| 1. |
- Hjortsberg, Erik, et al.
(författare)
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X-ray microtomography for characterisation of cracks in iron ore pellets after reduction
- 2013
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Ingår i: Ironmaking & steelmaking. - 0301-9233 .- 1743-2812. ; 40:6, s. 399-406
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Tidskriftsartikel (refereegranskat)abstract
- This work presents a method, based on X-ray microtomography and three-dimensional (3D) image analysis, of characterising and quantifying crack distribution in iron ore pellets. The aims have been to verify the method and to determine to what extent crack propagation contributes to the decrease in compressive strength that occurs during reduction at 500°C as haematite transforms into magnetite. Raw materials known to cause disintegration problems were selected in order to promote crack propagation. Pellets displayed crack lengths of sizes roughly corresponding to half the pellet diameter already before reduction and, during reduction, a further crack propagation of ∼50% occurred. Through estimations by finite element analysis of the crack size and the pellet geometry, it has been possible to determine that this crack growth most likely is a mechanism that contributes to the decrease in compressive strength. The decrease of ∼90% that was experimentally determined to occur after 30 min of reduction is, however, too large to be explained by crack propagation alone. The study shows that the proposed techniques allow 3D imaging of iron ore pellets and characterisation of cracks. The scans are non-destructive and can be carried out repeatedly, which allows a specific sample to be studied at different stages during a process. Through future use of the proposed method, our aim is to reach a deeper understanding of the mechanisms behind low temperature disintegration of iron ore pellets and the performance of LKAB olivine pellets inside the blast furnace.
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| 2. |
- Sjöquist, Emma S., et al.
(författare)
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Physical Activity Coaching of Patients with Rheumatoid Arthritis in Everyday Practice : A Long-term Follow-up
- 2011
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Ingår i: Musculoskeletal Care. - Chichester : John Wiley & Sons. - 1478-2189 .- 1557-0681. ; 9:2, s. 75-85
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To investigate the long-term effects on perceived general health, disease activity, pain, activity limitation and cognitive behavioural factors of a one-year coaching programme performed in ordinary physical therapy practice to promote the adoption of health-enhancing physical activity in patients with early rheumatoid arthritis (RA).METHODS: A total of 228 patients with early RA, from 10 rheumatology clinics in Sweden, were randomly assigned to an intervention group (IG; n = 94) or a control group (CG; n = 134). The IG was coached by physical therapists during the first year to adopt health-enhancing levels of physical activity (30 minutes/day, moderately intensive, ≥ 4 days/week). No coaching was given during the subsequent year between post-intervention and follow-up. Follow-up assessment consisted of a postal questionnaire on physical activity and of visual analogue scales for ratings of general health perception and pain. The Health Assessment Questionnaire Disability Index (HAQ) and the Disease Activity Score in 28 joints (DAS 28) were collected at regular medical check-ups.RESULTS: Sixty-five (69%) participants in the IG and 92 (69%) in the CG completed the entire study period by filling in the follow-up questionnaire on physical activity two years after baseline. The intervention seemed to lack any significant influence on long-term outcome. However, different patterns of change in physical activity behaviour were observed in the two groups.CONCLUSIONS: No long-term improvement in perceived general health or other outcomes were found in the follow-up. This may partly be because the intervention lacked several important behavioural elements for physical activity maintenance. Copyright © 2011 John Wiley & Sons, Ltd.
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