1,721,087 research outputs found
Componenti Avanzati GCM/SCA
No full textQuesta tesi fa prima una panoramica sullo stato dell'arte esistente in merito ai componenti software usati in ambito Grid e poi cerca di implementare un componente GCM: un behavioural skeleton task-farm usando come runtime di supporto SCA al fine di dimostrare la fattibilità e le presetazioni del behavioral skeleton sotto tale piattaforma
Esc: Towards an Elastic Stream Computing Platform for the Cloud
No full textToday, most tools for processing big data are
batch-oriented. However, many scenarios require continuous,
online processing of data streams and events. We present ESC,
a new stream computing engine. It is designed for computations
with real-time demands, such as online data mining. It offers
a simple programming model in which programs are specified
by directed acyclic graphs (DAGs). The DAG defines the data
flow of a program, vertices represent operations applied to
the data. The data which are streaming through the graph
are expressed as key/value pairs. ESC allows programmers to
focus on the problem at hand and deals with distribution and
fault tolerance. Furthermore, it is able to adapt to changing
computational demands. In the cloud, ESC can dynamically
attach and release machines to adjust the computational
capacities to the current needs. This is crucial for stream
computing since the amount of data fed into the system is
not under the platform´s control. We substantiate the concepts
we propose in this paper with an evaluation based on a highfrequency
trading scenario
P4SINC - An Execution Policy Framework for IoT Services in the Edge
No full textInternet of Things (IoT) services are increasingly deployed at the edge to access and control Things. The execution of such services needs to be monitored to provide information for security, service contract, and system operation management. Although different techniques have been proposed for deploying and executing IoT services in IoT gateways and edge servers, there is a lack of generic policy frameworks for instrumentation and assurance of various types of execution policies for IoT services. In this paper, we present P4SINC as an execution policy framework that covers various functionalities for IoT services deployed in software-defined machines in IoT infrastructures. P4SINC supports the instrumentation and enforcement of IoT services during their deployment and execution, thus being leveraged for other purposes such as security and service contract management. We illustrate our prototype with realistic examples
Markovian Workload Characterization for QoS Prediction in the Cloud.
Get PDF11.10.13 KB. Accepted version ok to add to spiral. IEEEResource allocation in the cloud is usually driven by performance predictions, such as estimates of the future incoming load to the servers or of the quality-of-service (QoS) offered by applications to end users. In this context, characterizing web workload fluctuations in an accurate way is fundamental to understand how to provision cloud resources under time-varying traffic intensities. In this paper, we investigate the Markovian Arrival Processes (MAP) and the related MAP/MAP/1 queueing model as a tool for performance prediction of servers deployed in the cloud. MAPs are a special class of Markov models used as a compact description of the time-varying characteristics of workloads. In addition, MAPs can fit heavy-tail distributions, that are common in HTTP traffic, and can be easily integrated within analytical queueing models to efficiently predict system performance without simulating. By comparison with trace-driven simulation, we observe that existing techniques for MAP parameterization from HTTP log files often lead to inaccurate performance predictions. We then define a maximum likelihood method for fitting MAP parameters based on data commonly available in Apache log files, and a new technique to cope with batch arrivals, which are notoriously difficult to model accurately. Numerical experiments demonstrate the accuracy of our approach for performance prediction of web systems. © 2011 IEEE
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
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