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- Karlsson, Alexander
(författare)
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Evaluating credal set theory as a belief framework in high-level information fusion for automated decision-making
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High-level information fusion is a research field in which methods for achieving an overall understanding of the current situation in an environment of interest are studied. The ultimate goal of these methods is to provide effective decision-support for human or automated decision-making. One of the main proposed ways of achieving this is to reduce the uncertainty, coupled with the decision, by utilizing multiple sources of information. Handling uncertainty in high-level information fusion is performed through a belief framework, and one of the most commonly used such frameworks is based on Bayesian theory. However, Bayesian theory has often been criticized for utilizing a representation of belief and evidence that does not sufficiently express some types of uncertainty. For this reason, a generalization of Bayesian theory has been proposed, denoted as credal set theory, which allows one to represent belief and evidence imprecisely. In this thesis, we explore whether credal set theory yields measurable advantages, compared to Bayesian theory, when used as a belief framework in high-level information fusion for automated decision-making, i.e., when decisions are made by some pre-determined algorithm. We characterize the Bayesian and credal operators for belief updating and evidence combination and perform three experiments where the Bayesian and credal frameworks are evaluated with respect to automated decision-making. The decision performance of the frameworks are measured by enforcing a single decision, and allowing a set of decisions, based on the frameworks’ belief and evidence structures. We construct anomaly detectors based on the frameworks and evaluate these detectors with respect to maritime surveillance. The main conclusion of the thesis is that although the credal framework uses considerably more expressive structures to represent belief and evidence, compared to the Bayesian framework, the performance of the credal framework can be significantly worse, on average, than that of the Bayesian framework, irrespective of the amount of imprecision.
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| 2. |
- Ahlbäck Öberg, Shirin, 1964-, et al.
(författare)
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En högskoleledning i fritt fall
- 2013
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Ingår i: Gefle Dagblad. - Gävle : Gefle Dagblad AB. - 1103-9302. ; :9/3
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 3. |
- Ahlbäck Öberg, Shirin, 1964-, et al.
(författare)
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MOOCs-studenter bildar B-laget
- 2013
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Ingår i: Upsala Nya Tidning. - Uppsala : AB Upsala Nya Tidning. - 1104-0173. ; :17/6
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 7. |
- Al Rashidi, Faleh, et al.
(författare)
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Comparison of the effectiveness and safety of a new de-airing technique with a standardized carbon dioxide insufflation technique in open left heart surgery: A randomized clinical trial.
- 2011
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Ingår i: The Journal of thoracic and cardiovascular surgery. - : Elsevier BV. - 1097-685X .- 0022-5223. ; okt, s. 1128-1133
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: We have compared the effectiveness, time required for de-airing, and safety of a newly developed de-airing technique for open left heart surgery (Lund technique) with a standardized carbon dioxide insufflation technique. METHODS: Twenty patients undergoing elective open aortic valve surgery were randomized prospectively to the Lund technique (Lund group, n = 10) or the carbon dioxide insufflation technique (carbon dioxide group, n = 10). Both groups were monitored intraoperatively during de-airing and for 10 minutes after weaning from cardiopulmonary bypass by transesophageal echocardiography and online transcranial Doppler for the severity and the number of gas emboli, respectively. The systemic arterial partial pressure of carbon dioxide and pH were also monitored in both groups before, during, and after cardiopulmonary bypass. RESULTS: The severity of gas emboli observed on transesophageal echocardiography and the number of microembolic signals recorded by transcranial Doppler were significantly lower in the Lund group during the de-airing procedure (P = .00634) and in the first 10 minutes after weaning from cardiopulmonary bypass (P = .000377). Furthermore, the de-airing time was significantly shorter in the Lund group (9 vs 15 minutes, P = .001). The arterial pH during the cooling phase of cardiopulmonary bypass was significantly lower in the carbon dioxide group (P = .00351), corresponding to significantly higher arterial partial pressure of carbon dioxide (P = .005196) despite significantly higher gas flows (P = .0398) in the oxygenator throughout the entire period of cardiopulmonary bypass. CONCLUSIONS: The Lund de-airing technique is safer, simpler, and more effective compared with the carbon dioxide insufflation technique. The technique is also more cost-effective because the de-airing time is shorter and no extra expenses are incurred.
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| 8. |
- Andersson, Sara-Linnea, et al.
