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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.
1

AvaliaÃÃo do Rendimento de Unidade de Bombeamento de Ãgua Acionada por um Gerador EÃlico de Pequeno Porte / Performance evaluation of water pumping unit powered by a small wind turbine

Mendeleyev Guerreiro Ferreira 27 March 2009 (has links)
Esta dissertaÃÃo de mestrado apresenta um sistema para bombeamento de Ãgua utilizando um gerador eÃlico autÃnomo de pequeno porte, instalado em frente ao aÃude do Campus da UFC. A potÃncia do gerador à de 1 kW e o mesmo utiliza a tecnologia de Ãmà permanente garantindo vantagens como: menores perdas no rotor, menor aquecimento e o alcance de maiores rendimentos. AlÃm do gerador eÃlico, o sistema à composto por um conjunto motor-bomba centrÃfuga de 0,5 cv de potÃncia, um medidor de vazÃo, um medidor de pressÃo, um analisador de energia que registra valores de grandezas elÃtricas (corrente, tensÃo, potÃncia), um datalogger para coleta de dados e um anemÃmetro de conchas para mediÃÃo de vento. O projeto consiste em determinar o rendimento deste sistema para as condiÃÃes de vento do local da instalaÃÃo, a partir de dados coletados durante os meses de maio e julho de 2008. Os resultados demonstram que em apenas cerca de 10,97% do total de dias referentes ao mÃs de maio e cerca de 54,57% do total de dias do mÃs de julho, o conjunto motor-bomba foi acionado pelo gerador eÃlico e que os rendimentos globais variam entre 0,41 e 0,74%. Observando os valores de vazÃo encontrados, quando comparados com a curva caracterÃstica da bomba utilizada, percebe-se uma sub-utilizaÃÃo da mesma, principalmente no mÃs de maio. / This work presents a system for water pumping using an independent small wind generator, installed in the UFCÂs Campus. The generatorâs power is 1 kW and uses a permanent magnet technology providing advantages such as: lower losses in the rotor, lower heating and achieving higher yields. Besides the wind generator, the system consists of centrifugal pump-motor assembly 0,5 cv of power, a flow meter, a pressure meter, an energy analyzer that records the electrical data (current, voltage, power), a datalogger for data collection and a shell anemometer for measuring of wind speed. The project consists in determining the performance of this system for the local wind conditions, from data collected during the months of May and July 2008. The results show that in only about 10,97% of total days for the month of May and about 54,57% of the total days of July, the pump-motor was triggered by the wind generator and the global yields ranging between 0,41 to 0,74%. Observing the flow values found when compared with the characteristic curve of the pump used, there is a perceived under-utilization of the same, especially in May.
2

Variační metody v termomechanice kontinua pevné fáze / Variational Methods in Thermomechanics of Solids

Pelech, Petr January 2020 (has links)
The thesis is devoted to study of continuum mechanics and thermodynamics and the related mathematical analysis. It consists of four self-contained chapters dealing with different aspects. The first chapter focuses on peridynamics, a non-local theory of continuum mechanics, and its relation to conventional local theory of Cauchy-Green elasticity. Similar compar- isons has been used for proving consistency and for determining some of the material coefficients in peridynamics, provided the material parameters in the local theory are known. In this chapter the formula for the non-local force-flux is computed in terms of the peridynamic interaction, relating the fundamental concepts of these two theories and establishing hence a new connection, not present in the previous works. The second and third chapters are both devoted to Rate-Independent Systems (RIS) and their applications to continuum mechanics. RIS represents a suitable approximation when the internal, viscous, and thermal effects can be neglected. RIS has been proven to be useful in modeling hysteresis, phase transitions in solids, elastoplasticity, damage, or fracture in both small and large strain regimes. In the second chapter the existence of solutions to an evolutionary rate-independ- ent model of Shape Memory Alloys (SMAs) is proven. The model...

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