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The first complete CCD light curves of the eclipsing binary system V370 Cygni have been obtained in the B, V, R and I filters
during 5 consecutive nights in 2005 at Kryoneri Observatory, Greece. These curves were analyzed with the Wilson–Devinney program
in order to determine the geometrical and physical parameters of the system. The analysis indicates a semi-detached configuration
and a mildly evolved state of the system.
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Vassilios N. Manimanis Chloe Vamvatira-Nakou Panagiotis G. Niarchos 《Astrophysics and Space Science》2009,323(2):115-121
A photometric analysis of the short-period Algol eclipsing binary system BF Velorum based for the first time on complete BVRI
CCD light curves is presented. The new photometric solution obtained with the Wilson-Devinney program reveals that BF Vel
is a near-contact semi-detached system with its secondary component filling its Roche lobe. Moreover, we discovered pulsations
of one member of the binary system, the analysis of which shows main frequencies of 44.9386 and 33.6731 cycles/day. Absolute
elements of the system were calculated, and the evolutionary status of its members was estimated.
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Combining geographic information system, multicriteria evaluation techniques and fuzzy logic in siting MSW landfills 总被引：2，自引：0，他引：2
Alexandra Gemitzi Vassilios A. Tsihrintzis Evangelos Voudrias Christos Petalas George Stravodimos 《Environmental Geology》2007,51(5):797-811
This study presents a methodology for siting municipal solid waste landfills, coupling geographic information systems (GIS),
fuzzy logic, and multicriteria evaluation techniques. Both exclusionary and non-exclusionary criteria are used. Factors, i.e.,
non-exclusionary criteria, are divided in two distinct groups which do not have the same level of trade off. The first group
comprises factors related to the physical environment, which cannot be expressed in terms of monetary cost and, therefore,
they do not easily trade off. The second group includes those factors related to human activities, i.e., socioeconomic factors,
which can be expressed as financial cost, thus showing a high level of trade off. GIS are used for geographic data acquisition
and processing. The analytical hierarchy process (AHP) is the multicriteria evaluation technique used, enhanced with fuzzy
factor standardization. Besides assigning weights to factors through the AHP, control over the level of risk and trade off
in the siting process is achieved through a second set of weights, i.e., order weights, applied to factors in each factor
group, on a pixel-by-pixel basis, thus taking into account the local site characteristics. The method has been applied to
Evros prefecture (NE Greece), an area of approximately 4,000 km2. The siting methodology results in two intermediate suitability maps, one related to environmental and the other to socioeconomic
criteria. Combination of the two intermediate maps results in the final composite suitability map for landfill siting. 相似文献
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Christos Kourouklas Eleftheria Papadimitriou George Tsaklidis Vassilios Karakostas 《Journal of Seismology》2018,22(5):1225-1246
The determination of strong earthquakes’ recurrence time above a predefined magnitude, associated with specific fault segments, is an important component of seismic hazard assessment. The occurrence of these earthquakes is neither periodic nor completely random but often clustered in time. This fact in connection with their limited number, due to shortage of the available catalogs, inhibits a deterministic approach for recurrence time calculation, and for this reason, application of stochastic processes is required. In this study, recurrence time determination in the area of North Aegean Trough (NAT) is developed by the application of time-dependent stochastic models, introducing an elastic rebound motivated concept for individual fault segments located in the study area. For this purpose, all the available information on strong earthquakes (historical and instrumental) with Mw ≥ 6.5 is compiled and examined for magnitude completeness. Two possible starting dates of the catalog are assumed with the same magnitude threshold, Mw ≥ 6.5 and divided into five data sets, according to a new segmentation model for the study area. Three Brownian Passage Time (BPT) models with different levels of aperiodicity are applied and evaluated with the Anderson–Darling test for each segment in both catalog data where possible. The preferable models are then used in order to estimate the occurrence probabilities of Mw ≥ 6.5 shocks on each segment of NAT for the next 10, 20, and 30 years since 01/01/2016. Uncertainties in probability calculations are also estimated using a Monte Carlo procedure. It must be mentioned that the provided results should be treated carefully because of their dependence to the initial assumptions. Such assumptions exhibit large variability and alternative means of these may return different final results. 相似文献
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Melina G. Sidiropoulou Konstadinos N. Moutsopoulos Vassilios A. Tsihrintzis 《水文研究》2007,21(4):534-554
