Miguel Barron

Metropolitan Autonomous University | UAM · Departamento de Materiales

The stability of a ring of coupled van der Pol oscillators is studied in this work considering a non-uniform distribution of the coupling parameter along the ring. The stability analysis is based on the transformation of the linearized equation of the ring into a canonical Hill equation. A stability condition is derived considering the stability of...

An anchor-shaped geometrical design for a Submerged Entry Nozzle for the slab continuous casting of steel is presented in this work. To evaluate its performance, transient 3D multiphase numerical simulations were carried out using the Computational Fluid Dynamics technique. The performance of the proposed nozzle is numerically compared with that of...

The stirring of a molten steel ladle with argon injection through a top submerged lance and a bottom nozzle is numerically studied here through Computational Fluid Dynamics (CFD) simulations. Three lance submergence depths and three injection velocities are considered in the CFD numerical experiments. The turbulent dissipation rate is employed to c...

The horizontal and vertical velocity components of molten steel in a slab continuous casting mold produced by three different two-port Submerged Entry Nozzle (SEN) designs are monitored and compared using Computational Fluid Dynamics (CFD) simulations. These two ports designs correspond to a conventional cylindrical SEN, a plate SEN and an anchor-s...

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 t...

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, combine...

Gas injection into liquids is common in many applications. Nozzles with simple geometries are used for injecting gases, this lead to some turbulence and thus different rates of mixing and residence times. In this paper we present a study on gas injection using convergent-divergent nozzles. Gas flow through nozzles with different diameter ratios has...

The synchronized behavior of two coupled, top heated, square plates with on–off control based on plate temperature is analyzed in this work. Each plate is represented by a two dimensional heat equation, and thermal communication between the plates is modeled by a thermal resistance; each plate also has an internal point at which the temperature is...

The way in which slag density influences the slag splashing phenomenon in an oxygen steelmaking converter is numerically analyzed in this work. Several values of the density of the slag are considered, and their effect on the global mass balance and slag average volume fraction on the sidewalls of the converter is studied using isothermal, two-dime...

Copper converting is mainly conducted in Peirce–Smith converters. Extensive work has been conducted to understand fluid flow phenomena as air is injected into molten mattes. High momentum must be transferred from the gas to the melt in order to refine the metal. In this work, we present a CFD analysis of gas injection with one and three tuyeres. Re...

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...

Abrasive wear of 8620 tempered and quenched steel under aggressive conditions was inve stigated and compared with samples of 8620 steel coated by a TiN layer in the same abrasion conditions. Oil quenchin g of 8620 steel specimens was carried out at 900°C until room temperature. After quenching, the samples were tempe red below the martensitic tempe...

Chromium Nitride (CrN) thin films were deposited on steel AISI 316 substrates with reactive magnetron sputtering method. CrN films were produced under two different conditions. In the first one, the substrate was heated by a d.c. source. At the second coating was applied a negative substrate bias voltage. X ray diffraction, quantitative energy disp...

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,...

Interconnected, self-excited oscillators are often found in nature and in engineered devices. In this work, a ring of van der Pol oscillators, each of which is connected to its immediate neighbors, is considered. The focus is on the emergent behavior of a large number of oscillators. Conditions are determined under which time-independent solutions...

Introduction Experimental Development Results Conclusions

The influence of an unconventional lance with a central nozzle on the multiphase fluid flow in a steelmaking converter is studied in this work by means of computer simulations. The lance has four peripheral supersonic nozzles and a vertical central nozzle. Besides, the oxygen flow in the central nozzle is considered independent from the main oxygen...

Computational Fluid Dynamics is employed to predict the efficiency of separation of water-oil mixtures in cylindrical and square hydrocyclones. Computer simulations are conducted using the Large Eddy Simulation model for turbulence. Mass flowrates of oil are trackeded for the upper and lower exits of each hydrocyclone. Finally, the results are comp...

