基于隐性危险驾驶人感知特性及判别模型研究*

为研究驾驶人在隐性危险场景中危险感知行为,基于Bayes判别法,将驾驶行为指标作为输入变量,建立驾驶人危险感知能力预测模型。结果表明:驾驶员在显性危险场景的纵向加速度显著低于隐性危险场景;驾驶人在隐性危险场景中TTC值小于显性危险场景;在被试车辆与轿车、行人、非机动车冲突3种交通冲突场景中,驾驶人对行人危险感知能力最弱。研究结果对提高道路交通安全水平以及驾驶人应急避险能力具有一定实际指导意义。     

掘进面多级气相压裂卸压抽采防突研究*

为解决煤层赋存条件复杂、煤体渗透率低、部分区域突出易发性高等问题,提出运用多级气相压裂的方案在阳泉矿区新元矿31004工作面辅助回风巷与进风巷进行压裂试验,以考察其卸压增透效果;在试验巷道的不同区段实施单孔压裂和双孔压裂,并采用“压裂抽采”和“压后即掘”2种工作循环方式进行试验;基于对多项抽采参数的实测结果,从多角度评价多级气相压裂效果。结果表明:多级气相压裂具有明显的重启裂缝与扩张裂缝作用,能够有效改善煤体的渗透性和瓦斯抽采条件;通过对比单孔压裂与双孔压裂效果,并结合现场监测数据发现,双孔多级压裂的效果明显优于单孔多级压裂,双孔多级压裂钻孔作业难度低,且作业后瓦斯更易抽采;观测不同的工作循环方式未见明显差距,但“压后即掘”的工作效率明显更高。多级气相压裂的成功实施,对该技术在低渗矿区的防突消突与瓦斯抽采工作中的应用具有重要指导意义。     

“Like it’s wrong,but it’s not that wrong:” Exploring the normalization of risk-compensatory strategies among young drivers engaging in illegal smartphone use

Introduction: Young drivers are the most vulnerable road users and most likely to use a smartphone illegally while driving. Although when compared with drink-driving, attitudes to illegal smartphone risk are nearly identical, smartphone use among young drivers continues to increase. Method: Four in-depth focus groups were conducted with 13 young (18–25 years) drivers to gain insight into their perceptions of the risks associated with the behavior. Our aim was to determine how drivers navigate that risk and if their behavior shapes and informs perceptions of norms. Results: Three key themes emerged: (a) participants perceived illegal smartphone use as commonplace, easy, and benign; (b) self-regulatory behaviors that compensate for risk are pervasive among illegal smartphone users; and (c) risk-compensation strategies rationalize risks and perceived norms, reducing the seriousness of transgression when compared with drink-driving. Young drivers rationalized their own use by comparing their selfregulatory smartphone and driving skills with those of “bad drivers,” not law abiders. Practical Applications: These findings suggest that smartphone behaviors shape attitudes to risk, highlighting the importance for any countermeasure aimed at reducing illegal use to acknowledge how a young person’s continued engagement in illegal smartphone use is justified by the dynamic composition of use, risk assessment and the perceived norms.     

Exploring relationships between microscopic kinetic parameters of tires under normal driving conditions,road characteristics and accident types

IntroductionFreeway accidents are a leading cause of death in China, which also triggers substantial economic loss and an emotional burden to society. However, the internal mechanism of how microscopic kinetic parameters of vehicles influenced by road characteristics determine the occurrence of different types of accidents has not been explicitly studied. This research aimed to explore the “link role” of tire microscopic kinetic parameters in road characteristic variables and traffic accidents to aid in facilitating the traffic design and management, and thus to prevent traffic accident. Method: A mountain freeway in Zhejiang Province, China was used as the research object and the data used in this paper were obtained through a real-time vehicle experiment. Multiple estimation models, including the standard ordered logit (SOL) model, fixed parameters logit (FPL) model, and random parameters logit (RPL) model were established. Results: The findings show that road characteristics will affect the longitudinal kinetic characteristics of the vehicle and, consequently, map the level of risk of rear-end accidents. Driving compensation effects were also identified in this paper (i.e., the drivers tend to be more cautious in complicated driving circumstances). Another finding relating to the mountain freeway is that different tunnel characteristics (e.g., tunnel entrance and tunnel exit) have different effects on different types of traffic accidents. Practical Applications: The framework proposed in this article can provide new insight for researchers to enlarge the research subjects of both explanatory and outcome variables in accident analysis. Future research could be implemented to consider more driving conditions.     

