彩虹粉引燃危险性实验研究

为了研究彩虹粉引燃危险性,应用固体燃烧速率试验仪初步甄别了彩虹粉传播燃烧能力,发现堆垛状彩虹粉固体火焰传播危险性较低;采用粉尘爆炸筛选装置,判定彩虹粉具有爆炸性;应用最小点火能测定装置测定彩虹粉粉尘云的最小点火能在24~60 mJ之间,最优爆炸浓度为1 167 g/m3;应用快速筛选量热仪测试,彩虹粉在227℃开始分解;固体自燃点测试仪显示彩虹粉在250℃附近会发生自燃。向彩虹粉内添加不同比例相近粒径分布的食用盐粉体进行抑爆研究,结果证明食用盐对彩虹粉具有明显的抑爆效果。     

西安市城市主干道路面径流颗粒物沉降性能及粒径分布研究

在西安市城市主干道南二环路建立路面径流采样站,利用自制流量等比例采样装置,采集2009年4-9月的16场降雨路面径流,采用累积曲线法试验研究路面径流中颗粒物的沉降性能和粒径分布,并就降雨特征对径流中颗粒物粒径分布影响进行分析.结果表明,沉降可有效去除颗粒物,沉降60 min和2 h平均去除率分别为78.4%和86.3%. 要达到45%、60%和80%的沉淀去除率,表面负荷应分别为1.1～9.3 cm/min、0.6～5.9 cm/min和0.1～2.7 cm/min.沉淀去除率每提高10%,表面负荷相应减少1.3～3倍. 径流中颗粒物粒径分布呈宽幅变化,d10、d50、d90分别为3～23 μm、17～56 μm和40～65 μm,表明径流中颗粒物以粒径3～65 μm的细颗粒为主. 最大降雨强度与颗粒物粒径相关性较强,其他因子与颗粒物粒径相关性不强,降雨强度是影响径流中颗粒物粒径分布的主要因素.     

基于响应曲面法的松散煤体导热系数测试与分析

为研究松散煤体导热系数随其影响因素的变化规律,基于平行热线法和交叉热线法,通过自制的试验装置测得不同粒径、温度和含水率下松散煤体的导热系数,并拟合导热系数与温度、含水率的变化曲线;引入二次响应曲面法,对粒径、温度和含水率做Box-Behnken试验设计,得出影响因素的重要度排序。结果表明:借助试验装置进行试验,能够准确测算松散煤体导热系数,测量误差在3. 0%以内,并能同时得到热扩散率与比热容;松散煤体导热系数随粒径的增大而减小,随温度的升高而降低,随含水率的增大而增大;三因素对导热系数一次项重要度排序为含水率粒径温度,二次项重要度排序为粒径和温度粒径和含水率含水率和温度,且粒径和温度间存在交互作用,其余无交互作用。     

基于视频轨迹参数的边缘率减速标线驾驶行为效果评价方法

为探究边缘率减速标线对驾驶行为与交通安全的作用效果,提出了基于监控视频提取轨迹参数的实证评价方法.采用背景差法和透视变换方法对监控视频进行车辆目标提取和轨迹处理,进而提取车辆速度、加速度、车头时距、车头间距和车道偏移等行车参数;通过参数统计分析,边缘率减速标线对车速控制、跟车距离保持和车道保持都有不同程度的控制效果,但使纵向舒适性变差;为了综合评价其效果,基于层次分析法建立了边缘率标线的综合控制效果评价模型,从有效性、安全性和舒适性3个维度对减速标线进行综合评价.该方法和模型还可用于评价其他不同设计参数的减速标线.     

大叶女贞叶面结构对滞留颗粒物粒径的影响

为分析叶面微结构对滞留颗粒物粒径的影响,以分布较广的常绿植物——大叶女贞为研究对象,用激光粒度分析仪(湿法)测定叶面尘的粒径分布,用扫描电子显微镜和原子力显微镜观察叶面微结构;并用图像处理软件(图像法)分析叶面颗粒物的粒径特征,探讨不同测定方法对叶面颗粒物粒径分布的可能影响.结果表明,大叶女贞叶面滞留颗粒物粒径呈双峰分布,湿法测定的颗粒物粒径范围为0.4～ 52.6μm,粒径峰值为18.9 μm、36.2 μm,粒径均值为8.8 μm;图像法测定的颗粒物粒径范围为0.4～27.8 μm,粒径峰值为17.5μm、27.8μm,粒径均值为7.2μm.叶表面分布有大量的突起和凹陷,凹陷直径介于0.6～ 30 μm,直径小于2.5μm和10 μm的凹陷约占到总量的50％和80％.可吸入颗粒物(PM10)和细颗粒物(PM2.5)主要滞留在叶表的凹陷结构中,有少量粒径大于10 μm的颗粒物滞留在突起之上.PM2.5和PM10的体积分数仅占滞尘总量的17.9％和50.4％(湿法)、16.8％和45.9％(图像法),但数量多于大粒径颗粒物,这与小粒径的颗粒在个数上占优势、但大粒径的颗粒则对叶面滞留颗粒物的质量(或体积)贡献较大有关.叶背面颗粒物附着密度较正面小,PM2.5等颗粒物多分布在气孔周围,有少量颗粒物沉积在气孔上,从而堵塞气孔.     

