Proveniência da Titanite no Algarve (Sul de Portugal)

Com o objectivo de avaliar a proveniência da titanite existente nas praias e ribeiras do Algarve e avaliar o seu potencial para estudos de proveniência, foram estudadas diversas amostras recolhidas em afloramentos rochosos e em sedimentos detríticos de praias e ribeiras do Algarve (Sul de Portugal). A titanite, quando observada em grãos individuais com formas arredondadas pode ser facilmente confundida com a monazite. Nestes casos, recorreu-se à análise por difractometria de raios-X, tendo sido possível confirmar a identificação da titanite através de cálculos estequiométricos a partir dos elementos maiores. Nas amostras referentes aos sedimentos detríticos, a titanite foi observada em praticamente todas as amostras estudadas. Nas praias é abundante e arredondada. Nas ribeiras a titanite é igualmente abundante mas apresenta formas praticamente euédricas, em particular a sul do Maciço Ígneo de Monchique. As amostras dos afloramentos do Plio-Plistocénico também contêm titanite arredondada. As amostras correspondentes aos grauvaques do Paleozóico (Fm. Brejeira) são desprovidas de titanites. Nas amostras do Maciço Ígneo de Monchique foi observada uma grande quantidade de titanite muito angulosa e translúcida. Através das observações efectuadas foi possível concluir que a principal fonte de titanite para as ribeiras e praias do Algarve ocidental é o Maciço Ígneo de Monchique, revelando-se este mineral como um bom traçador sedimentar para estudos paleoambientais

Variability of detrital zircons from beaches and rivers in the western Algarve Region-South Portugal

Zircon is a common accessory mineral in most rocks and sediments, and although it is ubiquitous, it possesses a considerable petrologic interest. In the scope of CHYNA project, some samples of detrital sediments have been collected in rivers and beaches from Western Algarve region. The present work presents the results of the analyses undergone with the intent to document the existing zircons’ variability in these samples. The zircons from 22 samples have been analysed based on their shape, colour and inclusions. There is predominance of rounded and subrounded grains, generally colourless and without inclusions. Systematic differences between beaches and rivers are not observed, indicating that both environments have the same zircon sources.CHYNA project (POCTI/CTA/48375/2002), financed by the Fundação para a Ciência e Tecnologia (FCT), with FEDER and OE supports

Variabilidade dos Zircões de ribeiras e praias do Algarve Ocidental - dados preliminares

O Zircão é um mineral acessório comum na maioria das rochas, possuindo um considerável interesse petrológico por ser extremamente resistente à meteorização química e de amplo uso em estudos radiométricos (Heimlich et al., 1975). Devido à sua extrema resistência à meteorização e ao transporte, o zircão possui um carácter ubíquo nos sedimentos

G-Jsim: A GUI tool for wireless sensor networks simulation under J-Sim

“Copyright © [2008] IEEE. Reprinted from 12th Annual IEEE International Symposium on Consumer Electronics (ISCE 2008). ISBN:978-1-4244-2422-1. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.”A Wireless Sensor Network is composed of up to thousands of smart sensing nodes with processing unit and memory, sensing unit and wireless communication capabilities. Wireless Sensor Networks application spans from the military applications into almost every field we can think of. Several simulation tools are readily available, among them the J-Sim, a java-based simulator with growing interest by research and network developers alike. We propose to enhance J-Sim functionality with a Guided User Interface for Wireless Sensor Networks that dramatically increases the user-friendliness of the simulator. Also, we provide a free download web page for everyone to benefit

High-resolution digital 3D models of Algar do Penico Chamber: limitations, challenges, and potential

The study of karst and its geomorphological structures is important for understanding the relationships between hydrology and climate over geological time. In that context, we conducted a terrestrial laser-scan survey to map geomorphological structures in the karst cave of Algar do Penico in southern Portugal. The point cloud data set obtained was used to generate 3D meshes with different levels of detail, allowing the limitations of mapping capabilities to be explored. In addition to cave mapping, the study focuses on 3D-mesh analysis, including the development of two algorithms for determination of stalactite extremities and contour lines, and on the interactive visualization of 3D meshes on the Web. Data processing and analysis were performed using freely available open-source software. For interactive visualization, we adopted a framework based on Web standards X3D, WebGL, and X3DOM. This solution gives both the general public and researchers access to 3D models and to additional data produced from map tools analyses through a web browser, without the need for plug-ins

