基于教室人群疏散实验的行人流建模和模拟

基于教室人群疏散实验, 从中归纳出疏散过程中行人的基本运动特征. 将桌椅分别视为不可穿越和可穿越的静态障碍物, 而行人则被当成可移动的障碍物, 这将导致背景场随人群的运动而动态更新, 因此可以更好地反映前方拥挤程度对后面人群路径选择行为的影响. 采用基于动态背景场的元胞自动机模型研究了不同桌椅排列和出口宽度的教室人群疏散过程, 给出了疏散时间的空间分布以及平均和最大疏散时间, 再现了实验中人群疏散的基本特征. 数值模拟结果表明, 疏散时间取决于桌椅的排列方式和教室出口的宽度. 对于同一种排列, 出口越小则疏散时间越长; 对于给定的出口宽度, 通常随着过道数的增加, 疏散时间随之减少; 当过道数增加且过道宽度不足以两人并行, 从两侧进入过道的行人会发生冲突, 使疏散效率有所降低; 靠近出口一侧墙壁设置过道有利于人群的疏散. 文中进一步分析了模拟与实验结果存在差异的原因.     

三维空间行人疏散的元胞自动机模型

为了有效刻画行人在三维空间中的疏散状况,结合阶梯因素提出了一种新的三维元胞自动机模型,该模型首先基于位置吸引力和碰撞可能性给出了行人移动概率的计算公式,并通过定义元胞演化过程阐述其疏散策略,同时,利用建立的仿真平台进行实验,深入分析了疏散时间、出口流率、出口宽度、初始行人密度以及系统平均速度之间的关系,以此获得更加符合实际情况的行人流特征,结果表明,疏散时间、出口流率与初始行人密度呈现正相关,而与出口宽度呈现负相关,并且系统平均速度和出口宽度对于最优疏散时间存在一个理想阈值。     

双出口房间内疏散行人流的仿真和实验研究

为研究行人疏散过程中的路径选择行为, 提出了一个基于元胞自动机的行人微观模型, 并组织了三组双出口教室内的学生疏散实验. 模型中, 行人路径选择行为受其到出口距离、前方路径通行能力和行人间排斥力影响. 通过观察实验结果, 得到一些相关现象. 利用实验结果对模型参数进行校正. 利用校正模型对该教室内疏散学生流进行仿真, 结果表明 模型能有效地刻画教室内学生流的疏散特征, 疏散时间随学生人数线性增加. 该研究有助于类似场景中行人疏散策略和方案的制定. 关键词： 元胞自动机 行人疏散 仿真 实验     

菱形网格的行人疏散元胞自动机模型

利用改进的层次域元胞自动机模型,研究了正菱形网格空间中的行人疏散问题.这类网格可以避免行人贴近房间墙壁或障碍物,转移概率考虑了各种逃生受阻因素.数值仿真显示,出口处的行人分布与实验快照展示的行人分布基本相同,疏散时间和出口宽度呈线性关系,行人流率接近实验结果.     

基于元胞自动机的行人疏散流仿真研究

基于元胞自动机对行人疏散流进行仿真研究.模型利用两个动态参数反映行人移动区域内的疏散情况,从而决定行人的行为选择.模型中行人可以根据自身周围的情况选择移动、等待行为.本文仿真研究了行人在正常疏散环境下,系统规模、疏散人数、安全出口宽度、多个安全出口布局对行人疏散时间的影响.研究结果表明,行人疏散时间随行人数量呈线性增加;随安全出口宽度呈负指数性减少;同时,多个安全出口布局的不平衡也会对行人的疏散过程和疏散时间产生一定的影响. 关键词： 元胞自动机 行人疏散流 动态参数 疏散时间     

基于元胞自动机的行人视线受影响的疏散流仿真研究

基于元胞自动机对视线受影响的行人疏散流进行仿真研究.模型根据行人视野半径将疏散空间划分为可见安全出口区域、可见墙壁区域和盲目区域;利用两个动态参数描述行人在不同移动区域内的疏散特征,从而决定行人的行为选择,包括行人定向移动、沿墙移动和正常疏散移动等行为.仿真研究了行人在墙壁上存在疏散指示标志的疏散空间内,视线受影响时采用随机定向寻墙沿墙移动疏散策略的情况下,行人视野半径对行人疏散时间的影响.研究表明,行人疏散时间不仅受行人视野半径的影响,而且还与安全出口的宽度和安全出口利用率有关.     

