16 research outputs found

    Ordering of Jobs for Pickling Lines

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    Tato práce řeší problém plánování pohybů jednoho nebo více jeřábů při přesunu produktů mezi vanami mořicí linky. Harmonogramy zpracování jednotlivých produktů ve vanách jsou vytvořeny pomocí modifikované Shifting bottleneck heuristiky, zabraňující střetu produktů ve vanách. Pro prohledávání celého prostoru řešení je použit genetický algoritmus NSGA-II. Nad optimalizační procesem je postavena webová aplikace, která umožňuje správu a prohlížení produktů, částí mořicí linky, historie úloh a konfiguračních parametrů úlohy. Aplikace u úloh menšího rozsahu dosahuje zefektivnění až 30-45 % ve srovnání s naivními harmonogramy operací namáčení. Výsledkem této práce je funkční aplikace, na jejímž základě je možné postavit optimalizační aplikaci v jazyce C++ použitelnou k řešení obdobného problému o větším rozsahu.This work resolves the scheduling problem of multiple hoists transporting products between chemicals baths of pickling line. Harmonograms of products are calculated by modified Shifting bottleneck heuristic, which prevents product conflicts inside baths. Genetic algorithm NSGA-II is used for solution-space search. Web application built over the optimization process allows user to manage/edit products, hoists, baths, configuration parameters and optimization results. Applying proposed heuristic to smaller optimization tasks boosts production effectivity up to 30-45 % (comparing to naive harmonograms). The result of this work is application on the basis of which full-fledged C++ application might be programmed. Then it might be used for solving larger-scale problems.

    Unrelated parallel machine scheduling problem: a cement industry case study

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    Dissertação de mestrado em Engenharia de SistemasThis dissertation considers the problem of scheduling unrelated parallel machines, with unequal release dates and machine eligibility constraints, to minimize the total flow time of the system. It establishes an analogy between this problem and an existing process in the cement industry { the loading of trucks by the customers. Hence, it intends to find opportunities for improvement in the reduction of the customers' interaction times and in their experience inside the cement plants. To achieve this goal, three optimization models are proposed, one exact and two heuristics. Also, an extensive series of computational tests are carried out to compare the performance of the methods. The exact method, based on a mathematical formulation of the problem, requires a high computational time and it is incapable of dealing with large instances. Consequently, it is not a viable solution for an industrial sized problem. However, it contributes to a better understanding of the structure of the problem and to develop efficient heuristics. The heuristics, one based on dispatching rules and the other on a simulated annealing algorithm, show potential for the implementation in a real life scenario. Although simulated annealing gives considerably better solutions than the other heuristic, it takes more time to give results and it is more complex to implement. The dispatching rules based heuristic gives solutions almost instantly and more easily includes certain characteristics of the problem. In general, these methods improve the quality of service provided, reducing the overall time the customers are spending inside the cement plants. Thus, cement industry can and should use optimization models to improve their operations and the customers' experience.Esta dissertação considera o problema de agendamento de máquinas paralelas não relacionadas, com datas de disponibilidades diferentes e restrições de elegibilidade, para minimizar o tempo total de fluxo do sistema. Esta estabelece também uma analogia entre este problema e um processo existente na indústria cimenteira - o carregamento de camiões pelos clientes. Assim, pretende encontrar oportunidades de melhoria na redução dos tempos de interação dos clientes e na sua experiência dentro das cimenteiras. Para atingir este objetivo, três modelos de otimização são propostos, um exato e duas heurísticas. Além disso, uma extensa série de testes computacionais é realizada para comparar o desempenho dos métodos. O método exato, baseado numa formulação matemática do problema, requer bastante tempo computacional e é incapaz de lidar com instâncias grandes. Consequentemente, não é uma solução viável para um problema de tamanho industrial. No entanto, contribui para uma melhor compreensão da estrutura do problema e para desenvolver heurísticas eficientes. As heurísticas, uma baseada em regras de despacho e a outra num algoritmo de simulated annealing, mostram potencial para uma implementação num cenário da vida real. Embora o simulated annealing ofereça soluções consideravelmente melhores do que a outra heurística, este necessita de mais tempo para fornecer resultados e é mais complexo de implementar. A heurística baseada em regras de despacho fornece soluções quase instantaneamente e pode incluir mais facilmente certas características do problema. Em geral, estes métodos melhoram a qualidade do serviço prestado, reduzindo o tempo total que os clientes gastam dentro das cimenteiras. Assim, a indústria cimenteira pode e deve usar modelos de otimização, para melhorar as suas operações e a experiência dos clientes

