1,720,999 research outputs found
Rheological effects related to neo-fracturing processes in rock masses
Full text linkRockfall hazard is one of the main natural hazards in mountainous areas and along transportation routes. Roads and railways interruptions, as well as damages of buildings, are among the main inconveniences due to the detachment of unstable sectors of highly jointed rock masses. Rockfalls are the result of the combined action of the rock mass creep and of the natural and anthropic solicitations, which lead to the accumulation of inelastic strain within the rock mass and to the formation of new fractures or to the extension and movement of the pre-existing ones (rock mass damaging phenomena). The understanding of rock damaging processes through the microseismic monitoring of rock slopes predisposed for instabilities events can help in defining proper risk mitigation strategies. With the aim of assessing rock mass damaging phenomena, this PhD thesis proposes an analysis of the damping ratio associated with the microseismic emissions recorded in two test sites located in central Italy. Three monitoring campaigns have been conducted: two at the Acuto quarry test site, where the vibrational behaviour of a 12 m3 rock block partially detached from the back rock wall has been investigated; one at the Terni-Giuncano railway test site, where a rock mass close to a railway was studied to analyse the effects produced by the repeated trains transit. A STA/LTA event detection algorithm has been implemented for the recognition of the microseismic emissions from the seismic datasets acquired in continuous mode and with a sampling frequency of 2400 Hz. The damping ratio of the microseismic emissions, filtered in monofrequential waveforms, was evaluated; in the following, the daily mean damping values for each frequency were compared in respect to the environmental parameters monitored on site. No irreversible trend variations were observed, but significant variations related to transient processes were detected. It is deemed that the proposed approach can be applied on yearly seismic dataset and environments exposed to natural and anthropic forcing actions, to be furtherly tested and validated. Additional analyses were carried out on the train transit recordings. Each train passage was analysed in terms of: a) RMS value of the recording; b) cross-correlation between couples of sensors. The observation of the RMS and cross-correlation time series over time confirmed the unvaried long-term vibrational behaviour of the rock mass, according to the results of the damping analysis. In addition, the seismic noise was investigated by computing the average noise in one-minute intervals filtered at specific frequency bands. The cumulative of the filtered intervals allowed to determine the main energised frequency band, which resulted to be the one comprised between 500 and 1000 Hz. The derivative of the averaged noise was compared with the environmental parameters recorded in the two test sites. A marked correlation between the variation of air and rock mass temperature and the derivative of the noise in the frequency band comprised between 0.5 and 30 Hz was noted, while the correlation is feeble or lost for the other frequency bands considered. The correlation observed between thermal cycles and ambient noise variations is in agreement with previous bibliographical studies; moreover, a differentiation in the vibrational response for the different frequency bands has been detected
Seismometric monitoring of hypogeous failures due to slope deformations
No full textResults from a seismometric monitoring of rock mass failures affecting a karstified slope are here presented. The slope, located in Central Apennines (Italy), hosts a drainage plant and is involved in gravity-induced deformations. Starting from September 4, 2008 four accelerometric stations were installed within the tunnels of the drainage plant. More than 1,000 events, referred to both earthquakes and hypogeous rock mass failures, were recorded. The frequencies of occurrence of earthquakes and rock mass failures result to be generally well correlated; nevertheless, many hypogeous instabilities can be directly associated to the continuous slope deformations. The trend of the cumulative Arias intensity derived for the hypogeous instabilities shows a time variable rate which was used as a tool for monitoring the deformational process of the slope as well as for managing the associated geological risk by the use of alert or alarm plans. © Springer-Verlag Berlin Heidelberg 2013
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
Parametric Nnumerical study of observed amplification effects on the Colle di Roio limestone ridge (Central Italy)
No full textkoamabayili/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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