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The approaching the ideal efficiency assumption is possible in Stirling engine. Regenerator is the main component in improving the efficiency of the engine. Besides the Geometry and materials of the regenerator, amount and quality of porosity have significant impacts on the regenerator performance which is focused on this research. The main idea of this study is to evaluate the effect of porosity, or unsymmetrical porosity gradient in pressure drop and the thermodynamic performance of regenerator, so three models of regenerator are developed and analyzed: First, a model in which the porosity is constant and do not change (Common mode). In the Second model, the length of regenerator porosity is changed from high to low and in the third model, the length of regenerator porosity is changed from low to high. All versions of models have the same global porosity. Each of these models is separately simulated in Ansys software and validated with experimental results from a laboratory sample.

In this research, an optimal real-time trajectory planning method is proposed for autonomous ground vehicles in case of overtaking a moving obstacle. When an autonomous vehicle detects a moving vehicle ahead of it in a proper speed and distance and the braking is not efficient due to the lost of its kinematic energy, the autonomous vehicle decides to overtake the obstacle by performing a double lane-change maneuver. A two-phase nonlinear optimal problem is developed for generating the path for the overtaking maneuver. The cost function of the first phase is defined in such a way that the vehicle approaches the moving obstacle as close as possible. Besides, the cost function of the second phase is defined as the minimization of the sum of the vehicle lateral deviation from the reference path and the rate of steering angle during the overtaking maneuver while the lateral acceleration of the vehicle does not exceed a safe limit.