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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

An FPGA Based MPPT and Monitoring System : suitable for a photovoltaic based microgrid

Zheng, Rongpeng January 2019 (has links)
Microgrids containing photovoltaic (PV) cells and wind power gain more and more interest. These microgrids may work in stand-alone mode ("islanding") or be conncted to the main grid. In both modes of operation, power quality must be monitored and controlled. This report focuses on microgrids and aims to implement a monitoring system based on FPGA. In the monitoring system, two applications can be achieved, firstly a PAS-MPPT algorithm in a DC-DC boost converter to improve the maximun power point tracking of a PV unit, and secondly a detection and switching system of the grid mode - stand-alone or connected to the main grid. Simulation results prove the Verilog programs in FPGA are suitable to be used in microgrids.
262

Materiais híbridos baseados em compostos lamelares e moléculas redox ativas / \"Hybrid Materials Based on Layered Compounds and Active Redox Molecules\"

Bordonal, Ana Cláudia 27 October 2016 (has links)
Os Hidróxidos Duplos Lamelares (HDL) constituem uma classe de materiais que apresentam estrutura lamelar, consistindo de camadas positivamente carregadas de um hidróxido duplo, intercaladas com ânions hidratados no domínio interlamelar. Estes materiais têm recebido bastante atenção nos últimos tempos, devido ao baixo custo e relativa simplicidade de preparação, a possibilidade de combinação de uma variedade de cátions e ânions, aliados às propriedades que os HDL podem apresentar como: propriedades ácidas e básicas, \"efeito memória\", elevada área superficial, etc. Os HDL também podem ser utilizados em combinação com outros materiais, como por exemplo, óxido de grafeno, formando compósitos, com a finalidade melhorar as propriedades destes materiais. Podem ainda serem utilizados para a preparação de outros compósitos e/ou réplicas de carbono, por tratamento térmico de um HDL intercalado com um monômero, por exemplo, 4-vinil benzeno sulfonato (VBS), que pode ser polimerizado \"in situ\" e posteriormente carbonizado produzindo a réplica de carbono. A utilização dos materiais descritos anteriormente como suporte para imobilização de enzimas pode proporcionar uma plataforma alternativa para construção de dispositivos biossensores. O objetivo geral do trabalho foi a preparação e caracterização de materiais como HDL, Compósitos e/ou Réplicas de Carbono derivadas de HDL ou compósitos de HDL/ óxido de grafeno, como suporte da enzima Glicose Oxidase, estudando suas propriedades eletroquímicas, visando as potenciais aplicações destes materiais como biossensores. Para isto, foram preparados e caracterizados HDL de Mg-Al e Zn-Al intercalados com o ânion carbonato, pelo método de coprecipitação a pH variável; compósitos e/ou réplicas de carbono derivadas de um HDL precursor de Mg-Al-VBS, preparados, por coprecipitação a pH constante e compósitos de Mg-Al/óxido de grafeno que também foram preparados por coprecipitação a pH constante. Estes materiais foram utilizados na imobilização da enzima Glicose Oxidase (GOx), em eletrodos modificados e foi realizado o estudo eletroquímico dos mesmos e de suas potenciais aplicações. Foi possível observar que os HDL de Mg-Al-CO3, Zn-Al-CO3, Mg-Al-VBS e o compósito Mg-Al/óxido de grafeno exibiram boa cristalinidade, estabilidade térmica, e outras características como porosidade e superfícies positivamente carregadas, viabilizando a xiii utilização dos mesmos para a imobilização e estudo eletroquímico da enzima Glicose Oxidase. O estudo eletroquímico dos eletrodos modificados com estes materiais e a enzima Glicose Oxidase mostrou que os mesmos apresentam boa resposta catalítica frente ao substrato glicose e a importância destes materiais na atividade desta enzima. Os eletrodos modificados apresentaram boa sensibilidade, estabilidade à longo prazo e reprodutibilidade do método, podendo estes serem aplicados para a preparação de biossensores. / Layered Double Hydroxides (LDH) constitute a class of materials with a layered structure consisting of positively charged layers of a double hydroxide and hydrated anions intercalated in the interlayer domain. These materials have received much attention lately because they offer many advantages: they display acidic and basic properties, \"memory effect\", and high surface area; are inexpensive and easy to prepare; and can combine with a variety of cations and anions. Combination of LDH with materials like graphene oxide affords composites with improved properties as compared to the starting organic component. Heat treatment of LDH intercalated with a monomer such as 4-vinyl-benzene sulfonate (VBS), followed by \"in situ\" polymerization and carbonization, produces composites and/or carbon replica. The materials described above could be applied as support to immobilize enzymes and may provide an alternative platform for biosensor devices. In this study, we aimed to prepare and characterize LDH, composites and/or carbon replica derived from LDH, and LDH/graphene oxide composites and support glucose oxidase enzyme (GOx) on these matrixes. We investigated the electrochemical properties of the resulting materials and evaluated their potential application as biosensors. More specifically, we prepared and characterized Mg-Al and Zn-Al LDH systems intercalated with carbonate ion by the coprecipitation method; composites and/or carbon replica derived from a precursor LDH Mg-Al-VBS by coprecipitation at constant pH; and Mg-Al/graphene composites by coprecipitation at constant pH. We used these materials to immobilize GOx on modified electrodes and assessed the electrochemical activity and potential application of the immobilized enzyme as biosensor. Mg-Al-CO3, Zn-Al-CO3, Mg-Al-VBS LDH and Mg-Al/graphene oxide composite were crystalline, thermally stable, and porous and exhibited positively charged surface, which favored immobilization and electrochemical investigation of the GOx enzyme. The modified electrodes displayed good catalytic response to glucose, as substrate, and improved the activity of the enzyme as compared to GOx alone. Additionally, the modified electrodes were sensitive, stable, and reproducible, paving the way for their use in the design of biosensors.
263

