This Diploma thesis analyses monetary policy management in USA during the passed decade and proposes some changes regarding the future decision making of central banks. In particular, a considerable deviation of the actual monetary policy from the Taylor rule right before the housing bubble was proved by an econometric model. As a consequence, too low interest rates in this period caused significant higher magnitude of real estate prices. However, it can be said that monetary policy was not the main cause of the creation of this bubble. Regarding the FED's reaction on financial crisis, new perspectives are provided. According to this study, credit risk is thought to have been the main cause of financial stress. This is in contradiction with FED's measures that were mainly focused on lack of liquidity in financial markets. Last but not least, this thesis argues that nowadays, international development should be more reflected in monetary policy decision making.

In cattle breeding, it is necessary to pay great attention to calves, especially to the quality of their housing. Calf rearing is one of the riskiest parts of the whole breed. This requires a thorough development of biological, nutritional, ethological and technological factors of breeding. The aim of this thesis was to compare two different ways of housing calves (individually vs. pairs) in roofed outdoor individual boxes with feedeng twice a day and evaluate their influence on the course of growth and health from birth to weaning. The experiment was carried out at the Číčov farm, which i sone of the centers of Alimex a.s. Nezvěstice, farming in the district of Plzeň - South. The actual monitoring of the calves took place from 1. 1. 2018 to 31. 7. 2018. Both groups of calves included in the experiment were fed the same amount of feed (native milk, milk replacer, TMR). Each group had the same number of pieces - 12 calves (heifers) of the Holstein cattle breed. At the end of the reporting period, calves that were raised together in pairs at average weight of 227.17 kg during the dairy period, while calves reared individually during the same period reached a final weight of 215 kg. The average daily increase in calves with a common rearing was 0.89 kg, in calves of the second group this value was lower, namely 0.83 kg. However, tthe difference between the mean final weights of both groups was not statistically significant (p > 0.05). All calves included tn the exxperiment were fed with appropriate quality colostrum (immunoglobulin content of 100 g/l or more) within 2 hours of delivery. Immunity of all experimental calves was sufficient, so the level of immunoglobulins did not fall below 50 g/l, with more than 85 % of calves having an immunoglobulin content above 55 g/l. In calves reared individually during the experiment, diarrhea was noted in three animals and respiratory disease in four animals. In rearing together, there was diarrhea in five calves. Respiratory disease occured in four calves. In both experimental groups of calves, it was observed that immediately after drinking, the animals were mutually sucking mules, but the calves housed together with a lower frequency also licked the polypropylene plates separating the VIB and nibbled empty buckets.

Most of the modern wind turbines are based on doubly fed induction generators (DFIG), with a back to back power converter connecting the rotor to the network. It is known that voltage dips at the stator terminals can cause overcurrents in the rotor windings, which could threaten the converter integrity. In order to protect the converter, several strategies have been proposed in technical literature, requiring in some cases the converter deactivation, which disables the control that the converter has over the power transference between the generator and the system. This last is not a desirable behavior since it can put on risk the voltage stability of the electric system. It is the aim of this dissertation to introduce and compare five of those protection strategies, through the computational simulation of their performance in case of balanced voltage dips. In order to achieve this, the electromagnetic dynamic model of the DFIG was theoretically developed, as well as the models of the strategies of interest. Subsequently, the computational model of the system was assembled in the software Matlabs Simulink to finally perform the desired simulations and its corresponding analysis. / A maioria das turbinas eólicas modernas é baseada em geradores de indução duplamente alimentados (GIDE), com um back to back conversor de energia que liga o rotor para a rede. Sabe-se que as quedas de tensão nos terminais do estator podem causar sobrecorrentes nos enrolamentos do rotor, que podem ameaçar a integridade do conversor. A fim de proteger o conversor, várias estratégias têm sido propostas na literatura técnica, exigindo, em alguns casos, a desativação do conversor, o qual desativa o controlo do conversor, que possui ao longo da transferência de energia entre o gerador e o sistema. Este último não é um comportamento desejável, uma vez que pode colocar em risco a estabilidade de tensão do sistema elétrico. É o objetivo desta dissertação apresentar e comparar cinco dessas estratégias de proteção, através da simulação computacional de seu desempenho em caso de quedas de tensão equilibrada. A fim de alcançar este objetivo, o modelo dinâmico eletromagnética do DFIG teoricamente foi desenvolvido, bem como os modelos das estratégias de interesse. Subsequentemente, o modelo computacional do sistema foi montado no software Simulink do Matlab para finalmente executar as simulações desejadas e sua análise correspondente.

