Made available in DSpace on 2016-08-17T18:39:52Z (GMT). No. of bitstreams: 1 6643.pdf: 3451089 bytes, checksum: 5e7632994736d4c2565adbbdcdfa0f15 (MD5) Previous issue date: 2015-02-13 / Financiadora de Estudos e Projetos / This work deals with the application of two arrays of sensors composing an electronic tongue for the quality evaluation of UHT-type milk, with the specific aim of detecting the antibiotic tetracycline in this dairy product. The electronic tongue device was made up by sensing units composed by gold interdigitated electrodes assembled onto glass substrates. Polyamide 6 (PA6) nanofibers and PA6/polyaniline (PAni) blends were deposited on the electrodes via the electrospinning technique. The nanofibers were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), FTIR spectroscopy, Raman spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA/DTG). The electronic tongue measurements were carried out using an impedance analyzer to collect capacitance and resistance data at 1 KHz. As chemometric tool we employed the Principal Component Analysis (PCA) technique to verify the efficiency of the electrospinning nanofibers-based electronic tongue in distinguishing different types of milk, as well as those contaminated by tetracycline. The results showed that the use of PAni for obtaining polymer blend fibers caused some small changes on the physical chemical properties compared to the neat PA6 fiber. However, PAni addition allowed a great reduction on the fiber diameter. Our results demonstrated that the electronic tongue system is a potential methodology to be used for classifying milk samples, in terms of fat content and quality regarding the presence of antibiotic tetracycline. The electronic tongue system system was able to detect milk samples contaminated up to 1ppb of tetracycline, regardless of milk fat content. / O trabalho versa sobre a utilização de dois arranjos de sensores químicos do tipo língua eletrônica para avaliação da qualidade de leite UHT (pasteurização por Ultra High Temperature) visando à detecção do antibiótico tetraciclina. Cada unidade sensorial da língua eletrônica foi composta por eletrodos interdigitados de ouro em substratos de vidro, sobre os quais foram depositadas nanofibras de Poliamida 6 (PA6) e suas blendas com polianilina (PAni) obtidas pela técnica de eletrofiação. As nanofibras foram caracterizadas por microscopia eletrônica de varredura (MEV), difração de raios-X (DRX), espectroscopia vibracional de absorção no infravermelho (FTIR), espectroscopia vibracional Raman, calorimetria exploratória diferencial (DSC) e termogravimetria (TG/DTG). A análise das amostras de leite com a língua eletrônica foi feita utilizando-se um analisador de impedância para coleta das medidas de capacitância e de resistência elétrica na frequência de 1 kHz. Empregou-se como ferramenta quimiométrica a técnica de Análise de Componentes Principais (PCA, do inglês Principal Component Analysis) para verificar a capacidade do conjunto de sensores em distinguir diferentes tipos de leite, bem como aqueles contaminados com tetraciclina. Os resultados demonstraram que a utilização da PAni na formulação empregada para obtenção das fibras de PAni/PA6 alteraram discretamente algumas das propriedades físicos químicas em relação à fibra sem PAni. Porém, ao se comparar o diâmetro das fibras da blenda em relação às fibras de PA6, observa-se que o acréscimo da PAni diminuiu consideravelmente o diâmetro destas. O sistema desenvolvido neste trabalho é uma promissora metodologia para a distinção e classificação de amostras de leite em relação ao percentual de gordura e à detecção de resíduos de tetraciclina, sendo capaz de detectar amostras contaminadas com 1ppb de tetraciclina, indiferente do percentual de gordura do leite analisado.

