A methodology for assessment of long-term exposure to whole-body vibrations in vehicle drivers to propose preventive safety measures

Introduction: The appearance of musculoskeletal disorders (MDs) in professional drivers due to exposition to whole-body vibration (WBV) makes it relevant to assess this exposure. The European Directive 2002/44/EC has two methods to evaluate exposure to WBV (defined in ISO2631-1:2008). These methods evaluate the exposure associated with an 8-hour working day; however, MDs due to WBV could also be caused by accumulated exposure to vibrations over long term, and hence, the methods defined in the European directive may be limited in their ability to ensure the safety of workers exposed to WBV throughout their years of employment. Method: A detailed comparison and discussion of methods defined in the European Directive and the ISO2631-5:2018 was used as a starting point of the main results of this paper. On this basis, a new methodology for the management and organization of preventive measures is proposed to consider the assessment of ISO2631-5:2018 standard and the full working life of workers. Experimental data to assess exposure to WBV in heavy equipment vehicle (HEV) drivers under different road surface conditions and range of velocities were considered to illustrate the process of the proposed methodology. Results: The methods defined in the standards provide different assessments leading to a different possible consideration of safe operations when the risks associated with them may actually be high. The proposed methodology can be used with the aim of ensuring safety of workers throughout their working lives and providing an easy implementation of the calculations of ISO2631-5:2018 standard. Conclusions: A procedure to assess the health risk probability to which the HEV worker is exposed in terms of the exposure years and a different range of operational vehicle speeds is proposed and exemplified with a study case. Practical applications: This study provides a practical tool for the management of WBV exposure related to work-tasks in HEV drivers. Safety managers should consider the global exposition to WBV throughout their working life, and this research provides an easy tool to accomplish it.     

柴油车尾气颗粒物排放现状评价

对2013年哈尔滨市不同供油方式的柴油车排气细颗粒物或黑碳测量参数—光吸收系数进行了统计分析,结果表明:涡轮增压和自然吸气供油方式光吸收系数均值分别为1.39 m-1和1.27 m-1,超标率分别为5.8%和2.4%,采用颗粒物控制措施及排气装置强制维护降低了颗粒物排放,符合排放标准。     

利用IVE模型建立成都市轻型汽油客车排放清单

城市机动车污染物排放清单的建立是控制机动车污染的关键.本研究以2012年为基准年,通过对成都市轻型汽油客车技术水平分布、活动水平和保有量等数据的调查,将IVE模型本地化,计算了成都市2012年轻型汽油客车VOCs、PM、NOx、CO的排放清单,并分析了清单的不确定性.结果表明:成都市2012年轻型汽油客车排放的VOCs、PM、NOx和CO分别为2.23×104t、1.6×102t、1.26×104t和2.03×105t;轻型汽油客车中黄标车VOCs、PM、NOx、CO的排放量分别占排放总量的27.5%、18.1%、37.2%和42.5%,表明黄标车是轻型汽油客车污染物排放的主要来源;排放清单的不确定性主要来自于排放因子,VOCs、PM、NOx和CO清单的不确定性分别为-31.67%~32.35%、-54.75%~55.09%、-6.56%~6.76%和-12.22%~12.51%.     

Perceptions of safety on a shared road: Driving,cycling, or walking near an autonomous vehicle

Introduction: While improved safety is a highly cited potential benefit of autonomous vehicles (AVs), at the same time a frequently cited concern is the new safety challenges that AVs introduce. The literature lacks a rigorous exploration of the safety perceptions of road users who will interact with AVs, including vulnerable road users. Addressing this gap is essential because the successful integration of AVs into transportation systems hinges on an understanding of how all road users will react to their presence. Methods: A stated preference survey of the Phoenix, Arizona, metropolitan statistical area (Phoenix MSA) was conducted in July 2018. A series of ordered probit models was estimated to analyze the survey responses and identify differences between various population groups with respect to the perceived safety of driving, cycling, and walking near AVs. Results: Greater exposure to and awareness of AVs are not uniformly associated with increases in perceived safety. Various attitudinal factors, level of AV automation, and other intrinsic and extrinsic factors are related to safety perceptions of driving, walking, and cycling near AVs. Socioeconomic and demographic characteristics, such as gender, age, income, employment, and automobile usage and ownership, have various relationships with perceived safety. Conclusions: Cycling near an AV was perceived as the least safe activity, followed by walking and then driving near an AV. Both similarities and differences were observed among the factors associated with the perceived safety of different travel alternatives. Practical Applications: Public perception will guide the development and adoption of AVs directly and indirectly. To help maintain control of public perception, transportation planners, decision makers, and other stakeholders should consider more deliberate and targeted messaging to address the concerns of different road users. In addition, more careful pilot testing and more direct attention to vulnerable road users may help avoid a backlash that could delay the rollout of this technology.     

