This relation reveals that for x=0, a becomes equal to 125 making length of major axis of the each ellipse to 2a=250. x is subsequently changed to 20 and 40 making a=133 and 140. The resulting ellipses are shown in Figure 4. In this type of mobility vertex length a=140 and co-vertex length b=50 are used. In order to calculate time period of a node it is necessary to have knowledge of perimeter (circumference) of an ellipse. There is no straightforward formula to calculate this and following infinite series is utilized. (22c)p=π(a+b)∑n=1∞0.5n2hn