1,721,796 research outputs found
Analysis of flow blockage of a single RBMK channel
No full textThe aim of the this study is to perform an evaluation of the behaviour of a single RBMK reactor core
fuel channel focusing on the fuel clad and the Pressure Tube, in case of a flow blockage accident. The
tools used were the RELAP5 and FRAP code. The RBMK channel, the graphite stack and the He-N2
gap were modelled with the RELAP5 code; the thermo-mechanical fuel rod behaviour was studied by
FRAP code. Some cases were analyzed considering different values of coolant flow reduction at
different values of the channel power in order to demonstrate if the break of the pressure tube and the
failure of fuel clad occur. A failure map was drawn identifying safe operational zones for the Pressure
Tube and the fuel clad
EFFICACIA CLINICA DI TERAPIE COMBINATE MULTICOMPONENTE A BASE DI KRAMERIA O ZANTHOXYLLUM NELLE VULVOVAGINITI INFETTIVE, ATROFICHE E NELLE VAGINOSI
No full text
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
The Individual Channel Monitoring (ICM) proposal to improve the safety performance of RBMK
No full textA comprehensive study has been completed in relation to the accident analysis of RBMK with key results documented in three companion
papers in the present journal volume. The study also aimed at the comparison between selected accident analysis topics in Light Water Reactors
(LWR) and RBMK. The relevance of the Fuel Channel Blockage (FCB) event within the area of accident analysis was confirmed. Owing to the
probability of occurrence, also connected with the large number of channels, estimated in the order of 10−2 /reactor/year, the FCB is actually part
of the Design Basis Accidents (DBA) for the RBMK.
In case the FCB is part of the DBA, a noticeable difference occurs in results from safety evaluations between LWR and RBMK: in the latter
case, a DBA causes a loss of integrity for the pressure barrier and, though to a limited extent, damaged fuel overpasses such a barrier. The FCB
event also causes contamination in reactor cavity and in selected parts of the overall confinement, damage in various graphite blocks and, even
excluding the MPTR risk owing to the findings from the second companion paper in this journal volume, mechanical loads on neighbouring fuel
channels, graphite stacks and reactor tank that need extensive examination before reactor restart.
Therefore, a proposal has been formulated for performing the feasibility analysis for the design of a system denominated ICM (Individual
Channel Monitoring). The goal of the ICM is the early detection of the FCB event and the triggering of scram in such a way to prevent pressure
tube damage and, definitely, over-passing of the pressure barrier by molten or damaged fuel during a DBA situation.
The ICM is based upon the signals of pressure-drop (or flow-rate) and fluid temperature transducers installed in the bottom and the upper parts
of the fuel channels, respectively. The performed study shows that steam superheating at fuel channel outlet occurs early after the blockage event
and the related temperature signal can be used to cause scram. The availability of sophisticate computational tools including the detailed neutron
kinetic model for each core channel, made possible the preliminary conclusion of the study
An evolutionary multiobjective strategy for the effective management of groundwater resources
Full text linkThis paper introduces a modelling approach aimed at the management of groundwater re-sources based on a hybrid multiobjective paradigm, namely the Evolutionary Polynomial Re-gression. Multiobjective modelling in hybrid evolutionary computing enables the user (a) to find a set of feasible symbolic models, (b) to make a robust choice of models and (c) to improve the computational efficiency developing simultaneously a set of models with diverse structural parsimony levels. Moreover the methodology here presented proves to be particularly fit to those cases where the input to the process and the boundary conditions are not easily accessible. The multiobjective approach is based on the Pareto dominance criterion and it is fully integrated into the Evolutionary Polynomial Regression paradigm. This approach proves to be effective for modelling groundwater systems, which usually requires (a) accurate analyses of the underlying physical phenomena, (b) reliable forecasts under different hypothetical sce-narios and (c) good generalisation features of the models identified. For these reasons it is important to construct easily interpretable models which are specialized for well defined pur-poses. The introduced methodology is tested on a case study concerned with the determination of the dynamical relationship between rainfall height and groundwater levels for a shallow unconfined aquifer located in southeast of Italy, which is climatically a Mediterranean zone
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