A cianobactéria \' Spirulina platensis \' possui alto teor de proteína e vem sendo cultivada fotoautotroficamente para a produção de biomassa microbiana. Embora as fontes convencionais de nitrogênio utilizadas para a produção de Spirulina spp. sejam os nitratos, há a possibilidade do emprego de uréia, utilizando o processo descontínuo alimentado, com diminuição do custo de produção. O emprego do processo descontínuo alimentado repetitivo para o cultivo desta microalga utilizando a uréia como fonte de nitrogênio poderia facilitar os cultivos em escala de produção, pois não haveria a necessidade de preparo de inóculo para cada ciclo de produção, além de possibilitar o aumento da produtividade do sistema. Este trabalho tem o objetivo de verificar o comportamento do cultivo microbiano com este processo, visto que não foram encontrados na literatura tais estudos para o cultivo de \'S. platensis\'. Foi verificada a influência dos parâmetros fração de corte, tempo de alimentação de uréia e ciclos de cultivo neste tipo de processo, tendo como variáveis dependentes a concentração celular máxima (Xm), a produtividade em células (Px) e o fator de conversão de nitrogênio em células (Yx/n), bem como a composição protéica e lipídica da biomassa obtida. Os resultados obtidos permitem concluir que, de uma forma geral, uma fração de corte de 80% associada a um tempo de alimentação de 6 dias leva a melhores condições de cultivo com bons resultados nos três parâmetros cinéticos (em média, 2101 mg.L?¹, 219 mg.L?¹.d?¹ e 10,3 mg.mg?¹ para Xm, Px e Yx/n, respectivamente), que foram reprodutíveis ao longo de 3 ciclos. / \' Spirulina platensis \', with high protein content, can be cultivated photoautotrophically for the microbial biomass production. Although nitrates are the conventional source of nitrogen for the Spirulina spp. production, there is a possibility of the use of urea, in a fed-batch process, leading to a cost reduction. The application of repeated fed-batch process, using urea as nitrogen source, could propitiate the cultivation of this microorganism in a production scale, since it would not need to prepare the inoculum for each production cycle. Moreover, there is a possibility to improve the productivity of this process. The aim of this work was to verify the behavior of the microbial cultivation employing this process, since this kind of study for \' Spirulina platensis \' production was not found in literature. The influence of withdrawn rate, urea feeding time and cultivation cycles were studied, considering maximum cell concentration (Xm), cell productivity (Px), nitrogen-to-cell conversion (Yx/n), and protein and total fat contents as dependent variables. The results show that in general a 80% of withdrawn rate associated with 6 days of feeding time leads to the best cultivation conditions with satisfactory results of Xm, Px and Yx/n (2101 mg.L?¹, 219 mg.L?¹.d?¹ and 10.3 mg.mg?¹, in average, respectively), that could be reproduced through the three cycles.

<p>The purpose of the project is to replicate conditions found inside the reaction chamber of a nuclear thermal propulsion (NTP) rocket engine, thereby evaluating robust materials and construction techniques for future NTPs. The need to test materials exposed to hydrogen under combined high temperatures and pressures is crucial to determine their resistance to hydrogen attack.</p> <p>The proposed test article is a SiC resistive heating element which would heat the hydrogen gas flowing at 5.6 g/s from 300 to 2400 K at nominal pressure of 1000 psia then cool it to below its auto-ignition temperature before it is vented to the ambient air. The experimental evaluation of the test article should validate the reliability of materials used in the construction of the pressure vessel. The pressure vessel houses a resistive heating element made from open-cell refractory carbide foam which pairs well with hot hydrogen gas due to its resistance to thermal shock. The enclosure to encapsulate the heating element is lined with an oxide coated rhenium tube capable of sustaining high thermal and structural loads, and the outer shell is made from Inconel 718. Rhenium is a robust material with excellent ductility, is non-reactive with hydrogen, and is creep-resistant at high temperatures. Inconel 718 has a high yield strength capable of handling high temperature applications. </p> <p>Cooling the hydrogen gas requires designing a water-cooled nozzle to transport the gas to a heat exchanger. The design of the nozzle and its mechanical components involved analyzing the heat transfer through materials, predicting their structural integrity, and examining potential failure points. The 1-D steady-state heat transfer analysis is conducted to predict the inner and outer surface temperatures, heat flux, and fluid heat transfer coefficients. These parameters are considered in selecting the best candidate materials, copper and Inconel 718, to make the nozzle. To prevent gas leakage between interfaces of multiple components and joints, a careful selection of sealing techniques are implemented, including the use of bimetallic weldments and pressure-energized metal seals. </p> <p>Although the proposed test article was never tested due to schedule and budget limitations, the documentation of its design and analysis is complete and the system is ready for manufacturing and testing. The long lead times to manufacture, to inspect, and to validate the vessel were underestimated in the project scheduling. The rental cost of the electrical equipment required to run the test under initial design conditions exceeded budget. As a solution to satisfy the temperature and budget requirements, halving the flow rate and decreasing the delivered electrical power by 48% are proposed. </p> <p> The success of testing the pressure vessel at operating conditions would provide a physical and quantitative study on potential materials used on future NTP ground tests. The test would run for 5 minutes during which the strength of the materials weaken as a result of the diffusion of free carbon from their surfaces. Upon completion of the test, the performance of these materials would be evaluated for signs of macroscopic and microscopic surface effects on the test article. </p> <p> </p>

