Analysis of a Nondestructive Evaluation Technique for Defect Characterization in Magnetic Materials Using Local Magnetic Measurements

Table 2

Results of the inverse problem for simulated measurement data obtained from a sample with air gap $\alpha =(\mathrm{0,0.01})\hspace{0.17em}$m. The method using sensitivity equation converges to the exact solution of the inverse problem, corresponding to the absolute minimum of the cost functional. For the perturbation method, the algorithm converges to a value very close to the exact solution.

	Small perturbations			Sensitivity
$I_{\text{set}}$ (A)	${\alpha }_{\min \hspace{0.17em}}$ (m)	${\beta }_{\min \hspace{0.17em}}$ (m)	$F_{\min \hspace{0.17em}}$	${\alpha }_{\min \hspace{0.17em}}$ (m)	${\beta }_{\min \hspace{0.17em}}$ (m)	$F_{\min \hspace{0.17em}}$
3.0	$-$1.141971e-05	0.010018	1.25e-10	$-$2.171692e-11	0.010000	7.33e-22
2.5	$-$4.666539e-06	0.009999	2.94e-11	7.198648e-11	0.009999	3.77e-21
2.0	$-$5.270462e-06	0.010001	3.31e-11	$-$3.852418e-11	0.010000	1.35e-21
1.5	$\mathrm{\hspace{0.17em}\hspace{0.17em}}-$4.527130e-06	0.009999	2.91e-11	2.344620e-11	0.009999	1.43e-21
1.0	$-$1.880308e-06	0.009992	7.57e-11	1.920738e-12	0.010000	6.30e-24
0.5	$-$5.464956e-06	0.010001	3.52e-11	$-$8.964066e-12	0.010000	2.34e-22