Impact Of Shading Research Articles

An Experimental Evaluation of Dock Shading Impacts on Salt Marsh Vegetation in a New England Estuary

Docks constructed over salt marsh can reduce vegetation production and associated ecosystem services. In Massachusetts, there is a 1:1 height-to-width ratio (H:W) dock design guideline to reduce such impacts, but this guideline’s efficacy is largely untested. To evaluate dock height effects on underlying marsh vegetation and light availability, we deployed 1.2-m-wide experimental docks set at three different heights (low (0.5:1 H:W), intermediate (1:1 H:W), and high (1.5:1 H:W)) in the high and low marsh zones in an estuary in Massachusetts, USA. We measured temperature, light, vegetation community composition, and stem characteristics under the docks and in unshaded control plots over three consecutive growing seasons. Temperature and light were lower under all docks compared with controls; both increased with dock height. Maximum stem height and nitrogen content decreased with available light. In the Spartina patens-dominated high marsh, stem density and biomass were significantly lower than controls under low and intermediate but not high docks. Spartina alterniflora, the dominant low marsh vegetation, expanded into the high marsh zone under docks. S. alterniflora aboveground biomass significantly differed among all treatments in the low marsh, while stem density was significantly reduced for low and intermediate docks relative to controls. Permit conditions and guidelines based on dock height can reduce dock impacts, but under the current guideline of 1:1 H:W, docks will still cause significant adverse impacts to vegetation. Such impacts may interfere with self-maintenance processes (by decreasing sediment capture) and make these marshes less resilient to other stressors (e.g., climate change).

Experimental investigation of the effect of partial shading on photovoltaic performance

Partial shading of a photovoltaic (PV) installation has an inconsistent impact on power production. This study investigates the effect of partial shading on PV performance. The experiments were carried out with a 90-W PV module under both variable and constant irradiations with shaded area increased from 0 to 80% to observe the effect of variable solar radiation at certain shading points. The effect of shading under irradiation levels from 300 to 800 W/m2 was investigated. At a 600 W/m2 irradiation level, the shading impact factor was 1.25 with a 25% shading, while at 75% shading the impact factor decreased to 0.86. Results also show that for every 100 W/m2 increase in irradiation level, the electrical power output was enhanced by 3.89, 3.37, 2.27, and 2.02 W at 0, 25, 50, and 75% shading, respectively. The efficiency level was increased by 0.29, 0.27, 0.25, and 0.22% at 0, 25, 50, and 75% shading, respectively. Increasing the shaded area by 10% causes a 12.41 W drop in power output and a 2.3% drop in electrical efficiency. Partial shading not only deteriorates the PV performance, but also causes long-term degradation of the module.

Impact of decade-long warming, nutrient addition and shading on emission and carbon isotopic composition of CO2 from two subarctic dwarf shrub heaths

This study investigated ecosystem respiration, soil respiration and carbon isotopic composition in CO2 emitted from two subarctic shrub heaths with contrasting moisture regimes. The reported measurements were conducted 22 years (mesic heath) and 12 years (wet heath) upon initiation of in situ climate change related manipulations of temperature, nutrient availability and light.The aim was to quantify expected climatic change effects on soil and ecosystem respiration, and to investigate whether the emitted CO2 originates from old carbon stores in the soil or from newly fixed carbon. Ecosystem and soil respiration was measured using closed chambers and CO2 in the soil profile was sampled with gas probes installed at different depths.At the mesic heath ecosystem respiration was increased 46% by warming while soil respiration increased 133% by nutrient addition. At the wet heath, warming increased ecosystem respiration by 99% and soil respiration by 58%. Litter addition, short time warming and shading generally did not change ecosystem- and soil respiration.The carbon isotope compositions of the sources to CO2 were not significantly altered by any of the treatments at the two heaths across the growing season. However, there was a tendency across growing season towards an increased δ13C source value after 22 years of warming in the mesic shrub heath, and the effect was statistically significant in June, indicating increased decomposition of 13C enriched material. Hence, although more of the old carbon stock in the soil was possibly mineralized under warmed conditions, indicating a risk of long lasting positive feedback on climate warming, the effect was only periodically strong enough to gain statistical significance, despite strong warming-induced effect on ecosystem respiration, and may be counteracted by increased C gain by higher primary production.

