| 1. |
- Canon Falla, Gustavo, et al.
(författare)
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Characterization of unbound granular materials within a mechanistic design framework for low volume roads
- 2017
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Ingår i: Transportation Geotechnics. - : Elsevier Ltd. - 2214-3912. ; 13, s. 2-12
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Tidskriftsartikel (refereegranskat)abstract
- Unbound granular materials (UGM), used in base and subbase layers, play a major role in the structural performance of low volume roads (LVR) with a thin asphalt surface layer. A prerequisite for a proper design of such roads is the development of reliable testing techniques to simulate the behavior of UGMs under conditions similar to those that occur when subjected to traffic. Therefore, there is a need for simple and economical test methods to characterize the mechanical behavior of UGM under the action of high traffic loads. This paper presents a methodology for the experimental characterization of UGMs with a focus on mechanistic design. The results of a test campaign aimed at characterizing the elastic and plastic behavior of UGM are shown. The laboratory tests were performed using a new volumetric compaction tests and the triaxial test. Based on the results of the tests, a new classification method for UGMs intended to be used in the base course of thin asphalt pavements is suggested.
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| 2. |
- Erlingsson, S. I., et al.
(författare)
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Thermoelectric current in topological insulator nanowires with impurities
- 2018
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Ingår i: Beilstein Journal of Nanotechnology. - : Beilstein-Institut Zur Forderung der Chemischen Wissenschaften. - 2190-4286. ; 9:1, s. 1156-1161
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we consider charge current generated by maintaining a temperature difference over a nanowire at zero voltage bias. For topological insulator nanowires in a perpendicular magnetic field the current can change sign as the temperature of one end is increased. Here we study how this thermoelectric current sign reversal depends on the magnetic field and how impurities affect the size of the thermoelectric current. We consider both scalar and magnetic impurities and show that their influence on the current are quite similar, although the magnetic impurities seem to be more effective in reducing the effect. For moderate impurity concentration the sign reversal persists.
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| 3. |
- Erlingsson, Sigurd, et al.
(författare)
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Measurements Techniques for Water Flow
- 2009
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Ingår i: Water in road structures. - : Springer. - 9781402085611 ; , s. 45-67
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Bokkapitel (refereegranskat)
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| 4. |
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| 5. |
- Sjöberg, Lars Erik, et al.
(författare)
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Glacial rebound near Vatnajokull, Iceland, studied by GPS campaigns in 1992 and 1996
- 2000
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Ingår i: Journal of Geodynamics. - 0264-3707 .- 1879-1670. ; 29:2-Jan, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- Since about 1920 the Vatnajokull ice cap in Iceland has experienced a significant retreat, corresponding to a volume reduction of more than 180 km(3). With two GPS campaigns in 1992 and 1996 along the southern border of the glacier preliminary results reveal land uplift rates of 1-6 mm/yr, after a one-parameter (bias) fit with recent earth rheology models. The best fit model suggests that the lithosphere in the area is about 30 km thick and the viscosity of the asthenosphere 5 x 10(18) Pa s. The rms fit of uplift rate at all GPS sites is +/-1.4 mm/yr. As the GPS data alone cannot provide the absolute uplift rates, the one-parameter fit to the theoretical modelling implies that the absolute rates were estimated by the matching of the GPS data and model. The resulting uplift rate at station Hofn (1 mm/yr) is not consistent with two independent sources, and we therefore conclude that further GPS epoch and permanent GPS site data are needed to confirm the present geodynamic processes near Vatnajokull.
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| 6. |
- Sjöberg, Lars Erik, et al.
(författare)
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Land uplift near Vatnajokull, Iceland, as observed by GPS in 1992, 1996 and 1999
- 2004
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Ingår i: Geophysical Journal International. - 0956-540X .- 1365-246X. ; 159:3, s. 943-948
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Tidskriftsartikel (refereegranskat)abstract
- Warming of the climate in the 20th century has been manifested by an ablation of Europe's largest ice cap, Vatnajokull in Iceland. The thin elastic lithosphere and the low-viscosity asthenosphere are responding to the reduction in mass by current land uplift in the vicinity of the ice cap suggested to be of the order of 5-10 mm yr(-1): lithosphere thickness and asthenosphere viscosities compatible with these values have been inferred. From our repeated GPS epoch campaigns in 1992, 1996 and 1999 uplift rates are estimated to be of the order of 5-19 mm yr(-1), and the uplift rate is decreasing by -0.11 +/- 0.01 mm yr(-1) km(-1) with radial distance from the centre of the ice cap. These results deviate from previous Earth rheology models estimated for the region. Our data indicate that the lithosphere thickness might be of the order of 10-20 km and the asthenosphere viscosity may be as low as 5 x 10(17) Pa s, but these parameters need a careful fitting to the estimated uplift rates.
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| 7. |
- Vieira, Tiago, 1984-, et al.
(författare)
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Evaluation air void content of drilled porous asphalt mixture cores using non-destructive X-ray computed tomography
- 2021
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Ingår i: Proceedings Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields. - London : CRC Press. - 9781003222880 ; , s. 48-58
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Tomography technology is not usual when investigating drilled asphalt cores properties. Currently, there is no internationally recognised standard tomography method for asphalt pavements. Tomography provides, however, a non-destructive alternative to traditional, usually destructive, testing of drilled cores. Furthermore, tomography offers possibilities, which traditional laboratory analyses do not. It is not straightforward to distinguish mastic and aggre- gates in tomography results while air void content is less difficult to assess. To have a more reliable assessment of drilled cores properties found by tomography, the method must be carefully planned, executed, and the results compared to those of traditional laboratory methods. In this work, analysis was carried out using six in-situ drilled cores from a double layered porous asphalt pavement. This allowed a comparison of tomography and a standardised conventional laboratory air void measurement on the exact same samples. Comparisons of the air voids found by tomography in all three directions were also carried out, estimating how anisotropic and heterogeneous the samples are, which is not possible using traditional laboratory tests. As few as four tomography slices can give enough precision in the determination of air void content for the porous layers. No more than eight slices per sample were needed in the suggested tomog- raphy method. The statistical results did not indicate that the air void content determined by tomography is different from the laboratory results.
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