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1.
  • Semadeni Davies, Annette, et al. (författare)
  • Radiation balance of urban snow : a water management perspective
  • 2001
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 33:1, s. 59-76
  • Tidskriftsartikel (refereegranskat)abstract
    • The radiation balance of urbanised catchments differs from their rural counterparts, with snowpacks experiencing either enhanced or decreased irradiance depending on snowpack location and condition. As snowmelt is largely driven by radiation inputs, changes to localised irradiance (and melt rates) have implications for urban runoff generation. Storm- and wastewater drainage systems in cold regions are currently dimensioned for rain according to practices developed for temperate climates. They are not designed to cope with wintry conditions, which can lead to surface flooding, hydraulic overloads and poor water quality at receiving waters. Net allwave radiation measurements over snow made at the Swedish city of Luleå during April 1997 and 1998 are presented. The 1997 measurements were made in the vicinity of a matt-black-painted metal building at Luleå University of Technology, whereas the 1998 measurements are from a specially constructed 3×6-m black plastic-clad wall built on an open field just outside the town. Black minimises multiple reflections between the snow and walls, while maximising absorption of shortwave radiation by walls. The data were compared to the outputs of an urban radiation model. The results show that urban structures significantly alter radiation over snow. The temperature of the south-facing walls translates to longwave enhancements in the order of 150 W m−2 for several metres from the walls on sunny days. Shaded snow near the north-facing wall showed a net allwave radiation loss of the same order of magnitude. Radiation inputs to snow are similar both to the north and south of walls when the sky is overcast. The need to include snowmelt energetics within design and management techniques is discussed in light of the results.
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2.
  • Bengtsson, Lars (författare)
  • Percolation of meltwater through a snowpack
  • 1982
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 6:1, s. 73-81
  • Tidskriftsartikel (refereegranskat)abstract
    • The hydraulics of meltwater percolation through a snowpack is analyzed in some detail. An implicit numerical model is used for determining the meltwater movement. The effect of freezing fronts of the free liquid water in the snowpack is evaluated. It is shown that even after a moderately cold night, it takes several hours of snowmelt before the snowpack again reaches its irreducible liquid content. The meltwater flux front moves very slowly down through the depth, where the liquid water has been refrozen during a preceding night. The time delay between the initiation of snowmelt at the surface and the start of run-off at the base of the snowpack is shown to be determined from a simple continuity reasoning. Finally, a comparison between theory and field measurements is made.
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3.
  • Lundberg, Angela (författare)
  • Laboratory calibration of TDR-probes for snow wetness measurements
  • 1997
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 25:3, s. 197-205
  • Tidskriftsartikel (refereegranskat)abstract
    • In situ registration of snow liquid water content for avalanche protection and snow-melt prognosis is much needed. The Time Domain Reflectometry (TDR) method is a possible method to meet this need. Laboratory comparison of the TDR-method with the dilution method shows that the TDR-method has the potential to register variations in snow liquid water content down to 1-2 vol.%. It should be possible to achieve continuous registration of snow-pack wetness with a spatial resolution down to approximately 5 cm with several sets of TDR-probes (mounted with 3 cm vertical and 5 cm horizontal distance) combined with a multiplexer and a storage unit. For application when changes in snow density are great (as with newly fallen snow) the method has to be combined with separate density determinations. The dielectric constant of night-time refrozen snow can be used for density determination.
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4.
  • Maurice, Christian, et al. (författare)
  • LFG emission measurements in cold climatic conditions : seasonal variations and methane emissions mitigation
  • 2003
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 36:1-3, s. 37-46
  • Tidskriftsartikel (refereegranskat)abstract
    • Landfill gas (LFG) emissions were measured at three landfills in Northern Sweden and Northern Finland. Several strategies for measuring gas emissions in winter conditions (i.e., a snow-covered surface and frozen ground) were tested. Static chambers appeared to be the most suitable measurement technique. The study results showed that winter measurements should be done directly at the soil surface and that any snow cover should be removed beforehand. A seasonal variation of the emissions was observed. Methane emissions were measured during late winter at the three sites and during late summer at two of the same three sites. Monitoring performed during the different seasons yields a better estimation of the annual LFG emissions. Variations in methane oxidation are likely sources of any differences as low temperature and low soil water content both reduce methane oxidation activity. At low emission rates, the main methane emission may occur during wintertime because of the mitigation effect landfill cover has on methane oxidation during summertime. A reduced methane oxidation activity was observed during the late summer at two of the sites. A combination of summer dryness and heat from methane oxidation is believed to have dried the soil, which then caused a subsequent decrease in methane oxidation. To use landfill covers for the management of methane emissions in cold climates, special consideration must be given to the moisture and extreme low temperature factors.
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5.
  • Nordell, Bo (författare)
  • Measurement of P -T coexistence curve for ice-water mixture
  • 1990
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 19:1, s. 83-88
  • Tidskriftsartikel (refereegranskat)abstract
    • The pressure-melting curve of ice is often found in literature dealing with ice problems. This curve originates from the excellent experimental works of G. Tammann* and P.V. Bridgman**. The method used means that ice at constant temperature is submitted to an external pressure. When increasing the pressure a sudden volume change occurs, the pressure-melting point is reached. Results from their works are summarized in this paper. An alternative experimental method was used in this study. Water is confined in a filled-up pressure tank. The water is then cooled from an initial temperature of 0°C. The ice formed creates a pressure increase in the ice-water mixture. At any temperature a corresponding pressure occurs at phase equilibrium. The temperature and the pressure are measured in the ice-water mixture. The results are in good agreement with earlier measurements. The method used, which is easy to handle even with this prototype equipment, should be more accurate than the old method since one possible source of error (the external pressure) is eliminated. The method could be used for other substances than pure water.
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6.
  • Nordell, Bo, et al. (författare)
  • Method for continuous measurement of ice cover thickness
  • 1995
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 23:4, s. 389-391
  • Tidskriftsartikel (refereegranskat)abstract
    • The objective of this study was to evaluate a method for continuous measurement of ice cover thickness. The measuring device consists of a water-filled bucket, floating with its brim at the water surface. A pipe is vertically mounted at the centre of the bucket and capped with an oil-filled balloon. The volume expansion of the formed ice results in a corresponding oil flow, from the balloon at the bottom of the bucket through the pipe into an expansion bucket above ground. By measuring the volume expansion continuously, the ice thickness can be determined at any time. The performance of preliminary laboratory tests confirmed the feasibility of the method.
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7.
  • Sahlberg, Jörgen (författare)
  • Modelling the thermal regime of a lake during the winter season
  • 1988
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 15:2, s. 151-159
  • Tidskriftsartikel (refereegranskat)abstract
    • The thermal regime of a lake is investigated using both measured and numerically simulated data. The temperature measurements clearly demonstrate the importance of knowing the amount of short wave radiation that penetrates the ice-cover and the sediment heat flux from the lake bottom. However, the sediment/water coupling will not be treated in this study. In the numerical simulations a one-dimensional model is used, where the vertical exchange coefficient is calculated by a two-equation turbulence model. The meteorological forcing, which enters the model through the surface boundary conditions, is calculated on the basis of synoptic meterological observations every third hour. These boundary conditions are strongly affected by ice formation at the surface. Therefore, parameterizations of the initial ice formation and break-up and the ice growth and melting are included in the model. The amount of short wave radiation that reaches the ice/water interface is modelled in the following three steps: first, there is the snow or ice surface albedo, second, an absorption occurs in the upper 0.1 m of the ice and/or snow-cover, and third, the remaining radiation decays exponentially down to the ice/water interface. The modelled initial ice formation and break-up together with the ice growth and melting are verified against measurements with satisfactory results. Also the calculated water temperature increase and its vertical structure are well described by the model.
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8.
