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[EN] A Spanish version of the article is provided (see section before references). This paper presents the generation of a plausible data set related to the needs of COVID-19 patients with severe or critical symptoms. Possible illness’ stages were proposed within the context of medical knowledge as of January 2021. The parameters chosen in this data set were customized to fit the population data of the Valencia region (Spain) with approximately 2.5 million inhabitants. They were based on the evolution of the pandemic between September 2020 and March 2021, a period that included two complete waves of the pandemic. Contrary to expectation and despite the European and national transparency laws (BOE-A2013-12887, 2013; European Parliament and Council of the European Union, 2019), the actual COVID-19 pandemic-related data, at least in Spain, took considerable time to be updated and made available (usually a week or more). Moreover, some relevant data necessary to develop and validate hospital bed management models were not publicly accessible. This was either because these data were not collected, because public agencies failed to make them public (despite having them indexed in their databases), the data were processed within indicators and not shown as raw data, or they simply published the data in a format that was difficult to process (e.g., PDF image documents versus CSV tables). Despite the potential of hospital information systems, there were still data that were not adequately captured within these systems. Moreover, the data collected in a hospital depends on the strategies and practices specific to that hospital or health system. This limits the generalization of "real" data, and it encourages working with "realistic" or plausible data that are clean of interactions with local variables or decisions (Gunal, 2012; Marin-Garcia et al., 2020). Besides, one can parameterize the model and define the data structure that would be necessary to run the model without delaying till the real data become available. Conversely, plausible data sets can be generated from publicly available information and, later, when real data become available, the accuracy of the model can be evaluated (Garcia-Sabater and Maheut, 2021). This work opens lines of future research, both theoretical and practical. From a theoretical point of view, it would be interesting to develop machine learning tools that, by analyzing specific data samples in real hospitals, can identify the parameters necessary for the automatic prototyping of generators adapted to each hospital. Regarding the lines of research applied, it is evident that the formalism proposed for the generation of sound patients is not limited to patients affected by SARS-CoV-2 infection. The generation of heterogeneous patients can represent the needs of a specific population and serve as a basis for studying complex health service delivery systems., [ES] En este trabajo se presenta cómo se ha generado un conjunto de datos verosímiles relacionados con las necesidades de pacientes covid-19 con síntomas severe or critical. Se considerarán las etapas posibles con los conocimientos médicos a fecha de enero de 2021. Los parámetros elegidos en este data set están personalizados para adecuarse a los valores poblacionales de la región de Valencia (Spain), unos 2.5 Millones de habitantes y la evolución de la pandemia entre los meses de septiembre 2020 y marzo 2021, un periodo de tiempo que contemple dos olas completas de pandemia.En contra de lo que cabría esperar, a pesar de la ley de transparencia europea y nacional (BOE-A-2013-12887, 2013; Parlamento Europeo y del Consejo de la Unión Europea, 2019), los datos reales relacionados con la pandemia covid-19, al menos en España, tardan mucho en actualizarse y estar disponibles (normalmente una semana o más días). Además, algunos datos relevantes para trabajar los modelos de gestión de camas de hospital no están accesibles públicamente. Bien porque no se hayan recogido esos datos, o porque los organismos públicos no los ofrecen (a pesar de tenerlos indexados en sus bases de datos), o los ofrecen camuflados en indicadores procesados y no muestran los datos en bruto, o simplemente los publican en un formato de difícil reutilización (por ejemplo, en documentos PDF en lugar de en tablas CSV). A pesar de que los sistemas de información de los hospitales son bastante potentes, siguen existiendo datos que ni siquiera están recogidos adecuadamente en el sistema de información de salud.Por otra parte, los datos recogidos en un hospital dependen de las estrategias y practicas propias de ese hospital o sistema de salud. Este efecto limita la generalización de los datos “reales” y es necesario trabajar con datos “realistas” o verosímiles que están limpios de interacciones con variables o decisiones locales (Gunal, 2012; Marin-Garcia et al., 2020). Por un lado, se puede parametrizar el modelo y definir la estructura de datos que sería necesaria para ejecutar el modelo con datos reales. Por otro lado, se pueden generar conjuntos de datos verosímiles a partir de la información pública disponible y, posteriormente, cuando se disponga de los datos reales evaluar la bondad del modelo (Garcia-Sabater & Maheut, 2021).

[EN] One of the problems when conducting research in mathematical programming models for operations planning is having an adequate database of experiments that can be used to verify advances and developments with enough factors to understand different consequences. This paper presents a test bed generator and instances database for a rolling horizons analysis for multiechelon planning, multiproduct with alternatives processes, multistroke, multicapacity with different stochastic demand patterns to be used with a stroke-like bill of materials considering production costs, setup, storage and delays for operations management. From the analysis of the operations planning obtained from this test bed, it is concluded that a product structure with an alternative process obtains the lowest total cost and the highest service level. In addition, decreasing seasonal demand could present a lower total cost than constant demand, but would generate a worse service level. This test bed will allow researchers further investigation so as to verify improvements in forecast methods, rolling horizons parameters, employed software, etc.

