Public Safety Cognitive Radio (PSCR) is a Software Defined Radio(SDR) developed by the Center for Wireless Telecommunications (CWT) at Virginia Tech. PSCR can configure itself to interoperate with any public safety waveform it finds during the scan procedure. It also offers users the capability to scan/classify both analog and digital waveforms. The current PSCR architecture can only run on a general purpose processor and hence is not deployable to the public safety personnel. In the first part of this thesis an Android based control application for the PSCR on a Beagle Board(BB) and the GUI for the control application are developed. The Beagle Board is a low-cost, fanless single board computer that unleashes laptop-like performance and expandability. The Android based Nexus One connected to the Beagle Board via USB is used to control the Beagle Board and enable operations like scan, classify, talk, gateway etc. In addition to the features that exist in the current PSCR a new feature that enables interoperation with P25 (CPFSK modulation) protocol based radios is added. In this effort of porting the PSCR to Beagle Board my contributions are the following (i) communication protocol between the Beagle Board and the Nexus One (ii) PSCR control application on the Android based Nexus One (iii) detection/classification of P25 protocol based radios. In the second part of this thesis, a prototype testbed of a Dynamic Spectrum Access (DSA) broker that uses the Beagle Board PSCR based sensor/classifier is developed. DSA in simple terms is a concept that lets the user without license (secondary user) to a particular frequency access that frequency, when the licensed user (primary user) is not using it. In the proposed testbed we have two Beagle Board based sensor/classifiers that cooperatively scan the spectrum and report the results to the central DSA broker. The DSA broker then identifies the frequency spectrum without primary users and informs the secondary users about the free spectrum. The secondary users can then communicate among each other using the frequency band allocated by the DSA broker. When the primary user enters the spectrum occupied by the secondary user, the DSA broker instructs the secondary user to use a different spectrum. Based on the experiments conducted on the testbed setup in the CWT lab environment, the average time taken by the DSA broker to detect the presence of primary user is 0.636 secs and the average time taken for the secondary user to leave the frequency band that interferes with the primary user is 0.653 secs. / Master of Science

A simple Richardson iteration procedure converges slowly when applied to thick, diffusive problems with scattering ratios near unity. The current state of the art for overcoming this is to use a Krylov method with a diffusion preconditioner. However, the diffusion preconditioner must be tailored to the discretization of the transport operator to ensure effectiveness. We expand work from the bilinear discontinuous (BLD) finite element method (FEM) in two dimensions into a preconditioner applicable to all Discontinuous Galerkin FEMs in two and three dimensions. We demonstrate the effectiveness of our approach by applying it to the piecewise linear discontinuous (PWLD) FEM, which is notable for its flexibility with unstructured meshes. We employ a vertex-centered continuous FEM diffusion solution followed by local one-cell calculations to generate discontinuous solution corrections. Our goal is to achieve the same level of performance for PWLD and other methods, in two and three dimensions, as was previously achieved for BLD in two dimensions. We perform a Fourier analysis of this preconditioner applied to the PWLD FEM and we test the preconditioner on a variety of test problems. The preconditioned Richardson method is found to perform well in both ne and coarse mesh limits; however, it degrades for high-aspect ratio cells. These properties are typical for partially consistent diffusion synthetic acceleration (DSA) schemes, and in particular they are exactly the properties of the method that was previously developed for BLD in two dimensions. Thus, we have succeeded in our goal of generalizing the previous method to other Discontinuous Galerkin schemes. We also explore the effectiveness of our preconditioner when used within the GMRES iteration scheme. We find that with GMRES there is very little degradation for cells with high aspect ratios or for problems with strong heterogeneities. Thus we find that our preconditioned GMRES method is efficient and effective for all problems that we have tested. We have cast our diffusion operator entirely in terms of the single-cell matrices that are used by the discontinuous FEM transport method. This allows us to write our diffusion preconditioner without prior knowledge of the underlying FEM basis functions or cell shapes. As a result, a single software implementation of our preconditioner applies to a wide variety of transport options and there is no need to re-derive or re-implement a diffusion preconditioner when a new transport FEM is introduced.

