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  • A review of mathematical programming models for strategic capacity planning in manufacturing

     Martinez Costa, M. Carmen; Mas Machuca, Marta; Benedito Benet, Ernest; Corominas Subias, Albert
    International journal of production economics
    Date of publication: 2014-07
    Journal article

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    This paper offers an up-to-date review on strategic capacity planning in manufacturing companies, with two main objectives: (1) to describe and analyze the strategic capacity planning problems; and (2) to review the mathematical programming models proposed in the literature for dealing with these problems. The main search was conducted in the Web of Science using critical keywords and was complemented by using other search engines. Cross checking of citations of all the articles was also carried out. Papers were selected that have formulated discrete time, finite horizon, multi-period models. The major decisions addressed and the main conditioning factors of the strategic capacity problem in the literature are identified and described. A structured overview of the main strategic capacity planning mathematical programming models is given. A classification of the models is proposed and their main characteristics, solution procedures and industrial applications are identified. Based on the review of the existing studies, a framework for capacity planning is presented, consisting of three main phases: problem definition (considering context, characteristics of the manufacturing system and specific factors that could influence the decision-making process), model design and solution procedure. Closing the paper, some future lines of research are suggested. The review should help both practitioners and academic researchers in developing useful models and processes to aid decision-making in strategic capacity planning.

  • Combining matheuristics and MILP to solve the accessibility windows assembly line balancing problem level 2 (AWALBP-L2)

     Calleja Sanz, Gema; Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    Computers & operations research
    Date of publication: 2014-08-01
    Journal article

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    We propose an approach combining a matheuristic and a MILP model to solve the variant Level 2 of the Accessibility Windows Assembly Line Balancing Problem (AWALBP-L2). This is a novel problem that arises in those real-world assembly lines where, in contrast to the most common ones, the length of the workpieces is larger than the widths of the workstations. This means that, at any time, a workstation cannot access an entire workpiece, but only a restricted portion of a workpiece or two consecutive workpieces. As a result, a workstation can only perform, at any time, the subset of tasks that fall inside its accessible area. The problem is to solve the task assignment and the movement scheme subproblems, while minimizing the cycle time. The proposed solving approach consists of (i) a matheuristic to generate good feasible solutions and compute bounds and (ii) a MILP model that makes use of the obtained bounds. A computational study is carried out to compare the performance of the proposed approach with the existing literature. (C) 2014 Elsevier Ltd. All rights reserved.

    We propose an approach combining a matheuristic and a MILP model to solve the variant Level 2 of the Accessibility Windows Assembly Line Balancing Problem (AWALBP-L2). This is a novel problem that arises in those real-world assembly lines where, in contrast to the most common ones, the length of the workpieces is larger than the widths of the workstations. This means that, at any time, a workstation cannot access an entire workpiece, but only a restricted portion of a workpiece or two consecutive workpieces. As a result, a workstation can only perform, at any time, the subset of tasks that fall inside its accessible area. The problem is to solve the task assignment and the movement scheme subproblems, while minimizing the cycle time. The proposed solving approach consists of (i) a matheuristic to generate good feasible solutions and compute bounds and (ii) a MILP model that makes use of the obtained bounds. A computational study is carried out to compare the performance of the proposed approach with the existing literature. (C) 2014 Elsevier Ltd. All rights reserved.

  • A MILP model for the Accessibility Windows Assembly Line Balancing Problem (AWALBP).

