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Alavez-Ramirez R.,Grupo Mexico | Alavez-Ramirez R.,Technological Institute of Oaxaca | Montes-Garcia P.,Grupo Mexico | Martinez-Reyes J.,ESFM IPN Escuela Superior de Fisica y Matematicas | And 3 more authors.
Construction and Building Materials | Year: 2012

This study analyzes the use of lime and sugar cane bagasse ash (SCBA) as chemical stabilizers in compacted soil blocks. The blocks were tested for flexure and compression in a dry and a saturated state. The tests were performed at 7, 14 and 28 days of age in order to evaluate the effects of the addition of lime and SCBA on the mechanical properties of the compacted soil blocks. The results indicate that blocks manufactured with 10% of lime in combination with 10% of SCBA showed better performance than those containing only lime. Nevertheless, the addition of lime improved the strength of the blocks when compared with blocks fabricated with plain soil. According to SEM and DRX analyses, considerable improvement of the matrix was observed due to the formation of strong phases, such as CSH and CAH for the mixtures with additives. It was also concluded that the combination of SCBA and lime as a replacement for cement in the stabilization of compacted soil blocks seems to be a promising alternative when considering issues of energy consumption and pollution. © 2012 Elsevier Ltd. All rights reserved.


Hernandez I.P.,National Autonomous University of Mexico | Gochi-Ponce Y.,Technological Institute of Oaxaca | Contreras Larios J.L.,Metropolitan Autonomous University | Fernandez A.M.,National Autonomous University of Mexico
International Journal of Hydrogen Energy | Year: 2010

Ni-W/Al2O3 catalysts were synthesized, characterized and tested for the steam reforming of ethanol from 300 to 600 °C. Addition of Ni and W on the alumina, decreased the surface area and increased the pore volume of the mesoporous materials synthesized. The reaction products obtained were: H2, CO2, C2H4, CH4, CO2, CO and CH3CHO. A promoting effect of Ni-W was observed in the conversion of ethanol to H2 from 15 to 30 wt.% Ni and 1 wt.% W. The selectivity to H2 on the alumina with Ni-W, was between 66.53 and 68.53% at 550 °C, appearing some undesirable products, with low ratio of CO/CO2. Reaction was studied on a fixed bed reactor at atmospheric pressure with an ethanol/water molar ratio of 1:4, from 300 to 600 °C. The catalysts were characterized by the thermal gravimetric analysis (TGA)-Differential thermal analysis (DTA), N2 physisorption (BET and BJH methods), X-ray diffraction (XRD) and scanning electron microscopy (SEM), these techniques were used for characterization, before and after of the steam reforming. © 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.


Cortes-Martinez C.I.,National Polytechnic Institute of Mexico | Garcia-Mendez R.F.,Technological Institute of Oaxaca
Journal of Natural Fibers | Year: 2016

The morphology of the cross-section and longitudinal-section of bagasse fibers of Agave angustifolia Haw from the elaboration process of mezcal were investigated and tensile tests were performed in function of the diameter (0.20–0.79 mm), gauge length (10, 15 and 20 mm) and strain rate (5–50 mm/min). The cross-section of the fibers is ribbon-shape like with dislocations and the longitudinal section has mechanical damage in its surface. The ultimate tensile strength (14.83–86.51 MPa) and Young’s modulus (0.20–1.26 GPa) are influenced by the diameter and the strain rate, while the strain at failure (16–26%) is influenced by the gauge length. These results are discussed in light of information on relationship between morphology and tensile properties of natural fibers and possible effects of the elaboration process of mezcal. © 2016 Taylor & Francis


Rojas-Zarate Y.,Technological Institute of Oaxaca | Mondragon D.,National Polytechnic Institute of Mexico
Revista Mexicana de Biodiversidad | Year: 2016