La miniaturisation des circuits intégrés est largement tributaire de la lithographie optique qui va définir la taille minimale qu’il est possible d’obtenir sur un circuit. Actuellement, des moyens considérables sont mises en œuvre pour aller au-delà de la limite de résolution des systèmes optiques qui sont en production. Parmi les techniques qui sont envisagées, l'auto-assemblage des copolymères à bloc permet de diminuer la résolution des systèmes optiques utilisés et apparait donc comme une possible solution. Les copolymères à bloc sont des chaînes de polymères constituées de 2 polymères. Sous l’action de la chaleur, un mélange de copolymères à bloc va s’organiser de sorte que les polymères forment des domaines disjoints et réguliers. Ensuite, l’un des 2 domaines peut être gravé pour former les motifs désirés. En contraignant cet assemblage, il est possible de contrôler l’impression des motifs ainsi obtenus.Pour être utilisé en production, ce procédé doit être capable d’imprimer les motifs désirés avec une certaine précision afin d’assurer la fiabilité des niveaux ainsi obtenus. Tout l’enjeu de cette thèse est de mettre en place une analyse permettant de garantir cette impression avec une fiabilité suffisante. Nous nous sommes en particulier intéressés à un critère à un critère statistique portant sur le recouvrement de motifs entre 2 niveaux différents.Pour y parvenir, nous avons établis une plateforme pour établir des règles de dessin permettant d’assurer ce critère. Nous avons dans un premier temps simplifier le critère statistique en un critère plus simple à utiliser en étudiant finement les variabilités misent en jeux. Pour obtenir expérimentalement des valeurs de variabilités, nous nous sommes intéressés à l’étude des images SEM afin d’extraire de manière la plus automatisée possible ce type d’information. Finalement, nous avons établi pour le procédé DSA un ensemble de règles de dessin spécifique pour assurer notre critère. / The miniaturization of integrated circuits is largely dependent on optical lithography which is used to define the minimum size that can be obtained on a circuit. Currently, considerable resources are being deployed to go beyond the resolution limit of the optical systems that are in production. Among the techniques that are envisaged, block copolymer self-assembly makes it possible to reduce the resolution of the optical systems used and thus appears as a possible solution. Block copolymers are polymer chains consisting of two polymers. Under the action of heat, a mixture of block copolymers will be organized so that the polymers form disjoint and regular domains. Then one of the two domains can be etched to form the desired patterns. By constraining this assembly, it is possible to control the printing of the patterns thus obtained.To be used in production, this process must be able to print the desired patterns with a certain precision in order to ensure the reliability of the levels thus obtained. This thesis aims to set up an analysis to guarantee this impression with sufficient reliability. In particular, we look at a statistical criterion relating to the recovery of motifs between two different levels.To achieve this, we have established a platform to establish drawing rules to ensure this criterion. We first simplify the statistical criterion into a simpler criterion to use by studying finely the variabilities involved. To obtain variability values experimentally, we are interested in studying SEM images in order to extract this type of information in the most automated way possible. Finally, we have established for the DSA process a set of specific drawing rules to ensure our criterion.

