基于实车驾驶试验的螺旋匝道小客车纵向驾驶行为研究

为明确螺旋匝道(螺旋桥)驾驶操纵行为及车辆状态特征,选取2条桥头立交螺旋匝道和2座螺旋桥,开展小客车实车路试,通过连续采集行驶速度、加速度、踏板力等驾驶数据,分析螺旋匝道(桥)及前后衔接段的纵向驾驶行为特性.结果表明:行驶速度在螺旋匝道范围内基本恒定,并明显高于设计速度,螺旋匝道段的速度分布比主线段更集中,螺旋匝道对驾...     

干旱区土壤小麦根系界面Cd行为的环境影响研究——以甘肃省白银市区耕作灰钙土为例

通过大田环境-土壤-作物系统Cd行为的环境影响研究,初步发现,共存元素Cd、Cu、Ni、Pb、Zn对Cd元素在土壤-作物根系界面行为的影响表现为正效应,其影响顺序为Cd>Pb>Cu>Zn>Ni;pH值、粘粒、粗粉粒含量与根系Cd含量呈负相关;磷和砂粒含量与根系Cd含量呈正相关;细粉粒、粗粘粒、有机质和CEC     

Managing bog environments for recreational experiences

Bogs are of interest to outdoor recreationists, but little information exists concerning how recreation resource managers might manage these areas to enhance visitor benefits. This study evaluates bog visitor characteristics and experiences, visual preferences, and reasons for visiting. Implications for recreational resource management of bogs include the location and design of boardwalk trails and management of understory vegetation to meet the visual preferences and motives of bog visitors.     

环境雌激素EE2早期慢暴露对雄性大鼠成年后神经发育与空间学习行为的影响

环境雌激素17α-乙炔雌二醇(17alpha-ethynylestradiol, EE2)是一种常见的环境内分泌干扰物,主要经消化道被人和动物摄入,但其对中枢神经系统的影响尚不清楚。为探讨EE2早期慢暴露对Sprague-Dawley (SD)大鼠神经发育和成年后认知行为的影响及其机制,本研究选择5日龄雄性SD大鼠,随机分为3组：空白对照组(Control组)、EE2低剂量组(0.1 μg·kg^-1)、EE2高剂量组(10 μg·kg^-1),每组8只,EE2持续暴露16周。观察大鼠体质量、脑质量变化。采用Morris水迷宫、旷场实验观察大鼠行为学表现。Nissl染色和免疫组织化学染色法观察各组大鼠海马CA1区(CA1)、海马CA3区(CA3)、齿状回(DG)的细胞形态和脑源性神经营养因子(BDNF)的表达,Western Blot检测海马、大脑皮层的IL-1β、IL-10蛋白水平,并测定皮层和海马丙二醛(MDA)含量。结果显示,EE2暴露组大鼠体质量增长速度较对照组减缓,脑质量减轻。行为学发现,EE2组逃逸潜伏期延长,目标象限停留时间、跨台次数减少,中央区运动距离和中央区停留时间减少,并呈剂量依赖性变化。EE2暴露组海马各区神经元排列紊乱、形态不规则,DG区神经元前体细胞数量减少。进一步发现,EE2暴露组大鼠大脑皮层、海马组织的MDA含量均升高,IL-1β表达量增加,IL-10表达量下降。低剂量组海马DG区BDNF表达减少,高剂量组CA1、CA3、DG区BDNF表达均减少。以上结果表明,生命早期0.1 μg·kg^-1 EE2慢暴露可引起雄性大鼠成年后空间学习记忆行为障碍,与海马结构紊乱、BDNF水平降低和脑组织炎症反应有关。     

7个标准中危险源的定义、内容和分类研究

为更有效地识别危险源和管理职业安全风险,有必要明确危险源的定义和内容。用对比分析的方法,梳理7个标准中危险源的定义及识别危险源时需要考虑的因素。借助分析结果,研究危险源的内容、分类及其与隐患的关系。结果表明:危险源的内容非常宽泛,有可能造成事故的因素或原因的能量、物质、人、人的行为、人所在组织、系统、空间等是危险源;危险源的分类严格依赖于分类所依据的事故致因模型,危险源和隐患的含义相同。     

铋酸钠可见光催化降解孔雀石绿染料

以孔雀石绿(MG)模拟废水为研究对象考察铋酸钠的可见光催化活性,结果表明,17 min内浓度为20 mg·L-1的MG溶液在铋酸钠的作用下脱色率达97%,远比相同条件下TiO2和Bi2WO6的脱色效果好(分别为28%和44%).铋酸钠可以重复使用至少6次而没有明显活性下降,表征结果显示重复反应前后铋酸钠结构稳定.MG降解过程中UV/VIS吸收强度下降并最大吸收峰蓝移11 nm;GC/MS检出8种小分子降解产物;LC/MS/MS检出4类脱甲基产物,说明MG分子通过破坏生色团与脱甲基的方式降解.讨论了铋酸钠初始投加量与MG初始浓度对降解反应速率的影响.实验结果表明,催化剂使用量小于3 g·L-1时,降解反应速率随催化剂投加量增大,染料初始浓度减小而增加.     