[EN] This systematic literature review focuses on planning models jointly addressing location and allocation decisions related to the design of intermodal freight transportation networks. Since this body of literature is evolving quickly, a methodology based on a linked two-stage analysis is proposed. The first stage analyses recent surveys to establish the guidelines and criteria that enable the subsequent systematic review. Then, the review concentrates on analysing contributions to the current state of the art on intermodal freight transportation from two close, yet different research streams: transportation networks and supply chain networks. Key features identified in the first stage such as: 1) the research problem's characteristics; 2) the intermodal networks design's particularities; 3) proposed solution techniques, among others, are used to classify and analyse the different contributions. The review identifies current trends, emerging topics and some issues that merit being researched., This work was supported by the Bolivar Government and CEIBA Foundation (Colombia); and Spanish Ministry of Economy and Competitiveness under research project ECO2015-65874-P.

The rolling horizons procedure is widely used both in industry and in scientific research for the resolution of mathematical programming models. It allows reducing the size of the models to be solved in the times allowed with the available computational capacities. It takes into consideration the closest information with less uncertainty. But programming models can have symmetries, when they have variables that can be permuted without changing the structure of the problem. These symmetries increase the search spaces for possible solutions, increasing the need for computation and presenting alternative solutions with equivalent results in the objective function. The symmetry can generate different solutions with equivalent values in the objective function but that can imply very different results in the long term with the rolling horizons procedure. This paper presents the proposed actions to symmetry break that have been applied to the rolling horizons procedure. The work provides the different proposals identified to break the symmetry.

This paper presents an integrated framework for capacity and operations planning in Spanish sheltered employment centers (SECs). Employment provides socio-economic opportunities for people with disability. Well functioning SECs that provide opportunities for people with and without disability to work alongside each other are an important component of Spain&rsquo, s current labor market. To be economically sustainable, SECs need to satisfy their clients expectations in terms of price, flexibility and performance, whilst taking into account and strengthening the diverse skills and abilities of their workforce like specific learning and forgetting processes. The SEC studied herein, a non-for-profit organization whose mission is to create employment for people with disabilities its workforce is deployed directly on clients&rsquo, premises. Efficient management across this multi-site environment, whilst supporting the diverse employment needs of its staff, is of paramount importance. This paper contributes an integrated framework to support SEC capacity and operations planning, which prioritizes the explicit training needs of workers with disability at all levels (strategic, tactical, and operational) as a lever for achieving the organization&rsquo, s goals.

[EN] This paper addresses the redesign of an industrial assembly facility's internal logistics. To this end, it proposes a mathematical formulation that optimizes the components and parts' flow to feed the different workstations of the production lines. This flow of components starts at the reception docks where suppliers' trucks arrive. Components unloaded from trucks are moved to one or several storage areas by means of adequate handling equipment. Finally, components are transported to demand point located along the assembly line when required. Numerical results produced by the mathematical formulation for the studied plant show that savings of almost 33% in the total distribution time might be achieved by a better assignment of suppliers to reception docks and parts to storage areas, and by adequately choosing the capacity of the material handling equipment., The work described in this paper has been partially supported by the project "Hiperheuristico Lenitivo de la Variabilidad del Entorno Industrial en la Programacion de Produccion del Lote Econonimo GVA/2017/008" by the Conselleria de Educacion, Investigacion, Cultura y Deporte of the Generalitat Valenciana within the Program "Proyectos de I+D+I para grupos de investigacion emergentes". We would like to thank the two anonymous reviewers and the editor for their valuable comments and suggestions.

Purpose: With this work, we intend to promote research on the application of Operations Management tools in order to assist with decision-making in health crisis situations. During the first six weeks of the COVID-19 crisis in Spain, we have contacted a large number of hospital and health department managers in the Valencian Community and other regions of Spain. The result is that very few, at least when contact was made and at the time of writing this article, had consulted staff members in the Operations Management area for advice on this situation, and they are quite reluctant to do so. This is in spite of the fact that some medical sources also consider this crisis to be one of resources, not merely a medical crisis. Our opinion is that Operations Management can make a useful and valuable contribution to anticipate and improve the management of scarce resources, even in times of crisis. If those responsible for public health or heads of hospitals do not see this usefulness, then there is a huge gap between research and practice in Operations Management and what is transmitted to the healthcare sector. Our aim is to help reduce this gap. Design/methodology/approach: In the first part of the article, we will justify that this crisis, besides being a medical crisis, is also a crisis in terms of resources. We will briefly review some of the Operations Management tools that we believe are appropriate for managing this crisis. We will focus on those that we will illustrate in the second part of the article as a practical example of the action research protocol (only the action planning phase), in which we are currently involved. Findings: Due to the peculiarities of the COVID-19 epidemic, it is reasonable to think that the evolution and duration of each outbreak, and the way it is dealt with, will be different in each hospital and/or each health department. Anticipating the number of patients who will require care and forecasting the consumption of resources over time is complex, due to the long and variable incubation times and the uncontrolled evolution of the treatments needed by each patient. Furthermore, since the evolution of new patient admissions is not homogeneous, the forecasting of requirements is difficult. Providing real-time support and detecting with a certain degree of anticipation the potential levels of demand for health care will enable hospitals to define what stages of the contingency plan to apply and how to (re)assign the available resources in the most efficient way possible. Research limitations/implications: Hardly any current data are available, not only publicly, but also through public health ministries and managers; those that are available are not very reliable and come from studies with non-representative samples. For this reason, all forecasts must be taken with a note of caution, and in particular, designing review mechanisms every time a new set of updated reliable data becomes available (something that occurs on a weekly basis). Originality/value: In this work, we will show an example of a proposal for the practical application of Operations Management tools. Our proposal may be useful to hospital managers and public administrators in the healthcare sector (regional ministries or their equivalents). Each health department, hospital or hospital group will generate the aggregate data that facilitate the calculation of needs as input parameters for the model (available and occupied beds, daily admissions, mean lengths of stay in each healing phase and the percent of patients who evolve from one stage to another in the progression of the disease/healing process) and will be able to analyze how the system responds and evaluate different strategies or mitigating actions. These tools have been shown to be useful and reliable in manufacturing and service contexts that show a strong seasonal demand (both occasional and recurring) requiring a great deal of resources. We believe these situations are analogous to those faced by hospitals and the healthcare system in an epidemic like COVID-19. With them, we could facilitate the aggregate planning of resources for hospital administrators in order to provide them operational support during the COVID-19 contingency plan. However, the array of useful tools for this crisis is not limited to those that we will illustrate. Our intent is to encourage the Operations Management academic community to demonstrate how they contribute to the service of society in this COVID-19 epidemic, providing knowledge that can be extrapolated to other similar situations in the future that we may be unfortunate enough to experience.

