1,721,253 research outputs found
Simplified MC Simulation of Neutron Spectra at C-Pb, C-Unat, C-Fe Interfaces Induced by Fast Neutron Source.
No full textOne of the peculiarities of HTGR systems is the variability of the neutron spectrum in the core and reflector regions. Neutronic codes for reactor physics design and burnup analysis may then experience difficulties in reproducing correctly the flux behaviour in proximity of interfaces with the reflector, or absorbing control materials. In order to reduce these problems, benchmark experiments are proposed on the fast source reactor TAPIRO at the ENEA Casaccia Center. The experiments would consist in detection traverses in a graphite column, starting from near external reflector boundary, where a sector of the outer copper reflector has been removed and then characterized by a very hard neutron spectrum. Along the column the spectrum gradually softens up to thermal values. Different materials would be interposed, such as Unat, Pb, Fe, etc. to reproduce spectrum transition conditions at interface points between regions with different compositions. Activation foils would be used for activation analysis with threshold energies in the fast, intermediate and epithermal regions. A preliminary, simplified simulation exercise has been done aiming at showing the spectral changings occurring at material interface points for a number of configurations of the graphite column. The results have been calculated using a continuous energy Monte Carlo code (MCNP)
Metodo per la stima del punto caldo di un nocciolo di reattore nucleare basato su tecniche perturbative generalizzate (GPT)
Get PDFViene descritto un metodo mediante il quale I'informazione ottenuta in tempo reaIe
attraverso un sistema di dispositivi di misura neutronica SPND (collettroni) inseriti nel
nocciolo di un reattore nucleare di potenza (in particolare, un PWR) consente la
rilevazione in tempo reale di un eventuale punto caldo durante I'operazione dell'impianto. II metodo si basa sulle tecniche perturbative GPT (Generalized
Pertubation Methods), per il calcolo dei coefficienti di sensitivita delle quantita integrali
misurate con i collettroni rispetto ai parametri considerati per rappresentare il punto
caldo, e nell'uso di tecniche di inferenza statistica che tengono conto degli errori
associati alle misure. La metodologia consente anche di valutare I'effetto sulla qualita
del sistema di rilevazione dovuto al possibile degradarsi dei dispositivi di misura durante il cicio di vita del nocciolo. Questa informazione può essere utilizzata per poter
predisporre una strategia di protezione adeguata in termini di qualita, numero e
distribuzione dei collettroni
Application of the HGPT Methodology to Reactor Operation Problems with a Nodal Mixed Method
No full textRedacted: il mal d'archivio dopo l'11/09/2001
No full textL'articolo legge Redacted di Brian De Palma (2008) come un film che rende conto sia dei problemi geopolitici innescati dalla politica statunitense nel periodo successivo all' 11 settembre 2001, sia di una riflessione sul ruolo del cinema e dell'audiovisivo nell'epoca della convergenza digitale
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
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