Teses em Engenharia Elétrica (Doutorado) - PPGEE/ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2317

O Doutorado Acadêmico inicio-se em 1998 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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Agora exibindo 1 - 6 de 6

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Uma abordagem SDN para virtualização de redes
(Universidade Federal do Pará, 2016-11-25) PINHEIRO, Billy Anderson; ABELÉM, Antônio Jorge Gomes; http://lattes.cnpq.br/5376253015721742
The virtual SDN networks (vSDNs) have emerged from the association of virtualization and Software-Dened Networking (SDN), providing greater control and better use of network resources. Several studies have already shown the feasibility and benets of this approach. However, the issue still lacks solutions that can virtualize a network in a scalable, intuitive and simplied manner. Thus, this thesis proposes an SDN approach to network virtualization with the aim of reducing the limitations on vSDNs. Therefore, it is suggested to adopt in network virtualization the separation between data plans (distributed) and control (centralized), the global network view and use of ow abstraction to manage the communication between the dierent points. To support our proposition, three solutions were developed: the CIM-SDN (Common Information Model for Software-Dened Networking), to enable the use of formal representation of the new elements of vSDNs; The NVP (Network Virtualization Proxy), to provide greater scalability by separating the control plane into centralized and decentralized parts; And Graph Virtualization Layer (GVL), to provide greater use of abstractions between the hypervisor and controllers, thereby simplifying the understanding and use of the network. Proof of concept tests was carried out for the three proposed solutions, demonstrating the feasibility of the approach.
Acesso aberto (Open Access)
Estratégias evolucionárias para otimização no tratamento de dados ausentes por imputação múltipla de dados
(Universidade Federal do Pará, 2016-02-16) LOBATO, Fábio Manoel França; SANTANA, Ádamo Lima de; http://lattes.cnpq.br/4073088744952858
The data analysis process includes information acquisition and organization in order to obtain knowledge from them, bringing scientific advances in various fields, as well as providing competitive advantages to corporations. In this context, an ubiquitous problem in the area deserves attention, the missing data, since most of the data analysis techniques can not deal satisfactorily with this problem, which negatively impacts the final results. In order to avoid the harmful effects of missing data, several studies have been proposed in the areas of statistical analysis and machine learning, especially the study of Multiple Data Imputation, which consists in the missing data substitution by plausible values. This methodology can be seen as a combinatorial optimization problem, where the goal is to find candidate values to substitute the missing ones in order to reduce the bias imposed by this issue. Metaheuristics, in particular, methods based in evolutionary computing have been successfully applied in combinatorial optimization problems. Despite the recent advances in this area, it is perceived some shortcomings in the modeling of imputation methods based on evolutionary computing. Aiming to fill these gaps in the literature, this thesis presents a description of multiple data imputation as a combinatorial optimization problem and proposes imputation methods based on evolutionary computing. In addition, due to the limitations found in the methods presented in the recent literature, and the necessity of adoption of different evaluation measures to assess the imputation methods performance, a multi-objective genetic algorithm for data imputation in pattern classification context is also proposed. This method proves to be flexible regarding to data types and avoid the complete-case analysis. Because the flexibility of the proposed approach, it is also possible to use it in other scenarios such as the unsupervised learning, multi-label classification and time series analysis.
Acesso aberto (Open Access)
FOG: função de objetivo genérico para roteamento e alocação de comprimentos de onda em redes ópticas com tráfego de demanda estática
(Universidade Federal do Pará, 2011-04-29) CARDOSO, Afonso Jorge Ferreira; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434; FRANCÊS, Carlos Renato Lisboa; http://lattes.cnpq.br/7458287841862567
This doctoral thesis proposes a mathematical formulation to simulate routing and wavelength assignment in optical networks, without the inclusion of constraints that are not inherent to the basic problem and in order to be applicable to any type of optical network with a static traffic demand. The establishment of a route followed by wavelength assignment is one of the keys to the smooth operation of an optical network, as this influences on how the resources of the network will be managed. Thus, the process of routing and wavelength assignment (RWA) in optical networks, needs a solution that seeks its optimization. However, despite numerous studies aiming to optimize RWA, it is observed that there is no solution, a priori, that could lead to a standardization of RWA process. Whereas consolidating standardization is desirable in the use of any technology, the thesis described in this work is a Generic Objective Function(GOF) that deals with the process of routing and wavelength assignment to establish a basis from which we can develop a standard or several standards for optical networks. The GOF was tested by simulation in the process of wavelength assignment (WA) and the RWA process as a whole. In both cases, tests were performed considering opaque networks, bringing surprising results, considering the simplicity of solution for a non-trivial problem.
