Detection Of Buried Landmines Research Articles

D–T neutron generators as a feasibility tool for landmine detection based on neutron backscattering method

The detection of buried landmines was investigated based on using D–T neutron source and neutron backscattering method. Signal-to-noise ratio – which is the number of backscattered neutrons from the soil containing the explosives respect to the soil without explosives – was calculated using Monte-Carlo N-particle transport code. Different materials were used between the neutron source and soil to increase the signal-to-noise ratio. The results showed that the thermal backscattered neutrons from landmine can be increased up to 2 times greater than the background. In addition, the effect of soil moisture on the results was studied.

Fluorescent Nanofilms for Nitroaromatic Explosives Detection-Promises and Challenges

Fast and sensitive detection of nitro-aromatic explosives is of vital importance for finding hidden explosives in airport luggage or mails, screening of personnel, and detection of buried landmines [1-3]. A crucial example is the detection of trace amount of 2,4,6-trinitrotoluene (TNT), which is a typical nitro-aromatic explosives [ 4-8]. Various TNT detection methods are currently available, such as, the fluorescence quenching method, micromechanical sensors based on micro cantilever, the electrochemical method, ion mobility s pectroscopy (IMS), the surface-enhanced Raman spectroscopy ( SERS) and semiconductor based gas sensors [7,9-23]. Among t he above-mentioned methods used for TNT detection, the fluorescence quenching method is considered to be the most effective tool for sensing nitro-aromatic explosives in recent years owing to its high sensitivity, convenience, easy visualization, and short response t ime for detection [24].

Discrimination between landmine and mine-like targets using wavelets and spectral analysis

Landmine is an explosive apparatus hidden in or on the ground, which blows up when a person or vehicle passes over it. Egypt is one of the countries suffering due to the unexploded ordnance (UXO). Around 2 million UXO are present in the Egyptian soil especially at Al-Alameen province, north of the western desert. Detection of buried landmines is a problem of military and humanitarian importance.Ground penetrating radar (GPR) is a powerful and non-destructive geophysical approach with a wide range of advantages in the field of landmine inspection. In the present paper, we apply different simulation models with Vivaldi antenna and mine-like targets by using the CST Microwave studio program. The field work is carried out by using a GPR device of model SIR 2000 from GSSI (Geophysical Survey Systems Incorporation) connected to 900MHz antenna where the targets were buried in sand soil. Depending on the fact that the receiving powers (reflected, refracted and scattered) from the different materials are different, we study the spectral power densities for the received power from the different targets. The techniques used in this study are: direct fast Fourier transform, short time Fourier transform (spectrogram), wavelets transform and denoising techniques. Our results ought to be considered as finger prints for different scanned targets during this work. So we can discriminate between landmines and mine-like targets.

Remote detection of buried land-mines and IEDs using LWIR polarimetric imaging

We report results of an ongoing study designed to assess the ability for enhanced detection of recently buried land-mines and/or improvised explosive devices (IED) devices using passive long-wave infrared (LWIR) polarimetric imaging. Polarimetric results are presented for a series of field tests conducted at various locations and soil types. Well-calibrated Stokes images, S0, S1, S2, and the degree-of-linear-polarization (DoLP) are recorded for different line-of-sight (LOS) slant paths at varying distances. Results span a three-year time period in which three different LWIR polarimetric camera systems are used. All three polarimetric imaging platforms used a spinning-achromatic-retarder (SAR) design capable of achieving high polarimetric frame rates and good radiometric throughput without the loss of spatial resolution inherent in other optical designs. Receiver-operating-characteristic (ROC) analysis and a standardized contrast parameter are used to compare detectability between conventional LWIR thermal and polarimetric imagery. Results suggest improved detectability, regardless of geographic location or soil type.

Hand-Held GPR Imaging Using Migration for Irregular Data

Handheld ground-penetrating radar (GPR) system is one of a number of technologies that has been researched as a means of improving landmine detection efficiency. But it is difficult to display landmine imaging in horizontal slices, because human being operator cannot collect regular GPR data along the survey line and the measurement positions are random. Also detection of buried landmines by GPR normally suffers from very strong clutter that will decrease the image quality. So we proposed two processing procedures to achieve hand-held GPR subsurface imaging. One processing procedure is composed of interpolation and migration algorithm. The interpolation is chosen to produce the regular grid data set. The migration is used to improve signal-clutter ratio and reconstruct subsurface imaging. In the other processing procedure we developed a simply modified migration algorithm that can directly processes irregular GPR data. Two processing procedures, migration with interpolation and modified migration without interpolation, were applied to a field experiment data respectively. Both of processing procedures can efficiently process irregular GPR data and achieve subsurface imaging of high quality. The imaging processed by migration with interpolation is used in the dual sensor, advanced landmine imaging system (ALIS), and two sets of ALIS have detected more than 80 AP-mines since 2009. Also the modified migration algorithm can save the processing time, which is important for field real-time signal processing. We concluded that to achieve clear hand-held GPR imaging, the interpolation is not necessary algorithm and the migration is the key algorithm.

