Garcia J.C.,University of Huelva |
Zamudio M.A.M.,University of Huelva |
Perez A.,University of Huelva |
De Alva H.E.,Technological Institute of Ciudad Madero |
Lopez F.,University of Huelva
Journal of Chemical Technology and Biotechnology | Year: 2011
BACKGROUND: A central composite experimental design and multiple regression were used to model the production of pulp and paper sheets from a Paulownia fortunei × tormentosa × elongata trihybrid clone. Also, the same experiments were carried out with the solid phase after autohydrolysis of the raw material. RESULTS: The results were compared with those obtained from the solid phase remaining after autohydrolysis of the raw material with a view to optimizing the use of hemicelluloses and cellulose by fractionation. Pulp and paper sheets from the trihybrid clone surpass those from other Paulownia species such as P. fortunei and P. elongata in physical properties such as tensile index (11.6-49.1 Nm g-1), burst index (0.23-2.41 MPa m2 kg-1), tear index (0.71-3.03 mN m2 g-1) and intrinsic viscosity (427-958 cm3 g-1). CONCLUSIONS: The solid phase obtained by autohydrolysis of the Paulownia trihybrid provides pulp and paper sheets comparable in strength-related properties with those of pulp directly produced from the raw material, but using substantially milder operating conditions and with the added advantage that the autohydrolysis treatment provides highly valorizable liquor. © 2011 Society of Chemical Industry.
Moctezuma E.,Autonomous University of San Luis Potosi |
Zermeno B.,Autonomous University of San Luis Potosi |
Zermeno B.,Technological Institute of Ciudad Madero |
Zarazua E.,Autonomous University of Nuevo León |
And 2 more authors.
Topics in Catalysis | Year: 2011
Iron titanate (FeTiO3) obtained from rich titanium and iron mineral presented some absorption of UV light and photocatalytic activity for the degradation of phenol in aqueous solution. However, most of the reactant is converted to carboxylic acids that remain in the reaction mixture because natural ilmenite do not produce enough HO• radicals to completely mineralize the original reactant at the same rate as pure titania (Degussa P25). The XRD analysis of Fe-titania catalysts prepared by simple mixing of FeTiO3 and TiO2 showed that the structure of TiO2 is not modified when small amounts of FeTiO3, in the order of 10% weight, are well mixed with pure titania. Therefore, the photocatalytic activity of these catalysts is not affected by the presence of FeTiO3. But, heavy ilmenite particles induce the separation of the catalysts particles after the photocatalytic degradation processes. © 2011 Springer Science+Business Media, LLC.
Rosas-Caro J.C.,Technological Institute of Ciudad Madero |
Mancilla-David F.,University of Colorado at Denver |
Ramirez-Arredondo J.M.,CINVESTAV |
Bakir A.M.,University of Colorado at Denver
IET Power Electronics | Year: 2012
This study presents a topology for a pulse width modulated (PWM) three-phase voltage regulator that uses only two driving switches, providing high reliability and making the switching stage simpler and cheaper compared with other available configurations. The proposed topology is suitable for voltage regulation on the distribution power system. It is able to regulate the steady-state voltage and to reject voltage variations such as flicker or sags caused by large motors start. In addition, the compensator features a topology free of energy storage elements. The PWM control is based on dc signals, asynchronous from the grid, simpler than the control used for traditional voltage source converters - it does not require a phase-locked loop, and does not involve trigonometric calculations. As a result of this, the controller can be achieved with an analogue controller or a low-cost microcontroller. The proof of concept is performed with a 220 V three-phase voltage regulator, which is simulated and prototyped in the laboratory. © The Institution of Engineering and Technology 2012.
PubMed | UPEMOR, Technological Institute of Ciudad Madero and Autonomous University of Coahuila
Type: | Journal: Advances in bioinformatics | Year: 2016
A new hybrid Multiphase Simulated Annealing Algorithm using Boltzmann and Bose-Einstein distributions (MPSABBE) is proposed. MPSABBE was designed for solving the Protein Folding Problem (PFP) instances. This new approach has four phases: (i) Multiquenching Phase (MQP), (ii) Boltzmann Annealing Phase (BAP), (iii) Bose-Einstein Annealing Phase (BEAP), and (iv) Dynamical Equilibrium Phase (DEP). BAP and BEAP are simulated annealing searching procedures based on Boltzmann and Bose-Einstein distributions, respectively. DEP is also a simulated annealing search procedure, which is applied at the final temperature of the fourth phase, which can be seen as a second Bose-Einstein phase. MQP is a search process that ranges from extremely high to high temperatures, applying a very fast cooling process, and is not very restrictive to accept new solutions. However, BAP and BEAP range from high to low and from low to very low temperatures, respectively. They are more restrictive for accepting new solutions. DEP uses a particular heuristic to detect the stochastic equilibrium by applying a least squares method during its execution. MPSABBE parameters are tuned with an analytical method, which considers the maximal and minimal deterioration of problem instances. MPSABBE was tested with several instances of PFP, showing that the use of both distributions is better than using only the Boltzmann distribution on the classical SA.
