地电震后效应与新地震异常的识别方法     

余素荣  李晓玲 《地震》1996,16(1):80-85

文中重点讨论了大华北地区，Ａ、Ｂ、Ｃ三类地震活动的地电震后效应特征。研究表明，不同地震活动类型的地电震后效应差异是比较明显的。这种差异性可为未来震情判断提供地电前兆依据。  相似文献   

苏北低地系统及其对海平面上升的复杂响应   总被引：5，自引：0，他引：5  

陈晓玲  王腊春 《地理学报》1996,51(4):340-349

苏北低地位处我国沿海中部，地面平均高程３ｍ左右，平均坡降多在０．２‰－２‰之间，河渠水面比降平均迷０．０４‰，极易发生洪涝灾害。未来海平面上升，将对这一洪涝灾害频发地区带为严重的危害。本文通过剖析苏北低地系统状态与结构，考察低地系统对海平面上升的复杂响应过程，以寻求系统对未来全球变化的积极适应方式。  相似文献   

论沿海低地洪涝灾害测度问题     

陈晓玲 《武汉大学学报(信息科学版)》1997,(3)

选取频遭洪涝灾害威胁与危害的沿海平原低地，试图建立描述洪涝强度的等级测度模式，并分析其减灾意义。  相似文献   

北京地区中尺度非静力数值预报产品释用技术研究   总被引：9，自引：2，他引：9       下载免费PDF全文

王迎在  刘凤辉等 《应用气象学报》2002,13(3):312-321

在国家气象中心与北京市气象局联合开发的“北京地区中尺度数值预报业务系统”基础上，充分利用高分辨率中尺度数值预报产品和地面加密气象观测资料，分别使用统计和动力释用方法进行局地温度、风和北京市区空气污染状况的预报。试预报结果表明，用卡尔曼滤波方法建立的温度和风的预报效果高于中尺度数值预报直接输出结果；使用中尺度数值预报结果作为一个简单的污染预报动力模式的气象背景场，进行了污染预报试验，结果表明该预报方法具有一定的预报能力，其中SO₂、NO₂、CO浓度的预报准确率在夏、秋、冬三季中均可达到65%以上。上述研究成果已用于业务预报。  相似文献   

过冷层状云中飞机播云有效区域的模拟研究   总被引：8，自引：2，他引：8  

余兴  王晓玲  戴进 《气象学报》2002,60(2):205-214

根据飞机人工增雨作业个例 ,利用层状云中催化剂输送扩散的三维时变模式 ,对过冷层状云中播云产生的有效区域、催化剂水平输送和扩散速率等进行了模拟研究。结果表明 :(1)飞机播云 4 5min线长 32 7km ,投影有效面积和有效体积在播云刚结束时 (5 0分 )达到极大 ,其值分别为 70 7km2 和 2 98.0km3 ,有效扩展宽度和厚度为 2 .5 1km和 0 .4 2km ;(2 )有效作用时段为 2 0～ 80min ,其间的投影有效面积平均值为 5 13.3km2 ,平均有效扩展宽度和厚度分别为 2 .4 1km和 0 .4 5km ;(3)在扩散作用下 ,投影有效面积和有效体积先随时间不断增加 ,达到极值后逐渐减小 ,播云结束 (5 5分 )后 ,云中的有效区域消失 ,其间的投影有效面积平均值为 389.7km2 ,平均有效扩展宽度和厚度分别为 2 .34km和 0 .4 4km ;(4)云中催化剂水平输送 1h的平均值达到 6 5km ,仅与风场有关。催化剂扩散速率 1h平均为 0 .82m/s,与风、温、湍流有关 ;(5 )在飞机增雨作业时 ,飞行方案的设计必须是严格科学的 ,以便进一步提高人工增雨的实效  相似文献   

Statistical characteristics of chlorophyll-a concentration in Hong Kong's coastal waters     

CHEN Xiaoling  Yok Sheung Li  LI Zhilin 《地理学报》2002,12(3):331-342

In this paper seven of the ten Water Control Zones (WCZs) in Hong Kong's coastal waters with monthly or bi-weekly sampling data of 17 parameters collected at 37 monitoring stations from 1988 to 1999 were selected to analyze the spatial and temporal variations of chlorophyll-a and its influencing factors. Cluster analysis was employed to group the monitoring stations based on the structure of the data set. Multiple step regression was employed to determine the significant influencing factors of chlorophyll-a level. The results suggest that all the monitoring stations could be grouped into two clusters. Cluster I with frequent red tide incidents comprises two WCZs which are semi-enclosed bays. Cluster II with less red tide occurrence comprises the other five WCZs in an estuarine environment in the west. For both clusters, the organic contents indicator, BOD5, was a common significant influencing factor of the chlorophyll-a level. Nitrogen and light penetration condition related to turbidity, total volatile solids and suspended solids had more influence on the cholophyll-a level in Cluster I than in Cluster II, while phosphorus and oceanographic conditions associated with salinity, temperature, dissolved oxygen and pH were more important in Cluster II than in Cluster I. Generally, there was a higher average chlorophyll-a level in winter and autumn in a year. The chlorophyll-a level was much higher in Cluster I than in Cluster II among all seasons. Although the chlorophyll-a concentration had great variations from place to place in Hong Kong's coastal waters, it seemed to have a common long term fluctuation period of 8-10 years with a high-low-high variation in the period in the whole region, which might be influenced by other factors of global scale.  相似文献   

