14 resultados para Euler, Leonhard, 1707-1783.


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Complex systems, i.e. systems composed of a large set of elements interacting in a non-linear way, are constantly found all around us. In the last decades, different approaches have been proposed toward their understanding, one of the most interesting being the Complex Network perspective. This legacy of the 18th century mathematical concepts proposed by Leonhard Euler is still current, and more and more relevant in real-world problems. In recent years, it has been demonstrated that network-based representations can yield relevant knowledge about complex systems. In spite of that, several problems have been detected, mainly related to the degree of subjectivity involved in the creation and evaluation of such network structures. In this Thesis, we propose addressing these problems by means of different data mining techniques, thus obtaining a novel hybrid approximation intermingling complex networks and data mining. Results indicate that such techniques can be effectively used to i) enable the creation of novel network representations, ii) reduce the dimensionality of analyzed systems by pre-selecting the most important elements, iii) describe complex networks, and iv) assist in the analysis of different network topologies. The soundness of such approach is validated through different validation cases drawn from actual biomedical problems, e.g. the diagnosis of cancer from tissue analysis, or the study of the dynamics of the brain under different neurological disorders.

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Transcrição dos documentos relativos à expedição naturalista de João da Silva Feijó a Cabo Verde (1783-96), existentes no Arquivo Histórico Ultramarino e respetivo enquadramento histórico

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The foresight and scenario building methods can be an interesting reference for social sciences, especially in terms of innovative methods for labour process analysis. A scenario – as a central concept for the prospective analysis – can be considered as a rich and detailed portrait of a plausible future world. It can be a useful tool for policy-makers to grasp problems clearly and comprehensively, and to better pinpoint challenges as well as opportunities in an overall framework. The features of the foresight methods are being used in some labour policy making experiences. Case studies developed in Portugal will be presented, and some conclusions will be drawn in order to organise a set of principles for foresight analysis applied to the European project WORKS on the work organisation re-structuring in the knowledge society, and on the work design methods for new management structures of virtual organisations.

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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Química e Bioquímica

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Based on the report for Project III of the PhD programme on Technology Assessment and prepared for the Winter School that took place at Universidade Nova de Lisboa, Caparica Campus on the 6th and 7th of December 2010.

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pp. 141-183

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Increased demands on the capacity of the railway network gave rise to new issues related to the dynamic response of railway tracks subjected to moving vehicles. Thus, it becomes important to evaluate the applicability of traditionally used simplified models which have a closed form solution. Regarding simplified models, transversal vibrations of a beam on a visco-elastic foundation subjected to a moving load are considered. Governing equations are obtained by Hamilton’s principle. Shear distortion, rotary inertia and effect of axial force are accounted for. The load is introduced as a time varying force moving at a constant velocity. Transversal vibrations induced by the load are solved by the normal-mode analysis. Reflected waves at the extremities of the full beam are avoided by introduction of semi-infinite elements. Firstly, the critical velocity obtained from this model is compared with results of an undamped Euler- Bernoulli formulation with zero axial force. Secondly, a finite element model in ABAQUS is examined. The new contribution lies in the introduction of semi- infinite elements and in the first step to a systematic comparison, which have not been published so fa

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pp. 141-183

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Based on the report for “Project IV” unit of the PhD programme on Technology Assessment. This thesis research has the supervision of António Moniz (FCT-UNL and ITAS-KIT) and Manuel Laranja (ISEG-UTL). Other members of the thesis committee are Stefan Kuhlmann (Twente University), Leonhard Hennen (Karlsruhe Institute of Technology-ITAS), Tiago Santos Pereira (Universidade de Coimbra/CES) and Cristina Sousa (FCT-UNL).

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Dissertação para obtenção do Grau de Mestre em Engenharia Mecânica

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Although Josquin is by far the best-represented foreign composer in Gonçalo de Baena's Arte novamente inventada pera aprender a tanger (Lisbon, 1540), his music is undeniably under-represented both in the extant sixteenth-century Portuguese manuscripts containing Franco-Flemish polyphony and in volumes imported from the Netherlands such as Coimbra MM 2 and VienNB 1783. Josquin’s reputation made him, along with Ockeghem, a symbol in Portuguese humanistic culture, but up to at least the late 1530s his name seems to have been much better known than his music. Nevertheless, possible allusions to specific works by Josquin can be found in early- and mid-sixteenth-century Portuguese polyphony. By the 1520s, the general technical and stylistic characteristics of his and the following generation of northerners had begun to permeate locally produced polyphony. This eventually replaced the late-fifteenth- and early-sixteenth-century pan-consonant and homorythmic style associated with the Aragonese and the so-called Spanish court repertory.

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Com este estudo pretende-se que seja possível um avanço promissor no controlo da encurvadura (passivo e ativo), bem como o desenvolvimento inicial de um sistema de contraventamento com base no conceito de tensegridade, com encurvadura controlada, em estruturas ao nível macroscópico, com recurso às propriedades singulares das Ligas com memória de forma (LMF). A problemática inicial parte da análise da instabilidade de uma peça esbelta simples solicitada à compressão – coluna de Euler. A necessidade de controlar (ativa e passivamente) a encurvadura desta coluna leva ao desenvolvimento de sistemas de controlo com recurso às LMF. A aplicação das ligas é potenciada por desviadores, com duas configurações, dispostos a meia altura da coluna, perpendiculares ao eixo de menor inercia da coluna. Os modelos são ensaiados experimentalmente, tendo também sido desenvolvidos modelos numéricos, possibilitando uma completa análise do comportamento do sistema de controlo e da sua influência na resposta da coluna. No estudo foram utilizadas as ligas com o melhor perfil de adaptabilidade à engenharia Civil, NiTi – liga de memória de forma composta por Níquel e Titânio - que integraram um sistema de controlo de encurvadura. Fazem também parte desta dissertação desenvolvimentos paralelos ao estudo principal atrás referido. O âmbito destes estudos paralelos é centralizado na modelação das LMF enquanto elementos de controlo estrutural utilizando software de cálculo estrutural de elementos finitos. Destes desenvolvimentos resulta, para além do elemento de contraventamento dotado de LMF com base na tensegridade, a definição de um modelo constitutivo de LMF num software comercial de elementos finitos (SAP2000), com ampla divulgação no cálculo de estruturas de Engenharia Civil.

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Reconstitui-se neste artigo a história do palácio de Fernando de Larre (1689/1761), Provedor dos Armazéns Reais, na calçada do Combro, em Lisboa, comprado em 1742, em hasta pública, a Manuel Pedro de Melo, descendente de uma família de mercadores flamengos aí residente desde 1684. Entre as obras que o novo proprietário empreendeu, por volta de 1744/45, destacam-se os tectos em estuque de relevo, realizados “no ultimo primor da arte”, de acordo com uma avaliação de 1783. A inovadora linguagem ornamental presente nos estuques do palácio – em que se conjugam elementos da Regência francesa e do “barocchetto” de ascendência italiana – parece apontar para a presença de estucadores suíços que trabalhavam em Lisboa na mesma época: Giovanni Grossi, Domenico Maria Plura, Carlo Sebastiano Staffieri e Giovanni Francesco Righetti.