GNGTS 2013 - Atti del 32° Convegno Nazionale

In Fig. 3b some of the horizontal vector (black segments) taken at the top of the sample, and other horizontal vectors collected to a lower height (red segments), are stretched toward the sample centre. With a fair approximation the intersection areas of the black and red segments match, respectively, the top and the bottom end of the iron pin. Comments And Conclusions. Some comments on the whole experiment are mandatory. It must be considered that: the test was carried out at the ST-POLITO office in the Politecnico of Turin, a magnetically noisy environment; the results, according to the acquisition procedure we made up, do not represent the magnetic field around the sample. However the intensity of the anomaly and the vicinity of the sensor to the anomalous body concurred to the promising results of the test. On the side of the acquisition, a set of measurements with two triaxial sensors radially separated, in order to acquire a radial gradient, has been already done always with the rotation of the sample and a static sensor. A configuration with four sensor able to measure the gradient tensor is planned as well as measurements with the sensor moved around the sample. On the site of data interpretation we are currently working at finding algorithms for data inversion. Finally it seems reasonable, giving the raw data imaging obtained, to confirm the feasibility of sizing and locating iron restoration pins within statue, with satisfying approximation, by static magnetic field anomaly measurements. Acknowledgements. The Authors would like to thank Mr. Diego Franco form DIATI for his patient work during data acquisition. ST-Microelectronics is acknowledged for providing the MEMS sensors and the data acquisition circuitry. References L. Binda, A. Saisi, 2009, application of NDTs to the diagnosis of historic structures, NDTCE’09, Non Destructive Testing in Civil Engineering, Nantes, 28 pp. P.L. Cosentino, P. Capizzi, R. Martorana, P. Messina, S. Schiavone, 2011, From geophysics to microgeophysics for engineering and cultural heritage, International Journal of Geophysics, 8pp. doi:10.1155/2011/428412. R. Grimberg, 2009, Electromagnetic non destructive evaluation: present and future. Keynote lecture at 10 th International Conference of the Slovenian Society for Non Destructive Testing, Ljubljana, Slovenia, 267-284 K. Jain, K. Tej Singh, O.P. Agrawal, 1988, Corrosion of iron dowels and clamps in the deterioration of monuments. In Ciabach, J., ed., 6 th International Congress on the Deterioration and Conservation of Stone (Torum, Poland: Nicholas Copernicus University), 116–124. R.A. Livingston, 2001, Nondestructive testing of historic structures. Archives and Museum Informatics, 13, 249-271. D.Vaccaneo, L. Sambuelli, P. Marini, R. Tascone, R. Orta, 2004, Measurement system of complex permittivity of ornamental rocks in L-frequency band. IEEE Transaction on Geoscience and Remote Sensing, 2490-2498. Fig. 3 – Two of the most meaningful representation of the results. The total field vectors (a) and the top side view of all the measured horizontal component (b) plotted at each scanning height and angle. 172 GNGTS 2013 S essione 3.2