This paper describes the redesign of the internal logistics of an industrial assembly facility. In particular, we are concerned by the management of components and parts’ flow to feed the different workstations of the production line. This flow of components starts at the reception docks where suppliers’ trucks arrive. Components unloaded from trucks are moved to one or several storage areas by means of adequate handling equipment. Finally, components are transported to demand points located along the production line when required. Internal logistics cause therefore a huge volume of transportation and intensive activities that need to be carefully planned to keep the plant’s performance. To this end, a mathematical model is proposed to redesign the assignment of logistics resources (i.e., docks, storage areas, and handling equipment) in such a way that the total time consumed during de supply process is minimized.

Order-up-to level is one of the most popular inventory management strategies in the retail industry. However, there exist several manners to fix the up-to-level. In this paper, we consider several of these manners and analyze their application to a real retail company. The company requires a method which is simple to understand and adopt and that should seek to minimize stockouts and in-store stock levels. We empirically compare, using real data, several methods to set the order-up-to value and report the performance of the system for each of them. Our results also demonstrate the relevance of two important factors, which are the size of the packaging and the seasonality of demand.

[EN] This paper presents a case study describing a cell assignment problem in an assembly facility. These cells receive parts from external suppliers, and sort and sequence these parts to feed the final assembly line. Therefore, to each cell are associated important inbound and outbound flows generating hundreds of material handling equipment movements along the facility, impacting the traffic density and causing eventually safety issues in the plant. Following an important plant redesign, cells have been relocated, and the plant managers need to decide how to manage the new logistic flows. To that aim, a hybrid approach encompassing mathematical optimization and discrete event simulation (DES) is proposed. This approach allows us to reduce complexity by decomposing the design into two phases. The first phase deals with the problem of generating cell¿s assignment alternatives by using a heuristic method to find good quality solutions. Then, a DES software is used to dynamically evaluate the performance of the solutions with respect to operational features such as traffic congestion and intensity. This second phase provides interesting managerial insights on the manufacturing system from both quantitative and qualitative aspects related to in-plant safety and traffic.

[EN] The definition of lot sizes represents one of the most important decisions in production planning. Lot-sizing turns into an increasingly complex set of decisions that requires efficient solution approaches, in response to the time-consuming exact methods (LP, MIP). This paper aims to propose a Tabu list-based algorithm (TLBA) as an alternative to the Generic Materials and Operations Planning (GMOP) model. The algorithm considers a multi-level, multi-item planning structure. It is initialized using a lot-for-lot (LxL) method and candidate solutions are evaluated through an iterative Material Requirements Planning (MRP) procedure. Three different sizes of test instances are defined and better results are obtained in the large and medium-size problems, with minimum average gaps close to 10.5%., This paper shows the results of the project entitled "Algoritmo heuristico basado en listas tabu para la planificacion de la produccion en sistemas multinivel con listas de materiales alternativas y entornos de coproduccion" supported by Universidad de la Costa and Universitat Politecnica de Valencia.

This chapter is about a successful energy co-operative in Spain. With rising poverty and energy prices among the most expensive in Europe and, the cooperative not only provides a reliable source of clean energy to consumers, but also forms a central part of the community in which it is situated. The case study points to a need for private enterprises to collaborate with local authorities and social services to provide solutions to drastic situations of poverty that are still prevalent, particularly in areas of Southern and Eastern Europe. The Spanish energy cooperative demonstrates one way in which the social economy can help to shape the future of the welfare state in the absence of state funding and in the face of national policies that are not well aligned.

Since the 1990s, the low number of students choosing to study science and technology in higher education has been on the societal agenda and many initiatives have been launched to promote awareness regarding career options. The initiatives particularly focus on increasing enrolment in the engineering programmes. This article describes and compares eight European initiatives that have been established and operated by universities (and in some cases through collaboration with other actors in society). Each initiative is summarised in a short essay that discusses motivation, organisation, pedagogical approach, and activities. The initiatives are characterised by comparing the driving forces behind their creation, how the initiative activities relate to the activities at the university, size based on the number of participants and cost per participant and pedagogical framework. There seem to be two main tracks for building outreach activities, one where outreach activities are based on the university’s normal activities, and one where outreach activities are designed specifically for the visiting students.