     Calleja Sanz, Gema; Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    International Journal of Production Research
    Date of publication: 2013-06
    Journal article

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    This work studies a novel assembly line balancing problem that has recently appeared in the literature, which we name Accessibility Windows Assembly Line Balancing Problem (AWALBP). AWALBP is a real-world industrial problem that arises in those assembly lines where, as opposed to the most common ones, the length of the workpiece is larger than the widths of the workstation. This means that, at any time, a workstation cannot access one whole workpiece, but only a restricted portion of one or two consecutive workpiece. In our problem the cycle decomposes into stationary stages separated by forward steps, according to a cyclic movement scheme. The aim of this paper is (i) to formalise the AWALBP and its variants, and (ii) to propose a Mixed Integer Linear Programming (MILP) model using two alternative formulations to solve the variant AWALBP-L2. This variant involves solving the task assignment and the movement scheme sub-problems (with the objective of minimising the cycle time). An extensive computational experiment is carried out to study the behaviour of the proposed model for different instance sizes. To the best of our knowledge, this is the first work in the literature which provides optimal solutions for AWALBP-L2. In addition, a set of benchmark instances is provided, which can be further used by the research community.

  • Metaheuristic algorithms hybridized with variable neighbourhood search for solving the response time variability problem

     Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    TOP
    Date of publication: 2013-07
    Journal article

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  • Supply chains: What they are and the new problems they raise

     Corominas Subias, Albert
    International Journal of Production Research
    Date of publication: 2013-11-01
    Journal article

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    The term supply chain has been, perhaps surprisingly, highly successful since it was proposed. This paper discusses the material and theoretical roots from which the concept arises, as well as its content and implications. It focuses especially on the question of whether the term is useful only to, say, put old wine into new wineskins or responds to a very different reality from that we had a few decades ago. The latter poses new problems, some of which are pointed out, whose resolution requires new theoretical and computational tools. The obvious inadequacy of the term to describe the reality it refers to is emphasised. Some challenges, opportunities and switchpoints for the future of the supply chain are listed as well.

  • Resolución del problema de flujo general flexible con fechas comprometidas y costes dependientes del intervalo de realización de las operaciones  Open access

     González Vargas, Néstor Andrés
    Defense's date: 2013-06-28
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    En el marco de la problemática de la programación de operaciones en taller, en esta tesis se introduce un nuevo problema, que se identifica como problema de flujo general flexible (fJSP) con fechas comprometidas y costes dependientes del intervalo de realización de las operaciones. En el fJSP se deben tratar dos subproblemas, el de asignación de las operaciones a las máquinas que pueden ejecutarlas y el de secuenciación de las operaciones en cada una de las máquinas. Para este problemase propone, como función objetivo, minimizar la suma de los costes asociados a los adelantos y retrasos que se generan con respecto a la fecha de entrega comprometida y unos costes dependientes del intervalo de realización de las operaciones. De entre estos últimos se utiliza el coste de la energía necesaria para ejecutar las operaciones de los jobs (tareas) en las máquinas.Para resolver el problema propuesto se plantea un procedimiento dividido en tres pasos. En el Paso 1 se obtiene una secuencia inicial de jobs; en el Paso 2 se genera una solución inicial mediante un procedimiento que se basa principalmente en realizar,simultáneamente, la construcción y búsqueda del camino mínimo en un grafo polietápico para cada job; y en el Paso 3 se emplean procedimientos de mejora de la solución inicial. También se exponen los resultados de la experiencia computacionalque evalúa el procedimiento de resolución propuesto. En los resultados se observa que el procedimiento favorece la programación de las operaciones respetando las fechas de entrega, y ayuda a reducir la factura de la empresa eléctrica, ya queen las soluciones de un conjunto de tipos de ejemplares se observa cómo se asignan, mayoritariamente, operaciones a máquinas con menor consumo de energía, y principalmente en aquellos intervalos de tiempo en los que el coste de la energíaes menor. Al analizar los resultados de la experiencia computacional se observa, además, que el procedimiento encuentra la solución de ejemplares de diferente dimensión en un tiempo de proceso de ordenador razonable.

