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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.
31

Comportamento dinâmico e hidrodinâmico de um reator anaeróbico híbrido (UAHB) submetido à variação de carga hidráulica horária no tratamento de esgoto sanitário / Dynamic and hydrodynamic behavior of hybrid anaerobic reactor (UAHB) subject to varying hydraulic load rate on the treatment of domestic sewage

Godinho, Jayson Pereira 13 February 2017 (has links)
CAPES / O processo de digestão anaeróbia é muito importante no tratamento dos esgotos sanitários, por ser eficiente, simples e de baixo custo de implantação, operação e manutenção. Embora o Brasil tenha à disposição processos anaeróbios consolidados, o saneamento básico ainda é deficiente no país, e a otimização de reatores anaeróbios tem o intuito de melhorar a viabilidade, efetividade e ampliação dos sistemas de tratamento dos esgotos sanitários. O objetivo deste projeto foi avaliar o desempenho através do comportamento dinâmico e hidrodinâmico de reator anaeróbio híbrido (UAHB), com variação do tempo de detenção hidráulica (TDH) de 4 a 12 h e da DQO (amostras brutas) de 250 a 1250 mgO2L-1. O reator, com volume útil de 22,1 L, foi operado com meio suporte de anéis corrugados de Policloreto de Polivinila (PVC) e mantido a temperatura ambiente, sendo o afluente de alimentação, sintético simulando o esgoto sanitário. Foram analisados os parâmetros físico-químicos: temperatura do líquido e do ar, pH, alcalinidade total (AT), alcalinidade a bicarbonato (AB), ácidos voláteis (AV), demanda química de oxigênio (DQO), demanda bioquímica de oxigênio (DBO520), Turbidez, Sólidos Totais (ST), Sólidos Suspensos Totais (SST), nitrogênio total kjeldahl (N-NTK), nitrogênio amoniacal (Namon), nitrito(N-NO2-), nitrato (N-NO3-) e fósforo total (P). Foi avaliado o comportamento hidrodinâmico e verificada a existência de anomalias hidráulicas, pela técnica de estímulo-resposta tipo pulso com injeção do traçador eosina Y. Ao final dos experimentos, foi realizada a análise estatística para encontrar a condição operacional ótima, bem como os modelos estatísticos para validação dos experimentos. Em todas as condições operacionais foi possível observar que o reator UAHB entrou em equilíbrio dinâmico aparente (EEDA) com produção de alcalinidade para neutralizar os ácidos voláteis produzidos no processo de acidogênese e acetogênese da digestão anaeróbia. O aumento da carga orgânica volumétrica acarretou no aumento das eficiências de remoção em DQO (amostras brutas e filtradas), DBO520 e Turbidez, mas reduziu as remoções de Sólidos Totais e Sólidos Suspensos Totais. A diminuição do TDH reduziu as eficiências de remoção dos parâmetros DQO (amostras brutas e filtradas), DBO520, Sólidos Totais, Sólidos Suspensos Totais e Turbidez. Em relação à hidrodinâmica, em todas as condições operacionais foi observado o efeito de cauda longa, o regime de escoamento no interior do reator UAHB foi classificado como de tanques de mistura completa em série (NCSTR). Foi verificada a presença de zonas mortas no reator, a eficiência hidráulica foi em média 65% para as três condições e não foi possível observar a presença de curtos-circuitos para os três TDH testados. Pela análise estatística do delineamento composto central rotativo (DCCR), a condição ótima de operação para o reator foi para o TDH 12 h e DQO (amostras brutas) 553 mgO2.L-1. / The anaerobic digestion process is very important in the treatment of sewage, as it is an efficient, simple process and low cost of implementation, operation and maintenance. Although Brazil has provided consolidated anaerobic processes, sanitation is still poor in the country, and the optimization of anaerobic reactors aims to improve the viability, effectiveness and expansion of treatment systems for sewage. The aim of this research project is to evaluate the reactor's performance through dynamic and hydrodynamic behavior of hybrid anaerobic reactor (UAHB) with a range of hydraulic retention time (HRT) of 4 to 12 hours and COD (gross samples) 250 - 1250 mgO2L -1. The reactor, with a volume of 22.1 L was operated with support means corrugated rings of Polyvinyl chloride (PVC) and kept at room temperature, the influent feed, simulating the synthetic wastewater. the physicochemical parameters were analyzed: temperature of the liquid and air, pH, total alkalinity (TA), bicarbonate alkalinity (BA), volatile acids (VA), chemical oxygen demand (COD), biochemical oxygen demand (BOD ), Turbidity, Total Solids (TS), total suspended solids (TSS), nitrogen Total Kjeldahl (NTK-N), ammonia nitrogen (amon-N), nitrite (NO2-N), nitrate (NO3-N) and Total phosphorus (P). It evaluated the hydrodynamic behavior and the determination of hydraulic anomalies, the stimulus-response pulse technique with injection of the tracer eosin Y. At the end of the experiments, statistical analysis was performed to find the optimal operating condition as well as the statistical models for validation experiments. In all operating conditions it was observed that the UAHB Reactor became apparent dynamic equilibrium (ADE) with alkalinity production to neutralize the volatile acids produced in acetogenesis process of anaerobic digestion. The increased of organic loading rate resulted in increased efficiencies in the removal of COD (gross and filtered samples), BOD and Turbidity, but reduced removals of Total Solids and Total Suspended Solids. The decrease in HRT reduced the removal efficiencies of COD parameters (grosss and filtered samples), BOD, Total Solids, Total Suspended Solids and Turbidity. Regarding the hydrodynamic in all operating conditions was observed long tail effect, the flow regime inside the reactor UAHB was rated as complete mixing tanks in series (N-CSTR). The presence of dead zones in the reactor was checked, the hydraulic efficiency was averaged 65% for the three conditions and it was not possible to observe the presence of short circuits for the three HRT tested. For the statistical analysis of the central rotary compound design (CRCD), the optimum operating condition for the reactor was to HRT 12 h and COD (gross samples) 553 mgCOD.L-1.
32

