21 resultados para system dynamics analysis
Resumo:
Based on the report for the unit “Métodos Interactivos de Participação e Decisão A” (Interactive methods of participation and decision A), coordinated by Prof. Lia Maldonado Teles de Vasconcelos and Prof. Nuno Miguel Ribeiro Videira Costa. This unit was provided for the PhD Program in Technology Assessment in 2015/2016.
Resumo:
Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e Computadores
Resumo:
The basic motivation of this work was the integration of biophysical models within the interval constraints framework for decision support. Comparing the major features of biophysical models with the expressive power of the existing interval constraints framework, it was clear that the most important inadequacy was related with the representation of differential equations. System dynamics is often modelled through differential equations but there was no way of expressing a differential equation as a constraint and integrate it within the constraints framework. Consequently, the goal of this work is focussed on the integration of ordinary differential equations within the interval constraints framework, which for this purpose is extended with the new formalism of Constraint Satisfaction Differential Problems. Such framework allows the specification of ordinary differential equations, together with related information, by means of constraints, and provides efficient propagation techniques for pruning the domains of their variables. This enabled the integration of all such information in a single constraint whose variables may subsequently be used in other constraints of the model. The specific method used for pruning its variable domains can then be combined with the pruning methods associated with the other constraints in an overall propagation algorithm for reducing the bounds of all model variables. The application of the constraint propagation algorithm for pruning the variable domains, that is, the enforcement of local-consistency, turned out to be insufficient to support decision in practical problems that include differential equations. The domain pruning achieved is not, in general, sufficient to allow safe decisions and the main reason derives from the non-linearity of the differential equations. Consequently, a complementary goal of this work proposes a new strong consistency criterion, Global Hull-consistency, particularly suited to decision support with differential models, by presenting an adequate trade-of between domain pruning and computational effort. Several alternative algorithms are proposed for enforcing Global Hull-consistency and, due to their complexity, an effort was made to provide implementations able to supply any-time pruning results. Since the consistency criterion is dependent on the existence of canonical solutions, it is proposed a local search approach that can be integrated with constraint propagation in continuous domains and, in particular, with the enforcing algorithms for anticipating the finding of canonical solutions. The last goal of this work is the validation of the approach as an important contribution for the integration of biophysical models within decision support. Consequently, a prototype application that integrated all the proposed extensions to the interval constraints framework is developed and used for solving problems in different biophysical domains.
Resumo:
Some of the properties sought in seismic design of buildings are also considered fundamental to guarantee structural robustness. Moreover, some key concepts are common to both seismic and robustness design. In fact, both analyses consider events with a very small probability of occurrence, and consequently, a significant level of damage is admissible. As very rare events,in both cases, the actions are extremely hard to quantify. The acceptance of limited damage requires a system based analysis of structures, rather than an element by element methodology, as employed for other load cases. As for robustness analysis, in seismic design the main objective is to guarantee that the structure survives an earthquake, without extensive damage. In the case of seismic design, this is achieved by guaranteeing the dissipation of energy through plastic hinges distributed in the structure. For this to be possible, some key properties must be assured, in particular ductility and redundancy. The same properties could be fundamental in robustness design, as a structure can only sustain significant damage if capable of distributing stresses to parts of the structure unaffected by the triggering event. Timber is often used for primary load‐bearing elements in single storey long‐span structures for public buildings and arenas, where severe consequences can be expected if one or more of the primary load bearing elements fail. The structural system used for these structures consists of main frames, secondary elements and bracing elements. The main frame, composed by columns and beams, can be seen as key elements in the system and should be designed with high safety against failure and under strict quality control. The main frames may sometimes be designed with moment resisting joints between columns and beams. Scenarios, where one or more of these key elements, fail should be considered at least for high consequence buildings. Two alternative strategies may be applied: isolation of collapsing sections and, provision of alternate load paths [1]. The first one is relatively straightforward to provide by deliberately designing the secondary structural system less strong and stiff. Alternatively, the secondary structural system and the bracing system can be design so that loss of capacity in the main frame does not lead to the collapse. A case study has been selected aiming to assess the consequences of these two different strategies, in particular, under seismic loads.
