Modelling production cost with the effects of learning and forgetting

Defining a dynamic model for calculating production cost is a challenging goal that requires a good fitting ability with real data over time. A novel cost curve is proposed here with the aim of incorporating both the learning and the forgetting phenomenon during both the production phases and the reworking operations. A single-product cost model is thus obtained, and a procedure for fitting the curve with real data is also introduced. Finally, this proposal is validated on a benchmark dataset in terms of mean square error

Single machine scheduling with precedence constraints and positionally dependent processing times

In many real-life situations the processing conditions in scheduling models cannot be viewed as given constants since they vary over time thereby affecting actual durations of jobs. We consider single machine scheduling problems of minimizing the makespan in which the processing time of a job depends on its position (with either cumulative deterioration or exponential learning). It is often found in practice that some products are manufactured in a certain order implied, for example, by technological, marketing or assembly requirements. This can be modeled by imposing precedence constraints on the set of jobs. We consider scheduling models with positional deterioration or learning under precedence constraints that are built up iteratively from the prime partially ordered sets of a bounded width (this class of precedence constraints includes, in particular, seriesparallel precedence constraints). We show that objective functions of the considered problems satisfy the job module property and possess the recursion property. As a result, the problems under consideration are solvable in polynomial time

Aplicação de simulação para análise do makespan devido á inserção e/ou desistência de tarefas no problema de sequeciamento de produção em uma máquina

Orientador : Prof. Dr. Cassius Tadeu ScarpinCoorientador : Prof. Dr. José Eduardo Pécora JúniorDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Métodos Numéricos em Engenharia. Defesa: Curitiba, 17/02/2016Inclui referências : f.75-77Área de concentração: Programação matemáticaResumo: A necessidade de aproximar modelos encontrados na literatura a sistemas dinâmicos tem motivado grande parte das pesquisas recentes. O presente trabalho aborda o problema de sequenciamento de produção em uma única máquina com o objetivo minimizar o instante de término de processamento de todas as tarefas neste sistema produtivo, ou seja, minimizar o makespan. Neste processo, a geração de novos eventos que ocorram durante o sequenciamento representa a aleatoriedade constatada em problemas reais de produção. Os eventos citados podem ser classificados em tarefas a serem reinseridas no processo de acordo com a ocorrência de novos pedidos ou desistência de pedidos por decisão dos clientes. Uma simulação é criada para tal procedimento. Nele, características como quais tarefas serão reavaliadas ao longo do sequenciamento e em que momento as mesmas ocorrem são consideradas dados estocásticos. A partir destas informações, a simulação é aplicada a um modelo de Programação Linear Inteira Mista (MILP) e também a heurísticas, cujos resultados são comparados ao encontrado no modelo exato. Cinco cenários foram criados para tal avaliação: apenas inserções, mais inserções do que desistências, chegadas e saídas de pedidos em uma mesma proporção, mais desistências do que inserções e, por fim, apenas desistências. Os testes computacionais foram implementados em Visual Basic Studio e obtidos pelo software CPLEX. As respostas obtidas mostram que o conjunto de modelos exatos de cada teste gerado, fornece o melhor resultado dentre os métodos propostos para todos os testes realizados. Palavras-Chave: Minimização do makespan. Re-sequenciamento em uma única máquina. Simulação. Inserção e/ou desistência de novos pedidos.Abstract: The need to approximate models found in literature to dynamic systems has motivated a large part of recent researches. This paper addresses the production-scheduling problem on a single machine in order to minimize the total processing time of all tasks in this production system, called makespan. In this process, the generation of events that occur during sequencing, represents the randomness observed in real production problems. The mentioned events can be classified into tasks to be reinserted in the process according to new orders, or withdrawal of requests by customer decision. A simulation is created for such procedure. In it, variables such as which tasks will be reassessed throughout the sequence and at what time they occur are considered stochastic data. From this information, the simulation is applied to a Mixed Integer Linear Programming model (MILP) and some heuristics, whose results are compared to that found in the exact model. Five scenarios were designed for this evaluation: Only inserts, more inserts than withdrawals, arrival and departure of requests in balance, more withdrawals than insertions and, finally, only withdrawals. The computational tests were implemented in Visual Basic Studio and optimized using the CPLEX software. The responses show that the set of the exact models of each generated test provides the best results among the proposed methods for all the tests. Keywords: Makespan minimization. Rescheduling in a Single Machine. Simulation. Insertion and/or withdrawal of new orders

La quantification de la performance dans les entreprises manufacturières : de la déclaration des objectifs à la définition des systèmes d'indicateurs

