Geologic site characterization for deep nuclear waste disposal in fractured rock based on 3D data visualization     

S. A. Tirn  P. Askling  S. Wnstedt 《Engineering Geology》1999,52(3-4):319-346

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Atmospheric oxidation of the pyritic waste rock in Maardu, Estonia. 1 field study and modelling     

E. Puura  I. Neretnieks  K. Kirsimäe 《Environmental Geology》1999,39(1):1-19

 A field survey and modelling of the oxidation and carbonate buffering reactions inside the alum-shale-containing waste rock dumps located in Maardu, Estonia, was accomplished. In the slope areas, the shale has been altered at high temperatures due to the spontaneous combustion and the pyritic acidity has been eliminated through migration of SO_x gases out from the dump. In the central parts of the waste rock plateaus, low temperature pyrite oxidation fronts develop towards the dump depth and towards the centres of individual shale lumps. The main secondary phases precipitating in the weathering profile are gypsum, ferric oxyhydroxide, K-jarosite and smectite. The respective field data made it possible to calibrate the two-stage oxygen diffusion model and the characteristic pyrite oxidation rate 0.06–0.08 mol of pyrite reacted per kg of available water (pyrox/H₂O value) was estimated to describe the first tens of years of dump performance. The model is capable to compare different shale disposal strategies that are illustrated with two case scenarios. The buffering of sulphuric acid by Mg-calcite appears to be an incongruent reaction with gypsum precipitating that leads to the build-up of the high Mg/Ca ratio in the leachate. Application of the Mg/Ca method estimates the pyrox/H₂O value in the range of 0.05–0.14 mol/kg. Received: 26 January 1999 · Accepted: 23. February 1999  相似文献   

Electric field effects on ionospheric and thermospheric parameters above the EISCAT station for summer conditions     

V. V. Klimenko  Yu. N. Korenkov  M. Förster 《Annales Geophysicae》1998,16(10):1200-1211

Numerical calculations of the thermospheric and ionospheric parameters above EISCAT are presented for quiet geomagnetic conditions in summer. The Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) was used. The numerical results were obtained both with a self-consistent calculation of the electric fields of magnetospheric and dynamo-action origin and with the magnetospheric electric fields only. It was found that the dynamo-electric field has some effect on the ionospheric convection pattern during quiet geomagnetic conditions. It has a marked effect mainly on the zonal neutral wind component above EISCAT (±20m/s at 140 km altitude). We have studied the effects of various field-aligned current (FAC) distributions on thermosphere/ionosphere parameters and we show that a qualitative agreement can be obtained with region-I and -II FAC zones at 75° and 65° geomagnetic latitude, respectively. The maximum FAC intensities have been assumed at 03–21 MLT for both regions with peak values of 2.5 × 10^–7 Am^–2 (region I) and 1.25 × 10^–7 A m^–2 (region II). These results are in agreement with statistical potential distribution and FAC models constructed by use of EISCAT data. The lack of decreased electron density in the night-time sector as observed by the EISCAT radar was found to be due to the spatial distribution of ionospheric convection resulting from electric fields of magnetospheric origin.  相似文献   

多粒度时空对象动态行为表达模型与方法研究     

曾梦熊  华一新  张江水  曹一冰  张政 《地球信息科学学报》2021,23(1):104-112

对具有动态变化特征的空间实体的描述,除了表达其内在属性外,还应包括动态行为。传统GIS把空间对象内在属性和动态行为分开建模本质上是一种基于地图的静态建模思想,而多粒度时空对象把行为能力作为对象的固有属性,是区别于其它对象的一个重要特征,使得全空间信息系统能够描述具有认知和行为能力的“活”的地理实体。本文针对具有规则化动态变化特征的时空实体的描述与表达,从多粒度时空对象的角度,阐述了多粒度时空对象动态行为的表达思路,提出了多粒度时空对象个体和对象世界的动态行为表达模型,为全面认识和表达空间对象动态变化提供了新的视角。针对动态行为多属性交错改变、多对象复杂联动、多过程动态自主的特点,为开展多粒度时空对象动态行为实际建模,本文归纳了动态行为改变内在属性的4种不同方式,并分别基于动力学、规则、数据挖掘和智能体4个方面对动态行为的表达方法进行了探讨。最后,结合实际应用进行了实证分析,结果表明对空间实体内在属性和动态行为一体建模,不再需要设计额外的数据模型,行为与对象不再分离;采用统一的动态行为表达模型,行为不仅与对象是解耦的,而且是通用的、可继承和复用的;对象不同行为的组合,可以描述空间实体复杂的动态变化的过程,为全空间信息系统中对象行为建模提供了有益经验和借鉴。  相似文献   

Geometrical characteristics of phase and group velocity surfaces in anisotropic media     

Alexey Stovas  Yuriy Roganov  Vyacheslav Roganov 《Geophysical Prospecting》2021,69(1):53-69

The phase and group velocity surfaces are essential for wave propagation in anisotropic media. These surfaces have certain features that, especially, for shear waves result in complications for modelling and inversion of recorded wavefields. To analyse wave propagation in an anisotropic model, it is important to identify these features in both the phase and group domains. We propose few characteristics for this analysis: the energy flux angle, decomposed in the polar and azimuth angle correction angles and enhancement factor, which is able to characterize both singularity points and triplication zones. The very simple equation that controls the triplications is derived in the phase domain. The proposed characteristics are illustrated for elastic and acoustic anisotropic models of different symmetry classes.  相似文献   

基于Agent和CA的城市土地利用变化研究   总被引：12，自引：1，他引：11  

杨青生  黎夏  刘小平 《地球信息科学学报》2005,7(2):78-81,93

分析了元胞自动机在土地利用变化研究的基础上,将Agent引进元胞自动机模型中,在元胞自动机模拟土地利用变化自然性、连续性规律的基础上,将Agent的人为性、不确定性加入到模型模拟中,对CA模型中以随机数体现的不确定性通过Agent给予地理意义的解释,并以城市郊区--樟木头镇为例,对1988-1993年间城市用地变化进行了模拟研究,得到了良好的模拟精度,模拟结果符合土地利用变化的自然性、人文性特征。  相似文献   

主动式服务在态势图中的作用     

李永红  李彦 《测绘与空间地理信息》2005,28(6):5-7

态势图是伴随着地图、GIS和传播学的发展而诞生的,本文介绍了主动式服务、态势图的概念及主动式服务在态势图应用中的必要性,并介绍了元数据、可视化技术、分布式数据管理技术及安全传输机制在实现主动式态势图服务中的作用和主要研究内容。  相似文献   

网格GIS数据信息发布的关键技术   总被引：6，自引：1，他引：5  

孙庆辉骆剑承  周成虎蔡少华  陈秋晓郑江沈占锋  明东萍 《地球信息科学学报》2004,6(1):22-27

网格GIS数据信息发布是通过网格计算环境发布存储在数据库中的信息,是实现网格GIS的关键技术之一。网格GIS数据信息发布的特点是其发布方法的通用性、高效性、高自主性、易实现性以及软件的复用性。在传统的WebGIS数据信息发布中,常用的CGI、API、JDBC、ASP、JSP等方法在实现网格GIS数据信息发布过程中均存在局限性。软件Agent技术以及中间件技术为解决网格GIS数据信息发布提供了新的技术保障,本文针对网格GIS数据信息发布的要求和特点,讨论了利用Agent和中间件来实现网格GIS数据信息发布,利用Agent的思路和方法对传统的方法封装成数据信息发布中间件,从而用来进行网格GIS数据信息发布。  相似文献   

On the influence of physical parameterisations and domains configuration in the simulation of an extreme precipitation event     

《Dynamics of Atmospheres and Oceans》2014

At daybreak and late morning of 18th of February 2008 Lisbon and Setúbal have been under the influence of a heavy rain event. This period was simulated by two operational WRF model set ups running for Portugal at the University of Aveiro in two different horizontal and vertical resolution and physical parameterisations. These two model configurations were tested for the described precipitation event in terms of microphysics and cumulus parameterisation and also in their domain configuration setup. Results suggest that the combination of cumulus and microphysics schemes is very important in the prediction of the amounts of precipitation. A small change in domain resolution has more impact in the spatial patterns of precipitation rather than in the amounts predicted.  相似文献   

Tide-induced flow signature in rip currents on a meso-macrotidal beach     

《Ocean Modelling》2014

On rip-channelled beaches, intense rip currents are driven by waves due to alongshore variations in breaking-induced wave energy dissipation. This study addresses for the first time the potential development of tidal currents superimposed onto the wave-driven circulation. This phenomenon is observed on a rip-channelled meso-macrotidal beach (Biscarrosse, SW France). Field measurements show 20 to 45% stronger mean rip velocities during ebb than during flood. Numerical experiments reveal that this asymmetry is the signature of tidal currents developing over the rip channel morphology. This asymmetry is found to increase roughly linearly with increasing tidal range. These results are significant to beach safety and lifeguarding and stimulate further numerical exercises.  相似文献