1,721,073 research outputs found
LIGHTING EQUIPMENT FOR A CROP GROWING SYSTEM IN MICROGRAVITY CONDITIONS FOR SPACE MISSION
No full textThe international scientific community has been making efforts towards developing technologies to realise a sustainable spaceflight Bioregenerative Life Support System for food production, water purification, air revitalisation, and waste recovery in the International Space Station. Space environment, characterized by the absence of the Earth’s gravitational and magnetic fields, of tidal forces, and of the influence of the cyclical events of celestial mechanics, complicates the realization of this kind of system. A critical analysis of the lighting equipment requirements for a crop growing system is presented on the basis of the data and information collected on several Bioregenerative Life Support Systems developed or under development for spaceflight. Aim of the research is to compare different lighting equipment for Bioregenerative Life Support System. Traditional lighting regimes and innovative ones, such as light emitting diode module providing photons in the red and blue regions of the spectrum, has been analysed in order to assess the lighting engineering solutions for a crop growing system on-board the International Space Station supported by Italian Space Agency. The lighting system must maximise photon flux in the spectral range to satisfy plant photosynthesis needs, spatial uniformity and energy efficiency while the thermal load must be minimised because natural convection does not exist in microgravity to transfer heat away from the lights. Plants need photosynthetically active radiation in the wavelengths range between 400 and 700 nm for photosynthesis. Besides it is necessary to control radiation level at 670 and 735 nm which drives the phytochrome response, that is related to plant morphogenesis. Radiation over 750 nm seems not having direct effect on the plant growth and thus needs to be removed as heat via circulation of the chamber air by means of air ventilatio
Measuring strains of LDPE films: The strain gauge problems
No full textLow-density polyethylene (LDPE) films are the most widely used plastic covering materials of greenhouses in Mediterranean Europe. Research concerning these plastic films is an important issue in order to formulate technical suggestions for a reliable design, to make more efficient use of the film and to achieve a longer useful lifetime of LDPE films. Along this line, the elastic mechanical behaviour of LDPE films has been investigated experimentally and numerically. In the course of the experimental work, different approaches were used to measure the strain at selected points of the LDPE film under pressure and also in attempting to measure the Poisson's ratio. In the present work difficulties leading to failure in the measurement of strains of LDPE films are presented along with the analysis concerning the failure of commercial strain gauges for the measurement of strain of LDPE plastic films. © 2002 Elsevier Science Ltd. All rights reserved
Analysis and design of low-density polyethylene greenhouse films
No full textIn the present paper, the mechanical behaviour of low-density polyethylene (LDPE) films under various combinations of pre-tension and uniform pressure schemes is investigated experimentally and numerically using the finite element method of analysis. The behaviour of the film is simulated by means of numerical models and with the material properties obtained in the laboratory by using standard testing methods. The finite element models used include both a commercial finite element program and a recently developed research non-linear finite shell element, capable of modelling membrane behaviour. The numerical analysis results obtained under appropriate boundary conditions and different analysis Options are compared with experimental results obtained from a specifically designed experimental arrangement. For the cases tested experimentally, the two numerical approaches gave results in a good agreement with the experiment results, in the linear elastic region. Subsequently, using the research finite element model, design criteria are developed for the reliable design of LDPE greenhouse films. © 2003 Silsoe Research Institute. All rights reserved. Published by Elsevier Science Ltd
Preparation and Performance of Novel Biodegradable Polymeric Materials Based on Hydrolyzed Proteins for Agricultural Application
No full textAim of the research is the development of biodegradable polymeric materials based on hydrolyzed proteins,
derived from waste products of the leather industry. Particular attention has been devoted to evaluate the application of
such biobased materials in the agricultural practice of mulching. Biobased mulching films were generated in situ by lowpressure
spraying of polymeric water dispersion on the soil; the mulches were tested in an ornamental cultivation carried
out inside a greenhouse. The innovative spray films based on biodegradable components lasted in the field up to 12
months, keeping their mulching effect, thus guarantying weed suppression and preserving soil aggregates
Green façades to control wall surface temperature in buildings