三环唑粉尘爆炸特性研究

利用激光粒度仪对三环唑粉尘的粒径分布进行分析,并用20 L爆炸球测试装置、哈特曼管装置探讨了粉尘质量浓度、点火延迟时间、点火能量、粒径分布对粉尘爆炸的影响并总结了相关规律。实验结果表明:粉尘粒度是影响粉尘最小点火能和爆炸下限的单调因素,粉尘质量浓度是影响粉尘爆炸压力的极值因素,点火延迟时间是影响粉尘最小点火能的极值因素。     

垃圾焚烧飞灰中重金属的分布规律及化学形态分析

研究了重庆市垃圾焚烧发电厂焚烧飞灰的粒径分布,分析了焚烧飞灰中重金属的含量、浸出特性和形态分布特征,讨论了不同粒径飞灰中重金属的分布特性.结果表明,大部分飞灰粒径集中在38～250 μm,其中粒径为38～100μm飞灰占总量的49.49%.飞灰浸出液中Pb和Zn的浓度均超出了<危险废物浸出毒性鉴别标准>(GB5085.3-2007),因此该焚烧飞灰被认定为危险废物.在＜250μm粒径范围内,Cd、Cr、Cu、Mn和Pb普遍表现出向小颗粒富集的趋势;Zn的粒径分布则与上述5种元素表现出相反的趋势;Ni的分布与粒径的相关性不大,在各粒径上的分布较均匀.除Ni元素外,用BCR法分析所得的其他6种重金属形态分析结果和总量测定的结果基本吻合.飞灰中Cr、Ni、Zn和Mn主要以稳定态存在,而Cd、Pb和Cu则主要以不稳定态存在.     

狮城话交通

有幸去了一趟新加坡,岛国花园城市狮城,给人的感觉确实是耳目一新。无论是大街小巷,还是主干道,路面上、交叉口都漆画着清晰可见的交通标线,指引直行、左转弯、右转弯等行车方向。几乎每个路口都能看到悬挂整齐的交通标志,指示前方的主要景点、商店、单位的距离。一般街区的路口都设有闪烁不停的交通信号,控制车辆和行人的行进或     

承压设备两大CI法的图像质量评价

介绍承压设备超声检测计算机成像(CI)两大主流技术——TOFD法和PAUT法有关检测结果图像显示质量的等级评定要点。相位灰度对比度和端部分辨力,是TOFD斑马纹图的像质评定要素;相应于脉冲回波动态曲线的色谱显示,是PAUT彩虹图的像质评定要素。结合焊接试样中已知缺陷的检测显示,给出了像质评定示例。引述了最新国际动态,意在为国内及早推出承压设备CI法相关图像质量评定标准提供有用借鉴。     

狮城话交通

有幸去了一趟新加坡，岛国花园城市狮城，给人的感觉确实是耳目一新。无论是大街小巷，还是主干道，路面上、交叉口部漆画着清晰可见的变通标线，指引直行、左转弯、右转弯等行车方向，几乎每个路口都能看到悬挂整齐的交通标志，指示前方的主要景点、商店、单位的距离。一般街区的路口都设有闪烁不停的交通信号，控制车辆和行人的行进或停止。     

Sight obstruction at at-grade pedestrian crossings: A review of the understanding of the meaning of zigzag lines

Parked and stopped vehicles in the vicinity of an at-grade pedestrian crossing obstruct visibility between pedestrians crossing the roadway and approaching vehicles, leading into vehicle–pedestrian crashes. Pavement zigzag line markings at at-grade pedestrian crossings, mostly at mid-block locations are used to restrict parking, stopping, and overtaking within the crossing, to enhance driver–pedestrian visibility. Yet, in some countries zigzag lines are used as advance markings to the crossing. Like any other traffic control device, zigzag lines’ effectiveness hinges on road user’s understanding of their meanings.This paper reviews the literature on the applications and understanding of these lines at pedestrian crossings. The meaning of zigzag line pavement markings at pedestrian crossings has not been well understood to some road users and road safety stakeholders worldwide. This dilemma may suggest that educating road users, especially drivers, may be necessary in order to improve pedestrian safety. Documented literature such as this one may also improve the understanding of these lines to road safety stakeholders. Despite of the importance of unobstructed sight between the pedestrian and the driver, treatments in the forms of signs and pavement markings require continuous education and enforcement. Practicing traffic engineers may want to place more emphasis on engineering treatments that are more effective in improving pedestrian safety, such as those that manages vehicle speeds, than relying heavily on traffic control devices that are often misunderstood and lesser effective such as zigzag lines.     

