Soil discrimination using diffuse reflectance Vis–NIR spectroscopy in a local toposequence

Vis–NIR spectroscopy is nowadays presented as a possible routine method for soil sample analysis. However, there is still no consensus on which is the best multivariate statistical method to use. We propose to use principal component analysis to complete the spectral data treatment. The soil samples came from a pedological cover made up of red–yellow Latosols: 88 samples of 11 soil profiles on four toposequences were collected; clay, organic matter, silica, iron, aluminum and titanium total contents were determined; the contents of goethite, hematite, gibbsite, and kaolinite were calculated. Diffuse reflectance Vis–NIR spectroscopy at wavelengths from 400 to 2400 nm combined with principal component analysis (PCA) was sufficiently sensitive to discriminate different Latosols. Wavelengths of 700 nm and 2200 to 2300 nm were influenced by content ratios of organic matter and iron oxides (700 nm), and kaolinite and gibbsite absorption (2200 and 2300 nm). The spectral responses were affected not only by the content of these constituents, but also by the composition of the minerals, so that the same class of Latosol may have different or similar spectral responses. The role of microaggregation is discussed.     

西藏冈底斯地区斑岩铜矿识别的最佳多光谱遥感异常判据研究

文章应用多光谱遥感技术,对冈底斯斑岩铜矿带的实例(驱龙、甲玛、朱诺、冲江、夏玛日等矿床)进行了研究和总结,包括ASTER和ETM+数据技术特征、蚀变异常找矿的地质依据、蚀变异常提取的波谱前提、多光谱矿致遥感异常提取的常见技术方法、去干扰异常主分量门限化技术流程、冈底斯斑岩铜矿带找矿模型最佳遥感异常判据研究等.确定了ASTER主分量分析提取的羟基异常OHA6、OHA5同心套合异常可做为斑岩铜矿的最佳多光谱遥感异常判据,在从夏玛日至朱诺的13景共46万平方公里的ASTER提取异常中,依此判据圈定了冈底斯20处有潜能的斑岩铜矿异常.此外,还对夏玛日景遥感异常进行了解译,并提出了3处钻孔孔位建议.     

基于PCA和BP神经网络的径流预测

径流预测为流域水资源的合理开发利用与统筹配置提供依据。运用多元线性回归、主成分回归、BP神经网络及主成分分析和BP神经网络相结合的方法,对新疆呼图壁河流域石门水文站2009-2011年各月径流量进行预测,并采用相关系数、确定性系数及均方根误差对各模型预测精度进行比较。结果表明：（1）神经网络等智能算法具有高速寻优的能力,对短时间尺度的月径流量的预测结果较好;（2）主成分回归等常规算法能充分反映出某地区径流的年际的稳定性,对全年径流总量的模拟精度较高;（3）主成分分析和BP神经网络相结合的方法,提高了神经网络的收敛速度,同时降低了局部极值的影响,优于简单的BP神经网络,适用于呼图壁河月径流量预测。     

基于Wigner双谱对角切片的谱分解技术在油气检测中的应用

谱分解技术作为一种解释性处理技术得到了地质、地球物理工作者的广泛关注,如何有效地利用其分频显示功能进行油气检测也成为人们关注的一个焦点。利用Wigner高阶谱具有高时频聚集性的特点,提出了一种基于改进核函数的Wigner双谱对角切片的谱分解技术。即在分析指数型核函数与锥形核函数优缺点的基础上,给出了改进的新核函数,进而采用模糊域核函数滤波法抑制Wigner双谱对角切片的交叉项,并解决了Wigner双谱对角切片的模糊函数中心点校正问题。通过对新的核函数交叉项抑制能力的数值模拟,验证新的核函数对时延轴上的交叉项也能抑制。最后对实际地震数据进行了分频处理,在20 Hz低频剖面内的油气有利区表现为强能量显示,与井的钻遇结果一致。     

