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  • 1.
    Lintzén, Nina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Danvind, Jonas
    Dept. of Quality Management and Mechanical Engineering, Mid Sweden University, Östersund, Sweden.
    Söderström, Erik Melin
    Peak Innovation, Östersund, Sweden.
    Nilsson, Kajsa
    Dept. of Quality Management and Mechanical Engineering, Mid Sweden University, Östersund, Sweden.
    Skoglund, Per
    Dept. of Quality Management and Mechanical Engineering, Mid Sweden University, Östersund, Sweden.
    Laboratory Investigation of Different Insulating Materials Used for Snow Storage2019Ingår i: Journal of cold regions engineering, ISSN 0887-381X, E-ISSN 1943-5495, Vol. 33, nr 4, artikel-id 04019012Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Storage of snow has become of increasing interest for the winter business industry. Covering a pile of snow with an insulating material protects the snow from heat transfer from the surroundings and reduces the melting. Storing snow enables ski resorts to set an opening date, and it can also be used to secure winter sports events that are dependent on snow. Cover materials that are commonly used as insulation are wood-based materials, such as sawdust, and textile materials and sheets. How efficiently a cover material functions as thermal insulation depends on the material characteristics and thickness of the insulating layer. In this study, results from a laboratory experiment are presented, which aimed at comparing different commonly used cover materials, as well as some other materials that have not previously been used as thermal insulation on snow. Different layer thicknesses were also investigated. The results show that the insulating capacity of sawdust is reduced with time. Despite degrading insulating properties with time, sawdust is still considered one of the best materials to use as insulation on snow, and it is also more efficient than the textile materials investigated in this study. Doubling the textile layers or adding a three-dimensional (3D) spacer textile, which implies adding a layer of air between the textile and the snow, reduces the snow melting. Water absorption, water transport, and evaporation of water affect the melting. In this work, evaporative cooling did not prove to reduce melting; therefore, it was not evident whether a textile material should be permeable. An interesting material used in the study was Quartzene, which absorbed all the melt water and protected the snow most efficiently of the materials tested.

  • 2.
    Bonath, Victoria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Edeskär, Tommy
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Lintzén, Nina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Fransson, Lennart
    Cwirzen, Andrzej
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Properties of ice from first-year ridges in the Barents Sea and Fram Strait2019Ingår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    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.

  • 3.
    Eppanapelli, Lavan Kumar
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lintzen, Nina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Casselgren, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Wåhlin, Johan
    Department of Civil and Transport Engineering, Norwegian University of Science and Technology.
    Estimation of Liquid Water Content of Snow Surface by Spectral Reflectance2018Ingår i: Journal of cold regions engineering, ISSN 0887-381X, E-ISSN 1943-5495, Vol. 32, nr 1, artikel-id 05018001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study measures the spectral reflectance from snow with known liquid water content (LWC) in a climate chamber using two optical sensors, a near-infrared (NIR) spectrometer and a Road eye sensor. The spectrometer measures the backscattered radiation in the wavelength range of 920–1,650 nm. The Road eye sensor was developed to monitor and classify winter roads based on reflected intensity measurements at wavelengths of 980, 1,310, and 1,550 nm. Results of the study suggest that the spectral reflectance from snow is inversely proportional to the LWC in snow. Based on the effect of LWC on the spectral reflectance, three optimum wavelength bands are selected in which snow with different LWCs is clearly distinguishable. A widely used remote sensing index known as the normalized difference water index (NDWI) is used to develop a method to estimate the surface LWC for a given snow pack. The derived NDWI values with respect to the known LWC in snow show that the NDWI is sensitive to the LWC in snow and that the NDWI and LWC are directly proportional. Based on this information, the NDWI is used to estimate the surface LWC in snow from measurements on a ski track using the Road eye sensor. The findings suggest that the presented method can be applied to estimate the surface LWC in order to classify snow conditions potentially for ski track and piste applications.

  • 4.
    Lintzén, Nina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Snow storage: modelling, theory and some new research2018Ingår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 153, s. 45-54Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    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.

