scholarly journals Solar radiation distribution inside a monospan greenhouse with the roof entirely covered by photovoltaic panels

2016 ◽  
Vol 47 (1) ◽  
pp. 1 ◽  
Author(s):  
Sergio Castellano ◽  
Pietro Santamaria ◽  
Francesco Serio
Keyword(s):  
Numerical Model ◽  
Solar Radiation ◽  
Southern Italy ◽  
Three Dimensional ◽  
Qualitative Behaviour ◽  
Photovoltaic Panels ◽  
Radiation Distribution ◽  
Sky Conditions ◽  
Term Analysis

In the present work the variation over space and time of the amount of the photosynthetic photons flux density, inside a greenhouse entirely covered with photovoltaic panels was investigated experimentally and numerically. The greenhouse had 10.00 m spam width, 50.00 m length, 3.00 m height of the gutter, 6.60 m height of the edge. Data were acquired in the period 18<sup>th</sup> April-8<sup>th</sup> June 2014 by one sensor outside and one inside the experimental greenhouse built in Southern Italy. Numeric simulations were performed by means of commercial software Autodesk<sup>®</sup> Ecotect<sup>®</sup>. For the investigated greenhouse model, the exposed percentage - the ratio of the calculated insolation at a particular point within an enclosure to the simultaneous unobstructed outdoor insolation under the same sky conditions - was calculated over a three dimensional grid formed by 50x10x15 cells each with 1.00x1.00x0.20 m size. The long-term analysis demonstrated a good capability of the numerical model to predict the shading effect inside a photovoltaic greenhouse combining the daily calculated exposed percentage with measurements of solar radiation. The model was able also to predict the qualitative behaviour of the variation of photons flux during the day even if the measured values showed a higher fluctuation of values.

Modelling of real solar radiation spatial distribution as a tool for solar energy cadastre in the cities

2017 ◽  
Vol 29 (2) ◽  
pp. 204-215 ◽  
Author(s):  
Małgorzata Pietras-Szewczyk ◽  
Leszek Szewczyk
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Cloud Cover ◽  
Significant Variable ◽  
State Security ◽  
Radiation Distribution ◽  
Linke Turbidity Factor ◽  
Gis Software ◽  
The City

The increasing needs of energy and decreasing traditional energy sources are becoming one of the biggest issues of our civilization. The provision of stable energy supply is a matter of state security. The energy consumption keeps growing especially in big cities. Therefore, it became reasonable to produce energy directly in cities. To optimize the use of the solar energy in the city areas, a fundamental issue is to find and estimate the amount of solar radiations at a specified location by using available tools and data. The main goal of this work is to demonstrate the potential of the r.sun model, a component of GRASS software, in calculating real solar radiation for the selected location. The work starts with demonstrating the effect of cloud cover for the amount of solar radiation reaching the Earth’s surface and the usage of GIS software and Ogimet website in the spatial analysis of real solar radiation distribution. For this purpose, data concerning cloud cover for selected locations were analysed. The study is based on the synoptic data obtained from Ogimet. Average daily cloud cover totals and long-term values were calculated. Apart from the cloud cover data, a significant variable, the Linke turbidity factor, describing the weakening of solar radiation due to the presence of aerosols and water vapour in the atmosphere, was taken into consideration. The obtained results were used to develop a map of real solar radiation distribution for a part of Wrocław. The results obtained by that model with the acquired data by the local meteorological station show compatibility.

Terrestrial Solar Radiation

2017 ◽  
pp. 191-293
Keyword(s):  
Solar Radiation ◽  
Horizontal Plane ◽  
Cloud Cover ◽  
Weather Conditions ◽  
Clear Sky ◽  
Solar Tracking ◽  
Sky Conditions ◽  
The Impact ◽  
Estimation Models

After shading a light on the extraterrestrial solar radiation in the chapter 3 it is important to evaluate the global terrestrial solar radiation and its components. The information on terrestrial solar radiation is required in several different forms depending on the kinds of calculations and kind of application that are to be done. Of course, terrestrial solar radiation on the horizontal plane depends on the different weather conditions such as cloud cover, relative humidity, and ambient temperature. Therefore, the impact of the atmosphere on solar radiation should be considered. One of the most important points of terrestrial solar radiation evaluation is its determination during clear sky conditions. Therefore, in this chapter, the equations that determine the air mass basing on available theories are given and the clear sky conditions are introduced with shading a light on the previous work in identifying clear sky conditions. Taking into consideration that, clear sky solar radiation estimation is of great importance for solar tracking, a detailed review of main available models is given in this chapter. As daily, monthly, seasonally, biannually and yearly mean daily solar radiations are required information for designing and installing long term tracking systems, different available methods are commented regarding their applicability for the estimation of solar radiation information in the desired format from the data that are available. An important accent is paid also on the assessment and comparison of monthly mean daily solar radiation estimation models.

