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Garay-Ramirez B.,CICATA IPN | Cruz-Orea A.,CINVESTAV | San Martin-Martinez E.,CICATA IPN
International Journal of Thermophysics | Year: 2015

Sodium acetate trihydrate (SAT) is used as a phase change material (PCM) because of its high latent heat of fusion. Mixtures were prepared with SAT, a blend of the polymer sodium carboxymethil cellulose (CMC) and silica gel, silver nanoparticles (AgNPs), and anhydrous sodium sulfate to form a composite-PCM (c-PCM) based on SAT; the relative proportions of CMC/silica gel in the blend and AgNP content were varied according to a central composite experimental design. The thermal properties were determined for raw SAT, CMC, Na2SO4, and c-PCM samples. The thermal effusivity (es) of samples was evaluated by the inverse photopyroelectric technique. The thermal diffusivity (Ds) was obtained for samples by the open photoacoustic cell technique. The thermal conductivity (ks) was calculated from the obtained es and Ds values. To assess the thermal performance of the c-PCM compared to raw SAT, samples were studied through differential scanning calorimetry which served to determine the latent heat recovery (LHR). Properties es, Ds, ks, and LHR were analyzed by response surface methodology and compared. The SAT-based c-PCM was found to be more thermally conductive than raw SAT. The best LHR with good thermal diffusivity and thermal conductivity was identified in the region of the central composite experimental design with medium–low AgNPs and higher proportions of CMC in the polymer blend. © 2015, Springer Science+Business Media New York.

Terven J.R.,CICATA IPN | Raducanu B.,CVC | Meza M.-E.,UAQ | Salas J.,CICATA IPN
Proceedings of the IEEE International Conference on Computer Vision | Year: 2016

Mirroring occurs when one person tends to mimic the non-verbal communication of their counterparts. Even though mirroring is a complex phenomenon, in this study, we focus on the detection of head-nodding as a simple non-verbal communication cue due to its significance as a gesture displayed during social interactions. This paper introduces a computer vision-based method to detect mirroring through the analysis of head gestures using wearable cameras (smart glasses). In addition, we study how such a method can be used to explore perceived competence. The proposed method has been evaluated and the experiments demonstrate how static and wearable cameras seem to be equally effective to gather the information required for the analysis. © 2015 IEEE.

Terven J.R.,CICATA IPN | Cordova-Esparza D.M.,CIDESI
Science of Computer Programming | Year: 2016

This paper introduces Kin2, a Kinect 2 toolbox for MATLAB. This toolbox encapsulates most of the Kinect for Windows SDK 2.0 functionality in a single class with high-level methods. The toolbox is written mostly in C++ with MATLAB Mex functions providing access to color, depth, infrared, and body index frames; coordinate mapping capabilities; real-time six-body tracking with 25 joints and hands states; face and high-definition face processing; and real-time 3D reconstruction. We showed that the performance of a Kin2 application decreases 30% on average with respect to a native C++ application, however, Kin reduces in one order of magnitude the average code length yielding a significant reduction in development time for prototyping and research. © 2016 Elsevier B.V.

Rodriguez-Perez M.,CINVESTAV | Chacon C.,CICATA IPN | Palacios-Gonzalez E.,Mexican Institute of Petroleum | Rodriguez-Gattorno G.,CINVESTAV | Oskam G.,CINVESTAV
Electrochimica Acta | Year: 2014