Some variables that influence the slag splashing phenomenon in an oxygen steelmaking converter are numerically analyzed in this work. The effect of lance height, jet velocity, jet exit angle and slag viscosity on the washing and ejection mechanisms of slag splashing is studied in this work employing two-dimensional transient computational fluid dyn...

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 behavior of four coupled self-excited elastic beams is numerically studied using the finite-difference method. Self-excitation is modeled by adding a van der Pol damping term. Coupling based on shared boundary conditions at the roots of the beams is proposed, and the influence of the coupling on the dynamics is analyzed. Time and space correlat...

It is possible that self-excited vibrations in turbomachine blades synchronize due to elastic coupling through the shaft. The synchronization of four coupled van der Pol oscillators is presented here as a simplified model. For quasilinear oscillations, a stability condition is derived from an analysis based on linearizing the original equation arou...

A nonlinear mathematical model of a vacuum-based continuous casting process and an implicit nonlinear controller are developed. The aim of the controller is the regulation of the mold and tundish molten steel levels. In the proposed approach, the output error is designed to be asymptotically stable, and the current values of the control inputs are...

The dynamic behavior and synchronization of a large ring of mutually coupled Van der Pol oscillators is studied by extending a methodology previouly reported by another authors, in which the original equations are linearized around the unperturbed limit cycle. The linearized equations are trasformed into Hill’s equations and from here conditions fo...

Chromium Nitride (CrN) thin films were deposited on AISI steel 316 substrates by means of the reactive magnetron sputtering method. CrN films were produced under two different conditions. In the first one, the substrate was heated by a DC source. For the second coating a negative substrate bias voltage was applied. X ray diffraction, quantitative e...

Recently, a new lance design for BOF steelmaking has been proposed in the literature. This lance, in addition to six peripheral inclined supersonic nozzles, contains a vertical centered nozzle whose oxygen flow is independent from the main oxygen supply. The above authors affirm that their lance maximizes the droplet generation without causing spit...

In this paper we propose the design of a novel induction furnace for glass melting. The design is based on a mathematical analysis and performed numerically by means of the Finite Element Method. Several induction coils configurations were tested. The results from the mathematical model show that it is possible to melt glass in a furnace whose hear...

Combined blowing in the steelmaking basic oxygen converter is a technique that allows more agitation in the metal bath, and gives a fast decarburization rate, accelerated removal of impurities and chemical and thermal homogenization. In this work the multiphase flow in an industrial-like basic oxygen converter with top and bottom blowing is analyze...

In this paper mathematical modeling of circuit parameters that feature the electric performance of a traveling-wave heating induction device is carried out. Rotary magnetic fields are the excitation source, and they come from axial windings having one pair of magnetic poles. The method employed for obtaining impedance parameters is based on main ma...

Many authors have pointed out that the steel superficial quality strongly depends on the operating conditions at the continuous caster mold. The analysis of the dynamic behavior of the fluid inside the mold Submerged Entry Nozzle (SEN) was done in this work by means of numerical simulations. In this work, the tundish sliding nozzle was not included...

In order to analyze the influence of a third phase in the behaviour of the free surface profile in the mould of a slab steel continuous caster, multiphase flow in a mould water model is physically and numerically investigated. A one third scale mould water model was constructed in accordance with the Froude similarity criterion. The free surface pr...

In the present work, is developed the tribologic characterization of steels AISI H-13 and D-2, submitted to nitruration ionic process to determine wear resistance in aqueous conditions. Wear test are realized with an abrasion wear tool in an aqueous environment, designed and constructed by SEPI, ESIME, IPN, according to the norm ASTM G105-89. The a...

The basic circuit parameters that feature the electric performance in induction heating devices having an excitation axial winding as found in induction motors for generating rotary magnetic fields are mathematically modeled. The followed method for obtaining impedance parameters was based on main flux decomposition to partial fluxes along differen...

A proposal for electromagnetic induction heating of molten glass at mains frequencies is mathematically modelled. The proposed assembly consists of an axial excitation winding and a cylindrical vessel containing molten glass with a central metal column, made of molybdenum or molten tin, which acts as an inner magnetic shield. Ohmic heating of the m...

