Maximum level and time to peak of dam-break waves on mobile horizontal bed

Journal of Hydraulic Engineering, Vol. 135, No. 11, November 1, 2009

The contribution of multitemporal information from multispectral satellite images for automatic land cover classification at the national scale

Thesis submitted to the Instituto Superior de Estatística e Gestão de Informação da Universidade Nova de Lisboa in partial fulfillment of the requirements for the Degree of Doctor of Philosophy in Information Management – Geographic Information Systems

In situ measured cross section geometry of old timber structures and its influence on structural safety

Old timber structures may show significant variation in the cross section geometry along the same element, as a result of both construction methods and deterioration. As consequence, the definition of the geometric parameters in situ may be both time consuming and costly. This work presents the results of inspections carried out in different timber structures. Based on the obtained results, different simplified geometric models are proposed in order to efficiently model the geometry variations found. Probabilistic modelling techniques are also used to define safety parameters of existing timber structures, when subjected to dead and live loads, namely self-weight and wind actions. The parameters of the models have been defined as probabilistic variables, and safety of a selected case study was assessed using the Monte Carlo simulation technique. Assuming a target reliability index, a model was defined for both the residual cross section and the time dependent deterioration evolution. As a consequence, it was possible to compute probabilities of failure and reliability indices, as well as, time evolution deterioration curves for this structure. The results obtained provide a proposal for definition of the cross section geometric parameters of existing timber structures with different levels of decay, using a simplified probabilistic geometry model and considering a remaining capacity factor for the decayed areas. This model can be used for assessing the safety of the structure at present and for predicting future performance.

Evolution of Iberia during the Cenozoic with special emphasis on the formation of the Betic Cordillera and its relation with the western Mediterranean

The extensional process affecting Iberia during the Triassic and Jurassic times change from the end of the Cretaceous and, throughout the Palaeocene, the displacement between the African and European plates was clearly convergent and part of the future Internal Zone of the Betic Cordillera was affected. To the west, the Atlantic continued to open as a passive margin and, to the north, no significant deformation occurred. During the Eocene, the entire Iberian plate was subjected to compression. which caused major deformations in the Pyrenees and also in the Alpujarride and Nevado-Filabride, Internal Betic, complexes. In the Oligocene continued this situation, but in addition, the new extensional process ocurring in the western Mediterranean area, together with the constant eastward drift of Iberia due to Atlantic opening, compressed the eastern sector of Iberia, giving rise to the structuring of the Iberian Cordillera. The Neogene was the time when the Betic Cordillera reached its fundamental features with the westward displacement of the Betic-Rif Internal Zone, expelled by the progressive opening of the Algerian Basin, opening prolonged till the Alboran Sea. From the late Miocene onwards, all Iberia was affected by a N-S to NNW-SSE compression, combined in many points by a near perpendicular extension. Specially in eastern and southern Iberia a radial extension superposed these compression and extension.

On the hydrogeology of the Lower Tagus Basin and its Cenozoic geologic evolution

The chemical features of the ground water in the Lower Tagus Cenozoic deposits are strongly influenced by lithology, by the velocity and direction of the water movement as well as by the localization of the recharge and discharge zones. The mineralization varies between 80 and 900 mg/l. It is minimal in the recharge zones and in the Pliocene sand and maximum in the Miocene carbonated and along the alluvial valley. Mineralization always reflects the time of permanence, the temperature and the pressure. The natural process of water mineralization is disturbed in agricultural areas because the saline concentration of the infiltration water exceeds that of the infiltrated rainwater. In the discharge zones, the rise of the more mineralized, some times thermal deep waters related to tectonic accidents give rise to anomalies in the distribution of the aquiferous system mineralization model. The diversity of the hydrochemical facies of the ground water may be related to several factors whose identification is some times difficult.

Time-domain optimization of amplifiers based on distributed genetic algorithms

Thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Electrical and Computer Engineering

Evolution of genotypes of Group A streptococci from colonization and infection

Dissertação para obtenção do Grau de Doutor em Biologia

The Evolution of Population Distribution on the Iberian Peninsula: A Transnational Approach (1877–2001)

Surpassing the national perspective usually adopted, the authors confirmed the existence of a pattern of population distribution common to the whole Iberian Peninsula in the long run. This pattern is clearly associated with geographical factors. These variables seem to have more weight in explaining changes between 1877/78 and 1940 than in the period from 1940 to 2001. The observation of the cross-border region has shown that proximity to the frontier has not generated any distinct pattern of population density on either side of the boundary line. The spatial coherence of the observed phenomena throughout the Peninsula and of its evolution, independent of the border between states, reinforces the importance of geographic factors in their explanation. At the same time, this verification opens up new issues related to the effect of national political and economic policies.

