1,721,268 research outputs found
Static mixers: Effective means for intensifying mass transfer limited reactions
No full textThe potential of using screen-type static mixers to intensify mass transfer limited multiphase-reactions was investigated using a case of diesel desulfurization. Two reactor designs were assessed at different superficial velocities and operating temperatures. By focusing energy dissipation within a very narrow distance in the regions adjacent to the screen, it was possible to generate local energy dissipation rates as high as 40,000. W-kg while maintaining the specific energy consumption rates below 0.2. kWh-t of liquid processed. Depending on the operating temperature, up to 15,400-fold reduction in the residence time needed to react 95percent of the sulfur present in the diesel can be achieved by replacing a standard mixing tank agitated by a Rushton-type impeller with a screen-type static mixer. About 97percent of this can be credited to the higher inter-phase mass transfer achievable in screen-type static mixers, while the remaining 3percent can be attributed to the higher average mass transfer driving force encountered under the plug flow conditions prevalent in this contactor. The relatively uniform flow conditions encountered across the pipe diameter minimized the formation of difficult-to-separate liquid-liquid dispersions with the ensuing dispersion separating within 20 s. © 2013 Elsevier B.V.AlTaweel AM, 1996, CHEM ENG RES DES, V74, P445; Al Taweel A.M., 2007, T I CHEM ENG-LOND, V85, P1; Al Taweel A.M., 1984, P 12 AUSTR CHEM ENG, V1, P487; ALTAWEEL AM, 1983, CAN J CHEM ENG, V61, P527; Al Taweel AM, 2005, CHEM ENG SCI, V60, P6378, DOI 10.1016-j.ces.2005.03.011; Azizi F, 2011, CHEM ENG COMMUN, V198, P726, DOI 10.1080-00986445.2011.532748; Azizi F, 2012, CHEM ENG J, V179, P231, DOI 10.1016-j.cej.2011.10.063; Azizi F, 2007, CHEM ENG SCI, V62, P7436, DOI 10.1016-j.ces.2007.08.083; Azizi F., 2011, 8 EUR C CHEM ENG BER; Baldyga J, 1997, CHEM ENG SCI, V52, P457, DOI 10.1016-S0009-2509(96)00430-7; Baum JS, 1998, OIL GAS J, V96, P49; Bayer T, 2005, CHEM ENG TECHNOL, V28, P285, DOI 10.1002-ceat.200407121; Behrend O, 2001, ULTRASON SONOCHEM, V8, P271, DOI 10.1016-S1350-4177(01)00088-8; Campos-Martin JM, 2010, J CHEM TECHNOL BIOT, V85, P879, DOI 10.1002-jctb.2371; Duarte FA, 2011, FUEL, V90, P2158, DOI 10.1016-j.fuel.2011.01.030; El-Ali M.S., 2001, THESIS DALHOUSIE U H; Henschke M, 1999, AICHE J, V45, P2079, DOI 10.1002-aic.690451006; KOGLIN B, 1981, CHEM-ING-TECH, V53, P641, DOI 10.1002-cite.330530813; KRISHNA R, 1994, CHEM ENG SCI, V49, P4029; Laddha G. S., 1976, TRANSPORT PHENOMENA; Lu YP, 1997, CHEM ENG SCI, V52, P1349, DOI 10.1016-S0009-2509(96)00491-5; Maass S, 2010, CHEM ENG J, V162, P792, DOI 10.1016-j.cej.2010.06.007; Mann U, 2000, CHEM ENG SCI, V55, P991, DOI 10.1016-S0009-2509(99)00364-4; Manninen M., 2006, 2340 VTT; Mei H, 2003, FUEL, V82, P405, DOI 10.1016-S0016-2361(02)00318-6; Middleton J., 2007, 21 NAMF M PARK CIT U; Pennemann H, 2005, CHEM ENG TECHNOL, V28, P501, DOI 10.1002-ceat.200407144; Rang H, 2006, OIL SHALE, V23, P164; Sharipov AK, 2005, PETROL CHEM+, V45, P371; Shelat M.R., 2004, AICHE ANN M AUST TX; Srivastava P, 2000, BIOTECHNOL BIOENG, V70, P525, DOI 10.1002-1097-0290(20001205)70:55250
Inter-phase mass transfer in turbulent liquid-liquid dispersions: A comparative analysis of models
