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DSpace - Universidade do Porto (64,956 recursos)
Este repositório institucional visa coleccionar, preservar e disponibilizar na Internet a produção intelectual da comunidade académica da U.PORTO. Apenas as publicações em texto integral e de acesso livre (sob as condições de licença pública Creative Commons)fazem parte deste repositório. Informações adicionais sobre outras publicações encontram-se em

FCUP - Artigo em Acta de Conferência Internacional

Mostrando recursos 1 - 12 de 12

1. Intercomparison between existing wet tropospheric corrections for coastal altimetry,

2. Evaluating MODIS vegetation indices using ground based measurements in a mountains semi-natural meadows of northeast Portugal

3. Validation of coastal altimetry data along the west Iberian coast

4. Probabilistic surface change detection and measurement from digital aerial stereo images
We propose a new method to measure changes in terrain topography from two optical stereo image pairs acquired at different dates. The main novelty is in the ability of computing the spatial distribution of uncertainty, thanks to stochastic modeling and probabilistic inference. Thus, scientists will have access to quantitative error estimates of local surface variation, so they can check the statistical significance of elevation changes, and make, where changes have occurred, consistent measurements of volume or shape evolution. The main application area is geomorphology, as the method can help study phenomena such as coastal cliff erosion, sand dune displacement and various transport mechanisms through the...

5. The use of similarity images on multi-sensor automatic image registration
Automatic image registration (AIR) is still a present challenge regarding remote sensing applications. Although several methods have been proposed in the last few years, geometric correction is often a time and effort consuming manual task. The only AIR method which is commonly used is the correlation-based template matching method. It usually consists on considering a window from one image and passing it throughout the other, looking for a maximum of correlation, which may be associated to the displacement between the two images. This approach leads sometimes (for example with multi-sensor image registration) to low correlation coefficient values, which do not give sufficient confidence to associate...

6. Progress in coastal altimetry: outcomes of the COASTALT Project

7. A Comparative Study of Satellite and Ground-Based Vineyard Phenology

Beaches in the Portuguese western coast suffer sudden changes due to the action of the sea during winter. Frequent acquisition of digital surface models (DSM) is needed in order to assess volumetric changes. This paper presents a monitoring program carried in an area of 15 km near the city of Porto. Digital aerial photography is acquired twice a year, using a Zeiss-Intergraph DMC camera, with a spatial resolution of 10 cm, by a local company. Images are provided with exterior orientation provided by direct georeferencing equipment. An assessment of the exterior orientation parameters provided was done using field survey points. It could be concluded that...

9. Deployment and evaluation of a usage based collaborative filtering recommendation system with blacklists
Social web sites, like Palco Principal (PP), have considerably sized databases with the most varied types of information from user subscription information to user interactions. All that information is susceptible of being processed using data mining algorithms in order to extract knowledge relevant for the business. This document describes the implementation and evaluation of a system that uses data mining techniques, and that has been developed with the specific intent of generating recommendations, namely music recommendations, to users of the PP web site. The implemented system uses collaborative filtering techniques to recommend music additions to a user’s playlist. The impact of the deployed system has been evaluated online.

10. Kostia Beidar's contribution to module and ring theory
At the beginning of his mathematical career Kostia Beidar was working on rings with polynomial identities and primeness conditions for rings. By Posner’s theorem the two-sided quotient ring of a prime PI-ring is a finite matrix ring over some field. This result was extended by Martindale to rings with generalised polynomial identities by the construction of the central closure of a prime ring. Kostia was working extensively in this setting and made crucial contributions to the understanding of the theory. While his contribution to general PI theory will be outlined elsewhere we want to sketch here his work on prime rings and...

11. Comparability, distributivity and non-commutative φ-rings.
The purpose of this paper is to develop the theory of non-commutative φ-rings using concepts from distributive rings and rings with comparability. We recover the main statements for commutative φ-rings as obtained by Anderson and Badawi.

12. The splitting of the dual Goldie torsion theory
The splitting of the Goldie (or singular) torsion theory has been extensively studied. Here we determine an appropriate dual Goldie torsion theory, discuss its splitting and answer in the negative a question proposed by Ozcan and Harmanci as to whether the splitting of the dual Goldie torsion theory implies the ring to be quasi-Frobenius.


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