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61.
The study area lies between latitude 18–26°N and longitude 73–83°E, and mainly covers the Central India Tectonic Zone (CITZ). The frequency-dependent shear wave quality factor (Qs) has been estimated over the CITZ and its surroundings using Double Spectral Ratio (DSR) method. We have considered 25 local earthquakes with magnitude (ML) varies from 3.0 to 4.7 recorded at 11 stations running under national seismic network. The Fast Fourier Transformed (FFT) spectra were computed from the recorded waveform having time-window from onset of S-phase to 1.0 s and for a frequency-band of 0.1–10 Hz. Three different shear wave velocities (i.e., 3.87, 3.39 and 3.96 km/s) were obtained over the study area based on a pair of earthquakes recorded at a pair of stations. The low Qs values of 51–96 at 1 Hz (i.e., Qs = 51f0.49; Qs = 90f0.488 and Qs = 96f0.53) were found in the area covering the Son–Narmada–Tapti (SONATA) lineament, CITZ, eastern part of the Satpura fold belt, Vindhyan and Gondwana basins, Godavari and Mahanadi grabens, and southern part of Gangetic plain. Intermediate Qs values of the order of 204–277 (i.e., Qs = 204f0.56 and Qs = 277f0.55) were noted in the cartonic areas, namely, Bundelkhand, Dharwar-Bhandara and Bastar. While the higher Qs values of 391–628 at 1 Hz (i.e., Qs = 391f0.49, Qs = 409f0.48, Qs = 417f0.48, Qs = 500f0.66, Qs = 585f0.65 and Qs = 628f0.69) were found in the eastern part of the SONATA, CITZ, and the northeastern part of the Satpura fold belt. The low Qs values might be attributing to the more heterogeneous SONATA rift system. Low Qs values further may presumably be associated with lower-level of seismicity and apparently account for higher tectonic stress accumulation over long duration. The long-term accumulated stress is generally released through occasional triggering of moderate magnitude earthquakes in the SONATA zone. Surrounding the SONATA region, the higher Qs values possibly accounts for a more homogeneous subsurface structure along the SONATA zone. 相似文献
62.
63.
The loss-cone instability of energetic electrons at double plasma resonance is considered. Conditions required for the formation
of a zebra pattern in type IV solar radio bursts are determined. It is shown that electrons with a power-law energetic spectrum
can effectively excite upper-hybrid waves at double plasma resonance. Stripes of a zebra pattern become more pronounced with
an increase of the loss-cone opening angle and the power-law spectral index. The growth rate at the resonance frequencies
decreases with an increase of the cyclotron harmonic number. Interpretation of observations and diagnostics of plasma for
the April 21, 2002, event are performed. Conclusions about the impulsive mode of injection of energetic electrons into a coronal
arc are made. 相似文献
64.
Results of 2DH morphodynamic computations are presented to quantify the temporal evolution of the crescentic patterns emerging in a double nearshore bar system in response to constant wave boundary forcing. Sixteen different conditions varying both offshore wave height and angle of wave incidence were applied. The mean length scales of the emerging irregular crescentic patterns are linearly proportional to the local longshore velocity over the inner and outer bars. For similar longshore velocities, the length scales of the outer bar are larger than of the inner bar. This is explained by accounting for the difference in water depth above the bar crest. The variable morphological response times can be explained by including additional bathymetrical parameters. The active volume of the bar, defined by the breaker index, plays an important role in this response time. With larger active volumes the bar responds more rapidly to identical boundary conditions. Also, bars with a smaller total volume respond more quickly. This faster response is due to the steeper active volume of the bars. Different initial perturbations resulted in different locations of the emerging features, showing that their location is sensitive to the initial bathymetry. However, the range in length scales and response times due to the different perturbations was significantly smaller than those obtained for the different hydrodynamic conditions. Based on the present findings we hypothesize that morphological length scales in the field are rarely in equilibrium with the concurrent offshore wave height and angle of incidence owing to the slow response of the sandbars under constant conditions relative to the stochastic nature of natural wave forcing. 相似文献
65.
本文利用WRF(Weather Research and Forecasting)模式的不同云微物理方案对2009年6月14日发生在华东地区的一次飑线过程进行1 km的高分辨率模拟,探讨不同云微物理方案对飑线模拟的影响。结果表明:双参数方案的模拟效果总体上优于单参数方案,其中WDM6方案模拟效果最佳,能够较好的模拟出强对流回波区、层云区的主要特征。在单参数方案中以WSM6方案最优。Kessler和LIN方案模拟飑线的回波范围偏小,强度偏弱。进一步对比热力和动力场发现,WDM6方案模拟的冷池的面积最大,强度最强,气压最高,飑线前部的入流处风速最大。不同云微物理方案对微物理场的影响较明显,相比单参数方案,双参数方案模拟的水凝物混合比更高,且能够模拟粒子数浓度,更准确地描述了云中的各类粒子特征。 相似文献
66.
