Algorithms for Scheduling Problems

This edited book presents new results in the area of algorithm development for different types of scheduling problems. In eleven chapters, algorithms for single machine problems, flow-shop and job-shop scheduling problems (including their hybrid (flexible) variants), the resource-constrained project scheduling problem, scheduling problems in complex manufacturing systems and supply chains, and workflow scheduling problems are given. The chapters address such subjects as insertion heuristics for energy-efficient scheduling, the re-scheduling of train traffic in real time, control algorithms for short-term scheduling in manufacturing systems, bi-objective optimization of tortilla production, scheduling problems with uncertain (interval) processing times, workflow scheduling for digital signal processor (DSP) clusters, and many more

Simulation-Optimization model for a hybrid flow shop. Case study, chemical industry

Actualmente, las técnicas de investigación de operaciones han demostrado tener un impacto significativo en los sistemas de fabricación modernos, ya que proporcionan una productividad y rendimiento mejorados en mercados altamente competitivos. El problema del Flow Shop de flujo híbrido, también conocido como problema de Flow Shop flexible, es un problema de programación relacionado con un grupo de máquinas paralelas por etapa, frecuentemente asociado con la minimización del tiempo en un entorno de producción. Este problema se considera un problema NP-hard debido a las decisiones combinatorias, los recursos informáticos exigentes y el tiempo de ejecución. Esta investigación se centra en un caso de estudio de la empresa Fuller Pinto, una empresa internacional con sede en Colombia de la industria química que presenta un entorno de tienda de flujo híbrido. Incluso hoy en día, la compañía todavía tiene problemas asociados con la entrega tardía de productos debido a la mala programación, lo que hace que la producción planificada no se lleve a cabo en su totalidad. Además, estos productos sin terminar se convierten en pedidos pendientes con mayor importancia que deben suministrarse de manera obligatoria. Por esta razón, esta investigación propone un sistema de apoyo a la decisión basado en un modelo de simulación-optimizacion para la programación de Fuller Pinto, con el objetivo de minimizar la tardanza total ponderada. El modelo propuesto presenta capacidades mejoradas que simulan el comportamiento del entorno de fabricación para soportar las decisiones de Fuller Pinto. Para validar este modelo, se han probado diferentes escenarios o instancias relacionadas con el comportamiento de producción de productos químicos. Se presentan las comparaciones entre el modelo de simulación-optimización propuesto, la regla de despacho de SPT y los datos históricos de la empresa. Como resultado, el modelo proporciona una programación de la producción óptima de trabajos para cada campaña de Fuller Pinto.Currently, opeiations research techniques have proved to make a significant impact in modem manufacturing systeins as it provides an enhanced productivity and performance on highly competitive markets. Hybrid Flow Shop Problem, also known as Flexible Flow Shop problem, is a scheduling problem related to a group ofparallel machines per stage, frequently associated with time minimization in a manufacturing environment. This problem is considered a NP-hard problem due to the combinatoria! decisions and the demanding computing resources and execution time in its resolution. This research is focused on a case study of Fuller Pinto which is an intemational Colombian-based company from the Chemical industry that presents a Hybrid Flow Shop environment on its shop-floor. Even today, the company still have issues associated to late deliverof products due to poor scheduling, causing the planned production no to be completed. Moreover, these unfínished products become backorders with higher importance that must be supplied mandatory. For this reason, this research proposes a decisión support system based on a simulation-optimization model íor Fuller Pinto scheduling, aiming the minimization of the total weighted tardiness. The proposed model features enhanced capabilities simulating the behavior of the complex manufacturing environment and hybridize iteratively an optimization algorithm to support the Fuller Pinto decisions. To valídate this model, different scenarios or instances related to the production behavior of Chemical products have been tested. Comparisons among the proposed simulation-optimization model, the SPT dispatching rule and historical data of the company are presented. As results, the model provides an optimal schedule of jobs for each campaign of Fuller Pinto.Ingeniero (a) IndustrialPregrad

Hybrid Flow Shop with Unrelated Machines, Setup Time, and Work in Progress Buffers for Bi-Objective Optimization of Tortilla Manufacturing

We address a scheduling problem in an actual environment of the tortilla industry. Since the problem is NP hard, we focus on suboptimal scheduling solutions. We concentrate on a complex multistage, multiproduct, multimachine, and batch production environment considering completion time and energy consumption optimization criteria. The production of wheat-based and corn-based tortillas of different styles is considered. The proposed bi-objective algorithm is based on the known Nondominated Sorting Genetic Algorithm II (NSGA-II). To tune it up, we apply statistical analysis of multifactorial variance. A branch and bound algorithm is used to assert obtained performance. We show that the proposed algorithms can be efficiently used in a real production environment. The mono-objective and bi-objective analyses provide a good compromise between saving energy and efficiency. To demonstrate the practical relevance of the results, we examine our solution on real data. We find that it can save 48% of production time and 47% of electricity consumption over the actual production

Proceedings of the 8th International Conference on Energy Efficiency in Domestic Appliances and Lighting

At the EEDAL'15 conference 128 papers dealing with energy consumption and energy efficiency improvements for the residential sector have been presented. Papers focused policies and programmes, technologies and consumer behaviour. Special focus was on standards and labels, demand response and smart meters. All the paper s have been peer reviewed by experts in the sector.JRC.F.7-Renewables and Energy Efficienc