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Lemos, Marta Cruz Gomes de. "Mixed senses. Sinestesia como base criativa no design de moda." Master's thesis, Universidade Técnica de Lisboa. Faculdade de Arquitectura, 2011. http://hdl.handle.net/10400.5/2916.
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Tese de Mestrado em Design de ModaEsta investigação explora o fenómeno da Sinestesia - mistura e associação de sentidos - como base criativa na área do Design de Moda. Será que as percepções sinestésicas de um indivíduo fornecem dados suficientes para serem a única base de inspiração na concepção de vestuário? Para constituir hipótese, foi efectuada uma investigação sobre a sinestesia, as suas variantes e as suas condicionantes, e sobre a concepção de vestuário e os elementos essenciais a ter em conta no desenvolvimento de uma colecção de moda. A hipótese colocada pela investigadora foi que de facto a sinestesia pode ser a única inspiração na concepção de uma colecção, dado que as percepções sinestésicas incluem cores, formas, texturas e manchas/padrões - dados que vão de encontro aos elementos do design essenciais à concepção de vestuário. Para provar a hipótese, realizou-se um projecto experimental envolvendo um grupo de casos de estudo, todos sinestésicos, que culminou na concepção de um projecto de moda baseado exclusivamente nos dados provenientes dessa experiência. O projecto foi o principal objectivo da investigação e constitui a validação da hipótese, sendo a sua prova prática. A colecção final é um espelho do trabalho de investigação, dos quatro sinestésicos que participaram na experiência e do fenómeno da sinestesia em si. Obteve-se, assim, o resultado perfeito para uma investigação cuja uma temática é tão fascinante e fora do comum. Este projecto de investigação prova ainda que é possível a interligação de duas áreas completamente distintas - a Neurologia e o Design de Moda - de maneira harmoniosa e bem sucedida, originando um resultado inovador, que faz jus à temática da sinestesia e é enriquecedor para ambas as áreas.
This investigation explores the phenomenon of Synesthesia - a mix and association of senses - as a creative basis for Fashion Design. Can synesthetic perceptions provide enough data to be the only inspiration in the creation of clothes? In order to create an hypothesis, a deep investigation was carried out, focusing synesthesia and its variants, as well as the conception of clothing and the elements we have to keep in mind while creating a collection. The hypothesis was that indeed synesthesia could be the only inspiration in the conception of a collection, since synesthetic perceptions include colors, shapes, textures and patterns – all of which conform to the design elements that are essential to the conception of clothing. In order to prove this hypothesis, an experimental project took place, implicating a group of case studies, all synesthetes, that culminates with the conception of a fashion project based exclusively on the data gathered from that experience. This project was the main goal of the investigation and it is the validation of the hypothesis, its practical proof. The collection mirrors the investigation, the four synesthetes that took part in the experience and the phenomenon of synesthesia itself. This way, starting with a very unusual, peculiar and fascinating subject, we managed to reach a perfect conclusion for our investigation,. This project also proves that it is possible to connect two completely different areas – Neurology and Fashion Design – harmoniously and successfully, creating an innovative result that merits synesthesia and enriches both areas.
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Lange, Barbara. "The Impact of an Interdependent Conferencing Activity in an Online RN-BSN Practicum Clinical Conference on Psychologocial Sense of Community." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2256.
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RN-BSN students enrolled in a clinical course often have limited or no interaction with other students within the course due to geographic distance and individual preceptor assignments. Learning is often restricted to a student and his/her preceptor and instructor. Geographic and physical distance factors inhibit a student's perception of connectedness and learning. Interdependent interaction between peers, the instructor, and the professional community may increase student achievements and enhance a sense of connectedness. The purpose of this study was to assess the effects of an Interdependent Conferencing Activity (ICA) in an online clinical conference on RN-BSN students' Psychological Sense of Community (PSOC). Students' perception of learning and connectedness are the secondary outcome measurements for PSOC. The ICA was developed to promote interdependence and interaction to enhance PSOC. The research supports the hypothesis that implementation of an ICA will increase PSOC in RN-BSN students in the intervention group when compared to the control and comparison group in an online clinical conference. An experimental, pre-test, post-test research study was conducted to test the hypothesis that implementation of an ICA will increase PSOC in RN-BSN students in the intervention group when compared to the control and comparison group in an online clinical conference. RN-BSN students enrolled in their clinical practicum course (two sections over two semesters) were recruited to participate at the beginning of the course. Each of the sections had a web component. Those who consented to participate were randomly assigned to one of three groups: control, comparison, or intervention. The control group responded to focused questions; the comparison group answered questions related to the application of knowledge gained within their practicum experiences; and the intervention group responded to inquiry about the same theoretical concept from the perspective of their total professional experience, citing examples to support or change evidence-based practice. The Classroom Community Scale (CCS) developed by Rovai (2002c) for use in online course assessment was administered at the beginning and end of the course to measure PSOC and its subscales of learning and connectedness. A total of 67 students participated (control n = 20, comparison n = 22, intervention n = 25). The majority of subjects were female (91%) and Caucasian (83.6%). Their average age was 31.4 years and they had an average of 6.4 years of experience as an RN. With the exceptions of years of experience, demographic characteristics were similar for each group. There was a significant difference for PSOC among the groups (RMANOVA; p = <.001). Post hoc analyses indicated a significant difference in the total PSOC and the subscales of Connectedness and Learning between the experimental group and both the control and comparison groups. Implementation of an ICA enhanced PSOC in an online RN-BSN online conference. The development and implementation of the intervention supported the research hypothesis, the 21st Century educational factors, and the use of experiential learning in the profession of nursing. This research addressed two critical gaps in literature: a paucity of research available on clinical conferencing in nursing, and clinical conferencing within the RN-BSN population. The ICA is an action that could easily be implemented in online conferencing.Ph.D.
School of Nursing
Other
Nursing PhD
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Schulte, Thomas Rudolf. "Entwicklung von sauerstoffpermeablen Keramikmembranen für NOx-Sensoren /." Düsseldorf : VDI-Verl, 2000. http://www.gbv.de/dms/bs/toc/31386330x.pdf.
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Toshniwal, Smita. "Dynamic Mobility of Multiple Base Stations in an Event driven Static Wireless Sensor Network." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1249666898.
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Vaswani, Mohit Suresh. "BLE Controller Module for Wireless Sensor Networks." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1011776/.
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Sensors have been an integral part of our life since a long time. Traditionally, the transmit information to a data collection center through a physical wire. However, with the introduction of Bluetooth Low Energy (BLE) communication protocol, more research is being done into the field of wireless sensor networks (WSN). BLE was introduced to target low power applications. The CC2650 Launchpad designed by Texas Instruments (TI) can lead to a bulky final product. The aim was to design hardware for the CC2650 micro-controller with the aim of making it more compact for use in WSNs. A top-down approach was used wherein the available product is studied to identify the redundant and reverse engineer it to design a new product. A 2 layer printed circuit board (PCB) was designed which resulted in a 64 percent decrease in size compared to the Launchpad. Also, experiments were performed to test the proof of concept.
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Rosenberger, Andressa Giombelli. "Eletrofiação no preparo de sensor eletroquímico a base de nanotubos de carbono." Universidade Estadual do Oeste do Paraná, 2017. http://tede.unioeste.br/handle/tede/3098.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Estado do Paraná (FA)
Water is a vital element in human health and a determining factor in the pace of human evolution; however, the presence of emerging pollutants threatens its quality and may endangers the well-being of people and the environment. This work stands out for the development of a composite material based on nanotechnology to be used as an electroanalitic sensor in aqueous solutions with the Metronidazole drug which is considered an emerging pollutant. Initially the polymeric fibers were produced based on ecovio® and carbon nanotubes multilayer (MWCNT’s). In order to evaluate the parameters that could interfere in the process of electrospinning and to understand the interaction between the polymer and the MWCNT’s, a fractional factorial design and physicochemical characterizations analysis were used, which were: optical micrography scanning electron microcopy (SEM), mechanical analysis, wettability by contact angle, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DSC) and X-ray diffraction. For the porpuse of fabricating the sensor, the fibers were calcinated and the obtained residue was characterized by SEM and FTIR. The statistical data and the images of optical microscopy and SEM showed that the addition of MWCNT’s is the parameter that most influences the diameter of the obtained microfibers (1.16 ± 0.22 µm) so that their presence decreases the diameter and results in fibers more uniform and homogeneous. After selecting the ideal conditions an experiment was done with the following process and solution parameters: concentration of ecovio® 15,00% (m/v) and MWCNT’s 0,60% (m/v); flow: 1.80 mL.h-1; distance: 16 cm and applied voltage: 18 kV. The morphology and diamater os the fibers was obtained using SEM images and showed an average diameter of 1.59±0.61 µm. It was also demonstrated a better mechanical performance after the addition of MWCNT’s to the fibers, so that they presented greter elasticity (180%) and significant increase on the elastic resistance (163%) and tensile strength (107%), besides the analysis of wettability from the contact angle suggest that the carbon-based nanomaterial is inside the polymeric microfibers. The interactions between the MWCNT’s and the polymer were better evaluated by vibracional aspects by Fourier transform infrared spectroscopy (FTIR) and showed the interaction between the MWCNT’s and the functional group C=O characteristic of the group ester of the polymers. The analysis of thermogravimetry (TGA) demonstrated a higher stability. The thermogravimetric analysis (TGA) showed a higher stability of the poly (lactic acid) component and lower resistances of the poly (butylene adipate co-terephtalate) component in the polymer blend. Besides it was necessary a constant temperature of 550 ºC during 50 minutes to the total degradation of the polymer. By differential thermal analysis (DSC) it was possible to confirm the interactions proposed by FTIR and TGA, which indicate that the interaction occurs preferentially with the aliphatic chains of the ecovio® polymer. After the calcination of the fibers, the obtained residue was characterized by FTIR and MEV and variations in the characteristics of pure MWCNT's can be observed, with reduction of the corboxylic groups for the calcined and electrospun/calcined MWCNT's, as well as the formation of lamella for the MWCNT's electrospun/calcined. The electrochemical measurements using the cyclic voltammetry technique showed that the sensor is promising for determination of Metronidazole.
A água é um elemento vital e determinante no ritmo da evolução humana, contudo a presença de poluentes emergentes ameaça sua qualidade e põe em risco o bem estar humano e ambiental. O presente trabalho destaca-se por desenvolver um material compósito formado por poli (butileno adipato co-tereftalato) (PBAT) e poli (ácido lático) (PLA) para ser utilizado como sensor eletroanalítico em soluções aquosas contendo o fármaco metronidazol. Inicialmente produziu-se fios poliméricos a base de ecovio® e nanotubos de carbono de paredes múltiplas (MWCNT’s). A fim de avaliar os fatores interferentes do processo e compreender a interação entre o polímero e os MWCNT’s utilizou-se um planejamento fatorial fracionário e análises de caracterização físico-química tais como: micrografia ótica, microscopia eletronica de varredura (MEV), análise mecanica, molhabilidade por angulo de contato, espectroscopia vibracional de infravermelho por transformada de Fourrier, análise termogravimétrica (TGA), calorimetria exploratória diferencial (DSC) e difratometria de raio X (DRX).Para a construção do sensor eletroquímico as fibras foram calcinadas e o resíduo obtido foi caracterizado pelas ténicas de MEV e FTIR. Os resultados estatísticos em conjunto com as imagens de microscopia ótica e MEV demonstram que a adição de MWCNT’s é o parâmetro que mais influência no diâmetro das microfibras (1,16 ± 0,22 µm) obtidas, de modo, que sua inserção diminui este parâmetro deixando as fibras mais uniformes e homogêneas. Após a escolha das condições ideais procedeu-se um experimento com os seguintes parâmetros da solução e do processo de eletrofiação: ecovio® 15,00% (m/v) e MWCNT’s 0,60% (m/v); fluxo: 1,80 mL.h-1; distância: 16 cm e tensão: 18 kV. A morfolagia e o diâmetro das fibras foram realizadas usando as imagens de MEV e apresentam diâmetro médio de 1,59±0,61 µm. Foi evidenciado também um melhor desempenho mecanico após a inserção de MWCNT’s às fibras de modo que as fibras apresentam maior elasticidade (180%) e um aumento significativo da resistência elástica (163%) e tensão de ruptura (107%). Ademais a análise de molhabilidade por ângulo de contato sugere que o nanomaterial a base de carbono encontra-se no interior das microfibras poliméricas. As interações entre o MWCNT’s e os polímeros foram melhor avaliadas pelos espectros vibracionais de infravermelho por transformada de Fourrier (FTIR) e evidenciam a interação entre MWCNT’s e o grupamento funcional C=O, característicos dos grupamentos ésteres dos polímeros. As análises de termogravimetria (TGA) demonstram uma maior estabilidade do componente poli (ácido lático) e uma menor estabilidade do poli (butileno adipato co-tereftalato) na blenda polimérica, além disso, foi necessário uma temperatura constante de 550 ºC durante 50 minutos para degradar totalmente o polímero.Pela análise térmica diferencial (DSC) foi possível confirmar as interações propostas pelo FTIR e TGA, que indicam que a interação ocorre preferencialmente com as cadeias alifáticas do polímero ecovio®. Após a calcinação das fibras, para o preparo do sensor, o resíduo obtido foi caracterizado por FTIR e MEV e pode-se observar mudanças na caracteristica dos MWCNT’s puros com diminuição dos grupos carboxilicos para os MWCNT’s tratados termicamente e eletrofiados/calcinados, além da formação de lamelas para o MWCNT’s eletrofiados/calcinados. As medidas eletroquímicas usando a tecnica de voltametria cíclica, mostram que o sensor é promissor para determinação de metronidazol.
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Junior, Jose Mario Ferreira. "Síntese e caracterização elétrica de materiais com comportamento termistor à base de óxidos de manganês, de níquel e de cobalto." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-29032012-101954/.
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Materiais cerâmicos à base de óxidos de manganês, de níquel e de cobalto foram preparados por meio de mistura de óxidos seguida de homogeneização e sinterização controlada em 1250 °C. Os óxidos foram caracterizados por meio das técnicas de difração de raios X, fluorescência de raios X, termogravimetria e determinação de distribuição de tamanho de partículas por espalhamento laser. A caracterização dos corpos sinterizados foi feita por meio de análise por microscopia eletrônica de varredura, difração de raios X e fluorescência de raios X. O comportamento termistor foi estudado por meio de medidas de resistividade elétrica pela técnica dc de duas pontas de prova entre temperatura ambiente e 220 °C. Os principais resultados mostram ser possível a preparação de termistores em ampla faixa de resposta elétrica por meio da variação da composição relativa dos óxidos de manganês, de níquel e de cobalto.Ceramic tliermistors based on manganese, nickel and cobalt oxides were prepared by mixing these oxides followed by pressing and sintering at 1250 °C range. The oxides were characterized by X-ray diffraction, X-ray fluorescence, thermogravimetry and differential thermal analysis, and by the determination of particle size distribution by laser scattering. After sintering. X-ray diffraction. X-ray fluorescence and scanning electron microscopy analyses were carried out. The thermistor behavior was studied by two-probe dc electrical resistivity measurements in the room temperature-220 °C range. The main results show the possibility of designing thermistors with the required electrical response by suitable choice of the relative concentrations of the precursor oxides.
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Kondam, Sudhir Chander Reddy. "Deploying multiple sensor applications in a network." Kansas State University, 2010. http://hdl.handle.net/2097/6990.
