Viviane M. Gomes

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.

Calculation and analysis of voltage violation problem on electricity distribution networks

The approach of this paper it is about voltage conformity delivered to the final customer, on electricity distribution networks. Have obtained physical and electrical characteristics information from the network coming from the database of the electricity company. The study presents the process of voltages estimation in primary and secondary circuits wich estimation of indicators of voltage violation. The presented cases studies approach a statistical analysis of sampling campaigns of distributor, voltage level analysis of one feeder circuit, the estimative of indicators of voltage violation and simulation validation with field measurements on the circuit. Through the found results it is possible to make better decisions of action to be taken and point out the circuit who needs maintenance.

Heuristic regression method for descriptive data analysis

The purpose of this paper is to use the hybridized optimization method in order to find mathematical structures for analysis of experimental data. The heuristic optimization method will be hybridized with deterministic optimization method in order to that structures found require not knowledge about data generated experimentally. Three case studies are proposed and discussed to validate the results. The proposed method has viable solution for the analysis of experimental data and extrapolation, with mathematical expression reduced.

Soil resistivity study and simulation with finite elements method

This work purpose is to study the influence of concrete buried structures in grounding systems. Comparison of soil characteristics between dry and rainy seasons and soil electrical behavior was carried out. Simulations in finite element method was performed for tree layer stratified soil and the electrostatic equipotential surfaces were mapped into the region of interest.

Calculation of system complexity based on the connections: Methodology and applications

This paper proposes a methodology based on system connections to calculate its complexity. There are proposed two study cases: the dining Chinese philosophers problem and the distribution center. Both studies are modeled using the theory of discrete event systems and simulated in different contexts in order to measure their complexities. The obtained results present i) the static complexity as a limiting factor for the dynamic complexity and ii) the lowest cost in terms of complexity for each unit of measure of the system performance. The associated complexity and performance measures aggregate knowledge about the system.

Influence of slot geometry on air gap magnetic flux density of rotating machines

The objective of this work is to investigate the influence of slotted air gap constructive parameters on magnetic flux density of rotating machines. For this purpose, different approaches were used to solve the air gap field diagram using finite element method and the magnetic field distribution uniformity was evaluated by Carters factor calculation. Sensitivity analysis of slot constructive parameters was performed and results show that slot geometry modifies the magnetic flux on air gap and shifts the air gap magnetic equipotential midline of double slotted machines.

Heuristic methodology for horizontal multilayer soil stratification

Soil Stratification methods are used to estimate soil geoelectrical parameters. Several stratification methods are available, but reducing the error estimation introduced by such methods still poses as a challenge. The purpose of this work is to present a heuristic algorithm applied to the optimization of geoelectrical prospection process. The goal is to estimate soil parameters, such as the amount of layers, thickness and resistivity of each layer in an optimal and automated manner. The algorithm consists of analyzing the sensitivity of sampling space parameters. The propose methodology shows error reduction above 75% between the experimental and theoretical curves of the analyzed soils. The results are presented and discussed.