GOCE Gravity Field Processing Strategy     

Pail  R.  Plank  G. 《Studia Geophysica et Geodaetica》2004,48(2):289-309

A processing strategy and the corresponding software architecture for the processing of GOCE (Gravity field and steady-state Ocean Circulation Explorer) observables is presented and described, with the major objective to compute a high-accuracy, high-resolution spherical harmonic model of the Earth's gravity field. The combination of two numerical solution strategies, i.e. the rigorous solution of the corresponding large normal equation systems applying parallel processing (on a PC cluster) as the core solver, and the fast semianalytic approach as a quick-look gravity field analysis (QL-GFA) tool, is proposed. Such a method fusion benefits from the advantages of the individual components: the rigorous inversion of the system providing also the full variance-covariance information, and the quickness enabling the consecutive production of intermediate gravity field solutions, for the purpose to analyse partial and incomplete data sets and to derive a diagnosis of the performance of the GOCE measurement system. The functionality and operability of the individual components are demonstrated in the framework of a closed loop simulation, which is based on a realistic mission scenario both in terms of the orbit configuration and the coloured measuring noise. Special concern is given to the accuracy of the recovered coefficients, the numerical behaviour, the required computing time, and the particular role of the individual modules within the processing chain. In the case of the core solver, it is demonstrated that the assembling and rigorous solution of large normal equation systems can be handled by using Beowulf clusters within a reasonable computing time. The application of the quick-look tool to partial data sets with short-term data gaps is demonstrated on the basis of several case studies. Additionally, the spectral analysis of the residuals of the adjustment is presented as a valuable tool for the verification of the noise characteristics of the GOCE gradiometer.  相似文献   

Seismic structural control using an electric servomotor active mass driver system     

Chien‐Liang Lee  Yen‐Po Wang 《地震工程与结构动力学》2004,33(6):737-754

This study investigates an electric‐type active mass driver (AMD) system for structural vibration control. Composed primarily of an electric servomotor and a ball screw, the electrical AMD system is free from noise problems, oil leakage, and labor‐intensive maintenance that commonly are associated with hydraulic AMD systems. The desired stroke amplification of the mass and the power demand of the servomotor can be adjusted via the ball screw pitch, which in turn affects the effectiveness and efficiency of the system. Meanwhile, an instantaneous optimal direct output feedback control algorithm is adopted. Numerical simulation is performed using a five‐story steel frame as the object structure under the conditions of the 1940 El Centro earthquake. The AMD system proves to be effective and efficient within a certain range of the ball screw pitch. The reductions of the peak responses can reach as high as 70% if properly designed. Requiring only the velocity measurement of the top floor for on‐line feedback control, the proposed control algorithm is recommended for practical implementation. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

基于电场理论的主动防雷系统的初步设想   总被引：1，自引：0，他引：1  

钟万强  肖稳安 《南京气象学院学报》2004,27(5):667-673

针对目前使用的传统雷电防护技术存在的问题，通过分析雷电原理和雷电触发机制，利用电场理论来设计一套主动防雷系统，即实现保护对象所在空间大气处于被激放电状态，并利用闪电将大气激活为自激放电状态。介绍了主动防雷系统的原理，并对其核心的“引而不发”理论进行阐述，在此基础上设计出主动防雷系统的模型。具体说明了构成主动防雷系统的阻塞系统、疏导系统和电源系统的构造和特征以及它们之间的关系。计算得到主动防雷系统所需的电场强度E=0．69kV／m。最后指出了存在问题与发展方向，在结论中总结了主动防雷系统的特点及其关键。  相似文献   

高密度电法中的"异常扩展效应"及归位计算方法   总被引：1，自引：0，他引：1  

冯兵  张兴安  李有青 《物探与化探》2004,28(4):349-351,376

对高密度电法勘探的异常扩展效应问题进行了较深人的分析；提出了利用相关分析进行归位计算的方法。通过对球体及板状体的Pole-Pole、Wanner-alpha装置的异常归位计算，表明该方法对复杂异常的解释具有效果。  相似文献   

黄河流域分布式水文模型初步研究与进展   总被引：36，自引：2，他引：36       下载免费PDF全文

刘昌明  夏军  郭生练  郑红星  王中根  吴险峰  郝芳华 《水科学进展》2004,15(4):495-500

结合国家重点基础研究规划项目"黄河流域水资源演化规律与可再生性维持机理"的研究,综述了黄河流域分布式水文模型研究的主要进展,包括分布式水文模型的特点和基本结构、分布式水文模型中的数字高程模型(DEM)和水文学基础、地理信息系统(GIS)和遥感(RS)在分布式水文模拟中的应用等方面的内容,对未来分布式水文模型的研究提出几点认识。  相似文献   

