## Appendix A
### Remament Magnetization in Ceramic Fractures
The measurements are taken in positions at the base (B) and side (s) of each specimen and at equal measured distances \(\mathrm{D_{n}}\) from its edge, on the oriented axial plane xz at the common direction of \(\mathrm{B_{xy}}\) and the \(x\)-sensor, when \(\mathrm{B_{x}}=\mathrm{B_{xy}}>0\) and \(\mathrm{B_{y}}=0\). Since \(\mathrm{D_{n}}<\mathrm{d}=\mathrm{L.tan}\mathrm{\Theta_{B}}\), the heights, \(\ell_{B}\ =\ \frac{D_{\mathrm{n}}}{\sin\theta_{\mathrm{B}}}\
eq\ell_{s}\ =\ \frac{D_{\mathrm{n}}}{\sin\theta_{s}}\), of the magnetically detecting areas and the measured field \(\mathrm{B}\) are increased at the equally-spaced measurement positions at the base and side of each specimen, with increasing distance \(\mathrm{D_{n}}\). * If the directionality of the field is constant throughout the ceramic mass, as the result of its uniform magnetization, then the computed angles at the measurement positions of the base (\(\mathrm{\Theta_{B}}\)) should display similar values. The same must be true for the angles (\(\mathrm{\Theta_{s}}\)) at the specimen sides. * If, in addition, the differently oriented sensors on the surface of the specimens are excited to the same extent, then due to the fact that the same component of the field is measured by the vertical and parallel sensors at the equally-distanced positions, by \(\mathrm{D_{n}}\), on the base and on the side of the specimens, the computed angles \(\mathrm{\Theta_{B}}\), \(\mathrm{\Theta_{s}}\) must be complementary. In this case, the deviations in the value of the sum \(\mathrm{\Theta_{B}}+\mathrm{\Theta_{s}}\approx 90^{\circ}\) can be computed, since they are due solely to the different height, \(\ell_{B}\
eq\ell_{s}\) of the cylindrical magnetically detection areas of the sensors, which change in measurable way. Under the above conditions, the directionality of the magnetic field in the ceramic material mass is tested and the degree of excitation of the vertical and parallel sensors from measurements of the same component of the field is compared (Table 7), at measuring locations equally-spaced from the edges of the specimen, in order to normalize their readings. The results of the measurements in the above table show:  
* The values of the computed angles (Table A7a) at the measurement positions, at the equally spaced positions by \(\mathrm{D_{n}}\), from the base (\(\theta_{\mathrm{B}}\)) and the side (\(\theta_{\mathrm{s}}\)) of the specimen show similar values. The directionality of the field \(\mathbf{B}\) is constant but the degrees of sensor excitation (\(\theta_{\mathrm{B}}+\theta_{\mathrm{s}}\
eq 90^{\mathrm{o}}\)) are different. The parallel sensor (\(\mathrm{B_{xy}}^{//}\),\(\mathrm{B_{z}}^{//}\)) readings, for the measurement of the same component of the field, are approximately double of those of the vertical (\(\mathrm{B_{xy}}^{\perp}\), \(\mathrm{B_{z}}^{\perp}\)) sensor, which displays lower growth rate and range of values for each specimen from the vaes 4, 5 and 6. For the correction of the readings, the ratios \(\lambda_{\mathrm{xy}}=\mathrm{B_{xy}}^{//}\)/\(\mathrm{B_{xy}}^{\perp}\), \(\lambda_{\mathrm{z}}=\mathrm{B_{z}}^{//}\)/\(\mathrm{B_{z}}^{\perp}\) and the average values \(<\!\!\lambda_{\mathrm{xy}}\!\!>\!\!>\!<\!\!\lambda_{\mathrm{z}}\!\!>\!\!=\!\!\lambda \!\!=\!\!2\) are computed. * When, in the equally-distanced measuring positions at the base and side (Table A7b), the magnitude (\(\mathrm{B}^{//}\),\(\mathrm{B}^{\perp}\)) and directionality (\(\theta^{//}\), \(\theta^{\perp}\)) of the field are computed from only the readings of the parallel (\(//\)) or only the vertical (\(\perp\)) sensor, it can be seen that \(\mathrm{B}^{//}\
eq\mathrm{B}^{\perp}\) and \(\theta^{//}\approx\theta^{\perp}\).