Authors:M. Naderianfar, A. Faryabi, and H. Dehghan
The wind drift and evaporation losses (WDEL) are high in arid, semi-arid and windward areas, and reduce the efficiency of the sprinkler irrigation system; therefore, this study was carried out in order to achieve a practical criterion and provide a relationship for accurate estimation of the wind drift and evaporation losses in different atmospheric conditions. The experiments were done at the Meteorological Station of the Faculty of Agriculture of Ferdowsi University of Mashhad using a line-source sprinkler irrigation system based on the single sprinkler installation method. To achieve the objectives of this plan, factorial experiment was performed on PGP sprinkler with regard to the two factors, the pressure of the sprinkler function (with three levels 1.6, 2.5 and 3.4 bar) and the diameter of the nozzle (with three levels of 4, 5 and 6 mm) with three replications (morning, noon and night). Assessing the result of the data variance analysis showed that the effects of pressure, aperture diameter, and time on the wind drift and evaporation losses are not significant. Investigating the main effects of these factors showed that the effect of aperture diameter on irrigation losses is significant at the level of the 1%. In order to further investigate, the comparison of mean losses data in three aperture diameter was done using Duncan′s test. The results indicated that aperture 4 with the losses of 44% had a significant difference with other diameters. This result suggests an increase in losses for smaller diameters due to the small droplets and the increase in wind drift. Also, the comparison of the mean losses data in three times showed that irrigation at noon with the losses of 44% had a significant difference compared to other times due to a significant increase in temperature and radiation of the sun and saturation vapor pressure deficit, and there is no significant difference between morning and evening irrigation. Also, analysis of variance showed that the effect of water pressure change between 1.6 and 4.3 bar does not have a significant effect on the WDEL in this sprinkler. In general, the results showed that increasing wind speed increases the losses of evaporation and wind. Also, this study suggested that changing the irrigation time in areas with hot and dry days, from day to night in summer, leads to a significant reduction of the wind drift and evaporation losses.
Authors:Pandiaraj Karthigai Priya and Sankararajan Vanitha
decreases with increasing elevated temperature. The vaporpressure occurs due to the evaporation of the adsorbed and capillary water when the temperature is between 25 and 200 °C and thereby it tends to reduce the strength of the concrete [ 12 ]. The
Authors:G. Lizia Thankam and Neelakantan Thurvas Renganathan
cracks and explosive spalling. Lower porosity and dense microstructure are responsible for the poor behavior of MK concrete at elevated temperatures. Due to the vaporpressure in dense pore structure, explosive spalling was observed between 450 and 500 °C
Authors:Ágnes Kun, Csaba Bozán, B. Mária Oncsik, and Károly Barta
, Benyon R.G. , Theiveyanathan S. , Criddle R.S. , Smith C.J. & Falkiner R.A.
1998 . Response of effluent-irrigated Eucalyptus grandis and Pinus radiate to salinity and vaporpressure deficits . Tree Physology