1,721,094 research outputs found
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
Quantum effects on Lagrangian points and displaced periodic orbits in the Earth-Moon system
No full textRecent work in the literature has shown that the one-loop long distance quantum corrections to the
Newtonian potential imply tiny but observable effects in the restricted three-body problem of celestial
mechanics; i.e., at the Lagrangian libration points of stable equilibrium, the planetoid is not exactly at an
equal distance from the two bodies of large mass, but the Newtonian values of its coordinates are changed
by a few millimeters in the Earth-Moon system. First, we assess such a theoretical calculation by exploiting
the full theory of the quintic equation, i.e., its reduction to Bring-Jerrard form and the resulting expression
of roots in terms of generalized hypergeometric functions. By performing the numerical analysis of the
exact formulas for the roots, we confirm and slightly improve the theoretical evaluation of quantum
corrected coordinates of Lagrangian libration points of stable equilibrium. Second, we prove in detail that
for collinear Lagrangian points the quantum corrections are also of the same order of magnitude in the
Earth-Moon system. Third, we discuss the prospects of measuring, with the help of laser ranging, the above
departure from the equilateral triangle picture, which is a challenging task. On the other hand, a modern
version of the planetoid is the solar sail, and much progress has been made, in recent years, on the displaced
periodic orbits of solar sails at all libration points, both stable and unstable. Therefore, the present paper
investigates, eventually, a restricted three-body problem involving Earth, the Moon, and a solar sail.
By taking into account the one-loop quantum corrections to the Newtonian potential, displaced periodic
orbits of the solar sail at libration points are again found to exist
Analysis and Performance Evaluation of ZEM/ZEV Guidance and Its Sliding Robustification for Autonomous Rendezvous in Relative Motion
No full textDevising closed-loop guidance algorithms for autonomous relative motion is an important problem within the field of orbital dynamics. However, very few closed-loop algorithms have been devised that can autonomously generate feedback trajectories to execute rendezvous in relative motion (e.g. Lopez and McInnes, 1995, JGCD). In this paper, we explore the application of the generalized Zero-Effort-Miss/Zero-Effort-Velocity (ZEM/ZEV) feedback guidance (Guo et al., 2013, JGCD) and its robustified version known as Optimal Sliding Guidance (OSG, Wibben and Furfaro, 2016, ASR) to the problem of closed-loop spacecraft rendezvous guidance. The ZEM/ZEV feedback guidance has been studied extensively and can be found in the literature for intercept, rendezvous, terminal guidance and landing applications. Such analytical closed-loop guidance has been originally conceived by Battin who devised an energy optimal, feedback acceleration command for powered planetary descent. Ebrahimi et al. (2008, AA) introduced the ZEV concept, as a partner for the well-known ZEM and integrated it with a sliding surface for missile guidance with fixed-time propulsive maneuvers. Furfaro et al. (2011, Advances in Astronautical Sciences) extended the idea to the problem of lunar landing guidance and set the basis for the theoretical development of a robust closed-loop algorithm for precision landing. ZEM/ZEM feedback guidance is attractive because of its analytical simplicity as well as potential for quasi-optimal fuel performance. When robustified by a time-dependent sliding term, the resulting OSG can be proven to be Globally Finite-Time Stable (GFTS) in spite of perturbation with known upper bound. Here, we study the guided relative motion of two spacecraft for which one of them is executing an autonomous rendezvous via the ZEM/ZEV feedback guidance and its robustifed OSG counterpart. When augmented via time-dependent sliding, the application of Lyapunov stability theory for non-autonomous systems provides the sufficient conditions for GFTS. Indeed, the OSG can be demonstrated to be GFTS for any linear and non-linear relative motion model (e.g. rendezvous in circular orbit or in highly eccentric orbit). Starting from the classical Clohessy-Wiltshire (CW) model, we systematically analyze the ability of the ZEM/ZEV feedback guidance to execute quasi-optimal closed-loop maneuvers and its ability to correct disturbances for precision guidance. Comparison with the OSG counterpart will provide an assessment of the need for robustification as function of different rendezvous conditions (e.g. rendezvous in highly elliptical orbit) and different thrusting constraints (e.g. limited thrust)
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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