1,720,981 research outputs found
Green in-Space Transportation with Tether Technology
No full textRevitalized by recently concerns related to space debris and pollution, scientific research in the field of in-
space transportation is continuously evolving. Space tethers hold the potential to address traditional propellant consumption limitations and to reduce the ecological footprint of space exploration, providing adaptable and efficient solutions for debris removal, reboost and station-keeping operations. Notwithstanding space tethers have enjoyed a longstanding status as a promising propellant-free technology, the central challenge lies in their transition from experimental and scientific apparatuses to dependable, resilient, and efficient spaceborne assets to usher in a new era of space activity in low Earth orbits wherein tethers play a central role in recurrent missions.
Ongoing research, development, and thorough testing are imperative to address the challenge by unraveling the technical intricacies in both space tether design and system operation. This work focuses on establishing a deeper understanding of the critical processes and technologies and includes analyses on different tether configurations, spanning from momentum exchange tethers for satellite deorbiting to electrodynamic tethers for both orbit lowering and orbit raising. By addressing into topics such as tether mechanical properties, deployment dynamics, hardware design and control strategies, the multifaceted research effort proposes to optimize the performances and reliability of space tether systems, with the overarching goal of overcoming limitations inherent in existing propulsion strategies and technologies, advancing tether technology toward operational readiness and opening avenues for green in-space transportation with tether technology
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
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