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Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 201
Author(s):  
Ruochen Huang ◽  
Mingyang Lu ◽  
Ziqi Chen ◽  
Wuliang Yin

Alternating current field measurement (ACFM) testing is one of the promising techniques in the field of non-destructive testing with advantages of the non-contact capability and the reduction of lift-off effects. In this paper, a novel crack detection approach was proposed to reduce the effect of the angled crack (cack orientation) by using rotated ACFM techniques. The sensor probe is composed of an excitation coil and two receiving coils. Two receiving coils are orthogonally placed in the center of the excitation coil where the magnetic field is measured. It was found that the change of the x component and the peak value of the z component of the magnetic field when the sensor probe rotates around a crack followed a sine wave shape. A customized accelerated finite element method solver programmed in MATLAB was adopted to simulate the performance of the designed sensor probe which could significantly improve the computation efficiency due to the small crack perturbation. The experiments were also carried out to validate the simulations. It was found that the ratio between the z and x components of the magnetic field remained stable under various rotation angles. It showed the potential to estimate the depth of the crack from the ratio detected by combining the magnetic fields from both receiving coils (i.e., the x and z components of the magnetic field) using the rotated ACFM technique.


Author(s):  
Ruochen Huang ◽  
Mingyang Lu ◽  
Ziqi Chen ◽  
Wuliang Yin

Alternating current field measurement (ACFM) testing is one of promising techniques in the field of non-destructive testing with advantages of the non-contact capability and the reduction of lift-off effects. In this paper, a novel crack detection approach is proposed to reduce the effect of the angled crack (cack orientation) by using rotated ACFM techniques. The sensor probe is composed of an excitation coil and two receiving coils. Two receiving coils are orthogonally placed in the centre of the excitation coil where the magnetic field is measured. It is found that the change of the x component and the peak value of the z component of the magnetic field when the sensor probe rotates around a crack follows a sine wave shape. A customised accelerated finite element method solver programmed in MATLAB is adopted to simulate the performance of the designed sensor probe which can significantly improve the computation efficiency due to the small crack perturbation. The experiments have also been carried out to validate the simulations. It is found that the ratio between the z and x components of the magnetic field remains stable under various rotation angles. It shows the potential to estimate the depth of the crack from the ratio detected by combining the magnetic fields from both receiving coils (i.e., the x and z components of the magnetic field) using the rotated ACFM technique.


Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3998
Author(s):  
Mohammed M. Rahman ◽  
M. M. Alam ◽  
Sulaiman Y. M. Alfaifi ◽  
Abdullah M. Asiri ◽  
Meser M. Ali

In this research study, we developed a voltammetric electrochemical sensor probe with a copolymer Nafion (Sulfonated Tetrafluoroethylene-based Fluoro-polymer) decorated with hydrothermally prepared sandwich-type CuO/ZnO nanospikes (NSs) onto a glassy carbon electrode (GCE) for reliable thiourea (TU) detection. The detailed characterizations in terms of structural morphology, binding energy, elemental compositions, grain size and crystallinity for synthesized NSs were performed by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis, respectively. The differential pulse voltammetric (DPV) analysis for TU showed good linearity at current-versus-TU concentration on the calibration plot in the 0.15~1.20 mM range, which is defined as a dynamic detection range (LDR) of TU in a phosphate buffer solution. Considering the slope of LDR over the GCE-coated NSs surface area (0.0316 cm2), the TU sensor sensitivity (0.4122 µA µM−1 cm−2) was obtained. Besides this, the low limit (LOD) for TU detection was calculated and found to be 23.03 ± 1.15 µM. The fabricated Nafion/CuO/ZnO NSs/GCE sensor probe was created as a reliable sensor based on reproducibility, interference effect, stability and response time. Real bio-samples were investigated and the results confirm the anticipated reliability of the TU sensor probe. Thus, this is a noble way to develop enzyme-free electrochemical sensors that could be an alternative approach for the detection of chemicals in the field of enzyme-free biosensor development technology.


