A series of resins were synthesized using a range of bio-based materials to control the molecular architecture, and therefore the properties, of the inventive resins. Brush holder assemblies including a mounting block and a brush holder are disclosed. Upon satisfaction of an auto engine stop condition that the engine power demand Pe* decreases below a preset reference power Pref, the engine is controlled to be driven at idle. The primary plate includes a flux concentrating cylinder extending out therefrom. The method in the present invention requires no ditching and pitting, thus preserves the original topographic layer of a desert or arid land, and then can be widely used for its high survival rate and excellent vegetation performance. This invention is used to replace the Road Tests currently implemented by the service carriers for determining actual service coverage.