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| 2. |
- Hult, Johan, et al.
(author)
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Application of a high-repetition-rate laser diagnostic system for single-cycle-resolved imaging in internal combustion engines
- 2002
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In: Applied Optics. - 2155-3165. ; 41:24, s. 5002-5014
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Journal article (peer-reviewed)abstract
- High-repetition-rate laser-induced fluorescence measurements of fuel and OH concentrations in internal combustion engines are demonstrated. Series of as many as eight fluorescence images, with a temporal resolution ranging from 10 mus to 1 ms, are acquired within one engine cycle. A multiple-laser system in combination with a multiple-CCD camera is used for cycle-resolved imaging in spark-ignition, direct-injection stratified-charge, and homogeneous-charge compression-ignition engines. The recorded data reveal unique information on cycle-to-cycle variations in fuel transport and combustion. Moreover, the imaging system in combination with a scanning mirror is used to perform instantaneous three-dimensional fuel-concentration measurements.
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| 5. |
- Hultqvist, Anders, et al.
(author)
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The Hcci Combustion Process in a Single Cycle-High-Speed Fuel Tracer Lif and Chemiluminescence Imaging
- 2002
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In: SAE Technical Papers.
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Journal article (peer-reviewed)abstract
- The Homogeneous Charge Compression Ignition (HCCI) combustion progress has been characterized by means of high- speed fuel tracer Planar Laser-Induced Fluorescence (PLIF) combined with simultaneous chemiluminescence imaging. Imaging has been conducted using a high-speed laser and detector system. The system can acquire a sequence of eight images within less than one crank angle. The engine was run at 1200 rpm on iso-octane or ethanol and a slight amount of acetone was added as a fuel tracer, providing a marker for the unburned areas. The PLIF sequences showed that, during the first stage of combustion, a well distributed decay of fuel concentration occurs. During the later parts of the combustion process the fuel concentration images present much more structure, with distinct edges between islands of unburned fuel and products. The transition between the evenly distributed fuel oxidation in the beginning and the large structures at the end, is most likely the result of a gradual amplification of small temperature inhomogeneities and an expansion of burned gas compressing the unburned.
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| 7. |
- Nygren, Ingemar, et al.
(author)
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Robust Terrain Navigation with the Correlation Method for High Position Accuracy
- 2003
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In: OCEANS 2003 Marine Technology and Ocean Science Conference. - : IEEE. ; , s. 1269-1277
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Conference paper (peer-reviewed)abstract
- Describes the correlation method for determining the position of an autonomous underwater vehicle (AUV) in shallow waters. The method is conceptually simple. It involves measuring the seabed topography with a few sonar pings over a limited area by an ordinary bathymetric multibeam sonar. These measurements are then correlated with existing underwater maps. The position estimate from the correlation method can often be used as it is or fused by a linear Kalman filter with almost optimal performance. The paper also shows results from a sea-trial with the Reson SeaBat 8001 multibeam bathymetric sonar. The achieved 1/spl sigma/-circular accuracy is 0.3-0.4 metre in the north of the Baltic Sea.
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| 8. |
- Nygren, Ingemar, et al.
(author)
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Terrain navigation for underwater vehicles using the correlator method
- 2004
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In: IEEE Journal of Oceanic Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0364-9059 .- 1558-1691. ; 29:3, s. 906-915
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Journal article (peer-reviewed)abstract
- In many autonomous underwater vehicle (AUV) applications of long duration, there is a need to accurately determine the AUV's position in an effective way, in terms of both cost and energy consumption. Such situations may occur in reconnaissance operations, mine counter measure operations, and when an AUV is sampling the characteristics of the environment along a track. Since underwater maps are rare, there also is a need for navigational methods that can accommodate very infrequent sampling in terms of time and space. This paper describes a new method to solve the above problem by using a multibeam sonar for three-dimensional sampling of the bottom topography and a linear Kalman filter in a nearly optimal way. The proposed method is very accurate, robust, and computationally efficient compared to other methods that are used for terrain navigation. This method is also suitable for continuous navigation.
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| 9. |
- Nygren, Ingemar, et al.
(author)
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Terrain navigation using the correlator method
- 2004
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In: PLANS 2004. - NEW YORK : IEEE. - 0780384164 ; , s. 649-657
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Conference paper (peer-reviewed)abstract
- In many vehicle applications such as, unmanned air vehicles (UAV), autonomous underwater vehicles (AUV), and submarine applications, there is a need to robustly and accurately determine the vehicle's position relative to a map in an effective way in terms of both cost and energy consumption. Such situations may occur in reconnaissance operations. This paper discusses terrain navigation using the correlation method, used in a recursive manner, for determining the vehicle position. The position is determined by sampling the terrain topography with a multibeam radar or sonar and then match the measured topography with a map. Using several measuring beams leads to a linear Kalman filter problem with nearly optimal performance. The proposed method is very accurate, robust, and computationally efficient compared to other methods used for terrain navigation.
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| 10. |
- Nygren, Jenny, et al.
(author)
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Three-dimensional laser induced fluorescence of fuel distributions in an HCCI engine
- 2002
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In: Proceedings of the Combustion Institute. - 0082-0784 .- 1878-027X. ; 29, s. 679-685
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Conference paper (peer-reviewed)abstract
- Three-dimensional imaging of fuel tracer planar laser-induced fluorescence in a homogeneous charge compression ignition (HCCI) engine is presented. A high-speed multiple Nd:YAG laser and detection system, in combination, with a scanning mirror, are used to collect eight images, with an equidistant separation of 0.5 mm. Three-dimensional isoconcentration surfaces calculated from the data are visualized. Three-dimensional imaging offers new opportunities to study different combustion events, specifically the topology of flame structures. For example, it is possible to distinguish if separate islands in a fluorescence image really are separate or if it is an effect from wrinkling in and out of the laser sheet. The PLIF images were also analyzed by identifying five intensity ranges corresponding to increasing degrees of reaction progress. The gradual fuel consumption and thus combustion was then analyzed by calculating the volumetric fraction of these intensity ranges for different crank angle positions. The occurrence of multiple isolated ignition spots and the observed gradual decrease in fuel concentration indicates that HCCI combustion relies on distributed reactions and not flame propagation.
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| 11. |
- Wahlberg, Elisabet, et al.
(author)
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An affibody in complex with a target protein: Structure and coupled folding.
- 2003
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 100:6, s. 3185-3190
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Journal article (peer-reviewed)abstract
- Combinatorial protein engineering provides powerful means for functional selection of novel binding proteins. One class of engineered binding proteins, denoted affibodies, is based on the three-helix scaffold of the Z domain derived from staphylococcal protein A. The Z(SPA-1) affibody has been selected from a phage-displayed library as a binder to protein A. Z(SPA-1) also binds with micromolar affinity to its own ancestor, the Z domain. We have characterized the Z(SPA-1) affibody in its uncomplexed state and determined the solution structure of a Z:Z(SPA-1) protein-protein complex. Uncomplexed Z(SPA-1) behaves as an aggregation-prone molten globule, but folding occurs on binding, and the original (Z) three-helix bundle scaffold is fully formed in the complex. The structural basis for selection and strong binding is a large interaction interface with tight steric and polar/nonpolar complementarity that directly involves 10 of 13 mutated amino acid residues on Z(SPA-1). We also note similarities in how the surface of the Z domain responds by induced fit to binding of Z(SPA-1) and Ig Fc, respectively, suggesting that the Z(SPA-1) affibody is capable of mimicking the morphology of the natural binding partner for the Z domain.
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