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Segundo-Ramirez J.,Autonomous University of San Luis Potosi | Segundo-Ramirez J.,Instituto Tecnologico Superior Of Irapuato | Barcenas E.,Autonomous University of San Luis Potosi | Medina A.,Universidad Michoacana de San Nicolás de Hidalgo | Cardenas V.,Autonomous University of San Luis Potosi
IEEE Transactions on Industrial Electronics | Year: 2011

This paper provides the comprehensive development procedures and mathematical model of an adjustable speed drive (ASD) for steady-state solutions, transient trajectories, and local stability based on a Floquet multiplier theory. A complete representation of the ASD is employed, which includes the dynamic equation of the dc link capacitor and the detailed models of the diode rectifier and of the pulse width modulated inverter. The power electronic switches are efficiently represented through smooth functions that allow a larger integration step to be used without the loss of precision in the solution. An efficient technique in the time domain for the computation of the periodic steady-state solution of electric systems, including ASDs based on a discrete-exponential-expansion matrix and the Poincaré map, is used. The obtained results are validated against the solutions obtained with an implementation using the Power System Blockset of Simulink and against the response obtained by the measurements from a 1.5-kVA ASD experimental setup system. © 2006 IEEE.


Vargas-Bernal R.,Instituto Tecnologico Superior Of Irapuato | Herrera-Perez G.,Instituto Tecnologico Superior Of Irapuato | Calixto-Olalde M.E.,Instituto Tecnologico Superior Of Irapuato | Tecpoyotl-Torres M.,Autonomous University of the State of Morelos
Journal of Electrical and Computer Engineering | Year: 2013

The design of nanometric electronic devices requires novel materials for improving their electrical performance from stages of design until their fabrication. Until now, several DC electrical conductivity models for composite materials have been proposed. However, these models must be valued to identify main design parameters that more efficiently control the electrical properties of the materials to be developed. In this paper, four different models used for modeling DC electrical conductivity of carbon nanotube-polymer composites are studied with the aim of obtaining a complete list of design parameters that allow guarantying to the designer an increase in electrical properties of the composite by means of carbon nanotubes. © 2013 Rafael Vargas-Bernal et al.


Ramirez-Bautista A.,Autonomous University of the State of Hidalgo | Stephenson B.P.,Mercer University | Lozano A.,Autonomous University of the State of Hidalgo | Uribe-Rodriguez H.,Autonomous University of the State of Hidalgo | Manrique A.L.,Instituto Tecnologico Superior Of Irapuato
Ecology and Evolution | Year: 2012

The spiny lizard Sceloporus grammicus (Squamata: Phrynosomatidae) is a small reptile from central México and the southern United States, occurring in a wide geographic area characterized by extensive variation in topographic and climatic regimes. Genetic variation among lineages from central México is substantial, though the extent to which this variation corresponds with life-history traits remains obscure. To address part of this puzzle, we studied a population of S. grammicus from Tepeapulco, Hidalgo, México. Male-biased sexual dimorphism was extensive in this population;males were larger than females overall, and expressed proportionately larger heads and longer limbs. Minimum size at sexual maturity was similar in the sexes (males: 43 mm; females: 42 mm). In contrast to other populations from the Central Plateau, reproductive activity of males and females was synchronous. Testicular recrudescence of adult males was initiated in October-November, and maximum testis size maintained from December to July. Female reproductive activity showed no clear seasonal pattern: females had vitellogenic follicles from October to July, and pregnant females were found throughout the year. Female body size was not related to litter size. Neither male nor female gonadal mass was correlated with any abiotic environmental variable examined. Differences in reproductive characteristics among populations of S. grammicus might be indicative of plasticity in response to local environmental conditions, local adaptation, or complex gene × environment interactions. We consider these results in the context of previously studied populations of S. grammicus from the Central Plateau and elsewhere, and propose directions for future research. © 2012 The Authors.


