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Eric Thorsos

Sr. Principal Physicist--Retiree

Affiliate Associate Professor, Electrical Engineering

Email

eit@apl.washington.edu

Phone

206-543-1369

Research Interests

Shallow Water Acoustic Propagation, Sediment Acoustics, Rough Surface Scattering

Biosketch

Dr. Thorsos research addresses high-frequency sound penetration into, propagation within, and scattering from the shallow-water seafloor. One finding is that high-frequency acoustic penetration into sediments at grazing angles below the critical angle is possible--an important issue in detection of buried mines.

Dr. Thorsos is also presently leading a project to improve our understanding of the effects of sea surface and bottom roughness on shallow water propagation, and to determine the best approaches to modeling this propagation. A specialist in numerical studies of scattering theory and on the validity of scattering theory approximations, Dr. Thorsos publishes in the Journal of the Acoustical Society of America and the IEEE Journal of Oceanic Engineering.

Department Affiliation

Acoustics

Education

B.S. Physics, Harvey Mudd College, 1965

M.S. Engineering & Applied Science, University of California, Davis-Livermore, 1966

Ph.D. Theoretical Nuclear Physics, MIT, 1972

Publications

2000-present and while at APL-UW

Macroscopic observations of diel fish movements around a shallow water artificial reef using a mid-frequency horizontal-looking sonar

Lee, W.-J., D. Tang, T.K. Stanton, and E.I. Thorsos, "Macroscopic observations of diel fish movements around a shallow water artificial reef using a mid-frequency horizontal-looking sonar," J. Acoust. Soc. Am., 144, 1424-1434, doi:10.1121/1.5054013, 2018.

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18 Sep 2018

The twilight feeding migration of fish around a shallow water artificial reef (a shipwreck) was observed by a horizontal-looking, mid-frequency sonar. The sonar operated at frequencies between 1.8 and 3.6 kHz and consisted of a co-located source and horizontal line array deployed at 4‚ÄČkm from the reef. The experiment was conducted in a well-mixed shallow water waveguide which is conducive to characterizing fish aggregations at these distances. Large aggregations of fish were repeatedly seen to emerge rapidly from the shipwreck at dusk, disperse into the surrounding area during the night, and quickly converge back to the shipwreck at dawn. This is a rare, macroscopic observation of an ecologically-important reef fish behavior, delivered at the level of aggregations, instead of individual fish tracks that have been documented previously. The significance of this observation on sonar performance associated with target detection in the presence of fish clutter is discussed based on analyses of echo intensity and statistics. Building on previous studies of long-range fish echoes, this study further substantiates the unique utility of such sonar systems as an ecosystem monitoring tool, and illustrates the importance of considering the impact of the presence of fish on sonar applications.

On sensing nitro-group containing compounds using thin planar arrays of titanium dioxide nanowires

Asher, W.E., P. Colosimo, E.I. Thorsos, and A. Yao, "On sensing nitro-group containing compounds using thin planar arrays of titanium dioxide nanowires," IEEE Sens. J., 18, 6927-6936, doi:10.1109/JSEN.2018.2855110, 2018.

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1 Sep 2018

Previous laboratory results have suggested that unheated TiO2 nanowire arrays provide a means to detect trace level concentrations of nitro-group containing compounds in the gas phase with fast response and high chemical selectivity. The detection method is based on the chemiresistive effect, where an electron-deficient compound adsorbed to the surface of an n-type semiconductor causes a surface charge deficit on the semiconductor leading to an increase in its resistance. However, a major issue with this method is that chemiresistive sensors based on TiO2 are also sensitive to the presence of water vapor, and this cross-sensitivity could lead to artifacts for sensors used under environmental conditions. Results are presented here, where thin planar arrays of TiO2 nanowires were tested to determine the sensitivity towards water vapor, along with the detection limits and response times towards several nitrocontaining organic molecules as a function of gas-phase water vapor concentration. When water vapor concentrations were carefully controlled to ensure they remain constant throughout the testing cycle, it was found that TiO2 nanowire devices could detect 2,4,6-trinitrotoluene at a concentration as low as a few tens of part per trillion by volume with a response time in the range of 102 – 103 s, depending on experimental conditions.

Noise background levels and noise event tracking/characterization under the Arctic ice pack: Experiment, data analysis, and modeling

Williams, K.L., M.L. Boyd, A.G. Soloway, E.I. Thorsos, S.G. Kargl, and R.I. Odom, "Noise background levels and noise event tracking/characterization under the Arctic ice pack: Experiment, data analysis, and modeling," IEEE J. Ocean. Eng., 43, 145-159, doi:10.1109/JOE.2017.2677748, 2018.

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1 Jan 2018

In March 2014, an Arctic Line Arrays System (ALAS) was deployed as part of an experiment in the Beaufort Sea (approximate location 72.323 N, 146.490 W). The water depth was greater than 3500 m. The background noise levels in the frequency range from 1 Hz to 25 kHz were measured. The goal was to have a three-dimensional sparse array that would allow determination of the direction of sound sources out to hundreds of kilometers and both direction and range of sound sources out to 1–2 km from the center of the array. ALAS started recording data at 02:12 on March 10, 2014 (UTC). It recorded data nearly continuously at a sample rate of 50 kHz until 11:04 on March 24, 2014. Background noise spectral levels are presented for low and high floe-drift conditions. Tracking/characterization results for ice-cracking events (with signatures typically in the 10–2000-Hz band), including the initiation of an open lead within about 400 m of the array, and one seismic event (with a signature in the 1–40-Hz band) are presented. Results from simple modeling indicate that the signature of a lead formation may be a combination of both previously hypothesized physics and enhanced emissions near the ice plate critical frequency (where the flexural wave speed equals that of the water sound speed). For the seismic event, the T-wave arrival time results indicate that a significant amount of energy coupled to T-wave energy somewhere along the path between the earthquake and ALAS.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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