potential
solutions to the problem. Each particle embeds the relevant
information regarding the design variables and associated fitness
values providing an indication of its performance in the objective
space. Each particle flies through the search space and updates its
position based on the best position visited by the particle itself (local
best) and by the best among the neighbors of the particle (global
best). Compared to the other population-based algorithms such as
genetic algorithms, PSO has very few parameters to adjust, which
makes it particularly easy to implement. Nevertheless it has difficulties
in controlling the balance between exploration and exploitation.
Consequently, PSO has disadvantage of premature convergence. It
has been pointed out that PSO may outperform other evolutionary
algorithms in the early iterations; however, its performance may
not be competitive as the number of generations is increased [22].
Therefore several investigations have been undertaken to improve
the performance of standard PSO [19,23].