Showing papers by "Instituto Tecnológico de Morelia published in 2006"

High-efficient integrated electronic ballast for compact fluorescent lamps

Abstract: In this paper, a single-stage high-power-factor high-efficiency electronic ballast for compact fluorescent lamps is presented. The proposed topology uses two voltage sources connected in series to feed the inverter ballasting the lamp, one of them consists in the rectified line voltage and the other in a dc-dc converter operating in discontinuous conduction mode. In this way, the converter processes a lower energy than the nominal power of the lamp. The proposed topology presents simplicity, high-power-factor, low current crest factor, and high efficiency.

Delta robot: Inverse, direct, and intermediate Jacobians

Abstract: In the context of a parallel manipulator, inverse and direct Jacobian matrices are known to contain information which helps us identify some of the singular configurations. In this article, we employ kinematic analysis for the Delta robot to derive the velocity of the end-effector in terms of the angular joint velocities, thus yielding the Jacobian matrices. Setting their determinants to zero, several undesirable postures of the manipulator have been extracted. The analysis of the inverse Jacobian matrix reveals that singularities are encountered when the limbs belonging to the same kinematic chain lie in a plane. Two of the possible configurations which correspond to this condition are when the robot is completely extended or contracted, indicating the boundaries of the workspace. Singularities associated with the direct Jacobian matrix, which correspond to relatively more complicated configurations of the manipulator, have also been derived and commented on. Moreover, the idea of intermediate Jacobian matrices have been introduced that are simpler to evaluate but still contain the information of the singularities mentioned earlier in addition to architectural singularities not contemplated in conventional Jacobians.

Microbiologically influenced corrosion of steels by thermophilic and mesophilic bacteria

Abstract: Bacterial influenced corrosion of AISI 316 stainless steels (SS) and ASTM A36 carbon steel by two strains of sulfate reducing bacteria (SRB) were analyzed. Thermophilic and mesophilic bacteria were isolated from the condensate fluid of "Los Azufres", a geothermal electric field located in the State of Michoacan at Central Mexico. Anaerobic corrosion tests were carried out for 15, 30 and 60 days in lactate-containing media at 50 °C and 40 °C. Scanning electron microscopy (SEM) was used to determine corrosion morphology. Pitting density was determined with an optical microscope. Corrosion potential, anodic potentiodynamic polarization curves and pH values were measured under anaerobic conditions. Results show that the microbial activity influenced the overall corrosion process, whereas, pitting corrosion and localized attack corrosion (LAC) were found. The anodic polarization curves show that passivation and activation processes should take place on the steel surface of the sample and pH decreases as the exposure time increases.

A machine-vision system to measure the parameters describing the performance of a Foucault pendulum

Abstract: We describe a machine-vision system that makes real-time measurements of the kinematics of a Foucault pendulum Images are taken from a downward-facing camera placed close to the pendulum suspension point The bob is detected via background subtraction and located by fitting circles to the resulting contour segments The bob trajectory is then modelled by fitting ellipses to recent positions Parameters are improved through Kalman filtering Experimental results are shown Our implementation is a robust and accurate tool for visualization of the pendulum kinematics as well as troubleshooting and maintenance of the mechanical elements

Morphological Variations of Gall-Forming Insects on Different Species of Oaks (Quercus) in Mexico

Abstract: The knowledge of the interaction between gall-forming insects and oaks in Mexico is still very poor. However, the results presented in this chapter indicate that Mexican oaks have great gall morph diversity, and that external and internal gall morphology is structurally variable. More studies on gallwasp taxonomy, gall morphology and physiology are necessary to understand the adaptive significance of gall induction in oaks of temperate and tropical forests. Hybrids have the potential to act as new adaptive zones for the diversification of wasp species. Considering that hybridization is one of the main factors explaining the striking species richness of Mexican oaks, many gall-forming insects are also expected to have coevolved. Co-phylogenetic studies on Mexican oaks are now underway, and particularly aim at comparing endemic species with a restricted distribution to species with wider latitudinal and altitudinal distributions. This analysis is expected to contribute to our understanding of the co-evolutionary dynamics of this interaction at different spatial scales. Gall-forming insects associated to oaks may represent even greater species richness than found among oak species themselves. Therefore, this should be considered an important biodiversity component, which has its own specific conservation requirements within the diverse Mexican montane oak forests.

Desarrollo de simuladores para procesos industriales. Parte II (Colada continua)

Abstract: This work was written for illustrating the use of Monte Carlo methods and generating of random number in combination with the information of the simulation system for thermal behavior described previously in order to reproduce in a computer the solidification process of the steel and simulate the formation of structures of casting step by step.

Energy Generation and Discharge for a Semiautomatic Defibrillator EBT

Abstract: In this work the main consideration of the design of truncated biphasic exponential external defibrillator appear. The equipment is directed to the treatment of cardiac arrest by ventricular fibrillation. The structure of the defibrillator account with two main processes: the charge stage and the discharge stage. For the charge stage is used a Flyback topology controlled to constant frequency with a current sensor in primary and a voltage sensor in secondary of the Flyback transformer. The energy is stored in a bank of capacitors in a time from 6 to 15 sec., according to the defibrillators charge standards. For the discharge stage a H bridge is proposed to handle to high voltages with commercial devices. H Bridge allows to generate the biphasic exponential truncated waveform and to modulate the energy. The results of the proposed approach in a prototype of small signal appear.

