Notice of RetractionRisk assessments for a certain directed tree network system

Notice of Retraction

After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE´s Publication Principles.

We hereby retract the content of this paper. Reasonable effort should be made to remove all past references to this paper.

The presenting author of this paper has the option to appeal this decision by contacting TPII@ieee.org.

System reliability models play an important role in the reliability engineering. In order to meet the application, so far there are more than one hundred models. With the development of modern complex networks, reliability is an important criterion due the fact that failure of these networks affects its users adversely The directed tree network system is one of many network systems which are used widely, such as the urban water supply system, a simple picking system and multi-stage transportation system. In this study, a certain directed tree network system by considering their components lifetime distribution possessing general forms is introduced which with two kinds of failure categories: fail-safe states and fail-dangerous states. The component of the system works by the order of the each vertex´s path set. With the system become more and more complicated and larger, the risk of the system has become a hot topic. The risk analysis is one of effective method. To a certain directed tree network system, the formulae for some risk measures are presented in this paper.