山西数字测震台站SDH专线与3G信道互备方案设计     

高伟亮  殷伟伟  王卓君  李惠玲  吕睿 《山西地震》2018,(1):47-52,56

针对数字测震台站地震观测资料时效性、真实性和准确性的特殊需求,确保山西省测震台站通信传输信道畅通,提出了利用3G网络实现以SDH光纤传输为主、无线3G为辅的双链路备份传输方案。重点介绍该传输方案的原理和实施方法,进行3G路由器并网接入及省台网中心LNS服务器增加PPTP服务的设计与实验。结果表明,基于3G无线VPDN网络可以实现省内SDH专线通信传输信道备份。  相似文献   

The origin of magnetization and geochemical alteration in a fault zone,Kilve, England     

W. G. Bixler  R. D. Elmore  M. H. Engel 《Geological Journal》1998,33(2):89-105

The origin of an apparently syndeformational chemical remanent magnetization (CRM) and geochemical alteration in a fault zone in the Bristol Channel Basin, southwest England, was investigated. Deformation in the fault zone occurs in Jurassic aged, organic-rich limestones and consists of numerous normal and oblique-slip faults and associated folds. Migration of basinal, radiogenic fluids is indicated by elevated ⁸⁷Sr/⁸⁶Sr values for calcite veins that occur throughout the fault zone. Some of the calcite veins contain hydrocarbons sourced from deeper strata. Elevated ⁸⁷Sr/⁸⁶Sr values in the host Jurassic limestones indicate that they were also extensively altered by radiogenic fluids that migrated through microfractures in addition to major fault and fracture planes. Folded and tilted host limestones contain a pervasive secondary CRM residing in magnetite that was acquired during deformation in the Tertiary. The association between this pervasive CRM and the pervasive geochemical alteration is consistent with a genetic connection between the orogenic fluids and the CRM although the timing of CRM acquisition (Tertiary) is not consistent with structural interpretations for the timing of most veining. An alternative remagnetization mechanism which is not triggered by externally derived fluids, such as diagenesis of hydrocarbons, might account for the CRM. Hydrocarbon-bearing veins also contain a CRM that resides in magnetite, although the time for remanence acquisition is not well constrained by field tests. © 1998 John Wiley & Sons, Ltd.  相似文献   

基于解析解的长江口南港悬沙侧向捕集特征分析     

杨忠勇  王钟  程和琴  郭兴杰  曹振轶 《海洋学报》2017,39(5):22-32

为探讨长江口南港的水动力结构及悬沙侧向输运特征,本文从解析解的角度构建了潮汐河口水沙输运数学模型,并将其应用到长江口南港某横断面上。南港水动力主控于半日潮流,余流主要由陆相径流及本地非线性对流项驱动,悬沙分布上北侧副槽远大于南侧主槽,水沙分布的计算结果与实测结果在结构上基本一致。通过输沙函数进一步分析表明,潮流输沙和余流输沙是南港侧向输沙函数的两个主要部分。南港中强劲径流削弱了涨潮流,增强了落潮流,使得向河槽南侧的涨潮流输沙小于向河槽北侧的落潮流输沙,潮流输沙指向河槽北侧。径流驱动的南港侧向余流在涨潮流方向上为一逆时针环流结构,余流输沙指向河槽北侧。扩散输沙指向南侧主槽,因其总是指向悬沙浓度梯度的负方向。在各输沙因子的综合作用下,南港中大量悬沙捕集于河槽北侧,使得河槽北部底层潮平均含沙量值达到最大值。  相似文献   

基于NMM随钻电磁波传输信道特性分析   总被引：1，自引：0，他引：1       下载免费PDF全文

范业活  李威  聂在平  杨志强  孙向阳 《地球物理学报》2016,59(3):1125-1130

基于数值模式匹配法(NMM)与源等效原理,建立了随钻电磁波传输理论模型,可以同时考虑介质的径向和轴向非均质性,便于分析套管、泥浆、高导层、高阻层对信号传输的影响.通过理论计算结果与试验结果对比,验证了理论模型的正确性.在此基础上对地层电阻率、工作频率、套管、泥浆、钻柱导电性、高导层和高阻层对信号传输的影响进行了计算分析.  相似文献   

‘Universal’ recession curves and their geomorphological interpretation     

《Advances in water resources》2014

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Contamination of shallow aquifers by arsenic in upper reaches of Tista river at Siliguri–Jalpaiguri area of West Bengal, India     

Debkumar Bhattacharyya  Pradip Kumar Mukherjee 《Environmental Geology》2009,57(7):1687-1692

Arsenic is present in groundwater at Siliguri–Jalpaiguri area, West Bengal, India. This is the place where Tista river descending from the Himalayas meets the alluvial plain. The area represents alluvial fan and floodplains of Tista, Mahananda-Balasan, Jaladhaka and its tributaries. In the river sediment samples, para- and ferro-magnetic minerals within 0.3–0.05 mm fraction contain 9–80 ppm of arsenic. The study indicates that iron bearing minerals viz. biotite, hornblende as well as iron coated grains of the sediment are major contributors towards arsenic budget. Though magnetite as a mineral shows maximum arsenic content (22 ppm), it is volumetrically not of much significance. Measurement of groundwater collected from tube wells shows up to 0.05 ppm of arsenic. These arsenic contaminated tube wells occur in a linear fashion along the course of the rivers. Moreover, localization of contaminated tube wells coincides with the change of channel gradient as observed in longitudinal section. The study enumerates a cause–effect relationship of arsenic occurrence with river gradient and fluvial sedimentation.  相似文献   

