974 resultados para Mismatched uncertainties


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Os biocombustíveis têm estado na linha da frente das políticas energéticas mundiais visto que as suas vantagens conseguem colmatar as incertezas e resolver alguns dos problemas associados aos combustíveis fósseis. O biodiesel tem provado ser um combustível muito fiável, alternativo ao petrodiesel. É uma mistura de ésteres alquílicos produzidos a partir de óleos vegetais e gorduras animais através de uma reacção de transesterificação. Como combustível, o biodiesel é economicamente viável, socialmente responsável, tecnicamente compatível e ambientalmente amigável. O principal desafio associado ao seu desenvolvimento tem a ver com a escolha de matéria-prima para a sua produção. Nos países do terceiro mundo, óleos alimentares são mais importantes para alimentar pessoas do que fazer funcionar carros. Esta tese tem como objectivos produzir/processar biodiesel a partir de recursos endógenos de Timor-Leste e medir/prever as propriedades termodinâmicas do biodiesel, a partir das dos esteres alquílicos. A síntese do biodiesel a partir dos óleos de Aleurites moluccana, Jatropha curcas e borras de café foram aqui estudados. As propriedades termodinâmicas como densidade, viscosidade, tensão superficial, volatilidade e velocidade do som também foram medidas e estimadas usando modelos preditivos disponíveis na literatura, incluindo as equações de estado CPA e soft-SAFT. Timor-Leste é um país muito rico em recursos naturais, mas a maioria da população ainda vive na pobreza e na privação de acesso a serviços básicos e condições de vida decentes. A exploração de petróleo e gás no mar de Timor tem sido controlado pelo Fundo Petrolífero. O país ainda carece de electricidade e combustíveis que são cruciais para materializar as políticas de redução da pobreza. Como solução, o governo timorense criou recentemente o Plano Estratégico de Desenvolvimento a 20 anos cujas prioridades incluem trazer o desenvolvimento do petróleo do mar para a costa sul de Timor-Leste e desenvolver as energias renováveis. É neste último contexto que o biodiesel se insere. O seu desenvolvimento no país poderá ser uma solução para o fornecimento de electricidade, a criação de empregos e sobretudo o combate contra a pobreza e a privação. Para ser usado como combustível, no entanto, o biodiesel deve possuir propriedades termodinâmicas coerentes com as especificadas nas normas da ASTM D6751 (nos Estados Unidos) ou EN 14214 (na Europa) para garantir uma adequada ignição, atomização e combustão do biodiesel no motor.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The exponential growth of the world population has led to an increase of settlements often located in areas prone to natural disasters, including earthquakes. Consequently, despite the important advances in the field of natural catastrophes modelling and risk mitigation actions, the overall human losses have continued to increase and unprecedented economic losses have been registered. In the research work presented herein, various areas of earthquake engineering and seismology are thoroughly investigated, and a case study application for mainland Portugal is performed. Seismic risk assessment is a critical link in the reduction of casualties and damages due to earthquakes. Recognition of this relation has led to a rapid rise in demand for accurate, reliable and flexible numerical tools and software. In the present work, an open-source platform for seismic hazard and risk assessment is developed. This software is capable of computing the distribution of losses or damage for an earthquake scenario (deterministic event-based) or earthquake losses due to all the possible seismic events that might occur within a region for a given interval of time (probabilistic event-based). This effort has been developed following an open and transparent philosophy and therefore, it is available to any individual or institution. The estimation of the seismic risk depends mainly on three components: seismic hazard, exposure and vulnerability. The latter component assumes special importance, as by intervening with appropriate retrofitting solutions, it may be possible to decrease directly the seismic risk. The employment of analytical methodologies is fundamental in the assessment of structural vulnerability, particularly in regions where post-earthquake building damage might not be available. Several common methodologies are investigated, and conclusions are yielded regarding the method that can provide an optimal balance between accuracy and computational effort. In addition, a simplified approach based on the displacement-based earthquake loss assessment (DBELA) is proposed, which allows for the rapid estimation of fragility curves, considering a wide spectrum of uncertainties. A novel vulnerability model for the reinforced concrete building stock in Portugal is proposed in this work, using statistical information collected from hundreds of real buildings. An analytical approach based on nonlinear time history analysis is adopted and the impact of a set of key parameters investigated, including the damage state criteria and the chosen intensity measure type. A comprehensive review of previous studies that contributed to the understanding of the seismic hazard and risk for Portugal is presented. An existing seismic source model was employed with recently proposed attenuation models to calculate probabilistic seismic hazard throughout the territory. The latter results are combined with information from the 2011 Building Census and the aforementioned vulnerability model to estimate economic loss maps for a return period of 475 years. These losses are disaggregated across the different building typologies and conclusions are yielded regarding the type of construction more vulnerable to seismic activity.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Research on audiovisual speech integration has reported high levels of individual variability, especially among young infants. In the present study we tested the hypothesis that this variability results from individual differences in the maturation of audiovisual speech processing during infancy. A developmental shift in selective attention to audiovisual speech has been demonstrated between 6 and 9 months with an increase in the time spent looking to articulating mouths as compared to eyes (Lewkowicz & Hansen-Tift. (2012) Proc. Natl Acad. Sci. USA, 109, 1431–1436; Tomalski et al. (2012) Eur. J. Dev. Psychol., 1–14). In the present study we tested whether these changes in behavioural maturational level are associated with differences in brain responses to audiovisual speech across this age range. We measured high-density event-related potentials (ERPs) in response to videos of audiovisually matching and mismatched syllables /ba/ and /ga/, and subsequently examined visual scanning of the same stimuli with eye-tracking. There were no clear age-specific changes in ERPs, but the amplitude of audiovisual mismatch response (AVMMR) to the combination of visual /ba/ and auditory /ga/ was strongly negatively associated with looking time to the mouth in the same condition. These results have significant implications for our understanding of individual differences in neural signatures of audiovisual speech processing in infants, suggesting that they are not strictly related to chronological age but instead associated with the maturation of looking behaviour, and develop at individual rates in the second half of the first year of life.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tese de doutoramento (co-tutela), Ciências Geofísicas e da Geoinformação (Geofísica), Université de Toulouse, Universidade de Lisboa, 2013