基于GIS/RS的流域水文过程分布式模拟——Ⅰ模型的原理与结构   总被引：5，自引：6，他引：5       下载免费PDF全文

王中根  郑红星  刘昌明  赵为民 《水科学进展》2004,15(4):501-505

面向流域水资源管理,提出了一个基于GIS/RS的流域分布式水文模型,模型主要包括单元水文模型与河网汇流模型两大部分。单元水文模型涉及到冠层截留、融雪、蒸散发、坡面流、非饱和土壤水运动和地下水出流等水文物理过程。产流计算考虑到地形坡度的影响采用基于地形指数的计算方法。汇流演算基于河网结构采用分段马斯京根方法。模型的大部分参数与输入信息可以利用GIS和RS技术获取,能够对气候变化和人类活动对下垫面的改变,做出快速的模拟与响应。  相似文献   

基于拉格朗日插值法修正地形影响的分布式降水模型研究   总被引：1，自引：0，他引：1  

张升堂  康绍忠 《水文》2004,24(6):6-9

降水量一直是进行水文分析计算的输入项，对其分布状况的模拟直接影响水文分析成果精度。降水中心位置及其中心降水量对暴雨分析尤为重要，而目前尚未见对降水中心位置方面的模型研究。在对目前国内外降水模型分析的基础上，根据天气系统降水如不受地形影响其降水量等值线在平面上的分布近似为一组同心椭圆这一原理，建立了一种能够模拟次降水过程的降水中心位置及其中心降水量的新型分布式降水数学模型，并对其进行地形影响因素修正。由于模型建立原理简单，易于实现对流域未设站研究点的实时降水量估计，同时由于模型能够指明降水中心位置及其中心降水量，因此在流域暴雨分析和洪水预报中具有实用价值。模型经实践检验具有较高精度。  相似文献   

我国主要金矿类型中黄铁矿"电子-空穴心"特征及影响因素     

孙国胜  初凤友  胡瑞忠  胡大千  魏存弟 《矿物学报》2004,24(3):211-217

通过对我国主要金矿类型中黄铁矿导电类型的分析表明，黄铁矿“电子。空穴心”与金矿床的成因类型具有密切的联系，华北地台太古代变基性火山岩中的金矿床(绿岩带型)、热水淋滤型(卡林型)金矿床，黄铁矿多为单一的“电子心”型导电。大多数产于中生代岩体中的中深脉状金矿、火山次火山岩中的金矿床，黄铁矿为“电子心”、“空穴心”混合型导电，个别的为单一的“空穴心”导电。黄铁矿的“电子．空穴心”受杂质成分As、Co、Nl在成矿背景中的丰度，进入黄铁矿品格中的替代能力的差异、补偿类质同象现象、成矿时温度以及．f(S2)等多种因素的耦合制约。  相似文献   

Data Fusion in Distributed Multi-sensor System   总被引：5，自引：0，他引：5  

GUOHang YUMin 《地球空间信息科学学报》2004,7(3):214-217

This paper presents a data fusion method in distributed multi-sensor system including GPS and INS sensors“ data processing. First, a residual X^2-test strategy with the corresponding algorithm is designed.Then a coefficient matrices calculation method of the information sharing principle is derived. Finally, the federated Kalman filter is used to combine these independent, parallel, real-time data. A pseudolite (PL) simulation example is given.  相似文献   

Impact of land-cover and climate changes on runoff of the source regions of the Yellow River     

LI Daofeng  TIAN Ying  LIU Changming  HAO Fanghua 《地理学报》2004,14(3):330-338

After dividing the source regions of the Yellow River into 38 sub-basins, the paper made use of the SWAT model to simulate streamflow with validation and calibration of the observed yearly and monthly runoff data from the Tangnag hydrological station, and simulation results are satisfactory. Five land-cover scenario models and 24 sets of temperature and precipitation combinations were established to simulate annual runoff and runoff depth under different scenarios. The simulation shows that with the increasing of vegetation coverage annual runoff increases and evapotranspiration decreases in the basin. When temperature decreases by 2oC and precipitation increases by 20%, catchment runoff will increase by 39.69%, which is the largest situation among all scenarios.  相似文献