Showing papers by "Instituto Tecnológico de Morelia published in 2007"

Comparative analysis of micromorphological characters in two distantly related Mexican oaks, Quercus conzattii and Q. eduardii (Fagaceae), and their hybrids

Abstract: Interspecific hybridization occurs with high frequency in the genus Quercus, but few studies have analyzed and compared micromorphological characters in putative parental species and their hybrids. Quercus eduardii and Q. conzattii are two Mexican black oak species that, although distantly related, have formed at least one population of hybrid origin, where individuals with intermediate macromorphology are present. The purpose of this investigation was to analyze the degree of differentiation in micromorphological characters between the two species and to assess the expression of these characters in individuals with intermediate macromorphology. Foliar trichomes, epicuticular waxes, stomata, and pollen grains, were examined using scanning electron microscopy (SEM) in the three types of individuals (Q. conzattii, Q. eduardii, and intermediates). Trichome density was quantified with light microscopy. Types of trichomes present, length of trichome arms, types of epicuticular wax on the leaf surfaces...

WC / Stainless Steel Joints Produced by Direct Diffusion Bonding Using a Ni-Foil Interlayer

Abstract: Cemented tungsten carbides are industrially one of the most used composite materials as cutting tools, wear parts and replacements of standard materials for tools, dies and machine components. This work focuses on various aspects of diffusion bonding of tungsten carbide to AISI 304 stainless steel using a Ni-foil interlayer. WC/Ni/AISI 304 combinations were diffusion bonded at 1000°C using different holding times under argon atmosphere. The microstructure characterization of the resulting interfaces was carried out by SEM and EPMA. The results show that successful joining between WC and AISI 304 steel is achieved by the formation of a diffusion zone at both ends of the Ni foil. All WC/Ni/AISI 304 samples have been joined with no severe interfacial cracking or porosity at the interface. The joint strength is determined by four-point bending testing, a maximum of 210 MPa for samples joined at 1000 °C for 60 minutes has been achieved. These results indicate that there is a strong relationship between the thickness of the diffusion interface and the mechanical strength of the joints.

Optimization of energy consumption in electric arc furnaces operated with 100% dri

Abstract: An optimization mass and energy balance has been developed for Electric Arc Furnaces operated with 100% DRI. The model involves linear programming in order to define a metallurgical practice with the lowest production cost. The most recent thermochemical database was also included in the thermal balance. A higher consumption of electrical energy is expected when direct reduced iron is melted, in comparison with scrap, however, heats with 100% DRI show a large variability in energy consumption due to the large differences in its physical and chemical nature. The results of this work can be used to have a better estimate of the energy consumed for a given metallic charge as well as for the optimization of raw materials and production costs. �

An Alternative Solution Initiative to Problematic of Computer Science Security of Virus and Malware with Experimentation of Firewalls and Antivirus

Abstract: Exist in the computer science market a great amount of antivirus, the election of one of them depends on the company. But truly they are necessary, or with a tool we can be protected of the virus and the accesses no authorized our computer. In this document one sets out to demonstrate that firewall personal formed good will protect to us of the intruders and the virus.

An asymptotic solution to non-linear transmission lines

Abstract: This paper explores an asymptotic approach to the solution of a non-linear transmission line model. The model is based on a set of non-linear partial differential equations without analytical solution. The perturbations method is used to reduce the system of non-linear equations to a single non-linear partial differential equation, the modified Korteweg–de Vries equation (KdV). By using the Laplace transform, the solution is represented in integral form in terms of Green's functions. The solution for the non-linear case is obtained by means of asymptotic methods. Thus, an approximate explicit analytical solution to the problem is obtained where the errors can be controlled. This allows us to analyze the non-linear behavior of the solution. This kind of information is difficult to obtain by means of numerical methods due to the fact that for large periods of time greater computational resources are required and also accumulated errors increase. For this reason, asymptotic methods have a great importance like a natural complement to numerical methods. Computer simulations support the developments presented.

Digitally Addressable Digital Dimming Electronic Ballast Based on CAN Bus

Abstract: A digitally addressable digital dimming electronic ballast based on the CAN Bus protocol has been developed. The ballast is a basic lighting component of a novel lighting system proposed for this work based on this protocol. A digital dimming electronic ballast design, a lighting system structure scheme based on CAN Bus and a software platform to control the ballast by a personal computer are presented.

Digital domestic meter for the measurement and billing of electricity in Mexico

Abstract: This article describes the design, construction and characterization of a digital meter of electric energy based on a microcontroller. The meter carries out the calculation of the demand for the kWh consumption, being based on a staggered rate of domestic type of the Federal Commission of Electricity (C.F.E.) in Mexico. The prototype also presents voltage, current, power and time measurements. The instrument takes voltage and current samples of sinusoidal waves which are converted to digital in real time. The system is based on the microcontroller PIC16F874 of the Microchip technology. All the measured and calculated parameters are visualized in a screen of liquid glass of 2 X 16 characters. There is a menu where the parameters are selected to be shown. As a protection, when the electric power supply fails, the meter stores the energy consumption and the remaining parameters in a EEPROM memory. The prototype was divided in four stages: data acquisition, signal conditioning, signal processing and visualization of results, and together, they are a prototype of a digital meter of electric energy for C.F.E. At the end, a set of tests is presented for its characterization.

Aplicación de los factores de participación y del método de MW-Milla en la asignación de cargos por uso de redes de transmisión en mercados de electricidad

Abstract: Use of net work al lo ca tion costs by shift fac tors and MW-Mile method is re ported in this pa per. Con ven tional shift fac tors are com puted based on DC power flow. DC power flow re quires to se lect ing a slack bus in or der to avoid ma trix sin gu lar ity. There fore, shift fac tors are slack bus de pend ent. In or der to evade slack bus de pend ency, two ap proaches are con sid ered.

Laser shock processing to improve residual stresses with and without paint layer on 6061-T6 aluminum alloy

Abstract: Laser shock processing (LSP) or laser shock peening has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduce fatigue crack growth rate. We present a configuration and results in the LSP concept for metal surface treatments in underwater laser irradiation at 1064 nm with and without a thin surface paint layer. A convergent lens is used to deliver 1, 2 J/cm 2 with a 8 ns laser FWHM pulse produced by a 10 Hz, Q-switched Nd:YAG laser with a spot diameter of a 1,5 mm moving forward along the workpiece. A LSP configuration with experimental results using a pulse density of 5000 pulses/cm 2 in 6061-T6 aluminum samples are presented.

On the Fluid Flow and Mixing Phenomena in Ladles Equipped with Impeller and Gas Purging for Degassing of Al-Based Alloys

Abstract: In this work a fundamental Eulerian mathematical model is developed to simulate fluid flow and mixing phenomena in aluminum ladles equipped with an impeller for dehydrogenization treatment. The effect of rotating speed and type of impeller, depth of immersion, and gas flow rate, on the mixing behavior and vortex formation is analyzed with this model. The model simulates operation with and without gas injection and it is developed in the commercial PHOENICS 3.4 CFD code in order to solve all conservation equations governing the process, i.e., continuity, 3D turbulent Navier-Stokes and k-e turbulence model for a two-phase fluid flow problem using the Inter Phase Slip Algorithm. In order to realistically represent the process, the shape of the furnace and the impellers are modeled by employing Body Fitted Coordinates. It is concluded that the mixing behavior is highly dependent on the rotation speed and impeller type. Mixing time is improved when: the impeller is located at a depth of 0.229 m into the aluminum bath, and by using high rotation speeds, ladles with a high ratio of diameter to height, and impellers with notches.