objective genetic algorithm

In an anechoic chamber, the flat multi-layer sound absorber is cheaper, easier to install and less complicated in manufacturing than conventional wedge and pyramid absorbers. Therefore, design of the optimum flat multi-layer absorber which has minimum thickness is desirable. In this paper, the genetic algorithm has been employed as an effective optimization tool to determine flat triple layer porous absorber. To obtain a broader range of porous materials, combination of foam and fiber types is used. Theoretical and numerical method (finite element method specifically COMSOL Multi-physics version 4.4) have been used to investigate on the operation of sound absorption correspond to the multi-layer structure. In the first step, mathematical model is verified and finite element method, theoretical and experimental results are compared together for two different samples of structures which show appropriate matching. Furthermore to verify the operation of programmed genetic algorithm, the results obtained from the optimization of flat triple layer porous absorber are compared with others that show accuracy and efficiency of this method. The optimization results indicate that a flat triple layer porous structure can achieve results comparable with quality wedge type structure with overall thickness slightly smaller than a fifth of a wavelength at 80 Hz cut-off frequency.

In this paper the creep behavior of a functionally graded (FG) rotating disc made of Aluminum 6061 and Silicon Carbide is investigated and the optimum volume fraction of FG disc and its profile has been obtained. For this purpose, the temperature gradiant along the disc radius is obtained by solving the govering heat transfer differential equation. All the thermal properties of the material are assumed to be the function of temperature and volume fraction. To obtain material properties, two models of Mori-Tanaka and Hashin-Schtrickman are used. To validate the results, they are compared with those given in the literature. Two solution semi-analytical and closed form are employed and the results are compared. The optimum design is carried out with one, and multi-objective methods which are based on genetic algorithm. The objectives are increasing the factor of safety, reducing the weight of the disc and reducing the range between minimum and maximum safety factors. The design variables are percentage of volume fraction, the power of material distribution formula, and the thickness of the disc. The results show that two solution methods compare well. Also, it has been shown that high fraction of Silicon Carbide in the outer side the disc provide optimum results. Also, contradiction of the objectives is reviled, hence the results are presented as Pareto front.

In this paper، multi-objective Genetic Algorithm has been employed to find the communications satellite optimal transfer trajectory from geosynchronous transfer orbit (GTO) to geosynchronous orbit (GEO) as the destination operational zone. Because of satellite high specific impulse، Orbital maneuvers are considered as impulsive maneuvers in this paper and its validation is verified by comparison of results with continues one. Number of intermediate orbits has been found in order to physical constraints. In this systematic approach، both minimum-time and fuel-saving using constant acceleration simultaneously as the problem strategy to find the optimal transfer trajectory between two orbits. Set of optimal trajectories are plotted in Pareto Front and transfer trajectory can be selected from these points. Finally، the results are compared with the results obtained using STK software and good agreement has been revealed. The satellite access to ground station (GS) is analyzed and optimal position for GS is found by defining lack of access and mass consumption as objective functions. Finally، disturbance torques induced by liquid apogee motor (LAM) is investigated and thrusters'' fuel mass for this disturbance torque control is proposed.

This paper deals with dynamic modeling and path planning of a spherical mobile robot. Spherical robot is the prototype of mobile robot used in unknown environments. In this paper, it has five degrees of freedom such that its driver mechanism is 2DOF pendulum moved with two motors. This spherical robot is a non-holonomic and non-linear system. First, the kinematic of the spherical robot is analyzed and next its equations of motion are derived,using the Kane method. For path planning, inverse dynamic of the robot on straight and on circular trajectories are solved. For this, new iterative method, using genetic algorithm for path planning in motion on circular path is used.Finally, the optimal path for achieving minimum power and time of motion are obtained, using multi-objective genetic algorithm. Good agreements were observed between the results of this method and previous computer simulations.