The inverse problem of wave equation is the importance of study not only in seismic prospecting but also in applied mathematics. With the development of the research, the inverse methods of 1 - D wave equations have been trending towards the multiple parameters inversion . We have obtained an inverse method with double -parameter, in which medium density and wave velocity can be derived simultaneously. In this paper, to increase the inverse accuracy, the method is improved as follows. Firstly, the formula in which the Green Function is omitted are derived and used. Secondly, the regularizing method is reasonable used by choosing the stable function. With the new method, we may derive elastic parameter and medium density or medium density and wave velocity. Thus, lithology parameters for seismic prospecting may be obtained.After comparing the derived values from the new method with that from previous method, we obtain the new method through which substantially improve the derived accuracy . The new method has been applied to real depths inversion for sedimentary strata and volcanic rock strata in Chaoyanggou Terrace of Songliao Basin in eastern China. According to the inverse results,the gas - bearing beds are determlned. 相似文献
67.
Liu Ying-keZhou Fu-bao Liu LangLiu Chun Hu Shen-yong 《International Journal of Coal Geology》2011,87(2):139-149
This study investigates the deformation and the resultant pressure relief of highly gassy coal seams where a double seam mining operation takes place at lower depths at the Wulan Coal Mine, China. In order to predict the depressurization effect in the overlying coal seams, we simulate the extraction process by constructing a scaled model in the laboratory using similar rock materials. Analyses of experimental results concluded that due to the mining-induced stress redistribution, the pressure within target coal seams, which were 109 m above the mined seams, could be fully relieved to attain the statutory approval for gas drainage.In addition to scaled-model studies, computational modeling studies were conducted using UDEC (Universal Distinct Element Code), which showed that the features of deformation resulting from the double-seam extraction were different from that of in the case of single-seam extraction. The results of the numerical studies revealed that in addition to the panel margin on the air return side, areas near the intake entry could also be considered as borehole drilling positions. Besides, it was found that the gob of the extracted seams below the gassy one provided a “buffering effect” for the would-mined protective coal seam and that the depressurization effect was largely weakened.The laboratorial findings are instructive to the field practice of methane drainage. During the mining operation, a “displacement comparison method” was adopted to measure the dilated amount of protected coal seams, and as expected, the maximum dilation percentage was much more than 0.2% — the critical value upon which the target coal seam is appropriately depressurized to allow gas drainage to be safely and effectively implemented. 相似文献
68.
While much work has been done in investigating determinants of oil spillage attributed to vessel accidents, little research has been conducted on the effectiveness of ship hull design in reducing marine pollution. This paper addresses whether the double-hull requirement reduces vessel-accident oil spillage. The volume of oil spillage due to oil-cargo vessel accidents was investigated using tobit regressions and an empirical data set of individual vessel accident pollution incidents investigated by the US Coast Guard from 2001 to 2008. The results indicate that the double hull design on average reduces the size of oil spills by 20% and 62% in tank barge and tanker ship accidents, respectively. 相似文献
69.
A Double Solid Reactant Method was elaborated from a suggestion of Marini (Geological sequestration of carbon dioxide: Thermodynamics,
kinetics, and reaction path modeling. Developments in Geochemistry, Elsevier, Amsterdam, 2007) to simulate the release of
trace elements during the progressive dissolution of solid phases. The method is based on the definition, for each dissolving
solid, of both an entity whose thermodynamic and kinetic properties are known (either a pure mineral or a solid mixture) and
a special reactant, that is, a material of known stoichiometry and unknown thermodynamic and kinetic properties. The special
reactant is utilised to take into account the concentrations of trace elements in the dissolving solid phase. In this communication,
the influence of several trace elements on the ΔG
f
o, ΔG
r
o and log K of the minerals considered by Lelli et al. (Environ Geol, 2007) and Accornero and Marini (Geobasi, 2007a; Proceedings of
IMWA symposium, Cagliari, 27–31 May 2007b) was evaluated assuming ideal mixing in the solid state. These effects were found
to be negligible for albite and the leucite–latitic glass, limited for muscovites and chlorites, and slightly more important
for apatites. These influences become progressively higher with increasing concentration of trace elements in these minerals.
Based on these deviations in thermodynamic parameters, special reactants should not include oxide components with molar fractions
higher than 0.003.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Luigi MariniEmail: |
70.