Littérature scientifique sur le sujet « Infrastructures à large échelle »
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Articles de revues sur le sujet "Infrastructures à large échelle"
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Frossard, Etienne. « La mécanique dissipative des géo-matériaux granulaires et ses applications pratiques en Génie Civil ». Revue Française de Géotechnique, no 167 (2021) : 2. http://dx.doi.org/10.1051/geotech/2021007.
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L’article, résultant d’un travail de long terme sur la physique des géo-matériaux granulaires et la pratique du génie civil de grandes infrastructures, synthétise une vision nouvelle du comportement mécanique de ces matériaux, à partir d’approches dissipatives micromécaniques originales. Après le contexte et les hypothèses-clé, il présente les aspects essentiels des structures dissipatives induites par la friction de contact élémentaire, associée à des spécificités de mécanique statistique dans ces matériaux en mouvement quasi-statique, et leur expression multi-échelle par des relations tensorielles fortes : les équations de la dissipation d’énergie résultant de la friction. Sur cette base, est ensuite établi un large ensemble de propriétés pratiques d’usage général en génie civil, incluant : le critère de rupture, le couplage résistance au cisaillement/variations de volume, la compaction cyclique, l’équilibre géostatique « au repos »… Bien que l’essentiel de l’article soit focalisé sur les caractères induits par la friction de contact, une dernière section présente d’autres propriétés-clé induites par la rupture des granulats, autre processus dissipatif après la friction de contact. Ces propriétés incluent des incidences explicites sur les effets d’échelle dans le comportement structural d’ouvrages, vérifiées sur de grands ouvrages.
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Le Néchet, Florent. « Approche multiscalaire de la mobilité domicile-travail en Île-de-France et dans la région Rhin-Ruhr ». Cahiers de géographie du Québec 56, no 158 (28 février 2013) : 405–26. http://dx.doi.org/10.7202/1014553ar.
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Résumé L’étude des liens entre forme urbaine, accessibilité aux infrastructures de transport et pratiques de mobilité quotidienne est abordée à travers le prisme d’une échelle de fonctionnement intermédiaire, entre l’échelon local et l’échelon de l’aire fonctionnelle entière, traditionnellement étudiés. Une méthodologie générique de construction de bassins d’emplois est détaillée, puis appliquée aux espaces métropolitains de Paris et de la région Rhin-Ruhr. La mobilité quotidienne (utilisation des différents modes de transport, distances parcourues, part de trajets réalisés localement) est alors analysée à cette échelle intermédiaire, avec insistance sur la pertinence de mesures d’accessibilité à chacun des niveaux distingués.
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Loye, Nathalie. « Panorama des programmes actuels d’enquêtes à large échelle ». Mesure et évaluation en éducation 34, no 2 (6 mai 2014) : 3–24. http://dx.doi.org/10.7202/1024847ar.
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L’objet du premier article de ce numéro spécial est de présenter les caractéristiques relatives à la population visée, à la fréquence de passation et aux types de données récoltées dans douze programmes d’enquêtes à large échelle. Les objectifs des versions les plus récentes de ces programmes sont détaillées ainsi que la manière dont les disciplines sont évaluées.
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Dierendonck, Christophe, et Annick Fagnant. « Approche par compétences et évaluation à large échelle : deux logiques incompatibles ? » Mesure et évaluation en éducation 37, no 1 (18 janvier 2016) : 43–82. http://dx.doi.org/10.7202/1034583ar.
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Depuis les années 1990, un changement de paradigme s’opère dans la plupart des systèmes d’éducation : le pilotage centré sur les ressources investies (inputs) se transforme progressivement en un pilotage centré sur les résultats (outputs). C’est dans ce contexte que se sont développés les dispositifs d’évaluation externe à large échelle des acquis scolaires des élèves, tant au niveau international (comme PIRLS et PISA) qu’au niveau national ou même au niveau local. En parallèle, l’approche par compétences a été instaurée progressivement dans les référentiels scolaires et les classes. Basée sur un travail au départ de tâches complexes, l’approche par compétences n’est cependant pas sans poser certains problèmes sur le plan de l’évaluation. Certains auteurs affirment même que les évaluations externes à large échelle et l’approche par compétences présentent des logiques contradictoires et que, dès lors, les deux éléments sont inconciliables. L’objectif de cet article est de nuancer ce genre d’affirmations en rendant compte d’un dispositif d’évaluation exploratoire à large échelle combinant une évaluation « classique » (constitué d’un nombre important d’items à corriger de façon standardisée) et une évaluation de compétences à visée diagnostique (tâches complexes, tâches complexes décomposées et tâches élémentaires associées).
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Delprat-Jannaud, Florence. « Le captage et le stockage du CO2 ». Reflets de la physique, no 77 (février 2024) : 78–85. http://dx.doi.org/10.1051/refdp/202477078.
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Le captage et le stockage géologique du gaz carbonique ne sont pas des technologies nouvelles : le captage et la séparation du CO2 sont appliqués dans l’industrie depuis des décennies, et l’injection de CO2 est pratiquée depuis les années 1970 pour la récupération assistée du pétrole. Toutefois, des verrous restent à lever pour leur déploiement à grande échelle. Cet article propose une revue des technologies existantes, qu’elles soient matures ou en cours de développement, ainsi qu’une discussion sur les enjeux à adresser : réduction des couts et de la pénalité énergétique pour le captage du CO2, mutualisation des infrastructures pour le transport, démonstration de la faisabilité du stockage massif ainsi que perspectives en matière d’utilisation.
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Dupeux, Grégory, et Yvonnick Favreau. « Diagnostic à large échelle du colmatage des cours d'eau ». La Houille Blanche, no 6 (décembre 2017) : 25–29. http://dx.doi.org/10.1051/lhb/2017053.
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François, Jérôme, Radu State et Olivier Festor. « Botnets IRC et P2P pour une supervision à large échelle ». Techniques et sciences informatiques 28, no 4 (30 avril 2009) : 433–58. http://dx.doi.org/10.3166/tsi.28.433-458.
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Amra, C., C. Deumié, J. Y. Natoli et M. Commandré. « Topographie multi-échelle pour le filtrage optique multicouche large-bande ». Le Journal de Physique IV 11, PR7 (octobre 2001) : Pr7–53—Pr7–56. http://dx.doi.org/10.1051/jp4:2001719.
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Haldar, Achintya. « Reliable engineering computations of large infrastructures ». International Journal of Reliability and Safety 9, no 2/3 (2015) : 92. http://dx.doi.org/10.1504/ijrs.2015.072714.
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Blanchard, Elodie, Philippe Birnbaum, Christophe Proisy, Thomas Ibanez, Hervé Vandrot, Claire Chambrey, Vanessa Hequet et Pierre Couteron. « Prédire la structure des forêts tropicales humides calédoniennes : analyse texturale de la canopée sur des images Pléiades ». Revue Française de Photogrammétrie et de Télédétection, no 209 (29 janvier 2015) : 141–47. http://dx.doi.org/10.52638/rfpt.2015.226.
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Cartographier et classifier les forêts denses humides (FDH) selon une typologie structurale objective est un enjeu majeur pour leur conservation et leur gestion. Les principales contraintes dans l'étude des FTH sont dues à leur forte hétérogénéité et à leur faible accessibilité. Les images satellites Pléiades offrent de nouvelles opportunités pour l'étude, à large échelle, de l'organisation structurale de ces forêts. Dans cet article nous avons évalué à travers une étude de cas en Nouvelle-Calédonie leur potentiel pour construire une typologie des FDH à partir d'une analyse de texture de la canopée. La méthode FOTO (FOurier-based Textural Ordination) a été appliquée à des images à très haute résolution spatiale pour produire des indices de texture de la canopée. Les résultats ont montré que cette méthode était prometteuse pour, d'une part isoler la FDH des autres formations végétales, et d'autre part mettre en évidence leur diversité structurale à large échelle. .
Thèses sur le sujet "Infrastructures à large échelle"
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Quesnel, Flavien. « Vers une gestion coopérative des infrastructures virtualisées à large échelle : le cas de l'ordonnancement ». Phd thesis, Ecole des Mines de Nantes, 2013. http://tel.archives-ouvertes.fr/tel-00821103.
