Dissertações em Engenharia Elétrica (Mestrado) - PPGEE/ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2316

O Mestrado Acadêmico inicou-se em 1986 e pertence ao Programa de Pós-Graduação em Engenharia Elétrica (PPGEE) do Instituto de Tecnologia (ITEC) da Universidade Federal do Pará (UFPA).

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Acesso aberto (Open Access)
A machine learning framework for ECG biometric system
(Universidade Federal do Pará, 2020-02-28) SANTOS, Alex Barros dos; ROSÁRIO, Denis Lima do; http://lattes.cnpq.br/8273198217435163; CERQUEIRA, Eduardo Coelho; http://lattes.cnpq.br/1028151705135221; https://orcid.org/0000-0003-2162-6523
The new environment of IoT and the deployment of 5G networks have been generating a huge amount of data. Developers are creating new applications and redesigning other ones completely. Also, a society greater concern with health increases the demand for health services provided with the usage of wearable devices that are getting cheaper. Moreover, the applications require more data protection and privacy. Thus, biometrics has become one of the primary mechanisms for protecting information used by users in all kind of systems and applications. This work investigates the use of an ECG signal in biometrics systems approaching machine learning techniques. This signal is a new alternative not only to increase current safety standards by providing the individual’s continuous authentication but also to assess health with cardiac monitoring already well established in medicine by evaluations. In this context, this master’s thesis proposes some processing steps to data sets, improving its quality that allows it to be used as a reliable source of biometric data. We define techniques for extracting signal considering mobile application constraints and design a structure that allows the use of ECG as a biometric signal in a scalable and heterogeneous environment considering different machine learning techniques such as Support Vector Machine, Random Forest and Neural Networks. The set of our proposed feature extraction, processing steps of data set and a machine learning model are the main contributions of this work.
Acesso aberto (Open Access)
Impacto dos harmônicos de tensão na temperatura e desempenho de motores elétricos classes IE2, IE3 E IE4.
(Universidade Federal do Pará, 2020-02-19) MUÑOZ TABORA, Jonathan; MATOS, Edson Ortiz de; http://lattes.cnpq.br/0241051151153034; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
The introduction of new technologies as well as the improvement of materials and processes has contributed to accelerate the growth in the efficiency of the electric induction motors (IM). Currently in the market it is possible to observe the operation of IM classes IE3 and IE4, as well as minor efficiencies, in the same way proposals for IM class IE5 are being developed. This work aims to show the impact of 2nd, 3rd, 5th and 7th order voltage harmonics on the temperature and performance of IE2, IE3 and IE4 induction motor classes, the latter being a hybrid motor of permanent magnets and squirrel cage (Line Start Permanent Magnet Motor, LSPMM's). The measurements were divided into two stages, first feeding each of the motors with undistorted voltages and then entering each of the harmonics individually and in combination in percentages of 2% until reaching 25%. Considerable improvements in temperature, noise and consumption are notable in the case of the class IE4 hybrid motor, however, this motor also shows some weaknesses in its response compared to classes IE2 and IE3, mainly in the presence of harmonics. It is also presented as the presence of individual harmonics in electric motors, results in the appearance of other harmonics, according to the percentage of distortion present. Finally, in order to predict the variation of temperature in relation to the percentage of distortion, models representing this behavior were created, which represent good estimates of the temperature variation and the percentage of distortion inserted in the motor.
