货车-两轮车前碰撞事故中骑行者运动学响应及损伤分析

为探究货车-两轮车前部碰撞事故中参与双方速度对骑行者运动学响应与损伤的影响,基于MADYMO软件开展事故重建并进行了分析。建立了货车和两轮车的多体碰撞模型,对一起货车前部碰撞两轮车事故进行了事故重建;使用验证后的模型进行了25组不同速度下的全因子仿真试验;分析了不同碰撞速度和骑行速度对骑行者运动学响应和损伤的影响。研究结果表明,骑行者身体旋转幅度会随着两轮车及货车车速的升高而增加;当货车速度超过 20 km/h时,骑行者头部损伤指标 （Head Injury Criterion,HIC） 与胸部3 ms加速度将超过阈值;而当货车速度超过25 km/h时,骑行者下肢接触力也超过阈值;货车速度处于 30～40 km/h时,相同货车速度下,骑行者头部 HIC值出现随着两轮车速度的增加而升高的趋势,而胸部加速度出现相反的趋势。     

基于微震监测的深埋隧道岩爆预警研究

北武夷山高铁隧道是一座单洞双向隧道,隧道最大埋深达1 100 m,属于高地应力区。经岩爆倾向性研究,可能出现弱岩爆。为了预防岩爆造成人员伤亡和设备损坏,研究人员采用微震监测技术,在开挖同时配合微震监测,根据监测到的事件数和能量变化情况,对岩爆和片帮发生进行预警。当微震系统监测到的事件率和和能量率同时急剧增加时,说明岩体内部变化剧烈,发生岩爆等地质灾害的可能性大大增加。根据这一准则,研究人员成功预测了隧道开挖过程中的一次小型岩爆。研究成果如下： 1）总结了隧道施工中常见微震波形的特征; 2）佐证了事件率和相对能量释放率可以客观反映岩体内部剧烈变化的事实,对今后隧道等地下工程利用微震监测方法防治岩爆灾害具有重要意义。     

基于柔性连接模型的自卸车举升机构受力分析

利用ADAMS软件中参数化建模与分析功能,建立了自卸车举升机构的柔性连接模型,对各连接点处采用轴套连接,分析了货箱质心偏移和存在安装误差时油缸举升力以及三角臂所受拉力和扭矩,对举升机构的设计具有指导意义。     

基于交通事故深度调查数据的行人头部损伤特征研究

基于未来出行交通事故场景研究 （Future Mobile Traffic Accident Scenario Study,FASS） 数据库中135例人车碰 撞事故深度调查数据,对造成行人头部损伤的来源及车速对头部损伤来源的影响进行了统计分析。采用Spearman相关系 数检验法,建立了车辆速度区间与头部平均 MAIS 的回归模型。结果表明,行人头部致伤物主要来源于车辆,占比约 58%,其次为地面,占比约40%。行人事故中,碰撞车速对行人头部损伤来源的分布情况有一定的影响,当车速低于30 km/h时,行人头部损伤主要来源为地面,当车速为 ［30,50］ km/h时,车辆和地面对行人头部造成的损伤风险相近,当 车速高于 50 km/h时,行人头部损伤主要致伤物来源为车辆。因此,在进行交通损伤流行病学研究、交通损伤事故数据 库构建时,特别是在中低速碰撞中,应重视地面对头部造成损伤的风险。     

车辆移动监控系统并发调度机制的研究

在车辆移动监控系统运行过程中,监控中心将同时接收到从不同车载终端发送过来的大量信息,这些信息分别对应着不同的事件。监控中心如何针对这些事件,及时做出不同的响应和处理是极为重要的。在对监控中心并发处理的性能要求进行分析的基础上,提出了优先数事件队列算法来实现车辆监控中心的并发调度机制,并给出了算法实现。     

Mining of the association rules between driver electrodermal activity and speed variation in different road intersections

