distributed in fine and medium sand classifications, and fractal dimensions covered a wide range from 2.0810 to 2.6351; (ii) through logarithmic transformations, fractal dimensions were significantly positive correlated with clay and silt contents (R2 = 0.81 and 0.59, P < 0.01), and significantly negative correlated with sand content (R2 = 0.50, P < 0.01); (3) hierarchical cluster analysis divided the plots into three types which were similar to sand dune types indicating desertification degree. In a large spatial scale, fractal dimensions are still sensitive to wind-induced desertification. Therefore, we highly recommend that fractal dimension be used as a reliable and quantitative parameter to monitor soil environment changes in desertified regions. This improved information provides a firm basis for better understanding of desertification processes.

characteristics of pneumatic cylinders and to clarify the friction phenomenon of the pneumatic cylinders, this study describes friction force measurement tests to measure the friction force of pneumatic cylinder, under both dry and lubricated conditions. Experimental equipments are designed to assess the effect of seals and lubrications in pneumatic cylinder, where the velocity and pressure of the driving cylinder are controlled. Measurements of friction force are shown for velocities of up to 200 mm/s. This paper provides an easy and accurate measurement system to analyze the friction characteristic of pneumatic cylinder. The data obtained will be useful for developing a suitable friction model, and the experimental apparatus will facilitate the study of the effects of different types of seals and lubricants on friction force.