No full textA comparative evaluation of eight models used to predict the dispersed phase mass transfer coefficient was undertaken using recent drop size and mass transfer data obtained under well known and controlled hydrodynamic conditions encountered in screen-type static mixers. A wide range of experimental conditions were covered (e[open]= 1.5-117. W-kg, φ= 0.1-0.47) thereby allowing for proper assessment of the strength and weaknesses of each model. All models failed to properly predict the experimental results over a wide range of design and operating conditions with the exception of those that contain a system-specific adjustable fitting parameter. Although these models yielded reasonably acceptable order-of-magnitude predictions, they could not accurately account for the variations in the different parameters investigated. This shows that proper understanding of the various factors affecting the dispersed phase mass transfer coefficient is still incomplete and highlights the need for phenomenological models that can account for the various physicochemical and hydrodynamic conditions on the dispersed-phase mass transfer coefficient. © 2011 Elsevier B.V.AlTaweel AM, 1996, CHEM ENG RES DES, V74, P445; Al Taweel A.M., 1984, 12 AUSTR CHEM ENG C, V1, P487; Al Taweel AM, 2007, CHEM ENG RES DES, V85, P760, DOI 10.1205-cherd06180; Alves SS, 2004, CHEM ENG PROCESS, V43, P823, DOI 10.1016-S0255-2701(03)00100-4; Andersson R, 2004, CHEM ENG SCI, V59, P4911, DOI 10.1016-j.ces.2004.07.084; Asghar D. Molaei, 2002, AICHE J, V48, P2230; Azizi F, 2011, CHEM ENG COMMUN, V198, P726, DOI 10.1080-00986445.2011.532748; Azizi F, 2011, CHEM ENG J, V166, P715, DOI 10.1016-j.cej.2010.11.050; Azizi F., 2005, RELIABLE DESIGN IND; Bart HJ, 2003, CHEM ENG TECHNOL, V26, P723, DOI 10.1002-ceat.200306102; Botello-Alvarez E.J., 2004, IND ENG CHEM RES, V43, P6527; Bouaifi M, 2001, CHEM ENG PROCESS, V40, P97, DOI 10.1016-S0255-2701(00)00129-X; BOURNE JR, 1991, CHEM ENG J BIOCH ENG, V47, P155, DOI 10.1016-0300-9467(91)85021-M; Briassulis G, 2001, J FLUID MECH, V432, P219; CAMURDAN MC, 1989, CAN J CHEM ENG, V67, P554; COULALOGLOU CA, 1977, CHEM ENG SCI, V32, P1289, DOI 10.1016-0009-2509(77)85023-9; Ebrahimi SSS, 2009, J CHEM ENG JPN, V42, P10; HANDLOS AE, 1957, AICHE J, V3, P127, DOI 10.1002-aic.690030121; Henschke M, 1999, AICHE J, V45, P2079, DOI 10.1002-aic.690451006; HSIA MA, 1980, CHEM ENG J BIOCH ENG, V20, P225, DOI 10.1016-0300-9467(80)80007-4; JOHNSON AI, 1960, AICHE J, V6, P145, DOI 10.1002-aic.690060128; Kang HS, 2003, J FLUID MECH, V480, P129, DOI 10.1007-S0022112002003579; KRONIG R, 1950, APPL SCI RES, V2, P142; Kumar A, 1999, CHEM ENG RES DES, V77, P372, DOI 10.1205-026387699526359; Laakkonen M, 2006, CHEM ENG SCI, V61, P218, DOI 10.1016-j.ces.2004.11.066; Maass S, 2012, CHEM ENG SCI, V70, P146, DOI 10.1016-j.ces.2011.08.027; Newman AB, 1931, T AM INST CHEM ENG, V27, P310; Noh H.S., 1984, AICHE J, V30, P120; Paul E. L., 2004, HDB IND MIXING SCI P; Rahbar A, 2011, CAN J CHEM ENG, V89, P508, DOI 10.1002-cjce.20448; RIBEIRO LM, 1995, COMPUT CHEM ENG, V19, P333, DOI 10.1016-0098-1354(94)00054-R; Schmidt SA, 2006, CHEM ENG SCI, V61, P246, DOI 10.1016-j.ces.2005.02.075; Skelland P.A.H., 1981, AICHE J, V27, P99; SLATER MJ, 1988, CHEM ENG SCI, V43, P233, DOI 10.1016-0009-2509(88)85036-X; SLATER MJ, 1995, CAN J CHEM ENG, V73, P462; STEINER L, 1986, CHEM ENG SCI, V41, P1979, DOI 10.1016-0009-2509(86)87114-7; Vasquez V., 1997, MINER PROCESS EXTR M, V17, P239, DOI 10.1080-08827509708914150; Venneker BCH, 2002, AICHE J, V48, P673, DOI 10.1002-aic.690480404; Yadav RL, 2008, CHEM ENG J, V138, P389, DOI 10.1016-j.cej.2007.06.015; YOUNG CH, 1989, CHEM ENG SCI, V44, P2355, DOI 10.1016-0009-2509(89)85168-122
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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