1,720,988 research outputs found
Flow Reactor Oxidation of Ammonia–Hydrogen Fuel Mixtures
Full text linkHydrogen-assisted oxidation of ammonia under flow reactor conditions was investigated through experiments and chemical kinetic modeling. Novel experiments, conducted in a tubular laminar flow reactor as a function of the NH3/H-2 ratio, stoichiometry, and temperature (725-1475 K), were analyzed along with literature results from tubular and jet-stirred flow reactors. Ignition and oxidation of NH3 is strongly promoted by the presence of H-2 under all conditions investigated. In general, the behavior is captured well by the kinetic model. With an increasing fraction of H-2 in the fuel mixture, the generation of chain carriers gradually shifts from being controlled by the amine reaction subset to being dominated by the oxidation chemistry of H-2, which is known more accurately. However, under reducing conditions, the H-2 consumption rate is strongly underpredicted. This shortcoming suggests that the thermochemistry of amine radicals and/or the formation of higher amines need further assessment. The present analysis shows that for lean oxidation of NH3/H-2 mixtures in tubular flow reactors, data obtained at higher temperatures, particularly for NO formation, may be strongly affected by the reaction during preheating or by mixing (dependent on reactor design) in the inlet section prior to the isothermal zone. Modeling predictions for the high pressure, medium-temperature ignition conditions in a large diesel engine indicate that NH3/H-2 fuel mixtures may still require a cofuel to secure stable ignition
Experimental study of the combustion properties of methane/hydrogen mixtures
Full text linkIn this thesis the combustion properties of methane / hydrogen mixtures are investigated by measering autoignition delay times in methane/hydrogen mixtures under conditions relevant for gasengines. Moreover HCN and C2H2 measurements have been performed in fuel-rich one dimensional laminar CH4/H2/air flames. All measurements have been compared with numerical calculations.
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
Experimental study of the combustion properties of methane/hydrogen mixtures
Full text linkIn this thesis the combustion properties of methane / hydrogen mixtures are investigated by measering autoignition delay times in methane/hydrogen mixtures under conditions relevant for gasengines. Moreover HCN and C2H2 measurements have been performed in fuel-rich one dimensional laminar CH4/H2/air flames. All measurements have been compared with numerical calculations
Experimental study of the combustion properties of methane/hydrogen mixtures
No full textIn this thesis the combustion properties of methane / hydrogen mixtures are investigated by measering autoignition delay times in methane/hydrogen mixtures under conditions relevant for gasengines. Moreover HCN and C2H2 measurements have been performed in fuel-rich one dimensional laminar CH4/H2/air flames. All measurements have been compared with numerical calculations
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
Experimental study of the combustion properties of methane/hydrogen mixtures
Full text linkIn this thesis the combustion properties of methane / hydrogen mixtures are investigated by measering autoignition delay times in methane/hydrogen mixtures under conditions relevant for gasengines. Moreover HCN and C2H2 measurements have been performed in fuel-rich one dimensional laminar CH4/H2/air flames. All measurements have been compared with numerical calculations
Experimental study of the combustion properties of methane/hydrogen mixtures
Full text linkIn this thesis the combustion properties of methane / hydrogen mixtures are investigated by measering autoignition delay times in methane/hydrogen mixtures under conditions relevant for gasengines. Moreover HCN and C2H2 measurements have been performed in fuel-rich one dimensional laminar CH4/H2/air flames. All measurements have been compared with numerical calculations
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