Made available in DSpace on 2014-06-11T19:29:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-12-08Bitstream added on 2014-06-13T18:59:25Z : No. of bitstreams: 1 santos_eb_me_ilha.pdf: 2249660 bytes, checksum: 0671e80475fb96ecddd11946fe401103 (MD5) / O biossólido é um composto passível de utilização agronômica, sendo fonte de nutrientes para as culturas e condicionador de solo. Neste sentido, desenvolveu-se um trabalho que teve por escopo estudar a influência da reaplicação de doses de biossólido na recuperação de atributos físicos e químicos do solo e no desenvolvimento da cultura do eucalipto e da braquiária, num Latossolo Vermelho degradado. O estudo foi realizado cinco meses após a reaplicação do biossólido, numa área em recuperação cultivada há seis anos com eucalipto e braquiária. O delineamento experimental foi em blocos casualizados com seis tratamentos e quatro repetições, sendo: Solo cultivado com eucalipto e braquiária sem adição de insumos; Solo cultivado com eucalipto e braquiária com adubação mineral; Solo cultivado com eucalipto e braquiária com reaplicação de 4,64 Mg ha-1 (base seca) de biossólido; Solo cultivado com eucalipto e braquiária com reaplicação de 9,28 Mg ha-1 (base seca) de biossólido; Solo exposto (sem qualquer cultivo ou adubação); Solo com vegetação natural de Cerrado. Estudou-se nas camadas do solo de 0,00- 0,05; 0,05-0,10; 0,10-0,20 e de 0,20-0,40 m, os atributos físicos: macroporosidade; microporosidade; porosidade total e a densidade do solo. Para os atributos químicos nas mesmas camadas os teores de: P, MO, pH, K, Ca, Mg, H+Al, SB, CTC e V%. Já para a cultura do eucalipto estudou-se a altura média de plantas e o diâmetro a altura do Peito (DAP) e na braquiária a massa fresca e seca. Verificou-se que a replicação do biossólido está recuperando o solo tanto em relação aos atributos físicos como químicos, sobretudo nas camadas mais superficiais, e que a maior dose influencia no desenvolvimento do eucalipto. Não foi constatada diferença significativa entre médias dos tratamentos para recuperação do solo da matéria... / The sludge is a compound capable of agricultural use, a source of nutrients for crops and soil conditioner. In this sense, has developed a work which objective on studying the influence of reapplication of biosolids in the recovery of physical and chemical properties of soil and the development of culture of eucalyptus and grass in a degraded Oxisol. The work was conducted five months after the biosolids re-application in a recovery area cultivated for six years under eucalyptus and pasture. The experimental design was randomized blocks with six treatments and four replications, with: Solo under eucalyptus and pasture with no added inputs, soil under eucalyptus and pasture with mineral fertilization, soil under eucalyptus and pasture with reapplication of 4.64 Mg ha-1 (on dry basis) of sludge, soil under eucalyptus and pasture with reapplication of 9.28 Mg ha-1 (on dry basis) of sludge, soil exposed (without any cultivation or fertilization), soil with Savannah vegetation. Was studied in soil layers of 0.00-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.40 m, the physical attributes: macroporosity, microporosity; porosity and soil bulk density. For the chemical in the same layers of levels: P, organic matter, pH, K, Ca,Mg, H+Al, SB, CEC and V%. As for the cultivation of eucalyptus studied the average plant height and diameter at breast height (DBH) and the grass fresh and dry. It was found that replication of the sludge is regaining ground in relation to both physical and chemical properties, especially in the surface layers, and the highest dose influences the plantations development. There was no significant difference between treatment means for soil recovery of fresh and dry grass, after reapplication of biosolids

