Computational evaluation of hydraulic system behaviour with entrapped air under rapid pressurization

The pressurization of hydraulic systems containing entrapped air is considered a critical condition for the infrastructure's security due to transient pressure variations often occurred. The objective of the present study is the computational evaluation of trends observed in variation of maximum surge pressure resulting from rapid pressurizations. The comparison of the results with those obtained in previous studies is also undertaken. A brief state of art in this domain is presented. This research work is applied to an experimental system having entrapped air in the top of a vertical pipe section. The evaluation is developed through the elastic model based on the method of characteristics, considering a moving liquid boundary, with the results being compared with those achieved with the rigid liquid column model.

Computational evaluation of hydraulic system behaviour with entrapped air under rapid pressurization

The pressurization of hydraulic systems containing entrapped air is considered a critical condition for the infrastructure's security due to transient pressure variations often occurred. The objective of the present study is the computational evaluation of trends observed in variation of maximum surge pressure resulting from rapid pressurizations. The comparison of the results with those obtained in previous studies is also undertaken. A brief state of art in this domain is presented. This research work is applied to an experimental system having entrapped air in the top of a vertical pipe section. The evaluation is developed through the elastic model based on the method of characteristics, considering a moving liquid boundary, with the results being compared with those achieved with the rigid liquid column model.

Biaxial Nematic Order in the Hard-boomerang Fluid

We consider a fluid of hard boomerangs, each composed of two hard spherocylinders joined at their ends at an angle Psi. The resulting particle is nonconvex and biaxial. The occurence of nematic order in such a system has been investigated using Straley's theory, which is a simplificaton of Onsager's second-virial treatment of long hard rods, and by bifurcation analysis. The excluded volume of two hard boomerangs has been approximated by the sum of excluded volumes of pairs of constituent spherocylinders, and the angle-dependent second-virial coefficient has been replaced by a low-order interpolating function. At the so-called Landau point, Psi(Landau)approximate to 107.4 degrees, the fluid undergoes a continuous transition from the isotropic to a biaxial nematic (B) phase. For Psi not equal Psi(Landau) ordering is via a first-order transition into a rod-like uniaxial nematic phase (N(+)) if Psi > Psi(Landau), or a plate-like uniaxial nematic (N(-)) phase if Psi < Psi(Landau). The B phase is separated from the N(+) and N(-) phases by two lines of continuous transitions meeting at the Landau point. This topology of the phase diagram is in agreement with previous studies of spheroplatelets and biaxial ellipsoids. We have checked the accuracy of our theory by performing numerical calculations of the angle-dependent second virial coefficient, which yields Psi(Landau)approximate to 110 degrees for very long rods, and Psi(Landau)approximate to 90 degrees for short rods. In the latter case, the I-N transitions occur at unphysically high packing fractions, reflecting the inappropriateness of the second-virial approximation in this limit.

Aulas de técnica de flauta em grupo: uma forma de motivar os alunos para o estudo da mesma: relatório de estágio

RESUMO I - PARTE PEDAGÓGICA - O presente relatório de estágio é composto por dois capítulos: Prática Pedagógica e Investigação. A atividade docente, que serviu de base para a realização deste primeiro capítulo, teve lugar no Conservatório de Música de Santarém. Primeiramente caracteriza-se o Conservatório de Música de Santarém, sendo possível observar a sua história e objetivos pedagógicos. São também caracterizados os alunos participantes no estágio, o seu percurso académico, as suas expectativas e motivações. O subcapítulo dedicado à prática educativa desenvolvida, apresenta os objetivos e metas traçados para cada aluno; as estratégias adotadas pelo docente de forma a permitir o desenvolvimento de níveis metacognitivos e a motivação intrínseca. Neste capítulo é feita uma análise crítica da atividade docente, onde é apresentado o trabalho desenvolvido com cada aluno, ao longo do ano. Neste subcapítulo, é à semelhança do anterior, aparecem algumas referências a aspetos presentes nas considerações teóricas apresentadas na introdução do trabalho. A conclusão da atividade docente consiste numa reflexão sobre a postura adotada pelo professor e a sua autoavaliação do trabalho realizado com os alunos.