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31.
引入小波分析方法对大坝变形监测数据的处理,实现了对离散型的变形数据的尺度分解,对变形趋势的分析。并且对变形数据在滤波、消噪等方面,对分解层次中的偶然误差特性分析,以及阀值的选取方法进行了比较,表明利用小波变换的方法对变形数据的分析处理是有效、可行的。 相似文献
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Marleen Coetsiers Petra Blaser Kristine Martens Kristine Walraevens 《Environmental Geology》2009,57(5):1155-1168
Aquifers from the same typology can have strongly different groundwater chemistry. Deducing the groundwater quality of less
well-characterized aquifers from well-documented aquifers belonging to the same typology should be done with great reserve,
and can only be considered as a preliminary approach. In the EU’s 6th FP BRIDGE project “Background cRiteria for the IDentification
of Groundwater thrEsholds”, a methodology for the derivation of threshold values (TV) for groundwater bodies is proposed.
This methodology is tested on four aquifers in Flanders of the sand and gravel typology. The methodology works well for all
but the Ledo-Paniselian aquifer, where the subdivision into a fresh and saline part is disproved, as a gradual natural transition
from fresh to saline conditions in the aquifer is observed. The 90 percentile is proposed as natural background level (NBL)
for the unconfined Pleistocene deposits, ascribing the outliers to possible influence of pollution. For the Tertiary aquifers,
high values for different parameters have a natural origin and the 97.7 percentile is preferred as NBL. The methodology leads
to high TVs for parameters presenting low NBL, when compared to the standard used as a reference. This would allow for substantial
anthropogenic inputs of these parameters. 相似文献
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By using GDS dynamic hollow cylinder torsional apparatus, a series of cyclic torsional triaxial tests under complex initial consolidation condition are performed on Nanjing saturated fine sand. The effects of the initial principal stress direction α0, the initial ratio of deviatoric stress η0, the initial average effective principal stress p0 and the initial intermediate principal stress parameter b0 on the threshold shear strain y, of Nanjing saturated fine sand are then systematically investigated. The results show that y, increases as η0, P0 and b0 increase respectively, while the other three parameters remain constant. α0 has a great influence on y,, which is reduced when α0 increases from 0° to 45° and increased when α0 increases from 45° to 90°. The effect of α0 on γt plays a leading role and the effect of η0 will weaken when α0 is approximately 45°. 相似文献
36.
Representative sediment sizes in predicting the bed-material load for nonuniform sediments 总被引:1,自引:0,他引:1
《国际泥沙研究》2016,(1):79-86
37.
上海地磁加卸载响应比资料分析与地震研究 总被引:1,自引:0,他引:1
采用GM4型磁通门磁力仪与佘山台57型地磁记录得到的地磁加卸载响应比值以刁进行地震中短期预测分析,通过对两种设备在共同观测时期得到的只2)值进行分析。结果表明:由不同设备得到的旧值能满足以往的异常判定标准,GM4磁通门磁力仪得到的P(Z)值映震能力较好.可与余山台57型地磁记录仪匹配使用。 相似文献
38.
利用1951—2009年南京日平均气温、日最高气温以及日最低气温等资料,分析了南京日最高气温和最低气温的长期演变趋势及其与平均温度的关系。结果表明:近60 a来,南京年平均气温、年平均最高气温、年平均最低气温均呈变暖趋势,20世纪90年代增温尤为明显;日最高气温,除夏季表现为降温趋势外,其他季节均为升温趋势;而四季平均气温和平均最低气温均为增温趋势;夏季气温日较差下降趋势明显,导致夏季昼夜温差减小;极端高温、低温的发生日数均呈下降趋势。极端气温与平均气温之间存在明显的相关性,且极端低温对平均气温影响更为明显。 相似文献
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40.
Jameal F. Samhouri Phillip S. Levin C. Andrew James Jessi Kershner Greg Williams 《Marine Policy》2011
Human actions have altered the structure and function of coastal ecosystems worldwide. In many locations, the overall portfolio of goods, cultural amenities, and supporting services provided by the marine environment has deteriorated. Ecosystem-based management (EBM) offers significant promise for addressing these issues because it is a comprehensive and integrated approach designed to reconcile conflicts and trade-offs among users of marine resources. A key step in the implementation of EBM is the establishment of target reference levels, or desired states, for indicators that reflect the status of the ecosystem. This paper reviews five approaches, borrowed from a variety of disciplines, to establish target reference levels for EBM. The approaches include the use of existing reference levels, reference directions, and reference levels based on nonlinear functional relationships, baselines, or social norms. Each approach is particularly suitable for EBM because it can be used alone or in combination with others to contextualize status for a diverse suite of ecosystem goals influenced by a wide variety of human activities. Perhaps most importantly, these approaches offer a prospectus for moving forward with EBM by using readily available information, motivating existing scientific capacity, and addressing trade-offs implicit to the setting of targets. This last point is articulated via examples of how each type of reference level might be applied in Puget Sound, WA, USA, where the efforts of scientists, managers, and policy makers have aligned recently in the interest of EBM implementation. 相似文献