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Quantification of Structurally Alert Mutagenic Impurities in Meropenem Trihydrate Drug Substance by Liquid Chromatography with High Resolution Mass Spectrometer (LC-HRMS)
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作者 Anwar Sulaiman K. Ramakrishna Reddy +1 位作者 Vundavilli Jagadeesh Kumar Hemant Kumar Sharma 《American Journal of Analytical Chemistry》 CAS 2024年第3期119-133,共15页
Potential mutagenic impurities in Active Pharmaceutical Ingredient, Meropenem Trihydrate were assessed and a novel analytical method for their quantification was developed and validated. This Liquid Chromatographic me... Potential mutagenic impurities in Active Pharmaceutical Ingredient, Meropenem Trihydrate were assessed and a novel analytical method for their quantification was developed and validated. This Liquid Chromatographic method using High Resolution Mass Spectrometer (LC-HRMS) technique is proved to be suitable for simultaneous quantification of all ten identified impurities with required specificity, sensitivity, resolution, precision, accuracy, and other method characteristics as per ICH Guidelines. The acceptable limit of less than 2.9 μg/g was considered for evaluations, based on drug substance dosage and duration of treatment. The method stands most sensitive with a Limit of Detection of 0.35 μg/g, considering the challenge full acceptance criteria as per current regulatory standards. 展开更多
关键词 Mutagenic Impurities LC-HRMS Meropenem Trihydrate Method Validation
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Sediment Quality Assessment of Kavvayi Wetland in South Coast India with Special Reference to Phosphate Fractionation and Heavy Metal Contamination 被引量:1
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作者 Moonampadiyan Shiji Prabhakar Kavya Puthenveedu Sadasivan Pillai Harikumar 《Journal of Environmental Protection》 2015年第11期1308-1321,共14页
Sediments play an important role in elemental cycling in the aquatic environment;it can be sensitive indicator for monitoring contaminants in aquatic environments. The heavy metal prominence, the amount and different ... Sediments play an important role in elemental cycling in the aquatic environment;it can be sensitive indicator for monitoring contaminants in aquatic environments. The heavy metal prominence, the amount and different forms of phosphorous present in the surface sediments of Kavvayi Wetland, which is in the south west coast of India was studied and reported in this paper. A total number of 10 surface sediment samples were taken from various regions of Kavvayi Lake and were subjected to heavy metal analysis and also phosphorous fractionation. Phosphorous forms in the sediment samples were determined by the modified sequential extraction procedure and among the inorganic phosphorous pool;Fe and Al bound phosphorous constituted the major portion while the Ca-bound phosphorous constituted the minor part only. Higher concentration of organic phosphorous was also detected in all the samples. The sediment samples were analyzed for heavy metals such as Fe, Mn, Cu, Pb, Cd, Ni, and Zn and the results showed comparatively higher concentration than the background values. The degree of contamination for each station was determined. Sediment pollution load index (PLI) values of the studied area ranged from 0.39 to 2.55 which indicated that the wetland sediments were polluted. Multivariate statistical techniques were applied to evaluate and characterize the analytical data. Spatial distribution maps of phosphorous fractions and heavy metals would help to identify the pollution sources and vulnerable sites. 展开更多
关键词 Kavvayi WETLAND Phosphorous FRACTIONS Degree of Contamination Pollution Load Index MULTIVARIATE Statistics