Dans le contexte d’une miniaturisation des circuits imprimés dans l’industrie de la microélectronique, les méthodes de structuration optiques appelées photolithographies arrivent en limite de résolution. L’utilisation complémentaire de l’auto-assemblage dirigé (DSA) de copolymère à blocs (CPB) permet de repousser les dimensions critiques (CD) atteignables tout en multipliant la densité des structures obtenues. Ces matériaux peuvent en effet former des motifs géométriques biphasés et périodiques de dimensions inférieures à la vingtaine de nanomètre. Rapides, bas coût et compatibles avec les équipements déjà disponibles dans l’industrie, les différents procédés DSA pour application ligne/espace développés dans la littérature se heurtent néanmoins à des problématiques de défectivité, de rugosité et d’uniformité des dimensions transférées. La plupart des solutions envisagées se font au détriment des arguments de base en faveur du DSA, notamment en ce qui concerne sa compatibilité avec la lithographie actuellement utilisée dans l’industrie. Dans ce contexte, le travail de thèse présenté ici s’attachera à étudier et solutionner les différentes problématiques liées à l’utilisation en graphoépitaxie du DSA comme solution complémentaire à la lithographie conventionnelle. Cette thèse centrée sur le matériau PS-b-PMMA s’est tout d’abord attachée à la compréhension des mécanismes impliqués dans la structuration de ces domaines lamellaires dans deux environnements. En configuration plane tout d’abord, l’impact des paramètres dictant la morphologie, l’orientation et la défectivité du CPB est étudié. La cinétique d’organisation des micro domaines peut alors être optimisée pour obtenir des motifs les mieux définis et les plus stables possibles, en un minimum de temps. Des optimisations matériaux proposées par la société partenaire ARKEMA sont évaluées comme prometteuses, et l’importance du contrôle de l’atmosphère sur le comportement du CPB en température est étudiée. En utilisant ces premiers acquis, le matériau est utilisé pour réaliser la densification de motifs « guides » ligne/espace préalablement réalisés par lithographie optique. L’étude de la morphologie adoptée par le polymère en fonction des multiples paramètres du guide (dimension, chimie d’interface, taux de remplissage…) permet de délimiter des fenêtres de fonctionnement pour un procédé stable sur plaque 300mm. La dimension de ces fenêtres est confirmée par une étude statistique suivant les métriques de défectivité et de rugosité, mesurées par un protocole de métrologie développé pendant cette thèse. Cette première étude a fait l’objet d’une publication d’un papier. Dans un effort de démonstration de l’intérêt de ce procédé, son intégration dans un empilement de réalisation de transistors en nanofils est réalisée. De premiers essais de transfert révèlent des problématiques de défectivités locales jusqu’alors masquées par l’épaisseur du film. Les méthodes de transferts disponibles étant incapables de corriger ces défauts, une variante du procédé DSA est développée. Elle repose sur la possibilité de modifier sélectivement les énergies de surfaces par application d’une dose contrôlée de lumière UV. Une étude associant à la fois la modification de la morphologie du PS-b-PMMA et la composition du matériau (suivie par spectroscopie infrarouge) en fonction de cette dose d’insolation révèle qu’un phénomène de photo-oxydation est responsable de ces phénomènes. Grâce à cette méthode, qui fait l’objet d’une publication en cours de soumission, les surfaces directement en contact avec le CPB sont modifiées de façon à le contraindre à adopter des configurations morphologiques sans défauts enterrés. Ce résultat est confirmé par les différentes étapes de transfert qui permettent de réaliser les nanofils désirés avec des dimensions maîtrisées. Des problématiques d’uniformité de remplissage sont toutefois adressées car elles restent un obstacle des nanofils uniformes à travers une plaque 300mm. / There is a fixed limit to the maximum resolution the photolithography can provide in the context of the integrated circuit’s size reduction encouraged by the microelectronic industry. The Directed Self-Assembly (DSA) of bloc copolymers (BCP) can be used as a complementary technique enabling smaller critical dimensions of features (CD) obtained by density multiplication of initial, loose i193 lithography patterns. These materials can undergo specific phase separation to self-assemble into periodic, sub-20nm ordered nanostructures.Fast, cost-efficient and highly compatible with equipment and techniques already in use in the industry for line/space (L/S) applications, the different DSA processes found in literature still suffer from defectivity, roughness and CD uniformity (CDU) issues. Most successful solutions are made possible at the loss of some of the most appealing DSA features, mainly its compatibility with current i193 lithography. In this context, the work of this thesis studied