Phase-pure WO3 materials with different crystal structures and morphologies are prepared using alcoholysis and partial hydrolysis under solvothermal conditions, and their promise for photoelectrochemical water oxidation is evaluated under simulated sunlight. The materials are obtained in the hexagonal, orthorhombic and monoclinic structures. Electrophoretic deposition under ambient conditions is used to prepare mechanically stable and well-adhered films on transparent conducting glass substrates. Photoelectrochemical characterization of the films illustrates that sufficient electrical interconnectivity is achieved; however, a heat treatment at 500 °C dramatically improves the photocurrent, which is related to the passivation of defects and traps of the WO3 materials. The orthorhombic and monoclinic materials, the latter depending on the morphology and texture, achieve the highest photocurrents corresponding to water oxidation, while the hexagonal material has the lowest photocurrents. The novel orthorhombic material prepared in this work shows good promise for water oxidation, also because of the low density of electron traps as inferred from experiments under modulated illumination using a chopper. The properties of the monoclinic material depend on the morphology, in particular the texture. The electrochemical properties for a rod morphology with texture defined by the (002) or (020) reflections are characterized by lower photocurrents and a higher trap density, while a square platelets type of morphology with a texture characterized by the (002) reflection results in the highest photocurrents. The results indicate that electrophoretically deposited films of WO3 materials with shapes corresponding to two or three dimensions have better photoelectrochemical properties than one dimensional shapes such as rods and wires. © 2014 Elsevier Ltd. All rights reserved.

Mantilla A.,CICATA IPN | Tzompantzi F.,Metropolitan Autonomous University | Fernandez J.L.,CICATA IPN | Gongora J.A.I.D.,CICATA IPN | Gomez R.,Metropolitan Autonomous University
Catalysis Today | Year: 2010

ZnAlFe layered double hydroxides (LDHs) were synthesized by the co-precipitation method at different MII/MIII ratio. The solids were calcined at 723 K obtaining the respective mixed oxides with high specific surface areas (138-70 m2/g) and semiconductor properties (band gap values of 2.54-2.04 eV). The photocatalytic activity of these materials was tested for the photodegradation of aqueous solutions containing phenol and p-cresol (40 ppm), in presence of a UV light source. A disappearance of 98% of phenol and a total photodegradation of p-cresol were obtained after 6 and 4 h, respectively. © 2009 Elsevier B.V. All rights reserved.

Nieto-Perez M.,CICATA IPN | Allain J.P.,Purdue University | Heim B.,Purdue University | Taylor C.N.,Purdue University
Journal of Nuclear Materials | Year: 2011

Lithium deposition on Grade ATJ graphite substrates and metallic substrates under low-energy D2+ irradiation are compared. Transient and steady-state release rate of ejected species are measured for non-lithiated and lithiated ATJ graphite surfaces. Irradiation fluxes of order 1015 cm-2 s-1 exposed samples while ejected species are monitored with a line-of-sight quadrupole mass spectrometer. For lithiated ATJ graphite the dominant D emission channels are D2O and HDO and indicate the importance of lithium, water breakdown at the surface and oxide formation on desorption dynamics. Exponential decay in the transient release rate of ejected species is found for lithiated ATJ graphite, indicating that near surface super-saturation of D atoms at the vacuum interface in the presence of lithium atoms. In situ X-ray photoelectron spectroscopy (XPS) surface analysis corroborates this result. Lithium-coatings on Mo substrates demonstrate high sputtering rates; however depleted Li/Mo surfaces are quickly recovered when surfaces are heated to temperatures near 500 K. © 2010 Elsevier B.V. All rights reserved.

Marcano G.,University of Los Andes, Venezuela | Rincn C.,University of Los Andes, Venezuela | Lpez S.A.,University of Los Andes, Venezuela | Snchez Prez G.,University of Los Andes, Venezuela | And 3 more authors.
Solid State Communications | Year: 2011

The Raman-active phonons in semiconductor Cu2SnSe3 that crystallizes in the monoclinic structure with space group Cc were studied by measuring unpolarized Raman spectrum. The experimental Raman line wave numbers for the phonon modes were compared to those reported and to the results of lattice dynamical calculations based on simplified current models reported in the literature. From the factor group analysis of the zone-center vibrational modes, the symmetry of the observed Raman lines were tentatively assigned. The most intense A′ mode at 178 cm-1; the lowest- and highest-frequency A′ modes at 83 and 244 cm-1, respectively; A″ modes at 204, 231 and 291 cm-1; and a band at about 363 cm-1 which probably corresponds to an overtone on the strong peak at 178 cm-1, have been observed in this compound. © 2010 Elsevier Ltd. All rights reserved.