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Les besoins croissants en puissance de calcul sont généralement satisfaits en fédérant de plus en plus d'ordinateurs (ou noeuds) pour former des infrastructures distribuées. La tendance actuelle est d'utiliser la virtualisation système dans ces infrastructures, afin de découpler les logiciels des noeuds sous-jacents en les encapsulant dans des machines virtuelles. Pour gérer efficacement ces infrastructures virtualisées, de nouveaux gestionnaires logiciels ont été mis en place. Ces gestionnaires sont pour la plupart hautement centralisés (les tâches de gestion sont effectuées par un nombre restreint de nœuds dédiés). Cela limite leur capacité à passer à l'échelle, autrement dit à gérer de manière réactive des infrastructures de grande taille, qui sont de plus en plus courantes. Au cours de cette thèse, nous nous sommes intéressés aux façons d'améliorer cet aspect ; l'une d'entre elles consiste à décentraliser le traitement des tâches de gestion, lorsque cela s'avère judicieux. Notre réflexion s'est concentrée plus particulièrement sur l'ordonnancement dynamique des machines virtuelles, pour donner naissance à la proposition DVMS (Distributed Virtual Machine Scheduler). Nous avons mis en œuvre un prototype, que nous avons validé au travers de simulations (notamment via l'outil SimGrid), et d'expériences sur le banc de test Grid'5000. Nous avons pu constater que DVMS se montrait particulièrement réactif pour gérer des infrastructures virtualisées constituées de dizaines de milliers de machines virtuelles réparties sur des milliers de nœuds. Nous nous sommes ensuite penchés sur les perspectives d'extension et d'amélioration de DVMS. L'objectif est de disposer à terme d'un gestionnaire décentralisé complet, objectif qui devrait être atteint au travers de l'initiative Discovery qui fait suite à ces travaux.
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Rais, Issam. « Discover, model and combine energy leverages for large scale energy efficient infrastructures ». Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN051/document.
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La consommation énergétique de nos entités de calculs à grande échelle est une problématique de plus en plus inquiétante. Il est d'autant plus inquiétant que nous nous dirigeons vers "L'exascale",machine qui calcule 10^18 opérations flottantes par secondes, soit 10 fois plus que les meilleurs machines publiques actuelles. En 2017, les data-center consommaient 7% de la demande globale et étaient responsable de 2% de l’émission globale de CO2. Avec la multiplication actuelle du nombre d'outils connectés par personne, réduire la consommation énergétique des data-centers et supercalculateurs à grande échelle est une problématique cruciale pour construire une société numérique durable.Il est donc urgent de voir la consommation énergétique comme une problématique phare de cescentres. De nombreuses techniques, ici nommé "levier", ont été développées dans le but de réduire la consommation électrique des centres de calculs, à différents niveaux : infrastructure, matériel, intergiciel et applicatif. Bien utiliser ces leviers est donc capitale pour s'approcher de l'efficience énergétique. Un grand nombre de leviers sont disponibles dans ces centres de calculs. Malgré leurs gains potentiels, il peut être compliqué de bien les utiliser mais aussi d'en combiner plusieurs en restant efficace en énergie.Dans cette thèse, nous avons abordé la découverte, compréhension et usage intelligent des leviers disponibles à grande échelle dans ces centres de calculs. Nous avons étudié des leviers de manière indépendante, puis les avons combinés à d'autres leviers afin de proposer une solution générique et dynamique à l'usage combiné des leviersEnergy consumption is a growing concern on the verge of Exascale computing, a machine reaching 10^18 operations per seconds, 10 times the actual best public supercomputers, it became a crucial focus. Data centers consumed about 7% of total demand of electricity and are responsible of 2% of global carbon emission. With the multiplication of connected devices per person around the world, reducing the energy consumption of large scale computing system is a mandatory step to address in order to build a sustainable digital society.Several techniques, that we call leverage, have been developed in order to lower the electricalconsumption of computing facilities. To face this growing concern many solutions have beendeveloped at multiple levels of computing facilities: infrastructure, hardware, middle-ware, andapplication.It is urgent to embrace energy efficiency as a major concern of our modern computing facilities. Using these leverages is mandatory to better energy efficiency. A lot of leverages are available on large scale computing center. In spite of their potential gains, users and administrators don't fully use them or don't use them at all to better energy efficiency. Although, using these techniques, alone and combined, could be complicated and counter productive if not wisely used.This thesis defines and investigates the discovery, understanding and smart usage of leverages available on a large scale data center or supercomputer. We focus on various single leverages and understand them. We then combine them to other leverages and propose a generic solution to the dynamic usage of combined leverages
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Moise, Diana Maria. « Optimizing data management for MapReduce applications on large-scale distributed infrastructures ». Thesis, Cachan, Ecole normale supérieure, 2011. http://www.theses.fr/2011DENS0067/document.
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Les applications data-intensive sont largement utilisées au sein de domaines diverses dans le but d'extraire et de traiter des informations, de concevoir des systèmes complexes, d'effectuer des simulations de modèles réels, etc. Ces applications posent des défis complexes tant en termes de stockage que de calcul. Dans le contexte des applications data-intensive, nous nous concentrons sur le paradigme MapReduce et ses mises en oeuvre. Introduite par Google, l'abstraction MapReduce a révolutionné la communauté intensif de données et s'est rapidement étendue à diverses domaines de recherche et de production. Une implémentation domaine publique de l'abstraction mise en avant par Google, a été fournie par Yahoo à travers du project Hadoop. Le framework Hadoop est considéré l'implémentation de référence de MapReduce et est actuellement largement utilisé à des fins diverses et sur plusieurs infrastructures. Nous proposons un système de fichiers distribué, optimisé pour des accès hautement concurrents, qui puisse servir comme couche de stockage pour des applications MapReduce. Nous avons conçu le BlobSeer File System (BSFS), basé sur BlobSeer, un service de stockage distribué, hautement efficace, facilitant le partage de données à grande échelle. Nous étudions également plusieurs aspects liés à la gestion des données intermédiaires dans des environnements MapReduce. Nous explorons les contraintes des données intermédiaires MapReduce à deux niveaux: dans le même job MapReduce et pendant l'exécution des pipelines d'applications MapReduce. Enfin, nous proposons des extensions de Hadoop, un environnement MapReduce populaire et open-source, comme par example le support de l'opération append. Ce travail inclut également l'évaluation et les résultats obtenus sur des infrastructures à grande échelle: grilles informatiques et cloudsData-intensive applications are nowadays, widely used in various domains to extract and process information, to design complex systems, to perform simulations of real models, etc. These applications exhibit challenging requirements in terms of both storage and computation. Specialized abstractions like Google’s MapReduce were developed to efficiently manage the workloads of data-intensive applications. The MapReduce abstraction has revolutionized the data-intensive community and has rapidly spread to various research and production areas. An open-source implementation of Google's abstraction was provided by Yahoo! through the Hadoop project. This framework is considered the reference MapReduce implementation and is currently heavily used for various purposes and on several infrastructures. To achieve high-performance MapReduce processing, we propose a concurrency-optimized file system for MapReduce Frameworks. As a starting point, we rely on BlobSeer, a framework that was designed as a solution to the challenge of efficiently storing data generated by data-intensive applications running at large scales. We have built the BlobSeer File System (BSFS), with the goal of providing high throughput under heavy concurrency to MapReduce applications. We also study several aspects related to intermediate data management in MapReduce frameworks. We investigate the requirements of MapReduce intermediate data at two levels: inside the same job, and during the execution of pipeline applications. Finally, we show how BSFS can enable extensions to the de facto MapReduce implementation, Hadoop, such as the support for the append operation. This work also comprises the evaluation and the obtained results in the context of grid and cloud environments
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Pastor, Jonathan. « Contributions à la mise en place d'une infrastructure de Cloud Computing à large échelle ». Thesis, Nantes, Ecole des Mines, 2016. http://www.theses.fr/2016EMNA0240/document.
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La croissance continue des besoins en puissance de calcul a conduit au triomphe du modèle de Cloud Computing. Des clients demandeurs en puissance de calcul vont s’approvisionner auprès de fournisseurs d’infrastructures de Cloud Computing, mises à disposition via Internet. Pour réaliser des économies d’échelles, ces infrastructures sont toujours plus grandes et concentrées en quelques endroits, conduisant à des problèmes tels que l’approvisionnement en énergie, la tolérance aux pannes et l’éloignement des utilisateurs. Cette thèse s’est intéressée à la mise en place d’un système d’IaaS massivement distribué et décentralisé exploitant un réseau de micros centres de données déployés sur la dorsale Internet, utilisant une version d’OpenStack revisitée pendant cette thèse autour du support non intrusif de bases de données non relationnelles. Des expériences sur Grid’5000 ont montré des résultats intéressants sur le plan des performances, toutefois limités par le fait qu’OpenStack ne tirait pas avantage nativement d’un fonctionnement géographiquement réparti. Nous avons étudié la prise en compte de la localité réseau pour améliorer les performances des services distribués en favorisant les collaborations proches. Un prototype de l’algorithme de placement de machines virtuelles DVMS, fonctionnant sur une topologie non structurée basée sur l’algorithme Vivaldi, a été validé sur Grid’5000. Ce prototype a fait l’objet d’un prix scientifique lors de l’école de printemps Grid’50002014. Enfin, ces travaux nous ont amenés à participer au développement du simulateur VMPlaceSThe continuous increase of computing power needs has favored the triumph of the Cloud Computing model. Customers asking for computing power will receive supplies via Internet resources hosted by providers of Cloud Computing infrastructures. To make economies of scale, Cloud Computing that are increasingly large and concentrated in few attractive places, leading to problems such energy supply, fault tolerance and the fact that these infrastructures are far from most of their end users. During this thesis we studied the implementation of an fully distributed and decentralized IaaS system operating a network of micros data-centers deployed in the Internet backbone, using a modified version of OpenStack that leverages non relational databases. A prototype has been experimentally validated onGrid’5000, showing interesting results, however limited by the fact that OpenStack doesn’t take advantage of a geographically distributed functioning. Thus, we focused on adding the support of network locality to improve performance of Cloud Computing services by favoring collaborations between close nodes. A prototype of the DVMS algorithm, working with an unstructured topology based on the Vivaldi algorithm, has been validated on Grid’5000. This prototype got the first prize at the large scale challenge of the Grid’5000 spring school in 2014. Finally, the work made with DVMS enabled us to participate at the development of the VMPlaceS simulator
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Esteves, José Jurandir Alves. « Optimization of network slice placement in distributed large-scale infrastructures : from heuristics to controlled deep reinforcement learning ». Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS325.
