Analytic Representation of the Optimal Flow for Gravity Irrigation

The aim of this study is the deduction of an analytic representation of the optimal irrigation flow depending on the border length, hydrodynamic properties, and soil moisture constants, with high values of the coefficient of uniformity. In order not to be limited to the simplified models, the linear relationship of the numerical simulation with the hydrodynamic model, formed by the coupled equations of Barré de Saint-Venant and Richards, was established. Sample records for 10 soil types of contrasting texture were used and were applied to three water depths. On the other hand, the analytical representation of the linear relationship using the Parlange theory of infiltration proposed for integrating the differential equation of one-dimensional vertical infiltration was established. The obtained formula for calculating the optimal unitary discharge is a function of the border strip length, the net depth, the characteristic infiltration parameters (capillary forces, sorptivity, and gravitational forces), the saturated hydraulic conductivity, and a shape parameter of the hydrodynamic characteristics. The good accordance between the numerical and analytical results allows us to recommend the formula for the design of gravity irrigation.

Response of Kostiakov-Lewis Infiltration Parameters to Soil Physical-Chemical Properties in the Loess Plateau of China

In order to know the main factors influence the infiltration parameters, based on the 344 sets of double-ring infiltration experiments in 101 different experimental sites in the Loess Plateau, obtained a large sample of Kostiakov-Lewis infiltration model parameters, analyzed the relationship between infiltration parameters and soil properties, established a multiple linear model, a nonlinear model and a BP neural network model to predict the infiltration parameters. The results showed that through Pearson correlation analysis, the main factors for parameter k was bulk density, soil water content of 0-10 cm, sand content, silt content and organic matter of 0-20 cm, the main factors influence parameter α was water content, sand content, silt content of 0-40 cm, and bulk density of 20-40 cm, and the main factors for parameter f0 was water content, sand content, silt content, of 0-40 cm, bulk density of 10-40 cm, and organic matter of 0-20 cm. Compared with previous studies, this paper added soil organic matter content as an independent variable to study the effect of soil chemical properties on soil infiltration capacity, which makes the model more reasonable, higher accuracy, and better prediction effect. Based on the effective test, result error analysis and comprehensive analysis, it was feasible to obtain the infiltration parameters in the Kostiakov-Lewis model using three Pedo-transfer functions. Under the condition of comprehensive consideration of forecast accuracy and stability applicability, it was recommended to use the nonlinear model as the prediction model of soil water infiltration parameters in the Loess Plateau.

Refitting of Zirconia Toughening into Open-Cellular Alumina Foams by Infiltration with Zirconyl Nitrate

The present work describes the combination of the well-established dispersion infiltration of the hollow struts in reticulated porous ceramics (RPCs) and the salt solution infiltration of the remaining strut porosity. This approach is applied on alumina foams, which are loaded subsequently with a dispersion of sub-micrometer alumina particles and a ZrO(NO3)2 solution. The zirconyl nitrate is converted into a ZrO2 transformation toughening phase during the final sintering step. As a consequence of the complex microstructure evolution during the consecutive infiltration cycles, the reinforcement phase concentrates selectively at the weak spots of RPC structures—namely, the hollow strut cavities and longitudinal cracks along the struts. As a consequence, a severe improvement of the compressive strength is observed: The average compressive strength, normalized to a porosity of 91.6 vol.%, is 1.47 MPa for the Al2O3/ZrO2 infiltrated foams, which is an improvement by 40% with respect to alumina-only loaded foams (1.05 MPa) or by 206% compared to uninfiltrated alumina RPCs (0.48 MPa). The compressive strength results are correlated to infiltration parameters and the properties of the infiltration fluids, for example the rheological behavior and the size of the Zr solute species in the respective ZrO(NO3)2 solution.