  • Skogsberg, Kjell, et al. (författare)
  • The Sundsvall hospital snow storage
  • 2001
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 32:1, s. 63-70
  • Tidskriftsartikel (refereegranskat)abstract
    • During the summer, the regional hospital in Sundsvall in central Sweden requires 1000 MW h of cooling with a maximum cooling power 1500 kW. From the summer of 2000, seasonally stored snow will be utilised to meet the cooling demand. A storage area of 140×60 m with a capacity for 60,000 m3 (40,000 tons) of snow was constructed in 1999. Initially, about half of this volume will be stored. The storage consists of a shallow pit made of watertight asphalt. A layer of wood chips covering the snow reduces the natural melting to 20–30% of the total volume. Meltwater from the snow storage is pumped to the hospital. After cooling the hospital, the heated meltwater is re-circulated to the snow storage. When all the snow has melted, the wood chips will be burnt in a local heating plant. Luleå University of Technology is responsible for the scientific evaluation of the project. This paper describes the construction and the simulated operation of the snow storage system.
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9.
  • Skogsberg, Kjell (författare)
  • The Sundsvall Regional Hospital snow cooling plant : results from the first year of operation
  • 2002
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 34:2, s. 135-142
  • Tidskriftsartikel (refereegranskat)abstract
    • During the summer of 2000, the Sundsvall Regional Hospital (central Sweden) required 655 MW h of comfort cooling with a maximum cooling power of 1366 kW. Of the cooling demand, approximately 93% was attained by the use of 19,000 m3 of snow stored from the winter. The majority of the snow/ice was natural while the rest was artificially made with snowguns and a hose. The snow was stored in a 140×60-m shallow pond of watertight asphalt. A 0.2-m layer of wood chips thermally insulated the snow. The operation of the plant experienced only minor problems. Luleå University of Technology is responsible for the scientific evaluation of the project. This paper compiles the results and experiences of the snow cooling plant during the first year of operation in 2000.
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10.
  • Viklander, Peter (författare)
  • Laboratory study of stone heave in till exposed to freezing and thawing
  • 1998
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 27:2, s. 141-152
  • Tidskriftsartikel (refereegranskat)abstract
    • Cyclic freezing and thawing of soils affect the structure and might, under certain conditions, cause stones and particles to move and relocate. The movement of stones will influence the soil structure and create weak and loose parts with increased permeability. This phenomenon has been known for a long time, but the knowledge regarding the magnitude of stone heave and soil conditions necessary for heave to take place has been lacking. Therefore, laboratory tests were carried out. Fine-grained till (moraine) was compacted to different void ratios and then saturated in a rigid wall permeameter which was exposed to one-dimensional freezing and thawing in a closed water system. The movements of an embedded stone were measured by an X-ray technique. Unfrozen samples, as well as samples frozen and thawed, were X-rayed and the stone movements were quantified after 1, 2, 4, and 10 cycles of freezing and thawing. The results show that stone movements (vertical and horizontal) take place due to freeze/thaw. The void ratio (the ratio of the volume of void space to the volume of solid substance in the sample) was found to be a key parameter for whether upward or downward stone movements took place. The downward movement occurred when the soil had a high void ratio, and the upward when the void ratio was small. In the loose soil, the stone first moved downwards and then, when the soil became denser due to freeze/thaw, it changed direction and heaved. In the loose soil, significant movements in the horizontal direction as well as rotation of the stone were also found.
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11.
  • Viklander, Peter, et al. (författare)
  • Stone movements and permeability changes in till caused by freezing and thawing
  • 2000
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441. ; 31:2, s. 151-162
  • Tidskriftsartikel (refereegranskat)abstract
    • Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured. Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured. Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured.
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12.
  • Abrahamsson, Per, 1985, et al. (författare)
  • An infield study of road snow properties related to snow-car adhesion and snow smoke
  • 2018
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 145, s. 32-39
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2017 Elsevier B.V. This article analyzes the properties of snow on the road related to the formation of snow smoke and contamination of the car. The increased usage of sensors for active safety in modern cars increases the importance of understanding contamination of the car body. The analysis characterizes snow in terms of shape, size, and adhesiveness. The data is related to changing weather conditions and experienced car contamination. Several different sampling positions were chosen both on the road and on the car. The temperatures during the days of measurements ranged from − 4 °C to − 12 °C, which gave cold and dry snow. Data on size and shape was obtained via microscope analysis. An infield adhesion tester for snow adhesion measurements was built. The microscope analysis showed that the shape of the snow particles in the tire tracks and on the car body generally had a rounded structure. Even soon after a fresh snow fall, the rounded shapes remained in these positions. This structure was found to change to a more edgy hexagonal shape during hoar formation on the existing snow. The particle size distributions from tire tracks, from suspended snow smoke, and from different positions on the car were analyzed. It was found that smaller particles travel higher and are more prone to enter the wake behind the car to stick to the back parts of the vehicle. The adhesion test gave little distinction between the different snow types and samples. The adhesion force was found to range from 2 to 12 dyne.
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13.
  • Andrén, Anna, et al. (författare)
  • Evaluation of a laboratory model test using field measurements of frost penetration in railway tunnels
  • 2022
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 204
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite extensive grouting efforts to prevent water from leaking into tunnels, water seepages remain. When exposed to freezing temperatures, ice formations occur. During the winter, the Swedish Transport Administration's railway tunnels are affected by major problems caused by ice, such as icicles from roof and walls, ice loads on installations, ice-covered tracks and roads, etc. To ensure safety and prevent traffic disruptions, many tunnels require extensive maintenance. Improved knowledge about frost penetration in tunnels is required to reduce maintenance of the tunnels. Frost insulated drain mats are often used at leakage spots to prevent ice formation along the tunnels. To find out which parts of a tunnel are exposed to freezing temperatures, the University of Gävle and the Royal Institute of Technology in Stockholm conducted a laboratory model test on behalf of the Swedish National Rail Administration (now the Swedish Transport Administration). The laboratory model test aimed to find a method to determine the expected temperature conditions along a tunnel to decide which parts of the tunnel require frost insulation to protect the drainage system from freezing and prevent ice formation. To evaluate the laboratory model test, the Swedish Transport Administration in collaboration with Luleå University of Technology have performed field surveys in two Swedish railway tunnels. The field measurements involved monitoring temperatures in air, rock surfaces and rock mass, as well as measuring wind direction, wind and air velocity and air pressure. The measurements in the tunnels show that the frost penetrates further into the tunnels than was expected from the laboratory model test, which was based on a completely uninsulated tunnel. Frost insulated drains do not only prevent the cold air from reaching the rock mass, but also prevent the rock from emitting geothermal heat that warms up the cold tunnel air. Consequently, the frost penetrates further into the tunnel than it would do if the heat from the rock mass was allowed to warm up the outside air on its way into the tunnel. The number of frost insulated drains and how much of the tunnel walls and roof are covered thereby affect the length of the frost penetration.
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14.
  • Arvidsson, Anna K, 1971- (författare)
  • The Winter Model : A new way to calculate socio-economic costs depending on winter maintenance strategy
  • 2017
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 136, s. 30-36
  • Tidskriftsartikel (refereegranskat)abstract
    • The project “Winter Model” started at the beginning of the 2000s. The idea was to try and predict the consequences of different winter maintenance strategies and to calculate the associated socio-economic costs. It is now possible to calculate and validate the impact that different winter maintenance measures have on road users, road authorities and local communities.This paper contains results of the first complete Winter Model calculations using existing conditions. Comparisons with different road classification standards have been carried out in order to determine the effect they have on socio-economic costs. Road classification standards dictate how much snow should fall before a maintenance action is initiated and how long it should take until the action is completed. Socio-economic costs increased for all comparisons when reductions in the classification standard were applied. As an example of how costs can vary: the scenario is a salted road using a combined plough and salt spreader where the allowed time to complete the action is 4 h that is changed to an unsalted road with an allowed time to complete the action of 5 h. Both scenarios have an action start criteria of 2 cm deep snow, and an annual average daily traffic flow of 2000.Comparison results show that the change from salted to unsalted road saves the most cost due to a reduction in salt use and required actions. However, the increased time to complete the action will result in slightly longer travel times and accident costs will increase by 24.2%. The extended action hour affect fuel consumption in a positive way, for example, consumption decreases slightly due to driving more often at lower speeds on unclear roads. By lowering the road classification standard like in this example, total socio-economic costs increased by 3.5%.