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Assessment of Water Quality Status of Guruvayur Municipality
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作者 P. S. Harikumar Anisha Aravind Sandra Vasudevan 《Journal of Environmental Protection》 2017年第2期159-170,共12页
Groundwater is an essential and vital component of our life support system. The deterioration in the groundwater quality due to geogenic and anthropogenic activities has drawn great attention as it is the major altern... Groundwater is an essential and vital component of our life support system. The deterioration in the groundwater quality due to geogenic and anthropogenic activities has drawn great attention as it is the major alternate source of domestic and drinking water supply. Groundwater and surface water samples collected from various locations in Guruvayur were analysed for selected physico-chemical and bacteriological parameters by adopting APHA standard methods. The results of the analysis indicated the chemical and bacteriological contamination due to the disposal of solid, organic and septic wastes in the surface water samples of Chakkamkandam, Palayur and Edappally which are the various locations in Gurauvayur. Also the groundwater samples of Guruvayur were contaminated. The study revealed that, the water samples examined were found to be above the permissible limits of Bureau of Indian Standards (BIS). The sewage inlets that open directly to the water body are the major source of pollutants. The monitoring of various water bodies indicates the importance of taking appropriate measures to treat the water resources before either discharged to wetlands or consumed by human beings. It is also recommended to continue the monitoring periodically to assess the pollution status of the area. 展开更多
关键词 WATER QUALITY Chakkamkandam Palayur Edappully Guruvayur
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全球沙尘气溶胶源汇分布及其变化特征的模拟分析 被引量:19
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作者 刘建慧 赵天良 +2 位作者 韩永翔 Gong S L 熊洁 《中国环境科学》 EI CAS CSCD 北大核心 2013年第10期1741-1750,共10页
根据全球沙尘气溶胶气候模式GEM-AQ/EC模拟的1995~2004年的沙尘起沙量和干湿沉降量,分析了沙尘气溶胶源汇的全球时空变化特征.全球沙尘起沙量集中在各个主要沙漠地区,北非对全球沙尘气溶胶贡献最大为66.6%.沙尘气溶胶沉降的高值区分布... 根据全球沙尘气溶胶气候模式GEM-AQ/EC模拟的1995~2004年的沙尘起沙量和干湿沉降量,分析了沙尘气溶胶源汇的全球时空变化特征.全球沙尘起沙量集中在各个主要沙漠地区,北非对全球沙尘气溶胶贡献最大为66.6%.沙尘气溶胶沉降的高值区分布在沙漠源区及其紧临的下风地区.最大净沙尘气溶胶接收主要分布在沙漠周围地区并形成净接收量大于10t/(km2·a)的位于0°N^60°N之间的北非、欧亚大陆、西太平洋、北印度洋、北美和大西洋的带状分布.在北非、阿拉伯半岛、中亚、东亚和澳大利亚5个主要沙漠地区中,起沙量和沉降量都存在明显的季节变化,除中亚其他4个区域干湿沉降量和起沙的季节变化基本一致;东亚地区沙尘气溶胶起沙量和总沉降量的季节变化最为明显,而北非沙漠起沙量和总沉降量的季节变化最小,其他3个区域的季节变化幅度基本相同.中亚起沙峰值和阿拉伯半岛起沙次峰值出现在夏季,其他区域的峰值均出现在春季.10年间全球陆地年平均起沙量为(1500±94)Mt,保持略微上升趋势.以北非沙漠起沙量年际变化率最低(6.3%),而以东亚(28.3%)和澳大利亚(45.0%)起沙量年际变化最为明显;全球陆地的沙尘气溶胶沉降量以约9.9Mt/a的速率递减,全球海洋的沙尘气溶胶沉降递增. 展开更多
关键词 沙尘气溶胶 起沙量 干湿沉降量 模拟分析
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中国气溶胶分布的地理学和气候学特征 被引量:42
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作者 郑小波 罗宇翔 +2 位作者 赵天良 陈娟 康为民 《地理科学》 CSCD 北大核心 2012年第3期265-272,共8页
中国人口地理分界线——胡焕庸线根据人口、地理,气候和经济等特点把中国(不包括港、澳、台地区)分为东、西两部分。用2000~2010年MODIS大气气溶胶光学厚度(AOD)资料,分析气溶胶分布的地理学和气候学特征后发现,胡焕庸线还可被视为... 中国人口地理分界线——胡焕庸线根据人口、地理,气候和经济等特点把中国(不包括港、澳、台地区)分为东、西两部分。用2000~2010年MODIS大气气溶胶光学厚度(AOD)资料,分析气溶胶分布的地理学和气候学特征后发现,胡焕庸线还可被视为中国气溶胶地理学的分界线,在其两侧气溶胶的性质和浓度都有明显差别。在人口稠密和海拔较低的东部,由人类活动产生的气溶胶为主,年平均AOD约为0.45;在西部,自然过程释放的气溶胶主导的AOD约为0.25。近10 a来东部AOD的年际间变化呈现增加趋势,西部AOD出现微弱减少的趋势。东部人为气溶胶年际间变化受亚洲季风影响。西部自然气溶胶年际间变化主要受沙漠地区沙尘气溶胶排放源的影响,沙尘天气过程主要控制其气溶胶的释放。 展开更多
关键词 大气气溶胶光学厚度 MODIS 胡焕庸线 地理 气候
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中国各省区近10年遥感气溶胶光学厚度和变化 被引量:31
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作者 郑小波 周成霞 +2 位作者 罗宇翔 陈娟 Tianliang ZHAO 《生态环境学报》 CSCD 北大核心 2011年第4期595-599,共5页
