1,720,976 research outputs found
Sulla stima delle piene di progetto
No full textThe paper summarizes in a systematic way the results of the studies carried out by the writers on the topic of the estimation of design floods; some aspects are examined on the basis of new critical remarks.
The first part of the paper deals with the estimation of design peak discharge. It is based on the results of a regional analysis performed on more than 7000 gauging stations belonging to different geographical areas (mainly North America, Great Britain, Switzerland and Italy). Such analysis, which lead in previous papers to the formulation of a general probabilistic model (MG model), is here carried on in order to examine in more detail the performances of the proposed model. Some aspects regarding the estimation of peak discharge in ungauged sites are also considered.
The second part of the paper deals with the evaluation of synthetic hydrographs on the basis of the statistical analysis of floods recorded at the gauged sites. The considered case studies point out the ability of the methodology to characterize, from a statistical point of view, the response of systems to flood phenomena (flood routing in rives, peak flow reduction by means of flood control reservoirs). Application examples of the procedure to ungauged sites are given and the applicability range of the methodology is examined.
La presente memoria riprende i risultati delle ricerche condotte dagli scriventi sul tema della stima delle piene di progetto, risultati che hanno formato oggetto negli ultimi anni di pubblicazioni apparse in diverse sedi. Viene quindi proposta una sintesi organica e unitaria di tali ricerche e l’approfondimento di taluni aspetti sollecitati da nuove riflessioni critiche.
La memoria è divisa in due parti. Nella prima, dedicata alla stima della portata al colmo di progetto, vengono ripresi e sviluppati i risultati di un’analisi regionale condotta a partire dalle serie storiche delle portate al colmo massime annue registrate in più di 7000 stazioni idrometrografiche appartenenti a diverse aree geografiche (principalmente America del Nord, Gran Bretagna, Svizzera e Italia). L’analisi, che ha portato in precedenti lavori alla definizione di un modello probabilistico di validità generale (modello MG), viene approfondita allo scopo di meglio evidenziare la struttura e le proprietà di tale modello e le sue prestazioni in relazione ad altre distribuzioni di probabilità frequentemente impiegate nell’analisi statistica delle portate di piena. Vengono inoltre esaminati alcuni aspetti relativi alla stima delle portate al colmo in sezioni non strumentate.
Nella seconda parte della memoria, dedicata alla stima dell’onda di progetto, viene ripresa la metodologia proposta dagli scriventi per la definizione di onde sintetiche a partire dall’interpretazione statistica di alcuni caratteri fondamentali delle piene osservate nelle sezioni strumentate. In particolare, viene evidenziata l’efficacia del metodo nel sintetizzare in termini statistici i comportamenti idraulici di sistemi naturali o artificiali interessati da fenomeni di piena (propagazione in alvei fluviali, attenuazione delle portate al colmo attraverso l’impiego di interventi di laminazione). Vengono infine ripresi alcuni casi di applicazione relativi a sezioni non strumentate e vengono esaminati i vantaggi e i limiti di applicabilità della metodologia rispetto ad approcci alternativi proposti nella letteratura di settore
Sulla relazione tra portata media giornaliera e al colmo
No full textIn the paper the relationship between the yearly maxima of the peak discharge Q and the mean daily discharge q with the same return period is examined, analyzing the data relevant to the Po basin stations. The analysis shows that the relationship can be assumed to be linear and the ratio R between Q and q can either increase or decrease as the return period increases. The effect exercised on R by the main basin hydrological and geomorphological characteristics is also analyzed. It turns out that R decreases with the return period when the basin is very large and the q variability, represented by the variation coefficient, is high
VERIFICA DEL FUNZIONAMENTO IDRAULICO E DEL RISCHIO RESIDUO IN CANALI IRRIGUI NELLA PIANURA MANTOVANA
No full text
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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