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Luigi Garlatti Venturini (1885 – 1962). Progetti per la città di Ancona nella prima metà del Novecento
No full textAcoustic control of a coaxial jet
No full textMeasurements in the near field of a coaxial jet under unperturbed and controlled conditions are reported; the Reynolds number (defined with diameter and exit velocity of the inner-jet) is 5600, while the ratios of the velocities and of the diameters of the two jets are 1.8 and 2, respectively. The unperturbed flow, which issues in a nominally laminar state from the contraction nozzles, develops a shear-layer mode instability in the outer-shear layer of the outer-jet, followed by vortex pairing. A control perturbation, composed of sinusoidal acoustic waves at the frequency of the instability and its half, is applied to the flow. The control parameter is the phase difference Δφ between the two sinusoidal waves, and is initially varied in the entire range of phases. Then, two values of Δφ, providing the maximum attenuation and enhancement of the turbulence intensity, are chosen and, for these, detailed measurements in the axial and radial directions are performed. The data show that the control affects the mean and turbulent fields and is able to redistribute the kinetic energy between them. As a result, the potential core of the inner-jet can be shortened or lengthened. The turbulence intensity can also be modified, thus altering the ratio of the streamwise to the radial velocity components, and the ratio of the fundamental to the subharmonic spectral components.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Experimental analysis of the flowfield at the exit of a premixer for combustion applications
No full textThe flowfield at the exit of a premixer for combustion applications is experimentally studied under isothermal conditions. The premixer produces a main swirling flow, while an injector, positioned on the jet axis, generates four jets in cross-flow mimicking the fuel introduction. The main nozzle has a variable geometry to simulate different operative conditions. Two configurations, in which the flow rate of the fuel cross-flow jets is varied, are examined. Mean and fluctuating streamwise velocity profiles, acquired by means of laser Doppler anemometry (LDA) at the exit plane of the premixer, are presented for all of the geometrical setups and compared with the surrogate fuel distribution at the exit plane. The mixing characterization is provided either by means of an intrusive gas sampling technique and non-intrusive flow-visualization analyses. Results show that the velocity flowfield is considerably affected by the relative strength of the fuel jets with respect to the main swirling flow, and by the boundary conditions at the nozzle exit. Comparison of the mixing and velocity data shows that for some configurations there is a matching between the streamwise velocity momentum and scalar distributions. Correspondingly, the fuel jets at the exit plane maintain a marked individuality. © 2003 Elsevier Inc. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Small-scale statistics, local isotropy and axial symmetry in the far field of turbulent round jets: a comparison between PIV and HWA
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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
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