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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: [email protected]
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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 [email protected]
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 [email protected]
Measurements of seafloor scattering using synthetic
aperture sonar Dr. Derek R. Olson
Applied Research Laboratory
The Pennsylvania State University
Marine and Physical Acoustics Division
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
