1,720,992 research outputs found
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
Discrete and finite element models for periodic brickwork: a comparative analysis
No full textThe use of refined models for investigating the in-plane behaviour of periodic brickwork
is an active field of research; here a comparison between a Discrete Element Method (DEM)
and a Finite Element/Discrete Element Method (FEM/DEM) is performed
Continuous and discrete models for masonry like material: A critical comparative study
No full textThe aim of this paper is to present a critical comparative review of different models that may be adopted for modelling the mechanical behaviour of masonry, with particular attention to microstructured models.
Several continuous and discrete models are discussed. Such models are based on the following assumptions: i) the structure is composed of rigid blocks; ii) the mortar is modelled as an elastic material or an elastic interface. The rigid block hypothesis is particularly suitable for historical masonry, in which stone blocks may be assumed as rigid bodies. For this type of masonry, mortar thickness is negligible if compared with block size, hence it can be modelled as an interface.
Masonry-like materials may be modelled taking into account their heterogeneity by adopting a heterogeneous Finite Element Model (FEM) or a Discrete Element Model (DEM). The former seems to be more representative of masonry, but it is computationally onerous and results interpretation may be difficult; the latter is limited to rigid block assumption and mortar joints modelled as interfaces. For this reason, continuous equivalent models may be suitable to investigate masonry behaviour. Continuum equivalent models provide, in an analytical form, constitutive functions, but Cauchy model may be not suitable to describe masonry behaviour due to not negligible size of heterogeneity (block size) with respect to masonry panel size. For this reason, micropolar equivalent continuum may be adopted.
By reference to the existing literature, a simple and effective DEM is adopted, in which masonry is modelled as a ‘skeleton’ having a behaviour depending on forces and moments transferred between blocks through the interfaces (mortar joints). Moreover for the micropolar equivalent continuum, an ad hoc enriched homogenised FEM is formulated by means of triangular elements. The proposed numerical models represent two possible simple approaches for solving heterogeneous problems. Such models are developed both by means of fast numerical routines and do not require specific computer codes, whereas the heterogeneous FEM may be studied by adopting a traditional FE code.
DEM and heterogeneous FEM are adopted to verify reliability and application field of Cauchy and micropolar continua. Moreover, sensitivity of micropolar model to the Representative Elementary Volume (REV) chosen is discussed. For these purposes, ad hoc FE models are adopted, with constitutive functions obtained from an identification procedure (both for Cauchy and micropolar continua). An extensive comparison between DEM, heterogeneous FEM and equivalent homogenous FEM is presented in some meaningful cases, taking into account also the effect of heterogeneity size on models behaviour
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
Comparative analysis of numerical discrete and finite element models: the case of in-plane loaded periodic brickwork
No full textThe use of refined models for investigating the in-plane behavior of periodic brickwork is an active field of research. A key aspect in modeling periodic brickwork is the identification of an appropriate scale of analysis suited for the effective characterization of the mechanical properties of structure. With this purpose, different models will be defined to simulate, with an appropriate accuracy, the behavior of masonry. Here, a comparison between a Discrete Element Method (DEM) and a combined Finite Element and Discrete Element Method (FEM/DEM) is performed. DEM and FEM models start from different assumptions and envisage different fields of application. The synergic development of the comparative analysis of two numerical models together with a reliable analysis allows developing a specific strategy suitable for investigating historical masonries (periodic brickwork) with a twofold aim: to calibrate the models at the beginning in a linear elastic field such as to propose a perspective dynamic analysis and to carry out a nonlinear analysis
DEM & FEM/DEM models for laterally loaded masonry walls
Full text linkThe wide amount of historic masonry constructions in Italy and other European countries makes of paramount importance the development of reliable tools for the evaluation of their structural safety. Masonry is a heterogeneous structural material obtained by composition of blocks connected by dry or mortar joints. The use of refined models for investigating the in-plane nonlinear behavior of periodic brickwork is an active field of research. The mechanical properties of joints are usually considerably lower than those of blocks, therefore it can be assumed that damages occur more frequently along joints. Thus, a key aspect is represented by the evaluation of the effective behavior of joints and its reliable description into numerical models. With this purpose, in this contribution, different models are defined to simulate, with an appropriate accuracy, the behavior of masonry: Discrete Element Model (DEM) and a combined Finite Element and Discrete Element Model (FEM/DEM). Models are based on rigid block hypothesis and joints modeled as Mohr-Coulomb interfaces. These assumptions may be suitable for historical masonry, in which block stiffness is larger than joint stiffness, allowing to assume blocks as rigid bodies, moreover joint thickness is negligible if compared with block size. Analysis is performed in the nonlinear field to investigate the behavior of masonry walls subject to lateral loads, in order to simulate their seismic response, with particular attention to the determination of limit load multipliers
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