Time filter

Source Type

Mexico City, Mexico

Rojas-Chavez H.,Tlahuac Institute of Technology | Rojas-Chavez H.,Research Center en Ciencia Aplicada y Tecnologia Avanzada | Reyes-Carmona F.,National Autonomous University of Mexico | Garibay-Febles V.,Mexican Institute of Petroleum | Jaramillo-Vigueras D.,Research Center e Innovacion Tecnologica
Journal of Nanoparticle Research | Year: 2013

Transformations from precursors to nanoparticles by high-energy milling are promoted by two major driving forces, namely physical and/or chemical. While the former has been difficult to trace since stress, strain and recovery may occur almost simultaneously during milling, the latter has been sequentially followed as an evolution from precursors to intermediate phases and thereof to high purity nanocrystals. The specific objective of this work is to discern how solid-solid and partially solid-gas reactions manifest themselves correspondingly as a short-range diffusion through an interface or how vapor species, as a subliming phenomenon, grows as a different phase on an active local surface. These series of changes were traced by sub-cooling the as-milled powders extracted during a milling cycle. Through this experimental technique, samples were electron microscopically analyzed and where it was required, selected area electron diffraction images were obtained. High-resolution transmission electron microscopy results, unambiguously, confirm that nanocrystals in the last stage show a cubic morphology which average size distributions are around 17 nm. © 2013 Springer Science+Business Media Dordrecht.

Ramirez-Neria M.,Tlahuac Institute of Technology | Sira-Ramirez H.,CINVESTAV | Rodriguez-Angeles A.,CINVESTAV | Luviano-Juarez A.,UPIITA IPN
Proceedings of the American Control Conference | Year: 2012

In this article, we address an active disturbance rejection controller design for the output reference trajectory tracking problem in a 3 degree of freedom (DOF) Delta Robot. The proposed method relies on purely linear high gain disturbance observation and linear feedback control techniques. The estimation tasks are carried out with the help of Generalized Proportional Integral (GPI) observers, endowed with output integral injection to counteract zero mean measurement noise effects. As the lumped exogenous and endogenous disturbance inputs are estimated, the observers deliver them to the controllers for on-line disturbance cancelation, while simultaneously the phase variables, related to the measured flat outputs, are being estimated by the same GPI observer. The gathered values of the phase variables are used to complete a linear multivariable output feedback control scheme. The proposed control scheme avoids the traditional computed torque method, reducing the computation time and bypassing the need for explicit, accurate, knowledge of the plant. The estimation and control method is only approximate as small as desired reconstruction, or tracking, errors are guaranteed. The reported results, including laboratory experiments, are significantly better than the results provided by the classical model-based techniques, when the system is subject to endogenous and exogenous uncertainties. © 2012 AACC American Automatic Control Council).

Carrillo I.,Tlahuac Institute of Technology | Ramirez J.M.,National Autonomous University of Mexico | Magana L.F.,National Autonomous University of Mexico
Surface Science | Year: 2015

We used density functional theory and molecular dynamics to explore the adsorption of CO, CO2, and CH4 on a layer of h-BN with high titanium coverage. After optimization, we found that each titanium atom is located above each of the hexagons of the surface. We considered atmospheric pressure and 300 K. It is found that the first molecule is adsorbed and dissociated on the surface. The CO2 molecule is broken into O and CO. The methane molecule is physisorbed, and not dissociated. It is desorbed at 370 K. © 2015 Elsevier B.V.

Aviles Coyoli K.L.,Tlahuac Institute of Technology | Perez Armendariz B.,UPAEP University | Rosano Ortega G.,UPAEP University
Revista Internacional de Contaminacion Ambiental | Year: 2014

The number of students in higher technological education in Mexico is an important part of the national enrollment in this field. The learning competencies in sustainable development that future professionals acquire, will contribute to the strengthening society in a more just and balanced manner. The objective of this research was to know the competencies acquired by the students of The Technological Institute of Tlahuac, who studied the Sustainable Development subjects through the Sustainability Culture Index (SCI). Surveys were conducted (n = 254) to students majoring in Computer Engineering, Electronics Engineering, Mechatronics Engineering, and Architecture. SCI was generated with values from 0 to 10 on the expertise of four factors: (1) the sustainability, (2) the environmental dimension, (3) the social dimension, and (4) the economic dimension, with three variables: a) professional vision and sensitivity, b) life style and actions in environmental care, and c) acquired competencies in sustainable development. Results showed no significant differences in the four factors of study, with an SCI less than 7. The average SCI that stands out in acquired competency is with a value of 4.27. Regarding to gender, there are no significant differences in SCI with ranging values from 4.28 to 7.7. The education of sustainable development in Mexico is still in its early stages. The acquisition of this field´s competency should be strengthened, if it´s expected to have professionals who possess a critical thinking in relation to sustainability. © 2014 Centro de Ciencias de la Atmosfera, UNAM. All rights reserved.

Carrillo I.,Tlahuac Institute of Technology | Rangel E.,National Autonomous University of Mexico | Ramirez-De-Arellano J.M.,National Autonomous University of Mexico | Magana L.F.,National Autonomous University of Mexico
Surface Science | Year: 2013

Density functional theory and molecular dynamics were used to study the adsorption of sulfuric acid on two surfaces. One is graphene modified with titanium with high metal coverage (C2Ti). The other is a [001] titanium surface. We considered cis and trans molecule conformers at 300 K, and atmospheric pressure. We found that the molecule (trans and cis) is dissociated and chemisorbed on the graphene-titanium layer, in several ways, forming a conductor surface. We also found that the molecule (cis and trans) is dissociated on the [001] titanium surface in only one, but a different way. In this case, all four oxygen atoms are chemisorbed, forming titanium oxide (TiO). The remaining sulphydric acid is physisorbed, and it desorbs at 700 K. © 2013 Elsevier B.V.

Discover hidden collaborations