Impact of microstructure and horizontal heterogeneity of broken cirrus clouds on mean solar radiation fluxes in the visible spectral region: results of numerical simulation

2021 ◽  
Vol 34 (10) ◽  
pp. 792-802
Author(s):  
T.B. Zhuravleva ◽  
I.M. Nasrtdinov
2020 ◽  
Vol 15 (4) ◽  
pp. 613-619
Author(s):  
Li Kong ◽  
Yunpeng Zhang ◽  
Zhijian Lin ◽  
Zhongzhu Qiu ◽  
Chunying Li ◽  
...  

Abstract The present work aimed to select the optimum solar tracking mode for parabolic trough concentrating collectors using numerical simulation. The current work involved: (1) the calculation of daily solar radiation on the Earth’s surface, (2) the comparison of annual direct solar radiation received under different tracking modes and (3) the determination of optimum tilt angle for the north-south tilt tracking mode. It was found that the order of solar radiation received in Shanghai under the available tracking modes was: dual-axis tracking > north-south Earth’s axis tracking > north-south tilt tracking (β = 15°) > north-south tilt tracking (β = 45) > north-south horizontal tracking > east-west horizontal tracking. Single-axis solar tracking modes feature simple structures and low cost. This study also found that the solar radiation received under the north-south tilt tracking mode was higher than that of the north-south Earth’s axis tracking mode in 7 out of 12 months. Therefore, the north-south tilt tracking mode was studied separately to determine the corresponding optimum tilt angles in Haikou, Lhasa, Shanghai, Beijing and Hohhot, respectively, which were shown as follows: 18.81°, 27.29°, 28.67°, 36.21° and 37.97°.


2021 ◽  
Author(s):  
Katarzyna Zielonko-Jung ◽  
Justyna Janiak

AbstractThe present study is aimed at the analysis of possibilities for shading southern frontage of street oriented along the E-W axis by the single row of trees, parallel to the southern elevations. The effectiveness of solar control shading was tested depending on the geometric relationships between trees and buildings. Numerical simulation analyses were conducted in Rhinoceros® program for the street located in humid continental climate in city Płock, Poland (52°32′50 “N 19°42’00 “E), for the day of the highest degree of total solar radiation in the year i.e. June 7th, during hours: 8.00a.m - 5.00 p.m. The analysis has proved that a row of 20–25 year old Sycamore Maple ‘Rotterdam’ in the street 30 m wide and 18 m high (H/W = 0.6), can provide solar protection for the southern frontage, especially when trees are located no more than 4 m away. Location of greenery within the range of 4 to 5 m from the buildings leads to a radical reduction in the possibility of shading the wall surfaces (at 5 m to 0%). Over 90% of the shading area of the ground floor façade walls was found when trees were within the distance 2 and 3 m away from the building.


2014 ◽  
Vol 116 (4) ◽  
pp. 542-547 ◽  
Author(s):  
M. V. Zagidullin ◽  
M. I. Svistun ◽  
N. A. Khvatov ◽  
A. S. Insapov

1994 ◽  
Vol 49 (6) ◽  
pp. 849-851 ◽  
Author(s):  
G. C. Papavassiliou ◽  
I. B. Koutselas

The title compounds (natural low-dimensional semiconductors) show strong excitonic optical absorption bands in the UV-visible spectral region, because of the dielectric confinement of excitons. as in the cases of other similar systems based on PbX2-4, SnX2-4. PtI - X - PtIV-X , Cdx,Sy-clusters etc


Author(s):  
Rebeca Sola Llano ◽  
Edurne Avellanal Zaballa ◽  
Jorge Bañuelos ◽  
César Fernando Azael Gómez Durán ◽  
José Luis Belmonte Vázquez ◽  
...  

2019 ◽  
Vol 61 (5) ◽  
pp. 848
Author(s):  
У.В. Валиев ◽  
Gary W. Burdick ◽  
Р.Р. Вильданов ◽  
R.Yu. Rakhimov ◽  
Dejun Fu

AbstractThe spectra of luminescence and magnetic circular polarization of luminescence of praseodymium–yttrium aluminum garnet Pr^3+ : Y_3Al_5O_12 (PrYAG) are studied in the visible spectral region at temperature T = 300 K. An analysis of spectral dependences of magnetooptical and optical spectra makes it possible to identify optical 4  f –4  f -transitions between Stark sublevels of multiplets ^3 P _0, ^3 P _1, ^3 Н _5, and ^3 Н _6 in PrYAG. It was shown that an important role in the spectrum of the degree of magnetic circular polarization of luminescence of this paramagnetic garnet is played by the effect of quantum-mechanical J – J mixing of states of Stark singlets ^3 Н _5 and ^3 Н _6 of non-Kramer rare-earth ion Pr^3+ in the “green” luminescence band related to forbidden 4  f → 4  f transition ^3 P _0 → ^3 Н _5 in the visible spectral region. To interpret the spectra of magnetic circular polarization of luminescence, the energy of experimentally determined Stark sublevels of multiplets under study, their irreducible representations and wave functions determined by numerical simulation of the energy spectrum of the rare-earth ion Pr^3+ in the garnet structure are used.


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