2,616 research outputs found

    Downscaling of global solar irradiation in R

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    A methodology for downscaling solar irradiation from satellite-derived databases is described using R software. Different packages such as raster, parallel, solaR, gstat, sp and rasterVis are considered in this study for improving solar resource estimation in areas with complex topography, in which downscaling is a very useful tool for reducing inherent deviations in satellite-derived irradiation databases, which lack of high global spatial resolution. A topographical analysis of horizon blocking and sky-view is developed with a digital elevation model to determine what fraction of hourly solar irradiation reaches the Earth's surface. Eventually, kriging with external drift is applied for a better estimation of solar irradiation throughout the region analyzed. This methodology has been implemented as an example within the region of La Rioja in northern Spain, and the mean absolute error found is a striking 25.5% lower than with the original database

    In-plane shear cyclic behavior of windowed masonry walls reinforced with textile reinforced mortars

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    The current experimental study is focused on the mechanical performance of masonry walls under in-plane cyclic shear forces. All specimens were fabricated with a central window, in which the geometry considered the recommendations of the Spanish structural seismic design code. Windows represent a weak area in the masonry structure, in which there are stress concentrations responsible for crack initiation. In order to improve the mechanical strength and ductility, a reinforcement with a Textile Reinforced Mortar (TRM) was used on both sides of the wall. The performance of the unreinforced and reinforced masonry has been discussed in terms of strength and ductility gain, stiffness degradation and energy dissipation capacity. The experimental tests comprised an initial vertical preload, and shear cycles with increasing amplitude. All tests were monitored by means of traditional displacement transducers, and digital image correlation. The analysis of the images showed the time evolution of the overall crack distribution. The TRM effect could be observed as an increase of the mechanical strength (maximum shear from 120 kN to more than 300 kN), higher displacements (drift from 9 to 35 mm), and more energy dissipation (the cumulative energy loss from 2.7 to 12.7 kN·m). In addition, the TRM reinforcements were capable of controlling the crack initiation and growth. The widespread crack along mortar joints observed in the unreinforced masonry became localized cracks (from the window’s corners mainly), in which crack growth direction was not determined by masonry joints.The authors would like to acknowledge Mapei Spain S.A. for the materials supplied in this research. This research was funded by Spanish Ministry of Economy and Competitiveness, grant number BIA2015-69952-R and Spanish Ministry of Science, Innovation and Universities, grant number RTI2018-101148-B-I00

    Discovery of recurring slope lineae candidates in Mawrth Vallis, Mars

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    We thank NASA, JPL, University of Arizona, Malin Space Science Systems, Arizona State University, and The Johns Hopkins University Applied Physics Laboratory for providing HiRISE, CTX, CRISM images and related products free of charge. A.B. acknowledges the Swedish Research Council for supporting his research in cold arid environments. L.S. acknowledges the German Academic Exchange Service (DAAD) for her PhD scholarship. We acknowledge the Wallenberg Foundation and the Kempe Foundation for supporting the research activities. Data Availability All of the remote sensing data used in this study are freely available from the Planetary Data System (http://pds.nasa.gov) and from sensor-specific websites such as http://hirise.lpl.arizona.edu/ and http://crism-map.jhuapl.edu/. All the data products analysed for this study are included as web references in the figure captions and text of this article.Peer reviewedPublisher PD

    Distribution and Morphologies of Transverse Aeolian Ridges in ExoMars 2020 Rover Landing Site

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    We thank the efforts of the guest editor and the reviewers for their suggestions in improving the paper. We acknowledge the Wallenberg Foundation and the Kempe Foundation for supporting our Mars research activities in general. We thank Scott Nowicki for providing us the TES-derived rock abundance global dataset for Mars. We thank NASA, JPL, and University of Arizona for providing HiRISE images and DTMs free of charge. The maps in various figures have been created using ArcGIS version 10.6.1 (http://desktop.arcgis.com/en/arcmap/latest/get-started/setup/arcgis-desktop-quick-start-guide.htm).Peer reviewedPublisher PD

    Crystal defects and spin tunneling in single crystals of Mn12 clusters

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    The question addressed in this paper is that of the influence of the density of dislocations on the spin tunneling in Mn12 clusters. We have determined the variation in the mosaicity of fresh and thermally treated single crystals of Mn12 by analyzing the widening of low angle x-ray diffraction peaks. It has also been well established from both isothermal magnetization and relaxation experiments that there is a broad distribution of tunneling rates which is shifted to higher rates when the density of dislocations increases

    Correction to "Energy Transport in the Thermosphere During the Solar Storms of April 2002"

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    We present corrected computations of the infrared power and energy radiated by nitric oxide (NO) and carbon dioxide (CO2) during the solar storm event of April 2002. The computations in our previous paper underestimated the radiated power due to improper weighting of the radiated power and energy with respect to area as a function of latitude. We now find that the radiation by NO during the April 2002 storm period accounts for 50% of the estimated energy input to the atmosphere from the solar storm. The prior estimate was 28.5%. Emission computed for CO2 is also correspondingly increased, but the relative roles of CO2 and NO remain unchanged. NO emission enhancement is still, far and away, the dominant infrared response to the solar storms of April 2002

    Masonry walls strengthened with Textile Reinforced Mortars (TRM) and subjected to in-plane cyclic loads after real fire exposure

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    A key feature that determines the seismic performance of masonry buildings is the ability of the walls to withstand in-plane cyclic loads. In this context, Textile Reinforced Mortars (TRM) have proven to be a very suitable strengthening solution, although their effectiveness after high temperature exposure is currently practically unexplored. This paper proposes an experimental campaign with full-scale brick walls and carbon fiber TRM, tested to failure under horizontal cyclic in-plane loads, after being exposed to temperatures of about 1000 °C by exposure to real fire. TRM is applied on one or both sides of the walls, and after or before exposure to fire, to simulate different scenarios that a real building could be exposed to. The results show that high temperatures can seriously compromise the integrity of the walls, while TRM can provide effective protection and prevent cracking of masonry from fire. Even after previous fire damage, the reinforcements can double the shear strength of unreinforced damaged walls, and provide high ductility and energy dissipation capacity. However, it is important to note that TRM, even undamaged, may not be able to properly retrofit a severely fire-damaged wall.This research has been funded by the Spanish Ministry of Science, Innovation and Universities, grant number RTI2018-101148-B-I00
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