| 1. |
- Wiedorn, Max O., et al.
(author)
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Megahertz serial crystallography
- 2018
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In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 9
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Journal article (peer-reviewed)abstract
- The new European X-ray Free-Electron Laser is the first X-ray free-electron laser capable of delivering X-ray pulses with a megahertz inter-pulse spacing, more than four orders of magnitude higher than previously possible. However, to date, it has been unclear whether it would indeed be possible to measure high-quality diffraction data at megahertz pulse repetition rates. Here, we show that high-quality structures can indeed be obtained using currently available operating conditions at the European XFEL. We present two complete data sets, one from the well-known model system lysozyme and the other from a so far unknown complex of a beta-lactamase from K. pneumoniae involved in antibiotic resistance. This result opens up megahertz serial femtosecond crystallography (SFX) as a tool for reliable structure determination, substrate screening and the efficient measurement of the evolution and dynamics of molecular structures using megahertz repetition rate pulses available at this new class of X-ray laser source.
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| 2. |
- Palmberg, Andréa, 1991, et al.
(author)
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The effect of curve geometry on driver behaviour in curves by using naturalistic driving data
- 2015
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In: Proceedings of the 3rd International Symposium on Future Active Safety Technology Towards Zero Traffic Accidents (FAST-zero 2015).
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Conference paper (peer-reviewed)abstract
- Traffic accidents are commonly found on horizontal curves. It is therefore important to study how the curve geometry affects the driver behaviour. This paper focuses on analysis of speed and maximal lateral acceleration in seven curves on two-lane rural highways in Sweden. The curve geometry factors studied are radii, presence and length of spiral transitions, tangent lengths and radius of previous curve. Of the studied factors, radii and spiral transitions were found to influence the driver behaviour most. Both larger radii and longer spiral transitions result in higher speeds in curves, and speed variations within curves seemed to be independent on choice of speed entering the curve.
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| 3. |
- Holmberg, Johan, et al.
(author)
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Catalytic and structural effects of W-substitution in M2 Mo-V-Te-oxide for propene ammoxidation
- 2007
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In: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 128:3-4, s. 153-160
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Journal article (peer-reviewed)abstract
- Substitution of W for the Mo in M2-type Mo-V-Te-oxide was investigated. XRD, FTIR, XANES, and HRTEM verified that the substitution is possible in the whole range up to complete replacement of Mo by W. Catalytic measurements for propene ammoxidation show that both the specific activity and the selectivity to acrylonitrile pass through a maximum with increase of the W-content of the catalyst. XRD analysis indicates that the catalytic results, in part, can be explained by a disordered distribution of Mo, W, and V among the octahedral sites in M2 giving better catalytic performance than a more ordered arrangement does. Moreover, SEM and HRTEM imaging show that with increasing W-content, the M2 crystals change from μm-sized elongated crystals to spherical crystals of nm-size, influencing the type of surfaces being exposed and consequently the catalytic properties. Among the catalysts investigated, a catalyst with the composition (Mo0.3W0.7)1.9V1.0Te1.1O10 is the most active and selective one, giving 80% selectivity to acrylonitrile.
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| 4. |
- Häggblad, Robert, et al.
(author)
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Oxidation of methanol to formaldehyde over a series of Fe(1-x)Al(x)-V-oxide catalysts
- 2008
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In: Journal of Catalysis. - : Elsevier BV. - 1090-2694 .- 0021-9517. ; 258:2, s. 345-355
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Journal article (peer-reviewed)abstract
- A series of triclinic Fe1−xAlxVO4 phases with 0 <= x <= 1 were prepared and used in the oxidation of methanol to formaldehyde. The activity measurements revealed that both the activity and especially the selectivity to formaldehyde increased with time of operation for at least 16 h, indicating restructuring of the catalysts. Characterisation of the catalysts with XRD, XANES, and electron microscopy after use in methanol oxidation showed that the stability of the bulk phases improved when Al was substituted for Fe in the structure. XRD and XANES of the used FeVO4 showed that it partly transformed into a cation-vacant spinel-type Fe1.5V1.5O4 phase, whereas the AlVO4 phase showed no change in the bulk structure. HRTEM imaging of used catalysts confirmed that structural changes,including in the surface, occurred during catalysis. Quantitative surface analysis by XPS of the catalysts before and after use in methanol oxidation revealed no significant change in the metal composition, in good agreement with the corresponding bulk values, except for a lower Fe value. Steady-state activity data showed a modest increase in specific activity with the Al content, whereas the selectivity to formaldehyde was about 90% for all samples at high methanol conversion. The similar catalytic behaviour of the vanadates irrespective of the differences in the bulk structure indicates that the surface structure differed from the bulk structure. Compared with pure vanadia, the vanadates had lower activity per V atom and slightly greater selectivity to formaldehyde. Consequently, for methanol oxidation, the role of Al and Fe on the catalyst surface can be described as that of a spacer, decreasing the surface concentration of active V sites and the number of less selective V–O–V ensembles.
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| 5. |
- Häggblad, Robert, et al.
