綦江流域一次破记录洪水过程的水文与雷达回波特征分析     

翟丹华  张亚萍  朱岩  黎中菊  邱鹏  黎春蕾 《湖北气象》2020,39(6):603-610

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近25a重庆地区小时降水时空分布特征分析     

杨春  张勇  张亚萍  余君  吴胜刚  李强 《湖北气象》2020,39(1):71-80

利用重庆34个自动站1991—2015年逐小时降水资料,分别从降水比率、强降水占比、强降水频次、强降水事件、极大强降水及极端强降水阈值等方面分析了重庆时空分布特征。结果表明:(1)降水比率、强降水占比、强降水频次、强降水事件、极大强降水及极端强降水阈值在空间分布上具有一致性,高值区主要分布在东南部与西部,低值区主要位于东北部与中部。(2)降水比率、强降水占比、强降水频次及极大强降水在年变化上表现出波动起伏特征,且降水比率相对变化幅度较小,后三者表现出同相位的变化特点。在月变化上,降水比率呈双峰特征,后三者一致呈单峰特征。在日变化上,强降水高频次主要出现在03—05时,低频次主要是13—15时。(3)在强降水事件持续性上,强降水事件持续时间及其降水开始至最强降水时间的空间分布一致:高值区主要集中在东北部与东南部,而低值区主要分布在中部与西部。总体上看,持续时间越长,产生最强降水的时间越延后,且持续时间长的强降水事件主要产生在23时至次日04时。(4)第99、99.5、99.9百分位阈值与广义极值(GEV)分布函数5、10、20、50、100 a重现期阈值及极大强降水观测值在空间分布上与强降水具有一致性。  相似文献   

三氯乙烯污染土壤的复电阻率特征和频谱参数研究     

张振宇  许伟伟  邓亚平  任静华  施小清  吴吉春 《地学前缘》2021,28(5):114-124

复电阻率法(complex resistivity, CR)由于其对孔隙水化学性质、固-液界面和流体含量的敏感性已成为具有良好前景的污染物识别工具。本研究选取三氯乙烯(trichloroethylene, TCE)作为典型有机污染物,利用频谱激电仪对TCE污染土壤进行了复电阻率测量,讨论孔隙水盐度、水饱和度和土壤类型对污染土壤的复电阻率特征和频谱参数影响。试验结果表明:污染土样的复电阻率均随水饱和度的降低和孔隙水盐度的减小而增大;土壤黏土含量影响孔隙水连续性,当孔隙水出现不连续状态时,实部和虚部出现大幅度变化。总充电率M随着孔隙水盐度的增加而增加,随水饱和度的降低先减后增。黏土颗粒重排导致的比表面积减小使得总充电率M减小,双电层极化加强使总充电率M升高;平均弛豫时间常数随孔隙水盐度的升高而降低,二者呈对数相关,随水饱和度变化的主要原因为可极化孔隙尺寸的变化。本研究探讨了地球物理参数与水文地质参数间的关系,为SIP方法在实际有机污染场地调查与评估提供了理论依据。  相似文献   

基于Pitzer模型预测Na-K-Ca-Mg-Cl-H2O溶液的密度     

路淼  李东东  李武  董亚萍  胡斌 《地学前缘》2021,28(6):179-186

天然水体系的体积性质与压力、温度、组成的相关性(PVTx性质)研究在地球化学、盐湖化工等领域有广泛的应用。密度是卤水最基本的体积性质,不仅可以通过实验测定,还可以用理论模型进行预测。建立富钾卤水密度与组成、温度的关联模型有助于认识钾在复杂卤水中的富集、迁移规律。为了构建基于Pitzer离子相互作用模型的卤水密度预测方法,本文用高精度振荡管密度计测定了常压下KCl、CaCl₂纯盐溶液以及最高离子强度为11.8 mol·kg^-1的混合溶液在283~323 K下的密度,用所测得的密度通过Pitzer离子相互作用模型拟合得到多温下Pitzer单电解质参数和Pitzer混合参数。用Pitzer模型参数计算了Na-K-Ca-Mg-Cl-H₂O体系293~313 K的密度,计算密度值与实验值的相对偏差在±0.25%以内,计算的结果整体上要优于文献值,文献在计算中均未考虑Pitzer混合参数项。结果表明,K、Ca、Cl离子间的相互作用对于Na-K-Ca-Mg-Cl-H₂O溶液的密度有显著的影响,本文获得的Pitzer参数反映了这些离子间的相互作用,可用于计算含有K、Ca、Cl离子的复杂卤水密度的预测。  相似文献   

Study on the Combined Application of CFAR and Deep Learning in Ship Detection     

Ruifu Wang  Jie Li  Yaping Duan  Hongjun Cao  Yingjie Zhao 《Journal of the Indian Society of Remote Sensing》2018,46(9):1413-1421

To maintain national socio-economic development and maritime rights and interests, it is necessary to obtain the space location information of various ships. Therefore, it is important to detect the locations of ships accurately and rapidly. At present, ship detection is mainly carried out by combining satellite remote sensing imaging with constant false alarm rate (CFAR) detection. However, with the rapid development of satellite remote sensing technology, remote sensing data have gradually begun to show the characteristics of “big data”; additionally, the accuracy and speed of ship detection can be improved by analysing big data, such as by deep learning. Thus, a ship detection algorithm that combines CFAR and CNN is proposed based on the CFAR global detection algorithm and image recognition with the CNN model. Compared with the multi-level CFAR algorithm that is based on multithreading, the algorithm in this paper is more suitable for application to ship detection systems.  相似文献   

