1,721,259 research outputs found
A fast code using nonmagnetic measurements for RFX current and magnetic field profile reconstruction
No full textFast identification techniques of the plasma internal magnetic structure are needed for the real time control of the plasma current distribution in magnetic confinement devices. In this paper, a fast identification code using plasma internal nonmagnetic measurements is proposed and applied to the reversed field pinch experiment. The identification tool is based on a force-free ideal magnetohydrodynamic equilibrium model, using a parametric radial profile for the magnetic field and current density. A set of constraints on the internal magnetic distribution are derived from the Faraday rotation data given by a five-chord polarimeter, assuming the plasma density as given by an interferometric diagnostic. The code execution time is about a few second
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
Integration of magnetic and nonmagnetic measurements for current profile reconstruction in RFX
No full textA crucial issue in magnetically confined plasmas characterized by relevant internal current
redistribution, such as high beta and low field toroidal devices, is the determination of their internal
magnetic structure. The article presents a method for the integration of magnetic and nonmagnetic
measurements in a model which considers a plasma described by stationary ideal
magnetohydrodynamic equilibrium equations, with toroidal and poloidal plasma currents
represented by distributed discrete filaments and current sheets. The model also includes the massive
conductors representing the vessel, the shell, and the machine windings. The discrete current sets are
determined by using as input data the total currents flowing in the plasma, in the windings and in
the vessel, as deduced by external integral magnetic measurements. The obtained filamentary
current sets are then adjusted by imposing further constraints. One of the constraints is given by the
set of local magnetic field measurements provided by external pickup coils. A further and more
significant constraint is imposed by far infrared polarimeter, which gives an integral condition for
each implemented measurement chord. The method is validated by using experimental data from the
reversed field pinch Reversed Field eXperiment, and the results suggest that the current density
distribution is rather different from that usually predicted by conventional data inversion algorithms
Concepts, Design, and Development of a Multiplatform Framework for Real-Time Control in Nuclear Fusion
No full textThe paper discusses the requirements and presents an architectural overview of a new general-purpose framework for real-time control,
currently under development at the RFX laboratory. This represents the third generation of control framework developed at RFX. It takes into
account the experience gained in the development of the previous frameworks and exploits the evolution of computer technology, in particular,
the evolution of Linux towards real-time functionality and the availability of multicore CPUs in most general-purpose computing boards. The
framework will supervise data flow among the participating components, which may produce data, consume data, or apply some sort of
computation. Some system components have been already developed, while the architecture of others is still being refined. In particular, we are
going to integrate the infrastructure layer of the new framework with a real-time framework recently in use at JET. The aim of this collaboration
is a general purpose real-time system which can be used on both experiments
Workflow for the Assessment of ITER Plasma Control System Design
No full textThe plasma control system (PCS) for the first nonactive ITER operation phase will require simultaneous active monitoring and control of many continuous and discrete quantities. Considering the unique challenges ITER will face, all the controllers will be integrated and deployed with very little experimental time dedicated to PCS tuning and development. In order to maximize the efficiency of the ITER PCS design, a formal system engineering approach has been adopted. In a simplified way, the design process starts with the definition of the requirements. Functionalities are then designed and developed in order to meet these requirements. As a last step in the design process, it is important to assess that all the designed functionalities meet the associated requirements and that all the requirements are covered. The many different control functions will be designed and implemented in ITER PCS simulation platform (PCSSP) by different designing teams, both internal and external to ITER Organization. Although each team will be responsible for the independent assessment of the modules they deliver, an extra step is, nevertheless, necessary to guarantee that all the modules still continue to work when connected together. Therefore, integrated assessments will be built from independent assessments and will prove the controllers continue to meet the requirements. For this reason, it is necessary to have a unified workflow for the assessments performed by all the different designing teams. In fact, in order to guarantee a smooth integration assessment, it is important that all the assessments follow the same rules, use the same tools, are provided with the correct information, and are performed on the same platform. In this article, we present the proposed assessment workflow for ITER PCS components and some early impressions gathered from assessments of first delivered modules
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