1,720,957 research outputs found
Sporcarsi le mani.
Full text linkQuesto lavoro prende in considerazione tanti argomenti, variamente articolati, con lo intento di farne una carrellata di esempi. In questo modo, ampio spazio è lasciato allo impegno (fino a sporcarsi le mani, con una ardita proposta politica) ed alla fantasia (con due diversi esempi di una didattica universitaria), senza poter dare e/o applicare ricette preconfezionate. Rientrando ancora nel proprio mondo universitario, gli autori presentano un lungo esempio geometrico su cosa significhi studiare e collaborare, anche per una vera internazionalizzazione, contro la logica, ora imperante, di soddisfare acriticamente indici prestabiliti
3D object modelling and reconstruction of topologies and boundaries
No full textLa gestione e la strutturazione del dato sono operazioni notevolmente più complesse quando si considerano dati definiti nello spazio 3D piuttosto che nello spazio 2D. Ciò è dovuto al fatto che le relazioni topologiche e geometriche in uno spazio 3D sono molto diverse tra loro e in numero maggiore. In molti casi la modellazione 3D richiede la definizione di modelli concettuali che implicano la conoscenza delle topologie 3D.
La modellazione ad oggetti permette di rappresentare una vasta gamma di corpi e forme, ed è uno strumento innovativo e tecnologicamente avanzato per lo studio di fenomeni tempo – spazio variabili. Purtroppo questo strumento non è molto diffuso in quanto rende la gestione e la creazione di un sistema informativo estremamente difficile.
Ogni oggetto può essere descritto come un’entità concettuale e può essere facilmente definito sulla base dei dati e del contesto ad esso connessi. In effetti ogni oggetto appartiene ad una classe che ne definisce la tipologia, ed è composto da punti, linee, superfici e corpi 3D.
La struttura dati vettoriale in uno spazio 3D può essere realizzata a partire da un’approssimazione lineare utilizzando poliedri, poligoni, segmenti e punti. Dopodiché il “dato” viene elaborato in una struttura dati relazionale 3D utilizzando la teoria dei grafi. I punti e i segmenti sono nodi e archi di un grafo primario, mentre usando il concetto di dualità i poliedri diventano nodi duali e i poligoni archi duali. Una matrice di cross connessione permette di collegare i due grafi (il grafo primario e il grafo duale) che altrimenti sarebbero disgiunti. Questa contiene le m – n relazioni tra segmenti e poligoni, e dà luogo a due tipi di informazione: i segmenti che delimitano un poligono e i poligoni che hanno un segmento in comune.
Infine, se analizziamo le relazioni topologiche e quelle geometriche, queste sembrano avere la stessa cardinalità dei gruppi di simmetria. Sfruttando questo concetto è possibile semplificare la descrizione e l’analisi di molti oggetti caratterizzati da particolari caratteristiche morfologiche andando a selezionare solo i pochi casi ammissibili (di relazioni topologiche tra gli elementi di un oggetto e tra gli oggetti stessi) senza cercare tra tutte le possibili combinazioni.
Il sistema attuato ed implementato secondo le osservazioni di cui sopra è stato testato dapprima con un esempio creato appositamente e successivamente con due casi reali. Lo studio condotto e i risultati ottenuti non hanno evidenziato particolari problematiche rispetto alle ipotesi fatte nel corso della ricerca.Working in a 3D context is more complex than working in a 2D one; this is due to the fact that 3D topological and geometric relations are far more complicated. Many cases of 3D modelling require the definition of conceptual models, which implies a knowledge of 3D topologies. Object – oriented modelling allows to represent a wide range of bodies and shapes. Moreover, it is a useful basis for further research and analysis, as well as an innovative and technologically advanced instrument for studying spatial phenomena and their temporal dynamics. Unfortunately, this instrument is not yet widely used, as it makes informative systems’ creation and management an extremely difficult operation. Every object can be described as a conceptual entity and can be easily defined on the basis of the data and context related to it. Indeed, every object belongs to a class, which defines its type and is composed by points, lines, surfaces and 3D bodies. Thus, spatially referenced objects are identified and described by means of geometric and thematic features. The structure of vector data in a 3D space can be represented through linear approximation using polyhedrons, polygons, segments and points. The representation of 3D vector data structure, which uses the graph theory, is based on the concept of nodes and arcs as directly applied to points and segments; the concept of duality allows to link polyhedrons with dual nodes and polygons with dual arcs. A cross connect matrix allows to connect the two graphs (primary graph and dual graph) which would otherwise be disjointed. It shows the m – n relations existing between segments and polygons and provides two sets of information: the group of segments which delimit a polygon and the group of polygons which have a segment in common. Finally, if looking at topological and geometric relations, their cardinality appears to be the same as that of symmetry groups; this fact leads to highlight a curious analogy. Moreover, it allows to simplify the description and analysis of many objects and features, by selecting a posteriori only a few admissible cases without searching for all the possible combinations. The system, implemented according to the above mentioned remarks, has been tested using a simulation example and two case studies. The whole operation has highlighted no particular problems with regards to the hypotheses presented throughout the research.DIPARTIMENTO DI INGEGNERIA CIVILE E AMBIENTALE25MUSSIO, LUIGIGUADAGNINI, ALBERT
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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