Rapid Calculation of EMI Responses of Metallic Objects and Implementation in Inversion Schemes
Abstract
Broadband electromagnetic induction (EMI, 10's of Hz to ^ 100's of kHz) is emerging as one of the most promising technologies for discriminating subsurface unexploded ordnance (UXO) from widespread clutter. We have succeeded in performing detailed numerical simulations of EMI responses by a considerable variety of representative objects and UXO. Nonetheless, signal inversion schemes are impeded by a lack of rapid means for calculating the responses of possible target types in a great variety of depths and dispositions relative to the sensor. In this project we have developed a reduced source set (RSS) formulation of target response, which is essentially a modified and simplified method of auxiliary sources. In the RSS approach we express the same target response as would be obtained by a full-fledged, detailed, first- principles numerical solution but using only a small number of equivalent responding entities (e.g. charges, currents, surface field components, etc. We have shown that as long as the observer is at distance that is at least some significant fraction of the smallest dimension of an object of interest, the complete and the RSS responses are essentially indistinguishable.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2003
- Accession Number
- ADA425274
Entities
People
- Keith D. Paulsen
Organizations
- Dartmouth College