Brazilian Center for Research and Development in Telecommunications

Campinas, Brazil

Brazilian Center for Research and Development in Telecommunications

Campinas, Brazil

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Carrillo D.,Brazilian Center for Research and Development in Telecommunications
Conference of Open Innovation Association, FRUCT | Year: 2015

The CPqD Cognitive Mesh Network (CCMN) has been developed with traditional cognition elements, such as energy detection based sensing and with the ability to switch the data channel to take advantage of any available channels on a given radio-electric spectrum band. Many of the solutions that utilize cognitive mesh networks are based on the fact that it uses a common control channel (CCC) to manage the system. Therefore the Multi-Channel - One Interface Manager (MC-OIM) alg orithm was developed to maximize channel usage with a system that does not depend of any CCC. The MC-OIM algorithm was evaluated using network simulator ns-3 and simulation results were validated with testes that were done in a real scenario. © 2015 FRUCT Oy.


Mincov N.,Brazilian Center for Research and Development in Telecommunications
2013 IEEE PES Conference on Innovative Smart Grid Technologies, ISGT LA 2013 | Year: 2013

This paper presents a methodology which includes some technical guidelines, plan of development, and migration of communication technologies that may be used in the design of a communication network in the electric utility companies. Some patterns are analyzed containing conceptual visions used as references for elaboration of any technical action in the development of interoperable communication networks. Some technical criteria and best market practices are used to support this methodology in order to meet sponsors expectations in the process of business transformation in the technological point of view in power companies. © 2013 IEEE.


Barbosa C.F.,Brazilian Center for Research and Development in Telecommunications | Paulino J.O.S.,Federal University of Minas Gerais | Boaventura W.D.C.,Federal University of Minas Gerais
IEEE Transactions on Electromagnetic Compatibility | Year: 2013

This paper presents a time-domain method for the calculation of the horizontal electric field at the earth surface due to lightning, when the earth structure is made up of two parallel horizontal layers of finitely conducting earth. The method is based on the assessment of the electric field at the surface considering the earth as homogeneous and with the electrical parameters of the first layer. The contribution of the second layer is considered by computing the waves reflected from the boundary between the layers, after they have propagated through the first layer. The paper also shows that the displacement currents could be neglected during the wave reflection, which leads to a simple expression for the reflection coefficient. The results from the method presented in this paper agree with results calculated using a known frequency-domain expression. © 1964-2012 IEEE.


Barbosa C.F.,Brazilian Center for Research and Development in Telecommunications
Proceedings of the 3rd International Conference on Applied Robotics for the Power Industry, CARPI 2014 | Year: 2015

This paper describes an eddy current sensor carried by a corrosion detection robot that operates on energized power lines. The robot is installed on a live overhead conductor and it is controlled by the ground-based operator using a portable computer and a radio link. The sensor carried by the robot is capable of detecting the remaining thickness of the zinc layer over the steel wires that make the core of the aluminum conductor steel reinforced (ACSR) commonly used in power lines. The sensor is made of a contactless coil that encircles the conductor and applies an alternating longitudinal magnetic field along the conductor. This field induces eddy currents in the zinc layer that changes the coil impedance, which is used to obtain the zinc layer thickness. The main sensor characteristics are described in this paper, such as its immunity to the load current, its enhanced sensibility due to a hybrid circuit, and its contactless coils that facilitates the sensor installation on the power line conductor. © 2014 IEEE.


Paulino J.O.S.,Federal University of Minas Gerais | Barbosa C.F.,Brazilian Center for Research and Development in Telecommunications | Lopes I.J.S.,Federal University of Minas Gerais | Boaventura W.D.C.,Federal University of Minas Gerais
IEEE Transactions on Power Delivery | Year: 2010

An approximate formula is proposed to estimate the peak value of lightning induced voltages in an infinite line, considering the soil resistivity. The formula is derived from results of a computer code for lightning induced voltage calculation. The code is based on Rusck's formulation for the vertical electric field, for a perfect conducting earth, and the formulation for the horizontal electric field for finitely conducting earth proposed by Barbosa and Paulino. The electromagnetic field coupling with the line is carried out using the model proposed by Agrawal. The results are compared with experimental data from Barker for validation purposes. The paper also presents an extension of the methodology proposed in IEEE Std.1410 Guide to include the effect of the soil finite conductivity in the assessment of the lightning performance of distribution lines due to nearby strikes. The annual indirect lightning induced voltage flashover rates obtained with IEEE Std. 1410 method are compared with the approximate formula results. © 2010 IEEE.


