1,720,955 research outputs found
Wireless Ad-Hoc Networks: from Sensing to Socializing
No full textThe first part of this dissertation is related to static Sensor Networks and focuses on one of their most typical and restricting features, that is the limited availability of energy to power sensor nodes. We propose a routing protocol that effectively prolonges the network's lifetime through a new load-balancing technique. The protocol only uses locally available information, thus requiring a very low communication overhead. Moreover, all routing decision are made during a pre-processing stage, taking place before the proper network activity starts. No energy related information needs to be exchanged by nodes after pre-processing, although work-load results to be well distributed among sensor nodes. As a consequence, the strength of energy related attacks from malicious nodes happens to be heavily reduced.
In the second part of the dissertation we focus on Pocket-Switched Networks and define of a new unexplored problem related to the area of broadcasting. Broadcasting in Pocket-Switched Networks is usually intended to reach most of the nodes in a network, but does not guarantee to reach all of them. On the contrary, we propose a distributed protocol for the implementation of a reliable broadcast primitive – a broadcasting protocol where every single node is sure to receive any broadcast message circulating in the network. To this end, we consider hybrid networks where nodes can communicate through a short-range communication technology, such as Bluetooth or WiFi, and through a long- range communication infrastructure, such as cellular networks. In our reliable broadcast protocol, nodes use the short-range communication as much as possible and resort to long-range communications only sporadically. The goal is achieved through the inspection of the social links defined by the short-range contacts logged on the portable devices forming the network. Benefits in terms of cost and cellular network offload are showed
Fine grained load balancing in multi-hop wireless networks
No full textIn this paper we address the problem of local balancing in multi-hop wireless networks. We introduce the notion of proactive routing: after a short pre-processing phase in which nodes build their routing tables by exchanging messages with neighbors, we require that nodes decide the relay of each message without any further interaction with other nodes. Besides delivering very low communication overhead, proactive routing protocols are robust against some well known active attacks to network routing. In this framework, we develop a proactive routing protocol that is able to balance the local load. Experiments show that our protocol improves network lifetime up to 98% and that it delivers a network that is more robust against attacks that have the goal of getting control over a large part of the network traffic. (C) 2012 Elsevier Inc. All rights reserved
Count on me: Reliable broadcast and efficient routing in DTNs through social skeletons
No full textThis paper challenges the belief that reliable broadcasting and efficient routing primitives are not possible when DTNs are involved. Firstly, we present COM, a reliable broadcasting mechanism for hybrid networks where nodes can rarely use long-range and costly communication links (e.g. 3G) to complete missing opportunistic links. COM is based on the Social Skeleton, a compact and connected subgraph, computed in an efficient and distributed way, that best represents the strongest social links among nodes. COM exploits the Social Skeleton to guarantee reachability of 100% of nodes with the lowest number of long communications. Then we empirically prove that the Social Skeleton can be used to build routing mechanisms upon it. We deliver SR (Skeleton Routing), which involves at most 3 copies per message, and yields delivery rates up to 5.5 times higher than state-of-the-art forwarding protocols
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
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