基于卫－卫跟踪观测技术利用能量守恒法恢复地球重力场的数值模拟研究   总被引：16，自引：5，他引：16       下载免费PDF全文

郑伟  邵成刚  罗俊  许厚泽 《地球物理学报》2006,49(3):712-717

根据卫－卫跟踪观测技术的测量原理，基于能量守恒法建立了一种新的双星相互跟踪和三星相互跟踪的卫星观测方程. 通过数值模拟，采用预处理共轭梯度法恢复120阶地球重力场. 模拟结果表明：第一，双星相互跟踪恢复地球重力场的精度和美国喷气动力实验室公布的EIGEN GRACE02S的结果相符合；第二，三星相互跟踪恢复地球重力场的精度较双星提高约2倍.  相似文献   

Improved Representation of Land-surface Heterogeneity in a Non-hydrostatic Numerical Weather Prediction Model   总被引：2，自引：1，他引：2  

Felix Ament  Clemens Simmer 《Boundary-Layer Meteorology》2006,121(1):153-174

This study focuses on the relevance of accurate surface parameters, in particular soil moisture, and of parameterizations for heterogeneous land surfaces, for the prediction of sensible and latent heat fluxes by a mesoscale weather forecast model with horizontal grid resolution of 7 km. The analysis is based on model integrations for a 30-day period, which are compared both to flux measurements obtained from the LITFASS-2003 field experiment and to high-resolution-model (1-km grid spacing) results. At first, the relevance of improved parameter sets and input data compared to usual operational practice for an accurate prediction of near-surface fluxes is shown and discussed. It is demonstrated that an observation-based land-surface assimilation scheme leads to an improved soil moisture analysis, which is shown to be essential for the realistic simulation of surface fluxes. Secondly, the implementation of two efficient parameterization strategies for subgrid-scale variability of the surface, the mosaic and the tile approach, is presented. Using these methods, the simulations are in better agreement with measurements than simulations with simple aggregation methods that use effective surface parameters. Integrations with the mosaic approach reproduce high resolution simulations very well and more accurately than simulations with the tile method. Finally, the high resolution simulations are analyzed to justify and discuss the approximations underlying both methods.  相似文献   

应用泉水均衡法分析四川省兴文县新坝水库岩溶渗漏问题     

董淑乾  蒋海云  许模 《地质灾害与环境保护》2006,17(1):69-73

岩溶地区水库渗漏是碳酸盐岩地区兴建水利枢纽的主要工程地质问题之一,尤其是在可溶岩广布、岩溶发育强烈、地形复杂地区。拟建兴文县新坝水库地处岩溶地区,存在岩溶渗漏的可能性。通过对该水库库区地质概况、岩溶水系统进行分析研究,论证了水库潜在的三条岩溶渗漏途径均不会发生渗漏;并利用库区降雨量与泉流量进行水均衡计算,计算结果进一步论证了该水库不存在岩溶渗漏问题。  相似文献   

基于数字地价模型的地价监测点配置研究   总被引：1，自引：0，他引：1  

胡石元  李德仁  刘耀林 《武汉大学学报(信息科学版)》2007,32(9):838-841

从数字地价模型的建立、格网数字地价模型向TIN转化、TIN节点与宗地图层叠加拟合完成地价监测点的定位配置、结合市场比较法的监测点地价更新、TIN数字地价模型更新等几个方面详细阐述了数字地价模型运用于地价监测点配置的具体方法。并将这一配置模式与以标准宗地为载体的配置模式进行了比较分析。  相似文献   

高地应力硬脆性围岩开挖损伤区时效性扩展案例分析——特征与机制     

杨艳霜  周辉  梅松华  张占荣  李金兰 《岩土力学》2020,41(4):1357-1365

硬脆性围岩在开挖完成后，其强度在高应力的影响下具有明显的时间效应，这导致围岩开挖损伤区的发展也呈现出与时间相关的特征。在岩石强度时效性演化模型的基础上，以锦屏二级水电站试验洞钻孔摄像、声波、变形监测等开挖损伤区实测结果为目标函数，采用正交设计方法、最小二乘支持向量机模型、粒子群优化算法等方法，建立了考虑时间效应的LSSVM-PSO智能反演分析方法，并以锦屏二级水电站试验洞为例，研究了开挖完成后的25 d里，围岩强度在高地应力条件下的时效性演化特征，进而获得这一时段内开挖损伤区扩展过程。研究结果表明：（1）高应力地区，隧洞开挖后，围岩损伤区的主要扩展方向受地应力控制，且最大扩展方向为最小主应力方向，且破坏区（破坏接近度FAI≥2）也集中于该方向； （2）开挖损伤区面积随时间近似呈S形曲线变化，表明开挖损伤区初始发展较为缓慢，随着时间推移呈现线性增加的趋势，最后又逐渐趋于稳定；（3）开挖后第3～10 d为开挖损伤区快速增长阶段。该研究成果对高应力地区硬脆性围岩开挖损伤区时效性演化研究具有指导意义。  相似文献   

