基于改进场模型的城市腹地划分方法——以山东省为例     

张立芳  王亮  赵荣  徐胜华  金江  孙泰  宫政 《测绘科学》2016,(2):62-66

针对传统城市腹地划分方法很少考虑阻碍因素的不足,该文将阻碍因素引入场模型,改进场模型中的城市综合规模,提出了基于改进场模型的城市腹地划分方法,较好地界定了城市影响范围;基于改进的场模型,实现了城市势力范围合理划分。以山东省17个地级市为研究对象,开展了城市腹地划分验证分析,实验结果表明:山东省各城市势力范围差异较大,中心城市的势力范围远远超出其行政范围,各城市势力圈与市域行政范围吻合性有待提高。研究表明城市腹地范围是由中心城市和周边城市的实力共同决定,是对城市经济区的重新界定,对城市体系规划和结构调整有一定参考意义。  相似文献   

应用PCA和ICA法对岩心光谱的定量解译          下载免费PDF全文

蒋夕平  于瀚文  吴芳  黄俊杰 《地质找矿论丛》2016,31(1):121-126

岩心光谱属于混合像元光谱,维度多、数据量大,在端元数量、端元光谱及混合矩阵未知的情况下,定量解译岩心光谱以提取岩心所含矿物信息难度大,噪声的存在使问题更加复杂。文章应用PCA和ICA法定量解译岩心光谱主要有三步:采用PCA法预处理混合像元光谱矩阵,在新的特征空间中保留特征值较大的少量特征矢量,有效滤除能量较小的成分,只保留主要成分信息,同时滤除数据中的噪声;采用ICA法分离岩心混合像元,得到混合像元中的端元光谱集,通过矿物识别获取岩心矿物成分;对端元光谱进行归一化处理,基于线性光谱混合模型进行丰度反演,得到岩心混合像元中各端元丰度。通过研究仿真数据获得光谱定量解译的一般规律,创建有效的算法模型,再处理实际测量的岩心光谱,获得了比较理想的结果。  相似文献   

面向对象的高分辨率遥感影像阴影提取方法     

王理政  林祥国  宁晓刚 《测绘科学》2017,42(3)

针对高分辨率遥感影像阴影提取的问题,通过分析影像主成分变换和HIS变换的特征,提出了一种面向对象的高分辨率遥感影像阴影提取方法:首先,使用mean shift分割方法进行影像去噪和平滑;然后,结合主成分变换和HIS变换形成了一种阴影检测指数(SDI);最后,通过阈值分割提取阴影信息。选取两景影像进行了阴影提取实验。实验结果表明,SDI能有效地区分阴影与建筑物、水体、蓝色地物、植被等非阴影地物;另外,mean shift分割能有效地去除结果中斑点噪声的影响,提高阴影检测精度。  相似文献   

Climate variability and planktonic communities: The effect of an extreme event (severe drought) in a southern European estuary   总被引：1，自引：2，他引：1  

Snia Cotrim Marques  Ulisses Miranda Azeiteiro  Filipe Martinho  Miguel ngelo Pardal 《Estuarine, Coastal and Shelf Science》2007,73(3-4):725-734

As a consequence of climate change, flood and drought events are increasing in frequency throughout the world. Nevertheless, knowledge of the effects on zooplankton estuarine communities is still scarce. The present study aimed to examine zooplankton ecology over two contrasting environmental conditions: regular years and extreme dry years, in a shallow temperate southern European estuary, the Mondego Estuary (Portugal). Monthly samples were carried out during three consecutive years: 2003 characterized as a regular temperate year concerning precipitation and river flow, and an extremely dry period during 2004–2005. The spatial and temporal structure of the biological data was evaluated by a three-mode principal component analysis (PCA), which allowed us to distinguish three distinct ecological areas based on their biological composition and their relationship with hydrologic parameters. The severe drought in 2004–2005 was responsible for spatial shifts in the estuary regarding zooplankton community and interannual variability, with an increase in abundance and diversity during the period of low freshwater flow. This freshwater flow regime influenced the composition of the zooplankton community at the most upstream section of Mondego estuary (zone 3), with a replacement of the freshwater community by one predominantly dominated by estuarine organisms. The occurrence of such estuarine community contributed to the increase in zooplankton abundance which is ascribed to the estuarine species Acartia tonsa. The comparison with previous data obtained for this estuarine ecosystem, demonstrated the occurrence of a different scenario at times of high freshwater flow, being defined the existence of two sub-estuarine systems, the north and south arm, presenting the south one the highest values of abundance.  相似文献   

