基于网络的空间信息表达研究   总被引：5，自引：1，他引：4  

张新池天河  陈华斌谭玉敏王钦敏  陈崇成卢毅敏 《地球信息科学学报》2003,5(2):43-45

本文结合我国目前“数字省区”空间信息共享建设对于空间信息网络表达的需求,深入分析了空间信息共享系统中多种空间信息的网络表达问题,以及实现共享空间信息网络表达所需要解决的3个基本问题。研究了基于XML的空间信息网络表达实现技术。该研究对于空间信息共享系统中实现空间信息网络分布式表达和系统共享空间信息的潜在价值有重要意义。最后通过“数字省(区)”建设的实践,实现了该研究成果的应用系统。  相似文献   

基于多源遥感数据的北京市1973-2005年间城市建成区的动态监测与驱动力分析   总被引：42，自引：0，他引：42  

牟风云  张增祥  迟耀斌  刘斌  周全斌  王长有  谭文彬 《遥感学报》2007,11(2):257-268

城市地域空间扩展情况是衡量城市化水平的重要测度指标。利用陆地卫星MSS影像、TM（或ETM＋）影像、灾害监测星座数据和“北京一号”小卫星数据,对1973—2005年北京市建成区的扩展过程、面积变化和土地利用影响进行了监测分析。结果表明：32年间,北京市建成区面积净增加超过1000km2,2005年达到1209.97km2,相当于1973年的6.58倍,年均扩展32.07km2。北京市建成区的扩展基本上呈现出以旧城区为中心向四周扩展的方式,并未在某一方向表现出特别明显的变化,但在不同时期内的扩展速度差异非常明显。北京市建成区的扩展面积中,54.34%来自于农村居民点和独立工矿用地及其他建设用地,43.57%来自于水田、旱地等耕地。人口增长对北京市建成区的扩展有显著的刺激作用;经济增长是城市变化的主要动力之一;交通的发展促进了城市用地的扩展,是城市扩展的牵引力,对城市空间扩展具有指向性作用;而政策与制度因素则在很大程度上决定了北京市发展和扩张的宏观格局。  相似文献   

Seedling growth dynamic of <Emphasis Type="Italic">Haloxylon ammodendron</Emphasis> and its adaptation strategy to habitat condition in hinterland of desert     

Wei Jiang  Zhang XiMing  Shan LiShan  Yan HaiLong  Liang ShaoMing 《中国科学D辑(英文版)》2007,50(1):107-114

Through measuring the above/below-ground growth data of Haloxylon ammodendron seedlings at different stages in hinterland of the desert the results show that the H. ammodendron seedling growth has demonstrated different adaptation characteristics in the continued arid environment with time and space. In May, July, September and October, the growth speed of vertical root is 0.607 cm/d, 0.809 cm/d, 0.155 cm/d and 0.394 cm/d, respectively; the growth speed of height is 0.093 cm/d, 0.076 cm/d, 0.408 cm/d and 136 cm/d, respectively. It is explained that seedlings root system has the growth superiority in space. The maximum growth speed of below-ground (vertical root and horizontal root) of seedling is earlier than that of above-ground (height and horizontal of shoot). In the different periods, the vertical growth speed and the horizontal growth speed of below-ground is 2–10 times and 3–5 times than the height increase speed and the shoot growth speed, respectively. In the whole season, the growth speed of above/below-ground of seedlings shows the alternation growth tendency. At the different periods, the root/shoot ratio of H. ammodendron seedlings is 0.41, 0.3, 0.39 and 0.88. All these characteristics are the comprehensive performance of seedlings’ strategy selection to adapt to the continued arid environment.  相似文献   

Nd Isotopes and Geochemistry of Phanerozoic Clastic Sedimentary Rocks from the Yangtze Block and Their Tectonic Implications   总被引：1，自引：1，他引：0  