Os resíduos de construção civil e demolição (RCD) constituem-se em um grande problema ambiental, pois representam mais de 50% do resíduo sólido gerado nos médios e grandes centros urbanos, sendo que a maior parte deste resíduo acaba tendo uma disposição final irregular. Isso causa sérios impactos ambientais como degradação das áreas de manancial e proteção permanente, proliferação de agentes transmissores de doenças, assoreamento de rios e córregos, obstrução dos sistemas de drenagem, ocupação de vias e logradouros públicos e degradação da paisagem urbana. Caso esse material seja disposto em aterros, pode reduzir drasticamente a vida útil dos mesmos. Como alternativa, usinas de reciclagem têm moído este resíduo, produzindo o RCD reciclado, ou RCD-R, que tem sido utilizado na própria construção civil. Por outro lado, a acidez do solo é um dos principais fatores capazes de reduzir o potencial produtivo dos solos brasileiros, pois provoca a diminuição da disponibilidade de nutrientes para as plantas. Além disso, solos arenosos são encontrados em quase todo o território nacional e apresentam características desfavoráveis como a baixa capacidade de retenção de água e grandes perdas de nutrientes por percolação que proporcionam baixas produtividades. Neste trabalho o RCD-R produzido pela Usina de Reciclagem de São Carlos, SP, que é dividido em dois tipos: cinza e vermelho, foi caracterizado pelas técnicas de FRX, DRX, medidas dos teores de CaO e MgO, PN e PRNT e análise granulométrica por radiação gama. Foi avaliada a utilização deste RCD-R como corretivo de acidez e condicionador para aumento da capacidade de retenção de água no solo por meio de um experimento de plantio de alfafa em um solo LVAd textura média, ácido e de baixa fertilidade com doses de 10, 20 e 40% de RCD-R, em massa. Foi avaliada a produção de matéria seca de alfafa, a fertilidade química do solo, a capacidade de retenção de água, macro e microporosidade do solo por meio das curvas características de retenção de água e por microtomografia de raios X. Concluiu-se que o RCD-R cinza neutraliza a acidez e carreia cálcio e magnésio para o solo, tendo potencial para ser utilizado como corretivo da acidez do solo e que o RCD-R vermelho aumenta a capacidade de retenção de água, tendo potencial para ser utilizado como condicionador de solo. Devido às doses necessárias, a utilização desses RCD-R mostrou-se interessante em áreas como jardinagem, na composição de substratos para plantio em vasos ou na preparação de covas para culturas permanentes / Construction and demolition residues (CDR) are an important environmental issue because they represent more than 50% of solid waste produced in medium and big cities, where most of this waste ends up having an irregular final disposition. This causes serious environmental impacts as the degradation of water sources and permanent protection areas, proliferation of disease agents, clogging of drainage systems, occupation of public roads and degradation of the urban landscape. Moreover, if such material is disposed in landfills it can drastically reduce their lifetime. Alternatively, CDR has been processed by mills and used as recycled material (RCDR) in the construction sector. Soil acidity is one of the main aspects that reduce the productive potential of the Brazilian soils because it causes a decreasing availability of nutrients for plants. Furthermore, sandy soils are very common in Brazil and have unfavorable characteristics such as low water retention capacity and high nutrient losses by leaching, providing, generally, low crop yields. In this work, the RCDR produced by the Recycling Plant of São Carlos, SP, which is divided into gray and red materials, were mineralogically, physically and chemically characterized. It was evaluated the use of the RCDR materials as a corrective for the soil acidity and as a conditioner to increase the soil water retention capacity by means of an experimental planting trial with alfalfa in a LVAd acidic and low fertility soil, at 10, 20 and 40% (m/m) doses of RCDR. Parameters evaluated were dry matter production, the soil chemical fertility, water holding capacity and macro and microporosity of soil samples from the water-potential characteristic curves and X-ray microtomography. It was concluded that the gray RCDR neutralizes the acidity and adds calcium and magnesium to the soil, having the potential to be used as corrective of soil acidity and the red RCDR increases the soil water retention capacity, presenting a potential to be used as soil conditioner. Due to the doses used in the experiment, the RCDR proved to be interesting for use in gardening, substrate composition for planting in pots or in the preparation of pits for permanent crops