    En el marco de la problemática de la programación de operaciones en taller, en esta tesis se introduce un nuevo problema, que se identifica como problema de flujo general flexible (fJSP) con fechas comprometidas y costes dependientes del intervalo de realización de las operaciones. En el fJSP se deben tratar dos subproblemas, el de asignación de las operaciones a las máquinas que pueden ejecutarlas y el de secuenciación de las operaciones en cada una de las máquinas. Para este problema se propone, como función objetivo, minimizar la suma de los costes asociados a los adelantos y retrasos que se generan con respecto a la fecha de entrega comprometida y unos costes dependientes del intervalo de realización de las operaciones. De entre estos últimos se utiliza el coste de la energía necesaria para ejecutar las operaciones de los jobs (tareas) en las máquinas. Para resolver el problema propuesto se plantea un procedimiento dividido en tres pasos. En el Paso 1 se obtiene una secuencia inicial de jobs; en el Paso 2 se genera una solución inicial mediante un procedimiento que se basa principalmente en realizar, simultáneamente, la construcción y búsqueda del camino mínimo en un grafo polietápico para cada job; y en el Paso 3 se emplean procedimientos de mejora de la solución inicial. También se exponen los resultados de la experiencia computacional que evalúa el procedimiento de resolución propuesto. En los resultados se observa que el procedimiento favorece la programación de las operaciones respetando las fechas de entrega, y ayuda a reducir la factura de la empresa eléctrica, ya que en las soluciones de un conjunto de tipos de ejemplares se observa cómo se asignan, mayoritariamente, operaciones a máquinas con menor consumo de energía, y principalmente en aquellos intervalos de tiempo en los que el coste de la energía es menor. Al analizar los resultados de la experiencia computacional se observa, además, que el procedimiento encuentra la solución de ejemplares de diferente dimensión en un tiempo de proceso de ordenador razonable

    In the context of the job-shop scheduling problem, this thesis introduces a new problem, which is identified as the flexible job-shop scheduling problem (fJSP) with due dates and energy costs that are dependent on the time interval in which the operations are processed. The fJSP involves two subproblems: that of assigning operations to the machines that can process them and that of sequencing the operations on each of the machines. For this problem, we propose an objective function that minimizes the sum of the costs of earliness and tardiness with respect to the due date and the costs that depend on the time interval in which the operations are processed. Regarding these costs, we have focused primarily on the cost of the energy required to process the jobs on the machines. To solve the proposed problem, we suggest a solution procedure that is divided into three steps. Step 1 involves obtaining an initial sequence of jobs, Step 2 involves generating an initial solution using a procedure based primarily on simultaneously constructing and finding the shortest path in a multistage graph for each job, and Step 3 involves implementing procedures for improving the initial solution. We report the results of the computational experiment used to test the proposed solution procedure. We were able to conclude from the results that the procedure is useful for scheduling operations while respecting due dates and that it could help reduce electricity bills, since the solutions to a set of example types demonstrated that operations were generally assigned to machines with a lower energy consumption, and mainly in time intervals in which the energy costs is low. When analysing the results of the computational experiment, we also observed that the procedure found the solution for examples of varying sizes in a fairly reasonable computer processing time.

  • Task assignment considering cross-training goals and due dates

     Olivella Nadal, Jorge; Corominas Subias, Albert; Pastor Moreno, Rafael
    International Journal of Production Research
    Date of publication: 2013-02-01
    Journal article

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  • Technical note: A systematic procedure based on CALIBRA and the Nelder & Mead algorithm for fine-tuning metaheuristics

     Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    Journal of the Operational Research Society
    Date of publication: 2013-02
    Journal article

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  • A branch and bound algorithm for the response time variability problem

     García Villoria, Alberto; Corominas Subias, Albert; Delorme, Xavier; Dolgui, Alexandre; Kubiak, Wieslaw; Pastor Moreno, Rafael
    Journal of scheduling
    Date of publication: 2013-04
    Journal article

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    The response time variability problem (RTVP) is an NP-hard scheduling problem that has been studied intensively recently and has a wide range of real-world applications in mixed-model assembly lines, multithreaded computer systems, network environments and others. The RTVP arises whenever products, clients or jobs need to be sequenced in order to minimise the variability in the time between two successive points at which they receive the necessary resources. To date, the best exact method for solving this problem is a mixed integer linear programming (MILP) model, which solves to optimality most of instances with up to 40 units to be scheduled in a reasonable amount of time. The goal of this paper is to increase the size of the instances that can be solved to optimality. We have designed an algorithm based on the branch and bound (B&B) technique to take advantage of the particular features of the problem. Our computational experiments show that the B&B algorithm is able to solve larger instances with up to 55 units to optimality in a reasonable time.