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Master of ScienceDepartment of Computing and Information Sciences
Gurdip Singh
TinyOS is an open-source component based operating system designed for highly memory constrained wireless embedded sensor network. TinyOS includes interfaces and components for communication management, routing and data acquisition tools to be refined further for custom applications. This project aims at developing a system which detects overlapping paths for data collection in different applications in the network and utilizing that information for efficient data acquisition. This prevents a reconfiguring the entire network of wireless sensor nodes (called motes) for each new application request. The application for initial or first data acquisition request tries to build the tree architecture on motes in the network where each node in the tree knows its immediate parent and children. The application builds the tree routed at the base station for the initial request and each intermediate node sends data to its parent when the data request is made. Each base station can request Light, Temperature and Passive Infrared sensory data from all or a subset of motes present in the system. When a new base station comes and connects to the network through a mote/node in the tree, the system reconfigures only those parts of the tree built in the initial phase which do not overlap with the tree required for the new base station as the root, all the other overlapping parts of the tree are left unchanged. We present experimental result to illustrate the efficiency of the approach.
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Costa, Raelson Santos. "Desenvolvimento de sensor eletroquímico a base de grafite poliuretana modificado Zeólita Ag-A para análise de Cl- em etanol combustível." Universidade Federal do Maranhão, 2017. http://tedebc.ufma.br:8080/jspui/handle/tede/1554.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
This work presents the development of an electrochemical sensor obtained from the modification of the polyurethane graphite composite electrode with Ag-A zeolite, an aluminosilicate of LTA structure modified with Silver, and its application in the determination of chloride ions, Cl-, in samples of Fuel ethanol. The aluminosilicates were synthesized by the hydrothermal method and characterized by X-ray diffraction, scanning electron microscopy. The obtained materials were then used as modifiers in the proportion of 10% in GPU electrodes, in order to make a comparison between the electrodes without modification and modified with Na-A and Ag-A using the technique of voltammetry of Cyclic. The results showed that the incorporation of Ag into the pores of the material promotes an improvement in the electrical and analytical properties of the electrode. The analytical response of the sensor in the determination of the Clion showed that the GPU-Ag-A electrode responds selectively to the chloride in terms of the decrease in peak current compared to the GPU or GPU-Na-A electrodes. The best response was obtained with electrodes modified with 10% Ag-A. With this percentage composition, the experimental conditions, deposition potential, deposition time, ladder potential, frequency and pH were optimized for analysis by square wave voltammetry in an electrochemical cell containing 2.0 mL of ethanol, 8.0 mL of NaNO3 1.0 mol L-1 and a Clconcentration of 2.5 × 10-5 mol L-1. The Ag-A modified sensor was then evaluated for electroanalytical determination of Clions in fuel ethanol samples presenting linear response. Good results were obtained for the detection limit (3,21 x 10-6 mol L-1), quantification limit (1.07 x 10-5 mol L-1), recovery (87%) and linearity (0.998) . Cu+2 and SO4-2 ions, present in the analysis matrix, did not present significant interference in chloride determination.
Este trabalho apresenta o desenvolvimento de um sensor eletroquímico obtido a partir da modificação do eletrodo compósito de grafite poliuretana com zeólita Ag-A, um aluminosilicato de estrutura LTA modificado com Prata, e sua aplicação na determinação de íons cloreto, Cl-, em amostras de etanol combustível. Os aluminosilicatos foram sintetizados através do método hidrotérmico e caracterizados por difração de raios-X, microscopia eletrônica de varredura. Os materiais obtidos foram, então, utilizados como modificadores na proporção de 10% em eletrodos GPU, a fim de realizar-se uma comparação entre os eletrodos sem modificação e modificados com Na-A e Ag-A mediante a utilização da técnica de voltametria de cíclica. Os resultados mostraram que a incorporação do Ag aos poros do material promove uma melhora nas propriedades elétricas e analíticas do eletrodo. A resposta analítica do sensor na determinação do íon Cl-, mostrou que o eletrodo GPU-Ag-A responde de maneira seletiva ao cloreto, em termos de diminuição de corrente de pico, comparado aos eletrodos GPU ou GPU-Na-A. A melhor resposta foi obtida com eletrodos modificados com 10% de Ag-A. Com esta composição percentual, as condições experimentais, potencial de deposição, tempo de deposição, potencial de escada, frequência e pH, foram otimizadas para analise por voltametria de onda quadrada, em uma célula eletroquímica contendo 2,0mL de etanol, 8,0mL de NaNO3 1,0 mol L-1 e uma concentração de Clde 2,5×10-5 mol L-1. O sensor modificado com Ag-A foi então avaliado para determinação eletroanalítica de íons Clem amostras de etanol combustível apresentando resposta linear. Bons resultados foram obtidos para o limite de detecção (3,21×10-6 mol L-1), limite de quantificação (1,07×10-5 mol L-1 ), recuperação (87%) e linearidade (0,998). Íons Cu2+ e SO4-2, presentes na matriz de analise, não apresentaram interferência significativa na determinação do cloreto.
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Santhiago, Murilo 1984. "Construção e aplicação de dispositivos analíticos 2D e 3D à base de papel com detecção eletroquímica." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248388.
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Orientador: Lauro Tatsuo KubotaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Neste trabalho descreve-se a construção e aplicação de dispositivos analíticos 2D e 3D à base de papel com detecção eletroquímica (ePAD). Os dispositivos foram construídos empregando o método de impressão com cera e diferentes tipos de papéis. Eletrodos de ouro foram utilizados juntamente com o conceito da separação cromatográfica em dispositivos microfluídicos. No canal microfluídico à base de papel foi possível realizar a separação de ácido ascórbico e dopamina em 14 minutos. A necessidade por processos de fabricação mais simples e de baixo custo nos motivou a estudar eletrodos de carbono em ePADs. Assim, eletrodos de grafite de lapiseira foram selecionados visando o desenvolvimento de um biossensor para glicose. O biossensor apresentou uma excelente resposta eletroquímica e um tempo de análise de 4 minutos. O mesmo eletrodo de grafite foi acoplado com um sistema de informação para determinação de p-nitrofenol. Assim, foi possível detectar 1,0 mmol L de p-nitrofenol em amostras de água e analisar/interpretar os resultados empregando um celular. Por fim, a necessidade por sistemas eletroquímicos com menores limites de detecção nos impulsionou a fabricar microeletrodos de pasta de carbono. Os microeletrodos foram fabricados em folhas de transparência e acoplados no papel empregando uma configuração do tipo sanduíche. Os dispositivos foram caracterizados eletroquimicamente na presença de cisteína e apresentaram uma constante cinética de 10 L mol s. Um limite de detecção de 4,8 mmol L para cisteína foi obtido empregando um arranjo de microeletrodos. Por fim, os microeletrodos de pasta de carbono foram utilizados para a construção de um biossensor visando a determinação de metil paration. O ePAD foi construído de modo a acomodar o substrato (acetiltiocolina) e a enzima (acetilcolinesterase) no mesmo dispositivo
Abstract: This thesis describes the construction and application of 2D and 3D electrochemical paper-based analytical devices (ePADs). The devices were constructed using the wax printing method and different types of papers. Gold electrodes were employed along with the concept of chromatographic separation in microfluidic devices. By using the paper-based microfluidic channel it was possible to perform the separation of ascorbic acid and dopamine in 14 minutes. The need for simpler and low cost manufacturing processes motivated us to study carbon electrodes in ePADs. Thus, pencil graphite electrodes were selected for the development of a biosensor for glucose. The biosensor exhibited excellent electrochemical response and analysis time of 4 minutes. The same graphite electrode was coupled to an information system for the determination of p-nitrophenol. Thus, it was possible to detect 1.0 mmol L of p-nitrophenol in water samples and analyze/interpret the results using a smartphone. Finally, the need for electrochemical systems with lower limits of detection made us to search for carbon paste microelectrodes. The microelectrodes were fabricated on transparency sheets and coupled on paper using a sandwich-type configuration. The devices were characterized electrochemically in the presence of cysteine and had a rate constant of 10 L mol s. A detection limit of 4.8 mmol L for cysteine was obtained using an array of microelectrodes. By last, carbon paste microelectrodes were used to construct a biosensor in order to determine methyl parathion. The ePAD was constructed to accommodate the substrate (acetylthiocholine ) and enzyme ( acetylcholinesterase ) in the same device
Doutorado
Quimica Analitica
Doutor em Ciências
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Wenga, Gertrude. "Mise en œuvre d'un capteur chimique et biologique à base de nanofils de silicium." Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S170.
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L'objectif de ce travail de recherche est la réalisation de dispositifs à base de nanofils de silicium, réalisés par la méthode des espaceurs. La synthèse des nanofils est effectuée à partir d'une couche de silicium polycristallin, déposée par la technique LPCVD (Low Pressure Chemical Vapor Deposition). Ces nanofils sont ensuite intégrés dans les dispositifs électroniques tels que des résistances ou des transistors réalisés suivant deux configurations différentes « bottom-gate » et « step-gate ». Les caractéristiques électriques de ces deux types de transistors ont mis en évidence des propriétés électriques suffisantes pour leur utilisation en tant que capteurs. Une simulation permet d'expliquer l'effet de l'apport de charges électriques à la surface des nanofils sur la concentration d'électrons dans la couche active. Les dispositifs sont tout d'abord utilisés pour la mesure du pH, et montrent une sensibilité de détection supérieure à la sensibilité nernstienne. Pour une utilisation du dispositif en tant que biocapteur, une fonctionnalisation de la surface des nanofils est nécessaire pour permettre l'accrochage de sondes d'ADN. La détection électronique de l'hybridation sondes/cibles de brins d'ADN complémentaires est démontrée avec un faible seuil de détection. Enfin, afin d'augmenter la surface d'échange entre le nanofil et les espèces chargées, un procédé de fabrication de résistances à base de nanofils suspendus est développé. Des tests de détection en présence d'ammoniac ont mis en évidence une réponse linéaire sur une gamme de concentrations. Les résistances à base de nanofils suspendus présentent une plus grande sensibilité que celles à base de nanofils non suspendus, mettant en avant l'effet important de la surface des nanofils. Tous ces résultats permettent de démontrer la faisabilité de capteurs chimiques et biologiques à base de nanofils de silicium à partir des techniques conventionnelles de la microélectronique en utilisant un procédé de fabrication « bas-coût »The goal of this research work is the realization of devices based on silicon nanowires, realized using sidewall spacer formation technique. Nanowires are synthesized form a polycrystalline silicon layer deposited by LPCVD technique (Low Pressure Chemical Vapor Deposition). These nanowires are then integrated into electronic devices such as resistors and transistors made using two different configurations “bottom-gate” and “step-gate”. The electrical characteristics of these two types of transistors have shown adequate electrical properties for their use as sensors. A simulation is made, to explain how additional electrical charges on the surface of the nanowires, affect the electron concentration inside the active layer. The devices are firstly used for the pH measurement, and have shown sensitivity higher than the Nernstian sensitivity detection. For a use as biosensor, nanowires are functionnalized to allow the binding of DNA probes. Electronic detection of hybridization complementary probe/target DNA strands is demonstrated with a low detection limit. Finally, in order to increase the exchange surface between the nanowires and charged species, resistors based on suspended nanowires were developed. Different tests were performed in the presence of ammonia and showed a linear response over a range of concentrations. Resistors based on suspended nanowires highlighted greater sensitivity than those based on unsuspended nanowires, bringing out the important effect of the surface of the nanowires. All these results demonstrate the feasibility of chemical and biological sensors based on silicon nanowires compatible with conventional microelectronics techniques using a low-cost process
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Lima, Phabyanno Rodrigues. "Eletrodo modificado a base de 4-nitroftalonitrila : sensor amperometrico para quantificação de alguns antioxidantes de relevancia biologica." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248416.
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Orientadores: Lauro Tatsuo Kubota, Marilia Oliveira Fonseca GoulartTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Neste trabalho descreve-se o desenvolvimento de sensores amperométricos a base de um simples eletrodo de pasta de carbono modificado com um novo mediador redox, a 4-nitroftalonitrila (4-NO2FN), para a determinação de alguns antioxidantes de relevância biológica [L-cisteína (L-CySH), L-glutationa (L-GSH), ácido L-ascórbico (L-AscH2), ácido úrico (AU) e nicotinamida adenina dinucleotídeo (forma reduzida) (NADH)]. Com este propósito, inicialmente, a 4-NO2FN foi ativada in situ, gerando o par redox nitroso/hidroxilamina (4-NOFN/4- NHOHFN) estável na superfície eletródica, o qual apresentou atividade electrocatalítica na oxidação dos analitos estudados. As técnicas empregadas para a realização deste trabalho foram voltametria cíclica e cronoamperometria, as quais foram utilizadas para estudar o comportamento dos eletrodos modificados, para otimização dos parâmetros experimentais, obtenção dos parâmetros cinéticos e caracterização analítica dos sensores. Além disso, os estudos hidrodinâmicos e cronoamperométricos foram realizados com o objetivo de se obter maiores informações sobre os processos de oxidação entre L-AscH2, NADH e os eletrodos modificados. Assim, por meio dos gráficos e equações de Koutech- Levich e Cottrell foi possível obter os valores para o coeficiente de difusão (D) e constante de velocidade da reação (kobs) para L-AscH2 e NADH. Os valores do D e de kobs, determinados para L-AscH2 e NADH, foram de 9,0x10 cm s e 2,4x10 cms, 6,0x10 molL s e 1,0x10 molL s, respectivamente. O aumento na velocidade de reação, tanto para o L-AscH2 quanto para o NADH, foi atribuído à eficiente transferência de elétrons entre estas espécies e o par redox 4-NOFN/4-NHOHFN eletrogerado in situ. Sob condições otimizadas, o sensor amperométrico apresentou uma faixa de resposta linear (mmol L), limite de detecção (mmol L), quantificação (mmol L) e sensibilidade (nA L mmol) para L-CySH (a), L-GSH (b), L-AscH2 (c), AU (d) e NADH (e), os quais apresentaram os valores de (a) 0,8-13,2, 0,25, 0,8, 37,0; (b) 8,0-83,0, 2,7, 8,0, 54,0; (c)5,0-120,0, 1,6, 5,5, 108,0; (d) 5,0- 120,0, 1,3, 4,5, 121,6 e (e) 0,8-8,5, 0,25, 0,82, 500,0, respectivamente. Após a aplicação destes sensores em amostras de interesse, estudos de adição e recuperação dos analitos foram realizados para avaliar a exatidão dos métodos e verificou-se que foi possível uma percentagem de recuperação entre 98,5 e 102,0% para L-CySH, L-GSH, L-AscH2 e AU
Abstract: In this work, the development of amperometric sensors based on a simple carbon paste electrode modified with a new redox ¿mediator¿, 4- nitrophthalonitrile (4-NO2PH), for quantification of some antioxidants of biological relevance (L-cystein (L-CySH), L-glutathione (L-GSH), L-ascorbic acid (L-AscH2), uric acid (UA) and b-nicotinamide adenine dinucleotide (NADH)), is described. For this purpose, initially, 4-NO2PH was activated in situ, generating a stable redox-active nitroso/hydroxylamine system (4- NOPH/4-NHOHPH) on the electrodic surface, which presented electrocatalytic activity towards the oxidation of studied analytes. The techniques used in this work were cyclic voltammetry and cronoamperometry, to study the behavior of the modified electrodes, for the experimental parameters optimization, for the attainment of the kinetic parameters and analytical characterization of the sensors. Hydrodynamic and cronoamperometric studies were carried out with the aim to get information on the reduction processes and oxidation of L-AscH2 and NADH, respectively, on the modified electrodes. Through the Koutech-Levich and Cotrell plots it was possible to obtain the values for the diffusion coefficient (D) and kinetic constant of the reaction (kobs) for the analytes in study. The values of the diffusion coefficient and kobs, determined for L-AscH2 and NADH were 9,0x10 cm s and 2,4x10 cms, 6,0x10 molL s and 1,0x10 molL s, respectively. The increase of the reaction rate for L-AscH2 and NADH was attributed to the efficient electron transfer between the studied species and immobilized electroactive species on the surface of the carbon paste electrode. After optimizing conditions, the sensor provided a linear response range (mmol L), limit of detection (LOD) (mmol L), limit of quantification (LOQ) (mmol L) and sensitivity (nA L mmol) for L-CySH (a), L-GSH (b), L-AscH2 (c), UA (d) e NADH (e) of (a) 0.8-13.2, 0.25, 0.8, 37.0; (b) 8.0-83.0, 2.7, 8.0, 54.0; (c)5.0-120.0, 1.6, 5.5, 108.0; (d) 5.0-120.0, 1.3, 4.5, 121.6 and (e) 0.8- 8.5, 0.25, 0.82, 500.0, respectively. After the application of these sensors in samples of interest, studies of addition and recovery of the analytes were carried out to evaluate the error of the methods and it was verified recovery percentages between 98.5 and 102.0% for L-CySH, L-GSH, L-AscH2 and AU, were obtained
Doutorado
Quimica Analitica
Doutor em Ciências
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Grazon, Chloé. "Élaboration de nanoparticules fluorescentes à base de BODIPY par polymérisation RAFT en miniémulsion : synthèse, caractérisation et fonctionnalisation de surface." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2012. http://tel.archives-ouvertes.fr/tel-00841491.