Développement de biocapteurs ampérométriques pour la détermination de l’activité de la transcétolase et pour la détection d’inhibiteurs de cette enzyme / Development of amperometric biosensors for the determination of the activity of transketolase and for the detection of inhibitors of this enzyme

Touisni, Nadia 13 December 2013 (has links)
Depuis peu, des travaux ont montré que chez l’Homme, la transcétolase (TK, EC 2.2.1.1.) dont le cofacteur est la thiamine diphosphate (forme active de la vitamine B1), est une enzyme impliquée dans de nombreuses maladies telles que, le diabète, certains cancers, ou encore des maladies neurologiques, comme le syndrome de Wernicke-Korsakoff et la maladie d’Alzheimer. Pour des applications thérapeutiques, des inhibiteurs spécifiques de cette enzyme sont actuellement conçus et synthétisés dans les milieux académiques et industriels. Afin de déterminer l’activité de la TK (dans un but de diagnostic) d’une part, et de détecter des inhibiteurs potentiels de cette enzyme (dans un but thérapeutique) d’autre part, il est nécessaire de disposer de tests alliant rapidité, sensibilité et faible coût. Nous avons envisagé d’utiliser des biocapteurs ampérométriques qui combinent l’ensemble de ces avantages, et qui, de plus, n’ont jamais été mis en oeuvre avec la TK. Pour la détermination de l’activité des TK d’E. coli et humaine libres en solution, nous avons tout d’abord élaboré un premier biocapteur à galactose oxydase (GAOx, EC 1.1.3.9), dans lequel cette enzyme est immobilisée sur la laponite. Puis, dans le but de detecter des inhibiteurs de la TK, avec un système réutilisable, nous avons developpé un biocapteur à GAOx-TK d’E. coli, les deux enzymes étant co-immobilisées à la surface de l’électrode. Pour cela la TK a été immobilisée dans des Hydroxydes Doubles Lamellaires (HDL). Ce biocapteur bicouche et bi-enzymatique GAOx-TK, nous a permis d’évaluer l’effet d’inhibiteurs, tels que différents analogues du cofacteur et de substrats pris comme modèles. / Some recent studies have shown that human transketolase (TK, EC 2.2.1.1.), which thiamine diphosphate (active form of vitamin B1) is the cofactor, is involved in numerous disease such as diabete, some cancers and neurodegenerative diseases as Alzheimer’s disease and Wernicke-Korsakoff syndrome. For therapeutic purposes, TK inhibitors have been designed and synthesized in both academic and industrial fields. To determine TK activity (diagnostic) on the one hand, and to detect potential inhibitors of this enzyme (therapeutic) on the other hand, it is necessary to develop fast, sensitive and low cost assays. In this context, we designed some original amperometric biosensors that combine these advantages and were never studied with TK from now. We performed a first galactose oxidase (GAOx, EC 1.1.3.9) biosensor for E. coli and human TK activities detection. For that purpose, GAOx was immobilized on laponite matrix. Then, we designed a GAOx-TK biosensor by co-immobilization of GAOX and TK on the electrode surface that enabled the detection TK inhibitors with a reusable system. Thence, TK was immobilized in Layered Double Hydroxides (HDL). This bilayer and bi-enzymic biosensors, allowed us to determine the inhibitor potencies of several cofactors and substrates analogues as model compounds.
264

Etude physico-chimique d'oxydes mixtes issus d'hydroxydes doubles lamellaires. Application à la synthèse de nanofilaments de carbone.