Repertoire of traits in the sapling of a dwarf Mediterranean shrub confers withstanding the combined stress of drought and shade

ABSTRACTThe ability to cope with combinations of stresses is crucial for the establishment and development of young plants and determines processes of population dynamics. Seedlings and saplings of Mediterranean woody species in woody ecosystems often experience both drought and shade stresses. Our study aims at understanding the effect of the combined stresses of drought and shade on young sapling survival and development. We tested three alternative hypotheses: (1) Drought decreases plant performance in shade. (2) The impact of drought is lessened in shade or shade may even ameliorate plant performance under drought. (3) Plant response to shade is independent of plant response to water availability. The first and second hypotheses imply an interaction between drought and shade, while the third implies an orthogonal impact of drought and shade. We also ask what are the functional morphological traits that are involved in tolerating shade and drought stresses. We tested the hypotheses and questions focusing on Sarcopoterium spinosum as a model species in a fully factorial container experiment with three shading levels and two levels of water availability. The results demonstrate that moderate shading (50%) ameliorates seedling performance (measured by final biomass) under dry conditions. In contrast, when water was available, shading had a monotonic negative effect on seedling performance. Conversely, shade and drought had an independent effect on biomass partitioning and under drought – allocation to roots increased, while under shade allocation to leaves increased. The dry conditions did not cause a reduction in shade tolerance, and both shade avoidance and tolerance morphology were evidenced under moderate (50%) and deep (70%) shading (stem elongation, increased leaf area). Deep rooting – a drought-avoidance trait – was similar in high and low water availability. Our overall results support the hypothesis that shade ameliorates drought stress. Moreover, S. spinosum demonstrates that woody species inhabiting water-limited ecosystems may have a repertoire of traits that allows simultaneous tolerance to both drought and shade.

Measured and estimated performance of a fleet of shaded photovoltaic systems with string and module‐level inverters

AbstractShade obstructions can significantly impact the performance of photovoltaic (PV) systems. Although there are many models for partially shaded PV arrays, there is a lack of information available regarding their accuracy and uncertainty when compared with actual field performance. This work assesses the recorded performance of 46 residential PV systems, equipped with either string‐level or module‐level inverters, under a variety of shading conditions. We compare their energy production data to annual PV performance predictions, with a focus on the practical models developed here for National Renewable Energy Laboratory's system advisor model software. This includes assessment of shade extent on each PV system by using traditional onsite surveys and newer 3D obstruction modelling. The electrical impact of shade is modelled by either a nonlinear performance model or assumption of linear impact with shade extent, depending on the inverter type. When applied to the fleet of residential PV systems, performance is predicted with median annual bias errors of 2.5% or less, for systems with up to 20% estimated shading loss. The partial shade models are not found to add appreciable uncertainty to annual predictions of energy production for this fleet of systems but do introduce a monthly root‐mean‐square error of approximately 4%–9% due to seasonal effects. Use of a detailed 3D model results in similar or improved accuracy over site survey methods, indicating that, with proper description of shade obstructions, modelling of partially shaded PV arrays can be done completely remotely, potentially saving time and cost. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Influence of orientation and the impact of external window shading on building thermal performance in tropical climate

Energy saving in buildings is a high-priority in developed countries as buildings are responsible for a substantial part of the energy consumption. Typically heating, cooling and artificial ventilation systems of a building are major consumer of energy. A validated Fortran 77 compiler program has been used to elaborate the influence of building orientation on building energy consumption. The amount of heat influx through windows on different oriented vertical walls for various direction has been compared and it has been found that heat gain through south oriented windows is maximum followed by East, West and North bound windows in a tropical climate of northern hemisphere. An experimentally designed, Programmable Logic Controller based movable exterior window shading device linked with sun path has been introduced through a validated TRNSYS building model to show the reduction in cooling load of a hospital building in tropical climate. The simulation study shows that maximum energy savings can be achieved in the month of June i.e. 14.9% and average energy savings is 9.8% annually by movable exterior window shading for a building in tropical climate. Through an economic analysis it has been established that the proposed exterior shading device is financially viable and the payback comes within 6 months. This study is useful for professionals who are responsible for decision-making during the design phase of energy-efficient buildings and can show a path for sustainable building design.

