جستجوی مقالات مرتبط با کلیدواژه « amp » در نشریات گروه « برق »

One approach to improve the aerodynamic performance of airfoils and hydrofoils is inject a small amount of energy to the system (such as fluid injection or suction on the surface), to change the lift and drag. In fact, surface suction and blowing of the fluid can improve the pressure distribution and velocity gradient on the airfoil/hydrofoil surfaces and modify the flow separation point. Therefore, in this study the hydrodynamic behavior of turbulent flows over an airfoil exposed to the injection and suction of fluid in a part of its upper surface is discussed. Firstly, the behavior of the airfoil under one position of the injection or suction and then under two positions of injection or suction are investigated. In this simulation, the FLUENT software is used. The aim of this study is to investigate the effect of the power, the number, the position and the angle of blowing or suction on the hydrodynamic performance of the airfoil. The most important results are the reduction of 10 to 50 percent of the drag and the increase of 5 to 10 percent of the lift (for the blowing) and the reduction of 5 to 30 percent of the drag and the increase of 5 to 10 percent of the lift (for the suction) by considering two positions of injection in comparison to one position.

Assembly flow shop production system includes two stages. In the first stage that is usually assumed one station with some parallel machines, the parts are processed. The second stage is an assembly station (or line) to assemble the parts and complete the products. Suppose that a number of products of different kinds are ordered to be produced and each product needs a set of several parts to complete. Some of the parts are common and some others are unique for each product. Therefore it is important to study the setup times and batch production. The aim is to schedule the parts for process and the products for assembly with the minimum complete time objective. Literature review shows that the considered problem is a NP-Hard problem, so the problem characteristics and its parameters are defined and then a branch and bound algorithm is introduced to solve the small and mediocre problems. Some lower bounds and upper bounds are improved to increase the algorithm efficiency. Finally, a variety of problem is designed and performance of the proposed algorithm is evaluated in solving this problems.

Lack of national budgets, high capital cost of infrastructure projects in power transmission grid and associated risks are among serious complications for transmission system expansion. A fundamental solution to overcoming these difficulties is attracting private sector capital to finance these projects. However private sector participation requires a certain level of profitability and risk management. In this paper a framework for attracting merchant investment to finance power projects has been proposed which can be adapted in other energy infrastructure systems. In the proposed algorithm, maximizing merchant investment is formulated as an objective function in the process of transmission expansion planning problem .The objective functions and constraints such as minimizing the construction cost of transmission lines, minimizing congestion costs, maximizing absorbed private investment and investment risks are used for problem modeling. The scenario analysis is used for modeling uncertainties; the NSGA II algorithm is used to obtain pareto-optimal solutions and the fuzzy satisfying method is used to choose the best solution. Final results are shown on the IEEE 24Bus reliability test system. With the proposed method the system planner can be assured about maximized merchant investment and also the profitability and risk hedging could be guaranteed for private sector investors.