(author)
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Substituted Mo-V(Ti)-Te(Ce)-oxide M2 catalysts for propene ammoxidation
- 2008
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In: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1572-9028 .- 1022-5528. ; 50:1-4, s. 52-65
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Journal article (peer-reviewed)abstract
- One of the most effective propane to acrylonitrile ammoxidation catalyst is comprised of the two phases M1 (orthorhombic) Mo7.5V1.5NbTeO29 and M2 (pseudo-hexagonal) Mo4V2Te2O20. Under reaction conditions, the two phases work in symbiosis with each other where M1 is the paraffin activating component and M2 is the olefin activating component. Since the catalytic improvement of either phase should result in an enhancement of the overall acrylonitrile yield, controlled substitution of certain elements in either or both phases might result in the desired improvement. Our current study concentrates on the partial substitutions of V with Ti and Te with Ce in the M2 phase. Ti substitution results in a considerable propene activity improvement, whereas the selectivity to acrylonitrile is unaffected. Substitution with Ce, on the contrary, substantially improves the selectivity to acrylonitrile. Also, a minor improvement of the activity is notable. The acrylonitrile selectivity improvement is a result of better NH3 utilization and comes at the expense of reduced acrolein make. XRD reveals that all of the substituted compositions retain the M2 structure and essentially are monophasic. XANES recordings show for the bulk that the Mo is 6+, the V is 4+, or 4+ and 5+ when Ce is present, the Ti is 4+, the Ce is 3+, and the Te 4+ with some 6+ also present. According to the ESR data, in the M2 with Ce (7Te/3Ce) only 21% of the V is 4+, the remainder being 5+, which tentatively can be explained by the existence of some cation vacancies in the hexagonal channels. HRTEM imaging reveals little if any differences between the materials, all have the typical pseudo-hexagonal habit of the M2 phase and expose a 1-2 nm thick surface layer without any apparent long-range ordering. XPS data show that all catalysts, including the base, are highly enriched at the surface with Te at the expense of other metals. The 7Te/3Ce composition exhibits also substantial Ce surface enrichment. Moreover, the valences of the cations at the surface differ from the bulk in that for all fresh catalysts V is 5+ and Te is 6+ on the surface. Characterization by XPS of catalysts used in propene ammoxidation, reveals reduction of Te and, except when Ce is present, also Mo. Therefore, it might be inferred that the surfaces of the catalysts studied here are comprised essentially of one or a few monolayers of TeMoO or TeCeMoO on an interacting M2 crystalline base.
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| 6. |
- Sahlin, Jakob, et al.
(author)
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Transmission Line Loss Prediction Based on Linear Regression and Exchange Flow Modelling
- 2017
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In: 2017 IEEE Manchester PowerTech, Powertech 2017. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509042371
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Conference paper (peer-reviewed)abstract
- Inaccurate line loss predictions leads to additional regulation costs for Transmission System Operators (TSOs) that place energy bids at the day-ahead market to account for these losses. This paper presents a line loss prediction model design, applicable with the TSOs forecast conditions, that can reduce additional expenditure due to inaccurate predictions. The model predicts line losses for the next day per bidding area in relation to prognosis data on electrical demand, supply, renewable energy generation and regional exchange flows. Linear regression analysis can extract these relation factors, known as line loss rates, and derive a line loss prediction with increased accuracy and precision. Required input data is available at the power exchange markets apart from future exchange flows, which instead have been modelled as an optimisation problem and predicted by linear programming. Simulations performed on the Swedish National Grid for 2015 demonstrate the models performance and adequacy for TSO application.
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| 7. |
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| 8. |
- Broström, Robert, et al.
(author)
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Correlation between safety assessments in the driver-car interaction design process
- 2011
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In: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 42:4, s. 575-582
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Journal article (peer-reviewed)abstract
- With the functional revolution in modern cars, evaluation methods to be used in all phases of driver-car interaction design have gained importance. It is crucial for car manufacturers to discover and solve safety issues early in the interaction design process. A current problem is thus to find a correlation between the formative methods that are used during development and the summative methods that are used when the product has reached the customer. This paper investigates the correlation between efficiency metrics from summative and formative evaluations, where the results of two studies on sound and navigation system tasks are compared. The first, an analysis of the J.D. Power and Associates APEAL survey, consists of answers given by about two thousand customers. The second, an expert evaluation study, was done by six evaluators who assessed the layouts by task completion time, TLX and Nielsen heuristics. The results show a high degree of correlation between the studies in terms of task efficiency, i.e. between customer ratings and task completion time, and customer ratings and TLX. However, no correlation was observed between Nielsen heuristics and customer ratings, task completion time or TLX. The results of the studies introduce a possibility to develop a usability evaluation framework that includes both formative and summative approaches, as the results show a high degree of consistency between the different methodologies. Hence, combining a quantitative approach with the expert evaluation method, such as task completion time, should be more useful for driver-car interaction design.
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| 9. |
- Broström, Robert, et al.
(author)
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Perceived styling and usability in integrated centre panel layouts as a function of interaction style and age
- 2007
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In: Human Factors Issues in Complex System Performance. - Maastricht : Shaker Verlag. - 9789042303256 ; , s. 193-204
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Conference paper (peer-reviewed)abstract
- In the past ten years information and entertainment functionality has become an increasingly important part of the car interior. Infotainment functions have been growing in number and diversity, concurrently with a trend towards utilization of fewer controls and graphical displays in integrated centre panel layouts. This evolution has solved many functional and styling issues. However, as a consequence, several usability and safety concerns have been raised. A number of these concerns are related to age, a factor that is especially important in the premium car segment where a majority of drivers are older than 50 years. This study investigated perceived styling and usability of premium car centre panel layouts among different age groups. The investigation was based on APEAL customer survey data from the North American market, associated with the sound system. Questions on the appearance (styling), understanding (usability) and ease of use while driving (usability/safety) of the stereo faceplate and controls were analysed. The results showed that all age groups perceived the appearance of integrated centre panel layouts similarly. However, with rising age, there is a decrease in perceived understanding and ease of use while driving in the case of a number of premium car models.
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| 10. |
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