Exploiting temperature dependency in the detection of NQR signals

Jakobsson, Andreas; Mossberg, Magnus; Rowe, Michael; Smith, J. A. S.

doi:10.1109/tsp.2006.871969

Cited by 57 publications

(40 citation statements)

References 14 publications

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“…Importantly these lines, which are both associated with the para-nitro groups, also have the lowest temperature coefficients making them the best choice for detecting this explosive when the temperature of the sample is uncertain. When the sample temperature is known and multiple resolved lines are detected, it is possible to use a "finger print" of line frequencies (usually the four lines from 848 to 837 kHz), to enhance the signal-to-noise ratio (SNR) using approximate maximum likelihood parametric data processing [25].…”

Section: Temperature Variation Of Tnt 14 N Nqr Frequenciesmentioning

confidence: 99%

14N NQR, relaxation and molecular dynamics of the explosive TNT

Smith

Rowe

Althoefer

et al. 2015

Solid State Nuclear Magnetic Resonance

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Multiple pulse sequences are widely used for signal enhancement in NQR detection applications. Since the various 14 N NQR relaxation times, signal decay times and frequency of each NQR line have a major influence on detection sequence performance, it is important to characterise these parameters and their temperature variation, as fully as possible. In this paper we discuss such measurements for a number of the ν + and ν − NQR lines of monoclinic and orthorhombic TNT and relate the temperature variation results to molecular dynamics. The temperature variation of the 14 N spin-lattice relaxation times T 1 is interpreted as due to hindered rotation of the NO 2 group about the C-NO 2 bond with an activation energy of 89 kJ mol -1 for the ortho and para groups of monoclinic TNT and 70 kJ mol -1 for the para group of orthorhombic TNT.

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Section: Temperature Variation Of Tnt 14 N Nqr Frequenciesmentioning

confidence: 99%

14N NQR, relaxation and molecular dynamics of the explosive TNT

Smith

Rowe

Althoefer

et al. 2015

Solid State Nuclear Magnetic Resonance

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“…, K, may be formed from (1) using a maximum likelihood algorithm, which in this case coincides with the LS solution. Due to space limitations, the reader is referred to, e.g., [3,6]) for the details.…”

Section: The Echo Train Esprit Algorithmmentioning

confidence: 99%

“…1. As discussed in [3,4], the signal resulting from a PSL excitation can be well modeled as ym,t = xm,t + wm,t,…”

Section: Introduction and Data Modelmentioning

confidence: 99%

“…Common approaches for estimating the parameters for this form of data is to sum the echoes, thereby destroying the finer details resulting from the echo train decay (and causing a bias in the estimates), and then use classical approaches such as the periodogram or the matrix pencil [1,2]. An alternative approach was taken in [3], where a least-squares (LS) based algorithm for estimating all the unknown parameters in (2) was proposed. Such an estimate is formed using a gradient or grid-based search, but then requires a careful initialization of the various parameters, an often non-trivial task.…”

Section: Introduction and Data Modelmentioning

confidence: 99%

See 1 more Smart Citation

An esprit-based parameter estimator for spectroscopic data

Gudmundson

Wirfält

Jakobsson

et al. 2012

2012 IEEE Statistical Signal Processing Workshop (SSP)

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The pulse spin-locking sequence is a common excitation sequence for magnetic resonance and nuclear quadrupole resonance signals, with the resulting measurement data being well modeled as a train of exponentially damped sinusoidals. In this paper, we derive an ESPRIT-based estimator for such signals, together with the corresponding Cramer-Rao lower bound. The proposed estimator is computationally efficient and only requires prior knowledge of the number of spectral lines, which is in general available in the considered applications. Numerical simulations indicate that the proposed method is close to statistically efficient, and that it offers an attractive approach for initialization of existing statistically efficient gradient or search based techniques.

QC 20121030

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“…This is a method particularly used for the detection of explosives and drugs. It is based on the detection of nitrogen isotope ( 14 N) in the content of an explosive or a drug [5]. 6) Timed neutron detection (TND): Significant reduction of time is needed to identify hidden explosives and other hazardous materials by the "neutron-in gammaout" method.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis for Remote Identification of Materials With Magnetic Characteristics

Ege

Şensoy

Kalender³

et al. 2011

IEEE Trans. Instrum. Meas.

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Abstract-There is a variety of methods used for remote sensing of objects such as acoustic, ground penetration radar detection, electromagnetic induction spectroscopy, infrared imaging, thermal neutron activation, core four-pole resonance, neutron backscattering, X-ray backscattering, and magnetic anomaly. The method that has to be used can be determined by the type of material, geographical location (underground or water), etc. Recent studies have been concentrated on the improvement of the criteria such as sensing distances, accuracy, and power consumption. In this paper, anomalies created by materials with magnetic characteristics at the perpendicular component of the Earth magnetic field have been detected by using a KMZ51 anisotropic magnetoresistive sensor with high sensitivity and low power consumption, and also, the effects of physical properties of materials on magnetic anomaly have been investigated. By analyzing the graphics obtained by 2-D motion of the sensor over the material, the most appropriate mathematical curves and formulas have been determined. Based on the physical properties of the magnetic material, the variations of the variables constituting the formulas of the curves have been analyzed. The contribution of this paper is the use of the results of these analyses for the purpose of identification of an unknown magnetic material. This is a new approach for the detection and determination of materials with magnetic characteristics by sensing the variation at the perpendicular component of the Earth magnetic field. The identification process has been explained in detail in this paper.Index Terms-Anisotropic magnetoresistive sensor (AMR), magnetic anomaly, magnetic materials, power consumption, remote sensing.

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Exploiting temperature dependency in the detection of NQR signals

Cited by 57 publications

References 14 publications

14N NQR, relaxation and molecular dynamics of the explosive TNT

14N NQR, relaxation and molecular dynamics of the explosive TNT

An esprit-based parameter estimator for spectroscopic data

Numerical Analysis for Remote Identification of Materials With Magnetic Characteristics

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