利用参考重力场模型基于能量法确定GRACE加速度计校准参数   总被引：1，自引：0，他引：1  

徐新禹  李建成  王正涛  邹贤才 《武汉大学学报(信息科学版)》2008,33(1):72-75

利用多个参考重力场模型分别对GRACE一个月的实测加速度计观测数据进行检校.数值计算结果的比较分析表明了利用参考重力场模型确定加速度计校准参数是有效的.  相似文献   

Strain localization due to structural in-homogeneities in the Central European Basin System     

Mauro Cacace  Ulf Bayer  Anna Maria Marotta 《International Journal of Earth Sciences》2008,97(5):899-913

The large-scale crustal deformations observed in the Central European Basin System (CEBS) are the result of the interplay between several controlling factors, among which lateral rheological heterogeneities play a key role. We present a finite-element integral thin sheet model of stress and strain distribution within the CEBS. Unlike many previous models, this study is based on thermo-mechanical data to quantify the impact of lateral contrasts on the tectonic deformation. Elasto-plastic material behaviour is used for both the mantle and the crust, and the effects of the sedimentary fill are also investigated. The consistency of model results is ensured through comparisons with observed data. The results resemble the present-day dynamics and kinematics when: (1) a weak granite-like lower crust below the Elbe Fault System is modelled in contrast to a stronger lower crust in the area extending north of the Elbe Line throughout the Baltic region; and (2) a transition domain in the upper mantle is considered between the shallow mantle of the Variscan domain and the deep mantle beneath the East European Craton (EEC), extending from the Elbe Line in the south till the Tornquist Zone. The strain localizations observed along these structural contrasts strongly enhance the dominant role played by large structural domains in stiffening the propagation of tectonic deformation and in controlling the basin formation and the evolution in the CEBS.  相似文献   

GALILEO系统局域完备性监测设计与实现     

赵春梅  程鹏飞  高星伟 《测绘学报》2008,37(1):0-113

根据GALILEO系统局域完备性概念和网络RTK的基本理论,建立导航系统局域网络完备性监测理论和算法。算法主要包括网络系统完备性算法和用户完备性算法,内容包括网络误差模型的建立、插值算法的选择、误差改正数完备性指标的计算、完备性指标的验证和用户保护水平的计算等。仿真结果表明,采用网络RTK技术和完备性监测算法,飞机的平面保护水平和垂直保护水平均小于完备性告警门限值,可以满足飞机Ⅱ类和Ⅲ类精密进近的完备性要求,为卫星导航系统在民航中的应用提供完备性理论基础。  相似文献   

Modified Markov Chain Monte Carlo Method for Dynamic Data Integration Using Streamline Approach     

Yalchin Efendiev  Akhil Datta-Gupta  Xianlin Ma  Bani Mallick 《Mathematical Geosciences》2008,40(2):213-232

In this paper, the Markov Chain Monte Carlo (MCMC) approach is used for sampling of the permeability field conditioned on the dynamic data. The novelty of the approach consists of using an approximation of the dynamic data based on streamline computations. The simulations using the streamline approach allows us to obtain analytical approximations in the small neighborhood of the previously computed dynamic data. Using this approximation, we employ a two-stage MCMC approach. In the first stage, the approximation of the dynamic data is used to modify the instrumental proposal distribution. The obtained chain correctly samples from the posterior distribution; the modified Markov chain converges to a steady state corresponding to the posterior distribution. Moreover, this approximation increases the acceptance rate, and reduces the computational time required for MCMC sampling. Numerical results are presented.  相似文献   

Modelling of the vertical fluxes of nitric acid,ammonia, and ammonium nitrate     

Gerhard Kramm  Ralph Dlugi 《Journal of Atmospheric Chemistry》1994,18(4):319-357

Results from numerical investigations regarding the exchange of HNO₃, NH₃, and NH₄NO₃ between the atmosphere and the biosphere are presented. The investigations were performed with a modified inferential method which is based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's surface and the chemical reactions among these nitrogen compounds. This modified inferential method calculates the micrometeorological quantities (such as the friction velocity and the fluxes of sensible and latent heat), the height-invariant fluxes of the composed chemically conservative trace species with group concentrationsc ₁=[HNO₃]+[NH₄NO₃] (total nitrate),c ₂=[NH₃]+[NH₄NO₃] (total ammonia), andc ₃=[HNO₃]-[NH₃] as well as the fluxes of the individual nitrogen compounds. The parameterization of the fluxes is based on the flux-gradient relationships in the turbulent region of the atmospheric surface layer. The modified inferential method requires only the data of wind velocity, temperature, humidity and concentrations (HNO₃, NH₃, and NH₄NO₃) measured at a reference height by stations of a monitoring network.  相似文献   