(författare)
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Plug-in Hybrid Electric Vehicles as Regulating Power Providers - Case Studies of Sweden and Germany
- 2010
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Ingår i: Energy Policy. - : Elsevier BV. - 0301-4215. ; 38:6, s. 2751-2762
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates plug-in hybrid electric vehicles (PHEVs) as providers of regulating power in the form of primary, secondary and tertiary frequency control. Previous studies have shown that PHEVs could generate substantial profits while providing ancillary services. This study investigates under what conditions PHEVs can generate revenues using actual market data, i.e. prices and activations of regulating power, from Sweden and Germany from four months in 2008. PHEV market participation is modelled for individual vehicles in a fleet subject to a simulated movement pattern. Costs for infrastructure and vehicle-to-grid equipment are not included in the analysis. The simulation results indicate that maximum average profits generated on the German markets are in the range 30–80 h per vehicle and month whereas the Swedish regulating power markets give no profit.In addition, an analysis is performed to identify strengths, weaknesses, opportunities, and threats (SWOT) of PHEVs as regulating power providers. Based on the simulation results and the SWOT analysis, characteristics for an ideal regulating power market for PHEVs are presented.
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| 9. |
- Brax, Christoffer, et al.
(författare)
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Evaluating Precise and Imprecise State-Based Anomaly Detectors for Maritime Surveillance
- 2010
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Ingår i: Proceedings of the 13th International Conference on Information Fusion. - : IEEE. - 9780982443811 ; , s. Article number 5711997-
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Konferensbidrag (refereegranskat)abstract
- We extend the State-Based Anomaly Detection approach by introducing precise and imprecise anomaly detectors using the Bayesian and credal combination operators, where evidences over time are combined into a joint evidence. We use imprecision in order to represent the sensitivity of the classification regarding an object being normal or anomalous. We evaluate the detectors on a real-world maritime dataset containing recorded AIS data and show that the anomaly detectors outperform previously proposed detectors based on Gaussian mixture models and kernel density estimators. We also show that our introduced anomaly detectors perform slightly better than the State-Based Anomaly Detection approach with a sliding window.
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| 10. |
- Carlsson, Annelie, et al.
(författare)
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Low risk HLA-DQ and increased body mass index in newly diagnosed type 1 diabetes children in the Better Diabetes Diagnosis study in Sweden
- 2012
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Ingår i: International Journal of Obesity. - : Nature Publishing Group. - 0307-0565 .- 1476-5497. ; 36:5, s. 718-724
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Type 1 diabetes and obesity has increased in childhood. We therefore tested the hypothesis that type 1 diabetes human leukocyte antigen DQ (HLA-DQ) risk genotypes may be associated with increased body mass index (BMI). less thanbrgreater than less thanbrgreater thanDesign: The type 1 diabetes high-risk HLA-DQ A1*05:01-B1*02:01/A1*03:01-B1*03:02 genotype along with lower risk DQ genotypes were determined at the time of clinical onset by PCR and hybridization with allele-specific probes. BMI was determined after diabetes was stabilized. less thanbrgreater than less thanbrgreater thanSubjects: A total of 2403 incident type 1 diabetes children below 18 years of age were ascertained in the Swedish national Better Diabetes Diagnosis (BDD) study between May 2005 to September 2009. All children classified with type 1 diabetes, including positivity for at least one islet autoantibody, were investigated. less thanbrgreater than less thanbrgreater thanResults: Overall, type 1 diabetes HLA-DQ risk was negatively associated with BMI (Pandlt;0.0008). The proportion of the highest risk A1*05:01-B1*02:01/A1*03:01-B1*03:02 genotype decreased with increasing BMI (Pandlt;0.0004). However, lower risk type 1 diabetes DQ genotypes were associated with an increased proportion of patients who were overweight or obese (Pandlt;0.0001). Indeed, the proportion of patients with the low-risk A1*05:01-B1*02:01/A1*05:01-B1*02:01 genotype increased with increasing BMI (Pandlt;0.003). The magnitude of association on the multiplicative scale between the A1*05:01-B1*02:01/A1*05:01-B1*02:01 genotype and increased BMI was significant (Pandlt;0.006). The odds ratio in patients with this genotype of being obese was 1.80 (95% confidence interval 1.21-2.61; Pandlt;0.006). The increased proportion of overweight type 1 diabetes children with the A1*05:01-B1*02:01 haplotype was most pronounced in children diagnosed between 5 and 9 years of age. less thanbrgreater than less thanbrgreater thanConclusions: Susceptibility for childhood type 1 diabetes was unexpectedly found to be associated with the A1*05:01-B1*02:01/A1*05:01-B1*02:01 genotype and an increased BMI. These results support the hypothesis that overweight may contribute to the risk of type 1 diabetes in children positive for HLA-DQ A1*05:01-B1*02:01.
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