Currently, the most common strategy employed to detect DNA sequences is PCR (Polymerase Chain Reaction). Nevertheless, in the last few years research on DNA biosensors has increased significantly. Such sensors represent an alternative to PCR in the detection of specific DNA sequences, once they exhibit fast response, low limits of detection, and require simpler sample preparation. The development of a biosensor for detection of DNA from Human Papillomavirus type 18 is reported. To immobilise DNA probe onto indium-tin oxide (ITO) electrodes, a silanisation was carried out using 3-Aminopropyltryethoxysilane (APTES). Silanisation was studied and optimised using ultra-violet absorption spectroscopy, atomic force microscopy, fluorescence microscopy, and cyclic voltammetry. After immobilisation, the hybridisation with target sequence is detected by changes in surface properties of ITO electrode by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy, using the Ferri-Ferrocyante redox couple. The detection of synthetic target sequence was performed in the range of 12.5 to 100 nM, and 300nM for PCR products. The sensor did not show significative response for non-complementary sequence at 50 nM. This sensor can be applied for fast and low cost detection of HPV genetic material at nanomolar levels. / A estratégia mais empregada atualmente na detecção de sequência de DNA é a PCR (Reação em Cadeira da Polimerase). Contudo, nos últimos anos, a pesquisa em biossensores de DNA tem aumentado significativamente. Estes sensores representam uma alternativa a PCR na detecção de sequências específicas de DNA, uma vez que exibem resposta rápida, baixos limites de detecção e requerem preparação simples da amostra. Nesta dissertação descrito o desenvolvimento de um biossensor para a detecção do DNA do Papilomavirus Humano tipo 18. A fim de imobilizar a sequência de captura de DNA em eletrodos de óxido de estanho e índio (ITO), realizou-se uma silanização usando 3-Aminopropiltrietoxisilano (APTES). A reação de silanização foi estudada e otimizada através das técnicas de Espectroscopia de Absorção Ultravioleta, Microscopia de Força Atômica, Microscopia de Fluorescência e Voltametria Cíclica. Após a imobilização, a hibridização com a sequência alvo é detectada através de alterações nas propriedades de superfície do eletrodo através de Voltametria Cíclica e Espectroscopia de Impedância Eletroquímica, usando o par redox Ferri-ferrocianeto. A detecção da sequência alvo sintética foi realizada no intervalo de 12.5 a 100 nM, e para o produto de PCR, 300 nM. O sensor não demonstrou resposta significativa para sequência não complementar a 50 nM. Este sensor pode ser aplicado na detecção rápida e de baixo custo de material genético do HPV a níveis nanomolares.

O objetivo central deste trabalho consiste, a partir de um caso de ciclogênese ocorrido na costa leste do América do Sul, caracterizar as condições sinóticas favoráveis ao desenvolvimento de ciclones marítimos que possam gerar ressacas. Uma ciclogênese desenvolveu-se a leste da Argentina dia 03 de maio de 2001. Neste mesmo dia sobre o continente, existia um centro de alta pressão, que em conjunto com este ciclone marítimo formava um pista de vento de quadrante sul, paralelo ao continente, deixando o mar revolto, aumentando nível no extremo sul do Brasil, como registrado pela tábua de maré da cidade de Rio Grande, no estado do Rio Grande de Sul. No dia 04 de maio, à leste do estado de São Paulo, outro ciclone começa a se formar, intensificando a pista de vento pré existente. A metodologia utilizada afim de atingir os objetivos propostos, foi a da modelagem numérica. Utilizou-se modelo Regional Atmospheric Modeling System (RAMS). Foram utilizados como entrada dados de outros dois modelos, modelo Global e Modelo ETA. Para ambos os experimentos usando o RAMS, observou-se que o ciclone do dia 04 teve sua gênese em torno de 25ºS e 45ºW, se deslocando para sudeste. Na análise de mesoescala, foi observado que durante o período estudado os ventos sempre tiveram uma componente de sul e que os mais intensos ventos ocorreram em 28ºS e 48ºW, pois nesta região haviam maiores valores de gradiente de pressão, fluxo de calor sensível e fluxo de calor latente, já que é também nesta região onde se verifica a maior temperatura da superfície do mar.

Made available in DSpace on 2014-06-12T15:52:00Z (GMT). No. of bitstreams: 2 arquivo881_1.pdf: 4450080 bytes, checksum: 229fb90133942ff164163098f7f260a8 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Algumas cerâmicas supercondutoras apresentam um comportamento semicondutor em temperaturas acima da temperatura crítica, o que proporciona uma possibilidade de seu estudo em relação ao comportamento eletrônico de superfície com a pressão de oxigênio. Para os compostos da família PbSr(YCa)CuO esse comportamento semicondutor aparece em diversas composições, o que nos levou ao seu estudo e sua possível aplicação como um sensor de oxigênio. A rota de síntese proposta na literatura foi repetida, porém, houve difusão do chumbo, o que nos levou a rotas alternativas à mencionada pelo autor supracitado. Encontramos uma rota ideal, sintetizamos um grupo de amostras para estudo, fizemos o estudo dos compostos por difração de raios-X e encontramos fases distintas da requerida, como, por exemplo, a fase SrPbO3. Fizemos um estudo da variação da concentração do Ca e a sua influência na formação da estrutura PSYCCUO, assim como estudamos os efeitos da atmosfera de sinterização (oxigênio e nitrogênio). Caracterizamos as amostras utilizando difração de raios-Xe fizemos análises de condutividade eletrônica de superfície, usando o método das quatro pontas, em atmosfera e sob pressão de oxigênio (teste de sensor). Os resultados mostram que a amostra 1, tratada em atmosfera de oxigênio e cuja fase encontra-se acima, apresentou o melhor resultado dentre as demais

