1,721,002 research outputs found
Ordonnancement dynamique des patients dans les services d'urgence
No full textUn service d'urgence (SU) représente la porte d'entrée de chaque établissement de soins. Il est ouvert 24 heures sur 24 et 7 jours sur 7. Au cours des dernières années, les SU bénéficient d'une attention particulière de la part des décideurs. L'objectif est d'améliorer la qualité des services fournis aux patients.Cette thèse se concentre sur la planification des patients au SU. Après une revue de la littérature détaillée, le problème que nous traitons peut être considéré comme un problème de Job Shop Hybride (HJSP). L'objectif est de trouver un planning qui minimise le temps total d'achèvement ou le makespan. Il s'agit d'un problème d'optimisation combinatoire NP-hard. Ainsi, nous avons développé et validé un algorithme génétique (GA) et un algorithme génétique hybride (HGA) en les testant sur des benchmarks de la littérature issus du domaine industriel. Les performances obtenues ont été comparées avec celles des approches HJSP existantes.Ensuite, nous avons adapté et appliqué les deux algorithmes pour planifier les patients dans un service d'urgence d'un hôpital tunisien, dans lequel nous avons collecté des données. L'objectif est de minimiser le temps d'attente des patients en tenant compte de leur catégorie d'urgence. Une attention particulière est portée aux catégories de patients critiques qui doivent être rapidement pris en charge par une équipe médicale. Dans un premier temps, nous n'avons considéré que les patients programmés à l'avance et nous avons simulé plusieurs scénarios pour vérifier et mesurer l'efficacité de nos approches, en supposant que toutes les données sont parfaitement connues. Dans un second temps, compte tenu de toute la réalité d'un service d'urgence (c'est-à-dire avec des événements dynamiques), nous avons pris en compte les incertitudes liées à l'arrivée des patients et à la durée du traitement dispensé par les soignants. Enfin, nous avons considéré des patients non-programmés dont les arrivées sont imprévisibles. Pour faire face à ces événements dynamiques, nous avons étudié une stratégie de planification prédictive et réactive basée sur les algorithmes développés. Toutes les approches ont été testées par rapport à la stratégie existante basée sur le principe du «premier arrivé, premier servi» combiné à une règle de priorité de catégorie que l'on retrouve généralement dans les services d'urgence. Les résultats montrent que nos approches proposées améliorent la stratégie adoptée par l'hôpital lorsque le taux de patients dynamiques est inférieure à 50%.An Emergency Department (ED) represents the gateway to every health care center. It opens 24 hours per day and 7 days per week. During the last years, the ED have benefited special attention. The goal is to offer a better quality of service to the patient. In fact, the number of visits to EDs has greatly increased causing overcrowding and dissatisfaction of patients. Improving its efficiency as well as patients' treatment is a significant challenge.This thesis focus on the scheduling of patients in ED. The problem is considered as a Hybrid Job Shop Problem (HJSP). The objective is to find a schedule that minimizes the total completion time or the makespan. This problem is an NP-hard combinatorial optimization problem. So, we developed and validated a Genetic Algorithm (GA) and a Hybrid Genetic Algorithm (HGA) by testing them on benchmarks found in the literature on manufacturing systems. The performances obtained were compared to existing HJSP approaches of the literature.Then, we adapted and applied both algorithms to plan patient journeys in a Tunisian hospital ED, in which, we collected data. In ED, the objective is to minimize patient waiting times in order to reduce the problem of overcrowding while taking into account the categories of patients. Particular attention must be paid to the categories of critical patients who must be quickly taken care of by a team. Initially, we only considered the expected patients and we simulated several scenarios to verify and measure the effectiveness of an approach based on patient categories, assuming that all data are perfectly known. Then, in a second step, considering all the reality of an emergency (i.e. with dynamics events), we took into account the uncertainties related to the patient arrivals and the duration of treatment provided by caregivers. Finally, we considered unexpected patients whose arrivals are unpredictable. To deal with these dynamic events, we studied a predictive and reactive planning strategy based on the previous algorithms. All the approaches were tested compared to the existing strategy based on the principle of "first come, first served" combined with a category priority rule which is usually found in emergency services. Results show that our approaches can improve the usual strategy when the rate of dynamic patients is under 50%
Vers des systèmes de transport sûrs et sains dans des environnements dynamiques
No full textLes évolutions importantes dans le domaine du transport et de la logistique ont considérablement amélioré la vie des gens et influencé les performances de tous les secteurs économiques. Néanmoins, ils peuvent aussi avoir des effets négatifs. En effet, le trafic des véhicules contribue à la congestion, à la pollution et aux accidents. En outre, le transport de matériaux potentiellement dangereux présente un risque sérieux pour la sécurité des personnes et de l'environnement. Le problème du transport est généralement modélisé comme un problème de routage de véhicules (VRP). Compte tenu de la nature dynamique du problème du monde réel, le VRP statique ne pourrait pas être approprié puisque les informations sont susceptibles de varier au fil du temps et doivent être prises en compte par le décideur. Dans cette thèse, nous nous intéressons aux problèmes de transport dynamique.Dans un premier temps, nous étudions le problème de transport des matières dangereuses dans un environnement dynamique. Les objectifs sont la minimisation des coûts de transport et le risque lié aux transports des produits dangereux.La deuxième contribution de cette thèse a pour but de minimiser les coûts de transport et l'émission de dioxyde de carbone émis par les véhicules avec prise en compte des demandes dynamiques.Finalement, nous explorons le problème de la collecte des déchets et matières dangereuses liés aux activités de soins dans les hôpitaux. Dans ce contexte, nous proposons une approche d'optimisation des tournées pour collecter ces déchets. Également, la version dynamique de ce problème est étudiée. Comme cas pratique, nous avons appliqué l'approche proposée sur un réseau d'hôpitaux dans la région de Tunis.The significant advances in transportation and logistics have greatly improved people's lives and influenced the performance of all economic sectors. Nevertheless, it can also produce negative impacts. In fact, vehicle traffic contributes to congestion, pollution, and accidents. Besides, the transportation of highly toxic materials poses a serious safety risk to humans or to environment. The transportation problem is usually modeled as a vehicle routing problem (VRP). Considering the dynamic nature of the real-world problem, static variants of VRP could not be appropriate since the information are subject to change over time and have to be taken into account by the decision maker. In this thesis, we are particularly interested to design safe and healthy transportation systems in dynamic situations in order to protect human being and environment.First, we study the problem of transporting Haz-Mat in a dynamic environment. The objectives are the minimization of the transport costs and risk related to the transport of Haz-Mat.The second contribution of this thesis deals with the minimization of the transportation cost and the carbon dioxide emission caused by the vehicles while servicing a set of customers that occurred over time.Finally, we explore waste collection in hospitals. This is an important and complex problem taking into account the generated hazardous health care waste (HCW). Thus, we propose a method for optimizing the collections of these wastes by separating the non-hazardous wastes from the hazardous wastes. Besides, we study the dynamic version of this problem. As a practical case, we have used this approach to collect the HCW from a set of hospitals in the region of Tunis
Graph-related optimization and decision support systems
No full textConstrained optimization is a challenging branch of operations research that aims to create a model which has a wide range of applications in the supply chain, telecommunications and medical fields. As the problem structure is split into two main components, the objective is to accomplish the feasible set framed by the system constraints. The aim of this book is expose optimization problems that can be expressed as graphs, by detailing, for each studied problem, the set of nodes and the set of edges. This graph modeling is an incentive for designing a platform that integrates all optimizati
Exact and approximate approaches for the Pareto front generation of the single path multicommodity ?ow problem
No full textGoing 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
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
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