| 1. |
- Abrahamsson, Per, 1985, et al.
(författare)
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An infield study of road snow properties related to snow-car adhesion and snow smoke
- 2018
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 145, s. 32-39
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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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| 2. |
- Arvidsson, Anna K, 1971-
(författare)
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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
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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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| 3. |
- Barabadi, Abbas, et al.
(författare)
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Designing for performability : An icing risk index for Arctic Offshore
- 2016
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 124, s. 77-86
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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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| 4. |
- 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
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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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| 5. |
- Bonath, Victoria, et al.
(författare)
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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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| 6. |
- Dagli, Deniz, et al.
(författare)
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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
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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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| 7. |
- Dammann, Dyre Oliver, 1985, et al.
(författare)
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Evaluating landfast sea ice stress and fracture in support of operations on sea ice using SAR interferometry
- 2018
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 149, s. 51-64
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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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| 8. |
- Irannezhad, Masoud, 1983, et al.
(författare)
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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
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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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| 9. |
- Johnsson, Josef, 1986, et al.
(författare)
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Modeling the thermal performance of low temperature hydronic heated pavements
- 2019
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 161, s. 81-90
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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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| 10. |
- 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
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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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| 11. |
- Knutsson, Roger, 1987-, et al.
(författare)
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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
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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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| 12. |
- Lintzén, Nina, et al.
(författare)
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Snow storage : modelling, theory and some new research
- 2018
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Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 153, s. 45-54
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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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| 13. |
- Mainali, Ganesh, et al.
(författare)
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Experimental study on debonding of shotcrete with acoustic emission during freezing and thawing cycle
- 2015
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 111, s. 1-12
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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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| 14. |
- Mirzanamadi, Raheb, 1987, et al.
(författare)
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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
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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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| 15. |
- Petrich, Christian, et al.
(författare)
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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
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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.
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| 16. |
- Riska, K., et al.
(författare)
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Brash ice growth model : development and validation
- 2019
-
Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 157, s. 30-41
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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.
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| 17. |
- Shi, Chu, 1980, et al.
(författare)
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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
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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.
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| 18. |
- Thorsson, Petra, 1987-, et al.
(författare)
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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
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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.
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| 19. |
- Vignisdottir, H., et al.
(författare)
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A review of environmental impacts of winter road maintenance
- 2019
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 158, s. 143-153
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Forskningsöversikt (refereegranskat)abstract
- The need for winter road maintenance (WRM) is changing in cold regions due to climate change. How the different modes of WRM will contribute to future overall emissions from infrastructure is therefore of great interest to road owners with a view to a more sustainable, low-carbon future. In the quest for near-zero-emissions transport, all aspects of the transport sector need to be accounted for in the search for possible mitigation of emissions. This study used 35 peer-reviewed articles published between 2000 and 2018 to map available information on the environmental impacts and effect of WRM and reveal any research gaps. The articles were categorized according to their research theme and focus. They were found to focus mainly on the local effects of WRM with emphasis on effects on water. Of the reviewed works, 27 contain information related to the environmental effects of deicers on a local level while five focused on global impact, which was mainly caused by fuel consumption. Only two articles took a holistic look at the system to identify emission sources and the effectiveness of possible changes in operations methods or material selection. In conclusion, WRM would benefit from further research to understand how it affects the natural environment in regions with a cold climate. Furthermore, a life-cycle approach could reveal ways to mitigate emissions through effectively comparing possible changes in the system without shifting the problem to other aspects of road transport.
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| 20. |
- Wadi, Amer, et al.
(författare)
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Flexible culverts in sloping terrain : Numerical simulation of avalanche load effects
- 2016
-
Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 124, s. 95-109
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Tidskriftsartikel (refereegranskat)abstract
- Avalanche protection concrete structures are expensive and their construction period is often influenced by the climatological conditions at site, which could result in prolonging the erection process and increase its associated costs. Given the short construction time of flexible culverts, such structures can be a cost-effective alternative to traditional protective measures. This article investigates the performance of flexible culverts - often referred to as soil-steel composite bridges (SSCB) - when constructed in sloping topography under avalanche loads. A number of 2D finite element models were created to simulate two case studies composed of a pipe arch and a high-profile arch. The models were generated to investigate the effect of soil cover depth, the avalanche proximity, and the change in soil support conditions around the conduit. The aim was to perceive and understand the changes in deformations and sectional forces under defined avalanche loads. The results enable to realise the effect of shallow soil covers in the pronounced change in bending moments due to avalanches. The proximity of avalanche deviation point has a great influence on the structural performance, though increasing the soil cover depth could considerably help in reducing the bending moments resulting from avalanches. It is also found that the downhill soil support configuration has a substantial effect on the flexural response of the structure.
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| 21. |
- Wang, Jiabin, et al.
(författare)
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Impact of rotation of wheels and bogie cavity shapes on snow accumulating on the bogies of high-speed trains
- 2019
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 159, s. 58-70
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Tidskriftsartikel (refereegranskat)abstract
- The snow accumulation on the bogies of a high-speed train was studied using the unsteady Reynolds-Averaged Navier-Stokes simulations (URANS) coupled with the Discrete Phase Model (DPM). The effects of the rotation of wheels, shape of bogie fairings and length of bogie cavities on the flow characteristics and snow accumulation around bogie regions are discussed. The results show that the rotation of wheels significantly affects the flow characteristic and snow distribution around rear plates and the snow accumulation on the top surface of bogies. The shape of bogie fairings has been found to have large influence on the velocity profiles at the inlet and the outlet of bogie cavity, and thereby on the snow accumulation. The bogies without fairing have been found to be less influenced by the snow in the flows without crosswinds. The length of the bogie's cavity was found to have dominant role on the distribution of particle concentration and snow accumulation on the bogie surface. The total mass of snow accumulation on the bogie surface was shown to decrease with the shorter bogie cavity. Finally, the shorter bogie cavity is recommended for the design of the high-speed trains running under the circumstances permitted by the vehicle gauge.
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| 22. |
- Wu, Mousong, et al.
(författare)
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Solute and water effects on soil freezing characteristics based on laboratory experiments
- 2015
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 115, s. 22-29
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Tidskriftsartikel (refereegranskat)abstract
- Laboratory experiments were conducted to study effects of water and solute on soil freezing using TDR and temperature sensor combination methods. ANOVA methods were applied for analyzing significance for solute influences on soil freezing characteristic curve (SFCC). Results showed that higher initial water content influenced the SFCC by increasing liquid water content at the same temperature due to more water connection with soil pores, and adsorbed by soil particles. ANOVA results showed solute content and solute type all had significant effects (P < 0.001 to P < 0.5) on soil freezing processes. And solute in soil resulted in a lower freezing point of soil, which made more liquid water co-exist with ice at negative temperatures. And solute concentration condensing due to liquid water decline would also impede soil freezing processes by decreasing osmotic potential. Due to the physical and chemical process of soil solution, different ions also presented some differences in SFCC parameter estimation. Based on a trial and error method, a prediction model was also built, and it behaved well in predicting SFCC under different water and solute conditions.
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| 23. |
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