1,721,877 research outputs found
The development of a mesh bioreactor for the anaerobic digestion of biodegradable municipal waste
No full textA laboratory scale prototype mesh bioreactor (MeBR) for the two-stage anaerobic digestion (AD) of biodegradable municipal waste (BMW) was successfully designed and tested. The development involved a number of preliminary stages; creation and characterization of a synthetic BMW (SBMW), exploration of its single-stage AD characteristics under both methanogenic and hydrolytic conditions, and AD trials of a two-stage reactor system where SBMW was fed to a 1st stage hydraulic flush (HF)reactor and centrifuging was used as a method to produce liquid effluent which was fed to a 2nd stage anaerobic filter (AF) reactor. The single stage digestion of SBMW suffered from process instability at very low organic loading rates (OLR) of 2-2.5 gVSl-1d-1 whilst the two-stage HF/AF system was robust up to a maximum OLR of 7.5gVS/ld. The HF reactors became methanogenic due to the effect of effluent recycling. After this, two different prototypes designs of MeBR were built and tested in continuous two-stage AD trials (AF 2nd stage). The aim was to replace the centrifuging of the HF reactors with continuous mesh filtration whilst maintaining the stable and robust digestion process. The first design confirmed the ability to filter SBMW digestate through nylon meshes of pore size 30-140 >m at an OLR of 3.75 gVSl-1d-1. The mesh system operated similarly to the HF/AF system and efficient two-stage AD of the SBMW was shown. Problems with stirring thick digestate limited the OLR on both the mesh and HF systems. To address this limitation on OLR, a 2nd MeBR was designed which employed a rotating drum for low effort mixing and 100 >m nylon mesh sections on the drum surface for filtration. This reactor system operated stably at an OLR of up to 15 gVSl-1d-1 albeit with reduced specific methane production. Application of this type of system will be dependant on requirements for high plant throughput, system robustness and a compact process to make up for slightly lower methane production and waste stabilisation compared to single stage digestion.<br/
Walker (Mark). German National Socialism and the Quest for Nuclear Power 1939-1949
No full textHelmreich Jonathan E. Walker (Mark). German National Socialism and the Quest for Nuclear Power 1939-1949. In: Revue belge de philologie et d'histoire, tome 70, fasc. 4, 1992. Histoire médiévale, moderne et contemporaine — Middeleeuwse, moderne en hedendaagse geschiedenis. pp. 1148-1149
Walker (Mark). German National Socialism and the Quest for Nuclear Power 1939-1949
No full textHelmreich Jonathan E. Walker (Mark). German National Socialism and the Quest for Nuclear Power 1939-1949. In: Revue belge de philologie et d'histoire, tome 70, fasc. 4, 1992. Histoire médiévale, moderne et contemporaine — Middeleeuwse, moderne en hedendaagse geschiedenis. pp. 1148-1149
Use of a hydraulic flush reactor in a single and two-stage anaerobic digestion process for biodegradable municipal waste
No full textPerformance of a hydrolysis reactor in which the solids and liquid retention times were uncoupled to give enhanced solids retention and removal of hydrolysis products was evaluated for a feedstock of biodegradable municipal waste (BMW). The reactor was operated both alone and as part of a two-stage process in series with an anaerobic filter. Operating with a hydraulic flush to give hydraulic retention times (HRT) between 1.6 and 5.3 days, and a solids retention time (SRT) of 20 days increased hydrolysis in comparison with a control reactor where HRT and SRT were equal. Overall biodegradability was low; however, with an effluent chemical oxygen demand (COD) equivalent to 30% of the substrate biochemical methane potential (BMP). When operated as part of a two-stage process using effluent from the anaerobic filter as the flush liquor the characteristics of the system changed substantially with an increase in performance to an overall methane production of 0.22–0.24L g?1 volatile solids (VS) added. This was achieved even when the maximum loading of 7.5gVS L?1day?1 was applied. During acclimatization the first-stage hydrolytic reactor became methanogenic despite the short HRT, and was responsible for as much as 70% of the overall methane production. The system could not revert to single-stage operation after acclimatization, showing the continuing importance of the anaerobic filter. The combined system was robust, and could recover from major disturbances and step increases in loading without reduction in continuous methane production, indicating some potential for larger scale application in BMW disposa
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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