Transmission Of Solar Radiation Research Articles

Agroforestry systems and understory harvest management: the impact on growth and productivity of dual-purpose wheat.

The objective of the study was to evaluate the growth and production efficiency of forage-grain dual-purpose wheat in two arrangements and four agroforestry systems (Intercrop-I and Intercrop-II), as well as to evaluate crop management for the wheat crops in two planting seasons (Crop Season I-2014 and Crop Season II-2015. The experiment was conducted in a randomized complete block design, factorial scheme 7x2x2, with seven cultivation systems Eucalyptus urophylla x Eucalyptus grandis Intercrop-II and Intercrop-I; Peltophorum dubium Intercrop-II and Intercrop-I; P. rigida Intercrop-I; S. parahyba Intercrop-I; a wheat monoculture with no tree species present; and two harvest management techniques (with and without harvesting of the forage species). Agroforestry systems generated shading for wheat plants, with a higher phyllochron and lower values of leaf area index of those individuals kept under trees with higher crown shading (non-deciduous trees) due to the lower transmissivity of solar radiation. The systems composed with Schizolobium parahyba in Intercrop-I and Parapiptadenia rigida in Intercrop-I provide a minor phyllochron to the wheat, resulting in a higher leaf area index and dry matter yield. Thus, the cultivation of tree species and dual-skilled agricultural crops, such as wheat, provides promising alternatives for the future use of land in tropical countries.

Ефективність передачі сонячного випромінювання на відстань по волоконно-оптичним кабелям

Ефективність передачі сонячного випромінювання на відстань по волоконно-оптичним кабелям

Ефективність передачі сонячного випромінювання на відстань по волоконно-оптичним кабелям

Ефективність передачі сонячного випромінювання на відстань по волоконно-оптичним кабелям

Animal thermal comfort indexes in silvopastoral systems with different tree arrangements

This study aimed to assess solar radiation transmission and animal thermal comfort indexes in two silvopastoral systems established with different tree arrangements in a tropical region. This study was conducted between 2014 and 2017 in two silvopastoral systems, one composed by an established Urochloa (syn. Brachiaria) decumbens pasture with Brazilian native trees planted in triple rows spaced 17 m apart, and another by an established Urochloa (syn. Brachiaria) brizantha (Hochst ex A. Rich.) Stapf ‘BRS Piatã’ pasture with Eucalyptus urograndis (clone GG100) trees arranged in single rows spaced 15 m apart. In these systems and in a full-sun pasture, photosynthetically active radiation transmission, air temperature, relative humidity, black globe temperature, and wind speed were measured. These variables were used to calculate black globe temperature and humidity index (BGHI) and radiant thermal load (RTL). Higher animal thermal comfort was observed in the silvopastoral systems due to changes in the microclimate induced by the trees; notably, a decrease in solar radiation transmission. Fewer hours of potential animal thermal stress (BGHI>79) were observed in the silvopastoral systems than under the full-sun conditions, with differences up to 3 h per day. The silvopastoral systems presented lower radiant thermal load than the full-sun pasture with differences up to 22% achieved. The assessed silvopastoral systems may help livestock adapt to climate change, since they achieved the limit of BGHI considered to cause stress to animals following an increase of 2.2 °C in air temperature, compared with full-sun pastures.

Transmission of Solar Radiation by Semicylindrical and Segmented Transparent Protections

Transparent protection (TP) is one of the basic elements of low-potential solar installations. The problem of determining the flux coefficients that allow one to calculate the solar flux entering through the TP is considered. An algorithm and program are developed for determining the flux coefficients for film semicylindrical and segmented TP. It is shown that the meridional orientation of a semicylindrical TP is more efficient than latitudinal, while for a segmented TP, the latitudinal orientation is more favorable.

Dynamics of solar radiation and soybean yield in agroforestry systems

Soybean (Glycine max L.) monocropping have had a great socio-economic and environmental impact on the world and agroforestry systems has been considered an alternative for more sustainable production. The aim of this study was to evaluate the effect of different arrangements of agroforestry systems of the species E. urophylla x E. grandis and P. dubium and the pruning of the trees on the dynamics of solar radiation and soybean yield. A field experiment was conducted in Southern Brazil. In order to achieve the objective of the study, the solar radiation transmissivity and the productive performance of the soybean were evaluated. In this study, the soybean yield was determined by the arrangement of the agroforestry system and forest species utilized. The soybean crop cultivated in the understory of the P. dubium trees showed the highest yield response. The use of silvicultural practices for the management of forest species should be considered to generate the balance of the productive system. In this context, tree pruning is a viable side for agroforestry systems, as it promotes an increase in the incidence of solar radiation in the understory, resulting in an increase in soybean yield, especially when integrated with P. dubium.

