Experimental Study On The Impact Of Geometry Formation Abutting Bottleneck On The Evacuation Efficiency Of Mice

It is not rare to find accidents of stampede in where large number of people gathered,and this problem has not been lightened as our society develops.Therefore,it would be necessary to study how to improve the evacuation efficiency,avoiding the congestion and reduce casualties caused by such accidents when large number of people gathered.In this paper,a funnel-shaped guiding wall is set to achieve the goal of improving evacuation.The mice is chosen as the experiment object to avoid the disadvantages when using human as the object,that is to say,human can not be put in a scenario where it is actually dangerous,and that they would not perform what they would do in an emergency.There are two major scenarios of the experiment,which are evacuation research under the condition of open boundary and evacuation research under the condition of limited boundary.Two aspects of funnel-shaped guiding wall are studied for the open boundary condition,which are the intersection angle between funnels and the bottom margin and the height of the funnel,that is to say,the distance from the top of the funnel to the bottom margin.The intersection angles are set in four scenarios,which are 0°,30°,45° and 60°,and the heights of funnels are set in four scenarios,which are 5cm,10 cm,15cm and 20 cm.The time intervals between two consecutive mice passing through the bottleneck are analyzed,and four criteria are introduced to find out which scenario performs best.The conclusions are as follow:When the intersection angle is set as regular and change the height of funnels from low to high,each criterion of evacuation do not show a significant regularity,and that it would be reasonable to assume the diffrences between different scenarios are caused by randomness.On the other hand,when the height of funnel is set as regular and change the intersection angles of funnels form small to large,although in some scenarios it is not the case,it can be found that there is a trend for improving evacuation efficiency,and that apart from the criterion of fitted power-law distribution,all criterias reach the optimal value when the angle is set as 75°,so it would be reasonable to assume that the evacuation efficiency is improved as the intersection angles grow.Based on the conclusion drawn above,the impacts of height of funnels are ignored in the study on evacuation under limited boundary.Five scenarios,including funnel angles of 30°,45°,60°,80° and the benchmark are studied,and the conclusions are as follows.The evacuation efficiency grows with funnel angles when the angles are still small,and after the funnel angles get too big the evacuation efficiency falls.But when the funnel angles keep on growing,the evacuation efficiency would improve again and gain maximum at the angle of 80°.By force analysis,a hypothesis is put up why the watershed would exist.