1,720,969 research outputs found
Modelling tracer dispersion from landfills
Full text linkSeveral wind tunnel experiments of tracer dispersion from reduced-scale landfill models are presented in this paper. Different experimental set-ups, hot-wire anemometry, particle image velocimetry and tracer concentration measurements were used for the characterisation of flow and dispersion phenomena nearby the models. The main aim of these experiments is to build an extensive experimental data set useful for model validation purposes. To demonstrate the potentiality of the experimental data set, a validation exercise on several mathematical models was performed by means of a statistical technique. The experiments highlighted an increase in pollutant ground level concentrations immediately downwind from the landfill because of induced turbulence and mean flow deflection. This phenomenon turns out to be predominant for the dispersion process. Tests with a different set-up showed an important dependence of the dispersion phenomena from the landfill height and highlighted how complex orographic conditions downwind of the landfill do not affect significantly the dispersion behaviour. Validation exercises were useful for model calibration, improving code reliability, as well as evaluating performances. The Van Ulden model proved to give the most encouraging results
Uncertainty and validation of urban scale modelling systems applied to scenario analysis in Tuscany, Italy
No full textInfluence of meteorological input parameters on urban dispersion modelling for traffic scenario analysis
No full text
INTERCOMPARISON, SENSITIVITY AND UNCERTAINTY ANALYSIS BETWEEN DIFFERENT URBAN DISPERSION MODELS APPLIED TO AN AIR QUALITY ACTION PLAN IN TUSCANY, ITALY
Full text linkThe Tuscan Regional Administration funded project MoDiVaSET-2 (MOdellistica DIffusionale per la VAlutazione di
Scenari Emissivi in Toscana 2) was established in order to develop a decision support modelling system for implementing the Air
Quality Action Plan for the metropolitan area of Florence, Prato and Pistoia. The objective of the work is to build an integrated
meteorological and dispersion models for simulating and evaluating different future emission scenarios of PM10, NOx and NO2 in
the study area. With this purpose, the project included several 1-year long dispersion modelling applications and a detailed
evaluation study, including sensitivity, validation and uncertainty analysis. Several dispersion models (ADMS-Urban, CALPUFF,
CALINE4, SAFE AIR II and CALGRID) were applied and evaluated against monitoring data; the intercomparison between
different models is crucial in order to develop reliable modelling techniques.
The obtained results point out the importance of including the following critical factors: smaller scale effects (monitoring stations
are often located in complex environments; this implies a decrease in the effectiveness of validation studies) and secondary
pollution (primary PM10 levels are only a small part of the total PM10 concentrations; much of the urban PM10 is actually produced
by chemical transformations and other physical mechanisms, for example, resuspension).
In order to understand the weight of these issues, further modelling options (full chemistry and street canyon simulations) were
investigated by using CAMx and smaller scale nested models.
All the factors listed above affected the evaluation work. However, this does not alter the validity of the scenario analysis, because it
is based on the differences between calculated primary pollutants concentrations
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
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