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Abstract: Advanced techniques are examined to observe microstructure of rocks using image analysis combined with methods such as the fluorescent approach and the application of optical characteristics of minerals. Analyzed are discrimination of grains in rocks, distribution patterns of grain orientation in sandstone, changes of grain shape as weathering advances and distribution patterns of microcracks in granite. In Shirahama sandstone, relatively large and flat grains are orientated parallel to the bedding on the plane perpendicular to the bedding, while grains on the plane parallel to the bedding show random patterns. In weathered granite, it is clarified that the grain surface becomes complex as weathering advances and differences among three major mineral species are identified. In Inada granite, intracrystalline cracks predominate over intercrystalline cracks and grain boundary cracks both in total length and number. Furthermore, three types of microcracks show different orientations; the intercrystalline cracks show a dominant orientation which coincides with the orientation of the rift plane, the easiest plane to split, while the intracrystalline cracks and grain boundary cracks show no preferred orientation. 相似文献
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Minoru Ando Tetsuya Nagata Shuji Sato Makoto Watanabe Kunio Itoh Toshihide Kawai Hidehiko Nakaya Yoshiharu Namba Takeshi Takezawa 《Experimental Astronomy》2002,13(3):119-134
We constructed a wide field cryogenic telescope (WFCT) containing a whole Ritchey-Chrétien system and a focal plane array
in a cryostat for near infrared observations to cover the field of view of 0.4°. The telescope has a primary mirror of 220
mm and an engineering grade 256 × 256 InSb array. The optical components such as two mirrors, filters, spiders, and radiation
shield tube are cooled down to 180 K as well as the InSb array to 35 K by a mechanical refrigerator. We show the results of
the background surface brightnesses and the limiting magnitudes at 3.3 and 3.67 μm measured at Sutherland, South Africa. We
describe the on-going upgrade of this instrument, equipped with a 1024 × 1024 ALADDIN InSb science grade array.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Site effects by generalized inversion technique using strong motion recordings of the 2008 Wenchuan earthquake 总被引：3，自引：1，他引：2
The generalized inversion of S-wave amplitude spectra from the free-field strong motion recordings of the China National Strong Motion Observation Network System (NSMONS) are used to evaluate the site effects in the Wenchuan area. In this regard, a total of 602 recordings from 96 aftershocks of the Wenchuan earthquake with magnitudes of M3.7-M6.5 were selected as a dataset. These recordings were obtained from 28 stations at a hypocenter distance ranging from 30 km to 150 km. The inversion results have been verified as reliable by comparing the site response at station 62WUD using the Generalized Inversion Technique (GIT) and the Standard Spectral Ratio method (SSR). For all 28 stations, the site predominant frequency F p and the average site amplification in different frequency bands of 1.0–5.0 Hz, 5.0–10.0 Hz and 1.0–10.0 Hz have been calculated based on the inversion results. Compared with the results from the horizontal-to-vertical spectral ratio (HVSR) method, it shows that the HVSR method can reasonably estimate the site predominant frequency but underestimates the site amplification. The linear fitting between the average site amplification for each frequency band and the V s20 (the average uppermost-20 m shear wave velocity) shows good correlation. A distance measurement called the asperity distance D Aspt is proposed to reasonably characterize the source-to-site distance for large earthquakes. Finally, the inversed site response is used to identify the soil nonlinearity in the main shock and aftershocks of Wenchuan earthquake. In ten of the 28 stations analyzed in the main shock, the soil behaved nonlinearly, where the ground motion level is apparently beyond a threshold of PGA > 300 cm/s2 or PGV > 20 cm/s, and only one station coded 51SFB has evidence of soil nonlinear behavior in the aftershocks. 相似文献
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Limestone quarries where slaked lime is produced for steel makers have been urged to reduce the concentration of phosphorus in their products. In a few quarries in Japan, limestone blocks with low concentrations are blended with limestone blocks with high concentrations to stay below the limit of permitted phosphorus quality. The life of the quarry is extended as long as possible by this blending. Some quarries have a geological database with accurate records of the operations for phosphorus adjustment.However, the combination problem of these blocks typically is addressed by Dynamic Programming; that is, all combinations of possible limestone blocks are examined in the solving process; the combination numbers are so huge that the optimum combination cannot be solved in practical process times. Although it took 8 hours to solve for 600 blocks with a 2GHz high performance personal computer, it would take more than 36 days to approximately solve for 1200 blocks, and 3,378 days are estimated to solve 2,400 blocks. Therefore, a Genetic Algorithm was used to try and work out the optimum combination. First, blocks that can be removed are selected in the quarry and their removal sequence makes the genotype. The Order-base or the Grefenstette method was applied to avoid generating lethal genes in crossover. The fitness value was estimated by the number of products that included less than the permitted concentration of phosphorus.The GA process took less than 3 hours to solve for 1,200 blocks. Because the processing time is almost proportional to the block numbers, this GA method is practical in large quarries. Moreover, this method is easy to apply to other conditions in mining plans, such as environmental protection, noise prevention and eyesore problems. These problems are becoming important factors in quarries near towns in Japan. 相似文献
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The examination of fracturing process subjected to triaxial compression test in Inada granite 总被引：1，自引：0，他引：1
Takashi Nishiyama Youqing Chen Hiromu Kusuda Toshihide Ito Katsuhiko Kaneko Haruyuki Kita Toshinori Sato 《Engineering Geology》2002,66(3-4):257-269
The behavior of a granite subject to a triaxial compression test ranging from the prefailure stage to the postfailure stage was studied using a fluorescent technique from the geological point of view. Microscopic observations of the specimens at different stages showed changes in the failure process. The start of formation of new microcracks paralleled the compression direction through their propagation until the onset of faulting and ended with the failure of shear zones after the strength failure point. Pores chiefly identified in the feldspar increased in length and width in the early stages, but not in number. It seems that the effect of pore spaces did not have any effect of failure. The microcracks generated on angular edges of quartz or feldspar grains and around biotite grains with increasing compression force. The phenomenon appearing on the crystal boundaries among biotite and quartz or feldspar agrees with the result calculated based on the theory on stress fields with ellipsoidal inhomogeneity suggested by Eshelby. 相似文献
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