Made available in DSpace on 2017-07-10T17:48:22Z (GMT). No. of bitstreams: 1 Francieli_Batista_Silva.pdf: 721871 bytes, checksum: ef68182f64f3e618bb3a8151fe1ba5e5 (MD5) Previous issue date: 2011-03-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Two experiments were conducted to evaluate ways to use of oat hay, grazing and cutting. The first test evaluated the structural characteristics, chemical composition and digestibility in vitro dry matter (DM) and crude protein (DIVPB) of oat (Avena sativa IPR 126), under different management systems: grazing, cutting and free growth in two heights: 15 and 20 cm in three periods (July, August and September) with a mean interval of 25 days. In the management free growth, the samples were removed at the same intervals and cutting grazing and the same heights (15 and 20 cm). The design was a block design in a 3x2x3 factorial with three tillage systems, two heights and third assessment periods, with three replications. The results show that the dry matter production, production of straw, canopy height and apical meristem height was greater when the oats were not subjected to no management. On the same system on crude protein was higher in the first and cutting the fibrous fractions NDF, ADF, hemicellulose and lignin increased in the third cut. In cutting and grazing managements showed no difference in production dry matter and reduction in production from first to second period and those for the third. The same was true for straw production. The system cutting promoted greater number of tillers and apical meristem increased with the cuts in all managements. The heights of little influence on management characteristics evaluated. The second experiment was conducted with the objective to evaluate structural and productive, straw production residual rates of dehydration, chemical composition and occurrence of fungi in fresh forage and hay with oats made black and white under two cutting heights. The experimental design was a randomized block factorial 2x2 (two species of oats and two cutting heights: 10 and 20 cm) with five replications. The cut was done with mower-conditioner beaters with fingers free. The crude protein values were higher in oat only to be cut (14.15%). The oat showed nutritionally inferior to oat with higher levels of ADF and lignin. There was no effect of cutting height on the composition chemical, but this has interfered in the production of dry matter and the residue after cutting, with higher production with the cut to 10 cm (P <0.05) and increased production of waste in the cut to 20 cm (p<0.05). The oat white promotes hay with better nutritional quality and cutting heights interfere directly on dry matter yield and residue left after harvest / Foram conduzidos dois experimentos com o objetivo de avaliar formas de utilização da aveia: feno, pastejo e corte. O primeiro ensaio avaliou as características estruturais, a composição bromatológica e a digestibilidade in vitro da matéria seca (DIVMS) e da proteína bruta (DIVPB) da aveia branca (Avena sativa IPR 126), sob diferentes formas de manejo: pastejo, corte e crescimento livre sob duas alturas: 15 e 20 cm em três períodos de avaliação (julho, agosto e setembro), com intervalo médio de 25 dias. No manejo crescimento livre, as amostras eram retiradas nos mesmos intervalos de corte e pastejo e nas mesmas alturas (15 e 20 cm). O delineamento foi em blocos casualizados em esquema fatorial 3x2x3 com 3 sistemas de manejo; duas alturas e 3 períodos de avaliação, com 3 repetições. Os resultados encontrados mostram que a produção de matéria