Probabilistic collocation method for uncertainty analysis of soil infiltration in flood modelling

The probabilistic collocation method (PCM) based on the Karhunen-Loevè expansion (KLE) and Polynomial chaos expansion (PCE) is applied for uncertainty analysis of flood inundation modelling. The floodplain hydraulic conductivity (KS) is considered as one of the important parameters in a 2-dimensional (2D) physical model FLO-2D (with Green-Ampt infiltration method) and has a nonlinear relationship with the flood simulation results, such as maximum flow depths (hmax). In this study, due to the spatial heterogeneity of soil, log-transformed Ks was assumed a random field in spatiality with normal distribution and decomposed with KLE in pairs of corresponding eigenvalues and eigenfuctions. The hmax random field is expanded by a second-order PCE approximation and the deterministic coefficients in PCE are solved by FLO-2D. To demonstrate this method, a simplified flood inundation case was used, where the mean and variance of the simulation outputs were compared with those from direct Monte Carlo Simulation. The comparison indicates that PCM could efficiently capture the statistics of flow depth in flood modelling with much less computational requirements

Segregation of copper in an Fe–Cu alloy under pulsed electric current

Effect of electric current on the segregation of copper precipitates in the Fe–13.6Cu alloy is evaluated. Results of this approach present two stages of segregation, namely, grain-boundary segregation during the solidification and interphase-boundary segregation during the decomposition of a solid solution. The segregation becomes apparent not only because the thermodynamic barrier for segregation is decreased, but also because the diffusion is greatly enhanced. Based on the thermodynamic and kinetic aspects, the segregation process under electric current would be of great interest and of physical importance because this kind of electric current-induced segregation was much stronger than the thermal diffusion segregation