Feasibility of fast neutron analysis for the detection of explosives buried in soil

Abstract A commercialized thermal neutron analysis (TNA) sensor has been developed to confirm the presence of buried bulk explosives as part of a multi-sensor anti-tank landmine detection system. Continuing improvements to the TNA system have included the use of an electronic pulsed neutron generator that offers the possibility of applying fast neutron analysis (FNA) methods to improve the system's detection capability. This paper describes an investigation into the use of FNA as a complementary component in such a TNA system. The results of a modeling study using simple geometries and a full model of the TNA sensor head are presented, as well as preliminary results from an experimental associated particle imaging (API) system that supports the modeling study results. The investigation has concluded that the pulsed beam FNA approach would not improve the detection performance of a TNA system for landmine or buried IED detection in a confirmation role, and could not be made into a practical stand-alone detection system for buried anti-tank landmines. Detection of buried landmines and IEDs by FNA remains a possibility, however, through the use of the API technique.

Detection and characterization of buried landmines using infrared thermography

The application of infrared (IR) thermography to the detection and characterization of buried landmines (more generally, buried objects) is introduced. The problem is aimed at detecting the presence of objects buried under the ground and characterizing them by estimating their thermal and geometrical properties using IR measurements on the soil surface. Mathematically, this problem can be stated as an inverse problem for reconstructing a piecewise constant coefficient of a three-dimensional heat equation in a parallelepiped from only one measurement taken at one plane of its boundary (the air-soil interface). Due to the lack of spatial information in the observed data, this problem is extremely ill-posed. In order to reduce its ill-posedness, keeping in mind the application of detecting buried landmines we make use of some simplification steps and propose a two-step method for solving it. The performance of the proposed algorithm is illustrated with numerical examples.

High‐powered parametric acoustic array in air.

MIT Lincoln Laboratory has developed a prototype high‐powered parametric acoustic array (HPPAA) for standoff acoustic excitation in several applications. Parametric arrays offer a highly directional, narrow beam mechanism to deliver sound in air to desired targets typically within a 100 m range. However, a difficult challenge arises in generating sufficient sound power at difference‐frequencies below 1000 Hz at a range which can be critical for many target types. An important objective of the HPPAA design maximizes the difference‐frequency pressure amplitude at range by maximizing the end‐fire array length established by the PAA. The design optimizes the trade‐offs between the three characteristic lengths that control the resultant end‐fire array length including the pump or carrier wave attenuation, PAA aperture, and acoustic saturation of air. In field demonstrations, the HPPAA generated a carrier wave pressure power approximately 155 dB re‐20‐microPa one meter from the PAA face while generating a 300 Hz difference‐frequency SPL of 90 dB re‐20‐microPa 8 meters from the PAA. These sound pressure levels at a few hundred hertz may enable safe standoff excitation and detection of buried landmines and may be useful in standoff nondestructive testing (NDT) damage detection and imaging of structures.

Infrared Thermography for Buried Landmine Detection: Inverse Problem Setting

This paper deals with an inverse problem arising in infrared (IR) thermography for buried landmine detection. It is aimed at using a thermal model and measured IR images to detect the presence of buried objects and characterize them in terms of thermal and geometrical properties. The inverse problem is mathematically stated as an optimization one using the well-known least-square approach. The main difficulty in solving this problem comes from the fact that it is severely ill posed due to lack of information in measured data. A two-step algorithm is proposed for solving it. The performance of the algorithm is illustrated using some simulated and real experimental data. The sensitivity of the proposed algorithm to various factors is analyzed. A data processing chain including anomaly detection and characterization is also introduced and discussed.

Vector surface velocity measurement using contour scanning laser vibrometers for the detection of landmines

Much work has been done studying the detection of buried landmines using acoustic excitation and measuring the vibration response of the ground using Laser Doppler Vibrometry (LDV). We examine the benefits of measuring the full three-dimensional velocity response of the ground surface when a landmine is present. Three-dimensional velocity measurements provide a richer data set for identification of buried targets and avoid potential errors associated with projecting the surface velocity vector onto a single laser line of sight direction. We present results of a study conducted using landmines buried in sand in a laboratory environment. The data were obtained using a novel five-axis laser vibrometry system, which uses a single point LDV system to measure the surface of the sand from multiple angles at each measurement location. Data will be presented showing the consequences of a buried landmine on the three-dimensional velocity response of a contoured ground surface.

