Phase-field modeling of the influence of mechanical stresses on charging and discharging processes in lithium ion batteries

A promising cathodic material for lithium ion batteries is lithium manganese oxide. However, over battery cycling, this material shows capacity fade. This behavior may be induced by mechanical failure of the particles whose granular cathode consists of. This further indicates the occurrence of very large stresses in particles. By means of a phase-field model coupled to mechanics we have computed the stresses arising in these particles

Ensayo PROCTOR con MATHEMATICA

Se presenta una aproximación numérica para la determinación de la “Densidad Seca Máxima”, y la “Humedad Optima” de la compactación de suelos que se obtiene con el Ensayo Proctor, a partir de datos experimentales (S/Norma de Ensayo VN-E5-93 de la Dirección Nacional de Vialidad). Esta presentación se hace en la Cátedra Caminos II de la Facultad de Ingeniería (UNLP), como experiencia didáctica dentro de una perspectiva interdisciplinaria integradora con conceptos y métodos del Cálculo Numérico y Estudio de Suelos de Uso Vial. El mismo tiene por objeto reforzar e integrar los conocimientos alcanzados por los alumnos en Cálculo Numérico con los conceptos y métodos usados en Caminos II, utilizando el software Mathematica para la resolución de algoritmos y representación gráfica.Red de Universidades con Carreras en Informática (RedUNCI

Phase-field simulation and discrete element modeling of the interaction of diffusion and mechanics in electrode particles and electrodes of lithium ion batteries

In active electrode materials of litium ion batteries, there exists a coupling beween the field of lithium concentration on the one hand and mechanical strain on the other. When lithium ions are inserted in the electrode particles, this may cause significant stresses, which may lead to particle failure. For individual particles, we study the interaction of diffusion and mechanical stresses in cathode particles by means of a phase-field model employing the Cahn–Hilliard equation. Although the porous structure of electrodes allows for the improvement of cell power due to shortened diffusion paths in the solid phase for lithium ions, it constitutes issues with respect to the transport of electrons. In the second part of this discussion, the effective conductivity of the porous electrode is described by a resistor network method, coupled to DEM to account for the interaction with mechanical loadings

Aproximación de funciones por polinomios de Taylor en un intervalo cerrado

Un caso de aproximación de funciones se presenta cuando la función se da de manera explícita, y se quiere encontrar un tipo más simple, por ejemplo un polinomio, que nos sirva para determinar los valores aproximados de ella. En este trabajo se investiga como buscar el punto x0 del polinomio de Taylor de grado n fijo, para obtener la mejor aproximación de una función en un intervalo cerrado [a, b]. El algoritmo planteado está desarrollado con un programa interactivo usando el Mathematica, software producido por Wolfram Research, Inc. Con este programa puede repetirse el algoritmo para diferentes funciones o para otros valores de n, grado del polinomio de Taylor, para comparar los distintos resultados. Pueden probarse otros ejemplos entrando al sitio que se preparo para ofrecer a los interesados: http://www.inf.unisinos.br/~goedert/ Con este trabajo se propone realizar aportes en la generación y diseño de recursos didácticos que sirvan para el desarrollo de aptitudes y actitudes que favorezcan la adaptación del alumno a ámbitos de trabajo distintos en la enseñanza del Cálculo y del Cálculo Numérico. Dentro de este marco se profundiza en la utilización de nuevas tecnologías computacionales y de Internet.Eje: III - Workshop de tecnología informática aplicada en educaciónRed de Universidades con Carreras en Informática (RedUNCI

Aproximación de funciones por polinomios de Taylor en un intervalo cerrado

Un caso de aproximación de funciones se presenta cuando la función se da de manera explícita, y se quiere encontrar un tipo más simple, por ejemplo un polinomio, que nos sirva para determinar los valores aproximados de ella. En este trabajo se investiga como buscar el punto x0 del polinomio de Taylor de grado n fijo, para obtener la mejor aproximación de una función en un intervalo cerrado [a, b]. El algoritmo planteado está desarrollado con un programa interactivo usando el Mathematica, software producido por Wolfram Research, Inc. Con este programa puede repetirse el algoritmo para diferentes funciones o para otros valores de n, grado del polinomio de Taylor, para comparar los distintos resultados. Pueden probarse otros ejemplos entrando al sitio que se preparo para ofrecer a los interesados: http://www.inf.unisinos.br/~goedert/ Con este trabajo se propone realizar aportes en la generación y diseño de recursos didácticos que sirvan para el desarrollo de aptitudes y actitudes que favorezcan la adaptación del alumno a ámbitos de trabajo distintos en la enseñanza del Cálculo y del Cálculo Numérico. Dentro de este marco se profundiza en la utilización de nuevas tecnologías computacionales y de Internet.Eje: III - Workshop de tecnología informática aplicada en educaciónRed de Universidades con Carreras en Informática (RedUNCI

