1,720,969 research outputs found
Development of the EUROfusion pedestal database for ELMy H-Mode for the TCV tokamak
Full text linkLAUREA MAGISTRALEQuando, in un tokamak, viene fornita potenza al di sopra di un livello di soglia, il pla-
sma subisce una brusca transizione che porta alla creazione di una barriera di trasporto ai bordi, miglio-
rando cos`ı le capacità di confinamento del plasma stesso. Questo regime ` e chiamato High-confinement
Mode, o H-Mode: i vantaggi di questo regime sono molteplici rispetto al regime di confinamento che
precede l’H-Mode, l’L-Mode, in particolare il miglioramento dell’energy confinement time, che raddop-
pia approssimativamente di valore. Il regime di confinamento in modalità H sarà uno dei principali
scenari operativi di ITER, il futuro progetto internazionale sulla possibilità e la convenienza di effet-
tuare reazioni di fusione nucleare. Tuttavia, un plasma in H-Mode ` e l’insorgere di instabilità MHD che
si rilassano mediante processi chiamati Edge Localized Modes (o ELMs), espulsioni di plasma dalla
regione in cui il plasma stesso ` e confinato; tali espulsioni di plasma corrispondono ad una perdita di
confinamento e carichi termici pulsati contro componenti chiave come il divertore, riducendo cos`ı signi-
ficativamente la loro vita operativa.
A seconda di un ampio intervallo di parametri operativi, gli ELM che verranno generati saranno diversi.
Come tale, vorremmo capire quali sono le condizioni più significative che influenzeranno la generazione
di un tipo di ELM rispetto ad un altro, al fine di prevedere quali ELM si genereranno all’interno della
macchina considerata. Poich ́ e lo studio degli ELM ` e un settore di ricerca aperto, dove non si ha ancora
una teoria completa, per derivare risultati abbiamo bisogno di profili e comportamenti che si ripetono
anche in tokamak diversi, e questo significa raccogliere dati da esperimenti e macchine diverse. Per que-
sto motivo, EUROFusion sta promuovendo la creazione di un database riguardante i plasmi H-Mode
con generazione di ELM da parte di tokamak in tutto il mondo, concentrandosi in particolare nella
regione del pedestal, in quanto esiste una correlazione tra questa regione e la generazione di ELMs,
con l’obiettivo di comprendere e prevedere il comportamento e l’aspetto degli ELMs in ITER. Questo
lavoro di tesi mira a costruire una prima versione di quello che sarà il database del pedestal in ELMy
H-mode per la macchina operante presso lo Swiss Plasma Center, il Tokamak à Configuration Variable,
o TCV; per fare ciò, sono stati raccolti i dati dal Thomson Scattering System in servizio nella macchina,
ricavando dei fit dai dati e calcolando il plasma in equilibrio utilizzando il codice iterativo CHEASE,
utilizzando cos`ı le quantità estrapolate per costruire il database stesso; infine, sono state fatte alcune
considerazioni sulle quantità del nuovo database costruito, come profili che si ripetono in altre macchine.When, in a tokamak, external power is supplied above a threshold level, the plasma
undergoes an abrupt transition which leads to the creation of an edge transport barrier,
thus improving the confinement capabilities of the plasma itself. This regime is called
High-confinement Mode, or H-Mode; its features are several: the increasing of the temper-
ature, density and pressure profiles, leading to the formation of a region of steep gradients
at the plasma edge, called pedestal; the generation of an edge current called bootstrap
current; and, most importantly, the improvement of the energy confinement time, which
approximately doubles in value with respect to the confinement regime preceding the
H-Mode, the so-called L-Mode. For these reasons, the H-Mode confinement regime is one
of the primary operational scenarios at ITER, the future international project regarding
nuclear fusion feasibility at ignition conditions.
However, one of the consequences when operating in H-Mode is the arising of instabilities
called Edge Localized Modes (or ELMs), which are ejections of plasma from the region
where the plasma itself is confined; ELMs are triggered after the confined plasma reaches
an MHD instability limit, and even though they have ameliorating effects on some nega-
tive aspects of the H-Mode, such as expelling impurities from the highly confined plasma,
the plasma ejections correspond to a loss of confinement and pulsed heat loads against
key components like the divertor, thus significantly reducing their operating life.
Depending on a wide range of conditions, such as power input, impurity and fuel injec-
tions, geometric and magnetic configuration parameters and much more, the ELMs that
will generate will be different. As such, one would like to understand which are the most
significant conditions that will influence the generation of a type of ELM with respect
to another, in order to predict which ELMs will generate inside the considered machine.
Since there is an extensive bibliography about this topic, but ELMs study is still an open
research field, the theory concerning this phenomenon is majorly empyrical. As such, the
need scaling laws and behaviors that repeats themselves in different tokamaks is imper-
ative, and this means that gathering data from different experiments and from different
machines can be a good starting point to reach that goal. For this reason, EUROFusion is
promoting the creation of a database concerning ELMy H-Mode plasmas from tokamaks
all over the world, focusing in particular in the region of the pedestal, since there is a
correlation between this region and the ELMs generation, with the objective to under-
stand and predict the ELMs behavior and appearance in ITER.
This thesis work aims to build a first version of what the pedestal database will be for the
machine operating at the Swiss Plasma Center, the Tokamak à Configuration Variable,
or TCV; in order to do so, data from the Thomson Scattering System have been gath-
ered, then getting fitted profiles from them and by calculating the plasma at equilibrium
by using the CHEASE iterative code, thus using the extrapolated quantities to build
the database itself; finally, some considerations over the quantities of the newly built
database, such as common behaviors and basic trends, have been made
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
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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