[EN] This work illustrates the application of novel simulation architecture with two case studies where the proposed architecture, the so-called 4-layer, allowed us to address the complexity of the analysed systems. The fundamental objective of this work is to show the structure of layers, how layers interact with one another and with the user, and what benefits this separation proposes. The first case study deals with moving car bodies from the paint plant to the assembly line through a sequencing system that involves distributed decision-making processes in an ASRS. The second case study focuses on analysing a layout of a section used to assemble the engine and transmission set, where the quality of the material flow is evaluated. The work highlights some of the advantages of modelling with 4-layer architecture, and explains the key processes that connect different elements

[ES] Este trabajo analiza el comportamiento de varias estrategias de producción para el problema de secuenciación del lote económico, ELSP, en función del entorno de complejidad e incertidumbre en el que se emplean. Se estudia el rendimiento de varias heurísticas diseñadas para el problema ELSP clásico, analizando el comportamiento del coste total bajo diferentes escenarios en función del número de artículos y el nivel de utilización. Los resultados del estudio de simulación indican que existe una clara dependencia del rendimiento de las estrategias, y por tanto de la idoneidad de su uso, en relación con el entorno productivo. Se demuestra también que la variación del rendimiento no sigue el mismo patrón para cada estrategia, lo que refuerza la importancia de este estudio en el proceso de diseño de estrategias de producción para el ELSP., [EN] This study analyzes the behavior of various production strategies for the economic lot scheduling problem (ELSP), depending on the context of complexity and uncertainty in which they are used. The performance of various heuristics designed for the classical ELSP problem is analyzed. The influence of number of items and utilization on total cost under different scenarios is considered. The simulation results show a direct dependence of the production environment on the performance of the strategies, and thus their suitability to that particular environment. It is also proven that the variation in performance does not follow the same pattern for each strategy, which reinforces the significance of this study in the process of designing a production strategy for the ELSP.

[EN] This study analyzes the behavior of various production strategies for the ELSP, depending on the context of complexity and uncertainty in which they are used. We analyzed the performance of various heuristics designed for the classical ELSP problem.We evaluated total cost in different scenarios with respect to the number of items and the utilization level. The simulation results show a direct relationship between the performance of the strategies, and therefore their suitability, and the production environment. Furthermore, we have proven that the variation in performance does not follow the same pattern for each strategy, which reinforces the significance of this study in the process of designing a production strategy for the ELSP, [ES] Este trabajo analiza el comportamiento de varias estrategias de resolución para el ELSP en función del entorno de complejidad e incertidumbre en el que se emplean. Hemos analizado el rendimiento de varias heurísticas básicas para el problema ELSP clásico. Consideramos el comportamiento del coste en diferentes escenarios con respecto al número de artículos y el nivel de utilización. El resultado de la simulación indica que existe una clara dependencia del rendimiento de las estrategias, y por tanto de la idoneidad de su uso, en relación con las características del problema. Además, demostramos que la variación del rendimiento no sigue el mismo patrón para cada heurística, lo que refuerza la importancia de este estudio en el proceso de diseño de una estrategia de producción

[EN] Mixed-model assembly lines are used at the automotive industry to obtain more efficient production flows. The sequencing of the different units is done at the very beginning of the process, but frequently large perturbations of the original sequence can be observed. These perturbations might be intended or not but to some extent, a resequencing process –to create a new sequence with the available units- is necessary. This paper focuses in the re-sequencing process by using parallel buffering lines (known as mix banks). Algorithms to decide the line of destination of incoming units and the line of extraction of units to the line are presented and evaluated. The algorithms and their performance have been verified using discrete event simulation software (SIMIO). An analysis considering different operations situations is done and some recommendations to real case users are presented., [ES] En la industria del automóvil se utilizan líneas mixtas de montaje de modelos para obtener flujos de producción más eficientes. Aunque la secuencia de los productos en la línea se contempla en el comienzo del proceso, se suelen producir perturbaciones en la secuencia de producción. En ocasiones es necesaria una resecuenciación entendida como la creación de una nueva secuencia. Este trabajo se centra en la resecuenciación mediante el uso de líneas paralelas de almacenamiento (conocidas como mix-bank). Se proponen algoritmos para decidir en qué línea se debe introducir y de qué línea se debe extraer. Los algoritmos son verificados mediante modelos de simulación implementados en SIMIO. Se realiza un análisis para diferentes factores operacionales y se proponen reglas de gestión para su uso en casos reales., The work described in this paper has been supported by the project "CORSARI MAGIC DPI2010-18243" by the Ministerio de Ciencia e Innovación del Gobierno de España within the Program de "Proyectos de Investigación Fundamental No Orientada". This paper also has been written with financial support from the Project “Path Dependence y toma de decisiones para selección de herramientas y prácticas de Lean Manufacturing” (PAID-06-12-SP20120717) of the Universitat Politècnica de València.

