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991.
提出"全域-局部"遥感信息分布提取模型,通过计算和整合影像局部范围内的空间和光谱特征来优化全域上光谱混淆较大像元的提取精度。模型分为两个主要计算步骤:"全域"前分类与"局部"后分类;"全域"前分类将仅划分出满足一定精度阈值标准的像元,而"局部"后分类则在此部分分类结果基础上,进一步发掘和计算已分类像元所蕴含的信息来辅助对全域未分类像元的提取。在不透水面专题提取过程中,采用支持向量机SVM作为前分类器,通过控制精度阈值所对应的分类后验概率产生部分分类结果;采用调节最小距离分类器作为后分类器,根据一定的权重整合像元局部范围内的空间与光谱信息,代替了传统的全域光谱信息来优化分类。实验采用TM5影像以及所对应的NLCD(National Land Cover Data)标准不透水面产品作为测试集,"全域-局部"模型对应单一SVM模型的提取精度由80.31%提高为82.73%,局部后分类器精度较单一SVM模型由54.27%提高到59.94%。实验证明该模型具有较明显的精度提升且能够较好地解决不透水面与裸土混淆的问题,并得到空间形态上更为完善的不透水面提取结果。 相似文献
992.
This paper presents a framework for road network change detection in order to update the Canadian National Topographic DataBase (NTDB). The methodology has been developed on the basis of road extraction from IRS-pan images (with a 5.8 m spatial resolution) by using a wavelet approach. The feature matching and conflation techniques are used to road change detection and updating. Elementary experiments have showed that the proposed framework could be used for developing an operational road database updating system. 相似文献
993.
994.
《水文科学杂志》2013,58(5):992-1003
Abstract The extreme Tyne (Northumbria, UK) flood in January 2005 provided the opportunity to reassess flood risk and to link peak discharge and flooded area to probability of occurrence. However, in spite of the UK guidance on flood risk assessment given in the Flood Estimation Handbook (FEH), there is still considerable subjectivity in deriving risk estimates. A particular problem for the Tyne arises from the effects of river bed gravel extraction both on the reliability of gauged discharges and in the interpretation of historical level data. In addition, attenuation and drawdown of Kielder Water has reduced downstream flood risk since 1982. Estimates from single-site, pooled estimates and historical information are compared. It is concluded that the return period of the observed flood was around 71 years on the lower Tyne and was probably the largest flood since 1815. 相似文献
995.
The need for quantitative molecular methods is growing in environmental, food, and medical fields but is hindered by low and variable DNA extraction and by co-extraction of PCR inhibitors. DNA extracts from Enterococcus faecium, seawater, and seawater spiked with E. faecium and Vibrio parahaemolyticus were tested by qPCR for target recovery and inhibition. Conventional and novel methods were tested, including Synchronous Coefficient of Drag Alteration (SCODA) and lysis and purification systems used on an automated genetic sensor (the Environmental Sample Processor, ESP). Variable qPCR target recovery and inhibition were measured, significantly affecting target quantification. An aggressive lysis method that utilized chemical, enzymatic, and mechanical disruption enhanced target recovery compared to commercial kit protocols. SCODA purification did not show marked improvement over commercial spin columns. Overall, data suggested a general need to improve sample preparation and to accurately assess and account for DNA recovery and inhibition in qPCR applications. 相似文献
996.
太湖蓝藻水样中藻蓝蛋白提取方法比较 总被引:1,自引:1,他引:0
以2011年8月20日采集的太湖梅梁湾的夏季蓝藻水华为研究对象,通过12个样点平行样的藻蓝蛋白实验提取,基于光谱吸收特征和浓度值,对反复冻融法、超声波法、溶胀法、丙酮法的提取效果进行比较评价.结果表明:4种方法获取的藻蓝蛋白提取液在620 nm附近出现吸收峰,其中,反复冻融法的峰高最强,超声波法最弱,说明反复冻融法的提取效果优于其他方法;反复冻融法、超声波法、溶胀法获取的部分蓝蛋白提取液在670 nm附近具有次吸收峰,与藻蓝蛋白标样的吸收曲线存在差异;反复冻融法、超声波法提取的藻蓝蛋白浓度值变异系数小于0.6,表明这两种方法较其他方法稳定;反复冻融法提取的藻蓝蛋白浓度值高于其他3种方法,可推荐作为太湖蓝藻水样中藻蓝蛋白的提取方法. 相似文献
997.
The European Water Framework Directive (WFD) commits European Union member states to achieving good ecological status in all water bodies by 2015. For sediments the definition of good chemical status is based on numerical sediment quality guidelines. The aqua regia fraction is thus used for the evaluation of heavy metal concentrations in sediments. The chemical constituents in sediments responsible for mobility and toxicity are not considered generally. This article presents the combining of the sequential BCR procedure, for determining the chemical species of relevant elements, with the geoaccumulation index principle a numerical classification method for sediment quality guidelines. Using the BCR method it can be demonstrated that changes in element speciation can lead to more highly mobile species of trace elements which may affect the hazardous potential of sediments despite the “good chemical status” classification for aqua regia digestions. The Klinke stream is an urban surface water body located in Magdeburg, the state capital of Saxony‐Anhalt, Germany. Using this stream as an example it is shown that this additional information helps to describe the dynamics and discharge of the trace elements Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Rb, Sr, Mo, Pd, Cd, Sb, Ba, Pb, Bi, and U into the Elbe River from urban water bodies. 相似文献
998.
Sukran Akkus Tulin Bal Nagihan M. Karaaslan Emre Yaman Ersin Kilinc Mehmet Yaman 《洁净——土壤、空气、水》2013,41(12):1229-1234
Five‐step sequential extractions were employed to fractionation of Ni, Cr and Cu in soil polluted by anthropogenic activities and determine the mobility of the metals. Twelve samples were collected on an agricultural area that was located near an airport and intercity roads in Elazig‐Turkey. Exchangeable, organically bounded, carbonate bounded, adsorbed species on Fe and Mn oxides and residual species (except silicates) of Ni, Cr and Cu were extracted into solution by using CaCl2, Na4P2O7, Na2EDTA, NH2OH–HCl and HNO3–H2O2, respectively. Mobile metal concentrations in fractions and total recoverable in soils were determined by using inductively coupled plasma‐optical emission spectrometry (ICP‐OES). Total recoverable Ni, Cr and Cu concentrations were in the range of 40–119, 45–126 and 23–72 mg kg?1, respectively. It was observed that total concentrations of metals in some of the samples were higher than the permitted values. The sum of the mobile percentages of metals was found to be lower than 50%. The Ni, Cr and Cu percentages for exchangeable species are in the ranges of 0.18–1.64, 0.03–0.59 and 0.42–2.53%, respectively. 相似文献
999.
研究了一种基于雷达后向散射特性,从单张星载高分辨率SAR影像提取建筑物高度的方法。该方法通过检测建筑物二次散射强度,同时获取目标方位角、入射角等参数以及相关介质特性等信息,根据后向散射几何光学模型估算建筑物高度。实验验证了对于相当一部分典型建筑物都能够获得较为理想的高程估计值,进而证明了该方法提取建筑物高度的可行性和有效性。 相似文献
1000.