Zamora-Cardenas A.,Instituto Tecnologico Superior Of Irapuato | Zamora-Cardenas A.,Universidad Michoacana de San Nicolás de Hidalgo | Fuerte-Esquivel C.R.,Universidad Michoacana de San Nicolás de Hidalgo
Electric Power Systems Research | Year: 2011

This paper proposes a practical approach to incorporate Flexible AC Transmission Systems (FACTS) devices into a Weighted Least Squares (WLS) state estimation algorithm. The FACTS devices included in the estimator are the Thyristor Controlled Series Compensator (TCSC), the Static Var Compensator (SVC), and the Unified Power Flow Controller (UPFC). The proposed approach simultaneously upgrades the estimated values of the state variables of these devices and the state variables of the rest of the electric network, for a unified solution in a single-frame of reference. Results are presented to demonstrate the effectiveness of the proposed approach to assess the estimation of the system state and to set the parameters of FACTS controllers for given control specifications. © 2010 Elsevier B.V.


Guzman-Altamirano M.,San Luis Potosí Institute of Scientific Research and Technology | Guzman-Altamirano M.,Instituto Tecnologico Superior Of Irapuato | Gutierrez-Medina B.,San Luis Potosí Institute of Scientific Research and Technology
Optics Express | Year: 2015

We present an efficient alternative to remove lateral chromatic aberration (LCA) in bright field light microscopy images. Our procedure is based on error calibration using time-sequential acquisition at different wavelengths, and error correction through digital image warping. Measurement of the displacements of fiducial marks in the red and green images relative to blue provide calibration factors that are subsequently used in test images to realign color channels digitally. We demonstrate quantitative improvement in the position and boundaries of objects in target slides and in the color content and morphology of specimens in stained biological samples. Our results show a reduction of LCA content below the 0.1% level. © 2015 Optical Society of America.


Ramirez-Bautista A.,Autonomous University of the State of Hidalgo | Smith G.R.,Denison University | Leyte-Manrique A.,Instituto Tecnologico Superior Of Irapuato | Hernandez-Salinas U.,Autonomous University of the State of Hidalgo
Southwestern Naturalist | Year: 2013

Sexual dimorphism in the genus Sceloporus has historically been relatively well studied; however, there is little understanding of how patterns of sexual size dimorphism might vary within species and how that might affect our ability to generalize about the evolution of sexual size-dimorphism in Sceloporus and other organisms. We examined sexual size-dimorphism in a population of Sceloporus spinosus from Guadalcázar, San Luis Potosí, Mexico. Males (n = 85) and females (n = 63) showed no significant sexual dimorphism in size of the body, head, or legs. In combination with the results of other studies on sexual dimorphism in S. spinosus and closely related species of Sceloporus, our results suggest that there can be variation in sexual size-dimorphism within and among species that can limit the ability to make broad generalizations about the phylogenetic patterns of sexual dimorphism in Sceloporus.


Torres-Fernandez J.E.,Instituto Tecnologico Superior Of Irapuato | Espinosa-Paredes G.,Metropolitan Autonomous University | Prieto-Guerrero A.,Metropolitan Autonomous University
Annals of Nuclear Energy | Year: 2012

A novel method based on time-scale representations (TSR) is proposed to determine the time evolution of the linear stability parameters of a boiling water reactor (BWR) using neutronic noise signals. TSR are obtained by the affine smoothing of the Wigner time frequency representation (TFR) via an exponential kernel, the resulting TSR is called "exponential TSR" (ETSR). From the ETSR at a low scale, it is show how to estimate an instantaneous decay ratio (IDR) whose accumulated product is called the accumulated decay ratio (ACDR) closely follows the energy distribution given by a bilinear TFR valuated at the natural resonance frequency of the BWR. Therefore the peaks of the ACDR as a function of time indicate the periods of time where the energy buildups inside the BWR happen, i.e., those points in time where the nuclear reactor is having difficulty in dissipating energy out of its system. Therefore the energy buildups are directly correlated to reactor instability and, accordingly during those events the ACDR increases its value as expected indicating local instabilities. The methodology presented in this paper is validated using synthetic signals as well as real neutronic noise signals from the Laguna Verde event and the Ringhals stability benchmark. © 2012 Elsevier Ltd. All rights reserved.


