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A three-dimensional acoustics model using the method of fundamental solutions

The method of fundamental solutions (MFS) is formulated in the frequency domain to model the sound wave propagation in three-dimensional (3D) enclosed acoustic spaces. In this model the solution is obtained by approximation, using a linear combination of fundamental solutions for the 3D Helmholtz equation. Those solutions relate to a set of virtual sources placed over a surface placed outside the domain in orde...

Development of resources for computer-based testing in campus-wide IT systems

The aim of this work is to give a brief account of an ongoing project at the University of Porto which aims to connect two different fields of teaching and learning: e-learning and computer-based assessment. Although these are contiguous areas, related to each other, there are some issues that rise from the use of computers to engage assessment activities. The University of Porto started a vigorous project of e...

CA 125 half-life breakpoint between a “good” and “poor” prognosis in patients w...

2.5D scattering of waves by rigid inclusions buried under a fluid channel via BEM

A 2.5D Boundary Element Method (BEM) formulation, applied in the frequency domain, is developed to compute the scattering of waves by rigid inclusions buried in a semi-infinite solid under a fluid layer, when this system is excited by a spatially-sinusoidal harmonic load. ; http://www.sciencedirect.com/science/article/B6VKW-4G7G4FV-2/1/d8e95042c45a6fad34ce3dae672a00ff

EFFECT OF THE IONOSPHERE OF LOW LATITUDES IN GPS - SBAS (GLOBAL SYSTEM POSITION...

The low-latitude ionosphere has some features that could cause problems even to the joint GPS/SBAS operation. Among them, one finds the equatorial anomaly, whose electronic density - and thus its refractive index - can present intense horizontal gradients. These gradients can be intense enough to induce errors in the predictions by the GPS/SBAS. To analyze this problem, a computer simulation program has been de...

Protecção integrada em tomate de indústria: modelo de previsão do míldio

In Portugal, the processing tomato is of great economical importance. The maintenance of the quality of the final product is of growing preoccupation due to the ever increasing consumer demand. IPM has been considered as the best alternative due to the guarantee of some of these demands, in particular the non existence of pesticide residues. The objectives of the work carried out in the Ribatejo were to establi...

Wave motion between two fluid-filled boreholes in an elastic medium

The boundary element method (BEM) is used to fully simulate the propagation of waves between two fluid-filled boreholes. The sources are placed in one of the boreholes while the receivers are placed in the other. This model is frequently used in cross-hole seismic prospecting techniques to assess the characteristics of the elastic medium between the two boreholes. This work studies the dependence of the wave pr...