Dynamic performance of heavy-haul combined train applying emergency braking on straight line

A heavy-haul train-track coupled model is developed. Taking the emergency braking of the 2×104 t combined train as example, the train longitudinal impulse, the coupler dynamic behaviors and wheel-rail interactions of vehicles distributing in the different positions are analyzed. The results indicate that under the coupler compressing forces, the couplers of middle locomotives may tilt to the free swing limits, which induces the unidirectional tilt of their connected wagon couplers. Consequently, the coupler longitudinal forces produce the lateral components, and then affect the wheel-rail dynamic interaction. The performance of the middle locomotive and their neighboring freight wagons deteriorate significantly, becoming the most dangerous parts in the combined train. The wagons disconnecting with the locomotives can basically keep their couplers to stabilize in the centering positions, even though the maximum coupler longitudinal force acts on it. And its corresponding running safety also has little changes.

Dynamic Responses of A Semi-Type Offshore Floating Wind Turbine During Normal State and Emergency Shutdown

This paper addresses joint wind-wave induced dynamic responses of a semi-type offshore floating wind turbine（OFWT） under normal states and fault event conditions. The analysis in this paper is conducted in time domain, using an aero-hydro-servo-elastic simulation code-FAST. Owing to the unique viscous features of the reference system, the original viscous damping model implemented in FAST is replaced with a quadratic one to gain an accurate capture of viscous effects. Simulation cases involve free-decay motion in still water, steady motions in the presence of regular waves and wind as well as dynamic response in operational sea states with and without wind. Simulations also include the cases for transient responses induced by fast blade pitching after emergency shutdown. The features of platform motions, local structural loads and a typical mooring line tension force under a variety of excitations are obtained and investigated.

A Dynamic Emergency Decision-Making Method Based on Group Decision Making with Uncertainty Information

In emergency decision making(EDM),it is necessary to generate an effective alternative quickly.Case-based reasoning(CBR)has been applied to EDM;however,choosing the most suitable case from a set of similar cases after case retrieval remains challenging.This study proposes a dynamic method based on case retrieval and group decision making(GDM),called dynamic casebased reasoning group decision making(CBRGDM),for emergency alternative generation.In the proposed method,first,similar historical cases are identified through case similarity measurement.Then,evaluation information provided by group decision makers for similar cases is aggregated based on regret theory,and comprehensive perceived utilities for the similar cases are obtained.Finally,the most suitable historical case is obtained from the case similarities and the comprehensive perceived utilities for similar historical cases.The method is then applied to an example of a gas explosion in a coal company in China.The results show that the proposed method is feasible and effective in EDM.The advantages of the proposed method are verified based on comparisons with existing methods.In particular,dynamic CBRGDM can adjust the emergency alternative according to changing emergencies.The results of application of dynamic CBRGDM to a gas explosion and comparison with existing methods verify its feasibility and practicability.