O tratamento de efluentes industriais gerados em elevadas temperaturas por meio da digestão anaeróbia termofílica aparece como opção para o controle da poluição ambiental e obtenção de bioenergia. Nesse sentido, este trabalho investigou o uso do reator anaeróbio termofílico contendo biomassa imobilizada e com agitação mecânica operado em batelada e/ou batelada alimentada sequenciais no tratamento da vinhaça visando a produção de metano. Foi verificada a influência do aumento da carga orgânica volumétrica aplicada e da estratégia de alimentação no desempenho do reator. O volume do meio líquido do reator foi de 2,3 L, sendo 1,3 L de volume residual e 1,0 L o volume de efluente a ser tratado por ciclo, mantendo-se constante a temperatura (55º C &#8211; faixa termofílica), o tempo de ciclo (8 horas) e a velocidade de agitação (100 rpm). Inicialmente foi realizada a adaptação da biomassa, em seguida foi avaliada a influência da carga orgânica volumétrica aplicada (6,5-25,9 gDQO.L-1.d-1) pelo aumento da concentração de matéria orgânica afluente, e por fim foi implementada a estratégia de alimentação por batelada alimentada. Na etapa do aumento da COVA foram alcançadas maiores produtividades molar (304 molCH4.m-3.d-1) e volumétrica (6828 mL-CNPT CH4L-1.d-1) de metano na COVA de 25,9 gDQO.L-1.d-1, com rendimento de metano por matéria orgânica consumida próximo ao valor teórico (15,6 mmol de CH4.gDQO-1) e remoção da matéria orgânica na forma de DQO entre 75-80 % nas condições com COVA acima de 14gDQO.L-1.d-1. Na etapa em que se modificou a estratégia de alimentação, as produtividades molar e volumétrica de metano foram de 351,9 molCH4.m-3.d-1 e 7888 mL-CNPT CH4.L-1.d-1, respectivamente, com rendimento de metano por matéria orgânica removida próximo ao valor teórico. A produção de energia foi de 25,1 MW e 30,3 MW nas condições em batelada e batelada alimentada, respectivamente. O modelo cinético permitiu o entendimento da influência da carga orgânica e da estratégia de alimentação sobre o desempenho do reator para geração de metano, analisando-se os coeficientes das reações de consumo/produção dos compostos envolvidos na rota metabólica. / The thermophilic anaerobic digestion of wastewater that are generated at high temperatures appers as an option for the environmental pollution control and bioenergy production. Thus, this study investigate a anaerobic reactor containing immobilized biomass and mechanical stirrer operate in sequential batch or feed batch treating vinasse-based wastewater for methane production. It was analyzed the effects on reactor performance of increasing the applied volumetric organic load (AVOL) and modifying the feeding strategy. The total volume of liquid was 2,3 L, in which 1,3 L of residual volume and 1,0 L of wastewater to be treated per cycle, keeping constant the temperature (55 ºC &#8211; thermophilic range), the cycle length (8 hours) and the stirred velocity (100 rpm). At first it was realizes the biomass adaption, then it was analyzed the applied volumetric organic load (6,5-25,9 gDQO.L-1.d-1) increasing the influent concentration and after the feeding strategy was modified. In the AVOL increasing were achieved higher molar productivity of methane (304 molCH4.m-3.d-1) and volumetric productivity (6828 mL-CNTP CH4.L-1.d-1) at AVOL of 25,9 gDQO.L-1.d-1, and molar yield of methane per organic matter removed close to the theoretical value (15,6 mmolCH4.gDQO-1) and removal efficiency of organic matter in terms of DQO between 75-80% for all conditions above AVOL of 14 gDQO.L-1.d-1. In the stage of feeding strategy change, the methane molar and volumetric productivity were 351,9 molCH4.m-3.d-1 and 7888 mLCH4.L-1.d-1, receptively, and the yield methane production per removal organic matter close to the theoretical value. The energy production were 25,1 MW and 30,3 MW in the batch and fed batch conditions, respectively. The kinetic model allowed known of AVOL and feeding strategy influence under the reactor performance to methane generation, analyzing the reaction coefficient of the compounds consume/production involved in the metabolic rote.

