Simulação numérica na avaliação da fiabilidade de estruturas de betão armado

Neste trabalho apresenta-se uma metodologia para a avaliação da fiabilidade de estruturas de betão armado. A metodologia recorre a uma simulação numérica pelo método de Monte Carlo, com adopção de uma técnica de amostragem estratificada de redução de variância, vulgarmente designada por hipercubo latino, para a obtenção da probabilidade de não ser excedido o estado limite último em causa. Aplicou-se a metodologia a um caso prático.

Análise de sistemas de comunicação óptica com multiplexagem de subportadora e transmissão em banda lateral única

Tese dout., Engenharia Electrónica e Computação, Universidade do Algarve, 2005

A influência das tecnologias de informação e de comunicação na procura turística: uma abordagem com dados em macro panel

Tese de Doutoramento em Métodos Quantitativos Aplicados à Economia e à Gestão, Especialização em Econometria, Universidade do Algarve

Growth conditions, omega - 3 fatty acid concentrations and gene expression of fatty acid desaturases in Portulaca oleracea leaves

Tese de dout., Ciências Biotecnológicas (Biotecnologia Vegetal), Univ. do Algarve, 2009

French-greek machine translation of imperative sentences: issues in aspect and mood from a controlled language perspective

The present dissertation examines how grammatical aspect and mood are handled by machine translation (MT) systems within the scope of imperative sentences (orders, recommendations) when dealing with the language pair French-Greek (unidirectional, towards Greek). As the grammatical category of aspect is not expressed in the same way in both languages, choosing the correct aspect value when translating a verb from French to Greek can pose problems. We are interested in describing the types of errors that occur and their frequency in a corpus taken from texts pertaining to the security domain and from technical manuals, where imperative sentences are very common. In order to further delimit our research, our sample consists of sentences that comply with the general principles of simplicity and readability provided by several controlled language guidelines and aimed at higher translatability when having MT in mind. In a second phase, this study aims at discovering how modifying some of the control rules would help (or not) the MT systems better decide upon the translation of aspect and mood.

An embodied approach to language: the role of bodily feedback in discourse processing

Theories of embodied cognition argue that language processing arises not from amodal symbols that redescribe sensorimotor and affective experiences, but from partial simulations (reenactments) of modality-specific states. Recent findings on processing of words and sentences support such a stance emphasizing that the role of the body in the domain of language comprehension should not be overlooked or dismissed. The present research was conducted to extend prior work in two important ways. First, the role of simulation was tested with connected discourse rather than words or sentences presented in isolation. Second, both “online” and “offline” measures of discourse comprehension were taken. In Experiments 1 and 2 participants’ facial postures were manipulated to show that preparing the body for processing of emotion-congruent information improves discourse comprehension. In Experiment 3 the direction of body posture was manipulated to show that implicit properties of simulations, such as spatial dimension or location, are at least somewhat involved in processing of large language segments such as discourse. Finally, in Experiments 4 and 5 participants’ body movement and body posture were manipulated to show that even understanding of language describing metaphorical actions physically impossible to perform involves constructing a sensorimotor simulation of the described event. The major result was that compatibility between embodiment and language strongly modulated performance effectiveness in experiments on simulation of emotion and metaphorical action. The effect of simulation on comprehension of discourse implying spatial dimension was fragile. These findings support an embodied simulation account of cognition suggesting that sensorimotor and affective states are at least partially implicated in “online” and “offline” discourse comprehension.

Electrical characterization of metal-oxide-polymer devices for non-volatile memory applications

The objective of this thesis is to study the properties of resistive switching effect based on bistable resistive memory which is fabricated in the form of Al2O3/polymer diodes and to contribute to the elucidation of resistive switching mechanisms. Resistive memories were characterized using a variety of electrical techniques, including current-voltage measurements, small-signal impedance, and electrical noise based techniques. All the measurements were carried out over a large temperature range. Fast voltage ramps were used to elucidate the dynamic response of the memory to rapid varying electric fields. The temperature dependence of the current provided insight into the role of trapped charges in resistive switching. The analysis of fast current fluctuations using electric noise techniques contributed to the elucidation of the kinetics involved in filament formation/rupture, the filament size and correspondent current capabilities. The results reported in this thesis provide insight into a number of issues namely: (i) The fundamental limitations on the speed of operation of a bi-layer resistive memory are the time and voltage dependences of the switch-on mechanism. (ii) The results explain the wide spread in switching times reported in the literature and the apparently anomalous behaviour of the high conductance state namely the disappearance of the negative differential resistance region at high voltage scan rates which is commonly attributed to a “dead time” phenomenon which had remained elusive since it was first reported in the ‘60s. (iii) Assuming that the current is filamentary, Comsol simulations were performed and used to explain the observed dynamic properties of the current-voltage characteristics. Furthermore, the simulations suggest that filaments can interact with each other. (iv) The current-voltage characteristics have been studied as a function of temperature. The findings indicate that creation and annihilation of filaments is controlled by filling and neutralizing traps localized at the oxide/polymer interface. (v) Resistive switching was also studied in small-molecule OLEDs. It was shown that the degradation that leads to a loss of light output during operation is caused by the presence of a resistive switching layer. A diagnostic tool that predicts premature failure of OLEDs was devised and proposed. Resistive switching is a property of oxides. These layers can grow in a number of devices including, organic light emitting diodes (OLEDs), spin-valve transistors and photovoltaic devices fabricated in different types of material. Under strong electric fields the oxides can undergo dielectric breakdown and become resistive switching layers. Resistive switching strongly modifies the charge injection causing a number of deleterious effects and eventually device failure. In this respect the findings in this thesis are relevant to understand reliability issues in devices across a very broad field.

Prática desportiva, qualidade de vida, violência escolar, composição e satisfaçação corporal dos adolescentes algarvios

Tese de douoramento, Psicologia, Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, 2014

Relações entre capacidades musicais, consciência fonológica e desempenho da leitura em crianças do 1º e 2º ano de escolaridade

Dissertação de mestrado, Neurociências Cognitivas e Neuropsicologia, Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, 2015

Modeling the suitable habitat of a structural red gorgonian species in the Mediterranean/east Atlantic regions predicts a wider distribution than previously known

Dissertação de mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Univerdade do Algarve, 2015

Diversifying medical imaging of breast lesions

Dissertação de mestrado, Engenharia Informática, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

VIH - tratamento, profilaxia e novas estratégias no âmbito da nanotecnologia

Dissertação de mestrado, Ciências Farmacêuticas, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2014