Positive self-image over time

This paper incorporates egocentric comparisons into a human capital accumulation model and studies the evolution of positive self image over time. The paper shows that the process of human capital accumulation together with egocentric comparisons imply that positive self image of a cohort is first increasing and then decreasing over time. Additionally, the paper finds that positive self image: (1) peaks earlier in activities where skill depreciation is higher, (2) is smaller in activities where the distribution of income is more dispersed, (3) is not a stable characteristic of an individual, and (4) is higher for more patient individuals.

Evolution of Diplodocid Sauropod dinosaurs with emphasis on specimens from Howe Ranch, Wyoming (USA)

Diplodocidae are among the best known sauropod dinosaurs. Several species were described in the late 1800s or early 1900s. Since then, numerous additional specimens were recovered in the USA, Tanzania, Portugal, as well as possibly Spain, England, and Asia. To date, the clade includes about 12 to 15 different species, some of them with questionable taxonomic status (e.g. ‘Diplodocus’ hayi or Dyslocosaurus polyonychius). However, intrageneric relationships of the multi-species, iconic genera Apatosaurus and Diplodocus are still poorly known. The way to resolve this issue is a specimen-based phylogenetic analysis, which was done for Apatosaurus, but is here performed for the first time for the entire clade of Diplodocidae. New material from different localities and stratigraphic levels on the Howe Ranch (Shell,Wyoming, USA) sheds additional light on the evolution of Diplodocidae. Three new specimens are described herein, considerably increasing our knowledge of the anatomy of the group. The new specimens (SMA 0004, SMA 0011, and SMA 0087) represent two, to possibly three new diplodocid species. They preserve material from all parts of the skeleton, including two nearly complete skulls, as well as fairly complete manus and pedes, material which is generally rare in diplodocids. Thereby, they considerably increase anatomical overlap between the sometimes fragmentary holotype specimens of the earlier described diplodocid species, allowing for significant results in a specimenbased phylogenetic analysis. Furthermore, clavicles and interclavicles are identified, the latter for the first time in dinosaurs. Their presence seems restricted to early sauropods, flagellicaudatans, and early Macronaria, and might thus be a retained plesiomorphy, with the loss of these bones being synapomorphic for Titanosauriformes and possibly Rebbachisauridae. The new material allows to test previous hypotheses of diplodocid phylogeny. In order to do so, any type specimen previously proposed to belong to Diplodocidae was included in the study, as are relatively complete referred specimens, in order to increase the degree of overlapping material. For specimens subsequently suggested to be non-diplodocid sauropods, their hypothesized sister taxa were included as outgroups. The current phylogenetic analysis thus includes 76 operational taxonomic units, 45 of which belong to Diplodocidae. The specimens were scored for 477 morphological characters, representing one of the most extensive phylogenetic analyses done within sauropod dinosaurs. The resulting cladogram recovers the classical arrangement of diplodocid relationships. Basing on a newly developed numerical approach to reduce subjectivity in the decision of specific or generic separation, species that have historically been included into well-known genera like Apatosaurus or Diplodocus, were detected to be actually generically different. Thereby, the famous genus Brontosaurus is resuscitated, and evidence further suggests that also Elosaurus parvus (previously referred to Apatosaurus) or ‘Diplodocus’ hayi represent unique genera. The study increases our knowledge about individual variation, and helps to decide how to score multi-species genera. Such a specimen-based phylogenetic analysis thus proves a valuable tool to validate historic species in sauropods, and in paleontology as a whole.

Evolution of reputation in networks: A mean field game approach

This work models the competitive behaviour of individuals who maximize their own utility managing their network of connections with other individuals. Utility is taken as a synonym of reputation in this model. Each agent has to decide between two variables: the quality of connections and the number of connections. Hence, the reputation of an individual is a function of the number and the quality of connections within the network. On the other hand, individuals incur in a cost when they improve their network of contacts. The initial value of the quality and number of connections of each individual is distributed according to an initial (given) distribution. The competition occurs over continuous time and among a continuum of agents. A mean field game approach is adopted to solve the model, leading to an optimal trajectory for the number and quality of connections for each individual.