Research On Formation,Evolution And Control Mechanism Of Railway Dangerous Goods Transportation System Risk

In recent years,with the increase of railway dangerous goods transportation in China,railway dangerous goods transportation system accidents occur frequently.It is of great theoretical and practical significance to study the formation,evolution and control mechanism of railway dangerous goods transportation system.In this paper,the risk formation,evolution and control mechanism of railway dangerous goods transportation system are explored by using System Theory,Coupling Theory,Pulse Theory,Quantum Mechanics,Catastrophe Theory,Bifurcation Theory and Cybernetics.The research work of this paper mainly includes the following four parts.(1)WBS-RBS approach is used to classify all possible system risk factors in the whole process of railway dangerous goods transportation;Then,from the macro-system perspective,N-K model and Entropy-TOPSIS-Coupling Coordination Model are used to analyze the interaction and coupling relationship among the risk factors based on historical statistical data.The calculation results show that:(i)The more risk factors involved in the coupling process,the greater the final risk coupling value is,the more likely safety accidents occur;(ii)The coupling process involving human and management factors has the greatest risk impact,these factors need to be controlled seriously.(iii)The comprehensive coordination degree fluctuates obviously before 2010,the system is the most unstable in 2001,and the comprehensive coordination value decreases gradually after 2010.(iv)Before 2008,the interaction among the risk factors is stronger,the degree of harmony and consistency is higher in the development process.The greater the value of coupling and coordination is,the greater probability of safety accidents is.After 2008,the degree of harmony and consistency among the coupled risk systems gradually decreases,the system gradually changes from orderly development to disorderly development,which makes the system safer.(v)The TOPSIS rank value shows that the railway dangerous goods transportation system in 2001 is the most unsafe,the system's safety fluctuates greatly every year before 2010.After 2010,the railway dangerous goods transportation system gradually becomes safe;Finally,the cause of accident,the risk factor,and the interaction and coupling between cause of accident and risk factor,are defined as risk sources of railway dangerous goods transportation system.The unsafe events of railway dangerous goods transportation system are defined as the change of material,energy and information caused by the risk source to the system.The risk curve and risk energy of railway dangerous goods transportation system accumulate continuously,not fluctuate up and down.(2)Risk source carries risk energy,which cause disturbance or perturbation to railway dangerous goods transportation system.The disturbance or perturbation caused by risk energy is defined as risk pulse.Three risk pulse models including Gauss,Cosine-Gauss and Singer-Gauss risk pulse are established.The integral of the square of risk pulse waveform function in time is defined as the risk pulse energy.Based on Fourier transform and Euler formula,the basic physical quantities such as the amplitude spectrum,phase spectrum and energy spectrum of the risk pulse of railway dangerous goods transportation system are studied.The parameters in the models mentioned above are simulated,the simulation results show that:(i)The amplitude of the risk pulse and the energy of the risk pulse are negatively correlated with the variance,positively correlated with the equivalent loss coefficient and negatively correlated with the initial phase.(ii)The time width of the risk pulse is determined by the variance,and it is negatively correlated with the variance.(iii)The highest amplitude positon of the risk pulse is only determined by the risk pulse occurrence position on time axis.(iv)The number of Cosine-Gauss risk pulse envelopes is determined by variance and initial phase,which is positively correlated with variance and negatively correlated with initial phase.(v)For the Gauss risk pulse and Singh-Gauss risk pulse,the risk energy accumulates faster before reaching the highest amplitude position and slows down after reaching the highest amplitude position.(vi)For the Cosine-Gauss risk pulse,because of the existence of pulse envelope,the risk energy accumulates step by step.Equivalent loss coefficient combines the accident loss of the railway dangerous goods transportation system actual operation data with the risk pulse proposed in this paper,hence it plays an important role in the concept of risk pulse.After that a railway dangerous goods transportation accident happened in 2001 is conducted as case study,the equivalent loss is defined as the number of casualties caused by the risk source,the relationship among the risk pulse energy,the equivalent loss coefficient as well as variance is studied.Next the railway dangerous goods transportation system accident level is classified into four categories:special major accident,major accident,important accident and general accident.The equivalent loss and variance of all levels' accident are studied.The relationship between the equivalent loss coefficient and variance is given,and the range of the equivalent loss coefficient of each level of accident is given.Based on the simulation results of the amplitude spectrum,phase spectrum and energy spectrum of the three kinds of risk pulses,a hypothesis of the risk quantum is put forward:the risk quantum is the smallest particle that constitutes the system risk pulse.Risk quantum is in a state of constant vibration,and its vibration curve belongs to sine wave or cosine wave in frequency domain;each risk quantum has fixed amplitude,phase and energy;the joint action of risk quantums forms a risk pulse.Risk quantum satisfies all the changing laws of microphysics,such as Schrodinger equation,Dirac equation,wave-particle duality,uncertainty principle,etc.Finally,the adverse state change caused by risk pulse energy is defined as system risk.The magnitude of the system risk can be expressed by the energy carried by the risk pulse.The greater the risk pulse energy is,the greater the harm it causes to the system and the greater the system risk is.The risk formation mechanism of railway dangerous goods transportation system is presented: When the probability amplitude of risk quantum is determined,a pulse signal can be formed at a certain time.If the pulse signal is harmful to the safe operation of railway dangerous goods transportation system,it can be called as risk pulse.The release of risk pulse energy changes the structure,energy and information of the system,which results in system risk and threatens the safe and normal operation of the system.