1,721,015 research outputs found
Model Checking Techniques for the Performance Analysis of Delay Tolerant Networks with on-off Behavior
No full textSparse network of fixed or mobile wireless devices, where most of the time there does not exist a complete path from a source to a destination are often referred to as Delay Tolerant Networks. The store-carry-and-forward principle, according to which messages can be stored at mobile nodes moving around the network area before being forwarded to the destination, allows the transmission of messages in such systems. In this paper, we use an analytical framework to study Delay Tolerant Networks, based on asCSL model checking techniques. In particular we focus on the case in which fixed sensors exhibit on-off behavior to overcome battery capacity limitations
Performance Analysis of Delay Tolerant Networks with Model Checking Techniques
No full textDelay Tolerant Networks are a class of wireless networks that has recently attracted a lot of attention from the networking community. They are characterized by frequent network partitioning, intermittent connectivity, long and variable delays, high error rates. Such performance-challenging conditions are usually found in environments populated by a sparse set of fixed or mobile nodes with limited communication capabilities. The store-carry-and-forward principle, according to which messages can be stored at mobile nodes moving around the network area before being forwarded to the destination, has emerged as the new communication paradigm for delay tolerant networks, demanding novel performance evaluation tools and methodologies with respect to those developed in traditional store-and-forward packet networks. In this paper, we describe an analytical framework to study Delay Tolerant Networks, based on model checking techniques. In particular we employ the logic asCSL as a powerful formalism to define specific performance metrics suitable to analyze the behavior of these systems
A Queueing Network Model of Short-Lived TCP Flows with Mixed Wired and Wireless Access Links
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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
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