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15.
  • Barabadi, Abbas, et al. (författare)
  • Designing for performability : An icing risk index for Arctic Offshore
  • 2016
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 124, s. 77-86
  • Tidskriftsartikel (refereegranskat)abstract
    • Ice accretion affects the performability of offshore production facilities in various ways, including repair time and failure rate. It can increase power losses, life cycle costs and safety hazards. There are few studies and limited systematically collected information about the impact of ice accretion on performability and its attributes (reliability, maintainability, quality, safety and sustainability) for Arctic offshore production facilities. This paper will discuss the effects of different types of ice accretion on the performability of Arctic offshore production facilities. Then, to quantify their effect on the performability of offshore production facilities, an icing risk index is developed; its application is then shown by means of a case study.
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16.
  • Bhardwaj, Anshuman, et al. (författare)
  • Mapping debris-covered glaciers and identifying factors affecting the accuracy
  • 2014
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 106-107, s. 161-174
  • Tidskriftsartikel (refereegranskat)abstract
    • Supraglacial debris significantly hampers the mapping of glaciers using remote sensing data. A semi-automated approach for the mapping of debris-covered glacier was applied, which combined the inputs from thermal and optical remote sensing data and the Digital Elevation Model (DEM) derived morphometric parameters. A thermal mask that delineates the supraglacial debris extent was generated by the thresholding of surface temperature layer obtained from Landsat TM/ETM. + thermal band satellite data. The extent of clean glacier ice was identified by band ratioing and thresholding of TM/ETM. + 4 and TM/ETM. + 5 bands. Morphometric parameters like slope, plan curvature and profile curvature were rearranged in similar surface groups using the technique of cluster analysis. All these masks were vectorized and final classification maps were generated using geographic information system (GIS) overlay operations. The areal extent of semi-automated outlines of Hamtah and Patsio Glaciers derived from cluster analysis varied from manually derived outline using pan-sharpened Landsat ETM. + September 2000 image by -. 1.3% and -. 1.6%, respectively. Year 2011 classification map for Patsio Glacier was compared with the field observations and a high correlation and overall accuracy (~. 91%) were observed. The same classification methodology was adopted for images of years 2000 and 1989 for Patsio Glacier to observe the effects of varying snow cover patterns on adopted methodology. Also the methodology was adopted and verified for Hamtah Glacier, with different geometry and terrain conditions as compared to Patsio Glacier. Although the spatial resolution limitation of ASTER GDEM and Landsat TM/ETM. + thermal band limits the automated mapping of small debris-covered glaciers, the outcomes are still favorable enough to apply such methodologies for mapping different types of debris-covered glaciers in the future
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17.
  • Bonath, Victoria, et al. (författare)
  • Morphology, internal structure and formation of ice ridges in the sea around Svalbard
  • 2018
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 155, s. 263-279
  • Tidskriftsartikel (refereegranskat)abstract
    • The results from 3 years of comprehensive field investigations on first-year ice ridges in the Arctic are presented in this paper. The scopes of these investigations were to fill existing knowledge gaps on ice ridges, gain understanding on ridge characteristics and study internal properties of ice. The ability of developing reliable simulations and load predictions for ridge-structure interactions is the final principal purpose, but beyond the scope of this paper. The presented data comprise ridge geometry, ice block dimensions from ridge sails, ice structure in the ridge and values on the ridge porosity and the degree of consolidation. The total ridge thickness conformed to other ridges studied in the same regions. The consolidated layer thickness was on average 2–3 times the level ice thickness. Minimum 33% and in average 90% of the ridge keel area was consolidated. The distribution of ice block sizes and block shapes within a ridge appears to be predictable. A new approach for deriving a possible ridging scenario and ridge age is presented. Different steps of the ridge building process were identified, which are in good agreement with earlier simulated ridging events. After formation of very thin lead ice between two floes deformation occurs through rafting and ridging until closure of the lead. Subsequently the adjacent level ice floe fractures proceeding ridge formation until ridging forces exceed driving forces. A time span of 10 days could be assessed for a possible ridge formation date, estimating the ridge age of the studied ridge located east of Edgeøya at 78° N to be 7 to 8 weeks.
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18.
  • Bonath, Victoria, et al. (författare)
  • Properties of ice from first-year ridges in the Barents Sea and Fram Strait
  • 2019
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 168
  • Tidskriftsartikel (refereegranskat)abstract
    • First-year ice ridges are one of the main load scenarios that off-shore structures and vessels operating in ice-covered waters have to be designed for. For simulating such load scenarios, the knowledge gap on ice mechanical properties from the consolidated part of first-year ridges has to be filled. In total 410 small-scale uniaxial compression tests were conducted at different strain rates and ice temperatures on ice from the consolidated layer of 6 different first-year ridges in the sea around Svalbard. For the first time uniaxial tensile tests were performed on ice from first-year ridges using a new testing method. Ice strength was evaluated for different ice type, which are determined for each specimen based on a proposed ice classification system for ice from first-year ridges. 78% of all samples contained mixed ice with various compounds of brecciated columnar and granular ice. Ice strength of mixed ice showed isotropy, except for the samples containing mainly columnar ice crystals. For horizontal loading, mixed ice was stronger than columnar and granular ice. The residual strength of ductile ice depended on the strain rate. At 1.5% strain remained 70% of peak strength at 10−4 s−1 and 50% at 10−3 s−1. Ductile failure dominated for 75% of all mixed ice tests at 10−3 s−1 and − 10 °C. Ductile compressive strength was generally higher than brittle compressive strength for mixed ice. Brine volume was the main parameter influencing the tensile strength of the mixed ice which was between 0.14 MPa and 0.78 MPa measured at constant ice temperature of −10 °C.
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19.
  • Dagli, Deniz, et al. (författare)
  • Image analyses of frost heave mechanisms based on freezing tests with free access to water
  • 2018
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 146, s. 187-198
  • Tidskriftsartikel (refereegranskat)abstract
    • A freezing test apparatus was supplemented with a camera to allow for recording and monitoring one-dimensional freezing tests to analyze the development of ice lenses via particle image velocimetry (PIV) in the laboratory. Two tests on disturbed, partially saturated samples of silt loam were conducted. Image recording and correlation analyses provided detailed information about frost front penetration and ice lens formation(s) under varying temperature boundary conditions. Thawing has also been regarded in further studies.Results of the image analyses were compared to readings from conventional displacement measurements during the same test. Significant agreement between the results of image analyses and displacement measurements has been found. Test results were also used to establish a qualitative relationship between heat extraction and heave rates. Advantages and disadvantages of utilizing image analysis methods were discussed. Potential remedies for overcoming the drawbacks of using image analysis are suggested.Image analysis is shown to be a viable method in further understanding of frost heave mechanisms.
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20.