    The response time variability problem (RTVP) is an NP-hard scheduling problem that has been studied intensively recently and has a wide range of real-world applications in mixed-model assembly lines, multithreaded computer systems, network environments and others. The RTVP arises whenever products, clients or jobs need to be sequenced in order to minimise the variability in the time between two successive points at which they receive the necessary resources. To date, the best exact method for solving this problem is a mixed integer linear programming (MILP) model, which solves to optimality most of instances with up to 40 units to be scheduled in a reasonable amount of time. The goal of this paper is to increase the size of the instances that can be solved to optimality. We have designed an algorithm based on the branch and bound (B&B) technique to take advantage of the particular features of the problem. Our computational experiments show that the B&B algorithm is able to solve larger instances with up to 55 units to optimality in a reasonable time

  • Optimising the extraction rate of a non-renewable non-durable resource: a mathematical programming approach

     Corominas Subias, Albert; Fossas Colet, Enric
    European Conference on Operational Research
    Presentation's date: 2013-07-01
    Presentation of work at congresses

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  • The experience of the summer school in Optimization and Decision Support Systems for Supply Chains

     Bruno, Giuseppe; Amaro, Ana; Casquilho, Miguel; Corominas Subias, Albert; Genovese, Andrea; García López, Juan-Manuel; Lusa Garcia, Amaia; Magnusson, Johan; Matos, Henrique; Miranda, Joao; Rubio Lacoba, Sergio
    European Conference on Operational Research
    Presentation's date: 2013-07-03
    Presentation of work at congresses

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  • Using tabu search and MILP for the accessibility windows assembly line balancing problem (AWALBP)

     Calleja Sanz, Gema; Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    Congreso Nacional de Estadística e Investigación Operativa
    Presentation's date: 2013-09-12
    Presentation of work at congresses

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    The AWALBP arises in those assembly lines where, in contrast to standard ones, the length of the workpieces is larger than the accessibility windows of the workstations. Because of this, only a limited portion of one or two consecutive workpieces can be reached from each station at any moment. In our problem, the cycle decomposes into stationary stages separated between them by forward steps, according to a cyclic movement scheme. Several procedures were previously proposed to solve the problem to optimality and instances up to a certain size limit were solved. In this study, we propose a tabu search (TS) and a combination procedure using TS and a mixed integer linear programming (MILP) model in order to solve larger instances. The neighborhood search is performed in the space of the movement schemes. Results show that a better solution is obtained in most of the cases that could not be previously solved optimally.

  • Using simulated annealing and MILP for the accessibility windows assembly line balancing problem (AWALBP)

     Calleja Sanz, Gema; Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    European Conference on Operational Research
    Presentation's date: 2013-07-01
    Presentation of work at congresses

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    The AWALBP is an assembly line balancing problem where the length of the workpieces is larger than the width of the workstations. A procedure using a matheuristic and a mixed integer linear programming (MILP) model was previously tested to solve the AWALBP and it succeeded in finding optimal solutions to instances up to a certain size. We propose simulated annealing (SA) and a hybrid procedure using SA and MILP in order to find good quality solutions for larger instances. Results show that a better solution is obtained in most of the cases that could not be previously solved optimally.

