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51.
52.
对武当山隧道进口处Ⅰ号和Ⅱ号滑坡稳定性主要影响因素进行了分析,采用传递系数法对Ⅰ号和Ⅱ号滑坡在天然及饱和状态下的稳定性进行定量计算,利用Flac3d软件对Ⅰ号滑坡在天然及饱和状态时的应力应变进行数值模拟研究.综合分析认为,降雨入渗是加剧武当山隧道进口处滑坡活动触发因素.为保证襄渝铁路运营安全,建议对Ⅰ号滑坡进行削坡处理,对Ⅱ号滑坡在前缘设置抗滑桩进行处理. 相似文献
53.
设计基于DTU的强振记录终端,采用SOC系列C8051F015型单片机对MEMS加速度计的输出信号进行A/D转换,监测待测体所经受的强振加速度值,并通过DTU内嵌的GPRS无线网络通讯方式将数据发送到远程数据中心.该系统具有体积小,安装与操作方便,免维护等特性. 相似文献
54.
Benedikt Halldorsson Ragnar Sigbjornsson Johannes Schweitzer 《Journal of Seismology》2009,13(1):173-178
A small-aperture, strong-motion array, the ICEARRAY, has been deployed in South Iceland, a region with a history of destructive
earthquakes, some exceeding magnitude 7. The array’s purpose is: (1) monitoring future significant events in the region, (2)
quantifying spatial variability of strong-motion over short distances and (3) shedding light on earthquake source processes.
The number of array stations and their arrangement were based on an optimisation of the shape of the corresponding array transfer
function (ATF). The optimal ICEARRAY configuration comprises 14 stations, has an aperture of ~1.9 km and a minimum interelement
distance of ~50 m and possesses a near-azimuthally independent ATF with a sharp main lobe, negligible sidelobes and a wavenumber
range of 1.5–24 rad/km. Accordingly, the ICEARRAY has the intended capabilities of capturing seismic waves in the frequency
range of 1–20 Hz, which is of main interest to earthquake engineering and engineering seismology applications. 相似文献
55.
56.
The response wavelets for tether tension and the displacement of a package on the end of a tether are derived from a linear, frequency-domain model of vertically tethered systems using inverse fourier transform techniques. These wavelets are convolved with a record of ship displacement to predict the instantaneous tension and displacement to an accuracy of better than 20% for a typical system. Although snap loads are non-linear and the response cannot be calculated while the tether is slack, the onset of zero tension — a precursor to snap loads — is predicted by the wavelet. Thus, extreme and potentially hazardous conditions are foreseeable with the wavelet and this information can be used in real-time to guide operations at sea. 相似文献
57.
首先用二次函数建立了企业用水量与其用水效益的关系,然后根据这种关系,利用拉格朗日乘数法来确定该地区最优化水资源分配方案,并得到了该地区总的用水量与用水效益的关系,最终建立了区域调水中各地区间的调水总量的分配模型。此时原问题转化为一个典型的二次规划问题,结合各个地区的用水效益情况,可实现对各地区、各行业分水。利用假设的理想数据对模型进行检验,取得了较好的结果。对南水北调的实际情况,根据北方6个缺水地区基本的水资源及工农业用水情况进行了实际数据模拟,提出了南水北调的简单分配方案。该模型不仅可以用于区域间调水的优化控制,而且还可应用到其他水资源分配与管理。 相似文献
58.
Quantitative information on vegetation and climate history from the late glacial-Holocene on the Tibetan Plateau is extremely rare. Here, we present palynological results of a 4.30-m-long sediment record collected from Koucha Lake in the Bayan Har Mountains, northeastern Tibetan Plateau. Vegetation change has been traced by biomisation, ordination of pollen data, and calculation of pollen ratios. The application of a pollen-climate calibration set from the eastern Tibetan Plateau to Koucha Lake pollen spectra yielded quantitative climate information. The area was covered by alpine desert/steppe, characteristic of a cold and dry climate (with 50% less precipitation than today) between 16,700 and 14,600 cal yr BP. Steppe vegetation, warm (∼ 1°C higher than today) and wet conditions prevailed between 14,600 and 6600 cal yr BP. These findings contradict evidence from other monsoon-influenced areas of Asia, where the early Holocene is thought to have been moist. Low effective moisture on the northeastern Tibetan Plateau was likely due to high temperature and evaporation, even though precipitation levels may have been similar to present-day values. The vegetation changed to tundra around 6600 cal yr BP, indicating that wet and cool climate conditions occurred on the northeastern Tibetan Plateau during the second half of the Holocene. 相似文献
59.
南水北调东中两线不同水文区降水丰枯遭遇性分析 总被引:25,自引:0,他引:25
南水北调东中两线不同水文区来水的丰枯遭遇性是跨流域水资源调配必须考虑的重要问题。据年、季和月三种不同时间尺度的降水系列分别探讨了华北地区与长江中下游及华北地区与汉江上游来水丰枯的遭遇性。结果表明:不论是华北地区与长江中下游,还是华北地区和汉江上游,其降水丰枯异步频率都略大于丰枯同步频率。在三同步现象中,南北同枯出现的频率较低。就适合调水的4种丰枯遭遇情形统计,华北地区和长江中下游年尺度上的频率总和 相似文献
60.
I.N. Panchishkina G.G. Petrova A.I. Petrov T.V. Kudrinskaja 《Atmospheric Research》2009,91(2-4):238-243
The correlation of mechanical transfer current from the atmosphere to the ground with the process of space charge formation as a result of conductivity current divergence near ground is under discussion in this research. Experimental data of conductivity current and mechanical transfer current acquired at three observation points for different meteorological conditions are analyzed. In particular, the peculiarities of mechanical charge transfer to ground under different stratifications of the surface layer are under discussion. 相似文献