Cs0.33WO3 as a high-performance transparent solar radiation shielding material for windows

The optical properties of Cs0.33WO3 were analyzed based on experimental results reported in the literature. Its potential for use as a transparent energy-saving filter was evaluated using theoretical optical results. The results showed that Cs0.33WO3 exhibits excellent near-infrared radiation reflectance/absorption and high transmissivity of visible light, so it is ideal for use as a solar radiative filter for windows. In addition, Cs0.33WO3 provides perfect solar radiation shielding, suggesting that this material could be applied for compacted filters and nanoparticle-dispersed coatings. Two types of Cs0.33WO3 filters exhibited more than 80% transmissivity of visible light and excellent solar radiation shielding performance. This research work indicates that the doping of the Cs ion into hex-WO3 induces a persistent n-type electronic conductivity with metal-like characteristics and dramatically enhances near-infrared radiation absorption while maintaining excellent visible light transparency.

Atmospheric Transmission of Ultraviolet and Total Solar Radiation by Clouds, Aerosols, and Ozone in Seoul, Korea: a Comparison of Semi-Empirical Model Predictions with Observations

This study examines the semi-empirical models to evaluate the atmospheric broadband transmission of erythemally weighted ultraviolet (EUV), total ultraviolet (TUV), and global solar radiation (GS) by clouds, aerosols, and ozone in Seoul, Korea (37.57°N, 128.98°E). Climatological values of surface solar irradiance (SSI) for Seoul are briefly summarized, and atmospheric transmission is defined as the ratio of measured SSI to clear-sky irradiance calculated using harmonic analysis. Three multiple linear regression models are developed for the EUV, TUV, and GS spectral bands for all-sky (clear and cloudy conditions) transmission using three independent variables: cloud-cover amount, aerosol optical depth, and total ozone. The modeled total transmissions are 75%, 71%, and 67% for the EUV, TUV, and GS spectral bands, respectively, which are slightly overestimated than the measured values. The modeled annual mean clearness index, KT, is 1%, 45%, and 48% for the three spectral bands, respectively. Four semi-empirical models were developed to calculate transmission and were evaluated. Among the various empirical models, estimates from the exponential models were found to be the closest to measured values, having the lowest mean bias error (−0.3% to −2.4%) and highest explained variance (R2 = 0.17 to 0.50; p = 0.000), as was expected from their theoretical bases. The annual average transmissions of cloud, aerosol, ozone, and all three combined show decrease from the EUV to the TUV and GS bands.

Agroforestry systems and their effects on the dynamics of solar radiation and soybean yield

Agroforestry systems have been highlighted in the agricultural environment as an alternative form of sustainable production to meet the growing demand for food and energy with less environmental impact. Thus, the aim of this study was to evaluate the effect of different forest species on the dynamics of solar radiation and the productive response of soybean grown in agroforestry systems. Two field experiments were carried out in the city of Frederico Westphalen - Rio Grande do Sul, Brazil. In order to reach the aim of this study, the solar radiation transmissivity and the productive performance of soybean were evaluated. Productivity followed the same tendency as solar radiation transmissivity; in an agricultural year, the species with the higher incidence of solar radiation to the understory presented the best yield. The forest species Schizolobium parayba, Peltophorum dubium and Parapiptadenia rigida were used as they present the potential to compose the agroforestry systems; their canopy structure and leaf architecture provide greater availability of solar radiation in the subforest. The interception of solar radiation by the forest component of more than 50% significantly reduces soybean yield in agroforestry systems, requiring silvicultural practices that promote the availability of solar radiation in the understory.