All you need to know about the tricuspid valve: Tricuspid valve imaging and tricuspid regurgitation analysis

SummaryThe acknowledgment of tricuspid regurgitation (TR) as a stand-alone and progressive entity, worsening the prognosis of patients whatever its aetiology, has led to renewed interest in the tricuspid-right ventricular complex. The tricuspid valve (TV) is a complex, dynamic and changing structure. As the TV is not easy to analyse, three-dimensional imaging, cardiac magnetic resonance imaging and computed tomography scans may add to two-dimensional transthoracic and transoesophageal echocardiographic data in the analysis of TR. Not only the severity of TR, but also its mechanisms, the mode of leaflet coaptation, the degree of tricuspid annulus enlargement and tenting, and the haemodynamic consequences for right atrial and right ventricular morphology and function have to be taken into account. TR is functional and is a satellite of left-sided heart disease and/or elevated pulmonary artery pressure most of the time; a particular form is characterized by TR worsening after left-sided valve surgery, which has been shown to impair patient prognosis. A better description of TV anatomy and function by multimodality imaging should help with the appropriate selection of patients who will benefit from either surgical TV repair/replacement or a percutaneous procedure for TR, especially among patients who are to undergo or have undergone primary left-sided valvular surgery

q-exponential, Weibull, and q-Weibull distributions: an empirical analysis

In a comparative study, the q-exponential and Weibull distributions are employed to investigate frequency distributions of basketball baskets, cyclone victims, brand-name drugs by retail sales, and highway length. In order to analyze the intermediate cases, a distribution, the q-Weibull one, which interpolates the q-exponential and Weibull ones, is introduced. It is verified that the basketball baskets distribution is well described by a q-exponential, whereas the cyclone victims and brand-name drugs by retail sales ones are better adjusted by a Weibull distribution. On the other hand, for highway length the q-exponential and Weibull distributions do not give satisfactory adjustment, being necessary to employ the q-Weibull distribution. Furthermore, the introduction of this interpolating distribution gives an illumination from the point of view of the stretched exponential against inverse power law (q-exponential with q > 1) controversy.Comment: 6 pages, Latex. To appear in Physica

Echocardiographic diastolic function evolution in patients with an anterior Q-wave myocardial infarction: insights from the REVE-2 study.

International audienceBackground: Myocardial fibrosis plays a key role in the development of adverse left ventricular remodeling after myocardial infarction (MI). This study aimed to determine whether the circulating levels of BNP, collagen peptides, and galectin-3 are associated with diastolic function evolution (both deterioration and improvement) at 1-year after an anterior MI.Methods: The REVE-2 is a prospective multicenter study including 246 patients with a first anterior Q-wave MI. Echocardiographic assessment was performed at hospital discharge and ±1-year after MI. BNP, Galectin-3 and collagen peptides were measured ±1-month after MI. Left ventricular diastolic dysfunction (DD) was defined according to the presence of at least 2 criteria of echocardiographic parameters: septal e’6 mg/l (Odds Ratio, OR=5.29; 95%CI=1.05-26.66; p=0.044), Galectin-3>13 μg/l (OR=5.99; 95%CI=1.18-30.45; p=0.031), and BNP>82 ng/l (OR=10.25; 95%CI=2.36-44.50; p=0.002) quantified at 1-month post-MI were independently associated with 1-year DD. Follow-up of the 137 patients with DD at baseline among the 159 patients showed that 36 patients (26%) had a normalized diastolic function at 1-year post-MI. Patients with a BNP>82 ng/l were less likely to improve diastolic function (OR=0.06; 95%CI=0.01-0.28; p=0.0003).Conclusions. The present study suggests that circulating levels of PIIINP, Galectin-3 and BNP may be independently associated with new-onset DD in post-MI patients