用2000—2009年MODIS大气气溶胶光学厚度(AOD))资料,分析中国29个省(区、市)AOD多年平均值和年际间变化趋势。中国10年平均AOD高值区主要集中在华北、华中、华南和新疆,低值区主要在青藏高原、西北(除新疆外)、东北和西南地区。中国有1... 用2000—2009年MODIS大气气溶胶光学厚度(AOD))资料,分析中国29个省(区、市)AOD多年平均值和年际间变化趋势。中国10年平均AOD高值区主要集中在华北、华中、华南和新疆,低值区主要在青藏高原、西北(除新疆外)、东北和西南地区。中国有13个省(市、区)多年平均AOD超过0.4。最高为0.735(江苏)。只有西藏和黑龙江的AOD小于0.2,其余15个省区市的AOD在0.2至0.3之间。除新疆外,中国的AOD高值区全部集中在工业发达和人口密集的地区。中国年际间AOD的变化为上升趋势。近10 a来AOD增长的倾向率为0.019/10a,即增加了4.3%。其中在2000—2007年间的上升最为明显,在2007年达到近10 a来的最高峰(0.437 6),2008年以后中国的AOD开始出现下降趋势,2009年达到近10 a来最低值(0.372 0)。有17个省区市AOD气候学变化倾向率为正值,变化的范围为0.006~0.099/10a。有12个为负值,变化的范围为-0.037^-0.003/10a。出现AOD增加和减少趋势的区域两极分化,即高排放地区继续增加,低排放地区持续减少。 展开更多
关键词 中国 各省区 MODIS 气溶胶光学厚度(AOD) 变化趋势
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1995~2004年东亚沙尘气溶胶的模拟源汇分布及垂直结构 被引量:15
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作者 熊洁 赵天良 +1 位作者 韩永翔 Gong S L 《中国环境科学》 EI CAS CSCD 北大核心 2013年第6期961-968,共8页
利用全球气溶胶模式GEM-AQ/EC的1995-2004年10年沙尘气溶胶模拟,探讨了东亚地区沙尘气溶胶源汇分布和垂直结构特征.结果表明,东亚大陆沙尘气溶胶源区主要集中在东亚的沙漠地区,有两大沙尘主要源区:覆盖蒙古国南部及中国内蒙中西部的沙... 利用全球气溶胶模式GEM-AQ/EC的1995-2004年10年沙尘气溶胶模拟,探讨了东亚地区沙尘气溶胶源汇分布和垂直结构特征.结果表明,东亚大陆沙尘气溶胶源区主要集中在东亚的沙漠地区,有两大沙尘主要源区:覆盖蒙古国南部及中国内蒙中西部的沙漠地区和南疆的塔克拉玛干沙漠.东亚沙尘排放量春季最大,占全年排放总量的66.81%,四月份达15.29Mt,夏季下降,秋季小幅度回升,冬季最小;东亚沙尘排放量呈现明显的年际变化及增强的趋势.东亚沙尘沉降高值区与源区一致,源区及附近以干沉降为主,远距离传输到中国东北、长江以南及西太平洋包括日本、朝鲜半岛,湿沉降占主导地位;沙尘沉降具有季节变化,其趋势与东亚沙尘排放量的季节变化大致相同,且模拟的10年沉降量呈上升趋势.东亚沙漠地区排放的沙尘主导了东亚沙尘气溶胶的变化,最大的净沙尘汇区集中在紧邻净沙尘源区的黄土高原及华北平原西部.东亚地区春夏秋3个季节均是沙尘的净源区,而冬季强西风急流输入东亚以外的沙尘使东亚整体上为沙尘净接收区.东亚大陆大部分地区,沙尘垂直分布主要集中在对流层低层3km高度以下,在西太平洋地区包括日本、朝鲜半岛沙尘高值中心位于在对流层中层5km高度上下,在沙漠以北地区沙尘垂直廓线的高值出现在对流层中上层6-8km高度. 展开更多
关键词 东亚沙漠 沙尘气溶胶 气溶胶模式 垂直结构
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青藏高原黑碳气溶胶传输及沉降的季节特征模拟分析 被引量:9
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作者 韩永翔 孙海波 +2 位作者 刘建慧 赵天良 S.L.Gong 《干旱气象》 2014年第3期319-325,共7页
根据全球气溶胶气候模式GEM-AQ/EC的1995~2004年模拟,分析了青藏高原大气黑碳气溶胶的来源、传输及沉降季节特征。研究表明:青藏高原黑碳气溶胶主要来自自由对流层和大气边界层的输送。相对于自由对流层的黑碳输送,紧邻青藏高原的南亚... 根据全球气溶胶气候模式GEM-AQ/EC的1995~2004年模拟,分析了青藏高原大气黑碳气溶胶的来源、传输及沉降季节特征。研究表明:青藏高原黑碳气溶胶主要来自自由对流层和大气边界层的输送。相对于自由对流层的黑碳输送,紧邻青藏高原的南亚、东亚以及东南亚大气边界层的输送更有效,它形成了青藏高原由北向南、自西往东黑碳气溶胶浓度和沉降明显递增的基本分布形态。横跨欧亚大陆自由对流层的黑碳气溶胶由西向东向青藏高原的输送全年不变,夏季输送路径最北但强度最弱,冬季路径最南而强度最强。大气边界层黑碳气溶胶的输送受控于亚洲季风环流变化,来自南亚的黑碳气溶胶在春季越过孟加拉湾传输进入高原东南部,夏季则可翻越喜马拉雅山抵达青藏高原南部腹地;同时我国中部排放的黑碳气溶胶也在东亚夏季风向北扩展中驱动它从东向西往青藏高原东北部传输。从秋季到冬季,随着夏季风撤退,南亚黑碳源区向青藏高原传输衰退,东亚冬季风的反气旋性环流的南侧及西南侧的偏东风携带秋季我国东南部源区和冬季东南亚源区黑碳气溶胶向青藏高原东南部传输。受青藏高原明显的暖湿季和干冷季气候影响,干湿沉降分别主导了青藏高原冬季和夏季黑碳沉降,夏季青藏高原黑碳气溶胶沉降总量大多超过8~10 kg·km-2,在高原东北部的最高值超过40 kg·km-2。冬季青藏高原黑碳气溶胶沉降量最低,大部地区黑碳沉降低于5 kg·km-2。青藏高原黑碳沉降的冬夏季节相差约为2~8倍。 展开更多
关键词 黑碳气溶胶 青藏高原 气溶胶传输 干湿沉降 GEM-AQ EC
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云贵高原近45年来日照及能见度变化及其成因初步分析 被引量:34
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作者 郑小波 罗宇翔 +3 位作者 段长春 ZHAO Tian-liang 陈娟 康为民 《高原气象》 CSCD 北大核心 2010年第4期992-998,共7页
利用云贵高原1961—2005年184个气象站的日照时数、总云量和能见度的观测资料,分析了高原的日照、云量、中低空水汽和能见度变化趋势。结果表明,云贵高原的总云量、中低层大气水汽含量都没有发生明显变化的条件下,有85%的台站出现日照... 利用云贵高原1961—2005年184个气象站的日照时数、总云量和能见度的观测资料,分析了高原的日照、云量、中低空水汽和能见度变化趋势。结果表明,云贵高原的总云量、中低层大气水汽含量都没有发生明显变化的条件下,有85%的台站出现日照时数减少,减少量在12.2h.(10a)-1到173.7h.(10a)-1之间。Mann-Kendall检验的结果表明:日照时数减少的台站中有63.7%的站出现突变现象,突变发生的年代从20世纪70年代开始,主要发生在80~90年代,21世纪以来这种减少现象不明显。同时年平均能见度从60年代的34km下降到目前的27km。云量、高空水汽和能见度条件分析表明,高原对流层气溶胶和污染物浓度的增加是导致日照减少的主要原因。 展开更多
关键词 云贵高原 气候变化 日照 能见度 云量
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云贵高原1961-2006年大气能见度和消光因素变化趋势及原因 被引量:25
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作者 郑小波 王学锋 +2 位作者 罗宇翔 Tianliang Zhao 陈娟 《生态环境学报》 CSCD 北大核心 2010年第2期314-319,共6页
根据云贵高原203个气象台站1961—2006年大气能见度、降水、相对湿度、风速和天气现象等观测资料,采用倾向率方法对能见度和大气消光系数的变化趋势进行了分析。还应用Mann-Kendall方法对>19km能见度、霾日数和消光系数的多年变化进... 根据云贵高原203个气象台站1961—2006年大气能见度、降水、相对湿度、风速和天气现象等观测资料,采用倾向率方法对能见度和大气消光系数的变化趋势进行了分析。还应用Mann-Kendall方法对>19km能见度、霾日数和消光系数的多年变化进行了气候突变检验。结果表明,有84.2%台站出现了能见度减少趋势。减少最多为-11km·10a-1,最少为-1km·10a-1。减少的平均气候倾向率在1961—1979年为0.96km·10a-1,1980—2006年为1.6km·10a-1,高原平均能见度从60年代的约34km下降到目前的约27km。另一方面,有15.8%台站能见度有增加趋势,且多集中在人类活动较为稀少的高海拔山区。有71%的台站>19km能见度频率出现减少的趋势,平均倾向率为-2%·10a-1,主要出现在高原东部和中部人口和工业稠密区。该地区同时也出现霾日增加的现象。Mann-Kendall检测结果表明,>19km能见度频率减少和霾日数增加现象出现突变的时间相同。年平均消光系数发生突变的时间稍推后。认为能见度下降、消光因素增加的原因与人为排放污染物浓度增加有密切关系。 展开更多