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tese de doutoramento, Filosofia (Filosofia da Natureza e do Ambiente), Universidade de Lisboa, Universidade Nova de Lisboa, 2015

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tese de doutoramento, Ciências Geofísicas e da Geoinformação (Deteção Remota), Universidade de Lisboa, Faculdade de Ciências, 2015

Relevância:

10.00% 10.00%

Publicador:

Resumo:

[author abstract] The field of hydrographic surveying is inherently important to achieving a true understanding of the world that underlies the vast bodies of water that cover the earth. In this study I will determine the uncertainties of depth estimates of the seafloor that relate to the survey design and sound velocity. The survey design and collection of sound velocity were all conducted of the coast of Vancouver Island, B.C. near the entrance of the Strait of Juan de Fuca. The assessment will show how the change in sound velocity over time will influence the bathymetric reading, if not corrected for. The differences in bathymetric depth readings will show a correlation to the changes in sound velocity.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In response to contemporary concerns, and using neglected primary sources, this article explores the professionalisation of teachers of Religious Education (RI/RE) in non-denominational, state-maintained schools in England. It does so from the launch of Religion in Education (1934) and the Institute for Christian Education at Home and Abroad (1935) to the founding of the Religious Education Council of England and Wales (1973) and the British Journal of Religious Education (1978). Professionalisation is defined as a collective historical process in terms of three inter-related concepts: (1) professional self-organisation and professional politics, (2) professional knowledge, and (3) initial and continuing professional development. The article sketches the history of non-denominational religious education prior to the focus period, to contextualise the emergence of the professionalising processes under scrutiny. Professional self-organisation and professional politics are explored by reconstructing the origins and history of the Institute of Christian Education at Home and Abroad, which became the principal body offering professional development provision for RI/RE teachers for some fifty years. Professional knowledge is discussed in relation to the content of Religion in Education which was oriented around Christian Idealism and interdenominational networking. Changes in journal name in the 1960s and 1970s reflected uncertainties about the orientation of the subject and shifts in understanding over the nature and character of professional knowledge. The article also explores a particular case of resistance, in the late 1960s, to the prevailing consensus surrounding the nature and purpose of RI/RE, and the representativeness and authority of the pre-eminent professional body of the time. In conclusion, the article examines some implications which may be drawn from this history for the prospects and problems of the professionalisation of RE today.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tese de doutoramento, Sistemas Sustentáveis de Energia, Universidade de Lisboa, Faculdade de Ciências, 2016

