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Dive into the research topics where Manuel Cruz is active.

Publication


Featured researches published by Manuel Cruz.


Journal of The Electrochemical Society | 2005

Oxygen Deficiency as the Origin of the Disparate Behavior of LiM0.5Mn1.5 O 4 ( M = Ni , Cu ) Nanospinels in Lithium Cells

Álvaro Caballero; Manuel Cruz; L. Hernán; M. Melero; J. Morales; E. Rodríguez Castellón

A comparative study of the electrochemical properties of two spinels of nominal composition LiM 0 . 5 Mn 1 . 5 O 4 (M = Ni, Cu) was conducted. The doping element introduces significant structural changes in stoichiometry, cation distribution, and oxidation state of the elements. Whereas Ni spinels were virtually stoichiometric and exhibit mostly normal structure, the Cu samples were oxygen-deficient spinels with a greater contribution of the inverse structure. This was especially so in the sample obtained at 800°C, where X-ray photoelectron spectroscopy (XPS) revealed the presence of Cu + . Its electron configuration favored the occupancy of tetrahedral positions and the resulting displacement of some Li + ions to octahedral positions. All these features account for the increased Mn 3 + content of the Cu spinels, consistent with electrochemical measurements. Ex situ XPS measurements confirmed the oxidation processes of Ni and Cu ions on charging the cell at 5.0 V, and the reversibility of the electrochemical reaction undergone by Ni. However, the reversibility of the Cu 2 + ⇄ Cu 3 + reaction could not be demonstrated because of the low capacity delivered by the cell in the 5.0-4.5 V region. The structural defects in the Cu spinels have an adverse impact on cell performance. Compared to the Ni spinel, the Cu spinel possesses a low discharge capacity that fades faster on cycling.


Electrochemical and Solid State Letters | 2004

Nanostructured Lead Dioxide Thin Electrode

J. Morales; G. Petkova; Manuel Cruz; Álvaro Caballero

Nanostructured PbO2 obtained by hydrolysis of Pb(CH3COO)4 is shown to exhibit an excellent electrochemical activity as a thin electrode in lead-acid cells. This material was characterized by X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and Brunauer-Teller-Emmett measurements. The electrode was prepared by spray deposition of the nanostructured PbO2 material and showed high utilization ~about 65% of the theoretical capacity! and good cycling stability at discharge current of 1 C. It is suggested that the nanostructure is the key factor for the enhanced electrochemical activity of lead dioxide.


hybrid artificial intelligence systems | 2009

Memetic Pareto Differential Evolution for Designing Artificial Neural Networks in Multiclassification Problems Using Cross-Entropy Versus Sensitivity

Juan Carlos Fernández; César Hervás; Francisco José Martínez; Pedro Antonio Gutiérrez; Manuel Cruz

This work proposes a Multiobjective Differential Evolution algorithm based on dominance Pareto concept for multiclassification problems using multilayer perceptron neural network models. The algorithm include a local search procedure and optimizes two conflicting objectives of multiclassifiers, a high correct classification rate and a high classification rate for each class, of which the latter is not usually optimized in classification. Once the Pareto front is built, we use two automatic selection methodologies of individuals: the best model with respect to accuracy and the best model with respect to sensitivity (extremes in the Pareto front). These strategies are applied to solve six classification benchmark problems obtained from the UCI repository. The models obtained show a high accuracy and a high classification rate for each class.


intelligent systems design and applications | 2009

Design of Artificial Neural Networks Using a Memetic Pareto Evolutionary Algorithm Using as Objectives Entropy versus Variation Coefficient

Juan Carlos Fernández; César Hervás; F.J. Martínez; Manuel Cruz

This paper proposes a multi-classification pattern algorithm using multilayer perceptron neural network models which try to boost two conflicting main objectives of a classifier, a high correct classification rate and a high classification rate for each class. To solve this machine learning problem, we consider a Memetic Pareto Evolutionary approach based on the NSGA2 algorithm (MPENSGA2), where we defined two objectives for determining the goodness of a classifier: the cross-entropy error function and the variation coefficient of its sensitivities, because both measures are continuous functions, making the convergence more robust. Once the Pareto front is built, we use an automatic selection methodology of individuals: the best model in accuracy (upper extreme in the Pareto front). This methodology is applied to solve six benchmark classification problems, obtaining promising results and achieving a high classification rate in the generalization set with an acceptable level of accuracy for each class.


Advanced Functional Materials | 2006

Crystallinity control of a nanostructured LiNi0.5Mn1.5O4 spinel via polymer-assisted synthesis : A method for improving its rate capability and performance in 5 V lithium batteries

José Carlos Arrebola; Álvaro Caballero; Manuel Cruz; L. Hernán; J. Morales; Enrique Rodríguez Castellón


Journal of Power Sources | 2006

Synthesis and characterization of lead dioxide active material for lead-acid batteries

J. Morales; G. Petkova; Manuel Cruz; Álvaro Caballero


Journal of Power Sources | 2007

Electrochemical properties of electrodeposited nicked phosphide thin films in lithium cells

Manuel Cruz; J. Morales; L. Sánchez; Jesús Santos-Peña; F. Martín


Journal of Power Sources | 2005

Nanocrystalline materials obtained by using a simple, rapid method for rechargeable lithium batteries

Álvaro Caballero; Manuel Cruz; L. Hernán; Monserrat Melero; J. Morales; Enrique Rodríguez Castellón


Journal of Power Sources | 2002

Spray pyrolysis as a method for preparing PbO coatings amenable to use in lead-acid batteries

Manuel Cruz; L. Hernán; J. Morales; L. Sánchez


Electrochimica Acta | 2014

Improving the electrochemical properties of nanosized LiFePO4-based electrode by boron doping

Rafael Trócoli; Sylvain Franger; Manuel Cruz; J. Morales; Jesús Santos-Peña

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G. Petkova

Bulgarian Academy of Sciences

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Jesús Santos-Peña

François Rabelais University

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S.G. Real

National University of La Plata

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