Impact of background on color, transmittance, and fluorescence of leucite based ceramics.

This study evaluated the impact of tooth shade on differences in color (∆E), lightness (∆L), chromaticity coordinates a*/b* (∆a and ∆b), transmittance and the degree of fluorescence of CAD/CAM leucite based ceramic (LBC). Ten disks were fabricated of LBC; Empress CAD, A2, thickness of 1.5 mm and eight disks of resin-nano-ceramic (RNC; Lava Ultimate) in different colors to simulate variations in substrate shade. The associations of LBC disks with different color substrates were analyzed with a spectrophotometer; ∆E, ∆L*, ∆a*, ∆b*, and transmittance were measured and calculated. Fluorescence was evaluated with a fluorescence system (Fluorescence System, Biopdi). All substrate shades influenced the optical properties of LBC, with regard to color, luminosity, coordinate a* and b*, transmittance, and fluorescence (p<0.001). Substrate colors with high saturation (A3.5 and C2) presented highest impact, whereas colors with lowest saturations (BL, B1) showed less impact. Substrate color influenced the optical properties of ceramic restorations.

Evaluating a New Shade for Feedlot Cattle Performance and Heat Stress

Abstract. Heat stress in cattle results in decreased feed intake, lower daily gain, and potentially death in susceptible animals under intense conditions. A study was carried out during the summer of 2013 at the USDA-ARS U.S. Meat Animal Research Center feedlot evaluating the impact of shade on environmental conditions and cattle performance. A novel two-tiered shade was used in half of the 14 pens, each holding 30 animals. The shades were designed to reduce solar heat load by 40% to 60% and to provide traveling shade across the pen, providing varied amounts of shade area as well as varied solar reduction potential. The objective of this study was to determine if the shade was effective at improving performance (evaluated as average daily gain, feed intake, and feed to gain ratio) and reducing environmental conditions that cause heat stress. A group of mixed-breed cattle with varied genetics including both and were selected, penned on the basis of sex, and blocked by color. Production parameters of pen feed usage were measured daily, and individual body weights were taken monthly. Environmental conditions including air temperature, relative humidity, wind speed, ground temperature, and black globe temperature with and without shade were measured. Solar load on the pens was reduced when shade was provided, with both ground temperature and black globe temperature showing reductions. Cattle showed nominally better performance; however, no significant differences were found in gain or feed intake. Panting scores were significantly lower with shade provided; slopes of cattle respiration rate versus ambient temperature were significantly lower with shade during the afternoon period. Keywords: Cattle, Feedlot, Heat stress, Respiration, Shade.

Impact of External Shading on Light Comfort and Energy Efficiency in Apartment Buildings

The paper is focused on an example of volume solution of a superstructure designed within allowable legislative limits and its impact on light comfort in shaded flats. It deals with issues such as : optimizing allowable amount of external shade in relation to sustainable hygienic quality of residential environment, an impact of superstructure ́s shade on insolation time in affected flats and consequently on passive solar gain intensity of apartment buildings, as well as evaluation of energy efficiency of infill walls in compensating of their heat loss in heating period, depending on the amount of external shading, their orientation, and thermo-insulation quality in all model scenarios - current, legislatively allowable, and optimized. It solves compatibility of optimized shading in terms of hygienic quality in relation to the increased efficiency of solar gains utilization to cover heat loss by heat-exchange shell in contemporary and prospective low-energy buildings.

