Contribuição ao estudo da medida de desigualdades - análise conjunta dos índices de Gini e Theil

Paulo R Nunes

DOI: 10.14209/sbrt.2019.1570553038

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Abstract

In this paper, the Gini, , and the Theil, , indices, which are used to measure inequality in a population, are jointly analyzed. The Theil index is a measure based on Information Theory, and can vary from 0 to ∞ if there is no limit on the size of the population. The Gini index is limited to the interval [0,1]. In a simple way, it is shown that the Theil index is the negative of a differential entropy, and, in the light of Information Theory, it is defined a new index, here called the equivalent slave population index, , that is a function of the Theil index and varies in the interval . Ideal wealth distribution functions and the well-known Pareto distribution are analyzed in the S-G plane. Results suggest superiority of the S index.

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Modelo estocástico para roteamento de fluxos em redes sem fio restrito ao comprimento dos caminhos

Kátia Cilene Costa Fernandes, Phelipe A de Souza, Leizer Pinto, Kleber V Cardoso

DOI: 10.14209/sbrt.2019.1570553050

Keywords: Modelo estocástico de dois estágios Roteamento de fluxos em redes sem fio Gargalo Comprimento dos caminhos

Abstract

In wireless networks, channel quality tends to fluctuate regularly and this uncertainty is not captured in deterministic optimization. Recomputing routes whenever the channel condition changes it is computationally expensive and generates route instability that is unsuitable for many applications. This paper presents a new two-stage stochastic optimization model, minimizing the network bottleneck and having a "soft" constraint the total path length of all streams. We illustrate how fluctuations in few links degrade the solution from a deterministic approach, while stochastic is prepared to deal with this uncertainty.

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Quantificação de Microesferas de Vidro para Sinalização Horizontal pela Granulometria por Correlação com Pré-Processamento por Rede Convolucional

Joel Silva, Laura Mazzoni, Liedi Bernucci, Hae Yong Kim

DOI: 10.14209/sbrt.2019.1570553285

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Abstract

A sinalização horizontal em pavimentos rodoviários é um importante elemento de segurança que deve apresentar visibilidade tanto diurna como noturna. A visibilidade noturna é avaliada por meio da retrorrefletividade da sinalização e é dependente da quantidade de microesferas de vidro presente na pintura. Desta forma, a quantidade e a distribuição de microesferas na sinalização horizontal são indicativos importantes de sua qualidade. Este artigo propõe-se a utilizar a granulometria por correlação combinado com pré-processamento por rede convolucional U-Net para contabilizar a quantidade de microesferas presentes em imagens digitais.

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Acoplamento de Modos Guiados em Sistemas TDSL Utilizando Antenas com Simetria Radial

Brenda Sousa, Daynara Dias Souza, Gilvan Borges, Roberto Menezes Rodrigues, Andre Mendes Cavalcante, Joao Weyl Costa

DOI: 10.14209/sbrt.2019.1570553917

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Abstract

Recently, the exploitation of twisted pairs used as waveguide, as an alternative to the transmission lines mode, has gained prominence, mainly in order to reach the high demands of data. One of the challenges for this implementation is the coupling of the guided modes in the twisted pair, in this context, this paper aims to investigate the coupling of signals in these structures using antennas with radial propagation. The results were obtained by numerical simulations, in terms of the antenna scattering parameter and the electric field strength in the pair, demonstrating a coupling efficiency of 27.12% in 0,3 THz.

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Avaliação de Modos Guiados em Par Trançado para Transmissão em Terabit/s

Daynara Dias Souza, Brenda Sousa, Gilvan Borges, Roberto Menezes Rodrigues, Andre Mendes Cavalcante, Joao Weyl Costa

DOI: 10.14209/sbrt.2019.1570553918

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Abstract

The exploration of higher order or guided modes in twisted pair cables, as an alternative to the currently used transmission line mode, was recently proposed with the objective of reaching rates at Tbit/s levels. In this context, this paper evaluates from numerical simulations the use of twisted pair's guided modes. The results are evaluated in terms of attenuation and transmission rate of the system, considering a twisted pair per user transmitting four guided modes. It is shown that for some situations it is possible to reach rates above 1 Tbit/s in just over 10 meters.