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Les travaux de cette thèse présentent la synthèse par une polymérisation RAFT en miniémulsion de nanoparticules fluorescentes (NPFs) polymères à coeur BODIPY copolymérisé au styrène et à couronne hydrophile biocompatible et fonctionnalisable à base de poly(oxyde d'éthylène) et de poly(acide acrylique). Les propriétés de fluorescence de ces NPFs ont été étudiées par spectroscopie de fluorescence stationnaire et résolue en temps. L'élaboration de la synthèse de ce type de NPFs, et la mise au point d'un procédé "one-pot" sont présentés dans un premier temps. Ensuite, les propriétés spectroscopiques de ces NPFs sont étudiées, notamment l'influence de la concentration en monomères de BODIPY au coeur des NPFs pouvant mener à la formation d'agrégats peu ou pas fluorescents. Les propriétés spectroscopiques (longueur d'onde d'émission de fluorescence et rendement quantique) du coeur des NPFs ont été modulées. Cela est rendu possible en réalisant la synthèse de monomères de BODIPY portant des groupements aromatiques encombrés, ou présentant différentes fonctions polymérisables. La couronne hydrophile des NPFs a également été modifiée afin d'obtenir différentes répartitions des unités acide acrylique et oxyde d'éthylène dans les chaînes de copolymères en surface. Ces nouvelles NPFs sont également synthétisées par un procédé "one-pot". Enfin, des molécules à fonctions amine (fluorophores, protéines) ont été introduites dans la couronne hydrophile de ces diverses NPFs par une chimie de couplage peptidique sur les fonctions acides carboxyliques. Des nano-senseurs de pH ratiométriques ont ainsi pu être élaborés.
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Feldens, Guilherme de Oliveira. "O senso de justiça como base para a tomada de decisões judiciais." Universidade do Vale do Rio dos Sinos, 2014. http://www.repositorio.jesuita.org.br/handle/UNISINOS/4060.
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O senso de justiça é um dos elementos essenciais para a criação de uma comunidade justa e democrática nos moldes apresentados em A theory of justice. A virada política de Rawls, centrada na análise da estabilidade social e da legitimidade do poder diante a pluralidade de concepções morais presentes nas sociedades atuais, não eliminou totalmente a importância do senso de justiça na justificação pública proposta em Political liberalism. Nesse sentido, afirma-se que a moralidade em Rawls tem uma função social, pois visa defender o indivíduo frente à sociedade sem ter a coerção externa como principal fonte de motivação para cumprir seus preceitos. A partir desse quadro, o presente trabalho objetiva demonstrar que Rawls apresenta uma concepção de Direito embasada em princípios de justiça expressos no acordo Constitucional. Rawls garante um modelo de sistema jurídico afastado do positivismo jurídico e do utilitarismo, capaz de garantir um sentido democrático diferente, afastado da mera tentativa de legitimação da autoridade política através de um discurso normativo. Por fim, conclui-se que tal modelo garante uma atividade jurisdicional caracterizada pela responsabilidade de manter os princípios de justiça aceitos por todos os cidadãos no acordo constitucional. Dessa forma, as decisões relativas às questões sociais essenciais não serão influenciadas por interesses de maiorias transitórias, nem pelas concepções morais individuais dos julgadores, respeitando a coerência de um sistema de justiça construído a partir de juízos democráticos.
The sense of justice is one of the essential elements for the creation of a fair and democratic community as presented in A theory of justice. Rawls's political shift, focusing on the analysis of social stability and legitimacy of power before the plural moral concepts present in current societies, has not totally eliminated the relevance of the sense of justice in the public justification proposed in Political liberalism. In this sense, it is said that morality in Rawls has a social function, once it aims at defending the individual before society without external coercion as a main source of motivation to fulfill its precepts. Based on this picture, the purpose of this study is to show that Rawls presents a concept of Law based on principles of justice expressed in the constitutional settlement. Rawls establishes a model for the legal system distant from legal positivism and utilitarianism, one that is capable of assuring a different democratic sense, distant from the mere attempt to legitimize political authority through a normative discourse. Finally, it is concluded that such model assures a jurisdictional activity characterized by the responsibility to make all citizens in the constitutional settlement accept the justice criteria. Thus, decisions regarding essential social issues shall not be influenced by interests of the transient majorities, nor by the individual moral conceptions of the judges, this way respecting the coherence of a legal system built on democratic judgments.
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Kolsmyr, Johan, and Andreas Löfberg. "Software enhancement for improving sampling frequency and BLE communication in an embedded system." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-30928.
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Shimizu, Kenichi, Satoshi Sugaya, Shiro Kakimoto, Makoto Katagiri, and Atsushi Satsuma. "Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides." MDPI, 2011. http://hdl.handle.net/2237/20674.
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Tompkins, Nicholas William. "Design of a Machine Condition Monitoring System with Bluetooth Low Energy." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984239/.
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Valleron, Arthur. "Etude et optimisation de capteurs de gaz a base de dioxyde d’etain en conditions d’une ligne d’echappement automobile." Thesis, Saint-Etienne, EMSE, 2011. http://www.theses.fr/2011EMSE0613/document.
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Cette étude est dédiée à l’optimisation de capteurs chimiques de gaz de type résistifs à base de dioxyde d’étain (SnO2) pour l’application en ligne d’échappement automobile. Les capteurs sont élaborés par la technique de sérigraphie qui permet la production en masse de capteurs robustes sur substrat alumine. En vue de l’application automobile visée, les capteurs ont été optimisés par l’ajout d’une couche protectrice poreuse déposée sur l’élément sensible de SnO2. Le comportement de ces capteurs a été étudié en fonction de différents paramètres, comme la température et la vitesse des gaz, représentatifs de conditions d’échappement automobile. De plus, une modélisation « simple » de la réponse électrique des capteurs en fonction de la concentration d’un ou plusieurs gaz polluants cibles a été proposéeThis study is dedicated to the optimization of chemical gas sensors based on resistive type tin dioxide (SnO2) for automotive exhaust application. The sensors were produced by screen-printing technique which allows mass production of robust sensors on alumina substrate. In regards of the automotive application, the sensors were optimized by adding a porous protective layer deposited on the sensing element SnO2. The behaviour of this type of gas sensors was studied depending on gas parameters such as gas temperature and velocity, representative of real operation conditions. In addition, a “simple” modelisation of the electrical response of sensors depending on the concentration of one or more gaseous targets is proposed
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Ramos, Jessica Viviana Hinostroza. "Material híbrido bioinorgânico à base de sílica e quitosana aplicado no desenvolvimento de sensor eletroquímico para determinação de paracetamol na presença de dopamina." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/72046.
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Neste trabalho foram obtidas quatro amostras de um híbrido bioinorgânico de sílica-quitosana (SiO2/QT) usando-se TEOS como precursor e variando a concentração da QT, de 0,5 a 4,0% (m/m). Os materiais obtidos foram devidamente caracterizados e os resultados mostraram que são mesoporosos com diâmetro de poro na faixa de 6,2 a 7,3 nm. Os materiais apresentam estabilidade térmica e foi possível impregnar maior teor de QT no híbrido com o incremento de sua concentração na preparação. Na superfície do material híbrido foi imobilizada a ftalocianina de cobre (II) tetrassulfonada e foi utilizada como matriz para a construção de eletrodo de pasta de carbono. Este eletrodo foi avaliado mediante técnicas de voltametria cíclica e de voltametria de pulso diferencial, como um novo sensor eletroquímico de paracetamol na presença da dopamina como interferente, visto que está espécie pode causar interferências durante a detecção de paracetamol em meios biológicos. O material se mostrou altamente sensível (173 μA.L mmol-1) e seletivo para a determinação de paracetamol, permitindo uma boa separação e definição de picos de oxidação do paracetamol (0,30 V) e da dopamina (0,11V). O eletrodo contendo 1,0% de QT mostrou melhores resultados. Também foram obtidas amostras de um material carbono cerâmico SiO2/QT/C-grafite variando-se a concentração de grafite de 50% a 60% (m/m). Os resultados mostraram que são materiais mesoporosos, apresentam propriedades texturais semelhantes, com 6,6 nm de diâmetro de poro, e são estáveis termicamente. Um estudo do comportamento eletroquímico do ferricianeto e ferrocianeto de potássio utilizando esses materiais são apresentados. Na superfície dos materiais compósitos foi imobilizado o ácido ferroceno carboxílico. Medidas de voltametria cíclica mostraram que o eletrodo construído com este material na presença de paracetamol mostrou picos de oxidação pouco definido em 0,35 V e atribuído à oxidação do paracetamol.In this work, a silica based bioinorganic hybrid containing chitosan (SiO2/QT) was prepared using TEOS as precursor and varying the concentration of chitosan, from 0,5% to 4,0% (w/w). The obtained materials were properly characterized, the results showed that are mesoporous with pore size between 6,2 to 7,3 nm. The materials present adequate thermal stability and higher amount of chitosan was possible to impregnate on hybrid with the increase of its concentration on synthesis. Copper (II) tetrasulfonated phtalocyanine was immobilized on surface of hybrid and used as matrix for the construction of carbon paste electrode. By cyclic voltammetry and differential pulse it was assessed as a new electrochemical sensor of acetaminophen, being highly sensitive (173 μA.L mmol-1) and selective for determination of acetaminophen in the presence of dopamine as interference, because this species can cause interference during the detection of acetaminophen in biological means. The results showed a good separation and definition of oxidation peaks of acetaminophen (0.30 V) and dopamine (0.11 V). The electrode containing 1,0% chitosan showed the best results. It was also prepared a bioinorganic hybrid carbon ceramic SiO2/QT/C-graphite material varying the concentration of graphite, from 50 to 60% (m/m). The results showed that they are mesoporous materials and present similar textural properties, with 6.6 nm pore size and are thermally stable. A study of the electrochemical behavior of potassium ferricyanide and ferrocyanide using these materials are presented. On the surface of the composites materials was immobilized ferrocene carboxylic acid. Measurements by cyclic voltammetry showed that the electrode development with this material for acetaminophen showed oxidation peaks no definite at 0.35 V and attributed to the oxidation of paracetamol.
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Ribeiro, Izabela Aparecida Luiz. "Oxida??o eletrocatal?tica de NADH empregando um novo sensor ? base de um complexo macroc?clico n4 sobre grafeno e DNA." UFVJM, 2015. http://acervo.ufvjm.edu.br/jspui/handle/1/816.
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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (Capes)
?-Nicotinamida adenina dinucleot?deo (NADH) e sua forma oxidada correspondente (NAD+) representam uma coenzima de grande import?ncia em centenas de rea??es naturais catalisadas por enzimas desidrogenase, sendo vitais no metabolismo respirat?rio mitocondrial por estimular a produ??o de energia e atuam como principais transportadoras de cargas centrais em c?lulas vivas. Por estes motivos, a determina??o eletroqu?mica de NADH tem atra?do consider?vel aten??o no desenvolvimento de sensores. Neste trabalho foi desenvolvido um sensor para a determina??o voltam?trica de NADH de forma sens?vel e seletiva. O m?todo baseia-se num eletrodo de carbono v?treo modificado com ftalocianina tetrassulfonada de n?quel (NiTsPc - complexo macroc?clico N4), grafeno e DNA, designado por ECV/Grafeno/DNA/NiTsPc. A espectroscopia de infravermelho por transformada de fourier foi utilizada para caracterizar os materiais que comp?em a modifica??o. O processo de oxida??o do NADH foi investigado por voltametria c?clica (VC), cronoamperometria e voltametria de pulso diferencial (VPD). O sensor Grafeno/DNA/NiTsPc apresentou uma excelente atividade catal?tica para a oxida??o de NADH em baixo potencial. Par?metros experimentais que influenciam a resposta anal?tica do sensor foram investigados. As condi??es ?timas, para a eletrocat?lise da oxida??o de NADH sobre o ECV/Grafeno/DNA/NiTsPc, foram encontradas para o eletrodo modificado com 0,5 mg mL-1 de grafeno e 1 mmol L-1 de NiTsPc, com a concentra??o de DNA pr? estabelecida em 2 mg mL-1, utilizando-se o tamp?o fosfato 0,1 mol L-1 (pH 7,0) como eletr?lito suporte. O estudo da cin?tica da rea??o de oxida??o de NADH sobre o ECV/Grafeno/DNA/NiTsPc permitiu concluir que a rea??o promovida ? de ordem estequiom?trica 1, envolve 2 el?trons e ocorre de forma r?pida uma vez que o Kobs obtido foi 7,35 x 105 mol-1 L s-1. As correntes de pico voltam?tricas apresentaram uma resposta linear para a concentra??o de NADH no intervalo de 1 a 200 ?mol L-1 para n = 9 (R = 0,998), com sensibilidade, limite de detec??o e limite de quantifica??o iguais a 0,010 ?A L mol-1, 0,3 ?mol L-1 e 1 ?mol L-1, respectivamente. Estudos de adi??o e recupera??o do analito foram realizados para avaliar a exatid?o do m?todo e verificou-se que foi poss?vel uma porcentagem de recupera??o entre 99,8 e 101,0% para o NADH. A repetibilidade de medidas e a reprodutibilidade do preparo do sensor foram avaliadas pelo desvio padr?o relativo de 10 determina??es de NADH a 50 ?mol L-1, obtendo-se DPR?s (Desvios Padr?es Relativos) iguais a 2,33 e 3,13 %, respectivamente. A interfer?ncia de esp?cies que podem coexistir com o NADH em fluidos biol?gicos foi avaliada e concluiu-se que o sensor foi seletivo para o analito. Contudo, o sensor desenvolvido de forma simples, por?m efetiva, pode ser aplicado para a determina??o de NADH.
Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2015.