Multivariate statistical techniques for evaluating and identifying the environmental significance of heavy metal contamination in sediments of the Yangtze River, China   总被引：3，自引：0，他引：3  

Lan Wang  Yaping Wang  Wenzhao Zhang  Chunxue Xu  Ziyi An 《Environmental Earth Sciences》2014,71(3):1183-1193

The concentrations of heavy metals (Cr, Co, Ni, Cu, Zn, Pb, Cd, As, Hg, and Fe) in sediments of the Yangtze River, China, were investigated to evaluate levels of contamination and their potential sources. The lowest heavy metal concentrations were found in the source regions of the river basin. Relatively high concentrations of metals, except Cr, were found in the Sichuan Basin, and the highest concentrations were in the Xiangjiang and Shun’anhe rivers. All concentrations, except Ni, were higher than global averages. Principal component analysis and hierarchical cluster analysis showed that Zn, Pb, As, Hg, and Cd were derived mainly from the exploitation of various multi-metal minerals, industrial wastewater, and domestic sewage. Cu, Co, and Fe were derived mainly from natural weathering (erosion). Cr and Ni were derived mainly from agricultural activities, municipal and industrial wastewater. Sediment pollution was assessed using the geoaccumulation index (I _geo) and enrichment factor (EF). Among the ten heavy metals assessed, Cd and Pb had the highest I _geo values, followed by Cu, As, Zn, and Hg. The I _geo values of Fe, Cr, Co, and Ni were <0 in all sediments. EF provided similar information to I _geo: no enrichment was found for Cr, Co, and Ni. Cu, Zn, As, and Hg were relatively enriched at some sites while Cd and Pb showed significant enrichment.  相似文献   

海南岛周边海砂资源勘查进展及选区建议          下载免费PDF全文

仝长亮  宋家伟  邓开章  韩孝辉  王爱军  汪亚平 《海洋学研究》2022,40(3):33-48

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我国沿海地区物流效率和海洋产业集聚水平协调关系的时空格局特征分析          下载免费PDF全文

吴亚萍 《海洋开发与管理》2022,39(8):29-36

为促进我国物流业和海洋产业的协调可持续发展,文章综合运用中立型交叉效率模型、熵值法、耦合评价模型和重心迁移模型,选取包括区位熵在内的多层次评价指标,系统评价2008—2018年我国11个沿海地区的物流效率和海洋产业集聚水平,分析二者协调关系的时空格局特征,并提出发展建议。研究结果表明：2008—2018年我国沿海地区的物流效率和海洋产业集聚水平均呈提高趋势,但仍有较大的发展空间,且存在较大的区域差异;物流效率和海洋产业集聚水平的整体耦合协调度不断提高,并由初级协调发展到中级协调,各沿海地区的耦合协调等级从濒临失调到良好协调不等,耦合协调度重心基本呈NE-SW的迁移趋势;改善物流效率和海洋产业集聚水平的协调关系应加强物流基础设施建设、坚持陆海双向联动和促进资源要素流动。  相似文献   

Dust and Sand Storms (DSS) in East Asia     

Youngsin Chun  Yaping Shao  Masataka Nishikawa 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(1):1-2

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Fate and transport of ethanol-blended dissolved BTEX hydrocarbons: a quantitative tracing study of a sand tank experiment   总被引：2，自引：1，他引：1  

Yudao Chen  Yaping Jiang  Yinian Zhu  Yuan Xia  Yaping Cheng  Yuequn Huang  Hanle Liu 《Environmental Earth Sciences》2013,70(1):49-56

To estimate the behavior of ethanol-blended dissolved BTEX hydrocarbons in groundwater, a quantitative tracing study instead of qualitative analysis was carried out by using a large sand tank, into which 2-L solution including bromide, ethanol and dissolved BTEX was injected under a controlled hydraulic condition. Mean residence time (MRT), pore volume swept by solute (V _p), retardation coefficient (R) and biodegradation rate constant (k) of injected solutes were estimated. Compared with bromide that was used as a conservative tracer, ethanol and BTEX had shorter MRT and smaller V _p with the sequence of EtOH < T < E < m/p-X < o-X < B < Br. Biodegradation was confirmed as evidenced by the consumptions of dissolved oxygen (DO), nitrate and sulfate, and the production of acetate. The sequence of k as EtOH > T > E > m/p-X > o-X > B was just opposite to the sequences of MRT and V _p. The relationship among above sequences implies that MRT and V _p can be used as indicators to assess in situ biodegradability of a solute. Biodegradation of a reactive solute can make its MRT shortened and V _p shrunk. In addition, the sorption of ethanol could be neglected (R = 1.0), whereas BTEX compounds were adsorbed (R = 1.04–1.15). It should be noted that biodegradation of a solute can affect the estimation of its retardation coefficient. To our knowledge, this paper provides an available route to quantitatively estimate biodegradability of a solute in groundwater.  相似文献