The magnetic charge, which is due to martensite transformation around a crack in ferromagnetic materials, is reconstructed from the magnetic fields measured on a plane above the charge region. It is shown that both Tikhonov method with an appropriate regularization term and iterative regularization based on the CG method solving a modified normal equation yield satisfactory solutions. The regularization parameter for the Tikhonov method can be determined from the L-curve when the noise level is under 10% of measurement data. The residual tolerance of CG iteration, which gives great influence on the solution, can roughly be estimated from the discrepancy principle.
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