An oases dynamics model and its application in the Manas oasis     

CHEN Zhengjiang  SHI Wenzhong  HUI Yanghe 《地理学报》2002,12(3):348-356

This study applies theories of systems and system dynamics to ecological economic systems in the oasis environment, with the intention of finding the basic characteristics of the oasis environment and its feedback structures. This study explores the inner mechanisms of economic development in the oasis environment and its relationship to policy variables. This model is applied to economic development in the Manas oasis of the Xinjiang Uygur Autonomous Region of China. System dynamics method starts from studying feedback structure within the system study and then searches for the best solution through identifying the right "policy point" and through model simulation in the computer. It embodies the cream of "systems cybernetics theory". This study is justified because the nature of the oasis system and the simulation results are scientifically sound and practically feasible.  相似文献   

新疆城市化过程及机制分析   总被引：17，自引：19，他引：17  

杨德刚  李秀萍  韩剑萍  张小雷 《干旱区地理》2003,26(1):50-56

城市人则城市化研究的核心问题。在分析新疆城市化现状特征的基础上，围绕新疆城市发展的阶段和过程，采用多因素的灰色关联分析和比较分析等手段，对新疆1978－2000年间城市化发展过程进行分析和探讨，寻求并探索新疆城市化发展的特征、水平和演化机制。研究结果发现各因素与城市化的关联度不仅在横向上存在着指标间的差异，在纵向上显示出1990－2000间各指标与城市化的相关性明显高于1978－1989年间，部分指标与城市化关系发生了负向变化。表明近20多年来新疆城市化稳定发展，城市化系统条件（农村和城市的控制性次系统及整个社会经济文化）有一定的提高，体现了系统各因素与城市化发展的同向性以及区域发展的合理趋势，但整体薄弱的社会经济基础是新疆城市化落后的根本原因，产业结构升级转换仍将是新疆城市化的主要动力。  相似文献   

基于RS与GIS的干旱区绿洲景观格局变化研究——以金塔绿洲为例   总被引：35，自引：17，他引：35  

马明国  王雪梅  角媛梅  陈贤章 《中国沙漠》2003,23(1):53-58

景观生态学是宏观生态研究的一个新领域。景观格局变化研究,是目前景观生态学的研究热点。利用遥感的手段获取试验区1990和2000年景观格局的基础数据,并利用GIS做分析的工具,计算出6个指标值,采用格网化的方法,将研究区域的景观斑块转化成5m×5m的格网,进行空间分析,计算得出了景观斑块的转移矩阵,为景观格局在空间上的变化分析打下基础。分析显示:①多样性、均匀性、优势度3个指标数值上有很大的相关性,只需考虑多样性;②绿洲景观格局的变化与水资源的变化密切相关;③绿洲有沙漠化的威胁;④城镇居民点用地扩展迅速,主要在未利用土地上发展,金塔绿洲内城镇居民区有城市化的趋势;⑤城镇居民点破碎化指标值未能真正体现其景观特性,当不考虑少数几个大的斑块时,能够得到较为理想的结果。  相似文献   

Slip-weakening distance in dynamic rupture of in-slab normal-faulting earthquakes   总被引：1，自引：0，他引：1  

Takeshi Mikumo  Yuji Yagi 《Geophysical Journal International》2003,155(2):443-455

  相似文献   

Habitat, occurrence and conservation of Saharo-Arabian-Turanian element Forsskaolea tenacissima L. in the Iberian Peninsula   总被引：1，自引：0，他引：1  

Javier Cabello  Domingo Alcaraz  Francisco Gmez-Mercado  Juan F. Mota  Javier Navarro  Julio Peas  Esther Gimnez 《Journal of Arid Environments》2003,53(4):491-500

The aim of this study is to assess the Iberian populations of Forsskaolea tenacissima L. according to its biogeographical interest, habitat, geographical range and conservation status. Results point out that they are restricted to gravel wadis of Tabernas Desert (SE Spain), are scarcely included in protected areas and represent historically isolated populations with relict behaviour. We also describe a new association, Senecioni-Forsskaoleetum tenacissimae. Conservation status of species is cause for concern and two conservation actions must be carried out. Firstly, protected areas should house Forsskaolea populations and secondly, phytosociological characterization of a community allows inventorying its habitat and directing conservation efforts to community level.  相似文献   

