Uribe-Godinez J.,CINVESTAV |
Hernandez-Castellanos R.,Technological University of Mexico |
Journal of Power Sources | Year: 2010
The electrocatalytic activity for oxygen reduction and hydrogen oxidation of a discrete metal carbonyl cluster with a well defined molecular and crystal structure, Rh6(CO)16, is reported. The exchange current density of this compound for oxygen reduction is one order of magnitude higher than that of platinum, and its resistance degree to PEM fuel cell contaminants such as methanol and CO is as high as 2 mol L-1 and 0.5%, respectively. These properties make the metal complex a potential alternative for use as electrode in polymer electrolyte membrane fuel cells. © 2010 Elsevier B.V.
Arenas M.C.,National Autonomous University of Mexico |
Andablo E.,Technological University of Mexico |
Castano V.M.,National Autonomous University of Mexico
Journal of Nanoscience and Nanotechnology | Year: 2010
Conducting polyaniline nanofibers (nf-PANI) were successfully synthesized by simple polymerization of aniline in presence of single and binary dopant agents. Strong hydrochloride acid (HCI), two weak organic acids (poly acrylic acid, PAA, 2-acrylamido-2-methyl-1-propanesulfonic acid, AMPSA) and one anionic surfactant (sodium dodecyl sulfate, SDS) were used to form the binary dopant agents. The binary dopant agent PAA modified the morphology of the single doped PANI, whereas AMPSA and SDS modified the dimensions of the nanofibers: The length size single nanofibers is reduced 1.72 times with binary-doped AMPSA and increased by a factor of 0.7 with SDS. The surface roughness of the films decreases when the dimensions of the nanofibers increase: PANI-SDS film is flatter than PANI-AMPSA film. In general, the conductivity of the single-doped PANI nanofibers (nf-PANI-HCI) was improved by one order of magnitude with binary dopant agents (HCI-PAA, HCI-AMPSA, HCI-SDS). The influence of the binary dopant agents in the nf-PANI-HCI properties is analyzed by Transmission Electron Microscope (TEM), Atomic Force Microscopy (AFM), UV-VIS absorption spectra, thermogravimetric analysis (TGA) and Fourier-Transform infrared spectra (FT-IR). Copyright © 2010 American Scientific Publishers. All rights reserved.
Paredes-Sanchez J.P.,University of Oviedo |
Villicana-Ortiz E.,Technological University of Mexico |
Xiberta-Bernat J.,University of Oviedo
Journal of Cleaner Production | Year: 2015
The location of mining areas is subject to the availability of resources and the capability to extract them. As these areas are usually isolated or of difficult access they lack any means of electric infrastructure as its installation can be rather costly. Therefore the use of local energy resources, such as solar energy, becomes relevant for the mine energy supply. This study carries out a solar pumping project in a slate mine in Galicia (Spain) related to automatic control systems in surface water management affected by waste from the extractive activity and thus abiding with environmental legislation. © 2014 Elsevier Ltd. All rights reserved.
Ramirez J.M.,CINVESTAV |
Gonzalez J.M.,Technological University of Mexico |
Ruben T.O.,Tulancingo Polytechnic University
International Journal of Electrical Power and Energy Systems | Year: 2011
With the advent of new technology based on power electronics, power systems may attain better voltage profile. This implies the proposition of careful strategies to dispatch reactive power in order to take advantage of all reactive sources, depending on size, location, and availability. This paper proposes an optimal reactive power dispatch strategy taking care of the steady state voltage stability implications. Two power systems of the open publications are studied. Power flow analysis has been carried out, which are the initial conditions for Transient Stability (TS), Small Disturbance (SD), and Continuation Power Flow (CPF) studies. Steady state voltage stability analysis is used to verify the impact of the optimization strategy. To demonstrate the proposal, PV curves, eigenvalue analyses, and time domain simulations, are utilized. © 2010 Elsevier Inc. All rights reserved.
Sierra-Canto X.,Technological University of Mexico |
Madera-Ramirez F.,Autonomous University of Yucatán |
Uc-Cetina V.,Autonomous University of Yucatán
Proceedings - 9th International Conference on Machine Learning and Applications, ICMLA 2010 | Year: 2010
The Artificial Neural Networks (ANN) training represents a time-consuming process in machine learning systems. In this work we provide an implementation of the back-propagation algorithm on CUDA, a parallel computing architecture developed by NVIDIA. Using CUBLAS, a CUDA implementation of the Basic Linear Algebra Subprograms library (BLAS), the process is simplified; however, the use of kernels was necessary since CUBLAS does not have all the required operations. The implementation was tested with two standard benchmark data sets and the results show that the parallel training algorithm runs 63 times faster than its sequential version. © 2010 IEEE.
