1,721,100 research outputs found
Electro-Magnetic Launchers on the Moon : A Feasibility Study
No full textThe purpose of this effort is to study and perform preliminary design and simulations of an Electro-Magnetic Launcher (EML), aka mass driver (MD), for both sub-orbital and orbital launch applications. EML studies have been carried out among the railguns, which are the most explored and suffer from excessive component deterioration, and coilguns, more futuristic, which eliminate this defect through magnetic Ievitation and which are addressed in this work. While Earth applications are deterred by excessive temperatures achieved by the payload, due to friction in the atmospheric ascent as well as to the considerable deceleration, when launching from the Moon the conditions for EMLs become more favorable. They are also environment-friendly compared to conventional chemical propulsion, which creates wastes that are more toxic. In addition, MDs allow an optimal and continuous control of acceleration and have fewer constraints, compared to existing launch vehicles, regarding the payload size. A scenario examined is a notional mission in which the MD is placed inside a lunar crater. The study analyses mainly the thermal, electrical, structural, and environmental aspects, and provides an estimate of the energy needs, which have to be provided by a solar infrastructure on the crater rim, where there is almost permanent solar illumination. Not only the MD could be used to launch from the Moon to various destinations, including local depot stations at the Earth-Moon Lagrangian Point 2 (EML2) of mined materials, but it might also be convenient to move payloads between two points on the surface. The preliminary results of the study indicate that EMLs are a promising technology for future Moon missions and encourage further investigations
Analysis of Alternative Energy Harvesting Methods to Power Atmospheric Robotic Explorers on Jupiter
No full text
ESPACENET: A Framework of Evolvable and Reconfigurable Sensor Networks for Aerospace-Based Monitoring and Diagnostics
No full textThere is an increasing need to develop flexible, reconfigurable, and intelligent multi-spacecraft sensing networks for aerospace-based monitoring and diagnostics. Technical advancements in ad hoe networking, MEMS devices, low-power electronics, adaptive and reconfigurable hardware, microspacecraft, and micro-sensors have enabled the design and development of such highly integrated space wireless sensor networks.
This paper proposes the framework for an Evolvable Sensor Network Architecture, investigated as part of the ESPACENET project, collocated at the University of Edinburgh, Essex, Kent and Surrey. The aim is to design a flexible and intelligent embedded network of reconfigurable piconodes optimised by a hierarchical multi-objective algorithm. Although the project is targeted at aerospace applications, the same intelligent network can be used for many earth bound applications such as environmental and medical diagnostics
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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