1,720,973 research outputs found
Caratterizzazione territoriale della sicurezza sismica di strutture e infrastrutture critiche e rilevanti
Full text linkLa progettazione sismica di strutture critiche e rilevanti si basa usualmente su un’analisi di pericolosità sismica con approccio probabilistico che deve tener conto anche di eventi a bassa probabilità di eccedenza rispetto a un edificio ordinario. Nel presente studio la valutazione della pericolosità sismica, per un sistema di distribuzione di petrolio greggio localizzato in Friuli Venezia Giulia, nel nord-est Italia, è stata valutata in termini del picco di accelerazione (PGA) e velocità (PGV) per la sua componente orizzontale e Intensità di Arias, con una probabilità di eccedenza del 2% in 50 anni (corrispondente a un tempo di ritorno di 2475 anni).
In questo studio i maggiori eventi sismici sono stati associati alle sorgenti lineari derivate dal database italiano delle sorgenti sismiche (DISS Working Group, 2010) considerando un modello caratteristico del terremoto. Una zonazione sismogenica è stata aggiunta a tali sorgenti lineari al fine di caratterizzare la sismicità minore descrivendola mediante il modello di sismicità di Gutenberg-Richter. Infine sono state aggiunte al modello di sorgenti sismogeniche anche le faglie quaternarie localizzate nell’area del golfo di Trieste che hanno dimensioni sufficienti per giustificare, almeno, una magnitudo caratteristica di 6.
I risultati delle mappe di pericolosità sismica riferiti ai tre tipi di suolo (roccia, suolo rigido, suolo soffice) sono stati aggregati, attraverso la tecnologia GIS, in una singola mappa, definita pericolosità sismica alla superficie libera, sulla base delle caratteristiche litologiche locali.
Nel presente studio è stato considerato il sistema di distribuzione di petrolio greggio che connette Trieste (Italia) a Ingolstadt (Germania). Esso consiste in un deposito di stoccaggio costituito da 32 serbatoi, da 4 stazioni di pompaggio e dalla condotta sepolta. Quest’ultima componente è interrata, pertanto è stato necessario anche caratterizzare la pericolosità da possibili fenomeni di fagliazione superficiale, di liquefazione e movimenti gravitativi, che inducono rotture del terreno, e calcolare lo spostamento permanente del terreno (PGD).
La vulnerabilità delle tubazioni interrate è comunemente descritta in letteratura da curve di fragilità che relazionano un indicatore di prestazione, come il tasso di riparazione (numero di rotture per chilometro) stimate da dati empirici (osservazionali) come una funzione di scuotimento di parametri rappresentativi (PGA, PGV). Nel presente studio, oltre a tale metodologia è stata anche considerata una rappresentazione alternativa orientata alle conseguenze di un’eventuale rottura, cioè alle perdite di sostanze pericolose nell’ambiente nel caso in cui la condotta sia soggetta a un evento sismico.
Nell’ultima fase del lavoro si è effettuata la convoluzione, per ciascun sito del percorso dell’oleodotto, tra la curva di pericolosità sismica (che rappresenta la probabilità in 50 anni di superare certi livelli di scuotimento in termini di PGA e PGV nella loro componente orizzontale), e le curve di fragilità (che rappresentano la probabilità dell’elemento a rischio di raggiungere o superare differenti stati di danneggiamento), che permetterà di calcolare la probabilità di osservare danni e conseguenti perdite di contenuto di sostanze contaminanti sull’ambiente esterno
Seismic hazard from natural and induced seismicity: a comparison for Italy
Full text linkThe seismic hazard resulting from seismicity induced by human activity is not yet regulated in Italy. The presence of a significant natural seismicity complicates the differentiation of events possibly induced by human activity from ordinary natural seismicity, while it stimulates a comparison between the ground motion that can be expected due to tectonic events and the shaking caused by man-induced events. The
problem is complicated by the fact that it is not possible to compare homogeneous hazard estimates for the two classes of seismicity, since it is difficult to define the induced seismicity in terms of probabilities for a given return time. This paper provides an example of how the problem was first tackled in an Environmental Impact Assessment (EIA) procedure, and then attempts a nationwide extension of the results
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
Caratterizzazione della danneggiabilità sismica di infrastrutture critiche lineari: il caso dell’oleodotto in Friuli Venezia Giulia
No full textVariations 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
Characterization of the expected seismic damage for a critical infrastructure: the case of the oil pipeline in Friuli Venezia Giulia (NE Italy)
No full textSeismic codes using the performance-based approach for seismic design of critical and important structures generally refer to seismic hazard which takes into account a lower exceedance probability than that used for ordinary buildings. In the present study, the seismic hazard for an oil pipeline, located in the Friuli Venezia Giulia region (NE Italy), has been calculated in terms of PGA and PGV with a 2475-year return period, and compared with estimates calculated with the standard 475-year return period used for ordinary buildings. The results, referring to three soil types (rock, stiff soil, and soft soil), have been combined through GIS technology in a single map (soil seismic hazard map) on the basis of the local lithological characterization. The major earthquakes considered in the study have been associated with the linear sources found in the database of Italian seismic sources, considering the characteristic earthquake model. The regional seismogenic zonation has been added to the linear sources in order to consider minor seismicity as described by the Gutenberg-Richter model. Quaternary faults in the broader Trieste area, long enough to justify, at least, a characteristic magnitude of 6, have been added in the source model to take into account unlikely but possible unknown sources. The Transalpine Oil Pipeline, which connects Trieste (Italy) to Ingolstadt (Germany), is the crude-oil distribution system considered in the present study. It consists of a storage tank, compressor stations, and buried pipeline. For the characterization of the expected damage to the infrastructure in case of an earthquake, we have used underground pipeline seismic vulnerability curves that relate a performance indicator, such as the reparation rate (number of ruptures per kilometre), with a representative ground motion parameter (e.g., PGA or PGV). In this study, we have considered as performance indicator the consequences of a rupture in the pipeline caused by a seismic event
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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