| 11. |
- Ekvall, Thomas, 1986, et al.
(författare)
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Sulphation of potassium chloride in air and oxy-fuel combustion
- 2013
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Ingår i: The Proceedings of the 38th International Technical Conference on Clean Coal & Fuel Systems, June 2-6 2013, Clearwater, Florida, USA.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- During combustion of biomass, alkali and chlorine species are released to the gas phase, species which can react to form corrosive salts that potentially may cause severe corrosion problems on heat transfer surfaces upon condensation. This corrosion process is referred to as high-temperature corrosion (HTC) and it limits steam data in biomass combustion, with corresponding limitation in thermal efficiency. The flue gas composition and also the HTC conditions can be altered by introducing a second fuel, e.g. coal for co-combustion. The flue gas composition can be altered even more drastically when applying oxy-fuel combustion where the concentration of combustion products are higher than in air firing due to the use of pure oxygen and flue gas recycling. In this work, the alkali sulphation process in different oxy-fuel and air-fuel atmospheres has been investigated by modelling the gas phase chemistry. The overall purpose is to examine the combined effects of oxy-combustion and co-combustion on the HTC process and to make a comparison with air-fired conditions. The flue gas composition in oxy-fuel combustion depends on the recirculation strategy used which in turn also influences the sulphation. According to the modelling results the degree of sulphation of gas-phase alkali metals is in general higher for oxy-fuel combustion compared to air-fuel combustion. It is concluded from the modelling results that an increased amount of sulphur and water contribute to a substantial effect on the degree of sulphation of alkali species. On the other hand, the modelling also shows that an increased content of HCl, which is present during wet recirculation, has a negative effect on the sulphation; the degree of sulphation is therefore lower in wet compared to dry recirculation. The effects of other important parameters such as sulphur-to-potassium and air-to-fuel ratios, temperature and residence time are also discussed further in the paper.
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| 12. |
- Gisselbrecht, Mathieu, et al.
(författare)
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Exploring single-photon ionization on the attosecond time scale
- 2012
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Ingår i: XXVII International Conference on Photonic, Electronic and Atomic Collisions (Icpeac 2011), Pts 1-15. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 388, s. 032025-032025
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Konferensbidrag (refereegranskat)abstract
- One of the fundamental processes in nature is the photoelectric effect in which an electron is ripped away from its atom via the interaction with a photon. This process was long believed to be instantaneous but with the development of attosecond pulses (1 as 10(-18) s) we can finally get an insight into its dynamic. Here we measure a delay in ionization time between two differently bound electrons. The outgoing electrons are created via ionization with a train of attosecond pulses and we probe their relative delay with a synchronized infrared laser. We demonstrate how this probe field influences the measured delays and show that this contribution can be estimated with a universal formula, which allows us to extract field free atomic data..
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| 13. |
- Guenot, Diego, et al.
(författare)
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Photoemission time delay measurements and calculations close to the 3s ionization cross section minimum in ar
- 2012
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 85:5, s. 053424-
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental measurements and theoretical calculations of photoionization time delays from the 3s and 3p shells in Ar in the photon energy range of 32-42 eV. The experimental measurements are performed by interferometry using attosecond pulse trains and the infrared laser used for their generation. The theoretical approach includes intershell correlation effects between the 3s and 3p shells within the framework of the random-phase approximation with exchange. The connection between single-photon ionization and the two-color two-photon ionization process used in the measurement is established using the recently developed asymptotic approximation for the complex transition amplitudes of laser-assisted photoionization. We compare and discuss the theoretical and experimental results, especially in the region where strong intershell correlations in the 3s -> kp channel lead to an induced Cooper minimum in the 3s ionization cross section.
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| 14. |
- Göransson, Lisa, 1982, et al.
(författare)
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Linkages between demand-side management and congestion in the European electricity transmission system
- 2014
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Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 69, s. 860-872
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Tidskriftsartikel (refereegranskat)abstract
- We evaluate the possibility to reduce congestion in the transmission grid through large-scale implementation of demand-side management (DSM) in the form of load shifting for the EU-27 countries, Norway, and Switzerland for Year 2020. A linear, cost-minimising, dispatch model that includes a DC load-flow description of the transmission system and a general representation of load shifting is used. It is assumed that the EU Member States fulfil the targets for Year 2020 in their national renewable energy action plans. In the model calculations, a reference case without load shifting is compared with cases in which the load shifting is 5%, 10%, 15% or 20% of the load. The possibility to shift load in time is added exogenously and economic incentives for DSM are not evaluated. Three types of congestion are identified: peak-load-hour congestion, low-load-hour congestion and all-hour congestion. Peak-load-hour congestion is reduced as the DSM share of the load increases, whereas low-load-hour congestion, which is typically associated with a high level of wind generation, persists at all the DSM penetration levels investigated. We show that all-hour congestion occurs between systems that have large differences in supply structure, and that the impact of DSM on all-hour congestion is low. (C) 2014 Elsevier Ltd. All rights reserved.
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| 15. |
- Jensen, Patrik, et al.