scholarly journals Analysis on the impact of aerosol optical depth on surface solar radiation in the Shanghai megacity, China

2011 ◽  
Vol 11 (7) ◽  
pp. 3281-3289 ◽  
Author(s):  
J. Xu ◽  
C. Li ◽  
H. Shi ◽  
Q. He ◽  
L. Pan
Keyword(s):  
Solar Radiation ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Decadal Variation ◽  
Surface Solar Radiation ◽  
Atmospheric Transparency ◽  
Clear Sky ◽  
Term Variation ◽  
Sky Conditions

Abstract. This study investigated the decadal variation of the direct surface solar radiation (DiSR) and the diffuse surface solar radiation (DfSR) during 1961–2008 in the Shanghai megacity as well as their relationships to Aerosol Optical Depth (AOD) under clear-sky conditions. Three successive periods with unique features of long term variation of DiSR were identified for both clear-sky and all-sky conditions: a "dimming" period from the late 1960s to the mid 1980s, a "stabilization"/"slight brightening" period from the mid 1980s to the mid 1990s, and a "renewed dimming" period thereafter. During the two dimming periods of DiSR, DfSR brightened significantly under clear-sky conditions, indicating that change in atmospheric transparency resulting from aerosol emission has an important role on decadal variation of surface solar radiation (SSR) over this area. The analysis on the relationship between the Moderate-resolution Imaging Spectroradiometer (MODIS) retrieved AOD and the corresponding hourly measurements of DiSR and DfSR under clear-sky conditions clearly revealed that AOD is significantly correlated and anti-correlated with DfSR and DiSR, respectively, both above 99% confidence in all seasons, indicating the great impact of aerosols on SSR through absorption and/or scattering in the atmosphere. In addition, both AOD and the corresponding DiSR and DfSR measured during the satellite passage over Shanghai show obvious weekly cycles. On weekends, AOD is lower than the weekly average, corresponding to higher DiSR and lower DfSR, while the opposite pattern was true for weekdays. Less AOD on weekends due to the reduction of transportation and industrial activities results in enhancement of atmospheric transparency under cloud free conditions so as to increase DiSR and decrease DfSR simultaneously. Results show that aerosol loading from the anthropogenic emissions is an important modulator for the long term variation of SSR in Shanghai.

scholarly journals Three-dimensional Analysis of Solar Radiation Distribution at the Focal Zone of the Solar Furnace of IER_UNAM

2014 ◽  
Vol 57 ◽  
pp. 3031-3040 ◽  
Author(s):  
R. Perez-Enciso ◽  
D. Riveros-Rosas ◽  
M. Sanchez ◽  
C.A. Pérez-Rabago ◽  
C.A. Arancibia-Bulnes ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Dimensional Analysis ◽  
Three Dimensional ◽  
Solar Furnace ◽  
Radiation Distribution ◽  
Focal Zone

scholarly journals Causes of Dimming and Brightening in China Inferred from Homogenized Daily Clear-Sky and All-Sky in situ Surface Solar Radiation Records (1958–2016)

2019 ◽  
Vol 32 (18) ◽  
pp. 5901-5913 ◽  
Author(s):  
Su Yang ◽  
Xiaolan L. Wang ◽  
Martin Wild
Keyword(s):  
Water Vapor ◽  
Solar Radiation ◽  
Water Vapor Pressure ◽  
Historical Records ◽  
Surface Solar Radiation ◽  
Clear Sky ◽  
The Past ◽  
Sky Conditions