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Cette thèse examine comment optimiser le placement de tranches (slices) de réseau dans les infrastructures distribuées à grande échelle en se concentrant sur des approches heuristiques en ligne et basées sur l'apprentissage par renforcement profond (DRL). Tout d'abord, nous nous appuyons sur la programmation linéaire en nombre entiers (ILP) pour proposer un modèle de données permettant le placement de tranches de réseau sur le bord et le cœur du réseau. Contrairement à la plupart des études relatives au placement de fonctions réseau virtualisées, le modèle ILP proposé prend en compte les topologies complexes des tranches de réseau et accorde une attention particulière à l'emplacement géographique des utilisateurs des tranches réseau et à son impact sur le calcul de la latence de bout en bout. Des expérimentations numériques nous ont permis de montrer la pertinence de la prise en compte des contraintes de localisation des utilisateurs.Ensuite, nous nous appuyons sur une approche appelée "Power of Two Choices" pour proposer un algorithme heuristique en ligne qui est adapté à supporter le placement sur des infrastructures distribuées à grande échelle tout en intégrant des contraintes spécifiques au bord du réseau. Les résultats de l'évaluation montrent la bonne performance de l'heuristique qui résout le problème en quelques secondes dans un scénario à grande échelle. L'heuristique améliore également le taux d'acceptation des demandes de placement de tranches de réseau par rapport à une solution déterministe en ligne en utilisant l'ILP.Enfin, nous étudions l'utilisation de méthodes de ML, et plus particulièrement de DRL, pour améliorer l'extensibilité et l'automatisation du placement de tranches réseau en considérant une version multi-objectif du problème. Nous proposons d'abord un algorithme DRL pour le placement de tranches réseau qui s'appuie sur l'algorithme "Advantage Actor Critic" pour un apprentissage rapide, et sur les réseaux convolutionels de graphes pour l'extraction de propriétés. Ensuite, nous proposons une approche que nous appelons "Heuristically Assisted DRL" (HA-DRL), qui utilise des heuristiques pour contrôler l'apprentissage et l'exécution de l'agent DRL. Nous évaluons cette solution par des simulations dans des conditions de charge de réseau stationnaire, ensuite cyclique et enfin non-stationnaire. Les résultats de l'évaluation montrent que le contrôle par heuristique est un moyen efficace d'accélérer le processus d'apprentissage du DRL, et permet d'obtenir un gain substantiel dans l'utilisation des ressources, de réduire la dégradation des performances et d'être plus fiable en cas de changements imprévisibles de la charge du réseau que les algorithmes DRL non contrôlésThis PhD thesis investigates how to optimize Network Slice Placement in distributed large-scale infrastructures focusing on online heuristic and Deep Reinforcement Learning (DRL) based approaches. First, we rely on Integer Linear Programming (ILP) to propose a data model for enabling on-Edge and on-Network Slice Placement. In contrary to most studies related to placement in the NFV context, the proposed ILP model considers complex Network Slice topologies and pays special attention to the geographic location of Network Slice Users and its impact on the End-to-End (E2E) latency. Extensive numerical experiments show the relevance of taking into account the user location constraints. Then, we rely on an approach called the “Power of Two Choices"(P2C) to propose an online heuristic algorithm for the problem which is adapted to support placement on large-scale distributed infrastructures while integrating Edge-specific constraints. The evaluation results show the good performance of the heuristic that solves the problem in few seconds under a large-scale scenario. The heuristic also improves the acceptance ratio of Network Slice Placement Requests when compared against a deterministic online ILP-based solution. Finally, we investigate the use of ML methods, more specifically DRL, for increasing scalability and automation of Network Slice Placement considering a multi-objective optimization approach to the problem. We first propose a DRL algorithm for Network Slice Placement which relies on the Advantage Actor Critic algorithm for fast learning, and Graph Convolutional Networks for feature extraction automation. Then, we propose an approach we call Heuristically Assisted Deep Reinforcement Learning (HA-DRL), which uses heuristics to control the learning and execution of the DRL agent. We evaluate this solution trough simulations under stationary, cycle-stationary and non-stationary network load conditions. The evaluation results show that heuristic control is an efficient way of speeding up the learning process of DRL, achieving a substantial gain in resource utilization, reducing performance degradation, and is more reliable under unpredictable changes in network load than non-controlled DRL algorithms
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Tsafack, Chetsa Ghislain Landry. « Profilage système et leviers verts pour les infrastructures distribuées à grande échelle ». Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2013. http://tel.archives-ouvertes.fr/tel-00925320.
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De nos jours, réduire la consommation énergétique des infrastructures de calcul à grande échelle est devenu un véritable challenge aussi bien dans le monde académique qu'industriel. Ceci est justifié par les nombreux efforts visant à réduire la consommation énergétique de ceux-ci. Ces efforts peuvent sans nuire à la généralité être divisés en deux groupes : les approches matérielles et les approches logicielles. Contrairement aux approches matérielles, les approches logicielles connaissent très peu de succès à cause de leurs complexités. En effet, elles se focalisent sur les applications et requièrent souvent une très bonne compréhension des solutions proposées et/ou de l'application considérée. Ce fait restreint leur utilisation à un nombre limité d'experts puisqu'en général les utilisateurs n'ont pas les compétences nécessaires à leurs implémentation. Aussi, les solutions actuelles en plus de leurs complexités de déploiement ne prennent en compte que le processeur alors que les composants tel que la mémoire, le stockage et le réseau sont eux aussi de gros consommateurs d'énergie. Cette thèse propose une méthodologie de réduction de la consommation énergétique des infrastructures de calcul à grande échelle. Elaborée en trois étapes à savoir : (i) détection de phases, (ii) caractérisation de phases détectées et (iii) identification de phases et reconfiguration du système ; elle s'abstrait de toute application en se focalisant sur l'infrastructure dont elle analyse le comportement au cours de son fonctionnement afin de prendre des décisions de reconfiguration. La méthodologie proposée est implémentée et évaluée sur des grappes de calcul à haute performance de tailles variées par le biais de MREEF (Multi-Resource Energy Efficient Framework). MREEF implémente la méthodologie de réduction énergétique de manière à permettre aux utilisateurs d'implémenter leurs propres mécanismes de reconfiguration du système en fonction des besoins. Les résultats expérimentaux montrent que la méthodologie proposée réduit la consommation énergétique de 24% pour seulement une perte de performance de moins de 7%. Ils montrent aussi que pour réduire la consommation énergétique des systèmes, on peut s'appuyer sur les sous-systèmes tels que les sous-systèmes de stockage et de communication. Nos validations montrent que notre méthodologie s'étend facilement à un grand nombre de grappes de calcul sensibles à l'énergie (energy aware). L'extension de MREEF dans les environnements virtualisés tel que le cloud montre que la méthodologie proposée peut être utilisée dans beaucoup d'autres environnements de calcul.
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Capizzi, Sirio <1980>. « A tuple space implementation for large-scale infrastructures ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/914/1/Tesi_Capizzi_Sirio.pdf.
Texte intégralRésumé :
Coordinating activities in a distributed system is an open research topic. Several models have been
proposed to achieve this purpose such as message passing, publish/subscribe, workflows or tuple
spaces. We have focused on the latter model, trying to overcome some of its disadvantages. In
particular we have applied spatial database techniques to tuple spaces in order to increase their
performance when handling a large number of tuples. Moreover, we have studied how structured
peer to peer approaches can be applied to better distribute tuples on large networks. Using some of
these result, we have developed a tuple space implementation for the Globus Toolkit that can be
used by Grid applications as a coordination service. The development of such a service has been
quite challenging due to the limitations imposed by XML serialization that have heavily influenced
its design. Nevertheless, we were able to complete its implementation and use it to implement two
different types of test applications: a completely parallelizable one and a plasma simulation that is
not completely parallelizable. Using this last application we have compared the performance of our
service against MPI. Finally, we have developed and tested a simple workflow in order to show the
versatility of our service.
