| 1. |
- Löfgren, N., et al.
(författare)
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Remote sessions and frequency analysis for improved insight into cerebral function during pediatric and neonatal intensive care.
- 2003
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Ingår i: IEEE transactions on information technology in biomedicine. - 1089-7771 .- 1558-0032. ; 7:4, s. 283-90
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Tidskriftsartikel (refereegranskat)abstract
- A project involving recording and analysing EEG together with cardiovascular signals and temperature has been initiated. The aim of this project is to establish difficulties and possibilities involved with implementing a system for remote sessions and analysing EEG in correlation with other physiological signals. One objective is to find indicators of cerebral function during postasphyxia neonatal intensive care and pediatric cardiopulmonary bypass surgery with hypothermia. Remote sessions for joint interpretation have been carried out between pediatricians and clinical neurophysiologists, and EEG has been analyzed using frequency analyzing tools. One result is the discovery of reversible spectral changes coinciding with blood pressure falls, which may indicate loss of autoregulation function. This finding is one outcome from initial use of a system, developed during the project to facilitate communication about, and analysis of the recorded signals. Thus, already from a limited number of remote sessions and the use of basic signal processing techniques, important results have been achieved and better insight has been gained of how cerebral function is affected by cardiopulmonary bypass surgery. In this paper, we present our experiences from introducing a system for remote consultations, and evaluate the use for such a system in the current applications.
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| 2. |
- Hansson, Jörgen, et al.
(författare)
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Clearance of Flight Control Laws for Time-Varying Parameters
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this article exponential stability of the closed loop for the Saab AB VEGAS model controlled by a gain-scheduled linear fractional transformation controller is investigated for time-varying Mach-number. The analysis is based on parameter-dependent Lyapunov-functions which are obtained by investigating feasibility of linear matrix inequalities.
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| 3. |
- Wallin, Mikaela, 1975, et al.
(författare)
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Preparation of Mn, Fe and Co based perovskite catalysts using microemulsions
- 2004
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Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - : Elsevier BV. - 1873-4359 .- 0927-7757. ; 238:1-3, s. 27-35
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Tidskriftsartikel (refereegranskat)abstract
- Mixed metal oxides with perovskite structure were prepared using microemulsions. The perovskite materials had the nominal composition La0.8Sr0.2M1-xRhxO3 (where M = Mn, Co, Fe and x = 0, 0.1). X-ray diffraction analysis showed that the perovskite phase was generally obtained at relatively low temperatures, ≤700C. When the calcination temperature was kept low, the surface areas were relatively high and the highest surface area (25m2/g) was observed for La0.8Sr0.2Mn0.9Rh0.1O3 after calcination at 500C. Microstructural analysis using TEM and SEM showed particles in the size range of microns consisting of smaller crystallites in the range of 3050 nm. The materials were tested as catalysts for the selective reduction of NOx with NH3 (NH3-SCR) and the activity varied between samples with different transition metal. However, potassium, which originated from the technical surfactant used in the microemulsion, was detected by XRF analysis in various amounts in the samples and it was therefore not possible to conclude if the differences in catalytic performance were due to the different transition metals or to the potassium in the samples. Characterisation showed that it was possible to incorporate rhodium in the perovskite materials, which generally resulted in enhanced catalytic activities for the reduction of NOx with NH3.
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| 4. |
- Palmqvist, Anders, 1966, et al.
(författare)
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LOTUS: A co-operation for low temperature urea-based selective catalytic reduction of NOx
- 2004
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 20014
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Tidskriftsartikel (refereegranskat)abstract
- The European research co-operation Lotus is presented. The main objectives of the project were i) to show the potential for a urea-based SCR system to comply with the EU standard of years 2005 and 2008 for heavy-duty Diesel engines for different driving conditions with optimal fuel consumption, ii) to reach 95 % conversion of NOx at steady state at full load on a Euro III. engine, iii) to reach 75 % NOx reduction for exhaust temperatures between 200-300°C, and 85 % average NOx reduction between 200-500°C. The energy content of the consumed urea should not exceed 1.0 %, calculated as specific fuel consumption. These targets were met in May 2003 and the Lotus SCR system fulfilled the Euro V NOx legislative objectives for year 2008. Copyright © 2004 SAE International.
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| 5. |
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| 6. |
- Wallin, Mikaela, 1975, et al.
