贵州平坝白云岩风化壳稀土超常富集层中稀土赋存状态的研究

以平坝白云岩风化壳剖面为例,主要利用化学连续提取的方法,结合透射电镜的分析,对碳酸盐岩风化壳岩-土界面附近的稀土超常富集层中REE的赋存状态进行了研究,获得了REE在水溶态及可交换态(相态Ⅰ)、碳酸盐结合态及专性吸附态(相态Ⅱ)、非晶质氧化铁锰结合态(相态Ⅲ)、晶质氧化铁锰结合态(相态Ⅳ)、有机质及硫化物结合态(相态Ⅴ)和残渣态(相态Ⅵ)等6种相态的含量及变化规律.结果表明,REE在富集层中主要以专性吸附态、残渣态和有机态为主.风化前缘可溶态稀土所占比例较高,为稀土在风化壳中的迁移、转化提供可能;基岩中原生含磷稀土矿物的风化产生的稀土磷酸盐矿物的聚集导致了残渣态稀土大量存在于风化前缘;此外,由于风化淋溶的不断进行,可溶态的REE在高的pH值条件与剖面中的有机质、铁锰氧化物和粘土矿物共同作用下沉淀、富集,也导致了风化前缘稀土的超常富集.     

Robust statistical approaches for local planar surface fitting in 3D laser scanning data

This paper proposes robust methods for local planar surface fitting in 3D laser scanning data. Searching through the literature revealed that many authors frequently used Least Squares (LS) and Principal Component Analysis (PCA) for point cloud processing without any treatment of outliers. It is known that LS and PCA are sensitive to outliers and can give inconsistent and misleading estimates. RANdom SAmple Consensus (RANSAC) is one of the most well-known robust methods used for model fitting when noise and/or outliers are present. We concentrate on the recently introduced Deterministic Minimum Covariance Determinant estimator and robust PCA, and propose two variants of statistically robust algorithms for fitting planar surfaces to 3D laser scanning point cloud data. The performance of the proposed robust methods is demonstrated by qualitative and quantitative analysis through several synthetic and mobile laser scanning 3D data sets for different applications. Using simulated data, and comparisons with LS, PCA, RANSAC, variants of RANSAC and other robust statistical methods, we demonstrate that the new algorithms are significantly more efficient, faster, and produce more accurate fits and robust local statistics (e.g. surface normals), necessary for many point cloud processing tasks. Consider one example data set used consisting of 100 points with 20% outliers representing a plane. The proposed methods called DetRD-PCA and DetRPCA, produce bias angles (angle between the fitted planes with and without outliers) of 0.20° and 0.24° respectively, whereas LS, PCA and RANSAC produce worse bias angles of 52.49°, 39.55° and 0.79° respectively. In terms of speed, DetRD-PCA takes 0.033 s on average for fitting a plane, which is approximately 6.5, 25.4 and 25.8 times faster than RANSAC, and two other robust statistical methods, respectively. The estimated robust surface normals and curvatures from the new methods have been used for plane fitting, sharp feature preservation and segmentation in 3D point clouds obtained from laser scanners. The results are significantly better and more efficiently computed than those obtained by existing methods.     

地震波形的分形判别与特征提取

研究地震波的复杂性和它的自相似性以及计算地震道时间序列分数维等一系列特征问题,能得出地震波在复杂构造及断点位置的一系列特征,能轻易地实现地震道异常点的计算机自动拾取。对更深入地研究地震波和更准确地解释地震资料,会有很大的帮助。本文提出了计算地震道分数维的一般方法。实验表明地震道时间序列的分数维在异常点会具有不同的数值,其变化点能够定量指示出异常的准确位置。这对更精确的研究时间剖面上断点及不同地质构造变化有着非常重要的意义。     

不同植被覆盖率地区遥感矿化蚀变提取研究

从遥感图像上识别出的围岩蚀变信息往往是一种弱信息。地表植被和第四系覆盖的干扰,增加了遥感蚀变信息提取的难度。为了研究不同植被覆盖条件下的矿化蚀变信息提取方法,分别选取内蒙古西部戈壁荒漠基岩裸露区（温根地区）、中北部中覆盖草原区（达来庙地区）和东北部高覆盖森林草原区（颇格鲁山地区）,利用TM数据进行遥感蚀变信息提取方法研究,得出以下结论：在基岩裸露地区,利用比值法、主成分分析法均能较好地提取出矿化蚀变信息;在中覆盖草原区,利用掩膜对图像进行预处理,再利用主成分分析法提取矿化信息效果比较好;在高覆盖森林草原区,利用掩膜技术和抑制植被信息方法对遥感数据进行综合处理,再利用比值-主成分分析方法能够提取部分矿化蚀变信息。这些方法对今后在类似地区开展遥感蚀变信息提取工作具有一定的指导意义。     

Determination of experimentally enriched15N in nitrate nitrogen based on an improved method of azo dye formation

