干旱区水资源对城市化约束强度的综合评价模型   总被引：7，自引：3，他引：4  

鲍超  方创琳 《地理学报(英文版)》2009,19(3):273-286

Water has become a key restricting factor of the urbanization process in developing arid areas. Based on qualitative and quantitative methods, we constructed an integrated indicator system to assess the status of water resources and urbanization system in arid area, and established an AHP model reformed by entropy technology to evaluate the temporal and spatial variations of water resources constraint intensity on urbanization. This model is applied to the Hexi Corridor, a typical arid area in NW China. Results show that, water resources constraint intensity on urbanization in the Hexi Corridor is bigger in the east and smaller in the west. It has changed from the less strong constraint type into the strong constraint type from 1985 to 2005, yet it decreased appreciably in recent years. At present, most areas in the Hexi Corridor belong to the less strong or strong constraint type. Through rational adjustment of water resources and urbanization system, the Hexi Corridor can still promote water resources sustainable utilization and accelerate the urbanization process. This study suggests that the integrated assessment model of water resources constraint intensity on urbanization is an effective method to analyze the conflicts between water resources and urbanization system in arid area. Foundation: Knowledge Innovation Project of the Chinese Academy of Sciences, No.KZCX2-YW-307-02; China Postdoctoral Science Foundation; K. C. Wong Education Foundation, Hong Kong Author: Bao Chao (1978–), Ph.D, specialized in urbanization and water sustainable utilization.  相似文献   

中国耕地利用集约度结构变化及其区域差异   总被引：25，自引：6，他引：19  

陈瑜琦  李秀彬  田玉军  谈明洪 《地理学报(英文版)》2009,19(5):545-556

Based on the data from the Cost-benefit Data of Farm Produce and the China Agricultural Yearbook, this paper divided the intensity of cultivated land use into labor intensity and capital intensity, and then analyzed their temporal and spatial change at both national and provincial levels between 1980 and 2006. The results showed that: (1) At the national level, labor intensity on food produce decreased from 398.5 day/ha in 1980 to 130.25 day/ha in 2006; and a continuous decrease with a steep decline between 1980 and 1986, a slower decline from 1987 to 1996, and another steep decline from 1997 to 2006. On the contrary, capital intensity shows an increasing trend since 1980. As to the internal composition of capital intensity, the proportion of seed, chemical fertilizer and pesticide input decreased from 90.36% to 73.44% and the proportion of machinery increased from 9.64% to 26.56%. The less emphasis on yield-increasing input and more emphasis on labor-saving input are the main reasons for a slow increase of yield per unit area after 1996. (2) At the provincial level, the developed areas have lower labor intensity and higher capital intensity. The less developed ones have higher labor intensity but lower capital intensity. From the viewpoint of the internal composition of capital intensity, labor-saving input accounts for more proportion in the developed areas than that of other areas. The main reason is that in these developed areas, labor input has become a constraint factor in food production as more and more labors engaged in off-farm work. Farmers increase the labor-saving input for higher labor productivity. However, in the less developed areas, the major constraint is the shortage of capital; food production is still depending on labor and yield-increasing inputs.  相似文献   

Structural change of agricultural land use intensity and its regional disparity in China     

CHEN Yuqi  LI Xiubin  TIAN Yujun  TAN Minghong 《地理学报》2009,19(5):545-556

Based on the data from the Cost-benefit Data of Farm Produce and the China Agricultural Yearbook, this paper divided the intensity of cultivated land use into labor intensity and capital intensity, and then analyzed their temporal and spatial change at both national and provincial levels between 1980 and 2006. The results showed that: (1) At the national level, labor intensity on food produce decreased from 398.5 day/ha in 1980 to 130.25 day/ha in 2006; and a continuous decrease with a steep decline between 1980 and 1986, a slower decline from 1987 to 1996, and another steep decline from 1997 to 2006. On the contrary, capital intensity shows an increasing trend since 1980. As to the internal composition of capital intensity, the proportion of seed, chemical fertilizer and pesticide input decreased from 90.36% to 73.44% and the proportion of machinery increased from 9.64% to 26.56%. The less emphasis on yield-increasing input and more emphasis on labor-saving input are the main reasons for a slow increase of yield per unit area after 1996. (2) At the provincial level, the developed areas have lower labor intensity and higher capital intensity. The less developed ones have higher labor intensity but lower capital intensity. From the viewpoint of the internal composition of capital intensity, labor-saving input accounts for more proportion in the developed areas than that of other areas. The main reason is that in these developed areas, labor input has become a constraint factor in food production as more and more labors engaged in off-farm work. Farmers increase the labor-saving input for higher labor productivity. However, in the less developed areas, the major constraint is the shortage of capital; food production is still depending on labor and yield-increasing inputs.  相似文献   

