Autonomous University of Coahuila
Saltillo, Mexico

The Autonomous University of Coahuila is a state university founded in 1957. It is located in the northern Mexican state of Coahuila. The university system has three campuses — Saltillo, Torreón, and Norte — distributed among the most populated cities in the state. It perhaps the only one university in the world which is governed by a President elected for a period of 3 years by direct general balloting by the unqualified vote of both students and teachers. Wikipedia.

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Azhmyakov V.,University of Medellín | Juarez R.,Autonomous University of Coahuila
Nonlinear Analysis: Hybrid Systems | Year: 2017

This paper studies optimal control processes governed by switched-mode systems. We consider Optimal Control Problems (OCPs) with smooth cost functionals and apply a newly elaborated abstraction for the system dynamics under consideration. The control design we finally obtain includes an optimal switching times selection ("timing") as well as an optimal modes sequence scheduling ("sequencing"). For purpose of numerical treatment of the initially given OCP we use a newly elaborated relaxation concept and analyse the resulting "weakly relaxed" optimization problems. In contrast to the conventional relaxations our approach is based on the infimal prox convolution technique and does not use the celebrated Chattering Lemma. This fact causes a lower relaxation gap. Our aim is to propose a gradient-based computational algorithms for the OCPs with switched-mode dynamics. In particular, we deal with the celebrated Armijo-type gradient methods and establish the corresponding convergence properties. The numerical consistency (numerical stability) analysis makes it possible to apply a class of relative simple first-order numerical procedures to a sophisticated initial OCP involved in specific switched-mode dynamics. © 2017 Elsevier Ltd.

Salgado Conrado L.,Autonomous University of Coahuila | Rodriguez-Pulido A.,Autonomous University of Noreste | Calderon G.,Autonomous University of Coahuila
Renewable and Sustainable Energy Reviews | Year: 2017

The thermodynamics of a Parabolic Trough Solar Collector (PTC) play an important role in solar energy and the efficiency of the collectors. This report presents an up-to-date review on the thermal performance of PTC collectors. Various types of mathematical models, simulation and numerical methods, and experimental set-ups of the Parabolic Trough Solar Collectors are reviewed. These have been studied in terms of heat loss, environmental conditions, temperature and heat flux. Furthermore, the report cost analysis and economic strategy used for PTC collectors. The primary goal is to demonstrate the principal thermal aspects that need to be considered in future developments. The principal challenges that engineers face are (a) combining the thermal models that have been reported in the literature, (b) introducing numerical methods and simulations with less computational requirements, (c) proposing new methodologies that efficiently measure the thermal performance of a Parabolic Trough Solar Collector and (d) reducing the costs of these collectors. © 2016 Elsevier Ltd

Nieto Gonzalez J.P.,Autonomous University of Coahuila
International Journal on Interactive Design and Manufacturing | Year: 2017

The main goals of a fault diagnosis system in a vehicle are to prevent dangerous situations for occupants. This domain is a complex system that turns the monitoring task a very challenging one. This paper presents a new approach based on history data process. In the first phase the approach learns behaviour from normal operation of the system using an autoassociative neural network. In the second phase a multiclass support vector machine classifies the type of fault present giving the final diagnosis. Results are shown for a ten variables vehicle monitoring. © 2017 Springer-Verlag France

Calderon G.,Autonomous University of Coahuila | Munoz J.H.,University of Tolima | Vera C.E.,University of Tolima
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Axial-vector mesons a1(1260), f1(1285), h 1(1170), K1(1270), and K1(1400) can be produced in semileptonic τ→APντ decays, where P stands for the pseudoscalar mesons π or K. We calculate the branching ratios based in a meson dominance model. The exclusive channels τ-→a 1(1260)-π0ν, τ-→a 1(1260)0π-ν, and τ-→h 1(1170)π-ν turn out to be of order O(10 -3), the channel τ-→f1(1285)π -ν of order O(10-4), and channels τ -→K1(1270)-π0ν, τ -→K1(1270)0π-ν, τ -→K1(1400)-π0ν, and τ-→K1(1400)0π-ν of order O(10-6). These results indicate that the branching ratios could be measured in experiments. © 2013 American Physical Society.

