oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Search Results: 1 - 10 of 3595 matches for " Cabrera Hilerio "
All listed articles are free for downloading (OA Articles)
Page 1 /3595
Display every page Item
Morfogénesis in vitro de dioon merolae de Luca, Sabato & Vázquez-Torres (zamiaceae, cycadales) a partir de megagametofitos y embriones cigóticos
Cabrera Hilerio,Sandra Luz; Chávez ávila,Victor Manuel; Sandoval Zapotitla,Estela; Litz,Richard E; Cruz Sosa,Francisco;
Interciencia , 2008,
Abstract: organogenic cultures were induced from zygotic embryo and megagametophyte explants of the chiapas state (méxico) endangered cycad species, dioon merolae. the litz induction medium consisted of b5 major salts, ms medium minor salts and the organics glutamine (400mg·l-1), arginine (100mg·l-1), asparagines (100mg·l-1), sucrose (60g·l-1), gellan gum (4g), and supplemented with 0, 0.45, 2.26, 4.52 and 9.05μm 2,4-dichlorophenoxyacetic acid (2,4-d) and 0, 2.32, 4.60, 9.30, 13.90μm kinetin (k), arranged as a 5′5 factorial in a randomized block design. cultures were maintained in darkness at 25°c, and callus was subcultured onto fresh medium at 4 week intervals. callus initiation occurred on a wide range of plant growth regulators (pgr) combinations from megagametophyte explants. in comparison, callus initiation from explanted zygotic embryos occurred on few pgr combinations. adventitious shoot induction occurred from callus on formulations with k and 2,4-d. through the histological analysis of longitudinal sections of zygotic embryos were detected apical meristematic cells of the shoot and root and in megagametophytes the formation of elements similar to tracheids and coralloid roots. this technique has a great potential for preservation of the highly endangered cycads.
A Feedforward Controller to Regulate the Chemical Composition of Molten Steel in a Continuous Casting Tundish  [PDF]
Miguel A. Barron, Dulce Yolotzin, Isaias Hilerio
Intelligent Control and Automation (ICA) , 2013, DOI: 10.4236/ica.2013.43029
Abstract:

A feedforward controller for the automatic regulation of chemical composition of molten steel in the tundish of a continuous casting machine is proposed in this work. The flow of molten steel inside the tundish is modeled as a distributed parameter system, and the resulting partial differential equation is transformed into a set of ordinary differential equations by means of the finite differences technique. From the above set and using a proper boundary condition, a feedforward control law is synthesized. No experimental tests are reported, however, the dynamic performance of the controller is illustrated by means of numerical simulations.

CFD Analysis of Influence of Slag Viscosity on the Splashing Process in an Oxygen Steelmaking Converter  [PDF]
Miguel A. Barron, Dulce Y. Medina, Isaias Hilerio
Modeling and Numerical Simulation of Material Science (MNSMS) , 2013, DOI: 10.4236/mnsms.2013.33012
Abstract: Physical properties of molten slag such as viscosity, density and surface tension have a significant influence on the slag splashing process in an oxygen steelmaking converter. Particularly, viscosity determines the shear forces that rule droplets formation. Besides, stirring of the molten slag bath strongly depends on this property. In this work, the influence of viscosity on the efficiency of slag splashing is explored by means of transient Computational Fluid Dynamics simulations. Several values of viscosity are employed in the computer experiments. In order to quantify the splashing efficiency as function of slag viscosity, an average slag fraction on the converter walls is defined and calculated. CFD results are compared with those of an empirical expression, and at least qualitative agreement is found.
Collective Behavior of a Ring of Van Der Pol Oscillators under Gaussian and Random Coupling Schemes  [PDF]
Miguel A. Barron, Dulce Y. Medina, Isaias Hilerio
Open Journal of Applied Sciences (OJAppS) , 2014, DOI: 10.4236/ojapps.2014.47036
Abstract: The collective behavior of a ring of coupled identical van der Pol oscillators is numerically studied in this work. Constant, gaussian and random distributions of the coupling parameter along the ring are considered. Three values of the oscillators constant are assumed in order to cover from quasilinear to nonlinear dynamic performance. Single and multiple coupled frequencies are obtained using power spectra of the long term time series. Phase portraits are obtained from numerical simulations, and the coupled behavior is analyzed, compared and discussed.

