In comparison to the traditional solutions, active bearings offer great operating flexibility, ensure better operating conditions over a wider range of rotational speeds and are safe to use. In order to ensure optimum bearing performance a bearing control system is used that adapts different geometries during device operation. The selection of optimal controller parameters requires the use of modern optimization methods that make it possible to quickly achieve the assumed parameters. This article presents the method that has been employed to select the parameters of a proportional integral derivative (PID) controller, in which both stochastic algorithms and hybrid methods have been compared. The results show that all of the used algorithms were able to reach the global optimum but only the hybrid algorithm was repeatable in all runs within a low value of the standard deviation. The best solution will be proposed in the future to control an active foil bearing. Analysing of this paper would help to prevent failures of active foil bearing used in the designed rotating machine.
High frequency combustion instabilities imply a major risk for the solid rocket motor's stable operation and they are directly linked to the response of the solid propellant to the pressure coupling. Our paper aims at defining a linearized onedimensional flow study model of the solid propellant rocket motors' disturbed functioning analysis. Experimental researches were done with an adequate setup, built and improved in our lab, functioning on the basis of the nozzle throat intermittent modulating technique developed by ONERA researchers, able to evaluate the propellant response by the interpretation of the pressure oscillations damping in terms of propellant response.