Modelación matemática del mezclado en ollas (cucharas) de aluminio equipadas con la técnica de desgasificación rotor-inyector

Abstract: In this work a fundamental Eulerian mathematical model was developed to study fluid flow and mixing phenomena in aluminum ladles equipped with impeller for deshidrogenization treatment. The effect of critical process parameters such as rotor speed, depth of immersion, gas flow rate, and type of rotor on the mixing behavior and vortex formation was analyzed with this model. The model simulates operation with and without gas injection and it was developed on the commercial CFD code PHOENICS 3.4 in order to solve all conservation equations governing the process, i.e. continuity, 3D turbulent Navier-Stokes and the k-e turbulence model for a two-phase fluid flow problem using the Inter Phase Slip Algorithm (IPSA). In order to realistically represent the process, shape of the furnace and three kinds of impellers were drawn by employing Body Fitted Coordinates (BFC). From the results it was concluded that mixing behavior is highly dependent on the rotor speed and on the rotor type. Mixing time is improved when: 1) Impeller is located at a depth of 0.229m into the aluminum bath, 2) By using high rotor speeds, 3) By using ladles with a high aspect ratio of Diameter to Height, and 4)By using an impeller with notches.

Analytical Method for Calculating Steady-State Initial Value Conditions of Dynamic Periodic Networks with Nonlinear Components

Abstract: In electrical networks, the calculation of steady-state responses and boundary conditions are of fundamental importance. Conventionally, the steady-state can be obtained in the time domain through the solution of the resulting set of ordinary differential equations until the transient state dies-out. In many electric networks, this process can take long and computationally expensive simulation times. This article presents an analytical methodology to obtain steady-state response and boundary value conditions. The methodology is illustrated with a single-phase unloaded transformer model which includes a nonlinearity in a magnetic circuit and by a static synchronous compensator, which is a three-phase power electronic device.

Experimental Characterization and Evaluation of an Scaled-Down TCSC Prototype under Steady State Conditions

Abstract: The focus of this paper is to report key aspects of the laboratory-level performance on a three-phase, scaled-down Thyristor Controlled Series Capacitor, TCSC, prototype All-important issues concerned to the design and construction of the prototype are included in this work The testing of the TCSC prototype is restricted to steady-state conditions Several experimental cases are presented

Modelación matemática del mezclado en hornos-cucharas agitadas con gas

Abstract: In this work injection of air into a water physical model of an industrial steel ladle was mathematically simulated. Calculations were developed based on a multiphase Eulerian fluid flow model involving principles of conservation of mass, momentum and chemical species on both phases in order to predict turbulent flow patterns and mixing times in both centric and eccentric injections. Mixing phenomena was addressed by injecting a tracer and it was analyzed the effect of the gas flow rate, injector position, number of injectors and geometry of the ladle on the mixing time. It was concluded that the optimum injection conditions is using a single injector at 2/3 of the radius with high gas flow rates. It is shown that incrementing the number of injectors is detrimental on mixing. Finally, quantitative correlations of mixing time as a function of gas flow rate, position of the injector, number of injectors, geometry of the ladle and mass of liquid were obtained.

Laser shock processing on (AISI 1040) steel surface

Abstract: Laser shock processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results in the LSP concept for metal surfaces treatments in underwater 2laser irradiation at 1064 nm. A convergent lens is used to deliver 2.5 J/cm in a 8 ns laser FWHM pulse produced by a Q-switch Nd:YAG Laser. Experimental results using a pulse density of 5 000 pulses/cm 2 and spots of 0.8 mm in diameter in 1040 steel sample s are presented. Compressive residual stress distribution as a function of depth is assessed by the hole drilling method. High level compressive residual stresses are produced using 1064 nm wavelength. This method can be app lied for surface treatment of final metal products. Keywords : Laser Shock Processing, Residual Stress. 1. INTRODUCTION The Laser Shock Processing (LSP) has been developed as a surface treatment to metals 1-9 . Similar to conventional Shot peening (LP), the Laser Shock Processing (LSP) has been proposed as an effective alternative to traditional methods for metallic materials properties improvement, as fatigue, corrosion and wear resistance (compressive residual stresses are induced). The LSP is a technique for strengthening metals that induces a compressive residual stress field which increases fatigue crack initiation life and reduces fatigue crack growth rate

Viscosity of the Workover Fluid FAPX

Abstract: The physical properties of workover fluids are important in the success of workover operations, in particular, emulsion stability and viscosity. In this work these properties have been investigated using a direct emulsion of oil in water. Three emulsifiers were analyzed and their effects on emulsion stability have been measured both in terms of surface tension decrease and their hydrophilic-lypophilic behavior. An extensive investigation on viscosity was carried out under laboratory conditions and the results reported as isokoms in ternary diagrams. The experimental results were analyzed in terms of an Arrhenius-type equation. It is concluded that small changes in composition lead to large changes in the viscous properties of the workover fluid.