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机动车数量的急剧增长,使城市道路交通产生较大压力,易造成城市交通的拥堵.而城市道路受到土地资源等条件的限制无法扩建,因此需要通过远引调头等管制措施来缓解交通拥堵.通过VISSIM仿真系统分别建立车辆直接左转模型与车辆远引调头模型,对比分析车辆直接左转与远引调头的运行效果.通过对比两种交通组织方式的行程时间及延误时间,分... 相似文献
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针对车道被占用对城市道路通行能力的影响,根据所给条件,运用数据统计、车流波动理论等方法,分别建立了道路实际通行能力模型和速度—密度模型,使用了Excel进行求解、作图,进而给出了不同车道被占用时道路横断面实际通行能力的变化过程和差异,以及给定条件下车辆排队长度与事故横断面道路的实际通行能力、事故持续时间和路段上游车流量之间的关系式。 相似文献
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《东南大学学报》2021,(3)
为了提高城市隧道的安全性能,研究了不同驾驶经验的城市隧道驾驶员的固定传递特性.首先,在某城市隧道进行了实车试验,并利用Dikablis跟踪系统采集了10名不同驾驶经验驾驶员的眼动数据.其次,采用K均值聚类方法将驾驶员固定范围划分为8个视觉兴趣区域,并对隧道不同断面的固定效果进行了比较分析.最后,基于视觉兴趣划分、固定传递规律和不同驾驶经验的驾驶员在隧道不同路段上的平稳分布特征,运用马尔可夫理论进行了讨论.结果表明:隧道内段驾驶员重复固定的概率较大,视觉搜索效率较低;驾驶员主要从直上前方和直下前方区域获取信息,在这2个区域,在门槛和出口段固定点的概率明显高于其他路段;与经验丰富的驾驶员相比,新手驾驶员对直上前区和后视镜的关注度较低,这意味着他们对前方的注视力较弱,在获取后接近车辆信息和控制速度方面缺乏经验. 相似文献
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针对车道被占用对城市道路通行能力的影响及车辆排队。根据交通波、排队论等理论,构建了道路通行能力评价和交通波滞动等模型,综合运用MATLAB软件和Excel软件进行分析及求解,总结出事故对实际通行能力影响的变化过程,不同车道对实际通行能力影响的差异,得到车辆排队长度与事故横断面实际通行能力、事故持续时间、路段上游车流量间的关系,计算出车辆排队长度到达上游路口的时间。 相似文献
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本文通过某路段交通事故发生后的情况,研究不同车道被占后道路横断面实际通行能力的变化,得出路段不同情况下排队长度达到上游路口所需时间,同时估算车道被占用对城市道路通行能力的影响程度,为交通管理部门正确引导车辆行驶、审批占道施工、设计道路渠化方案、设置路边停车位等提供理论依据. 相似文献
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为提高车辆半主动空气悬架在不同路面下的平顺性和控制性能,以驾驶员座椅和车辆俯仰角的加权加速度均方根值为控制目标,提出了一种基于模糊最优控制和车辆实际模型的机器学习方法.研究结果表明：车辆在72 km/h以上高速行驶时,软路面对车辆的平顺性有明显影响.基于机器学习,软路面工况下采用模糊控制的座椅和车辆俯仰角的加权加速度均方根值分别降低了30.20%和19.95%,而硬路面工况下无控制策略的座椅加速度和俯仰角加速度的加权加速度均方根值分别降低了34.36%和21.66%.这说明不同仿真条件下,该方法均能提高车辆的行驶平顺性.此外,为提高机器学习的效率,需要对其学习数据进行不断更新,以适应车辆的各种运行工况. 相似文献
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王帅 《洛阳师范学院学报》2014,(8):11-13,16
本文以交通事故这种异常事件为例,分别对公路基本路段内交通事故影响时间、车辆排队长度、事故影响下不同时间段内不同路段断面流量变化和不同路段发生事故的车流变化进行了分析.采用交通波理论给出了该事故路段内不同阻塞行车道宽度的车辆排队长度. 相似文献
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YOUSEFI Saleh FATHY Mahmood BENSLIMANE Abderrahim 《浙江大学学报(A卷英文版)》2007,8(12):1990-2004
Currently, there is a growing belief that putting an IEEE 802.11-like radio into road vehicles can help the drivers to travel more safely. Message dissemination protocols are primordial for safety vehicular applications. There are two types of safety messages which may be exchanged between vehicles: alarm and beacon. In this paper we investigate the feasibility of deploying safety applications based on beacon message dissemination through extensive simulation study and pay special attention to the safety requirements. Vehicles are supposed to issue these messages periodically to announce to other vehicles their current situation and use received messages for preventing possible unsafe situations. We evaluate the performance of a single-hop dissemination protocol while taking into account the quality of service (QoS) metrics like delivery rate and delay. We realize that reliability is the main concern in beacon message dissemination. Thus, a new metric named effective range is defined which gives us more accurate facility for evaluating QoS in safety applications specifically. Then, in order to improve the performance, the effects of three parameters including vehicle's transmission range, message transmission's interval time and message payload size are studied. Due to special characteristics of the safety applications, we model the relationship between communication-level QoS and application-level QoS and evaluate them for different classes of safety applications. As a conclusion, the current technology of IEEE 802.11 MAC layer has still some challenges for automatic safety applications but it can provide acceptable QoS to driver assistance safety applications. 相似文献
