Accidents involving pedestrians with their backs to traffic or facing traffic: an evaluation of crash characteristics and injuries

This paper examines pedestrian anatomical injuries and crash characteristics in back‐to‐traffic and facing‐traffic crashes. Pedestrian crashes involving pedestrians walking along streets (i.e. with their backs to traffic or facing traffic) have been overlooked in literature. Although this is not the most frequent type of crash, the crash consequence to pedestrians is a safety concern. Combining Taiwan A1A2 police‐reported accident data and data from the National Health Insurance Database from years 2003–2013, this paper examines anatomical injuries and crash characteristics in back‐to‐traffic and facing‐traffic crashes. There were a total of 830 and 2267 pedestrian casualties in back‐to‐traffic and facing‐traffic crashes respectively. The injuries sustained by pedestrians and crash characteristics of these two crash types were compared with those of other crossing types of crashes (nearside crash, nearside dart‐out crash, offside crash, and offside dart‐out crash). Odds of various injuries to body regions were estimated using logistic regressions. Key findings include that the percentage of fatalities in back‐to‐traffic crashes is the highest; logistic models reveal that pedestrians in back‐to‐traffic crashes sustained more head, neck, and spinal injuries than did pedestrians in other crash types, and unlit darkness and non‐built‐up roadways were associated with an increased risk of pedestrian head injuries. Several crash features (e.g. unlit darkness, overtaking manoeuvres, phone use by pedestrians and drivers, and intoxicated drivers) are more frequently evident in back‐to‐traffic crashes than in other types of crashes. The current research suggests that in terms of crash consequence, facing traffic is safer than back to traffic. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of intake valve swirl on fuel-gas mixing and subsequent combustion in a CAI engine

A fully three-dimensional model was used to investigate the optimal value for intake valve lift in a CAI engine. Uniform mixing in the engine is a key parameter that affects the auto-ignition reliability and thermal efficiency. The method of intake of the air supply often determines the uniformity (or quality) of the fuel-air mixture. In this paper, four strategies were applied for controlling the swirl intensity of intake air. The variation of the intake valve lift induces different swirling and tumbling intensities. Both experimental data and 1D WAVE software (Ricardo, Co.) were coupled with the 3D model to provide pressure and temperature boundary conditions. The initial condition of the EGR mass fraction was also provided by the 1D model. The benchmark scenario (Case 1) was considered as a valve lift with 2 mm for all intake valves. We found that an intake valve lift of 6 mm with the other intake valve closed (i.e., Case 5) yielded the largest swirling (helical motion in the axial direction) and tumbling, which in turn rendered optimal fuel-gas mixing. We also found that fuel distribution affected the auto-ignition sites (or spot). The better the mixing, the greater the gas temperature and combustion efficiency achieved, as seen in Case 5. The NOx level, however, was increased due to the gas temperature. The optimal operating condition is selected from the viewpoints of environmental protection and combustion efficiency.     

基于拉姆塞定价模型的天津地铁价格定价研究

目前国内的地铁票价大多采取单一票价制或者计程票价制，虽然这在票价上体现了公平，但是，如果利用地铁票价的价格杠杆来引导客流，就可以进一步提高公共交通系统的效率，改善社会福利。研究认为，应用拉姆塞定价原理采用高峰定价法可以实现这种效果。此文从经典的最优拥挤定价理论出发，分析城市道路拥挤定价中的交通需求的变化和在拥挤定价条件下的交通需求预测问题，探讨拥挤定价的收费标准对出行方式选择和需求的弹性，为该高峰分时段定价政策的实施奠定理论基础。     

非对称连拱隧道非对称中隔墙施工力学行为研究

为研究非对称连拱隧道中非对称中隔墙在施工过程中的力学特性,以湖南省塞子界隧道为工程背景,基于普氏平衡理论,分析了中隔墙的受力特点和偏转机制;建立MIDAS/GTS三维数值模型,模拟分析不同形式的中隔墙在施工过程中位移和应力的变化规律,对比分析了隧道施工监测数据与数值模拟数据。研究结果表明：在非对称连拱隧道(左侧大洞径隧道、右侧小洞径隧道)中,中隔墙会向大洞径隧道发生偏移,且发生逆时针偏转;以中导洞中心线对称,减小小洞径隧道侧中隔墙厚度,使小洞径隧道侧中隔墙厚度小于大洞径隧道侧中隔墙厚度时,左右隧道拱顶沉降均减少,中隔墙下墙角处竖向位移、中隔墙中心线顶点和中隔墙墙底中点水平位移均减小,中隔墙上墙角受力情况更良好,整体偏转幅度更小,稳定性更高,但非对称中隔墙整体厚度减小量应适量。     

