| Understanding Predictability of the Ocean |
30 Sep 2011 |
12 pages |
| Authors:
Brian Powell; HAWAII UNIV HONOLULU (MANOA CAMPUS) DEPT OF OCEANOGRAPHY
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 | The long-term scientific goals of this research are as follows: (1) to develop an understanding of how some observations affect ocean predictability, (2) to further develop the state-of-the-art ROMS 4D-Var by extending the observational types and applications, (3) to gain experience and develop ideas regarding limitations to the predictability of oceanic processes, and (4) to train a new generation of students in data assimilation and ROMS. The primary objectives of ... |
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| Photoacoustic Imaging of Epilepsy |
Apr 2011 |
48 pages |
| Authors:
Huabei Jiang; FLORIDA UNIV GAINESVILLE
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| This research is aimed at developing a new imaging approach, called Photoacoustic tomography (PAT) , for non-invasively tracking dynamical changes during seizure occurrence. The project will develop imaging hardware and software, and conduct phantom/in vivo experiments to achieve the proposed goals. During the second year of this project, we have completed the construction of the proposed array based PAT system, and calibrated and tested the system using extensive phantom experiments. ... |
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| Portable Ultrasound Imaging of the Brain for Use in Forward Battlefield Areas |
MAR 2011 |
17 pages |
| Authors:
Gregory Clement; ULTRADIAGNOSTICS INC ATTLEBORO FALLS MA
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| The overall goal of this project has been to develop (i) an ultrasound-based detection system designed to detect foreign bodies in the brain and (ii) a portable ultrasound-based imaging system capable of producing full brain images through the intact skull. This year, based on preliminary designs and testing in Years I and II of the project, a final design and reconstruction approach has been established. Key findings and considerations leading ... |
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| Quantitative Side-Scan Sonar Research for Sediment Characterization and Development of Multibeam Subbottom Profiler |
Jul-2009 |
14 pages |
| Authors:
Jerald W Caruthers; UNIVERSITY OF SOUTHERN MISSISSIPPI STENNIS SPACE CENTER CENTER FOR MARINE SCIENCE
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| This report discusses research on seafloor backscatter at high frequencies in the range of a few hundred kilohertz using a specially modified side-scan sonar producing high-fidelity, high spatial- and bit-revolutions, quantitative acoustic-waveform data. A part of the work under N00014-03-1-0318 supported PI's effort in constructing the Multibeam Subbottom Profile under N00014-05-1-0750. |
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| Acoustic Scattering in Deep Ocean Waveguides due to Small Scale Ocean Structure |
30 Sep 2007 |
7 pages |
| Authors:
Michael Wolfson; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
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| The long-term goal is to contribute to the understanding of long-range propagation of acoustic pulses in deep ocean environments. Emphasis is placed on broadband pulses centered at around 100 Hertz in oceans that have a well defined acoustic waveguide. This effort directly compliments the Long-range Ocean Acoustic Propagation Experiment (LOAPEX) that was performed in the fall of 2004. A primary objective is to test the hypothesis that an stochastic environmental ... |
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| Tomographic Reconstruction of Atmospheric Turbulence with the Use of Time-Dependent Stochastic Inversion |
01-Sep-2007 |
11 pages |
| Authors:
Sergey N Vecherin; Vladimir E Ostashev; A Ziemann; D K Wilson; K Arnold; M Barth; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Acoustic travel-time tomography allows one to reconstruct temperature and wind velocity fields in the atmosphere. In a recently published paper [S. Vecherin et al., J. Acoust. Soc. Am. 119, 2579 (2006)], a time-dependent stochastic inversion TDSI was developed for the reconstruction of these fields from travel times of sound propagation between sources and receivers in a tomography array. TDSI accounts for the correlation of temperature and wind velocity fluctuations both ... |
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| Time-Dependent Stochastic Inversion in Acoustic Travel-Time Tomography of the Atmosphere |
MAY 2006 |
11 pages |
| Authors:
Sergey N. Vecherin; Vladimir E. Ostashev; George H. Goedecke; D. K. Wilson; Alexander G. Voronovich; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Stochastic inversion is a well known technique for the solution of inverse problems in tomography. It employs the idea that the propagation medium may be represented as random with a known spatial covariance function. In this paper, a generalization of the stochastic inverse for acoustic travel-time tomography of the atmosphere is developed. The atmospheric inhomogeneities are considered to be random, not only in space but also in time. This allows ... |
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| High Resolution Modeling of the Gulf of Mexico |
