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- Boberg, Elin, 1980-, et al.
(författare)
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Pollinator shifts and the evolution of spur length in the moth-pollinated orchid Platanthera bifolia
- 2014
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 113:2, s. 267-275
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Tidskriftsartikel (refereegranskat)abstract
- Plantpollinator interactions are thought to have shaped much of floral evolution. Yet the relative importance of pollinator shifts and coevolutionary interactions for among-population variation in floral traits in animal-pollinated species is poorly known. This study examined the adaptive significance of spur length in the moth-pollinated orchid Platanthera bifolia. Geographical variation in the length of the floral spur of P. bifolia was documented in relation to variation in the pollinator fauna across Scandinavia, and a reciprocal translocation experiment was conducted in south-east Sweden between a long-spurred woodland population and a short-spurred grassland population. Spur length and pollinator fauna varied among regions and habitats, and spur length was positively correlated with the proboscis length of local pollinators. In the reciprocal translocation experiment, long-spurred woodland plants had higher pollination success than short-spurred grassland plants at the woodland site, while no significant difference was observed at the grassland site. The results are consistent with the hypothesis that optimal floral phenotype varies with the morphology of the local pollinators, and that the evolution of spur length in P. bifolia has been largely driven by pollinator shifts.
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| 3. |
- Tahir, Mohammed, 1961-, et al.
(författare)
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Evaluation of tool material Vancron 40 with regard to wear, surface quality and galling
- 2012
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Ingår i: Proceedings of JSI 2012 - 30th International Steel Industry Conference, December 18-19, Paris, France. - Paris : B&W.
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Konferensbidrag (refereegranskat)abstract
- Resistance to adhesive wear on tool material can be improved by increasing the tool hardness, high ductility and decreasing of friction coefficient between the tool and the work material. In a similar way, resistance to galling can be increased by increasing the tool hardness and decreasing of friction. The purpose of this project was to investigate the use of Vancron 40 as work rolls in cold rolling of stainless steel in cluster rolling mills. Considerable factors were among others, the influence of different industrial lubricants, minimizing of temperature rising during rolling, lowering of rolling forces, longer life of rolls, easier grinding of rolls, increase the oil film bearing at normal cold rolling conditions and improving surface roughness of the final products.For using of work rolls in cold rolling cluster mills, roll material Vancron 40 was evaluated with regard to roll wear, surface quality and galling. Currently used roll type ASP23 was used as reference roll in the evaluation. The experiments were performed, as much as possible, in accordance to steel industries recommendations. The experiments were conducted with a 4-high pilot rolling mill at Swerea MEFOS in Luleå which is equipped for rolling of both flat and long products. The experiment was done for different industrial mineral-based lubricants. Lubrication was applied in a controlled form to the upper and lower work rolls and in the contact zone. To achieve the proposed final thickness, five passes were rolled. The characteristic of the upper and the lower work rolls, during rolling, was also examined. The pilot experimental results gave promising result in surface roughness, galling and roll material hardness. Due to its chemical and physical properties, Vancron 40 is believed to be the best solution to resist adhesive wear and galling in cold rolling process that require higher accuracy.
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