Global solar radiation is generally measured on a horizontal surface, whereas the maximum amount of incident solar radiation is measured on an inclined surface. Over the last decade, a number of ...models were proposed for predicting solar radiation on inclined surfaces. These models have various scopes; applicability to specific surfaces, the requirement for special measuring equipment, or limitations in scope. To find the most suitable model for a given location the hourly outputs predicted by available models are compared with the field measurements of the given location. The main objective of this study is to review on the estimation of the most accurate model or models for estimating solar radiation components for a selected location, by testing various models available in the literature. To increase the amount of incident solar radiation on photovoltaic (PV) panels, the PV panels are mounted on tilted surfaces. This article also provides an up-to-date status of different optimum tilt angles that have been determined in various countries.
Each day the Global‐scale Observations of the Limb and Disk imager observes the equatorial ionization anomaly (EIA) near sunset from ∼10°E to ∼80°W geographic longitude. Most images cover ∼45° of ...longitude (∼3 hr), and most longitudes are observed multiple times. Monthly averages of EIA crests' latitude (EIA lats) versus longitude during March, September, and December 2020 have been analyzed. The EIA lats reflect the combined influence of winds, solar radiation, and fields (electric and magnetic) in the equatorial region. Winter solstice differs significantly from the equinoxes, which are similar, but there are notable similarities between all three. The similarities in the EIA lats during the seasons examined indicates that the magnetic equator to subsolar point separation influences them in all three seasons and that it has a more distinct, possibly more significant, influence than winds on the average latitudes.
Plain Language Summary
Each day the Global‐scale Observations of the Limb and Disk imager observes the nighttime equatorial ionization anomaly (EIA) near sunset as the terminator progresses westward from Africa to across South America. Most images cover ∼45° of longitude (∼3 hr of local time), and most longitudes are observed multiple times. In 2020 seasonal averages of the crests' latitude versus longitude during the equinoxes (March and September) and winter solstice (December) show significant, important similarities. The observed latitude versus longitude dependence in all three show a dependence on the distance between the magnetic equator and the subsolar point. Greater knowledge of the seasonal‐longitudinal dependence of the EIA crests' latitudes contributes significantly to understanding the crests' response to fields (electric and magnetic) and winds in the equatorial region.
Key Points
The average nighttime EIA crests' latitudes observed by GOLD during 2020 equinoxes and December solstice have a longitudinal dependence
Crests' latitude dependence on longitude changes near 47°W geographic, where the magnetic and geographic equators cross
Crests' latitudes over 75°W–10°E geographic longitude during equinoxes and winter solstice depend on the subsolar point magnetic latitude
Nine simulations are used to predict the meteorology and aeolian activity of the Mars 2020 landing site region. Predicted seasonal variations of pressure and surface and atmospheric temperature ...generally agree. Minimum and maximum pressure is predicted at
Ls
∼
145
∘
and
250
∘
, respectively. Maximum and minimum surface and atmospheric temperature are predicted at
Ls
∼
180
∘
and
270
∘
, respectively; i.e., are warmest at northern fall equinox not summer solstice. Daily pressure cycles vary more between simulations, possibly due to differences in atmospheric dust distributions. Jezero crater sits inside and close to the NW rim of the huge Isidis basin, whose daytime upslope (∼east-southeasterly) and nighttime downslope (∼northwesterly) winds are predicted to dominate except around summer solstice, when the global circulation produces more southerly wind directions. Wind predictions vary hugely, with annual maximum speeds varying from 11 to
19
ms
−
1
and daily mean wind speeds peaking in the first half of summer for most simulations but in the second half of the year for two. Most simulations predict net annual sand transport toward the WNW, which is generally consistent with aeolian observations, and peak sand fluxes in the first half of summer, with the weakest fluxes around winter solstice due to opposition between the global circulation and daytime upslope winds. However, one simulation predicts transport toward the NW, while another predicts fluxes peaking later and transport toward the WSW. Vortex activity is predicted to peak in summer and dip around winter solstice, and to be greater than at InSight and much greater than in Gale crater.
