1,720,976 research outputs found
Impiego della reazione polimerasica a catena (PCR) "Real time" nella diagnosi microbiologica
No full textCorso di laurea in Tecnico di laboratorio biomedic
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
Shape optimization and uncertainty assessment of a centrifugal pump
No full textCentrifugal pumps, being used nowadays for many applications, must be suited for a wide range of pressure ratios and flow rates. To overcome difficulties arising from the design and performance prediction of this class of turbomachinery, many researchers have proposed coupling Computation Fluid Dynamics (CFD) codes and optimization algorithms for fast and effective design procedures. However, uncertainties are present in most engineering applications such as turbomachines, and their influence on performance should be assessed. In this work, some advanced optimization techniques are applied to the blade optimization of a European Research Community on Flow, Turbulence and Combustion (ERCOFTAC)-like pump, and the robustness of the optimal profiles through an uncertainty quantification study is assessed. Two primary sources of uncertainty are considered: (i) equipment uncertainties, primarily the rotational speed of the pump shaft that also affects the flow rate; and (ii) uncertainties in the inlet turbulence quantities in CFD simulations
Assessment of an Improved Delayed X-LES Hybrid Model for the Study of Off-Design Conditions in Centrifugal Pumps
No full textCentrifugal pumps work in a wide range of conditions, often far from the design condition. The flow field can be characterized by large separations, vortex dynamics, and, in general, unsteady turbulent phenomena. Strongly off-design conditions are characterized by large separations that lead to efficiency loss, vibrations, and even to fatigue failure. Therefore, the capability to predict the flow field in these conditions is of great interest and computational fluid dynamics (CFD) can represent a viable solution, which can also complement or substitute experimental measurements. In this context, the Reynolds-averaged Navier-Stokes (RANS) approach allows to accurately simulate attached turbulent flows around complex geometries but it fails the prediction of massively separated flows, crucial for the off-design performance. To overcome this limitation, scale-resolving simulations based on the large eddy simulation (LES) can be used. However, their computational cost is too large for a routine use in industry. In centrifugal pumps, where the typical Reynolds number is in the range 105-106, the use of a hybrid RANS-LES model or a wall modeled LES approach seems mandatory to improve the RANS accuracy and reduce the LES computational cost. In this work, an improved version of the extra-large eddy simulation (X-LES) model, the delayed X-LES or DX-LES model, is implemented in the open-source tool-box openfoam v.1812 and is assessed in the computation of the flow field through a centrifugal pump impeller, both at the design and one-quarter loads. The results are compared with experimental data and LES results available in literature
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
Uncertainty Assessment of an Optimized ERCOFTAC Pump
No full textCentrifugal pumps, being used nowadays for many applications, must be suited for a wide range of pressure ratios and flow rates. To overcome difficulties arising from the design and performance prediction of this class of turbomachinery, many researchers proposed the coupling of CFD codes and optimization algorithms for a fast and effective design procedure. However, uncertainties are present in most engineering applications such as turbomachines, and their influence on turbomachinery performance should be considered. In this work we apply some advanced optimization techniques to the blade optimization of an ERCOFTAC-like pump, and we assess the robustness of the optimal profiles through an uncertainty propagation study. The main sources of uncertainty are related to the operating conditions, primarily the rotational speed of the pump shaft that affects also the flow rate
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
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