The properties of the paths in an ROBDD representation of a Boolean function are presented and proved in the present paper, and the applications of ROBDD in calculating signal probability are also discussed. By this m...The properties of the paths in an ROBDD representation of a Boolean function are presented and proved in the present paper, and the applications of ROBDD in calculating signal probability are also discussed. By this method, the troublesome calculation of the correlation among the nodes, which is caused by the re-convergent fan-out in digital system, can be avoided and power estimation can be faster than simulation-based method in [1].展开更多
Fault tolerance designs are essential techniques for systems that require high levels of reliability,such as aircraft or spacecraft control system.Imperfect Fault Coverage(IFC)may lead to the failure of a system or su...Fault tolerance designs are essential techniques for systems that require high levels of reliability,such as aircraft or spacecraft control system.Imperfect Fault Coverage(IFC)may lead to the failure of a system or subsystem even with adequate redundancy.Previous studies of IFC mostly concentrated on evaluating Coverage Factor(CF),whereas the system failure behaviors with IFC have rarely been involved.Failures that occur in low-layer may be covered by highlayer.However,if the coverage is imperfect,uncovered failure will have functional and physical impact on the system behavior.In this thesis,the failure behavior and reliability of IFC of multi-layer systems are studied and a Binary Decision Diagram(BDD)-based modeling and simulation method are proposed to evaluate system reliability.As a case,the failure behavior of an aero engine electronic controller with IFC is studied.The results show that the IFC may impact system behavior without taking the IFC into account,the system maintenance intervals may reduce,and thus the maintenance costs will increase.展开更多
A new modular solution to the state explosion problem caused by the Markov-based modular solution of dynamic multiple-phased systems is proposed. First, the solution makes full use of the static parts of dynamic multi...A new modular solution to the state explosion problem caused by the Markov-based modular solution of dynamic multiple-phased systems is proposed. First, the solution makes full use of the static parts of dynamic multiple-phased systems and constructs cross-phase dynamic modules by combining the dynamic modules of phase fault trees. Secondly, the system binary decision diagram （BDD） from a modularized multiple- phased system （MPS）is generated by using variable ordering and BDD operations. The computational formulations of the BDD node event probability are derived for various node links and the system reliability results are figured out. Finally, a hypothetical multiple-phased system is given to demonstrate the advantages of the dynamic modular solution when the Markov state space and the size of the system BDD are reduced.展开更多
文摘The properties of the paths in an ROBDD representation of a Boolean function are presented and proved in the present paper, and the applications of ROBDD in calculating signal probability are also discussed. By this method, the troublesome calculation of the correlation among the nodes, which is caused by the re-convergent fan-out in digital system, can be avoided and power estimation can be faster than simulation-based method in [1].
基金funded by the National Natural Science Foundation of China(Nos.61503014 and 61573043)。
文摘Fault tolerance designs are essential techniques for systems that require high levels of reliability,such as aircraft or spacecraft control system.Imperfect Fault Coverage(IFC)may lead to the failure of a system or subsystem even with adequate redundancy.Previous studies of IFC mostly concentrated on evaluating Coverage Factor(CF),whereas the system failure behaviors with IFC have rarely been involved.Failures that occur in low-layer may be covered by highlayer.However,if the coverage is imperfect,uncovered failure will have functional and physical impact on the system behavior.In this thesis,the failure behavior and reliability of IFC of multi-layer systems are studied and a Binary Decision Diagram(BDD)-based modeling and simulation method are proposed to evaluate system reliability.As a case,the failure behavior of an aero engine electronic controller with IFC is studied.The results show that the IFC may impact system behavior without taking the IFC into account,the system maintenance intervals may reduce,and thus the maintenance costs will increase.
基金The National Natural Science Foundation of China(No.60903011)the Natural Science Foundation of Jiangsu Province(No.BK2009267)
文摘A new modular solution to the state explosion problem caused by the Markov-based modular solution of dynamic multiple-phased systems is proposed. First, the solution makes full use of the static parts of dynamic multiple-phased systems and constructs cross-phase dynamic modules by combining the dynamic modules of phase fault trees. Secondly, the system binary decision diagram （BDD） from a modularized multiple- phased system （MPS）is generated by using variable ordering and BDD operations. The computational formulations of the BDD node event probability are derived for various node links and the system reliability results are figured out. Finally, a hypothetical multiple-phased system is given to demonstrate the advantages of the dynamic modular solution when the Markov state space and the size of the system BDD are reduced.