and proposed innovative solutions to the problematics posed when using graphoepitaxy as the DSA complementary technique.This work presented therein - revolving around a 38nm period lamellar PS-b-PMMA material - first tried to comprehend the mechanisms involved in the self-assembly of lamellae in one of two environment: flat configuration and 3D, graphoepitaxy configuration. In the former, a study of the parameters dictating the morphology, orientation and defect levels of the BCP was performed. This provides a mean to optimize the kinetics of self-assembly to last less than five minutes while enabling stable and reproducible morphology. Materials optimization and atmosphere composition’s impact during annealing is also discussed. This initial knowledge is then used to perform the density multiplication of L/S guiding pattern using conventional optical lithography at Leti. The study of the lamellae morphology as a function of the multiples guiding patterns’ parameters (CD, interface chemistries, thickness levels…) provides fixed process windows (PW) for a stable process over a 300mm wafer. The shape and size of these PWs is further confirmed by a statistic study of defectivity and roughness metrics as defined by a specific metrology protocol developed during this thesis. This work has led to the publication of a paper.In an effort to demonstrate its relevance in the industry, full integration of this DSA process is carried out in pursuit of functional stacked nanowire (NW) transistors acquisition. First etching tests failed though, as they revealed unknown defective formation of the lamellae at the buried interface. The etching process Leti available at Leti proved enable to compensate for these local variations of transfer features. Consequently, a new iteration of the DSA process is presented. It consists in using UV light exposure to selectively shift the interfacial energies of the guiding patterns’ surfaces. A study of the shift in both the observed lamellae morphology and the composition of the material (followed by Infrared Spectroscopy) as a function of the UV dosage is performed. It identifies a photo-oxidation mechanism which can be finely tuned to independently promote defect-free alignment of the BCP lamellae with any of the guiding pattern surfaces. This work, currently awaiting publication, is further verified by the different etching steps achieving monocrystalline silicon nanowires of controlled dimensions. The associated transistors are now being submitted to electrical characterization. Full wafer uniformity of features is a work in progress however, as BCP thickness filling of guiding patterns is still highly dependent on their density.

Diploma thesis deals with an anonymous transmit of messages using protocol for anonymous authentication. In first part, we introduce theoretical familiarization to the issues and description protocol for anonymous authentication. Further, it describes the suggestion of the communication between the client and the server. Finally, contains a description of the created system for anonymous transmit of messages, which consists of the server and clients, who can leave challenges on the server for other users and they obtains challenges from the server. The thesis explains how to start and control program. There are also discussed methods of computing verification values, encryption keys and messages and authentication of receivers.

To date, the potential of on-line Dynamic Security Assessment (DSA) to monitor, alert, and enhance system security is constrained by the longer computational cycle time. Traditional techniques requiring extensive numerical computations make it challenging to complete the assessment within an acceptable time. Longer computational cycles produce obsolete security assessment results as the system operating point evolves continuously. This thesis presents a DSA algorithm, based on Transient Energy Function (TEF) method and machine learning, to enable frequent computational cycles in on-line DSA of power systems. The use of selected terms of the TEF as pre-processed input features for machine learning demonstrated the ability to successfully train a contingency-independent classifier that is capable of classifying stable and unstable operating points. The network is trained for current system topology and loading conditions. The classifier can be trained using a small dataset when the TEF terms are used as input features. The prediction accuracy of the proposed scheme was tested under the balanced and unbalanced faults with the presence of voltage sensitive and dynamic loads for different operating points. The test results demonstrate the potential of using the proposed technique for power system on-line DSA. Power system devices such as HVDC and FACTS can be included in the algorithm by incorporating the effective terms of a corresponding TEF. An on-line DSA system requires the integration of several functional components. The practicality of the proposed technique in terms of a) critical data communications aspects b) computational hardware requirements; and c) capabilities and limitations of the tools in use was tested using an implementation of an on-line DSA system. The test power system model was simulated using a real-time digital simulator. The other functional units were distributed over the Local Area Network (LAN). The implementation indicated that an acceptable computational cycle time can be achieved using the proposed method. In addition, the work carried out during this thesis has produced two tools that can be used for a) web-based automated data generation for power system studies; and b) testing of on-line DSA algorithms. / February 2017