Charging behavior of glass beads using a spiral air type tribocharging apparatus that utilizes a Faraday cup

This paper introduces a novel tribocharging apparatus that utilizes a Faraday cup and experimentally investigates the charging behavior of glass beads. The novel apparatus mainly consists of four parts: an air supply part to control air duration and pressure, a powder supply part for setting the desired amount of powder (1 g in this experiment), a metal pipeline for generating a tribocharge, and a cyclone for collecting the powder that has passed through the pipeline. Four different sizes of spherical glass beads were used in this experiment. As for the results, the charge clearly increased as the glass bead particles passed through the pipeline for all four types of glass beads. The charge amount of the glass beads and the charge amount obtained from the pipeline had a very similar trend and absolute values. This confirmed the reliability of the test and showed that there was no disturbance due to external noise. In all of the tests, the net charge was observed to be negative for all glass beads. This agrees with the triboelectric series relating to the work functions of metals and glass particles. Smaller particles had larger charge amounts than did larger ones with good reproducibility. The charge amount of all glass beads increased as the supplied spiral air pressure increased.     

Effect of novel divergence markings on conflict prevention regarding motorcycle-involved right turn accidents of mixed traffic flow

Introduction: In Taiwan, segregated traffic flow countermeasures have long been in place. Although these facilities have decreased the numbers of motorcycle left-turn collisions, right-angle collisions, and sideswipe collisions, they have also induced serious right-turn accidents. The purpose of this research was to evaluate an intervention intended to decrease conflicts and motorcycle-involved crashes. In this study, the reasons why the motorcycle accident rate is higher at intersections with slow lanes than at those without slow lanes are presented, and the theory of the self-explaining road was applied to create divergence markings for a mixed traffic flow environment. An intervention that guides motorcycles and cars into appropriate locations at intersections was applied to three intersection approaches. Method: The intervention effectiveness was evaluated by comparing the number of accidents at the intersections before and after the implementation of improvement measures. Moreover, video recordings were used to analyze the traffic distributions at the cross-sections of intersections. T-test was adopted to examine whether the traffic flows at the cross-sections of the intersections before and after the intervention were statistically different. In addition, this research applied the post-encroachment time (PET), the time between the first road user leaving the encroachment zone and the second road user arriving in it, to evaluate traffic conflicts. Finally, the PET and severity index between a straight-through motorcycle and a right-turn vehicle were analyzed. Results: PET increased by 3.2%–20.4%, and the rates of right-turn collisions, sideswipe collisions, and rear-end collisions decreased by 64.3%, 77.3%, and 61.5% respectively. Conclusions: Eliminating the slow traffic lane and setting divergence markings may not effectively cause vehicles in different driving directions to drive in the proper locations in the lanes. However, divergence markings both reduce the rate of right-turn collisions and decrease the incidence of sideswipe and rear-end collisions. Practical applications: The proposed design method may be a good design reference for countries having a high motorcycle density.     

Trajectory variability: Road geometry difficulty indicator

The analysis of the variability of vehicle trajectories can reveal important information about how situational constraints influence drivers’ behaviour (e.g., lateral position and/or speed). Variability in the lateral position using a driving simulator was examined. Forty-two participants had to drive on two road environments: a 3 km straight road with a crest vertical curve (CVC) with perceptual treatments and narrowed lane width with subsequent provision of a hard shoulder, by relocation of the road markings. The results showed that, on the one hand the lateral position variability was greater when driving on the test CVC, before meeting oncoming vehicle and on the narrowed lane width; and on the other hand it was limited according to the perceptual treatment used. The lateral position variability would be a difficulty indicator of road geometry which would inform road managers of the presence of a risk zone on their road network.     

气溶胶粉尘在玻璃表面的沉积行为研究

玻璃是建筑装修的重要材料之一.有关玻璃的表面清洁技术非常丰富,但是对于粉尘粘附于玻璃表面的行为等的研究成果尚不多见.为此, 测定了玻璃片以不同角度放置在大气中,玻璃片表面粘附粉尘的分布规律和粉尘的粒径分布等特征;发现粘附于玻璃片上粉尘粒径分布不同于大气中的粉尘粒径分布,不同湿度对玻璃表面粘附的粉尘形状、粉尘数量和粒径影响很大.     

