| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Lundgren, Sarah M., et al.
(författare)
-
Unsaturated fatty acids in alkane solution : adsorption to steel surfaces
- 2007
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 23:21, s. 10598-10602
-
Tidskriftsartikel (refereegranskat)abstract
- The adsorption of the unsaturated fatty acids oleic, linoleic, and linolenic acid on steel surfaces has been investigated by means of a quartz crystal microbalance (QCM). Two different solvents were used, n-hexadecane and its highly branched isomer. viz.. 2.2,4,4,6,8,8-heptamethylnonane. The area occupied per molecule of oleic acid at 1 wt % corresponds to what is needed for adsorption parallel to the surface. At the same concentration, the adsorbed amount of linoleic acid and linolenic acid indicates that they adsorb in multilayers. The chemisorbed amount estimated from static secondary ion mass spectroscopy (SIMS) measurements was found to be similar for the three unsaturated fatty acids. In the case of linolenic acid, it was found that the presence of water significantly alters the adsorption, most likely because of the precipitation of fatty acid/water aggregates. Furthermore, static SIMS results indicate that the amount of water used here inhibits the chemisorption of linolenic acid.
|
|
| 5. |
- Sielemann, Michael, et al.
(författare)
-
Select trade-offs in parallel hybrid turboprop cycle design
- 2022
-
Ingår i: Proceedings of the ASME Turbo Expo. - : American Society of Mechanical Engineers (ASME). - 9780791885970
-
Konferensbidrag (refereegranskat)abstract
- Parallel hybrid turboprop engines propose a means to reduce fuel consumption of regional aircraft due to lower flight velocities. They feature an electric drive, typically on the free power turbine, and require a design trade-off between the gas turbine and electric power sub-system characteristics. Degrees of freedom include the nozzle expansion, the propeller power loading, the gear ratio, and the selection of shaft speeds. The latter for instance requires a trade-off between propeller and free power turbine efficiency. For a parallel hybrid, the electric machine efficiency becomes a third factor to consider. The objective of this paper is to expose some key aspects of these trade-offs in terms of efficiency and weight. The paper applies sophisticated methodology in both the gas turbine and electrical power domains. For the gas turbine, multi-point design is used. Here, an extension of established synthesis matching schemes is used, which covers the design and operation rules also for the electric components of the hybrid. For the electrical machine, fully analytical sizing is used, which also captures the impact of cooling. For all main gas turbine components and the electric machine, the geometry is estimated based on the sizing methodology, and used as input for the weight estimation. Results are presented for parallel hybrid electric 2.5-spool geared turboprop architectures fulfilling requirements of a notional 19 passenger regional aircraft. Uninstalled fuel consumption can be lower for the hybrid than the conventional baseline, and the key relations to typical cycle parameters such as overall pressure ratio and shaft speed selection are exposed. Overall, the benefit of hybridization is low however with the concept of operations inspired by hybrid turbofans. This is related to differences in contradicting cycle design requirements.
|
|
| 6. |
- Stålgren, Johan Jim Roger, et al.
(författare)
-
Synthesis and characterization of cationic polymeric salts : derivatives of 2-(dimethylamino)ethyl-2-methacrylate, containing oligomeric ethylene oxide side-chains
- 2003
-
Ingår i: Polymer international. - : Wiley. - 0959-8103 .- 1097-0126. ; 52:3, s. 399-405
-
Tidskriftsartikel (refereegranskat)abstract
- A novel set of cationic polyelectrolytes has been prepared. The polyelectrolytes have a high cationicity with each segment carrying one positively charged quaternary ammonium group. The polyelectrolytes also contain grafted oligo(ethylene oxide) (110) chains. The grafted EO chains are, according to NMR measurements, six units long. The graft density of EO chains has been varied and polymers having approximately 100%, 20% and 10% of the segments with a grafted EO chain have been prepared. The obtained products were characterized using H-1 and C-13 NMR spectroscopy. Aqueous solutions of the cationic polymers were characterized by dynamic light-scattering (DLS) measurements. It was found to be important to include a radical inhibitor to prevent crosslinking reactions during isolation and purification. In general the DLS measurements showed a bimodal size distribution. The majority of the polymers (about 75wt%) were found to have a hydrodynamic radius of 6-8 mn, with the remaining polymers being dominated by a fraction with a hydrodynamic radius in the range 120-140nm.
|
|
