scholarly journals Performance of thermoelectric conversion device with power management module based on shallow soil-air temperature difference

2021 ◽  
pp. 101582
Author(s):  
Latai Ga ◽  
Zhe Zhang ◽  
Daochun Xu ◽  
Wenbin Li
Keyword(s):  
Power Management ◽  
Air Temperature ◽  
Temperature Difference ◽  
Soil Air ◽  
Thermoelectric Conversion ◽  
Shallow Soil

scholarly journals A Study of Developing a Prediction Equation of Electricity Energy Output via Photovoltaic Modules

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1503
Author(s):  
Minsu Kim ◽  
Hongmyeong Kim ◽  
Jae Hak Jung
Keyword(s):  
Experimental Data ◽  
Real Time ◽  
Air Temperature ◽  
Temperature Difference ◽  
Prediction Accuracy ◽  
Prediction Equation ◽  
Energy Output ◽  
Photovoltaic Modules ◽  
Mean Error ◽  
Pv Module

Various equations are being developed and applied to predict photovoltaic (PV) module generation. Currently, quite diverse methods for predicting module generation are available, with most equations showing accuracy with ≤5% error. However, the accuracy can be determined only when the module temperature and the value of irradiation that reaches the module surface are precisely known. The prediction accuracy of outdoor generation is actually extremely low, as the method for predicting outdoor module temperature has extremely low accuracy. The change in module temperature cannot be predicted accurately because of the real-time change of irradiation and air temperature outdoors. Calculations using conventional equations from other studies show a mean error of temperature difference of 4.23 °C. In this study, an equation was developed and verified that can predict the precise module temperature up to 1.64 °C, based on the experimental data obtained after installing an actual outdoor module.

scholarly journals Difference in Canopy and Air Temperature as an Indicator of Grassland Water Stress

2013 ◽  
Vol 1 (No. 4) ◽  
pp. 127-138 ◽  
Author(s):  
Duffková Renata
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Moisture Content ◽  
Air Temperature ◽  
Temperature Difference ◽  
Soil Moisture Content ◽  
Growing Season ◽  
Plant Residues ◽  
Dead Plant ◽  
Linear Correlations

In 2003–2005 in conditions of the moderately warm region of the Třeboň Basin (Czech Republic) the difference between canopy temperature (Tc) and air temperature at 2 m (Ta) was tested as an indicator of grass­land water stress. To evaluate water stress ten-minute averages of temperature difference Tc–Ta were chosen recorded on days without rainfall with intensive solar radiation from 11.00 to 14.00 CET. Water stress in the zone of the major portion of root biomass (0–0.2 m) in the peak growing season (minimum presence of dead plant residues) documented by a sudden increase in temperature difference, its value 5–12°C and unfavourable canopy temperatures due to overheating (> 30°C) was indicated after high values of suction pressure approach­ing the wilting point (1300 kPa) were reached. High variability of temperature difference in the conditions of sufficient supply of water to plants was explained by the amount of dead plant residues in canopy, value of va­pour pressure deficit (VPD), actual evapotranspiration rate (ETA) and soil moisture content. At the beginning of the growing season (presence of dead plant residues and voids) we proved moderately strong negative linear correlations of Tc–Ta with VPD and Tc–Ta with ETA rate and moderately strong positive linear correlations of ETA rate with VPD. In the period of intensive growth (the coverage of dead plant residues and voids lower than 10%) moderately strong linear correlations of Tc–Ta with VPD and multiple linear correlations of Tc–Ta with VPD and soil moisture content at a depth of 0.10–0.40 m were demonstrated.

scholarly journals Air temperature profile and air/sea temperature difference measurements by infrared and microwave scanning radiometers

Radio Science ◽  
2003 ◽  
Vol 38 (3) ◽  
pp. n/a-n/a ◽  
Author(s):  
D. Cimini ◽  
J. A. Shaw ◽  
E. R. Westwater ◽  
Y. Han ◽  
V. Irisov ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Air Temperature ◽  
Temperature Difference ◽  
Sea Temperature

scholarly journals Use of Reflectance Indices to Assess Vine Water Status under Mild to Moderate Water Deficits

Agronomy ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 346 ◽  
Author(s):  
Cristina González-Flor ◽  
Lydia Serrano ◽  
Gil Gorchs
Keyword(s):  
Air Temperature ◽  
Temperature Difference ◽  
Water Status ◽  
Canopy Structure ◽  
Similar Response ◽  
Water Deficits ◽  
Potted Plants ◽  
Significant Relationships ◽  
Leaf Level ◽  
Reflectance Indices