ABSTRACT ?-nicotinamide adenine dinucleotide (NADH) and its corresponding oxidized form (NAD+) represent a coenzyme of great importance in hundreds of natural reactions catalyzed by dehydrogenase enzymes, being vital in mitochondrial respiratory metabolism by stimulating the production of energy and act as the main carriers central loads in living cells. For these reasons, the electrochemical determination of NADH has attracted considerable attention in the development of sensors. In this work was developed a sensor for the voltammetric determination of NADH sensitively and selectively. The method is based on a glassy carbon electrode modified with tetrasulfonated nickel phthalocyanine (NiTsPc - N4 macrocyclic complex), graphene and DNA, designate ECV/Graphene/DNA/NiTsPc. Fourier transform infrared spectroscopy was used to characterize the materials composing the modification. The NADH oxidation process was investigated by cyclic voltammetry (CV), chronoamperometry and differential pulse voltammetry (DPV). The sensor Graphene/DNA/NiTsPc showed an excellent catalytic activity for NADH oxidation in low potential. Experimental parameters which influence the analytical response of the sensor were investigated. The optimum conditions for the NADH oxidation electrocatalytic on ECV/Graphene/DNA/NiTsPc were found to the modified electrode with 0,5 mg mL-1 of graphene and 1 mmol L-1 NiTsPc, with the concentration of DNA predetermined at 2 mg mL-1 using the phosphate buffer 0.1 mol L-1 (pH 7.0) as supporting electrolyte. The study of the kinetics of the reaction of NADH oxidation on the ECV /Grafeno/DNA/NiTsPc allowed us to conclude that the reaction promoted is of stoichiometric order 1, involves 2 electrons and occurs quickly once the Kobs obtained was 7.35 x 105 mol-1 L s-1. The voltammetric peak currents showed a linear response for NADH concentration in the range from 1 up 200 mmol L-1 for n = 9 (R = 0.998), with a sensitivity, detection limit and quantification limit of 0.010 ?A L mol-1, 0.3 ?mol L-1 and 1 ?mol L-1, respectively. Studies of addition and recovery of the analyte were carried out to evaluate the accuracy of the method and was verified a recovery percentage between 99,8 and 101,0% for NADH. The repeatability of the measurements and the reproducibility of the preparation of the sensor were evaluated by means of the Relative Standard Deviation (RSD) for 10 measurements of NADH 50 ?mol L-1, obtaining RSD (Relative Standards Deviations) equal to 2.33 and 3.13%, respectively. The interference of species that can coexist with the NADH in biological fluids was evaluated and it was concluded that the sensor was selective for the analyte. However, the sensor developed in a simple, but effective, can be applied to the determination of NADH.
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Morawski, Franciele de Matos. "Materiais mesoporosos a base de sílica titânia e sua aplicação como sensores e biossensores eletroquímicos para a determinação de compostos fenólicos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/179626.
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No presente trabalho foram desenvolvidos materiais mesoporosos de sílica/titânia visando sua aplicação como sensores e biossensores eletroquímicos para compostos fenólicos de interesse ambiental e medicinal. Os materiais obtidos foram caracterizados por diferentes técnicas buscando avaliar suas propriedades texturais, morfológicas e estruturais. O comportamento eletroquímico foi investigado por voltametria cíclica (VC) que permitiu determinar a proporção ideal de sílica/titânia do suporte sintetizado. Após a otimização do suporte, buscou-se desenvolver materiais estruturados com partículas magnéticas e tirosinase (SiTiMPs-Ty) e, nanopartículas de ouro previamente estabilizadas com quitosana (SiTi30-Au). Os materiais modificados foram aplicados no desenvolvimento de eletrodos de pasta de carbono (EPCs) para determinação de compostos fenólicos, após a otimização de parâmetros como efeito de pH e atmosfera e, empregados na análise simultânea de diferentes compostos através das técnicas de voltametria de pulso diferencial (VPD) e voltametria de onda quadrada (VOQ) Também foi avaliada a resposta do eletrodo na presença de potenciais interferentes, bem como sua a reprodutibilidade. O EPC modificado com SiTi30-Au apresentou resposta linear para a determinação simultânea de dopamina e norepinefrina na faixa de 50 a 400 mol L-1 e os limites de detecção foram determinados como 0,35 mol L-1 e 0,57 mol L-1 para norepinefrina e dopamina, respectivamente. O EPC modificado com material SiTiMPs-Ty também apresentou resposta linear para análise simultânea de catecol e epinefrina na faixa de 40 a 380 μmol.L-1 e os limites de detecção foram de 3,32 μmol L-1 e 1,65 μmol L-1 para catecol e epinefrina, respectivamente. A reprodutibilidade dos eletrodos apresentou desvio padrão relativo de 5,86% para o EPC SiTi30-Au e 6,87% para o EPC SiTiMPs-Ty. Os EPCs de sílica/titânia modificados no presente trabalho apresentaram potencialidade de aplicação na determinação simultânea de compostos fenólicos com altas sensibilidades, baixos limites de detecção e boa reprodutibilidade.In this work silica/titania materials were synthetized by sol-gel method by using different ratios of inorganic precursors and the obtained materials were applied as electrochemical sensors and biosensors. The materials were characterized using different techniques aiming to evaluate the textural, morphological and structural properties. The electrochemical behavior of the silica/titania materials was evaluated by Cyclic Voltammetry that allows estimating the optimum amount of titania in the resultant material. The electrochemical behavior guided the choice for developing modified materials containing magnetite particles (SiTiMPs-Ty) and gold nanoparticles (SiTi30- Au). After to achieve the best electrochemical conditions of pH and the best atmosphere, the resultant materials were applied in the development of modified carbon paste electrodes (CPE). The SiTi30-Au CPE and SiTiMPs-Ty CPE were applied in simultaneous electrochemical analysis of phenolic compounds by using differential pulse voltammetry (DPV) and square wave voltammetry (SWV). It was also evaluated the electrochemical response of these modified CPEs in interferences analysis The modified CPE/SiTi30-Au showed a linear response between peak current intensity and concentrations of dopamine and norepinephrine in a range from 50 to 400 mol L-1 and its linear response was also observed in simultaneous analysis of these compounds. The limits of detection were estimated as 0.35 mol L-1 and 0.57 mol L-1 for norepinephrine and dopamine, respectively. The modified SiTiMPs-Ty/CPE was used for simultaneous electrochemical determination of catechol and epinephrine presenting a linear response in a range from 40 to 380 μmol.L-1 and the limits of detection were 3.32 μmol L-1 for catechol and 1.65 μmol L-1 for epinephrine. Both electrodes presented a good reproducibility with relative standard deviations of 5.86% and 6.87% for SiTiMPs-Ty/CPE and SiTi30-Au/CPE, respectively. Therefore, the modified silica/titania CPEs obtained in this work showed a good electrochemical response in electrochemical simultaneous determination of phenolic compounds presenting low limits of detection and great sensitivities in the presence of the studied analytes.
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Gottumukkala, Venkata Praneeth Varma. "Providing Location Privacy to Base Station in Wireless Sensor Networks." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353100851.
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Rumar, Tove, and Larsen Ludvig Juelsson. "Towards an improvement of BLE Direction Finding accuracyusing Dead Reckoning with inertial sensors." Thesis, Malmö universitet, Fakulteten för teknik och samhälle (TS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-44776.
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Whilst GPS positioning has been a well used technology for many years in outdoor environments,a ubiquitous solution for indoor positioning is yet to be found, as GPS positioning is unreliableindoors. This thesis focuses on the combination of Inertial Sensor Dead Reckoning and positionsobtained from the Bluetooth Low Energy (BLE) Direction Finding technique. The main objectiveis to reduce the error rate and size of a BLE Direction Finding system. The positioned object is aMicro-Electrical Mechanical System (MEMS) with an accelerometer and a gyroscope, placed on atrolley. The accelerometer and gyroscope are used to obtain an orientation, velocity vector, andin turn a position which is combined with the BLE Direction Finding position. To further reducethe error rate of the system, a Stationary Detection functionality is implemented. Because of thetrolley movement pattern causing noise in the sensor signals, and the limited sensor setup, it is notpossible to increase the accuracy of the system using the proposed method. However, the StationaryDetection is able to correctly determine a stationary state and thus decreasing error rate and powerconsumption.GPS är en väl använd teknologi sedan många år, men på grund av dess bristande precision vid inomhuspositionering, behöver en ny teknologi för detta område hittas. Denna studie är fokuserad på Dead Reckoning som ett stöd till ett Bluetooth Direction Finding positioneringssystem. Det främsta målet är att minska felfrekvensen och felstorleken i BLE Direction Finding systemet. Föremålet som positioneras är en Micro-Electrical Mechanical System (MEMS) med en accelerometer och ett gyroskop, placerad på en vagn. Accelerometern och gyroskopet används för att erhålla en orientering, hastighetsvektor och därefter en position som kombineras med den position som ges av BLE Direction Finding. För att minska felfrekvensen ytterligare hos systemet, implementeras en funktionalitet som detekterar om MEMS-enheten är stillastående, kallad Stationary Detection. På grund av vagnens rörelsemönster, som bidrar till brus hos sensorsignalerna, samt den begränsade sensorkonfigurationen, är det inte möjligt att förbättra systemets precision med den föreslagna metoden. Dock kan Stationary Detection korrekt fastställa ett stationärt tillstånd och därmed minska felfrekvensen och energiförbrukningen för enheten.
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Pardieu, Elodie. "Conception et développement d'un capteur électrochimique à base de polymères conducteurs à mémoire de forme pour la détection de petites molécules : application au cas de l'atrazine." Thesis, Paris, CNAM, 2010. http://www.theses.fr/2010CNAM0738.
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Les besoins d’outils d’analyse et de contrôle de plus en plus performants en termes de spécificité et sensibilité favorisent le développement des capteurs chimiques et des biocapteurs. Ce travail, s’inscrivant dans ce contexte, a conduit au développement d’un capteur électrochimique à base de polymères conducteurs dédiés à la détection de molécules de faible poids moléculaire. Celui-ci repose sur l’association entre les propriétés de reconnaissance des polymères à empreintes moléculaires et celles de conduction des polymères conducteurs obtenant ainsi un capteur à base de polymères conjugués à mémoires de forme le SMP. Le polymère est obtenu en deux étapes i) une électropolymérisation sur une électrode de platine de l’EDOT avec le pré-complexé formé par l’acide thiophène-3-acétique avec atrazine via des liaisons hydrogène ii) l’extraction de l’atrazine créant des sites à mémoire de forme. Le SMP développé présente une gamme de concentration de 2,5.10-6 M à 5.10-3 M avec un seuil de détection de l’ordre du µM et une sélectivité vis-à-vis de la famille des triazines. Afin d’améliorer les performances de ce capteur et d’élargir le choix de cibles à détecter la synthèse de terthyènyle constitués de l’EDOT de part et d’autre d’un thiophène central fonctionnalisé en β a été réalisé. Ces trimères présentant des pics d’oxydation vers les 0,7 V / Ag/AgNO3 permettent d’envisager le développement de nouvelles fonctionnalités avant ou post-polymérisation tout en ayant un contrôle de la stœchiométrie et de la répartition des groupements fonctionnelsA rapidly increasing interest is actually devoted in the literature to the design of new analytical and control devices able to form efficient chemical sensors. Thus the aim of our work was the design and the development of an electrochemical sensor based on intrinsically molecularly imprinted conducting polymer for the selective and sensitive detection of small target molecules. This goal will be achieved by the used of the recognition properties of moleculary imprinted polymer, together with the electrical conduction of conducting polymer. An original electrochemical sensor based on shape memory polymer has been constructed. This sensor has been realized following two steps: (i) a frst electropolymerisation on a platinum electrode of two co-monomers Thiophene acetic acid TAA already associated through H bonding to the atrazine target and EDOT which is intinded to play the role of conjugated link between the TAA moieties and (ii) removal of atrazine from the resulting conjugated polymer, leaving recognition sites with shape memory. The obtained sensor shows remarkable properties: a high selectivity towards the triazinic family, a large detection dynamic (2.5x10−6 to 5x10−3 M) and a low detection threshold (10−6 M). In order to increase the efficiency of this sensor and to allow the detection of a wide range molecular targets, a terthienyl, i.e. two EDOT units on both sides of the -functionalized thiophene units has been syntesized. These trimers possess an oxydation peak at about +0.7 V/ Ag/AgNO3, allowing the potential development of new pre or post polymerisation functionalities, still controling of the stoechiometry and the distributuion of functional groups
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Kovaleski, Joao Luiz. "Etude, modélisation et réalisation de capteurs d'accélération et force à base de polymère piézoélectrique PVF2." Grenoble 1, 1992. http://www.theses.fr/1992GRE10122.
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Le pvf2 s'avere bien adapte chaque fois que l'une ou moins de ses proprietes intrinseques est exploitee. En vue de la realisation de capteurs accelerometriques, nous avons etudie les proprietes du pvf2 et nous avons analyse le comportement d'une lame de pvf2 soumise a une contrainte de compression. Nous avons developpe des modeles electriques du pvf2 qui nous permettent d'effectuer des simulations a l'aide du logiciel spice. Ces modeles nous ont permis de definir les caracteristiques theoriques de nos capteurs que nous avons pu correler avec les resultats experimentaux. A la suite de ces etudes theoriques nous avons realise des capteurs accelerometriques. Parmi ceux-ci nous retiendrons l'accelerometre sismique et le capteur d'activite. Ces deux capteurs sont interessants car ils presentent des caracteristiques extremes, tant sur le plan metrologique que sur le plan dimensionnel. Enfin, nous avons aussi a partir des etudes faites sur les caracteristiques des accelerometres a masses inertielles developpe un capteur gyrometrique susceptible de delivrer des signaux proportionnels aux grandeurs liees a un mouvement de rotation. En nous basant sur les travaux de modelisation, nous avons explore le domaine des basses frequences. A partir d'un algorithme de lecture de charge pour aborder le domaine des mesures de forces statiques, nous avons developpe une implementation capable de restituer une image de la force statique appliquee
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Nappini, Omar <1997>. "Il modello integrato DEA-BSC a due stadi per la valutazione delle performance dei musei: il caso della Fondazione Musei Senesi." Master's Degree Thesis, Università Ca' Foscari Venezia, 2021. http://hdl.handle.net/10579/20449.
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La valutazione della performance nel settore culturale ha acquisito notevole importanza negli ultimi decenni a seguito della diffusa concezione del museo come un’azienda e l’introduzione di pratiche manageriali in questo settore. Il presente lavoro si prefigge di analizzare e applicare il modello integrato DEA-BSC a due stadi per misurare l’efficienza di un gruppo di musei. Inizialmente le metodologie Balanced Scorecard (BSC) e Data Envelopment Anlysis (DEA) vengono analizzate separatamente e approfondite nella loro applicazione alle istituzioni museali, successivamente è riportata la letteratura sui possibili approcci di integrazione delle due metodologie. La metodologia della Balanced Scorecard permette di individuare i fattori critici di successo delle organizzazioni museali, che sono poi tradotti in variabili di input e output nei modelli DEA. La prima fase prevede il calcolo di un punteggio di efficienza per ogni singola prospettiva BSC. La seconda fase, invece, utilizza un ulteriore modello DEA in cui le variabili di output sono i punteggi di efficienza calcolati nella fase precedente. Al fine di verificare la fattibilità e la validità del modello, quest’ultimo è impiegato per calcolare l’efficienza di alcuni musei della rete Fondazione Musei Senesi.
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Neander, Jonas. "Using Existing Infrastructure as Support for Wireless Sensor Networks." Licentiate thesis, Mälardalen University, Department of Computer Science and Electronics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-144.
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Denna avhandling handlar om hur befintliga datorinfrastrukturer i t.ex. sjukhus och industrier kan avlasta sensornätverk med energikrävande uppgifter. Vi har forskat på olika aspekter som gör det möjligt att förlänga livslängden på dessa sensornätverk. Avhandlingen presenterar en ny plattform för sensornätverk tillsammans med inledande simuleringar som påvisar att vår plattform ökar livslängden på dessa typer av nätverk.
