Encontrados 112 documentos, a visualizar página 1 de 12
A topological framework for interactive queries on 3D models in the web
Figueiredo, Mauro; Rodrigues, J. I.; Silvestre, Ivo; Veiga-Pires, C.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 dat...
Does banning price discrimination promote entry and increase welfare? A model o...
Jorge, S.F.; Pires, C.P.In this paper we investigate the impact of firms’ pricing policies upon entry and welfare under duopoly price competition and product differentiation. We consider a model where an incumbent serves two distinct and independent geographical markets and an entrant may enter in one of the markets. Our results show that discriminatory pricing may be either more, less or equally favorable to entry than uniform pricin...
Foraminifera as tsunami tracers in Holocene sequences of Southwestern Spain
Guerra, L.; Ruiz, F.; Abad, Manuel; Veiga-Pires, C.El objetivo de este trabajo es la identificación de eventos de alta energia (tsunamis?) em el P.N. de Doñana a partir del análisis de asociaciones de foraminíferos, llevando a cabo en un testigo corto, y comparar estos datos con el registro del Tsunami de 1755 que tuvo lugar en el SO de la Península Ibérica, donde los foraminíferos se han mostrado como indicadores muy útiles para caracterizar los paleoambientes...
Morpho-sedimentary evidence of Holocene tsunamis in Southwestern Spain estuarie...
Ruiz, F.; Rodriguez-Vidal, J.; Cáceres, L. M.; Carretero, M. I.; Pozo, Manuel; Gómez-Toscano, F.; Izquierdo, T.; Font, Eric; Guerra, L.; Veiga-Pires, C.Los estuarios constituyen sistemas costeros excelentes para registrar tsunamis a través de un amplio tipo de evidencias geológicas. Este trabajo revisa y resume las evidencias de tsunamis prehistóricos e históricos en los quatro principales estuarios del suroeste de España. Las más frecuentes son erosión de playas y retroceso del litoral, ruptura y desbordamiento de flechas arenosas y depósito de capas bioclást...
Benchmarks, sediment source and hydrodynamics of the 1755 Lisbon tsunami deposi...
Font, Eric; Veiga-Pires, C.; Pozo, Manuel; Nave, Silvia; Costas, Susana; Muñoz, Francisco Ruiz; Abad, Manuel; Simões, Nuno; Duarte, SílviaStandardizing the signature of tsunami deposits has been pointed as a major limitation on the identification of paleo-tsunami deposits. This limitation majorly arises from the strongly source-dependent nature of these deposits, which in turn determines their composition and structure, and from the effect of the local morphology of the corresponding depositional environment. Here, we provide new high-resolut...
Magnetic fingerprints of stalagmites
Font, Eric; Veiga-Pires, C.; Camps, Pierre; Carvallo, Claire; Neto, António; Pozo, Manuel; Mirão, JoséDating stalagmite usi ng paleomagnetic methods is still in its early stage of development. Questions still remain regarding the nature and origin of the magnetic carriers and the reliability of the natural remanent magnetization preserved within the thin carbonat ed laminations of stalagmites. Here we apply high - resolution rock - and paleo - magnetic methods on two (altered and preserved) stalagmites in order...
Atmospheric halogen and acid rains during the major Deccan episode: magnetic an...
Font, Eric; Fabre, Sébastien; Nédélec, Anna; Adatte, Thierry; Keller, Gerta; Veiga-Pires, C.; Ponte, J.; Mirão, José; Khozyem, HassanEnvironmental and climatic changes linked to Deccan volcanism are still poorly known. A major limitation resides in the paucity of direct Deccan volcanism markers and in the geologically short interval where both impact and volcanism occurred, making it hard to evaluate their contributions to the mass extinction. We investigated the low magnetic susceptibility interval just below the Iridium-rich layer of the B...
Cave chamber data modeling and 3D Web visualization
Silvestre, Ivo; Rodrigues, J. I.; Figueiredo, Mauro; Veiga-Pires, C.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, geomorphologica...
An open source geophysical software for studying speleothem growth bands and co...
Veiga-Pires, C.; Coelho, Catarina; Moura, Delminda; Luis, JoaquimSpeleothem growth bands are commonly referred as one of the parameters that are used for paleoclimate reconstructions. Accordingly, this work presents a new tool for detecting these bands based on the gray-scale image of the speleothem using the Mirone open source geophysical software. This program has initially been developed for working on georeferenciated images for geophysical studies, as for instance f...
Framework for 3D data modeling and Web visualization of underground caves using...
Silvestre, Ivo; Veiga-Pires, C.; Rodrigues, J. I.; Figueiredo, MauroTerrestrial 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 geomorphologica...
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