Programa de Pós-Graduação em Engenharia Elétrica e de Computação
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Master Thesis Block uma ferramenta para reconhecimento e bloqueio de ataques a redes de computadores(Universidade Federal do Rio Grande do Norte, 2002) Amaral, Flávio Marcelo Cavalcante Bandeira do; Pires, Paulo Sérgio da Motta; Oliveira, Luiz Affonso Henderson Guedes de; http://lattes.cnpq.br/7987212907837941; Filho Souza, Guido Lemos de; http://lattes.cnpq.br/6614550860293610; http://lattes.cnpq.br/5093444018164760; Bezerra, João BatistaOperating Systems and hosts connected to networks can be a target for attacks. The in- creasing number and frequency of those attacks aimed at Internet connected institutions are very high as well as the risks of steal and the unauthorized access of their Information. The damage can range from a single reading to the modification of proprietary Information. NIDS, NetWork Intrusion Detection Systems, are tools used to detect attacks aimed at Online Systems. In this research, we have developed a tool named Block, which uses a free and open source NIDS to generate Cisco access lists as a response to detected attacks. Beyond authomatically blocking attacks, the developed program sends e-mail messages to the System administrator to notify about the actions taken by the tool.Master Thesis Identificação de golfinhos através de Técnicas de Processamento Inteligente de Imagens(Universidade Federal do Rio Grande do Norte, 2003-03) Magalhães, Kaiser Magalde Costa; Centeno, Tania Mezzadri; Gonçalves, Luiz Marcos Garcia; Alsina, Pablo Javier; Medeiros, Adelardo Adelino Dantas deThe inteligente processing of digital images applied to the identification of dolphins is based on several tecniques as preprocessing and segmentation of images, neural networks, mathematical morphology and geometrical transformation; they are combined to allow the dolphin images to be treated to identify different specimen. The analyzed dolphins in this work are from the S. fluviatilis species usually known as boto-cinza in Portuguese, and live in a sea area between Pipa and Tabatinga, two beaches in Rio Grande do Norte - Brazil. One of their main characteristics is a large dorsal fin. This fin acts as a dolphin identity card, since the aggressions suffered by the animal stay registered there. Another important characteristic is the own shape of the fin. In this work, we have implemented several algorithms to preprocess the image using the KLT theory and auto-contrast. We have used mathematical morphology tecniques to help extracting the characteristics and neural networks to classify the specimen. To identify the fin curvature we used two parametric cubic polynomials, associated to the two sides of the fin and both originating at the fin peak. Notches are detected at each curve and mapped to the parametric space of the polynomials. Some remarkable points are informed by the user to normalize the polynomials. The final data are maintained in a database and used to identify new images. Experimental results show that the selected characteristics are good identifiers, correctly classifying different specimens and recognizing with few errors the same specimen in different images.Doctoral Thesis Uma arquitetura para análise de agrupamentos sobre bases de dados distribuídas(2009-03-06) Gorgônio, Flavius da Luz e; Costa, José Alfredo Ferreira; ; ; http://lattes.cnpq.br/7375286161719016; Martins, Allan de Medeiros; ; Canuto, Anne Magaly de Paula; ; Barreto, Guilherme de Alencar; ; Adeodato, Paulo Jorge Leitão;Data mining can be defined as a set of techniques for knowledge extraction and search of useful and previously unknown patterns in large multidimensional databases. Clustering is the process of discovering data clusters within high-dimensional databases, based on similarities, with a minimal knowledge of their structure. Distributed data clustering is a recent approach to deal with distributed databases, since traditional clustering algorithms require centering all databases in a single dataset. Moreover, current privacy requirements in distributed databases demand algorithms with the ability to process clustering securely. Thus, an increasing need of methods to mining data stored in a distributed way has motivated the development of algorithms to analyze each database separately and to combine the partial results to get a final result. This thesis presents a framework for cluster analysis in distributed databases using traditional algorithms, as K-means and self-organizing maps. This