The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with ...The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.展开更多
The configuration-bias-vaporization Monte Carlo simulation method developed by Yan et al . has been used to simulate the phase equilibria of AB random copolymers based on the close-packed Flory-Huggins lattice model. ...The configuration-bias-vaporization Monte Carlo simulation method developed by Yan et al . has been used to simulate the phase equilibria of AB random copolymers based on the close-packed Flory-Huggins lattice model. Random copolymers are represented as linear chains consisted of r A segment A and r B segment B with segment-segment attractive interaction energy parameters ε AA / kT=-1.0/T *, ε AB / kT=-0.8/T * and ε BB / kT=-0.6/T *. The phase diagrams of random copolymers with a chain length up to 200 segments are obtained. The corresponding critical points for different chain lengths with fixed chain composition are also calculated.展开更多
A Monte Carlo simulation algorithm of polymer was proposed, which was similar to the cooperative motion algorithm in literatures. In this algorithm several segments of the polymer can move cooperatively, this may be i...A Monte Carlo simulation algorithm of polymer was proposed, which was similar to the cooperative motion algorithm in literatures. In this algorithm several segments of the polymer can move cooperatively, this may be interpreted as the effect of tensile force in the polymer chain. Its dynamic behavior is in agreement with the Rouse theory, so it can be used as a dynamic Monte Carlo simulation algorithm.展开更多
文摘The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.
文摘The configuration-bias-vaporization Monte Carlo simulation method developed by Yan et al . has been used to simulate the phase equilibria of AB random copolymers based on the close-packed Flory-Huggins lattice model. Random copolymers are represented as linear chains consisted of r A segment A and r B segment B with segment-segment attractive interaction energy parameters ε AA / kT=-1.0/T *, ε AB / kT=-0.8/T * and ε BB / kT=-0.6/T *. The phase diagrams of random copolymers with a chain length up to 200 segments are obtained. The corresponding critical points for different chain lengths with fixed chain composition are also calculated.
文摘A Monte Carlo simulation algorithm of polymer was proposed, which was similar to the cooperative motion algorithm in literatures. In this algorithm several segments of the polymer can move cooperatively, this may be interpreted as the effect of tensile force in the polymer chain. Its dynamic behavior is in agreement with the Rouse theory, so it can be used as a dynamic Monte Carlo simulation algorithm.
