| 1. |
- Andersson, Anton, et al.
(författare)
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Design of a Foiling Optimist
- 2018
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Ingår i: Journal of Sailboat Technology. ; 2018, s. 1-24
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Tidskriftsartikel (refereegranskat)abstract
- Because of the successful application of hydrofoils on the America's Cup catamarans in the past two campaigns the interest in foiling sailing craft has boosted. Foils have been fitted to a large number of yachts with great success, ranging from dinghies to ocean racers. An interesting question is whether one of the slowest racing boats in the world, the Optimist dinghy, can foil, and if so, at what minimum wind speed. The present paper presents a comprehensive design campaign to answer the two questions. The campaign includes a newly developed Velocity Prediction Program (VPP) for foiling/non-foiling conditions, a wind tunnel test of sail aerodynamics, a towing tank test of hull hydrodynamics and a large number of numerical predictions of foil characteristics. An optimum foil configuration is developed and towing tank tested with satisfactory results. The final proof of the concept is a successful on the water test with stable foiling at a speed of 12 knots.
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| 2. |
- Iraeus, Johan, 1973, et al.
(författare)
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Detailed subject-specific FE rib modeling for fracture prediction
- 2019
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 20:sup2, s. S88-S95
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The current state of the art human body models (HBMs) underpredict the number of fractured ribs. Also, it has not been shown that the models can predict the fracture locations. Efforts have been made to create subject specific rib models for fracture prediction, with mixed results. The aim of this study is to evaluate if subject-specific finite element (FE) rib models, based on state-of-the-art clinical CT data combined with subject-specific material data, can predict rib stiffness and fracture location in anterior-posterior rib bending. Method: High resolution clinical CT data was used to generate detailed subject-specific geometry for twelve FE models of the sixth rib. The cortical bone periosteal and endosteal surfaces were estimated based on a previously calibrated cortical bone mapping algorithm. The cortical and the trabecular bone were modeled using a hexa-block algorithm. The isotropic material model for the cortical bone in each rib model was assigned subject-specific material data based on tension coupon tests. Two different modeling strategies were used for the trabecular bone. The capability of the FE model to predict fracture location was carried out by modeling physical dynamic anterior-posterior rib bending tests. The rib model predictions were directly compared to the results from the tests. The predicted force-displacement time history, strain measurements at four locations, and rotation of the rib ends were compared to the results from the physical tests by means of CORA analysis. Rib fracture location in the FE model was estimated as the position for the element with the highest first principle strain at the time corresponding to rib fracture in the physical test. Results: Seven out of the twelve rib models predicted the fracture locations (at least for one of the trabecular modeling strategies) and had a force-displacement CORA score above 0.65. The other five rib models, had either a poor force-displacement CORA response or a poor fracture location prediction. It was observed that the stress-strain response for the coupon test for these five ribs showed significantly lower Young’s modulus, yield stress, and elongation at fracture compared to the other seven ribs. Conclusion: This study indicates that rib fracture location can be predicted for subject specific rib models based on high resolution CT, when loaded in anterior-posterior bending, as long as the rib’s cortical cortex is of sufficient thickness and has limited porosity. This study provides guide-lines for further enhancements of rib modeling for fracture location prediction with HBMs.
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| 3. |
- Lilja, Linus, et al.
(författare)
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Target temperature 34 vs. 36°C after out-of-hospital cardiac arrest - a retrospective observational study.
- 2017
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Ingår i: Acta anaesthesiologica Scandinavica. - : Wiley. - 1399-6576 .- 0001-5172. ; 61:9, s. 1176-1183
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Tidskriftsartikel (refereegranskat)abstract
- Intensive care for comatose survivors of cardiac arrest includes targeted temperature management (TTM) to attenuate cerebral reperfusion injury. A recent multi-center clinical trial did not show any difference in mortality or neurological outcome between TTM targeting 33°C or 36°C after out-of-hospital-cardiac-arrest (OHCA). In our institution, the TTM target was changed accordingly from 34 to 36°C. The aim of this retrospective study was to analyze if this change had affected patient outcome.Intensive care registry and medical record data from 79 adult patients treated for OHCA with TTM during 2010 (n=38; 34°C) and 2014 (n=41; 36°C) were analyzed for mortality and neurological outcome were assessed as cerebral performance category. Student's t-test was used for continuous data and Fischer's exact test for categorical data, and multivariable logistic regression was applied to detect influence from patient factors differing between the groups.Witnessed arrest was more common in 2010 (95%) vs. 2014 (76%) (P=0.03) and coronary angiography was more common in 2014 (95%) vs. 2010 (76%) (P=0.02). The number of patients awakening later than 72h after the arrest did not differ. After adjusting for gender, hypertension, and witnessed arrest, neither 1-year mortality (P=0.77), nor 1-year good neurological outcome (P=0.85) differed between the groups.Our results, showing no difference between TTM at 34°C and TTM at 36°C as to mortality or neurological outcome after OHCA, are in line with the previous TTM-trial results, supporting the use of either target temperature in our institution.