seca, produção de palhada residual, altura de dossel e altura de meristema apical foi superior quando a aveia não foi submetida a nenhum manejo. No mesmo sistema a proteína bruta foi superior no primeiro corte e as frações fibrosas FDN, FDA, hemicelulose e lignina elevaram-se no terceiro corte. Nos manejos corte e pastejo não houve diferença na produção de matéria seca, com redução na produção do primeiro para o segundo período e destes para o terceiro. O mesmo ocorreu para a produção de palhada. O sistema corte promoveu maior número de perfilhos e o meristema apical elevou-se com os cortes em todos os manejos. As alturas de manejo pouco influenciaram nas características avaliadas. O segundo experimento foi conduzido com o objetivo de avaliar as características estruturais e produtivas, produção de palhada residual, taxas de desidratação, composição bromatológica e a ocorrência de fungos na forragem fresca e nos fenos obtidos com a aveia branca e preta sob duas alturas de corte. O delineamento experimental foi em blocos casualizados em esquema fatorial 2x2 (duas espécies de aveia e duas alturas de corte: 10 e 20 cm), com 5 repetições. O corte foi realizado com ceifadeira-condicionadora com batedores de dedos livres. Os valores de proteína bruta foram superiores na aveia branca somente no momento do corte (14,15%). A aveia preta mostrou qualidade nutricional inferior a aveia branca com teores superiores de FDA e lignina. Não houve interferência da altura de corte na composição bromatológica, mas esta interferiu na produção de matéria seca e no resíduo após o corte, com valores mais elevados de produção com o corte a 10 cm (P<0,05) e maior produção de resíduo no corte a 20 cm (p<0,05). A aveia branca promove feno com melhor qualidade nutricional e as alturas de corte interferem diretamente na produção de matéria seca e resíduo pós colheita

Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-03-02T11:39:15Z No. of bitstreams: 1 fredericotoledoghetti.pdf: 2816885 bytes, checksum: 98c4c49d919a94d51a94ff86a91c33a1 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-03-06T19:32:09Z (GMT) No. of bitstreams: 1 fredericotoledoghetti.pdf: 2816885 bytes, checksum: 98c4c49d919a94d51a94ff86a91c33a1 (MD5) / Made available in DSpace on 2017-03-06T19:32:09Z (GMT). No. of bitstreams: 1 fredericotoledoghetti.pdf: 2816885 bytes, checksum: 98c4c49d919a94d51a94ff86a91c33a1 (MD5) Previous issue date: 2009-05-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / É apresentado, neste trabalho, um estudo sobre topologias alternativas de fontes ininterruptas de energia do tipo Delta, para o emprego em cargas monofásicas de até 1kVA. O estudo prevê a inserção de um conversor CC-CC entre o conversor shunt e o banco de baterias. Tal modificação em relação à UPS do tipo Delta convencional otimiza o projeto do banco de baterias e requisita um menor número de células em série para sua confecção. Além disso, a proposta elimina o uso de transformadores de baixa freqüência, considerados em alguns trabalhos anteriores, o que também contribui para a redução do peso e volume do sistema. Duas diferentes topologias para o conversor CC-CC foram investigadas e comparações de desempenho e viabilidade foram realizadas. A topologia que apresentou melhor desempenho nos quesitos custo, volume e peso, foi selecionada para testes em bancada. Ao final, resultados simulados e práticos são apresentados para validação do modelo. / This dissertation presents a study on single-phase Delta-UPS topological alternatives for low power and low cost applications. The proposed topology has a DC-DC converter connected between the shunt inverter and the battery bank/series converter DC terminals, respectively. This modification will allow the downsizing of the DC battery bank as well as the removing of the series converter transformer. Two different topologies of the DC DC converter were investigated and a comparative study among them will be accomplished. Simulation results are presented and experimental results will be included to validate the proposed study.

