1,721,054 research outputs found
The Method of the Pseudo Equivalent Deterministic Excitations (PEDE_M) to Bound the Random Response
No full textThe analysis of the response of a stochastic system, through a discrete coordinate set, can become computationally challenging, even when using a full modal representation. Nevertheless, many dynamic load cases, in engineering
applications, have stochastic behaviour as the wall pressure fluctuations due to the
turbulent boundary layer. In this work, a new method is proposed: it is named as
frequency Modulated Pseudo Equivalent Deterministic Excitation, PEDEM, and it is
based on the Pseudo Excitation Method, PEM. This latter can be considered as an
exact representation since it uses a modal decomposition of the cross-spectral
density matrix of the excitation; the extraction of the eigensolutions of the load
matrix, at each frequency step, is a computational disadvantage. PEDEM overcomes
this issue by introducing some approximations based on the analysis of the
eigensolutions of the dynamic load matrix versus frequency. Mainly, two different
approximations are proposed with reference to extreme frequency ranges (low and
high) wherein the dynamic matrix of a random and convective load has different
characteristics. A criterion to identify these frequency ranges is proposed versus a
dimensionless representation of the frequency. Moreover, it is shown that the
proposed approximations represent the bounding curves of the response for the
whole frequency range. Fruitful comparisons with a full stochastic approach is
discussed. The proposed approximations combine a good accuracy and representation of the stochastic system together with a significant reduction of the computational
costs if compared to a full stochastic response or a PEM solution. The
method is applied over two simple configurations (a chain of oscillators and two
flexural plates) but the possible extensions to more complex cases are motivated by
the quality of these preliminary results
Dimensionless Representations of the Interaction Between Turbulent Boundary Layer and Elastic Plates
No full textThe study of the interaction between elastic structures and turbulent
boundary layer still presents some uncertainties. This is true even assuming a oneway
coupling and stationary turbulent boundary layer (TBL) over smooth and flat
plates in subsonic flow. The reasons are mainly related to (i) the limitation for the
direct numerical simulations of Reynolds number value of the Navier-Stokes
equations, (ii) the high frequency structural and acoustic numerical and modelling
difficulties and (iii) the lack of experimental data representative of all frequencywavenumber
pressure fluctuation regions, needed for the direct validation of the
semi-empirical pressure models. In fact, when the pressure convective terms are the
dominant sources of vibrations and radiated noise, consolidated and almost case
independent formulations exist; on the contrary, when the subconvective terms are
of concern, the definition of models seems to be strongly dependent on the flow
conditions and the characteristics of the fluid-structure interaction. In order to find a
general procedure for the estimation of the response of elastic thin panels to TBL
excitation, some scaling laws derived using dimensional analysis and energetic
considerations are proposed. These dimensionless relations contain a combination
of both flow and structural parameters yielding to simple analytical expressions
relating a dimensionless structural response metric and a dimensionless frequency.
The found scaling expressions are validated with wall pressure fluctuations and
vibrational response data acquired in wind tunnels and towing tank for the case of
thin flat plates made of homogeneous isotropic and composite materials
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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