Brachetti-Sibaja S.B.,Technological Institute of Ciudad Madero |
Brachetti-Sibaja S.B.,Altamira |
Dominguez-Crespo M.A.,Altamira |
Torres-Huerta A.M.,Altamira |
And 2 more authors.
Journal of the Electrochemical Society | Year: 2012
Rare earth conversion films were obtained on the AA6061 aluminum alloy by the immersion method varying several experimental conditions such as rare earth (RE) concentration, bath temperature and immersion time. Formation dynamics of RE coatings and the effect of bath conditions on their structure, morphology, topography and corrosion resistance properties were investigated for the protection of this substrate immersed in an aqueous solution of NaCl. X-ray diffraction and scanning electron microscopy results revealed that the increment of the RE concentration caused some small cracks around the aluminum alloy intermetallic phase, whereas bath temperature and immersion time stimulated the conversion of the rare earths to more stable compounds, La 2O 3 and CeO 2. During electrochemical evaluation, the CeCCs displayed a steady state potential at times longer than 250 min; as for LaCCs, longer time intervals were required to reach a stable potential. After covering with rare earth conversion films, the anticorrosive properties of the aluminum alloy were evidently improved. This enhancement is presumably due to the improved barrier properties of the anticorrosion product layer. Additional active corrosion protection was originated from the inhibiting action of the lanthanide ions trapped either as oxides or hydroxides in this surface layer. © 2011 The Electrochemical Society.
Centeno G.,Mexican Institute of Petroleum |
Centeno G.,Technological Institute of Ciudad Madero |
Ancheyta J.,Mexican Institute of Petroleum |
Alvarez A.,Mexican Institute of Petroleum |
And 4 more authors.
Fuel | Year: 2012
Different feedstocks (7-21°API gravity, 300-450 ppm Ni + V) were hydrotreated in a bench-scale reactor at moderate reaction conditions (70 kg/cm 2, 5000 ft 3/bbl H 2/oil ratio, 0.5 h -1 LHSV) to study the deactivation of a NiMo/γ-Al 2O 3 commercial catalyst. The experiments were carried out at three temperatures (380, 400 and 420 °C) and samples were taken every 10 h during 240 h of time-on-stream and characterized for sulfur, metals and asphaltenes contents. The conversion of impurities resulted higher as the temperature was increased. The properties of the feed and of their asphaltenes were found to have a great impact on catalyst deactivation. A deactivation model considering both metals and carbon depositions was used to fit the data. Good agreement of the overall trend of experimental and predicted deactivation curves was observed. © 2012 Elsevier Ltd. All rights reserved.
Quiroz-Castellanos M.,Technological Institute of Ciudad Madero |
Cruz-Reyes L.,Technological Institute of Ciudad Madero |
Torres-Jimenez J.,CINVESTAV |
Gomez S. C.,Technological Institute of Ciudad Madero |
And 2 more authors.
Computers and Operations Research | Year: 2014
In this study, the one-dimensional Bin Packing Problem (BPP) is approached. The BPP is a classical optimization problem that is known for its applicability and complexity. We propose a method that is referred to as the Grouping Genetic Algorithm with Controlled Gene Transmission (GGA-CGT) for Bin Packing. The proposed algorithm promotes the transmission of the best genes in the chromosomes without losing the balance between the selective pressure and population diversity. The transmission of the best genes is accomplished by means of a new set of grouping genetic operators, while the evolution is balanced with a new reproduction technique that controls the exploration of the search space and prevents premature convergence of the algorithm. The results obtained from an extensive computational study confirm that (1) promoting the transmission of the best genes improves the performance of each grouping genetic operator; (2) adding intelligence to the packing and rearrangement heuristics enhances the performance of a GGA; (3) controlling selective pressure and population diversity tends to lead to higher effectiveness; and (4) GGA-CGT is comparable to the best state-of-the-art algorithms, outperforming the published results for the class of instances Hard28, which appears to have the greatest degree of difficulty for BPP algorithms. ©2014 Elsevier B.V. All rights reserved.
Barron C. A.E.,Technological Institute of Ciudad Madero |
Melo-Banda J.A.,Technological Institute of Ciudad Madero |
Dominguez E. J.M.,Mexican Institute of Petroleum |
Hernandez M. E.,Technological Institute of Ciudad Madero |
And 3 more authors.