地震导致山体变形破裂机制地质力学模拟试验研究          下载免费PDF全文

许向宁  王兰生 《地学前缘》2009,16(3):333-340

地震导致山体变形破裂是一个复杂的演化过程,文中通过一些典型实例的地质分析,总结归纳了高地震烈度区山体变形破裂失稳有一定代表性的倾外层状体斜坡滑坡型、高陡块(层)状体斜坡崩塌型、软弱基座体斜坡滑坡型等3种典型性地质力学模式。自主创新研制、设计、探索了一套振动条件下地质力学模拟试验的设备模型和方法,并对3种典型性地质力学模型进行机制模拟试验。通过变形破裂演化过程模拟再现试验,从中揭示出一些振动条件下变形破裂的典型迹象和重要证据,充分再现了典型地震失稳机制的形成条件、相关性因素以及演化规律,为进一步研究分析提供科学可靠的试验数据和证据。  相似文献   

An energy-based envelope function for the stochastic simulation of earthquake accelerograms     

P.J. Stafford  S. Sgobba  G.C. Marano 《Soil Dynamics and Earthquake Engineering》2009

An energy-based envelope function is developed for use in the stochastic simulation of earthquake ground motion. The envelope function is directly related to the Arias intensity of the ground motion as well to the manner in which this Arias intensity is built-up over time. It is shown that this build-up, represented by a Husid plot, can be very well modelled using a simple lognormal distribution. The proposed envelope makes use of parameters that are commonly available in seismic design situations, either following a deterministic scenario-type analysis or following a more comprehensive probabilistic seismic hazard analysis (PSHA), either in terms of Arias intensity or the more common spectral acceleration. The shape parameters of the envelope function are estimated following the calculation of the analytic envelopes for a large number of records from PEER Next Generation of Attenuation (NGA) database. The envelope may also be used to predict the distribution of peak ground acceleration values corresponding to an earthquake scenario. The distribution thus obtained is remarkably consistent with those of the recent NGA models.  相似文献   

Intensity measures for the seismic response of pile foundations     

Brendon A. Bradley  Misko CubrinovskiRajesh P. Dhakal  Gregory A. MacRae 《Soil Dynamics and Earthquake Engineering》2009

In this study the efficacy of various ground motion intensity measures for the seismic response of pile foundations embedded in liquefiable and non-liquefiable soils is investigated. A soil-pile-structure model consisting of a two-layer soil deposit with a single pile and a single degree-of-freedom superstructure is used in a parametric study to determine the salient features of the seismic response of the soil-pile-structure system. A suite of ground motion records scaled to various levels of intensity are used to investigate the full range of pile behaviour, from elastic response to failure. Various intensity measures are used to inspect their efficiency in predicting the seismic demand on the pile foundation for a given level of ground motion intensity. It is found that velocity-based intensity measures are the most efficient in predicting the pile response, which is measured in terms of maximum curvature or pile-head displacement. In particular, velocity spectrum intensity (VSI), which represents the integral of the pseudo-velocity spectrum over a wide period range, is found to be the most efficient intensity measure in predicting the seismic demands on the pile foundation. VSI is also found to be a sufficient intensity measure with respect to earthquake magnitude, source-to-site distance, and epsilon, and has a good predictability, thus making it a prime candidate for use in seismic response analysis of pile foundations.  相似文献   

基于地震动参数的结构易损性表达方法研究     

刘如山  胡少卿  邬玉斌  张美晶 《地震工程与工程振动》2009,29(6)

用贝塔分布函数对给定烈度下结构各个破坏等级的概率分布进行了破坏比概率密度的拟合,以地震动峰值作为地震动参数,根据烈度和加速度峰值的对应关系以对数插值方式计算了在任意一个峰值加速度下结构破坏比的倍塔概率密度分布及各个破坏等级的概率,从而使结构易损性的表达方式由烈度-震害等级构成的二维阶跃性易损性矩阵转化为由地震动参数-破坏比概率密度函数或地震动参数-各破坏等级的概率来表达的方式.试算结果表明,这种转化方法是可行的.本文为震害预测和地震经济损失估计提供参考.  相似文献   

