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排序方式: 共有563条查询结果,搜索用时 375 毫秒
1.
将模糊化(拓扑)导算子进行了公理化,并且给出了若干模糊化(拓扑)导算子的刻画;同时建立了模糊化(拓扑)导算子和模糊化(拓扑)闭包算子之间的关系。 相似文献
2.
湍流数值模拟中封闭模式应用的局限性 总被引:1,自引:0,他引:1
通过对琼州海峡的潮流场特征进行数值模拟,指出了选择不同的特征混合长度表达式对数值模拟结果的影响,表明了基于特征混合长度理论的流封闭模式在近海湍流数值模拟中应用的局限性。 相似文献
3.
将一个三维湍能封闭模型应用于开阔海区的风暴潮,通过数值计算探讨了Taylor底摩擦二次率的拖曳系数随空间的分布及拖曳系数与水深、海底粗糙度、风向和风速等因素的关系。本文对底摩擦二次率的可靠性做了评价。 相似文献
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Deep structure of the Nojima Fault, southwest Japan, estimated from borehole observations of fault-zone trapped waves 总被引:1,自引:0,他引:1
To estimate the deep structure of the southern part of the Nojima Fault, southwest Japan without the influence of near-surface structures, we analyzed the Love-wave-type fault-zone trapped waves (LTWs) recorded by a borehole seismometer at 1800 m depth. We examined the polarization, dispersion, and dominant frequency of the wavetrain following the direct S-wave in each seismogram to identify the LTW. We selected eight candidates for typical LTWs from 462 records. Because the duration of the LTW increases with hypocentral distance, we infer that the low velocity fault-zone of the Nojima Fault continues towards the seismogenic depth. In addition, since the duration of the LTW increases nonlinearly with hypocentral distance, we infer that the S-wave velocity of the fault-zone increases with depth. The location of events showing the LTW indicates that the fault-zone dips to the southeast at 75° and continues to a depth of approximately 10 km. We assumed a uniform low-velocity waveguide to estimate the average structure of the fault-zone. We estimated the average width, S-wave velocity, and Qs of the fault-zone by comparing an analytical solution of the LTW with measured data. The average width, S-wave velocity, and Qs of the fault-zone are 150 to 290 m, 2.5 to 3.2 km/s, and 40 to 90, respectively. Hence the fault-zone structure with a larger width and smaller velocity reduction than the fault-zone model estimated by previous surface observation is more suitable to represent the average fault-zone structure of the Nojima fault. The present study also indicated that the shallow layers and/or a shallow fault-zone structure drastically changes the characteristics of the LTW recorded at the surface, and therefore cause a discrepancy in the fault-zone model between the borehole observation and surface observation. 相似文献
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运用烃类勘察地球化学方法,对鄂尔多斯盆地南部彬县大佛寺井田钻遇中休罗统煤层的耽钻孔,进行了垂向剖面多指标的综合地球化学研究。结果表明:剖面中所有岩样中的烃类物质均为热解烃生成初期演化阶段的煤成烃产物,具明显的同一性;由煤层至地表黄土,所有岩样中的烃类呈明显的、规律性垂直向上运移。这证实地下煤层烃类在近地表具有很好的地球化学信息显示,利用勘察地球化学方法找煤/煤层气是可行的。 相似文献
9.
In Italy, the horizontal stress directions are well constrained in many regions, but the tectonic regime is not well known because the stress magnitudes are unknown. Our intention is to improve the knowledge of crustal stress in Italy, both at shallow depth and in low seismicity areas. Therefore, we inferred the tectonic regime from the comparison between the depth of breakout occurrence and the physical properties of the rocks in 20 boreholes. The critical value of the maximum horizontal stress, for which the effective tangential stress at the borehole wall overcomes the rock strength to form breakouts, could be computed from rock strength and density. Comparing the theoretical stress distributions for different tectonic regimes with the depth distribution of breakout occurrence, it is possible to infer the tectonic regime that fits best to the breakout depth distribution. We investigated boreholes up to 6 km deep located in different tectonic environments over the Italian peninsula: the Po Plain, the Apenninic chain, the Adriatic foredeep and the Tyrrhenian Quaternary volcanic region. These wells are characterised by breakout data of good quality (A, B and C, according to World Stress Map quality ranking system). The results are in general agreement with the style of faulting derived from earthquake focal mechanisms and other stress indicators. Our results show a predominance of a normal faulting (NF) regime in the inner Apennines and both normal faulting and strike–slip faulting (SS) style in the surrounding regions, possibly also associated with changes in the tectonic regime with depth. 相似文献
10.
三峡工程大江截流的水文技术 总被引:2,自引:0,他引:2
鉴于三峡工程大江截流水深大,流量大,工期紧,特别是截流过程中要考虑不断航因素,因此,在大江截流和二期围堰阶段的施工进程中,应充分考虑到各方面的因素,尽可能采取一切减少大江截流和二期围堰施工难度的手段和措施,其中水文测验,水文气象预报,河道观测,水文分析与计算和水力学计算等水文工作则是为顺利实施高质量大江截流的重要条件。 相似文献