Albedo Trend Analyses in Atlantic Forest Biome Areas

The albedo is an important variable that controls the balance of radiation and energy of the atmosphere, so changes in land cover cause alterations in albedo values, influencing changes in climate behavior at different scales. The goal in this work was to investigate the possible occurrence and causes associated with surface albedo trends within the Atlantic Forest biome (São Francisco de Paula, state of Rio Grande do Sul, Brazil), during the last thirty years (1987-2017), evaluating the impacts of the forest cover structure on albedo trends. The study included images of the TM/Landsat 5 and OLI/Landsat 8 sensors over the period 1987 to 2017. The surface albedo was obtained from the SEBAL algorithm, which includes in its variables the reflectance values of each band, reflected solar radiation and atmospheric transmissivity. The trend analysis was performed by the Mann-Kendall test verifying the existence of significant trends over 30 years. Subsequently, the influence of vegetation greenness on the trend presented by the albedo surface was evaluated. Approximately 92% of the pixels with significant tendency are associated with the decreasing tendency of the albedo. The downward trend was observed with the change from the field to the forest cover, while increasing trends were influenced by the change in forest cover, such as the suppression of individuals from the upper forest canopy. The forest populations in areas of the Mata Atlântica biome had a large participation in the energy balance, which exposed a reduction of approximately 60% of the surface albedo with its implantation, showing its importance for reducing the emission of energy to the atmosphere. The spatial pattern of the trend distribution of the surface albedo is related to the concentration and vigor of the arboreal vegetation.

Effects of UV-B radiation on fitness related behaviors of the sea urchin Strongylocentrotus intermedius

Ozone depletion induced by anthropogenic gases has been increasing the transmission of solar ultraviolet-B radiation (UV-B, 280–315 nm) through the atmosphere, which may impact the fitness of marine invertebrates in intertidal and shallow waters. To our knowledge, however, the responses of fitness related behaviors to UV-B radiation at different intensities have been rarely studied in marine invertebrates. For the first time, the present study investigated the effects of exposure of one hour to UV-B radiation at different intensities on foraging behavior, Aristotle’s lantern reflex and righting behavior of the sea urchin Strongylocentrotus intermedius. Exposure of one hour to UV-B radiation at 10 μW/cm2 significantly reduced foraging behavior. An intensity dependent effect of exposure to UV-B radiation was found in the duration of the Aristotle’s lantern reflex. Exposure to UV-B radiation at 20 μW/cm2 for one hour significantly reduced the duration of the Aristotle’s lantern reflex, but 10 μW/cm2 did not. There was no significant difference of righting response time among sea urchins exposed to 0, 10 and 20 μW/cm2 for one hour. To test potential carryover effects, the behavioral traits were re-measured three days later. We found significant carryover effects of UV-B radiation on foraging time and righting response time, but not on the duration of the Aristotle’s lantern reflex. The present study indicates that a brief exposure of one hour to UV-B radiation can significantly affect the duration of Aristotle’s lantern reflex, righting response time and foraging behavior of a sea urchin, although the immediate impacts and carryover effects were highly trait dependent. This study provides new information into the behavioral responses of marine invertebrates to exposure to UV-B radiation. Future studies should be carried out to investigate long-term carryover effects of UV-B radiation on behavioral and physiological fitness related traits.

Domus method for predicting sunlit areas on interior surfaces

Abstract This pilot study aims to analyze the solar radiation transmission, daylight performance and glare reduction probability of complex shape solar control devices, developed with parametric modeling and digital fabrication. As methodology, initially the Rhinoceros3D+Grasshopper digital tools suite was used for the parametric modeling of solar control devices. Performance evaluations were performed by computational simulation and measurements in prototypes. For the simulations, the Diva-for-Rhino and Ladybug plug-ins were used. For the measurements, through digital fabrication, a prototype used for glare evaluations through HDR photographs was made. As main results, the solar control devices contributed to the control of solar radiation admission, better daylight distribution and glare reduction in the indoor analysis environment, confirming the reliability of the methodological procedures employed. It is important to highlight the effects of depth and inclination of the devices analyzed, respectively on the daylight distribution and selectivity in the admission of solar radiation between winter and summer. Finally, the shading masks show that despite all the development of modeling and simulation tools, the simple understanding of the solar geometry is still essential for the adequate performance of the solar control devices.

Solar radiation transmittance of a boreal balsam fir canopy: Spatiotemporal variability and impacts on growing season hydrology

