Underwater Acoustics and Instrumentation Technical Group

Center for Acoustics and Vibration

Amanda D. Hanford, PhD May 6, 2015

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Research Areas/Core Competencies

• Ocean Acoustics – Seafloor characterization – Water column characterization – Acoustic modeling and simulation – Underwater threat neutralization – Weapon Countermeasures – Ocean array experiments – Radiated/self noise

• Marine Bioacoustics – Marine mammal/fish studies ONR, Woods

Hole Oceanographic Institution, Joint Industry Program on the Effects of Industry Sounds on Marine Animals, Int’l Oil and Gas

• Physical Acoustics – Atmospheric infrasonic monitoring arrays – Thermoacoustics

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Ocean Acoustics at-Sea Experiments International

• Seafloor Complexity, 2011, Larvik, Norway • AMiCa-10 Autonomous Mine Clearance, 2010, Italy

(student: Dan Brown) • Clutter09, active sonar 2009, Italy • QPE Geoacoustic Uncertainty, 2009, Taiwan • TAVEX, 2008, Korea (student: Chad Smith) • Clutter07, reverberation mechanisms, 2007, Italy • Philippine SeaTest 2009 (students: C. Jemmott, Alex Sell) • Boundary’04, seabed int,2004, Italy (student: Tom Weber)

National • Gulf-Ex12, active sonar reverberation, Panama City • NSCW ex, statistics of synthetic aperture sonar, 2011

(student: Dan Brown) • Long Range Acoustic Comms Sept 2010, Off San Diego • SW06, 2006, New Jersey Shelf (students: Megan Ballard,

Joy Lyons, John Camin, Tom Weber) • Gulf of Maine, Georges Bank, mapping fish schools, 2006 • 2006: Scattering Statistics Study, Seneca Lake • OREX05, 2005, Oregon coast

The ONR FIVE OCTAVE RESEARCH ARRAY (FORA) at Penn State

CTD Chain

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Center for Marine Science and Technology (C-MaST)

• Purpose: – To coordinate and promote diverse activities in the area of

marine science and technology across campus

• Goals: – Promote interdisciplinary research and training grants – Host a regular seminar series to bring together students,

faculty, postdocs and staff around C-MaST topics – Administer the Marine Science Minor – Represent the University in the Consortium for Ocean

Leadership (COL) – Publicize C-MaST activities at Penn State through freshman

recruiting, the Marine Science Society, graduate student recruiting, public seminars, community outreach activities, and maintenance of a website.

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Center for Marine Science and Technology (C-MaST)

• Housed within PSIEE (Penn State Institutes of Energy and the Environment)

• Acting Director – Jennifer Miksis-Olds (ARL)

• Advisory Board – David Bradley (ARL) – Chuck Fisher (Department of Biology) – Lee Kump (Geosciences)

J. Miksis-Olds: jlm91@arl.psu.edu

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Ocean Environment Characterization

Distance (m)

Height (m)

Synthetic Aperture SONAR Forward Modeling and Inversion

2D to 3D Synthetic Aperture Sonar Knowledge of how scattering strength varies as a function of angle allows one to go from a Synthetic Aperture SONAR intensity image to a seafloor height map

Anand Swaminathan1/2

Steven L. Garrett1 Robert W. M. Smith2

1: Graduate Program in Acoustics

2: Applied Research Laboratory

The Pennsylvania State University State College, PA azs5363@psu.edu

Experimental Investigation of Dynamic Stabilization of the Rayleigh-Bénard Instability by Acceleration Modulation

Acknowledgments: Applied Research Laboratory Walker Graduate Assistantship U.S. Department of Energy/ARPA-E

Thermoacoustic Refrigerators Pulse Tube Crycoolers

Theory:

Experiment:

Convectively Unstable : Convective flows transport heat (Rayleigh-Bénard Instability)

Stabilized : - Shaking inhibits convective motion - Results in improved thermal

isolation

Image: M. Shiraishi et al., Cryocoolers 14, 277 (2007).

Unstable Stable

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CS 289 in Lycoming County, PA [Tiadaghton State Forest]

• Continuous recording at 6 locations for 2 weeks

• Variety of weather operating conditions

• Understand dominant sources

• Provide high-quality recordings for human-subject testing

Selected measurement

locations

Typical spectral density

Natural Gas Compressor-Station Noise

T. B. Gabrielson tbg3@psu.edu

Measurements of seafloor scattering using synthetic

aperture sonar Dr. Derek R. Olson

Applied Research Laboratory

The Pennsylvania State University

Marine and Physical Acoustics Division

dro131@psu.edu

814-863-9895

Center for Acoustic Vibration 2015

Basic Research in Scattering

Water

tptbb cc δδρ

pbbc δρ

Seafloor

The scattering cross section characterizes the average scattered power

Scattered pressure

Cross section (average power over ensemble)

𝜃𝑖

𝜎 =𝑟2 𝑝𝑠 2

𝑝𝑖 2𝐴

Independent of measurement system

GEOMETRY

REVERBERATION

Why Scattering from Rocks?

Detection! NORMALIZED REVERBERATION

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Only 4 existing measurements, none have environmental measurements

Experiments and Sites

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© Google Maps

Glacial Abrasion

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GlacialPlucking

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NORGEX-13 Field Experiment

Semi-portable aerial measurement system (SPAMS)

Z [m

m]

Glacially abraded roughness and power spectrum

Glacially plucked roughness and spectrum.

Acoustic measurement system: HISAS 1030 •100 kHz SAS system •3x3 cm resolution •Designed and built by FFI / Kongsberg

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Thanks to Roy Hansen and Torstein Sæbo of

FFI for data and processing

Synthetic Aperture Sonar Basics

Figure courtesy of D. C. Brown (ARL/PSU)

Basic idea of SAS is to scale the array length with range.

Pings from real array are combined to form synthetic array

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Real aperture ping locations

Until now, SAS images are only used to analyze texture and shape

Image courtesy of CMRE

SAS images can also quantitatively measure seafloor backscattering

Scattering strength measurements from glacially abraded surfaces and small-slope model comparisons

Scattering model predictions using environmental inputs agree with measurements

𝑐𝑝~6400 𝑚/𝑠 𝜌~2700 𝑘𝑘/𝑚3 𝑐𝑠~3200 𝑚/𝑠

Scattering strength from glacially plucked surfaces

𝜎 = 𝜇 sin2 𝜃𝑖 Lambert’s law is empirical and has no basis in physics

Future model development will be based on these measurements