Acesso aberto (Open Access)
Mobility and cloud management in wireless heterogeneous 5g networks
(Universidade Federal do Pará, 2020-06-30) PACHECO, Lucas de Sousa; ROSÁRIO, Denis Lima do; http://lattes.cnpq.br/8273198217435163; HTTPS://ORCID.ORG/0000-0003-1119-2450; CERQUEIRA, Eduardo Coelho; http://lattes.cnpq.br/1028151705135221; https://orcid.org/0000-0003-2162-6523
The network mobility management branch is responsible for the protocols and actions taken by the network to ensure connectivity and the continuity of services consumed by mobile users. In this dissertation we analyse how next-generation networks pave the way for the distribution of video in vehicular networks (VANETs), composed by an heterogeneous ultra-dense infrastructure, joining existing wireless communication technologies to obtain greater spectral efficiency. A handover algorithm called HoVe is presented. Based on various criteria for video distribution on ultra-dense 5G VANETs. The simulation results show HoVe’s efficiency in providing videos with 19% higher quality than state-of-the-art algorithms, improving the package delivery rate by at least 30%. This work studies a particular case of VANETs that benefits from computing at the edge of the network, the case of Connected Autonomous Vehicles, or CAVs. Edge and mist computing are emerging solutions for remote data processing for autonomous vehicles, offering greater computational power, as well as the low latency required by autonomous driving. This work proposes the MOSAIC algorithm for service migration and resource management for communication between layers and between layers in edge and fog computing. Simulation results show the efficiency of the proposed algorithm with a better performance of up to 50% in terms of latency and five times less migration failures.
Acesso aberto (Open Access)
Fuzzy c-means based gateway placement algorithm for lorawan
(Universidade Federal do Pará, 2020-02-27) MATNI NETO, Nagib Coelho; CERQUEIRA, Eduardo Coelho; http://lattes.cnpq.br/1028151705135221; HTTPS://ORCID.ORG/0000-0003-2162-6523; ROSÁRIO, Denis Lima do; http://lattes.cnpq.br/8273198217435163; https://orcid.org/0000-0003-1119-2450
Low Power Wide Area Network (LPWAN) technologies recently gained interest from the research and industrial community. Internet of Things (IoT) devices communicate directly with gateways, which act as bridges towards a central network server and the Internet. In this context, it is important to study how to place multiple gateways in an area considering Quality of Service, Capital expenditure (CAPEX), and operational expenditure (OPEX) requirements. This is because network planning and optimization are considered to be significant issues that impact on the application performance, CAPEX, and OPEX. In this master thesis, we propose an optimal LoRa gateway placement (PLACE). It considers the Gap statistics method to find the number of LoRa gateway, which is used to compute the gateway placement using the Fuzzy C-Means algorithm. Simulation results show that PLACE reduced in 36% the CAPEX and OPEX compared to the grid and random gateway placement, while keeps a similar Packet Delivery Ratio.
Acesso aberto (Open Access)
Uma Proposta de arquitetura de big data para detecção de fake news.
(Universidade Federal do Pará, 2020-01-24) QUEIROZ, Daniele Moura de; FRANCÊS, Carlos Renato Lisboa; http://lattes.cnpq.br/7458287841862567
In last years, a large amount of information has been transmitted through the Internet, especially in social media, providing greater knowledge on various topics, but making people susceptible to false information that can cause various damage. Although it is not a recent phenomenon, the sharing of false news has been a matter of concern for specialists and the population in general, since it can cause impacts of national and even global proportions. The transmission of fake news can cause various damages, from financial to losses related to defamation, injury, offense, reputation or dignity of people or organizations. The spread of this false information has made it difficult to detect reliable news sources, increasing the need for computational tools that can help identify the reliability of digital content. Moreover, the massive amount of data generated daily at high speed and different types of formats such as text, images, videos and audios, makes analysing this data a big challenge. With the advent of big data technologies, it is possible to use a range of tools and techniques to efficiently store, process and analyse massive data to help investigate the credibility of news disseminated and shared by middle of the internet. This paper discusses the importance of Big Data to combat fake news, based on an appropriate conceptual and technological framework, and presents a Big Data architecture proposal for storing, processing and analysing large data sets, aiming to assist in the investigation of truth of news. For this, experiments were performed using a mass of data containing different formats, i.e. structured and unstructured data, extracted from news sources and forming a corpus composed of false and true news. This mass of data was stored in a Hadoop cluster using the Hadoop Distributed File System (HDFS). The corpus was processed using the MapReduce programming model and the news classification was performed using the Naive Bayes algorithm from Mahout library, obtaining an accuracy of 99.74%. The preliminary results produced by the development of this study reveal an architecture capable of storing, processing and analysing Big Data in the context of fighting fake news.
Acesso aberto (Open Access)
Circulador de 4 portas baseado em um ressonador elíptico de grafeno na região terahertz.