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南洛河流域洛南盆地表土孢粉与植被的关系

选取南洛河上游洛南盆地10 种植被类型下40 处样点表土苔藓开展孢粉与植被关系的研究.结果表明,表土中孢粉组成能很好地反映植被类型.森林表土中乔木植物花粉含量平均值大于40%,且有较高含量的中华卷柏孢子;疏林草原、灌丛群落中乔木植物花粉平均含量分别为13.2%和16.6%,灌木植物花粉相对草丛群落含量较高;草丛群落和农田中乔木花粉平均含量均<10%,草本植物花粉>80%,灌木植物花粉<1%.洛南盆地表土孢粉总浓度平均为1.42×10⁵粒/g,与植被覆盖度关系较弱,而与植被类型有一定联系,能辅助植被类型的辨识.聚类分析和PCA分析都能较好区分森林和非森林植被,前者能较好地区分松林和混交林,后者能较好地区分农田和灌、草丛植被,且比聚类分析更加稳定.松属、栎属等乔木花粉具有较强的扩散能力,能指示区域植被,松属没有表现出很强的超代表性,栎属具有低代表性;蒿属花粉与植被覆盖度间的相关关系较差,具有明显的超代表性,其大量出现与人类的干扰有一定的联系,禾本科花粉具有很好的植被指示性和低代表性,藜科花粉的高含量主要指示了高强度的人类活动;中华卷柏孢子在地层中的大量出现具有指示森林或松林环境的意义.     

Annual and spatial variations of chemical and physical properties in the Ross Sea surface waters (Antarctica)

Temperature, salinity, meltwater percentage, water column stability, dissolved oxygen and nutrients were measured in seawater samples collected at three fixed depths (0, 20, 100 m) in 104 stations located in three different areas of the Ross Sea (Antarctica), during four Italian Antarctic surveys carried out between 1998 and 2006. Nutrient data were used to quantify the nutrient removal, which appears particularly high in 2006, especially in polynya area. The N:P and Si:N disappearance ratios were studied to estimate the dominant phytoplanktonic community. No significant differences in the nutrient drawdown ratio were observed, in fact the N:P ratio was always below the Redfield standard ratio.     

Biogeographical distribution and diversity of bacterial and archaeal communities within highly polluted anoxic marine sediments from the marmara sea

Physicochemical and microbiological characterization of anoxic sediments taken from seven highly polluted sites of the Marmara Sea was carried out. The 16S rRNA based microbial community structure analyses were performed using domain-specific PCR followed by denaturant gradient gel electrophoresis (DGGE) and sequencing of characteristic bands. The results showed that the microbial communities in these sediments were diverse and evenly distributed. Relating the prokaryotic and geochemical variables through statistical tools revealed that the microbial diversity in the sediments significantly related to depth, and S, Mn and Fe content of the sediments. Fermentative bacteria, denitrifying bacteria and hydrogenotrophic methanogens were dominant whereas sulfate reducing bacteria were absent in the DGGE patterns. This unusual microbial community structure implied that the newly discovered anaerobic methane oxidation coupled to denitrification process may occur in these subseafloor environments.     

利用独立分量分析进行火山灰云遥感检测

火山灰云不但引起全球气候和环境系统的重大变化,而且还会威胁航空安全。热红外遥感技术为检测火山灰云提供了新手段,但是遥感数据自身的冗余和波段相关性大大降低了火山灰云的检测精度。独立分量分析(Independent Component Analysis,ICA)能够实现遥感数据的去相关和消除冗余,在火山灰云检测中具有一定的潜力。通过探索火山灰云的物理、化学性质,文中以2010年4月19日冰岛艾雅法拉(Eyjafjallajokull)火山灰云MODIS图像为数据源,在对MODIS数据进行主成分分析处理的基础上,利用ICA进行火山灰云检测。结果表明:ICA能够较好地从MODIS图像中获取火山灰云信息,所得结果与美国地质调查局标准光谱数据库和火山灰云SO2浓度分布具有较好的一致性,取得了较好的检测效果。     

基于对象变化矢量分析的土地利用变化检测方法研究

变化检测是资源和环境遥感应用的一个重要内容。在变化矢量分析法的基础上,本文提出采用变化矢量-主成分分析法提取研究区变化信息,首先,对不同时相的遥感影像进行差值运算得到差值影像,再对其进行主成分变换并选取主分量,最后,使用多尺度分割获取影像对象。在影像分割的基础上,采用变化矢量-主成分分析方法构建自动检测规则提取变化信息,并作精度评价。研究表明：基于对象的变化矢量-主成分分析方法不仅可克服传统的基于像元式方法难以利用空间信息的缺陷,有效避免了“椒盐”噪声,而且可将多波段差值信息经主成分变换后集中在几个累计贡献率较高的主成分分量上;同时,结合了变化矢量法与主成分分析法的优点,与单独使用变化矢量分析法相比提取精度明显提高。