Search results for "SHADING"
showing 10 items of 34 documents
Reconfigurable electrical interconnection strategies for photovoltaic arrays: A review
2014
Non-uniform irradiance significantly decreases the power delivered by solar photovoltaic arrays. A promising technique for compensating these power losses relies on dynamically reconfiguring the electrical connections between photovoltaic modules. This paper presents the current state-of-the-art strategies for photovoltaic array reconfiguration in order to increase the power output under partial shading and mismatch conditions. The different approaches have been compared in terms of effectiveness of the control algorithms, monitored electrical and environmental variables, overall hardware complexity and specific features of each solution. Finally, the most challenging aspects of the reconfi…
Absence of Sex Differential Plasticity to Light Availability during Seed Maturation in Geranium sylvaticum
2015
Sex-differential plasticity (SDP) hypothesis suggests that since hermaphrodites gain fitness through both pollen and seed production they may have evolved a higher degree of plasticity in their reproductive strategy compared to females which achieve fitness only through seed production. SDP may explain the difference in seed production observed between sexes in gynodioecious species in response to resource (nutrients or water) availability. In harsh environments, hermaphrodites decrease seed production whereas females keep it relatively similar regardless of the environmental conditions. Light availability can be also a limiting resource and thus could theoretically affect differently femal…
Façade Solar Control and Shading Strategies for Buildings in the Mediterranean Region
2020
With the pressing need for holistic solutions that can help in overcoming the imminent environmental and resources crises, a call for the conservation of natural resources and sustainable strategies is needed. Sustainable strategies allow for the mitigation against the impact of climate change on the environment while, simultaneously, seeking the health and comfort of users. Another environmental issue that is worthy of the attention of the scientific research community is the reduction of resources consumption, through the implementation of sustainable development concepts and the use of renewable sources of energy generation. These two aforementioned paradigms are both intrinsic in nature…
Acclimation Potential to High Irradiance of Two Cultivars of Watermelon
2000
The acclimation potential to high irradiance of two cultivars of watermelon, Reina de Corazones and Toro, calculated as the ratio of sun vs. shade activities of O2− and H2O2 scavenging enzymes and non-radiative energy dissipation, was similar. However, Reina de Corazones exhibited a higher capacity in absolute terms for photoprotection (harmless dissipation of absorbed light energy at PS 2 and ascorbate and O2− and H2O2 scavenging enzymes) suggesting a larger resistance of this cultivar to high irradiance. This could be seen as smaller decreases in fruit productivity and in lower oxidative injury as probed by malondialdehyde content in sun plants of Reina de Corazones than in Toro plants. A…
Temperature Inversion Breakup with Impacts on Air Quality in Urban Valleys Influenced by Topographic Shading
2015
AbstractUrban valleys can experience serious air pollution problems as a combined result of their limited ventilation and the high emission of pollutants from the urban areas. Idealized simulations were analyzed to elucidate the breakup of an inversion layer in urban valleys subject to a strong low-level temperature inversion and topographic effects on surface heating such as topographic shading, as well as the associated air pollution transport mechanisms. The results indicate that the presence and evolution in time of the inversion layer and its interplay with an urban heat island within the valley strongly influence the venting of pollutants out of urban valleys. Three mechanisms of air …
EFFECTS OF LIGHT REDUCTION AT BLOOM ON FRUITS SET IN BLACK MAGIC TABLE GRAPES CV IN EARLY AND LATE PRODUCTION CICLES
2013
A shading experiment in ‘Black Magic’ cv was conducted in Sicily to test a new thinning method, aiming to reduce the no. berries/cluster, maximising quality and value of the production. A reduction of intercepted light was imposed at the 65 stage of the BBCH scale (50% cap fall) for 12 days. The soilless greenhouse conditions allowed two growing cycles occurring under different climate conditions, an early (end of March flowering) and a late production cycle (beginning of August flowering). During the shade treatment, net photosynthetic rate was significantly reduced by 82% and 96% in the late and early production cycles, respectively. The sum of flowers and berries dropped in the untreated…
Vegetative and reproductive behavior of 'conference' and 'williams' pear trees trained to v-shape system
2007
V-shape systems represent an efficient and popular option to increase yields and fruit quality. Here we present a detailed study on canopy and root system growth and conformation, yields, fruit quality and dry matter partitioning of 'Conference' (C) and 'Williams' (W) pear trees trained to V-shape system. Digital images were used to determine total stem and root length, mean diameter and surface area; canopy and root system spread area, shape index and volume, canopy height and root depth. Dry weights were used to calculate dry matter partitioning. Stems of W trees were longer and thinner than those of C, which resulted in similar stem dry weights for the two cultivars, whereas root dry wei…
An improved photographic method to estimate the shading effect of obstructions
2012
Abstract A new photographic method is presented to evaluate the shading effects of obstructions on surfaces exposed to the sun. The method overcomes the difficulties caused by the need to accurately describe the surrounding objects to estimate the shading effects by means of the usual tools that use the spatial reconstruction of obstructions or cylindrical or polar suncharts. The photographs of the surrounding objects are used as the background on which the solar disc is depicted at the various hours of the day. In this way it is easily detectable if the sun is visible from the place where the photographs were taken or if the surrounding obstructions obscure the sun. In spite of the complex…
A photographic method to estimate the shading effect of obstructions
2012
Abstract A new, simplified photographic method is proposed to estimate the shading effects of obstructions. In spite of the complex mathematical background of the new tool, its practical application is very simple, and only requires the measurements of three angles for each photograph. The proposed method is particularly useful for overcoming the difficulties caused by the need to accurately describe surrounding objects to estimate shading effects. The new method uses the information contained in a picture and allows one to draw daily solar paths directly on the photograph. The procedure is useful to verify the suitability of a generic site for solar exploitation; its main benefit is the si…