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141.
Lake water levels change under the influences of natural and/or anthropogenic environmental conditions. Among these influences are the climate change, greenhouse effects and ozone layer depletions which are reflected in the hydrological cycle features over the lake drainage basins. Lake levels are among the most significant hydrological variables that are influenced by different atmospheric and environmental conditions. Consequently, lake level time series in many parts of the world include nonstationarity components such as shifts in the mean value, apparent or hidden periodicities. On the other hand, many lake level modeling techniques have a stationarity assumption. The main purpose of this work is to develop a cluster regression model for dealing with nonstationarity especially in the form of shifting means. The basis of this model is the combination of transition probability and classical regression technique. Both parts of the model are applied to monthly level fluctuations of Lake Van in eastern Turkey. It is observed that the cluster regression procedure does preserve the statistical properties and the transitional probabilities that are indistinguishable from the original data. 相似文献
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本文利用Coherent GeoLasHD型193 nm ArF准分子激光剥蚀系统和Agilent 7900型四极杆电感耦合等离子体质谱仪, 建立了LA-ICP-MS石榴子石U-Pb定年方法。利用该方法, 对采自冀北地区晚古生代镁铁质-超镁铁质混杂岩体中的异剥钙榴岩和闽西南马坑式铁矿含矿石榴子石矽卡岩这两种岩石中的石榴子石开展U-Pb定年研究。在冀北地区晚古生代镁铁质-超镁铁质混杂岩体中的异剥钙榴岩中, 获得石榴子石下交点年龄为(387.6±5.4) Ma (D496-1, MSWD=1.1, N=30)和(409.3±7.8) Ma (D493-1, MSWD=2.0, N=60), 在马坑铁矿石榴子石矽卡岩中, 获得石榴子石下交点年龄为(128.6±2.1) Ma (ZK7921-b24, MSWD=2.0, N=60)和(128.7±3.2) Ma (ZK7922-b1, 用锆石91500校正, MSWD=1.8, N=42); 在潘田铁矿的石榴子石矽卡岩中, 获得石榴子石的下交点年龄为(128.7±1.7) Ma (PT-b1, MSWD=1.7, N=30)和(132.1±1.3) Ma (PT-b1样品, 用锆石91500校正, MSWD=1.6, N=30)(除了指明使用锆石标样91500校正石榴子石未知样品外, 其他皆用石榴子石标样Willsboro校正石榴子石未知样品的U/Pb分馏)。以上结果与Sm-Nd等时线年龄及前人报道的锆石U-Pb年龄在误差范围内一致。对马坑式铁矿石榴子石矽卡岩U-Pb定年结果表明, 利用石榴子石标样Willsboro和锆石标样91500作为外标样校正同一样品中石榴子石U/Pb同位素分馏, 获得的下交点年龄一致, 206Pb/238U年龄的加权平均值也一致, 说明石榴子石与锆石之间的基体效应较小, 在缺乏石榴子石标样时, 可用锆石标样91500代替。在上述研究基础上分析了石榴子石U-Pb定年方法在矽卡岩型矿床成矿时代研究及异剥钙榴岩年代学研究中的应用潜力, 认为石榴子石U-Pb定年方法在矽卡岩型矿床及异剥钙榴岩年代学研究中具有巨大的应用推广前景, 具有重要的理论指导和实际应用意义。 相似文献
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CTS-1E型、CMG-3ESPC-120型地震计安装架设在库尔勒地震台小泉沟观测点同一台基上,均使用EDAS-24GN型数据采集器进行实时数据采集,对比分析观测数据波形特征、地动噪声功率谱及动态范围等,明确2套地震计在实际观测中的性能差异,以便为地震监测数据分析及相关研究提供参考。 相似文献
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作者根据2012年5月和2013年11月对日照近岸海域进行的底拖网调查资料,分析了该海域虾蟹类的种类组成、优势种和生物多样性。调查海域共捕获虾蟹类25种,根据相对重要性指数计算优势种为8种,其中经济价值较高的中大型虾蟹类5种,分别为:口虾蛄(Oratosquilla oratoria)、戴氏赤虾(Meraenaeopsis dalei)、鹰爪虾(Trachypenaeus curvirostris)、日本[虫寻](Charybdis japonica)和三疣梭子蟹(Portunus trituberculatus)。分别计算了日照近岸海域春、秋季虾蟹类群落的多样性指数(H')、丰富度指数(D)和均匀度指数(J)。该海域虾蟹类群落多样性整体处在较低的水平,在生物量和丰度上经济较高的中大型虾蟹类物种占据优势。 相似文献
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Yan Taiming Hu Jiaxiang Cai Yueping Xiong Sen Yang Shiyong Wang Xiongyan He Zhi 《中国海洋湖沼学报》2017,35(5):1197-1204
Laboratory-reared Schizothorax davidi larvae and juveniles were examined to assess the formation and characteristics of David’s schizothoracin otoliths.Otolith development was observed and their formation period was verifi ed by monitoring larvae and juveniles of knownage.The results revealed that lapilli and sagittae developed before hatching,and the first otolith increment was identified at 2 days post hatching in both.The shape of lapilli was relatively stable during development compared with that of sagittae;however,growth of four sagittae and lapilli areas was consistent,but the posterior area grew faster than the anterior area and the ventral surface grew faster than the dorsal surface.Similarly,the sum length of the radius of the anterior and posterior areas on sagittae and lapilli were linearly and binomially related to total fish length,respectively.Moreover,daily deposition rates were validated by monitoring knownage larvae and juveniles.The increase in lapilli width was 1.88±0.080 0μm at the ninth increment,which reached a maximum and the decreased gradually toward the otolith edge,whereas that of sagittae increased more slowly.These results illustrate the developmental biology of S.davidi,which will aid in population conservation and fish stock management. 相似文献
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The influence of ecological technology measures on the annual sediment loads of rivers complies with the principles of statistics. In this paper, the annual sediment load of the Wuding River is taken as the dependent variable and the rainfall, rainstorms during the flood period of the Wuding River and areas of ecological technology measures are taken as the independent variables to analyze the influence of ecological technology measures on the annual sediment load of the Wuding River during the years 1956 to 2007. This research uses a stepwise regression method. The result shows that 1) the non-linear regression equation composed of three independent variables including 7-8 monthly rainfalls along the Wuding River, areas of ecological technology measures and maximum daily rainfall along the Wuding River has been calculated and set up; the correlation coefficient is R2=0.857 and the significance level is α=0.001. 2) R2=0.717 is adjusted and the regression equation reveals a change of annual sediment load exceeding 71.7% over 52 years; 3) The standardized regression coefficient for ecological technology measure area has the maximum absolute value of the three independent variables shows maximum influence on the change of annual sediment load; and 4) Because of implementing the ecological technology measures, until to year of 2007, when the 7-8 monthly rainfall and maximum daily rainfall are the maximum values in the research section, the annual sediment load is calculated as 149million ton, which is 36% of the maximum value in the history. 相似文献