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Evangelos Paouris 《Solar physics》2013,284(2):589-597
Monthly coronal mass ejection (CME) counts, – for all CMEs and CMEs with widths >?30°, – and monthly averaged speeds for the events in these two groups were compared with both the monthly averaged cosmic ray intensity and the monthly sunspot number. The monthly P i-index, which is a linear combination of monthly CME count rate and average speed, was also compared with the cosmic ray intensity and sunspot number. The main finding is that narrow CMEs, which were numerous during 2007?–?2009, are ineffective for modulation. A cross-correlation analysis, calculating both the Pearson (r) product–moment correlation coefficient and the Spearman (ρ) rank correlation coefficient, has been used. Between all CMEs and cosmic ray intensity we found correlation coefficients r=??0.49 and ρ=??0.46, while between CMEs with widths >?30° and cosmic ray intensity we found r=??0.75 and ρ=??0.77, which implies a significant increase. Finally, the best expression for the P i-index for the examined period was analyzed. The highly anticorrelated behavior among this CME index, the cosmic ray intensity (r=??0.84 and ρ=??0.83), and the sunspot number (r=+?0.82 and ρ=+?0.89) suggests that the first one is a very useful solar–heliospheric parameter for heliospheric and space weather models in general. 相似文献
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Evangelos Chaliasos 《Celestial Mechanics and Dynamical Astronomy》2001,79(2):135-144
The formula giving the shift in the perihelion of the orbit of a charged particle moving around a Reissner-Nordstroem black hole is derived in the approximation 1/c2.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
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Evangelos P. Tziritis 《Central European Journal of Geosciences》2009,1(2):219-226
The Kopaida plain is a cultivated region of Eastern Greece, with specific characteristics related to the paleogeographic evolution and the changes in land use of the area. This study examines the geochemical conditions of the groundwater and soil, and the correlations between them. 70 samples (50 samples of groundwater and 20 samples of soil) were collected in order to asses the geochemical status and the major natural and manmade affecting processes in the region. Extended chemical analyses were carried out including the assessment of 28 parameters for groundwater and 13 for soil samples. The results revealed that groundwater geochemistry is influenced primary by natural processes such as the geological background, and secondary by manmade impact mainly deriving from the extended use of Nitrogen-fertilizers and the over-exploitation of boreholes. Soil geochemistry is influenced exclusively by natural processes, such as weathering of the prevailing geological formations. Chemical analyses and the statistical processing of data revealed that the major factor for the geochemical status of soils is the weathering of the karstic substrate, as well as the existing lateritic horizons and a weak sulfide mineralization. 相似文献
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The summer circulation over the eastern Mediterranean and the Middle East (EMME) is dominated by persistent northerly winds (Etesians) whose ventilating effect counteracts the adiabatic warming induced by large scale subsidence. The ERA40 dataset is used to study the vertical distribution of these circulation features, which both appear to be reconciled manifestations of the South Asian monsoon influence. As predicted by past idealized modeling studies, in late spring a westward expanding upper level warm structure and subsidence areas are associated with Rossby waves excited by the monsoon convection. Steep sloping isentropes that develop over the EMME facilitate further subsidence on the western and northern periphery of the warm structure, which is exposed to the midlatitude westerlies. The northerly flow and descent over the eastern Mediterranean have maxima in July that are strikingly synchronous to the monsoon convection over northern India, where the weaker easterly jet favors a stronger Rossby wave response and consequent impact on the EMME circulation. The pronounced EMME topography modifies the monsoon induced structure, firstly, by inducing orographically locked summer anticyclones. These enhance the mid and low level northwesterly flow at their eastern flanks, leading to distinct subsidence maxima over the eastern Mediterranean and Iran. Secondly, topography amplifies the subsidence and the northerly flow over the Aegean, Red Sea, the Iraq—Gulf region and to the east of the Caspian Sea. 相似文献
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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