Magister Chirurgiae Dentium (MChD) / Purpose: To evaluate and compare the in-vitro shear bond strength and micro leakage of two compomers with their adhesive systems and to examine the dentine-restorative interface under confocal scanning laser microscopy (CSLM). Matoiats and Methods: For shear bond strength (SBS) testing thirty non-carious human molars were used of which fifteen molars were restored with Dyract AP using Non-Rinse Conditioner (NRC) and Prime&Bond NT (PBNT) and fifteen were restored with F2000 and Scotchbond Multi-Purpose Plus (SBMP). For the microleakage evaluation cavity preparations were made on the facial surfaces of thirty non-carious premolars. These were then restored with the respective compomer system. The specimens were thermocycled, sectioned and examined for dye penetration. The dentine-restorative interface was examined through a confocal scanning laser microscope. The primers of the bonding agents were labelled with rhodamine B and the adhesive resins were labelled with fluorescein and examined under CSLM in fluorescent mode. Results: The mean SBS for PBNT and SBMP were 12.8 and 18.1 MPa, respectively. The microleakage scores showed Dyract with PBNT leaked on the dentine side in 13 of the 15 specimens examined. On the enamel side 2 of the 15 specimens showed microleakage. With F2000 and SBMP no micro leakage was observed on either enamel or dentine sides. The CSLM images show clear resin tag and hybrid layer formation for both the materials examined, although SBMP showed deeper penetration into the dentine with longer resin tags. The length of the resin tags and thickness of the hybrid layer for PBNT was found to be approximately 10 um and 2 um respectively. SBMP showed resin tags measuring about 100 um while the hybrid layer measured about 5 um. Conclusion: This study demonstrates that the acid-etch technique ofSBMP with F2000 produces higher bond strength and no micro leakage when compared to the self-etching/self-priming "non-rinse technique" of NRC with PBNT and Dyract.

Indiana University-Purdue University Indianapolis (IUPUI) / While most sealants available are resin-based, glass ionomer-based cements can be used as sealants, with the advantage of being more tolerant to moisture during placement and of releasing fluoride. The objective of this study was to evaluate the influence of different fissure conditioning techniques on penetration and microleakage of glass ionomer (GI) and resin-modified glass ionomer cements (RMGI) used as sealants. Clinically sound extracted human molars were distributed into nine experimental groups (n = 15 each). Group 1 (control) was sealed with resin-based sealant (Delton) following clinically accepted techniques. Groups 2 through 6 were sealed with RMGI (Vitremer) after having the fissure conditioned with either polyacrylic acid (RMGI-control), 35-percent H3PO4, low viscosity 35-percent H3PO4 with a surfactant, self-etch conditioner, or 35-percent H3PO4 followed by self-etch conditioner. Groups 7 through 9 were sealed with GI sealant (Fuji Triage) after having the fissures conditioned with either polyacrylic acid (GI-control), 35- percent H3PO4 or low viscosity 35-percent H3PO4 with a surfactant. After aging through thermocycling (2500 cycles), specimens were incubated in methylene blue for four hours and sectioned at multiple locations. Digital images were obtained using a digital stereomicroscope, and microleakage was determined by scoring the dye penetration along the enamel-sealant interface. The penetration of the material was determined by calculating the percentage of the total length of the fissure penetrated by the material. Results: The use of self etch-conditioner significantly increased RMGI penetration, while surface conditioning with 35-percent phosphoric acid with surfactant significantly decreased microleakage of GI. The resin-based sealant placed after 35-percent phosphoric acid surface conditioning showed the best penetration and the least level of microleakage. In conclusion, results from this study suggest that the placement of glass ionomer-based sealants can be enhanced by modifying current conditioning methods.