Dussault, Laurent 13 December 2005 (has links) (PDF)
Les Hydroxydes Doubles Lamellaires (HDL) présentent de nombreux domaines d'application en rapport avec leur structure lamellaire et la diversité de leur de composition. Ce travail souligne les potentialités des HDL lorsqu'ils sont utilisés comme précurseurs d'oxydes mixtes pouvant intervenir en catalyse hétérogène acido-basique ou d'oxydo-réduction.<br />La première partie du mémoire concerne l'étude d'une série d'oxydes à base de nickel, cuivre, magnésium et aluminium, obtenus par calcination des HDL précurseurs à 450°C. La caractérisation structurale et l'étude de l'acido-basicité des oxydes mixtes en fonction de leur composition ont été réalisées. Elles s'appuient sur l'utilisation complémentaire de différentes méthodes analytiques physico-chimiques donnant accès à des informations concernant à la fois la structure, la composition et la morphologie des cristaux obtenus(DRX, ATG, analyse chimique, SPX...), ou permettant la caractérisation de leurs propriétés acido-basiques (adsorption de molécules sondes suivie par microcalorimétrie et SPX).<br />La seconde partie du travail est consacrée à l'utilisation des oxydes mixtes obtenus après calcination à 800°C pour la synthèse de nanofilaments de carbone à partir de la décomposition catalytique du méthane. Après une étude détaillée des oxydes mixtes, les nanofilaments produits ont été caractérisés à l'aide de différentes techniques, notamment la microscopie électronique à transmission. Les données physico-chimiques obtenues ont mis en évidence les relations entre les caractéristiques du catalyseur (composition, mode de synthèse, propriétés...) et le type des nanofilaments (tubes, fibres) obtenus.
265

Elaboration et caractérisation de matrices hydroxydes doubles lamellaires macroporeuses

Géraud, Erwan 13 December 2006 (has links) (PDF)
Dans ce travail, la structuration de phases HDL en matrices macroporeuses a été réalisée grâce à l'utilisation d'un arrangement ordonné de sphères comme empreinte sacrificielle. Les phases HDL sont obtenues en précipitant les sels métalliques adsorbés à la surface de billes de PS ordonnées, en présence de soude. Un réseau 3D poreux est finalement obtenu soit par dissolution ou bien calcination de l'empreinte. Ces matrices HDL macroporeuses conservent leur propriétés d'intercalation et leur richesse de composition. La macroporosité ordonnée est maintenue lors de la décomposition thermique des phases HDL en oxydes. Cette macroporosité présente dans les phases HDL permet l'amélioration de l'adsorption, évaluée sur l'Orange II, et la photodégradation d'un pesticide par des anions décatungstate immobilisés. A partir de ces matrices macroporeuses, des carbones à porosité hiérarchisée ont été élaborés
266

High-Level Parallel Programming of Computation-Intensive Algorithms on Fine-Grained Architecture

Cheema, Fahad Islam January 2009 (has links)
<p>Computation-intensive algorithms require a high level of parallelism and programmability, which </p><p>make them good candidate for hardware acceleration using fine-grained processor arrays. Using </p><p>Hardware Description Language (HDL), it is very difficult to design and manage fine-grained </p><p>processing units and therefore High-Level Language (HLL) is a preferred alternative. </p><p> </p><p>This thesis analyzes HLL programming of fine-grained architecture in terms of achieved </p><p>performance and resource consumption. In a case study, highly computation-intensive algorithms </p><p>(interpolation kernels) are implemented on fine-grained architecture (FPGA) using a high-level </p><p>language (Mitrion-C). Mitrion Virtual Processor (MVP) is extracted as an application-specific </p><p>fine-grain processor array, and the Mitrion development environment translates high-level design </p><p>to hardware description (HDL). </p><p> </p><p>Performance requirements, parallelism possibilities/limitations and resource requirement for </p><p>parallelism vary from algorithm to algorithm as well as by hardware platform. By considering </p><p>parallelism at different levels, we can adjust the parallelism according to available hardware </p><p>resources and can achieve better adjustment of different tradeoffs like gates-performance and </p><p>memory-performance tradeoffs. This thesis proposes different design approaches to adjust </p><p>parallelism at different design levels. For interpolation kernels, different parallelism levels and </p><p>design variants are proposed, which can be mixed to get a well-tuned application and resource </p><p>specific design.</p>
267

Factors genètics i ambientals i les seves interaccions com a determinants de l'efecte protector de la paraoxanasa1 en la malaltia cardiovascular

