The power generation, using hydrokinetic turbine, has been significantly studied in recent years. Such importance is due to the use of clean energy source with low environmental impact. That kind of technology converts the kinetic energy transported by marine and fluvial currents into mechanical energy and, consequently in electrical energy. Therefore, this work presents a methodology for the efficient design of small horizontal axis hydrokinetic turbines with variable rotation. The approach uses the dynamic equation of the power train, taking into account the Blade Element Method (BEM) for determining the power coefficient of the turbine, which is coupled with the model of the drive line of the system, including the multiplier and the electric generator. Thus, the modeling of the whole system comprises the hydrodynamic information of the rotor and the characteristics of the inertia of the system, frictional losses and electromagnetic torque of the generator. The results of numerical simulation are obtained for the transient rotational speed of the rotor and compared with field data measured from small hydrokinetic turbine

Several dynamic projects and fault diagnosis of mechanical structures require the knowledge of the acting external forces. However, the measurement of such forces is often difficult or even impossible; in such cases, an inverse problem must be solved. This paper proposes a force identification method that uses the response surface methodology (RSM) based on central composite design (CCD) in conjunction with a random forest regression algorithm. The procedure initially required the finite element modal model of the forced structure. Harmonic analyses were then performed with varied parameters of forces, and RSM generated a dataset containing the values of amplitude, frequency, location of forces, and vibration acceleration at several points of the structure. The dataset was used for training and testing a random forest regression model for the prediction of any location, amplitude, and frequency of the force to be identified with information on only the vibration acquisition at certain points of the structure. Numerical results showed excellent accuracy in identifying the force applied to the structure.