1,720,960 research outputs found
Real-time multicast P2P video streaming architecture based on scalable multiple descriptions
No full textIn the immediate future video distribution applications will increase their diffusion thanks to the ever-increasing user capabilities and improvements in the Internet access speed and performance. The target of this paper is to propose a content delivery system for real-time streaming services based on a peer-to-peer approach that exploits multicast overlay organization of the peers to address the challenges due to bandwidth heterogeneity. To improve reliability and flexibility, video is coded using a scalable multiple description approach that allows delivery of sub-streams over multiple trees and allows rate adaptation along the trees as the available bandwidth changes. Moreover, we have deployed a new algorithm for tree-based topology management of the overlay network. In fact, tree based overlay networks better perform in terms of end-to-end delay and ordered delivery of video flow packets with respect to mesh based ones. We also show with a case study that the proposed system works better than similar systems using only either multicast or multiple trees
A P2P platform for real-time multicast video streaming leveraging on scalable multiple descriptions to cope with bandwidth fluctuations
No full textIn the immediate future video distribution applications will increase their diffusion thanks to the ever-increasing user capabilities and improvements in the Internet access speed and performance. The target of this paper is to propose a content delivery system for real-time streaming services based on a peer-to-peer approach that exploits multicast overlay organization of the peers to address the challenges due to bandwidth heterogeneity. To improve reliability and flexibility, video is coded using a scalable multiple description approach that allows delivery of sub-streams over multiple trees and allows rate adaptation along the trees as the available bandwidth changes. Moreover, we have deployed a new algorithm for tree-based topology management of the overlay network. In fact, tree based overlay networks better perform in terms of end-to-end delay and ordered delivery of video flow packets with respect to mesh based ones. We also show with a case study that the proposed system works better than similar systems using only either multicast or multiple trees
Design of a service platform for delay-sensitive video streaming applications based on multicast p2p and scalable MDC encoding
No full textThe great diffusion of Internet accesses in the world and the enormous evolution of the Internet technologies have strongly determined dissemination and consolidation of many applications of video content distribution. However, multicast real-time video communications for interactive service applications with a very high number of users, like for example multipoint videoconferences and interactive video games, remains a challenging research topic for the presence of very strict requirements in terms of end-to-end delay and perceived quality.
The target of this paper is to propose a video distribution platform that is able to provide a huge number of users with a delay constrained multicast video streaming. To this purpose, the proposed content delivery platform is based on a peer-to-peer approach that exploits multicast overlay organization of the peers to address the challenges due to bandwidth heterogeneity. To improve reliability and flexibility, video is coded using a scalable multiple description approach. Some design guidelines are provided taking into account some requirements in terms of delay, average PSNR, robustness against underlying network bandwidth fluctuations, and fairness
Adjective Semantics in Open Knowledge Extraction
Full text linkAdjectives carry a lot of discourse semantics, often being the core elements to understand the literal, emotional, cultural, and metaphoric meaning of a sentence. Their formal semantics has been investigated specially in lexical semantics and formal linguistics, with some contributions from formal ontology and the semantic web. However, no standard formal treatment of adjectives is available yet, which is capable to address the concerns of both theoretical and computational natural language understanding. In this paper we summarize the existing approaches, present some alternative solutions to approximate a rigorous but pragmatic representation, and describe an implementation of a lightweight adjective ontology as a core resource in FRED, a state-of-the-art open knowledge extraction tool
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
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