The convergence line caused by sea-land breeze and the topographic forcing effect are the main mechanism that triggers the low-trough type hail in Hainan.
It points out that the position of the maximum strain, stress and tension is at first group trough type roller, not at passing poion of pulley if the head drum works as pulley.
The trough type liquid distributor is the main part of packing tower for large scale refined unit.
There are two basin sediment types: the platform type and trough type.