Estrada-Medina H.,Autonomous University of Yucatán |
Graham R.C.,University of California at Riverside |
Allen M.F.,University of California at Riverside |
Jimenez-Osornio J.J.,Autonomous University of Yucatán |
Robles-Casolco S.,Puebla Institute of Technology
Plant and Soil | Year: 2013
Background and Aims: With limited soil depth in northern Yucatán (<30 cm), roots grow deeper through rock fractures and dissolution karst features (i. e., cavities, including soil-filled ones known as soil pockets). We assessed the importance of limestone bedrock and dissolution karst features on tree root growth. Methods: Fieldwork was conducted in a limestone quarry where the relative proportions of rock matrix, empty cavities, and soil pockets were calculated by observing recently exposed walls. Physical properties of rocks, topsoil, and soil pockets were analyzed. Root distribution was assessed and roots identified. Results: Soil pockets represented 9% of the rock matrix. The physical properties of rock layers were different with depth. Available water capacity is higher in soil (0. 11 m-3 m-3) than in rock layers (<0. 05 m-3 m-3). But potential available water was much higher in subsurface features than top soil. Conclusions: Dissolution karts features allow roots to grow deep into the bedrock, tapping water stored there. Although the limestone upper layer in northern Yucatan is highly restrictive to root growth, subsurface limestone layers and soil pockets are not restrictive and can hold important amounts of water. © 2012 Springer Science+Business Media B.V.
Ayon-Beato E.,CINVESTAV |
Ayon-Beato E.,Austral University of Chile |
Bravo-Gaete M.,University of Talca |
Correa F.,Leibniz University of Hanover |
And 5 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
The aim of this paper is to confirm in new concrete examples that the semiclassical entropy of a three-dimensional Lifshitz black hole can be recovered through an anisotropic generalization of the Cardy formula derived from the growth of the number of states of a boundary nonrelativistic field theory. The role of the ground state in the bulk is played by the corresponding Lifshitz soliton obtained by a double Wick rotation. In order to achieve this task, we consider a scalar field nonminimally coupled to new massive gravity for which we study different classes of Lifshitz black holes as well as their respective solitons, including new solutions for a dynamical exponent z=3. The masses of the black holes and solitons are computed using the quasilocal formulation of conserved charges recently proposed by Gim et al. and based on the off-shell extension of the ADT formalism. We confirm the anisotropic Cardy formula for each of these examples, providing a stronger base for its general validity. Consistently, the first law of thermodynamics together with a Smarr formula are also verified. © 2015 American Physical Society.
Sepulveda-Cervantes G.,Cidetec |
Portilla-Flores E.A.,Puebla Institute of Technology
Applied Mathematics and Information Sciences | Year: 2015
This work presents a novel method for haptic rendering contact force and surface properties for virtual objects using the Conformal Geometric Algebra orthogonal decomposition approach. The mathematical representation of geometric primitives along with collision algorithms based on its mathematical properties is presented. The orthogonal decomposition of contact and interaction forces is achieved using the same framework and dynamic properties in both subspaces are rendered simultaneously. Comparing with vector calculus, the Conformal Geometric Algebra (CGA) approach provides an easier and more intuitive way to deal with haptic rendering problems due to its inner properties and a simpler representation of geometric objects and linear transformation. The results of the evaluation of the method using a 3 DOF haptic device are presented. © 2015 NSP.
Majewski T.,Universidad de Las Americas Puebla |
Szwedowicz D.,CENIDET |
Melo M.A.M.,Puebla Institute of Technology
Journal of Sound and Vibration | Year: 2015
This paper presents an analysis of the automatic balancing of a rigid disk mounted on an elastic shaft. The balancing system consists of two drums at a variable distance from the disk and free balls (or rollers) inside the disk. The balls are able to change positions with respect to the rotor and compensate for rotor unbalance. This paper presents the equations of motion for the disk as well as for the balls during balancing. It is shown that the balls can compensate a part or all of the rotor unbalance depending on the positioning of the drums. There are vibratory forces that push the balls to new positions; these are responsible for the behavior of the balls and the final results. The vibratory forces are defined as a function of the system's parameters and they determine the position of equilibrium of the balls. The stability and efficiency of the method is analyzed in this paper. © 2015 Elsevier Ltd.
Polanco-Martagon S.,CENIDET |
Reyes-Salgado G.,CENIDET |
Reyes-Salgado G.,Technological Institute of Cuautla |
Flores-Becerra G.,Puebla Institute of Technology |
And 4 more authors.
Journal of Applied Research and Technology | Year: 2012
A fuzzy sets intersection procedure to select the optimum sizes of analog circuits composed of metal-oxidesemiconductor field-effect-transistors (MOSFETs), is presented. The cases of study are voltage followers (VFs) and a current-feedback operational amplifier (CFOA), where the width (W) and length (L) of the MOSFETs are selected from the space of feasible solutions computed by swarm or evolutionary algorithms. The evaluation of three objectives, namely: gain, bandwidth and power consumption; is performed using HSPICETM with standard integrated circuit (IC) technology of 0.35μm for the VFs and 180nm for the CFOA. Therefore, the intersection procedure among three fuzzy sets representing "gain close to unity", "high bandwidth" and "minimum power consumption", is presented. The main advantage relies on its usefulness to select feasible W/L sizes automatically but by considering deviation percentages from the desired target specifications. Basically, assigning a threshold to each fuzzy set does it. As a result, the proposed approach selects the best feasible sizes solutions to guarantee and to enhance the performances of the ICs in analog signal processing applications.
