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- Andre, C., et al.
(författare)
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Predation on Settling Bivalve Larvae by Benthic Suspension Feeders - the Role of Hydrodynamics and Larval Behavior
- 1993
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Ingår i: Marine Ecology-Progress Series. - 0171-8630. ; 97:2, s. 183-192
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Tidskriftsartikel (refereegranskat)abstract
- Predation by the suspension-feeding infaunal bivalve Cerastoderma edule on settling C. edule larvae was studied in a flume boundary-layer flow. The density of settled larvae was reduced by 33% in an area of 5 cm2 enclosing individual adults. Mean survival time for competent C. edule larvae drifting over sediment populated with feeding adults (380 ind. m-2) was 64 s, and 75% of the observed larvae were inhaled by adults. Observations of the siphonal currents produced by C. edule and the swimming behaviour of larvae were combined in a computer model to assess the importance of adult density and boundary-layer flow on the predation risk experienced by settling larvae. Survival of settling larvae decreased drastically with increasing adult density, whereas increased flow velocity caused only a slightly higher predation risk. Although reduction in larval settlement on the scale of individual adults may be small or moderate, inhalation of settling larvae by populations of resident suspension feeders may cause a significant decrease in settlement on a larger scale (10(1) to 10(3) m).
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- Mäntylä, P., et al.
(författare)
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Improved thickness and shape accuracy with advanced pass scheduling in plate rolling
- 1992
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Ingår i: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 34, s. 255-263
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Tidskriftsartikel (refereegranskat)abstract
- The so-called CROWN programs have been developed as a result of the co-operation in the Scandinavian Steel Industry. They consist of separate physical models for calculation of plate or strip temperature and roll thermal expansion, wear and elastic deformation. Flatness and residual stresses in the material are deduced from the relative change in profile during rolling with the aid of a shape vector method which considers the transverse metal flow in the roll gap. The CROWNON model is an on-line model which can be used for process control in rolling mills. A new optimized pass schedule generation system has been developed for the plate mill in Rautaruukki. The pass schedule is calculated in the forward direction for the sizing pass, broadside passes and the longitudinal passes. The drafts for the broadside and the first longitudinal passes are limited by maximum force, torque and strain. For the last longitudinal passes, the shape vector method is applied and the draft is restricted by the maximum steepness and flatness criteria. The change in the relative elongation differences between the centre and the edge of the plate together with experimentally determined values for the transverse metal flow (e.g. ξ-values) are used in the schedule calculation. To predict correct rolling loads during the scheduling, an adaptive temperature-dependant force-draft model is used based on statistical analysis of the rolling process. The system has decreased the number of passes, improved the yield and has provided the possibility of rolling thin, wide plates, e.g. 4.7 × 3250 mm with good flatness and minimum crown. The barrel length of Rautaruukki's plate mill is 3,6 m and the maximum rolling speed is 5 m/s. During the last years two dimensional and three dimensional Finite Element simulations of hot rolling of flat products have been made. The calculated rolling forces show very good agreement with experiments made in Rautaruukki's plate mill. © 1992.
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