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Saucedo-Munoz M.L.,National Polytechnic Institute of Mexico | Lopez-Hirata V.M.,National Polytechnic Institute of Mexico | Avila-Davila E.O.,Pachuca Institute of Technology | Villegas-Cardenas J.D.,Polytechnic University of Mozambique | Gonzalez-Velazquez J.L.,National Polytechnic Institute of Mexico
Metal Science and Heat Treatment | Year: 2017

The effect of grain-boundary precipitates on cryogenic impact toughness of two corrosion steels (standard AISI 316 and a steel with a nitrogen additive) is studied. The steels are aged at 600 – 900°C with a hold of up to 1000 min. The KCV impact toughness at –196°C is determined. It is shown that the impact toughness of the nitrogen-containing steel decreases under cooling after the aging at 700 and 800°C more considerably than that of steel 316 after aging at 800 and 900°C. The causes of the embrittlement of the nitrogen-containing steel are determined. © 2017 Springer Science+Business Media New York


De Dios Garrido J.,Pachuca Institute of Technology | Nascimento M.A.C.,Federal University of Rio de Janeiro
International Journal of Quantum Chemistry | Year: 2010

The title reaction is studied in the frame of quasiclassical trajectory method using a previously reported global potential energy surface for the ground electronic state of HSO 2. To assert the role of vibrational excitation in molecular oxygen, specific calculations at some vibrational quantum states were carried out. To take into account the zero point energy leakage of the classical calculations, a passive method, Internal Energy Quantum Mechanical Threshold is used. HSO + O are the most formed set of products. Total reactive cross-sections are calculated and fitted to models in the studied energy range. Analytical expression for rate coefficients are reported as well. A comparison of reactivities when vibrational energy is deposited either in O 2 or in HS is also presented. © 2009 Wiley Periodicals, Inc.


Lopez-Hirata V.M.,National Polytechnic Institute of Mexico | Avila-Davila E.O.,Pachuca Institute of Technology | Saucedo-Munoz M.L.,National Polytechnic Institute of Mexico | Villegas-Cardenas D.,Polytechnic University of Mozambique | Ortiz-Mariscal A.,National Polytechnic Institute of Mexico
PTM 2015 - Proceedings of the International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2015 | Year: 2015

The application of phase field method, based on the Cahn-Hilliard equation, was investigated to simulate the early stages of phase decomposition during the isothermal aging of Al-Zn and Al-Zn-Cu alloys. The simulation results indicated that the start of phase decomposition, increase in modulation amplitude, took place during the aging of binary alloys at temperatures of 100-300 °C for times up to 50 h, while the start of phase decomposition occurred during the aging of ternary alloys at temperatures of 400-550 °C for times equal to or longer than 3600 s. This analysis also showed that the morphology of the decomposed phases is irregular and interconnected in both of the aged alloys. Likewise, the equilibrium composition of the decomposed phases for both alloys was in good agreement with the predicted values in the equilibrium phase diagrams.


Soriano-Vargas O.,National Polytechnic Institute of Mexico | Soriano-Vargas O.,Autonomous University of Mexico State | Avila-Davila E.O.,National Polytechnic Institute of Mexico | Avila-Davila E.O.,Pachuca Institute of Technology | And 3 more authors.
Materials Science and Engineering A | Year: 2010

The hardening behavior of precipitation was studied during aging of Fe-Cr alloys. This mechanical behavior is associated with the nanometric modulation structure of the coherent decomposed Fe-rich and Cr-rich phases formed by the spinodal decomposition of the supersaturated solid solution. The growth kinetics of spinodal decomposition was very slow and it increased during coarsening stage. The morphology of decomposed phases consisted of an interconnected irregular shape with no preferential alignment for short aging times and a further aging caused the change to a plate shape of the decomposed Cr-rich phase aligned in the 〈1 1 0〉 directions of the Fe-rich matrix. The rapid increase in hardness and embrittlement seem to be associated with the coherency and nanometer size of the spinodally decomposed phases in the aged alloys. © 2010 Elsevier B.V. All rights reserved.


Lopez-Villarreal F.,Celaya Institute of Technology | Lopez-Villarreal F.,Pachuca Institute of Technology | Lira-Barragan L.F.,Universidad Michoacana de San Nicolás de Hidalgo | Rico-Ramirez V.,Celaya Institute of Technology | And 2 more authors.
Computers and Chemical Engineering | Year: 2014

This paper proposes a mathematical programming model for the pollution trading among different pollution sources which considers the sustainability of the surrounding watershed. The formulation involves the minimization of the costs associated to the implementation of the required technology to satisfy the environmental constraints in order to achieve optimal water quality conditions. The model uses a material flow analysis technique to represent changes on the behavior of the watershed due to the polluted discharges. The material flow analysis considers all discharges and extractions (i.e., industrial and residential discharges, pluvial precipitation, evaporation, etc.) as well as the chemical and biochemical reactions taking place in the watershed. In the context of pollution trading, the implementation of the proposed formulation determines if an industrial source must buy credits to compensate the violation of environmental constraints, or if it requires the installation of treatment technologies to sell credits to another source. The formulation was applied to a case study involving the drainage system of the Bahr El-Baqar region in Egypt; the results show the advantages of the proposed approach in terms of cost and sustainability. © 2014 Elsevier Ltd.


