智能交通系统的元胞自动机交通流模型

在Nagel-Schreckenberg(NS)模型的基础上，提出一种可应用智能交通系统（ITS）信息的新的交通流元胞自动机模型. 其中考虑了有效间距及刹车灯的作用，并引入了可变安全间距的新概念. 数值模拟表明：对于这种改进的ITS元胞自动机模型，道路交通量有了显著提高，体现了智能交通的优越性——有效地扩大交通流量，减少阻塞生成. 当考虑快车和慢车的混合交通流时，发现即使少量的慢车也会导致交通流量大幅度下降，说明了严格实施快慢道行驶的必要性. 关键词： 交通流 智能交通系统（ITS） 元胞自动机模型 刹车灯 可变安全间距     

利用智能决策的双通道交通流

考虑依据信息反馈进行智能决策的双通道交通流问题, 获得一定信息时，好的决策可以使效率提高.多个体资讯的分析及经验的反馈、判断、再适应是一个多个体复杂适应系统的本质性质，交通流也明显带有以上特性.研究表明，如果机械地利用不好的反馈信息，系统将会存在很大的振荡；智能地利用反馈信息，可以提高系统利用效率.因此，应在尽可能地提供好的反馈信息的同时合理地利用它们. 关键词： 元胞自动机 信息反馈 机械决策 智能决策     

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     

公交车站对交通流影响模拟分析

采用元胞自动机模型对城市道路中公交车站影响下的交通流特性进行模拟分析.研究了非港湾式车站和港湾式车站两种设置方式下交通流特性,对公交车比例和公交车站长度的影响进行了分析.模拟结果显示非港湾式车站对交通流的影响较大,通过增加车站长度并不能有效地提高系统流量;港湾式车站对交通流的影响较小,通过增加车站长度可以较大程度地增加系统流量. 关键词： 公交车站 混合交通流 元胞自动机     

基于元胞自动机和复杂网络理论的双向行人流建模

通过设计行人行走倾向性调查实验,分析了行人的行走倾向性特征. 引入前进系数、右倾系数、超越系数以及影响修正系数等对元胞自动机(CA) 基本模型中的转移概率进行修正,建立了考虑行人行走倾向性特征的CA行人仿真模型. 针对该模型中的行人群体,依据k-近邻作用原理,构建行人复杂网络. 通过计算机仿真,揭示了行人流密度、速度和流量的关系以及仿真过程中出现的自组织现象.进一步分析仿真输出的行人流基本参数和行人复杂网络主要特征参数,发现对同一行人流,其平均速度和网络平均路径长度均随着行人流状态的改变而变化.最后, 通过平均路径长度和平均速度的数据拟合,得出两者之间存在着线性负相关关系的结论, 即具有较小网络平均路径长度的行人流具有较高的平均速度.     

互联网络数据包传输的一种简单元胞自动机模型

提出了一种描述计算机互联网络数据包传输的简单元胞自动机模型,并研究了沿着网络固定路径中路由节点数据包队列长度和传输时间的统计特性.计算机仿真结果表明,根据数据包输入速率和路由节点平均最大传输速率的不同,系统存在自由流和拥塞两种相态.在自由流状态,路由节点数据包排队长度和传输时间都呈现幂律特性;在拥塞状态,路由节点数据包排队长度呈现白噪声特征,而传输时间在低频段为幂律、高频段为白噪声特征.仿真结果和已有文献和经验数据得到的结论一致. 关键词： 元胞自动机 1//f噪声 幂律 计算机网络     

考虑意外事件对交通流影响的元胞自动机交通流模型

在NaSh模型的基础上,考虑交通事故和养护路段等意外事件对高速公路交通流的影响,建立了有意外事件影响的在车道管制下的高速公路交通流元胞自动机模型,并进行数值模拟. 研究发现:意外事件对高速公路交通流有明显影响,并且意外事件对交通流的影响在某一密度值范围内尤其明显,且意外事件堵塞点在第一车道比在第二车道对交通流的影响小;同时,在该密度值范围内,意外事件堵塞时间和堵塞路段长度越长,对交通流的影响就越大. 关键词： 元胞自动机 交通流 意外事件     

