Fig. 7
From: Energy-efficient renewable scheme for rechargeable sensor networks
The energy behavior of node i during the nth and (n + 1)th charging period. Ti′ is defined as the visiting and charging interval of i, which is the time interval between two adjacent arrivals at i by MCV. In ERSVC, the MCV only visits and charges a portion of nodes in each cycle, and the visiting set in each cycle is different. Therefore, the moment when MCV arrives at i is different every time, and the visiting interval Ti′ is variable. In Fig. 7, ai is the moment when MCV arrives at node i in the (n + 1)th charging period. After the time of ti, the MCV charges the battery of node i to Emax. Apparently, the slope is (U−pi) when the MCV is charging node i and the slope is pi at other times