Strategic and operational decision-making in expanding supply chains for LNG as a fuel

The European Union aims for a 40% reduction in greenhouse gas emissions by 2030, compared to 1990 levels, and recognizes the opportunities of Liquefied Natural Gas (LNG) as an alternative fuel for transportation to reach this goal. The lack of a mature supply chain for LNG as a fuel results in a need to invest in new (satellite) terminals, bunker barges and tanker trucks. This network design problem can be defined as a Two-Echelon Capacitated Location Routing Problem with Split Deliveries (2E-CLRPSP). An important feature of this problem is that direct deliveries are allowed from terminals, which makes the problem much harder to solve than the existing location routing literature suggests. In this paper, we improve the performance of a hybrid exact algorithm and apply our algorithm to a real world network design problem related to the expansion of the European supply chain for LNG as a fuel. We show that satellite terminals and bunker barges become an interesting option when demand for LNG grows and occurs further away from the import terminal. In those situations, the large investments associated with LNG satellites and bunker barges are offset by reductions in operational costs of the LNG tanker trucks

Research trends in combinatorial optimization

Acknowledgments This work has been partially funded by the Spanish Ministry of Science, Innovation, and Universities through the project COGDRIVE (DPI2017-86915-C3-3-R). In this context, we would also like to thank the Karlsruhe Institute of Technology. Open access funding enabled and organized by Projekt DEAL.Peer reviewedPublisher PD

Solving the Capacitated location-Routing Problem by a GRASP complemented by a Learning Process and a Path Relinking

As shown in recent researches, the costs in distribution systems may be excessive if routes are ignored when locating depots. The location routing problem (LRP) overcomes this drawback by simultaneously tackling location and routing decisions. This paper presents a newmetaheuristic to solve the LRP with capacitated routes and depots. A first phase executes a GRASP, based on an extended and randomized version of Clarke and Wright algorithm. This phase is implemented with a learning process on the choice of depots. In a second phase, new solutions are generated by a post-optimization using a path relinking. The method is evaluated on sets of randomly generated instances, and compared to other heuristics and a lower bound. Solutions are obtained in a reasonable amount of time for such a strategic problem. Furthermore, the algorithm is competitive with a metaheuristic published for the case of uncapacitated depots

Two-phase method and Lagrangian relaxation to solve the Bi-Objective Set Covering Problem

This paper deals with the Bi-Objective Set Covering Problem, which is a generalization of the well-known Set Covering Problem. The proposed approach is a two-phase heuristic method which has the particularity to be a constructive method using the primal-dual Lagrangian relaxation to solve single objective Set Covering problems. The results show that this algorithm finds several potentially supported and unsupported solutions. A comparison with an exact method (up to a medium size), shows that many Pareto-optimal solutions are retrieved and that the other solutions are well spread and close to the optimal ones. Moreover, the method developed compares favorably with the Pareto Memetic Algorithm proposed by Jaszkiewicz

Multi-period profitable tour problem with electric vehicles and mandatory stops

15 páginasThe paper deals with a new variant of the profitable tour problem with electric vehicles. In order to avoid one of the main disadvantages encountered in this type of problem, i.e. the idle time imposed by recharging the battery, we propose a version where this operation is synchronized with lunch breaks. Such a policy requires multi-period agreements with clusters of restaurants. It leads to the multi-period profitable tour problem with electric vehicles and mandatory stops. This problem arises in scenarios of tourist trip design, blood mobile collection, or street marketing activities planning when the fleet is composed of electric vehicles. A mathematical model and a Branch-and-Price algorithm are proposed. In the solution method, the subproblem is solved following two different approaches, one exact approach using elementary paths and a relaxed approach allowing ng-paths. The numerical tests on instances with up to 100 clients and 3 periods show that both approaches produce excellent quality solutions in a very reasonable amount of time. © 2022 Taylor & Francis Group, LLC

Partager les livraisons dans un contexte de circuits courts alimentaires et de proximité

International audienceA food supply chain qualifies as "short and local" when it is characterized by a short physical distance between producers and consumers, with no more than a single intermediary between them. Such a configuration is referred to as the "short local food supply chain" (SLFSC). Our focus lies in examining the logistical problems associated with the SLFSC.Producers often set up organizations to simplify their logistical operations. For instance, they create producers's stores, design nodal points for third-party logistics operators to collect goods, or engage in reciprocal assistance. Our study focuses on the latter type of cooperation.We consider that a producer is authorized to transport goods from one another to customers. This practice is now possible in France for short distances, specific products and limited quantities. In the case where a customer C orders products from producers A and B, two collaborative cases may arise: producer A delivers to customer C after retrieving goods coming from producer B, or producer A drops off his own goods to producer B, and the latter delivers customer C.We model this new delivery sharing problem and present our first results