GIS-T中时空动态分段及其对交通事件的表达     

郭鹏  陈晓玲 《武汉大学学报(信息科学版)》2008,33(4):422-425

针对当前动态分段方法缺乏时间维的问题,在典型的标准动态分段基础上增加时间维线性特征,形成时空动态分段方法,并使用该方法在ArcGIS中对交通事件进行了可视化表达.  相似文献   

基于重构的多尺度目标提取与分割     

蒋志勇  陈晓玲  秦前清  陈楚群 《武汉大学学报(信息科学版)》2008,33(11):1158-1161

通过形态重构开闭算子构造了一个多尺度的目标提取和分割算法.首先用结构元素nB对影像分别作基于重构的Top-Hat和Bottom-Hat变换,得到所有不能放入nB的亮和暗的目标;然后再用结构元素(n-1)B对影像作开运算,消除所有不能放入该结构元素的目标.那么结果影像中就只剩下能同时放入nB和(n-1)B的目标.对不同尺度的结果影像进行处理,就可以得到不同尺度下的目标分割结果.重构是一个连通è区域算子,连通区域是运算的基本单位,所以不会改变影像中边缘的位置,同时不会有新的边缘和虚假的极值出现.  相似文献   

Morphological Characteristics of （K, Na）-Rectorite from Zhongxiang Rectorite Deposit, Hubei, Central China   总被引：3，自引：0，他引：3  

洪汉烈  张晓玲  万淼  侯一俊  杜登文 《中国地质大学学报(英文版)》2008,19(1):38-46

The morphological characteristics of the Zhongxiang (钟祥) rectorite have been studied using X-ray diffraction (XRD), electron probe micro-analyzer (EPMA), scanning electron microscopy (SEM), atomic force microscope (AFM), and high-resolution transmission electron microscopy (HRTEM). The structural formula of the Zhongxiang rectorite is: interstratification of (K, Na)-mica and Ca-montmorillouite. SEM observations show that Zhongxiang rectorite occurs as platy and fold-shaped crystals, and mainly as extremely thin plates with thickness ranging from 0.4 to 0.05 μm and a smooth (001) surface. There are well-developed polygonal steps on the surfaces of some thick crystals, suggesting a layer-by-layer growth mechanism. AFM observations show a series of steps with a height of 2 nm on the platy particles, suggesting the stacking of 20 nm fundamental particles. Club-like or fiber-shaped halloysite is included in the platy crystals with their elongated dimension paralleling (001) of the platy crystals or crossing the (001) surface of the platy rectorite, indicating multi-stage crystallization and involvement of hydrothermal fluids. The Zhongxiang rectorite was generated by both layer-by-layer growth mechanism and dissolution and crystallization growth mechanism with multistages.  相似文献   

应用空间技术研究干旱和半干旱地区由盐化作用造成的土地退化(英文)     

Mushtak T. Jabbar  Xiaoling Chen 《地球空间信息科学学报》2008,11(2):112-120

This study applied a computerized parametric methodology to monitor, map, and quantify land degradation by salinization risk detection techniques at a 1：250 000 mapping scale using geo-information technology. The northern part of the Shaanxi province in China was taken as a case. Multi-temporal remotely sensed materials of both Landsat TM and thematic maps （ETM＋） were used as the bases to provide comprehensive views of surface conditions such as vegetation cover and salinization detection. With ERDAS ver. 9.1 software, the Normalized Differential Salinity Index （NDSl） and Salinity Index （S.I.） were computed and then evaluated for land degradation by salinization. Arc/Info ver. 9.2 software was used along with field observation data （GPS） for analysis. Using spatial analysis methods, results showed that 19 973.1 km^2 （72%） of land had no risk of land degradation by salinization, 3 684.7 km^2 （13%） had slight land degradation by salinization risk, 2 797.9 km^2 （10%） had moderate land degradation by salinization risk, and 1 218.9 km^2 （4%） of the total land area was at a high risk of land degradation by salinization. The study area, in general, is exposed to a high risk of soil salinization.  相似文献