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공간의존 궤환효과가 포함된 원자로의 동특성 계산을 위한 해석함수전개 노달방법에서의 분해 해법
No full text학위논문(박사) - 한국과학기술원 : 원자력양자공학과, 2002.2, [ vi, 106 p. ]During the last several years, the analytic function expansion nodal (AFEN) method has been developed and successfully applied to static reactor analysis. In this thesis, we develop kinetics calculational capability of the AFEN method. We propose a novel method with the time-dependent solution decomposed into an analytic part and a polynomial correction part. The analytic part consists of the analytic solutions of the "quasi-static" diffusion equation. The polynomial correction part is determined applying a Galerkin scheme. The kinetic equations are discretized in time after exponential transformation of the neutron fluxes. This enables the method to use larger time step size than the case of direct differencing of the fluxes. The relation of delayed neutron precursor densities between time steps is obtained analytically by using the transformed fluxes and assuming linear variations of the fission rates within a time step. After the discretization in time and space, we use no more approximations except the solution decomposition.
During transient, the cross sections within a node change due to the space-dependent feedbacks. In conventional nodal methods, rehomogenization or four nodes/assembly calculation are needed to overcome this problem. However, in our method, we only need to add the weighted integrals of space-dependent terms in the equation. All other types of space-dependent cross sections can be treated in the same manner. In this thesis, we model the cross section variation using Legendre polynomial bases. The computing time increase due to space-dependent feedback is marginal, and it becomes negligible with infrequent update of the correction part. For the acceleration of the method, coarse group rebalance (CGR) scheme is modified and applied. The computing time is greatly reduced by applying this scheme. In three-dimensional problems, we incorporate the bilinear weighting method to treat the control rod cusping problem occurring in the partially rod...한국과학기술원 : 원자력양자공학과
연소경사가 일어난 핵연료집합체 노심을 위한 수정 해석함수전개 노달방법
No full text학위논문(석사) - 한국과학기술원 : 원자력공학과, 1996.2, [ iv, 42 p. ]In this thesis, a new burnup correction model for the AFEN (Analytic Function Expansion Nodal) method is developed and applied to two-dimensional, two-group neutron diffusion problems in rectangular geometry. In this model, the intranodal flux distribution of the burnt fuel assembly is expanded in a combination of analytic basis functions and additional polynomial correction terms, while only analytic basis functions are used for homogeneous assemblies. The analytic basis functions are obtained using the volume-averaged group constants of the burnt assembly and low order (first or second order) polynomials are used as the correction terms.
As in the homogeneous AFEN, all the expansion coefficients of flux distribution are expressed in terms of nine nodal quantities (one node average flux, four surface average fluxes, four corner point fluxes) in two-dimensional rectangular geometry. For a burnt fuel assembly, the number of expansion coefficients is larger than that of nodal unknowns because of the polynomial correction terms. The additional conditions to determine the coefficients of the correction terms are obtained using a weighted residual method.
This burnup correction model does not require additional discontinuity factors and flux-volume-weighted cross sections, which are, however, needed in the rehomogenization model (that rehomogenizes the burnt fuel assembly using equivalence theory). Therefore, the newly developed method is free from uncertainty of rehomogenization.
The new burnup correction model was implemented and the capability to treat the intranodal cross section gradients was tested on several benchmark problems. The results show that the model developed in this study eliminates almost all the errors in the nodal unknowns which are induced by the intranodal burnup gradients. Also we note that the first order polynomial correction can provide accurate solutions even for a steep burnup gradient and that additional accuracy is obtained from the se...한국과학기술원 : 원자력공학과
Improved Features of the AFEN Method in Hexagonal-Z 3-D Geometry for Neutron Diffusion Calculation
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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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