Particle Swarm Optimization (PSO) is an evolutionary algorithm that
emulates the swarm behavior of bird °ocking and ¯sh schooling [17].
In PSO, each swarm member, called a particle or agent, represents a
potential solution. The swarm initially has a population of random
particles (solutions). Each particle adjusts its search direction by
learning from its own experience and the other particles' experiences.
Each particle velocity is updated by following two optimum values.
The ¯rst one is the best solution (¯tness) that has been achieved so
far. This value is called pbest. The second one is the global best value
obtained so far by any particle in the swarm. This best value is called
gbest. Each D-dimensional vector of positions represents a possible
solution [18]. The velocity and position of the dth dimension of the ith