Optimization of the recovery of plastics for recycling by density media separation cyclones

Material recovery processes are presented as the optimum option for recycling plastic wastes as a means of recovering hydrocarbon resources. There exist a large variety of automated material recovery processes for recycling of such wastes but each with significant limitations. Of these, the separation based on differences in densities is advocated as the optimum process either for producing recycled products or preparing wastes for subsequent recovery processing.Density separation processes based on cyclone type density media separation (DMS) is presented as an important, potential method for increasing plastics recycling process capacities. It is demonstrated to have the capacity to separate a significantly larger range of particle sizes than those presently processed industrially. The mathematical relationship for the prediction of quality of typical LARCODEMS type density media separations by particle size and density as expressed by the Ecart Probable is presented.A proposed device configuration is presented for density media separation to optimize the recovery and purity of both density fractions produced. It is also suggested that to be economically viable, a large scale of operation is required for industrial plastics recycling operations recovering and producing a number of different plastics with a purity to be used as a substitute for virgin material.     

Giving green to get green? Incentives and consumer adoption of hybrid vehicle technology

Federal, state, and local governments use a variety of incentives to induce consumer adoption of hybrid-electric vehicles. We study the relative efficacy of state sales tax waivers, income tax credits, and non-tax incentives and find that the type of tax incentive offered is as important as the generosity of the incentive. Conditional on value, sales tax waivers are associated with more than a ten-fold increase in hybrid sales relative to income tax credits. In addition, we examine how adoption varies with fuel prices. Rising gasoline prices are associated with greater hybrid vehicle sales, but this effect operates almost entirely through high fuel-economy vehicles. By comparing consumer response to sales tax waivers and estimated future fuel savings, we estimate an implicit discount rate of 14.6% on future fuel savings.     

中国国道和省道机动车尾气排放特征

近年来,随着我国机动车保有量的持续增长,机动车排放已成为我国重要的大气污染物来源之一.现有的机动车排放研究多关注城市内的机动车大气污染物排放,针对城市间的大气污染物排放研究较少.我国城市间交通道路主要包括国道和省道,截止至2015年我国国道里程18.53万km、省道里程32.97万km,约占全国等级公路总里程的13%,因此开展我国国道和省道机动车大气污染物排放研究十分重要.本研究基于全国国道和省道交通监测站的年均监测数据,采用环境保护部发布的《道路机动车大气污染物排放清单编制技术指南(试行)》中的指导方法,计算了2015年我国国道和省道机动车的大气污染物排放清单,分析了污染物排放的时空分布特征.结果表明,我国国道和省道公路机动车排放的一氧化碳(CO)、氮氧化物(NO_x)、颗粒物(PM)和碳氢化合物(HC)排放量分别占全国机动车污染物总排放量的4.5%、27.9%、14.4%和7.7%;不同车型对国道和省道机动车大气污染物排放的分担率不同,其中大货车是NO_x、PM_(10)、PM_(2.5)的主要来源,摩托车是CO和HC的主要来源;不同道路类型中各车型的大气污染物排放分担率也不同,如高速路上大货车是NO_x、PM_(10)和PM_(2.5)的主要来源,普通道路上大客车和大货车是NO_x、PM_(10)和PM_(2.5)的主要来源.     

Regulated emission characteristics of in-use LNG and diesel semi-trailer towing vehicles under real driving conditions using PEMS

On-road driving emissions of six liquefied natural gas(LNG) and diesel semi-trailer towing vehicles(STTVs) which met China Emission Standard IV and V were tested using Portable Emission Measurement System(PEMS) in northern China.Emission characteristics of these vehicles under real driving conditions were analyzed and proved that on-road emissions of heavy-duty vehicles(HDVs) were underestimated in the past.There were large differences among LNG and diesel vehicles, which also existed between China V vehicles and China IV vehicles.Emission factors showed the highest level under real driving conditions, which probably be caused by frequent acceleration, deceleration, and start-stop.NOx emission factors ranged from 2.855 to 20.939 g/km based on distance-traveled and 6.719–90.557 g/kg based on fuel consumption during whole tests, which were much higher than previous researches on chassis dynamometer.It was inferred from tests that the fuel consumption rate of the test vehicles had a strong correlation with NOx emission, and the exhaust temperature also affected the efficiency of Selected Catalytic Reduction(SCR) aftertreatment system, thus changing the NOx emission greatly.THC emission factors of LNG vehicles were 2.012–10.636 g/km, which were much higher than that of diesel vehicles(0.029–0.185 g/km).Unburned CH_4 may be an important reason for this phenomenon.Further on-road emission tests, especially CH_4 emission test should be carried out in subsequent research.In addition, the Particulate Number(PN) emission factors of diesel vehicles were at a very high level during whole tests, and Diesel Particulate Filter(DPF)should be installed to reduce PN emission.     

Efficient energy management strategies for hybrid electric vehicles using shuffled frog-leaping algorithm

This paper proposes two novel approaches for the problem of energy management in hybrid electric vehicles. Shuffled frog-leaping algorithm (SFLA) is a recently proposed population-based optimization algorithm. This paper first formulates energy management as an optimization problem and optimizes the problem using SFLA. Then the paper makes use of SFLA as a training algorithm to train artificial neural network (ANN) and this SFLA-trained ANN is used for energy management. Interestingly, the proposed approaches of this paper are found to be robust and more efficient than contemporary approaches.     

克拉玛依市机动车污染现状调查与防治对策研究

在调查克拉玛依市机动车尾气污染的基础上,分析存在的问题,并针对性地提出城市交通污染的控制对策.