Wyniki wyszukiwania - Biblioteka Nauki

1

A Clustering Based Archive Multi Objective Gravitational Search Algorithm

100%

Abbasian M. A. , Nezamabadi-pour H. , Amoozegar M.

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tom Vol. 138, nr 4

387--409

EN

Gravitational search algorithm(GSA) is a recent createdmetaheuristic optimization algorithm with good results in function optimization as well as real world optimization problems. Many real world problems involve multiple (often conflicting) objectives, which should be optimized simultaneously. Therefore, the aim of this paper is to propose a multi-objective version of GSA, namely clustering based archive multi-objective GSA (CA-MOGSA). Proposed method is created based on the Pareto principles. Selected non-dominated solutions are stored in an external archive. To control the size of archive, the solutions with less crowding distance are removed. These strategies guarantee the elitism and diversity as two important features of multi-objective algorithms. The archive is clustered and a cluster is randomly selected for each agent to apply the gravitational force to attract it. The selection of the proper cluster is based on the distance between clusters representatives and population member (the agent). Therefore, suitable trade-off between exploration and exploitation is provided. The experimental results on eight standard benchmark functions reveal that CA-MOGSA is a well-organized multi-objective version of GSA. It is comparable with the state-ofthe- art algorithms including non-dominated sorting genetic algorithm-II (NSGA-II), strength Pareto evolutionary algorithm (SPEA2) and better than multi-objective GSA (MOGSA), time-variant particle swarm optimization (TV-PSO), and non-dominated sorting GSA (NSGSA).

2

Gravitational search optimization approach to improve fuzzy logic speed controller for induction motor drive

86%

Ali J. A. , Hannan M. A. , Mohamed A.

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tom R. 92, nr 8

200--205

EN

Fuzzy logic controller (FLC) is very useful for controlling speed and torque variables in the three-phase induction motor (TIM) operation. However, the conventional FLC has the exhaustive traditional trial and error procedure in obtaining membership functions (MFs). This paper presents an adaptive FLC design technique for TIM using a gravitational search algorithm (GSA) optimization technique. This technique provides the numerical values to limit the error and change in error of the MFs based on the evaluation results of the objective function formulated by the GSA. The root mean square error (RMSE) of the speed response is used as a fitness function. An optimal GSA- based FLC (GSAF) fitness function is also employed to tune and minimize the RMSE for improving the performance of the TIM in terms of changes speed and torque. Space vector pulse width modulation (SVPWM) technique is utilized to generate signals via voltage/frequency control strategy for variable frequency inverter. Results obtained from the GSAF are compared with those obtained through particle swarm optimization (PSO) to validate the developed controller. The robustness of the GSAF is better than that of the PSO controller in all tested cases in terms of damping capability and transient response under different load and speed.

PL

W artykule zaprezentowano adaptacyjny sterownik typu fuzzy logic przeznaczony do trójfazowego silnika indukcyjnego wykorzystujący algorytm optymalizacyjny badania grawitacyjnego. Jako funkcję fitness użyto błąd rms odpowiedzi prędkości. Do zasilania silnika wykorzystano metodę modulacji szerokości impulsu.

3

Development of hybrid performance‑based optimization algorithm for structures equipped with vibration damper devices

72%

Ayyash A. j. N. A. , Hejazi F.

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tom Vol. 23, no. 2

art. no. e123, 2023

EN

Nowadays, various types of vibration damping systems are being implemented in different buildings to diminish seismic effects on structures. However, engineers are faced with the challenging task of developing an optimum design for structures utilizing a proper type of damping device based on new techniques such as the performance-based design method. Therefore, this research was aimed at developing a multi-objective optimization algorithm by hybridizing the particle swarm optimization (PSO) and gravitational search algorithm (GSA) to obtain an optimum design for structures equipped with vibration damper devices based on the performance-based design method. Then, the developed hybrid algorithm (PSOGSA) would be capable of optimizing the damping system simultaneously with the optimized details of the structural sections, including the steel rebars, by satisfying all the design criteria. For this purpose, a special process for the design of structures equipped with vibration damper devices according to the performance-based design method was developed by considering of a wide range of vibration damping systems. The proposed PSOGSA optimization framework was then implemented to design a 12-storey reinforced concrete structure equipped with different types of dampers to minimize the structural weight while satisfying all the prescribed performance-based design acceptance criteria. The results indicated that the proposed optimization method was able to successfully optimize the details of the structural members as well as the type and properties of the damper, which significantly improved the structural response in terms of the formation of plastic hinges and the structural movements.

4

Coordinated design of PSS and TCSC based on Fuzzy controller using global signals

58%

Ghasemi A. , Shayeghi H.

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tom Vol. 98, nr 1

106--120

EN

This paper presents a modified chaotic gravitational search algorithm (CGSA) as a novel heuristic algorithm for coordinate design of fuzzy logic controller-based thyristor controlled series capacitor (FLC-TCSC) and power system stabilizers (PSSs) in multi-machine power system. The coordinate design of PSS and FLC-TCSC damping controllers is converted to a single optimization problem with the time-domain objective function which is solved by the proposed CGSA algorithm which has strong ability for finding the most optimistic results. By minimizing the employed fitness function in which oscillatory characteristics between areas are included, the interactions among the FLC-TCSC controller and PSS under transient conditions in the multi-machine power system are enhanced. The generator speed and the electrical power are chosen as global input signals. The system performance is assessed through the time multiplied absolute value of the error (ITAE), Eigenvalues and figure of demerit (FD) analysis performance indices. The robustness is tested by considering several operating conditions to establish the superior performance with the proposed controller over the other stabilizers.