Impact of shading on a flat CPV system for façade integration

Recently adopted energy efficiency policies in the EU induce a movement towards energy-neutral buildings. Building integrated photovoltaics technology connects with this ambition, as aside from the generation of electrical energy, it allows additional benefits such as heat generation, or daylight regulation by transmission of diffuse sunlight through transparent parts of the system. In this study three Concentrator Photovoltaic (CPV) system configurations that allow for the construction of semi-transparent building façade elements are investigated outdoor. The systems are a Fresnel lens based concentrator, a novel flat planar optic concentrator, and a 4×4 panel of these flat optics. The flat optic has no air cavity to account for optical focal depth which is highly beneficial when incorporated in a window. In particular the energy production of the systems when partially shaded is investigated, as adjoining systems will move behind one another during sun tracking, because the optics spacing must be small to achieve good daylight regulation. The planar optic concentrator is found to display similar performance as a Fresnel lens based concentrator of similar concentration. For a multi-receiver panel, shading introduces a loss of performance ranging from 7% to 12% which is attributed to electrical interconnection as individual receivers do not suffer this loss.

The impact of a shade from the growth and the results of two varieties soybean ( glycine max l .Merrill ) superior nationa

Abstract. Soybean needs national until now as still filled with than the import value that production in the country not enough. In solve the problems the low rate production soybean required production techniques of technology and awareness nice about the cultivation of plants soybean , the expansion of the increase , fix the quality , the environment and the use of varieties superior. Efforts to improving production soybean bounded by the limited by land ownership because some rice-fields productive have changed to a non farming. Behind the limited resources land for the expansion of the acreage of a farm, there are land potential to to use, namely land under kanofi plantation crops. The purpose of this study is to find the impact of shade and varieties and interaction between them to growth and the production of the soybean plant. Design experiments used in this research is a swath separate ( RPT) with two factors treatment. The research results show that treatment shade very had have real impact on some parameters that observed , on the parameter tall plant , diameter of the stem , flowering age , age harvest , the number of pods total , the number of pods pithy , heavy seeds 100 points and potential the results , the best result in find in treatment nuangan 60 % . Varieties influential very real to pertumbuhandan production the soybean plant, based on the results of observation tall plant, diameter of the stem, flowering age, the use of varieties anjasmoro showed growth and best in compared with varieties ringing. There are the interaction that very real between shade and varietas.kombinasi that tends to both in find in varieties anjasmoro but shade 60 %

Shading impacts by coastal infrastructure on biological communities from subtropical rocky shores

Summary Artificial shading has been highlighted as an important human disturbance, affecting both productivity and community organization. However, studies of shading have been poorly explored from an environmental impact perspective. We compared community structure on subtropical rocky shores in areas shaded by human constructions with those in unshaded areas. We then implemented a manipulative field experiment to determine the effects of shading on the macrobenthic community, biofilm biomass and larval recruitment. Shading consistently affected the biological community of rocky shores. The biomass and cover of macroalgae and the size of most sedentary grazers were smaller in shaded habitat. In the infralittoral fringe, we recorded a shift in dominance from macroalgae in unshaded habitats to invertebrate filter feeders in shaded ones. In a similar way, the community from the mesolittoral was also affected by shading but not at all locations. Experimental manipulation of shading led to a total loss of macroalgae from the infralittoral fringe and no community replacement over a period of 220 days. In the mesolittoral, oysters became more abundant in shaded conditions, while barnacles decreased in abundance. Larval recruitment was also affected, with oysters and barnacles recruiting more in shaded habitats. Synthesis and applications. We demonstrate a clear impact of shading by artificial human‐made structures on patterns and processes regulating biodiversity on rocky shores and thus consequences for coastal ecosystem functioning. We argue that shading by artificial coastal structures, such as those proposed in the port expansion in our study site in south‐eastern Brazil, is potentially underestimated. Our work emphasizes the importance of careful evaluations of artificial structures in order to promote sustainable coastal development. As a result, we do not recommend the proposed expansion by suspended structures of the port of São Sebastião, as the consequent shading will negatively affect the biodiversity and ecosystem functioning of the Araçá Bay and surrounding areas.