Scattering of a buried circular membrane imbedded in a rigid substrate in a layered fluid waveguide

A study of mathematical modeling of the buried landmine detection problem involves wave propagation in a layered waveguide in the presence of a flush mount buried circular target. In this study, emphasis is placed on acoustic to seismic coupling of an airborne CW point source located over an iso-velocity fluid layer. The top plate of the buried landmine is modeled as a circular elastic membrane stretched flush over a cylindrical cavity in a rigid substrate beneath the fluid layer. The finite fluid layer affords a manageable study of the modal resonances in the waveguide system with and without the target. The Helmholtz equation is solved in the atmospheric layer using cylindrical coordinates and a point source. The homogeneous Helmholtz equation is used in the fluid layer. Green's function techniques involving vibrations of the membrane are incorporated into the boundary conditions. Results of the closed form normal mode solution will be presented in a MATLAB™ user interface; describing the effects of frequency, depth, density, sound, absorption, including radius and elastic parameters of the membrane. Comparison of the results (involving the fluid surface particle velocity profiles across the target) will be made with experiments reported in the literature to evaluate its usefulness.

Fast acoustic landmine detection using multiple beam laser Doppler vibrometry

An acoustic method of buried landmine detection consisting of excitation of the ground using airborne sound or seismic waves in the frequency range from about 50 Hz to 1000 Hz, and obtaining a velocity image of the ground surface with a laser Doppler vibrometer (LDV) has been developed and successfully tested in the laboratory and field experiments. The presence of a buried landmine can be detected by an abnormality in the velocity image. Initially, the scanning single‐beam LDV created a velocity image of the ground through point‐by‐point measurements, which resulted in a long measurement time. To reduce this measurement time, a multiple beam LDV having 16 beams configured in a linear array was developed and successfully used in field experiments. To further reduce the time of measurement, a full‐field LDV capable of making 256 vibration measurements in parallel on the target, configured as 16x16 square array of points equally separated in x‐ and y‐directions has been recently developed. The system is capable of creating a two‐dimensional vibrational velocity image of the ground surface in the time defined by the required frequency resolution. The parallel measurement makes the system a unique tool to measure transient vibrations.

Investigation of microphones as near-ground sensors for seismic detection of buried landmines

Commercially available microphones were investigated as near-ground sensors to measure the acoustic pressure and the vertical pressure gradient of evanescent air-acoustic waves associated with audio-frequency seismic waves. Measurements in close proximity to the surface and the use of waveguides were found to improve the microphone signal's quality, the comparison of its seismic sensitivity to its sensitivity to propagating sound (ambient acoustic noise and nonseismic reverberation). Landmine images formed using microphone data collected in a laboratory experimental model clearly locate buried inert landmines but exhibit more clutter than images of the same objects formed with seismic displacement data collected using other techniques.

An investigation of surface-contacting sensors for the seismic detection of buried landmines

Techniques have been studied for the detection of buried landmines with acoustic/seismic interrogation signals. Much of this work has involved full wave-field imaging from local measurements of ground motion using noncontact sensors. These offer inherent safety for the system operator and accommodate the need to make measurements over rough ground surfaces. The system requirement is, however, only that a sensor does not intrude on the measurement rather than that it not contact the ground. An experimental investigation was conducted into the feasibility of an array of ground-contacting sensors for use in a seismic landmine-detection system that exploits full wave-field imaging. The main considerations in the design of the array sensor were safety, sensitivity, fidelity, reproducibility, and sensor-to-sensor interaction. A relatively simple and inexpensive sensor was demonstrated in an experimental simulation of a landmine-detection system. The sensor, which is suitable for inclusion in a large planar array that could be used for detection confirmation, exerts a safe normal force at the point of contact and enables detection performance comparable to that which could be achieved using noncontact techniques.

Detection of explosive-related compounds by laser photoionization time-of-flight mass spectrometry

We report studies using laser photoionization and time-of-flight mass spectrometry to detect several explosive-related compounds (ERCs). The ultimate goal of this work is the detection of buried land mines through their chemical signatures. Resonantly enhanced multiphoton ionization using jet expansion cooling, with a nanosecond pulse laser, results in complete photofragmentation of the parent ERC and appearance only of the NO+ ion, which forms all of the detected signal. This will also occur for compounds naturally occurring in the environment, such as NO2 or peroxyacetylnitrate, rendering too many false alarms for this approach to be viable. Therefore, two other techniques were evaluated. Single-photon ionization with nanosecond pulses in the vacuum ultraviolet is shown to produce only the parent ion, and is probably the most suitable choice. For 2,4-dinitrobenzene we find a limit of detection of about 40 ppb, for a signal to noise ratio of 3. This may be sufficient for land-mine detection, but improvement is likely with future work. Nonresonant multiphoton ionization in the ultraviolet with a femtosecond laser produces fragmentation but retains some parent ERC ion signal. The limit of detection is similar to that of single-photon ionization but it is harder to implement with lasers now commercially available. Future directions are outlined.

