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971.
972.
973.
Introduction The study mainly focused on tidal information, i.e. earth tide in the continuous deformationdata processing and analysis before. And the analysis methods used were specially for earth tideonly. As to the medium-long period and non-tidal information, fitting and filtering are not the bestmethods. Because they are not able to reflect the variation process of frequency information withtime and to distinguish and extract more earthquake information, although they can eliminateyea… 相似文献
974.
975.
引水式水电站深埋长引水隧洞对电站下游水温的影响直接关系到下游水生物生境.采用k-ε模型,结合能量传输方程建立了引水隧洞三维水温预测模型,并在利用原型观测资料验证模型的基础上,对拟建的锦屏二级引水隧洞的水温进行了预测.预测结果表明,由于雅砻江上拟建的锦屏二级隧洞洞径与过流量较大,水流在隧洞内滞流时间短,水温升高不明显.由于模型采用隧洞实际空间布置数据,建立包括混凝土衬砌区域在内的三维空间计算域,同时考虑温度场与流场的相互影响,实现了对温度场的精确模拟,从而可为水电站设计和水生物保护提供科学依据. 相似文献
976.
In this paper, observation data in 25 GPS reference stations of China have been analyzed by calculating GPS position coordinate
time-series with GIPSY. Result shows there is an obvious trend variation in such time-series. The trend variations of time
series along the longitude and latitude coordinate reflect the motion of each position in the global-plate, in which the trend
variation in the vertical direction reveals some large-scale construction information or reflects the local movement around
the positions. The analysis also shows that such time-series have a variation cycle of nearly 1.02 a, but the reason still
remains to be further studied. At the end of this paper, response of the time-series of M
S=8.1 Kunlunshan earthquake was analyzed, and the seismogenic process of M
S=8.1 Kunlunshan earthquake, according to the time proceeding and the feature of anomaly, was divided into 3 phases—changes
in blocks with forces, strain accumulation, quick accumulation and slow release of energy. At the initial stage of seismogenic
process of M
S=8.1 earthquake and at the imminent earthquake, coseismic process as well as during the post earthquake recovery, anomaly
in vertical direction is always in a majority. The anomalous movement in vertical direction at the initial stage resulted
in a blocking between faults, while at the middle stage of seismogenic process, the differential movement between blocks are
in a majority, which is the major reason causing energy accumulating at the blocking stage of faults.
Foundation item: National Natural Science Foundation of China (40074024 and 40304002). 相似文献
977.
Hydrochemistry of urban groundwater in Seoul, South Korea: effects of land-use and pollutant recharge 总被引:1,自引:0,他引:1
Byoung-Young Choi Seong-Taek Yun Soon-Young Yu Pyeong-Koo Lee Seong-Sook Park Gi-Tak Chae Bernhard Mayer 《Environmental Geology》2005,48(8):979-990
The ionic and isotopic compositions (δD, δ18O, and 3H) of urban groundwaters have been monitored in Seoul to examine the water quality in relation to land-use. High tritium contents
(6.1–12.0 TU) and the absence of spatial/seasonal change of O–H isotope data indicate that groundwaters are well mixed within
aquifers with recently recharged waters of high contamination susceptibility. Statistical analyses show a spatial variation
of major ions in relation to land-use type. The major ion concentrations tend to increase with anthropogenic contamination,
due to the local pollutants recharge. The TDS concentration appears to be a useful contamination indicator, as it generally
increases by the order of forested green zone (average 151 mg/l), agricultural area, residential area, traffic area, and industrialized
area (average 585 mg/l). With the increased anthropogenic contamination, the groundwater chemistry changes from a Ca–HCO3 type toward a Ca–Cl(+NO3) type. The source and behavior of major ions are discussed and the hydrochemical backgrounds are proposed as the basis of
a groundwater management plan. 相似文献
978.
979.
980.
青藏高原东北部强降水天气过程的气候特征分析 总被引:7,自引:2,他引:7
根据青藏高原东北部地区降水特点,定义青藏高原强降水概念,利用该区域内各测站自建站以来的气象资料,分析青藏高原强降水的时空分布特征和相对强度。结果表明:青藏高原东北部地区强降水的分布明显受到地形影响,年降水量和强降水次数自东向西呈阶梯性递减趋势,分别在青藏高原东北部的外流河谷地区和东南部四川北部地区存在大值中心;外流河谷地区两侧山脉的年降雨量较大,年均强降水日数较多,河源处相对较小,具有河谷地形的特点;青藏高原强降水的时段集中,雨强大,局地性强,且具有夜发性的特点;强降水日数和站数具有明显的年代际变化特征,近10年来出现区域性强降水的次数增加;青藏高原东北部外流河谷地区强降水的相对强度较大,同长江以南地区暴雨相对强度差不多。 相似文献