Catalysis Today | Year: 2011
Forecasting studies based upon Hubbert's type multicyclic calculations indicate a progressive declining of most of the fossil oil sources worldwide after reaching a production maximum . In the near future scenario the search of renewable alternate fuels sources will be of increasing importance, for example agrofuels, which are fuel grade derivates of vegetable oils; thus, this work deals with newer catalysts for selective hydrocracking of long hydrocarbons chains derived from safflower oil, i.e., heterogeneous catalysts supported on mesoporous SBA-15 were prepared and tested for hydrocracking of the unsaturated oil. For this, a series of catalysts based upon Ni-Mo, Ni-W carbides, Pt and triflic acid were characterized by N2 physisorption (BET), X-ray diffraction (XRD), transmission electron microscopy (TEM) and pyridine adsorption-DRIFTS. In parallel, their activity, selectivity and operation conditions were followed and the reaction products were analyzed by GC. The viscosity and API density of the liquid products thus obtained were classed as products equivalent to medium crude oil fractions. Naphtha (C5-C 9) was produced with a total yield in the interval 15-30 wt.%, while light products represented less than 5 wt.%. Two outstanding catalysts based upon trifluoromethanesulfonic acid produced naphtha and light compounds with a yield higher than 30% and 15%, respectively, which indicates the strong influence of the surface acidic active sites on the cracking reactions of long chain hydrocarbons derived from vegetable oils. © 2011 Elsevier B.V. All rights reserved.
Barron Cruz A.E.,Technological Institute of Ciudad Madero |
Melo Banda J.A.,Technological Institute of Ciudad Madero |
Mendoza H.,Technological Institute of Ciudad Madero |
Ramos-Galvan C.E.,Technological Institute of Ciudad Madero |
And 2 more authors.
Catalysis Today | Year: 2011
Biodiesel is synthesized via the transesterification of lipid feedstocks with low molecular weight alcohols. Industrially, alkaline bases such as sodium and potassium hydroxides (NaOH-KOH) are used to catalyze the reaction. These catalysts require anhydrous conditions and feedstocks with low levels of free fatty acids (FFAs). Water in the reaction promotes the formation of FFAs, which can deactivate the catalyst and produce soap, an undesirable byproduct. Strong liquid acids are less sensitive to FFAs and can simultaneously conduct esterification and transesterification reactions. Solid catalysts based on Ni and Pt supported on mesoporous materials (SBA-15 and SBA-16) were tested in the synthesis of biodiesel by transesterification of a vegetable oil via acid catalysis. Textural and structural proprieties of the catalysts were characterized by N2 physisorption (BET method), X-ray diffraction (XRD), and Transmission electron microscopy (TEM); the textural properties and XRD results showed the characteristic properties of mesoporous materials. The Cetane Index of the biodiesel obtained was tested and compared against the Cetane Index of conventional petroleum-based diesel. ASTM techniques used as comparison analysis for the synthetic biodiesel showed better properties than conventional diesel. © 2011 Elsevier B.V. All rights reserved.
Mar-Hernandez E.,Technological Institute of Ciudad Madero |
Gonzalez-Escobar M.,CICESE |
International Geology Review | Year: 2012
Tiburon Basin is characterized by a thick sedimentary fill that records the evolution of one of the rift segments of the East Pacific Rise. Its structure corresponds to an echelon pull-apart basin bounded by two dextral-oblique faults. Unlike basins in the southern Gulf of California that are underlain by oceanic crust, rift basins in the northern Gulf of California contain sedimentary thickness (up to 6 km) that masks the structure of the crust. To study the architecture of the Tiburon Basin, two-dimensional, multichannel seismic reflection data collected by Petróleos Mexicanos (PEMEX) in the early 1980s were used. The data base is a grid of lines, 5-20 km apart, with 6s of record in 48 channels. Additional seismic data of the Ulloa 99 project were also interpreted. Our results indicate that the general structural pattern of the Tiburon Basin is controlled by two dextral-oblique faults: De Mar and Tiburon. De Mar lies to the east and ends in elevated basement transferring the stress to the Desemboque fault. The latter borders the incoming basement from the Sonora and Tiburon faults to the west, ending to the north in an antiform. Four structural domains are recognized: (1) the northern Tiburon domain is a high basement that divides the Delfin Basin to the northeast and exhibits extensional folds with their axes parallel to the basement and its flanks; (2) the Libertad domain is a sheared basement high along the margin of Sonora and forms the right step of the Tepoca Basin to the north; (3) the Tiburon central domain defines a broad sag cut by a dense NE-striking pattern of normal faults with opposed dips in the depocentre and abruptly ends to the west against the Tiburon fault; and (4) the southern Tiburon domain forms a basement ramp offshore Isla Tiburon and is controlled by a pattern of NNE-striking normal faults on the south that likely connect at an oblique angle (60) to the De Mar fault. We propose a rhombochasm basin model with more than 6s of sedimentary record in the depocentre, in which the basement is not recorded. The NW-trending faults in the Libertad domain possibly continue towards the Sonora coastal plain. The principal NW-trending dextral faults and the secondary NNE-striking pattern of normal faults cut the shallow strata of this domain. © 2012 Taylor & Francis.