1,720,979 research outputs found
Co-combustion of coal and tire residue in a pilot plant: A simplified modeling approach for scale-up predictionsof char oxidation
No full textExperimental and modeling investigations have been performed on the co-combustion of a traditional fossil fuel and a tire residue. The experimental runs have been carried out using a pilot-scale vertical furnace (0.5 MW) with a burner for pulverized solid fuels. Different conditions have been set up for the co-combustion of a medium volatile bituminous coal and a tire residue. The scope was to test the feasibility of burning secondary fuels (biomasses and residues) with coals using a low NOx burner developed for pulverized coal in the ENEL Research Centre. A co-combustion model was developed for interpreting the results and extrapolating kinetic parameters to practical conditions. It considers the effect of the particle size distribution, the different reactivity, and, in general, the different combustion behavior of each fuel fed to the furnace. The kinetic scheme adopted is simple and the introduced assumptions allow easy coupling with computational reactive fluid dynamic codes. Fuel conversion, oxygen concentration and carbon-in-ash profiles have been computed and compared with the experimental results. Quite good agreement has been obtained, allowing kinetic information to be used in more comprehensive descriptions of full-scale systems
Single and combined deactivating effect of alkali metals and HCl on commercial SCR catalysts.
No full textAnalysis of syngas reburn technology for industrial boilers with advanced chemical engineering models
No full textThe outcome of an integrated methodology for analysis of combustion processes applied to technical feasibility of controlling NOx emissions and unburned carbon in ash from industrial scale plants was presented. The modeling methodology was based on an integrated use of furnace probing measurements coupled with different simulation tools: CFD code (IPSE) for 3D simulation of combustion chambers, PROATES for the convection pass, and Chemical Engineering Models (RNA) for pollutant emissions and burnout predictions. The solid phase included heterogeneous NO reduction by char and heterogeneous char oxidation with a detailed population balance (800 size burnout classes) keeping track of size, density change and burnout. As working case, to better explain the potentiality offered by this analytical approach, a study addressed to evaluate the best firing configuration for a tangentially-fired utility boiler supplied with pulverized coal by employing synthesis gas (syngas) as secondary fuel is presented. The case studied was chosen as increasing attention to the use of renewable and sustainable energy resources has led to consider, as near term option, the possibility of co-firing syngas (i.e. synthetic gas produced by gasification of biomass or waste) with coal in the existing large-scale pulverized coal power plants. This is an abstract of a paper presented at the 30th International Symposium on Combustion (Chicago, IL 7/25-30/2004)
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
False recalls, but not false recognitions, at the DRM paradigm are increased in subjects reporting insomnia symptoms: An online study
No full textBackground: In insomnia, poor sleep is accompanied by several cognitive impairments affecting prefrontal functioning that could affect source-monitoring processes and contribute to false memories production. By using a modified version of the Deese-Roediger-McDermott paradigm (DRM), we previously found that individuals suffering from insomnia produced more false memories than good sleepers adopting a free-recall task, especially for sleep-related stimuli. However, whether poor sleep affects false memory production in a task-dependent manner (i.e., free recall or recognition) remains unclear. Methods: Through an online research method, we adopted the classical DRM paradigm to investigate the production of false recalls and false recognitions in 32 subjects referring insomnia symptoms (IN group) and 37 good sleepers (GS group), addressing also executive functioning and source monitoring ability in both groups. Results: Compared to the GS group, the IN group produced more false memories (p = .002) and intrusions (p = .004) at the free recall task and showed a lower working memory index (p = .008). No between-groups differences emerged at the recognition task. Correlational analysis revealed significant associations between DRM performance, executive functioning and source monitoring (SM) variables. Moreover, false recalls were predicted by being in the presence of insomnia symptoms (p = .012) and intrusions by the number of correct responses to the Stroop task (p = .051) and SM task (p = .015), as well as by the presence of insomnia symptoms (p = .003). Conclusions: Our data show that the presence of insomnia symptoms can influence false memories production. Furthermore, the evidence that free recall is more affected than recognition suggests that poor sleep mainly affects performance at more cognitively demanding tasks. Finally, correlational and regression analyses support the hypothesis of a link between false memories production and both the presence of insomnia symptoms and executive functioning impairments
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