Tzompantzi F.,Metropolitan Autonomous University | Mantilla A.,CICATA IPN | Banuelos F.,Metropolitan Autonomous University | Fernandez J.L.,CICATA IPN | Gomez R.,Metropolitan Autonomous University
Topics in Catalysis | Year: 2011

ZnAl layered double hydroxides (LDHs) with different MII/M III molar ratio (0.89-3.81) were synthesized by the co-precipitation method and calcinated at 723 K. High specific surface areas (228-155 m 2/g) and semiconductor properties (band gap values from 3.32 to 3.07 eV) were obtained. The mixed oxides were reconstructed to the crystalline LDHs (memory effect) after being put in contact with aqueous solutions containing phenol and p-cresol. Using UV light, a maximum in photoactivity as a function of the Zn2+/Al3+ molar ratio was observed. The sample with a Zn2+/Al3+molar ratio of 1.48 photodegrades up to 95% of phenol and p-cresol after 4 and 6 h of irradiation, respectively. These values are lower than that obtained with ZnO and commercial P-25 TiO2 photocatalysts. The results show the applicability of alternative photocatalysts for the degradation of organic pollutant compounds rather than others such as TiO2. © 2011 Springer Science+Business Media, LLC 2011.

Vazquez-Carrillo M.G.,INIFAP CEVAMEX | Santiago-Ramos D.,PROPAC | Gaytan-Martinez M.,PROPAC | Morales-Sanchez E.,CICATA IPN | Guerrero-Herrera M.D.J.,INIFAP CIRNO
LWT - Food Science and Technology | Year: 2015

The objective of this study was to assess thermal, rheological and quality properties of grain, masa (ground nixtamalized corn), and tortillas made with high-oil maize hybrids and compare them with landraces. Grains of high-oil hybrids were harder (flotation index 10-36) with high onset, peak and final gelatinization temperatures, which were reflected in lower masa and tortilla yield. However, the tortillas had higher oil content (3.2-4.5g/100g) than those made with landraces (2.9-3.0 g/100g). Tortillas made with the yellow hybrids were softer (1.8 N). Pepitilla had the highest viscosity in grain, masa and tortillas, reflected in greater water absorption and masa and tortilla yield (1.61 kg/kg maize). A close relationship was found between G' and G″ and retained pericarp and oil content in masa; higher content of natural gums produced firmer masa with higher viscoelasticity. The high oil content in tortillas reduced their water absorption and starch swelling capacity but inhibited starch retrogradation, so they remained softer during storage. © 2014 Elsevier Ltd.

Lopez-Cervantes A.,CICATA IPN | Dominguez-Lopez I.,CICATA IPN | Barceinas-Sanchez J.D.O.,CICATA IPN | Garcia-Garcia A.L.,CICATA IPN
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2013

The effect of surface texturing on the performance of biocompatible ultra-high molecular weight polyethylene (UHMWPE) as a bearing material has been investigated using the kinematic range of motions reported for a knee-joint replacement. An experimental apparatus consisting of a ball and a disk rotating independently from each other was used to compare the performance of UHMWPE textured versus plain surfaces, under different combinations of sliding and rolling motion, better known as sliding-to-rolling ratio (SRR). Performance was evaluated through the coefficient of traction of a tribosystem comprising a steel ball on a flat UHMWPE disk and distilled water at 36. °C, acting as lubricant. A square array of cavities with diameter D=0.397. mm and center-to-center spacing of 1.5. D was machined on UHMWPE disks. The experimental design considered two levels for cavity depth, D and D/2, and two for the applied load, 17 and 25. N. The SRR was varied from 1 to 11% and the mean speed range was set from 5 to 55. mm/s, covering the kinematics and contact pressure conditions of a sauntering cycle on a knee-joint replacement. Stribeck curves of the plain and textured surfaces were obtained and compared against one another. The results demonstrate that the proposed surface pattern reduces the coefficient of traction of the tribological system for the 17. N load in the entire kinematic range explored, while for the 25. N load the effects were more noticeable at low mean speed and SRR, corresponding to the beginning of motion. © 2013 Elsevier Ltd.

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