As microalgas são organismos unicelulares, eucariotos, simples em estrutura, fotossintetizantes, que requerem principalmente luz, água e nutrientes inorgânicos para seu crescimento. Estes micro-organismos podem converter eficientemente dióxido de carbono em biomassa e certos compostos bioativos com aplicações nas indústrias alimentícia, farmacêutica e cosmética. Botryococcus braunii é uma espécie de microalga capaz de sintetizar e armazenar lipídios, incluindo ácidos graxos, epóxidos, alquilfenol, éter e hidrocarbonetos de cadeia longa. O conteúdo lipídico pode alcançar de 15% a 75% da biomassa seca, sendo que os ácidos graxos livres representam mais da metade deste extrato. Os parâmetros como carbono inorgânico, nitrogênio, vitaminas e sais são vitais para o crescimento de microalgas, exercem influência tanto no crescimento como na composição da biomassa. Assim, este trabalho tem a finalidade de verificar a influência das quantidades de nitrato de sódio e de fosfato de potássio dibásico no crescimento e composição da microalga Botryococcus braunii, onde serão avaliados parâmetros cinéticos e de crescimento, bem como a composição da biomassa. Os diferentes meios de cultivo avaliados para o crescimento da microalga mostraram a importância da influência da salinidade no crescimento e composição da biomassa de B. braunii, sendo o meio Chu encontrado como o melhor meio para o crescimento, no qual para uma otimização do crescimento e produção de biomassa foram utilizadas diferentes concentrações de fontes de nitrogênio e fósforo. Com uso de meio Chu, foi possível a obtenção de concentrações celulares de 4962,9mg.L-1 em fotobiorreator tubular, com correção da concentração das fontes de nitrogênio e fósforo de acordo com o crescimento celular. Nas várias concentrações de nitrogênio e fósforo avaliadas, foi encontrada uma concentração de lipídios numa faixa de 32,56 a 36,93%, onde foram encontrados os seguintes ácidos graxos C11:0; C14:1; C16:0; C16:1; C17:1; C18:0; C18:1n9; C18:2n6; C20:0; C18:3n6; C20:1 e C18:3n3. / Microalgae are unicellular photosynthetic organisms, eukaryotes, simple in structure, requiring mainly light, water and inorganic nutrients for growth. These micro-organisms can efficiently convert carbon dioxide into biomass and certain bioactive compounds with applications in food, pharmaceutical and cosmetic industries. Botryococcus braunii is a microalga capable of synthesizing and storaging lipids, including fatty acids, epoxides, ether, and hydrocarbons. Lipid content can reach 15% to 75% of dry matter, and free fatty acids represent more than half of this extract. Parameters such as inorganic carbon, nitrogen, vitamins and salts are important parameters regulating algal growth and the composition of biomass. This work aims to study the influence of the amounts of sodium nitrate and potassium phosphate dibasic in the growth and composition of microalgae Botryococcus braunii, by evaluating kinetic and growth parameters, as well as biomass composition. The culture media evaluated for the growth of microalgae, showed the importance of the influence of salinity on growth and biomass composition of Botryococcus braunii. Chu medium was found as the best medium for growth, for which an optimization of growth and biomass concentrations different sources of nitrogen and phosphorus was used. Using the Chu medium, it was possible to obtain cell concentrations of 4962.9mg.L-1 in tubular phobioreactor, with correction of concentrations of both nitrogen and phosphorus sources according to cell growth. Taking into account the various nitrogen and phosphorus evaluated, A concentration of lipids was found in a range from 32.56 to 36.93%, where the fatty acids are: C11:0; C14:1; C16:0; C16:1; C17:1; C18:0; C18:1n9; C18:2n6; C20:0; C18:3n6; C20:1 and C18:3n3.

