1,720,995 research outputs found
Quantitative investigation of the influence of electrode morphology in the electro-chemo-mechanical response of li-ion batteries
Full text linkLithium ion batteries are promising energy storage devices for next generation electric and hybrid vehicles. To achieve high performances and overcome electrochemical deficiencies, significant effort has been made in novel electrode designs and materials. Structural features, such as the morphology of the electrodes, are crucial aspects, too. In this study, we investigate numerically the influence of electrodes architecture, in terms of the electro-chemo-mechanical response of a battery cell with homogeneous electrodes and conventional liquid electrolyte. Simulations predict a suitable design of the electrodes, which leads to major increments of the battery efficiency
Review - Electrolyte and Electrode Designs for Enhanced Ion Transport Properties to Enable High Performance Lithium Batteries
No full textLithium-ion batteries (LiBs) are recognized as the most rapidly growing energy storage technology. To improve the energy and power density of LiBs, tremendous progress has been made in every battery component. In this review, we focus on the investigations of electrolyte and electrode designs aimed at understanding and enhancing ion transport properties to improve the performance of LiBs. Theoretical, computational, and experimental studies of the importance of transport properties are highlighted, and the efforts to enhance the lithium transference number in organic electrolytes is discussed. We also review the significant ion transport challenges in porous electrodes and the demonstrated examples of advanced, high power/energy density electrodes. Overall, we focus on the most recent and pioneering works in terms of complex electrolytes with high transport properties and thick porous electrodes for high performance LiBs. This review intends to provide guidance for development of advanced electrolytes and electrodes for high performance LiBs through comprehensive compilation of prior understanding via experimental, computational, and theoretical points of view
Shallow groundwater nitrogen and denitrification in a newly afforested, subirrigated riparian buffer
No full text1. The EU ‘Nitrates Directive’ (Directive 91⁄ 676 ⁄EEC) and the WFD (Water Framework Direc-
tive 2000⁄ 60⁄EEC) introduced a series of measures designed to reduce and prevent water pollution
caused or induced by nitrates from agricultural sources. Therefore, there is an urgent requirement
to control the nitrate concentration in freshwater. The objective of this paper was to verify the
potential capacity of a specifically designed afforested riparian zone in removing the excess of nitro-
gen from river water.
2. A buffer zone was set with irrigation ditches, to produce a subsurface water flow carrying water
from the study river through the buffer strip to drainage ditches. This experimental system enables
the co-occurrence of two main processes: vegetation⁄microbial nitrogen uptake and denitrification.
Both in situ denitrification and denitrification potential were measured at different soil depths, and
nitrogen removal of water passing through the buffer system was measured.
3. After the first year, high removal rates (63–64%) of total nitrogen in water were recorded. The
lowest rate of denitrification took place in the upper soil layer, while maximum denitrification
occurred in the medium layer (40–55 cm). Denitrification occurred mainly in the first few metres of
the irrigation ditches leading away from the river. The denitrification rates clearly increased from
the second to the third year, with highest rates in summer and autumn. Denitrification potential
indicated that carbon availability was the most limiting factor.
4. Synthesis and applications. This study has demonstrated that nitrogen levels can be reduced in
rivers by forcing water to circulate through afforested buffers. Nitrogen was removed both by plants
and by microbial denitrification. Such activity can be supported by promoting anoxic conditions
through appropriate water flow management. This could be achieved by creating semi-natural
floodplains where water flows can be efficiently managed as in a drained wetland
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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