1,721,089 research outputs found
Carlos Santiago Nino e la democrazia deliberativa
No full textC.S. Nino e la tesi del diritto come caso speciale della morale. Tre livelli giustificativ
Fluid Dynamics Measurements and Flow Visualizations of a Free Slot Jet of Air
No full textThe paper reports flow visualizations of a free slot jet of air, obtained with the shadowgraph technique, in the Reynolds number range allowed by the experimental apparatus, i.e. from Re=1,682 to Re=22,107. The Reynolds number is based on the hydraulic diameter of the slot. The shadowgraphs have confirmed the presence of the undisturbed region of flow, which is the zone of the jet flow where velocity and turbulence are about the same as those measured on the slot exit. The undisturbed region of flow is dependent on the Reynolds number. It is higher than three times the slot height, for Re=1,682, and equal to the slot height, for Re=22,107. To confirm the findings of the visualizations, fluid dynamics measurements have been carried out with the hot wire anemometry. The fluid dynamics measurements have confirmed these values with a little over-prediction
Small Gaseous Jets Visualized by Means of a Laser Speckle Based Background Oriented Schlieren Technique.
No full textAbstract. Small size synthetic jets have been investigated by means of a Particle Image Velocimetry (PIV) technique and the obtained results compared with the visualizations obtained with the recently introduced laser Speckle Based Background Oriented Schlieren technique (Speckle BOS). The latter technique have been adopted in order to increase the sensitivity of the standard Background Oriented Schlieren (BOS) technique and visualize the density inhomogeneity (essentially the inhomogeneity of the refractive index of the gas) induced by a gaseous isothermal jets injected in a quiescent gaseous environment. Since the isothermal and low speed jets, the induced effects on the surrounding environment are so small as to require the adoption of a visualization technique as sensitive as the interferometry techniques, so the Speckle BOS technique showed a high sensitivity with a remarkable simplicity of execution of the reliefs. The gaseous flows studied are substantially two: the first was constituted by a synthetic jet (not stationary) generated by the use of a small speaker normally used in the earphones of the headphone audio; while the second jet is formed by steady state conditions butane jet, discharged by means of a cylindrical duct with an internal diameter of 2.5 mm. The latter jet, having a different refractive index than ambient air, has been used to investigate the ability of optical resolution of the adopted speckle BOS technique
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
VISUALIZATION OF SUBMERGED ANNULAR JET EXITED BY MEANS OF A SYNTHETIC JET
Full text linkABSTRACT
In the school present paper the characterization of the flow field generated by means of a submerged gaseous jet exited by means of a coaxial synthetic jet has been investigated. The porpoise of this investigation is to infer the aerodynamic interaction of the two fluid structures that play an interesting role in several industrial applications like jet actuator, flame stability in the combustor for mini/micro gas turbine, etc.
Substantially two laser techniques have been employed: a Laser Döppler Velocimetry (LDV) featuring a high signal-noise ratio able to extract information from velocity time series in a few location in the jet flow and used, also, for an accurate determination of the Reynolds number. A Particle Image Velocimetry (PIV) system is also employed, in order to obtain instantaneous two dimensional velocity distribution overall the entire gaseous jet. Both techniques have been carried out by stretching the influences of coherent structures generated in the jet, by means of natural aerodynamic effect and by means of perturbation forced in the flow by means of the synthetic coaxial jet. The investigated conditions are ranging from Reynolds number (Re) 1000 to 3000 at several plate distance nozzle diameter ratio (but only the most significant results obtained at h/d=2 are reported in this paper). The synthetic jet has been generated by means of a loudspeaker driven at a pure sinusoidal wave at several frequencies in order to obtain different Strouhal number (St)
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
Bragg cell and rotating grating frequency shifting in laser vibrometer: a metrological and operating comparison
No full textAn experimental comparison has been carried out between two laser Doppler vibrometers, different as for frequency shift generation between measuring and reference beam of the interferometer. In particular, two systems, based either on a Bragg cell or on a rotating diffraction grating for frequency shifting, have been compared, with reference to both metrological and operating behavior. Based on the analysis of experimental information, a quantitative evaluation has been carried out of the effect on either optical configuration of the most typical operative parameters to be taken into account in laser Doppler vibrometry, in order to define the best optical lay-out and configuration depending on the specific industrial application
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