1,720,962 research outputs found
Regional analysis of flooding and flash flooding
Full text linkImproving the capacity to make predictions in ungauged basins is one of most difficult challenge for the scientific community (see for example the current initiative Prediction Ungaged Basins (PUB) launched by the International Association of Hydrological Sciences, IAHS). Whatever hydrological models are used, in view of the tremendous spatio-temporal heterogeneity of climatic and landscape properties, extrapolation of information, or knowledge, from gauged to ungauged basins remains fraught with considerable difficulties and uncertainties, especially in the light of the generally poor understanding of where water goes when it rains, what flow path it takes to the stream, and the age of the water that emerges in the channel.
The PUB problem is the key concept of this thesis and it is analysed from several point of view. Methodologies able to observe, model and predict the hydrological response at the regional scale are proposed
Influence of errors in radar rainfall estimates on hydrological modeling prediction uncertainty
No full textAnalisi della stabilità temporale dell'umidità del suolo in un piccolo bacino dolomitico
No full text(volume curato da G. Bischetti
Regional frequency analysis of extreme precipitation in the eastern Italian Alps and the August 29, 2003 flash flood
No full textThe main objective of the study is to characterise the severity of a flash flood-generating storm occurred on 29 August 2003 on the upper Tagliamento river basin, in the eastern Italian Alps. This storm was characterised by extraordinary rainfall amounts and large spatial variability. Regional frequency analysis based on the index variable method and L-moments is utilized to analyse short duration annual maximum precipitation for the Friuli-Venezia Giulia region, in north-eastern Italy, which includes the storm location. It is shown that the regional growth curves based on the Kappa distribution may be useful for the subregions specified. This analysis provides a framework to investigate the frequency characteristics of the 29 August 2003 flash-flood-generating storm for various rainfall durations. Radar rainfall estimates, adjusted by using a physically-based methodology and data from a raingauge network, are used to characterise the return period of the storm rainfall amounts, highlighting the importance of considering its spatial dimension. Severity graphs are developed to visualise the return periods and their variability for different rainfall durations within the storm. It is shown that adjusted radar rainfall estimates may suffer for considerable uncertainty and that the uncertainty magnifies in the evaluation of the relevant return periods. The analysis shows also that i) attributing a single return period to a storm event is not realistic, and ii) the severity of flash flood generating storms is poorly captured by using conventional raingauge networks. The reported results show that estimates obtained by using careful adjustment of radar observations may be useful to evaluate the severity of the storm for ungauged basins and to evaluate the spatial dimension of the frequency characterisation
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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