Fig. 2
From: Energy-efficient renewable scheme for rechargeable sensor networks
The charging period of node i in WSN. For each node i, the MCV charges i periodically with a mean period time of Ti. Ti is set to be an integral multiple of T. The blue and white blocks indicate that i will be charged and not be charged in this cycle, respectively. Ti′ is the visiting and charging interval of i, which is defined and explained detailly in the discussion section