The flow patterns prevailing at the free-surface in a water model of a slab continuous casting mold using several water flow rates and entry nozzle submergence depths are experimentally and numerically studied in this work. The experimental study was carried out using an one-third scale cold water model, constructed in accordance with the Froude si...

Presence oxides on sliding surfaces can greatly influence friction and wear. Oxides have been usually considered as a friction and wear reducing agent acting as a solid lubricant. Effects of pre-oxidation, carried out at different temperatures, on the tribological behaviour of a high-speed steel and a high chromium white cast iron sliding against a...

From the medical point of view it is important that the surface roughness in a knee prosthesis be small in order to reduce the wear friction due to the physical contact of the prosthesis with bone. Given the complex form of the knee prosthesis, formerly the finishing process was carried out through a manual technique. However, this technique has ma...

One of the fields of active research in dentistry today is biomaterials replacing, which is expected to be increasingly more similar to human dental enamel. As these dental materials are exposed to the diverse degrading actions present in the oral environment, it is important to know its superficial topography, which is related to the existence of...

The optimal position of the mold liquid level sensor for a continuous slab caster is experimentally studied in this work. To establish the optimal position, a 1:1/3 physical cold water model was employed. The water model was constructed in accordance with the Froude similarity criterion. The meniscus profile dispersion was evaluated at several volu...

Theoretical eddy currents at 60 Hz in molten glass, which is contained in a toroidal vessel, are analyzed when a traveling wave is imposed at its surface. Preliminary findings show that poloidal poly-phased excitation sources promote the occurrence of induced fields in relatively small volumes. Besides, thermal effects and fluid movement are studie...

The abrasive wear of 8620 borided steel under aqueous conditions was investigated. Boriding thermochemical treatment of the steel specimens was carried out at 900degreesC for 4 h in order to increase hardness and wear resistance. In these experiments, a suspension of silica sand (1.5 dm(3)) and water (0.94 dm(3)), was employed as a very agressive a...

An implicit controller for the stabilization of molten steel levels in a vacuum-based continuous caster is proposed. The controller is synthesized from the feedback linearizing approach. The output error is designed to be asymptotically stable and the values of the control inputs are numerically determined using the Newton-Rapson iterative procedur...

The temperature regulation problem of a class of continuous stirred tank reactors, where two consecutive exothermic reactions take place is addressed. Time delay control coupled with an exact sliding differentiator is used to design a discrete input−output linearizing controller. This time delay controller with sliding differentiation is robust in...

A robust control algorithm which uses partial state feedback is designed for a class of biochemical processes in the presence of modeling uncertainties. To design the controller, the model uncertainty and the nonmeasurable state are combined into a new state variable. A sliding mode state observer is used to obtain on-line estimates of this new sta...

An estimation algorithm related to the kinetics terms of the main uncertainties present in a continuous stirred tank bioreactor, is developed. This algorithm is based on a proportional-integral reduced order uncertainty observer. With the estimate generated of the uncertain term, an input-output linearizing feedback control is designed which provid...

A control scheme is proposed to regulate the level of molten steel in the mold of a continuous casting process in which the pressure in the vacuum chamber of the tundish is employed as control input. When the feedback linearising technique is employed, it yields an unusual control law, in which the link between the time derivative of the mold level...

A two-input two-output model-based controller to stabilize the molten steel level in the mold and the tundish in a one-strand continuous casting machine is developed; to stabilize the mold level, the pressure in the vacuum chamber of the tundish is employed as control input, while to stabilize the tundish level, the position of the slide-gate valve...

In this work, the LV-control problem in binary distillation columns is addressed. With least prior knowledge, a linear reference model with unknown terms is obtained. The time variations of the unknown terms are estimated using two on-line trained perceptrons. These estimates are subsequently used to design a feedback linearizing-like controller. T...

The fluid catalytic cracking (FCC) unit is one of the most complex interactive processes in the refining industry, and is difficult to operate and control. This work deals with the regulative control law design for stabilization of the reactor and regenerator temperatures, considering that the kinetics terms are poorly known. The proposed control l...