Submitted by Amanda Silva (amanda.osilva2@ufpe.br) on 2015-03-03T12:52:49Z No. of bitstreams: 2 Dissertação corrigida para impressão(4).pdf: 1678932 bytes, checksum: 7687bc1de75eec5968d00ef592573ccc (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-03T12:52:49Z (GMT). No. of bitstreams: 2 Dissertação corrigida para impressão(4).pdf: 1678932 bytes, checksum: 7687bc1de75eec5968d00ef592573ccc (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2013-03 / Com a crescente utilização das fontes de nêutrons em diferentes áreas, a demanda por detectores de nêutrons cresceu significativamente nas últimas décadas. A busca por detectores de menor custo impulsiona pesquisas ao redor do mundo através de materiais que possam ser utilizados com esse fim. Materiais poliméricos por seu baixo custo e fácil manuseio, vêm sendo testados em diversos campos da instrumentação nuclear. O presente trabalho teve como objetivo estudar as mudanças causadas na condutividade elétrica do polietileno linear de baixa densidade (PELBD) com carga de carbono, quando submetido à radiação de nêutrons. O material, com características elétricas de semicondutor, foi submetido a um fluxo de nêutrons em um reator nuclear de pesquisa. Amostras em triplicata, com geometrias idênticas, foram preparadas e irradiadas em diferentes intervalos de tempos para analisar as alterações na condutividade elétrica do material semicondutor. O método de análise consistiu em injetar uma corrente elétrica constante em cada amostra, gerada por um multímetro padrão primário, o qual fornece diretamente o valor da resistência elétrica. Os resultados demonstram que, pós-irradiação, o material apresentou uma variação na sua propriedade elétrica de acordo com o tempo de exposição. Considerando a geometria das amostras e o fluxo de nêutrons adotados, conclui-se que, pelo fato de ser um procedimento de mensuração via propriedades elétricas, o material pode funcionar mensurando um fluxo de nêutrons em tempo real.

University of Macau / Faculty of Science and Technology / Department of Electrical and Computer Engineering

Automated devices enabled by wireless communications are deployed for a variety of purposes. As they become more ubiquitous, their interaction becomes increasingly important for coexistence when sharing a scarce resource, and for leveraging potential cooperation to achieve larger design goals. This thesis investigates the use of game theory as a tool for design and analysis of networked systems of automated devices in the areas of naval defence, wireless environmental monitoring through sensor networks, and cognitive radio wireless communications. In the first part, decentralized operation of naval platforms deploying electronic countermeasures against missile threats is studied. The problem is formulated as a stochastic game in which platforms independently plan and execute dynamic strategies to defeat threats in two situations: where coordination is impossible due to lack of communications, and where platforms hold different objectives but can coordinate, according to the military doctrine of Network Enabled Operations. The result is a flexible, robust model for missile deflection for advanced naval groups. Next, the problem of cooperative environmental monitoring and communication in energy-constrained wireless sensor networks is considered from a game-theoretic perspective. This leads to novel protocols in which sensors cooperatively trade off performance with energy consumption with low communication and complexity overhead. Two key results are an on-line adaptive learning algorithm for tracking the correlated equilibrium set of a slowly varying sensor deployment game, and an analysis of the equilibrium properties of threshold policies in a game with noisy, correlated measurements. Finally, the problem of dynamic spectrum access for systems of cognitive radios is considered. A game theoretic formulation leads to a scheme for competitive bandwidth allocation which respects radios' individual interests while enforcing fairness between users. An on-line adaptive learning scheme is again proposed for negotiating fair, equilibrium resource allocations, while dynamically adjusting to changing conditions. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Diabetes Mellitus is a common chronic disease that is an ever-increasing public health issue. Continuous glucose monitoring has been shown to help diabetes mellitus patients stabilize their glucose levels, leading to improved patient health. Hence, a glucose sensor, capable of continuous real-time monitoring, has been a topic of research for three decades. Current methods of glucose monitoring, however, require taking blood samples several times a day, hence patient compliance is an issue. Optical methods are one of the painless and promising methods that can be used for blood glucose predictions. However, having accuracies lower than what is acceptable clinically has been a major concern. To improve on the accuracy of the predictions, the signal-to-noise ratio in the spectrum can be increased, for which the use of thermally tunable vertical cavity surface emitting lasers (VCSELs) as the light source to obtain blood absorption spectra, along with a multivariate technique (Partial Least Square (PLS) techniques) for analysis, is proposed. VCSELs are semiconductor lasers with small dimensions and low power consumption, which makes them suitable for implants. VCSELs provide higher signal-to-noise ratio as they have high power spectral density and operate within a small spectrum. In the current research, experiments were run for the preliminary investigations to demonstrate the feasibility of the proposed technique for glucose monitoring. This research involves preliminary investigations for developing a novel optical system for accurate measurement of glucose concentration. Experiments in aqueous glucose solutions were designed to demonstrate the feasibility of the proposed technique for glucose monitoring. In addition, multivariate techniques, such as PLS, were customized for various specific purposes of this project and its preliminary investigation. This research will lead to the development of a small, low power, implantable optical sensor for diabetes patients, which will be a major breakthrough in the area of treating diabetes patients, upon successful completion of this research and development of the device. / Applied Science, Faculty of / Graduate

