Experiment and simulation study of emergency evacuation during violent attack in classrooms

In recent years,as a disaster,terrorist attacks have occurred throughout the world.However,emergency evac-uation behaviors during these incidents were not clear,and the traditional emergency plans were not suitable for such incidents.In this paper,evacuation behaviors under armed assault attack in a classroom were studied based on evacuation experiments.A total of 103 participants took part in three experiments.In each experiment,the attacker’s attacking route was set differently to study the impact of the attacking route on evacuation be-haviors.Pre-evacuation delay,panic of the evacuees,exit choices,evacuation time,and evacuees’trajectories in the experiments were all analyzed.The results of the experiments showed that when a terrorist attack occurs,there is a long delay before evacuation,and most of the evacuees were in the state of“observation”before they moved.When one of the participants started to evacuate or shout,other participants would begin to recognize the danger and escape quickly.These three experiments showed that the route of the attacker had a significant impact on the routes and exit choices of the evacuees.Rather than searching for the nearest exit,the primary purpose of evacuees was to keep a safe distance from the attacker.The average speed of the evacuees in these three experiments was 1.07 m/s,0.81 m/s,and 0.84 m/s,respectively.The density distribution during the crowd evacuation process was uneven,with the highest density occurring at the area from the seats to the aisles.The research can provide data support for the design of emergency plans and the computer simulation of the armed assault attack.

Does a large group of pedestrians follow the evacuation signs?An experimental study

Guidance signs are generally considered to be key in improving the efficiency of emergency building evacuations.During a group evacuation,how obedient is the group to the evacuation signs?Would different evacuation signs affect the judgment of evacuated groups?Evacuation experiments were conducted to explore the influence of evacuation signs on the path selection of evacuation groups.Fourteen classes with 514 participants participated in these experiments,and each class participated in one experiment.Six classes conducted the experiments without guidance signs,and the rest conducted the experiments with guidance signs.The influences of the sign’s color(red and green),pattern(arrow and running man),and status(whether it flashes)on the route selection were studied.The results show that(1)the evacuation signs significantly affect the route choices of the evacuated groups.(2)The herding effect during the evacuation process does not influence the guiding effect of evacuation signs.(3)Evacuation signs of different colors and patterns have different guiding effects,and the Green running man sign has the best effect.(4)The constant bright,or flashing evacuation sign corresponding to the flashing Red running man has a significant impact on the route selection of the evacuated group.The results may provide a reference for improving the emergency evacuation guidance model of office buildings or other buildings with a large flow of people and optimize ideas for the design and layout of emergency evacuation signs.

Enhanced green fluorescence and afterglow in (Zn, Mg)_2GeO_4: Mn^(2+), Cd^(2+)

Long-lasting phosphorescent （LLP） materials have attracted considerable attention since green and blue emitting persis- tent Eu2＋ doped alkaline earth phosphors were reported in the mid-1990s [1-3]. Over the past few decades, a consid- erable effort has been made to design novel LLP materials for a wide range of applications such as emergency lighting, interior decoration, road signs, and in vivo bioimaging [4-6]. For these applications, long persistence times are often desir- able. Two types of active center involved are： emitters and traps in LLP phosphors. Emitters are capable of emitting ra- diation after being excited, and their color is determined by the emission wavelength of the LLP phosphor. Traps states usually do not emit radiation, but store the excitation energy later releasing it to the emitters under thermal disturbance. Thus, traps play an important role in photo-energy storage of LLP phosphors. The trap type and trap distribution are gen- erally associated with lattice defects and/or co-dopants. The overall nature of the trap states determines the persistence in- tensity and time. Thus, design of LLP phosphors focuses on generating suitable trap levels and trap densities.