98 research outputs found

    Improving Ambulance Dispatching with Machine Learning and Simulation

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    As an industry where performance improvements can save lives, but resources are often scarce, emergency medical services (EMS) providers continuously look for ways to deploy available resources more efficiently. In this paper, we report a case study executed at a Dutch EMS region to improve ambulance dispatching. We first capture the way in which dispatch human agents currently make decisions on which ambulance to dispatch to a request. We build a decision tree based on historical data to learn human agents’ dispatch decisions. Then, insights from the fitted decision tree are used to enrich the commonly assumed closest-idle dispatch policy. Subsequently, we use the captured dispatch policy as input to a discrete event simulation to investigate two enhancements to current practices and evaluate their performance relative to the current policy. Our results show that complementing the current dispatch policy with redispatching and reevaluation policies yields an improvement of the on-time performance of highly urgent ambulance requests of 0.77% points. The performance gain is significant, which is equivalent to adding additional seven weekly ambulance shifts.</p

    FOCUSING ON CENTRALITY MEASURE IN EMERGENCY MEDICAL SERVICES

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    Emergency Medical Services (EMS) attracted many researchers because the demand of EMS was increasing over time. One of the major concerns of EMS is the response time and ambulance despatching is one of the vital factors which affects the response time. This paper focuses on the problem of ambulance despatching when many emergency calls emerge in a short time, which exists under the condition of catastrophic natural or manmade disasters. We modify a new method for ambulance despatching by centrality measure, this method constructs a nearest-neighbor coupled emergency call network and then prioritize those calls by the score of fitness, where the score of fitness considers two factors: centralized measure a call by the emergency call network and the closest policy which means despatching to the closest call site. This method is testified by a series of simulation experiments on the real topology road network of Hong Kong Island which contains 8 hospitals. These analyses demonstrate the real situation and proof the potential of centrality measure in reducing response time of EMS

    Analyse des politiques d’affectation d’un service prĂ©hospitalier d’urgence par simulation

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    RÉSUMÉ : Lorsqu’une urgence mĂ©dicale survient, le premier rĂ©flexe est de composer le numĂ©ro d’appel d’urgence. AussitĂŽt, un processus complexe s’enclenche menant Ă  l’arrivĂ©e d’une Ă©quipe de techniciens ambulanciers paramĂ©dics. Leurs interventions rapides peuvent Ă©viter des drames et sauver des vies. Les services prĂ©hospitaliers d’urgence (SPU) sont les organisations derriĂšre ces interventions d’urgence. Leur mission est de fournir des soins prĂ©hospitaliers et du transport ambulancier de qualitĂ©. La vitesse Ă  laquelle les SPU rĂ©pondent aux demandes, leurs temps de rĂ©ponse (TR), est un indicateur important de la qualitĂ© de leur service comme l’état de santĂ© des patients peut se dĂ©grader rapidement en l’absence de soins. De plus, mĂȘme pour les patients non urgents, des temps de rĂ©ponse courts sont dĂ©sirables comme les patients souhaitent recevoir de l’aide rapidement. L’objectif de ce mĂ©moire est de dĂ©velopper un modĂšle de simulation d’un SPU et de l’utiliser pour dĂ©velopper et pour tester des rĂšgles de gestion capables de rĂ©duire les temps de rĂ©ponse. Plus prĂ©cisĂ©ment, nous modĂ©lisons Urgences-santĂ©, le SPU responsable de MontrĂ©al et de Laval, et proposons plusieurs politiques pour amĂ©liorer leurs dĂ©cisions d’affectations. Le modĂšle est dĂ©veloppĂ© en Ă©troite collaboration avec le SPU permettant ainsi de bĂątir un modĂšle rĂ©aliste. L’affectation consiste normalement Ă  choisir l’ambulance Ă  attribuer Ă  chaque patient parmi celles disponibles. Nous proposons d’étendre cette dĂ©finition en considĂ©rant non seulement les ambulances disponibles, mais Ă©galement celles qui sont indisponibles. En effet, il est possible que ces ambulances occupĂ©es soient capables de rĂ©pondre Ă  un appel plus rapidement que les ambulances libres. Cette approche a Ă©tĂ© trĂšs peu considĂ©rĂ©e dans la littĂ©rature. Nous permettons l’affectation d’ambulances indisponibles dans trois cas : avant le dĂ©but des quarts de travail, pendant la pause repas et pendant le transfert de patient Ă  l’hĂŽpital. D’aprĂšs notre modĂšle, l’inclusion du premier et du troisiĂšme groupe dans l’affectation des appels de basses prioritĂ©s permet de rĂ©duire leurs TR de 4.2% et 7.3% respectivement. La deuxiĂšme mĂ©thode n’amĂ©liore pas les temps de rĂ©ponse que nous expliquons par la redondance entre la position des ambulances qui prennent leur pause repas avec celles des ambulances disponibles. De plus, nous proposons d’utiliser les ambulances nouvellement disponibles pour amĂ©liorer les affectations de basses prioritĂ©s ce qui mĂšne Ă  une diminution de leurs TR de 7.3%. Au meilleur de notre connaissance, nous sommes les premiers Ă  utiliser cette politique pour des appels de basses prioritĂ©s. Ces politiques peuvent ĂȘtre combinĂ©es, ce qui peut amener des diminutions des TR de basses prioritĂ©s allant jusqu’à 8.2%. L’effet de ces politiques sur les appels de hautes prioritĂ©s est nĂ©gligeable ou nul. Ces gains sont rĂ©alisĂ©s par rapport aux rĂšgles actuelles d’Urgences-santĂ© dont la politique d’affectation est dĂ©jĂ  sophistiquĂ©e. Ces rĂ©sultats nous amĂšnent Ă  recommander l’ajout de ces politiques Ă  leurs politiques. Elles pourraient Ă©galement ĂȘtre bĂ©nĂ©fiques Ă  d’autres SPU. Notre modĂšle de simulation a le potentiel d’ĂȘtre appliquĂ© Ă  des politiques de gestion des SPU autres que celles d’affectation. En effet, les politiques de localisation et de relocalisation, de sĂ©lection du centre hospitalier, de gestion des effectifs et de spĂ©cialisation des ressources pourraient ĂȘtre Ă©tudiĂ©es Ă  l’aide du modĂšle.----------ABSTRACT : When faced with a medical emergency, our first instinct is to call 911. This puts in motion a complex process that leads to the arrival of one or more teams of emergency responders. Their intervention can save lives and avoid tragedies. Behind the scenes, emergency medical services (EMS) manage these teams. The goal of these organizations is to provide quality emergency prehospital care. The response time (RT), defined as the time required to reach a patient, is a primary quality indicator, because patients’ conditions can deteriorate rapidly. Even for non-urgent requests, fast RT is important as patients expect a quick reaction. The goal of this thesis is to develop a simulation model of an EMS and to use it to measure the impact of new strategies on response time. The model is based on Urgences-santĂ©, the EMS for Montreal and Laval Islands. We propose and evaluate policies to improve their dispatching performance. The model was developed in collaboration with the Urgences-santĂ©, which maximises its fidelity. Dispatching policies define which ambulance among all available ambulances is chosen to answer a call. We extended this definition to include “near-to-be-available” ambulances as they are sometimes able to reach a call faster than currently available ambulances. This has sparely been done in the literature. Ambulances are considered “near-to-be-available” during three periods: before the beginning of a shift, during the team’s lunch breaks, and during transfer of care at the hospital. Using our simulation model, we found that considering the first and third groups in dispatching for low priority calls reduces RT by 4.2% and 7.3% respectively. Considering the second group did not yield improvement to RT, as the locations of ambulances during lunch breaks were too similar to the locations of available ambulances. In addition, we evaluated a wholly novel strategy to reducing RT based on replacing alreadydispatched ambulances with newly-available ambulances to replace ambulances assigned to low priority calls which reduces RT. To be best of our knowledge, this has never been done before. This policy reduced RT for low-priority requests by 7.3%. Combining those policies improved performance further, yielding RT reductions of up to 8.2% for low-priority calls. It is important to note that all evaluated policies had no or negligible impact on the RT for high-priority calls. We recommend the adoption of those policies to Urgences-santĂ©. They might also be applicable to other EMS systems. The simulation model applications are not limited to the evaluation of dispatching policies. It could be used to evaluate new policies for location and elocation, hospital selection, staff management, and resources specialization

