Optimized inside-out magnetic resonance probe for soil moisture measuring in situ

Shen, Sheng; Guo, Pan; Wu, Jiamin; Ding, Ye; Chen, Fangge; Meng, Fanqin; Xu, Zheng

doi:10.1016/j.jmr.2019.07.052

Cited by 14 publications

(3 citation statements)

References 15 publications

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“…Magnet optimization was carried out by calculating its magnetic field distribution. The remanent magnetization of a permanent magnet is equivalent to a toroidal current around the surface of the permanent magnet block, for which the magnetic field distribution of the permanent magnet can be calculated using the Biot–Savard law [ 20 , 21 ]. The magnetic field strengths B x , B y , and B z generated at any point P (x, y, z) in space can be expressed by Equations (2)–(6), where dB x , dB y , and dB z are the magnetic inductance components in the x, y, and z directions at point P.

where

is the magnetic permeability in a vacuum and

is the surface current density.…”

Section: Methodsmentioning

confidence: 99%

Optimized Unilateral Magnetic Resonance Sensor with Constant Gradient and Its Applications in Composite Insulators

Guo

Yang

et al. 2023

Sensors

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In this study, an optimized unilateral magnetic resonance sensor with a three-magnet array is presented for assessing the aging of composite insulators in power grids. The sensor’s optimization involved enhancing the static magnetic field strength and the homogeneity of the RF field while maintaining a constant gradient in the direction of the vertical sensor surface and maximizing homogeneity in the horizontal direction. The center layer of the target area was positioned 4 mm from the coil’s upper surface, resulting in a magnetic field strength of 139.74 mT at the center point of the area, with a gradient of 2.318 T/m and a corresponding hydrogen atomic nuclear magnetic resonance frequency of 5.95 MHz. The magnetic field uniformity over a 10 mm × 10 mm range on the plane was 0.75%. The sensor measured 120 mm × 130.5 mm × 76 mm and weighed 7.5 kg. Employing the optimized sensor, magnetic resonance assessment experiments were conducted on composite insulator samples utilizing the CPMG (Carr–Purcell–Meiboom–Gill) pulse sequence. The T2 distribution provided visualizations of the T2 decay in insulator samples with different degrees of aging.

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where

is the magnetic permeability in a vacuum and

is the surface current density.…”

Section: Methodsmentioning

confidence: 99%

Optimized Unilateral Magnetic Resonance Sensor with Constant Gradient and Its Applications in Composite Insulators

Guo

Yang

et al. 2023

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

“…Magnet optimization was carried out by calculating its magnetic field distribution. The remanent magnetization of a permanent magnet is equivalent to a toroidal current around the surface of the permanent magnet block, for which the magnetic field distribution of the permanent magnet can be calculated using the Biot-Savard law [20,21]. The magnetic field strengths Bx, By, and Bz generated at any point P (x, y, z) in space can be expressed by Equations ( 2) -( 6), where dBx, dBy, and dBz are the magnetic inductance components in the x, y, and z directions at the point P.…”

Section: A Magnet Optimizationmentioning

confidence: 99%

Optimized Unilateral Magnetic Resonance Sensor with Constant Gradient and Its Applications on Composite Insulators

Guo

Yang

et al. 2023

Preprint

Self Cite

View full text Add to dashboard Cite

In this study, an optimized unilateral magnetic resonance sensor with a three-magnet array is presented for assessing the aging of composite insulators in power grids. The sensor's optimization involved enhancing the static magnetic field strength and the homogeneity of the RF field while maintaining a constant gradient in the direction of the vertical sensor surface and maximizing homogeneity in the horizontal direction. The center layer of the target area is positioned 4 mm from the coil's upper surface, resulting in a magnetic field strength of 139.74 mT at the center point of the area, with a gradient of 2.318 T/m and a corresponding hydrogen atomic nuclear magnetic resonance frequency of 5.95 MHz. The magnetic field uniformity over a 10 mm × 10 mm range on the plane is 0.75%. The sensor measures 120 mm × 130.5 mm × 76 mm and weighs 7.5 kg. Employing the optimized sensor, magnetic resonance assessment experiments were conducted on composite insulator samples utilizing the CPMG (Carr-Purcell-Meiboom-Gill) pulse sequence. The T2 distribution provides visualizations of the T2 decay in insulator samples with different degrees of aging.

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“…Soil moisture parameters can be used to assess the degree of fertilizer uptake by crops and ensure the efficient growth of crops. A rapid and noninvasive method [1][2][3] is required given that traditional methods for * Authors to whom any correspondence should be addressed. measuring soil moisture parameters are time consuming and invasive [4].…”

Section: Introductionmentioning

confidence: 99%

A compact magnetic resonance system with inside-out sensor for soil moisture measurement

Wan¹,

Wang²,

Guo³

et al. 2022

Meas. Sci. Technol.

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Accurate measurement of soil moisture parameters plays a vital role in promoting agricultural production. Nuclear magnetic resonance (NMR) measuring instruments have become increasingly compact, especially in low field applications. However, NMR soil moisture measurement instruments still have problems with portability. We report on a compact NMR measuring instrument that focuses on the circuit’s design and construction. The instrument includes an inside-out sensor, NMR spectrometer, radio frequency (RF) power amplifier, low-noise preamplifier (LNA), and duplexer. They are integrated into a slim 3D-printed cylinder. The integrated NMR instrument is portable and user-friendly and can reduce the influence of nonideal factors, such as transmission line effects and electromagnetic interference. We conducted different soil moisture experiments with the prototype using Carr–Purcell–Meiboom–Gill (CPMG) pulse sequence to obtain the corresponding transverse relaxation time (T2) decay curves. Then, the T2 1D spectrum distributions were obtained by inverse Laplace transformation. Finally, the results reveal that the area of long T2 component decreases as the soil moisture content decreases.

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Optimized inside-out magnetic resonance probe for soil moisture measuring in situ

Cited by 14 publications

References 15 publications

Optimized Unilateral Magnetic Resonance Sensor with Constant Gradient and Its Applications in Composite Insulators

Optimized Unilateral Magnetic Resonance Sensor with Constant Gradient and Its Applications in Composite Insulators

Optimized Unilateral Magnetic Resonance Sensor with Constant Gradient and Its Applications on Composite Insulators

A compact magnetic resonance system with inside-out sensor for soil moisture measurement

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