1,720,996 research outputs found
On orbit validation of structural health monitoring by a low-cost technological mission
No full textAim of this work is demonstrate the on-orbit reliability of piezoelectric technologies for structural sensing purposes; a low cost mission is analysed using a picosatellite platform as CubeSat. CubeSat permits the development of a small mission with a reduced effort in terms of time, economic and human resources. The European launcher Vega is selected with CubeSat as secondary payload; the mission could be scheduled among the first Vega missions in order to set and better describe mechanical launcher environment into the fairing. During launch phase the vibration level is registered by piezoelectric sensors installed as primary payload on CubeSat. A plate with piezoelectric patches is used as a middle panel into the CubeSat structure; direct piezoelectric effect permits to convert the mechanical environment (vibration) into electric output as a voltage. Voltage output is sampled and converted in a digital output suitable for on-board memory and signal data capture is completed. During orbit phase CubeSat sends data to ground station for the vibration level recorded; proper sampling rate (during the launch) and data rate (downlink) assure the complete data transfer (between satellite and ground station) in a limited number of orbits. The sizing of satellite sub-systems and choice of hardware equipment are completed by an estimation of the cost
Numerical solution for a fluid-active structure interaction
No full textPurpose - To present a numerical method for the solution of the unsteady incompressible Navier-Stokes equations in a generic setting. Design/methodology/approach - The equations are discretized in space by the finite element method, and in time by a semi-implicit finite difference scheme, using a fractional-step method to enforce incompressibility. Findings - The presented results demonstrate the satisfactory accuracy of the method in the simulation of vortical flows in laminar regime and the stability of the solution in presence of a strong boundary layer. Originality/value - The successful integration of the CFD into the industrial design depends on its capability to produce accurate and reliable simulations of real life applications. These considerations drive the development of the proposed method: it can be used in conjunction with finite elements of any order of accuracy, providing accurate and numerically stable results for complex flows. Moreover, the computational requirements are low when compared with other similar strategies. © Emerald Group Publishing Limited
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
On the central role of the invariant <i>I</i><sub>2</sub> in nonlinear elasticity
No full textThe necessity of the inclusion of the second invariant of the left Cauchy-Green deformation tensor B, namely I2, in the strain energy function W of rubber-like materials is analysed. Universal relationships that underline such necessity are revisited, and experimental data are examined to establish the trends in the variation of ∂W/∂I2. Corroborated by the established experimental trends, we consider (meso)structural arguments to devise a plausible approach for incorporation of I2 into the W function. On the basis of the molecular theory of rubbers and considering the entanglements as a topological tube constraint, our analysis confers that a first approximation of W(I1,I2) is of the form W(I1,I2)=f(I1)+g(I2). The f(I1) contribution may be that of any classical generalised neo-Hookean model, and the functional form of g(I2) is directly deduced from the tube model of entangled molecules. An additional logarithmic functional form of I2 is also devised based on the rational approximation of the response function β−1. The ensuing additive-type W(I1,I2) models are then compared with experimental datasets. While this additive consideration may not be sufficient to account for all aspects of the mechanics of rubber-like materials, the fitting results demonstrate an eminent improvement in the predictions of the additive-type models compared with generalised neo-Hookean models having the same number of constitutive parameters. These analyses underline the central role of I2 in modelling the finite deformation of rubber-like materials
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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