固定闭塞系统下列车运行限速区段交通流特性分析

针对铁路交通中四显示固定自动闭塞系统下的限速区段，建立了元胞自动机模型，对限速区段的交通流进行了模拟，分析了限速区段长度、发车时间间隔和限速值对交通流的影响，模拟结果表明减少限速区段长度、适当增加发车时间间隔和提高限速区段限速值都可增加列车在绿灯下的运行时间. 关键词： 四显示固定自动闭塞 元胞自动机 交通流     

一种改进的多速双向行人流元胞自动机模型

考虑行人的位置交换、侧向前进和后退行为,建立了一种改进的元胞自动机模型,用于研究地下通道中具有多种运动速度的双向行人流.将改进的元胞自动机模型与Weng的模型进行了比较.计算机模拟表明,改进的模型具有提高系统中行人的平均速度并降低行人占据密度的倾向. 关键词： 双向行人流 元胞自动机 计算机模拟     

智能交通灯对交叉路口交通流的影响

以改进的NaSch模型为基础,采用开放边界条件,分别对普通交通灯和智能交通灯控制下的十字交叉路口交通流进行模拟.结果表明,主干道车辆较多时,智能交通灯控制下的主干道车辆平均速度和流量都比普通交通灯控制下高,并可减少车辆的无谓等待时间. 关键词： 元胞自动机 交叉路口 智能交通灯 NaSch模型     

Green-wave control of an unbalanced two-route traffic system with signals

We introduce the preference parameter into the two-route dynamic model proposed by Wahle et al. The parameter represents the driver’s preference for the route choice. When the driver prefers a route, the traffic flow on route A does not balance with that on route B. We study the signal control for the unbalanced two-route traffic flow at the tour-time feedback strategy where the vehicles move ahead through a series of signals. The traffic signals are controlled by both cycle time and phase shift (offset time). We find that the mean tour time can be balanced by selecting the offset time successfully. We derive the relationship between the mean tour time and offset time (phase shift). Also, the dependences of the mean density and mean current on the offset time are derived.     

Behaviours in a dynamical model of traffic assignment with elastic demand

This paper investigates the dynamical behaviour of network traffic flow. Assume that trip rates may be influenced by the level of service on the network and travellers are willing to take a faster route. A discrete dynamical model for the day-to-day adjustment process of route choice is presented. The model is then applied to a simple network for analysing the day-to-day behaviours of network flow. It finds that equilibrium is arrived if network flow consists of travellers not very sensitive to the differences of travel cost. Oscillations and chaos of network traffic flow are also found when travellers are sensitive to the travel cost and travel demand in a simple network.     

A weighted mean velocity feedback strategy in intelligent two-route traffic systems

Information feedback strategies can influence the traffic efficiency of intelligent traffic systems greatly.Based on the more practical symmetrical two-route scenario with one entrance and one exit,an improved weighted mean velocity feedback strategy(WMVFS) is proposed,which is not sensitive to the precision of global position system(GPS) devices.The applicability of WMVFS to different weight factors,aggressive probabilities,densities of dynamic vehicles,and different two-route scenarios(symmetrical scenario and asymmetrical scenario with a speed limit bottleneck) is analyzed.Results show that WMVFS achieves the best performance compared with three other information feedback strategies when considering the traffic flux and stability.     

Effects of prediction feedback in multi-route intelligent traffic systems

We first study the influence of an efficient feedback strategy named the prediction feedback strategy (PFS) based on a multi-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. In this scenario, our model incorporates the effects of adaptability into the cellular automaton models of traffic flow. Simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux. At the end of this paper, we also discuss in what situation PFS will become invalid in multi-route systems.     