Comportamento dinâmico e hidrodinâmico de reator anaeróbio híbrido / Dynamic and hydrodynamic behavior of hybrid anaerobic reactor (UAHB) subject to varying hydraulic load rate on the treatment of domestic sewage

Godinho, Jayson Pereira 13 February 2017 (has links)
CAPES / O processo de digestão anaeróbia é muito importante no tratamento dos esgotos sanitários, por ser eficiente, simples e de baixo custo de implantação, operação e manutenção. Embora o Brasil tenha à disposição processos anaeróbios consolidados, o saneamento básico ainda é deficiente no país, e a otimização de reatores anaeróbios tem o intuito de melhorar a viabilidade, efetividade e ampliação dos sistemas de tratamento dos esgotos sanitários. O objetivo deste projeto foi avaliar o desempenho através do comportamento dinâmico e hidrodinâmico de reator anaeróbio híbrido (UAHB), com variação do tempo de detenção hidráulica (TDH) de 4 a 12 h e da DQO (amostras brutas) de 250 a 1250 mgO2L-1. O reator, com volume útil de 22,1 L, foi operado com meio suporte de anéis corrugados de Policloreto de Polivinila (PVC) e mantido a temperatura ambiente, sendo o afluente de alimentação, sintético simulando o esgoto sanitário. Foram analisados os parâmetros físico-químicos: temperatura do líquido e do ar, pH, alcalinidade total (AT), alcalinidade a bicarbonato (AB), ácidos voláteis (AV), demanda química de oxigênio (DQO), demanda bioquímica de oxigênio (DBO520), Turbidez, Sólidos Totais (ST), Sólidos Suspensos Totais (SST), nitrogênio total kjeldahl (N-NTK), nitrogênio amoniacal (Namon), nitrito(N-NO2-), nitrato (N-NO3-) e fósforo total (P). Foi avaliado o comportamento hidrodinâmico e verificada a existência de anomalias hidráulicas, pela técnica de estímulo-resposta tipo pulso com injeção do traçador eosina Y. Ao final dos experimentos, foi realizada a análise estatística para encontrar a condição operacional ótima, bem como os modelos estatísticos para validação dos experimentos. Em todas as condições operacionais foi possível observar que o reator UAHB entrou em equilíbrio dinâmico aparente (EEDA) com produção de alcalinidade para neutralizar os ácidos voláteis produzidos no processo de acidogênese e acetogênese da digestão anaeróbia. O aumento da carga orgânica volumétrica acarretou no aumento das eficiências de remoção em DQO (amostras brutas e filtradas), DBO520 e Turbidez, mas reduziu as remoções de Sólidos Totais e Sólidos Suspensos Totais. A diminuição do TDH reduziu as eficiências de remoção dos parâmetros DQO (amostras brutas e filtradas), DBO520, Sólidos Totais, Sólidos Suspensos Totais e Turbidez. Em relação à hidrodinâmica, em todas as condições operacionais foi observado o efeito de cauda longa, o regime de escoamento no interior do reator UAHB foi classificado como de tanques de mistura completa em série (NCSTR). Foi verificada a presença de zonas mortas no reator, a eficiência hidráulica foi em média 65% para as três condições e não foi possível observar a presença de curtos-circuitos para os três TDH testados. Pela análise estatística do delineamento composto central rotativo (DCCR), a condição ótima de operação para o reator foi para o TDH 12 h e DQO (amostras brutas) 553 mgO2.L-1. / The anaerobic digestion process is very important in the treatment of sewage, as it is an efficient, simple process and low cost of implementation, operation and maintenance. Although Brazil has provided consolidated anaerobic processes, sanitation is still poor in the country, and the optimization of anaerobic reactors aims to improve the viability, effectiveness and expansion of treatment systems for sewage. The aim of this research project is to evaluate the reactor's performance through dynamic and hydrodynamic behavior of hybrid anaerobic reactor (UAHB) with a range of hydraulic retention time (HRT) of 4 to 12 hours and COD (gross samples) 250 - 1250 mgO2L -1. The reactor, with a volume of 22.1 L was operated with support means corrugated rings of Polyvinyl chloride (PVC) and kept at room temperature, the influent feed, simulating the synthetic wastewater. the physicochemical parameters were analyzed: temperature of the liquid and air, pH, total alkalinity (TA), bicarbonate alkalinity (BA), volatile acids (VA), chemical oxygen demand (COD), biochemical oxygen demand (BOD ), Turbidity, Total Solids (TS), total suspended solids (TSS), nitrogen Total Kjeldahl (NTK-N), ammonia nitrogen (amon-N), nitrite (NO2-N), nitrate (NO3-N) and Total phosphorus (P). It evaluated the hydrodynamic behavior and the determination of hydraulic anomalies, the stimulus-response pulse technique with injection of the tracer eosin Y. At the end of the experiments, statistical analysis was performed to find the optimal operating condition as well as the statistical models for validation experiments. In all operating conditions it was observed that the UAHB Reactor became apparent dynamic equilibrium (ADE) with alkalinity production to neutralize the volatile acids produced in acetogenesis process of anaerobic digestion. The increased of organic loading rate resulted in increased efficiencies in the removal of COD (gross and filtered samples), BOD and Turbidity, but reduced removals of Total Solids and Total Suspended Solids. The decrease in HRT reduced the removal efficiencies of COD parameters (grosss and filtered samples), BOD, Total Solids, Total Suspended Solids and Turbidity. Regarding the hydrodynamic in all operating conditions was observed long tail effect, the flow regime inside the reactor UAHB was rated as complete mixing tanks in series (N-CSTR). The presence of dead zones in the reactor was checked, the hydraulic efficiency was averaged 65% for the three conditions and it was not possible to observe the presence of short circuits for the three HRT tested. For the statistical analysis of the central rotary compound design (CRCD), the optimum operating condition for the reactor was to HRT 12 h and COD (gross samples) 553 mgCOD.L-1.
33

Surveillance et diagnostic des machines synchrones à aimants permanents : détection des courts-circuits par suivi paramétrique / Monitoring and diagnosis of permanent magnets synchronous motor : Detection of short-circuits by parameter monitoring