Numerical Simulation of Decarburization in a Top-Blown Basic Oxygen Furnace  [PDF]
Miguel A. Barron, Dulce Y. Medina, Isaias Hilerio
Modeling and Numerical Simulation of Material Science (MNSMS) , 2014, DOI: 10.4236/mnsms.2014.43011
Abstract:
An improved mathematical model to describe the decarburization process in basic oxygen furnaces for steelmaking is presented in this work. This model takes into account those factors or parameters that determine the bath-oxygen impact area, such as the cavity depth, the lance height, the number of nozzles and the nozzles diameter. In the thermal issue, the model includes the targeted carbon content and temperature. The model is numerically solved, and is validated using reported data plant. The oxygen flow rate and the lance height are varied in the numerical simulations to study their effect on the carbon content and decarburization rate.
Modeling and Simulation of Hot Metal Desulfurization by Powder Injection  [PDF]
Miguel A. Barron, Isaias Hilerio, Dulce Y. Medina
Open Journal of Applied Sciences (OJAppS) , 2015, DOI: 10.4236/ojapps.2015.56030
Abstract: The desulfurization of hot metal by the mono-injection of lime powder and the co-injection of lime, calcium carbide and magnesium powders is mathematically modeled. The mono-injection model is derived from the continuity equation and is validated using experimental results and data previously reported in the literature. The co-injection model and the rate constant of the injected mixture are determined from the molar fractions and rate constants of the individual powders. The effect of the lime content of the mixture on the desulfurization dynamics is studied and discussed.
Slag Splashing in a Basic Oxygen Furnace under Different Blowing Conditions  [PDF]
Miguel A. Barron, Isaias Hilerio, Dulce Y. Medina
Open Journal of Applied Sciences (OJAppS) , 2015, DOI: 10.4236/ojapps.2015.512078
Abstract: The influence of three different blowing conditions on the slag splashing process in a basic oxygen furnace for steelmaking is analyzed here using two-dimensional transient Computational Fluid Dynamics simulations. Four blowing conditions are considered in the computer runs: top blowing, combined blowing using just a bottom centered nozzle, combined blowing using two bottom lateral nozzles, and full combined blowing using the three top and the three bottom nozzles. Computer simulations show that full combined blowing provides greater slag splashing than conventional top blowing.
Computer Analysis of a Methane Fired Crucible Furnace  [PDF]
Fernando Santiago, Miguel A. Barron, Isaias Hilerio, Dulce Y. Medina
Open Journal of Applied Sciences (OJAppS) , 2018, DOI: 10.4236/ojapps.2018.86017
Abstract: Two design factors and one operation parameter of a methane fired crucible furnace are numerically explored in this work. These are the number of burners, the location of the exhaust gas exit, and the air-fuel ratio, respectively. Three dimensional steady state Computational Fluid Dynamics simulations are carried out in order to analyze the influence of the above factors on the mean cavity temperature in absence of thermal load, the methane content and the oxygen content of the exit gas.
Computer Simulation of the Multiphase Flow in a Peirce-Smith Copper Converter  [PDF]
Oscar Barrios, Miguel A. Barron, Dulce Y. Medina, Isaias Hilerio
Open Journal of Applied Sciences (OJAppS) , 2018, DOI: 10.4236/ojapps.2018.87022
Abstract: The multiphase flow in a Peirce-Smith copper converter is numerically explored in this work. Molten matte, molten slag and air are the phases considered. The transient partial differential equations that constitute the mathematical model are discretized using a two-dimensional computational mesh. The Computational Fluid Dynamics technique is employed to numerically solve the discretized equations. The aim of the numerical analysis is to study the influence of the nozzle height on the phase distributions inside the converter. Three values of the nozzle heights are considered.
Numerical Analysis of Oscillation Death in Coupled Self-Excited Elastic Beams
Miguel A. Barron,Isaias Hilerio,Gabriel Plascencia
Advances in Mechanical Engineering , 2012, DOI: 10.1155/2012/746537
Abstract: The emergence of the oscillation death phenomenon in a ring of four coupled self-excited elastic beams is numerically explored in this work. The beams are mathematically represented through partial differential equations which are solved by means of the finite differences method. A coupling scheme based on shared boundary conditions at the roots of the beams is assumed, and as initial conditions, zero velocity of the first beam and three normal vibration modes of a linear elastic beam are employed. The influence of the self-exciting constant on the ring dynamics is analyzed. It is observed that oscillation death arises as result of the singularity of the coupling matrix. 1. Introduction In the past years the collective behavior of coupled nonlinear oscillators has been widely studied in many disciplines, for example, physics [1], biology [2], ecology [3], chemistry [4], and mechanics [5]. A wide diversity of nonlinear dynamic phenomena such as locking [1], partial synchronization [6], full synchronization [7], antiphase synchronization [8], and clustering [9] have been reported in coupled oscillators. Many coupling schemes have also been tested: local [10], nearest [11], global [12], diffusive [13], adaptive [14], delayed [15], hierarchical [16], and so on. An interesting behavior of coupled oscillators is amplitude death and oscillation death, which are steady states where the coupled oscillators stop their oscillation in a permanent way and become frozen in time [17–19]. Sometimes this cessation of oscillations in time is named quenching [20]. Amplitude death arises through a Hopf bifurcation mechanism in coupled oscillators with an important parameter mismatch or in identical oscillators with time delays [21]. An already existing unstable steady state with zero amplitude is transformed by the coupling into a stable one allowing its observation; that is, the coupling induces stability at the origin of the phase space. On the other hand, oscillation death occurs through a saddle-node bifurcation mechanism allowing the emergence of new fixed points: a new stable steady state with nonzero amplitude is created by the coupling [19, 21]. Frequently, in the literature amplitude death is confused with oscillation death [22–27]. Even the famous finding of Lord Rayleigh [28] related to the quenching of two organ pipes standing side by side is indistinctly considered as amplitude death or oscillation death [29]. To date, in spite of the significant conceptual and technical differences between amplitude death and oscillation death, there is not yet a clear
Page 1 /3595
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.