1,720,954 research outputs found
Mathematical modelling of the formation and evolution of surface ice
Get PDFDuring the fall season in cold regions when the air temperature drops below freezing levels, it removes heat from the water surface and creates a supercooled surface layer. In weak turbulent flows, the supercooled surface layer initiates the formation of ice particles on the water surface, which could evolve into various types of surface ice runs. In this paper a mathematical model of the formation and evolution of surface ice is presented. A heat balance model at the water surface is applied to calculate the heat loss from the water. The turbulent kinetic energy and the energy dissipation rates are modelled to find the eddy viscosity that affects the mixing rate. The mathematical model is then calibrated and verified using experimental data collected at the Hydraulics Research and Testing Laboratory at the University of Manitoba. The model simulates the supercooling process reasonably well for all surface ice conditions.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
A Theoretical and Experimental Study of the Evolution of Surface Ice
No full textThe theory of the formation of surface ice is not fully understood, yet its presence on water
surface affects the operation of many different kinds of hydraulic structures. It is known that
when the water surface temperature reaches supercooling ice particles are formed at the water
surface. If the intensity of turbulence is low these ice particles will be suspended on the
surface forming a surface ice. Herein, an experimental study that incorporates the effect of
depth, velocity, roughness and air temperature is carried out in a counter-rotating flume to
investigate the formation of surface ice in relation to these parameters. The experimental
result is supported by a mathematical model based on the theory of formation of surface ice.
A mathematical model is developed based on a comprehensive theory and is solved using
Matlab. The mathematical model integrates the effect of the heat balance on the water surface
with the degree of turbulent mixing and the rate of growth of surface ice. The two calibrating
parameters for the model are the magnitude of the initial seeding and the surface heat loss
coefficient. The developed mathematical model is calibrated for the different types of surface
ice formations for the data obtained from the experiment.
The experimental analysis shows that there are four main types of surface ice formations and
their formation is mainly dependent on the degree of turbulence. It is also found that the
types of these ice formations are dependent on the minimum supercooling temperature at an
average depth. Moreover, it is demonstrated that skim ice particles are those ice particles that
nucleate on the water surface during low to medium turbulent intensities and can have four
different types of shapes, namely needle shapes, finger shapes, hexagonal shapes and
irregular shapes. The sizes and relative quantities of these ice particles on the water surface
are also dependent on the degree of turbulence.May 200
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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