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介绍了山东数字地震台网基本情况,计算了40个测震台站台基背景噪声,利用Welch方法计算噪声功率谱密度（PSD）,进而计算地震台台基1—20 Hz地动噪声均方根值（RMS）和有效动态观测范围。根据计算结果,依照《地震台站观测环境技术要求》,对山东测震数字台网40个参评测震台站进行背景噪声级别分类,并分析不同台站背景噪声水平较低的原因,以期为测震台网的优化建设提供数据支持。 相似文献
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基于北京市测震台网连续三分量地震计波形数据，计算28个测震台站台基噪声，利用Welch方法计算噪声功率谱密度（PSD），进而计算地震台台基1-20 Hz地动噪声均方根值（RMS）和观测动态范围。结果表明，依照《地震台站观测环境技术要求》，北京市测震台网中有11个Ⅰ类台、9个Ⅱ类台、6个Ⅲ类台、2个Ⅳ类台。通过分析北京市测震台网数字地震台背景噪声水平，为测震台网的规划建设提供数据支持。 相似文献
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山西数字测震台站观测动态范围和台基背景噪声分析 总被引：2，自引：0，他引：2
《山西地震》2015,(4)
通过对山西数字测震台网台基背景噪声的计算和分析,得出各台基背景噪声地动速度均方根值(RMS)、有效测量动态范围、噪声信号功率谱。该研究结果为山西省主动震源技术发展和应用提供基础资料,也为测震台网的规划建设提供理论依据。 相似文献
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新疆数字地震台站观测动态范围和台基噪声的分析 总被引：2，自引：0，他引：2
介绍了新疆数字地震台仪器的配置,对新疆23个数字地震台站台基噪声进行分析计算。台站的观测动态范围,反映了观测仪器本身的性能和台基环境干扰背景的水平,有效动态范围大小反映记录地震信号的最大能力。台站(台网)的监测能力不仅取决于仪器的性能,而且还与台基的噪声背景有关。得出了各地震台台基的脉动噪声的均方根值、观测动态范围、地噪声功率谱。有效观测动态范围的大小与数字地震仪的种类和配置有关。新疆23个数字地震台中的21个台的台基地动噪声在1~20 Hz内符合中国数字测震台网技术规程的要求,而另外2个台,即二宫和石河子数字地震台没有达到规定指标。 相似文献
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地震台站台基噪声功率谱概率密度函数Matlab实现 总被引：3，自引：3，他引：0
选取2015年四川数字测震台网中筠连和华蓥山地震台记录的垂直分向连续波形数据，利用Matlab软件，计算地震台站台基噪声功率谱概率密度函数，分析地震台站环境噪声特征。结果表明，台站环境噪声功率谱密度概率密度分布对地震事件波形（体波、面波）、人为噪声（台站周围人为活动、车辆及机器噪声等高频干扰）、系统瞬变（数据丢失、地震计小故障）以及仪器标定信号等反映较好。使用台基噪声功率谱概率密度函数方法，有利于监测地震台站数据记录，提高观测数据质量。 相似文献
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《国际泥沙研究》2014,(4)
正Director:Shangfu Kuang,China Vice-directors:Chunhong Hu,China Duihu Ning,China Guangquan Liu,China The International Research and Training Center on Erosion and Sedimentation(IRTCES)was jointly set up by the Government of China and UNESCO on July 21,1984.It aims at the promotion of international exchange of knowledge and cooperation in the studies of erosion and 相似文献
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《中国科学:地球科学(英文版)》2014,(3)
正SCIENCE CHINA Earth Sciences,an academic journal cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press and Springer,is committed to publishing high-quality,original results in both basic and applied research. 相似文献
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Richard D. Hey 《地球表面变化过程与地形》1979,4(1):59-72
Feedback mechanisms, which operate upstream through drawdown and backwater effects and downstream through sediment discharge are responsible for channel evolution. By combining these mechanisms with channel processes it euables a dynamic process-response model to be developed to simulate the initial evolution of straight gravel-bed channels. When erosion commences on a land surface, sediment entrained in the headwater reach by hydraulic action is selectively transported, deposited and reworked. This produces a damped oscillation between degradation and aggradation as the channel and valley respond to spatial and temporal variations in sediment calibre and hydraulic conditions. The initial cut and fill phases are responsible for valley incision and floodplain development while secondary and subsequent activity can produce river terraces. Eventually sediment entrainment in the headwaters declines as slopes are reduced. Subsequent channel evolution is relatively insignificant because it is dependent on local weathering activity producing material that can be transported on declining slopes. Therefore landforms produced during the initial phase of development, when local weathering was non-limiting, dominate the landscape. 相似文献