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Capizzi, Sirio <1980>. « A tuple space implementation for large-scale infrastructures ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/914/.
Texte intégralRésumé :
Coordinating activities in a distributed system is an open research topic. Several models have been
proposed to achieve this purpose such as message passing, publish/subscribe, workflows or tuple
spaces. We have focused on the latter model, trying to overcome some of its disadvantages. In
particular we have applied spatial database techniques to tuple spaces in order to increase their
performance when handling a large number of tuples. Moreover, we have studied how structured
peer to peer approaches can be applied to better distribute tuples on large networks. Using some of
these result, we have developed a tuple space implementation for the Globus Toolkit that can be
used by Grid applications as a coordination service. The development of such a service has been
quite challenging due to the limitations imposed by XML serialization that have heavily influenced
its design. Nevertheless, we were able to complete its implementation and use it to implement two
different types of test applications: a completely parallelizable one and a plasma simulation that is
not completely parallelizable. Using this last application we have compared the performance of our
service against MPI. Finally, we have developed and tested a simple workflow in order to show the
versatility of our service.
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Quinson, Martin. « Méthodologies d'expérimentation pour l'informatique distribuée à large échelle ». Habilitation à diriger des recherches, Université de Lorraine, 2013. http://tel.archives-ouvertes.fr/tel-00927316.
Texte intégralRésumé :
Bien qu'omniprésents dans notre société, les systèmes informatiques distribués de très grande taille restent extrêmement difficiles à étudier et à évaluer. Ils agrègent des millions d'éléments hétérogènes dans des hiérarchies complexes afin de fournir une puissance de traitement et de stockage toujours accrue. Ces artéfacts, parmi les plus complexes jamais construits, posent un défi méthodologique nouveau en architecture des systèmes informatiques : l'approche réductionniste visant à expliquer le système au travers des interactions entre ses parties ne suffit plus à appréhender la complexité de ces systèmes. L'approche expérimentale s'impose alors avec une force nouvelle. Ce document présente mes recherches sur la résolution pratique de ces problèmes méthodologiques. La plupart de ces travaux ont été implémentés dans l'environnement SimGrid. Cet instrument scientifique permet l'étude des performances des systèmes distribués au travers de simulations réalistes. La première partie présente nos contributions aux performances de SimGrid grâce entre autres à une nouvelle approche de parallélisation des simulateurs de DES (Discrete-Event Systems). La seconde partie détaille nos travaux pour faire converger l'étude des performances et celle de la correction des systèmes au sein du même environnement, au travers de l'intégration d'un model checker complet à SimGrid. Enfin, nous étendons dans la troisième partie le champ d'application de SimGrid à des applications réelles.
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Griesner, Jean-Benoit. « Systèmes de recommandation de POI à large échelle ». Electronic Thesis or Diss., Paris, ENST, 2018. http://www.theses.fr/2018ENST0037.
Texte intégralRésumé :
La recommandation de points d’intérêts (POI) est une composante essentielle des réseaux sociaux géolocalisés. Cette tâche pose de nouveaux défis dûs aux contraintes spécifiques de ces réseaux. Cette thèse étudie de nouvelles solutions au problème de la recommandation personnalisée de POI. Trois contributions sont proposées dans ce travail. La première contribution est un nouveau modèle de factorisation de matrices qui intègre les influences géographique et temporelle. Ce modèle s’appuie sur un traitement spécifique des données. La deuxième contribution est une nouvelle solution au problème dit du feedback implicite. Ce problème correspond à la difficulté à distinguer parmi les POI non visités, les POI dont l’utilisateur ignore l’existence des POI qui ne l’intéressent pas. Enfin la troisième contribution de cette thèse est une méthode pour générer des recommandations à large échelle. Cette approche combine un algorithme de clustering géographique avec l’influence sociale des utilisateurs à différentes échelles de mobilitéThe task of points-of-interest (POI) recommendations has become an essential feature in location-based social networks. However it remains a challenging problem because of specific constraints of these networks. In this thesis I investigate new approaches to solve the personalized POI recommendation problem. Three main contributions are proposed in this work. The first contribution is a new matrix factorization model that integrates geographical and temporal influences. This model is based on a specific processing of geographical data. The second contribution is an innovative solution against the implicit feedback problem. This problem corresponds to the difficulty to distinguish among unvisited POI the actual "unknown" from the "negative" ones. Finally the third contribution of this thesis is a new method to generate recommendations with large-scale datasets. In this approach I propose to combine a new geographical clustering algorithm with users’ implicit social influences in order to define local and global mobility scales
Livres sur le sujet "Infrastructures à large échelle"
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Quesnel, Flavien. Scheduling of Large-Scale Virtualized Infrastructures. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118790335.
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L'enjeu capital(es) : Les métropoles de la grande échelle = Large-scale metropolises. Paris : Centre Pompidou, 2009.
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Rippa, Alessandro. Borderland Infrastructures. NL Amsterdam : Amsterdam University Press, 2020. http://dx.doi.org/10.5117/9789463725606.
Texte intégralRésumé :
Across the Chinese borderlands, investments in large-scale transnational infrastructure such as roads and special economic zones have increased exponentially over the past two decades. Based on long-term ethnographic research, Borderland Infrastructures addresses a major contradiction at the heart of this fast-paced development: small-scale traders have lost their historic strategic advantages under the growth of massive Chinese state investment and are now struggling to keep their businesses afloat. Concurrently, local ethnic minorities have become the target of radical resettlement projects, securitization, and tourism initiatives, and have in many cases grown increasingly dependent on state subsidies. At the juncture of anthropological explorations of the state, border studies, and research on transnational trade and infrastructure development, Borderland Infrastructures provides new analytical tools to understand how state power is experienced, mediated, and enacted in Xinjiang and Yunnan. In the process, Rippa offers a rich and nuanced ethnography of life across China’s peripheries.
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Chen, Hesheng, dir. Large Research Infrastructures Development in China : A Roadmap to 2050. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19368-2.
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Chen, Hesheng. Large Research Infrastructures Development in China : A Roadmap to 2050. Berlin, Heidelberg : Science Press, Beijing and Springer Berlin Heidelberg, 2011.
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Chwastowski, Janusz, et Krzysztof Korcyl. Wybrane zagadnienia technologii obliczeń wielkiej skali : Selected topics on large scale computing = Sujets sélectionnés sur l'informatique a grande échelle. Kraków : Wydawnictwo PK, 2013.
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Arts of VLSI circuit design : Symmetry approaches toward zero PVT sensitivity. [U.S.] : Xlibris Corporation, 2011.
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IABSE Symposium (2010 Venice, Italy). IABSE Symposium Venice 2010 : Large structures and infrastructures for environmentally constrained and urbanised areas : report = rapport = Bericht. Zürich : IABSE, 2010.
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Anthony, Fairall, et Woudt P. A. 1970-, dir. Nearby large-scale structures and the zone of avoidance : Proceedings of a meeting held in Cape Town, South Africa, 28 March - 2 April 2004. San Francisco, Calif : Astronomical Society of the Pacific, 2005.
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Canadian Conference on Very Large Scale Integration. CCVLSI '92 : Canadian Conference on Very Large Scale Integration = CCITGE '92 : Conférence Canadienne sur l'intégration à Très Grande Échelle : proceedings : October 18, 19, 20, 1992, Halifax, Nova Scotia, Canada. Kingston, Ont : Canadian Conference on Very Large Scale Integration, 1992.
Trouver le texte intégralChapitres de livres sur le sujet "Infrastructures à large échelle"
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Jiang, Lifen, Jiang Jiang, Junyi Liang, Kevin R. Wilcox, Scott L. Collins, Alan K. Knapp, William T. Pockman, Melinda D. Smith et Yiqi Luo. « Frontiers of Ecosystem Modeling and Large-Scale Experiments ». Dans Terrestrial Ecosystem Research Infrastructures, 137–62. Boca Raton, FL : CRC Press, 2017. : CRC Press, 2017. http://dx.doi.org/10.1201/9781315368252-8.
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Ahmed, Samar S., Marwan AlHeib, Yann Gunzburger et Vincent Renaud. « 3D Numerical Simulation of the Goaf Due to Large-Scale Longwall Mining ». Dans Sustainable Civil Infrastructures, 121–31. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-61905-7_11.
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Sauhats, Antans, Vladimir Chuvychin, Galina Bockarjova, Diana Zalostiba, Dmitrijs Antonovs et Roman Petrichenko. « Detection and Management of Large Scale Disturbances in Power System ». Dans Critical Information Infrastructures Security, 147–52. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-31664-2_15.
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Sampathirao, Ajay Kumar, Pantelis Sopasakis et Alberto Bemporad. « Decentralised Hierarchical Multi-rate Control of Large-Scale Drinking Water Networks ». Dans Critical Information Infrastructures Security, 45–56. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-31664-2_6.
