Analysis And Control On Collapse Process Of Complex System

With the development of scientific technology and social economy,many complex systems in our life become more and more complicated.These complex systems are unavoidably disturbed by external and internal perturbations.Once one or more subsystems can not operate normally and collapse,due to interaction among subsystems, disaster caused by initial collapsed subsystems will spread in the whole system,which may cause the whole system lose its function and collapse.The cases of immense loss caused by complex system collapse are numerous,so in-depth studies on complex system collapse are very important.By use of control theories,system theories and complex network theories,collapse process of complex system has been analyzed.Main works of this dissertation are summarized as follow:(1)A methodical approach has been proposed to analyze the collapse process of complex system.According to the cases of complex system collapse in our life,collapse process characteristics have been summarized and the process can be divided into two stages:Initial Collapse Stage and Collapse Spreading Stage.In the Initial Collapse Stage, environmental factors and some subsystems together cause initial collapse.By use of control theories and system theories,a method has been introduced to analyze this stage. In the Collapse Spreading Stage,disaster caused by initial collapsed subsystems spreads in the whole systems.According to the characteristics of this stage,by use of complex network theory,a formal description model has been given to describe this stage.Finally, Taking the China-Jiaoji Railway Accident as an example,all factors causing the initial collapse(Derailment of Train T195 ) have been identified and many improvement measures have been proposed.In addition,the disaster spreading mechanism(Collision between Train T195 and Train 5034 after Train T195 collapsed) has also been modeled.(2)A discrete state model has been proposed to analyze the Collapse Spreading Stage. States of many complex systems in our life are discrete,and for many continuous-state complex systems whose evolving mechanisms are unclear,system states can be also considered as discrete values so that some results can be still found for these systems. Based on the characteristics of these systems and the formal description model for Collapse Spreading Stage,a discrete state model has been proposed.For this model, several kinds of analytical method have been introduced,and then effects of model parameters,system topologies and topological complexity on collapse spreading process have been analyzed.Finally,several strategies have been formulated to control the spreading process and their effectiveness has been also discussed.(3)A continuous-state model has been proposed to analyze the Collapse Spreading Stage.States and evolving processes of many complex systems in our life are continuous. Based on the formal description model and several existing continuous-state models,a continuous-state model considering redundant systems has been proposed.For this model, effects of model parameters,redundant strategies and topological complexity on collapse spreading processes have been discussed,and from the point of view of mobilizing external resources,several emergent strategies used to control collapse spreading have been formulated and their effectiveness has also been discussed.(4)Taking the interdependent critical infrastructures as an example,a methodological approach has been proposed to analyze their collapse spreading process.Among all types of infrastructures,for gas pipeline network,each subsystem state is affected by its neighboring subsystems,which satifies the formal description model.But for power network,each subsystem state is affected by all other subsystems and system topology, which can not be modeled according to the formal description model.Taking interdependent power network and gas pipeline network as an example,by means of simulation,the Collapse Spreading Stage has been analyzed and the interdependent effects have been mainly discussed.In addition,several control strategies have been formulated and their effectiveness has also been discussed.