Resumo:
RESUMO - A segurança do doente é um tema que tem sido amplamente estudado por todo o mundo. Com o desenvolvimento do conhecimento, das técnicas e o advento das learning organizations é possível detectar as áreas onde existe potencial risco, conhecer o número de incidentes de forma sistemática, promover a evolução das técnicas nas áreas mais urgentes, determinar o impacto de todos os incidentes e eventos adversos, aprender com eles e promover modificações nas organizações. A neonatologia não foi excepção, pelo que se pretende a criação e validação de um sistema de notificação de eventos adversos e de incidentes, anónimo e não punitivo, adaptado a uma Unidade de Cuidados Intermédios Neonatal. O delineamento do estudo passou pela revisão bibliográfica para a construção de um sistema e posterior análise do mesmo por um painel de especialistas, para a selecção e consenso de itens que integraram o modelo. Por fim este sistema foi sujeito a um pré-teste. Com a aplicação da Técnica de Grupo Nominal constatou-se que a confidencialidade dos dados é um tema muito sensível aos profissionais. Na aplicação do pré-teste as categorias de incidentes notificados relacionam-se com medicação, ventilação e identificação. Assim sendo, este sistema detém validade interna, no entanto com a aplicação do pré-teste verificou-se que este perde validade externa, pelo que os resultados apresentados neste projecto de investigação não podem ser generalizados. A notificação é uma área para a qual os profissionais estão sensibilizados, no entanto, ainda encontra muitos entraves à sua implementação e consequentemente à colheita de dados.
Resumo:
Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores
Resumo:
A definição de pirataria ou a desmistificação da sua origem, no tempo e espaço, revela maiores dificuldades do que atualmente. Com este trabalho propusemo-nos a estudar como é que a pirataria era perpetrada e entendida no passado, bem como no presente. Também nos propomos a identificar limitações legais e as medidas operativas no combate à pirataria, como por exemplo: limites conceptuais, lacunas, estratégias, entre outros. Por outro lado, atendemos as soluções encontradas no combate à pirataria sem deixar de observar fraqueza da lei e conflitos entre jurisdições. Por fim, o curso da história dá-nos a seguinte percepção: a pirataria era tida como crime se fosse contra os interesses das nações. O desinteresse dos Estados para reprimir a pirataria possibilitou o seu aumento, proliferação, domínio e sofisticação em certas regiões do Mundo. O presente trabalho tem como objetivo trazer para o centro da discussão os direitos humanos numa perspetiva tripla: proibição da pirataria, supressão e raízes, aliando o estudo de possíveis respostas a dar a esta epidemia.
Resumo:
Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Estatística e Gestão de Informação
Resumo:
Thesis submitted to the Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia for the degree of Doctor of Philosophy in Environmental Engineering
Resumo:
Assessing the safety of existing timber structures is of paramount importance for taking reliable decisions on repair actions and their extent. The results obtained through semi-probabilistic methods are unrealistic, as the partial safety factors present in codes are calibrated considering the uncertainty present in new structures. In order to overcome these limitations, and also to include the effects of decay in the safety analysis, probabilistic methods, based on Monte-Carlo simulation are applied here to assess the safety of existing timber structures. In particular, the impact of decay on structural safety is analyzed and discussed, using a simple structural model, similar to that used for current semi-probabilistic analysis.
Resumo:
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
Resumo:
Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.
Resumo:
Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.
Resumo:
ABSTRACT - The Patient Protection and Affordable Care Act shook the foundations of the US health system, offering all Americans access to health care by changing the way the health insurance industry works. As President Obama signed the Act on 23 March 2010, he said that it stood for “the core principle that everybody should have some basic security when it comes to their health care”. Unlike the U.S., the Article 64 of the Portuguese Constitution provides, since 1976, the right to universal access to health care. However, facing a severe economic crisis, Portugal has, under the supervision of the Troika, a tight schedule to implement measures to improve the efficiency of the National Health Service. Both countries are therefore despite their different situation, in a conjuncture of reform and the use of new health management measures. The present work, using a qualitative research methodology examines the Affordable Care Act in order to describe its principles and enforcement mechanisms. In order to describe the reality in Portugal, the Portuguese health system and the measures imposed by Troika are also analyzed. The intention of this entire analysis is not only to disclose the innovative U.S. law, but to find some innovative measures that could serve health management in Portugal. Essentially we identified the Exchanges and Wellness Programs, described throughout this work, leaving also the idea of the possibility of using them in the Portuguese national health system.
Resumo:
A Work Project, presented as part of the requirements for the Award of a Masters Degree in Economics from the NOVA – School of Business and Economics