关键词 能见度 消光系数 霾日 气溶胶 云贵高原 大气污染
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Investigation on emission factors of particulate matter and gaseous pollutants from crop residue burning 被引量:61
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作者 CAO Guoliang ZHANG Xiaoye +1 位作者 GONG Sunling ZHENG Fangcheng 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2008年第1期50-55,共6页
微粒物质(下午)的排放因素,元素碳( EC ),器官的碳( OC ), SO2 , NOx ,公司, CO2 ,和十个离子(Na+,NH4+,K+,Mg2+,Ca2+, F ?, Cl ?, NO2 ?, NO3 ?, SO42 ?)从在农村中国的通常生产的罪残茬的四种类型的国内烧被估计:稻... 微粒物质(下午)的排放因素,元素碳( EC ),器官的碳( OC ), SO2 , NOx ,公司, CO2 ,和十个离子(Na+,NH4+,K+,Mg2+,Ca2+, F ?, Cl ?, NO2 ?, NO3 ?, SO42 ?)从在农村中国的通常生产的罪残茬的四种类型的国内烧被估计:稻秸,麦秸,玉米 stover,和棉花越过中国搜索区域,它从代表是镇定的。一个燃烧塔被设计模仿农民在农村中国在下面烧了他们的罪残茬的煮的条件,到措施排放因素。,结果证明那麦秸在四罪残茬之中有最高的排放因素彻底的下午(8.75 g/kg ) 玉米 stover 和麦秸分别地为 EC (0.95 g/kg ) 和 OC (3.46 g/kg ) 有最高的排放因素。玉米 stover 也作为有最高的排放因素介绍没有, NOx,和 CO2,麦秸,稻秸,和棉花梗分别地有 NO2, SO2,和公司的最高的排放因素。水溶性的离子, K+ 和 Cl ? ,从所有庄稼有最高的排放因素。麦秸有阳离子种类和 F 的一个相对更高的排放因素 ? , Cl ? , NO2 吗?比另外的残余。 展开更多
关键词 中国 农村 农作物燃烧 气体污染物 发射因数
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Chemical Composition of PM_(2.5) at an Urban Site of Chengdu in Southwestern China 被引量:22
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作者 陶俊 成天涛 +5 位作者 张仁健 曹军骥 朱李华 王启元 罗磊 张雷鸣 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2013年第4期1070-1084,共15页
PM2.5 aerosols were sampled in urban Chengdu from April 2009 to January 2010, and their chemical compositions were characterized in detail for elements, water soluble inorganic ions, and carbonaceous matter. The annua... PM2.5 aerosols were sampled in urban Chengdu from April 2009 to January 2010, and their chemical compositions were characterized in detail for elements, water soluble inorganic ions, and carbonaceous matter. The annual average of PM2.5 was 165 μg m-3 , which is generally higher than measurements in other Chinese cities, suggesting serious particulate pollution issues in the city. Water soluble ions contributed 43.5% to the annual total PM2.5 mass, carbonaceous aerosols including elemental carbon and organic carbon contributed 32.0%, and trace elements contributed 13.8%. Distinct daily and seasonal variations were observed in the mass concentrations of PM2.5 and its components, reflecting the seasonal variations of different anthropogenic and natural sources. Weakly acidic to neutral particles were found for PM2.5 . Major sources of PM2.5 identified from source apportionment analysis included coal combustion, traffic exhaust, biomass burning, soil dust, and construction dust emissions. The low nitrate: sulfate ratio suggested that stationary emissions were more important than vehicle emissions. The reconstructed masses of ammonium sulfate, ammonium nitrate, particulate carbonaceous matter, and fine soil accounted for 79% of the total measured PM2.5 mass; they also accounted for 92% of the total measured particle scattering. 展开更多
关键词 中国西南地区 化学成分 PM2 5 城市 成都 水溶性离子 站点 质量浓度
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Geospatial and Statistical Assessment of Groundwater Contamination Due to Landfill Leachate—A Case Study 被引量:4
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作者 Jaseela Chonattu Kavya Prabhakar Harikumar Puthenveedu Sadasivan Pillai 《Journal of Water Resource and Protection》 2016年第2期121-134,共14页
