Wesley P. Calixto

Parameters Estimation of a Horizontal Multilayer Soil Using Genetic Algorithm

This paper presents an optimization methodology by using a genetic algorithm (GA) to obtain the parameters of a soil that can be represented in a multilayer structure. The method uses a curve of experimental apparent resistivity obtained from measurements made in the soil. This experimental curve is compared with another curve of apparent resistivity of the soil, theoretical, produced by the GA. The theoretical curve is based on Sundes Algorithm and is exactly the inverse process used for the horizontal stratification of the soil in multilayers. With both curves in hand, the error produced in the process of soil stratification can be estimated. From the estimated errors, the parameters are optimized. The main difference of this method, comparing the already developed methods is just that, besides optimizing the resistivities ρi and the thicknesses hi of each soil layer, the proposed method also optimizes the layers quantity, seeking the best soil stratification. The obtained results of this paper are compared with other soil stratification methods.

Electromagnetic Problems Solving by Conformal Mapping: A Mathematical Operator for Optimization

Having the property to modify only the geometry of a polygonal structure, preserving its physical magnitudes, the Conformal Mapping is an exceptional tool to solve electromagnetism problems with known boundary conditions. This work aims to introduce a new developed mathematical operator, based on polynomial extrapolation. This operator has the capacity to accelerate an optimization method applied in conformal mappings, to determinate the equipotential lines, the field lines, the capacitance, and the permeance of some polygonal geometry electrical devices with an inner dielectric of permittivity . The results obtained in this work are compared with other simulations performed by the software of finite elements method, Flux .

3-D Soil Stratification Methodology for Geoelectrical Prospection

The purpose of this paper is to present an innovative methodology for 3-D soil stratification based on geoelectrical prospection. This methodology is useful in optimal substation grounding system designs by providing an accurate 3-D soil resistivity model. In the present methodology, the area being studied is subdivided into squared subareas and a recently developed geoelectrical prospection method based on the Wenners method and on a genetic algorithm is applied to each subareas edge. For each subarea, the soil stratification result consists of the number of layers and of its electrical resistivities and thicknesses. A global 3-D soil stratification solution is then obtained from these data. Results obtained with this new method are presented and discussed.

Firing angles optimization for Switched Reluctance Generator using Genetic Algorithms

This paper reports on a Switched Reluctance Machine (SRM) operating as generator excited through external power source. This device provides DC voltage output through its power converter. Parameters such as rotor speed, excitation voltage and firing angles interferes directly on the output voltage. Thus, many strategies have been studied and developed by scientific community in order to control the output voltage or achieve its maximization. This work proposes a driving strategy applied to the SRM that consists in obtaining the optimal firing angles in order to maximize the output voltage for given rotor speed and excitation. Simulations are presented for results analysis.

Eletricity generation using thermoelectric generator - TEG

Generating machines of electricity, using combustion engines and generate a great amount of residual thermal energy from the exhaust gases. This residual thermal energy can be converted into usable electricity using thermoelectric generator (TEG), which are manufactured cells with semiconductor materials employing the Seebeck effect. When recovering the waste heat in the exhaust ducts using TEG, increases the efficiency of electrical machines, because the same amount of fuel input generates more power or less intake of fuel, has the same amount the generated electric energy and thus less air pollution (as there will be less burning of fossil fuels) makes the system more sustainable. The purpose of this paper is present an electric generation plant using thermoelectric generator (TEG), which recover the thermal energy dissipated by combustion gases of an electric generator. The temperatures values are obtained through thermal imager and laser thermocouples type K. To improve the efficiency of generation is carried out the control and supervision of the temperature on the cold side of the TEG. The Supervisory System is responsible for data acquisition and generation of graphs and reports.

Heuristic and deterministic strategies applied on a PID controller tuning for speed control of a DC motor

This paper reports on a PID controller for speed control of a DC motor. The controller parameters were obtained through optimization methods employing heuristic and deterministic strategies. This methods were applied on a simulation model in order to verify which one provides better control results.

Calculation of sensitivity index using one-at-a-time measures based on graphical analysis

This work proposes different methods to calculate the sensitivity of system parameters based on graphic analysis. From percentages variations in base values of the parameters, one-at-a-time measures are taken to the construction of a graph that expresses the impact on the output caused by variations in the inputs. Two case studies are proposed, with simulated and experimental data, in which the proposed methods are applied and compared based on the values of the sensitivity indices for ranges of interest. All methods confirm quantitatively the most sensitive variables and the choice of one of the methods depends on the characteristics considered relevant for analysis, i.e., degree of sensitivity of a parameter in relation to another, the behavior of the curve and presence of peaks.

Electrical performance evaluation of PV panel through water cooling technique

This paper presents the development of a cooling apparatus using water in a commercial photovoltaic panel in order to analyze the increased efficiency through decreased operating temperature. The system enables the application of reuse water flow, at ambient temperature, over the front surface of PV panel and is composed of an inclined plane support, a perforated aluminum profile and a water gutter. A luminaire was specially developed to simulate the solar radiation over the module under test in a closed room, free from the influence of external climatic conditions, to carry out the repetition of the experiment in controlled situations. In the test conditions without cooling apparatus, the panel reached about 70°C and produced approximately 62Wh. With the cooling apparatus, the module reached about 50°C and produced approximately 77Wh. Through use of this cooling system the photovoltaic module showed a net enhancement in the power conversion efficiency of 16.66%.

High power LED luminaire design optimization

A methodology for optimizing the geometry of a high power (HP) light emitting diode (LED) luminaire is presented in this paper. The arrangement of a HP-LED luminaire is evaluated, technically and economically, for outdoor lighting. Parameters that affect both heat dissipation and lighting efficiency are considered. A finite element method (FEM) simulator is used to determine the thermal analysis and a stochastic ray tracing simulator is used to perform the lighting distribution. The thermal analysis of a HP-LED luminaire model is simulated and validated with 7.5% average error in LED temperature. An evaluation function is developed that considers the illuminance distribution on the target plane and the maximum temperature that reaches the LED chip. Optimized thermal and luminous results are presented and discussed.

Thermal simulation and validation of 5W high power LED luminaire

This paper presents initial studies on thermal heat dissipation in a high-power 5W LED (Light Emitting Diode) luminaire. Two types of heat sinks are proposed, and three thermal simulations are presented through an analysis by finite element methods (FEM). The first simulation considers a luminaire consisting of a confinement, a LED, and a star shaped heat sink base attached. The second simulation proposes an external heat sink. The third simulation proposes a new heat sink model. From the results, it was possible to design and build a prototype and test different cooling structures and heat dissipation issued by the LED. The results of experimental tests that were held with and without external heat sink are matched with simulation results. The major goal of this study is to know the thermal management of LED luminaires by simulation, in order to optimize geometry, material, and LED layout in a luminaire.