    Makespan Minimization in Re-entrant Permutation Flow Shops

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    Re-entrant permutation flow shop problems occur in practical applications such as wafer manufacturing, paint shops, mold and die processes and textile industry. A re-entrant material flow means that the production jobs need to visit at least one working station multiple times. A comprehensive review gives an overview of the literature on re-entrant scheduling. The influence of missing operations received just little attention so far and splitting the jobs into sublots was not examined in re-entrant permutation flow shops before. The computational complexity of makespan minimization in re-entrant permutation flow shop problems requires heuristic solution approaches for large problem sizes. The problem provides promising structural properties for the application of a variable neighborhood search because of the repeated processing of jobs on several machines. Furthermore the different characteristics of lot streaming and their impact on the makespan of a schedule are examined in this thesis and the heuristic solution methods are adjusted to manage the problem’s extension

    Sessenta anos de Shop Scheduling : uma revisão sistemática da literatura

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    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

    A Branch and Bound Method for Sum of Completion Permutation Flow Shop

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    We present a new branch and bound algorithm for solving three machine permutation flow shop problem where the optimization criterion is the minimization of sum of completion times of all the jobs. The permutation flow shop problem (F||∑Ci ) belongs to the class of NP-hard problems; finding the optimal solution is thus expected to be highly computational. For each solution our scheme gives an approximation ratio and finds near optimal solutions. Computational results for up to 20 jobs are given for 3 machine flow shop problem when the objective is minimizing the sum of completion times. The thesis also discusses a number of related but easier flow shop problems where polynomial optimization algorithms exist

    Simulated Annealing Approach To Flow Shop Scheduling

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    Flow Shop Scheduling refers to the process of allotting various jobs to the machines given, such that every job starts to process on a machine n only after it has finished processing on machine n-1, with each job having n operations to be performed one per machine. To find a schedule that leads to the optimal utilization of resources, expects the schedule to finish in a minimum span of time, and also satisfy the optimality criterion set for the related scheduling problem is NP-Hard, if n \u3e 2. In this thesis, we have developed an algorithm adopting a heuristic called Simulated Annealing, to act as a support to the Flow Shop Scheduling. This algorithm tries to deliver good/near optimal solutions to the given scheduling problem, in a reasonable time. We also carry out various tests to determine the behavior of the algorithm as well as to evaluate its effectiveness

    Ordonnancement des systèmes de production flexibles soumis à différents types de contraintes de blocage

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    This thesis deals mainly with makespan minimization in Flow-Shop and hybrid Flow-Shop scheduling problems where mixed blocking constraints are considered. In Flow-Shop scheduling problem, a set of N jobs must be executed on a set of M machines. All jobs require the same operation order that must be executed according to the same manufacturing process. Each machine can only execute one job at any time. Pre-emptive operation is not authorized in presented work. In case of hybrid Flow-Shop, at any processing stage k, there exist one or more identical machines Mk. Objective function consists in determining best schedule in order to reduce makespan, i.e. time where all operations are completed.The most common scheduling problem is classical flowshop where buffer space capacity between machines is considered as unlimited. Other problems are characterized by the fact that the storage capacity is limited or null and which generates one blocking constraint. This constraint can be a classical blocking (RSb) or particular blocking (RCb or RCb*). In our works, we present a general case which can be derived from industry and modeled as Flow-Shop and hybrid Flow-Shop systems subject simultaneously to different blocking.To solve these problems, we studied in this thesis complexity of these systems and we proposed exact methods, approached methods and lower bounds.Ce sujet de thèse concerne de manière générale l'évaluation des performances et l'ordonnancement dans des systèmes de production flexibles et principalement les problèmes d'ordonnancement d'atelier de type Flow-Shop et Flow-Shop hybride. Le problème d'ordonnancement d'un Flow-Shop peut être défini ainsi : un ensemble de N jobs composés chacun de M opérations, doivent passer sur M machines dans le même ordre. Une machine peut exécuter une seule opération à la fois, chaque job ne peut avoir qu'une seule opération en cours de réalisation simultanément et la préemption n'est pas autorisée. Dans le cas des Flow-Shops hybrides, Mk machines identiques sont disponibles à chaque étage k en un ou plusieurs exemplaires. Pour cette étude, notre objectif est toujours de minimiser le temps total d'exécution aussi appelé makespan.Les problèmes d'ordonnancement les plus répandus sont de type Flow-Shop classique où les espaces de stockage entre les machines sont considérées comme infinies. D’autres problèmes sont caractérisés par des capacités de stockage limitées ou nulles qui engendre une seule contrainte de blocage. Cette contrainte peut être un blocage classique (de type RSb) ou particulier (de type RCb ou RCb*). Dans nos travaux de recherche, nous présentons un cas général qui peut être tiré de l'industrie et modélisé sous forme de systèmes de type Flow-Shop et Flow-Shop hybride soumis simultanément à plusieurs types de blocage. Pour résoudre ce genre de problèmes, nous avons étudié dans cette thèse la complexité de ces systèmes et nous avons proposé des méthodes exactes, des méthodes approchées ainsi que des bornes inférieures

