| 11. |
- Nekouei, Ehsan, et al.
(författare)
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Optimal Decision Fusion Under Order Effects
- 2019
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Ingår i: IFAC PAPERSONLINE. - : ELSEVIER SCIENCE BV. - 2405-8963. ; , s. 53-60
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Konferensbidrag (refereegranskat)abstract
- This paper studies an optimal decision fusion problem with a group of human decision makers when an order effect is present. The order effect refers to situations wherein the process of decision making by a human is affected by the order of decisions. In our set-up, all human decision makers, called observers, receive the same data which is generated by a common but unknown hypothesis. Then, each observer independently generates a sequence of decisions which are modeled by employing non-commutative probabilistic models of the data and their relation to the unknown hypothesis. The use of non-commutative probability models is motivated by recent psychological studies which indicate that these non-commutative probability models are more suitable for capturing the order effect in human decision making, compared with the classical probability model. A central decision maker (CDM) receives (possibly a subset of) the observers' decisions and decides on the true hypothesis. The considered problem becomes an optimal decision fusion problem with observations modeled using a non-commutative (Von Neumann) probability model. The structure of the optimal decision rule at the CDM is studied under two scenarios. In the first scenario, the CDM receives the entire history of the observers' decisions whereas in the second scenario, the CDM receives only the last decision of each observer. The perfromance of the optimal fusion rule is numerically evaluated and compared with the optimal fusion rule derived when using a classical probability model.
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| 12. |
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| 13. |
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| 14. |
- Skoglund, Lena, et al.
(författare)
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No evidence of PGRN or MAPT gene dosage alterations in a collection of patients with frontotemporal lobar degeneration
- 2009
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Ingår i: Dementia and Geriatric Cognitive Disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 28:5, s. 471-475
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aims Alterations in gene dosage have recently been associated with neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease, and deletions of the progranulin (PGRN) locus were recently described in patients with frontotemporal lobar degeneration (FTLD). FTLD is a genetically complex neurodegenerative disorder with mutations in the PGRN and the microtubule-associated protein tau (MAPT) genes being the most common known causes of familial FTLD. In this study, we investigated 39 patients with FTLD, previously found negative for mutations in PGRN and MAPT, for copy number alterations of these 2 genes. Methods Gene dosage analysis of PGRN and MAPT was performed using multiplex ligation-dependent probe amplification. Results We did not identify any PGRN or MAPT gene dosage variations in the 39 FTLD patients investigated. Conclusion We therefore conclude that alterations in gene copy number of PGRN and MAPT are not a cause of disease in this ollection of FTLD patients.
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| 15. |
- Skoglund, Lena, et al.
(författare)
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Novel Progranulin Mutation Detected in 2 Patients With FTLD
- 2011
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Ingår i: Alzheimer Disease and Associated Disorders. - : Lippincott Williams & Wilkins. - 0893-0341 .- 1546-4156. ; 25:2, s. 173-178
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Tidskriftsartikel (refereegranskat)abstract
- Frontotemporal lobar degeneration (FTLD) with ubiquitin-positive, tau-negative inclusions, and linkage to chromosome 17 was recently found to be caused by mutations in the progranulin (PGRN) gene. In this study, we screened a group of 51 FTLD patients for PGRN mutations and identified a novel exon 6 splice donor site deletion (IVS6+5_8delGTGA) in 2 unrelated patients. This mutation displayed an altered splicing pattern generating 2 aberrant transcripts and causing frameshifts of the coding sequence, premature termination codons, and a near absence of PGRN mRNA from the mutated alleles most likely through nonsense-mediated decay. The subsequent PGRN haploinsufficiency is consistent with previously described PGRN mutations. We present a molecular characterization of the IVS6+5_8delGTGA mutation and also describe clinical and neuropathologic features from the 2 patients carrying this PGRN mutation. From the screening of these 51 FTLD patients, we could also identify the earlier reported mutation Gln130fs, and several coding sequence variants that are most likely nonpathogenic.
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| 16. |
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| 17. |
- Skoglund, Oskar, et al.