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Poppe, Olav, Johan Sæbø et Petter Nielsen. « Architecting in Large and Complex Information Infrastructures ». Dans Lecture Notes in Business Information Processing, 90–104. Cham : Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-09546-2_7.
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Chen, Hesheng. « Large Research Infrastructures and National Innovation System ». Dans Large Research Infrastructures Development in China : A Roadmap to 2050, 5–15. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19368-2_2.
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Quesnel, Flavien. « Distributed Infrastructures Before the Rise of Virtualization ». Dans Scheduling of Large-Scale Virtualized Infrastructures, 1–12. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118790335.ch1.
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Quesnel, Flavien. « Contributions of Virtualization ». Dans Scheduling of Large-Scale Virtualized Infrastructures, 13–26. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118790335.ch2.
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Quesnel, Flavien. « Virtual Infrastructure Managers Used in Production ». Dans Scheduling of Large-Scale Virtualized Infrastructures, 27–47. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118790335.ch3.
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Quesnel, Flavien. « Comparative Study Between Virtual Infrastructure Managers and Distributed Operating Systems ». Dans Scheduling of Large-Scale Virtualized Infrastructures, 49–65. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118790335.ch4.
Texte intégralActes de conférences sur le sujet "Infrastructures à large échelle"
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Sanjuàs-Cuxart, Josep, Pere Barlet-Ros, Gianluca Iannaccone et Josep Solé-Pareta. « Distributed scheduling in large scale monitoring infrastructures ». Dans the 2008 ACM CoNEXT Conference. New York, New York, USA : ACM Press, 2008. http://dx.doi.org/10.1145/1544012.1544065.
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Mogul, Jeffrey C., Rebecca Isaacs et Brent Welch. « Thinking about Availability in Large Service Infrastructures ». Dans HotOS '17 : Workshop on Hot Topics in Operating Systems. New York, NY, USA : ACM, 2017. http://dx.doi.org/10.1145/3102980.3102983.
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Helmholt, K., et W. Courage. « Risk management in large scale underground infrastructures ». Dans 2013 7th Annual IEEE Systems Conference (SysCon). IEEE, 2013. http://dx.doi.org/10.1109/syscon.2013.6549991.
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Kranzlmuller, Dieter. « Management of Large-Scale e-Infrastructures at LRZ ». Dans 2011 22nd International Conference on Database and Expert Systems Applications (DEXA). IEEE, 2011. http://dx.doi.org/10.1109/dexa.2011.49.
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Capizzi, Sirio, et Antonio Messina. « A Tuple Space Service for Large Scale Infrastructures ». Dans 2008 IEEE 17th Workshop on Enabling Technologies : Infrastructure for Collaborative Enterprises. IEEE, 2008. http://dx.doi.org/10.1109/wetice.2008.14.
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« The Effect Large Infrastructures Imposes on Urban Development ». Dans 14th Annual European Real Estate Society Conference : ERES Conference 2007. ERES, 2007. http://dx.doi.org/10.15396/eres2007_264.
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Cunha, Álvaro, Elsa Caetano, Carlos Moutinho et Filipe Magalhães. « CONTINUOUS DYNAMIC MONITORING PROGRAMS OF LARGE CIVIL INFRASTRUCTURES ». Dans 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering Methods in Structural Dynamics and Earthquake Engineering. Athens : Institute of Structural Analysis and Antiseismic Research School of Civil Engineering National Technical University of Athens (NTUA) Greece, 2019. http://dx.doi.org/10.7712/120119.6901.20156.
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Routray, Ramani, Rui Zhang, David Eyers, Douglas Willcocks, Peter Pietzuch et Prasenjit Sarkar. « Policy Generation Framework for Large-Scale Storage Infrastructures ». Dans 2010 IEEE International Symposium on Policies for Distributed Systems and Networks. IEEE, 2010. http://dx.doi.org/10.1109/policy.2010.30.
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Nguyen, Hoang, et Klara Nahrstedt. « Attack Containment Framework for Large-Scale Critical Infrastructures ». Dans 2007 16th International Conference on Computer Communications and Networks. IEEE, 2007. http://dx.doi.org/10.1109/icccn.2007.4317859.
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Khurana, Himanshu, Jim Basney, Von Welch et Roy Campbell. « Operational Security Requirements for Large Collaborative Compute Infrastructures ». Dans 2006 International Conference on Collaborative Computing : Networking, Applications and Worksharing. IEEE, 2006. http://dx.doi.org/10.1109/colcom.2006.361884.
Texte intégralRapports d'organisations sur le sujet "Infrastructures à large échelle"
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Martínez-Ventura, Constanza, Jorge Ricardo Mariño-Martínez et Javier Iván Miguélez-Márquez. Redundancy of Centrality Measures in Financial Market Infrastructures. Banco de la República de Colombia, août 2022. http://dx.doi.org/10.32468/be.1206.
Texte intégralRésumé :
The concept of centrality has been widely used to monitor systems with a network structure because it allows identifying their most influential participants. But this monitoring task can be difficult if the number of system participants is considerably large or if the wide variety of centrality measures currently available produce non-coincident (or mixed) signals. This document uses principal component analysis to evaluate a set of centrality measures calculated for the financial institutions that participate in four financial market infrastructures of Colombia. The results obtained are used to construct general indices of centrality, using the strongest measures of centrality as inputs, and leaving aside those considered redundant.
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Marchildon, Allison, Claire Boine, Andréane Sabourin Laflamme, Dave Anctil, Antoine Boudreau LeBlanc, Sylvain Auclair, Christine Balagué et al. Un an après l’arrivée de ChatGPT : Réflexions de l’Obvia sur les enjeux et pistes d’action possibles face à l’IA générative. Observatoire international sur les impacts sociétaux de l’intelligence artificielle et du numérique, janvier 2024. http://dx.doi.org/10.61737/zkwz3721.
Texte intégralRésumé :
Depuis l’automne 2022, avec l’arrivée abrupte de ChatGPT, la version gratuite du modèle de langage de l’entreprise OpenAI, les expérimentations à grande échelle du déploiement de ce système d’intelligence artificielle ont suscité un tsunami de réactions dont on perçoit les conséquences autant dans nos vies personnelles que professionnelles. En raison de l’ampleur des implications de cet événement, qui symbolise un changement hautement disruptif pour nos sociétés, il s’avérait incontournable qu’un groupe de chercheuses et de cherecheurs de l’Obvia s’y penche afin de contribuer à la réflexion sur le sujet et dégager des pistes d’action. Le but du présent document vise par conséquent à apporter des éléments de réflexion sur les différents enjeux que soulève l’émergence soudaine de ces technologies au potentiel révolutionnaire. Le présent document vise plus spécifiquement: • à situer dans son contexte le développement des applications d’IA générative; • à identifier ce qui nous semble être les principaux enjeux transversaux soulevés par l’arrivée de ces technologies dans nos vies et nos sociétés; • à esquisser quelques pistes d’action pour tenter de composer adéquatement avec ces enjeux. Ce document a été rédigé par une équipe multidisciplinaire de chercheuses et de chercheurs membres de l’Obvia. En effet, pour mener une réflexion sur une situation aussi large et complexe, il nous semblait essentiel de réunir des expertes et experts de plusieurs domaines, notamment en éthique appliquée, en neuropsychologie, en droit, en bioéthique et en philosophie. Les différentes thématiques qui émergent de cette réflexion ont été organisées comme suit, mais elles peuvent être découvertes dans l’ordre ou dans le désordre, selon les intérêts de la lectrice ou du lecteur.
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Chiavassa, Nathalie, et Raphael Dewez. Technical Note on Road Safety in Haiti. Inter-American Development Bank, janvier 2021. http://dx.doi.org/10.18235/0003250.
Texte intégralRésumé :
The IDB has been a predominant partner supporting Haiti development efforts for many years. Nowadays, the IDB is the main source of investment for the country. Considering the vital weight of road transport sector in the socio-economy of the country, the IDB has concentrated a large part of investment efforts in rehabilitating and improving national road infrastructures. In the same time, a rapid increase of motorization and relatively higher speeds have contributed to increasing the number of traffic fatalities and injuries. In 2017, road injuries were the fifth cause of mortality in Haiti. The Road Safety situation of the country is preoccupying with many Vulnerable Road Users involved, in particular pedestrians and motorcyclists. The country is facing multi-sector challenges to address this Road Safety situation. Despite recent efforts, high political will has not been continuous in promoting a multi-sector coordination and the success of technical efforts remained mitigated over the last years. Road user awareness is still weak in the country. Risk factors include dangerous driving, bad safety conditions of vehicles, together with limited law enforcement and poor maintenance of safety devices on the roads. In this context, the Road Safety situation of the country may be getting worse in the coming years if no action is taken. However, the new Decade provides with a unique opportunity to achieve Sustainable Development Goals (SDGs) including significant progress in reducing the burden of traffic crashes. The IDB has already initiated vital investments in modernizing crash data collection, promoting institutional dialogue and supporting capacity building in the area of Road Safety. Future actions to address Road Safety challenges in Haiti in the framework of the five UN five pillars would require a range of investments in the area of political commitment, institutional coordination and technical efforts. A change of political paradigm from making roads for travelling faster to making roads safer for all users is highly needed at national level. This technical note on Road Safety in Haiti present the current situation of the country and provides with recommendations for future actions on Road Safety.
