Enquadramento legal e estudo económico de parques eólicos

Portugal, no intuito de alcançar metas ambientais e económicas a que se propôs, e de reduzir a dependência das importações de energia, tem aumentado o investimento em eletricidade produzida a partir de energias renováveis (FER-E). Apesar do consenso em torno da sua utilização, as energias renováveis deparam-se com barreiras de várias ordens que dificultam a sua difusão no mercado. A atuação do Estado neste enquadramento passa por criar modelos de promoção da FER-E. A maioria dos países da União Europeia, incluindo Portugal, aplica as tarifas feed-in (FIT) como instrumento central de suporte à FER-E, inserido num modelo de apoio que contempla outros parâmetros de construção considerados críticos para o seu sucesso. No seguimento do estágio realizado na empresa Senvion Portugal a presente tese explora os programas e modelos de apoio às FER-E em Portugal, nomeadamente as que se referem à energia eólica. Bem como os trabalhos realizados com as equipas de O&M e a realização de um estudo de viabilidade económica da substituição de aerogeradores no parque eólico de Picos Verdes II.

Effect of different feed-rate in bone drilling: experimental and numerical study

The behaviour of bone tissue during drilling has been subject of recent studies due to its great importance. Because of thermal nature of the bone drilling, high temperatures and thermal mechanical stresses are developed during drilling that affect the process quality. However, there is still a lack information with regard to the distribution of mechanical and thermal stresses during bone drilling. The present paper describes a sequentially coupled thermal-stress analysis to assess the mechanical and thermal stress distribution during bone drilling. A three-dimensional thermo-mechanical model was developed using the ANSYS/LSDYNA finite element code under different drilling conditions. The model incorporates the dynamic characteristics of drilling process, as well as the thermo-mechanical properties of the involved materials. Experimental tests with polyurethane foam materials were also carried out. It was concluded that the use of higher feed-rates lead to a decrease of normal stresses and strains in the foam materials. The experimental and numerical results were compared and showed good agreement. The proposed numerical model could be used to predict the better drilling parameters and minimize the bone injuries.

Effect of different feed-rate in bone drilling: experimental and numerical study

The behaviour of bone tissue during drilling has been subject of recent studies due to its great importance. Because of thermal nature of the bone drilling, high temperatures and thermal mechanical stresses are developed during drilling that affect the process quality. However, there is still a lack information with regard to the distribution of mechanical and thermal stresses during bone drilling.