Wireless sensor and robot networks (WSRNs) are an integration of wireless sensor network (WSNs) and multi-robot systems. They comprise of networked sensor and mobile robots that communicate via wireless links to perform distributed sensing and actuation tasks in a region of interest (ROI). In addition to gathering and reporting data from the environment, sensors may also report failures of neighboring sensors or lack of coverage in certain neighborhood to nearby mobile robot. Once an event has been detected, robots coordinate with each other to make a decision on the most appropriate way to perform the action. Coverage can be established and improved in different ways in wireless sensor and robot networks. Initial random sensor placement, if applied, may be improved via robot-assisted sensor relocation or additional placement. One or more robots may carry sensors and move within the ROI; while traveling, they drop sensors at proper positions to construct desired coverage. Robots may relocate and place spare sensors according to certain energy optimality criteria. This thesis proposes a solution, which we call Election-Based Deployment (EBD), for simultaneous sensor deployment and coverage maintenance in multi-robot scenario in failure-prone environment. To our knowledge, it is the first carrier-based localized algorithm that is able to achieve 100% coverage of the ROI with multiple robots in failure-prone environment since it combines both sensor deployment and coverage maintenance process. We can observe from the simulation results that EBD outperforms the existing algorithms and balances the workload of robots while reducing the communication overhead to a great extent.

In this thesis, we propose a suite of Evolutionary Algorithms (EA)-based protocols to solve the problems of clustering and routing in Wireless Sensor Networks (WSNs). At the beginning, the problem of the Cluster Heads (CHs) selection in WSNs is formulated as a single-objective optimization problem. A centralized weighted-sum multi-objective optimization protocol is proposed to find the optimal set of CHs. The proposed protocol finds a predetermined number of CHs in such way that they form one-hop clusters. The goal of the proposed protocol is to enhance the network's energy efficiency, data delivery reliability and the protocol's scalability. The formulated problem has been solved using three evolutionary approaches: Genetic Algorithms (GA), Differential Evolution (DE) and Particle Swarm Optimization (PSO) and we assessed each of their performance. Then, a PSO-based hierarchical clustering protocol that forms two-hop clusters is proposed to investigate the effect of the number of CHs on network's energy efficiency. This protocol enhances the WSN's energy efficiency by setting an upper bound on the number of CHs and trying to minimize the number of CHs compared to that upper bound. It also maximizes the protocol's scalability by using two-hop communication between the sensor nodes and their respective CHs. Then, a centralized weighted-sum PSO-based protocol is proposed for finding the optimal inter-cluster routing tree that connects the CHs to the Base Station (BS). This protocol is appropriate when the CHs are predetermined in advance. The proposed protocol uses a particle encoding scheme and defines an objective function to find the optimal routing tree. The objective function is used to build the trade-off between the energy-efficiency and data delivery reliability of the constructed tree. Finally, a centralized multi-objective Pareto-optimization approach is adapted to find the optimal network configuration that includes both the optimal set of CHs and the optimal routing tree. A new individual encoding scheme that represents a joint solution for both the clustering and routing problems in WSNs is proposed. The proposed protocol uses a variable number of CHs, and its objective is to assign each network node to its respective CH and each CH to its respective next hop. The joint problem of clustering and routing in WSNs is formulated as a multi-objective minimization problem with a variable number of CHs, aiming at determining an energy efficient, reliable ( in terms of data delivery) and scalable clustering and routing scheme. The formulated problem has been solved using two state-of-the-art Multi-Objective Evolutionary Algorithms (MOEA), and their performance has been compared. The proposed protocols were developed under realistic network settings. No assumptions were made about the nodes' location awareness or transmission range capabilities. The proposed protocols were tested using a realistic energy consumption model that is based on the characteristics of the Chipcon CC2420 radio transceiver data sheet. Extensive simulations on 50 homogeneous and heterogeneous WSN models were evaluated and compared against well-known cluster-based sensor network protocols.