1,721,311 research outputs found
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
Transport barrier and current profile studies on the JET tokamak
Get PDFOne of the crucial problems in fusion research is the understanding of heat and particle transport in plasmas relevant for energy production. The neo-classical theory of tokamak transport is well-established, but it cannot explain experimental results. Instead, the micro-turbulence driven anomalous transport has been found to be dominant in present tokamak experiments.
There are several mechanisms that can locally suppress micro-turbulence and reduce significantly the anomalous transport. These regions of reduced transport are called transport barriers. The presence of Internal Transport Barriers (ITBs) is one of the bases in 'Advanced Tokamak Scenarios'. One of the principal goals in the 'Advanced Tokamak Scenarios' is to improve the fusion power density and confinement with internal transport barriers by controlling the current density profile and maximising the bootstrap current - and ultimately rendering the tokamak compatible with continuous operation.
This thesis reports on studies and modelling of internal transport barriers and current density profiles in the Joint European Torus (JET) tokamak with a fluid transport code. Explanations for the following open questions are sought: what are the mechanisms that govern the formation and dynamics of the ITBs in JET and secondly, how can the current density profile be modified and further, how does it affect ITBs and plasma performance?
On the basis of the empirical study at the ITB transition, the ωE×B flow shear and magnetic shear appear as strong candidates in determining the onset time, the radial location and the dynamics of the ITBs in JET. This ITB threshold condition, employed in the semi-empirical Bohm/GyroBohm transport model, has been found to be in good agreement with experimental results in predictive transport simulations. On the other hand, the simulation results from the predictive transport modelling with a theory-based quasi-linear fluid transport model strongly emphasise the importance of the density gradient in the ITB formation.
According to the current density modelling studies, lower hybrid and electron cyclotron current drive are the most versatile current drive methods in terms of the produced q-profile in the preheating phase in JET. With lower hybrid preheating, a core current hole has been found and a physics-based explanation, confirmed by the transport modelling, is given. The predictive transport simulations indicate that application of lower hybrid current drive during the high performance phase can enhance the fusion performance significantly by increasing the ITB radius.reviewe
Alahybridiaaltojen mooditransformaatiot tokamakeissa
No full textTällä hetkellä lupaavin laite magneettiseen koossapitoon perustuvalle fuusioreaktorille on tokamak.
Plasman koossapitoon tarvittava toroidaalinen plasmavirta voidaan indusoida muuntajan tavoin, jolloin plasma on muuntajan toisiopiirinä.
Koska muuntaja ei voi indusoida virtaa jatkuvasti, on käytettävä myöskin ei-induktiivista virranajoa.
Radiotaajuusaaltojen käyttö on eräs tapa generoida virtaa.
Tässä työssä tutkittiin alahybridiaaltojen käyttöä virranajoon tokamakeissa.
Alahybridiaaltojen taajuusalueella on olemassa kaksi eri aaltomoodia, hidas ja nopea aalto.
Tietyissä oloissa hidas aalto voi muuntua nopeaksi aalloksi.
Nämä alahybridiaaltojen mooditransformaatiot ovat mielenkiintoisia, koska nopean aallon absorboitumis- ja etenemisominaisuudet poikkeavat hitaan aallon vastaavista ominaisuuksista.
Alahybridiaaltojen etenemistä plasmassa simuloidaan ns. säteenseurantayhtälöiden avulla.
Tässä työssä käytettiin nopeaa säteenseurantakoodia (FRTC), kvasi-toroidaalista säteenseurantakoodia (QRTC) ja analyyttistä säteenseurantamallia.
Tehoabsorptio- ja virrantiheysspektrit laskettiin käyttämällä transport-koodi ASTRA:a, joka on kytketty FRTC-koodiin.
Aiemmin julkaistuissa tutkimuksissa on todettu, että mooditransformaatio on huono asia, koska nopeat aallot etenevät aina ainoastaan plasman reunalla menettämättä energiaansa.
Aiemmasta poiketen tässä työssä on kuitenkin havaittu, että ne pystyvät etenemään ja absorboitumaan myös ITER- ja JET-tokamakien plasman keskustassa muuttaen samalla niiden pikkusäteensuuntaista tehoabsorptiota.
Yhdensuuntaisen taitekertoimen ja plasman tiheyden todettiin vaikuttavan kaikkein eniten mooditransformaatioiden määrään.
FRTC- ja QRTC-koodeilla tehdyt simuloinnit mooditransformaatioista antoivat hyvin samanlaisia tuloksia tukien uutta käsitystä mooditransformaatioiden merkityksestä alahybridiaaltojen virranajossa.
Analyyttisen säteenseurantamallin todettiin olevan pätevä nopeasti absorboituvien säteiden analysointiin
Transport barrier and current profile studies on the JET Tokamak:Dissertation
No full textOne of the crucial problems in fusion research is the understanding of heat and particle transport in plasmas relevant for energy production. The neo-classical theory of tokamak transport is well-established, but it cannot explain experimental results. Instead, the micro-turbulence driven anomalous transport has been found to be dominant in present tokamak experiments. There are several mechanisms that can locally suppress micro-turbulence and reduce significantly the anomalous transport. These regions of reduced transport are called transport barriers. The presence of Internal Transport Barriers (ITBs) is one of the bases in 'Advanced Tokamak Scenarios'. One of the principal goals in the 'Advanced Tokamak Scenarios' is to improve the fusion power density and confinement with internal transport barriers by controlling the current density profile and maximising the bootstrap current - and ultimately rendering the tokamak compatible with continuous operation. This thesis reports on studies and modelling of internal transport barriers and current density profiles in the Joint European Torus (JET) tokamak with a fluid transport code. Explanations for the following open questions are sought: what are the mechanisms that govern the formation and dynamics of the ITBs in JET and secondly, how can the current density profile be modified and further, how does it affect ITBs and plasma performance? On the basis of the empirical study at the ITB transition, the wE B flow shear and magnetic shear appear as strong candidates in determining the onset time, the radial location and the dynamics of the ITBs in JET. This ITB threshold condition, employed in the semi-empirical Bohm/GyroBohm transport model, has been found to be in good agreement with experimental results in predictive transport simulations. On the other hand, the simulation results from the predictive transport modelling with a theory-based quasi-linear fluid transport model strongly emphasise the importance of the density gradient in the ITB formation. According to the current density modelling studies, lower hybrid and electron cyclotron current drive are the most versatile current drive methods in terms of the produced q-profile in the preheating phase in JET. With lower hybrid preheating, a core current hole has been found and a physics-based explanation, confirmed by the transport modelling, is given. The predictive transport simulations indicate that application of lower hybrid current drive during the high performance phase can enhance the fusion performance significantly by increasing the ITB radius
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