Eco-environment range in the source regions of the Yangtze and Yellow rivers     

DING Yongjian  YANG Jianping  LIU Shiyin  CHEN Rensheng  WANG Genxu  SHEN Yongping  WANG Jian  XIE Changwei  ZHANG Shiqing 《地理学报》2003,13(2):172-180

Based on geographical and hydrological extents delimited, four principles are identified, as the bases for delineating the ranges of the source regions of the Yangtze and Yellow rivers in the paper. According to the comprehensive analysis of topographical characteristics, climate conditions, vegetation distribution and hydrological features, the source region ranges for eco-environmental study are defined. The eastern boundary point is Dari hydrological station in the upper reach of the Yellow River. The watershed above Dari hydrological station is the source region of the Yellow River which drains an area of 4.49×104 km2. Natural environment is characterized by the major topographical types of plateau lakes and marshland, gentle landforms, alpine cold semi-arid climate, and steppe and meadow vegetation in the source region of the Yellow River. The eastern boundary point is the convergent site of the Nieqiaqu and the Tongtian River in the upstream of the Yangtze River. The watershed above the convergent site is the source region of the Yangtze River, with a watershed area of 12.24×104 km2. Hills and alpine plain topography, gentle terrain, alpine cold arid and semi-arid climate, and alpine cold grassland and meadow are natural conditions in the source region of the Yangtze River.  相似文献   

烃类物质微渗漏机制及垂向运移的数值模拟   总被引：2，自引：0，他引：2       下载免费PDF全文

肖伟  鲍征宇  黎华  李方林 《地质找矿论丛》2003,18(1):29-33

在前人烃类物质微渗漏机制研究基础上，建立了烃类物质微渗漏的概念模型，并且推导了烃类物质垂向运移的动力学模型。在动力学模型的基础上，通过数值模拟验证了烃类物质胶体气泡上升机制的合理性，并计算了不同情况下烃类物质垂向运移的平衡时间，进一步验证了烃类物质气泡上升机制满足运移速度快、流量少的特点。  相似文献   

川西及松辽南部油气微渗漏动力学模拟   总被引：3，自引：2，他引：3  

夏响华  陈银节  姚俊梅  朱怀平 《物探与化探》2003,27(6):458-461

选择川西孝泉-新场气田和松辽南部后五家户气田为研究区,采集14口井井中化探样品,测试热释烃、酸解烃、荧光等指标,进行了烃类垂向微运移的研究.由于岩石物性的影响,热释烃、荧光等指标显示不同程度的正向梯度,但酸解烃指标在油气田井中局部层段垂向分布特征显示负向梯度,或与其它化探指标没有相关关系.建立相应的微渗漏模型,并进行动力学模拟,模拟结果和实测资料较吻合.  相似文献   

考虑几何非线性的强夯流固动力耦合分析     

谢能刚  宋修广  王璐 《水文地质工程地质》2003,30(5):44-48

针对强夯法加固地基机理的流固动力耦合分析问题,本文考虑土体的几何非线性,建立土体非线性动力平衡方程和整体流固动力耦合方程,给出土体非线性动力平衡方程的迭代计算格式和流固动力耦合方程的解耦计算方法,并对一具体算例进行了数值分析,得到了地基位移、应力等在强夯作用下的变化规律和在空间上的分布特征,为精确模拟分析强夯加固机理提供了有效途径。  相似文献   

库尔勒数字地震台台基噪声分析   总被引：1，自引：0，他引：1  

张文来  郑黎明 《内陆地震》2003,17(4):343-347

选取库尔勒地震台FBS—3数字地震仪不同时段的无震记录资料，运用傅里叶变换对其台基噪声进行频谱分析，并计算台基的平均噪声水平及仪器的实际动态范围。库尔勒地震台数字地震仪台基噪声主要来自随机干扰，噪声频段相对稳定，噪声幅度随时段有所变化。观测系统实际动态范围符合数字地震仪架设的要求。  相似文献