Effects of onshore and offshore topography on sea breeze circulation: An observational study at eastern Attica,Greece     

M. Varvayanni  C. G. Helmis  G. T. Amanatidis  D. N. Asimakopoulos  J. G. Bartzis  A. Soilemes  K. H. Papadopoulos  H. D. Kambezidis 《Pure and Applied Geophysics》1993,140(4):681-720

Field measurements of wind, air temperature and humidity were taken at the eastern part of the Attika district in June 1991, to examine the topographic influences exerted on the local sea breezes. These influences are due either to the elongated Evia island, faced by the northern half of Attica coastline some tens of kilometers offshore, or to the coast-parallel range of Hymettos mountain, rising steeply 12 km onshore. The instrumentation consisted mainly of three tethered meteorological balloons released at characteristic sires (i.e., the coast, a location between shoreline and mountain foot and the mountain top) and three autographic ground-based anemometers operating at selected locations. Data from the ground-based and upper air stations of the Hellenic National Meteorological Service, as well as the diurnal weather maps were also obtained and analyzed. Observations were made under different synoptic wind and the latter was found to determine remarkably the significance of the topographic effects. A preliminary two-dimensional numerical approach was also made concerning the sea breeze capability to reach the Hymettos mountain top in the case of a weak opposing geostrophic flow.  相似文献   

杠杆点评估及设计空间抗差     

黄幼才 《测绘学报》1993,22(4):289-293

本分析了杠杆点的几何含义和统计特征,从杠杆点的保差性,矩阵的摄动和参数估值可靠性的观点出发讨论了杠杆点的不利和有利的两个方面,提出了一个全面的设计空间抗差方案。  相似文献   

地震前兆含义,科学问题与研究途径的研讨   总被引：5，自引：2，他引：3  

张肇诚  王贵宣 《地震》1997,17(4):429-439

地震前兆的研究已经取得了很大的进展,地震前兆的复杂性引起了广泛的关注,对地震预报、有关科学问题和探索途径的研究现状及其前景有各种评价。文章认为由于一些科学问题没有解决,尽管对中缅边境１９９５年７月连７．３级地震作出了成功预报,经验性预报有一定的局限性,文中讨论了广义地震前兆和狭义地震前兆,广义地震前兆包含二类前兆：场兆和源兆;而狭义前兆仅指后者。大陆震例前兆的系统研究证实了广义地震前兆的存在,然而  相似文献   

预测陕西关中地区需水量的改进GM(1,1)模型   总被引：6，自引：0，他引：6  

王菊翠  曹明明  仵彦卿 《干旱区地理》2006,29(1):35-41

需水量评价与预测是水资源规划与管理一项重要的研究内容。本文采用定额法计算需水量。通过对陕西关中地区需水量要素组成的分析,认为需水量要素属平稳时间序列,且一阶累加生成数据系列满足指数规律,符合灰色预测条件。为了提高GM(1,1)模型的精度,采用一种改变背景值的新方法,即:中心逼近方法。通过精度检验,中心逼近式GM(1,1)模型平均误差百分比、误差平方和分别比传统的GM(1,1)模型提高了0.147和1.579。用中心逼近式GM(1,1)模型预测需水量各要素近期和中长期值,经检验,其中非农业人口、农业人口、耕地面积、工业总产值预测模型满足一级模型,等级为良好。牲畜头数预测模型为不合格模型,分析其原因,主要是因为时间序列数据不完全符合指数规律。通过定额法计算,预计75%保证率时2005年和2010年关中地区工农业需水量分别占总需水量的92.21%和89.75%,生活需水量分别占7%和9.04%。  相似文献   

Holocene record of productivity in the NW Iberian continental shelf     

V. Alves Martins  C. Patinha  E. Ferreira da Silva  J.-M. Jouanneau  O. Weber  F. Rocha   《Journal of Geochemical Exploration》2006,88(1-3):408

A multiproxy approach (textural characteristics, heavy metal concentrations and benthic foraminifera data) was adopted to study the OMEX core KSGX 40, collected at the Galicia Mud Deposit (NW Iberian outer continental shelf) and recording the last ca. 4.8 ka cal BP. Geochemical profiles of Fe, Mn, Zn, Co, Cr, Cu, Ni, Pb, Al and Ca show significant temporal variations. Benthic foraminifera productivity proxy suggests that the recorded muddy events were contemporaneous of a higher C_org flux to the marine benthic environment. The higher flux of organic matter, following a long-term intensification of the upwelling and coinciding with a finer sedimentation, led to depressed levels of oxygen beneath the water-sediments interface and to early diagenetic processes of several redox-sensitive elements.  相似文献