(författare)
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Selective catalytic reduction of NOx over H-ZSM-5 under lean conditions using transient NH3 supply
- 2004
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Ingår i: Topics in Catalysis. - 1572-9028 .- 1022-5528. ; 30/31:1-4, s. 107-113
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Tidskriftsartikel (refereegranskat)abstract
- The selective catalytic reduction (SCR) of NO x over zeolite H-ZSM-5 with ammonia was investigated using in situ FTIR spectroscopy and flow reactor measurements. The adsorption of ammonia and the reaction between NO x , O2 and either pre-adsorbed ammonia or transiently supplied ammonia were investigated for either NO or equimolar amounts of NO and NO2. With transient ammonia supply the total NO reduction increased and the selectivity to N2O formation decreased compared to continuous supply. The FTIR experiments revealed that NO x reacts with ammonia adsorbed on Brønsted acid sites as NH4 + ions. These experiments further indicated that adsorbed -NO2 is formed during the SCR reaction over H-ZSM-5.
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| 7. |
- Grigoriev, I. A., et al.
(författare)
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Explicit algebraic and differential Reynolds stress model application to homogeneously sheared and compressed turbulence
- 2015
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Ingår i: Proceedings - 15th European Turbulence Conference, ETC 2015. - : TU Delft.
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Konferensbidrag (refereegranskat)abstract
- An explicit algebraic and differential Reynolds stress models (EARSM and DRSM) are used to investigate the influence of homogeneous shear and compression on the behaviour of turbulence in the limit of rapid distortion theory (RDT). EARSM is shown to give realizable results and to preserve RDT regime, unlike the eddy-viscosity model (EVM). The DRSM version of our model is in reasonable agreement with RDT theory.
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| 8. |
- Hallberg, Håkan, et al.
(författare)
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Modeling of Continuous Dynamic Recrystallization in Aluminum
- 2009
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Ingår i: DCE Technical Memorandum No. 11. - 1901-7278. ; 11, s. 59-62
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Konferensbidrag (refereegranskat)abstract
- A constitutive model is presented, considering grain size refinement through continuous dynamic recrystallization together with an evolving dislocation density. The grain refinement is allowed to influence both the evolution of the dislocation density and the rate dependence of the material. The model is calibrated against experimental data on aluminum and numerical simulations of equal channel angular pressing (ECAP) material processing illustrates the capabilities of the model.
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| 9. |
- Wallin, Mikaela, 1975, et al.
(författare)
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Selective catalytic reduction of NOx with NH3 over H-ZSM-5: Influence of transient ammonia supply
- 2003
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Ingår i: Journal of Catalysis. - 0021-9517 .- 1090-2694. ; 218:2, s. 354-364
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Tidskriftsartikel (refereegranskat)abstract
- The effect of ammonia supply on the selective catalytic reduction of NOX over zeolite H-ZSM-5 was investigated using step response experiments between 200 and 500 degrees C. For inlet NO:NO2 ratios > 1, the activity for NOX reduction transiently increased when NH3 was removed from the feed. For NO:NO2 ratios less than or equal to 1, the NOX reduction however decreased. By pulsing NH3 to the feed, the activity for NO reduction was enhanced up to five times compared to continuous supply of ammonia. For NO:NO2 ratios exceeding one, also the selectivity towards N2O formation was lower with transient ammonia supply. Temperature programmed reaction experiments with preadsorbed NH3 showed highest initial NOX reduction activity when ammonia had been adsorbed at 300 or 250 degrees C compared to 200 degrees C. A minimum in NO reduction was observed at 130 degrees C independent of the ammonia adsorption temperature. For NO:NO2 ratios > 1, the results strongly indicate that NO oxidation is the rate determining step in the ammonia selective catalytic reduction (NH3-SCR) reaction over H-ZSM-5.
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| 10. |
- Wallin, Ragnar, et al.
(författare)
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Maximum likelihood estimation of linear SISO models subject to missing output data and missing input data
- 2014
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Ingår i: International Journal of Control. - : Taylor and Francis: STM, Behavioural Science and Public Health Titles. - 0020-7179 .- 1366-5820. ; 87:11, s. 2354-2364
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we describe an approach to maximum likelihood estimation of linear single input single output (SISO) models when both input and output data are missing. The criterion minimised in the algorithms is the Euclidean norm of the prediction error vector scaled by a particular function of the covariance matrix of the observed output data. We also provide insight into when simpler and in general sub-optimal schemes are indeed optimal. The algorithm has been prototyped in MATLAB, and we report numerical results that support the theory.
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