Khov, Makara 17 December 2009 (has links)
Ce travail de thèse traite du problème de surveillance en ligne de défaillances électriques dans les entrainements électriques à base de machines synchrones à aimants permanents (MSAP) par une méthode de suivi paramétrique. Les défauts de court-circuit entre spires au stator sont souvent critiques et doivent être détectés au plus tôt avec un bon taux de confiance afin d’informer un système superviseur de la présence d’une défaillance pour limiter les risques encourues par l’environnement matériel et humain situé autour de la machine en défaut. La méthode que nous proposons de mettre en œuvre pour la détection des courts-circuits statoriques est basée des techniques d’identifications récursives. Nous proposons d’identifier en ligne les paramètres d’un modèle diphasé électrique de l’actionneur synchrone et d’analyser les variations des paramètres identifiées lors de l’apparition d’un défaut. Pour assurer les performances des méthodes d’identification, il est souvent nécessaire de disposer d’un signal d’excitation additionnel pour assurer les bonnes performances des algorithmes. Ces signaux peuvent cependant perturber le fonctionnement normal de la machine et entrainer des pertes additionnelles. Dans ce contexte, nous proposons une approche par identification faisant appel à un modèle diphasé spécifique appelé « le repère de Park à courants orientés ». Ce repère permet, tout en réduisant la complexité du problème d’identification, d’obtenir des propriétés d’auto-excitation intéressantes et donc d’éviter l’utilisation d’une excitation additionnelle. Des simulations sont menées à l’aide d’un modèle fin de la machine permettant de reproduire des situations de défaillances de manière virtuelle et d’éprouver l’efficacité des algorithmes dans ces situations dégradées. Cette machine, pouvant fonctionner en générateur ou en moteur, est intégrée dans un environnement complet, incluant le cas échéant une alimentation, une charge mécanique et éventuellement une commande, ce qui permet également de tester les algorithmes pour des fonctionnements en boucle ouverte et en boucle fermée. Les résultats présentés permettent de valider les techniques proposées et montrent qu’elles permettent d’extraire automatiquement, à partir des variations des paramètres identifiés, un indicateur de défaut. Des résultats expérimentaux sont également présentés en fonctionnement générateur sur une machine spécialement re-bobinée pour permettre la réalisation de défaut statoriques. Les algorithmes sont implantés sur une cible de calcul numérique afin de démontrer la faisabilité temps réelle de la détection / This work deals with the on-line monitoring of electrical faults in permanent magnet synchronous machine (PMSM) by parameter monitoring method. The inter-turns short-circuits faults in stator are often critical and have to be detected as early as possible with a high confidence rate to inform the supervisor system of the fault presence in order to limit the risk for the material and human environment. The proposed method is focus on the detection of short-circuits in stator and based on recursive identification technique. The on-line parameter identification uses an electrical diphase model of the PMSM and the analysis of the estimated parameter variations is performed to detect the presence of stator faults. In a general way, to ensure the performance of identification algorithms, it is necessary to have additional excitation signals. Consequently, those signals could disturb the normal operation of the drive. To overcome this problem, a specific diphase model in currents oriented Park reference frame is introduced for identification process. By reducing the complexity of identification problem, this reference frame provides an interesting auto-excitation property that leads to avoid the utilisation of additional excitation signals. The simulations are performed using an accurate model of PMSM that allows reproducing the failure situation and prove the efficiency of algorithms in degraded situations. This machine, operating as generator or motor, is integrated in a complete environment, included a power supply, mechanical load and control process. The detection scheme is then tested in open and closed loop operation. The results obtained from the simulation process underline the ability of the proposed technique to detect a stator fault occurrence and show that a fault indicator can be extracted automatically from the variation of estimated parameters. Experimental results are also achieved. A PMSM, with a specific winding including additional connexion points for stator short-circuit realisation is used. The algorithms are implemented in a numerical calculator in order to demonstrate the feasibility of the real-time faults detection for a generator operation mode
34

Contribution à l’étude de la robustesse des MOSFET-SiC haute tension : Dérive de la tension de seuil et tenue aux courts-circuits / High Voltage SiC MOSFET Robustness study : Threshold voltage shift and short-circuit behavior