(Universidade Federal do Pará, 2020-01-20) OLIVEIRA, Thiago Lima de; DMITRIEV, Victor Alexandrovich; http://lattes.cnpq.br/3139536479960191
A new type of four-port circulator based on graphene for the terahertz frequency range is proposed and analyzed in this work. It consists of two parallel waveguides coupled laterally to a magnetized resonator in the shape of an ellipse. The cross section of the components has a three-layer structure consisting of graphene, silica dioxides and silicon. The graphene resonator is normally magnetized in its plane by an external DC magnetic field. The physical principle of the device is based on the dipolar resonance of the resonant cavity of magnetized graphene. Using the Theory of Magnetic Groups, we were able to analyze the scattering matrices of the symmetry components of the device. In addition, the Temporal Coupled Modes Theory was used in order to analytically analyze the characteristics of the device. The influence of different parameters on the characteristics of the circulator was investigated using the Comsol Multiphysics software. Numerical simulations demonstrate the isolation of ports 3 and 4 around -32.6 dB and -16.2 dB, insertion losses around -2.5 dB, reflection around -20.3 dB and 5.7 % bandwidth with the center frequency of 5.03 THz. The DC magnetic field of applied polarization is 0.8 T. The central frequency of the circulator can be controlled by the change in the Fermi energy of graphene. Finally, a comparison was made between the numerical and analytical model of the device, using the aforementioned tools.
Acesso aberto (Open Access)
. Clusterização, classificação e predição de “pré-efeito anódico” de cuba eletrolítica de alumínio primário
(Universidade Federal do Pará, 2020-08-21) CONTE, Bruno Nicolau Magalhães de Souza; OLIVEIRA, Roberto Célio Limão de; http://lattes.cnpq.br/4497607460894318
The industrial sector is one of the main responsible for the serious environmental situation on the planet and also for increasing legal requirements, in relation to the waste generated. On the other hand, many companies have reacted proactively, based on the implementation of management strategies such as: clean production, environmental certification, reduction of toxic waste, recycling, sustainable consumption and reuse, mainly. It is worth mentioning that the aluminum reduction process is responsible for a large amount of greenhouse gas emissions and, thus, promotes environmental impacts and serious climate changes. During the aluminum reduction process, the occurrence of the anodic effect causes an extreme increase in the tub tension and, consequently, an increase in the bath temperature, with very high temperatures, resulting in a thermal disturbance, with the possibility of melting the insulating layer of the vat and the final consequences are the loss of production in the entire vat line, its shortened service life and the production of PFC gases. Seeking a strategy based on sustainability, I try to take into account the problem of the worsening of the Greenhouse Effect, the extreme increase in kiln tension and, consequently, the loss of production in the entire line of vats, this work proposes the use of an Artificial Neural Network together with Clustering algorithms to automatically create anodic pre-Effect labels, and thus predict the nonlinear dynamic behavior of the primary aluminum reduction industry oven anodic pre-effect, based on actual vat data electrolytic. With the use of these Machine Learning models, it is possible to predict the occurrence of the anodic pre-effect, allowing process operators to take mitigating measures to suppress the anodic effect, avoiding the loss of aluminum production in the vat and decreasing the emission of gases from the greenhouse effect.
Acesso aberto (Open Access)
Mitigação de variações de tensão em uma indústria cervejeira usando banco de capacitores fixos e chaveados
(Universidade Federal do Pará, 2020-06-04) SILVA JÚNIOR, Luiz Cláudio Lobo da; VIEIRA, João Paulo Abreu; : http://lattes.cnpq.br/8188999223769913
Fixed capacitor banks are equipment commonly used in industrial plants to correct power factor and/or mitigate undervoltage in their distribution networks. At heavy load levels, capacitor banks play an important role for reactive power compensation in industrial plants. On the other hand, during light load levels, the reactive power injection from capacitor banks can cause overvoltage in distribution circuits of industrial plants. The voltage variation problem in an industrial plant can adversely affect the useful life of its equipment. The combined use of fixed and switched capacitor banks is an alternative solution for mitigating steady-state voltage variation problems in industrial plants. This master dissertation proposes and investigates a technique to mitigate steady-state voltage variations in low voltage distribution circuits of a beer plant, located in the city of Benevides, PA. The proposed method is based on the reactive power compensation supplied fixed and switched capacitor banks. In recent years, the voltage quality problem has been observed in the above-mentioned beer plant, causing a drastic reduction in the useful life of its equipment. A set of real measurement data from the beer plant site was used in time-series load flow simulations, using OpenDSS software, to evaluate the proposed mitigation technique.
