Analysis of star camera errors in GRACE data and their impact on monthly gravity field models   总被引：1，自引：1，他引：0  

Pedro Inácio  Pavel Ditmar  Roland Klees  Hassan Hashemi Farahani 《Journal of Geodesy》2015,89(6):551-571

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A Geochemical Study of Rare Earth and Trace Elements in Cassiterite from Dachang Sn-Polymetallic Ore Field,Guangxi Province     

Pan JiahuaInstitute of Mineral Deposits  Chinese Academy of Geological Sciences  Beijing Amstutz G. C.Mineralogisch-Petrogrophisches Institut der Universitat Heidelberg  In Neuenheimer Feld  Heidelberg  Germany 《中国地质大学学报(英文版)》1993

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Numerical simulation of the heavy rainfall caused by a convection band over Korea: a case study on the comparison of WRF and CReSS     

Im  Eun-Soon  In  So-Ra  Han  Sang-Ok 《Natural Hazards》2013,69(3):1681-1695

Natural Hazards - This study investigates the capability of two numerical models, namely the Weather Research and Forecasting (WRF) and Cloud Resolving Storm Simulator (CReSS), to simulate the...  相似文献   

Geotechnical parameter estimation in tunnelling using relative convergence measurement     

Kook‐Hwan Cho  Min‐Kwang Choi  Seok‐Woo Nam  In‐Mo Lee 《国际地质力学数值与分析法杂志》2006,30(2):137-155

Accurate estimation of geotechnical parameters is an important and difficult task in tunnel design and construction. Optimum evaluation of the geotechnical parameters have been carried out by the back‐analysis method based on estimated absolute convergence data. In this study, a back‐analysis technique using measured relative convergence in tunnelling is proposed. The extended Bayesian method (EBM), which combines the prior information with the field measurement data, is adopted and combined with the 3‐dimensional finite element analysis to predict ground motion. By directly using the relative convergence as observation data in the EBM, we can exclude errors that arise in the estimation of absolute displacement from measured convergence, and can evaluate the geotechnical parameters with sufficient reliability. The proposed back‐analysis technique is applied and validated by using the measured data from two tunnel sites in Korea. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

A simulation using a hybrid method for predicting fault zones ahead of a tunnel face     

In‐Mo Lee  Don‐Hee Kim 《国际地质力学数值与分析法杂志》2003,27(2):147-158

By monitoring and analysing three‐dimensional absolute displacement during tunnel excavation, it is possible to predict discontinuity zones ahead of tunnel face. This paper presents results of the three‐dimensional displacement obtained from three‐dimensional simulations using hybrid method for assessing the effect of discontinuity zones on monitoring data. The influence of fault zones and in situ initial stresses on the three‐dimensional tunnel movement is evaluated. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Wide field X-ray monitor on board the High Energy Transient Experiment (HETE)     

A. Yoshida  M. Matsuoka  N. Kawai  F. Tokanai  E. E. Fenimore  J. J. M. In 'T Zand  M. Galassi  M. Yamauchi  K. Takagishi  I. Hatsukade 《Astrophysics and Space Science》1995,231(1-2):463-466

The High-Energy Transient Experiment (HETE) is designed for the multiwavelengths study of Gamma-Ray Bursts (GRBs) in UV, X-ray and gamma-ray range with three scientific instruments. The X-ray instrument, Wide-field X-ray Monitor (WXM), consists of four units of one-dimensional position sensitive gas proportional counters and two perpendicularly oriented one-dimensional coded apertures. The WXM has a wide FOV of 1.5 steradian together with the capability to locate GRBs with 10 arcmin accuracy, and covers photon energies of 2 to 25 keV with an energy resolution of typically 18 % at 6 keV, measuring wide band spectra together with the gamma-ray spectrometer (FREGATE). The coded X-ray image will be deconvolved on board and the GRB location will be provided to the UV camera within 1 sec . GRB locations will also be broadcast in real time to ground-based observers for follow-up observations.  相似文献   