  • Dammann, Dyre Oliver, 1985, et al. (författare)
  • Evaluating landfast sea ice stress and fracture in support of operations on sea ice using SAR interferometry
  • 2018
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 149, s. 51-64
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent Arctic warming has led to reduced sea-ice thickness and a more dynamic landfast ice cover with potential widespread consequences for ice users. Here, we develop an approach to assess the small-scale deformation of landfast ice critical to on-ice operations using synthetic aperture radar interferometry (InSAR). InSAR has previously proven successful in determining long-term qualitative climatology of ice deformation around on-ice operations, but is now used to explore its potential for providing quantitative guidance for ice road planning, construction, and maintenance. A validation effort using X-band SAR and high-precision GPS data over Elson Lagoon, Alaska, confirms the ability of InSAR to accurately estimate 3-dimensional sea ice strain values accumulated between SAR image acquisitions, using an inverse model. The inverse model was further applied to L-band InSAR data over the Northstar Island ice road near Prudhoe Bay, Alaska. Assuming an elasto-brittle rheology, the derived strain values yielded a spatial distribution of internal stress consistent with preexisting ice defects and morphology. In several localized regions of the study area, stress values exceeded expected yield stress. Resulting relative fracture intensity potential was shown to conform with local knowledge based on road inspections by engineers, and may be used to guide ice road planning, construction and maintenance efforts. The results presented here demonstrate that InSAR is an accurate tool for estimating landfast ice deformation and stability in support of ice use. The findings may also provide substantial new insights into the mechanics of landfast ice.
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21.
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22.
  • Eidevåg, Tobias, 1987, et al. (författare)
  • Angle of repose of snow: An experimental study on cohesive properties
  • 2022
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 194
  • Tidskriftsartikel (refereegranskat)abstract
    • The angle of repose is a measure reflecting the internal friction and cohesion properties of a granular material. In this paper, we present an experimental setup and measurements for the angle of repose of snow for seven different snow samples over a large range of temperatures. The results show that the angle of repose is dependent on the fall height, the temperature, and the grain size of the snow. These variables are quantified, and their interdependencies are separately studied. With increased snow temperature, the angle of repose increases, and this can be explained by the presence of a liquid layer on ice that can be thermodynamically stable at temperatures below the melting point of water. With decreasing grain size the angle of repose also increases which is expected since the cohesive energy decreases more slowly than the grain mass. For increasing fall height, the snow grains generally accelerate to larger collisional velocities, yielding a smaller angle of repose. In general, the dimensionless cohesion number was found to largely reflect the dependencies of the variables and is therefore useful for understanding what affects the angle of repose. The results demonstrate that the drag force and collision dynamics of ice grains are important for understanding how snow accumulates on a surface, for example if one desires predicting snow accretion by simulating a dispersed cloud of snow. © 2021
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23.
  • Hansson, Klas, et al. (författare)
  • Equifinality and sensitivity in freezing and thawing simulations of laboratory and in situ data
  • 2006
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 44:1, s. 20-37
  • Tidskriftsartikel (refereegranskat)abstract
    • Numerical models of soil freezing and thawing are being increasingly used in, e.g., agriculture, forestry, ecology and civil engineering. This study was conducted to 1) elucidate the sensitivity in simulation output to the variability of model parameters for the hydrodynamic model Hydrus-1D and 2) investigate how two operational considerations in the model setup, groundwater level and subgrade material (soil texture), affect indicators of road accessibility in northern Sweden. The analysis was carried out by applying the generalized likelihood uncertainty estimation (GLUE) procedure when simulating laboratory measurements of freezing cylinders and by a more conventional sensitivity analysis, varying one parameter at a time, using road surface temperatures measured during nearly 1 year as upper boundary condition. For the simulation of the laboratory experiment, it was found that, although the thermal conductivity scaling factor, λf, and the convective heat transfer coefficient, hc, most strongly affected the output, no parameter was redundant for the given problem. The frost depth was most sensitive to changes in λf and hc, while the water content in the unfrozen zone was most sensitive to changes in the hydraulic conductivity impedence parameter Ω. For the 1-year road simulation, the frost depth was larger for sand than for the loam and silt subgrades; the thawing period was shortest for sand and longest for the silt subgrade; and the silt subgrade allowed for the largest frost-induced upward water flow. Thus, among the subgrades studied, roads built on silt show the potential of being most frost-susceptible as a consequence of having the largest elevated water content in combination with the longest time of thawing. The study performed indicates that the model can provide information of interest from an operational perspective, allowing for local predictions important in the road construction and maintenance process.
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24.
  • Hellgren, Rikard, 1988-, et al. (författare)
  • Ice load measurements on Rätan concrete dam using different sensor types
  • 2021
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; , s. 103425-103425
  • Tidskriftsartikel (refereegranskat)abstract
    • Concrete dams in cold regions are designed to withstand loads from the ice sheet on top of the reservoir. However, the ice load's magnitude and return period are among the most considerable uncertainties in safety assessments of concrete dams. In a previous study, the development and installation of a 1 × 3 m2 prototype ice load panel attached at the upstream face of a concrete dam was presented. The panel is large enough for the ice sheet's cross-section to remain in contact with the panel as the water level varies, and it measures the total ice load without interpolation. This paper presents measurement results from the load panel from winters 2018–19 and 2019–20, an update to the measurement design, and additional ice pressure measurements with traditional stress cells. The panel measured seasonal maximum ice loads of 100 and 200 kN/m for the two winters, respectively. Winter 2019–20, when the panel measured the largest loads, was mild for the location, with great ice thickness near the dam face (1.2 m) and an almost snow-free ice sheet throughout the winter. Two 2.75 × 1.75 m2 dummy panels were installed adjacent to the load panel prior to the winter 2019–20 to minimize the load panel's protruding effect. These panels significantly reduced the local impact, as evident by the crack-pattern of the ice sheet near the load panel. The load panel recorded large ice loads (>75 kN/m) for all combinations with increasing/decreasing air temperature and/or water level. Identification of temperature change events and water level change events during the winters, shows that a change in air temperature, water level, or any combination of these, is not sufficient alone to explain large ice loads at Rätan dam. These findings suggest that other conditions must be satisfied before a water level or temperature change results in large ice loads. In February 2020, three panels consisting of a steel frame with four stress cells on each were placed on the dummy panels’ upstream face, and one single stress cell was placed 6 m out in the reservoir in front of the load panel. The majority of the stress cells recorded ice pressure larger than their measurement range. At the end of the ice season, only two of the panels’ twelve stress cells were still functional, and the ice vastly deformed the steel frames. From the period before the frames were damaged and unrelated to the choice of interpolation method, the recordings by the three stress cell panels at the dam are among the historically largest inferred ice loads on dams.
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25.
  • Hellgren, Rikard, 1988-, et al. (författare)
  • Measurement of ice pressure on a concrete dam with a prototype ice load panel
  • 2020
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 170
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents the development and installation of a prototype ice load panel and measurements of ice load from February 2016 to February 2018 at the Rätan hydropower dam in Sweden. The design of the 1 × 3 m2 panel enables direct measurement of ice pressure on the concrete surface is based on previous experience from similar measurements with sea ice. Important features of the design are sufficient height and width to reduce scale effects and to cover the ice thickness and variations in water level. The Rätan dam was chosen based on several criteria so that the ice load is considered to be reasonably idealized against the dam structure.For the three winters 2016, 2016/2017, 2017/2018, the maximum ice load recorded was 161 kN/m, 164 kN/m and 61 kN/m respectively. There were significant daily fluctuations during the cold winter months, and the daily peak ice loads showed a visual correlation with the daily average temperature and with the daily pattern of operation of the power station with its corresponding water level variations.
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26.
  • Hermansson, Ann-Charlotte, et al. (författare)
  • Mathematical model for paved surface summer and winter temperature : Comparison of calculated and measured temperatures
  • 2004
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 40:1-2
  • Tidskriftsartikel (refereegranskat)abstract
    • A simulation model has been developed to calculate pavement temperature for both summer and winter conditions. Input data are hourly values for solar radiation, air temperature and wind velocity. Longwave radiation, incident to and outgoing from the pavement surface, is calculated from the air and pavement surface temperature, respectively. The portion of the incident shortwave radiation absorbed by the pavement surface is calculated from the albedo of the surface. By means of a finite difference approximation of the equation for conduction of heat, the pavement temperature profile is calculated. Apart from radiation and heat conduction, convection losses from the pavement surface are also calculated based on wind velocity, air temperature and surface temperature. The model is validated by using data from three different sections in the LTPP program USA and six different sections in Sweden. Here, hourly meteorological data as well as surface temperature are taken. One set of parameter values for albedo, emissivity, atmospheric downwelling longwave radiation and convection losses, giving a good correspondence for asphalt concrete pavement for summer conditions, and one set for winter conditions are given. © 2004 Elsevier B.V. All rights reserved.
