3 resultados para Designación general de material
Resumo:
Over the last decade, much new research has appeared on the subject of the Great Irish Famine but, remarkably, a major political event during the famine - the 1847 general election - has received virtually no mention. Recent work on politics in this period has tended to concentrate on political reaction in Britain rather than Ireland. The aim of this article is to examine the response of Irish politicians to the famine during the general election of 1847. The main source has been the political addresses and nomination speeches of most of the 140 candidates. The evidence from this material shows that, although the famine was an important matter in many constituencies, it was not the dominant issue countrywide. Various proposals to deal with the famine emerged, but there was an absence of agreed, practical measures to deal with immediate problems. The parties in Ireland failed to create a common platform to challenge the government over its efforts. Ideological constraints played an important part in these failures. The general election of 1847 represents a lost opportunity to tackle some of the effects of the famine.
Resumo:
Polypropylene (PP), a semi-crystalline material, is typically solid phase thermoformed at temperatures associated with crystalline melting, generally in the 150° to 160°Celsius range. In this very narrow thermoforming window the mechanical properties of the material rapidly decline with increasing temperature and these large changes in properties make Polypropylene one of the more difficult materials to process by thermoforming. Measurement of the deformation behaviour of a material under processing conditions is particularly important for accurate numerical modelling of thermoforming processes. This paper presents the findings of a study into the physical behaviour of industrial thermoforming grades of Polypropylene. Practical tests were performed using custom built materials testing machines and thermoforming equipment at Queen′s University Belfast. Numerical simulations of these processes were constructed to replicate thermoforming conditions using industry standard Finite Element Analysis software, namely ABAQUS and custom built user material model subroutines. Several variant constitutive models were used to represent the behaviour of the Polypropylene materials during processing. This included a range of phenomenological, rheological and blended constitutive models. The paper discusses approaches to modelling industrial plug-assisted thermoforming operations using Finite Element Analysis techniques and the range of material models constructed and investigated. It directly compares practical results to numerical predictions. The paper culminates discussing the learning points from using Finite Element Methods to simulate the plug-assisted thermoforming of Polypropylene, which presents complex contact, thermal, friction and material modelling challenges. The paper makes recommendations as to the relative importance of these inputs in general terms with regard to correlating to experimentally gathered data. The paper also presents recommendations as to the approaches to be taken to secure simulation predictions of improved accuracy.
Resumo:
We describe a simple strategy, which is based on the idea of space confinement, for the synthesis of carbon coating on LiFePO4 nanoparticles/graphene nanosheets composites in a water-in-oil emulsion system. The prepared composite displayed high performance as a cathode material for lithium-ion battery, such as high reversible lithium storage capacity (158 mA h g-1 after 100 cycles), high coulombic efficiency (over 97%), excellent cycling stability and high rate capability (as high as 83 mA h g -1 at 60 C). Very significantly, the preparation method employed can be easily adapted and be extended as a general approach to sophisticated compositions and structures for the preparation of highly dispersed nanosized structure on graphene.