The use of monopole and dipole sources in crosswell surveying

This paper implements a boundary element method (BEM) solution, formulated in the frequency domain, to simulate the crosswell S wave surveying technique. In this technique, one fluid-filled borehole hosts the source, and the other the receivers. The system is excited by a monopole or a dipole source placed near the first wall of the borehole wall, while the pressure field is recorded in the second borehole. The three-dimensional solution is computed as a summation of 2.5D solutions for different axial wave numbers.This model is used to assess the influence of the distance between boreholes and the material properties of the medium on the pressure field generated in the second borehole. Slow and fast formations are both simulated. It was found that the responses recorded the contribution of the non-dispersive body waves (the dilatational (P) and shear (S) waves) as well as the effect of dispersive waves associated with different wave modes. The final time solutions are thus intricate, exhibiting wave patterns that may make it difficult to interpret the arrival times of the refracted P and S waves.http://www.sciencedirect.com/science/article/B6VFC-4D60GGB-2/1/08a72e22c052b611259a58399a80630

Influence of the cross-section geometry of a cylindrical solid submerged in an acoustic medium on wave propagation

This paper studies wave propagation in the vicinity of a cylindrical solid formation submerged in an acoustic medium generated by point blast loads placed outside the inclusion. The full 3D solution is obtained first in the frequency domain as a discrete summation of responses for 2D problems defined by a spatial Fourier transform. Each 2D solution is computed using the Boundary Element Method, which makes use of two-and-a-half-dimensional Green's functions. This model is implemented to obtain Fourier spectra responses which make it possible to identify the behavior of both the axisymmetric and non-axisymmetric guided wave modes, when the cross-section of the elastic inclusion changes from circular to smooth oval.http://www.sciencedirect.com/science/article/B6TW5-44W4412-2/1/730c9aeee648dd67ed04d4a46003f0a

Response of clamped structural slabs subjected to a dynamic point load via BEM

This work computes the response of clamped slabs when subjected to spatially sinusoidal harmonic line loads via the Boundary Element Method (BEM). The formulation uses 2.5D Green's functions for the steady state response of a homogeneous three-dimensional free solid layer formation of infinite extent, proposed earlier by the authors. The inclusion of these Green's functions in the BEM formulation avoids the discretization of free horizontal surfaces, which contributes to the efficiency of the BEM model. Frequency and time responses have been computed for slabs with and without lateral confinements, for different thickness and varying spatially sinusoidal harmonic line loads.http://www.sciencedirect.com/science/article/B6V2Y-478B3WC-2/1/858485466df347cb0aab610316d65e7

3D scattering of waves by a cylindrical irregular cavity of infinite length in a homogeneous elastic medium

http://www.sciencedirect.com/science/article/B6V29-459J6W9-3/1/3d445629b57a8b1547f3638751751d3

Thermal performance and cost analysis of mortars made with PCM and different binders

The high energetic consumption is one of the biggest concerns of modern society. The incorporation of phase change materials (PCM) in construction materials allows regulates the temperature inside the buildings. The main objective of this study was the characterization of the thermal performance of PCM mortars based in different binders. It was possible to observe that the incorporation of PCM in mortars leads to a decrease of the maximum temperatures, increase of the minimum temperatures, significant lag time delay, reduction of the heating and cooling needs, and consequent decrease of the cost of HVAC systems operation, for all tested seasons.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) for the financial support of PhD scholarship SFRH/BD/95611/2013

Modelling of acoustic and elastic wave propagation from underground structures using a 2.5D BEM-FEM approach