The purpose of this paper is to analyse the design of an activity based on wiki technology in a Higher Education environment, specifically in engineering studies. The issues proposed here are based on the previous experience of the authors by developing a wiki activity in the field of industrial engineering. Wiki is considered a type of Web 2.0 technology that enables users to work together on the Web. The research literature reports a number of experiences with wiki-based collaborative writing in education. However, to enable all the advantages as far as possible, a clear specific description of the activity is mandatory for both students and teachers. This work confers guidelines as to how wikis will be developed and evaluated. Regarding developing wikis, the content of this task is specified in collaboration with the instructor. Regarding assessments, the quality of the wikipage and possible competences developed should be considered. The methodological design presented herein intends to act as a basis for the wiki-based collaborative writing approach. In addition, a list of assessment indicators that can be the basis for a future research line related to an automated tool for evaluating wiki is provided.

This work presents the case of Fundacion Espurna, a non-profit NGO that helps the intellectually disabled to find work, founded in 1996. It began with very little capital and cared for five people, but it has multiplied its capital more than 200-fold, now cares for more than 500 different people each year, and has over 200 workers of whom more than 50% have some kind of disability.

[EN] We present a tool developed by the authors to facilitate the evaluation process by pairwise comparison and apply it in a context of problem-based learning to encourage reflection and previous work of students. Experience has proven successful with small groups (20 and 14 students) of undergraduate and master students. It remains for future research to expand the experience to large groups and check the psychometric properties of the marks obtained with this method, [ES] Presentamos una herramienta desarrollada por los autores para facilitar el proceso de evaluación por comparación pareada y la aplicamos en un contexto de aprendizaje basado en problemas para favorecer la reflexión y trabajo previo de los alumnos. La experiencia ha resultado exitosa con grupos pequeños (20 y 14 alumnos) de grado y máster. Queda pendiente para investigación futura ampliar la experiencia a grupos numerosos y comprobar las propiedades psicométricas de las puntuaciones obtenidas con este método., Este trabajo ha sido realizado con la financiación de la Unión Europea ["FINCODA" proyecto 554493-EPP-1-2014-1-FI-EPPKA2-KA] (The European Commission support for the production of this publication does not constitute an endorsement of the contents which reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein); y de la Universitat Politénica de Valencia PIME/2015/A/009/A “Evaluación de los indicadores del comportamiento innovador en el alumno universitario” y (PIME/2015/A/014/A) “Peer ranking: La evaluación por comparación en las aulas”.

[EN] A wiki is a website that can be edited easily by a user or any number of users. It can be stated that its use in the field of education is reasonably extended. However, assesment of the wiki is an emerging research line. According to the Spanish higher education system, raise the wiki activity as evaluable activity involves the evaluation by the teacher of both the quality of the wiki itself as competences developed through the activity. The electronic support of the wiki facilitates obtaining several automatic indicators such as number of words, number of links, number of figures, number of sources, etc., that could facilitate the task of the evaluation. Establishing connections between these indicators and the quality of the wiki as well as the competences developed during the activity is the main objective of this work, [ES] Una wiki es un sitio web que puede ser editado fácilmente por cualquier número de usuarios. Se puede afirmar que su uso en el ámbito de la educación está razonadamente extendido. Sin embargo, la evaluación de la wiki es una línea de trabajo emergente. En el marco del sistema universitario español, plantear la actividad wiki como actividad evaluable implica la evaluación por parte del profesor tanto de la calidad de la propia wiki como de la/s competencia/s desarrolladas a través de la actividad. El soporte electrónico de la wiki facilita la obtención de una serie de marcadores automáticos tales como nº de palabras, nº de links, nº de figuras, nº de fuentes, etc., que podrían facilitar la tarea de evaluación del profesor. El establecimiento de las conexiones entre dichos marcadores y la calidad de la wiki así como las competencias desarrolladas durante la actividad es el objetivo fundamental del presente trabajo., El presente trabajo se ha desarrollado en el marco del PIME 08/15 "WIKI en la docencia: diseño de una herramienta para evaluar la actividad del alumno" de la Universidad Politécnica de Valencia

La gestion de materiales de productos multi-nivel usa desde los anos 1970 la metodologia denominada MRP. La incorporacion del CRP en los ERP conjuntamente al MRP tradicional dio nacimiento a los llamados MRPII. Sin embargo, desde aquella epoca en la literatura, se asigna una unica lista de materiales y una lista unica de recursos a cada producto susceptible de ser ensamblado lo que implica fuertes limitaciones para considerar operaciones alternativas. En el problema GMOP, se propone el uso del concepto del stroke para resolver el problema de planificacion de las operaciones y de los materiales considerando operaciones alternativas. En este articulo, se presenta primero una evolucion del problema GMOP introduciendo las recepciones programadas, y segundo, se presenta el despliegue y analisis de las matrices que se proponen para facilitar la implementacion de un modelo y una herramienta que se basen en el concepto de stroke. Palabras clave : cadena de suministro, planificacion de las operaciones, operaciones alternativas, stroke, MRP, GMOP. The Operations & Materials Matrix and the Operations & Resources Matrix, a new approach to solve the GMOP problem based on the Stroke concept Abstract : Since the 1970, the multi-stage product materials management used the methodology called MRP. The CRP incorporation in the traditional ERP jointly with the MRP gave birth to the so-called MRPII. However, since that time in the literature, a unique bill of materials and a unique list of resources are assigned to each product to be assembled which implies strong limitations to consider alternative operations. In the GMOP problem, the use of the stroke concept is proposed to solve the operations and materials planning problem considering alternative operations. The aim of this paper is to present firstly an evolution of the GMOP problem considering scheduled receptions, and secondly to present the deployment and analysis of the matrices that are proposed to facilitate a model and tool implementation based on the stroke concept. Keywords : supply chain, operations planning, alternative operations, stroke, MRP, GMOP.

