UXO Targets Research Articles

Unmanned unexploded ordnance detection system based on magnetic method

Abstract Magnetic method is one of the main methods of UXO detection. This paper uses cesium optical pump magnetic detection module combined with UAV to build an unmanned UXO detection system, and introduces the detection principle and composition of the system. At the same time, the system is used to detect four kinds of UXO targets. The test results show that the system can detect ferromagnetic UXO targets, and can locate the position of UXO targets through magnetic anomaly images. Finally, the limit detection range of four kinds of targets is tested, and the limit detection range of 155 projectiles can reach 4.5m, which meets the actual detection requirements

Inverse modelling and classification of magnetic responses to improve marine unexploded ordnance rationalization

SUMMARY Unexploded ordnance (UXO), often deployed in WWI and WWII, are still present on the seabed posing a risk to seabed construction. UXO surveys identify potential UXO targets which are then investigated and removed where necessary; however, approximately 96 per cent of targets investigated on projects included in this study were non-UXO (false positives). Here we investigate methods of improving statistical confidence in targets picked through the improved classification of magnetic response, utilizing simulation methods and historic data. A simulation of the induced magnetism of UXO was developed to model the most likely dimensions and orientation of a given source item. Modelling results and measured variables were combined in an optimization algorithm, hereon referred to as ‘the classifier’. We document the results of integrating the magnetic responses of 3027 targets from 18 offshore wind projects into the classifier. Five of these projects were performed as tests in which the target results were unknown during classification. Finally, the classifier was deployed on a live project, Hollandse Kust Zuid 3 and 4 Offshore Wind Farm, in which it enabled the removal of 67 targets from the from the 1200-target investigation list. The classifier proved to be a valuable additional tool to assist the target rationalization process, reliably and repeatably distinguishing UXO from other items, thereby reducing false positives and repeatably demonstrating no threshold UXO false negatives. Assumptions and limitations of this methodology were highlighted, which must be understood and considered when integrating this approach on future projects.

Dual-Mode Detection Method for UXO Targets by Measuring Magnetic Anomaly and Electromagnetic Response With FeNiMoSiB/PZT-5A Composite

Dual-Mode Detection Method for UXO Targets by Measuring Magnetic Anomaly and Electromagnetic Response With FeNiMoSiB/PZT-5A Composite

Coherent fusion of multi-aspect scans of UXO targets from CLUTTEREX16

During the ONR and SERDP sponsored 2016 CLUTTEREX experiments, a large number of UXO were placed in a target field. These UXO were scanned by a sonar system mounted on a linear rail. Following each scan, the UXO were rotated in place by increments of 20 degrees to build up a multi-aspect acoustic characterization of each target. An automated process was subsequently developed to coherently fuse the results of these rotations to form 180-degree wide acoustic characterizations that could be used to represent the target in the complex image, frequency vs. aspect, or time vs. aspect domains. This talk will discuss the fusion process and the results for UXO and clutter objects in the target field.

Measurements and modeling of acoustic scattering from targets in littoral environments

Broadband laboratory and at-sea measurements systems have been built by NRL to quantify the acoustic target strength of objects sitting on or in the bottom of littoral environments. Over the past decade, these measurements and the subsequent modeling of the target strength have helped to develop an understanding of how the environment, especially near the bottom interface, impacts the structural acoustic response of a variety of objects. In this talk we will present a set of laboratory, at-sea rail and AUV based back scatter, forward scatter, and propagation measurements with subsequent analysis to understand the impact of the littoral environment. Simple targets such as spheres, along with UXO targets will be discussed. The analysis will be focused on quantifying the changes to target strength as a result of being near the bottom interface. In addition to the traditional backscatter or monosatic target strength, we focus upon efforts to investigate the multi-static scattering from targets. [Work supported by ONR.]

Magnetic Response of Clustered UXO Targets

The objective of many recent UXO surveys has been described as “wide-area assessment” with the purpose of obtaining better definition of a known problem area. The targets of interest are clusters of ordnance, fragments and debris which are all indicators of greater contamination, higher risk of UXO hazard and higher remediation or construction costs. This is a different problem from the detection and discrimination of individual anomalies. This paper provides a definition of a “cluster” based on the amount of overlap between individual dipole signatures. In total field surveys, magnetic anomalies overlap significantly and show an increased amplitude response once the individual sources are spaced closer than 0.5 times the sensor height. When this condition is extended over a large area, such as the center of a target site, the result can be comparable to a horizontal sheet of dipoles. The equations to simulate a horizontal sheet are derived, and from these the relative density of targets may be calculated from the measured data by assuming a nominal target moment. Two field tests support both the qualitative and quantitative predictions. Extending this concept to field practice, we examine some of the implications for standard operational procedures. For example, if we accept that QA/QC metrics should represent the targets of interest, then we should require wide-area assessment surveys to create impractically large grids of surface frag. Likewise, for detection of clusters the concepts of detection probability and search radius based on single items are irrelevant. Discrimination techniques that rely on dipole fitting will be extremely inaccurate. Instead, QA parameters and models suitable for horizontal sheets will have to be derived.

Fast approximate EM induction modeling of metallic and UXO targets using a permeable prism

The time-domain EM induction response of non-magnetic and magnetic targets can be approximated using a conductive permeable prism composed of six faces of conductive plates, each face being composed of a set of conductive ribbons. The effect of magnetic permeability is included by the use of two “apparent flux gathering” coefficients, and two “effective magnetic permeability” coefficients, in the axial and transverse directions. These four magnetic property coefficients are a function of physical properties and geometry of the target, but are independent of prism orientation relative to a transmitter. The approximation algorithm is computationally fast, allowing inversions for target parameters to be achieved in seconds. The model is tested on profiles acquired with a Geonics EM63 time-domain EM metal detector over a non-magnetic copper pipe target, and a steel artillery shell in horizontal and vertical orientations. Results show that this approximation to a permeable prism has a capability of fitting geometric, conductivity and magnetic parameters at both early and late sample times. The magnetic parameters show strong change from early to late times on the EMI decay curve, indicating that the magnetic properties of the target have non-linear characteristics. It is proposed that these magnetic parameters and the nature of their non-linearity may carry additional discrimination information for distinguishing between intact munitions and scrap in UXO studies.