Surveying control network optimization design is related to standards,such as precision,reliability,sensitivity and the cost,and these standards are related closely to each other.A new method for surve... 相似文献
On the basis of digital records from Tayuan well,we study coseismic effects of water temperature caused by re-mote earthquakes.The records show that the water temperature changes are consistently following the process ofdrop-rise-recovery regardless of focal mechanism or epicentral directions.The step amplitude of water temperatureincreases with the increase of earthquake magnitude,and decreases with the decrease of epicentral distances.Theyhave rather well correlation.Water temperature rising after earthquake is influenced by water level variations.Fi-nally,the mechanisms of coseismic effects of water temperature have been discussed.Preliminary study shows thataccelerated convection and mixing of different temperature water in virtue of seismic wave are the main causes ofwater temperature drops.Seismic wave accelerates water convection,which causes warm water to move up fromdeeper part of the well and cold water to go down from the upper part.Temperature probe will detect water tem-perature drops at early stage.After the occurrence of earthquake,as the fluctuation of water level gradually quietsdown,water temperature near the probe begins to rise. 相似文献
Based on remote sensing data on land use provided by the Chinese Academy of Sciences and socio-economic data collected by the authors,this paper analyzes the trends and regional differences in built-up area(BUA) expansion in China from the late 1980s to 2000,and empirically estimates the major determinants of BUA expansion in different regions in 1996―2000.In 1989―2000,although China's overall BUA expansion accelerated,the trends differed significantly among regions.BUA expansion in the central and western regions accelerated significantly,but it slowed down considerably in the east-ern region.The estimation results from our econometric analysis reveal that BUA expansion in the eastern region reached a period when economic growth had no further significant impact on per capita BUA,the land utilization in this region has become more intensive with further expansion of the economy.In the central and western regions,the BUA has expanded remarkably due to the relatively more flexible land development policies and the relatively cheap land prices.Therefore,as the econ-omy continues to grow rapidly,policies relating to BUA expansion and cultivated land reductions may face more serious challenges in the central and western regions. 相似文献
Mapping with Ag/Au ratios of mineralized rocks and ores as a parameter reveals that the deep fractures in the Gangdise block control the distribution of the high value regions which may represent the shallow zones of strongly mineralized areas. The variance gradient regions with large Ag/Au ratio may represent the boundaries between strongly mineralized areas and weakly mineralized areas. In the middle part of the Gangdise block, gold and silver mineralization centers mainly distribute along the NW extending Coqen-Xigaze region, NE extending Yangbajain region and E-W extending Lhasa-Gongbogyamda region. The gold and silver mineralized rocks and ores may have been slightly denuded in the west of the middle Gangdise block, and the denudation in the east, however, may be stronger. The primary gold and silver prospect in the west may be better than in the east.
In view of the large quantities of areas,complex landform and dynamic change of resources and environ-ment in China,China has already funded abundantly a series of macro remote sensing investigation projects in land use cover change(LUCC) since 1990.Supported by the achievements of such projects,Chinese resources,environmental and remote sensing database(CRERS) was created.In this paper,we standardized the LUCC dataset of CRERS at scale of 1km,which facilitated the study of spatial features of LUCC in China.The analysis on the spatial features of LUCC and their causes of formation in China are based on the CRERS supported by the technologies of Geographic Information System(GIS) .The whole research was based on the grade index of land use,ecological environmental index and index of population density.Based on the correlation analysis,we found that the special features of LUCC were closely related with those of ecological environment and population density,which resulted form that areas with better ecological environ-ment and high production potential of land were easy and convenient for human being to live,which,furthermore,led to the aggravation of excessive exploitation of land resources there. 相似文献
1 INTRoDUCTIONIt is well known that solar proton flares are maiuly correlated with strong, bright H. flares,in particular, with two ribbon flares. Ellison et al. (l961) were the first to draw attelltion tothe faCt that all cosndc-ray flares had the typical two-ribbon shape. Then, Svestka and Simon(1976) drew uP the "Catalog of Solar Particle Evellts, 195ty1969", and using this Catalog,Dodson and Hedeman could safely identify the flare sources for 50 proton events. Out of the 50idellti… 相似文献
1. IntroductionDuring June and July, from the mid-lower reachesof the Yangtze River basin in China to southern Japan,a precipitation zone with intensive torrential rain ap-pears and lasts for two to three weeks. This phe-nomenon is called the "mei-yu" in … 相似文献