Generella sensornätverk är uppbyggda av tätt grupperade, trådlösa, batteridrivna datorer som kan vara så små som en kubikmillimeter. Datorerna kallas för sensorer eller sensornoder eftersom de har en eller flera inbyggda sensorer som känner av sin omgivning. En sensor har till uppgift att samla information från sin omgivning, t.ex. temperatur, fuktighet, vibrationer, hjärtslag eller bilder. Sensorerna skickar sedan informationen till en insamlingsstation någonstans i nätverket.
I de typer av tillämpningar vi tittar på är det viktigt att minimera energiförbrukningen, så att man maximerar livslängden på sensornätverket. Avhandlingen presenterar en lösning där befintlig datorinfrastruktur fungerar som hjälpdatorer/avlastare till ett sensornätverk. Hjälpdatorerna, eller basstationerna som vi kallar dem i avhandlingen, hanterar energikrävande uppgifter som t.ex. vilken sensor som ska kommunicera med vem samt vid vilken tidpunkt etc. Då kan sensorerna i nätverket fokusera på att utföra sina egna uppgifter tills dess att basstationen säger att uppgifterna ändrats.
Simuleringar visar att vår plattform kan skicka upp till 97 % mera information till basstationen än en jämförbar plattform med samma energimängd. 88 % av våra sensorer är fortfarande vid liv när den andra plattformens sensorer förbrukat all sin energi.
Ett exempel på hur dessa typer av nätverk kan användas är att övervaka patienters hälsa och kondition i sjukhus eller sjukhem. Patienter behöver inte ha en fast sängplats där en viss typ av medicinskt övervakningsinstrument finns tillgänglig utan kan placeras där det finns en ledig sängplats. Via trådlös kommunikation skickar sensorerna sedan hälsoinformation som t.ex. hjärtfrekvens och blodtryck till en basstation som i sin tur skickar vidare till ett centralt övervakningsinstrument någonstans på sjukhuset. Övervakningsinstrumentet behandlar informationen och larmar personal med rätt kompetens vid behov. Larmet kan skickas till en mobiltelefon eller en liten handdator som personalen alltid bär med sig. Med larmet skickas även information om var patienten befinner sig och all nödvändig data för att personalen snabbt ska kunna ställa en första diagnos. På detta sätt kan man spara in på antalet specialbyggda sängplatser och slippa dyrbara installationer av medicintekniska utrustningar knutna till en sängplats.
Recent advancements in electronic design, such as low-power circuits, energy efficient wireless communication, and improved energy supply, has enabled the vision of wireless sensor networks to become a reality. Wireless sensor networks typically consist of hundreds up to thousands of collaborating low-cost, battery-driven and wireless sensor nodes with scarce resources. The wireless sensor nodes are typical small physical entities, and usually small as a matchbox but can in extreme cases be no larger than a cubic millimeter.
In this thesis we present an architecture called AROS that uses existing infrastructure to aid in the management of wireless sensor networks. As an example, the existing infrastructure could be situated in hospitals or industrial buildings. The existing infrastructure can aid in prolonging the lifetime of the wireless sensor network by having "unlimited'' energy, long range radio capacity, and high-speed computers. We enable prolonged lifetime by centralizing some of the energy consuming administrative functionality of wireless sensor networks.
We show, by simulations, that the AROS architecture is able to prolong the lifetime of the sensor nodes. AROS is compared to a well known cluster based architecture, LEACH. The comparisons show that AROS with static configuration performs at least as well as LEACH in small wireless sensor networks in the size 100x100m, and up to 97 % better in long distance wireless sensor networks in the size of 400x400m. We show that AROS still has got 88 % of its sensor nodes alive when LEACHs' network demises.
In our simulations we have also studied how dynamic network clustering in AROS, using a TDMA scheduler and non-mobile wireless sensor nodes, affects the amount of data received by a base station. We show that AROS is better than LEACH-C in collecting data to the base station with the same total amount of energy for long distance networks and that AROS performs as well or better than LEACH-C in small wireless sensor networks.
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TOSCHI, FRANCESCO. "Preparazione di materiali nanocompositi a base carbonio per applicazioni tecnologiche." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/983.
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La sintesi e le applicazioni dei materiali nanocompositi sono di importanza strategica nel campo della scienza dei materiali. In questo lavoro di tesi sono stati sviluppati diverse tipologie di materiali nanocampositi: Resina epossidica/nanotubi di carbonio (CNT), Poli(3,4-etilendiossitiofene) polistirensulfonato (PEDOT:PSS)/CNT, metallo/CNT. Questi materiali sono stati caratterizzati con le seguenti tecniche: Microscopia elettronica a scansione (SEM), Microscopia a forza atomica (AFM), microscopia acustica a forza atomica (AFAM), spettroscopia Raman e tecniche elettroanalitiche. La caratterizzazione funzionale è stata condotta testando i materiali in differenti applicazioni: Sensori resistivi, sensori di tipo nano-bilancia al quarzo e gestione del calore. I risultati sperimentali sono riportati nel lavoro di tesi.The synthesis and applications of nanocomposites are an important and strategical field of nanomaterial science. In this work has been developed several kind of nanocomposit materials, in particular: Epoxy resins and carbon nanotubes (CNT), Poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) and CNT, metal and CNT. This material has been characterized by means of: scanning electron microscopy (SEM), Atomic force miscroscpy (AFM), acoustic atomic force microscopy (AFAM), Raman spectroscopy and Electroanalitical techniques. The developed nanocomposite material has been tested by means different kind of application: Resistive sensors, quartz nano-balance and thermal management. The results are reported in the thesis work.
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Boughaleb, Jihane. "Développement et intégration d'un récupérateur d’énergie thermique à base de bilames thermiques et de matériaux piézoélectriques." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI114/document.
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Le développement des systèmes de récupération d'énergie est liée à l'émergence des applications de type Internet des objets (IoT) plus spécifiquement à la prolifération des réseaux de capteurs autonomes. Les progrès réalisés ces dernières années dans le domaine des technologies de l’information et de la communication ont permis de lever certains verrous technologiques au développement de ces réseaux de capteurs intelligents et autonomes, notamment grâce à l’amélioration des performances intrinsèques des composants microélectroniques (vitesse, consommation), la conception de circuits plus économes en énergie, ou bien la mise en place de standards de communications radio adaptés à ces contraintes énergétiques. Etant donné l’ubiquité des sources d’énergie, la fabrication de générateurs permettant d’alimenter directement ces capteurs et les rendre autonomes en énergie à partir de ces sources représente une alternative viable à l’utilisation de batteries pour prolonger la durée de vie de ces capteurs communicants. Diverses technologies de générateurs ont ainsi été proposées pour s’adapter aux différentes formes que peut prendre l’énergie, qu’elle soit d’origine thermique, mécanique ou solaire. Le présent travail est une contribution à l'élaboration d’un récupérateur d’énergie thermique à base de bilames thermiques et de matériaux piézoélectriques. Ce type de générateurs, proposé et développé au sein de STMicroelectronics à Crolles, se veut être une alternative fiable et bas coût à l’utilisation de matériaux thermoélectriques exploitant l’effet Seebeck pour générer de l’énergie électrique. Des preuves de concept de tels systèmes ont déjà été développées aussi bien à macro-échelle qu’a micro-échelle. Ce travail s’inscrit dans la continuité du développement d’un récupérateur d’énergie macroscopique reposant sur ce principe-là. L’objectif de cette thèse est dans un premier temps d’optimiser cette structure pour atteindre des niveaux de puissances plus élevés que la première preuve de concept puis dans un second temps, de réaliser son intégration afin d’effectuer des démonstrations de capteur autonome et confirmer la viabilité de la technologie développée pour de telles applicationsThe development of energy harvesting systems is linked to the emergence of the Internet of Things (IoT) more specifically to the proliferation of Wireless Sensor Networks that should respond to the growing needs for monitoring data in domains as diverse as the industry, the urban environments, the home or even the human body. Recent progress in the CMOS technology have enabled to remove some of the technical obstacles to the deployment of these smart and autonomous devices, specifically thanks to the improvements of the performances of microelectronic components, the design of ultra-low-power circuits and even the creation of wireless communication standards well adapted to the needs of wireless sensors. Given the availability of ambient energy sources like mechanical, thermal, light etc., energy harvesters are becoming reliable alternatives to batteries in order to extend the autonomy of these sensors. Consequently, various technologies of generators have been developed to harvest different kind of energies in function of their availability. The present work is a contribution to the development of a thermal energy harvester based on bimetallic strips heat engine and piezoelectric membranes. This type of technology developed by STMicroelectronics is intended to be a low cost alternative to thermoelectric generators exploiting the seebeck effect to convert heat into electricity. Based on this working principle, many harvesters both at the micro and macro scale have been fabricated. This thesis deals with the development of macroscopic energy harvesters whose first proofs of concept were established in a previous thesis. An important part of this manuscript deals with the thermal optimization of this energy harvester both in static and dynamic modes. Once the thermal properties improved, various piezoelectric materials were tested and compared to find the most adapted ones to our application and the same work is realized to choose the best device’s architecture. The integration of the energy harvester is then realized and wireless sensor node applications are demonstrated using various communication protocols and sensors. SPICE modeling of the system is also made and coupled with simulations of power management circuits developed by CEA’s design team. Finally, alternative ways to exploit wasted heat and vibrations are proposed through the development of piezoelectric bimetals and dual energy harvesters able to harvest thermal energy and mechanical energy at the same time: piezoelectric bimetals are realized either by direct deposition of piezoelectric composites or piezoelectric thin films onto bimetals. In the case of the dual energy harvester, piezoelectric cantilever beams were designed and simulated to vibrate at low frequencies (between 50Hz and 125Hz)
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Chevalier, César Clotaire. "Élaboration et caractérisation de capteurs de gaz à base de nanofils de ZnO." Phd thesis, Université Paris-Est, 2013. http://tel.archives-ouvertes.fr/tel-00975072.
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Les capteurs de gaz à base d'oxydes métalliques connaissent un engouement croissant pour des applications industrielles, militaires et environnementales. Néanmoins, ces capteurs se montrent peu sélectifs et nécessitent des températures de travail élevées pour obtenir une bonne sensibilité. La nanostructuration des matériaux permet d'augmenter la surface de réaction entre le gaz et le matériau hôte, améliorant ainsi la performance du capteur. ZnO est un semi-conducteur à large gap direct (3,37 eV) possédant de nombreuses propriétés physico-chimiques intéressantes, et aussi un matériau très prometteur pour les capteurs de gaz de type oxyde métallique. L'Elaboration de nanostructures de ZnO a conduit à un grand nombre d'études pour divers domaines d'applications. Dans ce contexte, cette thèse a pour objectif la synthèse des réseaux de nanofils de ZnO par voie hydrothermale et l'étude de leurs propriétés de détection. La première partie de ce travail porte sur l'étude systématique des différents paramètres influençant la synthèse des nanofils de ZnO. Les résultats montrent que la température de croissance, le pH de la solution et le temps de croissance influent sur la morphologie des nanofils de ZnO. Des nanofils avec un facteur d'aspect proche de 30 ont été obtenus sous conditions d'élaboration optimisées. La seconde partie de ce travail consiste en l'étude des propriétés de détection de nanofils de ZnO, par des méthodes électrique et optique. Les mesures électriques montrent une variation de résistance des nanofils, tandis que l'absorption UV révèle un déplacement du bandgap en présence du gaz. Une diminution de la résistance et un blue-shift de bandgap ont été observés lors de la présence d'un gaz réducteur tel que l'éthanol
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Englund, Carin, and Sabina Alisic. "Utveckling av taluppfattning i årskurs 1-2 : en läromedelsanalys." Thesis, Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-25682.
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Taluppfattning är grundläggande för all matematisk utveckling. I denna rapport har vi valt att analysera två olika läromedel i matematik för årskurs 1 och 2. Syftet med rapporten var att undersöka hur taluppfattning hanteras i de båda läromedlen samt vilka kognitiva nivåer (grundat på Blooms taxonomi) som stimuleras. Vi hade även för avsikt att undersöka omfattningen av konkretisering i de analyserade läromedlen. En del av vårt syfte var även att jämföra dessa två för att ta reda på om det förekommer skillnader/likheter läromedlen emellan. För att uppnå vårt syfte har vi tagit fram ett analysverktyg som vi hade till vår hjälp vid analysen. Analysverktyget har vi grundat på det centrala innehållet i Lgr11 (2011) i kombination med Blooms taxonomi. Datainsamlingsmetoden som vi använt oss av är av kvalitativ art. Resultatet är presenterat i tabeller och diagram som visar att området taluppfattning hanteras olika i de båda läromedlen, den kognitiva nivån som stimuleras mest är Förståelse. En slutsats som vi har dragit av resultatet är att det finns fler skillnader än likheter.
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Salles, Laís Monique Mendes. "Desenvolvimento de um dispositivo de medição de ruído com base no sistema OpenWrt." Ilha Solteira, 2017. http://hdl.handle.net/11449/154132.
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Orientador: João Antônio PerreiraResumo: O presente trabalho tem como proposta o desenvolvimento de um dispositivo de medição de ruído utilizando componentes e dispositivos eletroeletrônicos de baixo custo para uso no monitoramento de ruído em ambientes de trabalho. No desenvolvimento e implementação do sistema de medição foram estudas duas proposta de dispositivos, uma com base na plataforma Arduino e outra com base no sistema OpenWrt em conjunto com um roteador. Os circuitos de captação do ruído foram desenvolvidos com base em circuitos de captação de sinais já existentes, identificando o que melhor se adaptou a proposta. O sistema de medição contempla ainda a proposta de operação remota, por meio da telemetria, de forma que o operador possa controlar as medições sem estar no local. Para isso, foi utilizado um módulo Wireless no Arduino e o próprio roteador usado sistema OpenWrt. Os dispositivos de medição propostos podem ser usados tanto para o monitoramento do ruído, como para o registro dos níveis de ruído de forma continua ou em intervalos de tempo predefinidos, possibilitando assim, a obtenção do histórico do ambiente. Para avaliação de desempenho dos dispositivos foi utilizado um sistema de medição de ruído comercial e as especificações e requisitos de normas técnicas. Os resultados mostraram que o dispositivo implementado com base no sistema OpenWrt apresentou um melhor desempenho, principalmente, em relação sua taxa de amostragem que é maior, não necessitando ajustes e a busca de soluções para aumentar da ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The present work proposes the development of a noise measurement device, using components and electronic devices of low cost for use in the monitoring of noise in work environments. In the implementation of the measuring system were studied two proposals of devices one based on the platform Arduino and another based on the OpenWrt system together with a router. The noise pickup circuits were developed based on existing signal pickup circuits, identifying what best suited the proposal. The measurement system also contemplates the proposal of remote operation, by telemetry, so that the operator can control the measurements without being in place. For this, a wireless module was used in the Arduino and the router itself in the OpenWrt system. The proposed devices can be used both for noise monitoring and recording of noise levels continuously or at predefined time intervals, thus enabling the achievement of environmental history. For performance evaluation of the devices a commercial noise measurement system was used and the specifications and requirements of technical standards. The results showed that the system implemented based on the OpenWrt system presented a better performance, mainly in relation to its sampling rate that is higher, requiring no adjustments and the search for solutions to increase the sampling rate verified in the Arduino.
Mestre
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Matos, Ely Edison da Silva. "LUDI: um framework para desambiguação lexical com base no enriquecimento da semântica de frames." Universidade Federal de Juiz de Fora, 2014. https://repositorio.ufjf.br/jspui/handle/ufjf/695.
