Integrating the maximum capture problem into a GIS framework     

Benjamin D. Spaulding  Robert G. Cromley 《Journal of Geographical Systems》2007,9(3):267-288

This paper presents a methodology for reformulating the maximal capture problem by using the data representation and manipulation capabilities of GIS to define: (1) the coverage region captured by each potential facility, and (2) each unique demand region covered by a specific combination of potential facilities. The formulation is modeled on the maximum covering problem although the integer restriction on the demand capture variables is relaxed. Because demand regions are not exogenously given, areal interpolation is used to estimate the demand associated with each of these regions The model is used to determine the location on a network for a set of home improvement stores that are hypothetically in competition with existing Home Depot stores in Southeastern New Hampshire.   相似文献   

"莫拉克"台风引起的滑坡泥石流灾害HJ-1图像遥感监测研究   总被引：1，自引：0，他引：1  

邓睿  黄敬峰 《国土资源遥感》2011,22(1):106-109

利用HJ-1星2009年"莫拉克"台风前后获取的2个时相图像,通过去相关拉伸 (Decorrelation Stretch)、光谱信息增强和最大似然法分类提取滑坡、泥石流区域,并结合TRMM (Tropical Rainfall Measuring Mission)卫星降雨量数据和DEM (Digital Elevat...  相似文献   

观测分析非洲南部地区土壤湿度异常对南半球大气环流的显著影响     

荀爱萍  吴其冈  胡雅君  姚永红 《大气科学》2019,43(3):552-564

本文基于44年ERA40再分析月平均土壤湿度资料和大气环流变量场资料,去除ENSO遥相关以及趋势影响后,利用滞后最大协方差方法分析非洲南部地区土壤湿度分布与南半球大气环流异常之间的线性耦合。第一最大协方差模态的结果表明:在南半球冬季（Jun-Jul-Aug,6～8月）和夏季（Jan-Feb-Mar,1～3月）,大气中类似南极涛动（Antarctic Oscillation,简称AAO）正位相的环流型与超前月份（最长时间达到5个月）的非洲南部地区土壤湿度的异常分布显著相关。基于土壤湿度变率中心的线性回归分析方法证实非洲南部地区其北部土壤湿度正异常、中南部土壤湿度负异常的空间分布对后期夏季和冬季的大气有显著的反馈作用。诊断结果显示由于夏秋季节和春季初夏非洲南部地区土壤湿度异常均有显著的持续性,同时对后期AAO产生持续增强作用,所以滞后最大协方差方法可以检测出它们对后期AAO的显著影响。以上非洲南部地区土壤湿度异常超前于南极涛动的信号,将有助于加强对土壤湿度反馈机制及其对南半球大尺度环流变率影响的认识。  相似文献   

雅鲁藏布江流域古堰塞湖群的发育及其地质意义初探     

王萍  王慧颖  胡钢  覃金堂  李翠平 《地学前缘》2021,28(2):35-45

展布于青藏高原东南部的雅鲁藏布江流域河谷中广泛分布有古堰塞湖沉积,古堰塞湖发育与构造活动、气候变化和地表过程等因素关系密切。在广泛地质调查的基础上,识别出雅鲁藏布江流域的十余个古堰塞湖,通过对其开展沉积学、地貌学和年代学工作,结合前人工作结果,初步建立了古堰塞湖群的地层年代框架。地表残留的古堰塞湖沉积多集中于末次冰期冰盛期和全新世早期,持续时间可达千年—万年。对大竹卡古湖、格嘎古湖和易贡湖的研究结果进行了介绍,归纳出古堰塞湖群发育的基本特征,初步讨论了构造、气候和侵蚀相互作用下古堰塞湖研究的意义、存在的问题以及研究的方向。提出末次冰期以来的冰川(泥石流)堵江-堰塞-溃决洪水所构建的极端气候-灾害事件,对雅鲁藏布江河谷地貌和古地理环境等有重要影响。  相似文献   

Estimation of ultimate bond strength for soil nails in clayey soils using maximum likelihood method     

Huifen Liu  Peiyuan Lin 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2018,12(3):190-202

This paper presents a maximum likelihood estimation of the ultimate bond strength for soil nails in clays. Both uncensored and censored ultimate bond strength data for soil nails are collected from the literature. Based on the concept of maximum likelihood, a log-likelihood function is constructed for estimating the mean and coefficient of variation (COV) of the ultimate bond strength jointly using the two types of data. The mean and COV are determined as the pair that maximises the log-likelihood function. Two distribution models (normal and lognormal) are used for the estimation. A comparison of the relative competence between the two candidate distribution models that are adopted for describing the collected uncensored and censored data is performed using the Bayesian Information Criterion. Example designs of soil nail walls against internal pullout limit state of nails and overall stability limit state are provided to demonstrate the benefit of taking censored data into account for estimation of the ultimate bond strength of soil nails.  相似文献   

