Weathering Characteristics of Sloping Fields in the Three Gorges Reservoir Area, China

For the purpose of understanding the weathering characteristics of surface layers in purple mudstone sloping fields of the Three Gorges Reservoir area of China, oxide content of major elements, composition of clay minerals, magnetic susceptibility, and difference in weathering characteristics of surface layers under different slope gradients were determined. The results showed that the oxide content of Si, Al, and Fe ranged from 60% to 75% and the weathering coefficient with depth showed no trend along the slope gradient. Also, for gentle (10° and 15°) and intermediate (25° and 40°) slopes the clay relative diffraction peak for kaolinite at the surface between 0-10 cm and 10-20 cm declined with an increase in slope gradient, while the relative diffraction peak for kaolinite in weathered layers on steep slopes (50° and 60°) disappeared altogether. Magnetic susceptibility decreased with increasing depth and, for a given depth layer, decreased with an increase in slope gradient. Analysis of the oxide content, weathering coefficients, clay minerals, and magnetic susceptibility showed that in the Three Gorges Reservoir area, the pedogenesis of the weathering layer in purple mudstone sloping fields was weak with weaker soil formation going from gentle slope to steep slope.

Effect of Soil Erosion on Productivity of Sloping Field in a Micro-plot Experiment

[Objective] This study aimed to explore the effects of soil erosion on the productivity of sloping field. [Method] Through removing of and covering with topsoil in a micro-plot experiment, the effect of soil erosion on productivity of sloping field was studied. [Result] The results showed that there was extremely significantly posi- tive correlation between the thicknesses of covered topsoil with either the yield of maize seeds or the yield of maize stalks, which indicated that the yields of maize seeds and maize stalks decreased extremely significantly with the increase of the amount of surface soil loss caused by erosion on the sloping field. The yields of maize seeds and maize stalks decreased by 29.62% and 24.46% respectively in the treatment with removal of a 15 cm thick layer of mature topsoil in the plow layer; the yields of maize seeds and maize stalks decreased by 17.31% and 20.14% re- spectively in the treatment with removal of a 10 cm thick layer of mature topsoil in the plow layer; the yields of maize seeds and maize stalks decreased by 12.69% and 11.51% respectively in the treatment with removal of a 5 cm thick layer of ma- ture topsoil in the plow layer; the yields of maize seeds and maize stalks increased by 10.00% and 9.35% respectively in the treatment with covering with a 5 cm thick layer of mature topsoil in the plow layer; the yields of maize seeds and maize stalks increased by 15.77% and 16.19% respectively in the treatment with covering with a 10 cm thick layer of mature topsoil in the plow layer; the yields of maize seeds and maize stalks increased by 17.69% and 25.18% respectively in the treat- ment with covering with a 15 cm thick layer of mature topsoil in the plow layer. [Conclusion] This study provides a basis for assessing the effect of soil erosion on sloping field.

An applied research on remote sensing classification in the Loess Plateau

Dae to complex terrain of the Loess Plateau, the classification accuracy is unsatisfactory when a single supervised classification is used in die remote sensing investigation of the sloping field. Taking the loess hill and gully area of northern Shaanxi Province as a test area, a research was conducted to extract sloping field and other land use categories by applying an integrated classification. Based on an integration of supervised classification aad unsupervised classification, sampling method is remarkably unproved. The results show that the classification accuracy is satisfactory by the method and is of critical significance in obtaining up-to-date information of the sloping field, which should be helpful in the state key project of converting farmland to forest and grassland on slope land in this area. This research sought to improve the application accuracy of image classification in complex terrain areas.

Effects of gully terrain on stress field distribution and ground pressure behavior in shallow seam mining

This study proposes a novel approach to study stress field distribution and overlying ground pressure behavior in shallow seam mining in gully terrain.This approach combines numerical simulations and field tests based on the conditions of gully terrain in the Chuancao Gedan Mine.The effects of gully terrain on the in situ stress field of coal beds can be identified by the ratio of self-weight stress to vertical stress(η) at the location corresponding to the maximum vertical stress.Based on the function η =j(h),the effect of gully terrain on the stress field of overlying strata of the entire field can be characterized as a significantly affected area,moderately affected area,or non-affected area.Working face 6106 in the Chuancao Gedan Mine had a coal bed Jepth <80 m and was located in what was identified as a significantly affected area.Hence,mining may cause sliding of the gully slope and increased loading(including significant dynamic loading) on the roof strata.Field tests suggest that significant dynamic pressures were observed at the body and foot of the gully slope,and that dynamic loadings were observed upslope of the working face expansion,provided that the expanding direction of the working face is parallel to the gully.

A Study of Soil Nutrients in the Terrace Field Changed from Mountain Slope in Three Gorges Reservoir Region

In order to accurately grasp the soil fertility in Three Gorges Reservoir Region after changing mountain slope into terrace field,we take Wushan County for example,and use the spatio-temporal substitution method to analyze the soil nutrient status and trend about the terrace field changed from mountain slope under different length of implementation.The results show that the soil fertility is generally low in the study area,and according to the soil nutrient grading standards in the second national land survey,the average content of total nitrogen,available potassium,organic matter and available phosphorus reaches Standard III,Standard III,Standard IV and Standard V,respectively,and the spatial heterogeneity of soil nutrients is small.Compared to the sloping land,the terrace field changed from mountain slope has increasing soil nutrients on the whole with the length of farming.The mean of various indicators about soil nutrients in the terrace field changed from mountain slope for 2 years is lower than in the sloping land,and there is the biggest difference in soil fertility,while the mean of various indicators about soil nutrients in the terrace field changed from mountain slope for 14 years shows a linear upward trend,and the difference in soil fertility decreases.

A laterally graded junctionless transistor

This paper proposes a laterally graded junctionless transistor taking peak doping concentration near the source and drain region, and a gradual decrease in doping concentration towards the center of the channel to improve the I OFF and I ON/I OFF ratio. The decrease of doping concentration in the lateral direction of the channel region depletes a greater number of charge carriers compared to the uniformly doped channel in the OFF-state,which in turn suppresses the OFF state current flowing through the device without greatly affecting the ON state current.