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| 2. |
- 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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| 3. |
- Karlsson, Daniel, et al.
(författare)
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Experimental and theoretical study of the photodissociation of bromo-3-fluorobenzene
- 2008
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 128:3, s. 034307-
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Tidskriftsartikel (refereegranskat)abstract
- The UV photodissociation of bromo-3-fluorobenzene under collisionless conditions has been studied as a function of the excitation wavelength between 255 and 265 nm. The experiments were performed using ultrafast pump-probe laser spectroscopy. To aid in the interpretation of the results, it was necessary to extend the theoretical framework substantially compared to previous studies, to also include quantum dynamical simulations employing a two-dimensional nuclear Hamiltonian. The nonadiabatic potential energy surfaces (PES) were parameterized against high-level MS-CASTP2 quantum chemical calculations, using both the C–Br distance and the out-of-plane bending of the bromine as nuclear parameters. We show that the wavelength dependence of the photodissociation via the S0→1ππ*→1πσ* channel, accessible with a ∼ 260 nm pulse, is captured in this model. We thereby present the first correlation between experiments and theory within the quantitative regime.
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| 4. |
- Liu, Ya-Jun, et al.
(författare)
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Photodissociation of Bromobenzene, Dibromobenzene, and 1,3,5-Tribromobenzene
- 2004
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 120:14, s. 6502-
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Tidskriftsartikel (refereegranskat)abstract
- Quantum chemical calculations have been performed on the ground state and several low-lying excited states of bromobenzene, ortho-, meta-, and para-dibromobenzene, and 1,3,5-tribromobenzene using high-level ab initio and hybrid density-functional methods. Experimental observations of ultrafast predissociation in these molecules are clarified from extensive theoretical information about all low-energy potential-energy curves together with symmetry arguments. The intriguing observation that o- and m-dibromobenzene have two ultrafast predissociation channels while bromobenzene, p-dibromobenzene, and 1,3,5-tribromobenzene only have one such channel is explained from the calculated potential-energy curves. These show that the lowering of point-group symmetry from C2v to Cs along the main photodissociation reaction coordinate, which only occurs in o- and m-dibromobenzene, opens up a new predissociation channel. Dynamical quantum simulations based on the calculated potential-energy curves are used to estimate the coupling strength at the intersystem crossing point in bromobenzene.
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| 5. |
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| 6. |
- 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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| 7. |
- 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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| 8. |
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| 9. |
- Ahlbäck Öberg, Shirin, et al.
(författare)
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Projektsamhället och hoten mot akademin
- 2016
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Ingår i: Det hotade universitetet. - Stockholm : Dialogos Förlag. - 9789175042992 ; , s. 9-26
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 10. |
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