基于北京二号与地理国情数据的林地提取     

杜林丹  董春  赵荣  张玉  亢晓琛 《测绘通报》2023,(1):39-44

由于地理国情林地数据不包含实地面积小于400 m²的树木或四旁单排林,若仅利用地理国情的林地数据统计区域森林覆盖率,将对四旁树面积较大地区的林地统计结果产生较大误差。为提取区域内准确的林地覆盖与空间分布状况,本文借助地理国情地表覆盖数据,提出了一种基于北京二号高分辨率遥感影像的林地提取方法。首先,根据遥感影像光谱特征,将研究区按植被、道路、铁路、建筑用地进行地类划分,并基于遥感影像进行各地类的样本提取,通过可分离检验的样本利用最大似然分类提取研究区内植被覆盖范围;然后,借助地理国情地表覆盖数据,使用叠置分析剔除误分、错分地类,得到区域林地的空间分布。试验结果表明：(1)研究区内林地覆盖率为20.3%,尚未满足北京新一轮林地规划需求;(2)地理国情地表覆盖数据内林地面积占提取林地总面积的54.03%,说明在部分地区使用本文方法对地理国情林地数据进行补充是有必要的。通过将试验结果与遥感影像进行目视比对并结合外业调查结果发现,提取的林地空间分布情况与实际分布基本相符。本文为地理国情的应用提供了一种新方法,研究结果可辅助区域的绿色发展规划,有助于构建科学的生态空间格局。  相似文献   

Masterstroke or paper tiger – The reform of the EU׳s Common Fisheries Policy     

《Marine Policy》2014

The European fisheries policy has undergone a substantial reform. The reform process was initiated by a Green Paper published by the European Commission in 2009. It was recently finalised with an agreement on a new Basic Regulation between the European Commission, the Council and the Parliament in October 2013. The reform of the Common Fisheries Policy will be an important step towards a more sustainable fisheries policy in Europe. The most important reform steps are the introduction of maximum sustainable yield as the new management target, a landing obligation for bycatch and a governance shift towards regions. Although the mentioned reform elements are in generally very promising, their concrete design does not always meet existing expectations.  相似文献   

Minimising unsustainable yield: Ten failing European fisheries     

《Marine Policy》2014

Ten European fish stocks recognised by the European Union as “outside safe biological limits” are considered in light of widespread reforms to fisheries legislation in 2013, particularly the legal responsibility to exploit these resources sustainably. Given that some of these stocks are – as of 2013 – fished at over 150% the recommended intensity and many have been outside of these limits for the entirety of their assessment history, the utilisation of traditional fisheries management measures of sustainability are questioned and tougher approaches such as “zero-catch” and long-term, expansive spatial closure scenarios are considered. Finally, the pervasive issue of data-deficiency (the status of 54% of European stocks) is briefly considered, with specific reference to the understudied West of Scotland and North Sea stock of European seabass (Dicentrarchus labrax).  相似文献   

Mixture model based multivariate statistical analysis of multiply censored environmental data     

《Advances in water resources》2013

Environmental data are commonly constrained by a detection limit (DL) because of the restriction of experimental apparatus. In particular due to the changes of experimental units or assay methods, the observed data are often cut off by more than one DL. Measurements below the DLs are typically replaced by an arbitrary value such as zeros, half of DLs, or DLs for convenience of analysis. However, this method is widely considered unreliable and prone to bias. In contrast, maximum likelihood estimation (MLE) method for censored data has been developed for better performance and statistical justification. However, the existing MLE methods seldom address the multivariate context of censored environmental data especially for water quality. This paper proposes using a mixture model to flexibly approximate the underlying distribution of the observed data due to its good approximation capability and generation mechanism. In particular, Gaussian mixture model (GMM) is mainly focused in this study. To cope with the censored data with multiple DLs, an expectation–maximization (EM) algorithm in a multivariate setting is developed. The proposed statistical analysis approach is verified from both the simulated data and real water quality data.  相似文献   

Optimization of geothermal water exploitation in Xinji,Hebei Province,P. R. China     

YUE Gao-fan  LV Wen-bin  ZHANG Wei  SU Ran  LIN Wen-jing 《地下水科学与工程》2016,4(3):197-203

Geothermal with features of large reserves and non-pollution has been one of the most important energy. China has significant geothermal resources. There are rich hydrothermal resources in Xinji, which has been in development for 5 years. However, hot water continues to decrease because of extensive exploitation and utilization. We selected exploration area as study area, build a set of numerical models of Guantao formation on the basis of actual geological conditions. We get the distribution of hydraulic conductivity from 1.7 m/d to 1.9 m/d by parameter inversion using historical water level monitoring data, and simulation effect is good. We calculate the maximum permissible exploitation under the limitation of 200 m in depth in 50 years which is about 2.2 million m3/a. The results will provide theoretic support for plan making of geothermal exploitation.  相似文献