1,721,344 research outputs found
Applications of jet–jet/film impingement for atomization enhancement
Full text linkThis mini-review mainly focuses on the fundamental problem of jet–jet/film impingement exhibiting superior fragmentation and atomization characteristics compared to single-jet injection; this has been widely used in agricultural irrigation and combustion propulsion systems. First, it presents the main controlling parameters and spray characteristic for both jet–jet and jet–film configurations, analyzes the breakup mechanisms, and points out the coupling between jet fragmentation processes and collision-induced or externally imposed vorticity fields. Then, the atomization enhancement of jet–jet or jet–film impingement is explained from the aspects of vortex generation, evolution, identification, and the interactions between vorticity fields and spray fields. Finally, representative applications of jet–jet/film impingement in agricultural engineering and aerospace engineering are introduced so as to achieve spatially uniform spray distribution and efficient fuel/oxidizer mixing characteristics. Future advancements require breakthroughs in cross-scale vortex–ligament interaction diagnostics and intelligent control of variable-viscosity fluids to promote deep implementation of this technology in clean energy systems
Morphological variations of in-flame and exhaust soot particles associated with jet-to-jet variations and jet–jet interactions in a light-duty diesel engine
Full text linkThe variations in soot particle morphology due to jet-to-jet variations and jet–jet interactions have been investigated in a single-cylinder, optically accessible light-duty diesel engine by conducting thermophoretic particle sampling and subsequent transmission electron microscope (TEM) imaging of both in-flame and exhaust soot particles. To this end, the soot sampling experiments were conducted for three different jet configurations including two single-jets (Jet A and Jet B) and a double-jet (Jet A&B) with the latter being investigated at both fixed total fuel mass and fixed injection duration conditions. The results show that the differences in the jet development with respect to the wall cause variations in the soot structures and sizes of aggregates and primary particles in both the in-flame and exhaust samples. However, the jet-to-jet variations are relatively minor compared to the significant impact of jet–jet interactions on soot particles. It is found that the low jet–jet interaction at fixed fuel mass conditions leads to negligible amounts of sampled soot particles; however, the high jet–jet interaction at fixed injection duration conditions causes the increased number of soot particles compared with the single-jet cases, suggesting higher soot formation in the jet–jet interaction region. Both the soot aggregate and primary particle sizes of the double-jet with the fixed injection duration are lower than those of the single-jets, implying that the soot particles in the jet–jet interaction region are in the earlier stage of soot formation. The same trend is observed in the exhaust samples, albeit the differences are much less. It is likely due to the progression in soot formation/oxidation occurring inside the cylinder of the engine before the particles exit through the exhaust. Compared to marked variations in the soot particle sizes, the fractal dimension is largely unchanged due either to jet-to-jet variations or jet–jet interactions in both in-flame and exhaust soot particles
Z? ? bb? signal extraction from QCD continuum background using jet-jet mass
No full textWe report results on the extraction of the Z? ? bb? signal from the jet-jet mass spectrum for Run 1b, using monte carlo studies along with maximum likelihood fit techniques
Morphology and internal structure of soot particles under the influence of jet–swirl and jet–jet interactions in a diesel combustion environment
Full text linkA new multi-location soot sampling method is used to enhance the knowledge about the structural evolution of in-flame particles in a light-duty optical diesel engine. Through thermophoresis-based particle sampling performed at multiple in-bowl locations, the soot structures are shown for both early formation stage and later stage from the same combustion event. Three different jet-spacing angles of 45°, 90° and 180° were studied to analyse how different levels of jet–jet interaction impact the soot particle morphology and internal structure. One selected jet–jet interaction condition was further analysed to show differences in soot structures between the up-swirl side and down-swirl side of the wall jets. From transmission electron microscopes (TEM) images of the sampled soot particles and their statistical size analysis, it was found soot particles initially formed within 45∘ separated jet–jet interaction region have un-solidified premature aggregates due to limited carbonisation in the locally fuel-rich mixtures. When these soot particles travelled on the down-swirl side of the jets, they became solidified and carbonised while the oxidation was evident from the smaller soot primary particle and longer carbon-layer fringe and lower tortuosity. The higher mixing on the up-swirl side of the jets further enhanced the soot oxidation, resulting in even smaller soot primary particle, fragmentation of large soot aggregates, and even longer and less curved carbon-layer fringes. Regarding jet–jet interaction, the 180° jet spacing angle created no jet–jet interaction condition on the soot sampler locations. For smaller jet-spacing angles, the increase in jet–jet interaction promoted the soot formation as evidenced by larger and more complex soot aggregates formed due to more active soot aggregation and agglomeration. The soot oxidation became limited at higher jet–jet interaction conditions, which led to more amorphous soot internal structures
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
Boson-jet and jet-jet azimuthal correlations at high transverse momenta
No full textWe discuss our recent results on azimuthal distributions in vector boson + jets and multi-jet production at the LHC, obtained from the matching of next-to-leading order (NLO) perturbative matrix elements with transverse momentum dependent (TMD) parton branching. We present a comparative analysis of boson-jet and jet-jet correlations in the back-to-back region, and a study of the theoretical systematic uncertainties associated with the matching scale in the cases of TMD and collinear parton showers
Boson-jet and jet-jet azimuthal correlations at high transverse momenta
No full textAbstract: We discuss our recent results on azimuthal distributions in vector boson + jets and multi-jet production at the LHC, obtained from the matching of next-to-leading order (NLO) perturbative matrix elements with transverse momentum dependent (TMD) parton branching. We present a comparative analysis of boson-jet and jet-jet correlations in the back to-back region, and a study of the theoretical systematic uncertainties associated with the matching scale in the cases of TMD and collinear parton showers
- …