Barbosa C.F.,Brazilian Center for Research and Development in Telecommunications
Atmosphere | Year: 2016

The horizontal electric field at the ground surface in the vicinity of structures hit by lightningflashes is relevant to the safety of human beings and livestock; it determines the touch and stepvoltages around the structure. This paper uses an approximate analytical formula for calculatingthe horizontal electric field, which was adapted to take into account the effect of the structurefoundation. The input for the calculation is the current waveform at the base of the structure, andthe results agree well with those obtained by other authors using the finite-difference time-domain(FDTD) method. The approximate formula is applied to calculate touch and step voltages in thevicinity of a structure and the results show that the use of the direct current (DC) approximation tocalculate touch and step voltages may lead to significant errors; especially for fast-rising currentsand relatively good-conducting soils. This means that DC approximation could be used for positivefirst stroke and poor-conducting ground (ρ ≥ 1000 WΩ·m)., but cannot be used for subsequent strokesand good-conducting ground (ρ ≥ 100 WΩ·m). Moreover, step voltages differ more from the DCapproximation than the touch voltages. © 2016 by the author.


Paulino J.O.S.,Federal University of Minas Gerais | Barbosa C.F.,Brazilian Center for Research and Development in Telecommunications | Do Couto Boaventura W.,Federal University of Minas Gerais
IEEE Transactions on Electromagnetic Compatibility | Year: 2014

This paper analyzes the effect of a two-layer ground on the current induced in the shield of a buried cable due to lightning flashes. Each layer is assumed to be horizontal, homogeneous, isotropic, and having its own electrical parameters: conductivity, permittivity, and permeability. The inducing horizontal electric field is calculated for the incident azimuthal magnetic field and it is used for the calculation of the induced current. The calculation method is validated by comparing its results with results published in the literature. The currents induced in the shield of a buried cable by typical return-stroke current waveforms are calculated. The results show that the induced current waveform is initially determined by the first layer but, for later times, it follows the current that would be induced if the ground was homogeneous and had the characteristics of the second layer. © 2013 IEEE.


Carrillo D.,Brazilian Center for Research and Development in Telecommunications
2015 IEEE Colombian Conference on Communications and Computing, COLCOM 2015 - Conference Proceedings | Year: 2015

The demand of radio-electric spectrum in cities with high density of users is growing every day. There are many initiatives that aim to meet this demand, one of these initiatives is to insert into wireless communication devices algorithms that alternate their band operation through technology called cognitive radios to allow users to maintain connectivity and transfer data securely in unlicensed bands. Often the study and evaluation of research trying to explore the capabilities of cognitive radios require much financial investment in cases in which the intention is to implement a real experimental network or to perform simulations using proprietary software. Thus, this article presents a case of using modules that are implemented within the framework of network simulator textit 3 (ns-3). The results of this simulation were validated with experimental results of a real cognitive network, which was implemented on CPqD campus in Campinas, Brazil. This simulator creates a variety of opportunities to assess cognition algorithms using an open source tool. The validation of simulations with ns-3 show consistency of results with those which were obtained in cognitive experimental network, thus cognitive radio simulator implemented in ns-3 can be used to evaluate algorithms considering a variety of scenarios without increasing costs. © 2015 IEEE.


Barbosa C.F.,Brazilian Center for Research and Development in Telecommunications
IEEE Transactions on Magnetics | Year: 2014

This paper presents the development of a simple but accurate formula to obtain the coating thickness of galvanized steel wires from the impedance of a solenoid containing a sample of the wire. The basic assumption behind the formula is that the skin depth of eddy currents in the coating is much larger than the coating thickness, which can be obtained by a proper frequency selection. The results of the formula compare very well with results of the exact solution, leading to errors <0.08% in the normalized solenoid impedance, for coating thicknesses up to 80 μ m. A simplified version of this formula is also presented, which led to errors <1.3% in the normalized impedance, for coating thicknesses up to 80 μm. This simplified formula provides the coating thickness directly from the input data by performing some arithmetic operations. The formulas are used in the analysis of experimental data available in this paper, and the results are consistent with the uncertainties of the input data. A better representation of the experimental data was obtained by postulating a thin-intermediate layer between steel and zinc. The developed formulas are useful in the implementation of nondestructive testing methods based on eddy current inspection. © 2014 IEEE.


Rohde H.,Coriant GmbH | Gottwald E.,Coriant GmbH | Teixeira A.,University of Aveiro | Reis J.D.,Brazilian Center for Research and Development in Telecommunications | And 3 more authors.
Journal of Lightwave Technology | Year: 2014

Coherent optical communication has been well established as the technology of choice for long haul and high bit rate communication systems since a decade ago. Recent technology advances and ongoing price erosion further open the window of opportunity for the application of coherent optical transmission technology in other domains. This paper describes in detail the capabilities, design and implementation of a coherent ultra dense WDM technology for optical metro and access networks. Its capabilities enable a number of attractive options, such as variable downstream bit rates from 150 Mbit/s up to 10 Gbit/s per user, embedded OTDR and the coexistence with legacy systems such as GPON, EPON, XGPON or RF-Video in optical distribution networks. Due to its flexibility and capacity, it is also suitable for deployments in metropolitan networks, as well as for mobile front-haul and back-haul applications. © 2014 IEEE.

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