This study focuses on the determination of the Forchheimer equation coefficients a and b for non‐Darcian flow in porous media. Original theoretical equations are evaluated and empirical relations are proposed based on an investigation of available data in the literature. The validity of these equations is checked using existing experimental data, and their accuracy versus existing approaches is studied. On the basis of this analysis, some insight into the physical background of the phenomenon is also provided. The dependence of the coefficients a and b on the Reynolds number is also detected, and potential future research areas, e.g. investigation of inertial effects for consolidated porous media, are pointed out. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Nikolaos Theodulidis Zafeiria Roumelioti Areti Panou Alexandros Savvaidis Anastasia Kiratzi Vassilios Grigoriadis Petros Dimitriu Theodoros Chatzigogos 《Bulletin of Earthquake Engineering》2006,4(2):101-130
The densely populated city of Thessaloniki (Northern Greece) is situated in~the vicinity of active seismic faults, capable of producing moderate to strong earthquakes. The city has been severely affected by such events several times during the last 15 centuries. The most recent event occurred on 20 June 1978 (M6.5) in the Mygdonian graben, with an epicentral distance of about 30 km, causing extended damage in the city, with macroseismic intensities between MSK V+ and VIII+. The majority of buildings affected by the earthquake were of reinforced-concrete typology, typical to many southern European metropolitan areas. The source properties of the normal-faulting causative event and the source-to-city propagation path are well known from previous studies. The soil structure under the metropolitan area of Thessaloniki is assigned NEHRP categories B, C, D on the basis of geotechnical and geologic information and single-station ambient-noise measurements. A finite source model and various rupture scenarios of the June 1978 earthquake are used to perform forward stochastic modeling of strong ground motion in terms of peak ground and spectral acceleration. Rock motion is assessed under the city and it is transferred to the surface in accordance with the respective soil category. A GIS tool is employed to compare the estimated strong-motion parameters with the observed detailed damage pattern induced by the 1978 earthquake. For selected natural periods, a satisfactory correlation is established between macroseismic intensity and peak ground and spectral acceleration, thus encouraging the application of stochastic modeling for generating realistic ground-shaking scenarios in metropolitan areas. 相似文献
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Tatyana Novikova Gerassimos A. Papadopoulos Vassilios Karastathis 《Natural Hazards》2007,40(3):537-552
In the present paper we analyze the effect of local geology on ground motion by means of numerical calculations (numerical
models) using total (TS) and effective stress (ES) methods. These numerical calculations have been applied to the site of
Itea, Corinth Gulf, which was chosen based on liquefaction susceptibility criteria and field inspection. Data from seismic
refraction experiments and cone penetration test N-values as well as selected records of ground motion in nearby areas were
used to construct the input file for the numerical model. By means of␣dynamic analysis such characteristics of ground motion
as acceleration time histories, response spectra, and amplification function were evaluated. A one-dimensional soil amplification
effect was clearly shown. Liquefaction probability at the Itea site was predicted based on the safety factor and the calculation
of the induced settlement at the test site. Results of the TS and ES modeling lead us to conclude: (1) the presence of soft
soil at Itea caused significant amplification (almost 2.5-fold higher magnitude) of the underlying bedrock motion and, therefore,
can contribute to damage; (2) the area of Itea is highly susceptible to liquefaction due to presence of silty sand deposits
at depths between 2.48 m (the position of the water table) and 12 m that demonstrate the rapid growth of the excess pore water
pressure (EPWP) ratio with an increase in peak ground acceleration values. 相似文献
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Vassilios Karakostas Eleftheria Papadimitriou Maria Mesimeri Charikleia Gkarlaouni Parthena Paradisopoulou 《Acta Geophysica》2015,63(1):1-16
The 2014 Kefalonia earthquake sequence started on 26 January with the first main shock (MW6.1) and aftershock activity extending over 35 km, much longer than expected from the causative fault segment. The second main shock (MW6.0) occurred on 3 February on an adjacent fault segment, where the aftershock distribution was remarkably sparse, evidently encouraged by stress transfer of the first main shock. The aftershocks from the regional catalog were relocated using a 7-layer velocity model and station residuals, and their distribution evidenced two adjacent fault segments striking almost N-S and dipping to the east, in full agreement with the centroid moment tensor solutions, constituting segments of the Kefalonia Transform Fault (KTF). The KTF is bounded to the north by oblique parallel smaller fault segments, linking KTF with its northward continuation, the Lefkada Fault. 相似文献