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27.
  • Hermansson, Åke (författare)
  • Laboratory and field testing on rate of frost heave versus heat extraction
  • 2004
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 38:2-3, s. 137-151
  • Tidskriftsartikel (refereegranskat)abstract
    • Equipment for performing laboratory freezing tests on soils has been developed to study the relation between the rates of heave and heat extraction. Laboratory freezing tests are performed on specimens over 500 min tall. In addition, field equipment for automatically recording frost depth and heave has been installed in a pavement. The equipment gives temperature readings for every 50 mm. Temperature gradients at different depths, from laboratory as well as field, are calculated to estimate the rate of liberation of latent heat as a function of time. The calculations indicate that, for the laboratory testing, the heave rate is almost independent of the heat extraction rate for fairly long periods at a constant frost penetration rate. The recorded field data indicate that the heave rate is on average almost constant for relatively long periods of time with a continuous frost penetration, thereby supporting the existence of a maximum heave rate that can not be surpassed persistently. However, heave rate varies greatly if the heat extraction rate often changes between a high and a low level and can for short periods widely exceed the maximum average heave rate possible over long periods. The observed behavior is explained as a consequence of a limited capacity in the redistribution of water to the frost front to supply the heaving.
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28.
  • Hollesen, J., et al. (författare)
  • Modelling temperature-dependent heat production over decades in High Arctic coal waste rock piles
  • 2011
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 65:2, s. 258-268
  • Tidskriftsartikel (refereegranskat)abstract
    • Subsurface heat production from oxidation of pyrite is an important process that may increase subsurface temperatures within coal waste rock piles and increase the release of acid mine drainage, AMD. Waste rock piles in the Arctic are especially vulnerable to changes in subsurface temperatures as the release of AMD normally is limited by permafrost. Here we show that temperatures within a 20 year old heat-producing waste rock pile in Svalbard (78 degrees N) can be modelled by the one-dimensional heat and water flow model (CoupModel) with a new temperature-dependent heat-production module that includes both biological and chemical oxidation processes and heat source depletion over time. Inputs to the model are meteorological measurements, physical properties of the waste rock material and measured subsurface heat-production rates. Measured mean annual subsurface temperatures within the waste rock pile are up to 10 C higher than the mean annual air temperature of -5.8 degrees C. Subsurface temperatures are currently decreasing with 0.5 degrees C per year due to decreasing heat production, which can be modelled using an exponential decay function corresponding to a half-life period of pyrite oxidation of 7 years. Simulations further suggest that subsurface temperatures two years after construction of the pile may have been up to 34.0 degrees C higher than in 2009 and that the release of AMD may have been more than 20 times higher. Sensitivity simulations show that maximum temperatures in the pile would have been up to 30.5-32.5 degrees C lower and that the pile would have been frozen 12-27 years earlier if the pile had been initially saturated with water, constructed with a thickness half of the original or a combination of both. Simulation show that the pile thickness and waste rock pyrite content are important factors controlling the internal build up of heat leading to potential self-incineration. However, site specific measurements of temperature-dependent heat production as well as simulation results show that the heat produced from pyrite oxidation alone cannot cause such a temperature increase and that processes such as heat production from coal oxidation may be equally important. (C) 2010 Elsevier B.V. All rights reserved.
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29.
  • Irannezhad, Masoud, 1983, et al. (författare)
  • Long-term variability and trends in annual snowfall/total precipitation ratio in Finland and the role of atmospheric circulation patterns
  • 2017
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 143, s. 23-31
  • Tidskriftsartikel (refereegranskat)abstract
    • This study evaluated variabilities and trends in annual snowfall to total precipitation (S/P) ratio at Sodankyla, Kajaani and Kaisaniemi weather stations in northern, central and southern Finland during 1909-2008. Annual S/ P ratio was estimated using daily precipitation and temperature records as input to a calibrated and validated temperature-index snowmelt model developed to simulate snowpack accumulation and melt processes in Finland. Factors controlling variations in annual S/P ratio and their relationships with large-scale atmospheric circulation patterns (ACPs) were also studied. The results show that there were significant declines in annual S/P ratio during 1909-2008, which were principally attributable to century-long decreasing trends in annual snowfall (S) in Finland. These reductions in annual S were predominantly controlled by both annual rainfall (R) and snowfall-day temperature (ST) in the south, annual ST in the centre, and annual R in the north. However, dividing the 100-year study period into an early (1909-1958) and late (1959-2008) periods revealed non-linear trend behaviours in annual S and consequently annual S/P ratio during 1909-2008. The Arctic Oscillation, East Atlantic, East Atlantic/West Russia and Scandinavia patterns were the most influential ACPs for annual S variability.
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30.
  • Johnsson, Josef, 1986, et al. (författare)
  • Modeling the thermal performance of low temperature hydronic heated pavements
  • 2019
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 161, s. 81-90
  • Tidskriftsartikel (refereegranskat)abstract
    • Winter road maintenance is costly but it is necessary in order to keep roads accessible and safe during winter. Current winter road maintenance methods use 600,000 tons of salt annually, in the Nordic countries. The salt ends up in the environment along the roads and results in environmental challenges. Alternative winter maintenance methods that use heat instead of salt are in use today. However, those systems are designed to use high temperature of about 20–35 °C. This paper presents a numerical model for designing low temperature (4–8 °C) hydronic heated pavements (HHP). The model is validated against an experimental setup and different control strategies are evaluated. The validation indicated that the developed model can predict the behavior of the HHP with a root mean square error (RMSE) <1.4 °C for surface temperatures and <0.4 °C for the return fluid. In this paper the model is used with two different control strategies. A basic strategy controlling the system based on air temperature and one strategy based on dew point temperature. With dew point regulation the energy consumption can be reduced by 62%. However, the energy consumption is still in the range of 125–180kWh/m 2 for the location of Östersund, Sweden. We found that the HHP system can utilize low temperature sources like waste energy or geothermal energy that is freely available. By using renewable energy for winter road maintenance, the environmental impact from winter road maintenance can be reduced.
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31.
  • Khoshkhoo, Y., et al. (författare)
  • Calibration of an energy balance model to simulate wintertime soil temperature, soil frost depth, and snow depth for a 14year period in a highland area of Iran
  • 2015
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 119, s. 47-60
  • Tidskriftsartikel (refereegranskat)abstract
    • A physically-based heat and mass transfer model, CoupModel, is calibrated to simulate wintertime soil temperature, soil frost depth, and snow depth for a 14-year period in a highland area of Iran. A Monte Carlo based approach is used for calibration process based on subjective performance criteria. Sensitivity and uncertainty analyses of the model were performed by selecting 30 parameters and the model was run using 22,000 samples taken from the uncertainty range of the parameters. By using the Nash-Sutcliffe Index to evaluate the performance of the model and applying a cutoff threshold for the performance to snow depth and soil temperature, 161 behavioral simulations were recognized and considered as the accepted ensemble to represent the field conditions. Sensitivity analysis of the model revealed some parameters associated with soil evaporation, soil hydraulic properties, and snow modeling as sensitive and highly important parameters. Uncertainty analysis of the model for wintertime soil temperatures showed a reasonable agreement between simulations and observations in most cases. However, a systematic error occurred at some periods because of high uncertainty of the actual snow density and details of snow melting. Uncertainties were also due to the simplified model assumptions regarding snow thermal properties and temperature within snow cover. The snow depth at the accumulation and melting stages were described well by the model in most cases.
