Underwater Acoustics and Instrumentation Technical Group

Transcription

1 Underwater Acoustics and Instrumentation Technical Group Center for Acoustics and Vibration Amanda D. Hanford, PhD May 6, 2015

2 2 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

3 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) The ONR FIVE OCTAVE RESEARCH ARRAY (FORA) at Penn State 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, : Scattering Statistics Study, Seneca Lake OREX05, 2005, Oregon coast CTD Chain 3

4 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. 4

5 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: 5

6 Ocean Environment Characterization 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 Height (m) Distance (m) 6

7 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 Anand Swaminathan 1/2 Steven L. Garrett 1 Robert W. M. Smith 2 1: Graduate Program in Acoustics 2: Applied Research Laboratory The Pennsylvania State University State College, PA azs5363@psu.edu

8 Theory: Thermoacoustic Refrigerators Pulse Tube Crycoolers Image: M. Shiraishi et al., Cryocoolers 14, 277 (2007). Experiment: Unstable Stable Convectively Unstable : Stabilized : Convective flows transport heat - Shaking inhibits convective motion (Rayleigh-Bénard Instability) - Results in improved thermal isolation

9 Natural Gas Compressor-Station Noise Continuous recording at 6 locations for 2 weeks Variety of weather operating conditions Understand dominant sources Provide high-quality recordings for human-subject testing CS 289 in Lycoming County, PA [Tiadaghton State Forest] Selected measurement locations Typical spectral density T. B. Gabrielson tbg3@psu.edu 9

10 Measurements of seafloor scattering using synthetic aperture sonar Dr. Derek R. Olson Applied Research Laboratory The Pennsylvania State University Marine and Physical Acoustics Division Center for Acoustic Vibration 2015

11 Basic Research in Scattering Water ρ b c δ b p Seafloor ρ c c δ δ b b t p t

12 The scattering cross section characterizes the average scattered power Scattered pressure Cross section (average power over ensemble) σ = r2 p s 2 p i 2 A θ i Independent of measurement system

13 Why Scattering from Rocks? GEOMETRY REVERBERATION NORMALIZED REVERBERATION Detection! Only 4 existing measurements, none have environmental measurements 4

14 Experiments and Sites Google Maps 5

15 Glacial Abrasion 6

16 GlacialPlucking 7

17 NORGEX-13 Field Experiment Semi-portable aerial measurement system (SPAMS) 8

18 Glacially abraded roughness and power spectrum Z [mm]

19 Glacially plucked roughness and spectrum.

20 Acoustic measurement system: HISAS khz SAS system 3x3 cm resolution Designed and built by FFI / Kongsberg Thanks to Roy Hansen and Torstein Sæbo of FFI for data and processing 11

21 Synthetic Aperture Sonar Basics Figure courtesy of D. C. Brown (ARL/PSU)

22 Basic idea of SAS is to scale the array length with range. Pings from real array are combined to form synthetic array Real aperture ping locations

23 Until now, SAS images are only used to analyze texture and shape SAS images can also quantitatively measure seafloor backscattering Image courtesy of CMRE

24 Scattering strength measurements from glacially abraded surfaces and small-slope model comparisons Scattering model predictions using environmental inputs agree with measurements ρ~2700 kk/m 3 c p ~6400 m/s c s ~3200 m/s

25 Scattering strength from glacially plucked surfaces σ = μ sin 2 θ i Lambert s law is empirical and has no basis in physics

26 Future model development will be based on these measurements