Neste trabalho foram investigadas as propriedades de eletrodos ternários ADEs de composição nominal Ti/Ru0,3Ti(0,7-x)SnxO2 (x = 0; 0,2; 0,3; 0,4; 0,7), utilizando as medidas de Espectroscopia de Impedância Eletroquímica (EIE) em função da freqüência ac e potencial. A EIE é uma técnica de análise \"in situ\", que fornece informações importantes a respeito dos processos de carregamento/descarregamento da interface. O material eletródico utilizado foi preparado utilizando-se a metodologia de decomposição térmica de precursores poliméricos (DPP), um método que permite a obtenção de filmes finos, com superfície homogênea e um excelente controle do metal presente no recobrimento de óxidos. Os resultados obtidos foram interpretados de acordo com duas abordagens: a de circuito equivalente e também a de linha de transmissão, com a finalidade de verificar as diferenças e a eficácia de ambas abordagens de análise, bem como suas limitações para descrever o sistema em questão. Os experimentos de EIE foram realizados com eletrodos recém preparados nos intervalos de potencial referentes às regiões da dupla camada elétrica (DCE) e da reação de desprendimento de oxigênio (RDO), e também durante o processo de desativação dos mesmos nos testes de vida útil (TVU). Os circuitos equivalentes que melhor ajustaram os dados experimentais para os experimentos nas regiões da DCE e na RDO foram: RWL(Cdc[RpQp])(RfQf) e RWL(RtcQdc)(RfQf), respectivamente. O comportamento da capacitância da dupla camada elétrica em função dos potenciais na região da DCE é similar ao comportamento observado pelo voltamograma. A troca de TiO2 por SnO2 favoreceu a RDO, apresentando valores menores de Rtc. Na abordagem utilizando linha de transmissão, foi possível representar o comportamento dos eletrodos Ti/Ru0,3Ti(0,7-x)SnxO2 em ambas regiões (DCE e RDO) utilizando apenas uma linha de transmissão, formada por um único canal, onde c1 é formado por r ou q, e a interface z é formada por um conjunto em paralelo (rq). Os valores de rtc diminuem com o aumento do potencial e com o aumento da quantidade de SnO2 no sistema. Os diferentes componentes dos circuitos (Rf,Cdc, RW e L) obtidos para ambas abordagens apresentaram comportamentos similares. / In this work, we have investigated the electrochemical proprieties of ternary electrodes of the DSA-type with nominal compositions of Ti/Ru0,3Ti(0,7-x)SnxO2 (x = 0; 0,2; 0,3; 0,4; 0,7), using electrochemical impedance spectroscopy (EIE) as a function of ac frequency and potential. The EIE is an in situ analytical technique, which furnishes useful information about the charging/discharching process of the interface. The investigated electrode material has been prepared by thermal decomposition of the polymeric precursor (DPP). This method is possible to obtain thin films with homogeneous surface, as well as excellent control of the metal oxide present in the ceramic coating. The experimental data has been modeled using two different approaches: equivalent circuits and transmission line. The main purpose of doing this was to evaluate the efficiency of both models, as well as their limits concerning the description of the investigated system. The EIS experiments were conducted with fresh by prepared electrodes, in the potential region covering the double layer domain (DL) and the oxygen evolution reaction (OER). The electrode deactivation process was studied by using the electrode life time test. The equivalent circuits derived from the simulation of experimental data for the DL and OER regions were RWL(Cdl[RpQp])(RfQf) and RWL(RctQdl)(RfQf), respectively. The behavior of the capacitance in the double layer domain is similar to the behavior of the voltammogram. Substitution of TiO2 for SnO2 favors OER, leading to lower Rct values. By using the transmission line (TL) approach, it was possible to represent the behavior of Ti/Ru0,3Ti(0,7-x)SnxO2 electrodes in both potential regions (DL and OER) using a single TL, formed by one channel, where c1 is formed by r and q, the interface z is formed by a set of (rq) in parallel. The rct value diminishes as the potential and SnO2 content are increased. The different components of the circuit (Rf,Cdl, RW e L) presented similar behavior for both approaches.