Pacheco C.,Technological University of Mexico |
Garcia I.,Technological University of Mexico
Journal of Systems and Software | Year: 2012
This paper presents a systematic review of relevant published studies related to topics in Requirements Engineering, specifically, concerning stakeholder identification methods in requirements elicitation, dated from 1984 to 2011. Addressing four specific research questions, this systematic literature review shows the following evidence gathered from these studies: current status of stakeholder identification in software requirement elicitation, the best practices recommended for its performance, consequences of incorrect identification in requirements quality, and, aspects which need to be improved. Our findings suggest that the analyzed approaches still have serious limitations in terms of covering all aspects of stakeholder identification as an important part of requirements elicitation. However, through correctly identifying and understanding the stakeholders, it is possible to develop high quality software. © 2012 Elsevier Inc. All rights reserved.
Garcia I.,Technological University of Mexico |
Pacheco C.,Technological University of Mexico
Computers and Education | Year: 2013
Many courses for elementary school are based upon teacher presentation and explanation of basic topics, rather than allowing students to develop their own knowledge. This traditional model may turn elementary-level lessons into an extremely theoretical, boring and non-effective process. In this context, research in mathematics elementary education in Mexico indicates the need to analyze alternative pedagogic practices and to find different ways to make mathematics education in early ages less difficult and more attractive. Constructivist theory can provide an alternative for developing pedagogic proposals. The objectives of this research were: (1) develop a computational platform to support the traditional Mexican method of education with practical mathematics problems simulated as part of the daily world environment and to increase the level of students' social involvement through direct collaboration, and (2) analyze how this computational tool affects student motivation, collaboration and discussion. An exploratory case study concerning dimensions of mathematics problem-solving using computer simulations was conducted with 6-8 year old elementary school children. After a theoretical class the children were involved in solving a series of verbal problems, using our computational platform. Sixty third-grade children participated in this case study and data were collected from their responses to questions and interviews in order to explore attitudes toward learning mathematics and assess self-efficacy in this area. The results obtained in this research indicate that the integration of computational tools into conventional method courses provides elements to improve student motivation, collaboration and discussion based on their own exploratory experiences. These results can assist other education programs to incorporate positive attitudes and their own knowledge creation from a constructivist approach using technology. © 2013 Elsevier Ltd. All rights reserved.
Political concepts for the ethical debate on dilemmas on assisted suicide and euthanasia [Elementos políticos para o debate sobre os dilemas éticos do suicídio medicamente assistido e da eutanásia] [Elementos políticos para el debate sobre los dilemas éticos del suicidio médicamente asistido y de la eutanasia]
Rodriguez Soriano R.I.,Technological University of Mexico
Revista Ciencias de la Salud | Year: 2015
This essay is a reflection on some of the political elements embedded in the ethical problems of medically assisted suicide and euthanasia. The thesis work is that political theoretical foundations of modern nations are aimed to protect the lives of people, a fact that responds to a series of historical processes of the very development of modern political theory. These fundamentals directly affect the cultural and political positions for the refusal to accept the legalization or regulation of the two practices in question, thus denying the right of self-determination in human decision making on the own life and death. © 2015, Universidad del Rosario. All rights reserved.
Rosas-Caro J.C.,Madero City Technological Institute |
Mancilla-David F.,University of Colorado at Denver |
Mayo-Maldonado J.C.,University of Southampton |
Gonzalez-Lopez J.M.,Technological University of Mexico |
And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2013
This letter proposes a boost dc-dc converter topology with the novel capability of canceling the input current ripple at an arbitrarily preselected duty cycle. This is accomplished without increasing the count of the number of components in contrast to other solutions available in the literature. In addition, the converter features a high voltage gain without utilizing extreme values of duty cycle or boosting transformers. These features make the converter ideal to process electric power coming from low-voltage power-generating sources, such as renewables. This paper provides details on the principle of operation via topological considerations and a mathematical model. The key factor of reactive component sizing is also discussed in detail. The converter was validated in the laboratory through the construction of a hardware prototype. © 1982-2012 IEEE.
Cervera G.,Technological University of Mexico |
Barbeau M.,Carleton University |
Garcia-Alfaro J.,Orange Group |
Kranakis E.,Carleton University
Journal of Network and Computer Applications | Year: 2013
Multipath routing has been proposed to increase resilience against network failures or improve security in Mobile Ad Hoc Networks (MANETs). The Optimized Link State Routing (OLSR) protocol has been adopted by several multipath routing strategies. They implement Multipoint Relay (MPR) nodes as a flooding mechanism for distributing control information. Ideally, the construction of multiple disjoint paths helps to increase resilience against network failures or malicious attacks. However, this is not always possible. In OLSR networks, partial link-state information is generated and flooded exclusively by the MPRs. Therefore, the nodes only obtain a partial view of the network topology. Additionally, flooding disruption attacks may affect either the selection of the MPRs or the propagation of control traffic information. As a consequence, the chances of constructing multiple disjoint paths are reduced. We present a strategy to compute multiple strictly disjoint paths between any two nodes in OLSR-based networks. We provide mechanisms to improve the view of the network topology by the nodes, as well as handling potential flooding disruption attacks to the multipath construction mechanism in OLSR-based networks. We conduct simulations that confirm our claims. © 2012 Elsevier Ltd.