利用案例推理（CBR）方法对雷达图像进行土地利用分类   总被引：14，自引：0，他引：14  

黎夏  叶嘉安  廖其方 《遥感学报》2004,8(3):246-253

提出了基于案例推理 (CBR)的遥感分类的新方法。基于规则的专家系统被用来提高遥感分类的效率。但所涉及的规则可能多达上百或上千条 ,有的问题根本无法用规则来表达。CBR只是根据以往的案例进行推理 ,克服了基于规则的推理方法的不足 ,可以用来解决一些复杂的资源环境问题。利用CBR和模糊数学结合 ,并通过分层随机采样来控制案例在空间上的分布 ,以反映复杂环境所造成的光谱变化 ,由此解决遥感分类中的“同物异谱”现象。实验表明 ,所建立的案例库可以被重复多次使用 ,分类的效果比监督分类和非监督分类要好。  相似文献   

Impact of land-cover and climate changes on runoff of the source regions of the Yellow River     

LI Daofeng  TIAN Ying  LIU Changming  HAO Fanghua 《地理学报》2004,14(3):330-338

After dividing the source regions of the Yellow River into 38 sub-basins, the paper made use of the SWAT model to simulate streamflow with validation and calibration of the observed yearly and monthly runoff data from the Tangnag hydrological station, and simulation results are satisfactory. Five land-cover scenario models and 24 sets of temperature and precipitation combinations were established to simulate annual runoff and runoff depth under different scenarios. The simulation shows that with the increasing of vegetation coverage annual runoff increases and evapotranspiration decreases in the basin. When temperature decreases by 2oC and precipitation increases by 20%, catchment runoff will increase by 39.69%, which is the largest situation among all scenarios.  相似文献   

不同降水天气系统自然降水特征及火箭人工增雨潜力分析   总被引：4，自引：1，他引：4  

吴志会  段英  张晶  石立新 《气象科技》2005,(Z1)

统计分析了1981~2000年20年中15种降水天气系统影响下河北地区自然降水特征,并对火箭人工增雨的潜力进行了初步分析。统计分析表明:西来槽类、高空低涡类、冷锋、切变线和副高后部等天气系统是影响河北地区的主要降水系统,其降雨量和降雨日数占到了90%以上;不同的天气系统在不同季节对降水的贡献有所不同,其中西来槽类的降雨量和降雨日数均居首位,开展人工增雨催化作业机会最多;夏季降水系统最强,云水资源最为丰富,人工增雨潜力很大,是开展火箭人工增雨催化作业的最佳季节,春秋两季增雨潜力明显比夏季小,冬季最小;倒槽、副高后部、台风低压、高空低涡类和气旋类等系统最强,日降雨量和单位面积降雨量明显比其它系统大,尤其对蓄水型火箭增雨作业十分有利。  相似文献   

大桥水库MS4.6级诱发地震的初步研究     

胡先明  叶有清 《四川地震》2005,(4):25-31

2002年3月3日大桥水库诱发了Ms4．6级水库地震，其发震构造是安宁河东支断裂近傍具有正断层性质的一个分支断裂。据大桥台网7年多库区地震观测事件记录，地震空间分布上水体附近有一个明显的活跃过程，大坝上游发生小震群，大坝下游发生主震序列。地震的震源深度在蓄水前后有明显变化。4．6级地震的震源机制解的主压应力轴方位和倾角与大多数活动断裂上的地震有明显的差别，主压应力轴的倾角与其它的水库地震相比也存在较大差别。  相似文献   

广东省东部地区的S波速度结构   总被引：7，自引：0，他引：7       下载免费PDF全文

闻则刚  杨马陵  叶秀薇  康英  王正尚 《地震工程学报》2005,27(2):154-157

利用广东省数字遥测台网记录到的2000年11月16日发生在所罗门群岛的两次Ms7．7和Ms7．8地震及2000年11月18日新爱尔兰地区的Ms7．3地震面波波形数据，测定了在广东地区汕头和韶关之间路径上的相速度频散曲线并反演得到了对应的地壳横波速度结构。结果表明该地区的地壳厚度为30km，上地壳横波速度变化较大，中下地壳相对均匀，没有发现地壳内部的低速层。  相似文献   

Major reactive species of ambient volatile organic compounds (VOCs) and their sources in Beijing   总被引：1，自引：0，他引：1  

SHAO Min  FU Linlin  LIU Ying  LU Sihua  ZHANG Yuanhang  TANG Xiaoyan 《中国科学D辑(英文版)》2005,48(Z2)

Volatile organic compounds (VOCs) are important precursors of atmospheric chemical processes. As a whole mixture, the ambient VOCs show very strong chemical reactivity. Based on OH radical loss rates in the air, the chemical reactivity of VOCs in Beijing was calculated. The results revealed that alkenes, accounting for only about 15% in the mixing ratio of VOCs, provide nearly 75% of the reactivity of ambient VOCs and the C4 to C5 alkenes were the major reactive species among the alkenes. The study of emission characteristics of various VOCs sources indicated that these alkenes are mainly from vehicle exhaust and gasoline evaporation. The reduction of alkene species in these two sources will be effective in photochemical pollution control in Beijing.  相似文献   

Anisotropy from full waveform inversion of multicomponent seismic data using a hybrid optimization method     

