Lu Zhixiong

Fractal dimensions of soil strengths for paddy fields in China

Abstract Spatial variation of soil strengths for paddy fields in China was described using the concept of fractals. Soil strength was recorded with a cone penetrometer, along a series of transects, at 10 cm intervals. Fractal dimensions were calculated both from semi-variograms and from power spectral density (PSD) curves of soil strength profiles. In paddy fields after harvesting, such data gave fractal dimensions very close to 2, reflecting the characteristic nature of such paddy soils. This value implies that they were almost totally random, irrespective of site, date, direction or location of measurements. The values of fractal dimensions close to 2 corresponds to poor vehicle performance.

Correlation dimension of paddy soil strength in China

Abstract Embedding phase space Rm is reconstructed from the spatial series g(x) of cone indices measured in two paddy fields near Nanjing, China. The correlation dimension D2m for each field is derived from the correlation integral Cm(r) and the neighbours distance r in log–log scale. Results show D2m increases as m, and tends to 5.0, which expresses the estimate of correlation dimension for each soil strength profile measured.

Prediction of paddy soil normal adhesion to steel surfaces by fuzzy logic

Abstract Numerous data concerning paddy soil composition, water content and soil-steel normal adhesion were collected in South China during 1974–1983. The fuzzy logic relation of adhesion with clay content and water content was derived, by which paddy soil adhesion to steel surfaces was predicted if soil composition and water content were known.