Neste trabalho é apresentado o estudo da degradação eletroquímica de fenol, formaldeído e misturas de fenol-formaldeído sobre ânodos dimensionalmente estáveis (ADE). Foi utilizado um ADE comercial (composição nominal Ti/Ti0,7Ru0,3O2), em uma célula eletroquímica de compartimento único sob agitação constante. As concentrações utilizadas nas misturas de fenol-formaldeído foram similares às concentrações encontradas no efluente fornecido pela indústria de resinas fenólicas Schenectady Crios, localizada na cidade de Rio Claro, SP. No final do trabalho também foi feita a degradação eletroquímica do efluente industrial com os melhores parâmetros. O recobrimento do ADE foi caracterizado por Microscopia Eletrônica de Varredura (MEV) e análises de Energia Dispersiva de Raios X (EDX). A caracterização eletroquímica foi feita por voltametria cíclica na ausência e na presença das substâncias orgânicas sob estudo. Durantes as eletrólises, a degradação das substâncias inicialmente presentes em solução foi verificadas por análises de Cromatografia Líquida de Alta Eficiência (CLAE) e Carbono Orgânico Total (COT). Os subprodutos formados (ácido fórmico, benzoquinona, hidroquinona, catecol e resorcinol) também foram identificados e quantificados por CLAE. Cálculos de estimativa do consumo energético também foram realizados para cada eletrólise.Foram variados os seguintes parâmetros: as densidades de corrente aplicadas, o controle da temperatura das soluções durante as eletrólises, o pH e as concentrações iniciais de fenol e formaldeído contidas nas soluções.O decaimento das concentrações das substâncias orgânicas apresenta uma cinética de pseudo primeira ordem. Observou se que quanto maior a densidade de corrente aplicada, maior é a taxa de remoção de COT, porém o consumo energético também é maior. Não se obteve a mineralização total do poluente, porém foi possível atingir uma remoção de aproximadamente 90% de COT para as soluções contendo apenas formaldeído, aplicando uma densidade de corrente de 40 mA cm-2 durante 2 horas de eletrólise. Foi possível a identificação e a quantificação dos subprodutos presentes nas soluções e no efluente industrial. As degradações eletroquímicas realizadas sem o controle da temperatura das soluções obtiveram um consumo energético menor e maior remoção de COT. / In this work presents the study of electrochemical degradation of phenol, formaldehyde and phenol-formaldehyde mixtures at dimensionally stable anodes (DSA®). Commercial DSA® electrodes (nominal composition: Ti/Ti0,7Ru0,3O2), ) were employed in a single compartment electrochemical cell under constant agitation. The concentrations used for the mixtures of phenol-formaldehyde were similar to concentrations found in effluent provided by the phenolic resin producer Crios Schenectady, located in Rio Claro, São Paulo state. In the final stage of the present study, the electrochemical degradation of real industrial effluent was performed employing the best parameters observed for the simulated effluents. The oxide coating of the electrode was characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive X Ray analyses (EDX). The electrochemical characterization of the DSA® was performed using cyclic voltammetry in the absence and presence of organic substances. The degradation of the substances inicially present in solution were monitored by High Performance Liquid Chromatography (HPLC) and Total Organic Carbon (TOC) analyses. The products formed (formic acid, benzoquinone, hydroquinone, catechol and resorcinol) were also identified and quantified by HPLC. Estimates of the energy consumption were also performed for each electrolysis.The current densities applied, the concentrations of organic substance of the solution were varied during the electrochemical oxidation.The concentration decay of organic substances displayed pseudo first order kinetics of. It was observed that the higher the applied current density, the higher the TOC removal rate , but the energy consumption is higher. Total mineralization was not attained, but removals of approximately 90% of TOC were shown to be possible. It was possible the identification and quantification of products into the solutions and industrial effluents. The electrochemical degradation carried out without controlling the temperature of the solutions obtained a lower energy consumption and higher removal of TOC.