(3)Unify the risk sources,risk acceptors,risk factors/accident causes of risk source,catastrophe types in risk evolution process in a tree network structure,and this tree network structure is defined as the risk-accident tree of railway dangerous goods transportation system.Based on this,the catastrophe models of risk evolution of railway dangerous goods transportation system including Fold,Cusp,Swallowtail,Butterfly and Wigwan catastrophe models are deduced and established.The risk potential,equilibrium surface of risk evolution and bifurcation set of the five catastrophe models are analyzed.The multi-modes,sudden jumping,unreachable,divergence and hysteresis of each catastrophe model are studied.By using a railway dangerous goods transport accident in 2001,the case study of Fold and Cusp Catastrophes are presented.The Fold catastrophe simulation results show that:(i)As long as there are risk sources in the system,a risk factor/accident cause occurs,then Fold Catastrophe occurs after completing the risk pulse.The potential function curve of the system has two extreme points,the control points of the system jumps between the extreme points.(ii)The system may be initially safe,but because of the emergence of control variables with different equivalent losses,the disturbance degree of the system is different,hence the final evolution of the system may be different.The Cusp Catastrophe simulation results show that:(i)The yellow Cusp Catastrophe balance surface of the upper leaf of the railway dangerous goods transportation system is safer,the darker the color is,the safer the system is.The blue balance surface of the lower leaf indicates that the system is in a risk state,the darker the color is,the greater the risk is.The middle leaf indicates that the system state control point is not reachable,the system state control point jumps here.(ii)The energy produced by risk impulse makes the system state control point move towards the unreachable region.When the pulse curve reaches the left half of the bifurcation set,the system state control point jumps suddenly.After a sudden jump,the risk energy,structure and information of railway dangerous goods transportation system are destroyed.(iii)The Normal Factor of Cusp Catastrophe affects the width of the bifurcation set,while the Splitting Factor affects the height of the bifurcation set.The larger range of the bifurcation set is,the easier the trajectory of the risk pulse crosses with the bifurcation set.As long as the risk pulse crosses the bifurcation set,the sudden jump of Cusp Catastrophe occurs in the system.The evolution mechanism of the railway dangerous goods transportation system risk is presented: After the occurrence of risk pulse,the risk energy carried by the risk pulse has a dynamic impact on the railway dangerous goods transportation system state in the form of controlling variables and generating sudden changes.The essence of catastrophe is,the trajectory of risk impulse energy passes through the bifurcation set.The direct effect of catastrophe is,the risk value of railway dangerous goods transportation system increases suddenly,which acts on risk acceptor and attacks defense system of the system,finally it may make risk acceptor become a new risk source and generate new risk pulse.If the whole system prevention is broken through,the security accidents may occur.(4)The relationship between bifurcation set and risk control of railway dangerous goods transportation system is analyzed.From the perspective of system oscillation,the Duffing risk control equation of railway dangerous goods transportation system is established,and the bifurcation response equation of steady-state solution of the equation is deduced from two persperctives.Three control methods and their control mechanism are given,includes strengthening internal damping,reducing external excitation effect,strengthening internal damping and reducing external excitation effect of the system at the same time.The results of the case study show that:(i)All three kinds of control methods can effectively control the risk of railway dangerous goods transportation system.(ii)The method of reducing the influence of external excitation on the system risk has the least efficient,followed by the method of improving the internal damping of the system and reducing the influence of external excitation.The most efficient method is to improve the internal damping of the system.We suggest that the method of improving the internal damping of railway dangerous goods transportation system should be adopted in the actual production of risk management.The risk control mechanism of railway dangerous goods transportation system is given: Each coordination parameter ? corresponds to only one oscillation amplitude r when it changes.Because when one ? corresponds to more than one r,it means that there is a jump of the amplitude,that is,sudden change occurs in the system,which leads to unsafe state.By using the above three risk control methods,one? can be guaranteed to has only one r,that is,there is no jump of the amplitude,which can effectively suppress the sudden change in the system,thus ensuring the safety of the system operation.