Cave chamber data modeling and 3D Web visualization

Underground caves and its specific structures are important for geomorphological studies. In this paper we present tools to identify and map speleothems by surveying cave chambers interiors. The cave chamber was surveyed using Terrestrial Laser Scanning to acquire point clouds with high level of detail for 3D model generation. This data with 45 million points is useful for either reconstruction, geomorphological studies or virtual visits of caves. With this point cloud we generated a 3D-mesh to represent the surface model of the cave chamber, which is important to study its geomorphological features. A topological structure of the 3D-mesh was also implemented to get an efficient algorithm to help identifying stalactites. The possibility to publish 3D data on the Web is of particular interest for the geospatial field. For this reason, it was decided to make the cave model available in the Web by developing a 3D graphical interface where users can navigate and interact with the three-dimensional models of the cave. For this Web3D framework it was used X3D, WebGL and X3DOM. Such solution does not require any additional plug-ins or components

Framework for 3D data modeling and Web visualization of underground caves using open source tools

Terrestrial Laser Scanning is a very useful technique for cave studies. This surveying method creates point clouds with high detail levels for 3D model generation, which is indeed useful for either reconstruction, geomorphological studies or virtual visits of caves. The present work generated a 3D model of a cave chamber and developed a framework for 3D data visualization on the Web. Identifying geomorphological structures is one of the goals of this project. The generated 3D-mesh represents the surface model of the cave chamber, which is important to study its geomorphological features. A topological structure of the 3D-mesh was implemented to get an efficient algorithm to help determining stalactites. The recognition and positioning of cave stalactites can provide information on hidden cave features responsible for cave geomorphology. The possibility to publish 3D data on the Web is of particular interest for the geospatial field. For this reason, it was decided to make the cave model available in the Web by developing a 3D graphical interface where users can navigate and interact with the threedimensional models of the cave. For this Web framework, X3D, WebGL and X3DOM were used. Such solution does not require any additional plug-ins or components

Modelação 3D de grutas

A representação computacional de objetos espaciais complexos, como é o caso de grutas, possui variados campos de aplicações em domínios técnicos, científicos e artísticos. A construção destas representações envolve múltiplas tecnologias de aquisição e processamento de grandes conjuntos de dados. O presente trabalho apresenta um caso prático de criação de um modelo 3D do interior da gruta Algar do Penico (Algarve, Portugal) a partir de um levantamento por laser scanning terrestre (LST), com objectivo de identificar e cartografar estruturas geomorfológicas. Além do objectivo principal, a concepção de um modelo tridimensional permite reconstruir ambientes realistas para aplicações no domínio da criação artística, como por exemplo, animação 3D e Realidade Virtual

A topological framework for interactive queries on 3D models in the web

Several technologies exist to create 3D content for the web. With X3D, WebGL, and X3DOM, it is possible to visualize and interact with 3D models in a web browser. Frequently, three-dimensional objects are stored using the X3D file format for the web. However, there is no explicit topological information, which makes it difficult to design fast algorithms for applications that require adjacency and incidence data. This paper presents a new open source toolkit TopTri (Topological model for Triangle meshes) for Web3D servers that builds the topological model for triangular meshes of manifold or nonmanifold models. Web3D client applications using this toolkit make queries to the web server to get adjacent and incidence information of vertices, edges, and faces. This paper shows the application of the topological information to get minimal local points and iso-lines in a 3D mesh in a web browser. As an application, we present also the interactive identification of stalactites in a cave chamber in a 3D web browser. Several tests show that even for large triangular meshes with millions of triangles, the adjacency and incidence information is returned in real time making the presented toolkit appropriate for interactive Web3D applications

Chemostratigraphy (TOC, 13C, 18O) around the Pliensbachian/Toarcian boundary in the reference section of Peniche (Lusitanian Basin, Portugal)

This work presents the chemostratigraphy analysis based on total organic carbon (TOC) and the evolution of the carbon and oxygen stable isotopes in the whole rock samples around the Pliensbachian/Toarcian boundary in the Peniche section (uppermost part of Lemede Formation and lowermost part of Cabo Carvoeiro Formation). These are partial results which form part of a group of studies, being processed, that include isotope analyses of 87Sr/86Sr, 18O, 13C and major, minor and trace elements in whole rock and belemnites