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In this paper, a new method based on Pareto Simplex Search (PSS) 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. We solve this problem through using a mathematically efficient algorithm and in all transferring phases, considering transfer orbits to intermediate orbits; it is supposed that the orbital maneuver control unit has continuous performance characteristics. The system governing equations representing the two body system of a spacecraft and primary gravitational source and thrust force applying to spacecraft, are defined in a nonlinear form. In this systematic approach we incorporate system dynamics as the problem constraints, and both minimum-time and fuel consumption 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.

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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.

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Gravitational search algorithm (for the first time) has been used for two-objective optimization of airfoil shape, in this article. 2D compressible Navier-Stokes equations with Spalart-Allmaras model has been used to simulate viscous and turbulent flow. First, efficiency and accuracy of the optimizer sets have been evaluated using inverse optimization. Objective functions were differences between drag and lift with their corresponding values of the NACA0012 objective airfoil, as a set of airfoils randomly were chosen as starter airfoils, in this case and the aim was to obtain the airfoils that satisfy the considered objective functions. In direct optimization, gravitational search algorithm that has been used in the present work, has achieved proper parameters (related to the Parsec method) and consequently has found optimized airfoils with maximum lift and minimum drag objective functions. This algorithm starts to slove using a set of airfoils and it is directed towards the airfoils that provide the mentioned objective functions. Comparison of the results (Pareto fronts) shows better and more proper performance of the gravitational search algorithm rather than particle swarm optimization algorithm and former researches (done using other meta-heuristic algorithms) for aerodynamic optimizations.

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Iran is located in the warm and dry region of the Middle East, where summer temperature ranges from 35 to 50 0C in the majority of the regions. Some critical factors including hot weather, population growth, and reduction in water resources as a highly impressive factor in the recent decades, all have underlined more efficient use of power plant in Iran, such that the existing power plants must function properly in simultaneous generation. Thus, the current research presents a techno-economic analysis of the function of a combined cycle unit under the condition of conversion into a water and power co-generation system. In the system, both membrane and thermal water sweetener mechanisms are used in parallel. The performance of the system in different conditions of water and power demand has been investigated. The results show that when the Thermal and Revers Osmosi are in the system alone, they can produce about 7,000 and 1,400,000 cubic meters of fresh water per day.Following the modelling of the system, the economic analysis was also performed, and Changes in the price of water sales are shown in each of the water desalination units with increased capacity. Finally, considering the average water sale price as a objective function and combined cycle efficiency as another function, two-objective optimization was performed, and the results are presented in the form of Pareto Graph, which the highest efficiency and lowest sale price are 0.454 and 1.511, respectively

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In recent years, due to the reverse logistics and particularly integration with direct Logistics is considered important in reducing supply chain costs. In this paper, a closed supply chain with multi-objective, multi-product and multi-period is designed. The objective functions consists of minimizing transportation costs between centers and processing cost within centers and centers construction and also the minimization of carbon dioxide is published within centers and carbon dioxide is published of transportation between centers. For this purpose, a mixed integer programming model is used and the problem is NP Hard. This model is superior to previous models,Considering multi-product and multi-period in relevant two objectives and also the relevant model constraints Production carbon dioxide between centers and within centers consideration. In order to integrate the supply chain's two goals the same phase and by multi-objective planning became an object. In order to validate the model and the influence of objective functions Weights several problem is designed and is solved with CPLEX 12.3 and in the end, the results are analyzed.