Synchronous parallelization of Particle Swarm Optimization with digital pheromones

In this paper, Particle Swarm Optimization (PSO) using digital pheromones to coordinate swarms within n-dimensional design spaces in a parallel computing environment is presented. Digital pheromones are models simulating real pheromones emitted by insects for communication to indicate suitable food or nesting location. Particle swarms search the design space with digital pheromones aiding communication within the swarm during an iteration to improve search efficiency. Previous work by the authors demonstrated the capability of digital pheromones within PSO for searching the global optimum with improved accuracy, efficiency and reliability in a single processor computing environment. When multiple swarms explore and exploit the design space in a parallel computing environment, the solution characteristics can be further improved. This premise is investigated through deploying swarms on multiple processors in a distributed memory parallel computing environment. The primary hurdle for the developed algorithm was bandwidth latency due to synchronization across processors, causing the solution duration due to each swarm to be only as fast as the slowest participating processor. However, it has been observed that the speedup and parallel efficiency improved substantially as the dimensionality of the problems increased. The development of the method along with results from six test problems is presented. (C) 2009 Elsevier Ltd. All rights reserved,