周炼高山  刘勇胜Corey Archer 《中国地质大学学报(英文版)》2007,18(2):109-127

This article presents Sm-Nd and geochemical data on fine-grained sediments of the northern margin from the Yangtze block, China, to understand the variations of Nd isotopic compositions and crustal evolution history in this area. The results are as follows: (1) Nd isotopic compositions for clastic sedimentary rocks of the Middle-Late Proterozoic have relatively positive Nd(t) values ( 2.72 to 0.69), with Nd model ages from 1.38 Ga to 1.55 Ga, corresponding to the contemporaneous volcanic rocks from the Xixiang (西乡) Group. This indicates that the arc-related materials from Middle-Late Proterozoic dominate the provenances of the Middle-Late Proterozoic periods. (2) The gradual decrease in εNd(t) during the Cambrian-Carboniferous periods is likely to reflect the progressively increasing proportion of erosion materials from the Foping (佛坪) and Qinling (秦岭) complexes, corresponding to a gradually decreasing trend in the La/Th ratios. (3) A prominent increase in the εNd(t) value of the Late Permian strata probably reflects the significant incorporation of the mantle-derived materials. The trace element data are compared with data of the Emeishan (峨嵋山) flood basalts. These data indicate that the volcanic dust has been added to the Late Permian strata during the Late Permian, represented by periods of extremely high Emeishan flood basalt activity in the south-eastern margin of the Yangtze block.  相似文献   

基于MODIS地表覆盖(LC)的森林火灾识别方法   总被引：1，自引：1，他引：0  

赵文化  张鹏  单海滨 《气象科技》2008,36(2):210-214

通过分析MODIS多光谱地表覆盖产品,证明MODIS本身具有精确识别包括5种森林在内的IGBP 17种地表类型的能力,完全可以满足识别森林火灾的实际需要.在此基础上提出基于MODIS地表覆盖的森林火点识别方法,探讨使用MODIS地表覆盖数据识别森林火灾的数据处理操作过程.应用该森林火点识别方法,MODIS实时广播接收站可以建立一套由MODIS火点侦测模块和MODIS森林火点识别模块构成的完全基于自身数据的森林火灾监测系统.5种森林地表整体平均识别误差为3.5%,可以满足卫星遥感森林火灾监测系统要求.  相似文献   

Upper crustal abundances of trace elements: A revision and update   总被引：7，自引：0，他引：7  

Zhaochu Hu  Shan Gao   《Chemical Geology》2008,253(3-4):205-221

We report new estimates of abundances of rarely analyzed elements (As, B, Be, Bi, Cd, Ge, In, Mo, Sb, Sn, Te, Tl, W) in the upper continental crust based on precise ICP-MS analyses of well-characterized upper crustal samples (shales, pelites, loess, graywackes, granitoids and their composites) from Australia, China, Europe, New Zealand and North American. Obtaining a better understanding of the upper crustal abundance and associated uncertainties of these elements is important in placing better constraints on bulk crust composition and, from that, whole Earth models of element cycling and crust generation. We also present revised abundance estimates of some more commonly analyzed trace elements (Li, Cr, Ni, and Tm) that vary by > 20% compared to previous estimates. The new estimates are mainly based on significant (r² > 0.6) inter-element correlations observed in clastic sediments and sedimentary rocks, which yield upper continental crust elemental ratios that are used in conjunction with well-determined abundances for certain key elements to place constraints on the concentrations of the rarely analyzed elements. Using the well-established upper crustal abundances of La (31 ppm), Th (10.5 ppm), Al₂O₃ (15.40%), K₂O (2.80%) and Fe₂O₃ (5.92%), these ratios lead to revised upper crustal abundances of B = 47 ppm, Bi = 0.23 ppm, Cr = 73 ppm, Li = 41 ppm, Ni = 34 ppm, Sb = 0.075, Te = 0.027 ppm, Tl = 0.53 ppm and W = 1.4 ppm. No significant correlations exist between Mo and Cd and other elements in the clastic sediments and sedimentary rocks, probably due to their enrichment in organic carbon. We thus calculate abundances of these elements by assuming the upper continental crust consists of 65% granitoid rocks plus 35% clastic sedimentary rocks. The validity of this approach is supported by the similarity of SiO₂, Al₂O₃, La and Th abundances calculated in this way with their upper crustal abundances given in Rudnick and Gao [Rudnick, R., Gao, S., 2003. Composition of the continental crust. In: Rudnick, R.L. (Ed.), The Crust. In: Holland, H.D., Turekian, K.K. (Eds.), Treatise on Geochemistry, vol. 3. Elsevier–Pergamon, Oxford, pp. 1–64.]. The upper crustal abundances thus obtained are Mo = 0.6 ppm and Cd = 0.06 ppm. Our data also suggest a  20% increase of the Tm, Yb and Lu abundances reported in Rudnick and Gao [Rudnick, R., Gao, S., 2003. Composition of the continental crust. In: Rudnick, R.L. (Ed.), The Crust. In: Holland, H.D., Turekian, K.K. (Eds.), Treatise on Geochemistry, vol. 3. Elsevier–Pergamon, Oxford, pp. 1–64.].  相似文献   

