[1
]College of Economics and ManagementBeijing University of TechnologyBeijing China
[2
]School of Software EngineeringBeijing University of Posts and TelecommunicationsBeijing
China
[3
]Key Laboratory of Trustworthy Distributed Computing and ServiceMinistry of Education,
Beijing University of Posts and TelecommunicationsBeijing China
[4
]Department of Software Engineering, School of Information Sciences and EngineeringShaoguan
UniversityShaoguan China