Ying Ji  Satish C. Singh 《Geophysical Prospecting》2005,53(3):435-445

Seismic waveforms contain valuable information about the media, but the waveform inversion is a non‐linear problem. We present a waveform inversion method that combines a local optimization method with a genetic algorithm to determine the anisotropic parameters of a horizontally stratified medium. Synthetic seismograms for a horizontally stratified anisotropic medium are calculated using the reflectivity technique. In the initial stage of the inversion, the global space‐sampling properties of the genetic algorithm are used to direct the search to the region close to the global solution. This solution is then further improved using a conjugate‐gradient method. The numerical experiments performed with noisy synthetic data show that our hybrid optimization method satisfactorily reconstructs the anisotropic parameters at a reasonable computing cost while the range of slowness is adequate. We found that (i) for small‐angle data neither single‐ nor multiple‐component data are sufficient to determine the anisotropic parameters uniquely; (ii) for medium‐angle data the multiple‐component data are sufficient to determine the anisotropic parameters exactly whereas the single‐component data are not sufficient; and (iii) for wide‐angle data, either single‐ or multiple‐component data are sufficient to determine the anisotropic parameters accurately.  相似文献   

基于GIS的地下水水源地补给潜力探讨     

叶超  李宇  田茂勇 《水文地质工程地质》2005,32(1):67-69

本文提出了一种基于GIS的补给潜力分析方法。在实例研究中,通过对地形、地表物质组成、包气带岩性、植被覆盖等因子建立的专题图层的叠加分析,确定了地下水的补给潜力分区,结合研究区含水层分布特征,综合确定了水源地的靶区和开采潜力区。研究表明,利用GIS确定研究区降雨入渗补给量是一种高效、直观、可行的方法。  相似文献   

GEOCHEMICAL CHARACTERISTICS OF PLATINUM GROUP ELEMENTS IN JINCHUAN SUPER-LARGE SULFIDE COPPER-NICKEL DEPOSIT, JINCHANG CITY, GANSU PROVINCE, CHINA     

WANG Ruiting MAO Jingwen HE Ying WANG Dongsheng TANG Zhongli 《大地构造与成矿学(英文版)》2005,29(2):152-163

The platinum-group element geochemistry of rocks and ores from Jinchuan super-large copper-nickel sulfide deposit is systemically studied in this paper. The Cu/Pd mean ratio of Jinchuan intrusion is lower than that of original mantle magma, which indicates that these ultrabasic rocks were crystallized from magma that lost Pd in the form of melting segregation of sulfides. The PGE of the rocks show trend of partial melting, similar to that of mantle peridotite, which shows that magma formation occurs during rock-forming and ore-forming processes. The chondrite normalized PGE patterns of the rocks and ores are well related to each other, which signifies the signatures of multi-episode magmatic intrusion, melting and differentiation in the formation processes of rocks and ores. In addition, analyses about the relation between PGE and S, and study on Re-Os isotopes indicate that few contamination of the crustal substances occurred during the magmatic intrusion and the formation of deposit. However, contamination by crustal substances helps to supply part of the S for the enrichment of PGE. Meanwhile, the hydrothermal process is also advantageous for the enrichment of PGE, especially lbr Pt and Pd, due to deep melting segregation. The characteristic parameters （such as Pt/（Pt＋Pd）, （Pt＋Pd）/（Ru＋Ir＋Os）, Pd/Ir, Cu/（Ni＋Cu）, and so on.） for platinum-group elements for Jinchuan sulfide copper-nickel deposit show the same features as those for sulfide copper-nickel deposit related to basic magma, which also illustrates its original magma property representative of Mg-high tholeiite. Therefore, it is the marie （not ultramafic） magma that resulted in the formation of the superlarge sulfide copper-nickel deposit enriched in Cu and PGE. To sum up, the geochemical characteristics of platinum-group elements in rocks and ores from Jinchuan copper-nickel sulfide deposit are constrained by the continental rift tectonic environment, the parent magma features, the enriched mantel magma source, the complex metallogenesis and PGE geochemical signatures, and this would be rather significant for the study about the genetic mechanism of copper-nickel sulfide deposits.  相似文献   

Visualization issues in the development of electronic atlas in China     

WANG Yingjie  SU Ying  CHEN Xiaogang  YU Zhuoyuan  Liqiu MENG 《地理学报》2005,15(1):87-96

In this paper, we discuss the development of electronic atlas in China, with focus on the issues of visualization. We particularly categorise this development into four periods, and then analyse the characters in each period and discuss the visualization issues. The four periods are highlighted: 1) Infant period (<1990) characterized as computer assisted mapping with products of screen maps; 2) Starting period (1991-1995) characterized as object-oriented mapping with products of interactive maps/atlases; 3) Advancing period (1996-2000) characterized as integrated mapping with products of multimedia cartographic maps; 4) New era (> 2001) characterized as web mapping and adaptive map design with products of Internet maps and atlas as well as adaptive maps. It is obvious that the development follows the logical way from static to dynamic, and even real time visualization, from single user to multiple users, from presentation to exploration for effective communication and knowledge construction. Current research and development projects are focused on customisation of atlas information systems for real-time tasks, Internet operability, small displays and mobile environments. The major challenges involved in each of such customisation processes are identified and commented in relation to the further development of visualization.  相似文献