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The present study examined developmental differences in the effect of route extensity on the memory for the locations of objects in a spatial array. Kindergarten and adult subjects were trained to remember the locations of 4 objects. During this training, objects were either connected by a combination of indirect, looped train tracks and direct train tracks (experimental subjects) or connected by entirely direct train-track routes (control subjects). Analyses of actual interobject distances, from subjects' reproductions of object locations on a response board (without train tracks), revealed that children, but not adults, distort distance in terms of the nature of travel observed between objects. Further testing revealed that differences in the amount of time taken for travel could not account for the results obtained with children. 相似文献
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高速铁道车辆风致安全性研究 总被引：1，自引：0，他引：1
Xin-biao XIAO Liang LING Jia-yang XIONG Li ZHOU Xue-song JIN 《浙江大学学报(A卷英文版)》2014,15(9):694-710
研究目的：随着世界高速铁路网的不断扩张,高速列车的风致安全性成为高速铁路系统中的关键科学问题之一。本文利用车辆-轨道耦合动力学理论分析方法,确定强横风作用下高速铁道车辆的安全运行区域,为强风地带高速列车的安全控制提供依据。创新要点：首次提出了考虑多种影响因素和脱轨评价指标的高速列车脱轨安全域分析方法,并运用到了高速铁道车辆风致安全性研究中。研究方法：基于车辆-轨道耦合动态响应及多种安全性评价指标得到横风作用下高速铁道车辆的安全运行区域和脱轨区域。重要结论：铁道车辆安全性评价指标中,轮重减载率对横风激励最为敏感,其确定了强风作用下高速车辆安全运行区域的边界。 相似文献
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The conventional car-following theory is based on the assumption that vehicles will travel along the center line of lanes.
However, according to the field survey data, in complex traffic conditions, a lateral separation between the leader and the
follower frequently occurs. Accordingly, by taking lateral separation into account, we redefined the equation of time-to-collision
(TTC) using visual angle information. Based on the stimulus-response framework, TTC was introduced into the basic General
Motors (GM) model as a stimulus, and a non-lane-based car-following model of steady-state traffic flow was developed. The
property of flow-density relationship was further investigated after integrating the proposed car-following model with different
parameters. The results imply that the property of steady-state traffic flow and the capacity of each lane are highly relevant
to the microscopic staggered car-following behavior, and the proposed model significantly enhances the practicality of the
human driving behavior model. 相似文献
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毕雁冰 《深圳信息职业技术学院学报》2007,5(1):5-8
针对车道偏离预警系统LDWS(Lane Departure warning Systems)的车道偏离评价方法,目前通用的评价算法由于计算过程中使用了横向速度恒定和转向半径一定的假设,与车辆实际的速度和方向控制特性有较大的差别,因此评价结果误差也较大。本文基于稳态预瞄基本原理,通过改进隶属函数的方法,提出一种基于多边检测的驾驶安全性评价指标车道偏离评价方法。根据车辆的当前稳态特性预测车辆未来时刻到达的位置,对车辆的行驶轨迹进行稳态预瞄。并通过车辆预期轨迹点与车道的横纵向距离对车道偏离进行评价,大幅度提高了车辆预警精度,减少空预警的发生。 相似文献
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赵志忠 《廊坊师范学院学报(自然科学版)》2013,(6):76-78
结合工程实例,采用消防安全评估的方法,从人员安全疏散性能化设计的应用研究的角度进行探讨,重点对疏散通道及安全出口设计、可用疏散时间TASET、必需疏散时间TRSET进行了分析。根据上述标准,认为乌兰察布市机场航站楼消防安全设计方案可行。 相似文献
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郑红 《辽宁科技学院学报》2001,3(3):17-19,23
混凝土泵车的稳定性是安全性指标，它是整体结构布置与设计中优先考虑的一个问题，通过对混凝土泵车在行驶及工作中稳定性的分析，指出影响稳定性的因素，为混凝土泵车的优化设计提出稳定性的设计方法。 相似文献
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In this paper, a prediction model is developed that combines a Gaussian mixture model (GMM) and a Kalman filter for online forecasting of traffic safety on expressways. Raw time-to-collision (TTC) samples are divided into two categories: those representing vehicles in risky situations and those in safe situations. Then, the GMM is used to model the bimodal distribution of the TTC samples, and the maximum likelihood (ML) estimation parameters of the TTC distribution are obtained using the expectation-maximization (EM) algorithm. We propose a new traffic safety indicator, named the proportion of exposure to traffic conflicts (PETTC), for assessing the risk and predicting the safety of expressway traffic. A Kalman filter is applied to forecast the short-term safety indicator, PETTC, and solves the online safety prediction problem. A dataset collected from four different expressway locations is used for performance estimation. The test results demonstrate the precision and robustness of the prediction model under different traffic conditions and using different datasets. These results could help decision-makers to improve their online traffic safety forecasting and enable the optimal operation of expressway traffic management systems. 相似文献