Acesso aberto (Open Access)
Detecção e rastreamento de componentes de vagões ferroviários utilizando redes neurais convolucionais e restricões geométricas
(Universidade Federal do Pará, 2020-04-27) GONÇALVES, Camilo Lélis Assis; BARROS, Fabrício José Brito; http://lattes.cnpq.br/9758585938727609
A inspeção de componentes de trem que podem causar descarrilamento possui um papel importante na manutenção ferroviária. A fim de aumentar a produtividade e a segurança, empresas prestadoras de serviços procuram por soluções de inspeção automáticas e confiáveis. Apesar da inspeção automática baseada em visão computacional ser um conceito consolidado, tais aplicações desafiam a comunidade de desenvolvimento em razão de fatores ambientais e logísticos a serem considerados. Este trabalho propõe uma técnica de detecção e estimativa das posições das regiões de dreno presentes em vagões de trem. Nosso detector/rastreador consiste em uma rede neural convolucional e um conjunto de restrições geométricas, que levam em conta a trajetória ideal dos componentes de interesse dos vagões e as distâncias entre eles. Detalhamos os procedimentos de treinamento e validação, juntamente com as métricas utilizadas para aferir a performance do sistema proposto. Os resultados apresentados são comparados com outras duas técnicas, e exibem um bom custo‑benefício entre confiança e complexidade computacional para a detecção dos componentes de interesse.
Acesso aberto (Open Access)
Ciência de Dados Aplicada em Dados Públicos: Estudos de Caso Acerca da Previdência Social Brasileira.
(Universidade Federal do Pará, 2020-04-17) FELIX JÚNIOR, Francisco Eguinaldo de Albuquerque; SILVA, Marcelino Silva da; http://lattes.cnpq.br/7080513172499497
Data Science is an interdisciplinary area related to data analysis, which aims to extract knowledge and possible decision-making about specific problems. In this context, open government data, which often need pre-treatments and computational methods to process their data sets, present themselves as potential sources of information to be explored taking the Data Science’s perspective, allowing the development of strategies each time more efficient and optimized in public management. Given this, and allied to the recent discussions related to the reform in the Brazilian social security, this dissertation presents two case studies referring to analyzes in the national social security system. The first study used the microdata referring to the demographic censuses of 2000 and 2010, made available by IBGE, proposing to evaluate the participation that retirements and pensions have in the income inequality of the population in the years evaluated about Brazilian states and municipalities. The results show that, although the analyzed benefits contribute to the Brazil income concentration, the portion corres=ponding to a minimum wage contributes to the deconcentration of income, and the portion above one salary contributes to the concentration, being a repetitive pattern throughout the country. On the other hand, the second study proposed an evaluation of the impacts caused by the pension reform, which is proposed in PEC 06/2019. It was observed that PEC 06/2019 would hinder access to benefits, in which approximately 83,28% of the pensions would not have been granted had it been in effect since 1995.
Acesso aberto (Open Access)
Data science aplicado a dados abertos do Governo Federal: estudos de caso sobre a economia dos municípios brasileiros.