(författare)
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A numerical evaluation of new structural details for an improved fatigue strength of steel bridges
- 2022
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Ingår i: International Journal of Fatigue. - : Elsevier BV. - 0142-1123 .- 1879-3452. ; 160
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Tidskriftsartikel (refereegranskat)abstract
- Fatigue is often the decisive design factor when designing steel bridges and improving the fatigue strength of critical details can reduce the amount of steel material used. In this paper, the fatigue strength of four different structural detail solutions are investigated and compared through numerical simulations. Two of the evaluated structural details have not been used before in bridge construction. The most promising structural detail managed to improve the fatigue strength by more than 25 % compared to the conventional solutions used today. The numerical studies were performed as a preparation for future testing.
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| 18. |
- Skoglund, Oskar, et al.
(författare)
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Distortion induced fatigue of web-gap details, a parametric study
- 2022
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Ingår i: Engineering structures. - : Elsevier Ltd. - 0141-0296 .- 1873-7323. ; 254
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Tidskriftsartikel (refereegranskat)abstract
- Prior to the mid 1980’s, bridge girders were often constructed with a gap between the end of the connection plate and the flange in tension. This practice was stopped due to early fatigue damage being developed in the web-gap region due to out-of-plane distortion. Several hundreds of bridges have suffered from this type of damage and more are yet to come. The aim of this paper is to get a better understanding of distortion induced fatigue through the study of deformation and contour plots together with a parametric study of some key parameters. The improved understanding will help engineers to identify bridges prone to this type of damage and to choose a suitable retrofitting procedure for damaged bridges. The results from this paper indicates that the distortion induced stresses in the lower web-gap are mainly caused by rotation of the cross-section. Meanwhile, the ones in the upper web-gap are mainly caused by the deformation of the concrete deck and the uneven deflection between the longitudinal girders. Furthermore, web-thickness and the distance from the cross-bracing to the supports were among the parameters with highest influence on the web-gap stresses.
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| 19. |
- Skoglund, Oskar
(författare)
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Fatigue of steel bridges : New structural details and the implementation of high strength steel
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of high strength steel has the potential to reduce the amount of steel used in bridge structures and thereby facilitate a more sustainable construction. The amount of steel and what steel grade that can be used in bridge structures and other cyclic loaded structures are often limited by a material degradation process called fatigue. The fatigue resistance of steel bridges is to a large extent depending on the design of structural details and connections. The design engineer is limited by the selection of a few pre-existing structural details with rather poor fatigue strength to choose from when designing steel bridges. Therefore, he/she is often forced to increase the overall dimensions of the structure to cope with the design requirements of fatigue.This doctoral thesis aims at increasing the fatigue resistance of fatigue prone structural details and connections by implementing new structural solutions to the already existing details given in the design standards. A typical fatigue prone detail is the vertical stiffener at an intermediate cross-beam, which will be in focus. By improving the fatigue resistance, less steel material will be required for the con-struction of new steel bridges and composite bridges of steel and concrete. It is shown in this thesis and the appended papers that the use of high strength steel for bridge structures can considerably reduce the amount of steel used, the cost of the steel material, and the harmful emissions. However, this is only true if the fatigue strength of critical details can be improved. This is shown through a survey of existing bridge structures and an optimisation of a steel and concrete composite bridge.Furthermore, a few new structural details are proposed and a few already existing solutions are highlighted that have the potential to improve the fatigue strength. The most promising structural detail could potentially increase the fatigue strength by 25 %. This is shown through numerical analyses using linear elastic fracture me-chanical models. However, the new structural details should be verified through fatigue experiments as a final step to determine their fatigue strength.
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| 20. |
- Skoglund, Oskar, et al.
(författare)
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Initial parameters to estimate the fatigue strength of welded structures using a fracture mechanical model
- 2022
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Ingår i: Engineering structures. - : Elsevier BV. - 0141-0296 .- 1873-7323. ; 260
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Tidskriftsartikel (refereegranskat)abstract
- Producing S-N curves using experimental testing is a costly and time-consuming practice. An alternative to experimental testing is to estimate the fatigue strength of welded steel structures by using a linear elastic fracture mechanical (LEFM) approach. However, to get reasonable estimations of the fatigue strength, a suitable choice of initial parameters has to be made. The objective of this paper is to produce recommendations for initial parameters based on a selection of fatigue experiments. The recommendations were verified against a fatigue experiment covering a corrugated web plate girder and provided a realistic estimation of the fatigue capacity.
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