长隧道韵律型视觉环境设计研究

采用心理物理试验分析公路隧道内部视觉环境对驾驶员行车安全的影响,将E-prime 2.0软件与仿真驾驶模拟器相结合,对驾驶员在隧道内长时间行车中的速度判断准确率及反应时间两个指标进行分析,提出了利用标志标线构建公路隧道内韵律型标线系统的改善措施,以改善隧道内视觉环境,并利用数理统计方法及Logistics拟合分析对设计方案进行评价。结果表明:1)公路隧道内韵律型标线系统能提升隧道内驾驶员的速度判断准确率3.33%~11.66%;2)普通公路隧道场景中,被试者反应时间与隧道内行车时间存在显著关系,公路隧道内韵律型标线系统的场景中,反应时间与隧道内的行车时间没有显著关系,能有效缓解视觉疲劳现象;3)被试者反应时间的增加同时受隧道内视觉环境与行车时间的影响。公路隧道内韵律型标线系统能有效提高驾驶员的反应时间,适用于行驶速度为80 km/h、大于1 333 m的隧道。     

旧路改造工程路堤稳定性安全监测方案设计

本文从旧路改造工程的特点出发,通过室内实验获取土力学参数并对沉降量进行预测计算.利用沉降仪、测斜管、孔隙水压力计、土压力盒等多种测试仪器,选取有代表性的观测断面,对经过土工格栅加筋处理的软土地基进行了高路堤施工期间的沉降与稳定观测,并提出适合工程特点的控制标准.从而达到控制路堤稳定、检验填筑质量、控制差异沉降、为路面施工提供技术支持的目的.     

Hands on explosives: Safety testing of protective measures

Several attempts have been made to test the suitability of protective measures for the handling of explosives. We investigated the suitability of safety gloves and a combined safety helmet and face shield. In the presented studies, three different experimental setups were used to simulate the effects of an explosion of a primary explosive in a glass flask on the glove or helmet protected body. Depending on the experimental setup, the fragment effects were evaluated and compared. Furthermore, the fragment distribution of an explosion inside a glass flask was investigated. The explosion of 1 g of lead azide in a 10 mL flask yielded approximately 14,000 glass fragments. However, most of the shards were accelerated down- and side-wards and only few upwards. Holding a flask on its neck (instead of its bottom) is therefore a simple but effective way of diminishing the risk of injury, when handling explosives. The safety helmet/face shield performed very well, by shielding the face from all fragments. Furthermore, it could be proven that DIN and EN standard testing procedures for gloves are unsuitable to simulate the effects of a respective explosion.In this article, the progress in the development of realistic testing procedures for the testing of gloves for the protection against fragmentation effects of glassware in situations involving explosions is reported and the results and methods of previous tests are summarized.     

固定化细胞小球降解三氟甲苯的特性研究

制备了包埋菌种z3的海藻酸钙小球，对固定化细胞小球的机械强度和三氟甲苯的降解率做了研究。通过改变海藻酸钙凝胶组成，添加硅藻土、蛋白质，使用交联剂己二胺、戊二醛等方法，提高了固定化包埋小球交联的密度和机械强度，保持了固定化小球对三氟甲苯的降解活性。扫描电镜显示了包埋小球经过己二胺一戊二醛处理之后，小球的表面结构成网格状，内部网格复杂化，不均匀程度增加。     

The effects of a traffic guidance scheme for auto-toll lanes on traffic safety at toll plazas

The Transport Department of the Hong Kong SAR government conducted a trial traffic guidance scheme at the plaza of a busy road tunnel. The scheme involves the placing of reflective road markings on the approach lanes to the toll plaza and the erection of a gantry sign that clearly distinguishes the auto-toll lane. The main purpose of the scheme is to improve traffic flow and traffic safety at the toll plaza. If the scheme is successful, then it will be applied to all other toll plazas in Hong Kong. We conducted an observational before-and-after study to assess the effects of the scheme. We found that the overall lane-changing rate decreased significantly by 23% (0.1 lane crossings per vehicle) at a significance level of 0.05, the pooled conflict count decreased sharply by 44% at a significance level of 0.10, and the crash count also decreased sharply by 38%. The mean travel time for non-auto-toll traffic increased significantly by 30% (8 s), whereas that of auto-toll Sunday traffic decreased by 18% (2 s). Both changes are statistically significant at a level of 0.05. The results indicate that the trial scheme provided good guidance to drivers. Traffic safety was improved, and the travel time of auto-toll traffic improved in certain periods, although at the expense of non-auto-toll traffic.