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32.
  • Knutsson, Roger, 1987-, et al. (författare)
  • How to avoid permafrost while depositing tailings in cold climate
  • 2018
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 153, s. 86-96
  • Tidskriftsartikel (refereegranskat)abstract
    • Managing tailings deposition in cold climate requires specific measures not to create permafrost. The risk of generating permafrost due to tailings deposition exists even in regions where permafrost would naturally not occur. Material being frozen during winter might not fully thaw in the following summer due to added height of the tailings on the surface. Such embedded layers of permafrost should be avoided especially close to tailing dams. Main reasons are to prevent impermeable layers in tailings facilities, and to reduce the risk of having implications if such layers thaw during warmer summers causing increase in pore water pressure, reduced effective stress, and increased water content.This paper presents a numerical study on the effects of tailings deposition in cold regions in relation to the potential formation of permafrost. Various deposition rates, schedules and tailings properties were evaluated. One-dimensional heat conduction analyses were performed with a temperature scenario representing a mine district in northern Sweden. Results show, that the thickness of permafrost layers increase with increased deposition rate and with increased water content. It was also shown that wet and loose tailings must be deposited in short periods during summer to avoid permafrost generation. In the case of dry and dense tailings more time is available for deposition in order not to cause aggradation of permafrost in the deposit.These findings can help mining operation to set up deposition schedules for tailings facilities in cold climate. For known tailings properties, results can be used to identify periods of the year when, and how much, tailings can be deposited in critical areas of a deposit in order to avoid permafrost formation.
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33.
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34.
  • Lintzén, Nina, et al. (författare)
  • Snow storage : modelling, theory and some new research
  • 2018
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 153, s. 45-54
  • Tidskriftsartikel (refereegranskat)abstract
    • The arrival of natural snow is often delayed nowadays due to global warming. This causes problems for ski resorts and other places where winter activities in different forms take place. Storing snow provides one solution for the winter business industry to deal with this problem. However, there is so far very little research concerning this question. In this paper a review of current knowledge of snow storage and experiences from mainly Scandinavian snow storages is presented. New results concerning melting losses of stored snow from a trial experiment in the north of Sweden are presented. These results are compared to theoretical calculations. The model used for the calculations is shown to be useful for estimating melting losses of insulated piles of snow. Thus the calculations can serve as an important background when designing an insulated snow depot. The model can also be used to compare different insulating materials and to determine properties such as thickness of the insulating layer needed to sufficiently insulate the snow. By minimizing the surface area of insulated snow depots, melt rate due to heat from the air, sun and sky, which constitute the largest part of the total melt, can be reduced. The quality of insulating materials used will be subject to annual observation. Commonly used insulating materials such as bark, wood chips, cutter shavings and sawdust deteriorate.
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35.
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36.
  • Mainali, Ganesh, et al. (författare)
  • Experimental study on debonding of shotcrete with acoustic emission during freezing and thawing cycle
  • 2015
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 111, s. 1-12
  • Tidskriftsartikel (refereegranskat)abstract
    • Studying the deterioration of shotcrete due to freezing and thawing is important for improvement of the understanding of the failure mechanisms/debonding of shotcrete in cold regions. Water leakage in a tunnel leads to ice growth during freezing temperature and ultimately creates favorable environment for fallouts of shotcrete and rock. Repeated freezing and thawing of shotcrete lead to development of new micro cracks and propagation of pre-existing micro cracks. In this study, test panels of granite with dimension 800 x 800 x 80 mm covered with 50-mm thick shotcrete were subjected to freezing and thawing action in a controlled environment. The initiation and the development of freeze-induced micro cracks in shotcrete-rock interface were studied by continuously monitoring acoustic emissions (AE) and temperature. The clustering of the AE events during freezing and thawing indicates that micro cracks appeared in the shotcrete-rock interface and caused adhesion failure. The larger number of AE events in the panels, with access to water during freezing, confirmed that water contributes to material deterioration and also reduces the adhesive strength. The test results showed that most of the acoustic emission occurred during the freezing cycle and the number of acoustic emission events did not increase with the successive increase of the number of freezing and thawing cycles.
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37.
  • Mirzanamadi, Raheb, 1987, et al. (författare)
  • Anti-icing of road surfaces using Hydronic Heating Pavement with low temperature
  • 2018
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 145, s. 106-118
  • Tidskriftsartikel (refereegranskat)abstract
    • A traditional method to mitigate slippery conditions on a road surface is to spread out sand and salt. This method results in corrosion of the road infrastructures and damage to surrounding vegetation. A renewable alternative method for anti-icing the road surface is to use a Hydronic Heating Pavement (HHP). The HHP consists of embedded pipes in the road. A fluid as thermal energy carrier circulates through the pipe. The energy is harvested in summer and saved in seasonal thermal energy storages. The harvested energy, as the only source of energy, is released in winter for snow/ice melting. The aim of this study is to investigate the anti-icing performance of the HHP system during cold periods. A two-dimensional numerical model was developed to investigate how different design options, such as distance between the pipes, affect the efficiency of the HHP systems. The annual required energy for anti-icing and remaining hours of the slippery conditions on the road surface were numerically calculated using a finite element model. The numerical model was validated for two cases: (i) for a road without pipes using a one year measured data of an existing road and (ii) for a road with embedded pipes using an analytical solution. The validation results for a road without pipes showed that the mean annual temperature difference of the road surface is 0.28 °C with standard deviation of 3.53 °C between the measured data and numerical calculation. The validation results for the road with embedded pipes showed that the maximum relative error associated with the thermal resistance between the pipes and surface is less than 1% between the numerical model and the analytical solution. In order to investigate the anti-icing performance of the HHP system, the climate data from Östersund, an area in middle of Sweden, were selected. The results revealed that the anti-icing performance of the HHP system improves when the pipes are placed closer, the depth of embedded pipes is reduced, large pipe sizes are used and when the road surface has a lower emissivity value. Among all options, the distance between pipes has the most significant effect on improving the anti-icing performance, so changing the pipe distances from 400 mm to 50 mm results in approximately four times shorter hours of the slippery conditions on the road surface.
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38.
  • Mähönen, Joonas, et al. (författare)
  • Bevameter pressure-sinkage testing on snow
  • 2024
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 222
  • Tidskriftsartikel (refereegranskat)abstract
    • Pressure-sinkage tests for determining vehicle sinkage on soft soils can be done using a bevameter. In this study, pressure-sinkage tests were performed on snow, which, like soil, is a granular material. However, unlike soil, snow layers are inhomogeneous with varying properties. For tracked vehicles, the shape of the track print is rectangular, which is why rectangular plates are often used for pressure-sinkage tests. The aim of this study was to see if smaller circular plate or smaller rectangular plates can be used instead of larger rectangular plates, and to understand the possible limitations of using small plates. Radius for the circular plate was chosen to be equal to the width of the rectangular plate. Three measuring sessions were performed at different locations during different snow conditions using circular pressure plates and rectangular pressure plates of different aspect ratios. The results show that smaller rectangular plates can be used if the width of the plates remains the same, or circular plates can be used if the radius of the circular plate is equal to the width of the rectangular plate. Limitation comes with increasing pressure, which occurs more quickly with larger-area plates, as larger plates sense solid ground more rapidly than smaller plates. To avoid this, snowpack thickness should be a minimum of five times thicker than maximum sinkage.
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39.
