1,720,974 research outputs found
A sharing data system adapted to a Fog Computing environment
No full textL’informatique utilitaire a évolué au fil des années pour aboutir à ce que nous appelons aujourd’hui le Cloud Computing. Pourtant, ces infrastructures ne sont pas adaptées pour répondre aux besoins de l’Internet des Objets ayant des besoins de calculs à faible latence malgré des ressources limitées. C’est pourquoi, en 2012, Cisco a proposé le paradigme de Fog Computing, consistant à répartir des serveurs sur de nombreux sites placés près des utilisateurs. Dans cette thèse, nous cherchons à créer une solution de stockage unifiée entre les différents sites de Fog. Notre première contribution consiste à évaluer si les solutions de stockage existantes peuvent être utilisées dans un tel environnement. Nous montrons que la solution de stockage InterPlanetary FileSystem (IPFS) reposant sur un protocole similaire à BitTorrent et une table de hachage distribuée (DHT) pour localiser les données est la plus prometteuse. Toutefois, le trafic réseau inter-sites généré impacte négativement les temps de lecture. Notre seconde contribution consiste à coupler IPFS au système de fichiers distribué RozoFS pour limiter ces échanges inter-sites dans le cas d’accès à des données stockées sur le site local. Enfin, notre dernier axe de recherche vise à localiser les données grâce à un protocole reposant sur un arbre des plus courts chemins, de façon à confiner le trafic réseau et à privilégier les nœuds atteignables avec une faible latence. Grâce à de nombreuses expérimentations sur la plateforme Grid’5000, nous montrons que le couplage à un système de fichiers réduit en moyenne de 34% les temps d’accès et que notre protocole de localisation permet un gain de 20% du temps de localisation des données.Utility Computing has evolved for many years leading to the infrastructure we know today as Cloud Computing. Nevertheless, these infrastructures are unable to satisfy the needs of the Internet of Things which requires low latency computing despite limited resources. In 2012, Cisco proposed a paradigm called Fog Computing, consisting of deploying a huge number of small servers, spread on many sites located at the edge of the network, close to the end devices. In this thesis, we try to create a seamless storage solution between the different Fog sites. Our first contribution consists in comparing existing storage solution and check if they can be used in a such environment. We show that InterPlanetary FileSystem (IPFS), an object store relying on a BitTorrent like protocol and a Distributed Hash Table is a promising solution. Nevertheless, the amount of network traffic exchanged between the sites to locate the data is important and has a non-negligible impact on the overall performance. Our second contribution consists in coupling IPFS with RozoFS, a distributed filesystem deployed on each site to limit the use of the DHT when accessed data are stored on the local site. Finally, we proposed to replace the distributed hash table by a location mechanism relying on a shortest path tree built on the physical topology, in order to contain the network traffic and to first request nodes at a close location, reachable with a low latency. By performing many experiments on the Grid’5000 testbed, we show that the coupling of IPFS with a Scale-Out NAS reduces by 34 % in average the access times and that our protocol to locate the objects reduces by 20 % the time to locate the data
Conception d'un système de partage de données adapté à un environnement de Fog Computing
Full text linkUtility Computing has evolved for many years leading to the infrastructure we know today as Cloud Computing.Nevertheless, these infrastructures are unable to satisfy the needs of the Internet of Things which requires low latency computing despite limited resources. In 2012, Cisco proposed a paradigm called Fog Computing, consisting of deploying a huge number of small servers, spread on many sites located at the edge of the network, close to the end devices. In this thesis, we try to create a seamless storage solution between the different Fog sites.Our first contribution consists in comparing existing storage solution and check if they can be used in a such environment.We show that InterPlanetary FileSystem (IPFS), an object store relying on a BitTorrent like protocol and a Distributed Hash Table is a promising solution. Nevertheless, the amount of network traffic exchanged between the sites to locate the data is important and has a non-negligible impact on the overall performance. Our second contribution consists in coupling IPFS with RozoFS, a distributed filesystem deployed on each site to limit the use of the DHT when accessed data are stored on the local site. Finally, we proposed to replace the distributed hash table by a location mechanism relying on a shortest path tree built on the physical topology, in order to contain the network traffic and to first request nodes at a close location, reachable with a low latency. By performing many experiments on the Grid’5000 testbed, we show that the coupling of IPFS with a Scale-Out NAS reduces by 34 % in average the access times and that our protocol to locate the objects reduces by 20 % the time to locate the data.L'informatique utilitaire a évolué au fil des années pour aboutir à ce que nous appelons aujourd'hui le Cloud Computing.Pourtant, ces infrastructures ne sont pas adaptées pour répondre aux besoins de l'Internet des Objets ayant des besoins de calculs à faible latence malgré des ressources limitées. C'est pourquoi, en 2012, Cisco a proposé le paradigme de Fog Computing, consistant à répartir des serveurs sur de nombreux sites placés près des utilisateurs. Dans cette thèse, nous cherchons à créer une solution de stockage unifiée entre les différents sites de Fog.Notre première contribution consiste à évaluer si les solutions de stockage existantes peuvent être utilisées dans un tel environnement.Nous montrons que la solution de stockage InterPlanetary FileSystem (IPFS) reposant sur un protocole similaire à BitTorrent et une table de hachage distribuée (DHT) pour localiser les données est la plus prometteuse. Toutefois, le trafic réseau inter-sites généré impacte négativement les temps de lecture. Notre seconde contribution consiste à coupler IPFS au système de fichiers distribué RozoFS pour limiter ces échanges inter-sites dans le cas d'accès à des données stockées sur le site local. Enfin, notre dernier axe de recherche vise à localiser les données grâce à un protocole reposant sur un arbre des plus courts chemins, de façon à confiner le trafic réseau et à privilégier les nœuds atteignables avec une faible latence. Grâce à de nombreuses expérimentations sur la plateforme Grid'5000, nous montrons que le couplage à un système de fichiers réduit en moyenne de 34 % les temps d'accès et que notre protocole de localisation permet un gain de 20 % du temps de localisation des données
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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