Evaluating the Effects of Autofluorescence during Raman Hyperspectral Imaging

Raman hyperspectral imaging is becoming a popular technique to analyse geological materials. Autofluorescence can affect the quality of the spectra that comprise hyperspectral data sets. Few studies have addressed potential misinterpretation of Raman images from hyperspectral data sets affected by autofluorescence. Additionally, little work has been done to develop methods for identifying the spatial distribution of spectra affected by autofluorescence. This study illustrates how autofluorescence may lead to misinterpretation of the distribution of materials based on intensity at a point images. A method is proposed utilising signal to axis analysis to create images that identify regions affected by autofluorescence. Post‐processing baseline correction is often used to address autofluorescence, and most software programs utilise a form of partial least squares regression modelling based on a subjective choice of polynomial order. This study shows that an inappropriate choice of polynomial order can introduce error, which may lead to misinterpretation of Raman images. A signal to axis analysis method is proposed to statistically compare seemingly ‘appropriate’ baseline correction trials. Although post‐processing of hyperspectral data sets and creating Raman images seem simple, data quality issues such as autofluorescence must be considered. If baseline correction is deemed necessary, it should be addressed as an experiment involving statistical comparison.     

崂山湾网采浮游植物时空分布特征及其与环境因子关系

为了解崂山湾浮游植物群落年际变化特征,在该海域设置了14个监测站位,于2012年-2014年每年3,5,8,11月采用浅水Ⅲ型浮游生物网进行了12个航次调查,并同步监测其它环境因子。共鉴定浮游植物127种,隶属于硅藻、甲藻、金藻、蓝藻、绿藻5大门类25科47属,其中硅藻16科36属105种,占种类数的82.7%;甲藻6科8属19种,占种类数的15.0%;金藻、蓝藻、绿藻各1科1属1种。优势种季节更替明显,3月份主要优势种为冰河拟星杆藻、中肋骨条藻和加拉星杆藻等,5月优势种为夜光藻、尖刺拟菱形藻和密联角毛藻等,8月优势种为三角角藻、尖刺拟菱形藻和派格棍形藻等,11月份优势种为虹彩圆筛藻、派格棍形藻和冰河拟星杆藻,浮游植物群落年际相似性在42%水平聚类分为春夏秋冬四大类群。浮游植物丰度季节更替明显,上下半年均有一个高峰期,上半年高峰期出现在3月,平均丰度169.2×104cell/m3,下半年高峰期在8月,平均丰度51.8×104cell/m3。绝大部分时间浮游植物丰度由近岸向远海呈递减趋势,高值区出现在田横岛西侧和鳌山卫东北面的内湾处,低值区位于远离崂山湾的外侧海域。群落Shannon-Wiener多样性指数平均2.305(1.829—2.745),Margalef丰富度指数平均0.987(0.634—1.507),Pielou均匀度指数平均0.675(0.466—0.815)。浮游植物丰度很大程度上取决于硅藻丰度,二者均与盐度、铵盐、叶绿素a、N/P呈极显著正相关(P0.01),与p H和无机氮显著正相关(P0.05),而与水温呈显著负相关(P0.05)。甲藻丰度与无机氮和铵盐含量呈显著负相关(P0.05)。物种多样性指数与化学需氧量显著正相关(P0.05),与无机氮、总磷和活性磷酸盐显著负相关(P0.05)。     

三峡树坪滑坡动力学的有限元模拟

三峡工程是迄今为止最大的水利工程,对库区滑坡灾害的监测和机制研究一直是重要的研究课题。本文利用Terra SAR-X的强度图进行相关计算,求解出2009年5月20日至8月5日期间三峡树坪滑坡的形变场。该形变场特征和树坪滑坡体的地形特征吻合甚好,位移大小、方向和三峡大学对滑坡体的野外观测结果基本吻合。以此高精度位移场为外部约束,结合野外观测资料对滑坡体介质力学性质进行分类并选取边界条件,利用有限元方法对滑坡活动进行动力学计算模拟。计算过程中对滑坡体的滑动面形状、因降雨引起材料参数变化和三峡水库水位等因素分别反演和调整,得出符合其变形和发展过程的滑坡动力学特征。发现软弱带的物性参数决定滑坡体总体滑动量,滑坡体的物性参数决定位移分布的峰值位置。在确定了滑坡动力学特征之后,进一步讨论降雨和库区水位下降对滑坡产生的贡献权重,得出降雨是树坪滑坡的决定因素。     