This paper presents a numerical method based on a two-and-a-half dimensional (2.5D) boundary element-finite element (BEM-FEM) coupled formulation to study noise and vibration from underground structures. The proposed model properly represents the soil-structure interaction problem and the radiated noise and vibration. The soil is modelled with the boundary element method, and the Green's function for a fluid-solid formation is taken as the fundamental solution to represent a solid half-space flattened by a fluid medium, which represents the soil and the air above the ground surface. The finite element method is used to represent structures and enclosed air volumes. The problem representation is limited to a soil-structure interface and the ground surface does not need to be discretised. Radiated noise and vibration are determined after the soil-structure interaction problem has been solved. We verify the proposed method by comparing the solution with an analytical solution for the wave propagation in a fluid-solid medium. Three examples are given to illustrate the noise and vibration radiated by tunnels. The results show that the soil-structure interaction influences the sound pressure field above the ground surfaceMinisterio de Economía y Competitividad BIA2013-43085-

Um estudo acerca de pesquisas brasileiras que versam sobre professor formador de professores que ensinam matemática e suas concepções

Neste texto temos por objetivo a análise de pesquisas brasileiras que têm como foco de estudo o professor formador de professores que ensinam Matemática e suas concepções, produzidas no período de 2001 a 2012, cuja intenção é responder à seguinte questão: que concepões são abordadas nas pesquisas acerca dos professores formadores? As informações que compõem o corpus da nossa investigação são oriundas de uma pesquisa em âmbito nacional, enquadrada num projeto coordenado pelo Grupo de Estudos e Pesquisas sobre Formação de Professores de Matemática, para mapear e fazer o estado da arte da pesquisa brasileira sobre o professor que ensina Matemática. A metodologia seguida assenta numa abordagem qualitativa de cunho documental. Destacamos que do total de 858 pesquisas (teses e dissertações), 41 se referem aos professores formadores. Esse é um dos resultados do projeto expresso no e-book publicado, e que chama nossa atenção para o número reduzido de investigações com esse foco, bem como para o conteúdo dessas pesquisas ao se referirem as concepções desses formadores. As pesquisas tentam compreender concepções acerca da formação do formador, dos projetos pedagógicos de cursos, de tendências em Educação Matemática, acerca de um conteúdo específico, da Matemática e seu ensino

Mortars based in different binders with incorporation of phase-change materials: Physical and mechanical properties

In a society with a high growth rate and increased standards of comfort arises the need to minimise the currently high-energy consumption by taking advantage of renewable energy sources. The mortars with incorporation of phase-change materials (PCM) have the ability to regulate the temperature inside buildings, contributing to the thermal comfort and reduction in the use of heating and cooling equipment, using only the energy supplied by the sun. However, the incorporation of phase-change materials in mortars modifies its characteristics. The main purpose of this study was the production and characterisation in the fresh and hardened state of mortars with incorporation of different contents of PCM in mortars based in different binders. The binders studied were aerial lime, hydraulic lime, gypsum and cement. For each type of binder, different mortars were developed with different content of PCM. The proportion of PCM studied was 0, 20, 40 and 60% of the mass of the sand. It was possible to observe that the incorporation of PCM in mortars caused differences in properties such as workability, microstructure, compressive strength, flexural strength and adhesion.Foundation for Science and Technology (FCT), followed by the grant number [SFRH/BD/95611/2013

Influence of adding encapsulated phase change materials in aerial lime based mortars

Increasingly in a society with a high growth rate and standards of comfort, the need to minimize the currently high energy consumption by taking advantage of renewable energy sources arises. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing for an increase in the level of thermal comfort and reduction of the use of heating, ventilation and air conditioning (HVAC) equipment, using only the energy supplied by the sun. However, the incorporation of PCM in mortars modifies some of its characteristics. Therefore, the main objective of this study was the characterization of mortars doped with two different phase change materials. Specific properties of different PCM, such as particle size, shape and enthalpy were studied, as well as the properties of the fresh and hardened state of these mortars. Nine different compositions were developed which were initially doped with microcapsules of PCM A and subsequently doped with microcapsules of PCM B. It was possible to observe that the incorporation of phase change materials in mortars causes differences in properties such as compressive strength, flexural strength and shrinkage. After the study of the behaviour of these mortars with the incorporation of two different phase change materials, it was possible to select the composition with a better compromise between its aesthetic appearance, physical and mechanical characteristics.Fundação para a Ciência e Tecnologia (FCT