UXO detection and identification based on intrinsic target polarizabilities — A case history

Abstract

Electromagnetic induction data parameterized in time dependent object intrinsic polarizabilities allow discrimination of unexploded ordnance (UXO) from false targets (scrap metal). Data from a cart-mounted system designed for discrimination of UXO with 20 mm to 155 mm diameters are used. Discrimination of UXO from irregular scrap metal is based on the principal dipole polarizabilities of a target. A near-intact UXO displays a single major polarizability coincident with the long axis of the object and two equal smaller transverse polarizabilities, whereas metal scraps have distinct polarizability signatures that rarely mimic those of elongated symmetric bodies. Based on a training data set of known 1 targets, object identification was made by estimating the probability that an object is a single UXO. Our test survey took place on a military base where both 4.2" mortar shells and scrap metal were present. The results show that we detected and discriminated correctly all 4.2" mortars, and in that process we added 7%, and 17%, respectively, of dry holes (digging scrap) to the total number of excavations in two different survey modes. We also demonstrated a mode of operation that might be more cost effective than the current practice.

A Complex Approach to UXO Discrimination: Combining Advanced EMI Forward Models and Statistical Signal Processing

“…We note that Q has dimensions of volume, which makes it comparable to the polarizability tensor elements of the point dipole model [6][7][8][9][10][11][12][13].…”

Demonstration of the Berkeley UXO Discrimination at Live Sites

“…113 objects were from San Luis Obispo, and 199 from our previous library. The approach in this study was similar to the one applied to the former Camp Sibert data (Gasperikova et al, 2009). However, in this survey, the level of difficulty was increased by presence of multiple objects, and we present a new way how to analyze these kinds of data.…”

Demonstration Report: Handheld UXO Discriminator, SERDP No. MR-1667

“…There are six types of UXO present at the APG Blind Test Grid -25 mm, 37 mm, 60 mm, 81 mm, 105 mm (IF=indirect fire) projectiles, and 105 mm HEAT mortar (DF=direct fire). Principal polarizabilities from the soundings that have been selected for the discrimination were analyzed using a variant of the empirical likelihood ratio method (outlined in Gasperikova, et al 2009). In the empirical likelihood ratio method, probability densities of principal polarizability responses were estimated from the training data, previously collected UXO and scrap responses separately.…”

“…In keeping with these remarks and with prior funding (UX-1225, MM-0437, and MM-0838), the LBNL group has successfully designed and built the cart-mounted Berkeley UXO Discriminator (BUD) and demonstrated its performance at various test sites (cf. Gasperikova et al, 2007Gasperikova et al, , 2008Gasperikova et al, , and 2009). …”