  • Mähönen, Joonas, et al. (författare)
  • Portable bevameter for measuring snow properties in field
  • 2021
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 182
  • Tidskriftsartikel (refereegranskat)abstract
    • Mechanical properties of snow related to snowmobiles or similar lightweight tracked vehicles aren't widely researched today and it is difficult to find data. One challenge is that snow properties constantly are changing due to aging, climate conditions and location. Also the measuring procedure is difficult since aged snow often contains layers with various densities and hardness. Soil is to some extent similar to snow, in the context that both are granular materials. The bevameter is a popular device for measuring soil properties, however this device needs to be scaled in order to meet criteria of target for research, i.e. in this case snowmobiles. In this paper a new type of portable bevameter is presented, which is designed and built for measuring snow properties in the field. Results from initial tests are also presented. The aim with the bevameter is to measure snow properties which can be used to simulate the interaction between a snowmobile and soft snow. The designed bevameter can be towed with one snowmobile to the field to execute measurements. One full set of test results is introduced and parameters for simulations are extracted from the result data. The parameters from the data were usable but the quality of the measurements can be improved. One problem with the data collected was noise, which was caused by the interaction between the mechanical parts and the low mass of the bevameter. Furthermore, the usability can be improved by reducing cables which can be hard and fragile during cold weather and by replacing the laser distance-sensor with a string wire potentiometer which isn't sensitive to snow dropping in the measurement area. With some improvements the constructed bevameter is a very useful tool which can be used for field measurements to determine snow properties for snowmobile-size vehicle simulations.
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40.
  • Niemelä, Henna, et al. (författare)
  • Effects of multiple wetting incidents, shear and sliding friction on lubricant stability in SLIPS
  • 2023
  • Ingår i: Cold Regions Science and Technology. - : Elsevier B.V.. - 0165-232X .- 1872-7441. ; 211
  • Tidskriftsartikel (refereegranskat)abstract
    • Surface icing almost invariably derives from the precursory step of liquid water encountering the surface. Thus, slippery liquid infused porous surfaces, SLIPS, must possess steady wetting durability, and lubricant stability to function as a reliable hydro−/icephobic surface design especially in outdoor applications. Additionally, they should maintain their phobic performance under shear forces, and possess low sliding friction to act as a slippery, multirepellent surfaces. These characteristics are needed in variable applications ranging from moving and rotating blades to steady surfaces, operating in altering climate conditions. More profound durability testing is needed to examine the loss of surface functionality when the lubricant is depleted from the structure via various routes. In addition, the durability tests should be designed to serve the application-related purposes and thus, to reveal performance differences between slippery surfaces for further analysis and targeted end-use development. Here, we tested the wetting durability and stability of SLIPS with multicycle Wilhelmy plate by dipping the surfaces multiple times in water bath. Additionally, we examined the effects of centrifugal and friction-based shear stress to investigate the lubricant depletion from the structure. Tests that measure the durability and the stability of SLIPS designs are in great need in further developing functional slippery surfaces for real outdoor application coatings which encounter environmental stresses, e.g., wetting and icing. Acknowledging the material differences under specific stresses will guide designing the slippery surfaces towards more specific and functionable end-use applications
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41.
  • Nohr, Christian, 1966, et al. (författare)
  • A dynamic sea ice model based on the formation direction of leads
  • 2009
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 58:02-jan, s. 36-46
  • Tidskriftsartikel (refereegranskat)abstract
    • A dynamic ice model is presented using a novel approach where the memory of weak directions in the ice cover is stored. The model computes ice motion, ice deformation and the associated dynamic ice production without the need of a full two dimensional computation. The ice dynamics is based on a viscous-plastic approach in a marginal ice zone with both compressive and shear stresses. The method is very computational efficient but is likely restricted to basin scales of semi size with relatively coherent wind forcing over the basin. The model is applied to the Bothnian Bay of the Baltic Sea and coupled with an ocean model. The results show good agreement when compared against measurements of ice velocity from an upward looking ADCP deployed in the center of the Bothnian Bay and observations from ice charts. As a model application, the dynamic ice production that occurs in addition to the pure thermodynamic growth in a deforming ice cover has been computed over the period 1991-2004. The results show that the dynamic ice production typically increases the ice volume with 80% over the simulation period. 
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42.
  • Petrich, Christian, et al. (författare)
  • Time-dependent spatial distribution of thermal stresses in the ice cover of a small reservoir
  • 2015
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 120, s. 35-44
  • Tidskriftsartikel (refereegranskat)abstract
    • Static ice loads (ice actions) are a key design parameter for dams in cold climates. However, their theoretical description is still elusive, introducing uncertainty in design and hindering development of remediation measures. We present and analyze measurements of stresses due to thermal loads in a small reservoir in northern Norway. Several weeks of observations, including both cold and warm spells, were well-described by a simple equation that accounts for thermal expansion and temperature-dependent creep. One model parameter was found to depend systematically on the location of measurements within the reservoir. Biaxial stress measurements showed that the stress field was not homogeneous. Results suggest that the stress field in reservoirs should be predictable from first principles with numerical methods and point toward a promising, simple parameterization.
  •  
43.
  • Rasul, Hedi, 1980-, et al. (författare)
  • Two-dimensional model for heat and moisture dynamics in Nordic roads: Model set-up and sensitivity analysis
  • Ingår i: Cold Regions Science and Technology. - 0165-232X .- 1872-7441.
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Modeling moisture and heat changes in road layers is important for understanding road hydrology, but also for better construction and maintenance of roads. The modeling task is more complicated in cold regions, due to the water-ice phase change in wintertime. This paper presents a two-dimensional model based on a road section. The water and heat transport equations, including freezing/thawing and vapor flow, were implemented within the COMSOL Multiphysics tool. Parameters were optimized from modeling results based on measured soil moisture and temperature at a road test station near Stockholm. Impacts of phase change in the model were assessed. The results showed that model developed can accurately predict temperature changes, water and ice content in different road layers based on pressure head and temperature gradient. The model of water dynamics performs much better than predicting the average water content in the upper road layer. Parameters related to soil water retention curve are optimized and most parameters influence water and heat change in the same direction, except the thermal conductivity of soil. The optimized parameters based on moisture content and temperature data from the sensors in the road section can be used in this model for testing different road materials and geometries. The model provides a clear understanding of water and heat transfer in roads with ideal boundary and initial conditions. For a better understanding of road heat and moisture dynamics, more physical processes can be added to the model in future work by coupling snow melt and surface flow models.
  •  
44.
  • Riehm, Mats, et al. (författare)
  • Ice formation detection on road surfaces using infrared thermometry
  • 2012
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 83-84, s. 71-76
  • Tidskriftsartikel (refereegranskat)abstract
    • Ice formation on roads causes hazardous conditions due to reduction of road surface friction. Forecasting, detecting and preventing ice formation are therefore of high importance for winter road maintenance personnel. Advanced sensors for detecting road ice exist, but there is a demand for more cost-effective technologies. A method for detection of road surface ice formation based on remote temperature measurements with infrared thermometers is presented. Freezing events were detected based on the temperature dynamics that result from the exothermic reaction as water freezes. Experimental measurements in a climate chamber and in field conditions showed that ice formation often causes a distinct temperature pattern, which could easily be identified and distinguished from other temperature fluctuations. The method is promising as a cost-effective technique suitable for several applications in cold regions where detection of ice formation is important. (C) 2012 Elsevier B.V. All rights reserved.
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45.
