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971.
Based on the questionnaire investigation, the authors make a comparative study on local residents‘ perception of tourism impacts in Xidi, Zhouzhuang and Jiuhua Mountain. The result shows that residents of the three places tend to have strong and consistent perception of its positive economic, socio-cultural and environmental impacts, but distinctly diverse ones of its negative impacts. Residents in Xidi and Zhouzhuang also have noticeable perception of its negative environmental impacts while those in Jiuhua Mountain have weaker perception of them.The research confirms the fact that residents are more liable to have positive perceptions at the early stage of the life cycle of the tourist places. The authors conclude that there exists a nonlinear relationship between residents‘ perception and tourism development stages, and that tourism socio-cultural impact may appear at an early stage of tourism development instead of being no universal.  相似文献   
972.
1城乡一体化建设与耕地保护和土地集约利用的关系(1)城乡一体化建设需要占用一定数量的耕地。改革开放以来,我国城乡一体化水平得到迅速提高,城市发展进入最快时期。据统计,2006年我国城市人口约4.1亿,城乡一体化程度大约为30.4%。据专家预测,到2050年,城乡一体化水平将提高到7  相似文献   
973.
A fuzzy logic controller for ship path control in restricted waters is developed and evaluated. The controller uses inputs of heading, yaw rate, and lateral offset from the nominal track to produce a commanded rudder angle. Input variable fuzzification, fuzzy associative memory rules, and output set defuzzification are described. Two maneuvering situations are evaluated: track keeping along a specified path where linearized regulator control is valid; and larger maneuvers onto a specified path where nonlinear modeling and control are required. For the track keeping assessment, the controller is benchmarked against a conventional linear quadratic Gaussian (LQG) optimal controller and Kalman filter control system. The Kalman filter is used to produce the input state variable estimates for the fuzzy controller as well. An initial startup transient and regulator control performance with an external hydrodynamic disturbance are evaluated using linear model simulations of a crude oil tanker. A fully nonlinear maneuvering model for a smaller product tanker is used to assess the larger maneuvers  相似文献   
974.
北京市区杂填土地基处理技术综述   总被引:2,自引:0,他引:2  
北京市区存在许多杂填土回填地基,主要是人为挖沙等原因形成。该部分地基回填成分复杂,既有建筑垃圾、工业垃圾和生活垃圾,又有几者的混合,而且此种地基成层薄厚不一、具有湿陷性和负摩阻力、均匀性差、承载力低、压缩性高、不确定性成分大且无规律性,所以此种地基必须根据实际情况综合确定经济、适合和可靠的优化处理方案,进行地基处理后才能作为建(构)筑物地基。结合西南四环珠江绿苑工程,论述北京市区杂填土地基处理组合型(综合)技术,并通过试验结果和沉降观测资料分析多种地基处理技术相互结合在高层建筑中应用的效果,并得出结论。  相似文献   
975.
欧亚大陆及边缘海岩石圈的结构特性   总被引:2,自引:0,他引:2  
从地球层块结构的研究思路出发,运用构造解析的理论和方法,对东亚及西太平洋地区人工地震测深和天然地震面波层析成像进行构造解析,发现岩石圈中下部存在形态各异、大小不等的高速块体,结合地质学、地球化学及其他地球物理学标志的综合研究将其称为幔块构造,高速块体或幔块构造是控制东亚西太平洋岩石圈构造格局和岩石圈表层构造变形最基本条件之一。在系统研究该区岩石圈高速块体或幔块构造三维几何结构基础上,建立起东亚西太平洋岩石圈八种三维几何结构型式:克拉通陆根状结构、高原陆根状结构、造山带楔状结构、碎块状结构、香肠状结构、哑铃状结构、藕节状结构和板状结构,以及岩石圈形成与构造演化四种构造类型:克拉通型岩石圈、增厚型岩石圈、减薄型岩石圈和大洋型岩石圈。文章在详细论述岩石圈各结构构造类基本特征的基础上,认为全球最大的青藏高原具有增厚型岩石圈特性,存在大陆根,并且大陆根正在增厚过程中;地震层析成像显示,研究区存在全球最大的东亚大陆巨型裂谷体系,具有减薄型岩石圈特性,新生代晚期东亚大陆巨型裂谷体系被西太平洋沟弧盆体系叠加与改造。根据岩石圈三维结构型式,探讨了岩石圈形成机制与演化模式,东亚大陆边缘岩石圈大规模伸展拆沉减薄作用以及软流圈和地幔物质上涌加热作用与青藏高原岩石圈大规模俯冲碰撞?入增厚作用是东亚大陆及边缘海晚中生代以来地幔动力学最基本的表现型式,从而形成全球最大的青藏高原和全球最大的东亚大陆巨型裂谷体系。  相似文献   
976.
