An economic lot and delivery scheduling problem with the fuzzy shelf life in a flexible job shop with unrelated parallel machines

This paper considers an economic lot and delivery scheduling problem (ELDSP) in a fuzzy environment with the fuzzy shelf life for each product. This problem is formulated in a flexible job shop with unrelated parallel machines, when the planning horizon is finite and it determines lot sizing, scheduling and sequencing, simultaneously. The proposed model of this paper is based on the basic period (BP) approach. In this paper, a mixed-integer nonlinear programming (MINLP) model is presented and then it is changed into two models in the fuzzy shelf life. The main model is dependent to the multiple basic periods and it is difficult to solve the resulted proposed model for large-scale problems in reasonable amount of time; thus, an efficient heuristic method is proposed to solve the problem. The performance of the proposed model is demonstrated using some numerical examples

Minimizing The Number of Tardy Jobs in Hybrid Flow Shops with Non-Identical Multiple Processors

Two-stage hybrid flow shops (a.k.a., flow shops with multiple processors (FSMPs)) are studied wherein the multiple processors at a stage are non-identical, but related (a.k.a., uniform) in their processing speeds.   The impact of ten different dispatching procedures on a due-date based criterion (specifically, the number of tardy jobs) is analyzed over a set of 1,800 problems of varying configurations wherein the number of jobs per problem is between 20 and 100 and their due dates are randomly assigned.  Results indicate that the modified due date (MDD), earliest due date (EDD), slack (SLK), shortest processing time (SPT), and least work remaining (LWR) rules are statistically inseparable but yield superior performance to the other rules included in this study.  The longest processing time (LPT) and most work remaining (MWR) rules provide the poorest performance

Multicriteria hybrid flow shop scheduling problem: literature review, analysis, and future research

This research focuses on the Hybrid Flow Shop production scheduling problem, which is one of the most difficult problems to solve. The literature points to several studies that focus the Hybrid Flow Shop scheduling problem with monocriteria functions. Despite of the fact that, many real world problems involve several objective functions, they can often compete and conflict, leading researchers to concentrate direct their efforts on the development of methods that take consider this variant into consideration. The goal of the study is to review and analyze the methods in order to solve the Hybrid Flow Shop production scheduling problem with multicriteria functions in the literature. The analyses were performed using several papers that have been published over the years, also the parallel machines types, the approach used to develop solution methods, the type of method develop, the objective function, the performance criterion adopted, and the additional constraints considered. The results of the reviewing and analysis of 46 papers showed opportunities for future researchon this topic, including the following: (i) use uniform and dedicated parallel machines, (ii) use exact and metaheuristics approaches, (iv) develop lower and uppers bounds, relations of dominance and different search strategiesto improve the computational time of the exact methods,  (v) develop  other types of metaheuristic, (vi) work with anticipatory setups, and (vii) add constraints faced by the production systems itself

Diseño y validación de un modelo de planeación y programación de la producción basado en sistemas multiproducto – multiempaque

La programación de múltiples referencias en los sistemas de manufactura apunta a la facilidad de la producción. En estos sistemas se implementan diferentes estrategias de producción por lotes, de acuerdo con el tipo de sistema. Sin embargo, se ignoran elementos importantes tales como los alistamientos y emisiones de dióxido de carbono por la utilización de energía. Adicionalmente, se tiene incertidumbre de la demanda, la cual influye en cómo se empaca. Por lo tanto, es necesario implementar estrategias de estandarización o flexibilidad para determinar el tamaño de empaque de producto terminado. Esta investigación presenta la formulación de dos modelos matemáticos que integran los problemas de programación de la producción y tamaño de empaque de producto terminado con base en dos estrategias: (1) minimización de costo de unidades perdidas y (2) minimización de costo de desembalaje. Ambos modelos están sujetos a restricciones de secuenciación, tiempos de inicio de procesamiento y empaque, tamaño de los sub–lotes de empaque, tiempo total disponible e inventario final por referencia. Se diseñó un algoritmo genético híbrido (AGH) para resolver cada uno de los modelos. Los resultados obtenidos mostraron que la calidad de las soluciones está afectada por los parámetros de búsqueda del AGH al resolver el modelo 1, mientras que para el modelo 2 no. El tiempo computacional aumenta al agregar referencias al resolver ambos modelos. Además, la segunda estrategia de empaque (modelo 2) entrega mejores resultados por la flexibilidad de abrir empaques de producto terminado.MaestríaMagister en Ingeniería Industria

Diseño de una metodología de programación de producción para la reducción de costos en un flow shop híbrido flexible mediante el uso de algoritmos genéticos. Aplicación a la industria textil

La industria textil posee configuración productiva flow shop híbrido flexible, además de una serie de particularidades que hacen que los modelos estándares de programación de producción no sean aplicables. Se ha demostrado la naturaleza N-P completo del problema, por lo que el uso de meta heurísticas está bien justificado. Considerando la importancia de la reducción de los costos de fabricación en la industria textil colombiana, se propone una nueva metodología de programación de producción basada en algoritmos genéticos, que tiene presente algunas de las complejidades de la industria textil (tiempos de montaje dependientes de la secuencia, máquinas paralelas no relacionadas, cumplimiento de fechas de entrega) y permite la reducción de sus costos de producción. Al aplicarla a un problema basado en la industria textil colombiana se obtuvo una mejora promedio del 22,39% y 22,36% con respecto al método SPT y a un método aleatorio, respectivamente. Asimismo se reduce casi en un 100% el incumplimiento de fechas de entrega. Se concluye que la metodología es efectiva y que puede extenderse su aplicación a otros sectores industriales con configuración flow shop híbrido flexible. Futuros trabajos podrían considerar otras complejidades como los lotes de transferencia variables, la entrada dinámica y la maleabilidad, o aplicar la metodología a otro tipo de industrias con esta configuración productivaAbstract : Textile industry can be described by the productive configuration denominated Hybrid Flow Shop, and has a number of characteristics that make the standard scheduling models not applicable. It has been proved the NP-complete nature of the problem, so that the use of meta-heuristics is well justified. Considering the importance of reducing manufacturing costs in Colombian textile industry, a new production scheduling methodology based on genetic algorithms is proposed, which take into account some of the complexities presented in the textile industry (sequence dependent setup times, unrelated parallel machines, compliance with due dates) and allows the reduction of production costs. When the methodology was applied to a Colombian textile industry-based problem, an average improvement of 22.39% and 22.36% in comparison with the SPT method and random method, respectively, were obtained. It was also reduced almost in 100% the failure to due dates. It is concluded that the methodology is effective and can extend its application to other industries with a hybrid flow shop configuration. Future work could consider other complexities such as variable transfer batches, dynamic input and malleability, or apply the methodology to other industries in this productive configurationMaestrí