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Enquanto no âmbito da Sintaxe, as técnicas, os algoritmos e as aplicações em Processamento da Língua Natural são bem estudados e já estão relativamente bem estabelecidos, no âmbito da Semântica não é possível observar ainda a mesma maturidade. Visando, então, contribuir para os estudos em Semântica Computacional, este trabalho busca maneiras de implementar algumas das ideias e dos insights propostos pela Linguística Cognitiva, que é, por si, uma alternativa à Linguística Gerativa. A tentativa é reunir algumas das ferramentas disponíveis, seja no viés computacional (Bancos de Dados, Teoria dos Grafos, Ontologias, Mecanismos de inferências, Modelos Conexionistas), seja no viés linguístico (Semântica de Frames e Teoria do Léxico Gerativo), seja no viés de aplicações (FrameNet e ontologia SIMPLE), a fim de abordar as questões semânticas de forma mais flexível. O objeto de estudo é o processo de desambiguação de Unidades Lexicais. O resultado da pesquisa realizada é corporificado na forma de uma aplicação computacional, chamada Framework LUDI (Lexical Unit Discovery through Inference), composta por algoritmos e estruturas de dados usados na desambiguação. O framework é uma aplicação de Compreensão da Língua Natural, que pode ser integrada em ferramentas para recuperação de informação e sumarização, bem como em processos de Etiquetagem de Papéis Semânticos (SRL - Semantic Role Labeling).
While in the field of Syntax techniques, algorithms and applications in Natural Language Processing are well known and relatively well established, the same situation does not hold for the field of Semantics. Aiming at contributing to the studies in Computational Semantics, this work implements ideas and insights offered by Cognitive Linguistics, which is itself an alternative to Generative Linguistics. We attempt to bring together contributions from the computational domain (Databases, Graph Theory, Ontologies, inference mechanisms, Connectionists Models), the linguistic domain (Frame Semantics and the Generative Lexicon), and the application domain (FrameNet and SIMPLE Ontology) in order to address the semantic issues more flexibly. The object of study is the process of disambiguation of Lexical Units. The results of the research are embodied in the form of a computer application, called Framework LUDI (Lexical Unit Discovery through Inference), and composed of algorithms and data structures used for Lexical Unit disambiguation. The framework is an application of Natural Language Understanding, which can be integrated into information retrieval and summarization tools, as well as into processes of Semantic Role Labeling (SRL).
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Heitz, Jérôme. "Etude, modélisation et conception d'un multicapteur chimique à base de CNTFET." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAD031/document.
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Depuis quelques années, les explosifs artisanaux à base de peroxyde sont fréquemment utilisés dans les actes de terrorisme. Leur simplicité de conception ne les rend pas moins inoffensifs car ils sont tout aussi puissants que ceux à base de TNT (trinitrotoluène). Au regard des enjeux majeurs de la sécurité globale et en particulier de la protection du citoyen, il devient nécessaire de bénéficier d'instruments de détection fiables. C'est dans ce cadre que s'inscrit ce travail de thèse qui vise à développer un capteur intégré, sensible et sélectif aux traces d'explosifs, notamment ceux à base de peroxyde. Ce nez électronique est constitué d'une matrice de transistors à nanotubes de carbone (CNTFET) et d'une électronique et traitement des données. Après une brève introduction relative aux CNTFET pour la détection gazeuse, nous présentons les bases de l'élaboration d'une modélisation électrique du capteur. Cette modélisation a pour but, à terme, de permettre aux concepteurs decircuits intégrés de bénéficier d'un support de simulation des CNTFET, nécessaire à la mise en oeuvre de l'électronique de contrôle et de conditionnement des signaux. Nous détaillerons également ce qui constitue selon nous l'étape fondamentale précédant l'élaboration d'un modèle compact prédictif basé sur la physique, c'est à dire la compréhension topologique du réseau de nanotubes. Nous détaillerons alors différentes probabilités de contacts entre nanotubes. Nous présentons ensuite,l'élaboration de l'électronique permettant le contrôle des potentiels appliqués aux CNTFET et le conditionnement des signaux électriques. Ce conditionnement a pour objectif d'acheminer les réponses électriques du capteur vers des architectures de traitement de données utilisées pour la détection des différents gaz cibles. L'électronique intégrée en technologie CMOS HV (haute tension) est alimentée par pile basse tension. Des pompes de charge, élévateurs de tension, générant ces hautes tensions ont été étudiées, modélisées et réalisées. Nous proposons également dans ce manuscrit une nouvelle architecture de pompe de charge qui constitue, dans certaines plages d'utilisation, une alternative intéressante aux pompes de charge les plus performantes utilisées jusqu'à présentFor the last few years, improvised peroxide based explosives are frequently used in acts of terrorism. Their simple design does not make them less threatening than those based on TNT because they are equally as powerful as those based on TNT (trinitrotoluene). In view of the major issues of the overall safety and, in particular, the citizens' protection, it becomes necessary to enjoy reliable detection instruments. Such is the background of this PhD work which aims to develop a built-in sensor,sensitive and selective to traces of explosives, especially those based on peroxide. This electronic nose is made up of a network of carbon nanotube field-effect transistors (CNTFET), and data processing hardware. After a brief introduction relating to CNTFETs for gaseous detection, we will provide the basis for the elaboration of an electronic modeling of the sensor. This modeling aims, at the end, to allow designers of integrated circuits to benefit from a simulation support of CNTFETs, required to the implementation of control and signal conditioning electronics. We will also detail what are the fundamental steps mandatory before the development of a predictive compact model based on physics, which means the topological understanding of the nanotubes network. Then, we will describe different probabilities of contacts between nanotubes. Later, we will introduce the elaboration of the electronics allowing the control of the voltages applied to the CNTFETs and the electrical signals conditioning. The objective of this conditioning is to carry electrical responses from the sensor to data processing architectures used for the detection of the different target gasses. High Voltage CMOS integrated electronics are powered by low-voltage batteries. Charge pumps and voltage boosters which generate these high voltages, have been investigated, modeled and carried out. We also provide in this dissertation a new charge pump architecture which offers, in some ranges of application, an interesting alternative to the most efficient charge pumps used until now
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Melo, Jakub. "Srovnání agentích platforem pro bezdrátové senzorové sítě." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2013. http://www.nusl.cz/ntk/nusl-236410.
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This thesis deals with the agent platforms for wireless sensor networks. Wireless sensor networks together with the software and hardware tools used for their programming are introduced at the beginning of the thesis. The following chapter is devoted to the agents and their possible usage in wireless sensor networks. Two agent platforms Agilla and WSageNt are presented in the rest of the thesis. The end of the thesis presents the main differences between both platforms.
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Martins, Neto José de Ribamar. "SENSOR AMPEROMÉTRICO A BASE DE UM POLÍMERO DE IMPRESSÃO MOLECULAR COM PROTOPORFIRINA IX DE FERRO PARA A DETERMINAÇÃO DE 4-AMINOFENOL." Universidade Federal do Maranhão, 2010. http://tedebc.ufma.br:8080/jspui/handle/tede/906.
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This work presents an analytical study on determination of 4-aminophenol (4-APh) with a system based on molecurlaly imprinted polymer (MIP) and iron protoporphyrin IX as biomimetic sensor of the peroxidase enzyme. The MIP synthesis was performed by the precipitation method and the analytical determinations by amperometric measurements with a glassy carbon electrode modified with the biomimetic system. The best analytical conditions established for 4-APh determination were: applied potential of -0.1 V vs. Ag/Agl, 0.05 mol L-1 Tris buffer solution, pH 7 and hydrogen peroxide concentration of 100 μmol L-1. Under such optimized conditions, a good linear sensor response was observed in a concentration range from 10 to 90 μmol L-1 (r>0.998), with detection and quantification limits of 3 and 10 μmol L-1, respectively. Experiments performed with tap and river water samples spiked with 4-APh resulted in 93 to 112 % recovery values, suggesting the viability of using the MIP/iron protoporphyrin IX system as biomimetic sensor for determinations of 4-APh in real samples.
O presente trabalho apresenta um estudo analítico da determinação de 4-aminofenol com um sistema a base de um polímero de impressão molecular (MIP, do inglês Molecularly Imprinted Polymer) e protoporfirina IX de ferro como sensor biomimético da enzima peroxidase. A síntese do MIP foi realizada pelo método de precipitação e as determinações analíticas realizadas amperometricamente com um eletrodo de carbono vítreo modificado com o sistema biomimético. As melhores condições analíticas estabelecidas para a determinação de 4-aminofenol foram: potencial aplicado de - 0,1V vs Ag/AgCl, tampão Tris 0,05 mol L-1, pH 7,0 e concentração de peróxido de 100 μmol L-1. Sob tais condições, uma boa resposta linear do sensor foi observada numa faixa de concentração de 10 a 90 μmol L-1 (r>0,9978), com limites de detecção e de quantificação de 3 e de 10 μmol L-1, respectivamente Experimentos realizados com amostras de águas de torneira e de rio fortificadas com 4-aminofenol, resultaram em valores de recuperação entre 93 a 112 %, indicando a viabilidade da aplicação do sistema MIP/proptoporfirina IX de ferro como sensor amperométrico para a detecção de 4-aminofenol em amostras reais.
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Creux, Amélie. "Micro-capteur à base d'un spectromètre de Fourier en optique intégrée sur verre." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENT099.
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La spectrométrie est une méthode d'analyse permerttant d'avoir accès à la composition et à la strucuture de la matière. Les spectromètres étant utilisés dans de nombreux domaines , beaucoup de développements sont réalisés afin de les rendre plus compacts pour des raisons de place et de mobilité. Cette thèse présente la réalisation et la caractérisation d'un spectromètre de Fourier en optique intégrée sur verre appelé LLIFTS (Leaky Loop Integrated Fourier Transform Spectrometer). Il utilise le couplage d'un guide plan avec un guide courbe à fuite pour créer un interférogramme de Fourier. Des caractérisations dans le proche infrarouge et dans le domaine du visible ont permis de mesurer une résolution spectrale de 7nm (R=221) entre 1500nm et 1600nm et de 3nm (R=260) à 4nm (R=221) entre 700nm et 900nm. Le LLIFTS permet donc d'obtenir des résolutions spectrales équivalentes aus autres spectromètres compacts existants mais avec l'avantage d'être facilement réalisable. L'accès à l'interférogrmme de Fourier permet aussi de détecter des variations de phase entre deux ondes. Ce qui permet d'utiliser le LLIFTS dans des applications comme la tomographie optique cohérente (OCT). Des premières mesures de déphasage sont présentées dans cette thèseSpectrometry is an analytical method to access the composition and structure of the matter. Spectrometers are used in many fields. For reasons of space and mobility, many development are made to decrease the size of these spectrometers. This thesis presents the realization and characterization of a Fourier spectrometer in glass integrated optics called LLIFTS (Leaky Loop Integrated Fourier Transform Spectrometer). It uses the coupling of a plane waveguide with a bend waveguide to obtain a Fourier interferogram. Characterizations in the near infrared and visible domain were made. A spectral resolution of 7 nm (R = 221) between 1500nm and 1600nm and 3 (R = 260) 4 nm (R = 221) between 700nm and 900nm is obtained. The Fourier spectrometer developed in this thesis allows to obtain spectral resolution equivalent to other existing compact spectrometers but with an easier realisation. The measurement of the Fourier interferogram allows to detect phase changes between the two waves. So the LLIFTS can be used for applications such as optical coherence tomography (OCT). The first measurements of phase shift are presented in this thesis
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Carmo, João Roberto do. "Síntese, caracterização microestrutural e elétrica de compostos cerâmicos à base de soluções sólidas de titanato de estrôncio, titanato de cálcio e óxido de ferro." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-21112011-093502/.
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Composições cerâmicas de CaxSr1-xTi1-yFeyO3-δ, x = 0, 0,5 e 1,0, y = 0 e 0,35, foram preparadas por meio de síntese reativa de CaCO3, SrCO3, TiO2 e Fe2O3 e pela técnica dos precursores poliméricos. Os pós-cerâmicos foram avaliados por meio de análise térmica (termogravimétrica e térmica diferencial), difração de raios X e microscopia eletrônica de varredura. Compactos cerâmicos sinterizados foram analisados por difração de raios X, microscopia eletrônica de varredura, microscopia de varredura por sonda e espectroscopia de impedância. A força eletromotriz gerada entre duas faces paralelas de amostras cilíndricas foi monitorada na faixa de temperatura 600 - 1100 oC para pressão parcial de oxigênio de ~50 ppm, utilizando-se uma bomba eletroquímica de oxigênio com transdutores de zircônia estabilizada com ítria. Foram refinadas, por meio de análise de Rietveld as estruturas cristalinas determinadas na análise por difração de raios X: perovskita cúbica (x = 0) e perovskita ortorrômbica (x 0). A condutividade elétrica foi analisada por medidas de espectroscopia de impedância na faixa de freqüências 5 Hz-13 MHz da temperatura ambiente até ~200 C. A deconvolução dos diagramas de impedância [-Z\"() x Z\'()] na faixa de temperaturas 300 < T(K) < 500 mostra dois semicírculos atribuídos às contribuições intragranular (grãos) e intergranular (contornos de grão) à resistividade elétrica. Os compactos sinterizado utilizando pós preparados pela síntese de estado sólido apresentam valores de resistividade intergranular e intragranular maiores que os compactos preparados com pós obtidos pela síntese química. O sinal elétrico (força eletromotriz) gerado sob exposição a oxigênio mostra que esses compostos podem ser utilizados em dispositivos sensores de oxigênio entre 600 e 1100C. Análises topográficas em microscópio de varredura por sonda em superfícies polidas e atacadas termicamente mostram detalhes morfológicos dos grãos, permitindo concluir que compactos sinterizados preparados com pós obtidos pela rota química são menos porosos que os preparados com pós obtidos pela rota convencional de síntese de estado sólido. Estes resultados estão de acordo com os resultados de medidas de espectroscopia de impedância.CaxSr1-xTi1-yFeyO3-δ, x = 0, 0.5 and 1.0, y = 0 and 0.35, ceramic compounds were synthesized by reactive solid state synthesis of CaCO3, SrCO3, TiO2 and Fe2O3, and by the polymeric precursor technique. The ceramic powders were evaluated by thermogravimetry and differential thermal analysis, X-ray diffraction and scanning electron microscopy. Sintered ceramic pellets were analyzed by X-ray diffraction, scanning electron microscopy, scanning probe microscopy and impedance spectroscopy. The electromotive force resulting from the exposing the pellets to partial pressure de oxygen in the ~50 ppm in the 600-1100 oC range was monitored using an experimental setup consisting of an oxygen electrochemical pump with yttria-stabilized zirconia transducer and sensor. Rietveld analysis of the X-ray data allowed for determining the crystalline structures: cubic perovskite (y = 0) and orthorhombic perovskite (y 0). The electrical conductivity was determined by the two probe impedance spectroscopy measurements in the 5 Hz-13 MHz frequency range from room temperature to approximately 200 C. The deconvolution of the [-Z\"() x Z\'()] impedance diagrams in the 300 < T(K) < 500 range shows two semicircles due to intragranular (bulk) and intergranular (grain boundary) contributions to the electrical resistivity. Sintered pellets using powders prepared by the ceramic route present higher inter- and intragranular resistivity values than pellets prepared with chemically synthesized powders. The emf signal under exposure oxygen shows that these compounds may be used in oxygen sensing devices in the 600 - 1100 C range. Scanning probe microscopy topographic analysis of the polished and thermally etched surfaces of the pellets gave details of grain morphology, showing that pellets prepared with powders synthesized by the chemical route are less porous than the ones obtained by the ceramic route. These results are in agreement with the impedance spectroscopy results.
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Kamouni, Belghiti Dounia. "Réseaux d'électrodes en diamant fonctionnalisées par des nanoparticules à base de métaux de transition pour applications analytiques." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066055/document.