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tese de doutoramento, Ciências do Ambiente, Universidade de Lisboa, Faculdade de Ciências, Universidade Nova de Lisboa, 2015

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This study presents and discusses the tsunami hazard posed by an updated CSZ earthquake scenerio to the coastal communities of Port Angeles and Port Townsend, based on the results of a high resolution GeoClaw simulation with 2/3 arc second resolution (about 20.56 meters) surrounding these towns. In addition, we will also present the results of a coarse regional simulation of the Strait of Juan de Fuca. This coarse study encompasses 28 regions that span the Strait’s coast, including the communities of Anacortes, Bellingham, Friday Harbor, and Victoria, BC in addition to extended areas around Port Angeles and Port Townsend. The finest grid for these 28 regions where we collected results had 2 arc sec resolution (around 62 meters). Finally, we will discuss some inherent uncertainties in the specification of the earthquake scenario, the limitations of the GeoClaw model, and the associated uncertainites in the results.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The Malaysian palm oil industry is well known for the social, environmental and sustainability challenges associated with its rapid growth over the past ten years. Technologies exist to reduce the conflict between national development aims of economic uplift for the rural poor, on the one hand, and ecological conservation, on the other hand, by raising yields and incomes from areas already under cultivation. But the uptake of these technologies has been slow, particularly in the smallholder sector. In this paper we explore the societal and institutional challenges that influence the investment and innovation decisions of micro and small enterprise (MSE) palm oil smallholders in Sabah, Malaysia. Based on interviews with 38 smallholders, we identify a number of factors that reduce the smallholders' propensity to invest in more sustainable practices. We discuss why more effective practices and innovations are not being adopted using the concepts of, firstly, institutional logics to explore the internal dynamics of smallholder production systems, including attitudes to sustainability and innovation; and, secondly, institutional context to explore the pressures the smallholders face, including problems of access to land, labour, capital, knowledge and technical resources. These factors include limited access to global market information, corruption and uncertainties of legal title, weak economic status and social exclusion. In discussing these factors we seek to contribute to wider theoretical debates about the factors that block innovation and investment in business improvements in marginal regions and in marginalised groups.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dissertação apresentada à Escola Superior de Educação de Lisboa para obtenção do grau de Mestre em Educação - Especialização em Educação Especial

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dissertação para a obtenção do grau de Mestre em Engenharia Electrotécnica Ramo de Energia

Relevância:

10.00% 10.00%

Publicador:

Resumo:

As classificações geomecânicas são uma das abordagens mais reconhecidas para estimar a qualidade do maciço rochoso, face à sua simplicidade e competência para gerir incertezas. As incertezas geológicas e geotécnicas podem ser avaliadas de forma eficaz usando classificações adequadas. Este estudo pretende enfatizar a importância das classificações geomecânicas e índices geomecânicos, tais como a Rock Mass Rating (RMR), a Rock Tunnelling Quality Index (Qsystem), o Geological Strength Index (GSI) e o Hydro‐Potential (HP) Value, para ajuizar a qualidade do maciço rochoso granítico das galerias subterrâneas de Paranhos (setor de Carvalhido ‐ Burgães; área urbana do Porto). Em particular, o valor hidro‐potencial (HP‐value) é uma classificação semi‐quantitativa aplicada a maciços rochosos que permite estimar as infiltrações de água subterrânea em escavações de terrenos rochosos. Para esta avaliação foi compilada e integrada uma extensa base de dados geológico‐geotécnica e geomecânica, apoiada na técnica de amostragem linear de superfícies expostas descontinuidades. Para refinar o zonamento geotécnico do maciço rochoso granítico, previamente realizado em 2010, foram coletadas amostras de rocha em pontos‐chave, com o objetivo de avaliar a sua resistência através do Ensaio de Carga Pontual (PLT). A aplicação das classificações geomecânicas foi realizada de uma forma equilibrada, estabelecendo diferentes cenários e tendo sempre em conta o conhecimento das características do maciço in situ. Apresenta‐se uma proposta de zonamento hidrogeomecânico com o objetivo de compreender melhor a circulação geo‐hidráulica do maciço rochoso granítico. Pretende‐se com esta metodologia contribuir para aprofundar o conhecimento do substrato rochoso do Porto, nomeadamente no que diz respeito ao seu comportamento geomecânico.