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Based on relocating the Jiujiang-Ruichang earthquake sequence which occurred on November 26, 2005 in Jiangxi Province with the double-difference （DD） algorithm and master event technique, the paper discusses the focal mechanism of the main shock （MsS.7） and the probable seismo-tectonics. The precise relocation results indicate that the average horizontal error is 0.31kin in a EW direction and 0.40kin in a NS direction, and the average depth error is 0.48kin. The focal depths vary from 8kin to 14kin, with the predominant distribution at 10kin - 12kin. The epicenter of the main shock is relocated to be 29.69^oN, 115.74^oE and the focal depth is about 10.Skin. Combining the predominant distribution of the earthquake sequence, the focal mechanism of the main shock and the tectonic conditions of N-E- and NW-strike faults growth in the seismic region, we infer that the main shock of the earthquake sequence was caused by a NW striking buried fault in the Rnichang basin. The nature of seismic faults needs to be further explored. 相似文献
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《水文科学杂志》2013,58(6)
Abstract The western reservoirs represent the principal groundwater system in Morocco. Demographic, industrial and agricultural developments during the last decade have markedly altered groundwater quality. The Mamora coastal aquifer system is among the Atlantic systems which are most heavily threatened by pollution. Agricultural and industrial activities, and rapid urban growth contribute to the pollution of the groundwater. Contamination transport is facilitated by a high permeability of the aquifer formations. In order to assess the actual groundwater quality of the Mamora aquifer and to understand the influence of the factors generating the pollution, an extensive multidisciplinary research programme is in progress, with hydrochemistry and microbiology playing essential roles. The present paper concerns the spatial distribution of physico-chemical parameters in the groundwater, subjected to domestic, industrial and agricultural pollution. Fifty-seven samples were analysed for several parameters (Ca2+, Mg2+, Na+, K+, Cl?, SO4 2?, HCO3 ?, NO3 ?, pH, electrical conductivity and temperature). The microbiological analysis of 143 samples reveals the presence of four kinds of indicator bacteria in the groundwater resources: faecal Streptococci, faecal coliform, Escherichia coli and Clostridium. The physico-chemical results and bacteriological monitoring show that the nitrate and bacteria concentrations exceed the maximum admissible levels, notably around pumping stations in the sectors of Sidi Taibi, Sidi Ahmed Taleb and Aïn Sbaâ. Contamination is generated by uncontrolled anthropogenic activities and accentuated by the high intrinsic vulnerability of the aquifer system. Several parameters appeared to exceed admissibility standards. Measures are recommended to prevent groundwater pollution in the region. 相似文献
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K.-G. Malle 《洁净——土壤、空气、水》1992,20(4):196-204
Zinc in the Environment. In 1990 the world production of zinc ammounted to 7 Mio. metric tons. The main areas of application were: galvanization, alloys like brass and zinc metal. The content in the earth crust varies between 10–300 ppm zinc with a mean of 70 ppm. Uncontaminated surface waters contain less than 10 mg/m3 zinc. Apart from civilization air contains 1–10 ng zinc per m3. These background concentrations are exceeded by orders of magnitude in zinc deposit areas and where anthropogenic influences predominate. Accumulation can occur in sediments and sewage sludge. Molluscs and Algae also accumulate zinc. Zinc is essential for live. With normal food the zinc supply of man is just sufficient. Bioaccumulation of zinc towards man or chronic oversupply of man is not known. Zinc has no teratogenic or mutagenic effects, a suspicion on a carcinogenic effect proved wrong. In stockbreeding and plant cultivation a minimum supply of zinc is necessary. Plants are relatively less sensitive against higher soil contents of zinc. Considering the toxicological and ecotoxicological effects of zinc in the environment, the critical organismens are marine invertebratae like tubifex, daphnia, gammarus and algae. But normally only a minor part of the total zinc contest is biologically available, depending on salt content and pH of the waters. 相似文献