1,720,957 research outputs found
Optimal design and discharge operation of lithium-ion whole-cell
No full textThe optimal design of Li-ion whole-cells is presented for different discharge operating constraints: constant current (CC), constant power (CP), and constant resistance (CR). In addition, a new Optimal Theoretical Operation Policy (OTOP) is derived resorting to Variational Calculation. When applied to cell discharge, this policy relates equilibrium voltage, applied current, and discharge time. The considered design variables comprise electrode thicknesses, porosity volume fractions, total solid volume fractions, and cell mass. The objective of the optimal design formulation is to maximize the total specific energy delivered for a set of given discharge time values with the aim of relating delivered energy to delivered power. The simultaneous optimization of multiple design variables under different operating conditions is efficiently achieved by using a simple phenomenological mathematical model that predicts the main aspects of these systems. The importance of this procedure is reflected in remarkable improvements to total specific energy delivered. The optimized whole-cell designs gained average improvements of more than 40%, depending on time discharge, when compared to the initial design taken from the literature; and when the optimal designs obtained under the different operating conditions are compared, an additional specific energy is obtained (OTOP results in the best operating condition, followed by CR, CC, and CP, with average differences of 7, 8, and 15%, respectively).Fil: Aimo, Corina Eva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; ArgentinaFil: Henquín, Eduardo Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química; ArgentinaFil: Aguirre, Pio Antonio. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; Argentin
Lithium-ion whole-cell design and charging protocol optimization within safe operating conditions
No full textThe main phenomena of battery degradation occur during the charge and, unlike the discharge, this process can be predefined and controlled. In this paper, the optimization of different charging protocols is proposed, considering three different objectives: charging time minimization, charge capacity maximization and consumed energy minimization. These optimization problems are subject to security constraints that define a feasible region, which offers protection against the main cell degradation phenomena. The study is posed by applying a phenomenological cell model in a mathematical programming environment. In addition, the whole-cell design optimization is presented within this framework and an analysis of internal energy losses is performed, allowing a holistic understanding of the system performance and the influence of each of its variables during the charging process. Therefore, the proposed approach allows the simultaneous optimization of the multiple design and operation variables. The characteristic variables for a particular chemistry and a given cell design are obtained: minimum full charge time, optimal constant charge current and the current and voltage values at the end of charge. Furthermore, an expression of an optimal theoretical charging protocol is obtained through the minimization of the consumed energy. Simulation results show considerable improvements in the objectives, such as a reduction of 30% in the total charging time for the traditional CC-CV protocol when multiple cell design variables are optimized.Fil: Aimo, Corina Eva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; ArgentinaFil: Aguirre, Pio Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; Argentin
Multi-objective optimization of a lithium cell design operating in a cyclic process
No full textMulti-objective optimization frameworks of lithium-ion whole-cell design operating in a cyclic process are presented in this paper. The objective functions involved are maximization of capacity, maximization of specific energy in discharge and maximization of cycle energy efficiency. The considered design variables are electrode thicknesses, solid volume fraction and porosity of electrode compartments, and cell mass per unit cross-sectional area. In addition, the constant current value of charge and discharge is optimized. A phenomenological mathematical model developed in GAMS (General Algebraic Modeling System) environment is applied to achieve the stated goals and the multi-objective problems are solved using an epsilon constraint method-based, which is effective for finding solutions in non-convex feasible regions. Solutions for two different cell chemistries are analyzed: LMO and LCO. Pareto curves and surfaces are obtained and sets of solutions with the highest contradictions and with the most balanced agreement between the objectives involved are identified. When comparing optimal LMO designs with optimal LCO designs, the former result on average 48 % less capacity, 19 % less specific energy and 31 % more energy efficiency. Results show that material type-dependent variables such as active solids have a strong influence on the specific energy and cycle energy efficiency. While the electrode thicknesses show a general trend regardless of the type of chemistry, presenting a strong influence on cell capacity values.Fil: Aimo, Corina Eva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; Argentina. Universidad Nacional de Rafaela; ArgentinaFil: Schmidhalter, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; ArgentinaFil: Aguirre, Pio Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; Argentin
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
- …
