Eddy current density by inversion of one measured component of the resulting magnetic field perturbation

2016 ◽  
Vol 52 (1-2) ◽  
pp. 35-40
Author(s):  
Dário Pasadas ◽  
A. Lopes Ribeiro ◽  
Helena Ramos ◽  
Tiago Rocha
Keyword(s):  
Magnetic Field ◽  
Current Density ◽  
Eddy Current ◽  
Field Perturbation ◽  
Eddy Current Density ◽  
Magnetic Field Perturbation

scholarly journals Comparison of Inspecting Non-Ferromagnetic and Ferromagnetic Metals Using Velocity Induced Eddy Current Probe

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3199
Author(s):  
Bo Feng ◽  
Artur Ribeiro ◽  
Tiago Rocha ◽  
Helena Ramos
Keyword(s):  
Magnetic Field ◽  
Eddy Current ◽  
Eddy Currents ◽  
Steel Plate ◽  
Signal Amplitude ◽  
Field Perturbation ◽  
Ferromagnetic Metals ◽  
Eddy Current Density ◽  
Simulation Results ◽  
Magnetic Field Perturbation

A velocity induced eddy current probe has been used to detect cracks in both non-ferromagnetic and ferromagnetic metals. The simulation and experimental results show that this probe can successfully detect cracks in both cases, but further investigation shows that the underlying principles for inspecting non-ferromagnetic and ferromagnetic metals are actually different. For an aluminum plate, the induced eddy current density and the signal amplitude both increase with probe speed, which means the signal is caused by velocity induced eddy currents. For a steel plate, probe speed changes the baselines of the testing signals; however, it has little influence on signal amplitudes. Simulation results show that the signal for cracks in a steel plate is mainly caused by direct magnetic field perturbation rather than velocity induced eddy currents.

Peierls’ substitution via minimal coupling and magnetic pseudo-differential calculus

2019 ◽  
Vol 31 (03) ◽  
pp. 1950008
Author(s):  
Horia D. Cornean ◽  
Viorel Iftimie ◽  
Radu Purice
Keyword(s):  
Magnetic Field ◽  
Differential Calculus ◽  
Spectral Band ◽  
Spatial Decay ◽  
Minimal Coupling ◽  
Field Perturbation ◽  
Wannier Functions ◽  
Weak Magnetic Fields ◽  
The Magnetic Field ◽  
Magnetic Field Perturbation

We revisit the celebrated Peierls–Onsager substitution for weak magnetic fields with no spatial decay conditions. We assume that the non-magnetic [Formula: see text]-periodic Hamiltonian has an isolated spectral band whose Riesz projection has a range which admits a basis generated by [Formula: see text] exponentially localized composite Wannier functions. Then we show that the effective magnetic band Hamiltonian is unitarily equivalent to a Hofstadter-like magnetic matrix living in [Formula: see text]. In addition, if the magnetic field perturbation is slowly variable in space, then the perturbed spectral island is close (in the Hausdorff distance) to the spectrum of a Weyl quantized minimally coupled symbol. This symbol only depends on [Formula: see text] and is [Formula: see text]-periodic; if [Formula: see text], the symbol equals the Bloch eigenvalue itself. In particular, this rigorously formulates a result from 1951 by J. M. Luttinger.

scholarly journals SYNTHESIS OF EDDY CURRENT PROBES WITH VOLUMETRIC STRUCTURE OF THE EXCITATION SYSTEM, IMPLEMENTING HOMOGENEOUS SENSITIVITY IN THE TESTING ZONE

2021 ◽  
Vol 2021 (3) ◽  
pp. 10-18
Author(s):  
V.Ya. Halchenko ◽  
◽  
R.V. Trembovetska ◽  
V.V. Tychkov ◽  
◽  
...  
Keyword(s):  
Neural Networks ◽  
Current Density ◽  
Eddy Current ◽  
Dimensional Structure ◽  
Practical Implementation ◽  
Approximation Technique ◽  
Excitation System ◽  
Simultaneous Application ◽  
Testing Zone ◽  
Eddy Current Density

A method for nonlinear surrogate synthesis of surface eddy current probes with a volumetric structure of the excitation system was proposed. This method a priori provides a given uniform distribution of eddy current density in the testing object area where the measuring coil is located. The implementation of the task using modern metaeuristic stochastic algorithms for finding the global extremum was achieved. For the effective usage of such algorithms, taking into account the effect of velocity, metamodels of eddy current probe were preliminarily created. They were built using a productive approximation technique based on artificial radial-basis neural networks with a Gaussian activation function. Acceptable accuracy of metamodels was achieved due to the simultaneous application of the search area decomposition technologies and plural neural networks based on the techniques of associative machines with group methods for obtaining a solution. For metamodels creation a multidimensional computer experiment design with high homogeneity was used on the basis of the parameterless additive Rd-Kronecker sequence. Numerical experiments to determine the eddy current density distributions which formed by synthesized excitation structures were carried out. The advantages of using a three-dimensional structure excitation system in comparison with classical and planar ones in terms of increasing the width of the testing zone, which is characterized by uniform sensitivity, were shown. Examples of practical implementation of an excitation system with a volumetric structure for an surface eddy current probe are given. References 13, figures 8, table 1.

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