1,720,992 research outputs found
System identification of a reduced scale model blade with an adaptive pitch link using whirl tower test data
No full textIn this paper the identification of the dynamic properties of a rotating helicopter blade has been performed using data recorded during whirl tower tests. A new methodology has been developed in order to extend the applicability of the operational modal analysis to systems characterized by harmonic component excitations blended with white noise spectra loading. The proposed approach is able to identify the harmonic components and then to remove their effects on the time responses of the system. The capabilities of the such method to track the changes in the natural frequencies, damping ratios and mode shapes of the rotating helicopter blade will be investigated in order to asses the overall efficiency. Furthermore, the experimental findings will be compared to those numerically achieved using an aeroelastic numerical procedure developed to deal with the dynamics of rotating blades. Finally, the effects of changes of the stiffness of the pitch link, located at the root of the rotating blade, on the modal parameters will be investigated. © 2012 AIAA
Whirl-tower open-loop experiments and simulations with an adaptive pitch link device for helicopter rotor vibration
No full textIn the present work are presented both experimental and numerical simulation results obtained with an open-loop control law applied to an individual blade control system that incorporates a mechanism for blade active impedance adaptation at the root, the active pitch link or "smart spring". It is demonstrated that the active pitch link provides parametric excitation of the blade in the rotating frame and, with it, alters the vibration spectra of the vibration loads both in the blade structure and transmitted to the nonrotating frame by the hub. The experimental results were obtained in whirl tower tests where blade periodic excitation was provided by a fan located at the base of the rotor and generated a transversal flow at a range of blade azimuth angles. © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved
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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