Thesis (M. Tech. (Agriculture)) -- Central University of Technology, Free state, 2014 / The main objective of the study was to determine the effect of different potassium concentrations and water quality (salt) compared with the current scientifically accepted potassium threshold level and standardised water quality on the yield, oil composition and leaf morphology of rose geranium (Pelargonium graveolens L.) when grown in different potting-bag sizes and root media under temperature controlled condition. To achieve this objective, two trials were conducted. The first experiment evaluated potassium concentrations at 1.3, 3.3, 5.3 and 7.3 mmol L-1 and potting-bag size of 5 and 10 L. Treatments were arranged in a randomised complete block design assigned in a split plot layout. The main plots consisted of potassium concentration and the pottingbag sizes were allocated to sub-plots. Plant height, potassium content, linalool, geraniol, geranyl formate and the citronellol to geraniol ratio (C:G) were affected by potassium. Plant height, number of branches, the branch to height ratio (B:H), foliar fresh mass (FFM) and oil yield were significantly increased when 5 L potting bags were used. Plant foliar mass was significantly increased by the interaction between 5.3 mmol K L-1 and 5 L potting bags. In the second experiment salt levels applied at 1.6, 2.4, 3.2 and 4.0 mS cm-1 and root media (sand and sawdust) were evaluated. A split plot experimental layout was also used in this trial, with the salt levels allocated to the main plots. The sub-plots were allocated to the root medium. High salt level of 4.0 mS cm-1 reduced the number of leaves, plant height, number of branches, B:H ratio, leaf area, chlorophyll content and foliar fresh mass significantly. The number of leaves, leaf area and FFM were significantly increased where sawdust was used. Time of the day significantly affected stomatal conductance, and the opening of most stomata occurred at 10:00. Geranyl formate and the C:G ratio were significantly affected by salt at 4.0 mS cm-1. Salt induced the development of capitates trichomes. The abaxial leaf surface had a higher number of trichomes than the adaxial leaf surface. A strong polynomial (r2=0.97) relationship was found between capitates trichomes and salt levels. High densities of capitates trichomes were found at high salt level of 4.0 mS cm-1. Although the development of asciiform trichomes was induced, it was at an insignificant level. Trichome densities are therefore not affected by salt. It was therefore concluded that the application of 5.3 mmol K L-1 concentration and the use of 5 L potting bags improves the yield and oil quality of rose geranium. It was evident from this study that rose geranium might Salt induced have some degree of tolerance to salt. It was therefore concluded that rose geranium is a moderately salt-sensitive crop.

Avec l’avènement des véhicules hybrides rechargeables, voire tout électrique et la nécessité d’une augmentation de l’autonomie et de l’énergie volumique des batteries de traction, leur refroidissement au cours du roulage devient nécessaire pour garantir leur fiabilité et leur durabilité. Pour ces véhicules, le système de production de froid peut avoir à alimenter deux évaporateurs pour la climatisation de l’habitacle (Climatisation au rang 1 et rang 2) ainsi qu’un refroidisseur de liquide pour le refroidissement de la batterie de traction. Ce type de système de réfrigération multi-évaporateur présente un certain nombre de verrous technologiques qu’il convient de lever liés au dimensionnement des éléments dans un contexte de réduction de la charge en fluide frigorigène et au contrôle - commande de tels systèmes. Dans les systèmes de climatisation multi-évaporateurs, la pression d’évaporation est sensiblement égale dans chaque évaporateur de telle manière que leur fonctionnement est couplé dynamiquement. Cependant, la demande en puissance frigorifique et les consignes de température de l’air soufflée et de l’eau peuvent varier d’un évaporateur à l’autre. Le détendeur devient alors un composant clé et son fonctionnement doit être étudié. Pour ces raisons, un banc d’essais expérimental a été créé pour étudier ce type de climatisation multi-évaporateurs en régime stabilisé et en régime transitoire. Des détendeurs thermostatique et électronique ont été montés en parallèle sur chaque évaporateur afin de pouvoir étudier leur impact sur le système. Une fois les différents bilans réalisés, les résultats expérimentaux sont exploités pour caractériser l’ensemble des composants avec le nouveau fluide frigorigène R-1234yf. Les phénomènes de mauvaise distribution du fluide frigorigène dans l’évaporateur ainsi que de l’évaporateur endormi sont également étudiés. Dans un second temps, à partir des résultats expérimentaux, un modèle numérique et dynamique du climatiseur a été réalisé avec le logiciel LMS Imagine Lab Amesim® 1D. Après avoir validé indépendamment chacun des