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71.
利用区域双差层析成像方法,基于2008年10月—2018年6月近震资料,对晋冀豫交界地区记录到的地震事件进行震源位置与P波、S波三维速度结构的联合反演。重新定位后,地震空间位置得到明显改善,浅部的速度结构与地形及沉积层厚度对应较好,研究区内控制性断裂和地震多分布在太行山隆起区的高、低速变化梯级带上。对比分析研究区内不同构造单元及同一构造单元不同深度的P、S波速度异常特征及其与中小地震和历史强震的分布关系,结合研究区内历史强震和现今中、小震分析发震构造及深部孕震环境,为该区未来强震危险区判定提供科学依据。 相似文献
72.
Settling velocity of diluted suspended aggregates is examined under steady-state conditions. It is shown that if the local settling velocity of the suspended mass of sediments at the bottom is gamma distributed, then, the vertical variation of the local mean settling velocity is proportional to a power of the local concentration C, where r is the gamma distribution parameter. That is a consequence of the suspended-sediment sorting produced by the vertical dynamics. The parameter r characterizes the range of settling velocity values for all the aggregates simultaneously in suspension. To cite this article: M. Sánchez et al., C. R. Geoscience 337 (2005). 相似文献
73.
Zoltán Zajacz Werner Halter Wim J. Malfait Olivier Bachmann Robert J. Bodnar Marc M. Hirschmann Charles W. Mandeville Yann Morizet Othmar Müntener Peter Ulmer James D. Webster 《Contributions to Mineralogy and Petrology》2005,150(6):631-642
A new approach was developed to measure the water content of silicate glasses using Raman spectroscopy, which is independent
of the glass matrix composition and structure. Contrary to previous studies, the compositional range of our studied silicate
glasses was not restricted to rhyolites, but included andesitic, basaltic and phonolitic glasses. We used 21 glasses with
known water contents for calibration. To reduce the uncertainties caused by the baseline removal and correct for the influence
of the glass composition on the spectra, we developed the following strategy: (1) application of a frequency-dependent intensity
correction of the Raman spectra; (2) normalization of the water peak using the broad T–O and T–O–T vibration band at 850–1250 cm−1 wavenumbers (instead of the low wavenumber T–O–T broad band, which appeared to be highly sensitive to the FeO content and
the degree of polymerization of the melt); (3) normalization of the integrated Si-O band area by the total number of tetrahedral
cations and the position of the band maximum. The calibration line shows a ±0.4 wt% uncertainty at one relative standard deviation
in the range of 0.8–9.5 wt% water and a wide range of natural melt compositions. This method provides a simple, quick, broadly
available and cost-effective way for a quantitative determination of the water content of silicate glasses. Application to
silicate melt inclusions yielded data in good agreement with SIMS data. 相似文献
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75.
A Merchantek LUV266 TM petrographic ultraviolet (UV) laser microprobe has been used in conjunction with a Finnigan MAT ELEMENT TM high resolution ICP double-focusing mass spectrometer (HR-ICP-MS) for solid microsampling and geochemical analysis. This new configuration for laser ablation has the advantage of coupling the high sensitivity and fast scanning technology applied in the ELEMENT with the ablation efficiency of a UV laser. Optimisation of the configuration on the synthetic NIST SRM 612 glass standard reference material using Q-switched UV laser energy of 2 mJ and a 5 Hz repetition rate demonstrates: (1) a linear element response factor throughout the mass spectrum, suggesting limited fractionation during laser ablation; (2) a high sensitivity and very low background noise for most elements of interest; (3) limits of detection ranging from 3 ng g-1 for Sc to 300 pg g-1 for U; (4) a flat topped peak shape suitable for precise isotopic measurements; and (5) a flat bottomed crater geometry which permits progressive ablation for the analysis of thin sections. Average precision and accuracy estimates based on replicate analyses of synthetic NIST standard reference material and USGS BCR-2G glasses are below 10% for most elements. 相似文献
76.
Spring frosts are feared by farmers, fruit growers, and wine growers as they can cause significant damage to crops when they occur during the development of the plants. In the second half of April 2017, following a very warm period that had caused premature vegetation growth, a cold air mass from the Arctic penetrated central and western Europe, causing severe damage to natural and cultivated vegetation over broad areas. Here, we analyze how exceptional this event was in Switzerland and Germany in relation to the accumulated growing degree days (GDD), used as a proxy for plant phenology advancement. Although this damaging frost was not the latest on record in terms of calendar days, our results show that it was, in some regions, unprecedented in relation to the accumulated warmth during the preceding period, at least since the beginning of instrumental temperature records (1864). Our results also highlight how global warming has considerably increased the number of days with mean temperature above 5 °C in late winter and early spring, especially since 1970 (+?16.8?±?4.7 °C days decade?1). However, in spite of earlier spring phenology due to climate warming, our results suggest that the risk of damaging frost events to vegetation has remained unchanged over the last 150 years in lowlands of Switzerland and Germany, due to the concurring earlier occurrence of the last potentially damaging frosts (about ??20 days since 1864). Our analyses reveal therefore that the April 2017 damaging frost was a true outlier in terms of risk of frost damage to plants. 相似文献
77.
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79.
Detailed reservoir models routinely contain 106–108 grid blocks. These models often cannot be used directly in a reservoir simulation because of the time and memory required for solving the pressure grid on the fine grid. We propose a nested gridding technique that efficiently obtains an approximate solution for the pressure field. The domain is divided into a series of coarse blocks, each containing several fine cells. Effective mobilities are computed for each coarse grid block and the pressure is then found on the coarse scale. The pressure field within each coarse block is computed using flux boundary conditions obtained from the coarse pressure solution. Streamline-based simulation is used to move saturations forward in time. We test the method for a series of example waterflood problems and demonstrate that the method can give accurate estimates of oil production for large 3D models significantly faster than direct simulation using streamlines on the fine grid, making the method overall approximately up to 1,000 times faster than direct conventional simulation. 相似文献
80.