Classes de Códigos Coloridos em Superfícies com Gênero g ≥ 2

Clarice Dias de Albuquerque, Reginaldo Palazzo Junior

DOI: 10.14209/sbrt.2017.211

Keywords: Códigos Coloridos Códigos de Superfície Tesselações Hiperbólicas Códigos Quânticos

Abstract

Neste artigo apresentamos as construções de três classes de códigos coloridos em superfícies compactas com gênero g ≥ 2. Tais classes derivam das tesselações hiperbólicas, {8, 3}, {10, 3} e {12, 3} e possuem taxas de codificação assintoticamente iguais a 1/4, 2/5 e 1/2, respectivamente. Além disso, a distância mínima dos códigos cresce com o gênero da superfície.

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SÍNTESE E CARACTERIZAÇÃO DA CERÂMICA CaBi4T i4O15 (CBT) APLICADO A UMA ANTENA RESSOADORA DIELÉTRICA

Lucas Freitas Ximenes, Antônio Alan Rodrigues de Araújo, Ismael Araújo Ramos, Edmar Miranda Ávila Júnior, Múcio Costa Campos Filho, Guilherme Francisco de Morais Pires Júnior

DOI: 10.14209/sbrt.2017.212

Keywords: CaBi4T i4O15 X-Ray Diffraction Microwave Radiofrequency Sintering

Abstract

With the recent advances of the telecommunications industry, it is becoming increasingly necessary to develop materials that have high values of dielectric constant, low dielectric loss and good thermal stability. This paper presents the development and characterization of ceramics CaBi4T i4O15 (CBT), material known for its excellent dielectric properties, mainly high dielectric constant values. The ceramic matrix was produced from the conventional ceramic method or solid state method with the use of high energy mechanical milling and thermal treatment. The ceramic matrix was calcined at 800 ◦C for 2 hours and formed into a cylindrical form after grinding for 6 hours. Subsequently the sintering was carried out at 1150 ◦C for 4 hours to promote better densification. X-ray diffraction was used in the characterization and confirmation of the ceramic phase. Antenna analysis was performed using a ground plane monopole and the data were collected on a network analyzer. The results show the resonance frequency at 1.94 GHz and return loss of -40.4 dB. The measurements of dielectric characterization in radiofrequency and microwave, carried out at room temperature, had a high dielectric constant value (r = 154, 6) and a dielectric loss tangent (tan δe) of the order of 10−2 . Therefore, it can be seen that the ceramic matrix presented is potentially applicable in several electronic devices in radiofrequency and as a microwave dielectric resonator antenna.

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A Comparative Analysis of Correlation and Correntropy in Graph-Based Brain Computer Interfaces

Luisa Fernanda Suárez Uribe, Carlos Alberto Stefano Filho, Vanessa Brischi Olivatto, Levy Boccato, Gabriela Castellano, Romis Attux, Vinícius Alves de Oliveira, Diogo Coutinho Soriano

DOI: 10.14209/sbrt.2017.213

Keywords: Brain-computer interfaces information-theoretic learning correntropy graph measures motor imagery

Abstract

This work presents a comparative analysis of correlation and correntropy in the context of graph-based braincomputer interfaces using motor imagery. These two statistical entities are used in the construction of the graphs, from which features are extracted. The results indicate that correntropy has a more consistent performance over the different graph measures, hence deserving to be considered as a relevant option by researchers of the field.

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UTILIZAÇÃO DE EOS NA DETECÇÃO DE FALHAS ESTRUTURAIS EM VIGAS

A. W. M. Pinto, F. E. M. Borges, D. A. Pereira, B. H. G. Barbosa, R. R. Magalhães, D. D. Ferreira, T. S. Barbosa

DOI: 10.14209/sbrt.2017.214

Keywords: Análise de Vibrações Reconhecimento de Padrões Monitoramento da Saúde Estrutural EOS

Abstract

Neste artigo é proposto um método de detecção de falhas ou danos estruturais usando Estatística de Ordem Superior (EOS). A partir de sinais de vibração medidos por um acelerômetro, características são extraídas por cumulantes e selecionadas com o Discriminante de Fischer. Posteriormente é realizada a classificação com o auxílio de Máquinas de Vetores de Suporte, objetivando-se determinar a presença ou não de falhas na estrutura. O método apresenta alta taxa de detecção. Vantagens apresentadas são o baixo custo computacional e a não exigência de informações sobre a estrutura danificada.

