Experimental Study On Escape Behavior And Evacuation Law Of Mice Crowd In Emergency Situation

In recent years,with the large-scale population gathering in cities,crowd accidents have occurred frequently around the world.In emergencies,especially in the case of fires,how to effectively evacuate people in a limited space has been a topic of widespread concern to scholars at home and abroad.The research on the escape behavior and evacuation of the crowd in an emergency situation,especially the evacuation of personnel at the exit in a limited space,has gradually developed.The collective behavior in emergency situation is very complicated,including the interaction of the individual with the surrounding environment,the physical pushing behavior between the individual and the individual,following behavior,competitive behavior,and modesty behavior.Among many research methods,the simplification and hypothesis of the establishment of the mathematical model on the evacuation system,the limitation of the stimulus conditions in the real-life exercise experiment,and the difficulty in reproducing the emergency emotions have made the results of some people's emergency evacuation research controversial.Therefore,many previous conclusions still need to be explained and proved by a variety of research methods.In recent years,the evacuation experiments of animal groups in emergency situations,have been widely accepted to descovery the general rules of collective movement in nature by scholars in various countries.Among these animals,mice are considered to be good substitutes for humans because of their good similarity to humans in terms of physical structure and stress response.This paper first analyzed the research status of crowd evacuation in emergency.Based on the lack of description of the training process of establishing mice evacuation model in previous reports,we studied the training method of mice evacuation to optimize training effect and improve training efficiency.From another perspective,we can provide technical guidance for related research in establishing experimental model of mice evacuation.Next,the well-trained mice were applied to conduct experimental evacuation to study the effect of exit width on evacuation in emergency of mice stimulated by smoke.Then,the effect of exit location as well as exit width on the evacuation of mice under different levels of smoke stimulation were demonstrated.To study the acquisition of escape skills of mouse in evacuation training,we analyzed the time evolution of mice evacuation in the training and testing states,the time interval and its frequency distribution of successive escape mice,and the individual trajectories of mice.The results showed that the training was beneficial to the mice to gradually obtain escape skills,and two-day training can help the mouse's escape skills have a significant development on time scale.Training made the trajectories of the mice clearer,and made mice go straight obviously to the exit.But,sometimes the competition between individuals aggravated the tortuosity of the trajectory.In the two-day training,the mice in G30,not G12,were found to gradually produce aggregation behavior and pushing behavior.The memory of mice on escape skills was maintained for more than three weeks.It was worth noting that the large-scale group G80 has shown a transition from "faster is faster" effect based on individual escape experience to "faster is slower" effect based on individual competition.Therefore,when establishing an experimental evacuation model of mice,an appropriate group size and training program should be designed in combination with device size and research purpose.At the same time,the variations of time and trajectory angle of these groups with different size suggested that we should conduct multi-angle analysis on the experimental results of evacuation.About the effect of exit width on evacuation of mice in emergency situation,the results showed that the total evacuation time of the mice gradually increased with the increase of exit width,but the increase was slowed down when the exit increases to a certain width.Based on the phased changes of the trend of time evolution curve,we divided the mice evacuation process into three stages.We found that the changes were related to the exit width.The frequency of time interval between two consecutive escaped mice changed from a lognormal distribution to an exponential decay distribution as the exit width increased.The population density of mice near the exit first peaked with the progress of evacuation and then gradually decreased over time.As the width of the exit increases,the peak density of the higher density state and its duration gradually decreased.In addition,this paper analyzed the relationship between cluster size and cluster flow rate under different scenarios.Regarding the effect of exit location on emergency evacuation of mice,the results indicated that the occupied position of mouse in the arch near the exit had an important influence on its escape order.At the middle-exit,the location close to the wall facilitated the mouse to escape preferentially;At the corner-exit,the location near the wall and the body direction facing the opening direction of exit facilitated the mouse to escape preferentially.At low stimulation level,the narrow middle-exit was more effective at increasing the flow rate of mice than the narrow corner exit.However,the opposite result occured when the exit was widened.We attempted to explain the phenomenon through the "corner propensity" of the mouse.At high stimulation level,the effects of exit location on mice evacuation efficiency tended to diminish,which suggested that high stimulation conditions or competitive environments may "mask" evacuation efficiency due to differences in exit width and location.Therefore,this paper proposed that in order to optimize the efficiency of croed evacuation in emergency by changing the geometric design of the bottleneck region of the limited space,it was necessary to comprehensively analyze the specific stimulus conditions in combination with the emergency situation.The research in this paper made full use of the similarity between mice and human body in terms of physical characteristics and stress response to avoid the simplification and distortion of biological factors in traditional mathematical models.The evacuation of mice can avoid personal body risk in real panic and distortion of emotions of actors,as well as moral constraints and legal disputes.At the same time,the experimental conditions were controllable,the experiment was simple,the cost was low,and the feasibility was strong.The experimental results in this paper provided basic data support for the study of escape behavior and evacuation patterns of mice in emergencies.Besides,by comparing with other research methods or related research results,it can help to deepen our understanding of the laws of collective behavior in nature,and demonstrate the advantages and significance of using mice for evacuation experiments.Furthermore,the exploration of exit design in this paper can provide inspiration for the optimization of exit design for specific places,especially those with limited space.