AbstractThis paper presents a study on long-term surface solar radiation (SSR) changes over China under clear- and all-sky conditions and analyzes the causes of the “dimming” and “brightening.” To eliminate the nonclimatic signals in the historical records, the daily SSR dataset was first homogenized using quantile-matching (QM) adjustment. The results reveal rapid dimming before 2000 not only under all-sky conditions, but also under clear-sky conditions, at a decline rate of −9.7 ± 0.4 W m−2 decade−1 (1958–99). This is slightly stronger than that under all-sky conditions at −7.4 ± 0.4 W m−2 decade−1, since the clear-sky dimming stopped 15 years later. A rapid “wettening” of about 40-Pa surface water vapor pressure (SWVP) from 1985 to 2000 was found over China. It contributed 2.2% to the SSR decline under clear-sky conditions during the whole dimming period (1958–99). Therefore, water vapor cannot be the main cause of the long-term dimming in China. After a stable decade (1999–2008), an intensive brightening appeared under the clear-sky conditions at a rate of 10.6 ± 2.0 W m−2 decade−1, whereas a much weaker brightening (−0.8 ± 3.1 W m−2 decade−1) has been observed under all-sky conditions between 2008 and 2016. The remarkable divergence between clear- and all-sky trends in recent decades indicates that the clouds played two opposite roles in the SSR changes during the past 30 years, by compensating for the declining SSR under the cloud-free conditions in 1985–99 and by counteracting the increasing SSR under cloud-free conditions in 2008–16. Aerosols remain as the main cause of dimming and brightening over China in the last 60 years, although the clouds counteract the effects of aerosols after 2000.

scholarly journals Detection of dimming/brightening in Italy from homogenized all-sky and clear-sky surface solar radiation records and underlying causes (1959–2013)

2016 ◽  
Author(s):  
Veronica Manara ◽  
Michele Brunetti ◽  
Angela Celozzi ◽  
Maurizio Maugeri ◽  
Arturo Sanchez-Lorenzo ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Significant Contribution ◽  
Southern Italy ◽  
Temporal Evolution ◽  
Surface Solar Radiation ◽  
Clear Sky ◽  
The North ◽  
Underlying Causes ◽  
Set Up ◽  
Sky Conditions

Abstract. A dataset of 54 daily Italian downward surface solar radiation (SSR) records has been set up collecting data for the 1959–2013 period. Particular emphasis is placed upon the quality control and the homogenization of the records in order to ensure the reliability of the resulting trends. This step has been shown as necessary due to the large differences obtained between the raw and homogenized dataset, especially during the first decades of the study period. In addition, SSR series under clear-sky conditions were obtained considering only the cloudless days from corresponding ground-based cloudiness observations. Subsequently, the records were interpolated onto a regular grid and clustered in two regions, Northern and Southern Italy, which were averaged in order to get all-sky and clear-sky regional SSR records. Their temporal evolution is presented, and possible reasons for differences between all-sky and clear-sky conditions and between the two regions are discussed in order to understand which part of the SSR variability depends on aerosols or clouds. Specifically, the all-sky SSR records show a decrease until the mid-1980s (dimming period) and a following increase until the end of the series (brightening period) even if the strength and the persistence of the tendencies are not the same in all seasons. The clear-sky records present stronger tendencies than the all-sky records during the dimming period in all seasons and during the brightening period in winter and autumn. This suggests that under all-sky the variations caused by the increase/decrease of the aerosol content have been partially masked by cloud cover variations, especially during the dimming period. Under clear-sky the observed dimming is stronger in the South than in the North. This peculiarity could be a consequence of a significant contribution of mineral dust variations to the SSR variability.

scholarly journals Detection of dimming/brightening in Italy from homogenized all-sky and clear-sky surface solar radiation records and underlying causes (1959–2013)

2016 ◽  
Vol 16 (17) ◽  
pp. 11145-11161 ◽  
Author(s):  
Veronica Manara ◽  
Michele Brunetti ◽  
Angela Celozzi ◽  
Maurizio Maugeri ◽  
Arturo Sanchez-Lorenzo ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Significant Contribution ◽  
Southern Italy ◽  
Temporal Evolution ◽  
Surface Solar Radiation ◽  
Clear Sky ◽  
The North ◽  
Underlying Causes ◽  
Set Up ◽  
Sky Conditions

