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David Dall'Osto

Senior Research Scientist/Engineer

Email

dallosto@apl.washington.edu

Phone

206-221-5085

Department Affiliation

Acoustics

Education

B.S. Mechanical Engineering, Vanderbilt University, 2006

M.S. Mechanical Engineering, University of Washington, 2009

Ph.D. Mechanical Engineering, University of Washington, 2013

Publications

2000-present and while at APL-UW

Source triangulation utilizing three-dimensional arrivals: Application to the search for the ARA San Juan submarine

Dall'Osto, D.R., "Source triangulation utilizing three-dimensional arrivals: Application to the search for the ARA San Juan submarine," J. Acoust. Soc. Am., 146, 2104-2112, doi:10.1121/1.5125251, 2019.

More Info

1 Sep 2019

On Nov. 15, 2017, an intense acoustic event coincident with the disappearance of the Argentine navy submarine, ARA (Armada Argentina) San Juan, was recorded on the hydroacoustic network established to enforce compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Analysis by Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) scientists, based on two hydroacoustic and one seismic detection, provided a likely origin within an error ellipse of 19 km by 12 km; analysis based solely on the main arrival detected at the two hydroacoustic stations gave an error ellipse of ~500 km by ~25 km [Nielsen, Zampolli, Le Bras, Mialle, Bittner, Poplavskiy, Rozhkov, Haralabus, Tomuta, Bell, and Grenard, in European Geosciences Union General Assembly, Vol. 20, EGU2018-18559 (2018)]. The large major axis depends on uncertainty in establishing the event time, while the minor axis depends on precision in the ocean state estimate used to model propagation speed. This paper demonstrates how three-dimensional (3-D) propagation features can also be used in source triangulation, in particular when no seismic detection is available. A mode-based 3-D propagation model is implemented to reconstruct the propagation path of a 3-D arrival bathymetrically refracted from the continental slope. This additional arrival provides a third (virtual) station to decouple the location and time of the event and triangulate the event. This improvement is commensurate with the CTBTO analysis, but does not rely on the additional seismic station detection.

Vector acoustic analysis of time-separated modal arrivals from explosive sound sources during the 2017 Seabed Characterization Experiment

Dahl, P.H., and D.R. Dall'Osto, "Vector acoustic analysis of time-separated modal arrivals from explosive sound sources during the 2017 Seabed Characterization Experiment," IEEE J. Ocean. Eng., EOR, doi:10.1109/JOE.2019.2902500, 2019.

More Info

26 Mar 2019

The Intensity Vector Autonomous Recorder (IVAR) is a system that records four coherent channels of acoustic data continuously: one channel for acoustic pressure and three channels associated with a triaxial accelerometer from which acoustic particle velocity is obtained. IVAR recorded the vector acoustic field in broadband signals originating from Signal, Underwater Sound (SUS) (Mk-64) charges deployed at 5–13-km range from the fixed IVAR site (mean depth 74.4 m) as part of the 2017 Seabed Characterization Experiment (SBCEX) designed to study the acoustics of fine-grained muddy sediments. Sufficient geometric dispersion at these ranges permitted unambiguous identification of up to four modes as a function of frequency for frequencies less than 80 Hz. From time–frequency analysis of the dispersed arrivals, a single mode (n) and single-frequency (fi) properties are identified at peaks in the narrowband scalar field, with time dependence corresponding to mode group speed. At these time–frequency addresses, four quantities derived from the vector acoustic measurements are formed by coherent combination of pressure and velocity channels: first, modal phase speed; second, circularity, a measure of the normalized curl of active intensity; third, depth-dependent mode speed of energy; and fourth, vertical component of reactive intensity normalized by scalar intensity. A means to compute these quantities theoretically is provided, and a comparison of model results based on a notional geoacoustic representation for the SBCEX experimental area consisting of a single low-speed mud layer over a half-space area versus a Pekeris representation based on the same half-space shows a striking difference, with the field observations also clearly at variance with the Pekeris representation. A fundamental property of mode 2, observed at the IVAR location, is a change in sign for circularity and vertical reactive intensity near 37 Hz that is posited as a constraint observation for mode 2 that must be exhibited by any geoacoustic model that includes a low-speed mudlike layer applied to this location.

Observations of water column and bathymetric effects on the incident acoustic field associated with shallow-water reverberation experiments

Dall'Osto, D.R., and P.H. Dahl, "Observations of water column and bathymetric effects on the incident acoustic field associated with shallow-water reverberation experiments," IEEE J. Ocean. Eng., 42, 1146-1161, doi:10.1109/JOE.2017.2717661, 2017.

More Info

1 Oct 2017

As a part of the 2013 Targets and Reverberation Experiment (TREX13), measurements of the acoustic field generated by a source used in midfrequency (1.8–3.6 kHz) reverberation experiments are studied at 5 and 6 km range. The TREX13 reverberation sources were placed off the coast of Panama City, FL, USA, in waters ~20 m deep, and data discussed here are from a 2-h period in the late afternoon on April 28, 2013. The observed coda of the source signal is partitioned into an initial primary arrival, and a distinct second arrival delayed by roughly 2 s. Characteristics of the two arrivals are studied in terms of the effective number of modes, interference features, and the direction of acoustic intensity, which was directly measured by a vector sensor located at 5 km range. A shift in frequency within the primary arrival is observed over the 2-h measurement period. Frequency shifts are related to a change in range of dislocations, defined as points of complete destructive interference in the acoustic field, that modulate with tidal variation in the sound-speed profile. Precise frequencies are identified with the vector property called circularity, a nondimensional measure of acoustic intensity curl, that is maximal within the vortex-like intensity field within a dislocation. Using the waveguide invariant β, the frequency shift is used to estimate the tidal change in the thermocline depth. These interference features are absent in the second arrival, which is postulated to be an acoustic path horizontally refracted by the gently sloping bathymetry (~0.4°) forming the coastal environment. A description of the refraction using modal rays is developed, and the transition of the mode from being trapped to leaky is handled as a transition to a virtual mode near the cutoff depth. Models of the primary and refracted arrivals are presented to support the conclusions.

More Publications

Inventions

Automatic Implementation of NOAA Marine Mammal Guidelines

Record of Invention Number: 48478

Peter Dahl, David Dall'Osto

Disclosure

13 Nov 2018

Airborne Acoustic Particle Motion Sound Meter

Record of Invention Number: 48135

David Dall'Osto, Peter Dahl

Disclosure

1 Aug 2017

Underwater Sound Level Meter

Record of Invention Number: 46351

David Dall'Osto, Per Reinhall, Tim Wen, Peter Dahl

Disclosure

8 Jan 2013

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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