排序方式： 共有11条查询结果，搜索用时 343 毫秒
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P. Rodríguez-Gil B. T. Gänsicke H.-J. Hagen S. Araujo-Betancor A. Aungwerojwit C. Allende Prieto D. Boyd J. Casares D. Engels O. Giannakis E. T. Harlaftis J. Kube H. Lehto I. G. Martínez-Pais R. Schwarz W. Skidmore A. Staude M. A. P. Torres 《Monthly notices of the Royal Astronomical Society》2007,377(4):1747-1762
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Additive as well as multiplicative noise may occur when acoustic waves propagate through the ocean. Second-order spectral methods fail to retrieve frequencies of such random amplitude modulated harmonic time series, especially when the multiplicative noise is broadband. An existing fourth-order method assumes real Gaussian multiplicative and additive noise. A novel approach is proved herein to impose no constraints on the distribution or the color of the disturbances. It relies on fourth-order special cumulant or moment slices. In particular, the fourth-order moment spectrum is shown to offer computational advantages. Extension to multicomponent models and generalizations to alternative higher order moments are also provided. Simulations corroborate the theoretical results 相似文献
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Evangelos Mitsakis Iraklis Stamos Anestis Papanikolaou Georgia Aifadopoulou Haris Kontoes 《Natural Hazards》2014,72(1):87-107
This paper deals with the 2007 wildfires that hit Peloponnesus, the southern peninsula of Greece, presenting an overview of the impacts in terms of infrastructural damages and human injuries and losses. Network performance and components’ criticality analyses are used to assess the effects of the fires in vehicular traffic and the overall transport network. The crisis and emergency management of the event are discussed in depth, highlighting potential gaps and possibilities for future improvement. The paper concludes with a presentation of the adaptation measures that succeeded the event in terms of recovery plans, national efforts on fire prevention programs and wildfire management. 相似文献
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S. D. Nerantzaki D. Efstathiou G. V. Giannakis M. Kritsotakis M. G. Grillakis A. G. Koutroulis 《水文科学杂志》2013,58(10):1190-1203
ABSTRACTCrete is a Mediterranean, karst-dominated island, characterized by long drought periods. The Karst-SWAT model, combined with 11 climate change scenarios, was run to assess climate change impacts on the island under two set-ups, both using the auto-irrigation function of the model: (1) with water drawn from the shallow or deep aquifer, and (2) with irrigated water derived from an unlimited outside source. The first set-up provided insight into the fluctuation of future irrigation needs, and when compared to the second set-up, enabled quantification of the future water deficit. The Water Exploitation Index was used to describe the spatial variability of future water stress on Crete. A decrease in both surface and karstic spring flows is foreseen, especially after 2060 (24.2 and 16.5%, respectively). Simulated irrigation water demand and water deficit show continuous increase throughout the projection period (2020–2098). 相似文献
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Marina Pantazidou Iraklis Panagiotakis Daniel Mamais Vasiliana Zikidi 《Ground Water Monitoring & Remediation》2012,32(1):106-119
This paper aims to reconcile discrepancies among reports of dechlorination performance in the presence of sulfate, by analyzing data from the literature, presenting results from laboratory experiments performed with mixed anaerobic microbial cultures, and synthesizing respective findings. A complete set of metrics for dechlorination progress was developed and used in the analysis of selected field and laboratory studies. When differences in site and experimental conditions are accounted for and definitions of dechlorination completeness are harmonized, the inverse relationship between dechlorination performance and sulfate concentration becomes clearer. This relationship was investigated in detail with laboratory experiments on mixed anaerobic microbial cultures enriched with the same concentration of trichloroethylene (TCE) and different sulfate concentrations, equal to near zero (considered as the baseline culture), 30, 400, and 1100 mg/L. In all experiments, sulfate reduction proceeded concurrently with dechlorination. The observed behavior was bimodal, indicating a transition in dechlorination performance between 30 and 400 mg/L. Under low donor to acceptor stoichiometry conditions, TCE dechlorination was incomplete in all experiments after 14 days, while the percentage of TCE moles reduced to vinyl chloride was lower by about 50% in the experiments with high sulfate concentrations. When donor was added in excess to stoichiometry needs for TCE reduction, TCE dechlorination was complete in the baseline culture, while only little ethene was detected in the high sulfate concentration cultures. When all studies are considered together, it appears that the presence of sulfate does not preclude complete dechlorination but rather delays it. Data analysis also suggests that the proposed upper limit of 500 mg/L for the range of initial sulfate concentration that is not problematic for dechlorination should be revised to a lower value. 相似文献
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Iraklis S. Konstantopoulos Nate Bastian Linda J. Smith Gelys Trancho Mark S. Westmoquette Jay S. Gallagher III 《Astrophysics and Space Science》2009,324(2-4):343-346
The post-starburst region B in M82 and its massive star cluster component have been the focus of multiple studies, with reports that there is a large population of coeval clusters of age ～1 Gyr, which were created with a Gaussian initial mass distribution. This is in disagreement with other studies of young star clusters, which invariably find a featureless power-law mass distribution. Here, we present Gemini-North optical spectra of seven star clusters in M82-B and show that their ages are all between 10 and 300 Myr (a factor of 3–100 younger than previous photometric results) and that their extinctions range between near zero and 4 mag (A V ). Using new HST ACS-HRC U-band observations we age date an additional ～30 clusters whose ages/extinctions agree well with those determined from spectroscopy. Completeness tests show that the reported ‘turn-over’ in the luminosity/mass distributions is most likely an artefact, due to the resolved nature of the clusters. We also show that the radial velocities of the clusters are inconsistent with them belonging to a bound region. 相似文献
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O. Giannakis E. T. Harlaftis P. G. Niarchos S. Kitsionas H. Barwig M. Still R. G. M. Rutten 《Astrophysics and Space Science》2006,304(1-4):321-322
We report the results of simultaneous optical/X-ray observations of X1822-371 at 0.1 second time resolution. The preliminary analysis finds no correlation between the optical/X-ray light curves. We aim to constrain the vertical structure and radius of the accretion disc.Deceased Feb. 13, 2005 相似文献