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71.
利用2001~2015年三峡数字遥测地震台网记录到的数字地震观测资料,结合三峡工程水库蓄水情况,采用Atkinson方法分析该地区的地震波衰减特征,得到不同蓄水阶段、不同库段的非弹性衰减结果。结果显示,Q值与频率变化的线性关系较好,各频点在拟合线附近波动;3个库段在不同蓄水阶段均具有较小的Q0值和中等的η值,表明三峡工程水库重点监视区构造复杂,且介质的均匀程度较低;仙女山-九畹溪断裂附近地区Q值较大,表明该地区构造运动比较稳定;巴东高桥断裂附近地区Q值较小,表明该地区构造运动比较强烈;泄滩地区随着水位的升高,Q0值增大,表明该地区介质均匀程度有所提高。 相似文献
72.
证明了下面两个定理:(1)设n,k≥2为正整数,a为有穷非零复数,F为区域D上的亚纯函数族,F中任一函数的零点重级至少为k.vf,g∈F,fLn(f)与gLn(g)IM分担a.则F在D上正规,其中L(f)为f(k)+a1f^(k-1)+…+akf,这里a1,…,ak为常数.(2)设n,k为正整数,且n≥2,a为有穷非零复数,F为区域D上的亚纯函数族,F中任一函数的零点重级至少为k,且fLn(f(z))=a能够推出|f^(k)(z)|≤A,其中A为正数,则F在区域D上正规. 相似文献
73.
CPI values of terrestrial higher plant-derived long-chain n-alkanes: a potential paleoclimatic proxy
Zhiguo Rao Zhaoyu Zhu Suping Wang Guodong Jia Mingrui Qiang Yi Wu 《Frontiers of Earth Science》2009,3(3):266-272
Carbon Preference Index (CPI values) of higher plant-derived long-chain n-alkanes extracted from 62 surface soil samples in eastern China exhibited a specific pattern of variations, namely gradual
increase with the increasing latitudes. Such regular variations existed in both forest soil and grassland soil. Our data implied
that CPI values of higher plant-derived long-chain n-alkanes had a certain connection with climatic conditions, and such a connection was not influenced by vegetation types.
Together with previous data from marine sediments, loess/paleosol sequences, tertiary red clay and modern plants, our observation
made us conclude that CPI values of higher plant-derived long-chain n-alkanes may be used as an excellent proxy for paleoclimatic studies. 相似文献
74.
对麻栗坡地区1∶5万水系沉积物测量数据的统计分析表明,W、Sn、Pb、Zn、Cu等主要成矿元素不完全服从正态分布和对数正态分布,而表现出多重分形结构特征。因此,采用传统的地质统计学方法提取异常显然不能客观地反映区域的成矿元素分布特征。本文引用了"C-A"多重分形模型来研究该地区成矿元素特征,并有效提取各元素异常下限值,结合区域成矿地质背景,对区内成矿潜力进行初步预测。实践表明,分形方法所提取的剩余异常与研究区的矿产分布较为相符,较好地反映了研究区成矿元素分布规律,为研究区成矿预测提供了依据。 相似文献
75.
In a Cost-Benefit Analysis (CBA) or an Environmental Impact Assessment (EIA), determining the value that the general public attaches to a landscape is often problematic. To aid the inclusion of this social value in such analyses, a Google Maps-based tool, called the HotSpotMonitor (HSM), was developed. The HSM determines which natural places are highly attractive by having people mark such places on a map. The definition of attractiveness remains open to avoid having marker placement being influenced by preconceived thoughts. The number of markers an area receives is considered to indicate its social value. Six regions were selected, and from these, stratified samples were drawn (total n = 3293). Participants placed markers at three spatial levels: local, regional and national. This paper focuses on the markers at the national level. The first research question is whether the HSM can produce an accurate map of highly attractive places at a national level. The results indicated that while in principle HSM can produce such a map, the spatial representativeness of the sample is important. The region of origin of the participants influenced where they placed their markers, an effect previously termed spatial discounting. The second research question considers which qualities the participants associate with the marked places. These qualities were very similar at all three spatial levels: green, natural, presence of water and quiet were often selected out of the fourteen suggested qualities. The third, and more exploratory, research question concerns which characteristics of an area predict its attractiveness. Natural and forest areas had higher marker densities than water surfaces or all other types of land use combined. The discussion evaluates the potential of the HSM to generate input on social landscape values for CBAs and EIAs. 相似文献
76.
ABSTRACT Groundwater-level time series often have a substantial number of missing values which should be taken into consideration before using them for further analysis, particularly for numerical groundwater flow modelling applications. This study aims to comprehensively compare two data-driven models, singular spectrum analysis (SSA) and multichannel spectrum analysis (MSSA), to reconstruct groundwater-level time series and impute the missing values for 25 piezometric stations in Ardabil Plain, northwest Iran. The reconstructed groundwater-level time series are assessed against the complete observed groundwater time series, while the imputed values are appraised against the artificially created gap values. The results show that both SSA and MSSA demonstrate a solid competency in imputation and reconstruction of groundwater-level data. However, depending on the spatial correlation between the piezometers, and the most suitable probability distribution function (pdf) fitted to the time series of each piezometer, the performance may vary from piezometer to piezometer. 相似文献
77.
78.
A typhoon leading is an important natural disaster to many disasters to China. A giant wave caused by it has brought large threat for an offshore project. Based on the maximum entropy principle,one new model which has 4 undetermined parameters is constructed,which is called the discrete maximum entropy probabilistic model. In practical applications,the design wave height is considered as soon as possible in a typhoon affected sea areas,the result fits the observed data well. Further more this model does not have the priority compared with other distributions as Poisson distribution. The model provides a theoretical basis for the engineering design more reasonable when considering typhoon factors comprehensively. 相似文献
79.
80.
通过LI-8100土壤碳通量测定仪对中亚热带山区不同土地利用方式土壤呼吸进行测定与分析.结果表明,不同土地利用方式土壤温度变化趋势较为一致,峰值出现在16:00,但坡耕地均出现在14:00;不同土地利用方式土壤呼吸速率昼夜变化趋势大致呈单峰变化,呼吸速率在12:00—16:00之间达到一天的最大值,而在6:00达到最小值,但杉木林与木荷林土壤呼吸速率在夏季呈现出不规则的多峰变化,不同季节呼吸速率最大值出现的时间不同;杉木林与木荷林不同季节的土壤呼吸速率的目变化幅度较小,果园的最大;土壤呼吸速率的均值大小顺序为:经济林〉木荷林〉坡耕地〉杉木林〉果园,但不同土地利用方式间土壤呼吸速率差异不显著(P〉0.05).不同土地利用方式土壤呼吸Q10值的季节变化中,杉木、木荷2种人工林用地冬季Q10值最大,最小值分别出现在夏季与秋季,而坡耕地、经济林与果园3种土地利用方式以春季的Q10值最大,秋季最小;Q10值随土壤碳质量的降低而增大. 相似文献