It is commonly acknowledged that the human factor and the interaction between the human factor and the road environment are among the most common causes of road accidents. Physiological signals can provide a real-time assessment of the driver's state because they can be collected continuously without interfering with the driver's task performance or the drivers' perception of the road. This study presents a method for measuring and quantifying drivers' physiological responses when approaching T-junctions and roundabouts using electrodermal activity and speed variations. Speed and electrodermal activity were collected continuously during a driving study which took place on a test environment based at Cranfield University and surrounding roads. Twenty participants were involved in the study. The analysis focused on four crossing manoeuvres on two T-junctions and a roundabout. The association Rule with the Apriori algorithm was used in order to evaluate associations between the variables related to electrodermal activity, i.e. the number and amplitude of the SCR peaks (assessed by the Electrodermal Impact Index in aggregate form), and the variables related to speed, i.e. the speed variation and its sign (positive or negative), for each type of intersection. The main results of this study can be summarized as follows: 1) the rules obtained for the manoeuvres on the T-Junctions show that the T-junctions induce low variations in the electrodermal activity and are often associated with a significant speed increase (between 20% and 30%); 2) the rules obtained for the manoeuvres on the roundabout highlights that the roundabout induces high variations in the electrodermal activity and is associated with a significant speed reduction (between 20% and 40%).     

Trip characteristics impact on the frequency of harsh events recorded via smartphone sensors

The Internet of Things (IoT) constantly offers new opportunities and features to monitor and analyze driver behavior through wide use of smartphones, effective data collection and Big Data analysis, resulting in assessment and improvement of driver behavior and safety. The objective of the present study is to investigate the impact of detailed trip characteristics on the frequency of harsh acceleration and harsh braking events through an innovative smartphone application developed within the framework of BeSmart project. A 200-driver naturalistic experiment spanning 12 months is carried out since July 2019. During the first two months, participants were asked to drive in the way they usually did, without receiving any feedback on their driving behavior from the application. Over the subsequent two months, participants were provided with personalized feedback, a trip list and a scorecard regarding their driving behavior, allowing them to identify their critical deficits or unsafe behaviors. Some of the most important risk factors, such as speed and driving above the speed limit, usage of mobile phone while driving and harsh events (acceleration and braking) are recorded through the application and subsequently analyzed. Generalized Linear Mixed-Effects Models were fitted to the trips of car drivers who made frequent trips for both experiment phases in order to model the frequencies of harsh events. Results indicate that maximum speed, the percentage of speeding duration and total trip duration are positively correlated with both harsh acceleration and harsh braking frequencies. On the other hand, the exposure metric of total trip distance was found to be negatively correlated with both harsh event types. A small positive correlation of the percentage of mobile use duration with harsh accelerations was also detected.     

离心试验砂雨法试样制备研究

全国岩土工程离心模拟平行试验之一,是砂土模型地层的制备.砂土试样制备主要通过相对密度进行控制,试验中采用福建标准砂,采用砂雨法制备砂土地层和网眼式与鸭嘴式出砂头,通过对试验结果分析得到落距-相对密度标定曲线,并设定土体目标密度(55 %和75 %),验证曲线的可靠性;同时,考察制备模型地基的相对密度在空间上的均质性.出砂头的孔径大小、出砂量、出砂头水平移动速度对相对密度的影响,还需进一步研究.     

Speed management strategies and drivers' attitudes in Thailand

In Thailand where speeding on highways and roads has been a key contributing factor in road traffic crashes, considerable efforts to control vehicle speeds have been made, mostly through speed limit enforcement. However, the fact that speed limits are very often violated on a large scale in Thailand suggests the need for implementing more effective speed management strategies such as automatic speed cameras, increasing speeding penalty, and smart vehicle design to control vehicle speeds. While the effectiveness of such measures depends mainly on how well they could lead drivers to change speeding behavior, public acceptability is also vital as a key to sustainability of most speed management programs. This paper attempts to identify public acceptability of speed management measures, both currently implemented and under consideration, in Thailand. In doing so, data from the questionnaire surveys based on a random sample of 2180 drivers in Thailand including a wide range of individual characteristics of respondents and their attitudes to select speed management schemes are analyzed using an econometric technique. In particular, we introduce a simplified methodological framework to develop a better understanding of factors that explain drivers' attitudes towards speeding behavior and alternative speed management strategies. Findings from this research provide several important implications that could improve the current practices of speed management in Thailand.     