approach reduces significantly the amount of data transferred between remote units and the central unit. The framework includes a strategy, based on vectorial quantization, that extract a representatives subset, in order to get partial views of the existing clusters in each horizontal and/or vertical partitions of the database. Later, the representatives of each local unit are sent to the central unit, which carry out a combination of the partial results applying a clustering algorithm over all representative subsets. The experimental results with different datasets show that the framework proposed obtains results very close and with effectiveness comparable to conventional data mining techniques, where all the databases are transferred to a central unit in the pre-processing stage.Master Thesis Firewall de aplicação para redes industriais(Universidade Federal do Rio Grande do Norte, 2009-07) Batista Júnior, Aguinaldo Bezerra; Pires, Paulo Sérgio da Motta; ; http://lattes.cnpq.br/5093444018164760; ; http://lattes.cnpq.br/8027998782770972; Rocha Neto, José Sérgio da; ; http://lattes.cnpq.br/9085919442313408; Brito Junior, Agostinho de Medeiros; ; http://lattes.cnpq.br/0958617290020120; Melo, Jorge Dantas de; ; http://lattes.cnpq.br/7325007451912598The utilization of firewalls is a widely accepted approach when protecting Automation Technology (AT) environments from Information Technology (IT) ones. This dissertation covers the development of a firewall system for TCP/IP-based industrial networks which can protect automation devices from abnormal traffic. Thus, all non-conformity traffic or traffic which does not respect the imposed constraints is considered abnormal and must be blocked. It was developed an user-space application which filters traffic in the application layer. The industrial protocol chosen as a case study was Modbus/TCP, due to its simplicity, abundant documentation and high relevance for current industrial networks.Master Thesis Controle adaptativo indireto por modelo de referência e estrutura variável(Universidade Federal do Rio Grande do Norte, 2003-02) Oliveira, Josenalde Barbosa de; Araújo, Aldayr Dantas de; http://lattes.cnpq.br/3165031680223608; ; http://lattes.cnpq.br/0503501772199456; Barbalho, David Simonetti; ; http://lattes.cnpq.br/7208859488227503; Mota, Francisco das Chagas; ; http://lattes.cnpq.br/1640808531484356; Costa, Ramon Romankevicius; ; http://lattes.cnpq.br/7179082749910428; Cunha, Caio Dorneles; ; http://lattes.cnpq.br/2348572465951605An indirect approach to the variable structure model reference adaptive control with robustness to parametric uncertainties and disturbances as well as fast transient is proposed, being therefore an unedited work. In the direct approach, the switching laws are designed to the controller parameters. On the other hand, in the indirect approach, the switching laws are designed to the plant parameters, which present uncertainties that can be known easier than in the direct approach, since they are related with physical parameters, such as inertia moments, etc., being its main advantage the possibility to get an easier design. The model reference adaptive control is reviewed, in both approaches (direct and indirect), as well as the variable structure model reference adaptive control, in its direct approach. For a better understanding of the proposed technique is presented an introduction to the variable structure systems. For each mentioned technique, stability proofs and simulations results are shown. For the particular proposed method was also carried out an experimental test on a three-phase induction motor.Doctoral Thesis Verificação formal automatizada para sistemas de raciocínio procedural (PRS) utilizando redes de petri coloridas (RPC)(Universidade Federal do Rio Grande do Norte, 2005-09-02) Araújo, Ricardo Wagner de; Medeiros, Adelardo Adelino Dantas de; ; http://lattes.cnpq.br/6787525856497063; ; http://lattes.cnpq.br/4189661112532670; Botelho, Sílvia Silva da Costa; ; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4723628Z9; Dórea, Carlos Eduardo Trabuco; ; http://lattes.cnpq.br/0143490577842914; Alsina, Pablo Javier; ; http://lattes.cnpq.br/3653597363789712; Oliveira, Luiz Affonso Henderson Guedes de; ; http://lattes.cnpq.br/7987212907837941Master Thesis Contribuições para a detecção e identificação de faltas em inversores Multiníveis(Universidade Federal do Rio Grande do Norte, 2008-11-19) Melo, Liviane Catarine Almeida; Ribeiro, Ricardo Lúcio de Araújo; ; http://lattes.cnpq.br/6628177274865696; ; http://lattes.cnpq.br/3027521463114311; Araújo, Aldayr