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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

Acoustic resonances within the surfical layer of a muddy seabed

Dall'Osto, D.R., and D. Tang, "Acoustic resonances within the surfical layer of a muddy seabed," J. Acoust. Soc. Am., 151, 3473-3480, doi:10.1121/10.0011472, 2022.

More Info

1 May 2022

This is an investigation of sound propagation over a muddy seabed at low grazing angles. Data were collected during the 2017 Seabed and Bottom Characterization Experiment, conducted on the New England Mud Patch, a 500 km2 area of the U.S. Eastern Continental Shelf characterized by a thick layer of muddy sediments. Sound Underwater Signals (SUS), model Mk64, were deployed at ranges of 1–15 km from a hydrophone positioned 1 m above the seafloor. SUS at the closest ranges provide measurements of the bottom reflection at low grazing angles (< 3 deg). Broadband analysis from 10 Hz to 10 kHz reveals resonances in the bottom reflected signals. Comparison of the measurements to simulated signals suggest a surficial layer of mud with a sound speed lower than the underlying mud and overlying water. The low sound speed property at the water–mud interface, which persists for less than 1 m, establishes a sound duct that impacts mid-frequency sound propagation at low grazing angles. The presence of a low-speed surficial layer of mud could be universal to muddy seabeds and, hence, has strong implications for mid-frequency sound propagation wherever mud is present.

Polarization of ocean acoustic normal modes

Bonnel, J., J. Flamant, D.R. Dall'Osto, N. Le Bihan, and P.H. Dahl, "Polarization of ocean acoustic normal modes," J. Acoust. Soc. Amer., 150, 1897-1911, doi:10.1121/10.0006108, 2021.

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1 Sep 2021

In ocean acoustics, shallow water propagation is conveniently described using normal mode propagation. This article proposes a framework to describe the polarization of normal modes, as measured using a particle velocity sensor in the water column. To do so, the article introduces the Stokes parameters, a set of four real-valued quantities widely used to describe polarization properties in wave physics, notably for light. Stokes parameters of acoustic normal modes are theoretically derived, and a signal processing framework to estimate them is introduced. The concept of the polarization spectrogram, which enables the visualization of the Stokes parameters using data from a single vector sensor, is also introduced. The whole framework is illustrated on simulated data as well as on experimental data collected during the 2017 Seabed Characterization Experiment. By introducing the Stokes framework used in many other fields, the article opens the door to a large set of methods developed and used in other contexts but largely ignored in ocean acoustics.

Range-dependent inversion for seabed parameters using vector acoustic measurements of underwater ship noise

Dahl, P.H., and D.R. Dall'Osto, "Range-dependent inversion for seabed parameters using vector acoustic measurements of underwater ship noise," IEEE J. Ocean. Eng., EOR, doi:10.1109/JOE.2021.3086880, 2021.

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20 Jul 2021

The Intensity Vector Autonomous Recorder (IVAR) measures acoustic particle velocity and pressure simultaneously. IVAR was deployed on the seabed during the 2017 Seabed Characterization Experiment (SBCEX) with the primary objective to study sound propagation within underwater waveguides for which the seabed consists of fine-grained, muddy sediments. In this study, a Bayesian framework is applied to underwater noise recorded by IVAR from a cargo ship traversing the central region of the SBCEX2017 area for the purpose of inversion to characterize sediment properties. The vector acoustic data are in the form of a bounded, nondimensional form known as circularity, a quantity that is independent of the ship noise-source spectrum and that can be interpreted as the normalized curl of active intensity. The inversion model space for the seabed consists of a low-compressional speed layer and underlying basement half-space, with each having compressional and shear components. The interpretative model for producing a replica of the data is based on the plane wave reflection coefficient for a layered, elastic seabed in conjunction with the depth-dependent Green’s function that is integrated in the complex wave number plane to obtain pressure and particle velocity fields. The small change in water depth between the location of the ship source and IVAR is addressed using adiabatic mode theory. The inversion results exhibit slow variation over the 20-min observation period, representing approximately 5 km of travel by the ship source.

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Inventions

+AIRVS

Record of Invention Number: 49582

David Dall'Osto

Disclosure

29 Jun 2022

Acoustic Intensity Sensor Using MEMS Triaxial Accelerometer and MEMS Microphone

Record of Invention Number: 48987

David Dall'Osto, Peter Dahl

Disclosure

30 Jun 2020

Automatic Implementation of NOAA Marine Mammal Guidelines

Record of Invention Number: 48478

Peter Dahl, David Dall'Osto

Disclosure

13 Nov 2018

More Inventions

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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