1,720,980 research outputs found
Modelling of Electrodialysis units by a multi-scale process simulator
Full text linkDrinking water production by desalination is an interesting alternative to face water scarcity issues. Electrodialysis (ED) is an electro-membrane process that is actually gaining attention as a competitive alternative for seawater and brackish water desalination due to recent developments in manufacturing of high performance ion exchange membranes (IEMs). In this context, a suitable process simulator can be a very effective tool in order to drive the design of optimized ED systems.
In this work a novel mathematical model of ED units was developed by a hierarchical simulation strategy of separation of scales, in order to address the full simulation problem. The model was implemented in PSE gPROMS Modelbuilder. In the lower-hierarchy model, transport phenomena of salt and water were simulated within the whole cell pair of an electrodialyser. Then, the higher-hierarchy model describes the behaviour of the stack. The model is based on mass balance equations and phenomenological expressions of fluxes that describe transport phenomena along channels and across IEMs. In addition, Kirchhoff’s law together with the Nernst’s law for the non-Ohmic voltage drop was used to determine the electrical behaviour of the equivalent circuit. Finally, the model makes use of CFD correlations from a lower scale as input data in order to predict the effect of concentration polarization and the contribution of pumping to the energy consumption.
Co-current, counter-current and crossflow configurations were simulated, by obtaining the distribution of current density/voltage and concentration along the channels. Finally, total resistance, total power consumption and specific energy consumption were computed. Several simulations were carried out by changing the operating conditions and the stack features. Simulation results showed a good agreement with experimental findings as obtained from the literature, demonstrating that the model is able to adequately capture the phenomenological description of the ED process
Electrodialysis with capacitive electrodes (CED): hierarchical process modelling for water desalination
No full textThe present work describes the development of the first dynamic model for CE
Dynamic modelling of electrodialysis with bipolar membranes unit using NARX recurrent neural networks
Full text linkElectrodialysis with bipolar membranes (EDBM) is an innovative and effective process
for the simultaneous production of acid and base solutions from salty streams. It has been
proven to play a key role in several circular economy approaches to valorize waste
industrial brines, but it can also be used for in situ generation of chemicals, especially in
remote areas. The adoption of such technology at industrial scale requires reliable
modelling tools capable of predicting both dynamic and stationary operations as process
conditions vary, such as energy supplied to the system and the target concentration of
chemicals. In this study, nonlinear autoregressive models with exogenous inputs (NARX)
were applied for the first time to EDBM to predict the behaviour of this complex and nonlinear process. Thus, an effective and low computational demanding neural-based
modelling tool was developed. As a preliminary step, the network was trained with three
different datasets, generated by a fully validated model. The best architecture was chosen
to give good performance, testing the network with a new dataset. The NARX network
accurately predicts the different behaviour of EDBM outputs (i.e. voltage and solutions
conductivities) showing low average discrepancies between predicted and true values
(lower than 0.5 %). These results suggest the possibility of using neural network-based
models to effectively optimize and control EDBM process. Next step will focus on the
training and validation of a network obtained with a set of data from a real EDBM plant
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
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