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KNUT BJØRN LINDKVIST LORENA GALLART-JORNET† MAI CECILIE STABELL‡ 《The Canadian geographer》2008,52(1):105-120
This article discusses how cultural, technological and social factors contribute to the restructuring of the Spanish salted fish market and production systems. The analytical principles used are institutional, evolutionary socio-economic theories on spatial, technological and social change. A major focus of the analysis is the use of production chain theory to analyze the Spanish salted fish market. The main issue is whether Spain, as a traditional salted fish consumer market, is more influenced by technology and supplier strategies than by cultural aspects and consumer traditions. The strategies of Icelandic salted fish suppliers, better preservation systems and new salting methods seem to have influenced the restructuring of the Spanish salted fish market more than cultural factors. Nevertheless, without the Spanish tradition of salted fish, the new light salted fillets and desalted products most likely would not have been accepted by consumers. In addition, the Icelandic influence proves the strength of national Icelandic production systems. 相似文献
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Layered low permeability rock units, like shales, represent seals or ‘cap‐rocks’ in a variety of geological settings. A continuous increase in the fluid pressure gradients across a virtually impermeable rock layer will ultimately lead to hydro‐fracturing. Depending on the boundary conditions, such fracturing may lead to the formation of a set of sub‐parallel cracks oriented more or less perpendicular to the cap‐rock layer. In this article, we propose a new numerical model that describes interactions between multiple cross‐cutting fractures in an elastic low permeability rock layer. The width of each fracture and the spacing between them are modeled as a force balance between the fluid pressure and the elastic forces in the cap‐rock and between each fracture. The model indicates that the system of fractures evolves toward a spatially periodic steady‐state distribution with a fixed fracture spacing and aperture. The results are similar for incompressible and compressible fluids. The steady‐state conditions depend on only two dimensionless parameters, and the fracture spacing is only weakly dependent on the cap‐rock thickness. This is in contrast to fracturing produced by simple extension of an elastic rock layer beyond the fracture strength, in which case fracture spacing is proportional to layer thickness. 相似文献
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