1,720,957 research outputs found
Computational modeling of UV-initiated advanced oxidation processes in a cross-flow photoreactor
No full textA computational fluid dynamics (CFD) modeling study of different advanced oxidation processes (AOPs) in a UV photoreactor with a cross-flow lamp arrangement is presented in this paper. In particular, the verification and validation of three different AOP-CFD models: UV185, UV254+H2O2, and UV185+UV254+H2O2, developed in a Eulerian framework, is introduced and discussed. The AOP model was developed by coupling a comprehensive kinetic model with advanced optical models and detailed hydraulics. Oxalic acid (OXA) was chosen as model pollutant for the assessment of the AOP performance. Results revealed that the efficacy of the UV185/UV254/H2O2 process, at laminar flowrates, is superior to the other treatment processes in terms of oxalic acid degradation
Modeling virus transport and inactivation in a fluoropolymer tube UV photoreactor using Computational Fluid Dynamics
No full textFluoropolymer tube photoreactors employing external UV lamps to irradiate the fluid conveyed by semitransparent tubes are currently used for water and wastewater applications based on their intrinsic simplicity in system assembly and claims that the hydrophobic characteristics of the tube material reduce fouling. Nonetheless, there is limited published information to date on the short and long term disinfection efficiency and the potential implications of these factors for operational costs. In this paper, empirical and numerical bioassay experiments on virus inactivation were conducted on a pilot-scale fluoropolymer tube photoreactor using MS2 and T1 bacteriophages to gain further insight into delivered dose. Simulated and observed MS2 and T1 reduction equivalent doses displayed good agreement with an error (relative to the observed RED) ranging from -13.7% to +4.4% for MS2 (average =-3.9%) and from -5.6% to +27.0% for T1 (average = +4.6%).The impact of the fluoropolymer UV absorption on disinfection was also assessed. Integrating sphere measurements revealed that absorption events occurring in the fluoropolymer tubes play a pivotal role in determining disinfection efficiency. At 253.7 nm, the diffuse transmission of UV light was the dominant radiative transfer mechanism and a considerable proportion of incident photon flux (13.5%) was absorbed by the fluoropolymer tube. As highlighted by the model sensitivity analysis, the fluoropolymer absorption coefficient was found to be the most important factor affecting bacteriophage inactivation. Although further research will be conducted to investigate potential efficiency enhancements attainable through shape optimization and internal UV reflectors, CFD predictions indicated that the current electrical efficiency of the investigated photoreactor (0.0190-0.0289kWhm-3 MS2log-1) was considerably higher than conventional UV photoreactors (0.0044-0.0049kWhm-3 MS2log-1) suggesting that fluoropolymer tube UV technologies may not be ideal for high-flow installations or energy sensitive application
Nondeterministic computational fluid dynamics modeling of Escherichia coli nactivation by peracetic acid in municipal wastewater contact tanks
No full textWastewater disinfection processes are typically designed according to heuristics derived from batch experiments in which the interaction among wastewater quality, reactor hydraulics, and inactivation kinetics is often neglected. In this paper, a computational fluid dynamics (CFD) study was conducted in a nondeterministic (ND) modeling framework to predict the Escherichia coli inactivation by peracetic acid (PAA) in municipal contact tanks fed by secondary settled wastewater effluent. The extent and variability associated with the observed inactivation kinetics were both satisfactorily predicted by the stochastic inactivation model at a 95% confidence level. Moreover, it was found that (a) the process variability induced by reactor hydraulics is negligible when compared to the one caused by inactivation kinetics, (b) the PAA dose required for meeting regulations is dictated equally by the fixed limit of the microbial concentration as well as its probability of occurrence, and (c) neglecting the probability of occurrence during process sizing could lead to an underestimation of the PAA dose required by as much as 100%. Finally, the ND-CFD model was used to generate sizing information in the form of probabilistic disinfection curves relating E. coli inactivation and probability of occurrence with the average PAA dose and PAA residual concentration at the outlet of the contact tank
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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