composants, le système est validé sur une série de points de fonctionnement en régime stationnaire. Le modèle est ensuite exploité afin d’étudier diverses lois de contrôle permettant l’optimisation du fonctionnement. / With the arrival of plug-in hybrid and fully electrified vehicles, the air-conditioning system has to be reconsidered. Battery cooling management system and high level of comfort for passengers make the single evaporator air-conditioning system a multi-evaporator one. In a multi-evaporator air-conditioning system, evaporating pressures are equal in each evaporator so that evaporators are coupled dynamically. However, the demand in cooling capacity and temperature target can vary from each other. For an operating point with a first evaporator working at high load and a second at low partial load, thermal interaction can occur from the superheated refrigerant coming from a first evaporator to the outlet of a second evaporator. This phenomenon makes the second evaporator sleeping since its expansion valve bulb misreads the superheat and closes. Furthermore, sleeping evaporator looks like an extreme case of refrigerant maldistribution in the evaporator. Refrigerant maldistribution is then investigated to show some drawbacks and advantages multi-evaporator air-conditioning systems (MEAC) have to face or can benefit by comparing two types of expansion valve: thermostatic and electronic ones. In this paper, sleeping evaporator and refrigerant maldistribution phenomena are experimentally investigated in order to propose in the future a robust control of an automotive MEAC. A test bench was built to compare two types of expansion valves (thermostatic/electronic) and study their behaviours in steady and transient state to tackle sleeping evaporators and benefit from refrigerant maldistribution. An automotive multi-evaporator air conditioning system, which is composed of two evaporators and a secondary fluid cooler, was modeled using the LMS Imagine.Lab Amesim® 1D software. The present study focuses on understanding the dynamic coupling of the several loop components such as the three evaporators having different cooling capacities. This kind of multi-evaporator air-conditioning system has a number of technological barriers that must be overcome. Understanding the behavior of their respective expansion devices and the choice of these latter is also essential to control properly the transient phase and ensure an optimal operation of the air-conditioning system. In order to study the behavior of the loop, step disturbances were simulated on an operating point at medium and high load. The impact of these disturbances on the stability of the supplied cooled air temperature is analyzed for two types of expansion valve. Initial results show that the thermostatic expansion valves can cause instabilities. Furthermore, the electronic expansion valves have to be regulated with an advanced control in order to use their full potential and to try to achieve desired results.

A crescente demanda por fontes alternativas de energia, voltada principalmente a minimizar impactos ambientais provenientes do uso de combustíveis fósseis na geração de energia elétrica, tem impulsionado as pesquisas tanto no âmbito acadêmico como no setor privado. Dessa forma, estudos científicos vêm abordando painéis fotovoltaicos, aerogeradores, células combustível, dentre outros, no sentido de gerar energia limpa por meio de conversores estáticos CC-CC e CC-CA, conectados na rede de distribuição elétrica, configurando um cenário de Geração Distribuída. Devido ao uso de tais conversores, têm-se introduzido perturbações harmônicas nas redes de distribuição. Sendo assim, a qualidade de energia tornouse uma questão de suma importância no contexto energético contemporâneo, de tal modo que esta tese se apresenta um estudo voltado ao desenvolvimento e implementação de uma plataforma experimental de um Condicionador Unificado de Qualidade de Energia (UPQC) monofásico com compensação ativa de potência série e paralela, com uma potência de 1 kW, capaz de minimizar perturbações harmônicas em redes de distribuição. O sistema realiza a supressão de harmônicos e a compensação de afundamentos e elevações de tensão em redes elétricas, além de manter a tensão na carga regulada e com baixa taxa de distorção harmônica. Além disso, esse dispositivo realiza compensação de potência reativa e supressão de harmônicos da corrente de carga, o que resulta em uma efetiva correção do fator de potência. Nesse sentido, o dispositivo atua como um filtro ativo universal, realizando compensação da corrente de entrada, como também da tensão de saída. Para este fim, dois conversores monofásicos ANPC de 5 níveis são empregados, sendo estes o filtro ativo série (FAS), que atua como fonte de corrente senoidal, e o filtro ativo paralelo (FAP), que atua como fonte de tensão senoidal, em que ambos são controlados de tal forma a operar em fase com a tensão da rede elétrica. Com o