Actualmente estamos asistiendo a un cambio en la organizacion del mapa de titulaciones en la Universidad espanola. Con esto se pretende alcanzar la convergencia entre los paises europeos de forma que los titulos sean facilmente comparables y se fomente la movilidad de los estudiantes y de los profesores. En este contexto, planteamos el debate sobre la titulacion de Ingenieria de Organizacion y algunas propuestas para su definicion, ademas de apor tar el perfil del titulado y la descripcion de las competencias profesionales necesarias para su futura vida laboral. Palabras clave : Espacio Europeo de Educacion Superior, Ingenieria de Organizacion, Universidad. Industrial Engineering and the design of new European degrees Abstract : Today, we are living a change in bachelor and degree studies in the Spanish University.The reason for this is achieving the convergence between European countries by defining easy-comparable degrees and promoting mobility for students and lecturers. In this context, we show the characteristics of the studies in Industrial Engineering and some proposals about its structure. Moreover, we define the characteristics of the future engineer and the professional competences to develop in his or her future jobs. Key words : European Higher Education Area, Industrial Engineering, University.

Current practices for the treatment of the physically and/or mentally handicapped prescribe meaningful job activity as a means towards both a more fulfilling life and societal integration. In many countries, these practices have facilitated the development of many Sheltered Work Centres for Disabled. In the case study presented, a reengineering process is done starting from individual workplaces where only certain workers were capable of assembling the entire product, and finishing with an assembly line implementation. It is revealed how the traditional division of work in single tasks, typical in assembly lines, becomes a perfect tool for making certain worker disabilities invisible, providing new jobs for disabled people; always taking into account certain special constraints that are analysed.

We propose a new fuzzy mathematical programming model for production planning under uncertainty in an industrial environment. This model considers fuzzy constraints related to the total costs, the market demand and the available capacity of the productive resources and fuzzy coefficients for the costs due to the backlog of demand and for the required capacity. The main goal is to determine the master production schedule of each product, the MRP (Material Requirement Planning) for each raw component in each period, stock levels, demand backlog, and capacity usage levels over a given planning horizon. Finally, the proposed model is tested by using data from an automobile seat assembler and compared with other fuzzy mathematical programming approaches. The experiment shows that the proposed model has not got a better behaviour than more simple fuzzy models, but the advantage is that both types of uncertainties, fuzziness and lack of knowledge or epistemic uncertainty can be considered in a model with fuzzy constraints and fuzzy coefficients.

We consider the problem of scheduling the production of multiple products on a single facility with limited production capacity, in literature known as Economic Lot Scheduling Problem (ELSP). In this work we compare the performance of five different production strategies for the ELSP under different stationary stochastic demand patterns. The performance, related to total inventory and setup costs, of different approaches to this problem is clearly dependent upon the production environment. In this study we focus on demand rates, as one of the most important parameters affecting this environment. We analyze through a simulation study the effect of diversity on stochastic demand rates, under different utilization levels. The results of our simulation study confirm that the performance of a production strategy is strongly dependent on utilization and homogeneity of demand rates. Therefore, this effect proves that a sensitivity analysis to evaluate the impact of the particular value of these and other parameters on the performance of the production strategies might be a key issue for industrial applications of the ELSP.

[EN] In this paper, a simulation modeling using system dynamics (Vensim®) to propose an alternative coordination solution between two companies in the construction sector. It is provided a comparison between the field results of an alternative solution provided by the adhesive company in response of his customer collaboration request, kitchen bench company, to manage the supply and the results of the simulation model., [ES] En este artículo, se propone un modelo de simulación mediante la dinámica de sistemas (Vensim®) con el fin de evaluar alternativas de coordinación en la gestión del aprovisionamiento entre dos empresas del sector de la construcción. Se comparan los resultados de campo, de una solución aportada por una empresa de adhesivos, en respuesta a la solicitud de colaboración de su cliente, empresa de encimeras, para la gestión del aprovisionamiento y se evalúan los resultados a través de una simulación.

During the designing phase of a retail chain, a very important decision appears to fulfil the client service target with the total minimum cost as a trade-off between inventory management policies for each shop and delivery policies from the central warehouse. This balance is the basis for key decisions, such as inventory planning, space allocated to the shops, delivery management and customer responsiveness. In this paper, we (a) analyze and model this problem, including some usual operational constraints at the shop level; (b) apply to a realistic example; and (c) find that, in some instances, total costs can be lowered while increasing customer responsiveness.