ASTER和TM/ETM+遥感数据融合监测土地覆盖变化   总被引：3，自引：0，他引：3  

贺奋琴  胡振琪  尹建忠  房世波 《测绘科学》2007,32(1):96-97,111

在人们纷纷选择IKONOS、QUICKBIRD、SPOT-5等高分辨率影像监测土地利用/覆盖变化之际,以北京海淀区为例,尝试采用Brovey变换和主成分分析(PCA)法融合ASTER、TM/ETM+中等分辨率影像,充分利用ASTER、TM/ETM+数据的多光谱和较高空间分辨率特性,挖掘其在土地覆盖变化监测中的潜力,为大规模监测土地利用/覆盖变化提供科学参考。研究将2003年ASTER多光谱3N、2、1波段与1999年ETM+PAN波段进行Brovey变换;1992年TM543与1999年ETM+PAN波段进行PCA融合,快速发现土地覆盖变化信息。经验证,变化发现精度达92.50%,符合项目精度要求。试验表明:在缺乏高分辨率影像的地区,选择价格相对便宜的AS-TER和TM/ETM+数据,采用Brovey变换和主成分分析(PCA)法进行融合,可有效监测土地覆盖变化,节约动态监测成本,二者具有很大的应用价值,值得推广。  相似文献   

基于主成分方法分析2013年甘肃岷县漳县6.6级地震前地磁日变化异常     

李军辉  何康  王燚坤  汪小厉 《地震》2022,42(1):122-132

选用2013—2014年兰州台、 天水台、 寺滩台3个台站地磁垂直分量分钟值数据, 利用调和分析剔除1~4次地磁日变化谐波成分, 在此基础上对3个台站地磁Z分量数据进行主成分分析, 计算结果显示: 2013年7月22日岷县漳县6.6级地震前, 最小的第三主成分在2013年4月20日至6月10日出现明显的增强变化, 超出阈值, 异常持续50 d左右; 同时, 在信号的子空间中特征矢量的方向也出现同步的异常扰动, 震后恢复到原来的水平, 其他时段第三主成分未出现类似变化。 据此认为, 这些异常信号与2013年岷县漳县6.6级地震相关。 研究结果表明, PCA方法对地震电磁异常的提取是有效的。  相似文献   

四种基于像元的地表覆盖变化检测方法比较   总被引：1，自引：0，他引：1  

周晓光  曾联斌  袁愈才  宋正祥  李飞 《测绘科学》2015,40(1):52-57

目前遥感影像变化检测方法很多,但各种方法的适用性各不相同。鉴于灰度差值、NDVI差值、灰度比值、主成分分析法在地表覆盖变化检测中应用广泛,文章从数据更新的角度对这4种方法进行了比较;在分析比较这4种方法的单一变化检测精度、检测结果的相同性、相异性的基础上探索了适合于30m分辨率TM地表覆盖变化检测的组合方法。实验结果表明,在地表覆盖变化检测中,有效组合方法能够取得比单一变化检测方法更好的效果;比值法并NDVI差值法并PCA差异法的检测结果中包含了4种单一检测方法所检测出的全部变化像元,达到了最高的生产者精度,比较适合于地表覆盖数据更新制图应用。  相似文献   

Disentangling late-Holocene climate and land use impacts on an Austrian alpine lake using seasonal temperature anomalies,ice-cover,sedimentology, and pollen tracers   总被引：1，自引：0，他引：1  

Roland Schmidt  Monika Roth  Richard Tessadri  Kaarina Weckström 《Journal of Paleolimnology》2008,40(1):453-469