objetivo de realizar as compensações harmônicas, é utilizado o algoritmo de extração de referência, conhecido como Compensação Cooperativa baseada na Teoria de Potência Conservativa. / The growing demand for alternative sources of energy, aimed mainly at minimizing environmental impacts from the use of fossil fuels in electric power generation, has driven research in both the academic and private sectors. Thus, scientific studies have addressed photovoltaic panels, aerogenerators, fuel cells, among others, in order to generate clean energy by means of static converters CC-CC and CC-CA, connected in the electric distribution network, configuring the Distributed Generation. Due to the use of such converters, harmonic disturbances have been introduced in the distribution networks. Thus, the quality of energy has become a matter of paramount importance in the contemporary energy context, such that this thesis presents a study aimed at the development and implementation of an experimental platform of a single-phase Unified Energy Quality Conditioner (UPQC) with active series and parallel power compensation, with a power of 1 kW, capable of minimizing harmonic disturbances in distribution networks. The system performs the suppression of harmonics and the compensation of sags and tensions in electrical networks, besides maintaining the voltage at the regulated load and with a low harmonic distortion rate. In addition, this device performs reactive power compensation and harmonic suppression of the load current, which results in an effective power factor correction. In this sense, the device acts as a universal active filter, performing compensation of the input current, as well as the output voltage. For this purpose, two 5-level ANPC single-phase converters are used, which are the series active filter (FAS), which acts as a sinusoidal current source, and the parallel active filter (FAP), which acts as a sinusoidal voltage source, in that both are controlled in such a way to operate in phase with the mains voltage. In order to perform the harmonic compensations, the reference extraction algorithm, known as Cooperative Compensation based on the Conservative Power Theory, is used.

Made available in DSpace on 2016-12-12T17:38:31Z (GMT). No. of bitstreams: 1 (Final).pdf: 65790 bytes, checksum: e733029dada465cd658278f93c2fc5fa (MD5) Previous issue date: 2012-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work introduces a dual unified power quality conditioner (iUPQC) made by two active filters, the series and the parallel. The parallel active filter is voltage controlled, responsible for maintaining the sinusoidal, regulated, balanced and harmonic free load voltage. The series active filter is responsible for draining a sinusoidal and harmonic free current from the utility grid whose current is synchronized with the fundamental component of the voltage utility grid, implying a high power factor. The advantage of this configuration is the use of the sinusoidal references for both active filters. First, the power quality is addressed by discussing the main utility grid distortions and the active solutions for these problems. The characteristics, the power structure definition and the power flow of the iUPQC are then addressed. Next, the high frequency filters of active filters are analyzed and designed, the circuit models are obtained and the iUPQC controllers are designed. The iUPQC simulation is then analysed and, finally, the last chapter is about the prototype developed at the university laboratory, and the analysis of the experimental results which were compared to the IEEE519-1992 standard / Esta Dissertação de Mestrado apresenta um condicionador unificado de qualidade de energia dual (iUPQC) trifásico a quatro fios, controlado analogicamente, composto por dois filtros ativos, o série e o paralelo. O filtro ativo paralelo é controlado em tensão, responsável por manter a tensão da carga senoidal, regulada, equilibra e livre de harmônicos. O filtro ativo série é responsável por drenar da rede de alimentação uma corrente senoidal, com baixa distorção harmônica e em fase com a componente fundamental de tensão da rede, garantindo alto fator de potência. A vantagem desta configuração é a utilização de referências senoidais para ambos os filtros ativos. Inicialmente, a qualidade de energia é abordada, trazendo as principais distorções encontradas na rede elétrica e as soluções ativas para estes problemas. O iUPQC é apresentado, trazendo suas características, a definição de sua estrutura de potência e o fluxo de potência do sistema. Após isto são analisados e projetados os filtros de alta frequência presentes nos filtros ativos, obtidos os modelos do circuito e projetados os controladores do iUPQC. Em seguida a simulação do iUPQC é apresentada e no último capítulo são mostrados os circuito utilizados no protótipo e os resultados experimentais obtidos, os quais são analisados e comparados à norma IEEE 519-1992.