Location Optimization Of Evacuation Points Based On Crowd Convenience

In recent years,natural disasters such as earthquakes,typhoons,rainstorms,and mudslides,as well as the frequent occurrence of man-made disasters such as terrorist attacks and the leakage of dangerous goods,have posed great threats to the lives and property of the people,they also hindered the development of social economy in a certain extent.Therefore,the emergency evacuation of large-scale catastrophic events has aroused widespread attention from domestic and foreign governments and scientific research institutions.Scientific research about it has gradually become a hot topic in the international communities.According to the characteristics of the disastrous emergencies,this paper selects the problem of site selection in the emergency evacuation process and proposes the optimization of the evacuation gathering site selection based on the convenience of the populations.In the process of emergency evacuation,the government needs to protect the lives and property of people in hazardous areas in shortest time.Based on the convenience of the crowds,this paper considers the needs of vulnerable people walk slowly.At the same time,considering the potential safety problems of evacuation crowd crossing the road and its influence on the evacuation of traffic on the road.A bi-objective optimization model has been established whose main goal is to have the shortest total walking distance,and the secondary goal is to have the least number of crossings to major roads.Before the model is constructed,the experts grading methods was used to make a preliminary screening of the original selected candidate assembly points,the candidate assembly points with low integrated index of impact factors are removed from the original candidate set point collection to improve the evacuation efficiency in the process.When solving the model,considering the limitation of converting the bi-objective optimization model into a single-objective optimization model,the optimized genetic algorithm NSGA-II algorithm was chosen to solve it.This algorithm takes into account the elite strategy,through the design of a reasonable chromosome coding method,through the process of selection,crossover,mutation,fast non-dominated sorting,and population pruning to obtain a Pareto optimal solution with double objectives.Finally,we selected a chemical plant in Xi'gu District of Lanzhou as an example for analysis.We need to urgently evacuate the residents in the danger zone if the chemical plant exploded.We use the model and algorithm established in the emergency evacuation process.The research results of the location selection of the emergency evacuation assembly point show that the model constructed in this paper can provide a certain theoretical basis and technical support for emergency evacuation plan planning in emergency situations,and it has certain feasibility in practical application.