This work deals with the industrial performance quantification of manufacturing companies. Such a performance is defined with regards to the achievement of an assigned objective. Performance indicators and performance measurement systems are, in the overall and multicriteria context, the methodological tools for providing the performance expressions. A performance expression framework is proposed, based on the quantification of two kinds of performance expressions, respectively the so-called elementary expression and the aggregated expression. The model is structured in accordance with a hierarchical break-down of overall objectives into sub-objective trees. The elementary expression is the result of the comparison of achieved states with the objectives. The aggregated expression is the result of the combination of the expressed elementary performances. Fuzzy subset theory as well as multicriteria decision-aiding tools are used for handling, on the one hand, flexible and imprecise aspects that characterise both industrial objectives and measures; and, on the other hand, a sound aggregation. The MACBETH method is used, being associated with the Integral Choquet operator. This compromise aggregation operator has been chosen because of its ability to take criteria interactions into account. The developed model has been experimented with regards to improvement performance problematics submitted by our industrial partners.Les travaux menés ont été guidés par une volonté de quantifier la performance des activités des entreprises manufacturières. Cette performance se définit au regard de l’atteinte d’un objectif assigné au préalable. Dans un contexte global et multicritère, les indicateurs et systèmes d’indicateurs sont les outils méthodologiques pour retourner les expressions de performance. Un cadre d’expression de la performance est proposé, fondé sur la distinction de deux expressions, l’une élémentaire et l’autre agrégée. La structuration du modèle de quantification repose sur une décomposition d’un objectif dit global en un arbre de sous-objectifs. L’expression élémentaire est définie comme le résultat de la comparaison d’un état atteint avec l’objectif. L’expression agrégée est le résultat de l’agrégation d’un ensemble d’expressions élémentaires. En termes de modélisation, nous avons eu recours à la théorie des sous-ensembles flous pour la prise en compte du caractère flexible des objectifs et de celui imprécis des mesures. Par ailleurs, nous avons utilisé les outils d’aide à la décision multicritère afin de réaliser une agrégation fondée. La méthode MACBETH a été retenue, associée à l’intégrale de Choquet, qui est un opérateur d’agrégation à même de prendre en compte les interactions entre critères. Le modèle proposé a été expérimenté auprès de partenaires industriels, autour de leurs problématiques d’amélioration de la performance

Sessenta anos de Shop Scheduling : uma revisão sistemática da literatura

Orientador : Prof. Dr. Cassius Tadeu ScarpinDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia de Produção. Defesa: Curitiba, 09/02/2017Inclui referências : f. 449-492Resumo: Desde o seminal artigo de Johnson em 1954, a Programação da Produção em Shop Scheduling tem se tornado uma área relevante dentro da Pesquisa Operacional e, atualmente, duzentos trabalhos tangentes à temática são publicados anualmente. Dentre os artigos aqui citados tem-se aqueles que se dedicam à apresentação e síntese do estado da arte desse assunto, intitulados artigos de revisão. Quando tais artigos são elaborados a partir de um conjunto objetivo de critérios, relativos à categorização dos artigos selecionados, tem-se a Revisão Sistemática da Literatura (RSL). O presente trabalho realiza uma RSL em Shop Scheduling, a partir da análise de cada ambiente fabril que o compõe. Fez-se o escrutínio de 560 artigos, à luz de um conjunto de métricas, que constitui a estrutura basilar da proposta de nova taxonomia do Shop Scheduling, complementar à notação de Graham, objetivo fulcral do presente trabalho. Além disso, utilizou-se uma representação em redes dos resultados obtidos em algumas das métricas empregadas, como a característica dos itens, algo outrora inaudito em estudos de revisão desse assunto. Ademais, outro ponto relevante desse estudo repousa na identificação de campos pouco explorados, de modo a colaborar com a pesquisa futura neste tomo. Palavras-chave: Shop Scheduling. Revisão Sistemática da Literatura. Taxonomia. Representação em Redes.Abstract: Since Johnson's seminal article in 1954, Shop Scheduling in Production Scheduling has become a relevant area within Operational Research, and currently hundreds of tangential works on the subject are published annually. Among the articles cited here are those dedicated to the presentation and synthesis of the state of the art of this subject, which are entitled review articles. When these articles are elaborated from an objective set of criteria, regarding the categorization of the selected articles, we have the Systematic Review of Literature (SLR). The present work performs a SLR in Shop Scheduling, based on the analysis of each manufacturing environment that composes it. There were 560 articles scrutinized based on a set of metrics, which is the basic structure of the proposed new Taxonomy of Shop Scheduling, complementary to Graham's notation, the main objective of this work. In addition to that a network representation of the results was obtained in some of the metrics used, such as the job characteristics, something previously unheard of in review studies of this subject. Moreover, another relevant point of this study lies in the identification of less explored fields in order to collaborate with future research in this matter. Keywords: Shop Scheduling. Systematic Literature Review. Taxonomy. Network Representation