Molin, Quentin 14 December 2018 (has links)
Ce manuscrit est une contribution à l’étude de la fiabilité et de la robustesse des composants MOSFET sur carbure de silicium, matériau semi-conducteur grand gap qui possède des caractéristiques bien meilleures que le silicium. Ces nouveaux interrupteurs de puissances permettent d’obtenir entre autres propriétés remarquables, des fréquences de commutations et des tenues en tension plus élevées dans les systèmes de conversions de puissance. Ils sont particulièrement mis en avant depuis un peu plus d’une dizaine d’années pour les gains en performances, diminution des tailles et poids qu’ils apportent à certaines topologies de convertisseurs pour les réseaux haute tension à courant continu. Puis sont répertoriés les principaux mécanismes de défaillances de ces MOSFET SiC induits par la faiblesse de la grille. Toutes les mesures nécessaires au suivi des paramètres clés lors des prochains vieillissements sont présentées. Les résultats de nos tests sur l’instabilité de la tension de seuil sont aussi détaillés et un modèle empirique pour valider le comportement de relaxation observé est proposé. Celui-ci nous aidera par la suite à établir un protocole de mesure rigoureux de la tension de seuil. Les tests expérimentaux et résultats de vieillissement en statique et dynamique sur les composants 1,7 kV vont permettre de se rendre compte de l’importance de la dérive de la tension de seuil sur 1000 h. Dans le cas d’un vieillissement statique, il y a environ 7 % de dérive positive du VTH et un pourcentage équivalent pour les tests dynamiques. Des analyses supplémentaires (C-V et pompage de charge) sur l’oxyde de grille en cours de vieillissement sont proposées pour une meilleure compréhension des mécanismes mis en jeu dans la dégradation de l’oxyde. Enfin, les derniers tests présentés seront focalisés sur le comportement en court-circuit et courts-circuits répétitifs des mêmes composants. Avec une énergie critique évaluée autour de 1,5 J nos tests sur les MOSFET 1,7 kV montrent les limites de la robustesse de ces composants, avec une tenue en court-circuit bien inférieure à 10 µs et une incapacité à résister à plus de 150 courts-circuits successifs. L’influence de la tension entre drain et source y est notamment étudiée, et montre que l’énergie critique supportée par le composant diminue avec l’augmentation de cette tension. / This manuscript is a contribution to reliability and robustness study of MOSFET components on silicon carbide “SiC”, wide band gap semiconductor with better characteristics compared to silicon “Si” material. Those new power switches can provide better switching frequencies or voltage withstanding for example in power converter. SiC MOSFET are the results of approximately 10 years of research and development and can provide increased performances and weight to some converter topology for high voltage direct current networks. Others power switches available are still introduced and an introduction to reliability is explaining why such work on this new power switches is important. Transition from Si technologies to SiC ones require a lot of work regarding its robustness. Before showing reliability and robustness results is presented I give a lot of details regarding to the measurement and monitoring of key parameters used in the next chapters. The results of our tests on the threshold voltage instability are presented and how we validated an empirical model on this drift. This was used to propose an enhanced measurement protocol on the threshold voltage. Static and dynamic experimental results presented next will show if the voltage drift during ageing is significant or not. Further analysis is proposed to add more insight on the understanding of the oxide degradation mechanisms through C-V and charge pumping measurements. Finally, the ageing results presented on 1,7 kV SiC MOSFET are focused on the short-circuit and repetitive short-circuit behavior of the same components. Drain to source voltage influence on critical energy during this particular and stressful operation mode is studied. This time, the results are worrying.The last chapter is confidential.