No full textGreen façades can represent a sustainable solution for construction of new buildings and for retrofitting of existing buildings, in order to reduce the energy demands of the cooling systems, to mitigate the urban heat island and to improve the thermal energy performance of buildings. Green façades can allow the physical shading of the building and promote evapotranspiration in summer, and increase the thermal insulation in winter. An experimental test was carried out at the University of Bari (Italy) for two years. Three vertical walls, made with perforated bricks, were tested: two were covered with evergreen plants (Pandorea jasminoides variegated and Rhyncospermum jasminoides) while the third wall was kept uncovered and used as control. 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 up to 9.0 °C. The nighttime temperatures during the cold days for the vegetated walls were higher than the respective temperatures of the control wall up to 3.5 °C. The thermal effects of the facades at daytime was driven by solar radiation, wind velocity and air relative humidity. The highest cooling effect of such parameters occurred with a wind speed of 3–4 ms−1, an air relative humidity within the range 30–60% and a solar radiation higher than 800 Wm−2. The long-term experimental test demonstrated that both Pandorea jasminoides variegated and Rhyncospermum jasminoides are suitable for green façades in the Mediterranean climatic area. The results shown in the present research allow to fill the gap in literature concerning the lack of data for all the seasons of the year, in order to obtain a complete picture of the building thermal performance in the Mediterranean climate region
Heat transfer mechanisms in vertical green systems and energy balance equations
Full text linkThe use of vegetated vertical systems is a sustainable technology for improving the energy efficiency of buildings in cities in order to reduce the energy consumption for air conditioning in summer and to increase the thermal insulation in winter. increasing urban green infrastructure (ugi) in a city can contribute to improve urban climate in summer reducing buildings surface temperature and urban air especially in southern europe. the application of vertical green systems requires the knowledge of the energy performance of the applied greenery system. the choice of the green facades depends on the local climate, water availability, building shape. the presence of green facades affects the building microclimate all day, by reducing heat waves during the warm periods and heat losses from the building in the cold period. the heat and mass transfer between the external environment, the green facades and the building surface determine the building microclimate. solar radiation, long wave infrared radiation, convective heat transfer and evapotranspiration are the main mechanisms of heat transfer in a green façade. the paper describes the main parameters concerning heat flow in green facades that can be used in simulation models for predicting temperatures in buildings using the external weather conditions as model inputs. the input parameters are: external air temperature and relative humidity, solar radiation, wind velocity and direction, plants and building characteristics. the green facade was described by a schematic representation, four layers were defined: the green layer, the external surface of the building wall, the internal surface of the building wall, the air inside the building. the energy balance was defined for each layer and all the terms involved in the energy exchange between the layers were defined as a function of the plant, the weather conditions and the constructive characteristics of the wall
Indoor vertical greening for regulating building microclimate
No full textThe integration of vegetation in buildings can increase the environmental sustainability of urban
contexts as well as produce other relevant unquantifiable effects. Vegetation can be applied both on the
exterior side of the buildings’ envelope and inside, in different ways and layouts. Green façades are a
specific kind of vertical greening for buildings consisting of plants covering vertical walls of buildings. The
presence of vegetation on the envelope positively affects the building’s thermal and acoustic performance,
air quality, aesthetics, with relevant consequences in terms of energy and cost savings and human wellbeing. Until now, research has focused mainly on vertical greening systems applied to the exterior side of
the buildings, but indoor applications deserve attention as well. This is the reason behind the present
research: assessing the physical functioning of an indoor green façade. To this end, an experimental
prototype of an indoor greening system was designed and realized to be monitored, at the University of
Bari. The prototype consists of a sealed chamber, with evergreen plants, properly equipped with sensors for
collecting air, soil and plant parameters, needed for studying the system functioning. The database created
with the collected data enables investigations of the green façade behaviour and effects. A better
understanding of this green technology, allowing for informed design and knowledge of induced effects,
can promote the spread of indoor green façades
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