Mario Velez-Gallego
Universidad EAFIT, Ingeniería de Producción, Faculty Member
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ABSTRACT A simulated annealing approach is proposed to minimize the makespan on a set of non-identical batch processing machines arranged in parallel. The scheduling problem under study has the following characteristics: arbitrary job... more
ABSTRACT A simulated annealing approach is proposed to minimize the makespan on a set of non-identical batch processing machines arranged in parallel. The scheduling problem under study has the following characteristics: arbitrary job sizes, arbitrary job processing times, and non-identical machine capacities. Each machine can process several jobs simultaneously as a batch as long as the machine capacity is not violated. The batch processing time is equal to the largest processing time among those jobs in the batch. The performance of the proposed solution approach (both in terms of solution quality and run time) are evaluated by solving random problem instances and comparing the results to a solution approach reported in the literature. The experimental study indicates that the proposed solution approach outperforms the existing method.
ABSTRACT In a flow shop with two batch processing machines (BPMs) one of the key objectives is to minimise the makespan. In this study jobs with different sizes were batched together, without exceeding the machine capacity, and processed... more
ABSTRACT In a flow shop with two batch processing machines (BPMs) one of the key objectives is to minimise the makespan. In this study jobs with different sizes were batched together, without exceeding the machine capacity, and processed in the BPMs. Job ready times were also taken into consideration hence, a batch cannot be started unless all the jobs in the batch are ready and available. Also, the batches cannot wait between two machines (i.e., no-wait). The problem under study is NP-hard. A greedy randomised adaptive search procedure (GRASP) algorithm has been developed for this problem. Experiments were conducted to study up to 200 job instances. The solution quality of the GRASP algorithm was compared with the results of a mathematical model developed using CPLEX and a particle swarm optimisation algorithm. The experimental study highlights the advantages, in terms of solution quality of using GRASP to solve large-scale problems.
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ABSTRACT A discrete event simulation--optimization heuristic is presented for configuring a selective pallet rack system. To the rack system under study pallets arrive dynamically over time to be stored for a given period of time. The... more
ABSTRACT A discrete event simulation--optimization heuristic is presented for configuring a selective pallet rack system. To the rack system under study pallets arrive dynamically over time to be stored for a given period of time. The storage duration, arrival time and pallet height are assumed to be continuous random variables with known density functions. In such a system, if there is no available slot in the rack to store an arriving pallet, it is placed on the floor. The proposed heuristic aims at minimizing the number of racking banks needed so that the long term proportion of pallets that are placed in a rack slot reaches a minimum pre-specified value. The computational experiments conducted suggest that the proposed heuristic effectively solves the problem under study.
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ABSTRACT This paper investigates the problem of minimizing makespan on a single batch-processing machine, and the machine can process multiple jobs simultaneously. Each job is characterized by release time, processing time, and job size.... more
ABSTRACT This paper investigates the problem of minimizing makespan on a single batch-processing machine, and the machine can process multiple jobs simultaneously. Each job is characterized by release time, processing time, and job size. We established a mixed integer programming model and proposed a valid lower bound for this problem. By introducing a definition of waste and idle space (WISWIS), this problem is proven to be equivalent to minimizing the WISWIS for the schedule. Since the problem is NP-hard, we proposed a heuristic and an ant colony optimization (ACO) algorithm based on the theorems presented. A candidate list strategy and a new method to construct heuristic information were introduced for the ACO approach to achieve a satisfactory solution in a reasonable computational time. Through extensive computational experiments, appropriate ACO parameter values were chosen and the effectiveness of the proposed algorithms was evaluated by solution quality and run time. The results showed that the ACO algorithm combined with the candidate list was more robust and consistently outperformed genetic algorithm (GA), CPLEX, and the other two heuristics, especially for large job instances.
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La escasa difusión que se les ha dado a las nuevas técnicas de solución de problemas complejos en las áreas de administración de operaciones por parte de universidades y publicaciones no académicas tiene como consecuencia directa que las... more
La escasa difusión que se les ha dado a las nuevas técnicas de solución de problemas complejos en las áreas de administración de operaciones por parte de universidades y publicaciones no académicas tiene como consecuencia directa que las empresas pierdan oportunidades ...
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This paper aims to minimise the makespan of a set of identical batch processing machines in parallel. The batch processing machine can process a batch of jobs as long as the total size of all the jobs in the batch does not exceed its... more
This paper aims to minimise the makespan of a set of identical batch processing machines in parallel. The batch processing machine can process a batch of jobs as long as the total size of all the jobs in the batch does not exceed its capacity. The processing time of the job and its size are given. Batch processing time is equal to the longest processing job in the batch. Two interdependent decisions are required, namely grouping jobs into batches, and scheduling the batches on the machines. The problem under study is NP-hard and hence ...
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Page 1. ORIGINAL ARTICLE A particle swarm optimization algorithm for minimizing makespan of nonidentical parallel batch processing machines Purushothaman Damodaran & Don Asanka Diyadawagamage & Omar Ghrayeb & Mario... more
Page 1. ORIGINAL ARTICLE A particle swarm optimization algorithm for minimizing makespan of nonidentical parallel batch processing machines Purushothaman Damodaran & Don Asanka Diyadawagamage & Omar Ghrayeb & Mario C. Vélez-Gallego ...