Nonrenewable resources in economic, social, and environmental sustainability     

Deborah J. Shields 《Natural Resources Research》1998,7(4):251-261

This paper reviews the linkages among energy and mineral resources and economic, social, and environmental sustainability. Nonrenewable resources are shown to be integral components of sustainability, regardless of which paradigmatic definition of the concept is invoked. Potential measures of the degree to which nonrenewable resources contribute to or detract from sustainability are presented. We conclude that a set of such measures should be incorporated in the comprehensive framework of sustainability currently being developed by the Federal government. National scale indicators could be presented within the structure of the seven criteria from the Santiago Declaration, whereas a life cycle or materials flow approach could be used when sustainability of specific resources is at issue.  相似文献   

A proposal for comparing the reliabilities of alternative seismic hazard models     

G. Grandori  E. Guagenti  A. Tagliani 《Journal of Seismology》1998,2(1):27-35

Differences between statistical unertainty and modeling uncertainty are briefly discussed. It is pointed out that, when different models are proposed for the interpretation of reality, the uncertainty cannot be described in terms of mean value and coefficient of variation. The important question is: which of the proposed models is more reliable than the others? The attention, then, is concentrated on the comparison between different models proposed for the estimate of the required quantity, looking for a criterion leading to the selection of the most reliable one. A criterion for comparison of different models is suggested. In the example of application considered in this paper, it proved to be effective, so that the continuation of numerical experiments, exploring different and more complex situations, seems promising.  相似文献   

Multiscale approach to geo‐composite cellular structures subjected to rock impacts     

François Nicot  Philippe Gotteland  David Bertrand  Stéphane Lambert 《国际地质力学数值与分析法杂志》2007,31(13):1477-1515

Geo‐composite cellular structures are an efficient technological solution for various applications in civil engineering. This type of structure is particularly well adapted to resisting rockfalls and can act as a defensive structure. However, the design of such structures is for the most part empirically based; this lack of research‐based design stagnates optimization and advanced development. In this paper, the mechanical behaviour of a geo‐composite cellular structure is investigated using a multi‐scale approach, from the individual cell made up of an assembly of rocky particles contained in a wire netting cage to the entire structure composed of a regular array of cells. Based on discrete modelling of both the cell and structure scales, a computational tool has been developed for design purposes. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

西北贫困地区乡村类型识别与振兴途径研究   总被引：11，自引：2，他引：11  

文琦  郑殿元 《地理研究》2019,38(3):509-521

乡村振兴战略是新时期我国推进城乡融合发展的重要举措。贫困地区既是脱贫攻坚的主战场,又是乡村振兴的重点区域。如何科学识别村落类型,分类推进典型区域乡村振兴发展,对于破解农村发展不平衡不充分问题具有重要的现实意义。本文解析了乡村地域系统发展理论,阐释了城乡融合发展理论,剖析了村域空间结构格局演变和城乡要素结构功能优化重组;构建了西北干旱贫困地区乡村振兴村落类型识别体系,从乡村主体、产业发展、人居环境、资源禀赋4个子系统进行逐级分类判断,识别乡村主导类型,结合专家征询分析与村落特征,将乡村振兴村落类型识别为集聚提升类、三产融合类、城郊融合类、特色保护类、搬迁撤并类,结合不同乡村振兴模式提出了相应地发展路径,以期为乡村振兴提供理论依据与决策参考。  相似文献   

Introduction: Interaction between environment and fisheries—The role of stakeholder participation     

Riku Varjopuro  Tim Gray  Jenny Hatchard  Felix Rauschmayer  Heidi Wittmer 《Marine Policy》2008

This paper is an introduction to the special issue on a role of participation in dealing with the interactions between environment and fisheries. In this introduction, we explore the recent discussion on the ecosystem-based approach to fisheries management (EBAFM) and extract important points for implementation of EBAFM from the social science literature on participation and participatory processes in environmental management. The introduction finishes by describing the analytical framework for studying participatory processes.  相似文献