Energy demand and yield enhancement for roof mounted photovoltaic snow mitigation systems

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Polar solar power plants – Investigating the potential and the design challenges

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Evolving timber school building design in Norway

Due to the eminent importance of global sustainability, Norwegian municipalities as acting clients for school buildings, have initiated the usage of massive timber (Cross Laminated Timber) in new buildings. This paper is aiming to gain knowledge regarding the construction of massive timber school buildings by examining three case studies located in Norway. The findings suggest that appear to be four main factors that determine the choice and placement of material in the selected buildings: sustainability, topography, function and structure. Sustainability goals advocate maximization of usage of massive timber in the school buildings. Topography indicates that underground volumes are constructed in concrete and steel. Function and structure restrict the usage of CLT in main teaching spaces that have smaller spans, while acoustically challenging spaces like music rooms and auditoriums are constructed in steel and concrete. Literature also showed an evolution of massive timber construction in Norway, with contemporary architects and engineers achieving larger room spans than 10 years ago. Based on the findings, CLT construction is increasing and can change the way schools are being built in the Nordics.acceptedVersio

Applications of "SnoWind" engineering - Climatic WInd tunnel Methods

-Transport and deviation of snow by wind induce many constraints on buildings, vehicles and indus - trial systems. a selection of questions from snow-wind engineering are presented in the paper. The experimental method that was undertaken to investigate these questions makes use of a large climatic wind tunnel, partly designed to address snow engineering problems at full scale: snow penetration in buildings, into ventilation systems of buildings and vehicles and snow or ice accretions on struc - tures

Estimation of phosphorus-based flame retardant in wood by hyperspectral imaging—a new method

It is recognised that flame retardant chemicals degrade and leach out of flame-protected wood claddings when exposed to natural weathering. However, the ability to survey the current state of a flame retardant treatment applied to a wood cladding, an arbitrary length of time after the initial application, is limited today. In this study, hyperspectral imaging in the near infrared to short-wavelength infrared region is used to quantify the amount of flame retardant present on wooden surfaces. Several sets of samples were treated with various concentrations of a flame retardant chemical and scanned with a push broom hyperspectral camera. An inductively coupled plasma (ICP) spectroscopy analysis of the outermost layer of the treated samples was then carried out in order to determine each sample’s phosphorus content, the active ingredient in the flame retardant. Spectra from the hyperspectral images were pre-processed with extended multiplicative scatter correction, and the phosphorus content was modelled using a partial least squares (PLS) regression model. The PLS regression yielded robust predictions of surface phosphorus content with a coefficient of determination, R2, between 0.8 and 0.9 on validation data regardless of whether the flame retardant chemical had been applied to the surface of the wood or pressure-impregnated into it. The result from the study indicates that spectral imaging around the 2400–2531nm wavelength region is favourable for quantifying the amount of phosphorus-based flame retardant contained in the outermost layer of non-coated wooden claddings. The results also reveal that the uptake of phosphorus-based flame retardant does not occur uniformly throughout the wood surface, but is to a larger extent concentrated in the earlywood regions than in the latewood.publishedVersio

Hyperspectral NIR time series imaging used as a new method for estimating the moisture content dynamics of thermally modified Scots pine

The purpose of this research is to develop a method for estimating the spatially and temporally resolved moisture content of thermally modified Scots pine (Pinus sylvestris) using remote sensing. Hyperspectral time series imaging in the NIR wavelength region (953–2516 nm) was used to gather information about the absorbance of eight thermally modified pine samples each minute as they dried during a period of approximately 20 h. After preprocessing the collected spectral data and identifying an appropriate wavelength selection, partial least squares regression (PLS) was used to map the absorbance data of each pine sample to a distribution of moisture contents within the samples at different time steps during the drying process. To enable separate studying and comparison of the drying dynamics taking place within the early- and latewood regions of the pine samples, the collected images were spatially segmented to separate between early- and latewood pixels. The results of the study indicate that the 1966–2244 nm region of a NIR spectrum, when preprocessed with extended multiplicative scatter correction and first order derivation, can be used to model the average moisture content of thermally modified pine using PLS. The methods presented in this paper allows for estimation and visualization of the intrasample spatial distribution of moisture in thermally modified pine wood.publishedVersio

Characterisation of shear stress distribution on a flat roof with solar collectors

-i n the search for new renewable energy sources, photovoltaic systems and solar thermal collectors have become more common in buildings. With increased efficiency and demand for energy, solar power has also become exploitable at higher latitudes where snow is a major load on buildings. For flat roofs, one usually expects approximately 80% of the snow to be eroded off the roof surface. i nstalling solar panels would change this since the flow pattern and wind conditions on the roof are affected by their presence. t his study shows the erosion of sand particles from underneath solar panels of various configurations associ - ated with different wind velocities. The pattern of erosion is used to determine the relative friction velocity, u * rel , of the wind on the roof. t his value is the friction velocity on the roof relative to the friction velocity on a flat roof without solar panels. t he experiments, conducted in a wind tunnel, show that the area where u * rel is 0 and where it is expected that sand and snow will accumulate in case of an upwind particle source and decrease with increasing distances between roof and solar panel. i t is also shown that a larger gap between the solar panel and roof surface creates larger erosion zones, where u * rel > 1 for both wind directions. s ince the erosion is closely linked to the air flow under the solar panels, and that higher air velocity increases the erosion, it is likely that a larger solar panel, extending higher into the free air flow would be desirable to avoid snow accumula - tion on a flat roof with solar panels. i f the solar panel has large enough dimensions, the solar panels can be used as a deflector to decrease snow accumulation on flat roofs. With solar panels of the size in the current experiments, a building with a length smaller than the equivalent of x/L = 0.3 would have u * rel > 1 on most of the roof surface and would thus likely have a lower snow load than an equivalent float roof without solar panels

Polar solar power plants – Investigating the potential and the design challenges

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Urban surfaces studied by VIS/NIR imaging from UAV: Possibilities and limitations

The present research approach aims at analyzing the relation between material properties and their thermal behavior using airborne multispectral imaging in VIS/NIR and IR with sensors mounted on Unmanned Aerial Vehicle (UAV). As a follow up to a pilot study from spring 2016, a survey including several flights spanned over three days, from early morning before sunrise until late evening after sunset, was carried out in Athens in June 2017. The camera specifications for the survey in 2017 were different than the ones used in 2016. The performance of the cameras was evaluated, taking into account atmospheric correction. The images have been combined to form maps of surface temperature distribution and material physical properties. The VIS/NIR images were used to classify the different surface materials, to compute a map of estimated albedo, and to construct a 3D-model of the area. By combining thermal maps with material classification, albedo information and local weather data, thermal material properties could be characterized for the various materials. The derived properties from this dataset yield valuable information for improved simulation models of urban climate.submittedVersion© 2018 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited