基于基态修正模型的地籍时空数据库设计与实现   总被引：10，自引：0，他引：10  

王华敏  陈继祥  于雷易 《测绘信息与工程》2003,28(3):9-11

通过分析面向对象的时态GIS，依据地藉管理的时空内聚性及空间／属性内聚性，设计了基于基态修正模型的地藉时空数据库，实现了对地藉变更的任意时刻与任意时段的历史数据查询与分析。  相似文献   

磁通门磁变仪状态函数对电磁转换函数测定值的影响     

朱兆才 《东北地震研究》2003,19(1):72-75

分析了磁通门磁变仪定向状态函数对电磁转换函数测定位的影响，指出在利用转换函数分析预报地震时，定向状态函数的影响不容忽视。  相似文献   

影响北极地区迅速变化的一些关键过程研究   总被引：6，自引：3，他引：6       下载免费PDF全文

陈立奇  赵进平  卞林根  陈波  陈敏  高爱国  高众勇 《极地研究》2003,15(4):283-302

最近研究证明 ,近半个世纪来 ,北极地区正在发生迅速变化。部分地区温度上升了 2- 3°C ,北冰洋海冰退缩 5 %,中心地区海冰厚度变薄 ,海面压力降低 ,中上层水淡化和变暖 ,吸收CO2 能力增加 ,臭氧耗损和紫外线辐射增强。中国于 1 999年开展了“中国首次北极科学考察” ,在楚科奇海、加拿大海盆、白令海以及临近海域开展了海冰气相互作用的多学科综合考察 ,对北极的区域特征及其在全球变化中的作用研究获得一些新的认识。观测到加拿大海盆中层水持续增暖的现象 ,揭示了西北冰洋与白令海水体交换的途径和次表层暖水结构 ,发现了加拿大海盆是北冰洋河水的主要储存区。利用联合冰站观测数据 ,模拟了北冰洋夏季大气边界层结构和下垫面能量平衡的变化特征 ,定量给出了北冰洋夏季海 /气和冰 /气之间湍流通量和边界层参数的差异。海 /气CO2 的通量观测表明 ,考察区的大部分海域均为大气CO2 汇区 ;西北冰洋海冰区具有较高的生物泵运转效率 ,楚科奇海陆架是一个高效的有机碳“汇”区 ,寒冷水体中微生物活动并未受到明显抑制。沉积物的地球化学过程研究表明 ,海底表层沉积物中碘含量存在着由低纬度到高纬度增加趋势 ,北极地区可能是碘的汇区 ,碘可作为极区古海洋中的地球化学元素变化的重要指标。楚科奇海、白令海  相似文献   

Finite element modelling of frictional instability between deformable rocks   总被引：1，自引：0，他引：1  

H. L. Xing  A. Makinouchi 《国际地质力学数值与分析法杂志》2003,27(12):1005-1025

Earthquakes are recognized as resulting from a stick–slip frictional instability along faults. Based on the node‐to‐point contact element strategy (an arbitrarily shaped contact element strategy applied with the static‐explicit algorithm for modelling non‐linear frictional contact problems proposed by authors), a finite element code for modelling the 3‐D non‐linear friction contact between deformable bodies has been developed and extended here to analyse the non‐linear stick–slip frictional instability between deformable rocks with a rate‐ and state‐dependent friction law. A typical fault bend model is taken as an application example to be analysed here. The variations of the normal contact force, the frictional force, the transition of stick–slip instable state and the related relative slip velocity along the fault between the deformable rocks and the stress evolution in the total bodies during the different stages are investigated, respectively. The calculated results demonstrate the usefulness of this code for simulating the non‐linear frictional instability between deformable rocks. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

The state and the regulation of biodiversity: International biopolitics and the case of Mexico     

Ulrich Brand  Christoph Görg 《Geoforum》2003,34(2):221-233

In this article, the evolving forms of biodiversity politics are examined in the light of regulation theory and in the tradition of materialistic state theory (Gramsci, Poulantzas, etc.). Biodiversity politics is not so much oriented toward the conservation of biodiversity as towards the creation of a stable political-institutional framework for its commercialization. In this contested and contradictory process, the nation state plays a crucial role. After a few remarks on the theoretical assumptions, some basic elements of the international regulation system of genetic resources are presented. The main topics of international biodiversity politics beside conservation are: access to biodiversity and its genetic resources, benefit sharing from its use and intellectual property rights. A major problem of this system is the relationship between varying negotiation processes in different fora. Another closely connected problem is the contradictory relationship between different regulatory levels at different spatial scales (international, regional, local). These contradictions are analyzed for the case of Mexico. Central issues of Mexican biodiversity politics, and the different actors, forces and interests are outlined and discussed against our initial theoretical reflections. Bioprospecting projects in the south of Mexico have raised questions of legal and legitimate forms of access, which have generated growing concern and significant disputes within Mexico. Finally, some conclusions are drawn, binding together the theoretical with the empirical results of our study.  相似文献   

