1,721,968 research outputs found
Periodic Path Changes in RIPE Atlas
No full textLarge-scale data sets of the Internet measurements are commonly used by researchers and operators for investigating Internet performance or for tackling network issues. Looking at sequences of traceroutes in such data sets, it is common to observe paths that change over time. We are interested in verifying if there are periodic phenomena affecting such path changes and, if yes, in determining if they depend on artifacts of the used data set or on topology changes of the network. For this purpose, we devise a novel algorithm for detecting periodicities in sequences of traceroutes. Then, we exploit the algorithm for analyzing the traceroutes produced by the RIPE Atlas, a popular public measurement platform. We study and report the features of the found periodicities and some of their causes. We found that: 1) a surprisingly large percentage of the traceroutes exhibit a periodic behavior; 2) a large number of periodicities depend on the RIPE Atlas platform itself; and 3) a smaller amount is related to the MPLS and load balancing
Exploiting spectral differences between two acoustic imaging methods for the in situ evaluation of surface-breaking cracks in asphalt
No full textThe assessment of the location and the extension of cracks in roads is important for determining the potential level of deterioration in the road overall and in the infrastructure buried beneath it. Damage in a pavement structure is usually initiated in the tarmac layers, making Rayleigh waves ideally suited for the detection of shallow surface defects. In this work, the differences between the spectral images obtained with the Multichannel Analysis of Surface Waves (MASW) and the Multiple Impact of Surface Waves (MISW) are suggested for the first time to detect, locate and evaluate surface-breaking cracks in dispersive material, i.e. roads. Assessment of crack in roads is usually performed assuming constant velocity and non-dispersive behaviour of the material tested, limiting this approach to the very shallow layer of the road. The road is here holistically treated as a dispersive medium, supporting a paradigm-shifting approach to in situ crack evaluation. It is shown that surface-breaking cracks influence the content of the spectral images obtained with these two acoustic imaging techniques. Their differences are used for the first time for the in situ evaluation of the presence, the location and, in some cases, the extension of vertical cracks in roads. The study is conducted through numerical simulations, alongside experimental investigations. The paper describes two cases for which the cracking is internal and then external to the deployment of sensors. The method proposed in this paper proved to be successful for the in situ evaluation of cracks in asphalt, tackling the heterogeneities and dispersive behaviour of the material tested.</p
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
“Networks For Local Development: Planning a Local Festival (Cal-Iter) For the Avellino’s Cheese Industry”
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