Neste trabalho foram investigadas as propriedades de eletrodos ternários ADEs de composição nominal Ti/Ru0,3Ti(0,7-x)SnxO2 (x = 0; 0,2; 0,3; 0,4; 0,7), utilizando as medidas de Espectroscopia de Impedância Eletroquímica (EIE) em função da freqüência ac e potencial. A EIE é uma técnica de análise \"in situ\", que fornece informações importantes a respeito dos processos de carregamento/descarregamento da interface. O material eletródico utilizado foi preparado utilizando-se a metodologia de decomposição térmica de precursores poliméricos (DPP), um método que permite a obtenção de filmes finos, com superfície homogênea e um excelente controle do metal presente no recobrimento de óxidos. Os resultados obtidos foram interpretados de acordo com duas abordagens: a de circuito equivalente e também a de linha de transmissão, com a finalidade de verificar as diferenças e a eficácia de ambas abordagens de análise, bem como suas limitações para descrever o sistema em questão. Os experimentos de EIE foram realizados com eletrodos recém preparados nos intervalos de potencial referentes às regiões da dupla camada elétrica (DCE) e da reação de desprendimento de oxigênio (RDO), e também durante o processo de desativação dos mesmos nos testes de vida útil (TVU). Os circuitos equivalentes que melhor ajustaram os dados experimentais para os experimentos nas regiões da DCE e na RDO foram: RWL(Cdc[RpQp])(RfQf) e RWL(RtcQdc)(RfQf), respectivamente. O comportamento da capacitância da dupla camada elétrica em função dos potenciais na região da DCE é similar ao comportamento observado pelo voltamograma. A troca de TiO2 por SnO2 favoreceu a RDO, apresentando valores menores de Rtc. Na abordagem utilizando linha de transmissão, foi possível representar o comportamento dos eletrodos Ti/Ru0,3Ti(0,7-x)SnxO2 em ambas regiões (DCE e RDO) utilizando apenas uma linha de transmissão, formada por um único canal, onde c1 é formado por r ou q, e a interface z é formada por um conjunto em paralelo (rq). Os valores de rtc diminuem com o aumento do potencial e com o aumento da quantidade de SnO2 no sistema. Os diferentes componentes dos circuitos (Rf,Cdc, RW e L) obtidos para ambas abordagens apresentaram comportamentos similares. / In this work, we have investigated the electrochemical proprieties of ternary electrodes of the DSA-type with nominal compositions of Ti/Ru0,3Ti(0,7-x)SnxO2 (x = 0; 0,2; 0,3; 0,4; 0,7), using electrochemical impedance spectroscopy (EIE) as a function of ac frequency and potential. The EIE is an in situ analytical technique, which furnishes useful information about the charging/discharching process of the interface. The investigated electrode material has been prepared by thermal decomposition of the polymeric precursor (DPP). This method is possible to obtain thin films with homogeneous surface, as well as excellent control of the metal oxide present in the ceramic coating. The experimental data has been modeled using two different approaches: equivalent circuits and transmission line. The main purpose of doing this was to evaluate the efficiency of both models, as well as their limits concerning the description of the investigated system. The EIS experiments were conducted with fresh by prepared electrodes, in the potential region covering the double layer domain (DL) and the oxygen evolution reaction (OER). The electrode deactivation process was studied by using the electrode life time test. The equivalent circuits derived from the simulation of experimental data for the DL and OER regions were RWL(Cdl[RpQp])(RfQf) and RWL(RctQdl)(RfQf), respectively. The behavior of the capacitance in the double layer domain is similar to the behavior of the voltammogram. Substitution of TiO2 for SnO2 favors OER, leading to lower Rct values. By using the transmission line (TL) approach, it was possible to represent the behavior of Ti/Ru0,3Ti(0,7-x)SnxO2 electrodes in both potential regions (DL and OER) using a single TL, formed by one channel, where c1 is formed by r and q, the interface z is formed by a set of (rq) in parallel. The rct value diminishes as the potential and SnO2 content are increased. The different components of the circuit (Rf,Cdl, RW e L) presented similar behavior for both approaches.