Application of shade treatments during Shiraz berry ripening to reduce the impact of high temperature

Background and Aims The impact of high temperature on grapevine function is predicted to be a serious problem in our warming climate. We studied the impact of shading on some aspects of vine physiology, berry cell death and other components of berry development and on the resultant wines in order to understand grapevine physiology and the ripening process in shaded conditions and to assess shading as a mitigation strategy for high temperature. Methods and Results Several shading treatments on Shiraz vines were imposed from veraison to harvest during three seasons at two locations. An overhead shade (OS) treatment (62% absorption) was the most consistent in high temperature mitigation. Compared with controls (no shading) or to soil shade, the leaves of OS vines had higher chlorophyll concentration, higher net CO2 assimilation at saturating light, and higher midday stem water potential but similar sap flow and leaf transpiration rates. Overhead shade berries accumulated sugars per berry at a similar rate but had lower TSS due to higher water content. Berry cell vitality measured with impedance or vital stains was higher in OS vines, and mass loss was delayed. Wines had lower alcohol with no significant difference in the concentration of anthocyanins; however, phenolic substances and some of the colour properties were affected. Conclusion Overhead shade can ameliorate the impact of heat stress through a significant reduction in berry cell death and in loss of berry mass. This results in reduced alcohol concentration with relatively minor effects on other wine components. Significance of Study Shading from veraison to harvest may be a viable mitigation strategy against extreme high temperature during ripening.

Impact of Ag Pads on the Series Resistance of PERC Solar Cells

Screen-printed passivated emitter and rear cells (PERC) require Ag pads on the rear side to enable solderable connections for module integration. These Ag pads are separated from the silicon by a dielectric layer to avoid recombination of minority charge carriers. The drawback of this configuration is an elongated transport path for the majority charge carriers generated above the pads. This results in an increase in series resistance. The strength of this effect depends on charge carrier generation above the Ag pads that critically depends on shading of the cell's front side. Ag pads are usually wider than the busbars or the interconnector ribbons and thus are only partially shaded. We build PERC test structures with various rear side configurations of Ag and Al screen printing as well as with and without laser contact openings (LCO). Using experiments and finite element simulations we investigate the impact of shading the Ag pads by the busbars and other means. While fully shaded regions do not increase the lumped solar cell's series resistance, unshaded Ag pads lead to an increase of about 37%.

Impact of Manually Controlled Solar Shades on Indoor Visual Comfort

Daylight plays a significant role in sustainable building design. The purpose of this paper was to investigate the impact of manual solar shades on indoor visual comfort. A developed stochastic model for manual solar shades was modeled in Building Controls Virtual Test Bed, which was coupled with EnergyPlus for co-simulation. Movable solar shades were compared with two unshaded windows. Results show that movable solar shades have more than half of the working hours with a comfortable illuminance level, which is about twice higher than low-e windows, with a less significant daylight illuminance fluctuation. For glare protection, movable solar shades increase comfortable visual conditions by about 20% compared to low-e windows. Moreover, the intolerable glare perception could be reduced by more than 20% for movable solar shades.

Arbuscular mycorrhizal fungal communities in buffelgrass pasture under intercropping and shading systems in Brazilian semiarid conditions

The intercropping of grasses and legumes has been suggested as an alternative for ensuring pasture sustainability. However, few studies have focused on the impact of intercropping and shading on the soil microbiota in semi-arid regions. The goal of this study was to evaluate the effects of intercropping a grass, Cenchrus ciliaris, with a legume, Clitoria ternatea, under different levels of shading, on the C. ciliaris carbohydrate concentration and the arbuscular mycorrhizal fungal (AMF) community over time. Soil samples were collected at four sampling times: before intercropping (BI) and after 120, 165 and 210days cultivation. Four levels of shading were tested: 0 (full sunlight), 26, 39 and 55%. In the intercropped system, mycorrhizal colonization was higher under lower shading levels after 120 and 165days cultivation, but the number of glomerospores was higher under higher shading levels. After 165days cultivation, the carbohydrate concentrations were higher under full sunlight. After 210days cultivation, the reducing carbohydrate concentrations were higher in the intercropped system. Thirty-one AMF species were detected; Acaulospora and Glomus species were predominant compared with the remaining genera. This study showed that AMF community composition was relatively similar between shading and intercropping by multidimensional scaling (MDS) and PERMANOVA analysis, and it was observed only sampling time effect on the AMF community. The Shannon diversity index showed a reduction in AMF diversity from 210days of cultivation and an increase in the AMF species richness over time. It was concluded that pastures of C. ciliaris under shading and intercropping with C. ternatea did not modify the AMF community composition. However, the results suggest that intercropping of these plant species may result in AMF species selection over time.

