1,721,201 research outputs found
A branch-and-cut algorithm for the single truck and trailer routing problem with satellite depots
No full textIn the single truck and trailer routing problem with satellite depots (STTRPSD), a truck with a detachable trailer based at a main depot must serve the demand of a set of customers accessible only by truck. Therefore, before serving the customers, it is necessary to detach the trailer in an appropriate parking place (called either a satellite depot or a trailer point) and transfer goods between the truck and the trailer. This problem has applications in milk collection for farms that cannot be reached using large vehicles. In this work we present an integer programming formulation of the STTRPSD. This formulation is tightened with several families of valid inequalities for which we have developed different (exact and heuristic) separation procedures. Using these elements, we have implemented a branch-and-cut algorithm for the solution of the STTRPSD. A computational experiment with published instances shows that the proposed branch-and-cut algorithm consistently solves problems with up to 50 customers and 10 satellite depots, and it has also been able to solve instances with up to 20 satellite depots and 100 clustered customers
Models and optimization approaches for logistic problems in health care systems and services sector
No full textCette thèse aborde le problème de tournées de véhicules (VRP) intégrant des contraintes temporelles : fenêtres de temps (TW), synchronisation (S) et précédence (P), appliqué au secteur de soins à domicile, donnant le VRPTW-SP. Il s’agit d’établir un plan de visite journalier des soignants, aux domiciles des patients ayant besoin d’un ou plusieurs services. Tout d’abord, nous avons abordé ce problème sous angle mono-objectif. Ensuite, le cas bi-objectif est considéré. Pour la version mono-objectif, un Programme Linéaire à Variables Mixtes Entières (PLME), deux heuristiques constructives, deux procédures de recherches locales et trois métaheuristiques à base de voisinages sont proposés : une procédure de recherche constructive adaptative randomisée (GRASP), une recherche locale itérée (ILS) et une approche hybride (GRASP × ILS). Concernant le cas bi-objectif, différentes versions de métaheuristiques évolutionnaires multi-objectifs sont proposées, intégrant différentes recherches locales : l’algorithme génétique avec tri par non-dominance version 2 (NSGAII), une version généralisée de ce dernier avec démarrages multiples (MS-NSGAII) et une recherche locale itérée avec tri par non-dominance (NSILS). Ces algorithmes ont été testés et validés sur des instances adaptées de la littérature. Enfin, nous avons étendu le VRPTW-SP sur un horizon de planification, donnant le VRPTW-SP multi-période. Pour résoudre cette extension, un PLME ainsi qu’une matheuristique sont proposésThis work addresses the vehicle routing problem (VRP) including timing constraints: time windows (TW), synchronization (S) and precedence (P), applied in Home Health Care sector; giving the VRPTW-SP. This problem consists in establishing a daily caregivers planning to patients' homes asking for one or several services. We have started by considering the problem as a single objective case. Then, a bi-objective version of the problem is introduced. For solving the single-objective problem, a Mixed Integer Linear Program (MILP), two constructive heuristics, local search procedures and three local search based metaheuristics are proposed : a Greedy Randomized Adaptive Search procedure (GRASP), an Iterated Local Search (ILS) and a hybrid approach (GRASP × ILS). Regarding the bi-objective VRPTW-SP, different versions of multi-objective evolutionary algorithm, including various local research strategies are proposed: the Non-dominated Sorting Genetic Algorithm version 2 (NSGAII), a generalized version of this latter with multiple restarts (MS-NSGAII) and an Iterated Local Search combined with the Non-dominated Sorting concept (NSILS). All these algorithms have been tested and validated on appropriate instances adapted from the literature. Finally, we extended the VRPTW-SP on a multi-period planning horizon and then proposed a MILP and a matheuristic approac
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Modelling and optimization of biomass supply chains for biorefineries
No full textLes travaux de cette thèse concernent la modélisation et l'optimisation de chaînes d’approvisionnement en biomasses pour de futures bio-raffineries. En effet, des chaînes d'approvisionnement efficaces sont essentielles pour fournir aux installations de conversion, de façon régulière, des quantités suffisantes de biomasse de qualité à des prix raisonnables. Le problème est tout d'abord décrit puis modélisé.Un modèle de réseau et un modèle de données sont ensuite développés pour permettre de décrire la structure de la chaîne d'approvisionnement et ses données, sans affecter le modèle mathématique sous-jacent. Ce dernier (MILP) combine pour la première fois divers aspects, soit originaux, soit gérés séparément dans la littérature. A partir des demandes de la raffinerie, une résolution exacte précise les activités logistiques dans le réseau et les équipements nécessaires, afin de minimiser le coût total composé des coûts de récoltes, de transport et de stockage. Des études de cas sont décrites pour illustrer ce modèle de planification tactique multi-biomasse et multi-période. Un modèle plus compact est aussi élaboré pour traiter des instances de très grandes tailles. Il est illustré par une étude de cas réelle pour une bio-raffinerie prévue près de Compiègne. Pour finir, les développements effectués pour la mise en place d’un prototype logiciel d’aide à la décision sont présentés et des recommandations d’un futur logiciel commercial sont proposéesThe research works of this thesis address the problem of modeling and optimizing biomass supply chains for biorefineries. Indeed, efficient supply chains are essential to provide conversion facilities with sufficient quantities of quality biomass at reasonable prices. The problem is described and modeled.A network model and a data model are developed to allow to describe the structure of the supply chain and its data, without affecting the underlying mathematical model. The latter is a mixed-integer linear programming that combines for the first time various aspects, either original or tackled separately in the literature. For given refinery needs, its exact resolution by CPLEX specifies the logistic activities in the network (amounts harvested, baled, transported, stored etc.) and the necessary equipment, in order to minimize a total cost including harvesting costs, transport costs and storage costs. Case studies are described to illustrate this multi-biomass and multi-period tactical planning model.A more compact model is also elaborated to cope with large-scale instances. It is illustrated using a real case study for a bio-refinery planned near Compiègne, France.Finally, the developments conducted for the implementation of a prototype of decision-support application are presented and recommendations for coming to a commercial software are propose
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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