1,721,259 research outputs found
How Far from a Building Does the Ground-Motion Free-Field Start? The Cases of Three Famous Towers and a Modern Building
No full textIt is well known that artificially inducing large amplitude vibrations on buildings produces seismic waves that are detectable up to a few kilometers away. Does a similar effect occur with seismic tremors? If the tremor wave field were perturbed by the presence of buildings, passive surveys in a urban environment would be potentially impaired. The literature is rather inconclusive on this issue. We experimentally analyzed the cases of three of the most famous Italian towers: the leaning tower of Pisa, the bell tower of San Marco in Venice, and the Asinelli tower in Bologna. We also analyzed a large modern 16 story residential building. Even performing the measurements in windy days, we found no cases in which the large structures perturb the free-field tremor at distances larger than 12 m. This confirms what was expected from simple dimensional analysis and suggests that passive soil–structure interaction is of little concern for standard buildings and standard ambient condition
Leggi di natura, prevedibilità, probabilità
No full textSecondo una lunga tradizione, durata almeno fino alla metà dell’Ottocento, la scienza si è ispirata all’ideale deterministico, ossia alla tesi che i fenomeni sono regolati da leggi causali, conoscendo le quali è possibile tanto spiegare quanto la prevedere. Gli sviluppi delle scienze fra Otto e Novecento hanno messo in crisi il determinimo, e con esso lo stretto legame fra spiegazione e previsione, ponendo in primo piano la probabilità, strumento chiave per la previsione. Tuttavia, laddove non si disponga di leggi deterministiche, ma statistiche, tanto la spiegazione quanto la previsione divengono più problematiche. In generale, si può dire che l’accuratezza delle previsioni probabilistiche dipende dalla quantità e dalla qualità dell’informazione disponibile. Eventi derivanti dal concorso di molti fattori di diversa natura, a volte difficilmente quantificabili, come i terremoti e altri eventi calamitosi, presentano particolari problemi di prevedibilità. Agli aspetti problematici derivanti dalla complessità di questi fenomeni si aggiunge il fatto che la nozione di probabilità e il ragionamento probabilistico sono in generale poco conosciuti nel nostro Paese, dove la mentalità più diffusa è tuttora in termini di aut aut. La nozione di probabilità non ha un significato univoco, e questo ha alimentato scuole di pensiero che ne danno diverse interpretazioni, che a loro volta stanno alla base di varie metodologie statistiche. I diversi modi di concepire la probabilità, così come i diversi metodi della statistica, presuppongono assunzioni, la cui applicabilità al problema oggetto di studio andrebbe sempre vagliata con grande attenzione. La bontà delle previsioni, e delle decisioni prese in base a queste, dipende tanto dalla completezza dell’informazione presa in considerazione, quanto da un responsabile uso delle metodologie adottate
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
Le sequenze sismiche: imprevedibilità e incertezza dell’evoluzione cronologica
No full textIl concetto di sequenza sismica è uno dei più abusati della Sismologia in quanto viene spesso utilizzato senza una chiara definizione del suo significato. In generale, i terremoti avvengono «in sequenza» temporale ma non sono distribuiti uniformemente e tendono invece a raggrupparsi nello spazio e nel tempo («clustering»). Questa è un’osservazione tra le più verificate della Sismologia e si può dare per certa senza ulteriori commenti. Il raggruppamento delle scosse vale per scale molto diverse, sia spaziali (da poche centinaia di metri a centinaia di km) che temporali (da pochi secondi a decine o centinaia di anni)
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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