1,721,004 research outputs found
Impact location in composite plates using proper orthogonal decomposition
No full textThe paper presents a novel algorithm for detecting the point of impact in composite plates. Instead of using an approach based on the calculation of the time of arrival of waves at the sensors’ location, the proper orthogonal decomposition of the dynamics of the system after impact is used; thanks to this procedure, there is no need to know the wave propagation velocity, which can be an uncertain quantity when anisotropic materials are involved. Results on a composite plate are compared to the ones obtained with an integral approach present in literature. The proposed approach provides smaller location errors over a wide range of impact positions. Finally a comparison between this novel approach and a classic triangulation method is proposed
Outdoor recreation in North eastern Alps: a two stages nested logit random utility model
No full text
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
Effects of the transfer function evaluation on the impact force reconstruction with application to composite panels
No full textThe determination of a reliable transfer function for force reconstruction of impacts on composite panels is addressed in the paper. The reconstruction of the impact force history requires the knowledge of the transfer function which relates the response to the contact force. In this paper, a new method to determine the transfer function of a composite plate, instrumented with surface bonded piezoelectric sensors, is proposed. Impact tests are carried out and the data are used to evaluate the transfer function. The force reconstruction results, obtained by using the new transfer function, are compared with the results obtained with the classic approach. Significant improvements are observed in predicting the force history, particularly when large deflections are present; these are quantifiable as an out of plane displacement of the same order of magnitude as the thickness of the plate. The influence of increasing the
impact velocity, with the related increase in the contact force, is also studied. The proposed method provides good results over a range of impact velocities. Multiple impacts were also investigated and the
method could correctly reconstruct force histories of consecutive impacts
Application of Laplacian operators on noisy data to compute curvature with Proper Orthogonal Decomposition
No full textDamage detection is a wide field of research and different approaches can be used to monitor structure integrity. Continuous monitoring of critical components is of vital importance to guarantee the safety of a structure. Variations in the dynamic response, in particular the curvature of mode shapes, are considered good indicators of the presence of possible defects. However noise, which often affects data, can lead to an erroneous calculation of the curvature, preventing the location of possible damage. The aim of this paper is to investigate the capability of the proper orthogonal decomposition (POD) to overcome noise, computing the curvature of proper orthogonal modes with a modified Laplacian operator. A numerical investigation on a cracked beam is compared to an analytical case present in literature. An extension of the mono-dimensional modified Laplacian scheme is introduced to study also plate-like structures. An experimental application on a vibrating composite plate will be presented in order to validate the numerical model
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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