1,720,959 research outputs found
Un metodo per l'identificazione in linea delle proprieta' dinamiche di edifici civili tramite eccitazione non misurata di tipo indiretto
No full textMechanical Identification and Model Validation for Shear-Type Frames
No full textIn the field of civil structural engineering great effort is being devoted to develop robust identification procedures for characterisation of dynamical behaviour, that concern characterisation of both modal and structural parameters. In this work, a procedure for identification of "shear- type" multi-storey frames in free vibrations is tested. "shear-type" models are very often used in civil engineering and are characterised to have just a few significant degrees of freedom (dofs, i.e. floor displacements). The procedure is composed by two consecutive steps: (1) identification of the experimental modal model from data acquisition in time domain; (2) updating of an a priori finite element model (FEM) of the structure by comparing identified modal quantities. A rational fractional polynomial technique is used to obtain the experimental modal behaviour of the structure and an eigensensitivity model updating technique to modify the structural parameters of an FEM. The whole procedure is applied to a laboratory three floor "shear-type" framed structure to provide an updated FEM. An experimental validation is performed using the updated model to predict the effect of structural modifications upon the modal behaviour variation both in the laboratory frame and in the FEM
Simulation and experimental validation of modal analysis for non-linear symmetric systems
No full textA dual approach, direct and inverse, is proposed for the study of a subset of discrete mechanical non-linear systems. Applying the definition of a "mode" for a non-linear system, the response calculation is refined for a class of mechanical systems possessing elastic restoring forces proportional to the cube of the displacement. The relationship between the modal natural frequencies and modal amplitudes of oscillation is analytically computed using the Harmonic Balance Method. An identification method, which operates on the free response of the system, is presented and it is shown to be capable of recovering these functional relationships. Comparisons of the analytical approximation and identification solutions are made in order to evaluate the method's effectiveness and its range of application. This comparison is achieved through numerical simulation.An experiment performed on a physical mechanical system exhibiting non-linear behaviour is then presented. For such a system, the analytical relationships between modal natural frequencies and modal amplitudes of oscillation are calculated using its mechanical parameters. These relationships are compared with those identified experimentally and finally the results and possible extensions to the work are discussed. <br/
Modal identification of multi-degrre-of-freedom mechanical systems endowed with geometric non linearities
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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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