1,720,956 research outputs found
Novel Modeling and Vibration Analysis Method on a Helicopter Drive Train System
Full text linkWhen it comes to analyzing the dynamic characteristics of a geared system, it is common practice to create an equivalent mathematical model for which the rotational velocity is the same for all the elements. In contrast to creating the equivalent system firstly, a novel strategy based on the transfer matrix method is developed, which can directly obtain the equation of motion according to the system topology figure. Actually, any kind of topology of the system, e.g., geared branch or geared closed-loop systems, can be decoupled into a combination of a series of independent chain systems via introducing the virtual branched-gear transfer matrix. The overall transfer equation of the system can be efficiently obtained because the transfer matrix method of a chain system is simply matrix multiplication. The transfer matrices of typical gear types, e.g., reduction gear and planetary gear, are derived. In particular, a simple and aesthetic transfer matrix of rotating beam is derived to solve the rotor blade flapping or lead-lag vibration problems. A dimension reduction strategy is also introduced to address the dimension unmatched issue, further reducing the scale of the overall transfer matrix of the system. At last, an application on modeling an analysis of the coupled flexible rotor blade/engine/tail rotor/drive train system of a helicopter is presented
Optimal Control of Pretwisted Rotating Thin-Walled Beams via Piezoelectrically Induced Couplings
Full text linkProblems related to mathematical modeling and optimal active control of pretwisted adaptive blade are considered. The blade is modeled as a rotating thin-walled composite beam embedded with anisotropic piezo-composite layers accounting for nonclassical effects, such as transverse shear and warping inhibitions. The linear-quadratic-regulator feedback control strategy is adopted to study the tailoring of piezo-actuators on vibration suppression. Control authority of piezoelectrically induced transverse shear and bending coupling is highlighted. Tailoring studies using the present model reveal that piezoelectrically induced transverse shear plays an important role on control effectiveness. In addition, the relations between the control authority and the elastic couplings, piezoelectrically induced actuation couplings, pretwist angle, and size and position of piezo-actuators are investigated
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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