This study was conducted to measure the impact of a municipal solid waste landfill on groundwater quality around Njelianparamba, a solid waste dumping site in Kozhikode district, Kerala state, India. One of the major ... This study was conducted to measure the impact of a municipal solid waste landfill on groundwater quality around Njelianparamba, a solid waste dumping site in Kozhikode district, Kerala state, India. One of the major problems associated with dumping of municipal solid waste landfill is the release of leachate and its impact on surrounding groundwater. In this study, physico-chemical and bacteriological parameters of groundwater samples collected from the region surrounding the leachate area during the pre- and post-monsoon seasons were analysed. The majority of the groundwater samples contained contaminants at a level beyond the permissible limit set by the Bureau of Indian Standards for drinking water quality. The Geographic Information System software of the Environmental Systems Research Institute, (USA) ArcMap 10.1 was used to prepare spatial distribution maps of different parameters and Leachate Pollution Index and Water Quality Index in the study area were applied to assess the overall quality of groundwater. Characterisation of leachate and groundwater samples revealed that, water in the domestic wells has been deteriorated in response to the percolation of leachate. Additionally spatial and correlation analysis revealed that contamination was present maximum within 300 m radius around the landfill site. 展开更多
关键词 Correlation Analysis Geographic Information System LEACHATE Leachate Pollution Index PERCOLATION Water Quality Index
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A new approach to quantifying vehicle induced turbulence for complex traffic scenarios 被引量:2
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作者 Yesul Kim Li Huang +1 位作者 Sunling Gong Charles Q.Jia 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第1期71-78,共8页
Traffic-related pollutants adversely affect air quality, especially in regions near major roadways. The vehicleinduced turbulence(VIT) is a significant factor that controls the initial dilution, dispersion, and ultima... Traffic-related pollutants adversely affect air quality, especially in regions near major roadways. The vehicleinduced turbulence(VIT) is a significant factor that controls the initial dilution, dispersion, and ultimately the chemical and physical fate of pollutants by altering the conditions in the microenvironment. This study used a computational fluid dynamics(CFD) software FLUENT to model the vehicle-induced turbulence(VIT) generated on roadways, with a focus on impact of vehicle-vehicle interactions, traffic density and vehicle composition on turbulent kinetic energy(TKE). We show, for the first time, that the overall TKE from multiple vehicles traveling in series can be estimated by superimposing the TKE of each vehicle, without considering the distance between them while the distance is greater than one vehicle length. This finding is particularly significant since it enables a new approach to VIT simulations where the overall TKE is calculated as a function of number of vehicles. We found that the interactions between vehicles traveling next to each other in adjacent lanes are insignificant,regardless the directions of the traffic flow. Consequently, simulations of different traffic scenarios can be substantially simplified by treating two-way traffic as one-way traffic, with less than 5% difference in the overall volume-averaged TKE. We also developed equations that allow the estimation of the overall volume-averaged TKE as a function of the number and the type of vehicles. 展开更多
关键词 车辆行驶 湍流动能 交通流 计算流体动力学 诱导 场景 量化 时间估计
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Observations of Aerosol Optical Properties in the Beijing Urban Area in Summer 被引量:6
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作者 JING Jun-Shan ZHANG Ren-Jian +1 位作者 TAO Jun ZHANG Lei-Ming 《Atmospheric and Oceanic Science Letters》 2011年第6期338-343,共6页
