A hybrid heuristic for the multi-plant capacitated lot sizing problem with setup carry-over

This paper addresses the capacitated lot sizing problem (CLSP) with a single stage composed of multiple plants, items and periods with setup carry-over among the periods. The CLSP is well studied and many heuristics have been proposed to solve it. Nevertheless, few researches explored the multi-plant capacitated lot sizing problem (MPCLSP), which means that few solution methods were proposed to solve it. Furthermore, to our knowledge, no study of the MPCLSP with setup carry-over was found in the literature. This paper presents a mathematical model and a GRASP (Greedy Randomized Adaptive Search Procedure) with path relinking to the MPCLSP with setup carry-over. This solution method is an extension and adaptation of a previously adopted methodology without the setup carry-over. Computational tests showed that the improvement of the setup carry-over is significant in terms of the solution value with a low increase in computational time.FAPES

A Hybrid Heuristic for the k-medoids Clustering Problem

Clustering is an important tool for data analysis, since it allows the exploration of datasets with no or very little prior information. Its main goal is to group a set of data based on their similarity (dissimilarity). A well known mathematical formulation for clustering is the k-medoids problem. Current versions of k-medoids rely on heuristics, with good results reported in the literature. However, few methods that analyze the quality of the partitions found by the heuristics have been proposed. in this paper, we propose a hybrid Lagrangian heuristic for the k-medoids. We compare the performance of the proposed Lagrangian heuristic with other heuristics for the k-medoids problem found in literature. Experimental results presented that the proposed Lagrangian heuristic outperformed the other algorithms.UNIFESP, Inst Ciencia & Tecnol, BR-12230280 Sao Jose Dos Campos, SP, BrazilUNIFESP, Inst Ciencia & Tecnol, BR-12230280 Sao Jose Dos Campos, SP, BrazilWeb of Scienc

The production planning problem of orders in small foundries

The production planning problem in market-driven foundries consists of determining the alloys to be melted and the items to be produced. A production plan is defined based on the foundry book order that compiles customer requests. Each customer order can be composed of items of different types and made from different alloys. In the literature, production planning does not usually consider the customers’ orders, i.e., items are independently handled. However, in practical situations, several orders cannot be partially delivered. An order can be delivered only when all of its items have been produced, which often results in delays in meeting the customer demands. Conversely, some orders may be split, which would incur delivering costs. This paper addresses the production planning problem of orders in market-driven foundries, which is considered a gap in the literature. A mathematical model and a relax-and-fix heuristic are proposed to address the problem. An experimental evaluation using synthetic datasets and a real dataset compares the proposed methods with the practical policy planning and a state-of-the-art method that solve the production planning problem of items. The results demonstrate the relevance of the production planning of orders

A network flow model for the capacitated lot-sizing problem

The lot-sizing problem considered in this paper consists in planning the production of multiple items on a single machine over a finite planning horizon divided into time periods. The objective of the problem is to determine a minimum cost production plan that meets the forecast demand for the items. The mathematical model considers setup time and setup cost, and is represented as a minimum cost network flow problem. A branch-and-bound method is proposed for solving the model. The performance of the method is evaluated by using numerical experiments for various demand patterns and values of cost parameters.Production planning Lot-sizing Network flows Branch-and-bound Setup time

GRASP heuristic with path-relinking for the multi-plant capacitated lot sizing problem

This paper addresses the independent multi-plant, multi-period, and multi-item capacitated lot sizing problem where transfers between the plants are allowed. This is an NP-hard combinatorial optimization problem and few solution methods have been proposed to solve it. We develop a GRASP (Greedy Randomized Adaptive Search Procedure) heuristic as well as a path-relinking intensification procedure to find cost-effective solutions for this problem. In addition, the proposed heuristics is used to solve some instances of the capacitated lot sizing problem with parallel machines. The results of the computational tests show that the proposed heuristics outperform other heuristics previously described in the literature. The results are confirmed by statistical tests. (C) 2009 Elsevier B.V. All rights reserved.Funda dacao de Amparo A Pesquisa do Estado de Sao Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq, Brazil)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq