Modeling walking behavior of pedestrian groups with floor field cellular automaton approach

Walking in groups is very common in a realistic walking environment. An extended floor field cellular automaton （CA） model is therefore proposed to describe the walking behavior of pedestrian groups, This model represents the motion of pedestrian groups in a realistic way. The simulation results reveal that the walking behavior of groups has an important but negative influence on pedestrian flow dynamics, especially when the density is at a high level. The presence of pedestrian groups retards the emergence of lane formation and increases the instability of operation of pedestrian flow. Moreover, the average velocity and volume of pedestrian flow are significantly reduced due to the group motion. Meanwhile, the parameter-sensitive analysis suggests that pedestrian groups should make a compromise between efficient movement and staying coherent with a certain spatial structure when walking in a dense crowd.

An extended cellular automata model with modified floor field for evacuation

The floor field model has been widely used in evacuation simulation research based on cellular automata model. However, conventional methods of setting floor field will lead to highly insufficient utilization of the exit area when people gather on one side of the exit. In this study, an extended cellular automata model with modified floor field is proposed to solve this problem. Additionally, a congestion judgment mechanism is integrated in our model, whereby people can synthetically judge the degree of congestion and distance in front of them to determine whether they need to change another exit to evacuate or not. We contrasted the simulation results of the conventional floor field model, the extended model proposed in this paper, and Pathfinder software in a same scenario. It is demonstrated that this extended model can ameliorate the problem of insufficient utilization of the exit area and the trajectory of pedestrian movement and the crowd shape of pedestrians in front of exit in this new model are more realistic than those of the other two models. The findings have implications for modeling pedestrian evacuation.

Efficient Dynamic Floor Field Methods for Microscopic Pedestrian Crowd Simulations

Floor field methods are one of the most popular medium-scale navigation concepts in microscopic pedestrian simulators.Recently introduced dynamic floor field methods have significantly increased the realism of such simulations,i.e.agreement of spatio-temporal patterns of pedestrian densities in simulations with real world observations.These methods update floor fields continuously taking other pedestrians into account.This implies that computational times are mainly determined by the calculation of floor fields.In this work,we propose a new computational approach for the construction of dynamic floor fields.The approach is based on the one hand on adaptive grid concepts and on the other hand on a directed calculation of floor fields,i.e.the calculation is restricted to the domain of interest.Combining both techniques the computational complexity can be reduced by a factor of 10 as demonstrated by several realistic scenarios.Thus on-line simulations,a requirement of many applications,are possible for moderate realistic scenarios.

Comparative Analysis of the Distribution Characteristics of Floor Stress Field between Gob-Side Entry Retaining with Roof Cutting and Conventional Mining

All coal fields in North China are affected by floor confined water to varying degrees, floor failure and water inrush risk have always been a major problem to baffle coal mining activities. Roof cutting and pressure relief and the lack of protective coal pillar can cause the change of floor stress field, leading to the change of the floor failure depth, stress field of floor is the key to determine the depth of floor failure. In order to deeply study the distribution characteristics of floor stress field in gob-side entry retaining mining with roof cutting, taking the 50107 and 50109 working faces of Dongdong Coal Mine in Chenghe as the research objects, the numerical simulation software is used to simulate the floor stress field distribution of gob-side entry retaining mining with roof cutting and conventional mining. The distribution characteristics of the floor stress field of the working face are compared and analyzed under the three modes of conventional mining of reserved coal pillar, the first mining face of gob-side entry retaining with roof cutting and gob-side entry retaining with roof cutting. The results show that the peak stress concentration in front of the working face all occurs at 10 m under the three mining modes. The stress concentration area in front of conventional working face of reserved coal pillar is mainly in the middle of the working face. The stress concentration area in front of the first working face of gob-side entry retaining with roof cutting (50107) is located in the middle of the working face and the side of the working face of the retaining roadway. The stress concentration area of the working face (50109) is mainly in the middle and the two ends of the working face. The order of the peak value of the maximum concentrated stress in front of the working face is conventional working face of reserved coal pillar > the first working face of gob-side entry retaining with roof cutting (50107) > working face of gob-side entry retaining with roof cutting (50109). There is a stress reduction zone behind the working face, but there is a stress concentration phenomenon extending to the outside of the roadway, and the stress distribution is obviously different. Conventional working face of reserved coal pillar and the first working face of gob-side retaining with roof cutting (50107) show a double peak form of stress concentration on the outside of the two ends of the roadway, and the peak value of the concentrated stress at the rear of the working face is in the following order: On the side close to the transportation roadway, conventional working face of reserved coal pillar = the first working face of gob-side entry retaining with roof cutting (50107) > working face of gob-side entry retaining with roof cutting (50109);on the side close to the return airway, conventional working face of reserved coal pillar > the first working face of gob-side entry retaining with roof cutting (50107) > working face of gob-side entry retaining with roof cutting (50109).

