∗Shahid Beheshti University, a khodadadi@sbu.ac.ir ... with an elementary probability and statistics background and some ... Jandhyala, Venkata K. and Al-Saleh, Jamal A. (1999-8) ... variable with probability density function (p.d.f.) f and mean residual life ... Journal of the American Statistical Association, 73, 744-745.. the network theory and lavish real data sets, network scientists have d..