  • A detailed workforce planning model including non-linear dependence of capacity on the size of the staff and cash management

     Corominas Subias, Albert; Lusa Garcia, Amaia; Olivella Nadal, Jorge
    European journal of operational research
    Date of publication: 2012-01-01
    Journal article

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  • A manufacturing and remanufacturing aggregate planning model considering a non-linear supply function of recovered products

     Corominas Subias, Albert; Lusa Garcia, Amaia; Olivella Nadal, Jorge
    Production planning and control
    Date of publication: 2012
    Journal article

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  • Cocktail of heuristics for solving hard problems

     Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    Dyna
    Date of publication: 2012-05
    Journal article

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  • Optimal manufacturing policy in a reverse logistic system with dependent stochastic returns and limited capacities

     Benedito Benet, Ernest; Corominas Subias, Albert
    International Journal of Production Research
    Date of publication: 2012-03-02
    Journal article

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    The stochastic models of systems with reverse logistics usually assume that the quantity of products returned is independent of sales. This hypothesis is obviously not true and can lead to suboptimal production policies. In this paper a new sales-dependent returns model is described. In this model, the returns depend on the useful life of the products sold and on the probability of an end-of-life product being returned. A Markov decision problem is formulated in order to obtain the optimal manufacturing policy. A numerical example is provided to illustrate the use of the defined model. An approximated Markov decision model is defined where the optimal policy is easily obtained. The optimal policies of the original and the approximated models are compared.

  • Quant paga l'estudiant?

     Arcas Abella, Oriol; Botella, J.; Corominas Subias, Albert; de la Villa, L.; França, J.; Sacristán Adinolfi, Vera
    Date of publication: 2012
    Book

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  • Heuristics for the response time variability problem

     Corominas Subias, Albert; Kubiak, Wieslaw; Pastor Moreno, Rafael
    European journal of industrial engineering
    Date of publication: 2012
    Journal article

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  • LETRIS: staffing service systems by means of simulation

     Corominas Subias, Albert; Lusa Garcia, Amaia
    Journal of industrial engineering and management (JIEM)
    Date of publication: 2012
    Journal article

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    Purpose: This paper introduces a procedure for solving the staffing problem in a service system (i.e., determining the number of servers for each staffing period). Design/methodology: The proposed algorithm combines the use of queueing theory to find an initial solution with the use of simulation to adjust the number of servers to meet previously specified target non-delay probabilities. The basic idea of the simulation phase of the procedure is to successively fix the number of servers from the first staffing period to the last, without backtracking. Findings: Under the assumptions that the number of servers is not upper-bounded and there are no abandonments and, therefore, no retrials, the procedure converges in a finite number of iterations, regardless of the distributions of arrivals and services, and requires a reasonable amount of computing time. Originality / value: The new procedure proposed in this paper is a systematic, robust way to find a good solution to a relevant problem in the field of service management and it is very easy to implement using no more than commonly accessible tools.

  • Estimating the quality of service of sales in multiplex cinemas using a simulation model

     Ferrer Marti, Laia; Corominas Subias, Albert; Pastor Moreno, Rafael; Malaret, Anna
    International Journal of Modelling in Operations Management
    Date of publication: 2012
    Journal article

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    One key decision for managers of multiplex cinemas is how many box offices to open to avoid overstaffing or poor service. We present a simulation model developed to support the capacity management of the Spanish leader of the multiplex cinema sector; the model uses ad hoc collected data. The user introduces the film schedule, the expected audience and the number of opened box offices and the model gives the expected level of service. The company has tested the model and considers that estimates the waiting time correctly and allows adjusting the open box offices to limit the waiting time without overstaffing.

