Adaptive inversion database for electromagnetic nondestructive evaluation

A novel method is proposed for generating an inversion database, by which the defect reconstruction problem of eddy-current testing can be solved. The database realizes a finite approximation of the forward operator that maps defect configurations to output signals. This approximation is achieved by interpolation on an n-dimensional simplex mesh, where n is the number of defect model parameters considered for the inversion. The inversion can be traced back to a nearest point search. The key element of the method is that the mesh supporting the database is optimized to fit the given testing experiment. On one hand, this feature allows the qualification of the inversion results. On the other hand, the mesh structure of the optimized database provides meta-information about the inverse problem, including the capabilities of the testing experiment and the suitability of the applied defect model among others. Some interpolation and meshing issues are discussed as well, and an application example is presented in the paper.