Major and trace elements, minerals and grain-size were analysed from a sediment core covering the last 4,000 years of an Austrian Alpine lake (Oberer Landschitzsee, ObLAN, 2,076 m a.s.l.). These analyses were combined with autumn and spring temperature anomalies and ice-cover estimated from a diatom and chrysophyte cyst, thermistor-based regional calibration dataset and selected pollen markers published previously. Diatom-inferred pH (Di-pH) and DOC (Di-DOC) completed the multi-proxy approach, which, together with ordination techniques (PCA and RDA), helped (1) to confirm proposed climatic patterns and hypotheses, and (2) to disentangle the complex interactions between climatic and anthropogenic impacts. Shifts in chemical and physical weathering, erosion, production, lake stratification, redox potentials and air pollution were the major processes that have affected Oberer Landschitzsee in relation to climate, lake/catchment interactions, and human impact. Geochemistry supported the finding that the four waves of high-altitude land use (Early to Middle Bronze, ca. 1,800–1,300 B.C.; Late Bronze to Hallstatt, ca. 1,000–500 B.C.; Celtic to Roman, ca. 300 B.C.–400 A.D.; and Medieval, ca. 1,000–1,600 A.D.) were coupled mainly with warm periods. Increased production, onset of lake stratification, and the deterioration of hypolimnetic oxygen conditions were the major changes governing in-lake processes during climate warming. They resulted in specific element assemblages associated with organic matter accumulation (Br), oxygen depletion (As, Ga, Cu, S), and changes in redox (Fe/Mn). The Se/Di-DOC ratio was introduced to track shifts between in-lake production and allochthonous sources. Nutrient loading from pastures, coupled with climate warming, could explain that in-lake production was highest during Roman and Medieval land use. Lithogenic elements mainly originated from chemical weathering of silicate bedrock and they increased when intense land-use was coupled with climate deterioration and/or increased humidity. These perturbations were highest during a High Medieval climate fluctuation around 1,000 A.D. The association of sand with LOI and C/N and the decoupling of sand from quartz and feldspar separates erosion from physical weathering. Di-DOC, S, and C/N showed hybrid characters in relation to climate and human impact. The mineral proportions indicated gradients in relation to weathering, snow-cover and running waters, as well as vegetation. Air pollution by metallurgic industries, starting during the High Medieval and culminating during the Late Medieval, caused lead accumulation and could have contributed to As and S enrichment. Corresponding features in the distribution of selected elements and pollen tracers, as well as changes in mineral proportions, supported the hypotheses of shifts in seasonal climate and an overall trend towards more continental climate conditions since Medieval times.  相似文献   

基于Landsat 8影像赤壁-嘉鱼地区岩性划分效果分析     

何文熹  王磊  杨玉龙 《华南地质与矿产》2019,35(2):261-269

以鄂东南赤壁-嘉鱼地区为例,在缺少地表各岩石单元样品的情况下,对Landsat8可见光近红外和短波红外(VNIR-SWIR)波段反射率数据进行处理提取岩性信息。首先对VNIR-SWIR多波段反射率数据进行最佳指数因子(IOIF)运算,得出最佳波段组合band7-band5-band2,从其假彩色合成图像上只能识别少量岩性单元;为了减少高相关性波段之间的信息冗余度,并对波段信息进行集成,后对Landsat8VNIR-SWIR波段反射率数据采用主成分变换并进行彩色合成,能够有效增强志留系、侏罗系及第四系地质单元之间的影像差异,从而划分岩性界线。对比已有地质资料,认为提取结果可靠,能为野外地质工作提供基础信息。  相似文献   

晋中地区荞麦品质气候区划的GIS多元分析     

冯美臣  牛波  杨武德  肖璐洁 《地球信息科学学报》2012,14(6):807-813

 探索荞麦的最佳生产布局,为优质荞麦生产的区域化、规模化提供理论和实践依据。本文分析了荞麦品质指标与气象因子的关系,结合荞麦地理分布,筛选影响各品质指标的主要气象因子,利用主成分分析法构建荞麦综合品质评价模型,并以ArcGIS软件的空间分析功能,对荞麦综合品质进行气候区划及区划评述。结果表明:温度、降水、日照时数等气象因子是影响各品质指标的主要因子。较高的均温和日最高温大于30℃时,对荞麦的生长有不良影响,不利于各品质指标的积累。而8月丰富的降水和生育期充足的光照有利于荞麦品质指标的积累。结合评价模型,利用GIS对荞麦综合品质进行区划,将晋中地区分为3个区,即适宜、次适宜、不适宜荞麦种植区,且各区与实际状况基本符合。利用主成分分析法和GIS进行荞麦品质气候区划是可行的,研究结果为荞麦的优质生产提供参考。  相似文献