Geological mapping of Santorini Volcanic island (Greece), with the combined use of Pleiades 1A and ENVISAT satellite images     

Dimitrios Oikonomidis  Spyridon Pavlides 《Arabian Journal of Geosciences》2017,10(7):175

Very high-resolution (VHR) Pleiades 1A and ENVISAT/ASAR (Advanced Synthetic Aperture Radar) satellite images were used for lithological and tectonic mapping respectively of Santorini island complex, South Aegean, Greece. The results were compared to the existing geological maps of the study area. The extracted, quantitative results within GIS environment, followed by a ground-truth visit, showed that there is some variance in the delineation of the boundaries of certain lithological units on the geological map compared to those on the Pleiades 1A image and that a number of lineaments detected on the ENVISAT image could be incorporated to the faults’ population. As a general conclusion, new findings can be embodied to the existing geological maps.  相似文献   

The rocking spectrum and the limitations of practical design methodologies     

Nicos Makris  Dimitrios Konstantinidis 《地震工程与结构动力学》2003,32(2):265-289

This paper is concerned with the superficial similarities and fundamental differences between the oscillatory response of a single‐degree‐of‐freedom (SDOF) oscillator (regular pendulum) and the rocking response of a slender rigid block (inverted pendulum). The study examines the distinct characteristics of the rocking spectrum and compares the observed trends with those of the response spectrum. It is shown that the rocking spectrum reflects kinematic characteristics of the ground motions that are not identifiable by the response spectrum. The paper investigates systematically the fundamental differences in the dynamical structure of the two systems of interest and concludes that rocking structures cannot be replaced by ‘equivalent’ SDOF oscillators. The study proceeds by examining the validity of a simple, approximate design methodology, initially proposed in the late 1970s and now recommended in design guidelines to compute rotations of slender structures by performing iteration either on the true displacement response spectrum or design spectrum. This paper shows that the simple design approach is inherently flawed and should be abandoned, in particular for smaller, less‐slender blocks. The study concludes that the exact rocking spectrum emerges as a distinct intensity measure of ground motions. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Evaluation of the influence of vertical irregularities on the seismic performance of a nine‐storey steel frame     

Fragiadakis Michalis  Vamvatsikos Dimitrios  Papadrakakis Manolis 《地震工程与结构动力学》2006,35(12):1489-1509

A methodology based on incremental dynamic analysis (IDA) is presented for the evaluation of structures with vertical irregularities. Four types of storey‐irregularities are considered: stiffness, strength, combined stiffness and strength, and mass irregularities. Using the well‐known nine‐storey LA9 steel frame as a base, the objective is to quantify the effect of irregularities, both for individual and for combinations of stories, on its response. In this context a rational methodology for comparing the seismic performance of different structural configurations is proposed by means of IDA. This entails performing non‐linear time history analyses for a suite of ground motion records scaled to several intensity levels and suitably interpolating the results to calculate capacities for a number of limit‐states, from elasticity to final global instability. By expressing all limit‐state capacities with a common intensity measure, the reference and each modified structure can be naturally compared without needing to have the same period or yield base shear. Using the bootstrap method to construct appropriate confidence intervals, it becomes possible to isolate the effect of irregularities from the record‐to‐record variability. Thus, the proposed methodology enables a full‐range performance evaluation using a highly accurate analysis method that pinpoints the effect of any source of irregularity for each limit‐state. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Modelling the extension of heterogeneous hot lithosphere   总被引：2，自引：0，他引：2  

Dimitrios Sokoutis  Giacomo Corti  Marco Bonini  Jean Pierre Brun  Sierd Cloetingh  Thomas Mauduit  Piero Manetti 《Tectonophysics》2007,444(1-4):63-79

The consequences of weak heterogeneities in the extension of soft and hot lithosphere without significant previous crustal thickening has been analysed in a series of centrifuge models. The experiments examined the effects of i) the location of heterogeneities in the ductile crust and/or in the lithospheric mantle, and ii) their orientation, perpendicular or oblique to the direction of bulk extension. The observed deformation patterns are all relevant to the so-called “wide rifting” mode of extension. Weak zones located in the ductile crust exert a more pronounced influence on localisation of deformation in the brittle layer than those located in the lithospheric mantle: the former localise faulting in the brittle crust whereas the latter tend to distribute faulting over a wider area. This latter behaviour depends in turn upon the decoupling provided by the ductile crust. Localised thinning in the brittle crust is accompanied by ductile doming of both crust and mantle. Domains of maximum thinning in the brittle crust and ductile crust and mantle are in opposition. Lateral differences in brittle crust thinning are accommodated by lateral flow in the ductile crust and mantle. This contrasts with “cold and strong” lithospheres whose high strength sub-Moho mantle triggers a necking instability at the lithosphere-scale. This also differs from the extension of thickened hot and soft lithospheres whose ductile crust is thick enough to give birth to metamorphic core complexes. Thus, for the given lithospheric rheology, the models have relevance to backarc type extensional systems, such as the Aegean and the Tyrrhenian domains.  相似文献   