基于混合式磁浮平台的解耦及控制分析

为了研究磁悬浮平台系统中存在的多自由度耦合问题,提出一种利用永磁体之间的被动受力来减少竖直方向上主动控制的设计思路,给出一种混合斥力式磁浮平台的结构设计,该磁悬浮结构的定子由永磁体和电磁线圈共同组成,由永磁体提供主要的悬浮力,电磁线圈提供水平方向的驱动力,以此减少负责主动悬浮的线圈数量,减小线圈功耗及产热. 基于磁荷模型推导出磁标量势满足的拉普拉斯方程,利用分离变量法求出磁标量势的解析表达式,并对浮子在整个磁场中的受力进行精确的计算;充分研究探讨了定子与动子永磁体之间被动悬浮力的稳定区域,简化忽略了竖直方向上力的解耦,建立被控对象的数学模型,并研制了以微控制单元为中心的数字集成控制器,通过试验研究了平台的悬浮性能. 研究结果表明:本文所提出的混合斥力式磁浮平台在悬浮高度23 mm水平范围 ± 4 mm内,能够实现稳定的水平运动,并且浮子在垂直方向的位移变化不超过0.2 mm.      

图像分块下的隧道裂缝识别方法

针对隧道衬砌表面不均匀光照、渗水和噪声等强视觉干扰,设计了基于图像分块的隧道衬砌裂缝检测算法;根据中国西部地区的地理特征和隧道衬砌的外观病害,研制开发出一种快速、自动化的非接触式智能隧道结构物外观检测系统; 以非均匀光照下隧道图像数据集为研究对象,在图像分块的基础上提出一种适用于隧道裂缝特征提取的图像识别算法;研究了电子元件产生的噪声,并分析和总结了隧道衬砌的灾害特征;根据裂缝特征和分辨率将图像矩阵划分为适当数量的区域块,根据区域块的灰度特征将原始图像划分为目标背景区、目标病害区、病害背景区和其他区域,通过最大类间方差法和局部阈值法分割得到了隧道裂缝的粗图像,在此基础上进行了粗图像裂缝特征提取;对原始图像的每个区域块进行了对比度受限的自适应直方图均衡操作和局部阈值分割,得到了细节图像;将细节图像和粗图像的重叠区域设为理想裂缝二值化图像;结合隧道结构物外观检测系统对不同方向的裂缝图像进行了二值化试验,并通过隧道裂缝定位和投影法得到了隧道衬砌图像中裂缝的位置信息和方向。研究结果表明:提出的算法对隧道裂缝识别的准确值、召回率和F值可分别达90.34%、98.78%和94.37%,既可以保证隧道裂缝的完整性,也可以在非均匀光照下最大程度地保留目标裂缝的细节,可用于处理一般灰度图像的二值化问题。      

基于Domino的OA系统调优

针对基于Domino的OA系统当前存在的性能问题进行分析,找出造成性能瓶颈的原因,并提出可行的解决方案来优化性能。     

水平泥岩砂岩互层隧道超欠挖控制技术

水平泥岩砂岩互层围岩的地质特点导致围岩在施工爆破后易沿结构面及软弱破坏面破坏,形成较难人为控制的超欠挖现象。以大梁峁特长公路隧道为工程背景,提出了相应的超欠挖控制措施：采用科学合理的控制爆破技术和施工措施,经此处理后,超欠挖值明显减小,开挖面基本平整、光滑,隧道施工过程中未发生塌方事故,拱顶掉块也明显减少。     

长大货物车回送时混编列车纵向冲动分析

使用空气制动系统与纵向动力学联合仿真系统,计算l辆HXD1机车+60辆载重C70车辆+1辆HXD1机车短编组列车加挂350 t落下孔车回送运行施行紧急制动的列车纵向冲动,分析350 t落下孔车编组位置、前后机车操纵同步性对回送列车的纵向动力学影响.仿真分析表明,主控机车和从控机车操作同步性能的好坏直接决定了整列车纵向动力学性能,350 t落下孔长大货物车的位于列车中部时列车最大车钩力增幅最小.     

一种严密的高精度自由设站方法研究

为提高全站仪自由设站精度,降低全站仪挑选标准,从而增强全站仪的适用性,本文详细研究了全站仪加常数、乘常数及竖盘指标差等误差对自由设站精度的影响,并针对不同误差源提出了提高全站仪自由设站精度的不同处理方法:(1)对于能快捷测定的系统误差通过外业现场测定系统消除;(2)对于不易测定的系统误差和偶然误差通过附加参数的平差方式...