Visible spectroscopy IADmeasures in apple: impact of stress and shading on maturity indexing

Visible spectroscopy I_ADmeasures in apple: impact of stress and shading on maturity indexing

Impact of shade on outdoor thermal comfort-a seasonal field study in Tempe, Arizona.

Shade plays an important role in designing pedestrian-friendly outdoor spaces in hot desert cities. This study investigates the impact of photovoltaic canopy shade and tree shade on thermal comfort through meteorological observations and field surveys at a pedestrian mall on Arizona State University’s Tempe campus. During the course of 1 year, on selected clear calm days representative of each season, we conducted hourly meteorological transects from 7:00 a.m. to 6:00 p.m. and surveyed 1284 people about their thermal perception, comfort, and preferences. Shade lowered thermal sensation votes by approximately 1 point on a semantic differential 9-point scale, increasing thermal comfort in all seasons except winter. Shade type (tree or solar canopy) did not significantly impact perceived comfort, suggesting that artificial and natural shades are equally efficient in hot dry climates. Globe temperature explained 51 % of the variance in thermal sensation votes and was the only statistically significant meteorological predictor. Important non-meteorological factors included adaptation, thermal comfort vote, thermal preference, gender, season, and time of day. A regression of subjective thermal sensation on physiological equivalent temperature yielded a neutral temperature of 28.6 °C. The acceptable comfort range was 19.1 °C–38.1 °C with a preferred temperature of 20.8 °C. Respondents exposed to above neutral temperature felt more comfortable if they had been in air-conditioning 5 min prior to the survey, indicating a lagged response to outdoor conditions. Our study highlights the importance of active solar access management in hot urban areas to reduce thermal stress.Electronic supplementary materialThe online version of this article (doi:10.1007/s00484-016-1172-5) contains supplementary material, which is available to authorized users.

Investigation of damage caused by partial shading of CuInxGa(1-x)Se2photovoltaic modules with bypass diodes

This study evaluated the impact of partial shading on CuInxGa(1-x)Se2 (CIGS) photovoltaic (PV) modules equipped with bypass diodes. When the CIGS PV modules were partially shaded, they were subjected to partial reverse bias, leading to the formation of hotspots and a possible occurrence of junction damage. In a module with a cadmium sulfide buffer layer, hotspots and wormlike defects were formed. The hotspots were formed as soon as the modules were shaded; the hotspots caused permanent damage (wormlike defects) in the CIGS module. Specifically, the wormlike defects were caused by the window layer, leading to increased recombination and decay of the solar cell properties. However, a CIGS module with a zinc sulfide buffer layer did not exhibit the formation of hotspots or any visual damage. The reverse bias breakdown voltage of the CIGS PV module with the cadmium sulfide buffer layer was higher than that of the CIGS PV module with the zinc sulfide buffer layer. Copyright © 2016 John Wiley & Sons, Ltd.

樹木モデルを用いた植物個体光合成量の計算手法

A method for computing photosynthesis rate of a tree using realistic plant models, AMAP, is discussed in this paper. Photosynthetic rate calculation is an important factor to estimate the growth rate of plants and landscape dynamics in green spaces. However, photosynthesis of plants is difficult to compute because of plants' complex three-dimensional structures composed of leaves, branches and trunks. Complicated structure makes it hard to quantify irradiation intensity caught by each leaf, which is a major factor to define photosynthetic rate. On another front, simulation models which recreate a plant structure inside computer make progress. This enables simulating light acquisition of leaves by ray-tracing methods. Accordingly we compute photosynthesis rate in a sunny summer day using AMAP plant models. The results show that photon weight for ray-tracing greatly influence the amount of photosynthesis rate, and should be set carefully according to target scale. And these calculations suggest that an impact of light shading by branches is slightly large. This method can be applied to a simulation of plants dynamics, for example. And such a simulation will be expected to offer new insights of the landscape managements.