(Universidade Federal do Pará, 2020-03-13) SANTOS, Sandio Maciel dos; SILVA, Marcelino Silva da; http://lattes.cnpq.br/7080513172499497
The process of analyzing open databases in recent years has gained considerable prominence in the Brazilian scenario since the granting of Law 12,527 / 2011, which guarantees access to public information, allowing for better transparency of public spending by society. Allied to this, numerous discussions arose around the use of Brazilian government microdata, among which we highlight the discussions on social security reform and the analysis of fiscal health in Brazilian municipalities through social security approaches. Thus, this work focuses on the use of Data Science, specifically in the KDD process to analyze microdata from Brazilian municipalities. Thus, in this work, two different approaches are made, the first of which performs a descriptive statistical analysis without inferences, to understand the fiscal health of Brazilian municipalities between 2010 and 2017, through transfers from the RGPS. The second approach to fiscal analysis using the STVAR model through the following variables: expenditure, revenue, and GDP of the municipality of São Paulo. The results of analysis I show that municipalities with populations greater than 100 inhabitants do not show a deficit due to the difference between municipal collections and transfers from the RGPS. In analysis II, the results found show that the economic cycle analyzed when undergoing exogenous shock (or external impulse) can generate changes in the states of recession and expansion with an average duration of 12 months.
Acesso aberto (Open Access)
Sistema de identificação duplo (SID) de usuários através dos biosinais fotopletismograma e eletrocardiograma
(Universidade Federal do Pará, 2020-05-28) BASTOS, Lucas de Lima; ROSÁRIO, Denis Lima do; http://lattes.cnpq.br/8273198217435163; CERQUEIRA, Eduardo Coelho; http://lattes.cnpq.br/1028151705135221
With the growth of the area in digital health, wearable devices stood out due to their practicality and comfort in detecting the personal data of their users. In general, these devices have a variety of sensors that capture information about the environment and user, heartbeat, amount of steps, oxygenation in the bloodstream, and photoplethymram, and electrocardiogram. Typically, capturing signals through sensors presents problems that impair signal analysis such as noise, false electromagnetic waves, and unexpected user movements. From this, signal filtering becomes an indispensable step in the process of removing these noises. The sensors can capture these signals, and through later steps, filtering, classification, one can reach in the identification of users. There are traditional methods of recognizing people, such as iris, face, or fingerprints. Today, biosignals are already able to be used for authentication, going through several steps to achieve this goal. Steps such as capture, filtering, extraction of characteristics, classification, and correlation are the main equipment used by these biosignals but still depend on mobile devices. There are many biosignals to be used in the authentication of people. Still, not all are effective; the choice is due to the fact of the shape of the graph of the generated signal, the quality in the capture of signals, and their ability to extract unique characteristics and classification. With these aspects pointed out, this master’s thesis aims to present a Double Identification System of wearable device users through the signs of Photoplethysogram and Electrocardiogram. With this, a method of parameterizing filtering and extracting peaks and the second method of double authentication through the biosignals PPG and ECG. The results indicated a correlation of 80% between the entire raw signal and filtered signal until peak extraction. They obtained an accuracy of 94.1% for the PPG signal without the calculation of errors and 99.98% with the calculation of the error rate, ECG signal reached 88.79% accuracy, for a total of 2809 inferences for each signal for identification of wearable device users.
Acesso aberto (Open Access)
Proposta de um framework para identificação de sistemas dinâmicos multivariáveis não lineares
(Universidade Federal do Pará, 2020-02-27) OLIVEIRA, Ewerton Cristhian Lima de; ARAÚJO, Jasmine Priscyla Leite de; http://lattes.cnpq.br/4001747699670004
The techniques of dynamic systems identification are algorithms of most importance for generating mathematical and computational models capable to represent the dynamic of systems and processes present in many fields of society, such as: industrial processes; automobiles; food production; aerospace vehicles; biological systems and etc. The identification of these systems, which generally have more than one variable of input and output (multivariable systems) and also are nonlinear, it is very important for science and engineering in relation to the development of new control techniques, fault monitoring and prediction of operating state of these mechanisms. Nonetheless, the identification of nonlinear MIMO (Multiple Input Multiple Output) systems is a hard task, as much due the difficulty of implementing the classic algorithms for solve this problem, as the fact that nonlinear systems require complex models for represent their dynamics in satisfactory way. In order to contribute with the solution of this problem, this work proposes a framework capable of performing as much the identification of nonlinear dynamic MIMO systems in multivariable fuzzy TSK model, which can represent in simple way the coupling among the variables involved in identification, as the selection of regressor vector used in model. To perform fuzzy TSK multivariable model parameterization, the proposed framework uses the algorithms Least Square (LS) and Particle Swarm Optimization (PSO), which are responsible to estimate the matrix of parameters and the set of standard deviation of the Gaussians in model inputs, respectively. The proposed methodology is tested and compared with RNA and a Hammerstein-Wiener (WH) model in identification of two nonlinear MIMO industrial plants: Continuous Stirred Tank Reactor (CSTR); Industrial Dryer. The comparison of these three techniques is made with base in indices of Mean Squared Error (𝑀𝑆𝐸) and Variance Accounted For (𝑉𝐴𝐹), further the analysis of residues between the observed and estimated data. The results show that the proposed framework got the best performance, based in the two indices, in 80% of outputs estimation of the two multivariable plants, and also reached the best performance in 60% of residual analysis of plants identification.