湘黔桂相邻区新元古代820～635Ma时期裂谷盆地充填序列与地层格架

湘黔桂相邻区发育一套序列完整、界面清楚的武陵造山运动不整合面之上至震旦纪(820~635 Ma)时期的裂谷盆地沉积地层。通过详细的区域岩石地层划分与对比,结合年代学研究成果,显示其时空展布格局完整,充填序列连续,划分标志清楚,完全可以划分对比。在此基础上建立了其地层格架,为扬子古大陆周缘新元古代820~635 Ma时期地层划分对比研究提供了详实的资料,亦为中国前寒武系新元古代地层划分对比及国际新元古代研究提供了新的资料成果。     

Swelling model study of expansive soil at K-0 and triaxial stress stateEI北大核心CSCD

A series of swelling tests is performed on a typical Nanyang expansive soil with medium swelling capacity compacted at various initial densities and water contents. The swelling tests are separately conducted using the conventional oedometer to confine the lateral swelling of the soil specimens, and using the GDS triaxial apparatus to allow the free volumetric swelling. The multiple nonlinear mathematical method is adopted to obtain the lateral swelling model (i.e. K-0 model), which fully considers the coupled effect of initial degree of compaction, moisture content and overburden pressure on the swelling strain. Also, an empirical model for the relationship between spherical stress and volumetric strain is proposed by triaxial swelling test. Based on the K-0 swelling model, a formula is proposed to quantitatively evaluate the swell potential, and also a theoretical calculation method is derived to determine the processing layer thickness of expansive soil slope. Based on the assumption that volumetric swelling strain only changes with spherical stress and is not affected by the deviatoric stress, the correlations between the K-0 model and triaxial model are analyzed, and a method to calculate the volumetric swelling strain by only employing the K-0 model is given. Experimental results show that the proposed K-0 model with multifactor coupling is reasonable to predict the swelling potential of compacted expansive soil. It is found that the key factor to link the K-0 model and triaxial swelling model is assuming an average static lateral pressure coefficient. The average static lateral pressure coefficient tends to decreases with increasing overburden pressure by inversion method. This tendency of average static lateral pressure coefficient is believed to rely on the fact that lateral swelling pressure decreases with the increase of overburden pressure.     

基于灰色关联模型的南京市碳排放驱动因素研究

全球气候变暖已经成为不争的事实,人们逐渐认识到依靠大量能源消费的生产方式、不惜牺牲环境的经济增长模式、无节制大量消费的生活方式应该从根本上得到改变.城市作为工业、建筑、交通的载体,也是高能耗、高碳排放的主要源头,需要改变传统城市发展的模式来应对全球变暖的挑战,发展低碳城市被认为是未来最有希望的经济发展动力.首先采用IPCC能源转换模型对南京市碳排量进行测算,选取南京的人口数量、GDP、人均GDP、人口城市化率、产业结构多元化系数（ESD）、能源消费结构多元化系数（ESCD）和能源强度作为对比数列,以南京CO₂排放总量作为参考数列,运用灰色系统关联模型进行关联度计算并排序.结果显示,南京市碳排放量关联度从大到小依次为ESD、人口数量、城市化率、ECSD、能源强度、人均GDP、GDP,这与南京工业生产因化石能源的大量使用对城市碳排放量贡献占总排量一半以上的分析结果相吻合.最后详细分析各指标对南京建设低碳城市的影响,并提出对策建议.     