  • Riska, K., et al. (författare)
  • Brash ice growth model : development and validation
  • 2019
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 157, s. 30-41
  • Tidskriftsartikel (refereegranskat)abstract
    • Brash ice growth in frequently navigated areas like fairways or ports is quick due to the ‘freezing – breaking’ cycle induced by sub-zero temperatures and ship traffic. This problem is very acute in ports in Arctic areas where the temperatures are very low for long durations and the ship traffic is frequent. In order to take adequate action in managing the brash ice, the forecasts of the amount of brash ice expected should be reliable. The aim of this work is to develop and validate these prediction methods.The growth model developed is based on extension of earlier growth models which modify the Stefan type growth modelling. The improvement on the earlier models is that the brash ice layer is divided into three layers (instead of two in earlier models): The consolidated layer just below the water level, the brash ice over the water level and the unfrozen brash ice below the consolidated layer. The thermodynamic model follows the Stefan formulation including only the heat flux from latent heat release upon freezing (Stefan, 1891 and e.g. Anderson, 1961). The modelling includes the cyclic breaking and refreezing.The validation of the model is made using measurements carried out in winter 2013 in Luleå port and in winter 2015 in Sabetta in the Yamal peninsula. Luleå data suggests that the sideways motion of brash ice due to ship motion and wake should be taken into account when assessing the brash ice thickness. The analytical calculation over-estimates the brash ice thickness in the actual channel but under-estimates the total amount of broken ice. When applied to Sabetta data, the analytical calculation predicts well the observed brash ice thickness. It can be concluded that the analytical method that does not take into account any radiation heat fluxes can be applied in the high Arctic where solar radiation plays a minor role and ice surface is clearly below zero.
  •  
46.
  • Shi, Chu, 1980, et al. (författare)
  • Validation of a temperature-gradient-dependent elastic-plastic material model of ice with finite element simulations
  • 2017
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 133:1, s. 15-25
  • Tidskriftsartikel (refereegranskat)abstract
    • A temperature-gradient-dependent elastic-plastic material model of ice is proposed for the numerical study of the influence of temperature-gradient on impact force in ship-iceberg collisions. The model is based on the ‘Tsai-Wu’-type yield surface, and an empirical failure criterion is adopted. A series of yield surfaces with different sizes but the same shape are obtained from the linear interpolation of test results to represent the continuous temperature range in an iceberg. Temperature dependence is defined as the change in ice properties due to the temperature gradient as a function of depth of the iceberg. Based on field test data, three types of iceberg temperature profiles are assumed. The ice model is implemented as a user-defined subroutine in the commercial explicit finite element code LS-DYNA. Collisions between a rigid plate and different geometric iceberg shapes are simulated to analyse the influence of iceberg geometry and ice model temperature. The calculated contact area-pressure curves are compared with design laws to further calibrate the proposed ice model. Both a sharp temperature profile and low temperature range can increase the local contact pressure and global contact force as the penetration increases. The simulation results show that the ice model can capture and be used to demonstrate the influence of temperature-gradient on contact force in ship-iceberg collisions.
  •  
47.
  • Skogsberg, Kjell, et al. (författare)
  • Wood chips as thermal insulation of snow
  • 2005
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 43:3, s. 207-218
  • Tidskriftsartikel (refereegranskat)abstract
    • Snow (and ice) cooling is in some areas an alternative cooling technique to chillers. However, to utilise snow cooling during the summer, storage is needed. Snow storages were traditionally insulated by sawdust. A large demonstration plant has been in operation since 2000 for cooling the regional hospital in Sundsvall, Sweden. This storage is thermally insulated by larger wood chips. This paper summarizes laboratory testing of some key factors that influence the functioning of cutter shavings (another kind of wood chips) as thermal insulation. The melt rate significantly increased with increased wind velocity, light intensity (from spotlight bulbs), air temperature, and air humidity. A 1 cm thicker layer of cutter shavings decreased the melt rate about 0.097 kg m- 2 h- 1, within the studied layer limits of 2.5 to 7.5 cm. The melt rate with initially wet cutter shavings was about the same as for initially dry cutter shavings. This was explained by the increased evaporation which balanced increased thermal conductivity. Evaporation was found to be an important part of the energy balance and reduced the melt rate. Solar light reflectivity of new cutter shavings was measured in a separate outdoor experiment, found to be about 20%.
  •  
48.
  • Sundström, Nils, et al. (författare)
  • Modeling and simulation of GPR wave propagation through wet snowpacks : testing the sensitivity of a method for snow water equivalent estimation
  • 2012
  • Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 74-75, s. 11-20
  • Tidskriftsartikel (refereegranskat)abstract
    • Snow water equivalent (SWE) of a snowpack is an important input to the distributed snow hydrological models used for runoff predictions in areas with annual snowpacks. Since the conventional method of manually measuring SWE is very time-consuming, more automated methods are being adopted, such as using ground penetrating radar operated from a snowmobile with SWE estimated from radar wave two-way travel time. However, this method suffers from significant errors when liquid water is present in the snow.In our previous work, a new method for estimating SWE of wet snowpacks from radar wave travel times and amplitudes was proposed, with both these parameters obtained from a common mid-point survey. Here we present a custom ray-based model of radar wave propagation through wet snowpacks and results of MATLAB simulations conducted to investigate the method's sensitivity to measurement errors and snowpack properties. In particular, for a single-layer snowpack up to 2.1 m deep and with liquid water content up to 4.5% (by volume), the simulations indicate that SWE can be estimated with an error of ± 5% or less if (a) the noise (measurement errors) in the resulting amplitude has a standard deviation less than 15% and(b) the noise in two-way travel time has a standard deviation less than 0.075 ns (22.5% and 0.15 ns for a snowpack less than 1.3 m deep).
  •  
49.
  • Thorsson, Petra, 1987-, et al. (författare)
  • Modelling atmospheric icing : A comparison between icing calculated with measured meteorological data and NWP data
  • 2015
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 119, s. 124-131
  • Tidskriftsartikel (refereegranskat)abstract
    • In this case study several periods of measured active icing events have been compared with calculated activeicing. Icing events from three winter seasons in Sweden have been selected as a base for studying how well acommonly used method to calculate icing can capture icing events, aswell as to try out a newapproach. Anotherpurpose is to enlighten parties interested in atmospheric icing of the challenges of calculating icing. For thosewith little knowledge of Numerical Weather Prediction (NWP) models it can be hard to understand why thereare differences between two models, or even the same model using different physical parameterisation schemes.In this study data fromtwoNWP models have been used to calculate icing, aswell as being compared with a newapproach using meteorological measurements to calculate icing. Using meteorological measurements to calculateicing is an interesting alternative as it is computationally less expensive than using aNWP model to generatethe necessary data.All tested methods could at times capture the dynamics of the measured icing, though there are on occasion largedifferences between the different calculated icing and also between calculations and measurements. This highlightsthe importance of having an understanding of NWP models when studying atmospheric icing; there canbe a large spread between different models, and also when using the same model with different schemes. Theresults show that calculated icing is comparable to measured icing and that the methodologies investigatedare viable options for calculating atmospheric icing.
  •  
50.
  • Tommik, Karina, et al. (författare)
  • Air velocity and temperature distribution in culverts
  • 2023
  • Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 212
  • Tidskriftsartikel (refereegranskat)abstract
    • Uneven frost heave in roads and railways is a frequent problem in cold regions leading to degradation of structures. To improve drainage, culverts are frequently integrated into road and railway embankments. The presence of culverts changes the temperature distribution in the surrounding soil as cold air passes through the culvert. Consequently, frost depth and corresponding frost heave are increased in the vicinity of the culvert compared to the rest of the structure if frost susceptible soil is present. For an accurate frost related design, information of heat balance between the culvert and the surrounding soil is needed. A field study focusing on convective heat transfer in culverts was conducted in northern Sweden by the authors. Temperatures and air velocities in culverts of three sizes (0.6, 0.8 and 3.4 m) were recorded. Analysis of obtained data is presented in this paper with emphasis on the influence of air velocity on the temperature distribution. Influence of wind on development of airflow in culverts is also addressed. Accuracy of trained gaussian process regression (GPR) models is estimated in predicting temperature distribution inside of culverts. It is concluded, based on the field measurement data, that airflow can significantly affect temperature distribution inside culverts and development of airflow in culverts is largely influenced by the orientation of the culvert in relation to the predominant wind direction.
  •  
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