Francisco José Grandinetti

Notes on Steady Natural Convection Heat Transfer by Double Diffusion From a Heated Cylinder Buried in a Saturated Porous Media

This paper aims to present numerical solutions for the problem of steady natural convection heat transfer by double diffusion from a heated cylinder buried in a saturated porous media exposed to constant uniform temperature and concentration in the cylinder and in the media surface. A square finite domain 3 x 3 and acceptance criterion converged solution with an absolute error under 1 x 10(-3) were considered to obtain results presented. The Patankars power law for approaching of variables calculated T, C, and phi also was adopted. In order of method validation, an investigation of mesh points number as function of Ra, Le, and N was done. A finite volume scheme has been used to predict the flow, temperature, and concentration distributions at any space from a heat cylinder buried into a fluid-saturated porous medium for a bipolar coordinates system. Examples presented show that the differences in the flow distribution caused not only when Rayleigh number range is considered but also when Lewis number range is considered. Further, increase in the Rayleigh number has a significant influence in the flow distribution when the concentration distribution is considered. Steady natural convection heat transfer by double diffusion from a heated cylinder buried in a saturated porous medium is studied numerically using the finite volume method. To model fluid flow inside the porous medium, the Darcy equation is used. Numerical results are obtained in the form of streamlines, isotherms, and isoconcentrations. The Rayleigh number values range from 0 to 1000, the Lewis number values range from 0 to 100, and the buoyancy ratio number is equal to zero. Calculated values of average heat transfer rates agree reasonably well with values reported in the literature.

Feasibility study of chromium electroplating process in stamping tooling

Due to the great need for reducing production costs, productivity increasing quality improvement of products, the study had its start drafting surface treatment of dies process development, where the first step was a market study looking for the treatment types and their applications. These treatments are intended to stabilize the production process so that there are no variations on the production and increasing the useful life of dies and their appropriate tools. It was determined through analysis, that the parts had problems in dies drawing which influenced on productivity, quality and cost. It had been realized that those parts had similar problems and the treatments could generally minimize such problems. The following step was to apply the treatment of dies and tools, and then realized that the results achieved certain goals, managing to stabilize the stamping process of those parts.

Trajectories generation for a robotic manipulator

The inverse kinematics determines the joint angles that result in the desired position of the manipulators end-effector with regard to the reference coordinated system. The inverse kinematics solution is difficult a time that the mapping between the Cartesian space and the joint space is nonlinear and involves equations that can have multiple solutions. This work presents the application of a neural network with radial basis function (RBF) for the inverse kinematics solution of a robotic manipulator with three degrees of freedom. For a good learning generalization in the training phase of RBF network, some initial and final points had been initially generated inside of the manipulators work volume. In order to prevent extreme angular oscillations, the angles for each one of the n generated points, they had been optimized by genetic algorithms. In accordance with the cartesian coordinate (x, y) supplied, the RBF neural network implemented in this work supplied angles that it had presented very next to the desired values.

Notes on vibration control of a micro/macromanipulator mounted on a flexible structure

The objective of this study is to describe the design and the implementation of an experimental set-up used to study the dynamics, the experimental identification, and the active vibration control of a flexible structure mounted manipulator system. The system consists of a three-degree-of-freedom cylindrical manipulator system with a flexible link on its tip. A two-degree-of-freedom polar rigid manipulator is mounted on the flexible macromanipulator. The dynamic modelling and experimental modal analysis identification in the frequency domain are being applied to design active digital control strategies for the micro-manipulator system to damp the mechanical vibrations of the flexible structure on the tip of the macro-manipulator system.

Modeling the Mechanical Behaviour of a Subsea Guide Base Subject to Installation and Operations Loads

Historically, the guide cable system for installation of subsea oil production equipment has proven its efficiency. These cables extend from the rig to the wellhead, which are fixed to the guide base posts and will be subject to loads during the installation and operation of the production equipment. The majority of guide base designs have been calculated by analytical methods, although they allow obtaining exact answers in all infinite points of a structure, they are not applicable to all cases. This motivated the application of finite element analysis method (FEA) in this work, which from the development of approximate procedures can be applied regardless of the structure shape and loading conditions. This paper consists of a structural analysis of the guide base frame model, generated in Autodesk Inventor® software and analyzed in ANSYS® Workbench. The study brings a diagnostic research using a quantitative and exploratory approach. Different mathematical models were generated to obtain the results at the most critical points of the structure in order to determine its resistance to the loads applied during installation and operation, taking into account the criteria laid down in DNV 2.7-3, API 17D 1st Ed and von-Mises equivalent stress.

Optimal trajectory and solution of the inverse kinematics of a robotic manipulator by genetic algorithms

This paper presents the generation of optimal trajectories by genetic algorithms (GA) for a planar robotic manipulator. The implemented GA considers a multi-objective function that minimizes the end-effector positioning error together with the joints angular displacement and it solves the inverse kinematics problem for the trajectory. Computer simulations results are presented to illustrate this implementation and show the efficiency of the used methodology producing soft trajectories with low computing cost.

Modeling of a MIT for the Application of a Frequency Inverter of the Electric Vehicle

Nowadays, drives that use a combination of induction motors and frequency inverters are very common, a fact due to the financial practicality and viability in purchasing and operating that system. This system modeling and simulation becomes important when it wants to evaluate the performance, to calculate and correct parameters, and it has a fundamental role in functionality and viability analysis for application of new configurations and technologies. This work is about to elaborate a simple induction motor model based in the torque versus speed characteristic, using the linearization method for application in a specific operation range to be controlled by a frequency inverter.

Aplicação do GRAFCET na redução do retrabalho de uma linha de pintura automotiva

Na area de pintura, em geral, o maior problema encontrado no processo de aplicacao e a quantidade de impurezas sobre a superficie de trabalho. As empresas fazem muitos investimentos para eliminar este problema que, em muitas vezes, e invisivel ao olho humano. Inicialmente, procurou-se mapear e identificar as areas com maior sujidade na planta estudada. Encontraram-se cabines com boas condicoes para aplicacao, porem, a parte exterior da cabine possuia outras fontes contaminaveis, como o proprio ar (devido ao sistema de filtragem) e as poeiras, ambas geradas pelo processo. Este trabalho apresenta um sistema de filtragem de ar na area de pintura, o sistema de limpeza das carrocerias e a proposta de implementacao de uma cortina de ar automatizada para limpeza das carrocerias na area de pintura. Nesta cortina, desenvolveu-se um sistema de automacao em que e possivel gerar a trajetoria para cada tipo de veiculo, levando em consideracao a sua silhueta. O programa para o funcionamento da cortina foi implementado em linguagem “Ladder”; o programa para o calculo da trajetoria foi implementado em linguagem “C” e a descricao do funcionamento foi realizado utilizando o diagrama de blocos GRAFCET, o que permitiu a verificacao de cada etapa do funcionamento da cortina. Sensores opticos sao utilizados para garantir a seguranca do sistema quando este estiver em funcionamento. Ensaios, realizados com simulacao de limpeza em placas, comprovaram a eficiencia do sistema.