The consideration of uncertainty in manufacturing systems supposes a great advance. Models for production planning which do not recognize the uncertainty can be expected to generate inferior planning decisions as compared to models that explicitly account for the uncertainty. This paper reviews some of the existing literature of production planning under uncertainty. The research objective is to provide the reader with a starting point about uncertainty modelling in production planning problems aimed at production management researchers. The literature review that we compiled consists of 87 citations from 1983 to 2004. A classification scheme for models for production planning under uncertainty is defined.

This paper addresses the problem of products grouping in the tile industry. This production system can be classified as a three-stage hybrid flowshop with sequence dependent and separable setup times. Main objective has been to identify a set of families integrated by products with common features. This classification would help Production Managers to minimize changeover time, allowing them to further reduce production times. The basic concept of “exploiting similarities”, taken from the Group Technology (GT) philosophy, has been used to address the problem in a creative way. A new “coefficient of similarity” between each of the products, has been defined and used as a parameter, allowing products to be grouped through a heuristic method. This research has already been applied in the framework of a real case, getting quite positive results (actual reduction in both setup and production costs, easier long-horizon planning and short-horizon scheduling, more accurate set up time estimates for new products, etc.).

[EN] This paper presents a decision support system to simultaneously solve the supply network configuration problem and the operations scheduling problem for the machine tool industry. A novel database structure, which is able to consider alternative operations and alternative bills of material, has been used. An algorithm for complete enumeration to determine all the feasible solutions using stroke graphs is introduced. A multiagent-based simulator evaluates the different key performance indicators that the supply network deals with for each alternative solution (e.g. workload, profits, delivery times, etc.) to determine that ‘satisficed’ by the collaborative decision-making among its members. A case study based on a Spanish company that assembles highly customised machines and tools in several European plants is considered. From the experiments results based on data linked to this industry, it will be demonstrated that the tool is potentially useful for stakeholders and for the central decision-maker to make decisions collaboratively in a multisite context case, We thank the EWG-DSS and their four expert anonymous referees as well as the guest editorial board for their useful suggestions and criticism on earlier versions of this paper. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. NMP2-SL-2009-229333 and has been partially supported by the Spanish Ministry of Science and Innovation within the 'Proyectos de Investigacion Fundamental No Orientada Programme' through Project 'CORSARI MAGIC DPI2010-18243'. Julien Maheut holds a VALi+d grant funded by the Regional Valencian Government (Ref. ACIF/2010/222).

[EN] The EOQ formula (Harris, Fact Mag Manage 10(2):135-6-152, 1913) provides a balance between setup costs and holding costs in the system. This formula has been widely developed in the literature. However in the industrial reality, it is often difficult to know the exact value of these setup and holding costs. In this paper, we develop a formula to estimate lot size from the values known in the company. It is verified that the behavior of these formulas meets expectations., The work described in this paper has been supported by Project “CORSARI MAGIC DPI2010-18243” from the Spanish Ministry of Science and Innovation.

[EN] This paper presents a simulation model that has been created to support decision-making during the layout redesign of an engine and transmission assembly plant in the automotive sector. The plant requires a new layout and supply logistic due to an increase in its complexity and daily production. Discrete event simulation has been used to validate an initial proposal and to propose different what-if scenarios of layout and operations management systems. These scenarios will be evaluated regarding materials flow generated throughout the plants. The main focus of the decision process was focused on safety issues related to the material handling. The simulation model and its description have been done according to the methodology proposed in Sáez Más, García Sabater, Morant Llorca, y Maheut (2016), where the simulation model is focus as a 4-layer architecture (network, logic, database and visual reality). The achieved model is very flexible and modular, and it allows to save modelling time because of the parameterize of different combinations in layout and operations management., [ES] Este trabajo presenta un modelo de simulación, que se ha creado para apoyar el rediseño de las instalaciones de una planta de montaje de motores y transmisiones en el sector del automóvil. La planta requiere de un nuevo layout y logística de aprovisionamiento, debido a un aumento en su complejidad y su producción diaria. La simulación por eventos discretos se utiliza para validar una propuesta inicial y proponer diferentes escenarios what-if de distribución y gestión de las operaciones. Estos escenarios se evalúan considerando el flujo de material generado a lo largo de las instalaciones. El principal objetivo durante la toma de decisiones se centra en aspectos de seguridad relacionados con el movimiento de material. La construcción de modelo de simulación y su descripción en el documento se realiza según la metodología propuesta en Sáez Más, García Sabater, Morant Llorca, y Maheut (2016) donde, el modelo de simulación se enfoca como una arquitectura de 4 capas (red, lógica, base de datos y realidad visual). El modelo obtenido resulta ser muy flexible y modular, lo que permite un ahorro de tiempo de modelado considerable, al parametrizar las diferentes combinaciones de distribución y de gestión de las operaciones.

The aim of this paper is to present a coordination mechanism between MILP models for planning operations within an integrated planning tool. The mechanism presented allows co-ordinate planning models between different domains (procurement, production, transportation), the different planning horizons (mid-term, short-term and very short-term) and between the different planning periods. This mechanism has been design to ensure coordination and integrity between the different plans while meeting the expectations of the different stakeholders involved in the planning process of an automotive plant. The proposed mechanism was implemented in an Advanced Planning and Scheduling system for an engine assembly company.