Patil S.S.,University of South Australia |
Patil S.S.,RMIT University |
Adetutu E.M.,University of South Australia |
Aburto-Medina A.,Puebla Institute of Technology |
And 2 more authors.
Biotechnology Letters | Year: 2014
Chlorinated ethenes are of environmental concern with most reports of successful microbial-mediated remediation being associated with major dechlorinating groups such as Dehalococcoides (Dhc) species. However, limited information is available on the community dynamics and dechlorinating activities of indigenous non-Dhc groups. Here, we present evidence of dechlorination of tetrachloroethene (perchloroethylene, PCE) in groundwater samples by indigenous microbial communities. 100 % PCE conversion to ethene was observed in acetate-stimulated 24 week-microcosms (controls; 15 %). Microbial community profiles showed dominance by groups such as Proteobacteria, Spirochaetes, Firmicutes, Methanomicrobiaceae and Methanosarcinaceae. Pareto-Lorenz (PL) analyses suggested an adapted (45 % PL value) but variable bacterial community (55.5 % Δt(week)) compared to Archaea (25 % PL value; 46.9 % Δt(week)). Our findings provide evidence of dechlorinating potential of indigenous microorganisms and useful information on their dynamics which may be exploited for in situ groundwater bioremediation. © 2013 Springer Science+Business Media Dordrecht.
Mejias-Brizuela N.Y.,National Institute of Astrophysics, Optics and Electronics |
Olivares Perez A.,National Institute of Astrophysics, Optics and Electronics |
Grande Grande A.,Puebla Institute of Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010
We present the behaviors in the time of the diffraction efficiency of holographic gratings, there were recorded in two monosaccharides, glucose and fructose, and both were sensitized with potassium dichromate and blue dye. There monosaccharides present diffraction efficiency with a maximum of 7% approximately, without protection, the sample exposure at environmental conditions, after 48 hours the parameter of diffraction efficiency decays. By this reason is necessary to protect after of the stabilized emulsion the hologram. © 2009 Copyright SPIE - The International Society for Optical Engineering.
Valdez S.,National Autonomous University of Mexico |
Pech-Canul M.I.,CINVESTAV |
Ascencio-Gutierrez J.A.,National Autonomous University of Mexico |
Casolco S.R.,Puebla Institute of Technology
International Journal of Electrochemical Science | Year: 2013
The chemical composition of metallic AlZnAg alloy is related with microstructure in order to know their influence on electrochemical degradation. The microstructure has been characterized by high transmission electron microscopy with energy-dispersive X-ray. The electrochemical behavior has been tested by potentiodynamic polarization tests. In addition, weight loss analysis was carried out for the corrosion rate. In electrochemical tests the results showed the significant influence of silver concentration on the dissolution reactions of Al-matrix, solid solution rich-Zn, and AgZn3 precipitate phase. The electrochemical investigation shows that the corrosion rate increases with the silver additions. Likewise, it was moreover evidenced the development of a film passive layer for the maximum silver content alloys; the passivity of this cover could be broken due to the existence of precipitate phase AgZn3. Based on this behavior the AgZn3 particles, and microstructural phases play a significant role in the corrosion process for the metallic AlZn alloys. © 2013 by ESG.
Vergara-Betancourt A.,Autonomous University of Puebla |
Vergara-Betancourt A.,Puebla Institute of Technology |
Marti-Panameno E.,Autonomous University of Puebla |
Luis-Ramos A.,Autonomous University of Puebla |
Parada-Alfonso R.,National Polytechnic Institute of Mexico
Journal of Optics (United Kingdom) | Year: 2013
Based on numerical techniques, in this paper, we study light propagation in two types of waveguide arrays. One array contains hexagonal cells, and the second contains honeycomb cells. The waveguides demonstrate the well-confined mode condition and possess Kerr nonlinearity. The mathematical model is based on the modified discrete nonlinear Schrödinger equation, which allows us to evaluate the influence of the array geometry on nonlinear light propagation, primarily the process of discrete soliton formation. The main conclusion involves the role of the coupling length; the greater the coupling length, the lower the power threshold required for discrete soliton formation. © 2013 IOP Publishing Ltd.
Jaime V.B.J.,Puebla Institute of Technology
International Journal of ChemTech Research | Year: 2014
A series of ferrocenylmono-and dichalcone derivatives have been synthesized under solvent-free conditions via Claisen-Schmidt condensations between aryl/ferrocenyl ketones and aryl/ferrocenyl aldehydes by just grinding in an agate mortar. All the reactions occur in a short time with excellent yields (>85%) of steroselective trans-conformation in the chalcones. The structures of all the compounds have been characterized by FT-IR, 1H NMR, 13C NMR and EI-MS and elemental analyses.