1,720,958 research outputs found
Diferenciação de serviços em servidores web baseada em escalonamento adaptativo e controle de admissão
Get PDFDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia ElétricaCom o paradigma de melhor esforço (best-effort) oferecido pela Internet atual, clientes de novos tipos de aplicações (VoIP e IPTV) têm que conviver com aplicações tradicionais da Internet como: e-mail e simples web sites. Contudo, verifica-se que nem todos os tipos de tráfego têm os mesmos requisitos de confiabilidade, segurança e urgência. Considerando-se a infra-estrutura de rede, existem algumas propostas nesse sentido, elaboradas sob a coordenação da IETF (Internet Engineering Task Force). Entretanto, em nível de aplicação os esforços ainda são limitados, não sendo encontrados na grande maioria dos servidores web
Explorando descartes de ativações periódicas para provimento de qualidade de serviço em redes IEEE 802.15.4
Get PDFTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e SistemasAtualmente, tem se considerado cada vez mais o uso de redes sem fios em sistemas de automação industrial e controle de processos. Sistemas de Controle via Rede são exemplos de aplicações em que busca-se implantar em ambientes industriais. Para estes tipos de aplicações, o suporte à serviços de comunicação tempo real é uma das maiores necessidades. Tradicionalmente, aplicações de tempo real industriais assumem que nenhuma amostra será perdida durante os ciclos de controle. Contudo, alguns estudos realizados nos últimos anos indicam que os efeitos dos descartes de mensagens frente ao desempenho dos sistemas de controle podem ser compensados com emprego de outras técnicas. O padrão IEEE 802.15.4 têm se mostrado uma solução atrativa para uma vasta gama de aplicações no campo das Redes de Sensores sem Fios e mais recentemente no campo da instrumentação sem fios. Sendo assim, esta tese tem por objetivo principal propor abordagens de provimento de Qualidade de Serviço (QoS) em redes IEEE 802.15.4 para aplicações de tempo real que tolerem perdas de deadline. Primeiramente, um mecanismo de priorização de tráfego para dispositivos de tempo real, durante períodos de acesso com contenção (CAP) foi proposto. Este mecanismo, denominado DDBP, oferece de forma descentralizada aos dispositivos que desejam realizar suas transmissões durante o CAP, priorização de acesso ao meio de comunicação de acordo com a distância para falha dos dispositivos. Posteriormente, duas abordagens de escalonamento durante períodos de acesso sem contenção (CFP) foram propostas: abordagem SDBP, a qual oferece garantias de atendimento de deadline às aplicações, através de um teste de escalonabilidade determinístico e uma heurística on-line de priorização de mensagens; e abordagem (m,k)-spin, a qual apresenta uma análise de escalonabilidade baseada no conceito de período de nível de ocupação. As abordagens propostas voltadas para o escalonamento durante o CFP oferecem garantias temporais para as aplicações com restrições de QoS, modeladas de acordo com o modelo de tarefas (m,k)-firm. Dispositivos que não conseguem realizar suas transmissões durante períodos livres de contenção, poderão realizar suas transmissões utilizando a abordagem de priorização de tráfego tempo real desenvolvida para o CAP.In the last few years, the use of wireless networks has been increasingly seen in industrial automation and process control. Network Control Systems are examples of driving applications in industrial environments. For these types of applications, support for real-time communications services is one of the major requirements. In traditional approaches, many of these real-time applications assume no data losses during the control cycle. However some more recent studies indicate that the effect of control messages discards upon the performance of the control systems may be significantly encompassed with the adoption of other techniques. The IEEE 802.15.4 protocol is an attractive solution for a wide range of applications in the field of Wireless Sensors Networks and more recently in the field of wireless instrumentation. Thus, this thesis aims to propose approaches to providing Quality of Service (QoS) in IEEE 802.15.4 for real-time applications that tolerate deadline misses. First, a mechanism for prioritizing traffic for real time devices during Contention Access Periods (CAP) was proposed. This mechanism, called DDBP offers in a decentralized way, priority access in accordance to the distance to device failure. Subsequently, two approaches to scheduling during Contention Free Periods (CFP) were proposed: SDBP approach which provides deadlines guarantees by the adoption of a deterministic scheduling test and an on-line prioritization heuristic; and (m,k)-spin approach, which presents a schedulability analysis based on the busy period concept. The proposed approaches applied to the CFP scheduling provide temporal guarantees for applications with QoS constraints, modelled according to the (m,k)-firm task model. Devices that cannot perform their transmissions during contention free periods, can try to perform their transmissions using the real-time traffic prioritization approach developed for the CAP
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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