Part 1: Sustainability; International audience; A trend in up-to date developments in multi-site operations planning models is to consider in details the different ways to produce, buy or transport products and the distributed decision-making process for operations planning. One of the most generic approaches to support global optimization in those supply chain networks by considering all the different operations alternatives and product structures is the Generic Materials & Operations Planning Problem. This problem can be modelled by a Mixed Integer Linear Programming model capable of considering production, transportation, procurement tasks and their alternatives and other relevant issues such as packaging. The aim of this paper is to introduce the implementation of a parallelizable heuristic method for materials and operations planning and its application to a case of a Supply Chain Network of the automotive industry. The approach uses variants of the GMOP model to overcome traditional MRP systems’ limitations.

[EN] This paper presents an operations planning scheme based on mathematical programming models (specifically, Mixed-Integer Linear Programming (MILP) models) integrated into a web-enabled Advanced Planning and Scheduling System (APS), developed for and implemented in an engine assembler that supplies the car industry. One objective of this paper is to provide empirical insights into some operations planning characteristics in the automotive industry. The other main objective is to show MILP models and their use to create plans that enable the coordination of different planning levels (mid-term and short-term) and planning domains (procurement, production and distribution). The APS fulfills the requirements of an engine assembler in the automotive sector (namely lean-type constraints and objectives). The system is based on two MILP models, which have been purposely developed together along with their relations. The models presented herein provide a solution that considers supply chain objectives and constraints, and are integrated by means of data and constraints which have proven sufficient to fulfill users' and stakeholders' requirements. This case study presents the models' most relevant aspects and their implementation. © Springer Science+Business Media, LLC 2011., The work described in this paper has been partially supported by the Ministerio de Ciencia e Innovacion del Gobierno de Espana within the Program de "Proyectos de Investigacion Fundamental No Orientada through the project "CORSARI MAGIC DPI2010-1824300" and by the Universitat Politecnica de Valencia, through the Project PAID-05-2010-2741. Julien Maheut holds a Val I + D grant funded by the Generalitad Valenciana (Regional Valencian Government, Spain) (Ref. ACIF/2010). The authors wish to thank three anonymous reviewers for their comments which have greatly improved the paper. They also wish to thank the people at the factory and at the IT consultancy firm for their continuous support and encouragement.

This paper presents an algorithm to define the optimal parameters for deliberated and controlled coproduction in an economic lot scheduling problem setting (DCCELSP). Coproduction is said to be deliberated and controlled because it is possible to decide whether or not to coproduce when all the parameters associated with the process are known. The aim is to determine how to produce two products most economically where deliberated coproduction is an option. For this purpose, a procedure for defining optimal lot periods is introduced. Two models are proposed for this procedure and a numerical illustration is provided to gain insight into their dynamics. The cost advantages of coproduction were found to depend on the relationship between setup and holding costs, production rates, and demand for products. The more similar these system parameters are and the higher the machine usage ratio is, the more favourable coproduction is. Additionally, if coproduction is not deliberated appropriately, costs soar., The work described in this paper has been supported by the project "CORSARI MAGIC DPI2010-18243" of the Ministerio de Ciencia e Innvovacion of Government of Spain within the Program "Proyectos de Investigacion Fundamental no orientada". The translation of this paper was funded by the Universidad Politecnica de Valencia, Spain.

Part 1: Production Process; International audience; This paper addresses the Generic Materials and Operations Planning (GMOP) problem, a multi-site operations planning problem based on the “stroke” concept. The problem considers a multinational company subject to positive and negative backlogs imposed by using returnable racks that have to be filled by end products and transported to customers, alternative operations (purchase, transformation and transport), different BOM structures given the different operation types (injection operations, assembly operations) performed in the various factories of the supply chain, and capacitated production resources. This paper describes and defines the “stroke” construct that mathematically models the relationships between operations and materials. The mathematical modelling approach is provided, as is a brief description of an operations planning tool that has been implemented. Furthermore, some results obtained in a first-tier level supplier of the automotive industry have been introduced.

One of the problems to be solved in manufacturing networks, with several production centers, is the selection of a suitable manufacturer for each component in order to obtain competitive costs while making full use of the network's capacity. A solution is to own redundant information channels which, despite offering the network greater resilience, generate high costs. The coordination of the nodes in the manufacturing network could lower materials and information flows, thus cutting lead times and total costs, and regulating the system's total productive capacity. This work proposes a coordination model that centralizes materials and information flows, and cuts the costs and overall lead times. It also makes the self-adjustment of productive capacity possible.

The aggregate production planning (APP) problem is concerned with determining the optimum production, work force, and inventory levels for each period of the planning horizon. The aggregate production planning problem is a multiple objective one; that involves many functional areas to create. This paper addresses an implementation of a Decision Support System that supports an aggregate production planning problem. The case study covers a real engine assembler serving from their local premises to clients all over the world, with variable demands and calendars. The core of the global tool is a set of MILP model which calculates working calendars for six different sections of a factory, taking into account production rates defined by the company, its internal and external suppliers working calendars and the union requirements. Moreover, the real system had requirements that are not usually considered on APP literature. The model has been designed and calibrated in a prototype-validation iterative process and has been optimized to calculate scenarios with an acceptable computational time within planners' expectative. The system has been developed using free-software and its interfaces have been designed to require the minimum possible interaction from users. The time cost due to the use of non-commercial software has been assessed