Although there are bromeliad inventories for Mexico, some regions of the country have not yet been extensively sampled, as is the case of the district of Zaachila in Oaxaca. According to the literature, there are only 3 species of epiphytic bromeliads there. However, large areas of pine-oak and oak suggest a greater richness of epiphytic bromeliads. In order to complement Mexican bromeliad records, specifically in the Oaxacan region, 2 plots (1 ha/plot) were sampled in the 3 vegetation types reported for the District of Zaachila: pine, pine-oak and oak. The objective was the search of bromeliad species present in each type of vegetation. We found 17 species of bromeliads: 16 belonging to genus Tillandsia and 1 to genus Catopsis. The pine-oak forest was the most diverse, with 16 species; followed by oak forest, with 7 species, and pine forest with 2 species. We are presenting the first formal inventory of epiphytic bromeliads of the Zaachila District. © 2016 Universidad Nacional Autónoma de México, Instituto de Biología.


Flores-Ruiz F.J.,CINVESTAV | Enriquez-Flores C.I.,CINVESTAV | Chinas-Castillo F.,Technological Institute of Oaxaca | Espinoza-Beltran F.J.,CINVESTAV
Applied Surface Science | Year: 2014

Fullerene-like carbon nitride films exhibit high elastic modulus and low friction coefficient. In this study, thin CNx films were deposited on silicon substrate by DC magnetron sputtering and the tribological behavior at nanoscale was evaluated using an atomic force microscope. Results show that CNx films with fullerene-like structure have a friction coefficient (CoF ∼ 0.009-0.022) that is lower than amorphous CNx films (CoF ∼ 0.028-0.032). Analysis of specimens characterized by X-ray photoelectron spectroscopy shows that films with fullerene-like structure have a higher number of sp3 CN bonds and exhibit the best mechanical properties with high values of elastic modulus (E > 180 GPa) and hardness (H > 20 GPa). The elastic recovery determined on specimens with a fullerene-like CNx structure was of 95% while specimens of amorphous CNx structure had only 75% elastic recovery. © 2014 Elsevier B.V.


Trejo F.,National Polytechnic Institute of Mexico | Rana M.S.,Kuwait Institute for Scientific Research | Ancheyta J.,Mexican Institute of Petroleum | Rueda A.,Mexican Institute of Petroleum | Rueda A.,Technological Institute of Oaxaca
Fuel | Year: 2012

Pure and mixed oxides (Al 2O 3, ZrO 2, Al 2O 3-MgO, Al 2O 3-SiO 2, Al 2O 3-TiO 2, and Al 2O 3-ZrO 2) were prepared by homogeneous delayed precipitation. The synthesized supports were impregnated by incipient wetness method to obtain CoMo catalysts. Both supports and catalysts were characterized by N 2 physisorption, X-ray diffraction, among other techniques. Acid-base properties were studied with isopropyl alcohol and cumene decomposition. It was possible to assess qualitatively that nature of Al-Si and its respective catalyst was mainly acidic. Conversion of isopropyl alcohol leads to the dehydration products, mostly propylene with a low amount of di-isopropyl ether and acetone. The CoMo/Al 2O 3-SiO 2 catalyst showed the highest conversion during cumene cracking. CoMo/Al 2O 3-SiO 2 catalyst also was the most active during thiophene hydrodesulfurization followed by CoMo/Al 2O 3-TiO 2 catalyst. © 2012 Elsevier Ltd. All rights reserved.


de Rubio J.J.,National Polytechnic Institute of Mexico | Gutierrez G.,National Polytechnic Institute of Mexico | Pacheco J.,National Polytechnic Institute of Mexico | Perez H.,Technological Institute of Oaxaca
International Journal of Innovative Computing, Information and Control | Year: 2011