Neste trabalho é apresentado o estudo da degradação eletroquímica de fenol, formaldeído e misturas de fenol-formaldeído sobre ânodos dimensionalmente estáveis (ADE). Foi utilizado um ADE comercial (composição nominal Ti/Ti0,7Ru0,3O2), em uma célula eletroquímica de compartimento único sob agitação constante. As concentrações utilizadas nas misturas de fenol-formaldeído foram similares às concentrações encontradas no efluente fornecido pela indústria de resinas fenólicas Schenectady Crios, localizada na cidade de Rio Claro, SP. No final do trabalho também foi feita a degradação eletroquímica do efluente industrial com os melhores parâmetros. O recobrimento do ADE foi caracterizado por Microscopia Eletrônica de Varredura (MEV) e análises de Energia Dispersiva de Raios X (EDX). A caracterização eletroquímica foi feita por voltametria cíclica na ausência e na presença das substâncias orgânicas sob estudo. Durantes as eletrólises, a degradação das substâncias inicialmente presentes em solução foi verificadas por análises de Cromatografia Líquida de Alta Eficiência (CLAE) e Carbono Orgânico Total (COT). Os subprodutos formados (ácido fórmico, benzoquinona, hidroquinona, catecol e resorcinol) também foram identificados e quantificados por CLAE. Cálculos de estimativa do consumo energético também foram realizados para cada eletrólise.Foram variados os seguintes parâmetros: as densidades de corrente aplicadas, o controle da temperatura das soluções durante as eletrólises, o pH e as concentrações iniciais de fenol e formaldeído contidas nas soluções.O decaimento das concentrações das substâncias orgânicas apresenta uma cinética de pseudo primeira ordem. Observou se que quanto maior a densidade de corrente aplicada, maior é a taxa de remoção de COT, porém o consumo energético também é maior. Não se obteve a mineralização total do poluente, porém foi possível atingir uma remoção de aproximadamente 90% de COT para as soluções contendo apenas formaldeído, aplicando uma densidade de corrente de 40 mA cm-2 durante 2 horas de eletrólise. Foi possível a identificação e a quantificação dos subprodutos presentes nas soluções e no efluente industrial. As degradações eletroquímicas realizadas sem o controle da temperatura das soluções obtiveram um consumo energético menor e maior remoção de COT. / In this work presents the study of electrochemical degradation of phenol, formaldehyde and phenol-formaldehyde mixtures at dimensionally stable anodes (DSA®). Commercial DSA® electrodes (nominal composition: Ti/Ti0,7Ru0,3O2), ) were employed in a single compartment electrochemical cell under constant agitation. The concentrations used for the mixtures of phenol-formaldehyde were similar to concentrations found in effluent provided by the phenolic resin producer Crios Schenectady, located in Rio Claro, São Paulo state. In the final stage of the present study, the electrochemical degradation of real industrial effluent was performed employing the best parameters observed for the simulated effluents. The oxide coating of the electrode was characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive X Ray analyses (EDX). The electrochemical characterization of the DSA® was performed using cyclic voltammetry in the absence and presence of organic substances. The degradation of the substances inicially present in solution were monitored by High Performance Liquid Chromatography (HPLC) and Total Organic Carbon (TOC) analyses. The products formed (formic acid, benzoquinone, hydroquinone, catechol and resorcinol) were also identified and quantified by HPLC. Estimates of the energy consumption were also performed for each electrolysis.The current densities applied, the concentrations of organic substance of the solution were varied during the electrochemical oxidation.The concentration decay of organic substances displayed pseudo first order kinetics of. It was observed that the higher the applied current density, the higher the TOC removal rate , but the energy consumption is higher. Total mineralization was not attained, but removals of approximately 90% of TOC were shown to be possible. It was possible the identification and quantification of products into the solutions and industrial effluents. The electrochemical degradation carried out without controlling the temperature of the solutions obtained a lower energy consumption and higher removal of TOC.