考虑恐慌情绪和信息传递的行人疏散模拟

为分析应急疏散过程中恐慌情绪和信息传递对行人疏散效率的影响,提出基于热传递原理的情绪感染模型和元胞自动机场域模型相结合的疏散模拟方法。该方法通过量化的恐慌值影响行人决策偏好,并引入信息扩散模型,修正成功接收到出口信息的人群的疏散路径,模拟研究恐慌情绪作用下行人受到信息引导后疏散行为的变化。研究结果表明:恐慌情绪感染主要出现在人群聚集时期,伴随恐慌的蔓延,整体疏散效率降低,且对小规模行人疏散影响效果更显著;随着危险源向出口靠近,恐慌情绪使行人做出非理性决策的可能性更大,导致出口处人群出现分散再聚集现象;有效的信息传递可以降低恐慌情绪影响、提高疏散出口利用率,且信息传递影响效果随疏散人数的减少和危险源向出口的靠近而有所增强。研究结果可为提升应急疏散效率提供理论支持。

考虑折返行为的元胞自动机人员疏散模型

为研究行人折返行为对疏散的影响,考虑多出口对行人的吸引力、人员相互作用力、火源蔓延威胁以及折返场吸引力的共同影响,在元胞自动机模型的基础上提出基于静态场、动态场、火源场以及折返场共同作用的行人疏散场域模型,研究不同折返比例、折返区域、人员密度、出口数量和位置情况下折返行为对疏散进程的影响。研究结果表明:少量折返行为对总疏散时间影响较小,而群体性折返行为的存在会增加总体疏散时间,随着折返比例的增加,疏散时间随之增加。折返区域离出口越近,对总体疏散效率的影响越小。折返行为对疏散进程的影响效果,随着人员密度的增加不断增强。在双出口条件下,对侧设置出口位置能有效减少折返行为对疏散进程的负面影响。研究结果可为提高紧急情况下的疏散效率提供参考。

考虑换乘通道利用的地铁换乘站行人疏散引导策略研究

换乘地铁站的安全管理因其结构更为复杂、客流交织更为严重而备受关注。以某T形换乘地铁站为例,基于元胞自动机场域模型构建了考虑换乘通道利用程度的行人紧急疏散模型,并分别设计了面向站台层和站厅层的行人引导策略,对比分析了不同疏散策略组合对换乘地铁站行人疏散的影响。结果表明:T形换乘地铁站中等规模(约3000人)疏散场景下,与无引导策略相比,同时考虑站台引导和站厅引导的疏散用时更短,且疏散人员分布更均衡;针对换乘通道利用程度调配的疏散分区设计,存在最优分隔间距,总疏散人数的变化对最优分隔间距没有影响,但疏散人员在各个站台的分布比例对最优分隔间距有一定的影响。研究有助于T形换乘地铁站内的密集人群安全管理。

浅海孤立子内波作用下的三维声场空间特性

针对浅海环境下孤立子内波对声场空间特性的影响,以三维抛物方程理论及高精度根式算子近似方法为基础,建立了适应孤立子内波环境的三维声场计算方法。充分考虑孤立子内波传播特点与浅海中点源柱扩散形式的声场结构特征,形成以直角坐标系−柱坐标系的联合环境处理的声场计算形式,通过改变环境参数输入形式,提升了计算效率,并研究了孤立子内波影响下的三维声场分布特性。结果表明,平坦海底情况下,内波影响下的三维声场垂直和水平分布结构均发生变化,且随频率增加而增大,尤其是声源深度在跃层附近时变化更为明显;非平坦海底环境下,三维声场受到非水平海底和内波的双重调制作用,导致孤立子内波影响下的声场水平分布变化进一步加剧,从而在一定程度上反映出海底地形这一大尺度非均匀性对声场产生的水平折射效应以及对声传播特性的影响。

Numerical analysis of the destruction of water-resisting strata in a coal seam floor in mining above aquifers

With the increase in mining depth many mining areas in China have entered a period necessitating mining above aquifers. Production safety in coal mines in northern China is under serious threat from Ordovician karst water on coal seam floors, in order to analyze the destruction of water-resisting strata in floors of coal seams being mined and to achieve safe mining above deep aquifers, we established a numerical model of water-resisting strata, considering the structural characteristics and mechanical properties of a floor layered with hard and soft rock. We simulated the distribution characteristics of deformation, failure and seepage using the analytical module of fluid-structure interaction of FLAt：. We also obtained the corresponding stress distribution, deformation and flow vectors. Our results indi- cate that： （1） the advance of the working face causes water-resisting strata in goaf floors to form a deep double-clamped beam, subject to homogeneous loading at the bottom; （2） the two sides of the rock beam are subject 1~0 shear failure; （3） both sides of the rock seam at the bottom of the water-resisting strata are subject to tension and the greater the working face advance, the more serious the failure; C4） the original balance of the stress and seepage fields are broken and redistributed due to mining activities, especially the interaction of the abutment pressure in both sides of the goal; the lateral pressure on the goal floor and the water pressure on the floor of the aquifer promote floor heave and shear failure on both sides of the floor, forming a water-inrush passage. Our study results can provide references for the mechanism of water-inrush on mine floors.

远场应力作用下底抽巷对底板隔水性能影响及加固技术优化

大水矿区底抽巷施工影响底板岩层隔水性能,增加煤炭开采的危险性并给底板注浆加固技术带来挑战。为此开展了远场应力作用下采动条件下底抽巷对关键岩层隔水性能影响及加固技术优化研究。根据底抽巷的轴向和断面特征,建立远场主地应力作用下底板关键岩层力学作用模型,求解有底抽巷和无底抽巷时底板破坏区下方粉砂岩的变形和弯矩理论解,进而研究底抽巷道条件下浆液充填套管在注浆加固岩层的应用效果,并进行数值验证。首先,根据研究区主要远场地主应力赋存特征得到局部坐标系中粉砂岩Ⅱ承受的应力分量σ′;然后根据弹性矩形薄板单三角级数的Levy解,运用广义简支边和叠加法,得到两邻边自由条件下工作面推采距离与工作面长度比分别为0.50、0.75、1.00、1.50和2.00时底板破坏区下方粉砂岩Ⅱ的变形和弯矩值。结果表明近似弹性条件下粉砂岩Ⅱ在底抽巷交叉点处的位移最大,且大于四边固支条件下同尺寸岩层最大位移;底抽巷影响下粉砂岩Ⅱ固定边承受的最大弯矩值比固支边时高一个数量级,同等条件下底抽巷使得粉砂岩Ⅱ更易发生变形,降低了粉砂岩Ⅱ抵抗变形性能和抗弯刚度。据此提出底板注浆加固工程优化方法,将浆液充填套管进入粉砂岩Ⅲ垂直深度2 m,给粉砂岩Ⅱ自由边增加约束,底板注浆加固工程中浆液充填长套管利用抗弯性能改善粉砂岩Ⅱ边界条件增加其抵抗强度,数值计算结果验证了底板注浆加固工程中浆液充填套管实际作用效果。

基于势能场元胞自动机的不同个性人群疏散仿真

为了综合考虑人群个性和室内环境对疏散的综合影响,采用势能场元胞自动机(FFCA)模型模拟混合有不同性格行人的疏散.该模型构建了人群疏散环境的时空网络图,并通过计算最小运动消耗(LTC)路径建立静态势能场.疏散人群根据性格特征被分为3类,每类人群都可能使用不同的策略来平衡疏散中的运动和时间消耗.在每个时间步,每位行人都能根据随时变化的FFAC模型选择下一个移动目标.行人会根据自己的决策机制不断规划新路线或选择等待,直到到达出口.疏散模拟选择在不同的复杂疏散场景中进行,如多出口房间、教室和地铁,且疏散人群由不同性格的稠密人群混合而成.该研究为揭示行人心理、逃生环境与疏散行为之间的内在联系提供了一种新的方法.