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Les électrodes en diamant polycristallin dopé au bore (BDD) présentent beaucoup d'intérêts et notamment une large fenêtre de potentiel supérieure à 3 V en milieux aqueux, un faible courant résiduel et une excellente résistance à la corrosion et à l'encrassement. Ces propriétés en font donc un matériau de choix pour le développement de capteurs chimiques. Afin d'exalter la réactivité des électrodes BDD envers certains composés, notre approche a consisté à déposer sur la surface des électrodes des nanoparticules à base de métaux de transition comme le platine ou l'iridium. Ces nanoparticules présentent une activité électro catalytique intéressante, ce qui ouvre la voie à la détection de produits dérivés de réactions enzymatiques, de pesticides ou de bien d'autres espèces non électro-actives sur les électrodes en BDD nues. L'objectif de mes travaux a été de mettre au point une nouvelle méthode de dépôt de nanoparticules métalliques sur la surface d'électrodes et de les caractériser d'un point de vue à la fois structurel et électrochimique. L'objectif est de développer un système de détection multi-capteurs composé d'électrodes BDD chacune fonctionnalisée par un catalyseur métallique différent sous forme de nanoparticules. Le système de détection permet ainsi d'obtenir une signature chimique caractéristique du composé à détecter. Par couplage des différents capteurs, des méthodes algorithmiques d'apprentissage / reconnaissance permettent alors d'apporter de la sélectivité au système de détection, à la manière d'une " langue électronique ". La technique a été appliquée à plusieurs composés d'intérêt, et notamment à l'eau oxygénée, l'indole, le scatol, le paraoxon, et l'imidacloprideBoron-doped polycrystalline diamond electrodes (BDD) exhibit a number of advantages, including a wide potential window above 3V in aqueous media, a low background current, and excellent resilience to corrosion and fouling. These properties make it a very interesting material for the development of chemical sensors. In order to enhance the reactivity of the BDD electrodes towards a wider range of chemical compounds, we have studied the possibility to deposit on the electrode surface nanoparticles based on transition metals such as platinum or iridium. These nanoparticles exhibit an interesting electro-catalytic activity and open the way to the detection of products derived from enzymatic reactions, pesticides or many other electrochemically non-active species. The aim of this thesis work has been to propose a new method for the deposition of metallic nanoparticles on the diamond surface and to characterize them from a structural and electrochemical point of view. The objective is to develop a multi-sensor detection system composed of several BDD electrodes each functionalized using a different metal catalyst in the form of nanoparticles. The detection system thus enables to obtain a characteristic chemical fingerprint of the product to detect. By assembling several of such sensors, and coupling them with algorithmic learning / recognition methods, the system provides an improved selectivity, in a similar way to an “electronic tongue”. This was applied to several case studies, including the detection of hydrogen peroxide, scatol, indole, paraoxon and imidaclopride
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Savary, Eric. "Conception et intégration d'une électronique de conditionnement pour un capteur audio à base de nano-fils de silicium." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4716.
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Les microphones sont des capteurs qui permettent à nos systèmes électroniques de prendre connaissance de notre environnement acoustique en fournissant un signal électrique représentatif des vibrations de l’air. Ils sont employés dans la plupart des systèmes multimédia, mais aussi dans les appareils auditifs. Dans l’implant auditif, le microphone se substitue à l’oreille humaine capable de détecter des pressions acoustiques variants de quelque μPa à quelques Pa. Les microphones, sont en général accompagnés d’un circuit électronique spécifique qui permet leur exploitation au coeur d’un système hétérogène. Depuis les toutes premières transductions acoustique-électriques, le microphone a été perfectionné avec la mise en oeuvre de nouveau principes de transduction et l’élaboration de circuit de conditionnement plus performants. Dernièrement, l’introduction de la technologie MEMS (Micro Electro Mechanical Systems) a permis de réaliser des microphones extrêmement compacts et peu couteux. Ces travaux de recherches concernent la réalisation d’un circuit électronique dédié à l’exploitation d’un transducteur M&NEMS (Micro & Nano Electro Mechanical Systems) survenant comme une évolution du MEMS. Pour commencer l’étude, le principe de transduction et l’application du microphone sont étudiés. Les circuits existants sont examinés en détail et adaptés au transducteur M&NEMS. Les résultats potentiels sont discutés et situés dans l’application. Dans un second temps, un circuit de conditionnement spécifique est proposé. Les résultats sont présentés puis le circuit électronique dédié est intégré sur silicium. Les performances des blocs fonctionnels intégrés sont mesurées et présentéesMicrophones are sensors which allow gauging acoustic environment through an electric representation of vibrations in the air. They can be found in most multimedia equipment and in hearing aids. In this particular application, microphone substitutes a human ear which is able to sense pressure level of sound ranging from a μPa to few Pa. The read-out circuit of microphones converts physical signal from transducer into electronic signals that can be used in any heterogeneous system involving audio processing. Transducers of microphones have known successive generation of improvement. The latest refinement is related to the emergence of MEMS (Micro Electro Mechanical Systems) technology which is suitable to build compact sensor. This thesis explores the design of a readout-circuit using an innovative M&NEMS (Micro & Nano Electro Mechanical Systems) technology derived from MEMS. The thesis is structured beginning with review of existing circuits for M&NEMS microphone. A comparative study is reported considering the proposed technical specifications using simulations and a prototype was realized using discrete components. In the second phase, an innovative circuit was proposed as an ASIC solution targeting M&NEMS technology developed at CEA-LETI. The performance evaluation and the physical measurements of the proposed ASIC are detailed
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Monrat, Ahmed Afif. "A BELIEF RULE BASED FLOOD RISK ASSESSMENT EXPERT SYSTEM USING REAL TIME SENSOR DATA STREAMING." Thesis, Luleå tekniska universitet, Datavetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-71081.
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Among the various natural calamities, flood is considered one of the most catastrophic natural hazards, which has a significant impact on the socio-economic lifeline of a country. The Assessment of flood risks facilitates taking appropriate measures to reduce the consequences of flooding. The flood risk assessment requires Big data which are coming from different sources, such as sensors, social media, and organizations. However, these data sources contain various types of uncertainties because of the presence of incomplete and inaccurate information. This paper presents a Belief rule-based expert system (BRBES) which is developed in Big data platform to assess flood risk in real time. The system processes extremely large dataset by integrating BRBES with Apache Spark while a web-based interface has developed allowing the visualization of flood risk in real time. Since the integrated BRBES employs knowledge driven learning mechanism, it has been compared with other data-driven learning mechanisms to determine the reliability in assessing flood risk. Integrated BRBES produces reliable results comparing from the other data-driven approaches. Data for the expert system has been collected targeting different case study areas from Bangladesh to validate the integrated system.
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Ramzi, Ammari. "DESIGN AND DEVELOPMENT OF A FALL DETECTION DEVICE WITH INFRARED RECEIVING CAPABILITIES." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1314139225.
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Sizun, Thibaut. "Effet de l'humidité sur la réponse à l'ammoniac de capteurs conductimétriques à base de matériaux moléculaires." Phd thesis, Université de Bourgogne, 2012. http://tel.archives-ouvertes.fr/tel-00783853.
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De nombreux capteurs d'ammoniac existent, mais la prise en compte de l'effet de l'humidité sur la mesure capteur est rarement assurée, y compris chez les fabricants. L'objectif de cette thèse est de proposer un transducteur conductimétrique capable de mesurer le taux d'ammoniac de façon sélective, avec une précision suffisante, pour une application au contrôle de la qualité de l'air dans un environnement à taux d'humidité variable. Le moyen employé pour atteindre cet objectif est l'utilisation de résistors à base de phtalocyanines de cobalt, sous forme de films minces, comme matériaux semi-conducteurs. L'étude porte sur la mise en forme de ces films minces réalisés par évaporation sous vide, évaporation de solvant et électrodéposition. Des bancs de mesures automatisés ont été mis en place pour effectuer les mesures électriques sous argon et pour étudierles réponses à l'ammoniac sec ou humide en appliquant des cycles exposition / repos. A partir de ces cycles de 1 min et 4 min, des réponses relatives sont calculées pour obtenir des valeurs proportionnelles aux concentrations d'ammoniac. Les effets de l'humidité seule et de l'ozone ont également été étudiés. Des tests sur la sensibilité croisée ammoniac / humidité ont été réalisés sur quatre résistors différents, dans des gammes de concentration allant de 25 à 90 ppm et dans des gammes d'humidité allant de 0 à 80% d'HR, à température ambiante. Deux d'entre eux, un résistor de phtalocyanine de cobalt (PcCo) et un résistor hybride de phtalocyanine de cobalt sulfonée /polypyrrole (s-PcCo/PPy), ont donné des résultats particulièrement intéressants.PcCo permet de discriminer des concentrations de 25, 45 et 90 ppm d'ammoniac dans une gammede 20 à 60% d'HR, avec une réponse relative de 40% à 45 ppm. De plus, mêmes si les RRs à 80%d'HR divergent légèrement, la discrimination est toujours possible entre les différentesconcentrations de NH3.s-PcCo / PPy est moins sensible à l'ammoniac, mais son étude a permis de démontrer que l'ajout dephtalocyanine dans une matrice polypyrrole augmente la sensibilité de ce matériau. Il donne uneréponse relative de 3,3% à 45 ppm. Cependant, la gamme d'humidité couverte est plus large, allant de 20 à 80% d'HR.Cette étude a donc permis de comparer des matériaux et d'estimer leur potentiel pour des applications au contrôle de la qualité de l'air avec différents taux d'humidité
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Landreau, Nina. "Capteur colorimétrique à base d’oxydes mixtes pour la détection du chloroforme dans l’air des piscines couvertes." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS522.
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Depuis une vingtaine d’années, des campagnes de mesures de la qualité de l’air intérieur des piscines couvertes ont révélé la présence de composés toxiques, notamment de chloroforme (cancérigène probable pour l’homme) à des concentrations très supérieures à la valeur toxicologique de référence recommandée par l’Anses. Ainsi, la garantie de la santé des baigneurs nécessite de pouvoir détecter facilement le dépassement de cette valeur limite.Pour pallier à l’absence d’appareil répondant à ce besoin, l’objectif de cette thèse est donc d’élaborer un capteur colorimétrique, fait d’une matrice nanoporeuse dopée en molécules-sondes capables de réagir de façon sélective et sensible avec le chloroforme pour former un produit coloré.La réaction de Fujiwara a été sélectionnée pour notre capteur et son optimisation a permis de dégager les conditions optimales qui devront être reproduites dans les pores de la matrice sol-gel pour assurer un fonctionnement optimal du capteur. En raison des contraintes imposées par la réaction de Fujiwara, un nouveau type de matrices mixtes silice-zircone a été développé pour héberger cette réaction en phase gaz.La maîtrise fine de la différence de réactivité entre les précurseurs de silice (peu réactifs) et les précurseurs de zircone (très réactifs) nous a permis de moduler à la fois l’homogénéité, l’absorbance et la porosité de ces matrices de façon à obtenir des matrices présentant les caractéristiques requises de transparence, porosité, tenue mécanique, absorbance et compatibilité avec la réaction colorimétrique choisie.Le dopage de cette matrice avec les réactifs de Fujiwara finalement été réalisé avec succès et la fonctionnalité du capteur a été démontréeDuring the last twenty year, indoor swimming-pool air quality measurement campaigns confirmed the presence of toxic compounds such as chloroform (carcinogenic) at higher level than those advised by French authorities. Hence, the ability to easily perform direct detection of chloroform at concentration above the advised threshold is crucial to ensure the safety of swimmers.At the moment, no devices seems to meet such a need. This PhD work aims at preparing a colorimetric sensor suited to this application, thanks to a nanoporous material incorporating probe-molecules to specifically react with chloroform and yield a coloured product.The optimization of the Fujiwara colorimetric reaction was carried out and the best mode to be used within the nanopores in the gas phase was identified. A new type of silica-zirconia materials had to be specifically developed to resist to the harsh chemical conditions of the Fujiwara reaction.Fine-tuning of the differential reactivity of silica (slow) and zirconia (fast) precursors led to a good control of the homogeneity, absorbance and porosity of the materials which was absolutely essential to meet the specifications of transparency, porosity, mechanical stability, absorbance and ability to host the Fujiwara reaction.Such materials were successfully doped with Fujiwara reagents, and the functional material obtained was validated as a chloroform sensor
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Grall, Simon. "Microcapteurs de particules à base de micropoutres pour le contrôle de la qualité de l'air dans un véhicule automobile." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0038/document.
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Les particules fines ont un impact réel sur la qualité de vie et la santé de millions de personnes dans les grandes zones urbaines, notamment en Asie. Pour les détecter et quantifier leur concentration, les capteurs de particules optiques sont les plus couramment étudiés, mais restent relativement chers et volumineux. Les transducteurs MEMS micropoutres sont largement utilisés pour des applications gravimétriques, pour la détection de particules ou de gaz, ce qui requiert des sensibilités massiques (Sm) élevées et des limites de détection (LOD) basses. Pour cela les micropoutres les plus adaptées sont celles ayant des fréquences de résonance (f0) et facteurs de qualité (Q) élevés, avec de faibles bruits de mesure et des masses faibles. Les micropoutres silicium sont couramment utilisées en tant que capteurs gravimétriques et sont de sérieux candidats pour répondre aux caractéristiques souhaitées. Cependant, la sérigraphie a le potentiel pour une fabrication moins chère, plus rapide et aussi à grande échelle. Pour ces micropoutres, l'actionnement et la lecture de f0 sont possibles par effet piézoélectrique. Bien qu'il existe des solutions inorganiques prometteuses sans plomb, les céramiques de titano-zirconate de plomb (PZT) possèdent encore les meilleures propriétés parmi les matériaux piézoélectriques. Des micropoutres fabriquées en technologie hybride couches épaisses sérigraphiées, à actionnement et lecture piézoélectriques intégrés, libérées à l'aide d'une couche sacrificielle polyester et avec co-cuisson de toutes les couches pour leurs libérations sont présentées ici. Différentes géométries ont été testées de 1 mm à 2 mm de large et de 1 mm à 8 mm de long, pour une épaisseur d'environ 100 μm. Une masse volumique ρ PZT = 7200 kg/m³ a été obtenue (≈ 93%ρ PZT massif). Enfin, avec une micropoutre 1×2×0,1 mm³, une sensibilité Sm ≈ 85 Hz/μm et une LOD de 70 ng ont été trouvées, permettant des applications en détection de particulesFine particulate matters (PM) have a real impact on the quality of life and health of millions of people in large urban areas, especially in Asia. In order to detect them and quantify their concentration, optical PM sensors are the most widely studied, but remain relatively expensive and bulky. MEMS microcantilever transducers are widely used for gravimetric applications, for PM or gas detection, which requires high mass sensitivities (Sm) and low limits of detection (LOD). A solution is to focus on microcantilevers with high resonance frequencies (f0) and quality factors (Q), low measurement noise and low masses. Silicon microcantilevers are commonly used as gravimetric sensors and are serious candidates to meet the desired characteristics. However, screen printing has the potential for cheaper, faster and large scale manufacturing. Such microcantilevers can be actuated and f0 read-out using the piezoelectric effect. Although promising lead-free inorganic solutions exist, titanium lead zirconate (PZT) ceramics still have the best properties among piezoelectric materials. Screen-printed microcantilevers manufactured in hybrid thick-film technology, with integrated piezoelectric actuation and read-out, released using a polyester sacrificial layer and with co-firing of all the layers are presented here. Different geometries were tested from 1 mm to 2 mm wide and from 1 mm to 8 mm long, for a thickness of about 100 μm. A density ρ PZT = 7200 kg/m³ (≈ 93%ρ PZT bulk) was obtained. With a 1×2×0.1 mm³ microcantilever, a sensitivity Sm ≈ 85 Hz/μm and a LOD of 70 ng were found, compatible with applications in PM mass detection
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Megahed, Mohamed Helmy Mostafa. "SurvSec Security Architecture for Reliable Surveillance WSN Recovery from Base Station Failure." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31154.
