This paper presents an original approach for determining the unknown remanent magnetization of a ferromagnetic thin shell by utilizing material sensitivity information. To achieve this, first, the forward problem is formulated in term of the equivalent magnetic charge method for minimizing system unknowns. Then, a material sensitivity formula, which gives the first-order gradient information of an objective function with respect to the magnetic charge, is analytically derived by exploiting the governing integral system equation, augmented objective function, and adjoint variable method. The formula facilitates applying the deterministic approach to searching for an optimal charge distribution and saving computing time for solving an inverse problem in three dimensions as well. The proposed method has been successfully applied to a scale model ship and the results have been validated on a mock-up with real measurements.
This paper presents an experimental technique to accurately separate a permanent magnetic field and an induced one from the total magnetic fields generated by a steel ship, through compensating for the Earth's magnetic field. To achieve this, an Earth's magnetic field simulator was constructed at a non-magnetic laboratory, and the field separation technique was developed, which consisted of five stages. The proposed method was tested with a scaled model ship, and its permanent and induced magnetic fields were successfully extracted from the magnetic field created by the ship. Finally, based on the separated permanent magnetic field data, the permanent magnetization distribution on the hull was predicted by solving an inverse problem. Accordingly, the permanent magnetic fields generated by the ship can easily be calculated at any depth of water.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.