Forest canopies act as permeable barriers between the atmosphere and the ground, reflecting and absorbing solar radiation. In the boreal forest, the large number of gaps and heterogeneities further complicates these processes. Several studies have adequately measured and modeled the transmittance of solar radiation through forest canopies in western North America and Scandinavia, but few have addressed those of Eastern North America. Furthermore, most of these studies have assessed the effects of solar radiation transmittance on snowpack energetics, but few have focused on the hydrological impacts during the growing season. This paper addresses this knowledge gap with precise measurements of sub-canopy solar radiation in a juvenile balsam fir forest located in the Montmorency Forest, Quebec, Canada. Twenty (20) sub-canopy stations were deployed in a 200 m by 150 m gridded box around a flux tower measuring above canopy radiation and eddy covariance fluxes during late summer and early fall 2016. Results show that the heterogeneous forest has substantial spatial variability of transmittance, with site-specific seasonal averages ranging between 0.07 and 0.69. Canopy gaps of size relative to tree height (H) between 0.1H and H had a temporal influence on solar radiation transmittance in canopy gaps at the sub-daily scale, but do not influence seasonal trends. This is attributed to very frequent cloudiness at the site, which renders the solar radiation mostly diffuse. As a result, a Beer-Lambert extinction law proved adequate at modeling site-specific or spatially averaged transmittance on a seasonal basis. We complement the observations by modeling canopy and soil moisture balances at 20 sites using the Canadian Land Surface Scheme (CLASS). The modeling results exhibit the following trend: a thicker (thinner) vegetation leads to more (less) evapotranspiration, because there is more (less) evaporation of intercepted precipitation and more (less) transpiration, but less (more) ground evaporation. During drier periods, the latter leads to wetter soil conditions for the thicker vegetation. These modeling results of sensitivity to vegetation density, while informative, still need to be confirmed with observations.

Drought and surface‐level solar radiation predict the severity of outbreaks of a widespread defoliating insect

AbstractDefoliating insects are a major factor impacting tree growth in temperate and boreal forests, but the effects of climate change on the severity and frequency of outbreaks of these insects are not well understood. Dendrochronological reconstruction of forest tent caterpillar (Malacosoma disstria) outbreaks on trembling aspen (Populus tremuloides) in southwestern Manitoba, Canada, from 1851 to 2010 was used to examine the effects of changes in temperature, incident surface‐level solar radiation, and drought severity on the cyclicity, frequency, and severity of outbreaks. Outbreak severity was determined by comparing the tree‐ring widths of trembling aspen with those of white spruce (Picea glauca), which is not a forest tent caterpillar host. Wavelet analysis suggested the cyclicity of outbreaks increased after 1930. From 1930 to 2010, the dominant period length of outbreak cycles steadily increased over time from three to seven years, coinciding with long‐term declines in drought severity. The strength of forest tent caterpillar suppression of trembling aspen growth in a given year was inversely related to incident solar radiation and drought severity during late spring (the larval feeding period) of the same year. The effect of late spring drought on the impact of forest tent caterpillar on ring growth differed from that of summer drought. There was a nonlinear relationship between growth suppression in a given year and summer drought severity in the previous year; slightly above‐average drought severity was associated with reduced impacts of the defoliator, whereas severe drought was associated with intense growth suppression. Strong suppression of aspen growth observed during outbreaks from 1983 to 2010 may be partly explained by observed long‐term trends of decreasing atmospheric transmittance of solar radiation (a phenomenon termed “global dimming”) and increasing soil moisture availability during late spring. However, as the severity and frequency of summer droughts are expected to increase over the 21st century, the nonlinear relationship between summer drought severity and growth suppression the following year suggests a future in which summer droughts precede severe outbreaks that threaten the health of boreal forest hardwood trees.

Toward ultra-low reflectance semi-transparent organic photovoltaic cells with biomimetic nanostructured transparent electrode

Abstract Semi-transparent organic photovoltaic cells (STOPVs) hold the great potential as a solar conversion source installed on the glass curtain walls. The cell performance of STOPVs is to some extent balanced among the absorption, transmission and reflection of the incident solar radiation. For the practical application with a defined transparency, the efficiency of STOPVs can be optimized by maximizing the light absorption as well as minimizing the reflection that contribute to the light pollution. Herein, a low-reflectance STOPV is presented with relatively high efficiency, high transmittance, and suitable color rendering property. A 15.9% increase in photocurrent and a 28% decrease in reflection are realized with the implementation of biomimetic moth-eye nanostructures into the dielectric-metal-dielectric transparent electrodes. For an optimized PTB7:PC71BM-based STOPV on flexible plastic substrate, the average transmittance in the visible region is kept at 46.1% and the average reflectance is reduced to 10.3%, leading a power conversion efficiency of 3.4%. The pathway described here is promising for opening up opportunities of reliable STOPVs towards the future commercial applications.