Through the time, there are less farms and less production of food, however, more food is required. The people are afraid for the high costs of the food, and some kinds of food cannot be bought by some persons. In some countries as India and China, the population has grown increasing their necessity of food. Other situation is that some land has been taken for other things subtracting the space used for the agriculture. In this paper, three kinds of controls are proposed to accelerate the growth of the crop plants, yielding an increase in the crop production in a greenhouse. The major contributions of this paper are as follows: 1) The singular perturbed control is modified to be applied to accelerate the greenhouse crop production and to be exponential stable, however, the condition that needed to guarantee the exponential stability of the tracking error of the closed loop system in the theory is not satisfied and in the simulations, it is shown that this control does not have a good behavior. 2) The state feedback control is modified to be applied to accelerate the greenhouse crop production and to be exponential stable, however, in the last row of a matrix related with the control has zeros giving that even the exponential stability of the tracking error of the closed loop system is assured in the theory, the simulations give that the state which describes the growth of the crop cannot be controlled. 3) The fictitious control is modified to be applied to accelerate the greenhouse crop production and to be exponential stable, the exponential stability of the tracking error of the closed loop system is a assured in the theory, and in the simulations it is shown that this control has a good tracking control behavior. © 2011 ISSN.


Perez-Cruz J.H.,Technological Institute of Oaxaca | Chairez I.,National Polytechnic Institute of Mexico | Poznyak A.,National Polytechnic Institute of Mexico | de Rubio J.J.,National Polytechnic Institute of Mexico
International Journal of Innovative Computing, Information and Control | Year: 2011

In this study, a control scheme to accomplish the tracking of power profiles in a TRIGA Reactor is presented. This scheme permits the fulfillment of the inverse period constraint. Additionally, it eliminates the need for a physical model of the plant. Closed-loop identification of the nuclear system is carried out based only on external reactivity and neutron power by a differential neural network. This network utilizes a new learning law by which it is possible to guarantee the boundedness for weights and identification error. Once a neural model of the reactor is obtained, inverse period constraint can be expressed as a new constraint on the control input (external reactivity). However, an error term must be calculated to determine the new admissible set of control signal. This difficulty is overcome by using the sliding mode technique. Finally, a new control law is proposed. The effectiveness of this procedure is illustrated by numeric simulation. © 2011 ISSN 1349-4198.


Alavez-Ramirez R.,The Interdisciplinary Center | Chinas-Castillo F.,Technological Institute of Oaxaca | Morales-Dominguez V.J.,The Interdisciplinary Center | Ortiz-Guzman M.,The Interdisciplinary Center
Construction and Building Materials | Year: 2012

This study evaluates the potential use of coconut fibre as thermal isolating filler for ferrocement panel walls in sandwich configuration of schools and houses' roofing in Puerto Escondido, Oaxaca, Mexico. Thermal conductivity measurements were performed to compare the thermal behaviour of ferrocement panel walls filled with coconut fibre to other typical building materials of the region. Measured thermal conductivities for red clay brick, hollow concrete block and lightweight concrete brick panel walls are 0.93, 0.683 and 0.536 W/m K respectively. Thermal conductivity of the proposed configuration is 0.221 W/m K and that is lower than typical materials used for home-buildings in this region. © 2012 Elsevier Ltd. All rights reserved.


Guzman-Arenas A.,National Polytechnic Institute of Mexico | Guzman-Arenas A.,Technological Institute of Oaxaca | Cuevas A.-D.,National Polytechnic Institute of Mexico | Cuevas A.-D.,Technological Institute of Oaxaca
Expert Systems with Applications | Year: 2010

In order to compute intelligent answers to complex questions, using the vast amounts of information existing in the Web, computers have (1) to translate such knowledge, typically from text documents, into a data structure suitable for automatic exploitation; (2) to accumulate enough knowledge about a certain topic or area by integrating or fusing these data structures, taking into account new information, additional details, better precision, synonyms, homonyms, redundancies, apparent contradictions and inconsistencies found in the incoming data structures to be added; and (3) to perform deductions from that amassed body of knowledge, most likely through a general query processor. This article seeks to solve point (2) by using a method (OM, Ontology Merging), with its algorithm and implementation, to fuse two ontologies (coming from Web documents) without human intervention, producing a third ontology, taking into account the inconsistencies, contradictions and redundancies between them, thus delivering an answer close to reality. Results of OM working on ontologies extracted from Web documents are shown. © 2009 Elsevier Ltd. All rights reserved.

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