中文摘要：

jtwang@bjtu. edu. cn Jinting Wang is a full professor at Beijing Jiaotong University. He received his Ph.D. Degree in Operations Research and Cybernetics from Chinese Academy of Sciences （CAS） in 2000. His research interests include issues related to queueing theory, reliability and applied probability. He is author or co-author of several publications in Queueing Systems： Theory and Applications （QUESTA）, Journal of Multivariate Analysis, European Journal of Operational Research, etc. Peng-Feng Zhou is a Master student in the Department of Mathematics, School of Science at Beijing Jiaotong University. He received his B.Sc. in Mathematics from Beijing Jiaotong University. His research area includes retrial queues and reliability.