Ablanedo-Rosas J.H.,University of Texas at El Paso | Alidaee B.,University of Mississippi | Moreno J.C.,Procter and Gamble | Urbina J.,Pachuca Institute of Technology
International Journal of Production Research | Year: 2010

Global markets are continuously changing and demanding customised, low cost, and high quality products and services; organisations that offer these products and services are dealing with these issues on a daily basis to stay competitive. Among the quality tools used to achieve competitive advantage, the 5S practice plays an important role facilitating the introduction and development of other quality and continuous improvement methods and techniques. We present results of an empirical study applied to some Mexican organisations with the aim of understanding their implementation experience, empirical relationships, and ongoing challenges associated with the 5S practice. © 2010 Taylor & Francis.


Gonzalez-Marron D.,Pachuca Institute of Technology | Gonzalez-Marron D.,Monterrey Institute of Technology | Gonzalez-Mendoza M.,Monterrey Institute of Technology | Hernandez-Gress N.,Monterrey Institute of Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

Recently, many researchers are trying to automate the automatic production of ontologies, realizing extraction of the information contained in databases using reverse engineering, however, because of the continuous evolution of standards in relational databases, not all the characteristics presented by modern databases managers are still supported. Besides as databases can be implemented in several ways in relational databases using different commands, this frequently causes differences when creating ontologies. In this paper, is presented how this approach can be applied to an epidemiological database and the advantages of use, when realizing query exploitation. © 2013 Springer-Verlag.


Cruz-Tolentino J.A.,Autonomous University of the State of Hidalgo | Ramos-Velasco L.E.,Autonomous University of the State of Hidalgo | Espejel-Rivera M.A.,Pachuca Institute of Technology
CONIELECOMP 2010 - 20th International Conference on Electronics Communications and Computers | Year: 2010

In this paper a self-tuning wavelet PID controller using wavelet networks is presented. The wavelet-based multiresolution PID controller was purpose by [8], the ability of this controller is to provide good rejection to disturbances and smooth control signal. One of its disadvantages is that the tuning gains are in trial or error mode. A wavelet network to identify the system and to tune the gains of the wavelet PID controller is proposed. To validate the proposed control system numerical simulation is performed for a motion control system. ©2010 IEEE.


Gomez-Mancilla J.C.,National Polytechnic Institute of Mexico | Palacios-Pineda L.M.,Pachuca Institute of Technology | Lopez-Grijalba Y.,Pachuca Institute of Technology
World Academy of Science, Engineering and Technology | Year: 2011

A new mechanism responsible for structural life consumption due to resonant fatigue in turbine blades, or vanes, is presented and explained. A rotating blade or vane in a gas turbine can change its contour due to erosion and/or material build up, in any of these instances, the surface pressure distribution occurring on the suction and pressure sides of blades-vanes can suffer substantial modification of their pressure and temperatures envelopes and flow characteristics. Meanwhile, the relative rotation between the blade and duct vane while the pressurized gas flows and the consequent wake crossings, will induce a fluctuating thrust force or lift that will excite the blade. An actual totally used up set of vane-blade components in a HP turbine power stage in a gas turbine is analyzed. The blade suffered some material erosion mostly at the trailing edge provoking a peculiar surface pressure envelope which evolved as the relative position between the vane and the blade passed in front of each other. Interestingly preliminary modal analysis for this eroded blade indicates several natural frequencies within the aeromechanic power spectrum, moreover, the highest frequency component is 94% of one natural frequency indicating near resonant condition. Independently of other simultaneously occurring fatigue cycles (such as thermal, centrifugal stresses).


Lezama-Alvarez S.,National Polytechnic Institute of Mexico | Avila-Davila E.O.,Pachuca Institute of Technology | Lopez-Hirata V.M.,National Polytechnic Institute of Mexico | Gonzalez-Velazquez J.L.,National Polytechnic Institute of Mexico
Materials Research | Year: 2013

The analysis of phase decomposition was carried out using the nonlinear and linear Cahn-Hilliard equations in a hypothetical A-B alloy system with a miscibility gap. These equations were solved by the explicit finite difference method assuming a regular solution model. The supersaturated solid solution and decomposed phases were considered to have an fcc structure. Different aging temperatures and thermodynamic interaction parameters OA-B were used to simulate different alloy systems. The numerical simulation results showed that the growth kinetics of phase decomposition in the alloy with 30at.% A was slower than that of 50 at.% A. Additionally, the start time and modulation wavelength of phase decomposition are strongly affected by the thermodynamic interaction parameter OA-B value. The numerical simulation results showed that the growth kinetics of phase decomposition with the linear equation is slower than that with the nonlinear one. © 2013.

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