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Surveillance wireless sensor networks (WSNs) are highly vulnerable to the failure of the base station (BS) because attackers can easily render the network useless for relatively long periods of time by only destroying the BS. The time and effort needed to destroy the BS is much less than that needed to destroy the numerous sensing nodes.
Previous works have tackled BS failure by deploying a mobile BS or by using multiple BSs, which requires extra cost. Moreover, despite using the best electronic countermeasures, intrusion tolerance systems and anti-traffic analysis strategies to protect the BSs, an adversary can still destroy them. The new BS cannot trust the deployed sensor nodes. Also, previous works lack both the procedures to ensure network reliability and security during BS failure such as storing then sending reports concerning security threats against nodes to the new BS and the procedures to verify the trustworthiness of the deployed sensing nodes. Otherwise, a new WSN must be re-deployed which involves a high cost and requires time for the deployment and setup of the new WSN. In this thesis, we address the problem of reliable recovery from a BS failure by proposing a new security architecture called Surveillance Security (SurvSec).
SurvSec continuously monitors the network for security threats and stores data related to node security, detects and authenticates the new BS, and recovers the stored data at the new BS. SurvSec includes encryption for security-related information using an efficient dynamic secret sharing algorithm, where previous work has high computations for dynamic secret sharing. SurvSec includes compromised nodes detection protocol against collaborative work of attackers working at the same time where previous works have been inefficient against collaborative work of attackers working at the same time.
SurvSec includes a key management scheme for homogenous WSN, where previous works assume heterogeneous WSN using High-end Sensor Nodes (HSN) which are the best target for the attackers. SurvSec includes efficient encryption architecture against quantum computers with a low time delay for encryption and decryption, where previous works have had high time delay to encrypt and decrypt large data size, where AES-256 has 14 rounds and high delay. SurvSec consists of five components, which are:
1. A Hierarchical Data Storage and Data Recovery System.
2. Security for the Stored Data using a new dynamic secret sharing algorithm.
3. A Compromised-Nodes Detection Algorithm at the first stage.
4. A Hybrid and Dynamic Key Management scheme for homogenous network.
5. Powerful Encryption Architecture for post-quantum computers with low time delay.
In this thesis, we introduce six new contributions which are the followings:
1. The development of the new security architecture called Surveillance Security (SurvSec) based on distributed Security Managers (SMs) to enable distributed network security and distributed secure storage.
2. The design of a new dynamic secret sharing algorithm to secure the stored data by using distributed users tables.
3. A new algorithm to detect compromised nodes at the first stage, when a group of attackers capture many legitimate nodes after the base station destruction. This algorithm is designed to be resistant against a group of attackers working at the same time to compromise many legitimate nodes during the base station failure.
4. A hybrid and dynamic key management scheme for homogenous network which is called certificates shared verification key management.
5. A new encryption architecture which is called the spread spectrum encryption architecture SSEA to resist quantum-computers attacks.
6. Hardware implementation of reliable network recovery from BS failure.
The description of the new security architecture SurvSec components is done followed by a simulation and analytical study of the proposed solutions to show its performance.
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Abdelghani, Aymen. "Capteur de gaz hyperfréquence à base de nanotubes de carbone, imprimé par technologie jet d’encre." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0089/document.
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Au cours de ces dernières années, le développement des capteurs de gaz a connu un essor grandissant pour des applications industrielles, militaires et environnementales afin d’assurer la sécurité et la protection contre les gaz nocifs et toxiques. Ces applications demandent des capteurs sensibles, sélectifs, à faible consommation d’énergie et à faible coût. Le travail de thèse présenté dans ce manuscrit, s’inscrit dans ce contexte. Il a pour objectif la réalisation d’un capteur hyperfréquence à base de nanotubes de carbone et fabriqué par technologie jet d’encre. Le principe de fonctionnement du capteur repose sur la caractérisation en fréquence d’un résonateur RF, dont un élément est sensible grâce aux nanotubes de carbone, à la présence d’un gaz environnant. Le manuscrit aborde l’ensemble des étapes nécessaires à la réalisation du capteur, à savoir : la conception des dispositifs de test, s’appuyant sur une étude théorique de leur comportement, la caractérisation des matériaux utilisées, la fabrication sur un substrat flexible par une technique d’impression jet d’encre et enfin la caractérisation du capteur de gaz en termes de comportement en fréquence et de sensibilité en présence de gazIn recent years, the development of gas sensors has grown rapidly for industrial, military and environmental applications to ensure safety and protection against harmful and toxic gases. These applications require sensitive, selective, low power and low cost sensors. The thesis work presented in this manuscript fits into this context. Its objective is the realization of a microwave sensor based on carbon nanotubes and manufactured by inkjet technology. The operating principle of the sensor is based on the frequency characterization of an RF resonator, one element of which is sensitive, thanks to the carbon nanotubes, to the presence of a surrounding gas. The manuscript addresses all the steps necessary for the realization of the sensor, namely: the design of the test devices, based on a theoretical study of their behavior, the characterization of the materials used, the fabrication on a flexible substrate by inkjet printing technique and finally the characterization of the gas sensor in terms of frequency behavior and sensitivity in the presence of gas
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Saoudi, Massinissa. "Conception d'un réseau de capteurs sans fil pour des prises de décision à base de méthodes du Data Mining." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0065/document.
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Les réseaux de capteurs sans fil (RCSFs) déterminent un axe de recherche en plein essor, puisqu’ils sont utilisés aujourd’hui dans de nombreuses applications qui diffèrent par leurs objectifs et leurs contraintes individuelles.Toutefois, le dénominateur commun de toutes les applications de réseaux de capteurs reste la vulnérabilité des nœuds capteurs en raison de leurs caractéristiques et aussi de la nature des données générées.En effet, les RCSFs génèrent une grande masse de données en continue à des vitesses élevées, hétérogènes et provenant d’emplacements répartis. Par ailleurs, la nécessité de traiter et d’extraire des connaissances à partir de ces grandes quantités de données nous ont motivé à explorer l’une des techniques conçues pour traiter efficacement ces ensembles de données et fournir leurs modèles de représentation. Cependant, parmi les techniques utilisées pour la gestion des données, nous pouvons utiliser les techniques de Data mining. Néanmoins, ces méthodes ne sont pas directement applicables aux RCSFs à cause des contraintes des noeuds capteurs. Il faut donc répondre à un double objectif : l’efficacité d’une solution tout en offrant une bonne adaptation des méthodes de Data mining classiques pour l’analyse de grosses masses de données des RCSFs en prenant en compte les contraintes des noeuds capteurs, et aussi l’extraction du maximum de connaissances afin de prendre des décisions meilleures. Les contributions de cette thèse portent principalement sur l’étude de plusieurs algorithmes distribués qui répondent à la nature des données et aux contraintes de ressources des noeuds capteurs en se basant sur les techniques de Data mining. Chaque noeud favorise un traitement local des techniques de Data mining et ensuite échange ses informations avec ses voisins, pour parvenir à un consensus sur un modèle global. Les différents résultats obtenus montrent que les approches proposées réduisent considérablement la consommation d’énergie et les coûts de consommation, ce qui étend la durée de vie du réseau.Les résultats obtenus indiquent aussi que les approches proposées sont extrêmement efficaces en termes de calcul du modèle, de latence, de réduction de la taille des données, d’adaptabilité et de détection des événementsRecently, Wireless Sensor Networks (WSNs) have emerged as one of the most exciting fields. However, the common challenge of all sensor network applications remains the vulnerability of sensor nodes due to their characteristics and also the nature of the data generated which are of large volume, heterogeneous, and distributed. On the other hand, the need to process and extract knowledge from these large quantities of data motivated us to explore Data mining techniques and develop new approaches to improve the detection accuracy, the quality of information, the reduction of data size, and the extraction of knowledge from WSN datasets to help decision making. However, the classical Data mining methods are not directly applicable to WSNs due to their constraints.It is therefore necessary to satisfy the following objectives: an efficient solution offering a good adaptation of Data mining methods to the analysis of huge and continuously arriving data from WSNs, by taking into account the constraints of the sensor nodes which allows to extract knowledge in order to make better decisions. The contributions of this thesis focus mainly on the study of several distributed algorithms which can deal with the nature of sensed data and the resource constraints of sensor nodes based on the Data mining algorithms by first using the local computation at each node and then exchange messages with its neighbors, in order to reach consensus on a global model. The different results obtained show that the proposed approaches reduce the energy consumption and the communication cost considerably which extends the network lifetime.The results also indicate that the proposed approaches are extremely efficient in terms of model computation, latency, reduction of data size, adaptability, and event detection
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Ghaddab, Boutheina. "Développement d’un capteur de gaz à base de couche hybride dioxyde d’étain / nanotubes de carbone." Thesis, Besançon, 2012. http://www.theses.fr/2012BESA2028/document.
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L’objectif de cette étude est le développement d’un capteur de gaz à base de couche hybrideSnO2/SWNTs dans le but d’améliorer les performances des capteurs chimiques « classiques »uniquement constitués de dioxyde d’étain. En premier lieu, afin de maîtriser la synthèse dumatériau sensible, nous avons validé l’élaboration d’une couche sensible à base de dioxyded’étain préparée par procédé sol-gel. Le matériau synthétisé a été déposé par la technique ‘microgoutte’sur une micro-plateforme permettant simultanément le chauffage de la couche sensible etla mesure de sa conductance. L’étude des réponses électriques du capteur de gaz en présence dubenzène a permis de valider la possibilité d’utilisation du sol d’étain préparé pour la réalisation decouches sensibles aux gaz. En effet, des traces de benzène (500 ppb) ont été détectées à latempérature optimale de couche sensible de 420°C.Le second volet de cette étude repose sur la fabrication du matériau hybride obtenu par dispersiondes nanotubes de carbone dans un sol d’étain. Les couches sensibles élaborées par dip-coating àpartir du sol d’étain modifié par les nanotubes de carbone ont clairement montré la possibilité dedétection de divers gaz (ozone et ammoniac) à température ambiante. Ce résultat constitue l’undes points importants de ce travail de thèse dans la mesure où jusqu’à présent les capteurschimiques à base de dioxyde d’étain ne présentaient une forte sensibilité aux gaz que pour destempératures de fonctionnement de l’ordre de 350-400°C. Pour les deux gaz cibles étudiés dans lecadre de ce travail, la limite de détection à température ambiante a été évaluée à 1 ppm enprésence de NH3 et est inférieure à 20 ppb en présence d’ozone.La dernière partie de ce travail a porté sur l’optimisation des performances de détection descouches hybrides. Dans ce cadre, les expérimentations ont porté sur l’étude de l’influence dedivers paramètres tels que la quantité de nanotubes dans le matériau hybride, la température decalcination de la couche sensible, la température de fonctionnement ou encore les propriétésphysico-chimiques des nanotubes de carbone (mode de synthèse, diamètre,…) sur l’efficacité dedétection des couches sensibles. Les résultats ainsi obtenus en termes de performance de détectionont été discutés en relation avec les paramètres expérimentaux utilisésThe objective of this study is to develop a gas sensor based on a hybrid layer of SnO2/SWNTs inorder to improve the performance of “Conventional” chemical sensors basically made from tinoxide. First, in order to control the synthesis of the sensitive material, we validated the elaborationof a sensitive layer based on tin dioxide prepared using the sol-gel process. The synthesizedmaterial was deposited by the 'microdrop' technique on a micro-platform which simultaneouslyallows the heating of the sensitive layer whilst also measuring its conductance. The study of theelectrical responses of the gas sensor in the presence of benzene has allowed us to validate thepossibility of using our prepared tin sol for the realization of gas sensitive layers. In fact, it waspossible to detect benzene at traces with an optimal temperature of the sensing layer found to be420ºC.The second part of this study describes the synthesis of the hybrid sensor obtained by dispersingSWNTs in the tin-oxide based sol. The sensitive layers made by dip-coating from the carbonnanotubes modified tin sol have clearly shown the possibility of detecting various gases (ozoneand ammonia) at room temperature. This result is one the most important points of this work tothe extent that until now the chemical sensors based on tin dioxide only showed a high sensitivityto gases when they were operated at temperatures in the range of 350 - 400ºC. Concerning the twotarget gases tested in this work, the detection limit at room temperature was evaluated at 1 ppm inthe presence of NH3 and was lower than 20 ppb in the presence of ozone.The last part of this work has focused the optimization of the detection performance of thesensitive layers. In this case, the experimental study was oriented towards examination of theeffect of various parameters such as the amount of nanotubes in the hybrid material, thecalcination temperature of the sensitive layer, the sensor working temperature and also thephysico-chemical properties of the carbon nanotubes (synthesis method, diameter...) on thedetection efficiency of the sensing layers. The results obtained in terms of detection performancewere discussed in relation to the experimental parameters used
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Othman, Mehdi. "Effet des nanograins métalliques sur les propriétés de détection des capteurs de gaz à base de WO3." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4360.
Full textAbstract:
Ce travail de thèse porte sur l’amélioration des performances des capteurs de gaz à base de WO3 en s’intéressant particulièrement à l’effet de l’ajout des nanoparticules métalliques sur les propriétés de détection de ces dispositifs. La démarche a consisté à évaluer puis améliorer les performances des capteurs sous différents gaz oxydants et réducteurs. Deux approches ont été menées : une approche théorique qui consiste à modéliser la résistance du capteur sous gaz et une approche expérimentale qui consiste à modifier la surface des couches sensibles par des ajouts métalliques. Le modèle ainsi développé a permis de mettre en évidence les différents paramètres intrinsèques et structuraux de la couche sensible, sur lesquels il est possible d’agir pour améliorer les performances des capteurs. La deuxième approche a consisté à ajouter des nanograins métalliques. Cette méthode montre une grande efficacité sur les performances des capteurs. Les résultats obtenus avec les nanoparticules d’or montrent en effet une amélioration de la réponse, des temps de réponse et de recouvrement ainsi que du temps de stabilisation des capteurs sous ozone. Il en est de même pour les ajouts de nanoparticules d’argent et de palladium, même si les résultats sont différents. Dans le cas de l’ajout de nanoparticules de cobalt, un phénomène singulier se manifeste par l’inversion des réponses des capteurs dans certains cas. Cette propriété peut être exploitée pour la détection sélective de différents gaz, avec la même couche sensible modifiée par l’ajout de très faibles quantités de matièreThis work focuses on improving the performance of WO3-based gas sensors with particular attention to the effect of metal additives on device sensing properties. The goal is to assess and improve the performance of sensors under different oxidizing and reducing gases. Two approaches have been taken: a theoretical approach which consists in the modeling of gas sensor resistance and an experimental approach which consists in modifying the surface of the sensitive layers by metal nanograins. The developed model allowed us to highlight the various intrinsic and structural parameters of the sensitive layer, in which it is possible to act to improve the performance of the sensors. The second approach is to add metallic nanograins. This method shows high efficiency on the sensor performance. Indeed, the results obtained with the gold nanoparticles show improved response, response and recovery times, and the time stabilization under ozone. It is the same for the additions of silver and palladium nanoparticles, even if the results are different. In the case of adding cobalt nanoparticles, a singular phenomenon is manifested by the sensor responses inversion in some cases. This property can be exploited for the selective detection of different gases, with the same sensitive layer modified by the addition of very small quantities of material