1,720,954 research outputs found
Modeling of wet jet in fluidized bed
No full textA wet jet zone is established in many applications wherever feeding and dispersing a liquid, solution or slurry into fluidized bed by gases is needed. In the present study, a simple mathematical model has been developed to simulate the wet jet in fluidized bed. The different stages involved inside the jet zone have been estimated and analyzed.
The evaporation stage of traveling droplets through the jet flare has been treated. The rates of evaporation of each size at all positions along the jet flare have been estimated according to the velocities and surrounding conditions. The final droplet sizes have been determined. Moreover, the total evaporation rate from traveling droplets, before collision either with entrained sand particles or flare boundaries, has been estimated. The traveling droplets, partially evaporated, may collide and settle on entrained sand particles. The model predicts the settlement rates of liquid droplets on entrained sand particles. The total part evaporated from settled liquid has been estimated as well.
The study has been applied to the pneumatic feeding of liquid fuel into fluidized bed combustors operating at 850 oC. The model has been utilized to predict the ratio of fuel vapor that releases inside the jet flare. The remaining part is assumed to evaporate inside the emulsion phase. Three different liquid fuels have been considered: a heavy oil, diesel fuel and gasoline. The main independent variables are those related to the injection conditions including the initial velocity of dispersing air, uo, and air to liquid mass ratio, ALR.
The model results demonstrate that only very small droplets completely evaporate inside the flare. The liquid settling over the entrained sand particles plays an essential role in the fuel evaporation inside the flare. The phenomenon is dominant at conditions that result in generation of droplets of larger sizes, i.e., heavier fuel, lower uo, and greater ALR. The ratio of vapor fuel released in jet flare increases with lighter fuel, higher uo and lower ALR. At uo=200 m/s and ALR=1.0 nearly all-liquid fuel evaporates inside the flare
Design and setup activities for the development of methane autothermal reforming in a jet fountain fluidized bed reactor
No full textIn the framework of hydrogen production and process intensification for energy applications, this work presents the design and the construction of a novel lab-scale experimental facility, which is aimed at testing and demonstrating the feasibility of the auto-thermal catalytic reforming of methane in a recently proposed reactor configuration, i.e., the jetting fountain fluidized bed (JFFBR). The proposed solution consists of a jet pipe and an annulus which are concentrical and it is designed to operate the auto-thermal reforming in two almost-distinct zones: oxidant (oxygen or air) is only fed to the jet pipe, which substantially provides methane partial oxidation and consequently heat generation; the annulus is designed to operate in a bubbling fluidized bed regime, and it is the region in which methane steam reforming essentially occurs. The two zones communicate through a pair of holes in the bottom part of the jet pipe, which determine the entrainment of solid particles and the fountain on the top of the jet pipe. The jetting fountain fluidized bed regime is expected to enhance the heat and mass transfer phenomena, while the selective fed of the oxidant to the jet pipe is expected to provide an in-situ regeneration of the catalyst. In view of starting an actual experimental program with the designed facility, a suitable catalyst has been selected and its catalytic activity has been characterized in a lab-scale fixed-bed reactor. The formulation, previously optimized, involves a ceria-silica support, which can be easily fluidized, and two active phases, namely Ni and Pt, obtaining a final catalyst 3%Pt-10%Ni/CeO2/SiO2.The catalyst performed well in terms of activity and selectivity. The activity test results from the fixed-bed reactor allowed to set-up a satisfactory kinetic model of the reacting system
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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