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In-cylinder sampling of high molecular weight hydrocarbons from a D.I. light duty diesel engine
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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
Formation of soot and polycyclic aromatic hydrocarbons in a direct injection diesel engine
No full textMass spectrometric analysis of large PAH in a fuel-rich ethylene flame
No full textMass spectrometric analysis by laser desorption-time of flight-mass spectrometry (LDI-TOF-MS) was exploited to extend the detection of flame-formed polycyclic aromatic hydrocarbons (PAH) up to the mass limit of the first soot particles (> 2000 Da) in the soot formation region of a premixed fuel-rich (C/O = 1) ethylene flame. The typical decreasing intensity of PAH ion peaks with increasing mass was found in the mass range m/z 500-1700 although a slight enrichment in the heavier part of PAH could be observed to occur along the flame axis. The separation by means of size exclusion chromatography (SEC) into two different classes of PAH followed by UV-visible spectroscopy corroborated the mass spectral identification of large mass PAH. Critical examination of mass spectral features and SEC separation was the starting point for speculation about the changes occurring in PAH growth from planar to concave structures which could be important for soot inception mechanisms
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
Precursor formation and soot inception in premixed ethylene flames
No full textAbsorption, fluorescence and scattering measurements were applied both in the ultraviolet and visible to rich premixed C2H4/O2 flames in the C/O range from 0.5 to 0.8. The concentration of soot and condensed hydrocarbon species were also measured by direct sampling along a lightly-sooting (C/O=0.65) and sooting (C/O=0.75) flame. The early formation in the flames of "particles" with typical average size around 2 nm (2500 a.m.u.), which do not absorb in the visible and fluoresce in the ultraviolet, was followed. These "transparent" particles were considered soot precursors on the basis of their decreasing concentration profile in correspondence of soot inception, as evaluated by both optical and chemical measurements. The soot inception process is characterized by the progressive aromatization of the "transparent" particles as shown by the progressive shift toward the visible of absorption and fluorescence. The internal rearrangement of a partially aromatic polymeric structure, more than a progressive formation of very large PAH structures, is proposed as the mechanism of soot inception. © 1992 Combustion Institute
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