| 1. |
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| 2. |
- Lee, Kyuho, et al.
(författare)
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Benchmarking van der Waals density functionals with experimental data: potential-energy curves for H2 molecules on Cu(111), (100) and (110) surfaces
- 2012
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Ingår i: Journal of Physics: Condensed Matter. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 24:42
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Tidskriftsartikel (refereegranskat)abstract
- Detailed physisorption data from experiment for the H2 molecule on low-index Cu surfaces challenge theory. Recently, density functional theory (DFT) has been developed to account for nonlocal correlation effects, including van der Waals (dispersion) forces. We show that the functional vdW-DF2 gives a potential-energy curve, potential-well energy levels and difference in lateral corrugation promisingly close to the results obtained by resonant elastic backscattering–diffraction experiments. The backscattering barrier is sensitive to the choice of exchange functional approximation. Further, the DFT-D3 and TS-vdW corrections to traditional DFT formulations are also benchmarked, and deviations are analyzed.
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| 3. |
- Hassellöv, Martin, 1970, et al.
(författare)
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REACH missar nano!
- 2009
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Ingår i: Miljöforskning. ; 2009:3-4
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Löfgren, Johan, 1983, et al.
(författare)
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High-rate local sea level monitoring with a GNSS-based tide gauge
- 2010
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Ingår i: Proceedings of the 2010 IEEE International Geoscience and Remote Sensing Symposium, Proceedings DVD-ROM. - 9781424495665 ; , s. 3616-3619
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present first results from the analysis of high-rate observations with a GNSS-based tide gauge at the Onsala Space Observatory. The goal is to determine local sea level with high temporal resolution. The GNSS-based tide gauge makes use of right-hand circular polarized GNSS signals that are directly received and left-hand circular polarized GNSS signals that are reflected from the sea surface. An experimental setup of the GNSS-based tide gauge was operated in the spring of 2010 and data were recorded with a sampling rate of 20 Hz.We analyzed data decimated to 1 Hz using different temporal resolution between 5 and 240 seconds, and the resulting time series of local sea level were compared to each other and to results from two stilling well gauges. The comparison with the data from the stilling well gauges shows a common trend.The comparison of the results from analyses with different temporal resolution show consistent results. There is also an indication that the GNSS-based tide gauge might be able to give information on the sea surface state.
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| 5. |
- Löfgren, Johan, 1983, et al.
(författare)
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Monitoring coastal sea level using reflected GNSS signals
- 2011
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Ingår i: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 47:2, s. 213-220
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Tidskriftsartikel (refereegranskat)abstract
- A continuous monitoring of coastal sea level changes is important for human society since it is predicted that up to 332 million people in coastal and low-lying areas will be directly affected by flooding from sea level rise by the end of the 21st century. The traditional way to observe sea level is using tide gauges that give measurements relative to the Earth’s crust. However, in order to improve the understanding of the sea level change processes it is necessary to separate the measurements into land surface height changes and sea surface height changes. These measurements should then be relative to a global reference frame. This can be done with satellite techniques, and thus a GNSS-based tide gauge is proposed. The GNSS-based tide gauge makes use of both GNSS signals that are directly received and GNSS signals that are reflected from the sea surface. An experimental installation at the Onsala Space Observatory (OSO) shows that the reflected GNSS signals have only about 3 dB less signal-to-noise-ratio than the directly received GNSS signals. Furthermore, a comparison of local sea level observations from the GNSS-based tide gauge with two stilling well gauges, located approximately 18 km and 33 km away from OSO, gives a pairwise root-mean-square agreement on the order of 4 cm. This indicates that the GNSS-based tide gauge gives valuable results for sea level monitoring.
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| 6. |
- Löfgren, Johan, 1983, et al.
(författare)
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Tropospheric correction for InSAR using interpolated ECMWF data and GPS zenith total delay from the Southern California Integrated GPS Network
- 2010
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Ingår i: Proceedings of the 2010 IEEE International Geoscience and Remote Sensing Symposium, Proceedings DVD-ROM. - 9781424495665 ; , s. 4503-4506
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A tropospheric correction method for Interferometric Synthetic Aperture Radar (InSAR) was developed using profiles from the European Centre for Medium-Range Weather Forecasts (ECMWF) and Zenith Total Delay (ZTD) from the Global Positioning System (GPS). The ECMWF data were interpolated into a finer grid with the Stretched Boundary Layer Model (SBLM) using a Digital Elevation Model (DEM) with a horizontal resolution of 1 arcsecond. The output were converted into ZTD and combined with the GPS ZTD in order to achieve tropospheric correction maps utilizing both the high spatial resolution of the SBLM and the high accuracy of the GPS. These maps were evaluated for three InSAR images, with short temporal baselines (implying no surface deformation), from Envisat during 2006 on an area stretching northeast from the Los Angeles basin towards Death Valley.The RMS in the InSAR images was greatly reduced, up to 32%, when using the tropospheric corrections. Two of the residuals showed a constant gradient over the area, suggesting a remaining orbit error. This error was reduced by reprocessing the troposphere corrected InSAR images with the result of an overall RMS reduction of 15 − 68%.
