1,720,958 research outputs found
Particle dispersion produced by a turbulent free convection flow in a room-sized cubical cavity
Full text linkNumerical simulations of particle turbulent dispersion and deposition with implications for the spreading of airborne diseases
Full text linkAquesta tesi doctoral examina la dinàmica de partícules en fluxos turbulents mitjançant simulacions numèriques, enfocant-se en dos escenaris clau: els fluxos generats per l'exhalació i els impulsats per flotabilitat en espais tancats. Inicialment, s'avaluen diferents mètodes numèrics per predir la dispersió de partícules en tos suau, destacant que les simulacions totalment resoltes superen els models Unsteady Reynolds Averaged Navier-Stokes en la captura de la dispersió vertical.
Posteriorment, s'examina la dispersió de partícules després d'exhalació mitjançant el "Reto de Dinámica de Fluidos Computacional Internacional de 2022". Es detecta una subestimació constant en la mescla vertical, particularment en models basats en equacions de Navier-Stokes no estacionàries.
L'estudi es centra també en la fase post-exhalació, explorant la dinàmica de partícules patògenes en corrents d'aire de fons. A més, s'investiga el transport d'aerosols en fluxos turbulents en espais tancats, revelant una distribució homogènia de partícules amb el temps.
Finalment, es considera la dispersió i deposició de partícules sòlides en suspensió en una caixa cúbica amb parets escalfades, correlacionant resultats amb experiments i solucions analítiques. Aquesta recerca destaca la importància de la modelització precisa en la resposta a emergències i la reducció de la transmissió de malalties per l'aire, contribuint a la comprensió d'aquests fenòmens crítics mitjançant comparacions amb dades experimentals i models teòrics.Esta tesis doctoral aborda el movimiento de partículas en flujos turbulentos mediante simulaciones numéricas en dos contextos clave: flujos de partículas generados por la exhalación y flujos turbulentos en espacios cerrados impulsados por flotación.
Primero, se evalúan diferentes enfoques numéricos para predecir la dispersión de partículas durante la tos inicial. Se encuentra que el modelo de Navier-Stokes no estacionario con un modelo de turbulencia k-epsilon captura aspectos importantes pero subestima la dispersión vertical en comparación con simulaciones más detalladas.
Luego, se participa en el "Desafío Internacional de Dinámica de Fluidos Computacionales de Eventos de Exhalación Violenta de 2022" para evaluar modelos de dispersión de partículas post-exhalación. Se detecta una subestimación constante de la mezcla vertical en modelos basados en Navier-Stokes no estacionarios.
La investigación explora la dinámica de partículas y patógenos en corrientes de aire posteriores a la turbulencia. También investiga el transporte de aerosoles en flujos turbulentos en espacios cerrados, observando una distribución uniforme de partículas de diferentes tamaños con el tiempo.
Además, se examina la dispersión y deposición de partículas en una caja cúbica con paredes calentadas de manera diferencial, relacionando los resultados con experimentos y soluciones analíticas, aportando valiosos conocimientos sobre la transferencia de calor y la deposición de partículas.
En resumen, este estudio integral de la dinámica de partículas resalta la importancia de la modelización precisa en la respuesta a emergencias y la reducción de la transmisión de enfermedades transmitidas por el aire.This doctoral thesis thoroughly investigates particle movement in turbulent flows through numerical simulations. It focuses on two scenarios: particle-laden jet flows triggered by expiratory events and buoyancy-driven turbulent flows in enclosed spaces.
The research begins by evaluating numerical methodologies for predicting particle dispersion during the initial phase of a cough. The Unsteady Reynolds Averaged Navier-Stokes model captures essential features but underestimates vertical dispersion compared to fully resolved simulations.
Participation in the "2022 International Computational Fluid Dynamics Challenge on Violent Expiratory Events" reveals consistent underestimation of vertical mixing in various models, particularly in Unsteady Reynolds Averaged Navier-Stokes.
The study also examines the second stage of expiratory events, where pathogen-particle dynamics depend on background air currents after turbulent energy dissipation. Additionally, it explores aerosol transport in buoyancy-driven turbulent flows within enclosed spaces, showing homogeneous particle distribution over time.
The work extends to dispersion and deposition of airborne solid particles in a cubical cavity with differentially heated walls, offering valuable insights into heat transfer and particle deposition.
In summary, this research contributes to our understanding of particle dispersion and deposition dynamics, vital for emergency response and mitigating airborne disease transmission, by comparing simulations with experimental data and theoretical models
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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