1,721,713 research outputs found
On the understanding of a cryogenic two phase LOX/GH2 flame: Parametric sensitivity, characteristic scaling and phase instability
No full textThis study concerns the cryogenic hydrogen combustion in subcritical pressure conditions, with practical relevance to rocket engine applications. A cryogenic two phase flame in the counterflow configuration is calculated and analyzed with the consideration of real fluid effects and heat/mass transfer across the liquid gas interface. The effects of pressure, strain rate, fuel inlet temperature, and heat loss on the flame characteristic behaviors are examined. It is found that the vaporization rate of liquid oxidizer scales with the square root of pressure (p) times strain rate (ast), and is not a limiting factor for combustion. The total heat release scales withffiffiffiffiffiffiffiffip at lower strain rates while with p4=5a1=3 past st at higher strain rates. The significant results on the phase stability of cryogenic flame are also established. It is found that the unstable phase, in terms of vapor liquid equilibrium, arises in the vi cinity of the liquid gas interface; however, all unstable phase states still stay in the metastable region of the phase diagram. For all the flame solutions considered in this study, no thermochemical state enters the spinodal region.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.</p
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
Development and validation of a combustion large-eddy-simulation solver based on fully compressible formulation and tabulated chemistry
No full textThis study concerns the development and validation of a high-fidelity CFD solver for large-eddy simulations (LES) of combustion and reacting flows. The solver is built upon a high-resolution numerical scheme and leverages a compressible flamelet formulation, so that it can capture both the turbulent combustion and thermoacoustic effects simultaneously. The validation study is first performed by considering a scalar-mixing case in homogeneous turbulence, and then extended to LES of a non-premixed jet flame. The solver accuracy is assessed by comparing the numerical solutions with the available experimental data. It is found that the newly developed solver is able to accurately predict the time-averaged combustion fields as well as the fluctuation quantities. The predictive accuracy is comparable to that of the state-of-the-art low-Mach solvers in literature. (C) 2022 Elsevier Masson SAS. All rights reserved.</p
A novel reduced-order model method for characterization of acoustic response of laminar premixed flames
No full textThis study presents a general, predictive and cost-efficient reduced-order modeling (ROM) technique for characterization of laminar premixed flame response under acoustic modulation. The model is built upon the kinematic flame model-G-equation to describe the flame topology and dynamics, and the novelties of the ROM lie in i) a procedure to create the compatible base flow that can reproduce the correct flame geometry and i i ) the use of a physically-consistent acoustic modulation field for the characterization of flame response. This ROM addresses the significant limitations of the classical kinematic model, which is only applicable to simple flame configurations and relies on ad-hoc models for the modulation field. The ROM is validated by considering the acoustically-excited laminar premixed methane/air flames in conical and M-shape configurations, experimentally study by Durox et al. Proc. Combust. Inst. , 32 (2009). To test the model availability to practical burners, a confined flame configuration Cuquel et al., Proc. Combust. Inst. , 34 (2013) is also employed for model evaluation. The model accuracy is evaluated concerning flame geometrical features and flame describing function, and assessed by comparing the ROM results with both the experimental measurements and the direct-numerical-simulation results. It is found that the flame describing/transfer functions predicted by the ROM compare well with reference data, and are more accurate than those obtained from the conventional kinematic model built upon heuristically-presumed modulation fields. & COPY; 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.</p
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
Acumulación/eliminación de oxitetraciclina en el camarón blanco, lv y su residualidad en dietas artificiales
No full textAcumulación/eliminación de oxitetraciclina en el camarón blanco, LV y su residualidad en dietas artificialesAcumulación/eliminación de oxitetraciclina en el camarón blanco, LV y su residualidad en dietas artificiale
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