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961.
In conjunction with a nationwide motorcycle safety program, the provision of exclusive motorcycle lanes has been implemented to overcome link-motorcycle accidents along trunk roads in Malaysia. However, not much work has been done to address accidents at junctions involving motorcycles. This article presents the development of predictive model for motorcycle accidents at three-legged major-minor priority junctions of urban roads in Malaysia. The generalized linear modeling technique was used to develop the model. The final model reveals that motorcycle accidents are proportional to the power of traffic flow. An increase in nonmotorcycle and motorcycle flows entering the junctions is associated with an increase in motorcycle accidents. Nonmotorcycle flow on major roads had the highest effect on the probability of motorcycle accidents. Approach speed, lane width, number of lanes, shoulder width, and land use were found to be significant in explaining motorcycle accidents at the three-legged major-minor priority junctions. These findings should enable traffic engineers to specifically design appropriate junction treatment criteria for nonexclusive motorcycle lane facilities. 相似文献
962.
超累积植物富集重金属的分子生化机理 总被引:4,自引:1,他引:4
植物提取修复技术有赖于植物特别是其地上部对重金属的富集,本文主要从耐性、吸收、输运三方面探讨了超累积植物富集重金属的分子生化机理。 相似文献
963.
本文根据组合模式原理提出了一种用小震调制比(rm)异常区出现高频次的空间异常图,进行强地震中短期预报的方法,简称rs法。该方法在预报强震地点和时间上可望取得较好效果。本文在介绍该方法的基础上,应用该法对3次7级以上大震进行了回顾性检验。 相似文献
964.
试验设计了一种新型的蒸氨反应器,创新之处在于采用雾化喷头代替了传统的填料.废水经过加压雾化后与上升的气流逆向接触,通过增加接触面积达到提高去除率的目的.通过试验验证了使用这种新型的蒸氨反应器处理含高浓度氨氮的废水,在温度80 ℃,pH值11,鼓风量为1.63 m3/min,蒸氨时间为30 min的条件下,能达到高于90%的去除率. 相似文献
965.
本文对常温(25℃±3℃)条件下低密度载体厌氧流化床(AFB)反应器处理高浓度有机废水进行了研究。实验结果表明:采用好氧预挂膜快速排泥法可加快反应器的启动,低密度载体可有效降低反应器运行能耗,有机物去除效果良好。 相似文献
966.
阐述了直线电机轨道交通的技术特点,并就其安全评价体系做了介绍,应用ADAMS/Rail软件分别建立了轮对、构架、悬挂系统、止挡、自导向径向转向架、直线电机以及车体的模型,并考虑轮轨关系组合为直线电机轨道交通的车辆-轨道耦合动力学整体模型,进行了大量的计算仿真。笔者主要以脱轨系数为例进行了动力响应分析,给出考虑了径向转向架和直线电机后的安全评判指标,比较了与径向转向架和未安装直线电机的区别,验证了模型的正确性和有效性。为后续研究直线电机轨道交通车辆-轨道耦合动力学模型提供了理论基础,从而可以进一步从安全性角度研究线路设计参数。为我国今后直线电机轨道交通建设就线路参数对车辆运行安全性的影响研究方面起到理论指导作用。 相似文献
967.
968.
Dynamics of dissolved organic carbon in the mires in the Sanjiang Plain,
Northeast China 总被引:1,自引:0,他引:1
Mires in boreal area had proved to be an important dissolved organic carbon (DOC) reserve for the sensitivity to climate change
and human interfering. The study was focused on the temporal and spatial dynamics and controlling factors of DOC in a seasonallywaterlogged
mire (SLM) and perennially-waterlogged mire (PLM) in the Sanjiang Plain, Northest China. In the two mires, DOC
concentrations in both surface water and upper soil strata experienced pronounced seasonal variation. DOC concentrations in the
surface waters were the greatest and averagely was 47.82 in SLM and 34.84 mg/L and PLM, whereas that in soil water at 0.3-m depth
had little di erence (20.25 mg/L in SLM and 26.51 mg/L in PLM). Results revealed that DOC concentrations declined 5–8 times
vertically from the surface down to groundwater. DOC in the groundwater only was in a very small part with the average concentration
of 5.18 mg/L. In relation to the surface water, DOC concentrations varied positively with temperature just before 8 August, and only
in early spring and later autumn DOC concentrations exhibited identifiable spatial trends along with standing water depths in PLM. It
was supposed that the influences from standing water depth took e ect only in conditions of low temperature, and temperature should
be the most powerful factor controlling DOC dynamics in the mires. Redox potential (Red) showed negative relationship with DOC
values while total nitrogen (TN) and the majority of free ions in the soil solution exhibited no relationship. High soil TOC/TN ratio and
low redox potentials also led to DOC accumulation in the mires in the Sanjiang Plain. 相似文献
969.
北京市CFCs和CCl_4的浓度水平与变化趋势 总被引:1,自引:0,他引:1
采用预浓缩-GC/MS方法对2009年4—8月北京市大气中CFC-11,CFC-12,CFC-113,CFC-114和CCl45种主要消耗臭氧层物质进行了监测.结果表明:观测期内北京市大气中φ(CFC-11),φ(CFC-12)和φ(CCl4)的平均值高于全球本底站观测值,而φ(CFC-113)和φ(CFC-114)与全球本底水平相当,其原因是这5种物质在我国的排放水平差异所致,其中CFC-11,CFC-12和CCl4仍存在一定量的排放.不同季节的日变化分析表明,4月5种物质的体积分数日变化趋势平缓,而8月观测日内基本呈现出夜间物质的体积分数高于白天的特征.8月φ(CFC-11),φ(CFC-12)和φ(CCl4)的平均值比4月高,这可能是由于8月的温度较高,致使这3种物质现有排放源的排放量增加. 相似文献
970.
Phosphorous (P) fraction characteristics in sediment resuspension were investigated under adequately hydrodynamic conditions.
Four forms of P in overlying water, including dissolved inorganic P, dissolved total P, total P, and particulate P, and six fractions of
P in suspended particulate matter (SPM), including loosely sorbed P (NH4Cl-P), redox-sensitive P (BD-P), aluminum-bound P (Al-
P), organic P (NaOH-nrP), calcium-bound P (Ca-P) and residual P (Res-P), were quantified, respectively. Di erent hydrodynamic
conditions resulted in di erent P form changes. Four states could be ascribed: (1) P desorption by sediment and SPM, and P adsorption
by overlying water; (2) P desorption by SPM, and P adsorption by overlying water; (3) P adsorption by SPM, and P desorption by
overlying water; and (4) P equilibrium between SPM and overlying water. The contents of P in overlying water acquired peak values
in the middle position of the vertical P distribution due to the combined actions of SPM and sediment. P fractions in SPM were in the
following order: BD-P > NaOH-nrp > Ca-P > Al-P > Res-P > NH4Cl-P. BD-P in SPM frequently exchanged with P forms in overlying
water. Resuspension was favorable to forming Ca-P in SPM. 相似文献