2012年夏季北极浮冰生物群落结构及垂直分布特征研究

海冰生物群落是北极生态系统的重要组成部分,在北冰洋初级生产和碳循环中扮演着重要角色。本文利用荧光显微分析技术对2012年度夏季采集于北冰洋中心区的浮冰生物群落进行了分析,结果显示：柱总生物量平均为105.85±53.41 mgC •m^-2,其中细菌占生物量的47.2%,而后依次是硅藻（26.7%）,鞭毛虫（18.2%）,鞭毛藻（6.9%）和纤毛虫（1.0%）。最高纬站位（123°43.454′E 87°39.598′N）出现冰底鞭毛藻藻华现象,生物量可达329.6 μg C•L^-1,该站位生物群落处于硅藻藻华后期,海冰上层存在较大程度的融冰作用,底部冰芯营养盐N/P比较高,可能形成有利于鞭毛藻生长的小生境。与已有研究结果的对比表明,近年来夏季北极海冰的快速融化对浮冰生物群落结构产生了明显影响,异养类群生物量升高,细菌取代硅藻成为优势类群。     

A universal spectral analytical method for digital terrain modeling

There are three major mathematical problems in digital terrain analysis: (1) interpolation of digital elevation models (DEMs); (2) DEM generalization and denoising; and (3) computation of morphometric variables through calculating partial derivatives of elevation. Traditionally, these three problems are solved separately by means of procedures implemented in different methods and algorithms. In this article, we present a universal spectral analytical method based on high-order orthogonal expansions using the Chebyshev polynomials of the first kind with the subsequent Fejér summation. The method is intended for the processing of regularly spaced DEMs within a single framework including DEM global approximation, denoising, generalization, as well as calculating the partial derivatives of elevation and local morphometric variables.

The method is exemplified by a portion of the Great Rift Valley and central Kenyan highlands. A DEM of this territory (the matrix 480 × 481 with a grid spacing of 30″) was extracted from the global DEM SRTM30_PLUS. We evaluated various sets of expansion coefficients (up to 7000) to approximate and reconstruct DEMs with and without the Fejér summation. Digital models of horizontal and vertical curvatures were computed using the first and second partial derivatives of elevation derived from the reconstructed DEMs. To evaluate the approximation accuracy, digital models of residuals (differences between the reconstructed DEMs and the initial one) were calculated. The test results demonstrated that the method is characterized by a good performance (i.e., a distinct monotonic convergence of the approximation) and a high speed of data processing. The method can become an effective alternative to common techniques of DEM processing.     

Genesis of lower strain S-L-type tectonites in Daqingshan area,Inner Mongolia

Usual ductile shear zone has relatively high strain magnitude.However,for high-grade metamorphic rocks in Daqingshan area,the related strain is very low with weakly developed lineation.Significantly,the fi-nite strain type with a K-value slightly lower than 1 and is characterized by compressional strain.Because the special tectonic environment with high temperature,the percentage of melt is relatively higher,which leads to a series of microscopic phenomenon such as multi-grain quartz bands,feldspar three edges equilibrium-like tex-ture,granular flow,etc.As a consequence,the tectonites in the studied area illustrate a unique character:ob-vious rheological meso-deformation structure but with very weak intracrystalline micro-deformation.     

Application of partial least squares regression and WetSpa model to determine factors controlling sediment yield in Chardavol watershed,Iran

This paper examines the effects of watershed complexity in terms of physiography and land use on the specific sediment yield of the Chardavol watershed (1012.946 km²) in Iran. First, specific sediment yield was simulated using spatially distributed hydrological WetSpa model, then the influential factors such as morphometric variables, land-use composition and pattern and soil properties of the watershed were calculated at the sub-watershed scale. Due to the inter-reliant of these watershed characteristics, a partial least squares regression (PLSR) was used to illustrate the relationship between the specific sediment yield and data of 15 selected watershed characteristics. The results showed that the land-use composition and soil properties had the maximum effects on the specific sediment yield and clarified 79% of the variation in the specific sediment yield. Regarding the availability of digital spatial database over the watershed, this simple PLSR procedure could be applied in different watersheds.