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Performance of Simple and Fast Sliding Window Detectors for Spectrum Sensing in Radar Bands

Dayan A. Guimarães, Chang Heon Lim

DOI: 10.14209/sbrt.2019.1570554107

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Abstract

The recently-proposed sliding Gershgorin radii and centers ratio (SGRCR) detector makes use of multiple sensing rounds using a short window that slides over the full sensing interval, being adequate for detecting short duration signals, like those emitted by pulse radar systems. This articles proposes the sliding Gini index detector (SGID) as a variation of the SGRCR and compares the performances of both in the context of cooperative spectrum sensing for cognitive radio applications in radar bands. These detectors have approximately the same computational complexity, but the SGID can outperform the SGRCR in most of the system parameterizations and scenarios.

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Impacto do Efeito Brillouin em Sistemas Óptico-wireless com Amplificação de RF no Domínio Fotônico

Eduardo Saia, Luiz Augusto Melo Pereira, Ramon Maia Borges, Arismar Cerqueira S. Jr.

DOI: 10.14209/sbrt.2019.1570554145

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Abstract

Este trabalho reporta o impacto do efeito Brillouin (SBS - stimulated Brillouin scattering), bem como a redução do mesmo, em um sistema óptico-wireless amplificado. Tal sistema utiliza 470 m de fibra altamente não-linear (HNLF - highly nonlinear fiber) para estimular o efeito mistura de quatro ondas (FWM - four-wave mixing) e prover ganho de radiofrequência no domínio elétrico. Resultados numéricos e experimentais comprovam que o SBS limita a eficiência de potência do referido sistema. Identificou-se o comprimento ótimo de 35 m para a HNLF, que garante FWM e proporciona um aumento de 14 dB no limiar de SBS.

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Desempenho de Redes Cooperativas Full Duplex Baseadas em NOMA e Seleção Parcial de Relays

Anderson Tregancini, Edgar Eduardo Benitez Olivo, Diana Pamela Moya Osorio

DOI: 10.14209/sbrt.2019.1570554356

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Abstract

This work analyzes the performance in terms of the outage probability for a NOMA-based cooperative scheme, which employs partial relay selection. The considered system model consists of one source, two users accessing the channel using NOMA, and a cluster of full-duplex amplify-and-forward relays. As contributions of this work, exact single-fold integral expressions and asymptotic closed-form expressions at the high signal-to-noise ratio regime are obtained. From these analytical expressions the performance of the proposed communication scheme is assessed. Monte Carlo simulations validate the obtained results.

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On the Use of Vertex-Frequency Analysis for Anomaly Detection in Graph Signals

Gabriela Lewenfus, Wallace A. Martins, Symeon Chatzinotas, Björn Ottersten

DOI: 10.14209/sbrt.2019.1570554422

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Abstract

Graph signals (GS) are widespread in many areas of data analysis, such as in social, genetics, and biomolecular networks as well as in several engineering applications. Detecting localized properties of GS using spectral tools while taking into account the underlying graph topology is still an active research topic called vertex-frequency analysis (VFA). This paper provides a brief and up-to-date overview on state-of-the-art VFA tools, namely windowed graph Fourier transform and spectral graph wavelet transform. In addition, the paper shows how VFA can be applied to detect and localize anomalies in GS. In the particular example of localizing a malfunctioning weather station,the average area under ROC curve achieved by the local factor outlier technique can be improved from 72% to 87% when fed with VFA-extracted features to detect small drifts in temperature measurements, ranging from 0.5°C to 4°C.

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Laser Sintonizável em Regime Mode-Locking Harmônico (HML) em Cavidade em Figura-de-Oito

Marlon Correia, Flávio André Nogueira Sampaio, Laila Jorge de Sousa Souto, Vinicius Nunes Henrique Silva, Ricardo Marques Ribeiro

DOI: 10.14209/sbrt.2019.1570554542

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Abstract

This paper of Scientific Initiation describes the assembly and testing of a mode-locked laser operating on passive mode in a figure-of-eight cavity. The laser is composed by a single-mode fiber optic ring containing an SOA as medium of gain. Mode-Locking was obtained with MHz repetition rate of the fundamental and harmonic frequencies (Harmonic Mode-Locking).

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