Geological information from telecommunications cable route surveys of the continental shelf     

J. Noad  A. Crosby 《Marine Georesources & Geotechnology》2013,31(4):323-333

Several burial assessment surveys using a seabed plough have been carried out along routes on the United Kingdom continental shelf to assess their potential for cable burial. Detailed information on sediment thicknesses and characteristics within the top meter of the seabed was collected using a survey tool called the Plough Surveyor. Geophysical surveys along these routes have enabled correlation with the plough data. Results include the range of tensions, tension trace characteristics, and typical penetration, and these have been correlated with seabed types and thickness of sediment.  相似文献   

槽波层析成像方法在煤田勘探中的应用——以河南义马矿区为例   总被引：9，自引：4，他引：5       下载免费PDF全文

王伟  高星  李松营  乐勇  胡国泽  历玉英 《地球物理学报》2012,55(3):1054-1062

在地下煤田的开发中,工作面内的小构造、异常体、煤层厚度变化等是需要解决的关键问题,而槽波探测则为这些问题的解决提供了重要的物探方法.本文对河南义马矿区11061工作面进行槽波透射法测量,在巷道显示的煤层厚度变化为1.5~8 m,从理论频散曲线分析速度与厚度关系,确定125 Hz频率槽波主要用于观测厚度约为2~5 m的煤层厚度变化;有效提取了684个频散曲线,并分别拾取了125 Hz时槽波群速度与走时,采用走时层析成像方法获得工作面内煤层速度、厚度以及高应力区分布特征,回采验证了结果的正确性.  相似文献   

Predicting sediment inputs to aquatic ecosystems across England and Wales under current environmental conditions     

A.L. Collins  S.G. Anthony 《Applied geography (Sevenoaks, England)》2008,28(4):281-294

The awareness of water quality issues has never been higher. As part of its continuing strategic diffuse pollution policy support, ADAS recently undertook to identify catchments across England and Wales that could potentially fail recently proposed suspended sediment yield targets under current environmental conditions. The total suspended sediment loads (SSL) delivered to all rivers were assumed to comprise contributions from diffuse sources in the agricultural and urban sectors, as well as from eroding channel banks and point sources represented by sewage treatment works (STWs). Diffuse agricultural sediment loss to rivers was predicted using the PSYCHIC model. Corresponding inputs from diffuse urban sources were estimated on the basis of an Event Mean Concentration (EMC) methodology. Channel bank sediment inputs were calculated using a prototype national scale model, while point source sediment contributions were based on a register of consented effluent discharges. Modelled SSL were validated (r²=68%) against PARCOM data (1999–2003) for the delivery of sediment to different regions of the UK maritime area. The results of the validation were considered to be realistic for a national scale predictor. The modelling exercise suggested that those catchments currently at risk of exceeding proposed suspended sediment yield critical thresholds are largely confined to upland areas across Wales and northwest England and the chalklands of southern and eastern England.  相似文献   

The morphology and hydrology of small spring-dominated channels     

Ronald E. Griffiths  Diana E. Anderson  Abraham E. Springer   《Geomorphology》2008,102(3-4):511-521

Small, low order channels located in wet meadows along the Mogollon Rim of northern Arizona that receive the bulk of their flow from spring discharge exhibit a morphology that differs markedly from channels that receive the bulk of their flow from runoff. These small, spring-dominated channels generally have dense vegetation cover, vertical (or near vertical) banks with flat channel beds that are armored with clasts up to 60 mm. Clasts armoring the spring-dominated channels become mobile at 45 to 85% of the bankfull depth. The lack of fine-grained material in the bed of the spring-dominated channels reflects the small drainage size, lack of fine grain input from the spring, and winnowing affect of the consistent discharge. Minor amounts of large woody debris were present in some of the spring-dominated channels, however, unlike previous studies it does not appear to play a role in the spring-dominated channel morphology. Sinuosity values for spring-dominated channels averaged 1.19, while the average sinuosity values for the runoff-dominated channels, 1.08, were significantly lower. Measured width-to-depth ratios averaged 2.4 in the spring-dominated channels, much lower than the average ratio of 11.6 found for the runoff-dominated channels. The standard deviation of width-to-depth ratios was higher for runoff-dominated channels, reflecting a more variable channel profile. A third channel type, here referred to as hybrid channels, receive significant flow from both springs and runoff. These channels have characteristics that fall between spring-dominated and runoff-dominated channels.Elevation, gradient, organic matter content, and sediment grain size distribution of the wet meadows in which the channels are formed do not exhibit significant differences between channel types, suggesting that these factors are not responsible for the observed differences in channel morphologies. The major differences in controls on the channel morphology found between the spring-dominated and runoff-dominated channels are the discharge regime and the sediment input. The hydrology unique to the spring-dominated channels and the lack of fine-grained sediment input combine to create the observed differences.  相似文献