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| 7. |
- Chen, Zhe, et al.
(författare)
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Nano-scale characterization of white layer in broached Inconel 718
- 2017
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Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - Amsterdam : Elsevier BV. - 0921-5093 .- 1873-4936. ; 684, s. 373-384
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Tidskriftsartikel (refereegranskat)abstract
- The formation mechanism of white layers during broaching and their mechanical properties are not well investigated and understood to date. In the present study, multiple advanced characterization techniques with nano-scale resolution, including transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT) as well as nano-indentation, have been used to systematically examine the microstructural evolution and corresponding mechanical properties of a surface white layer formed when broaching the nickel-based superalloy Inconel 718.TEM observations showed that the broached white layer consists of nano-sized grains, mostly in the range of 20–50 nm. The crystallographic texture detected by TKD further revealed that the refined microstructure is primarily caused by strong shear deformation. Co-located Al-rich and Nb-rich fine clusters have been identified by APT, which are most likely to be γ′ and γ′′ clusters in a form of co-precipitates, where the clusters showed elongated and aligned appearance associated with the severe shearing history. The microstructural characteristics and crystallography of the broached white layer suggest that it was essentially formed by adiabatic shear localization in which the dominant metallurgical process is rotational dynamic recrystallization based on mechanically-driven subgrain rotations. The grain refinement within the white layer led to an increase of the surface nano-hardness by 14% and a reduction in elastic modulus by nearly 10% compared to that of the bulk material. This is primarily due to the greatly increased volume fraction of grain boundaries, when the grain size was reduced down to the nanoscale.
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| 8. |
- Hörnqvist Colliander, Magnus, 1979, et al.
(författare)
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Early stages of spinodal decomposition in Fe-Cr resolved by in-situ small-angle neutron scattering
- 2015
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 106:6
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Tidskriftsartikel (refereegranskat)abstract
- In-situ, time-resolved small-angle neutron scattering (SANS) investigations of the early stages of the spinodal decomposition process in Fe-35Cr were performed at 773 and 798K. The kinetics of the decomposition, both in terms of characteristic distance and peak intensity, followed a power-law behaviour from the start of the heat treatment (a' = 0.10-0.11 and a '' = 0.67-0.86). Furthermore, the method allows tracking of the high-Q slope, which is a sensitive measure of the early stages of decomposition. Ex-situ SANS and atom probe tomography were used to verify the results from the in-situ investigations. Finally, the in-situ measurement of the evolution of the characteristic distance at 773K was compared with the predictions from the Cahn-Hilliard-Cook model, which showed good agreement with the experimental data (a' = 0.12-0.20 depending on the assumed mobility).
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| 9. |
- Insulander Björk, Klara L, 1982
(författare)
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Thorium-plutonium fuel for long operating cycles in PWRs - preliminary calculations
- 2012
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Ingår i: Proceedings of the Thorium and Rare Earths Conference.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Preliminary calculations have been carried out to investigate the possibility of extending oper-ating cycle length in PWRs by use of Thorium-Plutonium mixed oxide fuel (Th-MOX). Thecalculations have been carried out in two dimensions, using the fuel assembly burnup simula-tion program CASMO-5. The reload scheme and the operating parameters are modelled on theSwedish PWR Ringhals 3 and a normal UOX fuel assembly designed for this reactor has beenused as a reference. Results show that an extension of the currently employed 12-month oper-ating cycle length is possible, either with a burnable absorber or with a modified fuel assemblydesign, assuming the same 3-batch reload scheme as currently used in Ringhals 3.The initial k∞ of the new Th-MOX fuel design was designed not to exceed that of the refer-ence UOX fuel. The power peaking factor is initially significantly lower than the reference,but slightly higher later in the life of the fuel assembly. All reactivity coefficients are withinacceptable range. The worth of control rods and soluble boron are lower than the reference, asexpected for a plutonium-bearing fuel.
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| 10. |
- Itkonen, Teemu, 1985, et al.
(författare)
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Characterisation of Motorway Driving Style Using Naturalistic Driving Data
- 2020
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Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour. - : Elsevier BV. - 1369-8478. ; 69, s. 72-79
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Tidskriftsartikel (refereegranskat)abstract
- The study of measurable differences between drivers has ramifications for several subfields in traffic and transportation research. Better understanding of the variability in individual driving styles would be especially useful for understanding driver preferences, psychological mechanisms for vehicle control and for developing more realistic traffic simulations. In our study based on a large naturalistic data set, we investigated the driving style of 76 individuals driving in a motorway setting. We discovered that the majority of between-driver variation in keeping longitudinal and lateral safety margins, lane changing frequency, acceleration and speed preference, can be reduced to two dimensions, which we interpret as habitualised motives centred around mental effort and expediency.
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