  • 5.
    Lintzén, Nina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Properties of snow with applications related to climate change and skiing2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Snow has been a subject of research since the mid-20th century. Research on mechanical properties of snow started as an off-shoot of soil mechanics, where methods, tools and instruments used often are the same. However, during the last decades the winter business industry has been growing requiring a number of new fields of research. The aim with this PhD thesis is to investigate and contribute to solutions of some of the new research problems appearing in this area. Machine-made snow is commonly used for buildings and artwork of snow. Only minor scientific studies of machine-made snow and its properties have been published. Therefore, mechanical properties of machine-made snow were investigated. Strength and deformation properties were evaluated through uniaxial compressive tests where cylindrical test specimens were subjected to different constant deformation rates. Creep deformation, bending strength and ultimate load were also evaluated through beam tests. The results showed that the deformation rate is crucial if the snow will deform plastically or if brittle failure will occur. The grain size and structure of the snow had a strong influence on the strength properties. Snow is a constantly changing material with a large variety of grain sizes and shapes. Therefore it is of importance to classify snow. Classication of snow can be done using different methods depending on the property that is to be investigated. Several non-contact detection methods to evaluate snow properties exist. In this thesis, spectral reflectance measurements were performed to investigate liquid water content in snow using two different systems, a spectrometer and an optical sensor called Road Eye. The Road Eye sensor was also used to classify snow in cross-country ski tracks. This method enables a fast classication of a complete track where different types of snow can be distinguished. The properties of a ski track and the characteristics of the snow determine the type of skis that should be selected for optimum sliding properties. Cross-country skis have different mechanical properties, which to a large extent can be evaluated from the span curve of the ski. Depending on the skiing style, the skier's skills, terrain and track conditions different ski properties are required, which is particularly important for competitive skiing. Span curves of cross-country skis were measured using a digital instrument called Skiselector. Results from the investigations showed that skis within the same pair may have signicantly different properties. Moreover, temperature influences the span curve and thus the mechanical properties of the skis. Therefore, skis should be measured at a temperature close to where they are aimed to be used. Field tests of skis with similar span curves but different ski base topography were tested during wet and cold snow conditions. The results indicate that different topographies are preferable during different snow conditions. Due to the climate change, winters have become shorter and warmer with less natural snow. To compensate for the lack of natural snow, ski resorts and other stakeholders produce machinemade snow in order to run their business. Storing snow in insulated piles is an alternative and sometimes a complement to snow production. Studies on stored snow show that the surface area of the pile should be minimized in order to reduce the melt rate. Furthermore, the pileshould be covered with a suciently thick insulating layer, preferably with good evaporation properties. Theoretical calculations can be used to estimate the amount of snow that melts and to predict the efficiency of different materials as thermal insulation on snow. These calculations coincide well with experiments performed in northern Sweden where snow melt was measured. This PhD thesis consists of five publications and an introduction to this area which in particular puts these publications into a more general frame.

  • 6.
    Lintzén, Nina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Almqvist, Andreas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Grip, Niklas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Span curve temperature dependence of classic style cross country skis2016Ingår i: Sports Technology, ISSN 1934-6182, E-ISSN 1934-6190Artikel i tidskrift (Refereegranskat)
  • 7.
    Lintzén, Nina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Edeskär, Tommy
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Uniaxial Strength and Deformation Properties of Machine-Made Snow2015Ingår i: Journal of cold regions engineering, ISSN 0887-381X, E-ISSN 1943-5495, Vol. 29, nr 4, artikel-id 4014020Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Snow as a construction material has been used for centuries, with igloos among the first examples. Each winter, snow and ice villages, buildings, and artwork are built in many places around the world. Machine-made snow manufactured by snow guns is commonly used for constructions made of snow. However, only a few basic studies on machine-made snow have been published. Knowledge based on experience and studies on natural snow constitute the basis for constructions made using snow and ice. Through material tests on machine-made snow used for construction, data on important physical and mechanical properties have been established that aim to improve and optimize safe constructions made from snow. Strength tests have been performed using two different qualities of machine-made snow. Specimens used for testing were cut out from one block of snow that had a coarse-grained structure with clusters of ice in the snow and from one block of snow with a fine-grained and homogeneous structure. The density for each tested snow sample was measured and strength tests were performed at different deformation rates to investigate the relationship between mechanical properties and deformation rate or strain rate. The load response curves achieved from the strength tests were used to evaluate compressive strength, Young’s modulus, and the residual modulus. The results show that compressive strength increases with increasing density. Increasing compressive strength with an increasing strain rate was also observed for fine-grained snow quality specimens, whereas no similar tendency was observed for coarse-grained snow. The residual modulus increased with an increasing strain rate up to a certain critical value for the fine-grained machine-made snow specimens. Regression analysis was used to investigate whether any dependence was observed between the calculated mechanical properties; no further relationship between the mechanical and the physical properties was noticed

