Through mechanism analysis of several modified particle swarm optimizations (PSO), a new uniform model of PSO is described, and the convergence is analysed with linear control theory. To improve the calculation efficiency, two enhanced global search capability self-adaptive PSOs, one-population self-adaptive PSO and two-population self-adaptive PSO, are proposed. The one-population self-adaptive PSO uses the diverse coefficients in the first evolutionary strategy. The two-population self-adaptive PSO uses t...