The monitoring of vine water status is of interest for irrigation management in order to improve water use while optimizing both berry yield and quality. Remote-sensing techniques might provide accurate, rapid, and non-destructive estimates of vine water status. The objective of this study was to test the capability of the reflectance-based water index (WI) and the photochemical reflectance index (PRI) to characterize Vitis vinifera L. cv. Xarel·lo water status under mild to moderate water deficits. The study was conducted at the leaf level in irrigated potted plants and at the plant level on five commercial rain-fed vineyards in 2009 and 2010. In potted plants, the reflectance indices PRI and WI closely tracked variation in the leaf-to-air temperature difference (ΔT) with r2 = 0.81 and r2 = 0.83, for WI and PRI, respectively (p < 0.01). In addition, in potted plants, both PRI and WI showed significant relationships with light-use efficiency (LUE)—calculated as the ratio between net CO2 assimilation rate (An) and incident photosynthetic active radiation (PAR) at the leaf surface—with r2 = 0.92 and r2 = 0.74 for PRI and WI, respectively. At the canopy level, vine predawn water potential (Ψpd) was related to the canopy-to-air temperature difference (ΔTm) across years (r2 = 0.37, p < 0.05). In the years of study, the relationships between PRI and WI showed variable degrees of correlation against Ψpd and ΔTm. Across years, PRI and WI showed significant relationships with Ψpd, with r2 = 0.41 and r2 = 0.37 (p < 0.01), for WI and PRI, respectively. Indices formulated to account for variation in canopy structure (i.e., PRInorm and WInorm) showed similar degrees of correlation against Ψpd to their original formulations. In addition, PRI and WI were capable of differentiating (p < 0.01) between mild (Ψpd > −0.4 MPa) and moderate (Ψpd < −0.4 MPa) water deficits, and a similar response was observed when PRInorm and WInorm—formulated to account for variation in canopy structure—were considered. Thus, at the leaf level, our result suggest that WI and PRI can be used to adequately predict the diurnal dynamics of stomatal aperture and transpiration. In addition, at the canopy level, PRI and WI effectively differentiated vines under mild water deficits from those experiencing moderate water deficits. Thus, our results show the capability of WI and PRI in characterizing vine water status under mild to moderate water deficits.

Canopy-air temperature difference of winter wheat near-isogenic lines and its relationship with total water consumption by winter wheat grown under water deficit conditions

2019 ◽  
Vol 39 (1) ◽  
Author(s):  
梅旭荣 MEI Xurong ◽  
黄桂荣 HUANG Guirong ◽  
严昌荣 YAN Changrong ◽  
刘晓英 LIU Xiaoying ◽  
张欣莹 ZHANG Xinying ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Water Deficit ◽  
Air Temperature ◽  
Temperature Difference ◽  
Water Consumption ◽  
Near Isogenic Lines ◽  
Total Water ◽  
Isogenic Lines ◽  
Total Water Consumption

Generation of electric charge associated with the formation of soft hail in thunderclouds

1961 ◽  
Vol 260 (1303) ◽  
pp. 537-549 ◽  
Keyword(s):  
Impact Velocity ◽  
Air Temperature ◽  
Temperature Difference ◽  
Temperature Drop ◽  
Ice Crystals ◽  
Drop Diameter ◽  
Charge Generation ◽  
Typical Experiment ◽  
A Charge ◽  
Negative Sense

The electrical charging which results from collisions between ice crystals and a simulated hailstone is measured as a function of their temperature difference, and of the size and impact velocity of the crystals. It is found that the sign of the charging is governed by that of the temperature difference, the hailstone becoming negatively charged if it is warmer than the rebounding crystals. The magnitude of the charging is proportional to the temperature differ­ence but rather insensitive to the size and impact velocity of the crystals. With a temperature difference of 5°C, a rebounding crystal of diameter about 50 μ produces, on average, a charge of 5 x 10 -9 e. s. u. The electrification of an artificial pellet of soft hail growing by the accretion of supercooled water droplets (riming) is also investigated. Freezing of the droplets on the hailstone is accompanied by the ejection of positively charged ice splinters, the hailstone acquiring a negative charge. The manner in which the rates of charging and splinter produc­tion vary with the air temperature, drop diameter and impact velocity has been established. In a typical experiment, with the air temperature at -15°C, droplets of diameter 80 μ impacting at 10 m s -1 freeze to produce, on average, 12 splinters and a charge of 4 x 10 -6 e. s. u. per drop. Droplets of diameter less than 30 μ produce few splinters and little charging. The results of both sets of experiments are interpreted in terms of the authors’ theory of charge separation in ice under the influence of a temperature gradient, and are used to calculate probable rates of charge generation in thunderstorms. It appears that the electrification which accompanies the growth of pellets of soft hail through the freezing and splintering of supercooled droplets is capable of generating and separating charge at the required rate of about 1 C km -3 min -1 but, while rebounding ice crystals will usually charge the hailstones in the same (negative) sense, this mechanism will contribute only slightly to thunderstorm electrification.

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