Dantas de; ; http://lattes.cnpq.br/3165031680223608; Silva, Edison Roberto Cabral da; ; http://lattes.cnpq.br/7577873305205472This work presents contributions in the detection and identication of faults in multilevel inverters through the study of the converters behavior under these operation conditions. Basically, the approached fault consists of an open-circuit in any switch of a three-level clamped diode inverter. The converter operation is characterized in the pre and post-fault states. A wave form behavior analysis of the pole voltage, phase current and dc-bus current is also done, which highlights characteristics that allow the detection of failure and, even, under favorable conditions, the identication of the faulty device. A compensation strategy of the approached fault (open-switch) is also investigated with the purpose of maintaining the driving system operational when a failure occurs. The proposed topology uses SCRs in parallel with the internal switches of the inverter, which allows, in some occasions, the full utilization of the dc-busMaster Thesis Uma nova proposta de antena planar multibanda para comunicações móveis(Universidade Federal do Rio Grande do Norte, 2007-02-22) D'assunção Júnior, Adalido Gomes; Mendonça, Laércio Martins de; ; http://lattes.cnpq.br/1853488415531363; ; Martins, Ronaldo de Andrade; ; http://lattes.cnpq.br/0978273656336966; Sousa, Fernando Rangel de; ; http://lattes.cnpq.br/9092018794878372; Gomes Neto, Alfrêdo; ; http://lattes.cnpq.br/1403715441701958The great interest observed in wireless communication systems has required the development of new configurations of microstrip antennas, because they are easily built and integrated to other microwave circuit components, which is suitable for the construction and development of planar antenna arrays and microwave integrated circuits. This work presents a new configuration of tapered microstrip antenna, which is obtained by impressing U-slots on the conducting patch combined with a transmission line matching circuit that uses an inset length. It is shown that the use of U-slots in the microstrip antenna conducting patch excites new resonating modes, that gives a multiband characteristic for the slotted microstrip antenna, that is suitable for applications in communication systems that operates several frequencies simultaneously. Up to this date, the works reported in the literature deals with the use of Uslotted microstrip rectangular antennas fed by a coaxial probe. The properties of a linear array of microstrip patch tapered antennas are also investigated. The main parameters of the U slotted tapered microstrip antennas are investigated for different sizes and locations of the slots impressed on the conducting patch. The analysis of the proposed antenna is performed by using the resonant cavity and equivalent transmission line methods, in combination with a parametric study, that is conducted by the use of the Ansoft Designer, a commercial computer aided microwave software well known by its accuracy and efficiency. The mentioned methods are used to evaluate the effect in the antennas parameters, like resonant frequency and return loss, produced by variations of the antenna structural parameters, accomplished separately or simultaneously. An experimental investigation is also developed, that consists of the design, construction and measurement of several U slotted microstrip antenna prototypes. Finally, theoretical and simulated results are presented that are in agreement with the measured ones. These results are related to the resonating modes identification and to the determination of the main characteristics of the investigated antennas, such as resonant frequency, return loss, and radiation patternMaster Thesis Controlador adaptativo backstepping a estrutura variável(Universidade Federal do Rio Grande do Norte, 2008-11-20) Queiroz, Kurios Iuri Pinheiro de Melo; Araújo, Aldayr Dantas de; ; http://lattes.cnpq.br/3165031680223608; ; http://lattes.cnpq.br/7489022506091803; Oliveira, Josenalde Barbosa de; ; http://lattes.cnpq.br/0503501772199456; Costa, Ramon Romankevicius; ; http://lattes.cnpq.br/7179082749910428Master Thesis Controlador adaptativo por modelo de referência e estrutura variável aplicado ao controle de ângulo de carga e fluxo de campo de um gerador síncrono(Universidade Federal do Rio Grande do Norte, 2008-10-23) Fernandes, Marcus Vinícius Araújo; Araújo, Aldayr Dantas de; ; http://lattes.cnpq.br/3165031680223608; ; http://lattes.cnpq.br/1751575325705144