  • Pure and hybrid metaheuristics for the response time variability problem

     García Villoria, Alberto; Corominas Subias, Albert; Pastor Moreno, Rafael
    Date of publication: 2012-08-16
    Book chapter

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  • Modelo de PLEM mejorado para el Accessibility Windows Assembly Line Balancing Problem (AWALBP)

     Calleja Sanz, Gema; Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    International Conference on Industrial Engineering and Industrial Management. Congreso de Ingeniería de Organización
    Presentation's date: 2012-07-18
    Presentation of work at congresses

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    The Accessibility Windows Assembly Line Balancing Prob-lem (AWALBP) occurs in those assembly lines where the length of the workpiec-es is large relative to the width of the workstations. As a result, each workstation can only access to the limited portion of workpiece(s) that is inside its accessibil-ity window. In previous works we proposed a mixed-integer linear programming (MILP) model and a heuristic decomposition approach to solve AWALBP. Com-putational results revealed the size limits of the instances that could be solved. In this work, we provide an enhanced MILP model using reformulations and addi-tional bound contraints, which significantly improves the percentage of the in-stances optimally solved.

  • Enhanced MILP model for the Accessibility Windows Assembly Line Balancing Problem (AWALBP)

     Calleja Sanz, Gema; Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    Congrès Annuel de la Société Française de Recherche Opérationnelle et d'Aide à la Décision
    Presentation's date: 2012-04-13
    Presentation of work at congresses

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    The Accessibility Windows Assembly Line Balancing Problem (AWALBP) arises in those assembly lines where, as opposed to traditional assembly lines, the dimensions of the workpieces are larger than the width of the workstations. This means that, at any cycle, a workstation cannot access to one whole workpiece, but only to a restricted portion of one or two consecutive workpieces [1]. In our problem the cycle decomposes into stationary stages separated between them by forward steps, according to a cyclic movement scheme.

  • Comparing ways of breaking symmetries in mathematical models for SALBP-1

     Pastor Moreno, Rafael; García Villoria, Alberto; Corominas Subias, Albert
    Assembly automation
    Date of publication: 2011
    Journal article

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  • Hyper-heuristic approaches for the response time variability problem

     García Villoria, Alberto; Salhi, Said; Corominas Subias, Albert; Pastor Moreno, Rafael
    European journal of operational research
    Date of publication: 2011-05-16
    Journal article

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  • Las Encrucijadas estratégicas de la universidad pública española

     Corominas Subias, Albert; Sacristán Adinolfi, Vera
    Revista de educación
    Date of publication: 2011-05
    Journal article

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  • Assessing the impact on optimal production capacities in a closed-loop logistics system of the assumption that returns are stochastically independent of sales

     Benedito Benet, Ernest; Corominas Subias, Albert
    Journal of industrial engineering and management (JIEM)
    Date of publication: 2011
    Journal article

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  • Designing greedy algorithms for the flow-shop problem by means of Empirically Adjusted Greedy Heuristics (EAGH)

     Corominas Subias, Albert; Pastor Moreno, Rafael
    Journal of the Operational Research Society
    Date of publication: 2011-09
    Journal article

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  • Assembly line balancing: general resource-constrained case

     Corominas Subias, Albert; Ferrer Marti, Laia; Pastor Moreno, Rafael
    International Journal of Production Research
    Date of publication: 2011
    Journal article

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  • Optimal production and storage capacities in a system with reverse logistics and periodic demand

     Benedito Benet, Ernest; Corominas Subias, Albert
    International journal of logistics systems and management
    Date of publication: 2011
    Journal article

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  • Single-site strategic capacity planning considering renewal, maintenance, inventory, taxes and cash-flow management

     Benedito Benet, Ernest; Corominas Subias, Albert; Martinez Costa, M. Carmen; Mas Machuca, Marta
    Date: 2011-09-01
    Report

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    In this paper we propose a model of a single-site manufacturing system adressed to deal with the capacity planning from an strategic perspective. The model takes in account relevant business aspects, some of them not found in literature and others only partially considered. The model is formulated as a mixed-integer linear program with an objective function that maximize the after-tax cash balance at the end of the planning horizon. The model could be applied to several sectors especially in manufacturing industry. We present a computational experiment with 1792 business scenarios that test the computing time.