A method has been developed for determination of¹⁵N isotope ratio in nitrate nitrogen, which is a major analytical step in tracer experiments for studies of nitrate metabolism in the marine environment. The method is based on diazotization of nitrite with sulfanilic acid following reduction of nitrate to nitrite by a cadmium-copper column. The diazonium compound is then subject to the azo coupling reaction with 2-naphthol, and the azo dye formed is extracted by a solid phase extraction column. The dye eluted from the column is collected, and total nitrogen and¹⁵N content of the dye are determined by mass spectrometry. Sulfanilic acid can also remove preexisting nitrite by heating the sample under acidic conditions before passing through the cadmium-copper reduction column. The average recovery of nitrate nitrogen was 86%. A procedure for reducing the background nitrogen that derives from the analytical operations has been developed; background nitrogen was limited to about 0.25 μg-atomN. The variation in the background nitrogen levels reflects the range of error in¹⁵N determination of nitrate nitrogen by this method. Application of the present method to a¹⁵NO₃ ⁻ isotope dilution experiment for determination of nitrification rate in sea water is demonstrated.     

地电提取法寻找贫硫化物金矿的研究

通过在江西贫硫化物的金山金矿区开展地电提取法寻找贫硫化物金矿的研究,认为金山金矿深部隐伏金矿体存在着较弱的电化学溶解作用。按现有的激发装置,在地表仍能提取到Ａｕ 的异常反映,即用地电提取法来寻找贫硫化物矿床是可行的     

甲壳素提取方法的研究进展

甲壳素是一类重要且应用广泛的天然高分子。海洋甲壳类加工副产物,如虾壳、蟹壳等,是甲壳素的重要来源之一,常见的提取方法主要有化学法、酶法、微生物发酵法等,其中微生物发酵法是一种依赖微生物发酵完成脱矿(DM)、脱蛋白(DP)过程的方法,整个过程不引入任何化学试剂,绿色无污染,是解决目前甲壳素生产过程中酸、碱用量大导致污染严重的关键技术。本文综述了各种甲壳素提取方法及各种影响因素在提取过程对所得甲壳素性质的影响,讨论了微生物发酵法的相关内容,以期为相关研究提供理论支撑。     

中巴资源一号卫星湖泊信息提取——以南京景为例

中巴地球资源一号卫星（CBERS－1）是我国的第一颗地球资源卫星,它的发射成功及运行,解决了长期依赖国外卫星数据的缺陷,本文简要介绍了CBERS－1的传感器类型,并利用CBERS－1 1999年11月29日过境的南京景数据,根据图幅特点,将水质信息尤其是该区内的湖泊信息加以提取,进行分析,较为详实的分析了区内湖泊所面临的环境问题。     

水稻(Oryza sativa L.)秸秆浸提液对铜绿微囊藻(Microcysti aeruginosa)的抑制作用

用刚收割的水稻(Oryza sativa L.)秸秆浸提液代替水配制培养基培养铜绿微囊藻(Microcystic aeruginosa),追踪测定微囊藻的生物量、叶绿素a含量、光合速率、呼吸速率、膜透性、超氧物歧化酶(SOD)活性、光合膜自发荧光强度等相关生理生化指标的变化,研究水稻秸秆浸液对铜绿微囊藻的抑制作用.结果表明,质量比≥1/100(水稻秸秆/水)的水稻秸秆浸提液对微囊藻的生长有明显的抑制作用,表现如下:藻细胞生物量在实验过程中逐日降低,藻细胞叶绿素a含量和光合速率急剧下降,呼吸速率和超氧物歧化酶(SOD)活性呈先升高后下降的趋势,膜透性迅速升高,细胞光合膜自发荧光强度显著衰减.用不同的有机溶剂对该浸提液进行萃取,浓缩后用滤纸片法在固体培养基上做抑藻实验,乙醚和乙酸乙酯萃取液能明显看到抑藻圈,证实其中含有抑制物质.     

深海能源土含气储层力学特性三轴试验研究

为研究深海能源土在负压开采过程中含气储层的力学特性,基于含气土赋存理论,提出一种能够控制含气量及气泡大小的制样方法,通过GDS标准应力路径三轴试验系统,开展深海能源土含气储层的固结排水试验研究,分析深海能源土在不同黏土含量及不同含气量下的力学响应规律。研究结果表明：围压变化对深海能源土含气储层的抗剪强度峰值大小影响显著,围压越大抗剪强度峰值越高;黏土含量是决定应力应变曲线变化趋势的关键影响因素,黏土含量越高试样抗剪强度越低,试样抵抗应变软化效应的能力越强;含气土比饱和土体承载能力更低,且承载能力随含气量的增大呈衰减趋势;黏土含量和含气量是深海能源土含气储层抗剪强度指标的重要影响因素,黏土含量、含气量越高,土体自身的总抗剪强度值越低。