Protecção contra descargas atmosféricas: aplicação informática de identificação das vulnerabilidades das edificações e de apoio à concepção da protecção

A concepção de instalações eléctricas deve garantir condições de segurança para as pessoas e equipamentos. Para tal é exigida, quer por força de regulamentação ou de normalização, a instalação de dispositivos que garantam a detecção e a protecção contra os defeitos mais comuns nas instalações eléctricas como, por exemplo, as sobreintensidades e as sobretensões. Susceptíveis de criar sobretensões perigosas nas instalações eléctricas, as descargas atmosféricas podem ainda causar danos estruturais elevados, o que, em algumas actividades económicas, torna fundamental a implementação de medidas de protecção contra este fenómeno natural. A protecção contra descargas atmosféricas directas consiste em identificar as vulnerabilidades das estruturas e, nesses locais, implementar dispositivos de captura, direccionamento e escoamento da descarga atmosférica à terra, em condições de segurança. O presente trabalho, desenvolvido no âmbito da dissertação de Mestrado em Engenharia Electrotécnica, visa desenvolver e implementar uma ferramenta computacional, baseada em programas de desenho assistido por computador (CAD) de utilização corrente na área de projecto de arquitectura e de engenharia, que permita, no âmbito de normas internacionais, a análise e implementação de sistemas de protecção em edifícios contra descargas atmosféricas de uma forma rápida e expedita. Baseado num programa CAD 3D, que permite a modelização tridimensional das estruturas a proteger, a ferramenta desenvolvida tentará identificar as suas vulnerabilidades das estruturas às descargas atmosféricas directas, com o intuito de implementar as medidas de protecção mais adequadas do ponto de vista técnico económico. Prevê-se que a ferramenta resultante deste estudo, o Simulador do Modelo Electrogeométrico (SIMODEL), possibilite aos projectistas e particularmente aos alunos das unidades curriculares na área do projecto de instalações eléctricas da Área Departamental de Engenharia de Sistemas e Potencia e Automação (ADESPA) do ISEL, estudar e implementar sistemas de protecção contra descargas atmosféricas (SPDA) baseados na normalização internacional do CENELEC e da IEC, nomeadamente as normas da série 62305.

Efeito do tolueno e ruído na génese de perda auditiva ocupacional: projecto de investigação

Mestrado em Higiene e Segurança no Trabalho

Damage detection and quantification using transmissibility

Structures experience various types of loads along their lifetime, which can be either static or dynamic and may be associated to phenomena of corrosion and chemical attack, among others. As a consequence, different types of structural damage can be produced; the deteriorated structure may have its capacity affected, leading to excessive vibration problems or even possible failure. It is very important to develop methods that are able to simultaneously detect the existence of damage and to quantify its extent. In this paper the authors propose a method to detect and quantify structural damage, using response transmissibilities measured along the structure. Some numerical simulations are presented and a comparison is made with results using frequency response functions. Experimental tests are also undertaken to validate the proposed technique. (C) 2011 Elsevier Ltd. All rights reserved.

Analysis of a 17.9 kb region from Saccharomyces cerevisiae chromosome VII reveals the presence of eight open reading frames, including BRF1 (TFIIIB70) and GCN5 genes

We report the nucleotide sequence of a 17,893 bp DNA segment from the right arm of Saccharomyces cerevisiae chromosome VII. This fragment begins at 482 kb from the centromere. The sequence includes the BRF1 gene, encoding TFIIIB70, the 5' portion of the GCN5 gene, an open reading frame (ORF) previously identified as ORF MGA1, whose translation product shows similarity to heat-shock transcription factors and five new ORFs. Among these, YGR250 encodes a polypeptide that harbours a domain present in several polyA binding proteins. YGR245 is similar to a putative Schizosaccharomyces pombe gene, YGR248 shows significant similarity with three ORFs of S. cerevisiae situated on different chromosomes, while the remaining two ORFs, YGR247 and YGR251, do not show significant similarity to sequences present in databases.

Sequencing of a 9.9 kb segment on the right arm of yeast chromosome VII reveals four open reading frames, including PFK1, the gene coding for succinyl-CoA synthetase (beta-chain) and two ORFs sharing homology with ORFs of the yeast chromosome VIII

A 9.9 kb DNA fragment from the right arm of chromosome VII of Saccharomyces cerevisiae has been sequenced and analysed. The sequence contains four open reading frames (ORFs) longer than 100 amino acids. One gene, PFK1, has already been cloned and sequenced and the other one is the probable yeast gene coding for the beta-subunit of the succinyl-CoA synthetase. The two remaining ORFs share homology with the deduced amino acid sequence (and their physical arrangement is similar to that) of the YHR161c and YHR162w ORFs from chromosome VIII.