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Análise de limitantes de atraso do procedimento de acesso aleatório para NB-IoT

Gustavo Baracat, José Marcos Camara Brito

DOI: 10.14209/sbrt.2017.215

Keywords: NB-IoT Random Access NPRACH parameters delay

Abstract

Narrowband Internet of Things (NB-IoT) is a cellular technology that will provide connection for a massive number of low-cost and low-power devices. This paper describes the analysis of delay bounds for the NB-IoT, calculating minimum delay and maximum delay in the random access procedure, aiming at the best solution in the configuration of the network parameters in order to meet the access capacity and data rate requirements.

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Um scanner 3D de baixo custo

Wagner Wispel, Renato Machado, Andrei P. Legg, Fábio M. Bayer

DOI: 10.14209/sbrt.2017.209

Keywords: Triangulação a laser scanning 3D calibração

Abstract

Sistemas de scanning tridimensional (3D) são utilizados em um grande número de aplicações, tais como na digitalização de quadros, esculturas e patrimônios culturais, engenharia reversa e computação gráfica. A maioria dos scanners 3D disponíveis no mercado são projetados para uma alta resolução e precisão. Isso requer o uso de equipamentos tecnologicamente mais avançados, o que acarreta na elevação do custo do produto final. Este artigo apresenta a implementação de um sistema de scanning 3D de baixo custo baseado no uso da técnica de triangulação a laser utilizando apenas uma câmera e um gerador de laser tipo linha. Dois objetos são escaneados e suas respectivas nuvens de pontos são analisadas. Os resultados demonstram que o sistema de scanning 3D proposto, apesar de sua simplicidade e baixo custo, é capaz de digitalizar superfícies com uma boa precisão.

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Classificação Digital de Cicadidae com Wavelets e Support Vector Machines

Joao Paulo Lemos Escola, Rodrigo Capobianco Guido, Ivan Nunes da Silva, Alexandre Moraes Cardoso, Douglas ˜ Henrique Bottura Maccagnan, Artur Kenzo Dezotti, Igor de Moraes Sampaio, Lucas Exposto Soares

DOI: 10.14209/sbrt.2017.150

Keywords: Cicadidae Wavelets Suport Vector Machine

Abstract

The cicada is one of the key crop pests and the only way to combat application of insecticides. However, the sounds emitted by the male, in order to attract females, are peculiar and can be employed for digital detection and classification of species. This work presents an algorithm of signal processing and recognition of patterns to detect and classify cicadas in order to provide a tool that assists the control and the monitoring of species, contributing to the state of the art and covering a gap in the area. The results obtained shows an accuracy of more than 90% indicates the feasibility of using the present prototype.

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Detecção de Eventos Sonoros para Sistemas de Segurança

Tito Caco Curimbaba Spadini, Ricardo Suyama

DOI: 10.14209/sbrt.2017.193

Keywords: Digital Signal Processing Digital Audio Processing Machine Learning Pattern Recognition Surveillance System

Abstract

This work aims to investigate different techniques for the classification of atypical sound events, considering the accuracy and classification time, in order to find which of these techniques are most advantageous for surveillance scenarios, minimizing the possibility of relevant events to go unnoticed. LDA, QDA, Decision Tree and KNN techniques were compared. The results obtained indicate that the KNN is the most indicated classification method for the purposes described.

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Um estudo sobre separação não supervisionada de misturas convolutivas

Renan D. B. Brotto, Joao M. T. Romano

DOI: 10.14209/sbrt.2017.216

Keywords: Unsupervised signal processing Convolutive mix- tures Deconvolution. I. IN

Abstract

This paper presents the results of a study in sepa- ration of convolutive mixtures by means of linear and nonlinear decorrelation. These techniques have also been applied to the problem of channel deconvolution, exploring the duality between these two fields.

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On the Encoding Capacity of Some Non-Abelian Group Codes

Jorge Pedraza Arpasi

DOI: 10.14209/sbrt.2017.217

Keywords: Symmetric channels non-Abelian group codes En- coding capacity

Abstract

In this work we study group codes over non-Abelian groups which are extensions. Extension of groups is a general- ization of semi-direct product and direct product of groups. For channels having as its input alphabet a signal set, one-to-one matched to a non-Abelian group which is an extension, is given a definition of encoding capacity adapted from an existent one that covers the Abelian group case. By using this adapted definition, formulas to compute the encoding capacity of the channel, are derived. Two important examples of application are given.

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