61 research outputs found
Análise dinâmica de colisão de comboios para projeto de segurança passiva
Trabalho final de mestrado para obtenção do grau Mestre em Engenharia MecânicaEste trabalho visa a modelação multicorpo da colisão de comboios com o objetivo de
permitir efetuar simulações da colisão, de modo a observar os fenómenos de absorção de
energia, de modo a permitir uma redução dos custos computacionais, mas também dos custos
com testes reais. O modelo desenvolvido replica de forma bastante correta uma colisão,
podendo servir para análise da colisão.
O modelo desenvolvido tem por base um modelo real, sendo este modelo constituído por
carruagens, onde uma das carruagens apresenta uma dada velocidade inicial enquanto as outras
se encontram em repouso, e buffers, sendo estes últimos estruturas de absorção de energia, estas
estruturas encontram-se acopladas às carruagens por molas não lineares. Uma vez que os
resultados dependem da curva de rigidez das molas é relativamente simples alterar as
características do modelo de modo a simular diferentes tipo de colisão a diferentes velocidades
e com diferentes massas.
Uma vez que se verifica que quando existe o impacto entre carruagens, não existe recuo
do corpo que se encontra inicialmente em movimento, é necessário garantir que o mesmo se
verifica nas simulações, esta situação apresentou um grande desafio de simulação, sendo que
foram necessárias várias tentativas e modelos, de modo a conseguir replicar o melhor possível
este fenómeno.
Este projeto oferece uma ferramenta de análise da colisão de carruagens, sendo que a
utilização do modelo desenvolvido pode ser útil no projeto e fabrico de carruagens, bem como
em projetos de segurança passiva de passageiros.This paper aims the multibody modeling of railway collisions, with the purpose of allow
collision simulations, in order to observe the energy absorption phenomena, in order to allow
reducing the computing cost, and real test cost as well. The model was developed to replicate
quite accurately a collision and can be used for collision analysis.
The developed model was based on a real model, being this model was made by carriages,
where one of them has an initial velocity while the others are at rest, the model also have buffers,
wich are structures for energy absorption, these structures are coupled to the carriages by
nonlinear springs. Since the results depend on the springs stiffness curve it is relatively simple
to change the characteristics of the model in order to simulate different types of collision, at
different velocities with different masses.
Since it is found that when there is an impact between carriages there is no recoil of the
body that was initially moving, it is necessary to ensure this is what happens in the simulations,
this situation presented a big challenge, and several models and trials was made in order to
replicate this phenomenon as best as possible.
This project offers a different railway crash analysis tool, and the use of the developed
model can be useful in the project and manufacture of rail carriages, as well as passive passenger
safety projects.N/
Ecosystem services for intensification of agriculture, with emphasis on increased nitrogen ecological use efficiency
Funding Information: This work was undertaken as part of NUCLEUS, a virtual joint center to deliver enhanced N-use efficiency via an integrated soil?plant systems approach for the United Kingdom and Brazil. This work was funded in Brazil by FAPESP-S?o Paulo Research Foundation (Grant Number 2015/50305-8), FAPEG-Goi?s Research Foundation (Grant Number 2015-10267001479), and FAPEMA-Maranh?o Research Foundation (Grant Number RCUK-02771/16); and in the United Kingdom by the Biotechnology and Biological Sciences Research Council (Grant Number BB/N013201/1) under the Newton Fund scheme.Peer reviewedPublisher PD
Quantifying soil carbon stocks and greenhouse gas fluxes in the sugarcane agrosystem: point of view
Strategies to mitigate climate change through the use of biofuels (such as ethanol) are associated not only to the increase in the amount of C stored in soils but also to the reduction of GHG emissions to the atmosphere.This report mainly aimed to propose appropriate methodologies for the determinations of soil organic carbon stocks and greenhouse gas fluxes in agricultural phase of the sugarcane production. Therefore, the text is a piece of contribution that may help to obtain data not only on soil carbon stocks but also on greenhouse gas emissions in order to provide an accurate life cycle assessment for the ethanol. Given that the greenhouse gas value is the primary measure of biofuel product quality, biorefiners that can show a higher offset of their product will have an advantage in the market place
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