35

Studie připojitelnosti výrobny / Study of Power Plant Connection to Power Network

Sýkora, Martin January 2011 (has links)
It is necessary to judge the influences of producers on the electric compounds while creating electrical energy or during the regulation of those existing. These analyses are sorted out by so called studies of connectivity. These calculations analyze the degree of connection of the producer and the standby unit during a break-down. The results of this report are several recommendations for creating such unit and succeeding steps leading to secure the stability and safety of the electric compound operation. The aim of this thesis is to discuss about software for PC solutions for static and dynamic network model, to draft power outlet into a network of generating high voltage, to complete a study of connectivity with respect to all the distortion factor, as increased voltage, inrush current at startup, flicker, harmonic currents, interference ripple, contribution to short-circuit current, reactive power control options, and demands for compensation.
36

Effects of carbon nanotubes on barrier epithelial cells via effects on lipid bilayers

Lewis, Shanta January 2013 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Carbon nanotubes (CNTs) are one of the most common nanoparticles (NP) found in workplace air. Therefore, there is a strong chance that these NP will enter the human body. They have similar physical properties to asbestos, a known toxic material, yet there is limited evidence showing that CNTs may be hazardous to human barrier epithelia. In previous studies done in our laboratory, the effects of CNTs on the barrier function in the human airway epithelial cell line (Calu-3) were measured. Measurements were done using electrophysiology, a technique which measures both transepithelial electrical resistance (TEER), a measure of monolayer integrity, and short circuit current (SCC) which is a measure of vectorial ion transport across the cell monolayer. The research findings showed that select physiologically relevant concentrations of long single-wall (SW) and multi-wall (MW) CNTs significantly decreased the stimulated SCC of the Calu-3 cells compared to untreated cultures. Calu-3 cells showed decreases in TEER when incubated for 48 hours (h) with concentrations of MWCNT ranging from 4µg/cm2 to 0.4ng/cm2 and SWCNT ranging from 4µg/cm2 to 0.04ng/cm2. The impaired cellular function, despite sustained cell viability, led us to investigate the mechanism by which the CNTs were affecting the cell membrane. We investigated the interaction of short MWCNTs with model lipid membranes using an ion channel amplifier, Planar Bilayer Workstation. Membranes were synthesized using neutral diphytanoylphosphatidylcholine (DPhPC) and negatively charged diphytanoylphosphatidylserine (DPhPS) lipids. Gramicidin A (GA), an ion channel reporter protein, was used to measure changes in ion channel conductance due to CNT exposures. Synthetic membranes exposed to CNTs allowed bursts of currents to cross the membrane when they were added to the membrane buffer system. When added to the membrane in the presence of GA, they distorted channel formation and reduced membrane stability.

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