深井巷道滑移底鼓机理与钢管混凝土桩治理底鼓技术研究

深井巷道底鼓现象十分普遍,其中滑移型底鼓治理难度大。以羊东矿-850水平北翼轨道大巷为背景,研究了轨道大巷强烈大变形规律,分析了巷道底板滑移破坏机理,提出巷道底板钢管混凝土桩抗滑抑制底鼓技术,并利用数值模拟方法分析了不同支护密度下抗滑桩控制底鼓效果。结果表明:高应力场环境、岩石黏土矿物含量高、裂隙水与工程积水,是导致岩石崩解破坏、巷道围岩大变形及强烈底鼓的主要因素;控制底板岩层滑移面形成及增加滑移面抗剪切强度是抑制滑移型底鼓的关键;钢管混凝土桩兼具抑制滑移面形成和提高滑移面部位强度的作用;随着抗滑桩布置密度的增加,巷道底鼓量与巷道底板破坏深度随之减小,在一定支护密度下巷道底板破坏深度趋于稳定;抗滑桩由外至里受力呈拱形分布,桩支护密度大时桩受力小,巷道底板中部或里侧桩受力大于两侧桩。现场试验表明:巷道底鼓得到了有效控制,能够满足生产运输的正常使用。

不同材质抗浮锚杆与基础底板的黏结强度试验研究

玻璃纤维增强聚合物(Glass fiber reinforced polymer,GFRP)锚杆因具有耐腐蚀性能强、抗拉强度高、导电性差、造价相对低等诸多优势成为钢筋锚杆的潜在替代品应用于地下结构抗浮工程中。采用倒置基础底板对GFRP筋和钢筋两种材质的抗浮锚杆开展现场极限抗拔试验,明确GFRP抗浮锚杆与地基底板之间的黏结锚固特性,揭示锚筋材质、竖向锚固长度、弯曲半径、弯折锚固长度及黏结长度等因素对抗浮锚杆与基础底板黏结强度的影响机制。结果表明:(1)GFRP抗浮锚杆及直锚的钢筋抗浮锚杆易发生剪切滑移破坏,弯锚的钢筋锚杆发生锚筋断裂破坏;(2)本试验条件下,直径28 mm的抗浮锚杆与基础底板的黏结强度介于1.23~7.79 MPa;(3)弯折锚固长度是影响抗浮锚杆与基础底板黏结强度的主要因素,且对GFRP抗浮锚杆的影响最显著,GFRP锚筋不宜在基础底板内进行弯折;(4)对这两种材质抗浮锚杆的黏结-滑移曲线进行对比,直锚钢筋锚杆的黏结-滑移曲线存在明显拐点,而直锚GFRP锚杆则几乎为线性上升状态。

盆底磁刺激联合中医理疗对压力性尿失禁患者漏尿量及盆底肌张力的影响

[目的]探讨盆底磁刺激联合中医理疗对压力性尿失禁(Stress Urinary Incontinence,SUI)患者漏尿量及盆底肌张力的影响.[方法]选取延安市人民医院收治的86例SUI患者,按照随机数字表法分为观察组和对照组,每组43例.对照组采用盆底肌磁刺激治疗,观察组在对照组的基础上加用中医温针灸理疗.比较两组患者临床疗效、漏尿情况(1h尿垫试验漏尿量、3d漏尿次数)、复发情况及治疗前后盆底肌力、生活质量评分、尿动力参数(最大漏尿点压力、初始排尿欲膀胱容量).[结果]治疗后,观察组总有效率为88.37%,显著高于对照组的69.77%,差异有统计学意义(P<0.05);观察组手测盆底肌力、盆底Ⅰ类肌纤维肌电压、盆底Ⅱ类肌纤维肌电压、QOL评分均显著高于对照组(P<0.05);盆底Ⅰ类肌纤维的疲劳度、盆底Ⅱ类肌纤维的疲劳度、1h尿垫试验漏尿量、3d漏尿次数、最大漏尿点压力、初始排尿欲膀胱容量等尿动力参数显著低于对照组(P<0.05);与对照组相比,观察组第3个月、第6个月复发率均明显降低(P<0.05).[结论]盆底磁刺激联合中医温针灸治疗SUI疗效显著,可明显增强患者盆底肌力,提高尿动力参数,改善漏尿情况和生活质量,降低复发率.

