Classification of Uxo by Principal Dipole Polarizability
Abstract
Data acquired by multiple-Transmitter, multiple-receiver time-domain electromagnetic devices show great potential for determining the geometric and compositional information relating to near surface conductive targets. Here is presented an analysis of data from one such system; the Berkeley Unexploded-ordnance Discriminator (BUD) system. BUD data are succinctly reduced by processing the multi-static data matrices to obtain magnetic dipole polarizability matrices for data from each time gate. When viewed over all time gates, the projections of the data onto the principal polar axes yield so-called polarizability curves. These curves are especially well suited to discriminating between subsurface conductivity anomalies which correspond to objects of rotational symmetry and irregularly shaped objects. The curves have previously been successfully employed as library elements in a pattern recognition scheme aimed at discriminating harmless scrap metal from dangerous intact unexploded ordnance. However, previous polarizability-curve matching methods have only been applied at field sites which are known a priori to be contaminated by a single type of ordnance, and furthermore, the particular ordnance present in the subsurface was known to be large. Thus signal amplitude was a key element in the discrimination process. The work presented here applies feature-based pattern classification techniques to BUD field data where more than 20 categories of object are present. Data soundings from a calibration grid at the Yuma, AZ proving ground are used in a cross validation study to calibrate the pattern recognition method. The resultant method is then applied to a Blind Test Grid. Results indicate that when lone UXO are present and SNR is reasonably high, Polarizability Curve Matching successfully discriminates UXO from scrap metal when a broad range of objects are present.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMNS23A1460K
- Keywords:
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- 0684 ELECTROMAGNETICS / Transient and time domain;
- 0694 ELECTROMAGNETICS / Instruments and techniques;
- 0933 EXPLORATION GEOPHYSICS / Remote sensing;
- 3235 MATHEMATICAL GEOPHYSICS / Persistence;
- memory;
- correlations;
- clustering