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381.
Introduction In recent years, with the development of earthquake observation technology, increasing ofobservation stations and improvement of observation instruments which are digitalized and con-nected by network, a great deal of data is recorded, to some extend, which brings difficulty for usto manage and store them. It leads to traditional methods, which use the file system to managemass data, could not satisfy our requirement, and it is necessary to find a new method in place oftradit… 相似文献
382.
On the basis of Biot dynamic theory, an analytic solution of two-dimensional scattering and diffraction of plane SV waves by circular cylindrical canyons in a half space of saturated porous media is presented in this paper for the first time. The solution is obtained by employing the Fourier–Bessel series expansion technique. Parametric studies had been carried out, which includes: the angle of incidence, the frequency of the incident SV wave, the porosity of saturated porous medium and the stiffness and Poisson's ratio of the solid-skeleton. All the outcomes are useful for the seismic analysis of the surface topography conditions. 相似文献
383.
Zhao Cuiping 《中国地震研究》2005,19(4):381-390
INTRODUCTIONThe study of source parameters is usually based oninversionfromobservational seismic waveformdata.Seismic wave affected bygeometric spreading,inelastic attenuation,scatteringandsite effects ofthe mediumontheir way fromsource to station.Therefo… 相似文献
384.
根据联合国有关机构发布的公报和世界各国近年来的学术研究情况,整理出了近期水文学科在地表水、地下水、水质、水资源系统、大气~土壤~植被、大陆侵蚀、冰雪、遥感技术和示踪技术等领域的热门研究课题,在一定程度上反映了当前国际上水文学科的研究和发展方向,对国内同行有一定的参考价值。 相似文献
385.
386.
库水位变化对库岸边坡稳定性的影响 总被引:3,自引:0,他引:3
在假定坡体孔隙水水位为水平线且不考虑渗透作用影响的基础上,基于极限平衡法考察了水位上升及下降的快慢对边坡安全系数的影响。对比计算表明:在水位缓慢变化即坡体内外水位线等高的条件下,边坡的安全系数随着水位坡高比的增大先略减小后急剧增大,且在水位坡高比为0.3处取得最小值,在边坡完全淹没于水中时取得最大值。当边坡完全淹没于水中后,水位高于坡顶的多少对边坡安全系数没有影响;在水位骤降或陡升条件下,相同库水位对应的边坡安全系数基本上均小于水位缓慢变化情况下的安全系数,故工程实际中无论是排水还是蓄水,都应尽量保持水位缓慢变化,这样才能使边坡处于较安全的状态。 相似文献
387.
A remarkable invariance in the ratio of 1,3-dimethylcarbazole (DMC) to 1,6-DMC was discovered in crude oils from the Pearl River Mouth Basin, South China Sea. The remarkably invariant ratio is kept at a constant of about unity regardless of their concentrations, sources or maturities for the sampies. In combination with the molecular structures of 1,3- and 1,6-DMCs, the invariance might indicate that the nitrogen compounds share a common precursor with a skeleton of 1-methylcarbazole and are formed through methylation at C3 and C6 with an essentially identical rate. 相似文献
388.
389.
Wenzhi Zhao Shuichang Zhang Feiyu Wang Jianping Chen Zhongyao Xiao Fuqing Song 《Organic Geochemistry》2005,36(12):1602-1616
Oil and gas exploration in eastern Tarim Basin, NW China has been successful in recent years, with several commercial gas accumulations being discovered in a thermally mature to over-mature region. The Yingnan2 (YN2) gas field, situated in the Yingnan structure of the Yingjisu Depression, produces gases that are relatively enriched in nitrogen and C2+ alkanes. The δ13C1 (−38.6‰ to −36.2‰) and δ13C2 values (−30.9‰ to −34.7‰) of these gases are characteristic of marine sourced gases with relatively high maturity levels. The distributions of biomarkers in the associated condensates suggest close affinities with the Cambrian–Lower Ordovician source rocks which, in the Yingjisu Sag, are currently over-mature (with 3–4%Ro). Burial and thermal maturity modeling results indicate that paleo-temperatures of the Cambrian–Lower Ordovician source rocks had increased from 90 to 210 °C during the late Caledonian orogeny (458–438 Ma), due to rapid subsidence and sediment loading. By the end of Ordovician, hydrocarbon potential in these source rocks had been largely exhausted. The homogenization temperatures of hydrocarbon fluid inclusions identified from the Jurassic reservoirs of the YN2 gas field suggest a hydrocarbon emplacement time as recent as about 10 Ma, when the maturity levels of Middle–Lower Jurassic source rocks in the study area were too low (<0.7%Ro) to form a large quantity of oil and gas. The presence of abundant diamondoid hydrocarbons in the associated condensates and the relatively heavy isotopic values of the oils indicate that the gases were derived from thermal cracking of early-formed oils. Estimation from the stable carbon isotope ratios of gaseous alkanes suggests that the gases may have been formed at temperatures well above 190 °C. Thus, the oil and gas accumulation history in the study area can be reconstructed as follows: (1) during the late Caledonian orogeny, the Cambrian–Lower Ordovician marine source rocks had gone through the peak oil, wet gas and dry gas generation stages, with the generated oil and gas migrating upwards along faults and fractures to form early oil and gas accumulations in the Middle–Upper Ordovician and Silurian sandstone reservoirs; (2) since the late Yanshanian orogeny, the early oil accumulations have been buried deeper and oil has undergone thermal cracking to form gas; (3) during the late Himalayan orogeny, the seals for the deep reservoirs were breached; and the gas and condensates migrated upward and eventually accumulating in the relatively shallow Jurassic reservoirs. 相似文献
390.
科技成果成功转化的主要标志是其产品的市场畅销度。产品的畅销度由于受各种内外部不确定因素影响,具有随机不确定性。基于这种随机不确定性,运用Markov chain对其产品进行市场预测,并通过实证分析说明其有效性,为科技成果的转化提供具体可行的定量依据。 相似文献