1,720,958 research outputs found
Progress toward Monte Carlo–thermal hydraulic coupling using low-order nonlinear diffusion acceleration methods
Full text linkA new approach for coupled Monte Carlo (MC) and thermal hydraulics (TH) simulations is proposed using low-order nonlinear diffusion acceleration methods. This approach uses new features such as coarse mesh finite difference diffusion (CMFD), multipole representation for fuel temperature feedback on microscopic cross sections, and support vector machine learning algorithms (SVM) for iterations between CMFD and TH equations. The multipole representation method showed small differences of about 0.3% root mean square (RMS) error in converged assembly source distribution compared to a conventional MC simulation with ACE data at the same temperature. This is within two standard deviations of the real uncertainty. Eigenvalue differences were on the order of 10 pcm. Support vector machine regression was performed on-the-fly during MC simulations. Regression results of macroscopic cross sections parametrized by coolant density and fuel temperature were successful and eliminated the need of partial derivative tables generated from lattice codes. All of these new tools were integrated together to perform MC-CMFD-TH-SVM iterations. Results showed that inner iterations between CMFD-TH-SVM are needed to obtain a stable solution
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
Cross Section Generation Strategy for High Conversion Light Water Reactors
No full textHigh conversion water reactors (HCWR), such as the Resource-renewable Boiling Water Reactor
(RBWR), are being designed with axial heterogeneity of alternating fissile and blanket zones to
achieve a conversion ratio of greater than one and assure negative void coefficient of reactivity. This
study assesses the generation of few-group macroscopic cross sections for neutron diffusion theory
analyses of this type of reactor, in order to enable three-dimensional transient simulations. The goal
is to minimize the number of energy groups in these simulations to reduce computational effort.
A two-dimensional cross section generation methodology using the Monte Carlo code
Serpent, similar to the traditional deterministic homogenization methodology, was used to analyze a
single RBWR assembly. Results from two energy group and twelve energy group diffusion analyses
showed an error in multiplication factor over 1000 pcm with errors in reaction rates between 10 and
60%. Therefore, the traditional approach is not sufficiently accurate. Instead, a three-dimensional
homogenization methodology using Serpent was developed to account for neighboring zones in the
homogenization process. A Python wrapper, SerpentXS, was developed to perform branch case
calculations with Serpent to parametrize few-group parameters as a function of reactor operating
conditions and to create a database for interpolation with the nodal diffusion theory code, PARCS.
Diffusion analyses using this methodology also showed an error in multiplication factor over
1000 pcm.
The three-dimensional homogenization capability in Serpent allowed for the introduction of
axial discontinuity factors in the diffusion theory analysis, needed to preserve Monte Carlo reaction
rates and global multiplication factor. A one-dimensional finite-difference multigroup diffusion
theory code, developed in MATLAB, was written to investigate the use of axial discontinuity factors
for a single RBWR assembly. The application of discontinuity factors on either side of each axial
interface preserved multiplication factor and reaction rate estimates between transport theory and
diffusion theory analyses to within statistical uncertainty. Use of this three-dimensional assembly
homogenization approach in generating few-group macroscopic cross sections and axial
discontinuity factors as a function of operating conditions will help further research in transient
diffusion theory simulations of axially heterogeneous reactors.U.S. Department of Energy. Office of Naval Reactors (Rickover Fellowship Program
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
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