1,720,959 research outputs found
Thermal radiation modelling in tunnel fires
No full textModelling based on Computational Fluid Dynamics (CFD) is by now effectively used in fire research and hazard analysis. Depending on the scenario, radiative heat transfer can play a very important role in enclosure combustion events such as tunnel fires. In this work, the importance of radiation and the effect of the use of different approaches to account for it were assessed. Firstly, small-scale tunnel fire simulations were performed and the results compared with experimental data, then realistic full-scale scenarios were simulated. The results show up the capability of CFD modelling to reproduce with good approximation tunnel fires. Radiation proved to be noteworthy mainly when the scale of the fire is relatively large. Among the various approaches employed to simulate radiation, the use of the Discrete Transfer model gave the most accurate results, mainly when the absorption-emission characteristics of the combustion products were taken into account. Finally, the suitability of the use of CFD in quantitative Fire Hazard Analysis is discussed. © 2011 Global Science Press
Simulation of fire scenarios due to different vehicle types with and without traffic in a bi-directional road tunnel
No full textThis paper presents findings obtained by CFD modelling for simulating the effects of fire due to different vehicle types in a hi-directional road tunnel. Four different burning vehicles placed in the centre of the driving lane at tunnel middle length were considered. Peaks of the heat release rate (HRR) of: 8, 30, 50, and 100 MW were simulated for the two cars, the bus, the heavy goods vehicle (HGV), and the petrol tanker, respectively. The fire effects on tunnel structure and on environmental conditions along people evacuation path were especially evaluated. The effects of the traffic jam, in contrast with the isolated vehicles, on temperatures, radiant heat flux, visibility distance, and toxic gases concentrations, were also investigated. The worst scenario was identified to be that pertaining to the petrol tanker and more critical conditions were also found when the tunnel-was full of vehicles. The maximum gas temperatures reached in the presence of traffic at the side wall (and at the tunnel ceiling reported in brackets) were found to be: 360 degrees C (170 degrees C) for the two cars; 740 degrees C (465 degrees C) for the bus; 835 degrees C (735 degrees C) for the HGV and 1305 degrees C (1145 degrees C) for the petrol tanker, respectively. The presence of the traffic, in contrast with the isolated vehicle, involved an increase in the maximum temperatures equal to 16-17% for the two cars, and contained in the range 12-29% with percentages increasing starting from the tanker, to the HGV and to the bus. In other words when the maximum temperatures produced by the isolated vehicle are very high (e.g. for the tanker), the presence of the traffic had a minor effect. With reference to environmental conditions along the evacuation path, the results showed that in the case of petrol tanker fire the emergency ventilation ensures a tenable level of temperature, radiant heat flux, and toxic gases concentrations up to 5 min from the fire starting. This time increases up to 6.5 min for the HGV and 8 min for the bus. This means that the tunnel users in order to be safe in all scenarios should leave the tunnel within 5 min after the fire starting. Toxic gases concentrations, however, were found to be below the limit values in all cases and also in the presence of traffic. In the light of the aforementioned results, tunnel occupants should be promptly informed of the fire risk and guided to the exit portals. This might be done by equipping the tunnel with illuminated emergency signs located along the tunnel length and by installing traffic lights before the entrances so that the tunnel can be closed in case of emergency. By activating the traffic lights at the portals and the emergency signs (more especially those at the ceiling) at the same time as the emergency ventilation is activated, safer conditions for the people evacuation are expected. (C) 2013 Elsevier Ltd. All rights reserved
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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