汶川地震框架柱震害的初步分析   总被引：10，自引：0，他引：10  

夏珊  刘爱文 《震灾防御技术》2008,3(3):237-242

按照框架结构抗震概念设计的要求,结构应具有多道抗震防线,其中一个原则是“强柱弱梁”。但是在汶川地震中,框架结构柱的破坏明显重于梁,柱端与节点的破坏较为突出,即所谓的“强梁弱柱”结构很普遍。在对地震破坏区实地考察的基础上,对框架结构梁柱节点处的破坏以及柱顶、柱脚和柱身的震害进行分类,分析了各种震害的原因,总结了框架结构中框架柱的破坏特点,从期为将来框架柱的抗震设计提供震害经验。  相似文献   

主题性旅游协作联盟及其构建——以运河文化主题协作联盟为例   总被引：5，自引：1，他引：4  

沈山  沈正平  孙旭芳  马晓冬  安宇 《地理研究》2008,27(6):1444-1454

主题性旅游协作联盟是一种新型的旅游合作战略模式,其协作基础为相似的空间认知要素、现代化的信息技术支撑和物态化的整合营销品牌。在分析国内外20多个旅游协作联盟的基础上,从地域联系、主题类型、空间结构和组织形式等4个视角,总结了主题性旅游协作联盟的12种基本类型,指出协作的基础理论是注意力经济学、协作网络共生理论和旅游产业集群理论。选取江苏扬州至山东济宁段运河为研究区域,分析其文化资源和旅游发展状况,提出"千年运河,世纪风情"的运河文化主题,从组织体系、品牌营销、产品体系、保障机制、信息平台等5个方面进行主题性旅游协作联盟的构建。  相似文献   

A model describing the time course and variability in toxicity of hydrophobic chemicals to aquatic organisms     

Wang?XiulinEmail author  Shan?Baotian  GE?Ming  Zhang?Lei  Zhu?Chenjian  Han?Xiurong 《中国海洋大学学报(英文版)》2002,1(1):71-79

The growth of Chlorella marine, Nannochloris oculate, Pyramimonaos sp., Platymonas subcordiformis and Phaeodactylum tricornutum exposed to chlorobenzene, 1,2-dichlorobenzene, 1,2,3,4-tetrachlorobenzene and pentachlorobenzene was tested. The Boltzman equation was used to describe organism growth. The time course for uptake of hydrophobic organic chemicals (HOCs) by aquatic organisms was expressed by incorporating growth and, if desired, the effect of metabolism into the HOC bioconcentration process. The probability of any given concentration of HOCs in the organisms causing a specified toxic endpoint was expressed with a modified Weibull distribution function. The combined bioconcentration and probability equations were tested with data for time course of incubation of algae exposed to chlorinated benzenes (CBs). A set of parameters, including the uptake rate constant k ₁, the elimination rate constant k ₂ and thereafter the bioconcentration factor on a dry weight basis, BCF _D, the critical HOC concentration in the organism resulting in a specified toxic endpoint, C _A ^* , and the spread factor, S, could be obtained by fitting only experimental data for percent growth inhibition(%)-time-CB exposure concentration. The average coefficients of variation within CBs were 15.2% for BCF _D, 21.0% for k ₁, 18.3% for k ₂, 8.1% for C _A ^* and 9.7% for S. The variability in toxicity (such as EC₁₀, EC₅₀, EC₉₀) derived from the model equations agreed well with those experimentally observed.  相似文献   

辽宁地震信息网Web页面制作方法     

王海英  单德华等 《东北地震研究》1999,15(4):60-64

阐述了辽宁地震信息网络Web页面设计风格和Web页面制作过程中的主要技术难点及其解决方法,对更好地创建Web页面,使网页制作从文字界面向图文并茂、生动活泼的图形和多媒体界面发展有一定的借鉴作用。  相似文献