基于ArcEngine的三维地形可视化系统的研究与开发   总被引:1,自引:0,他引:1  
ArcGIS Engine是ESRI公司在ArcGIS 9.O版本中发布的一个面向开发人员的产品,主要用来构建桌面的GIS应用.本文阐述了建立地形三维可视化系统的方法、技术途径及其关键技术,基于ArcEngine平台开发了一套三维地形可视化软件,实现了三维浏览、信息查询、地形分析等功能.  相似文献   
977.
Tele-seismic coseismic well temperature changes and their interpretation   总被引:1,自引:0,他引:1  
Coseismic water level oscillation and correlated deep water temperature changes have been observed in a water well at Tangshan City by high sensitivity measurement. Amount of water temperature changes depend on ampli-tude of water level oscillation. Coseismic water temperatures always decrease as water level oscillates, drop of temperature ranges from 0.001 °C to 0.01 °C corresponding to amplitude of water level oscillation from several centimeters to about one meter. Temperatures usually recover one to several hours after the oscillation. We suggest that the temperature drop is produced by dispersive transfer of heat as the water oscillates, and follow-up thermal conduction makes temperature recovery. Our finite element calculations support quantitatively the idea. High ac-curacy measurements of water temperature at different depths in the future may test our interpretation.  相似文献   
978.
A major slip and thrust belt within the eastern Jiaodong Peninsula is located at the eastern terminal of the Qinling-Dabie-Sulu orogenic belt between the Sino-Korea Block and Yangtze Block. Although a lot of isotope chronologic data have been obtained regionally, little structural chronological research has been conducted in this region and this paper corrects that. Syn-deformational minerals were system-atically selected from samples of the NE-ENE trending transpressional shear zones and transpres-sional nappes and carefully analysed using 40Ar/39Ar methods. Two tectonic events were defined with the first event resulting from early movement of transpressional nappes around 190 Ma ago. This ac-cords with the period of syn-orogenic sinistral slip of the Tan-Lu faults and clockwise shear in the Eastern Qinling-Tongbaishan part of the Qinling-Dabie-Sulu orogenic belt. The second event involved strikeslip thrust movement of deep shear zones between 130Ma and 120Ma. This resulted from the onset of Mesozoic tectonic conversion in the eastern Jiaodong Peninsula. The sinistral strikeslip-thrusting in Jiaodong Peninsula and the extensional tectonism (toward ESE) in Liaodong Peninsula probably resulted in the clockwise rotation of Korea Peninsula in late Mesozoic.  相似文献   
979.
As the third largest country in the world, China has highly variable environmental condition and ecological pattern in both space and time. Quantification of the spatial-temporal pattern and dynamic of terrestrial ecosystem carbon cycle in China is of great significance to regional and global carbon budget. In this study, we used a high-resolution climate database and an improved ecosystem process-based model to quantify spatio-temporal pattern and dynamic of net ecosystem productivity (NEP) in China and its responses to climate change during 1981 to 2000. The results showed that NEP increased from north to south and from northeast to southwest. Positive NEP (carbon sinks) occurred in the west of Southwest China, southeastern Tibet, Sanjiang Plain, Da Hinggan Mountains and the mid-west of North China. Negative NEP (carbon sources) were mainly found in Central China, the south of Southwest China, the north of Xinjiang, west and north of Inner Mongolia, and parts of North China. From the 1980s to 1990s, the increasing trend of NEP occurred in the middle of Northeast China Plain and the Loess Plateau and decreasing trends mainly occurred in a greater part of Central China. In the study period, natural forests had minimal carbon uptake, while grassland and shrublands accounted for nearly three fourths of the total carbon terrestrial uptakes in China during 1981–2000. Supported by the Ministry of Science and Technology of China (G2002CB412507), the Major Program of the National Natural Science Foundation of China (Grant No.30590384), the “Hundred Talent” Program of the Chinese Academy of Sciences, and K C WONE Education Foundation  相似文献   
980.
中国大陆黑碳气溶胶排放清单   总被引:1,自引:0,他引:1  
The detailed high-resolution emission inventory of black carbon (BC) from China in the year 2000 was calculated. The latest fuel consumption data including fossil and biomass fuels, and socio-economic statistics used were obtained from government agencies, mostly at the county level, and some new emission factors (Efs) from local measurements were also used. National and regional summaries of emissions were presented at 0.2°×0.2°resolution. Total BC emission was 1499.4 Gg in 2000, mainly due to the burning of coal and biomass. The BC emission estimated here is higher than those in previous studies, mainly because the emissions from coal burning by rural industries and residences were previously underestimated. More BC aerosols were emitted from eastern China than western China. A strong seasonal dependence was observed for BC emissions, with peaks in January and December and low emissions in July and August; and this seasonality is mainly due to patterns in residential heating and the open burning of crop residues.  相似文献   
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