Soil infiltration based on bp neural network and grey relational analysis

Soil infiltration is a key link of the natural water cycle process. Studies on soil permeability are conducive for water resources assessment and estimation, runoff regulation and management, soil erosion modeling, nonpoint and point source pollution of farmland, among other aspects. The unequal influence of rainfall duration, rainfall intensity, antecedent soil moisture, vegetation cover, vegetation type, and slope gradient on soil cumulative infiltration was studied under simulated rainfall and different underlying surfaces. We established a six factor-model of soil cumulative infiltration by the improved back propagation (BP)-based artificial neural network algorithm with a momentum term and self-adjusting learning rate. Compared to the multiple nonlinear regression method, the stability and accuracy of the improved BP algorithm was better. Based on the improved BP model, the sensitive index of these six factors on soil cumulative infiltration was investigated. Secondly, the grey relational analysis method was used to individually study grey correlations among these six factors and soil cumulative infiltration. The results of the two methods were very similar. Rainfall duration was the most influential factor, followed by vegetation cover, vegetation type, rainfall intensity and antecedent soil moisture. The effect of slope gradient on soil cumulative infiltration was not significant.

El origen de la construcción fenomenalista: Mach, Moore y Whitehead

It's usually believed that the idea of applying logical methods to constructivist phenomenalism was, --in general- a result of Russell's originality. In this paper is argued that some important ideas were in fact due to Mach, Moore and Whitehead. According to the author, Russell got from Mach the general idea of epistemology as an analysis of scientific concepts and, specially,the idea of sensations as the building blocks for his logical construction. Moore made Russell believe that only sensations are known in a direct way, and so, the existence of external objects as the cause of our perceptions is only inferred. Moreover, according to the author, Russell's views on sense data -his sensibilia- are also due to Moore. Finally, Russell got from Whitehead the idea of the phenomenical reconstruction as an alternative to the causal theory of perception, and also how the logical construction should be done. The author undertakes also a detailed analysis of some early works of Whitehead not very well known.