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91.
Introduction The Western Kunlun Mountain Pass M=8.1 earthquake occurred on November 14, 2001 is the other M=8 earthquake occurred 50 years after Dangxiong, Tibet M=8.0 earthquake in Chinese mainland. The earthquake has caused the attention of the seismologists in the following aspects: 1) The fracture length is more than 400 km, which is far away from the estimated length by the statistic empirical function between the magnitude and the fracture length (WANG, et al, 2002); 2) The aftersh… 相似文献
92.
高孟潭 《地震学报(英文版)》2003,16(6):639-645
1 Background of the new national seismic zoning map The policy of seismic disaster mitigation in the Chinese mainland is prevention first. According to the law, the earthquake design for ordinary structures must fit the demand of national seismic zoning map. Seismic zoning map is the basis of the earthquake design (TANG, 1998; WU, et al, 1998). The seismic zoning map must be updated with the progress in methodology and accumula-tion of the data. There are three generations of national seis… 相似文献
93.
滑带土粘土矿物定向性的x射线衍射及其对滑坡的作用 总被引:6,自引:1,他引:6
本文首先论述了粘土矿物颗粒定向排列测定的基本原理并提出粘土矿物定向性定量评价方法,然后根据实例—庙上北滑坡的滑带土粘土矿物的X射线衍射结果,进行定向性定量分析计算,得出滑带土粘土矿物颗粒的定向度为弱到中等定向,并以中等定向为主。因而在水的往返作用下,滑带土具一定的胀缩性及胀缩的不均匀性,再加上粘土矿物本身亦具有的胀缩性及胀缩的可逆性和循环性,故导致滑带土抗剪强度和结构强度不断降低,大大影响斜坡的稳定性。 相似文献
94.
From geometry to dynamics of microstructure: using boundary lengths to quantify boundary misorientations and anisotropy 总被引:1,自引:0,他引:1
John Wheeler Z. Jiang D. J. Prior J. Tullis M. R. Drury P. W. Trimby 《Tectonophysics》2003,376(1-2):19-35
The microstructure of a quartzite experimentally deformed and partially recrystallised at 900 °C, 1.2 GPa confining pressure and strain rate 10−6/s was investigated using orientation contrast and electron backscatter diffraction (EBSD). Boundaries between misoriented domains (grains or subgrains) were determined by image analysis of orientation contrast images. In each domain, EBSD measurements gave the complete quartz lattice orientation and enabled calculation of misorientation angles across every domain boundary. Results are analysed in terms of the boundary density, which for any range of misorientations is the boundary length for that range divided by image area. This allows a more direct comparison of misorientation statistics between different parts of a sample than does a treatment in terms of boundary number.The strain in the quartzite sample is heterogeneous. A 100×150 μm low-strain partially recrystallised subarea C was compared with a high-strain completely recrystallised subarea E. The density of high-angle (>10°) boundaries in E is roughly double that in C, reflecting the greater degree of recrystallisation. Low-angle boundaries in C and E are produced by subgrain rotation. In the low-angle range 0–10° boundary densities in both C and E show an exponential decrease with increasing misorientation. The densities scale with exp(−θ/λ) where λ is approximately 2° in C and 1° in E; in other words, E has a comparative dearth of boundaries in the 8–10° range. We explain this dearth in terms of mobile high-angle boundaries sweeping through and consuming low-angle boundaries as the latter increase misorientation through time. In E, the density of high-angle boundaries is larger than in C, so this sweeping would have been more efficient and could explain the relative paucity of 8–10° boundaries.The boundary density can be generalised to a directional property that gives the degree of anisotropy of the boundary network and its preferred orientation. Despite the imposed strain, the analysed samples show that boundaries are not, on average, strongly aligned. This is a function of the strong sinuosity of high-angle boundaries, caused by grain boundary migration. Low-angle boundaries might be expected, on average, to be aligned in relation to imposed strain but this is not found.Boundary densities and their generalisation in terms of directional properties provide objective measures of microstructure. In this study the patterns they show are interpreted in terms of combined subgrain rotation and migration recrystallisation, but it may be that other microstructural processes give distinctive patterns when analysed in this fashion. 相似文献
95.
S. K. Deb M. H. Manghnani K. Ross R. A. Livingston P. J. M. Monteiro 《Physics and Chemistry of Minerals》2003,30(1):31-38
A Raman scattering and X-ray diffraction study of the thermal decomposition of a naturally occurring, ettringite-group crystal
is presented. Raman spectra, recorded with increasing temperature, indicate that the thermal decomposition begins at ≈55 °C,
accompanied by dehydration of water molecules from the mineral. This is in contrast to previous studies that reported higher
temperature breakdown of ettringite. The dehydration is completed by 175 °C and this results in total collapse of the crystalline
structure and the material becomes amorphous. The Raman scattering results are supported by X-ray diffraction results obtained
at increasing temperatures.
Received: 9 July 2001 / Accepted: 14 August 2002 相似文献
96.
山东省龙卷风发生的气候特征 总被引:9,自引:0,他引:9
根据藤田-皮尔森强度分类法对1950年~2000年山东省出现的351次龙卷风进行分类,其中F0级61次,F1级256次,F2级34次。山东半岛、鲁中、鲁南出现次数较多,鲁西北较少。1950~1972年发生次数明显高于1973~2000年。龙卷风发生存在明显的季节变化,夏季发生较多。龙卷风主要发生于午后至傍晚,多数龙卷风仅能维持几分到十几分钟。 相似文献
97.
98.
99.
Advances in energy-dispersive X-ray fluorescence 总被引:1,自引:0,他引:1
Utz Kramar 《Journal of Geochemical Exploration》1997,58(1):73-80
Recently, two new instruments for X-ray fluorescence analysis (XRF) with interesting features for geochemical applications came to the market. Both instruments were designed to improve the peak to background ratio, the principal factor limiting the sensitivity of XRF. Total reflection XRF (TXRF) was designed to analyse extremely small sample amounts. An instrument, using polarised X-rays (P-XRF) for excitation, is designed to reduce scattered background in spectra of bulk samples. The performance of both instruments was compared with conventional XRF-methods and ICP/MS. Results for GXR-1, GXR-2, GXR-3, GXR-4 and GXR-6 obtained with TXRF and P-XRF are in good agreement with literature data. The effective amount of sample, analysed by TXRF was 200 μg only and detection limits of ~ l μg/g were achieved. P-XRF shows considerable improved detection limits (0.25–0.5 μg/g) for bulk samples for elements with atomic numbers 42–51 (Mo-Sb) compared with conventional XRF-methods. 相似文献
100.
Earthquake magnitude prediction is of vital importance for human safety. The earthquake is a very complicated and non-linear dynamic process. It cannot be described adequately by any deterministic models. In this paper a neural dynamic modelling for earthquake magnitude prediction is reported. Historical records of earthquake magnitude series are used to construct the optimal non-linear dynamic model, and the consequent outcome of the earthquake behaviour is then predicted by this model. In turn, the latest recorded data set can be fed back to improve the accuracy of the neural dynamic model. The modelling of experiments of three earthquake magnitude series in China and Japan and their extrapolated predictions are included in this paper. The values predicted by extrapolation are in good agreement with the historical data. 相似文献