A two-phase approach for periodic home health care planning

International audienceIn this paper, we study the problem of periodic vehicle routing encountered in Home Health Care (HHC). The problem can be considered as a Periodic Vehicle Routing Problem with Time Windows (PVRPTW). It consists in establishing a planning of visits to patients over a given time horizon so as to satisfy the adherence to the care plan while optimizing the routes used in each time period. One two-stage mathematical formulation of this problem is proposed. We then propose a Tabu Search (TS) and a MIP-based Neighborhood Search method to compute the weekly and daily plan, respectively. These approaches are tested on large size instances

The City Logistics Facility Location Problem

National audienceThe aim of this work is to propose a new model that we call the City Logistics Facility Location Problem (CLFLP). Our purpose when introducing the CLFLP, is to capture essential aspects of distribution in cities, while maintaining a reasonable level of genericity and simplicity in the defintion of the problem. Practically, this model was adapted to the case of the city of Marseilles (France) and inserted into a Decision Support System. With a more academic point of view, the model could serve as a cornerstone for the development of new models and methods for strategic issues in city logistics

A modeling approach for locating logistics platforms for fast parcels delivery in urban areas

International audienceThis study aims at defining a framework for optimizing, in a sustainable way (i.e. economical, eco-friendly and societal), the location of logistics platforms in urban areas. A first case study for our work is the city of Marseilles (France) which already has a logistics platform right in its centre (ARENC: 41362 m2 of warehouses and offices). In this abstract, we first provide a precise description of the problem we intend to solve. We then propose a mathematical model for representing it. Preliminary experimentations, based on the city of Marseilles, are then described; figures and preliminary results which are proposed for this first case study are obtained thanks to a decision-making software we have implemented. Conclusions and future works are finally drawn

Étude et résolution exacte de problèmes de transport à la demande avec qualité de service

In this thesis, we address vehicle routing problems deriving from on- demand transport systems (ODT). Such systems, combining taxi flexibility with public transport system advantages (grouping, price), seem well suited to the new mobility needs. We define and classify a large set of quality of service criteria. We select three of them among the most representative : the total distance traveled, the vehicle occupancy rate and the passenger wasted-time. We propose branch-and-price solution schemes for the three cases, under the assumption that demands are known in advance. The original quality of service objectives introduce non-standard features into the vehicle routing model, namely a multigraph and a fractional objective function, therefore inducing non-standard algorithms. This work is part of a multidisciplinary project managed by geographers. The implementation of an operational ODT in the Doubs Central area (France) is used as a testing ground for experimentations. For the practical use of this system, we propose an insertion heuristic in addition to the branch-and-price algorithm. A geomatic analysis of the interactions between quality of service criteria and the geographical area is carried out with a Geographic Information System, with a special focus on route shapes and route sinuosity measures.Nous étudions dans cette thèse un problème de construction de tournées de véhicules pour le transport de personnes à la demande (TAD) qui, combinant la souplesse des taxis à la capacité de regroupement des transports en commun, est une voie pour repenser nos pratiques en terme de mobilité. Après avoir défini puis classé plusieurs critères de qualité de service, nous en sélectionnons trois pour leur représentativité : la minimisation de la distance totale parcourue, la maximisation du taux de remplissage des véhicules et la minimisation du temps perdu en transport. La méthode d'optimisation utilisée est basée sur une approche par décomposition appelée génération de colonnes. Nous nous plaçons dans le cas statique où toutes les demandes sont connues par avance. L'adaptation de cette méthode exacte aux trois critères choisis induit des développements originaux, comme la modélisation du réseau par un p-graphe ou l'optimisation d'une fonction objectif fractionnaire. Cette étude est intégrée à un projet pluridisciplinaire piloté par des géographes qui a pour sujet d'expérimentation la mise en place d'un TAD opérationnel dans le Pays du Doubs Central (France). Un algorithme de résolution heuristique spécifique a été développé pour cette application. L'intégration des résultats des deux algorithmes à un Système d'Information Géographique permet une analyse des critères de qualité de service et de leurs interactions avec le territoire d'un point de vue géomatique. Il en découle une étude sur la forme des tournées et plus particulièrement sur différentes mesures de leur sinuosité

Online Large-Scale Taxi Assignment: Optimization and Learning

International audienceWe propose a solution method for online vehicle routing, which integrates a machine learning routine to improve tours’ quality. Our optimization model is based on the Bertsimas et al. (2019) re-optimization approach. Two separate routines are developed. The first one uses a neural network to produce realistic pick-up times for the customers to serve. The second one relies on Q-learning in addition to random walks for the construction of the backbone graph corresponding to the instance problem of each time step. The second routine gives improved results compared to the original approach

Consistent home health care problem

International audiencePas de résum