Abstract:This paper investigates the potential of M5 model tree based regression approach to model daily reference evapotranspiration using climatic data of Davis station maintained by California irrigation Management Information System (CIMIS). Four inputs including solar radiation, average air temperature, average relative humidity, and average wind speed whereas reference evapotranspiration calculated using a relation provided by the CIMIS was used as output. To compare the performance of M5 model tree in predicting the reference evapotranspiration, FAO-56 Penman-Monteith equation and calibrated Hargreaves-Samani relation was used. A comparison of results suggests that M5 model tree approach works well in comparison to both FAO-56 and calibrated Hargreaves-Samani relations. To judge the generalization capability of M5 model tree approach, model created by using the Davis data set was tested with the datasets of four different sites. Results from this part of the study suggest that M5 model tree could successfully be employed in modeling the reference evapotranspiration. Further, sensitivity analysis with M5 model tree approach suggests the suitability of solar radiation, average air temperature, average relative humidity, and average wind speed as input parameters to model the reference evapotranspiration

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Despite numerous works reporting on oxygen transfer by plunging jets, few studies have been carried out on multiple plunging jets. In this paper, the volumetric oxygen-transfer coefficient and oxygen-transfer efficiency of multiple plunging jets in a pool of water for different configurations in terms of varying numbers of jets and jet diameters were studied experimentally. This research suggests that the volumetric oxygen-transfer coefficient and oxygen-transfer efficiency of the multiple plunging jets for air/water systems were significantly higher than those of a single plunging jet for same flow area and other similar conditions. A relationship between the volumetric oxygen-transfer coefficient and jet parameters is also proposed. The suggested relationship predicted the volumetric oxygen-transfer coefficient for single and multiple plunging jet(s) within a scatter of ±15%.

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