Improvement of Lagrangian relaxation performance for open pit mines constrained long-term production scheduling problem
来源期刊：中南大学学报(英文版)2014年第7期
论文作者：E. Moosavi J. Gholamnejad M. Ataee-pour E. Khorram
文章页码：2848 - 2856
Key words：constrained long-term production scheduling problem; open pit mine; Lagrangian relaxation; genetic algorithm
Abstract: Constrained long-term production scheduling problem (CLTPSP) of open pit mines has been extensively studied in the past few decades due to its wide application in mining projects and the computational challenges it poses become an NP-hard problem. This problem has major practical significance because the effectiveness of the schedules obtained has strong economical impact for any mining project. Despite of the rapid theoretical and technical advances in this field, heuristics is still the only viable approach for large scale industrial applications. This work presents an approach combining genetic algorithms (GAs) and Lagrangian relaxation (LR) to optimally determine the CLTPSP of open pit mines. GAs are stochastic, parallel search algorithms based on the natural selection and the process of evolution. LR method is known for handling large-scale separable problems; however, the convergence to the optimal solution can be slow. The proposed Lagrangian relaxation and genetic algorithms (LR-GAs) combines genetic algorithms into Lagrangian relaxation method to update the Lagrangian multipliers. This approach leads to improve the performance of Lagrangian relaxation method in solving CLTPSP. Numerical results demonstrate that the LR method using GAs to improve its performance speeding up the convergence. Subsequently, highly near-optimal solution to the CLTPSP can be achieved by the LR-GAs.
E. Moosavi1, J. Gholamnejad2, M. Ataee-pour3, E. Khorram4
(1. Department of Mining Engineering, Tehran Science and Research Branch,
Islamic Azad University, Tehran 14778-93855, Iran;
2. Department of Mining and Metallurgical Engineering, Yazd University, Yazd 89195-741, Iran;
3. Department of Mining and Metallurgical Engineering, Amirkabir University of Technology,
Tehran 15916-34311, Iran;
4. Department of Applied Mathematical and Computer Science, Amirkabir University of Technology,
Tehran 15916-34311, Iran)
Abstract:Constrained long-term production scheduling problem (CLTPSP) of open pit mines has been extensively studied in the past few decades due to its wide application in mining projects and the computational challenges it poses become an NP-hard problem. This problem has major practical significance because the effectiveness of the schedules obtained has strong economical impact for any mining project. Despite of the rapid theoretical and technical advances in this field, heuristics is still the only viable approach for large scale industrial applications. This work presents an approach combining genetic algorithms (GAs) and Lagrangian relaxation (LR) to optimally determine the CLTPSP of open pit mines. GAs are stochastic, parallel search algorithms based on the natural selection and the process of evolution. LR method is known for handling large-scale separable problems; however, the convergence to the optimal solution can be slow. The proposed Lagrangian relaxation and genetic algorithms (LR-GAs) combines genetic algorithms into Lagrangian relaxation method to update the Lagrangian multipliers. This approach leads to improve the performance of Lagrangian relaxation method in solving CLTPSP. Numerical results demonstrate that the LR method using GAs to improve its performance speeding up the convergence. Subsequently, highly near-optimal solution to the CLTPSP can be achieved by the LR-GAs.
Key words:constrained long-term production scheduling problem; open pit mine; Lagrangian relaxation; genetic algorithm