JUL 2005 |
4 pages |
| Authors:
Patrick J. Hogan; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| An advanced, high-resolution numerical ocean model is employed to investigate the dynamics and physical characteristics of the deep and shallow circulation in the Gulf of Mexico. The resolution of the ocean model (approx. 4 kilometers) and revolutionary hybrid (quasi-isopycnic) vertical coordinate makes it an excellent candidate to form the ocean model core of an ocean acoustic tomography program that can provide near real-time subsurface ocean data to augment satellite data ... |
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| Scanning Microwave Induced Acoustic Tomography |
OCT 2003 |
79 pages |
| Authors:
Lihong Wang; TEXAS ENGINEERING EXPERIMENT STATION COLLEGE STATION
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| Since the previous report in 2002, we have published five peer- reviewed journal articles and delivered 12 invited talks. For the invited plenary talk given at UK, all travel related expenses were covered by the conference host. The combination of ultrasound and microwave has provided us a unique opportunity for early-cancer imaging with high resolution and high contrast. A good imaging modality should have both high contrast and high spatial ... |
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| Marine Mammal Sound Archive |
15 AUG 2003 |
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| Authors:
William A. Watkins; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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 | The marine mammal sound work supported by the last component of this Grant included work on monitoring calls produced by deep water whales of the North Pacific, as well as organization of a digital archive of the WHOI marine animal sound collections. The program of monitoring the calling whales across the North Pacific using U.S. Navy SOSUS and other systems has continued to be productive, with regular measures of the ... |
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| Scanning Microwave Induced Acoustic Tomography |
OCT 2001 |
30 pages |
| Authors:
Lihong Wang; TEXAS ENGINEERING EXPERIMENT STATION COLLEGE STATION
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| Since the grant was awarded in October 2000, we have published three peer-reviewed journal articles, published one conference proceedings article, delivered 16 invited talks, and graduated one M.S. student. This research has been successful and rewarding. We are well prepared to continue the project with greater successes. Until cancer is eradicated by preventative measures, the grand challenge in cancer research is early-cancer detection because the cure rate of cancers is ... |
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| Sound Propagation Through Anisotropic, Inhomogeneous and Intermittent Turbulence |
AUG 2001 |
10 pages |
| Authors:
V. E. Ostashev; G. H. Goedecke; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Three-dimensional models of anisotropic and inhomogeneous spectra of temperature and wind velocity fluctuations in unstable atmospheric boundary layers have been developed, modified or extended. Furthermore, theories of sound propagation through anisotropic, inhomogeneous, and intermittent atmospheric turbulence have been developed. These theories allow consideration of different geometries of sound propagation: line-of-sight sound propagation, interference of the direct and ground reflected waves, sound scattering into a refractive shadow zone, and waveguide sound ... |
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| Data Assimilation for Ocean Acoustic Tomography |
JUL 2000 |
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| Authors:
Chris G. Walter; UNIV OF WASHINGTON SEATTLE APPLIED PHYSICS LAB
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| This research evaluates the effectiveness of assimilating ocean acoustic tomography data into numerical ocean models. Acoustic tomography uses sound to remotely sample integrated or averaged properties of the ocean. These properties include sound speed and current velocity. Three different models are used in the assimilation: 1) a linear Rossby wave model without advection, 2) a Rossby wave model with advection, and 3) a non-linear quasi-geostrophic ... |
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| Broadband Modal Coherence and Beamforming at Megameter Ranges |
FEB 2000 |
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| Authors:
Kathleen E. Wage; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| Normal modes, the eigenfunctions of the ocean waveguide, are useful in underwater acoustics because the lowest modes provide an efficient description of the most energetic signals at long ranges. Understanding the structure of the mode arrivals at megameter ranges is crucial to tomographic and matched field processing applications, but there have been few opportunities for experimental observation of these signals. First, this thesis develops a short- ... |
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| A New Scheme for Acoustical Tomography of the Ocean |
30 Sep 1998 |
4 pages |
| Authors:
Alexander G Voronovich; E C Shang; NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION BOULDER CO ENVIRONMENTAL TECHNOLOGY LAB
