and published by . This book was released on 2017 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: A three-dimensional parabolic equation (PE) and perturbation approach is used to invert for the depth- and range-dependent geoacoustic characteristics of the seabed. The model assumes that the sound speed profile is the superposition of a known range-independent profile and an unknown depth- and range-dependent perturbation. Using a Green's function approach, the total measured pressure field in the water column is decomposed into a background field, which is due to the range-independent profile, and a scattered field, which is due to the range-dependent perturbation. When the Born approximation is applied to the resulting integral equation, it can be solved for the range-dependent profile using linear inverse theory. Although the method is focused on inverting for the sound speed profile in the bottom, it can also invert for the sound speed profile in the water column. For simplicity, the sound speed profile in the water column was assumed to be known with a margin of error of ± 5 m/s. The range-dependent perturbation is added to the index of refraction squared n2(r), rather than the sound speed profile c(ro). The method is implemented in both Cartesian (x,y,z) and cylindrical (r,q,z) coordinates with the forward propagation of the field in x and r, respectively. Synthetic data are used to demonstrate the validity of the method [1]. Two inversion methods were combined, a Monte Carlo like algorithm, responsible for a starting approximation of the sound speed profile, and a steepest descent method, that fine-tuned the results. In simulations, the inversion algorithm is capable of inverting for the sound speed profile of a flat bottom. It was tested, for three different frequencies (50 Hz, 75 Hz, and 100 Hz), in a Pekeris waveguide, a range-independent layered medium, and a range-dependent medium, with errors in the inverted sound speed profile of less than 3%. Keywords: Three-dimensional parabolic equation method, geoacoustic inversion, range-dependent sound speed profile, linear inversion, Born approximation, Green's functions.

Download or read book Le cri de guerre des Prussiens written by and published by . This book was released on 1860 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inversion for Subbottom Sound Velocity Profiles in the Deep and Shallow Ocean written by Luiz Alberto Lopes de Souza and published by . This book was released on 2005 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Development of an Acoustic Inversion Technique for Estimating Near surface Sound Speed written by Holly A. Burch and published by . This book was released on 1998 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Precision Sound Velocity Profiles in the Ocean Volume Iii 31 Hours in the Tongue of the Ocean Sound Speed Temperature Etc march 1965 written by Ants T. Piip and published by . This book was released on 1967 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report covers a 31-hour anchor station in the Tongue of the Ocean, in extremely calm weather. 34 consecutive, detailed, high-precision profiles and their 10, 20 and 31-hour envelopes are presented for both sound speed and temperature, from the sea surface to the bottom; and the graphs showing the gradual changes of constant sound speed and isotherm depths. The sound speed and temperature structure is found to be relatively stable, as in the open ocean. Small, rapid variations abound in the thermocline region; a slight slow rise in deep isotherms occurs, but no tidal effects can be seen. The ship's motions at anchor are described: a composite of diurnal east-west and semidiurnal north-south oscillations. Results of a derivation of salinity from sound speed - temperature - depth data are shown to be in good agreement with published data. (Author).

Download or read book Tables of Sound Speed in Sea Water written by and published by . This book was released on 1962 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sound Speed in Seawater as a Function of Realistic Temperature salinity pressure Domain written by Ernest R Anderson and published by . This book was released on 1971 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: