Direct and inverse electromagnetic methodologies: the proposal of MADEND project for ECT analysis

We present here some original methodologies for the solution of the direct and the inverse problems in Eddy Current Testing (ECT), developed or improved in the framework of the MADEND (Methods and Applications of Non-destructive Electromagnetic Diagnostic) research project partially funded by the Italian Research Ministry. Of the direct methods, the CARIDDI integral formulation has been tailored specifically for ECT problems, and an original discrete geometric approach of magneto-quasistatics has been developed. In order to validate and compare these formulations, a number of experimental benchmarks have been defined and set up with either inner or outer defects. Methods and techniques for the solution of ill-conditioned inverse problems have also been developed, such as a new non-iterative inversion method for electrical resistance tomography, the transformation from a hyperbolic problem into a parabolic problem and innovative approaches to conductivity distribution identification. In addition, an estimation of the reliability of the ECT results has been performed and, to reduce the Probability of False Indication of the reconstruction, a new stochastic approach has been developed.