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Doo, Johnny. Unsettled Issues Concerning eVTOL for Rapid-response, On-demand Firefighting. SAE International, août 2021. http://dx.doi.org/10.4271/epr2021017.
Texte intégralRésumé :
Recent advancements of electric vertical take-off and landing (eVTOL) aircraft have generated significant interest within and beyond the traditional aviation industry, and many novel applications have been identified and are in development. One promising application for these innovative systems is in firefighting, with eVTOL aircraft complementing current firefighting capabilities to help save lives and reduce fire-induced damages. With increased global occurrences and scales of wildfires—not to mention the issues firefighters face during urban and rural firefighting operations daily—eVTOL technology could offer timely, on-demand, and potentially cost-effective aerial mobility capabilities to counter these challenges. Early detection and suppression of wildfires could prevent many fires from becoming large-scale disasters. eVTOL aircraft may not have the capacity of larger aerial assets for firefighting, but targeted suppression, potentially in swarm operations, could be valuable. Most importantly, on-demand aerial extraction of firefighters can be a crucial benefit during wildfire control operations. Aerial firefighter dispatch from local fire stations or vertiports can result in more effective operations, and targeted aerial fire suppression and civilian extraction from high-rise buildings could enhance capabilities significantly. There are some challenges that need to be addressed before the identified capabilities and benefits are realized at scale, including the development of firefighting-specific eVTOL vehicles; sense and avoid capabilities in complex, smoke-inhibited environments; autonomous and remote operating capabilities; charging system compatibility and availability; operator and controller training; dynamic airspace management; and vehicle/fleet logistics and support. Acceptance from both the first-responder community and the general public is also critical for the successful implementation of these new capabilities. The purpose of this report is to identify the benefits and challenges of implementation, as well as some of the potential solutions. Based on the rapid development progress of eVTOL aircraft and infrastructures with proactive community engagement, it is envisioned that these challenges can be addressed soon. NOTE: SAE EDGE™ Research Reports are intended to identify and illuminate key issues in emerging, but still unsettled, technologies of interest to the mobility industry. The goal of SAE EDGE™ Research Reports is to stimulate discussion and work in the hope of promoting and speeding resolution of identified issues. These reports are not intended to resolve the challenges they identify or close any topic to further scrutiny.
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Drury, J., S. Arias, T. Au-Yeung, D. Barr, L. Bell, T. Butler, H. Carter et al. Public behaviour in response to perceived hostile threats : an evidence base and guide for practitioners and policymakers. University of Sussex, 2023. http://dx.doi.org/10.20919/vjvt7448.
Texte intégralRésumé :
Background: Public behaviour and the new hostile threats • Civil contingencies planning and preparedness for hostile threats requires accurate and up to date knowledge about how the public might behave in relation to such incidents. Inaccurate understandings of public behaviour can lead to dangerous and counterproductive practices and policies. • There is consistent evidence across both hostile threats and other kinds of emergencies and disasters that significant numbers of those affected give each other support, cooperate, and otherwise interact socially within the incident itself. • In emergency incidents, competition among those affected occurs in only limited situations, and loss of behavioural control is rare. • Spontaneous cooperation among the public in emergency incidents, based on either social capital or emergent social identity, is a crucial part of civil contingencies planning. • There has been relatively little research on public behaviour in response to the new hostile threats of the past ten years, however. • The programme of work summarized in this briefing document came about in response to a wave of false alarm flight incidents in the 2010s, linked to the new hostile threats (i.e., marauding terrorist attacks). • By using a combination of archive data for incidents in Great Britain 2010-2019, interviews, video data analysis, and controlled experiments using virtual reality technology, we were able to examine experiences, measure behaviour, and test hypotheses about underlying psychological mechanisms in both false alarms and public interventions against a hostile threat. Re-visiting the relationship between false alarms and crowd disasters • The Bethnal Green tube disaster of 1943, in which 173 people died, has historically been used to suggest that (mis)perceived hostile threats can lead to uncontrolled ‘stampedes’. • Re-analysis of witness statements suggests that public fears of Germany bombs were realistic rather than unreasonable, and that flight behaviour was socially structured rather than uncontrolled. • Evidence for a causal link between the flight of the crowd and the fatal crowd collapse is weak at best. • Altogether, the analysis suggests the importance of examining people’s beliefs about context to understand when they might interpret ambiguous signals as a hostile threat, and that. Tthe concepts of norms and relationships offer better ways to explain such incidents than ‘mass panic’. Why false alarms occur • The wider context of terrorist threat provides a framing for the public’s perception of signals as evidence of hostile threats. In particular, the magnitude of recent psychologically relevant terrorist attacks predicts likelihood of false alarm flight incidents. • False alarms in Great Britain are more likely to occur in those towns and cities that have seen genuine terrorist incidents. • False alarms in Great Britain are more likely to occur in the types of location where terrorist attacks happen, such as shopping areass, transport hubs, and other crowded places. • The urgent or flight behaviour of other people (including the emergency services) influences public perceptions that there is a hostile threat, particularly in situations of greater ambiguity, and particularly when these other people are ingroup. • High profile tweets suggesting a hostile threat, including from the police, have been associated with the size and scale of false alarm responses. • In most cases, it is a combination of factors – context, others’ behaviour, communications – that leads people to flee. A false alarm tends not to be sudden or impulsive, and often follows an initial phase of discounting threat – as with many genuine emergencies. 2.4 How the public behave in false alarm flight incidents • Even in those false alarm incidents where there is urgent flight, there are also other behaviours than running, including ignoring the ‘threat’, and walking away. • Injuries occur but recorded injuries are relatively uncommon. • Hiding is a common behaviour. In our evidence, this was facilitated by orders from police and offers from people staff in shops and other premises. • Supportive behaviours are common, including informational and emotional support. • Members of the public often cooperate with the emergency services and comply with their orders but also question instructions when the rationale is unclear. • Pushing, trampling and other competitive behaviour can occur,s but only in restricted situations and briefly. • At the Oxford Street Black Friday 2017 false alarm, rather than an overall sense of unity across the crowd, camaraderie existed only in pockets. This was likely due to the lack of a sense of common fate or reference point across the incident; the fragmented experience would have hindered the development of a shared social identity across the crowd. • Large and high profile false alarm incidents may be associated with significant levels of distress and even humiliation among those members of the public affected, both at the time and in the aftermath, as the rest of society reflects and comments on the incident. Public behaviour in response to visible marauding attackers • Spontaneous, coordinated public responses to marauding bladed attacks have been observed on a number of occasions. • Close examination of marauding bladed attacks suggests that members of the public engage in a wide variety of behaviours, not just flight. • Members of the public responding to marauding bladed attacks adopt a variety of complementary roles. These, that may include defending, communicating, first aid, recruiting others, marshalling, negotiating, risk assessment, and evidence gathering. Recommendations for practitioners and policymakers • Embed the psychology of public behaviour in emergencies in your training and guidance. • Continue to inform the public and promote public awareness where there is an increased threat. • Build long-term relations with the public to achieve trust and influence in emergency preparedness. • Use a unifying language and supportive forms of communication to enhance unity both within the crowd and between the crowd and the authorities. • Authorities and responders should take a reflexive approach to their responses to possible hostile threats, by reflecting upon how their actions might be perceived by the public and impact (positively and negatively) upon public behaviour. • To give emotional support, prioritize informative and actionable risk and crisis communication over emotional reassurances. • Provide first aid kits in transport infrastructures to enable some members of the public more effectively to act as zero responders.
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Very Large Research Infrastructures. Organisation for Economic Co-Operation and Development (OECD), juillet 2023. http://dx.doi.org/10.1787/2b93187f-en.
Texte intégral
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Payment Systems Report - June of 2020. Banco de la República de Colombia, février 2021. http://dx.doi.org/10.32468/rept-sist-pag.eng.2020.