Anisotropic Mesh Adaptivity and Control Volume Finite Element Methods for Numerical Simulation of Multiphase Flow in Porous Media   总被引：1，自引：1，他引：0  

Peyman Mostaghimi  James R. Percival  Dimitrios Pavlidis  Richard J. Ferrier  Jefferson L. M. A. Gomes  Gerard J. Gorman  Matthew D. Jackson  Stephen J. Neethling  Christopher C. Pain 《Mathematical Geosciences》2015,47(4):417-440

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Estimation of satellite position,clock and phase bias corrections     

Patrick Henkel  Dimitrios Psychas  Christoph Günther  Urs Hugentobler 《Journal of Geodesy》2018,92(10):1199-1217

Precise point positioning with integer ambiguity resolution requires precise knowledge of satellite position, clock and phase bias corrections. In this paper, a method for the estimation of these parameters with a global network of reference stations is presented. The method processes uncombined and undifferenced measurements of an arbitrary number of frequencies such that the obtained satellite position, clock and bias corrections can be used for any type of differenced and/or combined measurements. We perform a clustering of reference stations. The clustering enables a common satellite visibility within each cluster and an efficient fixing of the double difference ambiguities within each cluster. Additionally, the double difference ambiguities between the reference stations of different clusters are fixed. We use an integer decorrelation for ambiguity fixing in dense global networks. The performance of the proposed method is analysed with both simulated Galileo measurements on E1 and E5a and real GPS measurements of the IGS network. We defined 16 clusters and obtained satellite position, clock and phase bias corrections with a precision of better than 2 cm.  相似文献   

Correction to: Estimation of satellite position,clock and phase bias corrections     

Patrick Henkel  Dimitrios Psychas  Christoph Günther  Urs Hugentobler 《Journal of Geodesy》2018,92(10):1219-1221

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Extraction and predictability of coherent intraseasonal signals in infrared brightness temperature data     

Eniko Székely  Dimitrios Giannakis  Andrew J. Majda 《Climate Dynamics》2016,46(5-6):1473-1502

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Solution of the linear diffusion equation for modelling erosion processes with a time varying diffusion coefficient     

Georgios Aim. Skianis  Dimitrios Vaiopoulos  Niki Evelpidou 《地球表面变化过程与地形》2008,33(10):1491-1501

In the present paper the differential equation of the temporal development of a landform (mountain) with a time dependent diffusion coefficient is solved. It is shown that the shape and dimensions of the landform at time t are independent of the specific variation of the diffusion coefficient with time; they only depend on the mean value of the diffusion coefficient in the time interval where the erosion process takes place. Studying the behaviour of the solution of the differential equation in the wave number domain, it is concluded that Fourier analysis may help in estimating, in quantitative terms, the initial dimensions, the age or, alternatively, the value of the diffusion coefficient of the landform. The theoretical predictions are tested on a hill of the southern part of the Ural mountainous region, in order to show how the results of the mathematical analysis can be used in describing, in quantitative terms, the morphological development of landforms due to erosion processes. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Seismic intensity measures for above‐ground liquid storage tanks          下载免费PDF全文

Konstantinos Bakalis  Mohsen Kohrangi  Dimitrios Vamvatsikos 《地震工程与结构动力学》2018,47(9):1844-1863

A series of scalar and vector intensity measures is examined to determine their suitability within the seismic risk assessment of liquid storage tanks. Using a surrogate modelling approach on a squat tank that is examined under both anchored and unanchored support conditions, incremental dynamic analysis is adopted to generate the distributions of response parameters conditioned on each of the candidate intensity measures. Efficiency and sufficiency metrics are used in order to perform the intensity measure evaluation for individual failure modes, while a comparison in terms of mean annual frequency of exceedance is performed with respect to a damage state that is mutually governed by the impulsive and convective modes of the tank. The results reveal combinations of spectral acceleration ordinates as adequate predictors, among which the average spectral acceleration is singled out as the optimal solution. The sole exception is found for the sloshing‐controlled modes of failure, where mainly the convective period spectral acceleration is deemed adequate to represent the associated response due to their underlying linear relationship. A computationally efficient method in terms of site hazard analysis is finally proposed to serve in place of the vector‐valued intensity measures, providing a good match for the unanchored tank considered and a more conservative one for the corresponding anchored system.  相似文献