Sequencing of a 17.6 kb segment on the right arm of yeast chromosome VII reveals 12 ORFs, including CCT, ADE3 and TR-I genes, homologues of the yeast PMT and EF1G genes, of the human and bacterial electron-transferring flavoproteins (beta-chain) and of the Escherichia coli phosphoserine phosphohydrolase, and five new ORFs.

A 17.6 kb DNA fragment from the right arm of chromosome VII of Saccharomyces cerevisiae has been sequenced and analysed. The sequence contains twelve open reading frames (ORFs) longer than 100 amino acids. Three genes had already been cloned and sequenced: CCT, ADE3 and TR-I. Two ORFs are similar to other yeast genes: G7722 with the YAL023 (PMT2) and PMT1 genes, encoding two integral membrane proteins, and G7727 with the first half of the genes encoding elongation factors 1gamma, TEF3 and TEF4. Two other ORFs, G7742 and G7744, are most probably yeast orthologues of the human and Paracoccus denitrificans electron-transferring flavoproteins (beta chain) and of the Escherichia coli phosphoserine phosphohydrolase. The five remaining identified ORFs do not show detectable homology with other protein sequences deposited in data banks. The sequence has been deposited in the EMBL data library under Accession Number Z49133.

Ensaios em pontes

Dissertação para a obtenção do grau de Mestre em Engenharia Civil na Área de Especialização em Estruturas

Contribuição para a definição de procedimentos de inspeção de edifícios correntes após um sismo

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil

Water quality in lakes and reservoirs in China

Dissertation elaborated for the partial fulfilment of the requirements of the Master Degree in Civil Engineering in the Speciality Area of Hydarulics

Micronutrients intake associated with DNA damage assessed by in a human biomonitoring study

Nutrition science has evolved into a multidisciplinary field that applies molecular biology and integrates individual health with the epidemiologic investigation of population health. Nutritional genomics studies the functional interaction of food and its components, macro and micronutrients, with the genome at the molecular, cellular, and systemic level. Diet can influence cancer development in several ways, namely direct action of carcinogens in food that can damage DNA, diet components (macro or micronutrients) that can block or induce enzymes involved in activation or deactivation of carcinogenic substances. Moreover, inadequate intake of some molecules involved in DNA synthesis, repair or methylation can influence mutation rate or changes in gene expression. Several studies support the idea that diet can influence the risk of cancer; however information concerning the precise dietary factor that determines human cancer is an ongoing debate. A lot of epidemiological studies, involving food frequency questionnaires, have been developed providing important information concerning diet and cancer, however, diet is a complex composite of various nutrients (macro and micronutrients) and non-nutritive food constituents that makes the search for specific factors almost limitless.

Damage detection in structures using a transmissibility-based Mahalanobis distance

In this paper, a damage-detection approach using the Mahalanobis distance with structural forced dynamic response data, in the form of transmissibility, is proposed. Transmissibility, as a damage-sensitive feature, varies in accordance with the damage level. Besides, Mahalanobis distance can distinguish the damaged structural state condition from the undamaged one by condensing the baseline data. For comparison reasons, the Mahalanobis distance results using transmissibility are compared with those using frequency response functions. The experiment results reveal quite a significant capacity for damage detection, and the comparison between the use of transmissibility and frequency response functions shows that, in both cases, the different damage scenarios could be well detected. Copyright (c) 2015 John Wiley & Sons, Ltd.

Single side damage simulations and detection in beam-like structures

Beam-like structures are the most common components in real engineering, while single side damage is often encountered. In this study, a numerical analysis of single side damage in a free-free beam is analysed with three different finite element models; namely solid, shell and beam models for demonstrating their performance in simulating real structures. Similar to experiment, damage is introduced into one side of the beam, and natural frequencies are extracted from the simulations and compared with experimental and analytical results. Mode shapes are also analysed with modal assurance criterion. The results from simulations reveal a good performance of the three models in extracting natural frequencies, and solid model performs better than shell while shell model performs better than beam model under intact state. For damaged states, the natural frequencies captured from solid model show more sensitivity to damage severity than shell model and shell model performs similar to the beam model in distinguishing damage. The main contribution of this paper is to perform a comparison between three finite element models and experimental data as well as analytical solutions. The finite element results show a relatively well performance.