E-bikers’ braking behavior: Results from a naturalistic cycling study

Abstract

Objective: The number of e-bike users has increased significantly over the past few years and with it the associated safety concerns. Because e-bikes are faster than conventional bicycles and more prone to be in conflict with road users, e-bikers may need to perform avoidance maneuvers more frequently. Braking is the most common avoidance maneuver but is also a complex and critical task in emergency situations, because cyclists must reduce speed quickly without losing balance. The aim of this study is to understand the braking strategies of e-bikers in real-world traffic environments and to assess their road safety implications. This article investigates (1) how cyclists on e-bikes use front and rear brakes during routine cycling and (2) whether this behavior changes during unexpected conflicts with other road users.

Methods: Naturalistic data were collected from 6 regular bicycle riders who each rode e-bikes during a period of 2 weeks, for a total of 32.5?h of data. Braking events were identified and characterized through a combined analysis of brake pressure at each wheel, velocity, and longitudinal acceleration. Furthermore, the braking patterns obtained during unexpected events were compared with braking patterns during routine cycling.

Results: In the majority of braking events during routine cycling, cyclists used only one brake at a time, favoring one of the 2 brakes according to a personal pre-established pattern. However, the favored brake varied among cyclists: 66% favored the rear brake and 16% the front brake. Only 16% of the cyclists showed no clear preference, variously using rear brake, front brake, or combined braking (both brakes at the same time), suggesting that the selection of which brake to use depended on the characteristics of the specific scenario experienced by the cyclist rather than on a personal preference. In unexpected conflicts, generally requiring a larger deceleration, combined braking became more prevalent for most of the cyclists; still, when combined braking was not applied, cyclists continued to use the favored brake of routine cycling. Kinematic analysis revealed that, when larger decelerations were required, cyclists more frequently used combined braking instead of single braking.

Conclusions: The results provide new insights into the behavior of cyclists on e-bikes and may provide support in the development of safety measures including guidelines and best practices for optimal brake use. The results may also inform the design of braking systems intended to reduce the complexity of the braking operation.     

燃料特性对铁矿石烧结及烟气排放的影响

采用烧结杯试验,从固体燃烧角度出发,探究燃料结构和粒度对燃烧前锋温度及烧结气氛变化的影响。结果表明:随着燃料中煤粉比例逐渐提高(0~100%),烧结速度提高至4.32 mm/min,利用系数提高至0.13 t/(m²·h);转鼓强度先上升后下降,当煤粉比例为25%时,转鼓指数达到最高(58.4%);烟气中NO_x浓度与CO成分分别提高28.34 mg/m³和0.72%,CO能促进NO的还原反应,抑制NO_x生成。全煤条件下,随着煤粉粒径<1 mm的质量分数由50%降低到10%,烟气中NO_x降低了51.33 mg/m³,提高燃料粒度可降低烟气NO_x排放浓度;而延长烧结时间,NO_x总排放量上升。研究结果可为烧结燃料选择及烟气减排提供参考。     

间歇-阶段性酸雨入侵对填埋稳定化飞灰中重金属浸出行为影响

以间歇-分阶段进水方式进行了模拟酸雨柱式动态淋溶实验.结果表明,间歇-阶段性酸雨入侵会影响填埋飞灰中Pb、Zn、Cu、Cr和Ni的浸出行为;尤其间歇停滞期后的初期酸雨入侵会增加多数重金属的再浸出水平,且该部分重金属的释放主要源于前阶段酸雨侵蚀过程中所形成的非稳定性(弱酸态)重金属.各酸雨侵蚀阶段,部分重金属(如Pb-Zn)的浸出行为具有相关性,这与各重金属在飞灰基质内的赋存形态、矿物相稳定性及酸性侵蚀程度等有关.各阶段酸雨入侵会相继溶出飞灰中的可溶性(NaCl、KCl等)、难溶性氯盐(CaClOH)以及微溶性钙盐(CaSO₄),并增加CaCO₃和Ca-Al-Si-O等矿物的峰强.各阶段酸雨入侵会使初始飞灰表面的团簇状结构逐渐被酸性(H⁺)侵蚀作用破坏,并暴露出大量棒状或条形状CaCO₃晶体,且随着酸雨入侵次数的增加,CaCO₃也将逐渐被侵蚀破坏.本研究为非连续酸性降雨条件下填埋稳定化飞灰的重金属浸出行为评价及风险管控提供了科学依据.     

区域农村土地市场发育的农户行为响应与农业土地利用变化——以江苏省苏州市、南京市、扬州市村庄及农户调查为例

在江苏省苏州市、南京市、扬州市各自选择了2个村的基础上,运用对240个农户的抽样调查资料,建立了区域农业土地利用变化分析的数量经济模型,较为深入地分析了农村土地流转市场引导下的农户行为对于农业土地利用变化的影响。研究结果表明,在农户决策行为起主导作用的前提下,农业土地利用正在逐步由传统的大田作物向效益更高的经济作物和水产养殖等地类转化;农户家庭非农就业水平的提高有效地推进了这一转化;同时,农户受教育水平的高低以及政府行为都在一定程度上影响着农业土地利用变化。最后从区域非农产业和城镇化发展、深化农村土地产权的物权化改革、农村社会保障制度的完善、建立农村土地流转中介机制、进一步规范政府行为及积极推进农村户籍制度改革等方面提出了一些政策性建议。