Nunez-Colin C.A.,Instituto Nacional de Investigaciones Nucleares | Hernandez-Martinez M.A.,Instituto Nacional de Investigaciones Nucleares | Escobedo-Lopez D.,Instituto Nacional de Investigaciones Nucleares | Ortega-Rodriguez C.,Instituto Tecnologico Superior Of Irapuato
Plant Genetic Resources: Characterisation and Utilisation | Year: 2012

The genus Malacomeles (Decne.) G. N. Jones (Rosaceae subtribe Pyrinae) represents several fruit shrubs, which is mainly distributed in North and Central America, from southern USA to Honduras and Guatemala, although the main distribution of this genus is in Mexico. Five species of the genus Malacomeles have been reported to exist in Mexico. Malacomeles is widely distributed in several mountainous ranges in Mexico, although it is unknown where most of the diversity of the Malacomeles genus is located in the country. The aim of this biogeographic study was to determine the areas of highest diversity of the genus Malacomeles in Mexico based on species richness and diversity indices in order to identify the best regions of Mexico to collect germplasm. The results indicated that most of the diversity of the genus Malacomeles is concentrated in northeast Mexico, mainly in the biogeographic province of Sierra Madre Oriental. In this province, the highest values on three biodiversity indices were found. Thus, this area can be considered as the priority area to collect the germplasm of Malacomeles. M. denticulata is the predominant and the most interesting species in Mexico from the viewpoint of collecting plant genetic resources; this species is mainly distributed in the provinces of Trans-Mexican Volcanic Axis, Mexican Plateau and Sierra Madre del Sur, where secondary priority areas to collect germplasm are located. © Copyright 2012 © NIAB.


Hernandez-Hernandez V.,Colegio de Mexico | Hernandez-Hernandez V.,Instituto Tecnologico Superior Of Irapuato | Terrazas T.,National Autonomous University of Mexico | Mehltreter K.,Institute Ecologia Ac | Angeles G.,Institute Ecologia Ac
Botanical Journal of the Linnean Society | Year: 2012

In ferns, leaf traces in the petioles are sometimes surrounded by a circumendodermal band (CB), a cell layer of varying structure and arrangement. We studied the CB of 89 fern species from 53 genera and 28 families, and its correlation with leaf trace configuration, leaf dissection and life form, to explore its anatomical diversity, possible origin and suitability for fern systematics. The cells of the CB always contain tannins in their lumina and their walls, but lack lignin and suberin. Cell wall thickness varies among species and may prove to be useful for fern systematics. The occurrence of the CB correlates with a larger number of vascular strands in the leaf trace and a lower degree of leaf dissection, but not with life form. Cystopteridaceae is the earliest branching family with a CB. The exclusive presence of the CB in nine of the most derived fern families supports the hypothesis of a single origin before the divergence of the two major clades of eupolypods. The discontinuity or absence of the CB in some species of derived families (e.g. Polypodiaceae, subfamily Polypodioideae) is interpreted as a secondary loss. Possible functions of the CB are discussed. © 2012 The Linnean Society of London.


Vargas-Bernal R.,Instituto Tecnologico Superior of Irapuato
IEEE Journal on Emerging and Selected Topics in Circuits and Systems | Year: 2015

Nowadays electronic devices such as p-n diodes, field-effect transistors, logic gates, mixers, ring oscillators, and memories have been designed based on single, bi and/or multi-layer graphene. However, a lot of effort must be developed to integrate mathematical models into new simulators for electronic devices based on nanomaterials such as those based on carbon nanotubes, fullerenes, and graphene. Main contributions with respect to modeling and simulation of electronic devices based on graphene and developed in the ultimate years are analyzed here. In addition, future perspectives related with mathematical modeling of electronic devices based on graphene are discussed. © 2014 IEEE.

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