1,720,956 research outputs found
An Investigation of Aerodynamic Noise from Standard Ground Vehicles using Computational Aeroacoustics
Get PDFThe noise radiating from ground vehicles and its detrimental effects on occupants,
pedestrians, and the environment have spurred vehicle manufacturers to seek effective noise
prediction methods and mitigation strategies. This thesis focuses on predicting
aerodynamically generated noise from vehicles using a hybrid Computational Aeroacoustics
(CAA) method. This study aims to explore how geometrical features influence noise generation
and provide valuable insights for noise reduction. A hybrid CAA approach is proposed,
employing Stress Blended Eddy Simulation (SBES), and Ffowcs-Williams and Hawkings
(FW-H) acoustic analogy to predict noise radiation from standardised vehicle geometries.
Initially, SBES is validated against experimental data for scaled notchback geometry, followed
by assessing SBES coupled with FW-H to predict noise radiated by half-round mirrors.
Subsequently, the methodology is applied to full-scale vehicle geometry with a bluff mirror
mounted on one side.
The SBES predictions indicate that the flow behaviour behind the backlight of notchback
becomes increasingly asymmetric with a higher backlight angle, which is consistent with the
experimental findings. As the backlight angle increased, the strength of the vortex generated
from the lateral edges of the backlight decreased on one side and increased on the other side,
leading to an asymmetrical flow. The hybrid CAA approach predicts the flow and noise
radiated from the half-round mirror in agreement with experiments and reveals increased noise
radiation with higher aspect ratios but reduced noise when the mirror is inclined towards the
mounting plate. Notably, the radiated noise from the half-round mirror exhibited a dipole-like
structure near the plate and a monopole-like structure away from it. This observation is
consistent for both variations introduced into the half-round mirror. For the full-scale vehicle
model, the absence of the A-pillar is identified as the primary contributor to overall noise
radiation. However, in the presence of a side-view mirror, the side window becomes a
significant contributor to noise. Additionally, when the mirror is inclined, a linear reduction in
the radiated noise is observed, although the vehicle's overall drag becomes nonlinear and highly
dependent on the flow behaviour past the mirror.
The proposed hybrid CAA approach provides valuable insights into noise prediction for ground
vehicles. By considering the impact of mirror inclination and geometric factors on noise
radiation, this research contributes to the development of quieter and more aerodynamically
efficient vehicles, thus fostering a comfortable and sustainable transportation environment
Standard Squareback models for Aerodynamics and Aeroacoustics Research
No full textThis data is a collection CAD of various forebody configurations of standard squareback models. All geometries have a standard mirror, the side window, frame; some include A-pillars. All models are identical in the projected frontal area
The role of forebody topology on aerodynamics and aeroacoustics characteristics of squareback vehicles using Computational Aeroacoustics (CAA)
Get PDFThis study investigates the influence of forebody configuration on aerodynamic noise generation and radiation in standard squareback vehicles, employing a hybrid computational aeroacoustics approach. Initially, a widely used standard squareback body is employed to establish grid-independent solutions and validate the applied methodology against previously published experimental data. Six distinct configurations are examined, consisting of three bodies with A-pillars and three without A-pillars. Throughout these configurations, the reference area, length, and height remain consistent, while systematic alterations to the forebody are implemented. The findings reveal that changes in the forebody design exert a substantial influence on both the overall aerodynamics and aeroacoustics performance of the vehicle. Notably, bodies without A-pillars exhibit a significant reduction in downforce compared to their A-pillar counterparts. For all configurations, the flow characteristics around the side-view mirror and the side window exhibit an asymmetrical horseshoe vortex with high-intensity pressure fluctuations, primarily within the confines of this vortex and the mirror wake. Side windows on bodies with A-pillars experience more pronounced pressure fluctuations, rendering these configurations distinctly impactful in terms of radiated noise. However, despite forebody-induced variations in pressure fluctuations impacting the side window and side-view mirror, the fundamental structure of the radiated noise remains relatively consistent. The noise pattern transitions from a cardioid-like shape to a monopole-like pattern as the probing distance from the vehicle increases
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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