This work deals with the control and synchronization of chaotic systems. In the first part of the work, a general discrete-time strategy is developed to control a class of second-order uncertain nonlinear systems. The proposed strategy is based on an iterative procedure, borrowed from contraction map methodologies, and provides estimates of unmeasu...

In this work, a recursive nonlinear feedback control law for the regulation of the outlet substrate concentration for a fixed bed bioreactor with immobilized biomass is designed. The control algorithm is based on a reduced order model related with ordinary differential equations and only made use of a discrete substrate outlet concentration for its...

A simple methodology to determine the extent of workable regions of disturbance variables, i.e., feed temperature, inlet flow rate, and feed concentration, for a certain chemical reactor with a SISO feedback linearizing controller under constraints on control input is presented. In these relatively wide regions, the feedback linearizing controller...

A computer simulation using the finite element method is carried out in the present work to model a hot compression test. Real constitutive equations of the hot flow behaviour of a medium carbon microalloyed steel, experimentally determined, are implemented in a commercial computer code and an inverse analysis is performed to determine under which...

A MIMO model-based controller to stabilize the molten steel level in the mold and the tundish in a one-strand continuous casting machine is developed; to stabilize the mold level the pressure in the vacuum chamber of the tundish is employed as control input, while to stabilize the tundish level the position of the slide-gate valve of the ladle is u...

A continuous stirred bioreactor with open-loop periodic behavior is analyzed under closed-loop conditions, using the dilution rate as control input. In the absence of control input bounds, the limiting substrate concentration converges to set point. When stringent bounds on control input are imposed, it becomes permanently saturated; then a limit c...

In tackling the problem of liquid steel level regulation in the mold of a continuous steel caster, the values of some system parameters, such as the clogging degree and the discharge coefficients of nozzles, are seldom precisely known. The discrete control laws developed in this work employ on-line estimated values of these parameters, to produce a...

Tradicionalmente, los programas de elementos finitos de propósito general incluyen ecuaciones constitutivas idealizadas en sus modelos de deformación plástica. Esto se debe, en parte, a que no hay suficientes ecuaciones constitutivas verdaderas desarrolladas para todo tipo de aleaciones. El presente grupo de investigación ha desarrollado para un ac...

In this paper is studied the temperature regulation problem of a continuous stirred tank reactor with two consecutive and oscillatory exothermic reactions in which the heat of the reactions is unknown. A strategy to estimate the reactions' heat from measurements of reactor temperature is proposed. This strategy is coupled with a linearizing-like fe...

Bonding is a thermomechanical process employed to obtain borided layers in metal alloy, especially steels, which are extremely hard and wear resistant. Formation kinetics of such layers has been extensively studied by carrying out the process in hermetic metallic vessels which contain the bonding agent, commonly a powder and the process packed toge...

The closed-loop dynamic behavior of a chemical reactor with two consecutive and oscillatory exothermic reactions is analyzed. When bounds are imposed on the control input, equilibrium points induced by saturation (EPIS) are generated. In this case, the reactor dynamic trajectories are deviated towards the EPIS and their convergence to the set-point...

Identification and control of continuous fermentation processes are dif-ficult tasks due to the complexity and high coupling of dynamic behaviour of this kind of system. In this work is implemented an on-line estimation technique of the main uncertainties of a fermentation processes (e.g. specific growth rate, biomass concentration and yield coeffi...

We study the saturated state-feedback stabilization of a free-radical polymerization continuous reactor which must operate about an open-loop unstable point. We derive necessary and sufficient conditions for preclusion of critical points induced by saturation. The approach is constructive and yields a criteria for process and control designs. Numer...

Interconnected, self-excited oscillators are often found in nature and in en-gineered devices. In this work, a ring of van der Pol oscillators, each of which is connected to its immediate neighbors, is considered. The focus is on the emer-gent behavior of a large number of oscillators. The conditions under which time-independent solutions are obtai...