1,721,045 research outputs found
Identification of a Root ``Smart Spring'' System for Augmentation of Aeroelastic Stability of a Helicopter Rotor in Hover
No full textClosed-loop control of the smart spring. An analytical solution for the actuator model
No full textThe analytical modeling of the Smart Spring actuator for vibration reduction of periodically excited systems is performed. The mathematical model is developed in the frequency domain using the harmonic balance method, assuming that the solution is harmonic on the exciting frequency. Both the fixed-base and base-excited configurations are studied. It is shown that the Smart Spring transmissibility at the target frequency depends on only three dimensionless parameters associated with the stiffness modulation characteristics of the device for the fixed-base configuration and five dimensionless parameters for the base-excited configuration. The fundamental values for the Smart Spring closed-loop control are discussed
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
Experimental Investigation on the Modal Signature of the Smart Spring/Helicopter Blade System of SHARCS Project
No full textTo achieve efficient attenuation of noise and vibration characteristics within the helicopter environment, solid state actuators are seen as one of the most promising smart technologies. The Smart Hybrid Active Rotor Control System project is expected to demonstrate the ability of smart structure systems, employing multiple active material actuators, sensors, and closed-loop controllers, to reduce simultaneously rotorcraft vibration and noise. Within this project, piezoceramic elements were used as actuators to vary the dry friction and the stiffness of the whole helicopter blade system. This active control concept, named Smart Spring, originated a prototype used to demonstrate the ability to attenuate vibrations. Before testing the Smart Hybrid Active Rotor Control System in operative conditions, the dynamic properties of the Smart Spring installed on a nonrotating helicopter blade are investigated. The effects of the Smart Spring actuator on the modal properties are studied through experimental activities carried out at Carleton University. Furthermore, the capability of the Smart Spring to change the dynamic behavior of the helicopter blade is demonstrated by analyzing the shifts in the modal parameters. Finally, a beam finite element model of the blade, with stiffness and mass properties tuned to the experimental structure, is presented
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
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