The main goal of the research presented in this paper is to find an analytical solution for an electromagnetic energy harvester with double magnet. A double magnet configuration is defined as a structure in which two magnets, either attracting or repelling, are positioned at a constant distance from each other. Analytical dependencies that govern the shape of electromechanical coupling coefficient curves for various double magnet configurations are provided. In the subsequent step of the analysis, resonance curves for its vibrations and the corresponding recovered energy were determined for the selected dual magnet settings using the harmonic balance method. These characteristics enabled us to ascertain the optimal resistance and estimate the maximum electrical power that can be harvested from the vibrations of the double magnets.

In rotating machineries, misalignment is considered as the second most major cause of failure after unbalance. In this article, model-based multiple fault identification technique is presented to estimate speed-dependent coupling misalignment and bearing dynamic parameters in addition with speed independent residual unbalances. For brevity in analysis, a simple coupled rotor bearing system is considered and analytical approach is used to develop the identification algorithm. Equations of motion ingeneralized co-ordinates are derived with the help of Lagrange’s equation and least squares fitting approach is used to estimate the speed-dependent fault parameters. Present identification algorithm requires independent sets of forced response data which are generated with the help of different sets of trial unbalances. To avoid/suppress the ill-conditioning of regression equation, independent sets of forced response data are obtained by rotating the rotor in clock-wise and counter clock-wise directions, alternatively. Robustness of algorithm is checked for different levels of measurement noise.