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| The long-term purpose is to develop a new scheme of the acoustical tomography of the ocean of meso- to global scales which is based on measurements of horizontal-refraction angle (HRA) related to different acoustic modes rather than travel time along different rays. The objectives are to develop robust inversion scheme for retrieving 3-D ocean inner structure based on measurements of HRA. In spite of its small value HRA angle can ... |
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| Matched Field Tomographic Inversion for Geoacoustic Properties |
30 Sep 1998 |
4 pages |
| Authors:
N R Chapman; VICTORIA UNIV (BRITISH COLUMBIA) SCHOOL OF EARTH AND OCEAN SCIENCES
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| The geoacoustic properties of the ocean bottom, including sound speed profiles, densities, attenuations and sediment layer depths, have a significant effect on sound propagation in shallow water. The long term goal of this work is to develop a new tomographic inversion method based on matched field processing of broadband data for estimating geoacoustic properties. Matched field tomographic inversion is a relatively new approach (Tolstoy, 94) that is specifically designed for ... |
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| Investigation of Parametric Acoustic Response of a Fluctuating Ocean |
Jan 1998 |
3 pages |
| Authors:
Steven Tomsovic; WASHINGTON STATE UNIV PULLMAN DEPT OF PHYSICS
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| The long-term goals are: (1) to take advantage of the ever-changing ocean environment's effects in order to provide a more complete understanding of long-range acoustic pulse propagation including extracting parameters characterizing the ocean environment, for example, by linking them to range scales of temporal decorrelations in arriving signals, (2) understanding the extent of fundamental limitations on ray-based acoustic tomography; of particular interest is the breakdown range of semiclassical methods, and ... |
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| Shelfbreak PRIMER Data Analysis: Acoustic Propagation and Ocean Tomography |
Jan 1998 |
6 pages |
| Authors:
Ching-Sang Chiu; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
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| The long-term goals of this research are as follows: (1) the characterization of meso to internal-wave-scale oceanographic processes that influence broadband sound transmissions in a coastal environment -- central to the characterization are the formulation of accurate forward relations and the quantification of the sensitivities and variability of the various observable acoustic quantities to environmental differences and changes; and (2) the development and improvement of high-resolution tomographic inverse techniques for ... |
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| Acoustic Monitoring of Flow Through the Strait of Gibraltar: Data Analysis and Interpretation |
Jan 1998 |
5 pages |
| Authors:
Peter F Worcester; Bruce D Cornuelle; CALIFORNIA UNIV REGENTS LA JOLLA CA SCRIPPS INST OF OCEANOGRAPHY
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| Existing techniques do not begin to exploit the full potential of acoustic remote sensing methods to study ocean thermal structure and circulation. This research is intended to improve our understanding of acoustic propagation in shallow-to-intermediate depth environments and to extend tomographic techniques to ocean regimes in which acoustic propagation is more complex than the largely deep water cases studied to date. Understanding the acoustic forward problem in complicated environments is ... |
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| The Temperature and Depth Accuracy of Sippican T-5 XBTs |
01 FEB 1993 |
11 pages |
| Authors:
Janice D. Boyd; Robert S. Linzell; NAVAL OCEANOGRAPHIC AND ATMOSPHERIC RESEARCH LAB STENNIS SPACE CENTER MS
|
| Thirty-four near-simultaneous pairs of CTD and Sippican model T-5 XBT profiles were obtained during an experiment in the Sargasso Sea during the summer of 1991. The data were analyzed to assess the temperature and fall-rate accuracies of the T-5 probes. The XBT temperatures averaged 0.07 deg C warmer than CTD temperatures, with some suggestion that the offset might be different for different acquisition systems and that it might be slightly ... |
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| Smoothly Modulated Frequency-Bounded Impulse Signals for Tomography |
JUN 91 |
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| Authors:
Timothy F. Duda; James F. Lynch; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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| A group of amplitude and frequency modulated signals which generate narrow synthesized pulses and which also have smoothly varying phase are described. The frequency-sweep (chirp) signals have exactly-defined frequency content and differentiable phase. These signals can be used with efficient resonant transducers, if the resonant frequency is adjustable, and they have adequate Doppler response for use with drifting apparatus. |
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ACOUSTIC TOMOGRAPHY