一类基于随机行走机理的优化路由改进策略

在对随机行走过程的研究中发现:单个粒子通过某条特定路径的时间正比于该路径上所有节点度的连乘积.据此,文章提出基于随机行走机理的优化路由改进策略.该策略以节点度连乘积最小化为原则,通过调节可变参数,建立节点处理能力均匀分布的情况下最佳路由策略.通过分析比较不同路由策略条件下平均路由介数中心度,网络的临界负载量,平均路径长度以及平均搜索信息量等性能指标,研究结果表明,此改进路由策略在保证网络平均路径长度较少增加的前提下,使网络的传输能力获得最大幅度的提升. 关键词： 复杂网络 路由策略 负载传输     

基于道路限速策略的规划路网噪声控制*

为缓解交通噪声污染,研究限速方案对噪声的影响,考虑道路限速策略下的阻抗函数,建立基于道路限速的随机用户均衡模型并实现路网交通分配,对规划路网在不同限速策略下的噪声控制规律进行研究。案例结果表明：道路限速控制对象应选取噪声影响道路;道路限速策略控制噪声的主要因素在于降低影响道路上出行车辆的出行速度,控制区域噪声值与路网总出行时间呈线性关系,道路限速80%的情况下,控制区域噪声和路网总出行时间分别降低2.94dB和增加0.66%;路网总噪声排放存在两种不同变化趋势,且与道路等级,绕行系数相关。研究可为从道路规划角度实现交通噪声控制提供有效参考。     

New Feedback Control Model in the Lattice Hydrodynamic Model Considering the Historic Optimal Velocity Difference Effect

A feedback control model of lattice hydrodynamic model is proposed by taking the information of the historic optimal velocity into account for the traffic system. The modern control theory is applied for the linear stability condition with feedback control signal. The result shows that the stability of traffic flow is closely related to the information of the historic optimal velocity. Furthermore, numerical simulations conform that the new feedback control did increase the stability of traffic flow efficiently, which is in accord with theoretical analysis.     

Prediction feedback in intelligent traffic systems

The optimal information feedback has a significant effect on many socioeconomic systems like stock market and traffic systems aiming to make full use of resources. In this paper, we studied dynamics of traffic flow with real-time information provided and the influence of a feedback strategy named prediction feedback strategy is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Our model incorporates the effects of adaptability into the cellular automaton models of traffic flow and simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux.     

Corresponding Angle Feedback in an innovative weighted transportation system

The optimal information feedback has a significant effect on many socioeconomic systems like stock market and traffic systems aiming to make full use of resources. In this Letter, we study dynamics of traffic flow with real-time information. The influence of a feedback strategy named Corresponding Angle Feedback Strategy (CAFS) is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Our model incorporates the effects of adaptability into the cellular automaton models of traffic flow and simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux.     

The Stability of Multi-modal Traffic Network

There is an explicit and implicit assumption in multimodal traffic equilibrium models, that is, if the equilibrium exists, then it will also occur. The assumption is very idealized; in fact, it may be shown that the quite contrary could happen, because in multimodal traffic network, especially in mixed traffic conditions the interaction among traffic modes is asymmetric and the asymmetric interaction may result in the instability of traffic system. In this paper, to study the stability of multimodal traffic system, we respectively present the travel cost function in mixed traffic conditions and in traffic network with dedicated bus lanes. Based on a day-to-day dynamical model, we study the evolution of daily route choice of travelers in multimodal traffic network using 10000 random initial values for different cases. From the results of simulation, it can be concluded that the asymmetric interaction between the cars and buses in mixed traffic conditions can lead the traffic system to instability when traffic demand is larger. We also study the effect of travelers' perception error on the stability of multimodal traffic network. Although the larger perception error can alleviate the effect of interaction between cars and buses and improve the stability of traffic system in mixed traffic conditions, the traffic system also become instable when the traffic demand is larger than a number. For all cases simulated in this study, with the same parameters, traffic system with dedicated bus lane has better stability for traffic demand than that in mixed traffic conditions. We also find that the network with dedicated bus lane has higher portion of travelers by bus than it of mixed traffic network. So it can be concluded that building dedicated bus lane can improve the stability of traffic system and attract more travelers to choose bus reducing the traffic congestion.