1,720,981 research outputs found
A first approach towards DEM analysis of plasticity in pebble beds
No full textIn the solid blanket concept, the tritium breeder and the neutron multiplier are both used in the form of pebble beds. Due to their discrete nature, the Discrete Element Analysis (DEM) allows determining the macroscopic behaviour of the bed as a result of the microscopic interactions among pebbles. At the Karlsruhe Institute of Technology, a Discrete Element Code (KIT DEM code) is constantly under development to support the R&D on the solid breeding blanket. As a further extension of the code, a first approach towards implementing plastic deformation inside pebble beds was investigated. By simulating the plastic deformation of each single pebble, the macroscopic plastic strain of the bed is defined jointly with the rearrangement of the particles in the assembly. Among the approaches reported in literature, the Thornton theory was selected and implemented. In order to validate the method, a comparison with experiments already reported in literature was carried out. Numerical results are in good agreement with the experiment in terms of maximum stress and residual strain. However, due to the approximation introduced by the theory, a perfect linear behaviour which differs from the experimental results is obtained during the plastic loading phase. In this sense, Finite Element analyses were carried out to adjust the correlation describing the plastic loading occurring during uniaxial compression
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
Detection of feline immunodeficiency virus RNA by two nucleic acid sequence based amplification (NASBA) formats
No full textFeline immunodeficiency virus (FIV) is an AIDS-inducing lentivirus that infects domestic cats worldwide. Because of its clinicopathologic similarities to human immunodeficiency virus type I (HIV-1) infection. the FIV/cat infection system is a valuable animal model for investigating comparative aspects of HIV-1 biology. An assay that detects quickly and efficiently FIV RNA in relatively small volume samples of feline blood or other body fluids would be of benefit in studies of viral transmission and antiviral interventions. Nucleic acid sequence based amplification (NASBA) technology is particularly suited for the detection of RNA in a variety of body fluids. In this report, the development of two rapid. sensitive and versatile NASBA formats is described for the detection of FIV gag RNA in plasma from infected cats, RNA detection by either format was unaffected by the presence of feline plasma. The limits of detection were at least 200 copies of input RNA for both formats. Results from seropositive and seronegative feline plasma samples were clearly distinguishable. These results demonstrate that NASBA provides a rapid and sensitive alternative to RT-PCR and culture isolation for detecting FIV RNA in infected feline plasma. (C) 2002 Elsevier Science B.V. All rights reserved
STH/CFD coupled simulation of the protected loss of flow accident in the CIRCE-HERO facility
Full text linkThe paper presents the application of a coupling methodology between Computational Fluid Dynamics (CFD) and System Thermal Hydraulic (STH) codes developed at the University of Pisa. The methodology was applied to the CIRCE-HERO facility in order to reproduce the recently performed experimental conditions simulating a Protected Loss Of Flow Accident (PLOFA). The facility consists of an internal loop, equipped with a fuel pin simulator and a steam generator, and an external pool. In this coupling application, the System code RELAP5 is adopted for the simulation of the internal loop while the CFD code ANSYS Fluent is used for the sake of simulating the pool. The connection between the two addressed domains is provided at the inlet and outlet section of the internal loop; a thermal coupling is also performed in order to reproduce the observed thermal stratification phenomenon. The obtained results are promising and a good agreement was obtained for both the mass flow rates and temperature measurements. Capabilities and limitations of the adopted coupling technique are discussed in the present paper also providing suggestions for improvements and developments to be achieved in the frame of future applications
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
STH/CFD coupled calculations of postulated transients from mixed to natural circulation conditions in the NACIE-UP facility
No full textIn the present paper, coupled STH/CFD calculations are performed addressing two operating conditions in the frame of the NACIE-UP experimental campaign. In order to simulate mixed and natural circulation phenomena related to liquid metals thermal hydraulics, the RELAP5/Mod3.3 STH code and the CFD code ANSYS Fluent are adopted in an integrated manner. The combined use of STH and CFD codes aims to help the user overcoming the limits of the individual techniques and thus achieving a better predicting capability with respect to each stand-alone application. Measured values and calculated results are compared. In particular, the coupled application provides the best results in terms of predicted mass flow rate and comprehensiveness of information giving the possibility to analyse the local and cross-sectional distributions. Furthermore, as an additional beneficial aspect, CFD results can be used as a tuning tool for some of the STH code parameters. The aim of the present work is highlighting the advantages and drawbacks of the adopted techniques, also reporting the margins of error that may presently be expected from these applications. Though perfectly matching results were not obtained, coupled STH/CFD application report promising modelling capabilities and may be consequently considered as a sound candidate for addressing liquid metal thermal hydraulics in complex geometries and large systems
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
- …
