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A new device designed for both volumetric and surface NQR detection of substances spatially located in several positions,
and in the presence of environmental interference, is described. The device consists of two probe coils, placed on the same
detection plane, for excitation and detection of NQR signals. Experimental results obtained using Strong Off Resonance Comb
(SORC) pulse sequences, for the excitation of the ν- transition in samples of Sodium Nitrite (NaNO
2), are presented. It is shown that, when the total signals induced in each coil are properly combined, the interference commonly
detected in both coils is attenuated relative to the NQR signal detected by either one or both probe coils. NQR signal can
be detected by either one or both coils, but in both cases the noise induced by distant environmental sources is attenuated.
These files correspond to the revised version of the paper N° O-G-6, entitled “Pulsed 14N NQR device designed to detect substances in the presence of environmental noise” presented at the XVII International symposium
on Nuclear Quadrupole Interactions, held in Bonn, Germany in 2004.
Argentinian and International patents pending. 相似文献
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Modifications of the steady-state free precession multi-pulse technique for the effective detection of the nuclear quadrupole resonance (NQR) signals are proposed. These modifications are based on the use of composite pulses and enable the suppression of the coherent noise signals such as the magneto-acoustic and piezo-electric signals or the ringing signal from the NQR probe. Experimental results of applying the proposed technique to nitrogen-14 NQR in the sample of C6H12N4 are also presented and convincingly demonstrate its effectiveness. 相似文献
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介绍了基于核四极矩技术的爆炸物检测原理及信号处理方法.系统分析了NQR信号检测中主要误差来源,提出多种方法消除NQR信号处理中检测误差,主要包括相关累加消除随机噪声;单通道自适应消除振铃影响;相关性检测抑制同频干扰.实验表明相关检测可有效提高NQR信号信噪比,提高微弱NQR信号检测的准确性. 相似文献
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D. Ya. Osokin R. R. Khusnutdinov G. V. Mozzhukhin B. Z. Rameev 《Technical Physics》2014,59(5):749-753
The application of the multipulse sequences in nuclear quadrupole resonance (NQR) detection of explosive and narcotic substances has been studied. Various approaches to increase the signal to noise ratio (SNR) of signal detection are considered. We discussed two modifications of the phase-alternated multiple-pulse sequence (PAMS): the 180° pulse sequence with a preparatory pulse and the 90° pulse sequence. The advantages of optimal filtering to detect NQR in the case of the coherent steady-state precession have been analyzed. It has been shown that this technique is effective in filtering high-frequency and low-frequency noise and increasing the reliability of NQR detection. Our analysis also shows the PAMS with 180° pulses is more effective than PSL sequence from point of view of the application of optimal filtering procedure to the steady-state NQR signal. 相似文献
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Gregorovič A Apih T Kvasić I Lužnik J Pirnat J Trontelj Z Strle D Muševič I 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,209(1):79-82
We demonstrate excitation and detection of nuclear magnetization in a nuclear quadrupole resonance (NQR) experiment with a parallel plate capacitor, where the sample is located between the two capacitor plates and not in a coil as usually. While the sensitivity of this capacitor-based detection is found lower compared to an optimal coil-based detection of the same amount of sample, it becomes comparable in the case of very thin samples and even advantageous in the proximity of conducting bodies. This capacitor-based setup may find its application in acquisition of NQR signals from the surface layers on conducting bodies or in a portable tightly integrated nuclear magnetic resonance sensor. 相似文献
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Application of the Wavelet Transform for Detecting Signals of Nuclear Quadrupole Resonance 总被引:1,自引:0,他引:1
In the present study, the wavelet transform is used to increase the signal-to-noise ratio of nuclear quadrupole resonance (NQR) signals in the direct pulse method. The efficiency of the wavelet and Fourier transforms used for detecting the NQR signal component is compared. The signal consists of noise, magnetoacoustic and piezoelectric signals, noise from external sources, and NQR signal. Signals from 14
N nuclei in hexahydro-1,3,5-trinitro-s-triazine C3H6N6O6 (RDX) are investigated at a temperature of 298 K.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 47–50, January, 2005. 相似文献
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In the correlation method the signal shape information can be utilized for detection of weak signals, hidden in the noise. We tested the advantages, drawbacks and some practical features of the method applied to magnetic resonance detection. The influence of the signal width, shape and similarity to the template on the correlation function was studied by numerical simulation. The findings were applied to the optimization of the template for improved localization of a noisy14N nuclear quadrupole resonance (NQR) line in NaNO2 during repetitive scans by a superregenerative spectrometer. The value of the correlation method in faster NQR intensity evaluation was also confirmed. 相似文献