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- Hermannsson, Elvar, et al.
(författare)
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Hydrodynamic design optimization of trawl-door shapes with local surrogate models
- 2013
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Ingår i: SIMULTECH 2013. - 9789898565693 ; , s. 751-756
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Konferensbidrag (refereegranskat)abstract
- Trawl-doors have a large influence on the fuel consumption of fishing vessels. Design and optimization of trawl-doors using computational models are a key factor in minimizing the fuel consumption. This paper presents an optimization algorithm for the shape design of trawl-door shapes using computational fluid dynamic (CFD) models. Accurate CFD models are computationally expensive. Therefore, the direct use of traditional optimization algorithms, which often require a large number of evaluations, may prohibitive. The proposed approach is iterative and uses low-order local response surface approximation models of the expensive CFD model, constructed in each iteration, to reduce the number of evaluations. The algorithm is applied to the design of a two-element trawl-door (slat and airfoil), involving four design variables controlling the angle of attack and the slat position and orientation. The results show that a satisfactory design can be obtained at the cost of a few iterations of the algorithm.
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| 3. |
- Ladfors, S. W., et al.
(författare)
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Longitudinal Follow-Up on Cardiopulmonary Exercise Capacity Related to Cardio-Metabolic Risk Factors in Children With Renal Transplants
- 2021
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Ingår i: Frontiers in Sports and Active Living. - : Frontiers Media SA. - 2624-9367. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Background: Children with chronic kidney disease, including those treated with kidney transplantation (KT), have an increased risk of cardiovascular disease. The aim of this study was to examine the cardiopulmonary exercise capacity after KT compared to matched controls, to relate the results to physical activity, blood pressure and biochemical findings and to follow exercise capacity over time. & nbsp; Methods: Patients with KT (n = 38, age 7.7-18 years), with a mean time from transplantation of 3.7 years (0.9-13.0) and mean time in dialysis 0.8 years, were examined at inclusion and annually for up to three years. Healthy controls (n = 17, age 7.3-18.6 years) were examined once. All subjects underwent a cardiopulmonary exercise test, resting blood pressure measurement, anthropometry and activity assessment. Patients also underwent echocardiography, dual-energy X-ray absorptiometry (DXA), 24-h ambulatory BP measurements (ABPM), assessment of glomerular filtration rate (GFR) and blood sampling annually. & nbsp; Results: As compared to healthy controls, KT patients showed decreased exercise capacity measured both as VO2peak (34.5 vs. 43.9 ml/kg/min, p < 0.001) and maximal load (2.6 vs. 3.5 W/kg, p < 0.0001), similarly as when results were converted to z-scores. No significant difference was found in weight, but the KT patients were shorter and had higher BMI z-score than controls, as well as increased resting SBP and DBP z-scores. The patient or parent reported physical activity was significantly lower in the KT group compared to controls (p < 0.001) In the combined group, the major determinants for exercise capacity z-scores were activity score and BMI z-score (beta = 0.79, p < 0.0001 and beta = -0.38, p = 0.007, respectively). Within the KT group, low exercise capacity was associated with high fat mass index (FMI), low activity score, low GFR and high blood lipids. In the multivariate analysis FMI and low GFR remained predictors of low exercise capacity. The longitudinal data for the KT patients showed no change in exercise capacity z-scores over time. & nbsp; Conclusion: Patients with KT showed decreased exercise capacity and increased BP as compared to healthy controls. Exercise capacity was associated to GFR, physical activity, FMI and blood lipids. It did not improve during follow-up.
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