Texte intégralRésumé :
With its annual Payment Systems Report, Banco de la República offers a complete overview of the infrastructure of Colombia’s financial market. Each edition of the report has four objectives: 1) to publicize a consolidated account of how the figures for payment infrastructures have evolved with respect to both financial assets and goods and services; 2) to summarize the issues that are being debated internationally and are of interest to the industry that provides payment clearing and settlement services; 3) to offer the public an explanation of the ideas and concepts behind retail-value payment processes and the trends in retail payments within the circuit of individuals and companies; and 4) to familiarize the public, the industry, and all other financial authorities with the methodological progress that has been achieved through applied research to analyze the stability of payment systems. This edition introduces changes that have been made in the structure of the report, which are intended to make it easier and more enjoyable to read. The initial sections in this edition, which is the eleventh, contain an analysis of the statistics on the evolution and performance of financial market infrastructures. These are understood as multilateral systems wherein the participating entities clear, settle and register payments, securities, derivatives and other financial assets. The large-value payment system (CUD) saw less momentum in 2019 than it did the year before, mainly because of a decline in the amount of secondary market operations for government bonds, both in cash and sell/buy-backs, which was offset by an increase in operations with collective investment funds (CIFs) and Banco de la República’s operations to increase the money supply (repos). Consequently, the Central Securities Depository (DCV) registered less activity, due to fewer negotiations on the secondary market for public debt. This trend was also observed in the private debt market, as evidenced by the decline in the average amounts cleared and settled through the Central Securities Depository of Colombia (Deceval) and in the value of operations with financial derivatives cleared and settled through the Central Counterparty of Colombia (CRCC). Section three offers a comprehensive look at the market for retail-value payments; that is, transactions made by individuals and companies. During 2019, electronic transfers increased, and payments made with debit and credit cards continued to trend upward. In contrast, payments by check continued to decline, although the average daily value was almost four times the value of debit and credit card purchases. The same section contains the results of the fourth survey on how the use of retail-value payment instruments (for usual payments) is perceived. Conducted at the end of 2019, the main purpose of the survey was to identify the availability of these payment instruments, the public’s preferences for them, and their acceptance by merchants. It is worth noting that cash continues to be the instrument most used by the population for usual monthly payments (88.1% with respect to the number of payments and 87.4% in value). However, its use in terms of value has declined, having registered 89.6% in the 2017 survey. In turn, the level of acceptance by merchants of payment instruments other than cash is 14.1% for debit cards, 13.4% for credit cards, 8.2% for electronic transfers of funds and 1.8% for checks. The main reason for the use of cash is the absence of point-of-sale terminals at commercial establishments. Considering that the retail-payment market worldwide is influenced by constant innovation in payment services, by the modernization of clearing and settlement systems, and by the efforts of regulators to redefine the payment industry for the future, these trends are addressed in the fourth section of the report. There is an account of how innovations in technology-based financial payment services have developed, and it shows that while this topic is not new, it has evolved, particularly in terms of origin and vocation. One of the boxes that accompanies the fourth section deals with certain payment aspects of open banking and international experience in that regard, which has given the customers of a financial entity sovereignty over their data, allowing them, under transparent and secure conditions, to authorize a third party, other than their financial entity, to request information on their accounts with financial entities, thus enabling the third party to offer various financial services or initiate payments. Innovation also has sparked interest among international organizations, central banks, and research groups concerning the creation of digital currencies. Accordingly, the last box deals with the recent international debate on issuance of central bank digital currencies. In terms of the methodological progress that has been made, it is important to underscore the work that has been done on the role of central counterparties (CCPs) in mitigating liquidity and counterparty risk. The fifth section of the report offers an explanation of a document in which the work of CCPs in financial markets is analyzed and corroborated through an exercise that was built around the Central Counterparty of Colombia (CRCC) in the Colombian market for non-delivery peso-dollar forward exchange transactions, using the methodology of network topology. The results provide empirical support for the different theoretical models developed to study the effect of CCPs on financial markets. Finally, the results of research using artificial intelligence with information from the large-value payment system are presented. Based on the payments made among financial institutions in the large-value payment system, a methodology is used to compare different payment networks, as well as to determine which ones can be considered abnormal. The methodology shows signs that indicate when a network moves away from its historical trend, so it can be studied and monitored. A methodology similar to the one applied to classify images is used to make this comparison, the idea being to extract the main characteristics of the networks and use them as a parameter for comparison. Juan José Echavarría Governor
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Financial Infrastructure Report 2023. Banco de la República, décembre 2023. http://dx.doi.org/10.32468/rept-sist-pag.eng.2023.
Texte intégralRésumé :
Introduction The Financial Infrastructure Report is a product of Banco de la República’s (Banrep) continuous efforts to scrutinize financial market infrastructures (FMIs) in Colombia, besides being a contribution to analyzing and monitoring the country’s financial stability. If FMIs are not managed properly, they can pose significant risks to the financial system and be a possible source of contagion, especially in periods of market stress. The domestic financial infrastructure during 2022 was safe and efficient, allowing the payment system and financial markets to operate normally, which lent stability and confidence to its participants. This 2023 edition of the Report includes analysis on the mitigation of intraday liquidity risk in the large-value payment system (CUD), as well as credit and liquidity risk based on countercyclical practices for the management of initial and variation margins in the Cámara de Riesgo Central de Contraparte S.A. (CRCC). In addition, the Report addresses two topics that are at the center of international debate. The first deals with cyber risk, an issue that cuts across the entire domestic financial infrastructure. It is considered one of the most relevant risks; therefore, its effective management has been the focus of recommendations by multilateral organizations. On this occasion, a section is included that outlines these recommendations and focuses on highlights in local progress towards achieving substantial levels of cyber resilience in the Colombian payment system. It is worth noting that Banco de la República is moving forward with a research agenda to quantify the impact instances of cyber risk could have on the payment system and on financial stability. The second topic addresses the need to analyze the adoption of special frameworks for orderly settlement on the part of central counterparties (CCPs), so as to mitigate systemic risk, recognizing the role these types of entities play in the development of markets and financial stability, as well as their essential contribution to mitigating counterparty and liquidity risks. As for retail payments, the use of electronic payment instruments rose significantly in value during 2022 compared to 2021. Transactional data shows the increase in the use of electronic transfers, both intra- and interbank, was particularly important, having become an object of greater innovation, as evidenced, for example, by the use of mobile wallets. Although the adoption for electronic transfers and debit and credit cards has increased in Colombia over the last ten years, compared to other economies, the country still has low levels in this respect. According to the most recent survey on perception of the use of payment instruments conducted by Banrep (2022), cash continues to be the instrument most used by Colombians for regular payments involving small amounts. This points to an important area for increasing the adoption of digital payments, which would materialize with implementation of the different initiatives the industry and the financial authorities (Ministry of Finance-URF, the Office of the Financial Superintendent of Colombia and Banco de la República) are carrying out to develop the instant payments ecosystem. On the other hand, analyses of the risks associated with crypto assets, which are understood as alternatives to the regulated assets in the traditional financial system, but traded in an unregulated digital environment, are also relevant. In this respect, the Report looks at the potential risks that could arise from the added adoption of stablecoins in economies, specifically in a global context where authorities are studying possibilities for using different mechanisms to contain the risks inherent in crypto assets. The third section of the Report deals with aspects such as smart contracts and programmable money, which are innovations that could be considered in an eventual issue of digital currencies by central banks. In keeping with the previous editions of this Report on matters related to central bank digital currencies (CBDC), this edition explains how these two technological functionalities could accompany the design of a retail CBDC, as well as some of the risks that should be considered. Also addressed in this section is the topic of standardized messaging, which is a trend in the field of payments. Reference is made to the United Kingdom’s experience with the adoption of standardized messaging, and its contributions to interoperability.
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Financial Infrastructure Report 2022. Banco de la República, juin 2023. http://dx.doi.org/10.32468/rept-sist-pag.eng.2022.
