Firouzabad Institute of Higher EducationAnnals of Optimization Theory and Practice2588-36663420201201Comparative analysis between network systems with standby components113512096610.22121/aotp.2020.255364.1049ENIbrahimYusufDepartment of Mathematical Sciences, Bayero University, Kano, Nigeria0000-0002-4849-0163Surajo MahmudUmarDepartment of Mathematical Sciences, Bayero University, KanoKabiruSuleimanDepartment of Mathematics, Yusuf Maitama Sule University, KanoJournal Article20201101This paper analyzes the reliability of serial network systems. Two probabilistic models are discussed in this paper. Model I is a serial network device consisting of three A, B and C subsystems, with a C subsystem consisting of three out of six elements. Model II is a serial network system consisting of three subsystems A, B and C, with subsystem C consisting of 2-out-of-6 components. The failure and repair time of the running and standby components is believed to be exponentially distributed. The system of first-order linear differential equations is developed and resolved to obtain explicit expressions for steady-state availability and mean failure time for each model. In addition, both numerical and theoretical comparisons were conducted. Results have shown that Model II was the best in terms of availability, mean time failure and cost benefit ratiohttp://aotp.fabad-ihe.ac.ir/article_120966_e5ef4d9d4efebe8d34c0e46165d91602.pdf