Delgado-Acosta E.G.,Autonomous University of San Luis Potosi | Kirchbach M.,Autonomous University of San Luis Potosi | Napsuciale M.,University of Guanajuato | Rodriguez S.,Autonomous University of Coahuila
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We study multipole decompositions of the electromagnetic currents of spin-1/2, 1, and 3/2 particles described in terms of representation-specific wave equations which are second order in the momenta and which emerge within the recently elaborated Poincaré covariant-projector method, where the respective Lagrangians explicitly depend on the Lorentz group generators of the representations of interest. The currents are then the ordinary linear Noether currents related to phase invariance, and present themselves always as two-terms motion-plus spin-magnetization currents. The spin-magnetization currents appear weighted by the gyromagnetic ratio g, a free parameter in the method which we fix either by unitarity of forward Compton scattering amplitudes in the ultraviolet for spin-1 and spin-3/2, or in the spin-1/2 case, by their asymptotic vanishing, thus ending up in all three cases with the universal g value of g=2. Within the method under discussion, we calculate the electric multipoles of the above spins for the spinor, the four-vector, and the four-vector-spinor representations, and find it favorable in some aspects, specifically in comparison with the conventional Proca and Rarita-Schwinger frameworks. We furthermore attend to the most general non-Lagrangian spin-3/2 currents, which are allowed by Lorentz invariance to be up to third order in the momenta and construct the linear-current equivalent of identical multipole moments of one of them. We conclude that nonlinear non-Lagrangian spin-3/2 currents are not necessarily more general and more advantageous than the linear spin-3/2 Lagrangian current emerging within the covariant-projector formalism. Finally, we test the representation dependence of the multipoles by placing spin-1 and spin-3/2 in the respective (1,0)(0,1) and (3/2,0)(0,3/2) single-spin representations. We observe representation independence of the charge monopoles and the magnetic dipoles, in contrast to the higher multipoles, which turn out to be representation-dependent. In particular, we find the bi-vector (1,0)(0,1) to be characterized by an electric quadrupole moment of opposite sign to the one found in (1/2,1/2), and consequently to the W boson. This observation allows us to explain the positive electric quadrupole moment of the ρ meson extracted from recent analyses of the ρ meson electric form factor. Our finding points toward the possibility that the ρ-meson could transform as part of an antisymmetric tensor with an a 1 mesonlike state as its representation companion, a possibility consistent with the empirically established ρ and a 1 vector meson dominance of the hadronic vector and axial-vector currents. © 2012 American Physical Society.

Martins S.,IBB Institute for Biotechnology And Bioengineering | Mussatto S.I.,IBB Institute for Biotechnology And Bioengineering | Martinez-Avila G.,Autonomous University of Coahuila | Montanez-Saenz J.,Autonomous University of Coahuila | And 2 more authors.
Biotechnology Advances | Year: 2011

Interest in the development of bioprocesses for the production or extraction of bioactive compounds from natural sources has increased in recent years due to the potential applications of these compounds in food, chemical, and pharmaceutical industries. In this context, solid-state fermentation (SSF) has received great attention because this bioprocess has potential to successfully convert inexpensive agro-industrial residues, as well as plants, in a great variety of valuable compounds, including bioactive phenolic compounds. The aim of this review, after presenting general aspects about bioactive compounds and SSF systems, is to focus on the production and extraction of bioactive phenolic compounds from natural sources by SSF. The characteristics of SSF systems and variables that affect the product formation by this process, as well as the variety of substrates and microorganisms that can be used in SSF for the production of bioactive phenolic compounds are reviewed and discussed. © 2011 Elsevier Inc.