  • Programación de tareas para la obtención de la polivalencia, teniendo en cuenta el aprendizaje y el olvido

     Pastor Moreno, Rafael; Calleja Sanz, Gema; García Villoria, Alberto; Cuatrecasas Arbos, Luis; Corominas Subias, Albert; Olivella Nadal, Jorge
    Participation in a competitive project

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  • Planificación de la capacidad a largo plazo y diseño de la red de suministro

     Coves Moreno, Anna Maria; Mateo Doll, Manuel; Benedito Benet, Ernest; Mas Machuca, Marta; Martinez Costa, M. Carmen; Corominas Subias, Albert; Ribas Vila, Immaculada; Lusa Garcia, Amaia
    Participation in a competitive project

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  • Promoció de sistemes micro-eólics i solars per l'electrificació de comunitats de forma autònoma: anàlisis i desenvolupament d'eines de disseny i planificació per a diferents contextos i paisos II

     Ferrer Marti, Laia; Pastor Moreno, Rafael; García Villoria, Alberto; Corominas Subias, Albert; Villafafila Robles, Roberto; Ranaboldo, Matteo; Domenech Lega, Bruno; Triadó, Joan; Travesset, Oriol
    Participation in a competitive project

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  • Task assignment considering cross-training goals and due dates

     Olivella Nadal, Jorge; Corominas Subias, Albert; Pastor Moreno, Rafael
    International Federation of Operational Research Societies
    Presentation's date: 2011-07-11
    Presentation of work at congresses

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  • Prise en compte des objectifs de polyvalence et des dates d'échéance dans l¿affectation des tâches

     Olivella Nadal, Jorge; Corominas Subias, Albert; Pastor Moreno, Rafael
    Congrès Annuel de la Société Française de Recherche Opérationnelle et d'Aide à la Décision
    Presentation's date: 2011-03-02
    Presentation of work at congresses

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  • Heurísticas para el Visibility Windows Assembly Line Balancing Problem (VWALBP)

     Calleja Sanz, Gema; Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    Congreso de Ingeniería de Organización
    Presentation's date: 2011-09-08
    Presentation of work at congresses

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    En este trabajo se trata el problema conocido como problema de equilibrado de líneas de montaje con ventanas de visibilidad o Visibility Windows Assembly Line Balancing Problem (VWALBP), que ocurre en varios entornos de producción automatizados. En particular este problema surge, por ejemplo, en la producción de placas de circuito impreso (PCIs) en líneas pick&place. Este tipo de líneas consta de varias estaciones en paralelo que montan los componentes en posiciones predefinidas sobre la superficie de la placa. El montaje se realiza de modo cíclico (en cada ciclo se completa una pieza) y consiste en escoger (pick) un componente de un alimentador, trasladarlo hacia la placa, y colocarlo (place) en su posición correspondiente

  • Exact and heuristic approaches for the Visibility Windows Assembly Line Balancing Problem (VWALBP)

     Calleja Sanz, Gema; Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    French National Society of Operations Research and Decision Science
    Presentation's date: 2011-03-04
    Presentation of work at congresses

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    In this paper, we consider the problem that we name Visibility Windows Assembly Line Balancing Problem (VWALBP) [1], which arises in some actual automated production lines. In contrast to traditional assembly lines, the length of the workpieces may be larger than the visibility windows of the workstations, and because of this, only a limited portion of the unit can be reached from any station at any time.

  • Replanning working time under annualised working hours

     Corominas Subias, Albert; Pastor Moreno, Rafael
    International Journal of Production Research
    Date of publication: 2010
    Journal article

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  • A bicriteria integer programming model for the hierarchical workforce scheduling problem

     Pastor Moreno, Rafael; Corominas Subias, Albert
    Journal of modelling in management
    Date of publication: 2010
    Journal article

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  • Optimal manufacturing and remanufacturing capacities of systems with reverse logistics and deterministic uniform demand

     Benedito Benet, Ernest; Corominas Subias, Albert
    Journal of industrial engineering and management (JIEM)
    Date of publication: 2010
    Journal article

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    Using reverse logistics in production systems can help to reduce costs. However, it can also mean introducing a source of uncertainty in the system behavior. In this study we present a method for calculating the optimal manufacturing and remanufacturing capacities of a system with reverse logistics and steady demand taking into account the random behavior of the quantity, quality and timing of units that are collected thru the reverse logistics system. The collected units are remanufactured or disposed of. We also provide an example to illustrate the method.