Acesso aberto (Open Access)
Análise de Desempenho de Meta-heurísticas Aplicadas ao Problema de Restauração de Redes de Distribuição.
(Universidade Federal do Pará, 2020-02-20) BATISTA, Vítor dos Santos; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
In the last years, several meta-heuristics have been used to solve the problem of restoring distribution systems efficiently. Among them, the Multiobjective Evolutionary Algorithm with Node-depth encoding (MEAN) stands out, which together with Node-Depth Encoding (NDE) makes a great advance in the field. All this because the NDE makes changes on the topology of the distribution system without losing radiality and reestablishing the power supply for all disconnected loads after the fault. Due to the lack of exploration of other meta-heuristics that use NDE as a data structure, this work aims to evaluate a performance analysis comparing MEAN with three other meta-heuristics, Tabu Search, Artificial Bee Colony and Evolutionary Strategies. The analysis was performed in three distribution systems the84-bus, 119-bus and 135-bus.s
Acesso aberto (Open Access)
Utilização de métodos ativos na transformação de um prédio em um edifício de energia zero: estudo de caso da biblioteca central da Universidade Federal do Pará
(Universidade Federal do Pará, 2020-05-06) ALBUQUERQUE, Bruno Santana de; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
This dissertation proposes an energetic evaluation of a University Building transformation into a Zero Energy Building (ZEB), by using active methods such as Lighting System (LS), Photovoltaic System (PV) and Storage System (SS), and presents its application in the form of a case study. The purpose of this study is to analyze the energy balance between the UFPA Central Library, the implementation of the LS, the PV, the distribution system and the SS, aiming at the load autonomy. Satisfactory results were obtained for different scenarios created by the load variability, according to the university calendar, and the photovoltaic generation intermittency. The proposed LS reduced the building consumption by 44%. Using the PV system generates enough energy to supply most of the building load, however only 53% of this energy benefits the building, the energy surplus supplies other university loads. However, the SS integration allows the building to benefit 77% of the generated energy. Therefore, the proposed systems provide the ZEB concept to the study case building.
Acesso aberto (Open Access)
Contribuição da geração solar fotovoltaica na certificação de edificações públicas pelo RTQ-C e em edifícios de energia zero: laboratório de ensino da Universidade Federal do Pará
(Universidade Federal do Pará, 2020) SILVA, Hosaías Alves dos Prazeres; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
This work presents the contribution of solar photovoltaic generation as a renewable source in the methodology for obtaining Level A Label in Energy Efficiency certification and for the transformation into a Zero Energy Building, being applicable to buildings and public teaching laboratories. The methodology step-by-step essentially consists of two stages: the first, through an energetic diagnosis of the building analyzed, following the guidelines established in the Technical Regulation on Quality in Commercial, Service and Public Buildings - RTQ-C (in portuguese), resulting in a proposal of energetic, financial and environmental improvement processed with the aid of the RETScreen® software; and the second, dimensioning a photovoltaic solar generation system, based on local measurement data and the Meteonorm® software, as a bonus for obtaining the Level A Label of the RTQ-C levels and with energy production capacity that makes the energetic balance of the building as positive, making it a Zero Energy Building. In order to contextualize the relevance of the work and update the reader in the state of the art applicable to the methodology, a bibliographic review is presented, directed to the benefits of Energy Efficiency in public buildings and to the RTQ-C; to the current scenario, application and contribution of Solar Photovoltaic Energy in sustainable development, in obtaining nationally and internationally recognized classifications for public buildings; and the concepts currently used by the academic community to characterize Zero Energy Buildings. The bibliographic review and methodology were applied in a case study of the Laboratory of Electrical and Computer Engineering – LEEC (in portuguese), located at the Campus Guamá of the Federal University of Pará, with presentation of the energetic, financial and environmental results, showing that it is a solution to be applied in public institutions and buildings that have available space and similar infrastructure to that of the LEEC.
