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Identification of metallic objects using spectral magnetic polarizability tensor signatures: Object classification

Ben Wilson, Paul D. Ledger Orcid Logo, William R. B. Lionheart Orcid Logo

International Journal for Numerical Methods in Engineering, Volume: 123, Issue: 9, Pages: 2076 - 2111

Swansea University Author: Ben Wilson

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DOI (Published version): 10.1002/nme.6927

Abstract

The early detection of terrorist threat objects, such as guns and knives, through improved metal detection, has the potential to reduce the number of attacks and improve public safety and security. To achieve this, there is considerable potential to use the fields applied and measured by a metal det...

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Published in: International Journal for Numerical Methods in Engineering
ISSN: 0029-5981 1097-0207
Published: Wiley 2022
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa59248
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Abstract: The early detection of terrorist threat objects, such as guns and knives, through improved metal detection, has the potential to reduce the number of attacks and improve public safety and security. To achieve this, there is considerable potential to use the fields applied and measured by a metal detector to discriminate between different shapes and different metals since, hidden within the field perturbation, is object characterization information. The magnetic polarizability tensor (MPT) offers an economical characterization of metallic objects and its spectral signature provides additional object characterization information. The MPT spectral signature can be determined from measurements of the induced voltage over a range of frequencies in a metal signature for a hidden object. With classification in mind, it can also be computed in advance for different threat and non-threat objects. In this article, we evaluate the performance of probabilistic and non-probabilistic machine learning algorithms, trained using a dictionary of computed MPT spectral signatures, to classify objects for metal detection. We discuss the importance of using appropriate features and selecting an appropriate algorithm depending on the classification problem being solved, and we present numerical results for a range of practically motivated metal detection classification problems.
Keywords: Finite element method; Magnetic polarizability tensor; Machine learning; Metal detection; Object classification; Reduced order model; Spectral; Validation
College: Faculty of Science and Engineering
Funders: Engineering and Physical Sciences Research Council. Grant Numbers: EP/R002134/2, EP/R002177/1, EP/V009028/1, EP/V009109/1, EP/V049453/1, EP/V049496/1 ; Royal Society
Issue: 9
Start Page: 2076
End Page: 2111