Partitioned Search Space Research Articles

Partitioned-cooperative quantum-behaved particle swarm optimization based on multilevel thresholding applied to medical image segmentation

In this paper, in order to search the global optimum solution with a very fast convergence speed across the whole search space, we propose a partitioned and cooperative quantum-behaved particle swarm optimization (SCQPSO) algorithm. The auxiliary swarms and partitioned search space are introduced to increase the population diversity. The cooperative theory is introduced into QPSO algorithm to change the updating mode of the particles in order to guarantee that this algorithm well balances the effectiveness and simplification. Firstly, we explain how this method leads to enhanced population diversity and improved algorithm over previous strategies, and emphasize this algorithm with comparative experiments using five benchmark test functions and five shift complex functions. After that we demonstrate a reasonable application of the proposed algorithm, by showing how it can be used to optimize the parameters for OTSU image segmentation for processing medical images. The results show that the proposed SCQPSO algorithm outperforms than the other improved QPSO in terms of the quality of the solution, and performs better for solving the image segmentation than the QPSO algorithm, the sunCQPSO algorithm, the CCQPSO algorithm.

An Adaptive GA in Partitioned Search Space

Evolutionary algorithms are population based meta-heuristics inspired from natural survival of fittest phenomena.Despite their reasonable performance, these algorithms suffer from some weaknesses including the need for finding the values of their parameters that affect their performance.A new algorithm is proposed that divide the search space into equal sized partitions.Each partition is assigned with two parameters that determine the intensification and diversification rates.The partitions will be intensified or diversified adaptively with regards to the corresponding parameters.Traditional crossover and mutation operators are replaced with two new parameter-free operators.The experiments conducted on a wide range of multi-modal and epistatic problems showed the superiority of the proposed method in comparison to other algorithms in literature.

A multi-swarm PSO using charged particles in a partitioned search space for continuous optimization

Particle swarm optimization (PSO) is characterized by a fast convergence, which can lead the algorithms of this class to stagnate in local optima. In this paper, a variant of the standard PSO algorithm is presented, called PSO-2S, based on several initializations in different zones of the search space, using charged particles. This algorithm uses two kinds of swarms, a main one that gathers the best particles of auxiliary ones, initialized several times. The auxiliary swarms are initialized in different areas, then an electrostatic repulsion heuristic is applied in each area to increase its diversity. We analyse the performance of the proposed approach on a testbed made of unimodal and multimodal test functions with and without coordinate rotation and shift. The Lennard-Jones potential problem is also used. The proposed algorithm is compared to several other PSO algorithms on this benchmark. The obtained results show the efficiency of the proposed algorithm.