Articolele autorului Gabriel Preda
Link la profilul stiintific al lui Gabriel Preda

Eddy Current Levitation in Ferromagnetic Structures

The efficiency of electromagnetic levitation devices can be improved by shortening the path of the magnetic flux which can be done by employing a magnetic circuit. The eddy currents are computed using an integral equation, and the ferromagnetic materials nonlinearity is treated by applying the polarization fixed point iterative method, with a dynamic overrelaxation technique. To substantially reduce the computation time, the eddy current integral

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Nonlinear Integral Formulation and Neural Network-Based Solution for Reconstruction of Deep Defects With Pulse Eddy Currents

A method for reconstruction of defects buried deep under material surface of conductive nonlinear materials is proposed. Defects are approximated as zero thickness. Simulation of pulse eddy currents is done using an integral FEM method, with a polarization method with over-relaxation to speed up the nonlinear iterations, and a neural network method is used for the reconstruction of defects shape from the simulated signals.

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Comunicat Ad Astra – pozitia fata de premierea de la Salonul de Inventica de la Geneva

http://docs.ad-astra.ro/Comunicat_AdAstra_Geneva.pdf

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Evaluation of magnetic material losses produced by hysteresis and eddy currents

The paper presents a fast method for computing the quasi-stationary electromagnetic field in devices containing both magnetically nonlinear materials and hysteretic materials. The linear iterative procedure of fixed-point type allows the correct evaluation of the local field and of the losses produced by hysteresis and eddy currents. The tests are performed on a single-sheet device used to determine the magnetic material losses under the AC uniform

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Pulse eddy currents using an integral-FEM formulation for cracks detection

Pulse eddy currents are proposed for detection of cracks in structural conductive, non-magnetic parts. The rectangular pulse accounts for a multi-frequency analysis with the lower harmonics pentrating deeper in the material. An integral-FEM method for simulation of transient eddy-currents and model of defects as zero-thickness, two-dimensional flaws are used. Difference signals peak value depends on crack depth and the peak value moment is delayed

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Reconstruction of Magnetization from Magnetic Flux Leakage for Evaluation of Material Degradation
Integral-FEM Eddy Current Solver for Non-Destructive Testing

An Integral-FEM (finite element method) approach is proposed for solution of eddy current problems in Non-Destructive Testing (NDT). Simulation of zero-thickness 2D cracks is possible and large datasets can be simulated with an overall reduced computational effort.

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Integral Formulation and Genetic Algorithms for Defects Geometry Reconstruction Using Pulse Eddy Currents

A method for reconstruction of zero-thickness defects, buried deep under material surface, using pulse eddy currents, is proposed. Both an integral-FEM method for simulation of transient eddy-currents and genetic algorithms, as a model-free inversion technique, are proposed. Numerical results for the inversion of the eddy-currents signals, using genetic algorithms, are shown.

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Sprijiniţi propunere legislativă pentru finanţarea în avans a proiectelor de cercetare !

Senatorul Mihail Hărdău, fost ministru al educaţiei şi cercetării, a înregistrat la Senat o propunere legislativă care vizează creşterea la 90%, de la 30% cât este în prezent, a avansului acordat pentru derularea proiectelor de cercetare finanţate din fonduri publice: https://www.ad-astra.ro/posts/view_post.php?post_id=1133&lang=ro Propunerea a fost iniţial respinsă de Guvern: https://www.ad-astra.ro/posts/view_post.php?post_id=1201&lang=ro

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Polarization Method for Static Fields

An overview of the polarization method is presented. The method can by applied for different regimes of the electromagnetic field as well as for electric circuits. Criteria for the choice of the permeability are proposed, so that the iterative scheme leads to a Picard–Banach fixed point procedure. The errors are evaluated. An efficient overelaxation method is presented. The modality of using FEM numerical method is analyzed in order to ensure the

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