1,721,100 research outputs found
Technical Specification for a Synthetic Jet Experiment
No full textViene controllata la separazione della corrente attorno al profilo alare Naca 0024 mediante getti sintetici alle elvate incidenz
Effects of a trapped vortex cell on thick wing profile
Full text linkExperimental investigation on the effects originated from a trapped vortex cell on the NACA0024 airfoi
An experimental investigation of rotor wakes by means of time-resolved PIV measurements
No full textRotor wakes generated by a four-bladed isolated rotor of a scaled helicopter model in hover have been investigated by time-resolved particle image velocimetry. Two rotor speeds, i.e., Ω/2π equal to 29.9 Hz and 26.3 Hz, have been considered resulting in flow regimes defined by a tip Mach number and a chord Reynolds number of ∼0.20 and ∼1.50×105 or ∼0.17 and ∼1.32×105, respectively. The rotor disk generates aerodynamic loads for a thrust coefficient of CT=5.7×10−3, and a rotor solidity of σ=0.116. It is found an intensification of thrust fluctuations as the rotor speed increases, i.e., the amplitude of the standard deviation at 29.9 Hz intensifies approximately of 3.5 times more than that observed at 26.3 Hz. This enables the inspection of how aerodynamic loads, featured by two levels of fluctuation amplitudes, impact the spatial organization and dynamics of the wake structures. Data-driven decomposition methods, i.e., Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD), have been exploited for analyzing the most prominent coherent structures. A wake contraction inward the radial direction occurs suddenly below the rotor disk. The early wake ages feature overlapped trajectories of the tip vortices indicating a regular formation process. Conversely, as the tip vortices advect further downstream, their trajectories progressively depart from each other, and engulfment events appear. The dominance of the periodic shedding of the tip vortices was captured by both modal decompositions. The first pair of POD modes describe the spatial organization of the tip vortices and the engulfment. The corresponding time coefficients include multiple frequency peaks discerning the most prominent contribution ascribed to the tip vortex shedding for both rotor speeds. POD analysis highlights slightly higher efficiency at slower rotor speed, exhibiting a more spectral purity for the first couple of time coefficients. Despite multiple harmonics featuring the most energetic flow structures, the dominant pulsation attains a Blade Passing Frequency BPF=1 for both rotor speeds. Similarly, DMD analysis captures the tip vortices at BPF=1. However, the shear layer embeds additional flow structures pulsating at different harmonics, that include wake characteristics at BPF=0.25, secondary representation of the tip vortices scattering in the shear layer (BPF=1.5 and 2)
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
"Ocular hydrodinamic disorder induced by topical steroids revealed by means of Ibopamine test.
No full textOcular hydrodinamic disorder induced by topical steroids revealed by means of Ibopamine test
Investigation of the velocity field by means of PIV on airfoil models affected by ice accretions
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