1,720,969 research outputs found
Influence of the digested cod concentration on the alkalinity requirement in anaerobic digesters
No full textpH value and stability in anaerobic digesters are governed by the carbonic system. An expression is derived to determine the alkalinity requirement for maintaining a desired pH value in an anaerobic digester. The requirement is calculated from stoichiometric relationships and depends on measurable parameters of the influent (notably concentration of digestible material, influent VFA, alkalinity, acidity and organic nitrogen concentration) and operational conditions (temperature, recycle of effluent and/or biogas). The derived expression is applied to three cases of anaerobic digestion: dilute waste water (sewage), concentrated waste water (vinasse) and sludge. In each case it was calculated if the influent alkalinity was sufficient to maintain an adequate pH for digestion and when it was not, what was the alkalinity requirement to maintain the desired pH value. The calculated values of pH and alkalinity demand compared well with experimental data.</jats:p
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Improved performance and increased applicability of waste stabilisation ponds by pretreatment in a UASB reactor
No full textTraditionally waste stabilisation ponds (WSPs) are built as flow-through systems with an anaerobic, a facultative and one or more maturation ponds in series. The anaerobic pond can be substituted with great advantage by an upflow anaerobic sludge blanket (UASB) reactor. The practical advantages are that the required volume for the UASB reactor is much smaller than the anaerobic pond (20 to 30 times) and that the biogas in the UASB reactor is captured, so that odour problems can be eliminated. The UASB reactor is neighbour friendly and can be used in densely populated areas.
The UASB reactor is more efficient than the anaerobic pond, so that the residual organic load is small and the subsequent pond configuration can be designed with the specific purpose of eliminating pathogens. By adopting a plug flow regime, the required area for a particular hygienic effluent quality can be greatly reduced. Also, since the UASB effluent has good transparency, photosynthesis in the ponds is intense and pH increases due to biological carbon dioxide consumption, accelerating the death rate of pathogens and opening the possibility of reducing nutrients: Nitrogen by desorption of gaseous NH3 and phosphorus by phosphate precipitation.
The fact that an odour free system with a high quality effluent can be produced in relatively small system composed by a UASB reactor + maturation ponds, increases the applicability of this system for sewage treatment in urban areas. As operation of both UASB and ponds is very simple, several small treatment plants instead of one large central unit may be constructed. Thus a very significant of the sewerage network may be achieved.</jats:p
Profitability Increase of Alcohol Distilleries by the Rational Use of Byproducts
No full textIndustrial alcohol production in Brazil is based on fermentation of sugar cane juice. After centrifugation and distillation, azeotropic alcohol is obtained along with four side streams: (1) bagasse, the solid part of the cane plant, (2) yeast, grown during the fermentation, (3) carbon dioxide released during the fermentation and (4) waste water called vinasse composed of the bottom fraction of the distillation and wash waters. The profitability of alcohol distilleries can be improved by a more rational use of the side stream products. The solid products have a diversified application potential. By applying anaerobic digestion to vinasse, methane can be produced at a proportion of 100 kgCH4 per m3 of produced alcohol. Full scale application has shown anaerobic digestion to be technically and economically feasible and the digested waste water can be used for irrigation, whereas the produced solids can be applied as soil conditioners.
An alternative for improved energy production is to abandon alcohol fermentation and apply anaerobic digestion directly to the vegetal energy source. In that case the useful energy production is much higher and can be obtained using much simpler equipment. More importantly, the source for energy production would no longer be restricted to cane: Other crops, notably those produced in the drier hinterland of North East Brazil (cassava, sweet potatoes), could also be used for this purpose.</jats:p
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Qualidade tecnológica da pluma do algodoeiro herbáceo cultivado com biossólidos.
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Previous issue date: 2007-02-2
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