Person: Tirado Domínguez, Gregorio
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Económicas y Empresariales
Economía Financiera, Actuarial y Estadística
Estadística e Investigación Operativa
Now showing 1 - 10 of 30
PublicationImproved solutions to dynamic and stochastic maritime pick-up and delivery problems using local search.(Springer, 2017) Tirado Domínguez, Gregorio; Hvattum, L.M.Heuristics for stochastic and dynamic vehicle routing problems are often kept relatively simple, in part due to the high computational burden resulting from having to consider stochastic information in some form. In this work, three existing heuristics are extended by three different local search variations: a first improvement descent using stochastic information, a tabu search using stochastic information when updating the incumbent solution, and a tabu search using stochastic information when selecting moves based on a list of moves determined through a proxy evaluation. In particular, the three local search variations are designed to utilize stochastic information in the form of sampled scenarios. The results indicate that adding local search using stochastic information to the existing heuristics can further reduce operating costs for shipping companies by 0.5–2 %. While the existing heuristics could produce structurally different solutions even when using similar stochastic information in the search, the appended local search methods seem able to make the final solutions more similar in structure. PublicationElaboración de casos prácticos de Estadística utilizando el software R en el entorno Moodle(2019-02-05) Alonso Sanz, Rosa; Martín-Campo, F. Javier; Ortuño, M. T.; Pardo Llorente, María del Carmen; Rodríguez González, Juán Tinguaro; Rojas Patuelli, Karina Hortensia; Tirado Domínguez, Gregorio PublicationThe Double Traveling Salesman Problem with Multiple Stacks and a Choice of Container Types(MDPI, 2020-06-16) Hvattum, Lars Magnus; Tirado Domínguez, Gregorio; Felipe Ortega, ÁngelThe double traveling salesman problem with multiple stacks involves the transportation of goods between two regions. In one region, a vehicle carrying a container visits customers, where pallets of goods are loaded into the container. The container is then shipped to a different region, where another vehicle visits another set of customers where the pallets are unloaded. Pallets are loaded in several rows inside the container, where each row follows the last-in-first-out principle. The standard test instances for the double traveling salesman problem with multiple stacks implies the use of a 45-foot pallet wide container to carry EUR-1 pallets. This paper investigates the effect on transportation costs if an open side container could be used when transporting the pallets. Computational experiments show savings in transportation costs of up to 20%. Moreover, by using a container loaded from the side, rather than from the rear, the defining attributes of the double traveling salesman problem seem to be lost. PublicationDetermining departure times in dynamic and stochastic maritime routing and scheduling problems(Springer, 2017) Tirado Domínguez, Gregorio; Hvattum, L.M.In maritime transportation, decisions are made in a dynamic setting where many aspects of the future are uncertain. However, most academic literature on maritime transportation considers static and deterministic routing and scheduling problems. This work addresses a gap in the literature on dynamic and stochastic maritime routing and scheduling problems, by focusing on the scheduling of departure times. Five simple strategies for setting departure times are considered, as well as a more advanced strategy which involves solving a mixed integer mathematical programming problem. The latter strategy is significantly better than the other methods, while adding only a small computational effort. PublicationUsing intermediate infeasible solutions to approach vehicle routing problems with precedence and loading constraints(Elsevier Science, 2011-05-16) Ortuño, M. T.; Tirado Domínguez, Gregorio; Felipe Ortega, ÁngelLogistics and transportation issues have been receiving increasing attention during the last decades and their requirements have gradually changed, making it necessary to take into account new situations and conditions. The Double Traveling Salesman Problem with Multiple Stacks (DTSPMS) is a pickup and delivery problem in which some additional precedence and loading constraints are imposed on the vehicle to be used. In this paper we approach the problem using intermediate infeasible solutions to diversify the search process and we develop some fixing procedures and infeasibility measures to deal with this kind of solutions and take advantage of their potential. (C) 2010 Elsevier B.V. All rights reserved. PublicationHeuristics for dynamic and stochastic routing in industrial shipping(Pergamon-Elsevier, 2013-01) Tirado Domínguez, Gregorio; Hvattum, Lars Magnus; Fagerholt, Kjetil; Cordeau, Jean-FrancoisMaritime transportation plays a central role in international trade, being responsible for the majority of long-distance shipments in terms of volume. One of the key aspects in the planning of maritime transportation systems is the routing of ships. While static and deterministic vehicle routing problems have been extensively studied in the last decades and can now be solved effectively with metaheuristics, many industrial applications are both dynamic and stochastic. In this spirit, this paper addresses a dynamic and stochastic maritime transportation problem arising in industrial shipping. Three heuristics adapted to this problem are considered and their performance in minimizing transportation costs is assessed. Extensive computational experiments show that the use of stochastic information within the proposed solution methods yields average cost savings of 2.5% on a set of realistic test instances. PublicationEl doble problema del viajante con múltiples pilas(Universidad Complutense de Madrid, Servicio de Publicaciones, 2010-03-25) Tirado Domínguez, Gregorio; Felipe Ortega, Ángel; Ortuño Sánchez, María Teresa PublicationExperiencias piloto en evaluación online mediante casos prácticos generados en R para el entorno Moodle/Collaborate(2022-12-28) Martin Campo, Francisco Javier; Alonso Sanz, Rosa; Ferrer Caja, José María; González Ortega, Jorge; Muñoz López, Susana; Ortuño Sánchez, María Teresa; Tirado Domínguez, Gregorio; Vitoriano Villanueva, Begoña PublicationAn adapted heuristic approach for a clustered traveling salesman problem with loading constraints(Springer, 2012-09) Felipe Ortega, Ángel; Ortuño, M. T.; Tirado Domínguez, GregorioThe joint optimization of routing and loading operations is crucial to fully optimize the overall planning process in logistics, and as a result routing problems with side constraints are becoming more and more important during the last years. This paper approaches the design of optimal routes for pickup and delivery operations considering in addition some capacity and loading constraints on the vehicles to be used. It is focused on exploiting new ideas to deal with real life situations in which the customers are not uniformly distributed on the pickup or delivery regions of the problem. An adapted and effective heuristic based on a Variable Neighborhood Search framework using improved neighborhood structures is proposed and discussed. The algorithm is applied to several new sets of instances with special structures to better represent real life situations, providing computational results to evaluate its performance. PublicationOn a selection and scheduling problem in automatic storage and retrieval warehouses(Taylor & Francis, 2013-09-01) Alonso Ayuso, Antonio; Tirado Domínguez, Gregorio; Udías, AngelWarehousing is one of the main components of the supply chain and its optimisation is crucial to achieve global efficiency. Warehouse operations involve receiving, shipping, storing and order picking, among other things, and the coordinated optimisation of all these different operations is highly complex. This paper examines a real selection and scheduling problem that arises in an automatic storage/retrieval warehouse system involving the scheduling of forklift pickup operations. The objective is to minimise the total loading time of the vehicles performing transportation, while respecting their departure due dates. This complex problem is approached via a two-phase decomposition method, combining both exact and heuristic procedures. The performance of the proposed solution method is evaluated using extensive computational results from several scenarios from a real case study using data from a real mattress warehouse.