Scheduling Hybrid Flow Lines of Aerospace Composite Manufacturing Systems

Composite manufacturing is a vital part of aerospace manufacturing systems. Applying effective scheduling within these systems can cut the costs in aerospace companies significantly. These systems can be characterized as two-stage Hybrid Flow Shops (HFS) with identical, non-identical and unrelated parallel discrete-processing machines in the first stage and non-identical parallel batch-processing machines in the second stage. The first stage is normally the lay-up process in which the carbon fiber sheets are stacked on the molds (tools). Then, the parts are batched based on the compatibility of their cure recipe before going to the second stage into the autoclave for curing. Autoclaves require enormous capital investment and maximizing their utilization is of utmost importance. In this thesis, a Mixed Integer Linear Programming (MILP) model is developed to maximize the utilization of the resources in the second stage of this HFS. CPLEX, with an underlying branch and bound algorithm, is used to solve the model. The results show the high level of flexibility and computational efficiency of the proposed model when applied to small and medium-size problems. However, due to the NP-hardness of the problem, the MILP model fails to solve large problems (i.e. problems with more than 120 jobs as input) in reasonable CPU times. To solve the larger instances of the problem, a novel heuristic method along with a Genetic Algorithm (GA) are developed. The heuristic algorithm is designed based on a careful observation of the behavior of the MILP model for different problem sets. Moreover, it is enhanced by adding a number of proper dispatching rules. As its output, this heuristic algorithm generates eight initial feasible solutions which are then used as the initial population of the proposed GA. The GA improves the initial solutions obtained from the aforementioned heuristic through its stochastic iterations until it reaches the satisfactory near-optimal solutions. A novel crossover operator is introduced in this GA which is unique to the HFS of aerospace composite manufacturing systems. The proposed GA is proven to be very efficient when applied to large-size problems with up to 300 jobs. The results show the high quality of the solutions achieved by the GA when compared to the optimal solutions which are obtained from the MILP model. A real case study undertaken at one of the leading companies in the Canadian aerospace industry is used for the purpose of data experiments and analysis

An investigation of production and transportation policies for multi-item and multi-stage production systems

Die vorliegende kumulative Dissertation besteht aus fünf Artikeln, einem Arbeitspapier und vier Artikeln, die in wissenschaftlichen Zeitschriften veröffentlicht wurden. Alle fünf Artikel beschäftigen sich mit der Losgrößenplanung, jedoch mit unterschiedlichen Schwerpunkten. Artikel 1 bis 4 untersuchen das Economic Lot Scheduling Problem (ELSP), während sich der fünfte Artikel mit einer Variante des Joint Economic Lot Size (JELS) Problems beschäftigt. Die Struktur dieser Dissertation trägt diesen beiden Forschungsrichtungen Rechnung und ordnet die ersten vier Artikel dem Teil A und den fünften Artikel dem Teil B zu

Mejora de tiempos de entrega en un flow shop híbrido flexible usando técnicas inteligentes. Aplicación en la industria de tejidos técnicos

Se busca aportar herramientas útiles para la programación de producción en la industria de tejidos técnicos. Se parte de las condiciones actuales de la programación de producción en este tipo de industria y de los antecedentes en la literatura científica sobre modelos aplicables a estos entornos. Se propone un modelo de solución por técnicas inteligentes a la problemática de la secuenciación y asignación de tareas en los entornos flow shop híbrido flexible considerando situaciones como: paralelismo entre máquinas no relacionadas, tiempos de montaje dependientes de la secuencia, entrada dinámica de trabajos, restricción de elegibilidad, maleabilidad y lotes de transferencia variables entre etapas. De allí se construye la propuesta de solución que involucra simultáneamente todas las condiciones de entorno real mencionadas y aplica un algoritmo genético modificado de acuerdo a las características del problema. Se concluye que el modelado considerando condiciones realistas es posible, que los algoritmos genéticos son una opción práctica para entornos reales y que las empresas pueden obtener mejoras en su capacidad de respuesta con este tipo de solucionesAbstract : It seeks to provide useful tools for production scheduling in the technical textiles industry. It begins in the current conditions of production scheduling in this type of industry and the background in scientific literature, applicable to these environments models. The mathematical model to solve the problem of sequencing and assigning jobs in Flexible hybrid flow shop environments is developed considering: unrelated parallel machines, sequence dependent setup time, dynamic entry of jobs, availability constrain, malleability and variable transfer batches between stages. The solution proposal is build including all actual environment features considered together and applying a modified genetic algorithm modeled according to the problem. It is concluded that the model of scheduling problems considering realistic conditions is possible, that genetic algorithms are a practical option for real environments, and that companies can achieve improvements in their responsiveness with this kind of solutionsDoctorad