  • 8.
    Lintzén, Nina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mechanical properties of artificial snow2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Mechanical properties of snow have been a subject of research since the mid-20th century. Theresearch done is based on natural snow. During the last decades the winter business industryhas been growing and also the interest for constructing buildings and artwork of snow. Suchconstructions are generally built using artificial snow, i.e. snow produced by snow guns. Up tothe present constructions of snow are designed based on knowledge by experience. Only minorscientific studies on artificial snow and its properties has been published. Hence it is ofimportance to investigate material properties for artificial snow.A survey of current state of the art knowledge of properties for natural snow was done andbasic material properties for different qualities of artificial snow were investigated. Strengthand deformation properties for artificial snow were evaluated through uniaxial compressivetests where cylindrical test specimens were subjected to different constant deformation rates.The results show that artificial snow at low deformation rates will have a plastic deformationbehavior where the initial deformation will cause a hardening of the snow structure. At higherdeformation rates brittle failure may occur. For artificial snow with a homogeneous and finegrained structure the deformation behavior was found to change from plasticity to brittleness ata certain critical deformation rate. Artificial snow with coarse grained structure was found to bebrittle giving unstructured results independent of the load level.Four point loading was applied on beams of artificial snow to study creep deformation, bendingstrength and to determine the ultimate load for the different snow qualities. The results showedcoarse grained artificial snow underwent relatively small creep deformations. Both the creepbehavior and the ultimate strength varied randomly at the same applied load. Large plasticdeformations were observed with the fine grained artificial without any failure of the beams.The ultimate load was relatively high and repeatable results were achieved for all test.Previous presumptions that coarse grained artificial snow with high density would have highstrength and were not confirmed by the experiments performed on different qualities ofartificial snow. The performed tests indicate that fine grained artificial snow of lower densityhave more predictable strength properties of equally high or higher magnitude as for coarsegrained artificial snow. The plastic deformations were however higher for the fine grainedartificial snow. High deformations are not favorable for structures which should maintain theshape during the winter season. When designing constructions of snow both strength anddeformation properties should be taken into account.

  • 9.
    Lintzén, Nina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Compressive strength of snow: Experimental mesaurements at ICEHOTEL, April 20122012Rapport (Övrigt vetenskapligt)
  • 10.
    Lintzén, Nina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Snow storage in Piteå 20122012Rapport (Övrigt vetenskapligt)
  • 11.
    Lintzén, Nina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Snowmaking and snowstorage2012Rapport (Övrigt vetenskapligt)
  • 12.
    Lintzén, Nina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Edeskär, Tommy
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Study on basic material properties of artificial snow2012Ingår i: Proceedings of Nordic Conference on Soil Mechanics and Geotechnical NGM, Copenhagen: Danish Geotechnical Society , 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    For buildings and constructions made by snow, like for example the ICEHOTEL in Jukkasjärvi, generally artificial snow is used. Both for safety reasons and for design purposes it is hence of importance to understand the material behaviour of artificial snow. Many buildings and structures made by snow and ice are constructed using knowledge obtained by experience.When subjected to a load snow undergoes an immediate elastic deformation and a time-dependent irreversible deformation, known as snow creep, which constitutes the considerably highest part of the total deformation. The magnitude of the snow creep deformation is the dominating deformation mechanism for snow structures but it is poorly investigated and not well understood.To study material parameters and mechanical behaviour of artificial snow unconfined compression test and deformation tests to observe the creep behaviour have been performed. Results from experimental tests have been analyzed and compared with theoretical calculations and finite element simulations. The density and viscosity have shown to be important parameters for the deformation behaviour and will have a direct influence on the creep rate. The investigation indicates that the artificial snow used for the tests have higher density, compression strength and creep strength compared to natural snow used in other studies.

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