Changes in distribution patterns of weed species richness in agricultural lands on Qinghai-Tibet Plateau under climate change北大核心CSCD

农田杂草是阻碍农业生产的主要因素之一.明确农田杂草丰富度分布格局对农业生产管理具有重要意义.以青藏高原农田杂草为研究对象,利用物种分布模型探讨基于县域尺度的农田杂草物种丰富度分布格局及其未来(2050s)的变化,利用逐步回归筛选影响物种丰富度的环境因子,基于传统最小二乘法(OLS)和地理加权回归模型(GWR)分析环境因子对农田杂草物种丰富度的影响,并对两种分析方法进行比较.结果显示:(1)分布在青藏高原的农田主要杂草有51科284种,其中59种单子叶杂草、222种双子叶杂草、135种一年生杂草和149种多年生杂草.青藏高原农田杂草物种丰富度呈由西向东递增的变化规律,物种丰富度中心(丰富度值为167-194)主要集中在一江两河、河湟谷地和川西北等地区;(2)全球气候变化背景下,未来(2050s)青藏高原农田杂草物种丰富度整体呈由东南向西北方向增加的趋势,其中SSP1-2.6情境下最多增加43种,SSP5-8.5情境下最多增加49种;(3)GWR模型优于OLS,其结果表明青藏高原农田杂草物种丰富度的主要驱动因子是最冷季平均温、太阳辐射和最干月降水量,上述变量对杂草丰富度的影响存在明显的空间差异性,其中最冷季平均温由南向北逐渐从负向影响转变为正向影响.太阳辐射整体在青藏高原东部边缘等地区对农田杂草丰富度起正向的影响,在藏东南、青藏高原北部边缘等地区起负向的影响.最干月降水量对整个研究区域起负向影响,并表现出影响力由南向北逐步递增的趋势.上述结果表明青藏高原农田杂草物种丰富度调查不足,实际观测到的丰富度值明显低于当前气候下潜在的丰富度值,存在低估现象.当前气候背景下的农田杂草物种丰富度中心分布地区在未来仍是重点监管对象,且未来青藏高原部分地区作物可能面临新的杂草入侵风险.建议未来研究应注重于青藏高原粮食主产区农田杂草群落结构和功能调查、杂草和作物种间关系、耕地尺度上丰富度驱动因子分析等方面,为区域杂草管理和防治提供充分科学依据.(图6表2参53)     

中国土地沙漠化、水土流失和盐渍化的原因和驱动力:总体分析

论文收集了102篇沙漠化、79篇水土流失和64篇盐渍化的案例研究(共245篇),运用总体分析方法,把造成3种生态环境问题的因素归结为四类原因(农业扩张、资源利用、基础设施建设和自然因素)和五类驱动因子(经济、制度、技术、文化和人口)。分析结果表明,生态环境问题绝大多数由多因子所引起;在原因层面上,对沙漠化、水土流失和盐渍化案例影响最频繁的因子分别是农业扩张因子(92%)、资源利用因子(90%)和自然因素(86%);从驱动因子的层面上看,对沙漠化、水土流失和盐渍化案例影响最频繁的都是经济因素,影响频率分别为86%、81%和89%;总体来看,在发生生态环境问题的区域中,往往以经济因素的影响最为常见(85%),其次为技术(69%)和人口因素(62%)。因此,不适当地发展经济是造成我国沙漠化、水土流失和盐渍化日益严重的重要原因。     

中国农牧交错区土地利用变化空间格局与驱动力分析

以遥感与GIS为技术支撑,运用专家知识,结合实际,从农牧交错区的实质出发,定量地计算出我国的农牧交错区。在此基础上,分析我国农牧交错区近10年的耕地、草地变化的空间格局。整个农牧交错区的耕地以变林地、草地为主。耕地的变化以内蒙古的变化为大,主要分布于它的中、东部地区。草地主要以变耕地、城镇为主,分布于内蒙古与东北三省接壤处。最后探讨这种格局的成因。耕地变化受经济发展、人口增加、农业结构等驱动,主要表现为人文作用。草地变化受人为与自然的驱动,主要为人类活动的影响,表现为经济发展与草地过牧。     

蒸汽驱采废水回用高压锅炉给水处理工艺的研究

对蒸汽驱采废水回用高压锅炉给水处理工艺进行了研究,并对比分析了不同的工艺组合流程对蒸汽驱采废水回用高压锅炉给水的处理效果。结果表明,蒸汽驱采废水回用高压锅炉给水处理在技术上是可行的,并提出推荐工艺流程。     

流体流动状态对超滤效率及膜污染的影响

超滤技术作为膜分离技术的一种,由于具有效率高、能耗低等优点已经被多种行业广泛应用.但是,浓差极化和膜污染却极大降低膜分离效率,成为制约膜分离技术推广应用的重要因素.解决和减轻浓差极化和膜污染的方法有很多,本文着重于流体流动状态对浓差极化和膜污染的影响进行了论述.     

有机底物对活性污泥胞外聚合物的影响

研究了城市污水中常见的具有不同特性的有机底物(蛋白胨、葡萄糖、乙酸钠,以及乙酸钠和葡萄糖的混合物)分别在四个相同的反应器中所培养的活性污泥胞外聚合物的量和组成．结果表明：有机底物的特性影响胞外聚合物的组成和量,在乙酸钠为底物的污泥中,胞外多糖占大部分(糖类／蛋白质的比值为1．7—8.6,质量比),而以蛋白胨为底物时,胞外蛋白质占主要成分(糖类／蛋白质的比值为0.2-0.5);以乙酸钠为底物形成的胞外聚合物的总量较多,通过扫描电子显微镜和原子力显微镜对活性污泥进行观测,确证了胞外聚合物的存在及其形式,并得到了胞外聚合物层的大致尺寸．