1,720,954 research outputs found
New Capabilities of TOPICA Code: Lower Hybrid Antennas and Full Toroidal Plasmas
No full textTOPICA (TOrino Polytechnic Ion Cyclotron Antenna) code is a numerical suite aimed at the performance prediction and analysis of plasma-facing antennas. It is capable of handling real-life 3D antenna geometries (with housing, Faraday screen, etc.) as well as a realistic plasma model, including measured density and temperature profiles. Thanks to the approach underlying the code (i.e. the formal splitting of the problem into two parts: the vacuum region around the antenna and the plasma region inside the toroidal chamber), TOPICA can be extended to deal with lower hybrid (waveguide grill) antennas, as well as toroidal plasma. TOPICA has been upgraded to simulate and design lower hybrid (waveguide grill) antennas. On the other hand, to include plasma curvature effects, TOPICA can adopt the plasma impedance matrix computed independently via the fully toroidal TORIC plasma code. This way TOPICA both provides more accurate antenna parameters and yields the proper input (i.e. the electric field in front of the Faraday shield) to self-consistently run TORIC in a subsequent plasma analysis. In this work an account for the new capabilities of TOPICA will be presente
A simulation approach for ICRF plasma thruster antennas
No full textIn the past twenty years plasma‐based propulsion systems have found increasing aerospace interest; although they were initially conceived as rockets for interplanetary missions, more recent advances in plasma‐based concepts have led to the identification of radio‐frequency (RF) generation and acceleration systems as capable of providing not only continuous thrust, but also controllable exhaust velocities, as required in maneuvering applications. The most interesting such studies for plasma propulsion are those focused on the possibility of coupling radio frequency power to plasma, exploiting the possibility of having very efficient devices to generate and heat the plasma, magnetically confining it in a trap in the heating region, so that ion can escape the magnetic trap only when they are energetic enough to be converted into direct out‐going flow which provides the thrust. The structure of this system is therefore based on of three stages where plasma is respectively generated, heated and expanded in a magnetic nozzle. The heating stage acts as an amplifier; here plasma is heated by the radio frequency waves by the process of ion cyclotron resonance. It has been developed and tested a numerical tool for the electromagnetic modeling of the ICRF antenna, of the RF booster unit of plasma thrusters, and of the RF‐plasma interactions. The latter is studied in the critical ICRF acceleration region by setting up a convenient Electromagnetic (EM) analytical and numerical model based on the Moment‐Method solution of a suitable set of integral equations. Solution of the relevant integral equation directly provides the electric surface current density induced on antenna conductors, but the ultimate quantity to be computed is the circuit characterization (e.g. admittance matrix) at the input ports
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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