Texte intégralRésumé :
Banco de la República's monitoring of the local financial market infrastructure is an additional contribution to the country's financial stability. One of the products of that monitoring has been the Payment Systems Report, which is now known as the Financial Infrastructure Report. The change in name, as of this edition, is intended to reflect in a broader way the issues that are addressed in the report. The 2022 edition includes several changes that are the result of a comparative study of financial infrastructure reports prepared by other central banks. These changes seek to make the report more fluid and easier to read, including main points and selected key figures for the different interest groups to which it is addressed. The report shows the financial infrastructure continued to render its services without interruption, with general evidence of good performance in 2021. Additionally, the resilience of the Central Counterparty Risk of Colombia (CRCC) and the Large-value Payments System (CUD) to extreme events was validated, based on stress tests conducted according to international standards (focused on liquidity and credit risk). As for retail payments, transactional information indicates the use of electronic instruments increased in terms of value during 2021 compared to 2020 (credit and debit cards, checks and electronic funds transfers). The use of debit and credit cards in payments rose to levels similar to those reached in the pre-pandemic year. Meanwhile, electronic funds transfers continued to grow. Although the results of the BR 2022 survey show cash continues to be the instrument most used by the public for regular payments (like the situation in other countries), the perception of its use decreased significantly to 75 % (87 % in 2019). Also, in commerce, cash was the preferred instrument for customers. However, in this measurement, several retail channels such as hairdressers, drugstores and restaurants joined the group that has traditionally received electronic payments for a value greater than 10% of their sales (hypermarkets and gas stations). Likewise, for nearly 50% of the population, cash payments are lower than before the pandemic. This is consistent with the transactional increase in electronic payment instruments that was observed in 2021. Banco de la República continues to monitor the technological developments that have expanded and modernized the supply in the international and local payments market, as these are issues of interest to the industry that provides clearing and settlement services. This report outlines the Pix case for instant payments in Brazil, the projects that are underway regarding the possible issue of digital currency by central banks (CBDC) for cross-border payments, as well as an approach to the Fintech ecosystem in Colombia, with an emphasis on companies that provide payment services. Leonardo Villar Governor Main points: 2022 The local financial infrastructure was safe and efficient throughout the year. The services of the financial infrastructure were proved on a continuous basis, showing good performance overall. Less momentum in the large-value payment system CUD activity declined versus the previous year because of fewer government deposits with BanRep. This was offset partially by growth in repos to increase money supply and in retail-value payments (electronic funds transfers, checks and cards). Increased momentum in financial market infrastructures. Larger amounts were cleared and settled through the Central Securities Depository (DCV) due to an increase in the market for sovereign debt. Operations managed by the Central Counterparty Risk of Colombia (CRCC) increased due to inclusion of the foreign exchange segment and the positive evolution in non-delivery forward peso/dollar contracts. Added confidence in the peso/dollar spot foreign exchange market due to CRCC interposition. Number and value of trades grew, mainly due to the adjustment of therisk management model for the FX segment and the increase in the limiton net selling positions in dollars. Stress testing with international standards to validate CRCC and CUD resilience Stress tests conducted independently by the SFC, BanRep and the CRCC, like those done in England and the United States, concluded that the CRCC's risk management model allows it to withstand extreme market events and simultaneous defaults by its main members. Based on the experience of other central banks, BanRep strengthened its intraday liquidity risk stress exercises in the CUD by incorporating temporary payment delays. It calculated that a two-hour delay by a key participant increases the system's liquidity needs by 0.5%. Electronic payments increased during 2021 According to transactional information, all electronic payment instruments increased in value versus 2020 (electronic funds transfers, checks and debit and credit cards). Electronic funds transfers continued to grow (80% from legal entities), with the participation of closed schemes driven particularly by the use of mobile wallets (35% of the number of intra-transfer transactions). The use of debit and credit cards for payments climbed to levels similar to those witnessed in the pre-pandemic year. Cash continues to be the instrument most used by the public for regular payments. The results of the BanRep survey in 2022 show that the perception of the use of cash declined significantly to 75% (87% in 2019), and about 50% of the population perceive their cash payments as being lower than those they made before the pandemic. Electronic funds transfers were second most used instrument, having increased to 15% (3% in 2019). Also, in commerce, cash was the preferred instrument of payment for its customers; however, several commerce channels received more than 10% of the value of their sales in electronic payments (hypermarkets 35%, gas stations 25%, hairdressers 15%, drugstores 14% and restaurants 12%). Continuous technological developments have broadened, and modernized services offered in the payments market. Pix (instant payments in Brazil). The high level of adoption of instant transfers in Brazil motivated a review of its strengths; namely, the possibility of different use cases between individuals, businesses, and government; high participation by financial and payment institutions; free of charge for individuals and the possibility of charging legal entities, and simple user experience. Digital currencies in central banking. Several groups of countries have joined forces to conduct pilot projects with wholesale CBDCs for cross-border payments. Flows generated by international trade, foreign investment and remittances between individuals can be processed more efficiently, transparently, and securely by reducing their cost and increasing their speed. Due to the constant progress being made on this issue, BanRep will continue to monitor all CBDC-related matters. The fintech ecosystem for payments in Colombia. A high percentage of existing FinTech companies in the country are dedicated to offering digital payment services: wallets, payment gateways, mobile devices (point-of-sale terminals) and acquisition. These have driven innovation in payment services.
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Payment Systems Report - June of 2021. Banco de la República, février 2022. http://dx.doi.org/10.32468/rept-sist-pag.eng.2021.
Texte intégralRésumé :
Banco de la República provides a comprehensive overview of Colombia’s finan¬cial infrastructure in its Payment Systems Report, which is an important product of the work it does to oversee that infrastructure. The figures published in this edition of the report are for the year 2020, a pandemic period in which the con¬tainment measures designed and adopted to alleviate the strain on the health system led to a sharp reduction in economic activity and consumption in Colom¬bia, as was the case in most countries. At the start of the pandemic, the Board of Directors of Banco de la República adopted decisions that were necessary to supply the market with ample liquid¬ity in pesos and US dollars to guarantee market stability, protect the payment system and preserve the supply of credit. The pronounced growth in mone¬tary aggregates reflected an increased preference for liquidity, which Banco de la República addressed at the right time. These decisions were implemented through operations that were cleared and settled via the financial infrastructure. The second section of this report, following the introduction, offers an analysis of how the various financial infrastructures in Colombia have evolved and per¬formed. One of the highlights is the large-value payment system (CUD), which registered more momentum in 2020 than during the previous year, mainly be¬cause of an increase in average daily remunerated deposits made with Banco de la República by the General Directorate of Public Credit and the National Treasury (DGCPTN), as well as more activity in the sell/buy-back market with sovereign debt. Consequently, with more activity in the CUD, the Central Securi¬ties Depository (DCV) experienced an added impetus sparked by an increase in the money market for bonds and securities placed on the primary market by the national government. The value of operations cleared and settled through the Colombian Central Counterparty (CRCC) continues to grow, propelled largely by peso/dollar non-deliverable forward (NDF) contracts. With respect to the CRCC, it is important to note this clearing house has been in charge of managing risks and clearing and settling operations in the peso/dollar spot market since the end of last year, following its merger with the Foreign Exchange Clearing House of Colombia (CCDC). Since the final quarter of 2020, the CRCC has also been re¬sponsible for clearing and settlement in the equities market, which was former¬ly done by the Colombian Stock Exchange (BVC). The third section of this report provides an all-inclusive view of payments in the market for goods and services; namely, transactions carried out by members of the public and non-financial institutions. During the pandemic, inter- and intra-bank electronic funds transfers, which originate mostly with companies, increased in both the number and value of transactions with respect to 2019. However, debit and credit card payments, which are made largely by private citizens, declined compared to 2019. The incidence of payment by check contin¬ue to drop, exhibiting quite a pronounced downward trend during the past last year. To supplement to the information on electronic funds transfers, section three includes a segment (Box 4) characterizing the population with savings and checking accounts, based on data from a survey by Banco de la República con-cerning the perception of the use of payment instruments in 2019. There also is segment (Box 2) on the growth in transactions with a mobile wallet provided by a company specialized in electronic deposits and payments (Sedpe). It shows the number of users and the value of their transactions have increased since the wallet was introduced in late 2017, particularly during the pandemic. In addition, there is a diagnosis of the effects of the pandemic on the payment patterns of the population, based on data related to the use of cash in circu¬lation, payments with electronic instruments, and consumption and consumer confidence. The conclusion is that the collapse in the consumer confidence in¬dex and the drop in private consumption led to changes in the public’s pay¬ment patterns. Credit and debit card purchases were down, while payments for goods and services through electronic funds transfers increased. These findings, coupled with the considerable increase in cash in circulation, might indicate a possible precautionary cash hoarding by individuals and more use of cash as a payment instrument. There is also a segment (in Focus 3) on the major changes introduced in regulations on the retail-value payment system in Colombia, as provided for in Decree 1692 of December 2020. The fourth section of this report refers to the important innovations and tech¬nological changes that have occurred in the retail-value payment system. Four themes are highlighted in this respect. The first is a key point in building the financial infrastructure for instant payments. It involves of the design and im¬plementation of overlay schemes, a technological development that allows the various participants in the payment chain to communicate openly. The result is a high degree of interoperability among the different payment service providers. The second topic explores developments in the international debate on central bank digital currency (CBDC). The purpose is to understand how it could impact the retail-value payment system and the use of cash if it were to be issued. The third topic is related to new forms of payment initiation, such as QR codes, bio¬metrics or near field communication (NFC) technology. These seemingly small changes can have a major impact on the user’s experience with the retail-value payment system. The fourth theme is the growth in payments via mobile tele¬phone and the internet. The report ends in section five with a review of two papers on applied research done at Banco de la República in 2020. The first analyzes the extent of the CRCC’s capital, acknowledging the relevant role this infrastructure has acquired in pro¬viding clearing and settlement services for various financial markets in Colom¬bia. The capital requirements defined for central counterparties in some jurisdic¬tions are explored, and the risks to be hedged are identified from the standpoint of the service these type of institutions offer to the market and those associated with their corporate activity. The CRCC’s capital levels are analyzed in light of what has been observed in the European Union’s regulations, and the conclusion is that the CRCC has a scheme of security rings very similar to those applied internationally and the extent of its capital exceeds what is stipulated in Colombian regulations, being sufficient to hedge other risks. The second study presents an algorithm used to identify and quantify the liquidity sources that CUD’s participants use under normal conditions to meet their daily obligations in the local financial market. This algorithm can be used as a tool to monitor intraday liquidity. Leonardo Villar Gómez Governor