Meeting the management challenges of the Decade of Action for Road Safety

In low- and middle-income countries, the high price paid for mobility in terms of human loss and suffering is forecast to rise to unprecedented levels. More than 50 million deaths and 500 million serious injuries on the world's roads can be projected with some certainty over the first 50 years of the 21st century, unless sustained new initiatives are taken. This paper addresses the emergence of road safety as a development priority over the last decade and the management challenges facing the planned global response aimed at bringing road safety outcomes in developing countries under control. It outlines the decade of advocacy that created the UN Decade of Action for Road Safety 2011–2020 and related Global Plan, and highlights the concern that over the coming decade low and middle income countries will face considerable management challenges in successfully implementing related measures and sustaining their delivery. The paper discusses new road safety management tools that have been developed by the World Bank and ISO to provide assistance to countries and organizations within an integrated framework that ensures that measures taken are properly sequenced and adjusted to their absorptive and learning capacities. It concludes that strengthened institutions and the accelerated knowledge creation and transfer central to this, plus scaled-up investment and increased international cooperation and development aid are critical to the successful achievement of the Global Plan's ambitious goal.     

基于电磁驱动配气机构的发动机燃油经济性研究

基于全柔性化的电磁驱动配气技术,针对发动机低转速小负荷工况工质运动强度不足的问题,提出了一种新的进气策略以有效改善发动机的经济性。其机理是调节气门开启规律使进气初期完成绝大部分充气量,抑制泵气损失的过度增加,进气后期采用较低的升程以保证缸内较高的工质运动强度。通过与其他策略的对比分析可知,新策略在泵气损失和工质运动强度的变化上达到一个良好的平衡,更有利于改善发动机中低转速中小负荷工况的燃油经济性。     

基于响应面模型的智能台架供风系统开发

为解决瞬态工况下,汽车主动进气格栅（AGS）开度及风扇转速实时调整,换热器进风量时刻改变,热管理测试台架风机无法实时为换热器提供精准瞬态供风这一问题,应用计算流体力学（CFD）仿真技术,分析了换热器进风量与车速、AGS开度及风扇转速之间的关系,并构建了数学模型,模型预测误差小于6.6%。将该模型置于CANOE设备中,与VN1640设备及风机系统连接,可实时采集车速、AGS开度及风扇转速CAN信号,计算换热器进风量,从而控制风机输出相应风量,实现了台架风机为换热器提供精准、实时供风这一目标。     

不同出行方式交通空间颗粒物浓度特征及人体摄入量估算方法研究

为了提高居民出行健康,建立了评估出行者采用不同出行方式时的PM人体摄入量估算方法体系.使用PM检测仪采集各出行方式(步行、自行车、公交、出租车、地铁)不同交通空间(包括车厢、站台、人行道等出行者在出行过程中身处的周围环境空间)的PM浓度,建立了基于多元线性回归的PM浓度与影响因素的关系模型,并考虑出行个体心率指标的变化...     

Design for Headrest Including Guides Slot to Reduce the Neck Force in Rear End Impact

Whiplash injuries are one of the most common injuries reported in automotive rear end collisions. Automobile seat back and head restraints play a role in reducing neck injuries during low speed rear end collisions. Currently, many studies are being conducted on ways to reduce neck injuries. These deal with the design parameters that cause neck injuries and do not address the design of the head restraint connection structure. In this paper, we analyze the various trajectories of the headrest and propose a new design for a connection structure that can move along the corresponding trajectory. We model the headrest connection mechanism as a virtual link using kinematic modeling and perform trajectory analysis. Using the trajectory of motion, we select an oblong shape for the guide slot by fitting it with the equation of an ellipse and propose a new headrest connection mechanism. To evaluate the design of the proposed mechanism, we model the shape of the mechanism and test it using dynamic simulation under collision conditions. In addition, we design a prototype for the proposed guide, conduct a sled test, and confirm that the neck force is reduced by the proposed connection structure. In the proposed structure, the values of maximum upper neck shear and tension decreased by more than 20 % compared to existing headrest.     

Stability measurement of high-speed vehicles

Vehicle rollover represents a significant percentage of single-vehicle accidents and accounts for over 9000 fatalities and over 200,000 non-fatal injuries each year. Previous research has yielded rollover stability control systems that are effective in on-road conditions. Accident statistics show, however, that over 90% of rollovers involve road departure, during which a vehicle may encounter sloped and rough terrain while travelling at high speed. A critical element of most rollover stability control systems is a metric that monitors a vehicle's nearness to rollover. Most metrics, however, are designed for use on flat, level surfaces characteristic of on-road terrain. In this paper, a new stability metric, termed the stability moment, is proposed that is accurate on terrain surfaces with arbitrary geometry, which allows it to be used in road departure scenarios. The metric is based on an estimate of the distribution of wheel–terrain contact forces. The metric can be calculated on line in real time, using only practical, low-cost sensors. The metric is compared in simulations and experimental studies to existing stability metrics and is shown to exhibit superior performance, particularly in off-road conditions.     