Abstract. A dataset of 54 daily Italian downward surface solar radiation (SSR) records has been set up collecting data for the 1959–2013 period. Special emphasis is given to the quality control and the homogenization of the records in order to ensure the reliability of the resulting trends. This step has been shown as necessary due to the large differences obtained between the raw and homogenized dataset, especially during the first decades of the study period. In addition, SSR series under clear-sky conditions were obtained considering only the cloudless days from corresponding ground-based cloudiness observations. Subsequently, records were interpolated onto a regular grid and clustered into two regions, northern and southern Italy, which were averaged in order to get all-sky and clear-sky regional SSR records. Their temporal evolution is presented, and possible reasons for differences between all-sky and clear-sky conditions and between the two regions are discussed in order to determine to what extent SSR variability depends on aerosols or clouds. Specifically, the all-sky SSR records show a decrease until the mid-1980s (dimming period), and a following increase until the end of the series (brightening period) even though strength and persistence of tendencies are not the same in all seasons. Clear-sky records present stronger tendencies than all-sky records during the dimming period in all seasons and during the brightening period in winter and autumn. This suggests that, under all-sky conditions, the variations caused by the increase/decrease in the aerosol content have been partially masked by cloud cover variations, especially during the dimming period. Under clear sky the observed dimming is stronger in the south than in the north. This peculiarity could be a consequence of a significant contribution of mineral dust variations to the SSR variability.

scholarly journals Analysis on the impact of aerosol optical depth on surface solar radiation in the Shanghai megacity, China

2011 ◽  
Vol 11 (1) ◽  
pp. 627-652
Author(s):  
J. Xu ◽  
C. Li ◽  
H. Shi ◽  
Q. He ◽  
L. Pan
Keyword(s):  
Solar Radiation ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Decadal Variation ◽  
Surface Solar Radiation ◽  
Atmospheric Transparency ◽  
Clear Sky ◽  
Term Variation ◽  
Sky Conditions

Abstract. This study investigated the decadal variation of the direct surface solar radiation (DiSR) and the diffuse surface solar radiation (DfSR) during 1961–2008 in the Shanghai megacity as well as their relationships to Aerosol Optical Depth (AOD) under clear-sky conditions. Three successive periods with unique features of long term variation of DiSR were identified for both clear-sky and all-sky conditions: a "dimming" period from the late 1960s to the mid 1980s, a "stabilization"/"slight brightening" period from the mid 1980s to the mid 1990s, and a "renewed dimming" period thereafter. During the two dimming periods of DiSR, DfSR brightened significantly under clear-sky conditions, indicating that change in atmospheric transparency resulting from aerosol emission has an important role on decadal variation of surface solar radiation (SSR) over this area. The analysis on the relationship between the Moderate-resolution Imaging Spectroradiometer (MODIS) retrieved AOD and the corresponding hourly measurements of DiSR and DfSR under clear-sky conditions clearly revealed that AOD is significantly correlated and anti-correlated with DfSR and DiSR, respectively, both above 99% confidence in all seasons, indicating the great impact of aerosols on SSR through absorption and/or scattering in the atmosphere. In addition, both AOD and the corresponding DiSR and DfSR measured during the satellite passage over Shanghai show obvious weekly cycles. On weekends, AOD is lower than the weekly average, corresponding to higher DiSR and lower DfSR, while the opposite pattern was true for weekdays. Less AOD on weekends due to the reduction of transportation and industrial activities results in enhancement of atmospheric transparency under cloud free conditions so as to increase DiSR and decrease DfSR simultaneously. Results show that aerosol loading from the anthropogenic emissions is an important modulator for the long term variation of SSR in Shanghai.

Practical electron tomography

1995 ◽  
Vol 53 ◽  
pp. 742-743
Author(s):  
C.L. Woodcock
Keyword(s):  
Electron Tomography ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
3D Shape ◽  
Computational Resources ◽  
Shape Of Particles

Despite the potential of the technique, electron tomography has yet to be widely used by biologists. This is in part related to the rather daunting list of equipment and expertise that are required. Thanks to continuing advances in theory and instrumentation, tomography is now more feasible for the non-specialist. One barrier that has essentially disappeared is the expense of computational resources. In view of this progress, it is time to give more attention to practical issues that need to be considered when embarking on a tomographic project. The following recommendations and comments are derived from experience gained during two long-term collaborative projects.Tomographic reconstruction results in a three dimensional description of an individual EM specimen, most commonly a section, and is therefore applicable to problems in which ultrastructural details within the thickness of the specimen are obscured in single micrographs. Information that can be recovered using tomography includes the 3D shape of particles, and the arrangement and dispostion of overlapping fibrous and membranous structures.

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