| 1. |
- Borga, Magnus, et al.
(author)
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A Unified Approach to PCA, PLS, MLR and CCA
- 1997
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Reports (other academic/artistic)abstract
- This paper presents a novel algorithm for analysis of stochastic processes. The algorithm can be used to find the required solutions in the cases of principal component analysis (PCA), partial least squares (PLS), canonical correlation analysis (CCA) or multiple linear regression (MLR). The algorithm is iterative and sequential in its structure and uses on-line stochastic approximation to reach an equilibrium point. A quotient between two quadratic forms is used as an energy function and it is shown that the equilibrium points constitute solutions to the generalized eigenproblem.
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| 3. |
- Bui, Hai Thanh, 1972-, et al.
(author)
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Group theoretical investigations of daylight spectra
- 2004
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In: 2nd European Conference on Color in Graphics, Imaging and Vision,2004. - Springfield, VA, USA : IST: The Society for Imaging Science and Technology. ; , s. 437-
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Conference paper (peer-reviewed)
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| 4. |
- Campana, Pietro Elia, 1984-, et al.
(author)
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A gridded optimization model for photovoltaic applications
- 2020
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In: Solar Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0038-092X .- 1471-1257. ; 202, s. 465-484
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Journal article (peer-reviewed)abstract
- This study aims to develop a gridded optimization model for studying photovoltaic applications in Nordic countries. The model uses the spatial and temporal data generated by the mesoscale models STRANG and MESAN developed by the Swedish Meteorological and Hydrological Institute. The model is developed based on the comparison between five irradiance databases, three decomposition models, two transposition models, and two photovoltaic models. Several techno-economic and environmental aspects of photovoltaic systems and photovoltaic systems integrated with batteries are investigated from a spatial perspective. CM SAF SARAH-2, Engerer2, and Perez1990 have shown the best performances among the irradiance databases, and decomposition and transposition models, respectively. STRANG resulted in the second-best irradiance database to be used in Sweden for photovoltaic applications when comparing hourly global horizontal irradiance with weather station data. The developed model can be employed for carrying out further detailed gridded techno-economic assessments of photovoltaic applications and energy systems in general in Nordic countries. The model structure is generic and can be applied to every gridded climatological database worldwide.
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| 7. |
- Hellgren, Laila, et al.
(author)
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Severe mitral regurgitation : relations between magnetic resonance imaging, echocardiography and natriuretic peptides
- 2008
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In: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 42:1, s. 48-55
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Journal article (peer-reviewed)abstract
- BACKGROUND:Assessment of the severity of mitral regurgitation by echocardiography can be technically demanding in certain patients and supplementary methods are therefore desirable. This study addressed the agreement between magnetic resonance imaging (MRI) and echocardiography, and their relations to natriuretic peptides (NT-proANP and NT-proBNP), in quantifying severe mitral regurgitation.METHODS:Eighteen patients with severe mitral regurgitation scheduled for surgery underwent MRI, echocardiography and assay of natriuretic peptides preoperatively for clinical assessment.RESULTS:MRI and echocardiography were comparable in measuring severity of regurgitation qualitatively but not quantitatively, mitral regurgitant fraction (mean difference 27.5 (11) ml). There was a correlation between increasing regurgitant fraction on MRI and increased levels of plasma NT-proANP and NT-proBNP. In echocardiography, increasing vena contracta width and increasing PISA correlated to increased levels of plasma NT-proANP and NT-proBNP. No other correlation was found between measures on MRI and echocardiography and natriuretic peptides.CONCLUSIONS:MRI and echocardiography were comparable grading the severity of mitral regurgitation with qualitative measures but not with quantitative measures. MRI might be a complement to echocardiography when a more distinct measure of the regurgitant volume is needed, as in paravalvular leakage.
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| 8. |
- Knutsson, Hans, et al.
(author)
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Generalized Eigenproblem for Stochastic Process Covariances
- 1996
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Reports (other academic/artistic)abstract
- This paper presents a novel algorithm for finding the solution of the generalized eigenproblem where the matrices involved contain expectation values from stochastic processes. The algorithm is iterative and sequential to its structure and uses on-line stochastic approximation to reach an equilibrium point. A quotient between two quadratic forms is suggested as an energy function for this problem and is shown to have zero gradient only at the points solving the eigenproblem. Furthermore it is shown that the algorithm for the generalized eigenproblem can be used to solve three important problems as special cases. For a stochastic process the algorithm can be used to find the directions for maximal variance, covariance, and canonical correlation as well as their magnitudes.
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| 9. |
- Knutsson, Hans, et al.
(author)
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Learning Canonical Correlations
- 1995
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Reports (other academic/artistic)abstract
- This paper presents a novel learning algorithm that finds the linear combination of one set of multi-dimensional variates that is the best predictor, and at the same time finds the linear combination of another set which is the most predictable. This relation is known as the canonical correlation and has the property of being invariant with respect to affine transformations of the two sets of variates. The algorithm successively finds all the canonical correlations beginning with the largest one. It is shown that canonical correlations can be used in computer vision to find feature detectors by giving examples of the desired features. When used on the pixel level, the method finds quadrature filters and when used on a higher level, the method finds combinations of filter output that are less sensitive to noise compared to vector averaging.
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| 10. |
- Knutsson, Hans, 1950-, et al.
(author)
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Learning Multidimensional Signal Processing
- 1998
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In: Proceedings of the 14th International Conference on Pattern Recognition, vol 2. - Linköping, Sweden : Linköping University, Department of Electrical Engineering. ; , s. 1416-1420
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Reports (other academic/artistic)abstract
- This paper presents our general strategy for designing learning machines as well as a number of particular designs. The search for methods allowing a sufficient level of adaptivity are based on two main principles: 1. Simple adaptive local models and 2. Adaptive model distribution. Particularly important concepts in our work is mutual information and canonical correlation. Examples are given on learning feature descriptors, modeling disparity, synthesis of a global 3-mode model and a setup for reinforcement learning of online video coder parameter control.
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