1,721,064 research outputs found
Overview on the Recent Evolution in High-Speed Optical Access Networks
No full textIn this Chapter, we give an overview of the current status and expected
medium-long term (5-10 years from now) evolution of optical fixed access networks, which
have seen an enormous growth in deployment rate in Europe in the last decade, with an
annual Compounded Average Growth Rate (CAGR) that is steadily above 10% in most
EU Countries. Up to now (mid 2023), this growth in commercial volumes was mostly led
by the extensive deployment of Fiber-to-the-Home (FttH and its FTTx variants). In the
future, it is expected that optical access networks, while continuing their growth in FttH
market penetration, will also become more and more the fundamental transport technology
of 5G and next generation 6G mobile wireless networks, and in general of new network
edge applications
Integrated Public Mobile Radio Networks/Satellite for Future Railway Communications
Full text linkThe European train control system employs GSM-R for communications between trains and the command/control centers. GSM-R technology is quite old and will be replaced in the near future by other technologies offering less expensive solutions, especially for regional and local lines. This article investigates a new telecommunication solution based on multi radio bearers using cellular and satellite public networks as an alternative to the deployment of a dedicated infrastructure. A test campaign on a 300 km of rail line (about 10,000 km of tests) has been carried out to evaluate the performance of cellular and satellite networks in a railway environment. Test trial results presented and discussed in this article have been used to assess the performance of a multipath TCP protocol to effectively support multi-bearer communications. A discussion of the economic benefits and the potential industrial implications of the proposed solution concludes the article
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
Security Access Protocols in IoT Networks with Heterogenous Non-IP Terminals
No full textTo provide advanced services to citizens, Smart City services are enabled by a massive use of Internet of Things (IoT) technologies. The envisaged huge amount of sensors, and terminals with a great variety of typologies and applications, do not allow having a unique way to manage them, requiring for example minimal packaging and presentation overhead for many of them. In general in a network providing Smart City services, both IP and non-IP devices are present. In this paper, we tackle the security issue for non-IP devices able to connect by a short-range with a mediator gateway, forming a capillary access network, which can be seen as a short range extension of conventional access network in order to efficiently capture the IoT traffic. In particular, we propose security algorithms both for uni- and bi-directional terminals, depending on the terminal capabilities. The security algorithms are based on a local key renewal (without any exchange in air), performed just considering the local clock time. Performance are obtained respect to the maximum number of terminals that can be managed by one mediator gateway and the maximum packet delay as a function of the number of terminals in the area. © 2014 IEEE
Security Access Protocols in IoT Capillary Networks
Full text linkSmart city services are enabled by a massive use
of Internet of Things (IoT) technologies. The huge amount of
sensors, and terminals with a great variety of typologies and
applications, requires a secure way to manage them. Capillary
networks can be seen as a short range extension of conventional
access network in order to efficiently capture the IoT traffic, and
are enablers for smart city services. They can include both IP
and non-IP devices, and security can become an issue, especially
when simple unidirectional communication devices are considered.
The main goal of this paper is to analyze security aspects
in IoT capillary networks including unidirectional and bidirectional
IP or non-IP devices. We propose an algorithm for secure
access for uni- and bi-directional devices. The security procedure
is based on a secure key renewal (without any exchange in air),
considering a local clock time and a time interval of key validity.
Following previous work in 2014 by Giuliano et al., in this paper
we assess the duration of the validity of the time window, and
present extended simulation results in terms of (average) transmission
time in a realistic scenario, i.e., including the presence
of disturber(s), then providing indications for the setting of the
duration of the key validity time window. Finally, we present the
benchmark analysis in order to assess the effectiveness of our
approach with respect to other existing standards, as well as the
security analysis in terms of typical attacks
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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