1,720,969 research outputs found
A proposal of SDN based VANET architecture for urban intersection management
Get PDFOne of the main challenges for developed cities is vehicle traffic management. There are many studies about urban intersection managements both in literature and in practice. In recent years, VANET (Vehicular ad hoc networks) has been preferred in these studies, which enables vehicles to easily communicate with each other or with RSUs. On the other hand, there are many studies on a new network paradigm called SDN (software defined networks) that solves problems such as performance, programmability, scalability etc. difficulties in today's networks. Depending this, in this study, we will present an architectural proposal about how to use SDN and VANET paradigms together in intersection management systems in order to use both existing and future intersection management system modules more adaptively and in desired service quality. In addition, to show the functionality of the proposed architecture for signaling system, we propose an ant colony algorithm based SDN controller's modules. The results obtained from ant colony algorithm based SDN modules were compared with other signaling techniques in literature on a isolated intersection. It shows that the proposed algorithm and architecture provide an improvement about % 15-22 according to existing systems and % 7-12 according to computational techniques in average delay and queueing
A 3-stage fuzzy-decision tree model for traffic signal optimization in urban city via a SDN based VANET architecture
No full textOne of the main challenges for developed cities is vehicle traffic and its management. Because of physical structures and cross roads of urban intersections, traffic flows may cause time delay, congestion, traffic accidents and more fuel/time consumption. For these reasons, there are many studies on traffic management systems which are a part of smart city applications in both literature and practice. In recent years, it seems that VANET (Vehicular Ad Hoc Networks) architecture has been preferred in these studies, which enables vehicles to easily communicate with each other or devices on the edge of the road and also to transfer the related traffic data to the center. On the other hand, there are many studies on a new network paradigm called SDN (Software Defined Networks) that solves problems such as performance, programmability, scalability, security and management difficulties in today's traditional networks. Depending on all this, in this study, we will present an architectural proposal about how to use SDN and VANET network paradigms together in traffic management systems in order to use both existing intersection management system modules more adaptively and future traffic based services to be added in desired service quality without changing the communication infrastructure. Also in this study, a 3-stage fuzzy-decision tree model was proposed for traffic signaling which is the most important problems of urban traffic by focusing environmental factors (accident situation, priority vehicle transition etc.) and activity information (road construction, meeting, train and bus schedule etc.) not only vehicle density unlike other signaling studies in literature. The proposed model also generates/sends a dynamic flow input to SDN agent vehicles and SDN agent RSU (Road Side Unit) in intersection for making VANET routing protocols (AODV-ad hoc on-demand distance vector, DSDV-destination-sequenced distance vector) selection automatically according to traffic incident and density. In order to measure the functionality of the SDN based VANET architecture and 3 stage fuzzy-decision tree model on it for the transmission infrastructure of the traffic management, performance tests were performed on different traffic and network scenarios on Adapazari City Centre Model. SDN based VANET architecture was compared with traditional systems according to transmission infrastructure and also proposed 3-stage fuzzy-decision model was compared with signaling techiques in literature such as fixed-time signaling, Webster equation, ant colony algorithm and particle swarm optimization under same traffic and network scenarios. The results obtained from performance tests shows that the proposed 3-stage fuzzy-decision model has %15-17 better performance than fixed-time signaling and webster equation and also %9-11 better performance that particle swarm and ant colony optimizations in low density traffic scenarios. In high density and dynamic traffic scenarios these rates reach %20-22 compared to fixed-time signaling and webster equation and %14-15 compared to particle swarm and ant colony optimizations. In addition in this study, proposed SDN based VANET architecture was compared to traditional VANET ITS architectures within the same traffic and network scenarios. According to obtained results, it is shown that the proposed SDN based VANET has %30-40 better performance than traditional systems in end-end delay, throughput and packet loss rate criteria. (C) 2019 Elsevier B.V. All rights reserved
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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