1,720,988 research outputs found
난류성 정전기 표류파 연구를 위한 전산모사 코드 개발
No full text학위논문(박사) - 한국과학기술원 : 물리학과, 2003.2, [ vi, 61 p. ]Global drift wave map equations that allow the integration of particle orbits on long time scales are implemented to describe transport. Ensembles of test particles are tracked to simulate the Low-confinement mode/Reversed Shear/Enhanced Reversed Shear plasmas in Tokamak Fusion Test Reactor(TFTR) tokamak and the Optimized Shear plasma in Joint European Torus(JET) tokamak. The simulations incorporate a radial electric field, , obtained from a neoclassical calculation, and a model for drift wave fluctuations that takes into account change in the mode structure due to . Steady state particle density profiles along with two different measures of transport, the diffusion coefficient based on a running time average of the particle displacement and that calculated from the mean exit time, are obtained. For either weak or reversed magnetic shear and highly sheared , particle transport barriers are observed to be established. In the presence of such a transport barrier, it is shown that there is, in general, a difference between the two measures of transport. The difference is explained by a simple model of the transport barrier.
To investigate the physical properties of the electrostatic ion temperature gradient turbulence occurred in toroidal plasmas and associated ion energy and particle transports, we developed a numerical simulation program. The program was designed to solve the gyrokinetic Vlasov Poisson system by using the δ f particle in cell simulation scheme in 3-dimensional toroidal geometry in fully parallel ways. Its performance was tested varying number of processing elements used in calculation and we could confirm a good scalability.
For the validation of the simulation program, we compared the simulation results with known analytical solutions and local analysis. The linear simulation results showed a good agreement with the solutions of the local dispersion relation and reproduced the well known characte...한국과학기술원 : 물리학과
Coarse graining of kinetic equation
No full text학위논문(석사) - 한국과학기술원 : 물리학과, 1998, [ ii, 48 p. ; ]한국과학기술원 : 물리학과
Verification of fast ion and rotation effects on turbulence through comparison of GENE and CGYRO with L-mode plasmas in KSTAR
No full textThis study presents a cross-verification of fast ion effects on turbulence through a systematic comparison of two leading gyrokinetic codes, GENE Jenko et al (2000 Phys. Plasmas 7 1904-10) and CGYRO Candy et al (2016 J. Comput. Phys. 324 73-93), using L-mode plasma profiles from KSTAR for local linear and nonlinear electromagnetic simulations. The focus is on the impact of fast ions and rotation effects on energy flux, aiming to identify the similarities and differences between these codes in the context of turbulence transport research. The analysis shows consistency in linear stability results, fractional changes in energy flux, changes in the spectral distribution of energy fluxes, fluctuations and phase angle with fast ions, and zonal shearing between the codes. However, discrepancies arise in absolute thermal energy levels and rotation effects on energy transport, especially in the presence of fast ions. The study underscores the critical importance of phase angle analysis in gyrokinetic code verification, particularly when assessing fast ion effects on turbulence. Additionally, it highlights the need to examine quantities at lower levels of the primacy hierarchy, as discrepancies at lower levels can lead to divergent results at higher levels. These findings indicate the necessity for further investigation into these discrepancies and the novel phase angle structures observed, contributing to the advancement of accurate transport predictions in fusion plasmas. The near-marginality inferred in this study introduces additional challenges for precise cross-code comparisons; future research will further explore strategies to address these issues and enhance verification methodologies.
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
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