    Management, Technology and Learning for Individuals, Organisations and Society in Turbulent Environments

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    This book presents the collection of fifty two papers which were presented on the First International Conference on BUSINESS SUSTAINABILITY ’08 - Management, Technology and Learning for Individuals, Organisations and Society in Turbulent Environments, held in Ofir, Portugal, from 25th to 27th of June, 2008. The main motive of the meeting was the growing awareness of the importance of the sustainability issue. This importance had emerged from the growing uncertainty of the market behaviour that leads to the characterization of the market, i.e. environment, as turbulent. Actually, the characterization of the environment as uncertain and turbulent reflects the fact that the traditional technocratic and/or socio-technical approaches cannot effectively and efficiently lead with the present situation. In other words, the rise of the sustainability issue means the quest for new instruments to deal with uncertainty and/or turbulence. The sustainability issue has a complex nature and solutions are sought in a wide range of domains and instruments to achieve and manage it. The domains range from environmental sustainability (referring to natural environment) through organisational and business sustainability towards social sustainability. Concerning the instruments for sustainability, they range from traditional engineering and management methodologies towards “soft” instruments such as knowledge, learning, creativity. The papers in this book address virtually whole sustainability problems space in a greater or lesser extent. However, although the uncertainty and/or turbulence, or in other words the dynamic properties, come from coupling of management, technology, learning, individuals, organisations and society, meaning that everything is at the same time effect and cause, we wanted to put the emphasis on business with the intention to address primarily the companies and their businesses. From this reason, the main title of the book is “Business Sustainability” but with the approach of coupling Management, Technology and Learning for individuals, organisations and society in Turbulent Environments. Concerning the First International Conference on BUSINESS SUSTAINABILITY, its particularity was that it had served primarily as a learning environment in which the papers published in this book were the ground for further individual and collective growth in understanding and perception of sustainability and capacity for building new instruments for business sustainability. In that respect, the methodology of the conference work was basically dialogical, meaning promoting dialog on the papers, but also including formal paper presentations. In this way, the conference presented a rich space for satisfying different authors’ and participants’ needs. Additionally, promoting the widest and global learning environment and participativeness, the Conference Organisation provided the broadcasting over Internet of the Conference sessions, dialogical and formal presentations, for all authors’ and participants’ institutions, as an innovative Conference feature. In these terms, this book could also be understood as a complementary instrument to the Conference authors’ and participants’, but also to the wider readerships’ interested in the sustainability issues. The book brought together 97 authors from 10 countries, namely from Australia, Finland, France, Germany, Ireland, Portugal, Russia, Serbia, Sweden and United Kingdom. The authors “ranged” from senior and renowned scientists to young researchers providing a rich and learning environment. At the end, the editors hope and would like that this book will be useful, meeting the expectation of the authors and wider readership and serving for enhancing the individual and collective learning, and to incentive further scientific development and creation of new papers. Also, the editors would use this opportunity to announce the intention to continue with new editions of the conference and subsequent editions of accompanying books on the subject of BUSINESS SUSTAINABILITY, the second of which is planned for year 2011.info:eu-repo/semantics/publishedVersio
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