Mata-Gomez L.C.,Autonomous University of Coahuila | Montanez J.C.,Autonomous University of Coahuila | Mendez-Zavala A.,Autonomous University of Coahuila | Aguilar C.N.,Autonomous University of Coahuila
Microbial Cell Factories | Year: 2014

Nowadays, carotenoids are valuable molecules in different industries such as chemical, pharmaceutical, poultry, food and cosmetics. These pigments not only can act as vitamin A precursors, but also they have coloring and antioxidant properties, which have attracted the attention of the industries and researchers. The carotenoid production through chemical synthesis or extraction from plants is limited by low yields that results in high production costs. This leads to research of microbial production of carotenoids, as an alternative that has shown better yields than other aforementioned. In addition, the microbial production of carotenoids could be a better option about costs, looking for alternatives like the use of low-cost substrates as agro-industrials wastes. Yeasts have demonstrated to be carotenoid producer showing an important growing capacity in several agro-industrial wastes producing high levels of carotenoids. Agro-industrial wastes provide carbon and nitrogen source necessary, and others elements to carry out the microbial metabolism diminishing the production costs and avoiding pollution from these agro-industrial wastes to the environmental. Herein, we discuss the general and applied concepts regarding yeasts carotenoid production and the factors influencing carotenogenesis using agro-industrial wastes as low-cost substrates. © 2014 Mata-Gómez et al.; licensee BioMed Central Ltd.

Calderon G.,Autonomous University of Coahuila
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

Nonleptonic two-body B decays including radially excited π(1300) or ρ(1450) mesons in the final state are studied using the framework of a generalized naive factorization approach. Branching ratios and CP asymmetries of B→Pπ(1300), B→Vπ(1300), B→Pρ(1450) and B→Vρ(1450) decays are calculated, where P and V stand for pseudoscalar and vector charmless mesons. Form factors for B→π(1300) and B→ρ(1450) transitions are estimated in the improved version of the Isgur-Scora-Grinstein-Wise quark model. In some processes, CP asymmetries of more than 10% and branching ratios of 10 -5 order are found, which could be reached in experiments. © 2012 American Physical Society.

Delgado-Acosta E.G.,University of Guanajuato | Napsuciale M.,University of Guanajuato | Rodriguez S.,Autonomous University of Coahuila
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

We develop a second order formalism for massive spin 1/2 fermions based on the projection over Poincaré invariant subspaces in the (12,0)(0,12) representation of the homogeneous Lorentz group. Using the U(1)em gauge principle we obtain a second order description for the electromagnetic interactions of a spin 1/2 fermion with two free parameters, the gyromagnetic factor g and a parameter ξ related to odd-parity Lorentz structures. We calculate Compton scattering in this formalism. In the particular case g=2, ξ=0, and for states with well-defined parity, we recover Dirac results. In general, we find the correct classical limit and a finite value rc2 for the forward differential cross section, independent of the photon energy and of the value of the parameters g and ξ. The differential cross section vanishes at high energies for all g, ξ except in the forward direction. The total cross section at high energies vanishes only for g=2, ξ=0. We argue that this formalism is more convenient than Dirac theory in the description of low energy electromagnetic properties of baryons and illustrate the point with the proton case. © 2011 American Physical Society.

Rey S.J.,Arizona State University | Sastre Gutierrez M.L.,Autonomous University of Coahuila
Applied Geography | Year: 2015

In this paper we examine the trajectory of regional income inequality dynamics for two neighboring national systems. Using data on 3038 US counties and 2418 Mexico municipios, from 2000, 2005, and 2010, we employ recent extensions of spatial Markov chains and space-time mobility measures, to consider the following questions: Are regional inequality dynamics fundamentally distinct between Mexico and the United States? Does the role of spatial context influence the distributional dynamics of the two systems? Finally we examine if there is a distinct international border region that displays inequality dynamics different from those of the internal regions of the two national systems. Strong evidence of spatial heterogeneity in regional income mobility is found between the two national systems, with Mexico having higher mobility relative to the US. The international border region is found to have distinct mobility dynamics from either national system, experiencing the strongest mobility. Extensive evidence of spatial contextual effects are found throughout the US-Mexican pooled data set indicating that a region's transitional dynamics are influenced by incomes of neighboring regions. © 2015 Elsevier Ltd.

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