Acesso aberto (Open Access)
Modelos paramétricos simples e causais para cabos de cobre apropriados para caracterização de enlaces em sistemas G.fast
(Universidade Federal do Pará, 2014-12-12) NUNES, Diogo Lobato Acatauassú; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
The G.fast is a new standard from the International Telecommunication Union that targets 1 Gb/s over short copper loops, using frequencies up to 212 MHz. This new technology requires accurate parametric cable models for simulation, design and performance evaluation tests. Most existing copper cable models were designed for the VDSL spectra - i.e., frequencies up to 30 MHz - and adopt assumptions that are violated when the frequency range is extended to G.fast frequencies. This thesis presents new simple and causal cable models that are able to accurately characterize copper loops composed by single or multiple segments, in both frequency and time domains. Results using G.fast topologies show that, besides being accurate, the new models are attractive due to their low computational cost and closed-form expressions for fitting their parameters to measurement data.
Acesso aberto (Open Access)
Output-only methods for damage identification in structural health monitoring
(Universidade Federal do Pará, 2017-04-27) SANTOS, Adam Dreyton Ferreira dos; FIGUEIREDO, Elói João Faria; http://lattes.cnpq.br/2315380423001185; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
In the structural health monitoring (SHM) field, vibration-based damage identification has become a crucial research area due to its potential to be applied in real-world engineering structures. Assuming that the vibration signals can be measured by employing different types of monitoring systems, when one applies appropriate data treatment, damage-sensitive features can be extracted and used to assess early and progressive structural damage. However, real-world structures are subjected to regular changes in operational and environmental conditions (e.g., temperature, relative humidity, traffic loading and so on) which impose difficulties to identify structural damage as these changes influence different features in a distinguish manner. In this thesis by papers, to overcome this drawback, novel output-only methods are proposed for detecting and quantifying damage on structures under unmeasured operational and environmental influences. The methods are based on the machine learning and artificial intelligence fields and can be classified as kernel- and cluster-based techniques. When the novel methods are compared to the state-of-the-art ones, the results demonstrated that the former ones have better damage detection performance in terms of false-positive (ranging between 3.65.4%) and false-negative (ranging between 0-2.6%) indications of damage, suggesting their applicability for real-world SHM solutions. If the proposed methods are compared to each other, the cluster-based ones, namely the global expectation-maximization approaches based on memetic algorithms, proved to be the best techniques to learn the normal structural condition, without loss of information or sensitivity to the initial parameters, and to detect damage (total errors equal to 4.4%).
Acesso aberto (Open Access)
Smartcom: uma arquitetura inteligente de gerenciamento de consumo de energia para smart home
(Universidade Federal do Pará, 2017-08-25) OLIVEIRA, Edvar da Luz; FRANCÊS, Carlos Renato Lisboa; http://lattes.cnpq.br/7458287841862567
With advances in information technology for a variety of areas, such as health and wellness, Smart Home based solutions using Internet of Things (IoT) technologies are gaining in popularity, including energy-saving alternatives based on Home Energy Management Systems (HEMS). This thesis defines an innovative architecture, called SmartCoM, which is implemented to monitor and manage residences using IoT technologies. Such a strategy involves defining the parameters that can affect the interoperability between measurement, management and the layers of data communication, which are the resources necessary for the hardware devices to perform the intended monitoring and measurement. In addition, an interface is defined by a middleware layer to integrate the management of external installations and the visualization of data through cloud services. The SmartCoM architecture is defined end-to-end in detail from the consumer's point of view and optimization strategies are employed for both the end customer and the utility. In order to evaluate the proposed architecture, a case study was elaborated, from which the viability of developing solutions for Smart Home according to the requirements described in SmartCoM is observed.

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