Multi-objective Optimization Model for a Green Vehicle Routing Problem

AbstractThe concept of green logistics stems from green economic concepts which are inherently driven by the environmental sustainability challenges. In this work, measures of carbon dioxide (CO2) emission are added to the canonical capacitated vehicle routing problem. The proposed multi-objective optimization model tackles the conflicting objectives of the emission reduction while holding-off the economic cost uplift, leading to a set of Pareto optimal solutions. A biologically inspired Ant Colony Optimization (ACO) based evolutionary constructive heuristic is used to obtain routing plans with minimum financial impact. A Variable Neighborhood Search (VNS) algorithm is designed to obtain low emission routes by exploring the neighborhood of the ant foraging paths. The hybrid ACO-VNS heuristic will provide a set of non-dominated solutions leading to the Pareto optimal solution frontier. For consistency of solutions and solution convergence, the algorithm is tested on randomly generated problem instances

Development of modified discrete particle swarm optimization algorithm for quadratic assignment problems

Particle swarm optimization has been established to be one of the efficient algorithms for finding solutions for continuous optimization problems. The discretized form of particle swarm optimization, known as the discrete particle swarm optimization is an efficient tool for solving combinatorial optimization problems and other problems involving discrete variables. In this paper, a revised version of the discrete particle swarm optimization algorithm is proposed for solving Quadratic Assignment Problems (QAP). Instead of using the general velocity and position update procedures in particle swarm optimization algorithms, four different possible positions are found out for each particle and the best among them is accepted as the updated position. The algorithm is applied to solve some benchmark instances of QAP taken from QAP Library and the results show minute deviations from best-known solutions