To investigate aerosol optical properties in the Beijing metropolitan area,aerosol absorption coefficient(Ab) ,scattering coefficient(Sc) ,and fine particulate matter(PM2.5) were measured in the Beijing urban area fro... To investigate aerosol optical properties in the Beijing metropolitan area,aerosol absorption coefficient(Ab) ,scattering coefficient(Sc) ,and fine particulate matter(PM2.5) were measured in the Beijing urban area from 20 May to 30 August 2009.The average Ab,Sc,single scattering albedo(SSA) ,and PM2.5 concentration were 58.0±39.5 M m-1,343.5±353.7 M m-1,0.80±0.10 and 63.6±50.0-g m-3,respectively,during the observation period.Ab,Sc,and SSA all showed single peak diurnal variations,with their maximum values being measured at 0500,1000,and 1300 local time,respectively.Ab and Sc had a strong positive correlation with PM2.5,and Ab,Sc,and PM2.5 all had positive correlations with relative humidity and negative correlations with wind speed. 展开更多
关键词 北京城区 光学特性 气溶胶 城市地区 观测 夏季 单散射反照率 大都市区
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Defluoridation of water using biosorbents 被引量:2
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作者 Puthenveedu Sadasivan Pillai Harikumar Chonattu Jaseela Tharayil Megha 《Natural Science》 2012年第4期245-251,共7页
Contamination of drinking water due to fluoride is a severe health hazard problem. Excess of fluoride (>1.5 mg/l) in drinking water is harmful to human health. Various treatment technologies for removing fluoride f... Contamination of drinking water due to fluoride is a severe health hazard problem. Excess of fluoride (>1.5 mg/l) in drinking water is harmful to human health. Various treatment technologies for removing fluoride from groundwater have been investigated. The present study showed that Vetiveria zizanioides, a herbal plant of Kerala—commonly known as Vetiver is an effective adsorbent for the removal of fluoride from aqueous solution. Phosphoric acid activated Vetiver root showed good adsorption capacity than the fresh powdered Vetiver root. Batch sorptive defluoridation was conducted under variable experimental conditions such as pH, agitation time, dose of adsorbent and particle size. Maximum defluoridation was achieved at pH 6;there is a greater possibility of columbic interaction between fluoride ion and adsorbent surface at this pH. The percentage of fluoride removal in- creases with adsorbent dose and time at a given initial solute concentration. The surface and sorption characteristics were analyzed using SEM techniques. Freundlich as well as Langmuir isotherm were plotted and kinetic constants were determined. 展开更多
关键词 DEFLUORIDATION FLUOROSIS BATCH ADSORPTION Vetiver PHYTOREMEDIATION
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Trends in sunshine duration and atmospheric visibility in the Yunnan-Guizhou Plateau,1961-2005 被引量:4
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作者 XiaoBo Zheng TianLiang Zhao +2 位作者 YuXiang Luo ChangChun Duan Juan Chen 《Research in Cold and Arid Regions》 2011年第2期179-184,共6页
Using the observed data from 184 stations over the Yunnan-Guizhou Plateau (YGP) from 1961 to 2005,the long-term trends in sunshine duration,cloud amount,dry visibility (Vd),dry extinction,and water vapor over the YGP ... Using the observed data from 184 stations over the Yunnan-Guizhou Plateau (YGP) from 1961 to 2005,the long-term trends in sunshine duration,cloud amount,dry visibility (Vd),dry extinction,and water vapor over the YGP are analyzed.The results show that 85% of the stations recorded shortening annual sunshine duration,with the decrease rates between -12.2 and -173.7 h/10yr.Results of Mann-Kendall tests indicate that,among the stations with decreasing sunshine duration,63.7% of them experienced an abrupt change that started in the 1970s and peaked in the 1980s.This decreasing trend has reversed in the early years of the 21st century.The cloud cover and water vapor