Development of the Structure of a long Endurance Electric UAV

The goal of this project is to design and create the structure of a long endurance unmanned aerial vehicle (UAV) using solar power. The design’s main requirement was the creation of a low weight structure to handle diverse missions with a 1 Kilogram of payload. The UAV structure was divided in three parts: fuselage, empennages and empennage support, designed using CATIA® to verify interfaces and to study the positioning of the systems access and functionality. Because the main target is to build a low weight structure, the carbon fibre and wood were chosen for the fuselage, empennage support and tail, respectively. Two methods of structure analyses were used to design the composite structures, one a numerical analysis and the other the finite element method from ANSYS®. The UAV structure was manufactured in two phases. First was the composite structure using the hand lay-up and vacuum bagging method. And the second was the empennage structure using balsa wood construction. When the UAV structure was finished, a structural test was carried out to verify both analysis and manufacturing methods.Este trabalho tem como objetivo o desenvolvimento e criação da estrutura de um avião não tripulado (UAV) de longa autonomia movido a energia solar. O desenvolvimento teve como principal objetivo a criação de uma estrutura suficientemente leve, para poder efetuar diversas missões com uma carga útil de 1 Kg. A estrutura do UAV foi dividida em três partes, as quais compreendem: a fuselagem, empenagens e suporte de empenagens. Estas foram projetadas utilizando o CATIA® para verificar as interfaces e para estudar posições de acesso e funcionalidade. Dado que o objetivo principal é de uma estrutura leve, foi utilizado como material a fibra de carbono para a fuselagem e suporte de empenagens e a madeira para as empenagens. A estrutura em compósito foi dimensionada utilizando dois métodos: método numérico e método computacional, com recurso ao software de elementos finitos ANSYS®. A produção da estrutura do UAV foi executada em duas fases. A primeira foi a estrutura em compósito utilizando o método de hand lay-up e vacuum baggin method. E a segunda as estruturas das empenagens, utilizando os métodos de construção em madeira. Produzida toda a estrutura, foram efetuados testes estruturais para verificação de todos os métodos de construção bem como da análise estrutural

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved