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- Hansson, Klas, 1944-
(author)
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I mål efter 40 år?
- 2004
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In: Svensk kyrkotidning. - 0346-2153. ; :49
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Journal article (pop. science, debate, etc.)abstract
- Artikeln sammanfattar det förslag till samtalsgruppen mellan Svenska kyrkan och Svenska missionskyrkan till kyrkogemenskap mellan samfunden 2004
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- Hansson, Klas, et al.
(author)
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Water flow and heat transport in frozen soil : Numerical solution and freeze-thaw applications
- 2004
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In: Vadose Zone Journal. - : Wiley. - 1539-1663. ; 3:2, s. 693-704
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Journal article (peer-reviewed)abstract
- A new method is presented to account for phase changes in a fully implicit numerical model for coupled heat transport and variably saturated water flow involving conditions both above and below zero temperature. The method is based on a mixed formulation for both water flow and heat transport similar to the approach commonly used for the Richards equation. The approach enabled numerically stable, energy- and mass-conservative solutions. The model was evaluated by comparing predictions with data from laboratory column freezing experiments. These experiments involved 20-cm long soil columns with an internal diameter of 8 cm that were exposed at the top to a circulating fluid with a temperature of −6°C. Water and soil in the columns froze from the top down during the experiment, with the freezing process inducing significant water redistribution within the soil. A new function is proposed to better describe the dependency of the thermal conductivity on the ice and water contents of frozen soils. Predicted values of the total water content compared well with measured values. The model proved to be numerically stable also for a hypothetical road problem involving simultaneous heat transport and water flow. The problem was simulated using measured values of the surface temperature for the duration of almost 1 yr. Since the road was snow-plowed during winter, surface temperatures varied more rapidly, and reached much lower values, than would have been the case under a natural snow cover. The numerical experiments demonstrate the ability of the code to cope with rapidly changing boundary conditions and very nonlinear water content and pressure head distributions in the soil profile.
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- Lundin, Lars-Christer, et al.
(author)
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Water and heat flow in a road construction
- 2004
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Conference paper (peer-reviewed)abstract
- Construction of new roads and maintenance of old ones are major undertakings in infrastructure management. Our wish for safe, comfortable and rapid road transportation has increased, creating new demands on road construction and maintenance. Road deterioration is costly for society and for transportation companies. The Swedish National Road Authority has thus invested large resources in developing a road deterioration model, in order to improve road construction and maintenance. A crucial factor for road deterioration is the ability to withstand the wear of passing vehicles. Since this ability is greatly decreased by moisture in the road construction, water and heat flow (to be able to account for freezing/thawing) modelling has become an important issue. As a part of this work, a freezing and thawing routine has been implemented in the HYDRUS1D/2D model codes. The routine has been tested in a laboratory column freezing experiment and in a hypothetical road situation, using climate data from northern Sweden. The objective of this presentation is to point out the need for hydrological contributions to road research and review potential models of water and heat flow to be used in this context, including the newly developed HYDRUS2D model code, including freezing and thawing routines.
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