1,721,009 research outputs found
Analytical model for predicting rotor-stator interaction tonal noise in low-speed axial fans
No full textAnalytical models for aeroacoustic simulations are valuable due to their potential to reduce computational costs, a crucial consideration to optimize noise performance. Analytical models proposed so far focus mainly on isolated steady and unsteady fan tonal noise, often neglecting the significant contribution of rotor-stator interaction. As a matter of fact, for short axial spacing, tonal noise from potential flow interactions is relevant. This study presents an analytical model for predicting rotor-stator interaction noise caused by the stator vane potential effect on blades. The model requires only time-averaged flow fields from URANS simulations with periodic boundary conditions. Key features include accounting for uneven spacing and arbitrary chord, twist, and sweep distributions of blades and vanes. The model is based on the Sears aerodynamic model for blade loading fluctuations and the time-domain Ffowcs Williams-Hawkings formulation for noise prediction. Validations with evenly and randomly spaced blade show the model capability to predict tonal noise trends. The model captures noise at the blade passing frequency and harmonics associated with rotor-stator interaction. The model fails to predict noise at higher harmonics due to trailing edge noise sources, not currently accounted for. Future works will extend the model to broadband noise sources
Aeroacoustics Analysis of Radiator Installation Effects in a Pulling Engine Cooling Module
Get PDFFan noise is a critical issue for manufacturers, as they must balance aerodynamic and acoustic performance. Coupling a fan with a radiator in a pulling configuration, introduces significant challenges. Since it is challenging to perform scale resolved simulations of a radiator, an equivalent fluid approach is adopted. This study investigates the effects of an equivalent porous medium mimicking the radiator, and casing geometry on inflow and noise sources in an industrial cooling fan. Three configurations (Fan + Frame + Equivalent Porous Medium, Fan + Frame, Fan) are investigated using high-fidelity simulations. While aerodynamic performance remains consistent, the equivalent porous medium and casing geometry introduce inflow distortions, causing tonal noise variations, particularly in the full module configuration
On the numerical investigation of the tip leakage noise sources of a stationary aerofoil
No full textAmong the various noise sources related to duct fans, the noise generated by the interaction of the tip leakage flow with the blade geometric singularities is one of the least understood noise sources. Our past experimental investigations on a stationary aerofoil have highlighted two tip noise sources, localised at the mid-chord and at 75\% of the chord, which have been linked to the separation of the flow at the pressure side tip edge of the aerofoil. This paper aims at numerically visualise the fluid dynamic instabilities responsible for these noise sources. Furthermore, it examines how these instabilities change when we round the pressure side tip, as this modification leads to a notable 8 dB decrease in the tip noise
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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