Acesso aberto (Open Access)
Acoplamento de modos guiados em cabos de pares trançados utilizando antenas com simetria radial no cenário terabit DSL
(Universidade Federal do Pará, 2020-03-26) SOUSA, Brenda Penedo Tavares de; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
The development of data transmission standards and access technologies has always been linked to the need to supply high data rates. Thus, technologies already implemented, such as the DSL (Digital Subscriber Line) system that uses twisted pairs for transmission, have been adjusting to support this growing data demand. In DSL systems, the twisted pairs are used as a transmission line, using the transverse electromagnetic mode (TEM). However, the physical limitations of the twisted pair as a transmission line prevent the system from achieving higher rates, needed to support fifth generation (5G) applications. Recently, it was proposed to use other transmission modes in the twisted pair, the higher order guided modes, as an alternative for this structure to be able to support transmission rates of the order of Terabits per second, having been termed as the Terabit DSL technology (TDSL). However, one of the challenges for this implementation is the coupling of the guided modes in the twisted pair, since they are not widely explored in the context of the propagation of higher-order guided modes, as simpler waveguides, such as Sommerfeld and Goubau. In this scenario, this dissertation aims to evaluate the coupling of the radiated signal between an antenna with radial propagation and the twisted pair cable, analyzing the electromagnetic behavior of structures. Considering that the twisted pair cable does not have a closed analytical model for the behavior of higher order modes, which propagate along these structures, all the results were obtained from numerical simulations in the software HFSS (High Frequency Structure Simulator).These results are in terms of the scattering parameter of the antenna and the electromagnetic field in the cable, making it possible to evaluate the coupling efficiency, the signal guidance and to predict the transmission rate available to users. The results obtained showed that the coupling between the antenna and the unshielded twisted pair cable reached levels of up to 83.83 % at frequencies of 0.15 THz, demonstrating a high coupling efficiency when compared to simpler scenarios in the literature, reaching levels on average 67 %. It was found that the use of these cables for data transmission is effective, managing to deliver rates of up to 1.737 Tbps in cables of up to 10 meters, while the rate forecasts for the TDSL scenario that consider the 100 % coupling reach levels of 2.013 Tbps.
Acesso aberto (Open Access)
Heurística para provisionamento dinâmico de recursos de hardware em redes híbridas de acesso via rádio considerando o efeito de maré
(Universidade Federal do Pará, 2020-03-06) FALCÃO, Igor Wenner Silva; CARDOSO, Diego Lisboa; http://lattes.cnpq.br/0507944343674734
The increase in the volume of services and applications, in addition to the accelerated growth in wireless access demands, represent significant challenges for the fifth generation of mobile networks, the 5G network. This increase in the volume of applications is a reflection of the growing number of devices connecting to the network, consuming data expansively, generating high data load. Another point of great impact is the large-scale daily migration of people in urban centers, causing the so-called Tide Effect. This promotes the space-time fluctuation of traffic throughout the day, making it difficult to control and manage the network (low efficiency in the use of hardware resources, load imbalance, underutilization and idleness of resources). Based on these indications and considering the knowledge of the service operators, data from the movement of users in New York City were extracted through an LBSN (Location-Based Social Network). Considering the expected high traffic demand for 5G and the problems arising from the Tidal Effect, this dissertation proposes a heuristic with two approaches to provisioning hardware resources (one based on the aggregate throughput and the other on the number of connected users). The results show that the network provisioning met the traffic variability of the scenario used, reducing the Probability of Blocking by 3.7%, maximizing the efficiency of the Base Band Unit (BBU) and quantifying the Small Cells (SCs) necessary to meet user demand.
