1,721,033 research outputs found
A convergent and efficient decomposition method for the traffic assignment problem
No full textIn this work we consider the network equilibrium problem formulated as convex minimization problem whose variables are the path flows. In order to take into account the difficulties related to the large dimension of real network problems we adopt a decomposition-based approach suitably combined with a column generation strategy. We present an inexact block-coordinate descent method and we prove the global convergence of the algorithm. The results of computational experiments performed on medium-large dimensional problems show that the proposed algorithm is at least competitive with state of the art algorithms
On the convergence of inexact block coordinate descent methods for constrained optimization
No full textWe consider the problem of minimizing a smooth function over a feasible set defined as the Cartesian product of convex compact sets. We assume that the dimension of each factor set is huge, so we are interested in studying inexact block coordinate descent methods (possibly combined with column generation strategies). We define a general decomposition framework where different line search based methods can be embedded, and we state global convergence results. Specific decomposition methods based on gradient projection and Frank-Wolfe algorithms are derived from the proposed framework. The numerical results of computational experiments performed on network assignment problems are reported. © 2013 Elsevier B.V. All rights reserved
Recupero e consolidamento della collezione scheletrica del Museo di Zoologia “Doderlein”
Get PDFIl presente articolo illustra un’operazione di restauro che ha aperto una fase di recupero di diversi elementi scheletrici, da tempo deteriorati, nel Museo di Zoologia “Doderlein”, oggi afferente al Sistema Museale d’Ateneo - SIMUA - dell’Università degli Studi di Palermo. Il lavoro si è articolato in pulitura, restauro e consolidamento di cinquanta pezzi dei cinque gruppi di vertebrati. Questo intervento rappresenta solamente una piccola tessera di un progetto più ampio, che ha come obiettivo finale il recupero dell’intera collezione zoologica presente in Museo.The present work took place in the Museum of Zoology “Doderlein” of the SIMUA, University of Palermo. A restoration of skeletons was performed following the main phases: cleaning, restoration and consolidation of fifty pieces of the main five vertebrate taxa. This action represents the beginning of a wider project, of which the final aim is to recover the entire zoological collection present in the Museum
New model system for the screening and characterization of polyphenolic molecules provided with antioxidant and chemopreventive activity. From raw extracts to molecules
No full textANALISI METRICA E MORFOMETRICA DI UN CAMPIONE DI CRANI DELLE CATACOMBE DEI CAPPUCCINI DI PALERMO
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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