This thesis deals with the current financial crisis and its solutions. In the first part of this work are analyzed the main causes underlying the emergence of contemporary global crisies. Described are also the methods and financial products through which the crisies spread from the United States of America to the rest of the world, mentioned are main negative impacts of the crisis in the Czech Republic and anti-crisis measures taken by the czech government in context of crisis. In the second part of the work proposed recommendations that could reduce the likelihood of further crises in the future or measures, which could help to solve the current economic crisis. The conclusion summarizes the results of the analysis and answer the question if it is possible to avoid a financial crisis and the resulting economic recession or will come again and again?

This thesis analysis the parallel between Japan crises in the 90s and the recent financial crisis, which originated in the United States in 2007. A significant part is devoted to analyzing the root causes of the emergence of the Japan crisis and recent financial crisis. Practical part will focus on analysis of economic cycles of these crises, analysis of price behavior on stock and property market, and finaly on analysis of impact of impact of measures taken on subsequent economic development. Conclusion will seek to answer the question whether the United States expect the same economic development as Japan in the nineties.

A cianobactéria \' Spirulina platensis \' possui alto teor de proteína e vem sendo cultivada fotoautotroficamente para a produção de biomassa microbiana. Embora as fontes convencionais de nitrogênio utilizadas para a produção de Spirulina spp. sejam os nitratos, há a possibilidade do emprego de uréia, utilizando o processo descontínuo alimentado, com diminuição do custo de produção. O emprego do processo descontínuo alimentado repetitivo para o cultivo desta microalga utilizando a uréia como fonte de nitrogênio poderia facilitar os cultivos em escala de produção, pois não haveria a necessidade de preparo de inóculo para cada ciclo de produção, além de possibilitar o aumento da produtividade do sistema. Este trabalho tem o objetivo de verificar o comportamento do cultivo microbiano com este processo, visto que não foram encontrados na literatura tais estudos para o cultivo de \'S. platensis\'. Foi verificada a influência dos parâmetros fração de corte, tempo de alimentação de uréia e ciclos de cultivo neste tipo de processo, tendo como variáveis dependentes a concentração celular máxima (Xm), a produtividade em células (Px) e o fator de conversão de nitrogênio em células (Yx/n), bem como a composição protéica e lipídica da biomassa obtida. Os resultados obtidos permitem concluir que, de uma forma geral, uma fração de corte de 80% associada a um tempo de alimentação de 6 dias leva a melhores condições de cultivo com bons resultados nos três parâmetros cinéticos (em média, 2101 mg.L?¹, 219 mg.L?¹.d?¹ e 10,3 mg.mg?¹ para Xm, Px e Yx/n, respectivamente), que foram reprodutíveis ao longo de 3 ciclos. / \' Spirulina platensis \', with high protein content, can be cultivated photoautotrophically for the microbial biomass production. Although nitrates are the conventional source of nitrogen for the Spirulina spp. production, there is a possibility of the use of urea, in a fed-batch process, leading to a cost reduction. The application of repeated fed-batch process, using urea as nitrogen source, could propitiate the cultivation of this microorganism in a production scale, since it would not need to prepare the inoculum for each production cycle. Moreover, there is a possibility to improve the productivity of this process. The aim of this work was to verify the behavior of the microbial cultivation employing this process, since this kind of study for \' Spirulina platensis \' production was not found in literature. The influence of withdrawn rate, urea feeding time and cultivation cycles were studied, considering maximum cell concentration (Xm), cell productivity (Px), nitrogen-to-cell conversion (Yx/n), and protein and total fat contents as dependent variables. The results show that in general a 80% of withdrawn rate associated with 6 days of feeding time leads to the best cultivation conditions with satisfactory results of Xm, Px and Yx/n (2101 mg.L?¹, 219 mg.L?¹.d?¹ and 10.3 mg.mg?¹, in average, respectively), that could be reproduced through the three cycles.