Underestimation of roughness in rough rock joints   总被引：1，自引：0，他引：1  

Eun‐Soo Hong  Jong‐Sub Lee  In‐Mo Lee 《国际地质力学数值与分析法杂志》2008,32(11):1385-1403

Numerous studies have been made to improve Barton's shear strength model for the quantification of rock joints. However, in these previous studies, the roughness and shear strength of the rock joint have been underestimated especially for relatively high undulated profiles (joint roughness coefficient (JRC) >14). The main factors of roughness underestimation in rough rock joints are investigated for the proper quantification of rock joint roughness. The aliasing effect and the roughness characteristics are analyzed by using artificial joint profiles and natural rock joint profiles. A 3D camera scanner is adopted to verify the main source of underestimation when using conventional measurement methods. Shear strength tests are carried out by using two types of shear apparatus to study the roughness mobilization characteristics, which may also affect the roughness underestimation. The results of joint roughness assessment, such as aliasing and undulation of waviness, show that the roughness can be underestimated in relatively rough joint profiles (JRC>14). At least two components of roughness parameters are needed to properly represent the joint roughness, for example, the amplitude and the inclination angle of joint asperity. Roughness mobilization is affected by both the normal stress and the asperity scale. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Propagation characteristics of historical tsunamis that attacked the east coast of Korea     

Chae Ho Lim  Jae Seok Bae  Jong In Lee  Sung Bum Yoon 《Natural Hazards》2008,47(1):95-118

In this study, a numerical modeling system based on the dispersion–correction finite difference scheme equipped with a grid-nesting scheme is constructed. The model is applied to simulate the propagation of three historical tsunami events that attacked the east coast of Korea. The calculated free-surface displacements for the cases of the 1983 Akita and the 1993 Okushiri tsunamis are compared with the observations at four tidal stations along the east coast of Korea. The comparison shows that the results agree well with the observations. The analyses of the simulated results show that underwater topography, such as submerged rises and ridges, plays an important role in the propagation of tsunamis in this region.  相似文献   

Assessing interpolation error for space–time monitoring data     

Luís Margalho  Raquel Menezes  Inês Sousa 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(5):1307-1321

In Europe, since 1990, a survey on environmental monitoring has been taking place every 5 years, using moss samples to study the distribution of heavy metal concentration and assess contamination sources, resulting on the identification of statistical association of several heavy metal concentrations in mosses. With this work, we propose an extension of an existing spatio-temporal model, introduced in Høst et al. (JASA 90(431):853–861, 1995), allowing for prediction at unsampled locations of pollution data in the presence of covariates related to each country specificities, when separately modelling the spatial mean field, the spatial variance field and the space–time residual field. Moreover, this model allows to estimate an interpolation error, as an accuracy measure, derived dependently on the case study. For a validation purpose, a simulation study is conducted, showing that the use of the proposed model leads to more accurate prediction values. Results obtained by the proposed methodology for the most recent available survey, are compared with results obtained with no temporal information, namely when Ordinary Kriging, according to the definition in Cressie (Statistics for spatial data, Wiley, New York, 1993), is used to derive illustrative prediction maps based only on the most recent data. An exercise of cross-validation is performed relative to each of the scenarios considered and the average interpolation errors are presented. While assessing interpolation errors, we conclude that the monitoring specificities of each country and the information of preceding surveys allow for more accurate prediction results.  相似文献   

Experimental assessment of Posidonia oceanica‐associated gastropods grazing on an early‐successional biofilm community: nutrient availability and species‐specific effects          下载免费PDF全文

Inés Castejón‐Silvo  Jorge Terrados 《Marine Ecology》2017,38(1)

Although grazing is considered an essential process controlling epiphyte biomass on seagrass leaves, there is still a lack of fundamental knowledge about the species‐specific consumption rates of the most common grazers in Mediterranean meadows. This study experimentally assessed the effect of Posidonia oceanica‐associated gastropod grazing on early successional biofilm and the species‐specific relationship between biofilm consumption rates and biofilm biomass. Two biofilms on artificial substrata, both developed in situ (in a P. oceanica meadow), one under ambient conditions and the other under nutrient‐enriched conditions, were offered in aquaria assays to nine species of grazers found in P. oceanica meadows. Biofilm consumption rates and their association with biofilm biomass were assessed. It was found that: (i) there was a positive association between biofilm consumption and biofilm biomass up to 20 mg Chl a·m^?2 for Bittium reticulatum, Gibbula ardens, Jujubinus exasperatus and Tricolia pullus; (ii) Alvania montagui, B. reticulatum and Jujubinus striatus showed the highest consumption rates and are thus expected to be amongst the leading consumers in early‐successional epiphytic communities; (iii) there was not an increase of consumption rate when a substratum colonized under nutrient‐enriched conditions was offered to any of the nine studied species. This study provides species‐specific consumption rates knowledge that is useful for the assessment of the strength of grazer–epiphyte interactions and trophic fluxes in P. oceanica meadows.  相似文献