Acesso aberto (Open Access)
Implantação de sistema fotovoltaico de baixo custo em arquitetura de rádio centralizada
(Universidade Federal do Pará, 2020-01-31) SARAIVA, Paline Alves; CARDOSO, Diego Lisboa; http://lattes.cnpq.br/0507944343674734
The growing demand for higher data rates and better quality of Internet services has resulted in high investments in mobile network infrastructure by operators. In this context, Centralized Radio Architecture (CRA) is a promising solution that relies on centralizing, sharing, and better allocating network resources, resulting in reduced deployment and operation costs when adequately planned. While the benefits of CRA are numerous, this cost reduction can also be enhanced through the adoption of alternative energy sources. One of the options for this, it is Growing demand for higher data rates and better quality of Internet services has resulted in high investments in mobile network infrastructure by operators. In this context, Centralized Radio Architecture (CRA) is a promising solution that relies on centralizing, sharing, and better allocating network resources, resulting in reduced deployment and operation costs when adequately planned. While the benefits of CRA are numerous, this cost reduction can also be enhanced through the adoption of alternative energy sources. One of the options for this equipment through optimization approaches, considering the energy demand of CRA, represents a challenge to be overcome. To this end, this work proposes a strategy to minimize the cost of imple- menting a photovoltaic system by reducing the number of inverters, formulated as an Integer Linear Programming (ILP) problem, to further reduce costs related to CRA. From the results, it is evident that the proposed optimization technique, implied in the average reduction of the Total Cost of Ownership (TCO) of the photovoltaic system in about 0.02 million reais, as well as in the environmental sustainability through the reduction of carbon dioxide emissions (CO2) in the atmosphere.
Acesso aberto (Open Access)
Avaliação de modos guiados em cabos de cobre para transmissão de dados em terabit por segundo
(Universidade Federal do Pará, 2020-03-27) SOUZA, Daynara Dias; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
Copper-based technologies have used twisted pair and coaxial cables as transmission lines, exploring TEM (Transverse Electromagnetic) mode to transmit data. In twisted pair technology, to ensure higher rates, it is necessary to increase the band frequencies, which also implies an increase in attenuation over the TEM mode, with a consequent limit on the link data rate. Applications for the latest generation (5G) systems require rates in the order of tens Gbps (Gigabit per second), practically impossible to meet due to their attenuation, even considering short links. In this context, to give a new breath to twisted pair cables, it was proposed to use them as waveguides, i.e., exploring their higher-order modes for transmission, in a system called Terabit DSL (Digital Subscriber Line). Such modes are of the TE (Transverse Electric) or TM (Transverse Magnetic) types, and arise when the wavelengths, associated to the operating frequencies, are of the same order or smaller than the cross-sectional dimensions of the twisted pair cable. A similar fact applies to coaxial cables. When using these modes, it is estimated transmission rates in the order of Tbps (Terabit per second) to be achieved on twisted pair cables. This enables, for example, to have twisted pair and coaxial cables as viable alternatives to the transport network in the future 5G system. Such predictions assume that the model based on the guided mode on a single bare conducting wire, known as the Sommerfeld model, describes the attenuation of the higher-order guided modes in a twisted pair. However, this model does not adequately describe twisted pair cables, given that its physical structure is much more complex. Therefore, a more accurate study on the characteristics of the higher-order modes present in twisted pair and coaxial cables is needed, aiming at predictions in complete agreement with the real structure and electromagnetic propagation through them. This work investigates the propagation of several guided modes in twisted pair and coaxial cables, from numerical simulations in the HFSS (High Frequency Structure Simulator) software, considering real constructive characteristics. Based on the results obtained, the aggregate data rate of each cable used as a waveguide was determined. The results obtained indicate that data rates of more than 1.7 Tbps in just one twisted pair can be reached for 10 meters in length, up to 6.1 Tbps in one cable with four twisted pairs and approximately 5.6 Tbps in one coaxial cable.