Development of a path planning system using mean shift algorithm for driver assistance

The longitudinal and lateral vehicle control techniques have been widely used in several active driver assistance systems. The adaptive cruise control, lane keeping assistant control, vehicle platooning and stop-and-go control are typical examples of the most important applications. In this study, a novel path planning method is proposed considering the driving environment such as road shape, ego vehicle and surrounding vehicles’ movement. The relative distance and velocity between the ego vehicle and surrounding vehicles are identified with respect to the predicted lane shape in front of the ego vehicle. Based on the identified information, the road shape and surrounding vehicles are mapped into the intensity image and the desired vector for the ego vehicle’s movement is determined by the maximum intensity density tracing method. The desired vehicle path is followed by the acceleration/deceleration control and the steering assist control, respectively. In order to evaluate the performance of the proposed system, simulations are conducted and compared with ACC systems.     

Drivers' perceptions regarding speeding and driving on urban residential streets with a 30 km/h speed limit

Previous studies have shown very little information regarding drivers' opinions, attitudes and behaviours with respect to speeding and driving on urban residential streets with a 30 km/h speed limit. The present research aims to address this issue by conducting a questionnaire study with a sample of 367 Japanese drivers. The results showed that drivers tended to have positive beliefs about complying with the 30 km/h speed limit and understand the negative consequences of speeding; however, a majority of the drivers considered breaking the speed limit as a way to reduce their travel time. While the extent of speeding was found to be very serious, a number of drivers still supported the use of a 30 km/h speed limit on residential streets and favoured protecting the right of vulnerable street users. The logistic regression models developed in this study identified that the drivers who did not support the 30 km/h speed limit were associated with those who had committed traffic-law violations, who had negative beliefs about complying with the speed limit, who did not consider residents' opinions, who believed it is acceptable for them to drive at a high speed, and who felt it difficult to refrain from speeding. With regard to anti-speeding countermeasures, under drivers' point of view, streets should be designed to make the 30 km/h speed limit more credible, although this study also showed evidence supporting the application of public awareness programmes and social campaigns as speeding interventions. In addition, this research investigated drivers' speed choices in various specific driving circumstances, and six underlying factors affecting drivers' speed choices were determined. On the basic of the findings, the implications and suggestions for speeding interventions were also discussed.     

Driving behavior in mixed traffic flow: A novel model for assessing bus movement considering the interaction with motorcyclists

Improving level of service (LOS) is an essential requirement for a sustainable public transport development of a city. A large number of previous studies have considered bus LOS on viewpoints of its users. It should, however, be noted that the viewpoint of non-bus travelers is also equally important because they are potential to be bus users. This paper suggests a novel model for transport planners to assess driving behavior of bus drivers through a consideration of bus movement in association with motorcyclists' interaction. Bus movement assessment is modelled based on GPS and traffic surveillance video data in correlation with the traffic density estimated under Kalman-filter algorithm. A case study in Hanoi, Vietnam showed an illustration to the model.     

基于乘员伤害分析的路侧行道树事故严重度评价

为了定量评估公路路侧行道树事故严重度,有针对性地提出安全改善措施,以减少车辆与路侧行道树碰撞的事故损失,分别引入加速度严重性指数(Acceleration Severity Index,ASI)、头部损伤判据(Head Injury Criteria,HIC)和胸部合成加速度(Chest Resultant Accel...     

Implementing a GPU-based numerical algorithm for modelling dynamics of a high-speed train

This paper discusses the initiative of implementing a GPU-based numerical algorithm for studying various phenomena associated with dynamics of a high-speed railway transport. The proposed numerical algorithm for calculating a critical speed of the bogie is based on the first Lyapunov number. Numerical algorithm is validated by analytical results, derived for a simple model. A dynamic model of a carriage connected to a new dual-wheelset flexible bogie is studied for linear and dry friction damping. Numerical results obtained by CPU, MPU and GPU approaches are compared and appropriateness of these methods is discussed.