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  • 1.
    Eidevåg, Tobias
    et al.
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden. Contamination and Core CFD, Volvo Car Corporation, SE-40531 Gothenburg, Sweden.
    Thomson, Erik S.
    Department of Chemistry & Molecular Biology, Atmospheric Science, University of Gothenburg, SE-41296 Gothenburg, Sweden.
    Sollén, Sofia
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Casselgren, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Rasmuson, Anders
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
    Collisional damping of spherical ice particles2021In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 383, p. 318-327Article in journal (Refereed)
    Abstract [en]

    This paper presents experimental values for the coefficient of restitution (en) for millimeter-sized ice particles colliding with massive walls at different temperatures. Three different wall materials are tested: hardened glass, ice and Acrylonitrile butadiene styrene (ABS) polymer. The results show a high sensitivity to impact velocity Vi, where en decreases rapidly with increasing Vi. The results also show a decrease in en with increasing temperature T. A novel model that predicts en based on the assumption of collisional melting and viscous damping caused by an increased premelted liquid-layer, is proposed. The model predicts both the velocity and the temperature trends seen in the experiments. The difference obtained in experiments between wall materials is also captured by the new model. A generalized regime map for ice particle collisions is proposed to combine the new model with previous work.

  • 2.
    Sollén, Sofia
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Monitoring winter road friction using floating car data2022Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    More than a million people die every year due to road traffic accidents globally where one in five serious or fatal accidents occurs during severe weather conditions. Sweden is in the lead of Vision Zero, with the aim of zero casualties due to road traffic, and every year new countries and organisations accept the challenge of saving lives. Early studies have shown that one way of decreasing casualties is to implement floating car data (FCD), which is data obtained from connected road vehicles. One example of such an implementation is to gather knowledge about the current state of the road network enabling targeted winter road maintenance. By implementing FCD for winter road maintenance, besides creating safer roads, savings will be made for the environment by reducing the use of fossil fuels and salt.

    Since the fleet of road vehicles is going towards being fully autonomous, the volumes of FCD will increase rapidly generating new possibilities for FCD usage. Recent research regarding FCD has mainly focused on traffic flow, speed and route optimisation, together with general methods for FCD mining creating intelligent transport systems. Studies have also been made to cover the gap between road weather information systems (RWIS) monitoring the road condition and thereby improving road weather forecasts. But there is a need for research regarding the implementation of FCD at a level of action, closer to the road users improving winter road maintenance.

    Presented in this thesis are results gathered in the project Digital Winter, a project initiated by the Swedish Traffic Administration, where FCD regarding tire-to-road friction has been procured for all public roads in Sweden. Results show promising numbers regarding coverage and reliability for implementation of FCD for winter road maintenance follow-up, managing that assigned levels of road friction are achieved. Examples are given for different areas in Sweden where harsh weather conditions are detected and statistics show coverage of FCD both at a daily and hourly level. Multiple suppliers of FCD have been participating in Digital Winter and the measurements presented, show a correlation between suppliers of FCD and methods that today are approved for winter road maintenance follow-up in Sweden. But also that the friction measured using FCD is closer to the true road friction experienced by road users.

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  • 3.
    Sollén, Sofia
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Casselgren, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Comparing floating car data regarding tire-to-road friction for different-sized operational areas during winter- and summertime in Sweden2023In: Pre-proceedings Prague 2023, 2023Conference paper (Refereed)
  • 4.
    Sollén, Sofia
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Casselgren, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Comparison of methods for winter road friction estimation using systems implemented for floating car data2023In: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, E-ISSN 1745-6444, Vol. 17, no 2, p. 101-111Article in journal (Refereed)
    Abstract [en]

    Winter road maintenance is important for preventing accidents and enabling mobility. If the road friction gets low, there is a higher risk of road accidents. Therefore, it is vital to have information about road friction levels. Traditionally this is done by dedicated vehicles; however, using friction information from floating car data (FCD) would be more beneficial, as the coverage both in time and space increases. In this investigation, road friction data from three FCD suppliers, using only one test vehicle each, has been compared with a continuous method of road friction measurement. The test has been conducted on proving grounds covered with ice and snow, and on public roads covered with water, ice, snow, and slush; thereby both high friction and low friction surfaces have been evaluated. The investigation shows that the FCD provides a continuous method of friction measurement and is closer to the reality of road friction experienced by road users.

  • 5.
    Sollén, Sofia
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Casselgren, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Correlation between floating car data and road weather information implemented for winter road maintenance follow-up by monitoring theroad friction2023Conference paper (Refereed)
    Download full text (pdf)
    fulltext
  • 6.
    Sollén, Sofia
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Casselgren, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Friction information from floating car data2022Conference paper (Refereed)
  • 7.
    Sollén, Sofia
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Casselgren, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Large‐scale implementation of floating car data monitoring road friction2021In: IET Intelligent Transport Systems, ISSN 1751-956X, E-ISSN 1751-9578, Vol. 15, no 6, p. 727-739Article in journal (Refereed)
    Abstract [en]

    In Sweden today, friction measurements are performed manually, often using methods generating spot‐wise measurements. Because the low numbers of measurements provided by these methods are insufficient to follow up on the friction requirements set by the Swedish Transport Administration, the Administration has initiated the Digital Winter project. In Digital Winter, floating car data (FCD) are utilised for road friction estimation. The focus in this investigation is on coverage, and on whether the FCD detects harsh weather conditions with decreasing road friction. Two different methods—one continuous and one slip‐based—are implemented in this investigation. Furthermore, different approaches on how to build the vehicle fleet to collect the FCD have been applied using different combinations of commercial and private vehicles. The results showed that both methods detect low‐friction events, and for roads with high annual average daily traffic (AADT), the data collection using slip‐based methods and larger fleets gives more data points than for smaller fleets using continuous methods, and the reverse is true for lower AADT. The results showed differences between the two fleets in terms of coverage for the weekly and daily distributions, but overall, the method of using FCD for road friction estimation seems promising for the follow‐up of winter road maintenance.

  • 8.
    Sollén, Sofia
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Eppanapelli, Lavan Kumar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Casselgren, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Pettersson, Jennifer
    Division of Rotating Machines, Vattenfall AB, Asset Development - R&D, Solna, Sweden.
    Ukonsaari, Jan
    Division of Rotating Machines, Vattenfall AB, Asset Development - R&D, Luleå, Sweden.
    Attermo, Pär
    Division of Businesses Area Wind, Vattenfall AB, Solna, Sweden.
    Experimental Investigation of an Infrared Deicing System for Wind Power Application in a Cold Climate2022In: Journal of cold regions engineering, ISSN 0887-381X, E-ISSN 1943-5495, Vol. 36, no 4, article id 04022008Article in journal (Refereed)
    Abstract [en]

    Icing of wind turbine blades poses a great challenge for wind farms in cold climates, this challenge is addressed by implementing various deicing practices that require significant cost to operate. Thus, alternative and potential solutions are needed to improve wind power production in cold climate. The present study is investigates the effectiveness of a new deicing system consisting of infrared heaters. Two types of heaters were selected based on wavelength, input power, and investment cost. The heaters were tested on blades covered with soft rime ice. A thermal camera was used to image the deicing procedure together with a load cell to measure the weight of the ice melted. It was found that a combination of two different types of heaters provides effective deicing at a distance of 1.5 m compared with multiple units of the same type of heaters. It was observed that the infrared deicing system has a larger area of heat distribution, which is one of the major advantages compared with traditional systems. © 2022 American Society of Civil Engineers.

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