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Ali Rouhani

Publications and source records attributed to Ali Rouhani.

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Benders decomposition approach to solve the capacitated facility location problem

Facility Location (FL) problems as one of the most important problems in operations research aim to determine the location of a set of facilities in a way that the total costs, including costs of opening facilities and transportation costs, are minimized. This study addresses an FL problem in which the capacity of each facility is limited. Because this problem is in the category of np-hard problems, we use the Benders Decomposition (BD) approach to efficiently solve the FL problem. In this paper, we implement the classic BD algorithm and some accelerating BD methods such as Pareto-optimality cut and L-shaped decomposition methods. Furthermore, we propose and implement the hybrid Pareto-L-shaped (PL) method, and evaluate the performance of the implemented algorithms. The results show that the L-shaped decomposition outperforms the other algorithms in terms of time and the number of iteration, while the classic BD converges slowly especially on large scales.

math.OC

A Lagrangian Decomposition Algorithm for Robust Green Transportation Location Problem

In this paper, a green transportation location problem is considered with uncertain demand parameter. Increasing robustness influences the number of trucks for sending goods and products, and consequently, makes the air pollution enhance. In this paper, two green approaches are introduced which demand is the main uncertain parameter in both. These approaches are addressed to provide a trade-off between using available trucks and buying new hybrid trucks for evaluating total costs besides air pollution. Due to growing complexity, a Lagrangian decomposition algorithm is applied to find a tight lower bound for each approach. In this propounded algorithm, the main model is decomposed into master and subproblems to speed up convergence with a tight gap. Finally, the suggested algorithm is compared with commercial solver regarding total cost and computational time. Due to computational results for the proposed approach, the Lagrangian decomposition algorithm is provided a close lower bound in less time against commercial solver.

math.OC