Author(s):  
Md Abdus Subhan ◽  
Pallab Chandra Saha ◽  
M.M. Alam ◽  
Abdullah M. Asiri ◽  
Topu Raihan ◽  
...  
Keyword(s):  

2021 ◽  
pp. 138-141
Author(s):  
B. A. Hovhannisyan

Using a special sensor (probe antenna-applicator), radio signals emitted by the human brain are recorded. The changes of different parameters are investigated while studying different physical and emotional states of people. The studies are carried out using spectral and bispectral analysis in the LabVIEW environment. It is shown that in a stressful state the bispectrum of the brain’s radio signal is significantly enriched, and many phase coupled spectral components appear. They undergo changes in their amplitude and frequency. The results of these studies may be useful for understanding the nature and identification of fast processes in the human brain.


Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3379
Author(s):  
Mohammed Muzibur Rahman ◽  
S. Y. Alfaifi

Herein, a novel copper-doped gadolinium oxide (Cu-doped Gd2O3; CGO) nanofiber was synthesized by a simple solution method in the basic phase and successfully characterized. We have used Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Energy-Dispersive Spectroscopy (EDS) techniques for characterization of the CGO nanofiber. The CGO nanofiber was used later to modify Au-coated μ-Chips with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) polymer mixtures (coating binder) to selectively detect 4-cyanophenol (4-CP) in an aqueous medium. Notable sensing performance was achieved with excellent sensitivity (2.4214 µAµM−1 cm−2), fast response time (~12 s), wide linear dynamic range (LDR = 1.0 nM–1.0 mM: R2 = 0.9992), ultra-low detection limit (LoD; 1.3 ± 0.1 pM at S/N = 3), limit of quantification (LoQ; 4.33 pM), and excellent reproducibility and repeatability for CGO/Au/μ-Chip sensor. This CGO modified Au/μ-chip was further applied with appropriate quantification and determination results in real environmental sample analyses.


2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Chunguang Suo ◽  
Ran Wei ◽  
Wenbin Zhang ◽  
Yincheng Li

It is of great significance to accurately provide electric field information for electric power operators and electric power inspection equipment to ensure the safety of live working robots and electric power workers. In this paper, the principle of parallel plate charge induction is used to detect electric field signals and the influence of the inherent capacitance of the parallel plate on the back-end circuit is considered. An equipotential ring is used as the structure of the sensing unit to eliminate the uncertainty generated by the edge electric field. The parameters of the sensor probe are determined by the principle of differential-integration, and its structure is analyzed and designed. The consistency of the designed sensor probe was analyzed, and the results show that the consistency of the sensor is better. We have measured the sensitivity coefficients of the six probes, and the average absolute deviation reached 0.031556. The fits were all above 0.9995. In addition, a three-dimensional power frequency electric field measurement system that is easy to manufacture is designed using the hexahedral structure, which solves the problem of inaccurate electric field measurement caused by the parallel plate probe and the field source being not perpendicular, and the combined field strength formula of nonuniform electric field was obtained. In the laboratory environment, the three-dimensional power frequency electric field measurement system produced in this paper is compared with the electric field simulated by an electric field simulation tool. The test results show that the deviation between the measurement system and simulation is within ±0.55%, the measurement range is 1 kV/m–200 kV/m, the resolution is ≥1 V/m, and the maximum electric field can be measured at 200 kV/m. The nonlinear error is 2.15%, and the sensitivity coefficient is 19.10   mV / kV · m − 1 , which meets the measurement requirements of the power frequency electric field and can be applied to the actual power frequency electric field measurement.


2021 ◽  
Author(s):  
QI CHEN ◽  
Gao Feng ◽  
Wang Zhaokun ◽  
Hai-Long Wang ◽  
Dongning Wang ◽  
...  
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