  • A support tool for working time bargaining by considering individual time accounts and annual leave

     Pastor Moreno, Rafael; Corominas Subias, Albert; Olivella Nadal, Jorge
    Production planning and control
    Date of publication: 2010-01-01
    Journal article

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    Working time accounts (WTAs) are employer-oriented flexibility systems that have been applied in industry but could be used far more. Their use is limited by the complexity of planning them, assessing their financial benefits and establishing suitable compensation for workers. To overcome these drawbacks we define a planning model that takes into account work performance per task per worker, individual annual leave, the use of WTAs and the use of overtime. A four-stage process is proposed: Stage 1 deals with annual leave and the linear consideration of the cost of the lack of capacity; Stage 2 with annual leave and the non-linear consideration of the lack of capacity (but only for the periods during which holidays can be established); Stage 3 with minimising costs (once the holidays selected in Stage 2 are fixed, i.e. the holidays are considered as data) and Stage 4 with minimising capacity slack and excess capacity by minimising costs. A computational experiment based on the different periods of annual leave is used to calculate the financial benefit generated by WTAs in each case and to assess possible compensations for workers.

  • Solving the response time variability problem by means of the cross-entropy method

     García Villoria, Alberto; Corominas Subias, Albert; Pastor Moreno, Rafael
    International journal of manufacturing technology and management
    Date of publication: 2010-05-01
    Journal article

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  • A parametric multi-start algorithm for solving the response time variability problem

     Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    Lecture notes in computer science
    Date of publication: 2010-01-01
    Journal article

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    The Multi-start metaheuristic has been applied straight or hybridized with other metaheuristics to solve a wide range of optimisation problems. Moreover, this metaheuristic is very easy to be adapted and implemented for a wide variety of problems. In this study, we propose a parametric multi-start algorithm that keeps its original simplicity. To test the proposed algorithm, we solve the Response Time Variability Problem (RTVP). The RTVP is a NP-hard sequencing combinatorial optimisation problem that has recently defined in the literature. This problem has a wide range of real-life applications in, for example, manufacturing, hard real-time systems, operating systems and network environment. The RTVP occurs whenever products, clients or jobs need to be sequenced so as to minimise variability in the time between the instants at which they receive the necessary resources. The computational experiment shows the robustness of the proposed multi-start technique.

  • Fine-tuning a parametric Clarke and Wright heuristic by means of EAGH (Empirically Adjusted Greedy Heuristics)

     Corominas Subias, Albert; García Villoria, Alberto; Pastor Moreno, Rafael
    Journal of the Operational Research Society
    Date of publication: 2010
    Journal article

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  • A model for the assignment of a set of tasks when work performance depends on experience of all tasks involved

     Corominas Subias, Albert; Olivella Nadal, Jorge; Pastor Moreno, Rafael
    International journal of production economics
    Date of publication: 2010-08
    Journal article

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  • Sobre el gobierno de las universidades públicas

     Corominas Subias, Albert; Fillet Castella, Sergi; Ras Sabido, Antoni; Sacristán Adinolfi, Vera
    Date of publication: 2010
    Book chapter

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  • Mathematical programming modeling of the Response Time Variability Problem

     Corominas Subias, Albert; Kubiak, W; Pastor Moreno, Rafael
    European journal of operational research
    Date of publication: 2010-01
    Journal article

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  • An entropy-based measurement of working time flexibility

     Olivella Nadal, Jorge; Corominas Subias, Albert; Pastor Moreno, Rafael
    European journal of operational research
    Date of publication: 2010-01
    Journal article

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