content in the mid and lower levels over the YGP had no obvious changes during the study period.The annual averages of Vd declined from 34 km in the 1960s to 27 km at present.The annual mean dry extinction coefficient trended upward,from 0.176 to 0.190,on the YGP from 1980 to 2005.Analyses of cloud cover,water vapor,atmos-pheric visibility,and dry extinction coefficient revealed that emitted tropospheric aerosols (including air pollutants) resulting from increased energy consumption over the YGP could be a major factor influencing the reductions of sunshine duration and atmospheric visibility. 展开更多
关键词 大气能见度 云贵高原 日照时数 日照时间 消光系数 空气污染物 观测数据 上升趋势
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Modeling visitor use on high elevation mountain trails: An example from Longs Peak in Rocky Mountain National Park, USA 被引量:1
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作者 David PETTEBONE Ashley D'ANTONIO +1 位作者 Abigail SISNEROS-KIDD Christopher MONZ 《Journal of Mountain Science》 SCIE CSCD 2019年第12期2882-2893,共12页
Increasing use on mountain summits has both social and ecological implications.High numbers of visitors climbing mountain summits can be a safety issue,particularly in areas where terrain or elevation leads to queuein... Increasing use on mountain summits has both social and ecological implications.High numbers of visitors climbing mountain summits can be a safety issue,particularly in areas where terrain or elevation leads to queueing that may cause time delays.Estimating visitor use levels at site specific locations en route to summits is needed to understand the potential benefits and impacts of visitor use in these locations.However,it can be difficult to obtain reliable and robust data to estimate use and develop statistical relationships because of the remote and harsh climates on mountain summits,as well as the financial and personnel requirements involved to collect the data in remote locations.In 2015,data were collected on the higher stretches of the Keyhole Route on Longs Peak in Rocky Mountain National Park,USA(RMNP)to better understand use levels near the summit and to explore potential statistical relationships to trailhead use data that are relatively easy to collect.Strong statistical relationships from robust regression analyses were found between trailhead use counts and daily and hourly use totals on the"Homestretch"which is a final section of the Keyhole Route.Additionally,a strong statistical relationship was found between total daily use and maximum hourly use on the Homestretch.The results suggest that trailhead counts are an accurate and reliable means from which to estimate use levels on upper portions of the Keyhole route.Moreover,this research demonstrates the usefulness of an approach using proxy variables to estimate visitor use along remote peaks where data collection can be difficult.These types of data can elucidate various options and decisions for park management teams who are charged with deciding if and how to manage high use areas. 展开更多
关键词 Visitor use Mountain summits National parks Use estimation Recreation use Proxy variables
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Sanitation Mapping of Groundwater Contamination in a Rural Village of India 被引量:1
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作者 P. U. Megha P. Kavya +1 位作者 S. Murugan P. S. Harikumar 《Journal of Environmental Protection》 2015年第1期34-44,共11页
