1,720,955 research outputs found
Node-Dependent Kinematics and Multidimensional Finite Elements for the Analysis of Single/Double Swept, Composite Helicopter Blades
No full textThis paper deals with finite element analysis of helicopter blades with single and double swept geometries made by metallic and composite materials. First, classical and refined beam theories are combined at the element level via a nodedependent kinematic (NDK) concept, which was recently introduced by the authors. Such an NDK approach enables the accuracy/efficiency ratio of the solution to be tuned according to the level of fidelity required by the design phase. Second, one-dimensional NDK models are combined with the possibility to introduce solid elements in those regions of the blade with a sharp variation of the geometries. The numerical examples consider a swept-tip rectangular beam and a double-swept helicopter blade with a realistic airfoil. Natural frequencies and through-the-layer stress distributions are reported to demonstrate the flexibility and computational efficiency of the proposed methodology
Assessment of classical, advanced, and layer-wise theories for the vibration of rotating composite anisotropic blades
Get PDFThe present paper aims at studying composite cambered structures, tracking the seminar work “Rotating Blade Vibration Analysis Using Shells” presented by Leissa in Journal of Engineering for Power, in 1982, devoted to homogeneous metallic blades. A refined unidimensional (1D) formulation is here implemented to overcome the limitations of classical beam theories. With an appropriate choice of cross-sectional expansions, it is possible to make the 1D model suitable for analyzing shallow blades. This approach enables one to generate both layerwise (LW) and equivalent single layer (ESL) descriptions of the problem unknowns. Furthermore, it is possible to implement classic theories as special cases. Natural frequencies are determined for isotropic and composite blades, showing the effects of changing the fiber lamination angle of symmetric and unsymmetric configurations. Besides, this study investigates the effects of thickness and rotational speed over the structure. Significant differences between classic and high-order theories are found, concerning the accuracy and the computational costs. The causes of these differences are discussed, and the results can be used as a benchmark for future studies
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
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
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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