初始位置布局不平衡的疏散行人流仿真研究

行人初始位置布局不平衡的多安全出口疏散过程, 是行人疏散流仿真研究的热点. 利用行人流动态参数仿真模型, 在实际距离和假想距离"极大极小"路径选择机理的基础上, 改进假想距离的计算方法及其拥堵计算区域, 实现疏散过程的动态平衡; 提出行人位置布局的不平衡系数, 以描述疏散空间内行人初始位置布局的不平衡性. 从行人初始位置随机和固定布局的角度, 仿真研究正常疏散环境下行人布局的不平衡性对疏散时间的影响, 并将仿真结果与原始模型做对比分析. 研究表明, 模型能有效地实现行人流疏散过程的动态平衡, 行人疏散时间受行人位置或安全出口布局的影响较小, 而与安全出口总宽度、 行人的初始数量以及拥堵感知系数有关.     

基于介观元胞自动机的城市区域人员疏散模拟方法

传统元胞自动机疏散模型中,空间多划分为微观层面的精细网格,难以对大范围的疏散场景进行模拟.基于此,本文结合行人流的运动特征,建立了应用于大尺度人员疏散场景的人员疏散介观元胞自动机模型.该模型以道路元胞划分替代平面网格元胞划分方式,并引入"源加载"元胞加载模拟场景内疏散人员,建立元胞间状态转移方程模拟疏散过程中的人员运动.应用该模型,对高校校园进行疏散子网划分,模拟应急疏散过程并规划疏散路径,既可以对场景内宏观疏散情况进行分析,又可以观测单个元胞的状态变化.基于模拟结果,能够发现实际疏散过程中可能存在的问题,提出相应的改进指引和意见.     

雪花在非等温对流场生长过程的模拟

雪花是水蒸气在过冷环境下凝华相变形成的晶体,其生长过程涉及到多个尺度的热力学过程。本文提出了一种结合水蒸气扩散方程、热传导方程和动量守恒方程的改进的元胞自动机法,可以实现二维非等温对流场中雪花生长过程的模拟。研究结果和实验结果可以很好地吻合,验证了该模型的有效性。通过对模拟结果进行分析,研究了雪花生长过程中水蒸气分布、温度分布和对流速度对其形态的影响。     

元胞方法与蒙特卡洛方法相结合的薄膜生长过程模拟

利用仿真方法从原子尺度研究薄膜生长过程是当前薄膜研究领域的热点. 目前, 仿真方法主要在纳米尺度模型实现, 时空需求很大. 针对这一问题, 本文提出元胞和蒙特卡洛相结合的模拟方法, 实现对微米尺度模型薄膜生长过程的模拟. 利用元胞方法来实现模型表示以及演化计算, 从而降低对内存空间的要求, 提高计算效率, 并使用蒙特卡洛方法计算粒子的扩散概率. 通过对氮化硅薄膜生长过程进行具体研究, 将模拟结果与实际实验结果和分子动力学演化结果进行表面形貌和成分的比较, 验证了该方法的有效性.     

Simulation of pedestrian evacuation based on an improved dynamic parameter model

An improved dynamic parameter model is presented based on cellular automata. The dynamic parameters, including direction parameter, empty parameter, and cognition parameter, are formulated to simplify tactically the process of making decisions for pedestrians. The improved model reflects the judgement of pedestrians on surrounding conditions and the action of choosing or decision. According to the two-dimensional cellular automaton Moore neighborhood we establish the pedestrian moving rule, and carry out corresponding simulations of pedestrian evacuation. The improved model considers the impact of pedestrian density near exits on the evacuation process. Simulated and experimental results demonstrate that the improvement makes sense due to the fact that except for the spatial distance to exits, people also choose an exit according to the pedestrian density around exits. The impact factors α, β, and γ are introduced to describe transition payoff, and their optimal values are determined through simulation. Moreover, the effects of pedestrian distribution, pedestrian density, and the width of exits on the evacuation time are discussed. The optimal exit layout, i.e., the optimal position and width, is offered. The comparison between the simulated results obtained with the improved model and that from a previous model and experiments indicates that the improved model can reproduce experimental results well. Thus, it has great significance for further study, and important instructional meaning for pedestrian evacuation so as to reduce the number of casualties.     

