1,720,978 research outputs found
Thermal behaviour of green façades in summer
Full text linkBuilding greenery systems can represent a sustainable solution for new buildings design and for existing buildings retrofitting, in order to improve the thermal energy performance of buildings, to decrease building energy loads and to contrast the Urban Heat Island. Green façades can influence thermal properties of a building by means of different important mechanisms: the shading, the cooling, the insulating and the wind barrier effect. Moreover, green façades accomplish heating effect in the cold season and at nighttime. An experimental test was developed at small scale at the University of Bari (Italy) from 2014 to 2016 for testing two different green façades. The plant species chosen were Pandorea jasminoides variegated and Rhyncospermum jasminoides, two evergreen climbing plants. A third uncovered wall was used as control. The thermal behaviour of the plants was analysed during the 2016 summer season, by keeping in consideration the external surface temperature of the building and the temperature of the airgap behind the green vertical systems. The daylight temperatures observed on the plant-covered walls during representative days were lower than the respective temperatures of the uncovered wall up to 7.0°C. During nighttime, the temperatures behind the plants were higher than the respective temperatures of the control wall up to 2.2°C. The results shown in the present research allow delineating the behaviour of the two plant species during summer in the Mediterranean climate region
Electrolyzer performance analysis of an integrated hydrogen power system for greenhouse heating a case study
No full textA greenhouse containing an integrated system of photovoltaic panels, a water electrolyzer, fuel cells and a geothermal heat pump was set up to investigate suitable solutions for a power system based on solar energy and hydrogen, feeding a self-sufficient, geothermal-heated greenhouse. The electricity produced by the photovoltaic source supplies the electrolyzer; the manufactured hydrogen gas is held in a pressure tank. In these systems, the electrolyzer is a crucial component; the technical challenge is to make it work regularly despite the irregularity of the solar source. The focus of this paper is to study the performance and the real energy efficiency of the electrolyzer, analyzing its operational data collected under different operating conditions affected by the changeable solar radiant energy characterizing the site where the experimental plant was located. The analysis of the measured values allowed evaluation of its suitability for the agricultural requirements such as greenhouse heating. On the strength of the obtained result, a new layout of the battery bank has been designed and exemplified to improve the performance of the electrolyzer. The evaluations resulting from this case study may have a genuine value, therefore assisting in further studies to better understand these devices and their associated technologies
Deep-Seated Landslide and Rockfalls Threatening the Village of Pietracamela in Central Italy: Deciphering Phenomena from Interferometric Synthetic Aperture Radar and Point Cloud Analysis
No full textLandslides represent a major problem in human activities, especially in the proximity of cities or infrastructure. In this paper, we present the peculiar case of Pietracamela, Italy. Pietracamela is a small village located in the Central Apennines, a few kilometers north of the Gran Sasso Mountain. The peculiarity of the case study is the fact that the village is simultaneously affected by two different types of slope instabilities. The southwest sector, representing the historical part of the village, has been affected by large rockfalls generated from the “Capo le Vene” cliff located in the south of the village. The northeastern sector of the village represents the most recent urbanized area and is involved in a deep-seated landslide that, in the last decades, has damaged buildings and infrastructure. In this context, we have used two different types of remote sensing techniques to study the two phenomena. The rockfall area has been surveyed through the use of an Unmanned Aerial Vehicle (UAV) that allowed the definition of main joint sets and the volume of blocks associated with the most recent (2011) rockfall event. Three main joint sets have been highlighted, which are responsible for the failure of the “Capo le Vene” cliff. The volume of blocks that failed during the last rock failure in 2011 ranged from a few to 1500 m3. The deep-seated landslide has been studied by analyzing borehole data and 20 years of InSAR data from ERS1/2, ENVISAT, COSMO-SkyMed, and SENTINEL-1. It has been highlighted by InSAR analysis that the northeast sector of the village shows a perfectly linear displacement trend that generates movements up to about 230 mm (about 1 cm/year)
Mapping landslide prediction through a GIS-based model: A case study in a catchment in southern Italy