Availability of clean water and adequate sanitation facilities are of prime importance for limiting diarrheal diseases. We examined the spatial information on the groundwater quality and sanitation facilities of a vil... Availability of clean water and adequate sanitation facilities are of prime importance for limiting diarrheal diseases. We examined the spatial information on the groundwater quality and sanitation facilities of a village in southern India using Geographic Information System (GIS) tools. Place of residence, position of wells and latrines were mapped and well water samples were tested for microbial contamination (Total Coliform Counts (TCC), Fecal Coliform Counts (FCC) and Fecal Streptococcal Counts (FSC)). A well structured questionnaire was administered to 50 residents of the selected areas to elicit information on water collection, handling and storage. The location and distances of wells from latrines were determined using the Global Positioning System (GPS) device and a tape rule respectively. Data on 170 cases of various water-borne diseases were collected from primary health centers in the study area. Groundwater in the village was found to be microbiologically unfit for consumption. Analysis using direct observations supplemented by GIS maps revealed poor planning, design of the wells and improper siting of wells from latrines which were found to be the possible reasons of groundwater contamination. There was a significant difference in TCC between covered and uncovered wells (p < 0.01) but no significant differences were observed in the FCC, FSC and well covering. The mean distance (6.44 ± 2.37 m) of wells from the latrines in the study area was below the limit (15.24 m or 50 ft) set by United State Environmental Protection Agency (USEPA). TCC and FCC increased with a decrease in distance between the wells and latrines with a significance (p < 0.01). A moderate negative correlation (r = -0.593, r = -0.470) was ensued between the distance from latrine and coliform count. This study accentuates the need to set standards for the siting of wells from latrines and need for treatment. 展开更多
关键词 GEOGRAPHIC Information Systems SANITATION GROUNDWATER Latrines MICROBIAL COUNT
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Sub-Criticality Measurement with Source Term for Research Reactor in Inverse Kinetics Method 被引量:1
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作者 N. Jahan M. M. Rahman +1 位作者 M. Q. Huda S. M. Seo 《World Journal of Nuclear Science and Technology》 2017年第3期129-135,共7页
In reactor physics tests, it is important to monitor sub-criticality continuously during criticality approach. Reactivity measurements by the inverse kinetics method are widely used during the operation of a nuclear r... In reactor physics tests, it is important to monitor sub-criticality continuously during criticality approach. Reactivity measurements by the inverse kinetics method are widely used during the operation of a nuclear reactor. This technique is successfully applied at sufficiently high power level or to a core without an external neutron source where the neutron source term in point reactor kinetics equations may be neglected. For operation at low power levels or in the sub-critical domain, the increase in the fluctuation of the neutron signal may cause difficulties in the evaluation of reactivity and the effect of direct emission from the external neutron source may not be neglected. Therefore, contribution of the neutron source must be taken into account and this implies knowledge of a quantity proportional to the source strength, which calls the source term and then it should be determined. The research work has been conducted to measure reactivity with source term using a dedicated reactivity measurement system by the Least Square Inverse Kinetics Method (LSIKM). Application to a simulator of HANARO research reactor, Korea Atomic Energy Research Institute (KAERI), with known source strength and reactivity worth has showed consistent and satisfactory agreement. 展开更多
关键词 Source Strength Sub-Critical REACTIVITY REACTOR KINETICS INVERSE KINETICS Method
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