通过博弈的室内行人疏散动力学研究

在室内行人疏散过程中,行人博弈对疏散效率有着重要的影响.本文把抵制博弈策略更新的强度定义为抵制强度. 为了研究抵制强度对疏散效率的影响, 通过在行人博弈策略更新的概率中引入抵制强度,基于元胞自动机模型数值计算在不同的行人密度, 出口宽度下疏散总时间随抵制强度变化的关系.结果表明: 室内行人疏散过程中, 抵制强度小会使得争抢行为极其容易蔓延. 当行人密度小且出口宽大时, 输入以急速疏散为主的规范信息,鼓励行人模仿优胜者更新博弈策略, 当行人密度大且出口狭小时, 输入以避让为主的规范信息抑制行人争抢,都能提高疏散效率. 最后找出不同条件下与最短疏散总时间相对应的优化抵制强度, 为提高室内行人疏散效率提供一个新的视角.     

成对行为对行人疏散动力学的影响研究

熟悉的行人之间经常存在着聚集运动的整体跟随行为现象.为了研究这种行为对疏散过程的影响,考虑了行人的并排成对、前后成对、混合成对三种方式,建立了一个新的元胞自动机模型,研究了三种成对方式对双出口房间内行人疏散过程的影响,并分析、讨论了不同参数下成对方式之间的差异. 关键词： 行人流 元胞自动机 成对疏散 计算机模拟     

Cellular Automaton Simulation of Evacuation Process in Story

Computer simulations on the evacuation process in a story are launched with cellular automaton in this article. The story is composed of five rooms and one corridor. Influence of various parameters on the evacuation process is investigated. It shows that the width of the door of rooms has little influence but the width of the corridor and the maximum velocity of the pedestrian have great influence on the time for evacuation. The relation between evacuation time and the width of corridor is found as tc ∝ W^-0.84. It is also found that appropriate shape of the room is helpful to evacuation.     

Simulation of crowd dynamics in pedestrian evacuation concerning panic contagion: A cellular automaton approach

The study of the panic evacuation process is of great significance to emergency management. Panic not only causes negative emotions such as irritability and anxiety, but also affects the pedestrians decision-making process, thereby inducing the abnormal crowd behavior. Prompted by the epidemiological SIR model, an extended floor field cellular automaton model was proposed to investigate the pedestrian dynamics under the threat of hazard resulting from the panic contagion. In the model, the conception of panic transmission status (PTS) was put forward to describe pedestrians' behavior who could transmit panic emotions to others. The model also indicated the pedestrian movement was governed by the static and hazard threat floor field. Then rules that panic could influence decision-making process were set up based on the floor field theory. The simulation results show that the stronger the pedestrian panic, the more sensitive pedestrians are to hazards, and the less able to rationally find safe exits. However, when the crowd density is high, the panic contagion has a less impact on the evacuation process of pedestrians. It is also found that when the hazard position is closer to the exit, the panic will propagate for a longer time and have a greater impact on the evacuation. The results also suggest that as the extent of pedestrian's familiarity with the environment increases, pedestrians spend less time to escape from the room and are less sensitive to the hazard. In addition, it is essential to point out that, compared with the impact of panic contagion, the pedestrian's familiarity with environment has a more significant influence on the evacuation.     

Pedestrian evacuation at the subway station under fire

With the development of urban rail transit, ensuring the safe evacuation of pedestrians at subway stations has become an important issue in the case of an emergency such as a fire. This paper chooses the platform of line 4 at the Beijing Xuanwumen subway station to study the emergency evacuation process under fire. Based on the established platform, effects of the fire dynamics, different initial pedestrian densities, and positions of fire on evacuation are investigated. According to simulation results, it is found that the fire increases the air temperature and the smoke density, and decreases pedestrians' visibility and walking velocity. Also, there is a critical initial density at the platform if achieving a safe evacuation within the required 6 minutes. Furthermore, different positions of fire set in this paper have little difference on crowd evacuation if the fire is not large enough. The suggestions provided in this paper are helpful for the subway operators to prevent major casualties.