Full text linkShallow landslides are an increasing concern in Italy and worldwide because of the frequent association with vegetation management. As vegetation cover plays a fundamental role in slope stability, we developed a GIS-based model to evaluate the influence of plant roots on slope safety, and also included a landslide susceptibility map. The GIS-based model, 4SLIDE, is a physically based predictor for shallow landslides that combines geological, topographical, and hydrogeological data. The 4SLIDE combines the infinite slope model, TOPMODEL (for the estimation of the saturated water level), and a vegetation root strength model, which facilitates prediction of locations that are more susceptible for shallow landslides as a function of forest cover. The aim is to define the spatial distribution of Factor of Safety (FS) in steep-forested areas. The GIS-based model 4SLIDE was tested in a forest mountain watershed located in the Sila Greca (Cosenza, Calabria, South Italy) where almost 93% of the area is covered by forest. The sensitive ROC analysis (Receiver Operating Characteristic) indicates that the model has good predictive capability in identifying the areas sensitive to shallow landslides. The localization of areas at risk of landslides plays an important role in land management activities because landslides are among the most costly and dangerous hazards
Root biomechanical traits in a montane mediterranean forest watershed: Variations with species diversity and soil depth
No full textPlant roots play a key role in stabilizing slopes, particularly in the Mediterranean region, characterized by rough and unstable terrain. However, forest species differ in their stabilizing capacities. The purpose of this study is to fill the gap of knowledge on root biomechanical properties of relevant Mediterranean trees and shrubs in relation to slope stability. Root specimens of typical montane Mediterranean tree and shrub species were sampled in Southern Italy. Root characteristics, such as tensile strength (Tr) and root area ratio (RAR), were assessed from live roots sampled in trenches, while root cohesion was calculated. Power law functions yielded the best fit for the relationship of Tr versus root diameter; however, no significant relationship was found between root strength and root moisture content. RAR varied amongst different tree and shrub species. Roots of Quercus cerris L. were the most resistant to breaking under tension, while roots of Ilex aquifolium L. had the highest tensile strength among all shrub species. Results provide quantitative information on the role of root systems of montane Mediterranean forest species in stabilizing soils and will improve modeling of landslide susceptibility to the prevention and mitigation of natural hazards in mountain environments
Evaluation of wall surface temperatures in green facades
No full textGreen walls can be used to control the building microclimate as passive systems for energy saving. Three vertical walls were built at the University of Bari (Italy). The first wall was covered with Pandorea jasminoides variegated and the second with Rhyncospermum jasminoides; the third wall was kept uncovered as a control. High-definition infrared images were recorded, and several climatic parameters concerning the walls and the ambient conditions were collected during the experimental test. The daylight temperatures observed on the shielded walls during warm days were lower than the respective temperatures of the uncovered wall by up to 9·0°C; the nighttime temperatures observed during cold days were higher than the respective temperatures of the control wall by up to 6·0°C. The effective thermal resistance of the plants was calculated, using experimental data for a whole year; it ranged from 0·07 to 3·61m2 K/W
Experimental setup to evaluate the water permeability index of agricultural nets
No full textA system made of textiles able to protect cultivations from the damages of rain fall and to let pass through, could increase the yield and quality of the production and the reliability of predictions for the harvesting of many fruits such as cherries. To this purpose a test device was designed and set up at Arrigoni S.p.A. to simulate and measure the rain permeability of agricultural nets at different inclinations, in terms of water amount reduction passing through the net when exposed to the rain. Rain permeability index of the net was defined as the ratio between the water sprayed by the nozzles and the water gathered into the container under the net sample. Nets with different geometrical characteristics characterized by having low porosity were tested. Since the porosity could be of little significance to describe the agrotextile, water permeability was correlated with the air permeability of each sample measured in a micro wind tunnel. The first results allowed to understand the influence of the main parameters on water permeability of the nets. The mesh size, the inclination of the net and the use of the double layers scheme of the protection system were found to give the most significant change to the rain permeability behaviour of the nets
Georeferencing of agricultural plastic waste
No full textThe use of plastic materials in agriculture, for greenhouse covering, soil mulching, irrigation pipes, containers and bags, generates a huge amounts of plastic waste that must be properly disposed of. An adequate waste management and disposal system requires the knowledge of the waste generation on the land. This paper presents the results of a research, based on the application of a Geographical Information System, for mapping the waste generation in the municipality of Trinitapoli, Italy. Aim of the research is to identify the points of waste generation and to quantify the waste. A dedicated geo-referenced database with data on the spatial distribution and amount of the plastic wastes was created; waste density ranged from 3.3 kg ha-1yr-1 to 861 kg ha-1yr-1
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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