基于贝叶斯网络的生态系统服务空间格局优化——以泾河流域为例          下载免费PDF全文

余玉洋  李晶  周自翔  唐承延 《干旱区地理》2022,45(4):1268-1280

城市高速发展引起了区域土地利用格局的改变,不仅影响生态环境质量,而且还对生态系统服务的空间格局产生影响,在此基础上优化生态系统服务显得至关重要。在泾河流域2000—2020年净初级生产力（Net primary productivity, NPP）、农业生产力、土壤保持和产水服务空间评估的基础上,将贝叶斯网络和生态系统服务相结合,在关键变量子集和可视化的最优状态子集的基础上,评估了4种生态系统服务需要优化的区域,为区域经济和生态和谐发展提供参考。结果表明：（1） 水文评价模型（Soil and water assessment tool, SWAT）模型能较准确地模拟区域的径流量。通过模拟值和观测值对比分析,该模型具有较高的决定性系数（R²>0.6）和纳什效率系数（NSE>0.5）,可为进一步评估产水服务提供保障。（2） 2000—2020年泾河流域4种生态系统服务的时空差异性较为显著。在时间尺度上,4种生态系统服务均呈现波动中上升的趋势,在空间尺度上呈现较为稳定的变化趋势。（3） 通过对4种生态系统服务优化区域进行叠加分析,发现综合优化区域集中在彭阳县的中部和西南部以及环县的零星区域。研究结果对指导优化区域进行生态系统的可持续管理以及改善生态系统的退化状况具有重要意义。  相似文献   

Bayesian area-to-point kriging using expert knowledge as informative priors     

《International Journal of Applied Earth Observation and Geoinformation》2014

Area-to-point (ATP) kriging is a common geostatistical framework to address the problem of spatial disaggregation or downscaling from block support observations (BSO) to point support (PoS) predictions for continuous variables. This approach requires that the PoS variogram is known. Without PoS observations, the parameters of the PoS variogram cannot be deterministically estimated from BSO, and as a result, the PoS variogram parameters are uncertain. In this research, we used Bayesian ATP conditional simulation to estimate the PoS variogram parameters from expert knowledge and BSO, and quantify uncertainty of the PoS variogram parameters and disaggregation outcomes. We first clarified that the nugget parameter of the PoS variogram cannot be estimated from only BSO. Next, we used statistical expert elicitation techniques to elicit the PoS variogram parameters from expert knowledge. These were used as informative priors in a Bayesian inference of the PoS variogram from BSO and implemented using a Markov chain Monte Carlo algorithm. ATP conditional simulation was done to obtain stochastic simulations at point support. MODIS (Moderate Resolution Imaging Spectroradiometer) atmospheric temperature profile data were used in an illustrative example. The outcomes from the Bayesian ATP inference for the Matérn variogram model parameters confirmed that the posterior distribution of the nugget parameter was effectively the same as its prior distribution; for the other parameters, the uncertainty was substantially decreased when BSO were introduced to the Bayesian ATP estimator. This confirmed that expert knowledge brought new information to infer the nugget effect at PoS while BSO only brought new information to infer the other parameters. Bayesian ATP conditional simulations provided a satisfactory way to quantify parameters and model uncertainty propagation through spatial disaggregation.  相似文献   

机载激光雷达数据的建筑物三维模型重建   总被引：1，自引：0，他引：1  

肖勇  王成  习晓环  王方建 《测绘科学》2014,39(11):37-41

机载激光雷达技术可以快速获取建筑物高精度高密度的三维空间信息.文章提出一种建筑物三维模型重建方法,该方法利用栅格数据使用RANSAC算法提取建筑边界上的长线段,采用规则化策略获取建筑轮廓;在模型生成阶段,基于原始点云和屋顶拓扑关系约束,获取屋顶间的交线和交点,并结合已得到的建筑边界、屋顶间交线和交点获取三维建筑模型.实验结果表明,该方法思路清晰、科学可行且适用性强,提取的建筑边界和模型垂直精度高.  相似文献   

Bayesian modelling the retreat of the Irish Sea Ice Stream     

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   

基于贝叶斯网络的Web访问模式挖掘模型系统     

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   

The Kepler problem: A unifying view     

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   

A procedure for tidal analysis with a Bayesian information criterion   总被引：16，自引：0，他引：16  

Y. Tamura  T. Sato  M. Ooe  M. Ishiguro 《Geophysical Journal International》1991,104(3):507-516

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Hierarchical Bayesian approach for population dynamics modelling of fish complexes without species-specific data   总被引：1，自引：0，他引：1  

Jiao  Yan; Hayes  Christopher; Cortes  Enric 《ICES Journal of Marine Science》2009,66(2):367-377

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一种基于流形正则化的半监督指纹定位算法     

朱顺涛  卢先领  于丹石 《测绘通报》2018,(2):11-15,20

针对传统指纹定位算法采集带标签训练数据成本高的问题,本文提出了一种基于流形正则化的半监督指纹定位算法。首先以流形假设为依据,利用批量输入的带标签数据与无标签数据之间的相似度构建图拉普拉斯算子;然后与极限学习机算法相结合,通过随机特征映射建立隐含层;最后在流形正则化框架下,求解隐含层和输出层之间的权值矩阵,从而建立位置估计模型。仿真结果表明,与INN、SVR、ELM 3种算法相比,该算法的训练和测试时间相对较短,且在带标签训练数据稀疏的前提下仍能保持较高的准确率与稳定性。  相似文献   

Bayesian analysis of De distributions in optical dating: Towards a robust method for dealing with outliers     

《Quaternary Geochronology》2022

In optical dating, especially single-grain dating, various patterns of distributions in equivalent dose (D_e) 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 D_e distributions. In this paper, we present a Bayesian method for detecting D_e outliers and making allowance for them when estimating the D_e 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 D_e distributions containing outliers that, for a variety of reasons, do not form part of the target population. For example, D_e 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 D_e 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 D_e and age determination.  相似文献