中国澳门大学珠海校区礼堂结构设计与分析

中国澳门大学珠海校区礼堂结构设计需同时满足国家和地方的相关规范。礼堂内部空旷,楼层错落不齐,设置剪力墙可以让各部分有相对独立的较强的抗侧力体系,也可以为楼座大悬挑梁提供稳固的支撑。计算结果表明,框架-剪力墙结构的礼堂考虑观众席斜楼盖的影响后,抗侧刚度有一些增加,斜楼盖下端的构件及与其相连的柱内力增大。还介绍了屋盖预应力梁、楼座大悬挑梁等的设计,对于大小跨梁引起的内柱弯矩过大的问题,通过合理选择梁中预应力筋线型,在内柱产生与外荷载效应相反的弯矩有效地予以解决。

基于自适应共生生物搜索的人群疏散方法

为了解决传统场域模型在刻画人群疏散过程中的不足,基于自适应共生生物搜索方法来改进场域模型,构建了一种新的室内空间人群疏散优化模型。首先,该模型将路径拥挤度和局部方向拥堵度2个因素融入场域模型,以此构建最小疏散时间的目标优化函数。其次,通过调整动态自适应因子对共生生物搜索的共栖阶段进行扰动,解决优化方法的局部最优问题。最后,根据搭建的真实疏散环境与仿真试验平台,对比分析了改进模型与传统场域模型之间的性能状况。结果表明:传统场域模型在出口处容易造成大量拥挤,而优化模型能够有效实现躲避拥堵;同时优化模型可以根据不同时间段动态调整疏散策略,提高疏散效率。

倾斜不稳定煤层采动工作面底板破坏深度研究

为探究丰阳煤矿11采区11104工作面倾斜不稳定煤层采动底边变形破坏特征,通过现场实测与数值模拟,获得了该工作面底板变形破坏深度及采动矿压对底板的作用特征。研究结果表明,11104工作面采动底板变形具有分带性,可划分为“两带”,其中采动破坏带(Ⅰ)不超过20.0 m,扰动塑性损伤带(Ⅱ)不超过21.2 m;采后底板应变感应的数据变化反映出11104工作面底板矿压剧烈延续影响范围较大,采后卸压对底板产生了较强的扰动效应;获得该工作面采动煤层底板破坏深度不超过20.0 m。

大面积仓储厂房地坪平整度控制

随着国家物流产业的快速发展,仓储物流厂房建设工程的需求也日益增加。由于仓储货架及机器人等设备运行对地面平整度要求较高,地坪平整度的控制是厂房建设过程中的重点。以实施项目为例介绍地坪控制的要点,为类似项目施工提供技术参考。

汽车后地板拉延件成形裕度提升及参数优化研究

目的提升拉延工艺处理后汽车后地板零件的成形裕度,优化成形参数。方法首先,设置初始拉延工艺参数:压边力为807kN、摩擦因数为0.135、压边圈行程为205mm、成形力为3572kN,基于Autoform软件对后地板的拉延工艺进行数值模拟。其次,利用全场网格应变测量技术对试冲件进行全场测量,获得全场成形裕度云图、成形极限图、减薄云图。最后,调节压边力与拉延筋深度及圆角半径,优化拉延工艺的成形参数。结果通过模拟获得了零件的潜在风险区域位置,零件的最大减薄率为24.10%、全场成形裕度均小于10%;测量结果表明,最大成形裕度为-9.29%。对风险区域进行模具圆角抛光后,最大成形裕度达到-10.65%。通过综合分析测量结果与模拟结果可知,采用压边力为782kN、B处拉延筋圆角半径为4.5mm、拉延筋深度为4.5 mm等成形参数,试冲得到的零件无开裂和起皱缺陷,成形裕度最大值为-14.33%,满足大规模生产需要。结论利用数值模拟结合全场网格应变测量技术指导修模作业并优化工艺参数,可以有效提升模具的调试效率。

谦比希铜矿下向孔爆破底板控制技术研究

谦比希铜矿东南矿体主要采用预切顶下向平行中深孔采矿法进行开采,然而在爆破回采作业过程中,炮孔底部严重根底问题频繁发生,进而造成后续崩矿高度降低、铲运机出矿作业效率低下等问题。为解决以上问题,研究以谦比希铜矿下向孔爆破为工程背景,采用LS-DYNA建立了不同炮孔超深下的底板控制爆破模型,通过对比分析不同模型的爆破损伤范围,得出最优炮孔超深,进一步地开展现场验证试验并提出了相应的底板控制施工建议措施。