Effect of computer workstation height on EMG distribution over the trapezius muscle

Considering that the study on the mixed fusion pebble beds has been rarely conducted, in this paper the discrete element method (DEM) was used to report the mechanical behaviors and elastic moduli of mixed pebble beds which contain two kinds of solid materials. Several combinations of two kinds of solid materials were studied including the mixed Li2O-Li4SiO4, Li2O-Li2TiO3 and Li4SiO4-Li2TiO3 pebble beds. The effect of cyclic pressure p and the subtle difference in particle sizes within the granular system were considered. In this study, we observed that the stiffness of the mixed granular system falls in between the system consisting of softer solids and that consisting of stiffer solids as expected. We also observed that cyclic pressure (mechanical excitation) would stiffen the mixed granular system, but this effect will become smaller as the cycle number increases. This indicates that the stability of system will become stronger under this effect. Besides, the subtle difference in grain sizes was observed to soften the system although it caused a little higher packing density.