1,721,060 research outputs found
Fire behaviour simulation in Mediterranean maquis using FARSITE (fire area simulator)
Get PDFIn the last two decades several simulation systems were developed to provide
information about temporal and spatial variations of fire spread and behaviour. FARSITE
(Fire Area Simulator), one of the most common simulators, is a spatially and temporally
explicit fire simulation system. The simulator is based on Rothermel's fire spread model,
and describes the fire spread and behaviour as a function of relationships among fuels,
topography and weather conditions. The use of FARSITE on areas different from those
where the simulator was originally developed requires a local calibration in order to
produce reliable results. This is particularly true for the Mediterranean ecosystems,
where plant communities are characterized by high specific and structural heterogeneity
and complexity, determined by the interaction of sub-arid Mediterranean climate and
human factors. Therefore, to perform FARSITE calibration, the choice of the appropriate
standard fuel models or the development of specific custom fuel models are required. In
addition, the capabilities of FARSITE simulator can be affected by other environmental
characteristics, as complex steep terrains with the resulting high spatial and temporal
variability of wind speed and direction.
In this work, FARSITE was employed to simulate spread and behaviour of four
real fires occurred in North Sardinia during 2003, 2004 and 2006 summer seasons. The
effect of fuel models, weather conditions and topography on the accuracy of FARSITE
simulations was evaluated in order to assess the capabilities of the simulator in
accurately forecasting the fire spread and behaviour in areas covered by Mediterranean
maquis. A custom fuel model, designed and developed by our working group for maquis,
provided realistic values of simulated fire behaviour. Improvements on the accuracy of
both fire spread and behaviour were also obtained using raster maps of wind speed and
direction. The results confirm that the use of both accurate wind field data and
appropriate custom fuel models is crucial to obtain accurate simulations of fire
behaviour occurring on Mediterranean vegetation during the drought season, when
most wildfires occur
A web-based wildfire simulator for operational applications
No full textWildfire simulators and decision support systems can assist the incident command teams in charge of tactical wildfire suppression. This paper presents a web-based wildfire simulator developed to provide real-time support for wildfire management. The paper describes the overall software architecture, the modelling chain characteristics and the results produced by the simulator considering a set of actual wildfires that occurred in the island of Sardinia, Italy. The simulator consists of a graphical user interface that deals with data input-output management, a mass-consistent model devoted to the downscaling of wind fields, and a module that provides a spatially explicit representation of wildfire propagation. The simulator is a client'server application that is operated through a web-based graphical user interface that leaves the computational work to a dedicated server; most of the code is parallelised in order to minimise computational run-time. The validation phase demonstrated the capabilities of the simulator in providing wildfire predictions with a substantial agreement with actual wildfires, and a computational cost suitable for faster than real-time applications. The simulator is proposed as a tool to provide assistance to civil protection and fire management agencies during the incident response phase. The simulator is also appropriate for the training of personnel
Assessing the performance of fire danger indexes in a mediterranean area
No full textThe fire danger (FD) defines the conditions less or more favourable for a fire ignition success and its propagation. FD indexes, that integrates environmental variables related to FD in more or less complex equations and systems, are widely used in wildfire prone countries for both scientific and operational purposes. Assessing the performance of FD indexes is challenging and this issue is quite debated within the fire community, which has been trying to apply several methodologies to evaluate FD indexes. The main aim of this work is to give a contribution to this effort. The analysis was conducted using data from a fire-prone Mediterranean area (Sardinia island, Italy), where 8 FD indexes were evaluated and compared using different statistical approaches. We calculated the daily FD values for the period 2000-2007 over the study area. A set of statistical tools (namely Spearman rank correlation, Index Value Distribution and Percentile Analysis, and Logistic Regression) were applied to evaluate the performance of each FD index by comparing FD values with fire occurrence indicators. The statistical tests revealed a large variability in FD indexes performance, depending also on fire activity conditions. Our results showed that two of the tested FD indexes reached a good overall performance. Findings from this study can help both the scientific community and local fire managers, supporting the evaluation of early warning systems and fire prevention strategies in the Mediterranean Basin
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
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