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排序方式: 共有990条查询结果,搜索用时 359 毫秒
91.
92.
Richard C. Chiverrell Ian M. Thrasher Geoffrey S. P. Thomas Andreas Lang James D. Scourse Katrien J. J. van Landeghem Danny Mccarroll Chris D. Clark Colm Ó Cofaigh David J. A. Evans Colin K. Ballantyne 《第四纪科学杂志》2013,28(2):200-209
We present an 8000‐year history spanning 650 km of ice margin retreat for the largest marine‐terminating ice stream draining the former British–Irish Ice Sheet. Bayesian modelling of the geochronological data shows the ISIS expanded 34.0–25.3 ka, accelerating into the Celtic Sea to reach maximum limits 25.3–24.5 ka before a collapse with rapid marginal retreat to the northern Irish Sea Basin (ISB). This retreat was rapid and driven by climatic warming, sea‐level rise, mega‐tidal amplitudes and reactivation of meridional circulation in the North Atlantic. The retreat, though rapid, is uneven, with the stepped retreat pattern possibly a function of the passage of the ice stream between normal and adverse ice bed gradients and changing ice stream geometry. Initially, wide calving margins and adverse slopes encouraged rapid retreat (~550 m a?1) that slowed (~100 m a?1) at the topographic constriction and bathymetric high between southern Ireland and Wales before rates increased (~200 m a?1) across adverse bed slopes and wider and deeper basin configuration in the northern ISB. These data point to the importance of the ice bed slope and lateral extent in predicting the longer‐term (>1000 a) patterns and rates of ice‐marginal retreat during phases of rapid collapse, which has implications for the modelling of projected rapid retreat of present‐day ice streams. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
93.
刘军 《成都信息工程学院学报》2004,19(1):40-43
根据用户的访问记录,以及每次检索输入的关键词、用户的动作来动态更新用户的兴趣点.提出了一个能较好吻合这一思想的数据挖掘模型,以用户的停留时间、访问频率和用户输入的检索关键词为数据对象,进行用户兴趣分析,动态跟踪用户需求意向,简化检索过程,提高WEB资源的使用效率. 相似文献
94.
Maria Dina Vivarelli 《Celestial Mechanics and Dynamical Astronomy》1994,60(3):291-305
This paper is an attempt to bring unity in the study of the classical Kepler problem by combining, through simple vectorial and quaternionic techniques, its two peculiar aspects: the determination of the constants of the motion and the regularization at the origin.Research supported by the Consiglio Nazionale delle Ricerche of Italy (C.N.R.-G.N.F.M.). 相似文献
95.
A procedure for tidal analysis with a Bayesian information criterion 总被引:16,自引:0,他引:16
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97.
In optical dating, especially single-grain dating, various patterns of distributions in equivalent dose (De) are usually observed and analysed using different statistical models. None of these methods, however, is designed to deal with outliers that do not form part of the population of grains associated with the event of interest (the ‘target population’), despite outliers being commonly present in single-grain De distributions. In this paper, we present a Bayesian method for detecting De outliers and making allowance for them when estimating the De value of the target population. We test this so-called Bayesian outlier model (BOM) using data sets obtained for individual grains of quartz from sediments deposited in a variety of settings, and in simulations. We find that the BOM is suitable for single-grain De distributions containing outliers that, for a variety of reasons, do not form part of the target population. For example, De outliers may be associated with grains that have undesirable luminescence properties (e.g., thermal instability, high rates of anomalous fading) or with contaminant grains incorporated into a sample when collected in the field or prepared in the laboratory. Grains that have much larger or smaller De values than the target population, due to factors such as insufficient bleaching, beta-dose heterogeneity or post-depositional disturbance, may also be identified as outliers using the BOM, enabling these values to be weighted appropriately for final De and age determination. 相似文献
98.
Zhongqiang Liu Farrokh Nadim Alexander Garcia-Aristizabal Arnaud Mignan Kevin Fleming Byron Quan Luna 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2015,9(2):59-74
The effective management of the risks posed by natural and man-made hazards requires all relevant threats and their interactions to be considered. This paper proposes a three-level framework for multi-risk assessment that accounts for possible hazard and risk interactions. The first level is a flow chart that guides the user in deciding whether a multi-hazard and risk approach is required. The second level is a semi-quantitative approach to explore if a more detailed, quantitative assessment is needed. The third level is a detailed quantitative multi-risk analysis based on Bayesian networks. Examples that demonstrate the application of the method are presented. 相似文献
99.
Ji-Lei Hu Xiao-Wei Tang 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2015,9(3):200-217
The Bayesian network (BN) is a type of graphical network based on probabilistic inference that has been gradually applied to assessment of seismic liquefaction potential. However, how to construct a robust BN remains underexplored in this field. This paper aims to present an efficient hybrid approach combining domain knowledge and data to construct a BN that facilitates the integration of multiple factors and the quantification of uncertainties within a network model to assess seismic liquefaction. Initially, only using given domain knowledge, a naive network model can be constructed using interpretive structural modeling. Thereafter, some effective information about the naive model is provided to construct a robust model using structural learning of BN from historic data. Finally, the returning predictive results and the predictive results are compared to other methods including non-probabilistic and probabilistic models for seismic liquefaction using the metrics of the overall accuracy, the area under the curve of receiver operating characteristic, prediction, recall and F1 score. The methodology proposed in this paper achieved better performance, and we discussed the power and value of the proposed approach at the end of this paper, which suggest that BN is a good alternative tool for seismic liquefaction prediction. 相似文献
100.