Tomás Mestres, Marta 12 February 2003 (has links)
La present tesi avalua els efectes de certs factors ambientals sobre la paraoxonasa1 (PON1), enzim antioxidant, possiblement protector enfront les malalties cardiovasculars, a través de dos estudis d'intervenció i un de transversal. En primer lloc, el tractament amb simvastatina dels pacients amb hipercolesterolèmia familiar, que presentaven una activitat paraoxonasa baixa, s'associava a un increment de l'activitat fins a valors similars als d'individus normolipèmics, independentment dels polimorfismes PON1-55 o PON1-192. En segon lloc, l'entrenament físic s'associava a un augment de l'activitat paraoxonasa en els individus QQ i una disminució de la mateixa en els portadors de l'al·lel R pel polimorfisme PON1-192. L'increment de l'activitat paraoxonasa immediatament després de l'exercici físic agut era seguit per una disminució subseqüent de l'activitat. La recuperació dels nivells basals d'activitat paraoxonasa a les 24h de l'exercici físic agut es donava en els individus QQ independentment del seu estat d'entrenament, i en els individus portadors de l'al·lel R només quan estan entrenats. En tercer lloc, el consum elevat d'àcid oleic comportava un augment de la concentració de c-HDL i de l'activitat paraoxonasa en els homes portadors dels genotips QR i RR del polimorfisme PON1-192, respectivament.Paraules claus: paraoxonasa, PON1, genotips, simvastatina, hipercolesterolèmia familiar, interacció gen-dieta, lipoproteïna d'alta densitat (HDL), exercici físic agut, entrenament físic, estrès oxidatiu, àcid oleic, oli d'oliva, peròxids lipídics, malaltia cardiovascular. / The present thesis evaluates some environmental factor effects on paraoxonase1 (PON1), an possibly protective against cardiovascular disease antioxidant enzyme, through two intervention studies and a cross-sectional one. First, treatment with simvastatin of the familial hypercholesterolemic patients, which had low paraoxonase activity, was associated with an increase in the activity to values similar to the normolipemic ones, regardless of the PON1-55 or PON1-192 polymorphisms. Second, Regular exercise was associated with an increase in PON1 activity in QQ subjects and with a decrease in R carriers. Increased PON1 activity immediately after a bout of exercise was subsequently followed by a decrease of activity. The recovery of the basal PON1 activity levels at 24 h was found in QQ subjects regardless of their training status and in trained R carriers, but not in untrained R carriers. Third, high oleic acid intake was associated with increased HDL cholesterol and PON1 activity levels only in men who were QR and RR of the PON1-192 polymorphism, respectively.
268

High-Level Parallel Programming of Computation-Intensive Algorithms on Fine-Grained Architecture

Cheema, Fahad Islam January 2009 (has links)
Computation-intensive algorithms require a high level of parallelism and programmability, which make them good candidate for hardware acceleration using fine-grained processor arrays. Using Hardware Description Language (HDL), it is very difficult to design and manage fine-grained processing units and therefore High-Level Language (HLL) is a preferred alternative. This thesis analyzes HLL programming of fine-grained architecture in terms of achieved performance and resource consumption. In a case study, highly computation-intensive algorithms (interpolation kernels) are implemented on fine-grained architecture (FPGA) using a high-level language (Mitrion-C). Mitrion Virtual Processor (MVP) is extracted as an application-specific fine-grain processor array, and the Mitrion development environment translates high-level design to hardware description (HDL). Performance requirements, parallelism possibilities/limitations and resource requirement for parallelism vary from algorithm to algorithm as well as by hardware platform. By considering parallelism at different levels, we can adjust the parallelism according to available hardware resources and can achieve better adjustment of different tradeoffs like gates-performance and memory-performance tradeoffs. This thesis proposes different design approaches to adjust parallelism at different design levels. For interpolation kernels, different parallelism levels and design variants are proposed, which can be mixed to get a well-tuned application and resource specific design.
269

Interopérabilité en émulation et prototypage matériel

Blampey, A. 06 December 2006 (has links) (PDF)
Ce travail de thèse introduit un nouveau concept dans la vérification des circuits au niveau RTL : l'interopérabilité entre simulateurs HDL, émulateurs matériel et plateformes de prototypage. Cela permet de bénéficier, à la fois de l'excellente vitesse d'exécution des plateformes de prototypage et des capacités de déboguage, d'observabilité et contrôlabilité offertes par les émulateurs matériel et simulateurs HDL. L'idée principale de l'interopérabilité consiste en la réalisation des tests sur une plateforme de prototypage rapide tout en réalisant périodiquement des sauvegardes de l'état du circuit. Lorsqu'une erreur apparait, le déboguage est réalisé, soit un émulateur rapide, soit un simulateur HDL économique : le test est alors rejoué à partir de la dernière sauvegarde d'état réalisée avant l'instant d'apparition du problème. Enfin, cette thèse présente un flot de prototypage, validé sur un circuit industriel STM HLS25, permettant d'intégrer l'interopérabilité comme une fonctionnalité du circuit
270

Elaboracao e avaliacao da eficacia do sistema de pontos de um instrumento de orientacao alimentar como ferramenta para intervencoes dieteticas em individuos hiperlipidemicos

Abreu, Edeli Simioni de. January 2003 (has links)
Doutor -- Universidade de Sao Paulo. Faculdade de Saude Publica. Departamento de Nutricao, Sao Paulo, 2003.

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