1,720,963 research outputs found
A new method of modelling tuneable lasers with functional composition
Full text linkA new nonlinear model is proposed for tuneable lasers. Using the generalized nonlinear Schrodinger equation as a starting point, expressions for the transformations undergone by the pulse are derived for each of the five components (gain, loss, dispersion,
modulation, and nonlinearity) within the laser cavity. These transformations are then composed to give the overall effect of one trip around the cavity. We first examine the linearized version of the model which is solved analytically. Then the full nonlinear model is solved numerically. A consequence of the nonlinear nature of this model is that it is able to exhibit wave breaking which prior models could not.
We highlight the rich structure of the boundary of stability for a particular plane of the parameter space.University of Ontario Institute of Technolog
Modelling chemical and transfer processes in a silicon carbide reactor
Full text linkTraditional refining of silicon generates carbon dioxide emissions that are released into the atmosphere. An alternative pathway under experimental exploration processes quartz and carbon into silicon carbide. We present mathematical models for the chemical and transfer processes within a silicon carbide reactor. We consider both a single pellet model and multiphase model. We then optimize the the multiphase model for silicon~yield.
We first examine a quartz particle coated in a layer of porous carbon as the raw material. We derive governing equations for the key chemical species silicon monoxide, carbon monoxide, and carbon dioxide, along with conservation laws on the surface of the quartz. We reduce our model to an industrially relevant distinguished limit and identify two distinct behaviours: reaction-limited and diffusion-limited. We find that the diffusion-limited regime obtains higher silicon yield and carbon utilization.
We then develop a multiphase model for a homogenous bed of quartz and carbon particles in a laboratory-scale crucible. We model the phases of carbon, silicon carbide, quartz, and the gas mixture. We also consider the motion of the solid, and model the gas flow with Darcy's law. Both analytical and numerical methods are employed to explore the effects of the dimensionless parameters on system behaviour. The dependence of silicon yield, carbon utilization, and maximum pressure on dimensionless parameters is understood through parameter sweeps. We find that a high silicon yield is primarily achieved by balancing the relative speed of the reactions, while maintaining a safe gas pressure requires balancing the ratio of transport to reaction speed.
Finally, we focus on optimizing the multiphase model to maximize silicon yield while maintaining safe pressures. We further examine the parameter space around the optimum point with parameter sweeps and sensitivity analysis. We find that maximizing the speed of the silicon carbide reaction most significantly contributes to a high silicon yield. We then explore the effect of dimensional parameters, such as the initial bed height, on the maximum silicon yield achievable within an industrially relevant timeframe
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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