俯冲带深部应力场的二维粘弹性有限元数值模拟   总被引：4，自引：1，他引：4  

刘亚静  叶国扬  毛兴华  宁杰远 《地震学报》2002,24(3):285-292

基于粘弹性平面应变有限元数值模拟方法，研究了俯冲带深部的应力场特征．当根据Karato等的研究结果给出俯冲板块的粘度结构时，橄榄石——尖晶石相变界面以下中心低粘区两侧出现应力集中区，而且其主压应力方向沿俯冲方向走向．其特征与已有的深源地震主压应力方向沿俯冲方向及深源地震有两个条带的地震观测结果相吻合．相变过渡区因矿物更小的颗粒粒度而导致的更小的等效粘度对俯冲带深部应力场的影响不大；存在和不存在亚稳态橄榄石楔的情况下，橄榄石——尖晶石相变过渡区附近都有最大剪应力的最大值出现，而其主压应力方向有垂直于橄榄石——尖晶石相变过渡区走向的趋势，尚与地震观测资料不符．   相似文献   

IAP/LASG全球海-陆-气耦合系统模式的纬向平均大气气候态分析   总被引：1，自引：0，他引：1  

张韬  郭裕福  吴国雄 《大气科学进展》2002,19(6):1091-1102

分海洋和陆地两种情况来讨论IAP／LASG全球海－陆－气耦合系统模式（GOALS）四个版本的结果，并与观测资料进行对比分析，一些重要的大气变量包括表面空气温度，海平面气压和降水率用来评估GOALS模式模拟当代气候和气候变率的能力，总的来说，GOALS模式的四个版本都能够合理地再现观测到的平均气候态和季节变化的主要特征，同时评估也揭示了模式的一些缺陷，可以清楚地看到模拟的全球平均海平面气压的主要误差是在陆地上，陆地上表面空气温度模拟偏高主要是由于陆南过程的影响，值得注意的是降水率模拟偏低主要是在海洋上，而中高纬的陆地降水在北半球冬天却比观测偏高。通过模式不同版本之间的相互比较研究，可以发现模式中太阳辐射日变化物理过程的引入明显地改善了表面空气温度的模拟，尤其是在中低纬度的陆地上，太阳辐射日变化的引入对热带陆地的降水和中高纬度的冬季降水也有较大改进。而且，由于使用了逐日通量距平交换方案（DFA），GOALS模式新版本模拟的海洋上的温度变率在中低纬度有了改善。比较观测和模拟的年平均表面空气温度的标准度，可以发现GOALS模式四个版本都低估了海洋和陆地上的温度变率，中还对影响观测和模拟温度变率差异的可能原因进行了探讨。  相似文献   

Mantle Redox State Evolution in Eastern China and Its Implications     

LI Jianping  WANG Jian Guangzhou Institute of Geochemistry  Chinese Academy of Sciences  Guangzhou Liu Shuchun Zhu Xiling 《《地质学报》英文版》2002,76(2):238-248

Using the secondary spinel standard, the authors have precisely measured the Fe3+/∑ Fe values of spinels in mantle xenoliths from Cenozoic basalts in eastern China, and estimated the oxygen fugacities recorded by 63 mantle xenoliths through olivine-orthopyroxene-spinel oxygen barometry. The results indicate that the oxygen fugacities of the lithospheric mantle in eastern China are higher in the south than in the north. Among them, the oxygen fugacity of the North China craton lithospheric mantle is the lowest, similar to that of the oceanic mantle, while that of Northeast and South China are the same as that of the global continental mantle. The variations of mantle redox state in eastern China are mainly controlled by the C-O-H fluids derived from the asthenospheric mantle. According to the mantle oxidation state, it can be concluded that the C-O-H fluids in the lithospheric mantle of eastern China consist mainly of CO2 and minor H2O, but CH4-rich fluids should come from the asthenosphere where the ox  相似文献   

西安市街道灰尘中铬、镉、铅赋存状态及环境效应   总被引：8，自引：0，他引：8  

田晖 《城市地质》2002,14(2):34-39

本文通过对街道灰尘中铬、镉、铅三种元素赋存状态研究、铬、铅在街道灰尘中以残渣态为主，镉以有机质结合态为主。虽然铬、铅、镉存在形式稍有差异，但其在街道灰尘中主要以矿物质的形态存在，说明其比较稳定，不易迁移转化，对环境的危害比较持久。在治理措施上应有早遏止微量元素向环境中排放，以免其与灰尘发生相互作用对环境造成长期的危害。  相似文献   

2-D elastic FEM simulation on stress state in the deep part of a subducted slab   总被引：1，自引：1，他引：1  

毛兴华  刘亚静  叶国扬  宁杰远 《地震学报(英文版)》2002,15(3):294-300

Introduction Geoscientists concern the explanation of deep focus earthquakes greatly. As a great progress in understanding the formation of deep focus earthquakes, Sung and Burns (1976a, b) proposed that olivine could exist in transition zone in metastable form in the core of some cold subducting slabs, which have got supports from laboratory studies (Rubie, Ross, 1994). Iidaka and Suetsugu (1992) used the seismic data recorded by the dense seismograph networks in Japan to study the travelti…  相似文献