1,721,032 research outputs found
A general formulation of the potential energy release rate for a three-dimensional hyperelastic body containing a plane crack
No full textIn this paper a general expression of the potential energy release rate G for a three-dimensional fracture mechanics problem is supplied. Under the hypothesis of a quasi-static growth phenomenon, the distribution of the vector a, i.e. the velocity field of the fracture propagation, is assumed unknown along the crack front. This assumption leads to a general formula of G for a three-dimensional hyperelastic body containing a plane crack. Moreover, imposing a stationary condition of G with respect to a, the analytical problem of the crack front shape evaluation is formulated. A unique solution exists for the problem, which is described by a system of two non-linear equations. Practical applications of the theory can be obtained by the use of finite element analysis results, together with a numerical solution of the two equations in the unknown components of the fracture propagation velocity
The role of pressure field dynamics on the onset of transonic aeroelastic instabilities of high aspect ratio swept wings
Full text linkThe dynamic aeroelastic responses in the transonic regime for a conventional swept wing and a curved-planform wing, both having a high aspect ratio, are analysed in detail. Using 2-way fluid structure interaction (FSI) analysis, the power spectral density of both wing-tip displacements and wing aerodynamic coefficients are analysed to highlight instabilities. Furthermore, a study of the interaction between the structural dynamics and the dynamics of the pressure field is performed. To do this, transient computational fluid dynamics (CFD) analyses, performed on rigid wings with updated geometry, provided the frequency spectra of the pressure fields. For the conventional swept wing, a clear interaction between a structural bending mode and pressure field oscillations generates a flutter-buffet instability. Conversely, for the curved-planform wing, this work demonstrated that the transonic pressure field oscillations, although not negligible, are not a direct cause of the onset of the bending-torsion flutter of the wing
Formulation and Experimental design of Reusable launchers through Multiple Investigations (FERMI) : preliminary study of single stage to orbit concept
No full textIn this paper, recent trends in design and concept of fully reusable single stage to Orbit Launch vehicle is being studied. As step forwards to developing a generalised formulation with identified limits for launch vehicles especially for small payload class to LEO. The state of the art is based on DLR’s RETALT 2 concept, by using historical formulation detailed mass budget is obtained for the same. Trajectory design, loading conditions have been re-simulated with changes towards obtaining measurable improvements in overall performance of the vehicle. Shortcomings during the preliminary design process is identified from a structural design point of view
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
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