    Dynamic Workflow-Engine

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    We present and assess the novel thesis that a language commonly accepted for requirement elicitation is worth using for configuration of business process automation systems. We suggest that Cockburn's well accepted requirements elicitation language - the written use case language, with a few extensions, ought to be used as a workflow modelling language. We evaluate our thesis by studying in detail an industrial implementation of a workflow engine whose workflow modelling language is our extended written use case language; by surveying the variety of business processes that can be expressed by our extended written use case language; and by empirically assessing the readability of our extended written use case language. Our contribution is sixfold: (i) an architecture with which a workflow engine whose workflow modelling language is an extended written use case language can be built, configured, used and monitored; (ii) a detailed study of an industrial implementation of use case oriented workflow engine; (iii) assessment of the expressive power of the extended written use case language which is based on a known pattern catalogue; (iv) another assessments of the expressive power of the extended written use case language which is based on an equivalence to a formal model that is known to be expressive; (v) an empirical evaluation in industrial context of the readability of our extended written use case language in comparison to the readability of the incumbent graphical languages; and (vi) reflections upon the state of the art, methodologies, our results, and opportunities for further research. Our conclusions are that a workflow engine whose workflow modelling language is an extended written use case language can be built, configured, used and monitored; that in an environment that calls upon an extended written use case language as a workflow modelling language, the transition between the modelling and verification state, enactment state, and monitoring state is dynamic; that a use case oriented workflow engine was implemented in industrial settings and that the approach was well accepted by management, workflow configuration officers and workflow participants alike; that the extended written use case language is quite expressive, as much as the incumbent graphical languages; and that in industrial context an extended written use case language is an efficient communication device amongst stakeholders

    Theories and Methods for the Emergency Rescue System

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    A framework for the characterization and analysis of software systems scalability

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    The term scalability appears frequently in computing literature, but it is a term that is poorly defined and poorly understood. It is an important attribute of computer systems that is frequently asserted but rarely validated in any meaningful, systematic way. The lack of a consistent, uniform and systematic treatment of scalability makes it difficult to identify and avoid scalability problems, clearly and objectively describe the scalability of software systems, evaluate claims of scalability, and compare claims from different sources. This thesis provides a definition of scalability and describes a systematic framework for the characterization and analysis of software systems scalability. The framework is comprised of a goal-oriented approach for describing, modeling and reasoning about scalability requirements, and an analysis technique that captures the dependency relationships that underlie typical notions of scalability. The framework is validated against a real-world data analysis system and is used to recast a number of examples taken from the computing literature and from industry in order to demonstrate its use across different application domains and system designs

    ProblÚmes de gestion de flottes de véhicules en temps réel

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    ThÚse numérisée par la Direction des bibliothÚques de l'Université de Montréal
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