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新疆玛纳斯县大气臭氧浓度时空变化及影响因子分析 被引量:3
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作者 甘玉柱 兰瑞 任岗 《干旱环境监测》 2021年第2期86-90,共5页
选取新疆玛纳斯县2018—2019年空气自动站的监测数据,统计分析了臭氧浓度时空变化规律。主要结果表明,2019年臭氧为首要污染物天数同比2018年增加48.9%,2019年因臭氧浓度超标造成轻度污染天数较上年增加250%,臭氧已成为影响空气质量的... 选取新疆玛纳斯县2018—2019年空气自动站的监测数据,统计分析了臭氧浓度时空变化规律。主要结果表明,2019年臭氧为首要污染物天数同比2018年增加48.9%,2019年因臭氧浓度超标造成轻度污染天数较上年增加250%,臭氧已成为影响空气质量的重要因子之一。臭氧浓度具有明显的季节变化特征,2018—2019年玛纳斯县臭氧平均浓度均在5—8月达到全年的最高值,11月至翌年1月浓度为全年最低值,臭氧浓度整体呈现夏季高,冬季低的特点,城市形成局部臭氧超标的主要原因及其影响力的大小受温度和风速的影响。在此基础上对臭氧污染进行了溯源及影响因子分析,提出防控臭氧污染的建议。 展开更多
关键词 臭氧污染 时空变化及影响因子 分析建议
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基于改进拉普拉斯中心性的高速路网状态识别方法
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作者 薛相全 庞明宝 《科学技术与工程》 北大核心 2023年第5期2190-2196,共7页
为提高高速公路网络运行效率,提出一种考虑不同路段对系统时空影响差异性的高速公路网络交通状态识别方法。定义路网各类型路段为节点及其状态计算方法,建立基于改进拉普拉斯中心性和时空影响因子的路网状态识别模型。其中,利用皮尔逊... 为提高高速公路网络运行效率,提出一种考虑不同路段对系统时空影响差异性的高速公路网络交通状态识别方法。定义路网各类型路段为节点及其状态计算方法,建立基于改进拉普拉斯中心性和时空影响因子的路网状态识别模型。其中,利用皮尔逊相关系数改进拉普拉斯中心性方法以评估节点自身影响,设计时空影响因子评估邻居节点影响;融合节点自身及邻居节点影响,建立节点权重系数模型;在以上基础上建立反映路网交通状态的综合判别模型。以京港澳高速徐水-清苑的高速公路网络为例予以验证,结果表明:在不同交通需求情景下,所提方法能有效识别交通状态;对比交通运行指数(traffic performance index,TPI)模型和车辆行驶时间(vehicle hour traveled,VHT)模型,所提方法状态识别精准度均为最优,尤其是在交通需求大的情况下,对于含匝道节点3和纯主线节点4,与稳定性较强的TPI模型相比,所提方法准确率提升了9.7%和7.1%,进一步证明了模型的适用性强,能够满足工程实际的需要。 展开更多
关键词 智能交通 高速公路网络状态识别 改进拉普拉斯中心性 时空影响因子 节点权重模型
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Temporal-spatial Changes in Inner Mongolian Grassland Degradation during Past Three Decades 被引量:10
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作者 张清雨 吴绍洪 +1 位作者 赵东升 戴尔阜 《Agricultural Science & Technology》 CAS 2013年第4期676-683,共8页
[Objective] This study aimed to analyze the temporal-spatial variation of Inner Mongolian grassland degradation during past three decades. [Method] The dis- tribution characteristics of grassland were described by lan... [Objective] This study aimed to analyze the temporal-spatial variation of Inner Mongolian grassland degradation during past three decades. [Method] The dis- tribution characteristics of grassland were described by land use types supervised classification with TM/ETM. Then, temporal-spatial changes of grassland coverage were quantified by the mean of maximum vegetation coverage in last 30 years. Lastly, the grassland degradation reasons were explored through statistic analysis between the grassland coverage and precipitation, temperature and grazing intensity. [Result] The grassland degradation index of Inner Mongolia was increased from 1.38 to 1.68, and the smallest was 1.28 in 2005s. Grassland degradation and improve- ment were concurrent after 1980s, but grassland degradation was the major change trend for Inner Mongolia grassland. The area of grassland degradation was enlarged from 18.08×10^4 km2 in 1980s to 22.47×10^4 km2 in 2010s on the whole and distribu- tion range was shifted from central-eastern to west in Inner Mongolia that mainly distributed on Hulun Buir and Xilin Gol grassland in 1980s and Ordos and Alax grassland in 2010s. The grassland area of degradation had a rising trend form 1980s to 1995s, then reduced to 10.8x104 km2 in 2005s, and decreased in 2010s, which mainly speared in the west of Xilin Gol grassland. [Conclusion] Inner Mongo-lian grassland degradation were become more seriously in last 30 years because that temperature, precipitation and graze intensities change, which not performance on decreasing coverage but grassland areas. 展开更多
关键词 Grassland degradation Temporal-spatial change Influencing factor Inner Mongolia
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