Multi-beam laser Doppler vibrometer for landmine detection

The method of buried landmine detection based on using elastic waves in the ground and a laser Doppler vibrometer (LDV) as a vibration sensor has shown excellent performance in field tests. To increase the speed of measurements, a multi-beam laser Doppler vibrometer (MB-LDV) was developed. The system is based on a heterodyne interferometer and is capable of simultaneously measuring the vibration of the ground at 16 points over a span of 1 m with a velocity resolution of less than 1 µm/s. Both digital in-phase and quadrature (I&Q) and analog phase-locked loop (PLL) demodulation have been used for signal processing. The MB-LDV can create a velocity image of the ground surface either in "stop-and-stare" mode or in a continuously scanning mode. The continuously scanning operation results in an increased velocity noise floor due to speckle noise. The speckle noise floor increases with the increase of the speed of the laser beam and can degrade the velocity image of a mine. To overcome the effects of speckle noise, the excitation source must provide a ground vibration velocity higher than the velocity noise floor of the vibrometer. The MB-LDV has been tested at landmine test lanes and shows the ability to detect buried landmine within a one-square-meter area in a time of less than 20 s.

Nonlinear acoustic detection of buried landmines: A tribute to Joe Blue

As a graduate student at Brown University (∼1978), this researcher was very fortunate to have met Joe Blue at Acoustical Society meetings. As I had little knowledge of the members in the society and an extremely limited grasp of the practical technology behind nonlinear acoustics, Joe was extremely friendly and took the time to answer a long list of questions about nonlinear underwater transducer designs with applications to the parametric array [Muir, T.G. & Blue, J.E. ‘‘Experiments on the acoustic modulation of large-amplitude waves,’’ J. Acoust. Soc. Am. 46, 227–232 (1969)]. This influenced this researcher’s Ph.D. thesis involving experiments on the scattering of sound by sound in the presence of turbulence. Recently, experiments on the nonlinear acoustic detection of buried landmines [Korman, M.S. & Sabatier, J.M., ‘‘Nonlinear acoustic techniques for landmine detection,’’ J. Acoust. Soc. Am. 116, 3354–3369 (2004)] has brought some attention to understanding the difference between classical and nonclassical nonlinearity. As a tribute to Joe Blue, the latest results will be presented involving the connections to mesoscopic nonlinear elasticity and slow dynamics in nonlinear buried landmine detection. Here, tuning curve behavior of the soil-surface vibration over a landmine exhibits a linear decrease in resonant frequency with increasing amplitude. Two-tone test excitation reveals a rich spectrum of combination frequency components useful in detection schemes.

Thermal detection of buried landmines by local heating

A new concept for buried antipersonnel mine (APM) detection is proposed. The detection system is based on a focused heat source and a contactless thermometer mounted on a suspended carriage scanning the ground surface. Presence of heat diffusivity anomalies (mine candidates) is assessed from anomalies in the surface temperature measured after the local heating. After describing the structure of the proposed system, and the physical functioning principles, we discuss a case study, based on numerical simulations, which proves the feasibility of the device. Main advantages of the system proposed are the simplicity of the equipment (that is cheap to realize, and easy to use, maintain and repair), and power efficiency.

Strength of landmine signatures under different soil conditions: implications for sensor fusion

Most sensors for the detection of buried landmines are influenced by the properties of the soil that surrounds the mine. The temporal and spatial variability in soil properties accounts for a significant part of the detection uncertainty that is associated with most sensors. In particular, most sensor types (e.g. ground-penetrating radar, thermal infrared cameras, and chemical sniffers) are affected by the water content of the soil. However, each sensor type reacts in its own way to variations in soil water content and other soil properties. The resulting variation in sensor performance has serious implications for sensor fusion operations. We show how knowledge of soil physics can contribute to a better understanding of sensor performance and can lead to improved data fusion.

Detection of buried landmines and hidden explosives using neutron, X-ray and gamma-ray probes

Detection of buried landmines and hidden explosives using neutron, X-ray and gamma-ray probes