Navegando por Assunto "Algoritmos de computador"

Agora exibindo 1 - 3 de 3

Acesso aberto (Open Access)
Desenvolvimento de um algoritmo computacional MoM 3D aplicado em nanoplasmônica
(Universidade Federal do Pará, 2012-12-13) SOUZA, Nadson Welkson Pereira de; COSTA, Karlo Queiroz da; http://lattes.cnpq.br/7932708321834647
This work presents the development of a computational algorithm for electromagnetic scattering analysis of isolated plasmonic nanostructures. The tridimensional Method of Moments (MoM-3D) was used to solve the electric field integral equation, and the Lorentz-Drude model was used to represent the complex permittivity of the metallic nanostructures. Based in this model, a computational algorithm written in C language was developed. As example of application and validation of the code, two classical electromagnetic scattering problems of metallic nanoparticles are analyzed: nanosphere and rectangular nanorod, where the spectral response and near-field distributions were calculated. The obtained results were compared with other models and a good agreement and convergence was observed.
Acesso aberto (Open Access)
Development of computational 3D MoM algorithm for nanoplasmonics
(2013-12) SOUZA, Nadson Welkson Pereira de; COSTA, Karlo Queiroz da; DMITRIEV, Victor Alexandrovich
In this paper, we present an algorithm for full-wave electromagnetic analysis of nanoplasmonic structures. We use the three-dimensional Method of Moments to solve the electric field integral equation. The computational algorithm is developed in the language C. As examples of application of the code, the problems of scattering from a nanosphere and a rectangular nanorod are analyzed. The calculated characteristics are the near field distribution and the spectral response of these nanoparticles. The convergence of the method for different discretization sizes is also discussed.
Acesso aberto (Open Access)
Estudo de algoritmos para classificação de séries temporais: uma aplicação em qualidade de energia elétrica
(Universidade Federal do Pará, 2007-08-24) MORAIS, Jefferson Magalhães de; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
It concerns automatic classification of short circuits in transmission lines. Most trans-mission systems use three phases: A, B and C. Hence, a short-circuit between phases A and B will be identified as AB". Considering the possibility of a short-circuit to ground" (T), the task is to classify a time series into one among eleven possibilities: AT, BT, CT, AB, AC, BC, ABC, ABT, ACT, BCT, ABCT. These faults are responsible for the majority of the distur-bances in electric power systems. Each short circuit is represented by a sequence (time-series) and both online (for each short segment) and offline (taking in account the whole sequence) classification are investigated. To circumvent the current lack of labeled data, the Alternative Transient Program (ATP) simulator is used to create a public comprehensive labeled dataset. Some works in the literature fail to distinguish between ABC and ABCT faults. Then, results differentiated these two faults types adopting preprocessing techniques, different front ends (e.g., wavelets) and learning algorithms (e.g., decision trees and neural networks) are apresented. The computational cost of the some classifiers during the test stage is investigated and the choosing parameters of classiffers is done by automatic model selection. The results indicate that decision trees and neural networks outperform the other methods.