Time-Exposure Acoustics for Imaging Underground Structures

Award Information
Agency: Department of Defense
Branch: Air Force
Contract: F49620-03-C-0111
Agency Tracking Number: F023-0090
Amount: $499,016.00
Phase: Phase II
Program: STTR
Awards Year: 2003
Solicitation Year: N/A
Solicitation Topic Code: N/A
Solicitation Number: N/A
Small Business Information
Geophex Ltd.
605 Mercury Street, Raleigh, NC, 27603
DUNS: 148040447
HUBZone Owned: N
Woman Owned: N
Socially and Economically Disadvantaged: N
Principal Investigator
 I.J. Won
 Geophysicist
 (919) 839-8515
 ijwon@geophex.com
Business Contact
 Steven Daib
Title: Contract Administrator
Phone: (919) 839-8515
Email: sdaib@geophex.com
Research Institution
 UNIV. OF OKLAHOMA
 Alan Witten
 School of Geophysics
Norman, OK, 73019
 (405) 325-1563
 Nonprofit college or university
Abstract
We propose to further develop a new technique for imaging underground facilities based on the passive monitoring of acoustic emissions from both stationary and moving equipment within such facilities. It is well known that all mechanical devices, such asmotors, gears, etc, emit acoustic signals. It is possible to identify an acoustic source based on its noise spectrum. During Phase I, we have demonstrated theoretically and experimentally the subject passive acoustic imaging method. Passive listening has been considered and employed in the past to detect underground structures based upon noise emitted from within. The fundamental difference in our approach is that we rigorously considered the inverse source problem subject only tothe assumption that the noise source is localized. Rather than using time delays across a sensor array to triangulate on the source, our method, known as time-exposure acoustics (TEA), coherently sums the data receiver over an array of sensors andback-propagates it into the host geologic formation. This procedure yields an image of the source that is similar to the image formation process used in reflection seismic exploration. The proposed technique can have military applications in locating and monitoring hidden and/or underground structures for targeting as well as commercial applications for locating people buried under collapsed structures that may be caused by caving,mudslide, and earthquakes.

* information listed above is at the time of submission.

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