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| 4. |
- Lundin, Linus, 1993, et al.
(författare)
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Powered Two-Wheeler Rider Thoracic Impact Loading in Crashes with the Side of Passenger Cars: Literature Review and Human Body Model Validation
- 2023
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; , s. 445-468
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Konferensbidrag (refereegranskat)abstract
- Globally, powered two-wheeler (PTW) riders constitute a vulnerable road user group. This study aims to enhance the understanding of thoracic loading experienced by PTW riders in one of the most common crash configurations, PTW front to passenger car side (PFCS) impacts. A scoping review of the literature identified impact parameters describing common thoracic loading in terms of direction, location, distribution, and magnitude. Four experimental hub and bar post-mortem human subject (PMHS) test series, covering some of the identified variations in thoracic loading, were selected to validate the thorax of the SAFER human body model (HBM). The SAFER HBM demonstrated fair kinetics and kinematics biofidelity for frontal and oblique hub impacts and poor to fair biofidelity for the bar impacts. However, the SAFER HBM can accurately predict the rib fracture risk estimated from the PMHS tests. The findings demonstrate the potential of current HBMs to represent PTW-specific thoracic loading and support development of PTW rider safety systems in upright PFCS impacts. It also highlights a need for novel PMHS tests, in particular ones where the thorax is loaded above mid sternum and preferably including a vertical force component.
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| 5. |
- Lundin, Linus, 1993, et al.
(författare)
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Quantifying rider posture variability in powered two- and three-wheelers for safety assessment
- 2024
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Ingår i: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Injury outcomes for powered two- and three-wheeler (PTW) riders are influenced by the rider posture. To enable analysis of PTW rider accidents and development of protection systems, detailed whole-body posture data is needed. Therefore, the aim of this study is to fill this gap by providing collections of average male whole-body postures, including subpopulation variability, for different PTW types. This will enable future studies to explore the influence of PTW rider posture variation and to support safety system development. Methods: 3D photometric measurements of 51 anatomical landmarks were recorded on 20 (50th percentile male) volunteers in their preferred riding postures across three PTW types (naked, scooter, and touring). Following an outlier removal process, a principal component analysis (PCA) was performed to calculate average postures and principal components (PCs), to describe the observed posture variation, for each PTW. The visualization of the PCs was facilitated through kinematic linkage representations, connecting anatomical landmarks and estimated joint centers to form segments and characteristic joint angles. Results: The first seven PCs explained 80% of the variance in posture for each of the three PTWs. Across PTWs, these PCs frequently described combinations of postural features including variation in fore-aft seat positions, pelvic tilt, spinal curvature, head position, and extremity flexion-extension. Analysis revealed distinct differences in average postures across the three PTWs, on average, 10 ± 9° for the characteristic joint angles within a min-to-max range between the three PTWs. However, for all three PTWs, the variability between volunteers in characteristic joint angles on the same PTW were on average more than twice as large within a ± 2 SD range (26 ± 11°). Conclusions: The results suggest that PTW rider posture variation must be addressed by involving simultaneous adjustments of multiple body parts, as described by each of the first seven PCs, as a direct consequence of the human body interconnectedness. Furthermore, the study’s findings challenge conventional assumptions that the relative distance between PTWs’ handlebar, seat, and foot support predominantly influences rider postures. Instead, the research demonstrates that individual variability has a substantial influence on rider posture and should be considered in PTW safety development.
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| 6. |
- Pipkorn, Bengt, et al.
(författare)
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Head Injury Risks and Countermeasures for a Bicyclist Impacted by a Passenger Vehicle
- 2020
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Ingår i: Proceedings of International Research Council on the Biomechanics of Injury (IRCOBI) 2020.
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Konferensbidrag (refereegranskat)abstract
- The potential injury reducing benefits by a bicyclist helmet and a vehicle mounted bicyclist protectionairbag (BPA) was evaluated by means of human body model simulations. The human body model SAFER HBM waspositioned on a bicycle and impacted by a passenger vehicle in 40 km/h. Three conditions were evaluated; withoutcountermeasure, with helmet and helmet together with bicyclist protection airbag (BPA). Head injury risk wasevaluated by means of predicted HIC15, BrIC and strain in the brain.The impact conditions caused different impact points on the vehicle, windscreen and A-pillar. Both the impactpoints showed highest HIC and peak brain tissue strain for the case with no countermeasures and lowest valueswhen including both the helmet and BPA. BrIC increased when including the BPA for the windshield impact wherethe head did not impact the BPA, but a reduction was observed when the impact location was at the A-pillar.Generally head injury risk was reduced for a bicyclist wearing a helmet when impacted by a passenger vehiclein 40km/h. Additional reductions was obtained for a vehicle with a BPA. Therefore, the conclusion from this studywas that helmet and BPA have the potential to protect the head in vehicle to bicyclist impacts.
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