12th Annual T. Francis Ogilvie Young Investigator Lecture, Professor Purnima Ratilal at 1:00pm Friday, October 20th

“As I write this, I am on the research vessel, Oceanus, on the Northern flank of Georges Bank with my colleagues, instantaneously imaging marine life over 100 km diameter area in the Gulf of Maine with OAWRS, ocean acoustic waveguide remote sensing. We have been observing the migration and spawning behavior of Atlantic herring over several diurnal periods, including massive movements on and off the bank to spawn. Findings from this experiment will be presented and discussed in the lecture.”                                    – Purnima Ratilal, October 2, 2006

Measurements made concurrently with conventional fish-finding sonar provide information on the depth distribution of herring in the water column. Resonance scattering from fish is observed in OAWRS imagery over multiple frequencies. OAWRS utilizes the property of the ocean as a waveguide to channel audible sound waves over long ranges to image objects at great distances from the sonar system. Sound propagation and 3D scattering were simulated with a parabolic equation method for range-dependent ocean environments to help design and guide the experiment on-the-fly to enhance imaging of marine life.

Purnima Ratilal received a B.Sc. in Physics from the National University of Singapore and a Ph.D. in Ocean Engineering from MIT. Before assuming her current position as assistant professor in the Department of Electrical and Computer Engineering at Northeastern University, Dr. Ratilal was a research engineer at DSO National Laboratories in Singapore from 1994 to 1998 and a postdoctoral associate at MIT in the Department of Ocean Engineering from 2002 to 2004. She received the ONR Postdoctoral Award in Ocean Acoustics in 2004. She was awarded the R. Bruce Lindsay Award for substantial contribution to the advancement of theoretical and applied acoustics in spring 2006. Her research interests include Underwater Acoustics, Acoustical Oceanography, Bioacoustics, Ultrasound Imaging, Nonlinear Scattering, Wave Propagation in Random Media, Signal, Image and Array Processing, and Statistical Inference Theory. Her research has been published in numerous journals, including Science, Journal of the Acoustical Society of America, and Journal of Computational Acoustics.