ALLTEM UXO Detection Sensitivity and Inversions for Target Parameters from Yuma Proving Ground Test Data

Wright, David L.; Moulton, Craig W.; Asch, Theodore H.; Brown, Philip J.; Nabighian, Misac N.; Li, Yaoguo; Oden, Charles P.

doi:10.4133/1.2924651

Cited by 8 publications

(4 citation statements)

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“…In recent years, significant progress has been made in discrimination technology, which includes both instrumentation and data processing and discrimination algorithms (e.g., Gasperikova et al, 2006Gasperikova et al, & 2007Huang et al, 2007;Pasion et al, 2007;Snyder and George, 2005;Wright et al, 2007).…”

mentioning

confidence: 99%

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

et al. 2009

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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.

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confidence: 99%

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

et al. 2009

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“…The motivation for using multi-axis excitation and observation of target response is that the additional information aids in going beyond detection of metal objects in the ground to the critical task of discriminating between probable UXO and harmless scrap metal that can be safely left in the ground. The system (Figure 1) was described in Wright et al, 2006, andWright et al, 2007. System control and data acquisition software, written in National Instruments LabVIEW ® , provides the flexibility of selecting a single Tx polarization or multiplexing through all three polarizations.…”

Section: Introductionmentioning

confidence: 99%

ALLTEM UXO detection and discrimination

Asch

Wright

Moulton

et al. 2008

SEG Technical Program Expanded Abstracts 2008

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ALLTEM is a multi-axis electromagnetic induction system designed for unexploded ordnance (UXO) applications. It uses a continuous triangle-wave excitation and provides good late-time signal-to-noise ratio (SNR) especially for ferrous targets. Multi-axis transmitter (Tx) and receiver (Rx) systems such as ALLTEM provide a richer data set from which to invert for the target parameters required to distinguish between clutter and UXO. Inversions of field data over the Army's UXO Calibration Grid and Blind Test Grid at the Yuma Proving Ground (YPG), Arizona in 2006 produced polarizability moment values for many buried UXO items that were reasonable and generally repeatable for targets of the same type buried at different orientations and depths. In 2007 a test stand was constructed that allows for collection of data with varying spatial data density and accurate automated position control. The behavior of inverted ALLTEM test stand data as a function of spatial data density, sensor SNR, and position error has been investigated. The results indicate that the ALLTEM inversion algorithm is more tolerant of sensor noise and position error than has been reported for single-axis systems. A high confidence level in inversion-derived target parameters is required when a target is declared to be harmless scrap metal that may safely be left in the ground. Unless high confidence can be demonstrated, state regulators will likely require that targets be dug regardless of any "no-dig" classifications produced from inversions, in which case remediation costs would not be decreased.

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“…If the viscous magnetic effects have slow spatial variations, and have essentially the same values at locations surrounding the target, then background soil response can be subtracted from the target response before analyzing the target [19]. Calculating the Green's function in (1) and (4) is computationally expensive, and is not needed is most cases (i.e., when viscous magnetic soil is not present).…”

Section: Signalmentioning

confidence: 99%

“…Finally, the signals from deep targets can be too small for proper characterization. For example, UXO targets deeper than about 1.5 meters are generally difficult to characterize with the ALLTEM system [19]. This paper analyzes data from the ALLTEM instrument because it uniquely combines the desirable aspects of being broadband, fully polarimatric, and makes both magneto-static and electro-dynamic measurements.…”

Section: Introductionmentioning

confidence: 99%

Combining Advances in Em Induction Instrumentation and Inversion Schemes for Uxo Characterization

Oden¹

2012

PIER B

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Abstract-Several experimental time-domain EM induction instruments have recently been developed for unexploded ordnance (UXO) detection and characterization that use multiple transmitting and receiving coil combinations. One such system, the US Geological Survey's ALLTEM system, is unique in that it measures both the electrodynamic response (i.e., induced eddy currents) and the magneto-static response (i.e., induced magnetization). This allows target characterization based on the dyadic polarizability of both responses. This paper examines the numerical response of the ALLTEM instrument due to spheroidal, conductive, and permeable UXO targets; and to conductive and optionally viscous magnetic earth. An inversion scheme is presented for spheroidal targets that incorporates fully polarimetric measurements for both magneto-static and electro-dynamic excitations. The performance of the inversion algorithm is evaluated using both simulated and surveyed data. The results are examined as a function of the number of coil combinations, number of instrument locations, and uncertainty in sensor location and orientation. Results from the specific cases tested (prolate spheroids lying horizontally) show that 1) that collecting data from more than 12 sensor locations or from more than four coil combinations reduced the chances that inversion solutions would be from a local minimum, and 2) that uncertainties in position greater than 3 cm or in orientation greater than 10 degrees cause errors in the estimated spheroid principal lengths of greater than 100%. Soil conductivities less than 1 S/m contribute negligible interference to the target response, but viscous magnetic soils with permeabilities greater than 10 −6 MKS units do cause detrimental interference.

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ALLTEM UXO Detection Sensitivity and Inversions for Target Parameters from Yuma Proving Ground Test Data

Cited by 8 publications

References 8 publications

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

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

ALLTEM UXO detection and discrimination

Combining Advances in Em Induction Instrumentation and Inversion Schemes for Uxo Characterization

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