Non‐structure‐specific intensity measure parameters and characteristic period of near‐fault ground motions     

Dixiong Yang  Jianwei Pan  Gang Li 《地震工程与结构动力学》2009,38(11):1257-1280

This paper focuses on the effects of long‐period pulse of near‐fault ground motions on the structural damage potential. Two sets of near‐fault ground motion records from Chi‐Chi, Taiwan earthquake and Northridge earthquake with and without distinct pulse are selected as the input, and the correlation analysis between 30 non‐structure‐specific intensity measure parameters and maximum inelastic displacements and energy responses (input energy and hysteretic energy) of bilinear single degree of freedom systems are conducted. Based on the frequency characteristic of near‐fault ground motions with remarkable long‐period components, two intensity indices are proposed, namely, the improved effective peak acceleration (IEPA) and improved effective peak velocity (IEPV). In addition a new characteristic period of these ground motions is defined based on IEPA and IEPV. Numerical results illustrate that the intensity measure parameters related to ground acceleration present the best correlation with the seismic responses for rigid systems; the velocity‐related and displacement‐related parameters are better for medium‐frequency systems and flexible systems, respectively. The correlation curves of near‐fault ground motions with velocity pulse differ from those of ground motions without pulse. Moreover, the improved parameters IEPA and IEPV of near‐fault impulsive ground motions enhance the performance of intensity measure of corresponding conventional parameters, i.e. EPA and EPV. The new characteristic period based on IEPA and IEPV can better reflect the frequency content of near‐fault ground motions. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

江西省及邻区地震动参数衰减关系          下载免费PDF全文

吕坚  俞言祥  汤兰荣  高建华  卢福水 《地震地质》2009,31(1):122-132

在利用江西省及邻区的地震烈度等震线资料建立该区地震烈度衰减关系的基础上,以美国西部为参考地区,转换得到了相应的水平向基岩峰值加速度与反应谱衰减关系,并与中国东部地区的地震动参数衰减关系进行了对比,其结果更加符合该区历史和近代地震震害分布的地域性特点,可进一步应用于地震安全性评价、震害预测、损失快速评估等研究  相似文献   

Water surface mapping from airborne laser scanning using signal intensity and elevation data     

Bernhard Höfle  Michael Vetter  Norbert Pfeifer  Gottfried Mandlburger  Johann Stötter 《地球表面变化过程与地形》2009,34(12):1635-1649

In recent years airborne laser scanning (ALS) evolved into a state‐of‐the‐art technology for topographic data acquisition. We present a novel, automatic method for water surface classification and delineation by combining the geometrical and signal intensity information provided by ALS. The reflection characteristics of water surfaces in the near‐infrared wavelength (1064 nm) of the ALS system along with the surface roughness information provide the basis for the differentiation between water and land areas. Water areas are characterized by a high number of laser shot dropouts and predominant low backscatter energy. In a preprocessing step, the recorded intensities are corrected for spherical loss and atmospheric attenuation, and the locations of laser shot dropouts are modeled. A seeded region growing segmentation, applied to the point cloud and the modeled dropouts, is used to detect potential water regions. Object‐based classification of the resulting segments determines the final separation of water and non‐water points. The water‐land‐boundary is defined by the central contour line of the transition zone between water and land points. We demonstrate that the proposed workflow succeeds for a regulated river (Inn, Austria) with smooth water surface as well as for a pro‐glacial braided river (Hintereisfernerbach, Austria). A multi‐temporal analysis over five years of the pro‐glacial river channel emphasizes the applicability of the developed method for different ALS systems and acquisition settings (e.g. point density). The validation, based on real time kinematic (RTK) global positioning system (GPS) field survey and a terrestrial orthophoto, indicate point cloud classification accuracy above 97% with 0·45 m planimetric accuracy (root mean square error) of the water–land boundary. This article shows the capability of ALS data for water surface mapping with a high degree of automation and accuracy. This provides valuable datasets for a number of applications in geomorphology, hydrology and hydraulics, such as monitoring of braided rivers, flood modeling and mapping. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献