Reflexiones sobre la decisión de internamiento en campamentos de la Corte Suprema de Kenia

Los grupos de la sociedad civil han acogido una reciente victoria ante la Corte Suprema de Kenia como un recordatorio del importante papel que el litigio estratégico puede desempeñar en la aplicación y promoción de los derechos de los refugiados.

A finite element model of perforated panel absorbers including viscothermal effects

Most of the analytical models devoted to determine the acoustic properties of a rigid perforated panel consider the acoustic impedance of a single hole and then use the porosity to determine the impedance for the whole panel. However, in the case of not homogeneous hole distribution or more complex configurations this approach is no longer valid. This work explores some of these limitations and proposes a finite element methodology that implements the linearized Navier Stokes equations in the frequency domain to analyse the acoustic performance under normal incidence of perforated panel absorbers. Some preliminary results for a homogenous perforated panel show that the sound absorption coefficient derived from the Maa analytical model does not match those from the simulations. These differences are mainly attributed to the finite geometry effect and to the spatial distribution of the perforations for the numerical case. In order to confirm these statements, the acoustic field in the vicinities of the perforations is analysed for a more complex configuration of perforated panel. Additionally, experimental studies are carried out in an impedance tube for the same configuration and then compared to previous methods. The proposed methodology is shown to be in better agreement with the laboratorial measurements than the analytical approach.

Refugiados en Serbia: de camino hacia una vida mejor

Más de 450 000 personas pasaron a través de Serbia desde que comenzó 2015 hasta mediados de noviembre. Sin embargo, en 2014 las cifras fueron ya elevadas e iban en aumento.