A mathematical model for calculating total transmission of solar radiation through shuttle louvers and experimental verification

The main problem of previous methods for the calculation of total transmission of solar radiation through shading louvers is that they can only deal with flat slats and pure diffuse reflection. Taking the radian and specular reflection of louvers into consideration, a new model of total solar radiation transmitted through shuttle louvers was established and experimentally verified in this paper. Firstly, taking two adjacent shuttle louvers as the object of study, the new calculation model was established, and a computer program based on the model was developed in MATLAB, which can be used to study the impact of shape, size, rotation angle, and surface optical properties of shuttle louvers on the transmission of direct and diffuse radiation. Secondly, an experimental set-up equipped with integrating sphere was built and experiments were performed to verify the new model, with the results showing that the model predictions compared well with the experimental data. Finally, the calculation errors of two conventional methods, the “flat slat model” and the “pure diffuse reflection model”, were analyzed, and the results showed that the “flat slat model” can cause considerable error and the relative error increases with the rotation angle of the louvers, and the “pure diffuse reflection model” gives overestimated results when the rotation angle is positive and underestimated results when the rotation angle is negative.

Optically Transparent Thermally Insulating Silica Aerogels for Solar Thermal Insulation.

Rooftop solar thermal collectors have the potential to meet residential heating demands if deployed efficiently at low solar irradiance (i.e., 1 sun). The efficiency of solar thermal collectors depends on their ability to absorb incoming solar energy and minimize thermal losses. Most techniques utilize a vacuum gap between the solar absorber and the surroundings to eliminate conduction and convection losses, in combination with surface coatings to minimize reradiation losses. Here, we present an alternative approach that operates at atmospheric pressure with simple, black, absorbing surfaces. Silica based aerogels coated on black surfaces have the potential to act as simple and inexpensive solar thermal collectors because of their high transmission to solar radiation and low transmission to thermal radiation. To demonstrate their heat-trapping properties, we fabricated tetramethyl orthosilicate-based silica aerogels. A hydrophilic aerogel with a thickness of 1 cm exhibited a solar-averaged transmission of 76% and thermally averaged transmission of ≈1% (at 100 °C). To minimize unwanted solar absorption by O-H groups, we functionalized the aerogel to be hydrophobic, resulting in a solar-averaged transmission of 88%. To provide a deeper understanding of the link between aerogel properties and overall efficiency, we developed a coupled radiative-conductive heat transfer model and used it to predict solar thermal performance. Instantaneous solar thermal efficiencies approaching 55% at 1 sun and 80 °C were predicted. This study sheds light on the applicability of silica aerogels on black coatings for solar thermal collectors and offers design priorities for next-generation solar thermal aerogels.

Evaluation of Solar Radiation Transmission through Window glasses and Transparent Facades for Buildings in Sulaimani

Evaluation of Solar Radiation Transmission through Window glasses and Transparent Facades for Buildings in Sulaimani

Effectively predict the solar radiation transmittance of dusty photovoltaic panels through Lambert-Beer law

Abstract Due to the instability and unsatisfactory prediction of the generating capacity, the photovoltaic power is hard to directly connect to the electric grid. Dust deposition is one of the key impact facts for the photovoltaic power, but its effect cannot be predicted through a reasonable physical model, and it became a hot research topic. This paper proposed a comprehensive physical model to predict the impact of the deposition on the light transmittance of solar panel. This model involves some physical parameters of the deposition, which made it applicable widely. In addition, the results indicate the influence of deposition prominently increased with the raise of the concentration and the size of the particles, but decreased with the changes of particle diaphaneity.

A three-dimensional model of solar radiation transfer in a non-uniform plant canopy

A three-dimensional (3D) model of solar radiation transfer in a non-uniform plant canopy was developed. It is based on radiative transfer equations and a so-called turbid medium assumption. The model takes into account the multiple scattering contributions of plant elements in radiation fluxes. These enable more accurate descriptions of plant canopy reflectance and transmission in different spectral bands. The model was applied to assess the effects of plant canopy heterogeneity on solar radiation transmission and to quantify the difference in a radiation transfer between photosynthetically active radiation PAR (=0.39-0.72 μm) and near infrared solar radiation NIR (Δλ = 0.72-3.00 μm). Comparisons of the radiative transfer fluxes simulated by the 3D model within a plant canopy consisted of sparsely planted fruit trees (plant area index, PAI - 0.96 m2 m-2) with radiation fluxes simulated by a one-dimensional (1D) approach, assumed horizontal homogeneity of plant and leaf area distributions, showed that, for sunny weather conditions with a high solar elevation angle, an application of a simplified 1D approach can result in an underestimation of transmitted solar radiation by about 22% for PAR, and by about 26% for NIR.