(författare)
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Configuration through the parameterization of building components
- 2012
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Ingår i: Automation in Construction. - : Elsevier BV. - 0926-5805 .- 1872-7891. ; 23, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Many construction companies have developed building systems, based on prefabrication strategies, to enhance productivity. Current practice coupled with the difficulties of introducing these systems early in the design process often leads to ad hoc solutions and problems downstream along the value chain. In 2008 a multi-storey timber building system based on modularization principles was developed. The customization process used in this system is illustrated herein using a configurable timber floor slab module. The downstream flow of design information and upstream flow of constraints on, and rules for, the building system are described from three product viewpoints: the customer view, the engineering view and the production view. Using a manufacturing CAD tool, design automation is implemented in the engineering view and connected to an architectural CAD tool. The demonstration software shows that manufacturing CAD tools can be used to create design automation alternatives for modularized building systems within the construction industry.
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| 16. |
- Johnsson, Mikael, 1972-, et al.
(författare)
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Innovation Advising in practice: Four cases where the RAFT model has been used in environmental innovations, and how twenty-one STPs offers Innovation Advising.
- 2010
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Ingår i: XXVII IASP World Conference on Science and Technology Parks, 2010. - Daejeon Convention Center, Korea.
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Konferensbidrag (refereegranskat)abstract
- Science and Technology Park's (STP) often offers business incubators to Idea owners where they can develop ideas into companies. The scope of this paper is a study in how the RAFT-model, a “How to”-model based innovation process, affected four Idea owners with environmental innovations in different business areas. This paper also shows how twenty-one Swedish STPs offer Innovation Advice (IA) to Idea owners and think of IA as a competitive offer. All Idea owners found the RAFT-model useful and consider using the RAFT-model again. Two ideas were still in a developing progress and the other two were shut down. Five of the STPs thought IA as a competitive offer to Idea owners, the others found IA proper to be offered by other organizations. Conclusions from this study are that the RAFT-model was appropriate to environmental innovations and STPs found IA valuable for Idea owners but not as a competitive motive.
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| 17. |
- Klünder, Kathrin, et al.
(författare)
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Probing Single-Photon Ionization on the Attosecond Time Scale
- 2011
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Ingår i: Physical Review Letters. - 1079-7114. ; 106:14
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Tidskriftsartikel (refereegranskat)abstract
- We study photoionization of argon atoms excited by attosecond pulses using an interferometric measurement technique. We measure the difference in time delays between electrons emitted from the 3s(2) and from the 3p(6) shell, at different excitation energies ranging from 32 to 42 eV. The determination of photoemission time delays requires taking into account the measurement process, involving the interaction with a probing infrared field. This contribution can be estimated using a universal formula and is found to account for a substantial fraction of the measured delay.
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| 18. |
- Kuepper, Jochen, et al.
(författare)
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X-Ray Diffraction from Isolated and Strongly Aligned Gas-Phase Molecules with a Free-Electron Laser
- 2014
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 112:8, s. 083002-
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Tidskriftsartikel (refereegranskat)abstract
- We report experimental results on x-ray diffraction of quantum-state-selected and strongly aligned ensembles of the prototypical asymmetric rotor molecule 2,5-diiodobenzonitrile using the Linac Coherent Light Source. The experiments demonstrate first steps toward a new approach to diffractive imaging of distinct structures of individual, isolated gas-phase molecules. We confirm several key ingredients of single molecule diffraction experiments: the abilities to detect and count individual scattered x-ray photons in single shot diffraction data, to deliver state-selected, e.g., structural-isomer-selected, ensembles of molecules to the x-ray interaction volume, and to strongly align the scattering molecules. Our approach, using ultrashort x-ray pulses, is suitable to study ultrafast dynamics of isolated molecules.
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| 19. |
- Mauritsson, Johan, et al.
(författare)
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Attosecond electron interferometry
- 2013
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Ingår i: Attosecond Physics : Attosecond Measurements and Control of Physical Systems - Attosecond Measurements and Control of Physical Systems. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1556-1534 .- 0342-4111. - 9783642376221 - 9783642376238 ; 177, s. 121-134
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Bokkapitel (refereegranskat)abstract
- Attosecond extreme ultraviolet light pulses have the potential to resolve the ultrafast electron dynamics that govern basic properties of atoms, molecules, and solids. Here we present three different interferometric pump-probe methods aiming to access not only the temporal dynamics, but also state specific phase information after excitation/ionization using attosecond pulses.
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| 20. |
- Mauritsson, Johan, et al.
(författare)
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Attosecond Electron Spectroscopy Using a Novel Interferometric Pump-Probe Technique
- 2010
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Ingår i: Physical Review Letters. - 1079-7114. ; 105:5
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Tidskriftsartikel (refereegranskat)abstract
- We present an interferometric pump-probe technique for the characterization of attosecond electron wave packets (WPs) that uses a free WP as a reference to measure a bound WP. We demonstrate our method by exciting helium atoms using an attosecond pulse (AP) with a bandwidth centered near the ionization threshold, thus creating both a bound and a free WP simultaneously. After a variable delay, the bound WP is ionized by a few-cycle infrared laser precisely synchronized to the original AP. By measuring the delay-dependent photoelectron spectrum we obtain an interferogram that contains both quantum beats as well as multipath interference. Analysis of the interferogram allows us to determine the bound WP components with a spectral resolution much better than the inverse of the AP duration.
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