夜光遥感视角下的中国城市规模的时空演变     

徐慧敏  胡守庚 《武汉大学学报(信息科学版)》2021,(1):40-49

为探究中国城市规模的演变特征,基于总量统计、位序-规模分析和马尔可夫转移矩阵,利用夜光遥感影像分析了1993-2012年中国省级行政区和经济区的城市规模分布规律及演化.总量统计分析结果表明,所有经济区和省级行政区夜光都呈现增长趋势,其中大西南综合经济区、大西北综合经济区夜光增加比例最大,分别达到257％、254％,省级...  相似文献   

滦平盆地桑园营子露头剖面沉积层序的Markov链模拟   总被引：5，自引：0，他引：5  

陈永进  武法东 《现代地质》2000,14(4)

桑园营子露头剖面具有同沉积断层控制的近源、粗粒、陡坡型浅水扇三角洲体系的沉积特征。根据 Markov过程的基本原理 ,认识到桑园营子剖面出露完整的扇三角洲前缘沉积组合( C — C 旋回 )各岩性相之间的转移具有 Markov性质 ,利用转移概率矩阵法及差值矩阵法对该沉积组合进行 Markov链模拟 ,得出了理想的垂向沉积层序模式图。该模式图与实际地层层序吻合较好 ,反映了各岩性相的空间展布特征 ,建立了沉积环境的演化序列。  相似文献   

德令哈盆地早侏罗世冲积扇—扇三角洲沉积体系及其马尔科夫链分析     

杨明慧  牛雅莉 《中国煤田地质》2000,(1)

德令哈盆地下侏罗统含煤磨拉石盆地组合是在以冲积扇—扇三角洲沉积体系为主的沉积环境下发育起来的。简要报道研究区冲积扇—扇三角洲体系沉积及其组合特征 ,在此基础上借助马尔科夫链建立冲积扇—扇三角洲体系沉积旋回的结构模式 ,并探讨该结构模式的地质意义。  相似文献   

System Analysis of Disaster Prevention Design Criteria for Coastal and Estuarine Cities   总被引：3，自引：0，他引：3  

LIU Defu 《中国海洋工程》2000,14(1):69-78

—In China,estuarine and coastal cities are mostly regional economic development centers.Thedisasters by combined effect of upper reach flood,storm surge and typhoon waves are primary obstaclesto the economic development of such cities.Thus the risk analysis and system analysis of flood-stormsurge-wave disaster,economic loss and flood-storm surge control measures play a very important role inthe sustainable development of coastal cities.There are three types of coastal cities for consideration.Thefirst type of city is like Tianjin.The most significant damage is from the upper reach flood.The effect ofstorm surge is negligible,because in the estuary of the Haihe River,tidal locks are built.The Grey MarkovModel(GMM)is used to forecast the flood peak level.GMM combines the Grey system and the Markovtheory into a high-precision model.The predicted flood peak levels are close to the measured data.A syn-thetic model is established for economic assessment,risk analysis and flood-control benefit estimation.Asa n  相似文献   

Aeolian sediment fingerprinting using a Bayesian mixing model   总被引：1，自引：0，他引：1       下载免费PDF全文

Hamid Gholami  Matt W. Telfer  William H. Blake  Abolhassan Fathabadi 《地球表面变化过程与地形》2017,42(14):2365-2376

Identifying sand provenance in depositional aeolian environments (e.g. dunefields) can elucidate sediment pathways and fluxes, and inform potential land management strategies where windblown sand and dust is a hazard to health and infrastructure. However, the complexity of these pathways typically makes this a challenging proposition, and uncertainties on the composition of mixed‐source sediments are often not reported. This study demonstrates that a quantitative fingerprinting method within the Bayesian Markov Chain Monte Carlo (MCMC) framework offers great potential for exploring the provenance and uncertainties associated with aeolian sands. Eight samples were taken from dunes of the small (~58 km²) Ashkzar erg, central Iran, and 49 from three distinct potential sediment sources in the surrounding area. These were analyzed for 61 tracers including 53 geochemical elements (trace, major and rare earth elements (REE)) and eight REE ratios. Kruskal–Wallis H‐tests and stepwise discriminant function analysis (DFA) allowed the identification of an optimum composite fingerprint based on six tracers (Rb, Sr, ⁸⁷Sr, (La/Yb)_n, Ga and δCe), and a Bayesian mixing model was applied to derive the source apportionment estimates within an uncertainty framework. There is substantial variation in the uncertainties in the fingerprinting results, with some samples yielding clear discrimination of components, and some with less clear fingerprints. Quaternary terraces and fans contribute the largest component to the dunes, but they are also the most extensive surrounding unit; clay flats and marls, however, contribute out of proportion to their small outcrop extent. The successful application of these methods to aeolian sediment deposits demonstrates their potential for providing quantitative estimates of aeolian sediment provenances in other mixed‐source arid settings, and may prove especially beneficial where sediment is derived from multiple sources, or where other methods of provenance (e.g. detrital zircon U–Pb dating) are not possible due to mineralogical constraints. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Comparative analysis of predictive methods for drought durations: a case of monthly and annual streamflow droughts in Atlantic Canada     

T.C. Sharma 《水文科学杂志》2017,62(5):760-773

Methods based on the recursive probability, the extreme number theorem, and Markov chain (MC) concepts were applied to predict drought lengths (duration) on the standardized (termed as standardized hydrological index, SHI) sequences of monthly and annual river flows from Atlantic Canada. Results of the study indicated that the MC-based method is the most efficient, reliable and versatile method for predicting drought durations followed by the extreme-number-based method. The recursive-probability-based method was found to be computationally intensive and less efficient, although it provided a powerful means for calibrating the empirical plotting position formula needed in the MC-based method. The Weibull plotting position formula turned out to be a suitable measure of the exceedance probability in MC methodology for predicting drought lengths in Atlantic Canada. Based on results, it can be inferred that the MC-based method can be extended to MC2 and higher-order chains for predicting drought lengths on SHI sequences. The predictive capability of the extreme-number-theorem-based method is limited only to independent or weakly first-order persistent SHI sequences.