This paper argues that the positions of select stones at Stonehenge reveal a lunar calendar which is integrated with a solar calendar, and that this was intentionally included in the design of the ...monument. In particular, the analysis shows that Stone 11, which is half the size of the others, is pivotal in both the lunar and solar timelines. Further, it is argued that this stone also marked the midwinter sunrise, its shadow making contact with Bluestone 40 similar to the way in which the Heel Stone indicates midsummer sunrise by its shadow falling upon the Altar Stone.
Epidemic influenza and vitamin D CANNELL, J. J.; VIETH, R.; UMHAU, J. C. ...
Epidemiology and infection,
12/2006, Letnik:
134, Številka:
6
Journal Article
Recenzirano
Odprti dostop
In 1981, R. Edgar Hope-Simpson proposed that a ‘seasonal stimulus’ intimately associated with solar radiation explained the remarkable seasonality of epidemic influenza. Solar radiation triggers ...robust seasonal vitamin D production in the skin; vitamin D deficiency is common in the winter, and activated vitamin D, 1,25(OH)2D, a steroid hormone, has profound effects on human immunity. 1,25(OH)2D acts as an immune system modulator, preventing excessive expression of inflammatory cytokines and increasing the ‘oxidative burst’ potential of macrophages. Perhaps most importantly, it dramatically stimulates the expression of potent anti-microbial peptides, which exist in neutrophils, monocytes, natural killer cells, and in epithelial cells lining the respiratory tract where they play a major role in protecting the lung from infection. Volunteers inoculated with live attenuated influenza virus are more likely to develop fever and serological evidence of an immune response in the winter. Vitamin D deficiency predisposes children to respiratory infections. Ultraviolet radiation (either from artificial sources or from sunlight) reduces the incidence of viral respiratory infections, as does cod liver oil (which contains vitamin D). An interventional study showed that vitamin D reduces the incidence of respiratory infections in children. We conclude that vitamin D, or lack of it, may be Hope-Simpson's ‘seasonal stimulus’.
This paper describes the details of the design of a solar water disinfection system based on a small-scale linear Fresnel reflector. The proposed system consists of a small-scale linear Fresnel ...reflector, a filtering system, two disinfection units, a heat exchanger, a compressed air system and the control system. A detailed mathematical model has been developed and solved through an iterative procedure. The system has been studied under different operating conditions, such as beam solar irradiance (the beam solar irradiance on a horizontal surface, corresponding to solar noon, varies from 325 to 798 W m
−2
, for winter solstice and summer solstice, respectively), ambient temperature (the ambient temperature varies between 19 and 29 °C at the summer solstice and from 8 to 16 °C at the winter solstice), thermal fluid flow rate (2200 L h
−1
, 2400 L h
−1
, 2600 L h
−1
, and 2800 L h
−1
) and water temperature at the outlet of the filtered water tank (8 °C, 12 °C, 16 °C, and 20 °C). The performance of the system has been studied as a function of the temperature of the thermal fluid of the small-scale linear Fresnel reflector, the water temperature of the disinfection unit, the filling and emptying of inertia tanks, clean water productivity and the daily cumulative productivity of clean water. Numerical simulations reveal that the maximum values of cumulative daily productivity of clean water were 357.14 (L m
−2
day
−1
) at 100 (°C) and 198.41 (L m
−2
day
−1
) at 100 (°C) for summer solstice and winter solstice, respectively, in Almeria (Spain), for a thermal fluid flow rate of 2400 L h
−1
. Values much higher than those obtained by other systems. The inclusion of a heat exchanger in this system significantly increases its productivity. Small-scale linear Fresnel reflector thermal fluid temperature, disinfection unit water temperature, clean water productivity and daily cumulative clean water productivity decreased with increasing thermal fluid flow rate above 2400 L h
−1
. On the other hand, the water temperature at the outlet of the filtered water tank between 8 and 20 °C has a negligible influence on the small-scale linear Fresnel reflector thermal fluid temperature values, disinfection unit water temperature, clean water productivity and daily cumulative clean water productivity. It is concluded that the proposed solar system offers an energy efficient and environmentally friendly water treatment method.
This paper describes the details of the design of a solar water disinfection system based on a small-scale linear Fresnel reflector.
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