基于支持向量机的测井岩性识别在松散沉积物调查中的应用研究

砂砾质松散沉积物粒径组成复杂,钻探取心率低,导致对沉积相和相界面的判别准确度不高。本文结合岩心和测井资料,建立了松散沉积层基于支持向量机的测井数据岩性识别模型,分析了训练集样本数量对模型识别准确率的影响,并与BP神经网络模型进行了对比。结果表明,支持向量机模型的岩性识别准确率高,且对训练样本需求量低,可以有效地弥补钻孔取心率不足的问题,并降低钻探施工成本。在松散沉积物调查中,利用基于支持向量机的测井岩性识别模型自动识别沉积序列具有可行性,是实现绿色勘查的有益尝试。     

1973—2015年努尔苏丹气温变化与城市热岛效应

基于1973—2015年努尔苏丹市和阿科尔镇逐日气温数据,以及努尔苏丹2000—2015年城市发展数据,采用回归分析、七点二次平滑、Mann-Kendall突变检验、滑动T检验等分析方法研究了该区域气温和城市热岛强度的变化特征及成因.结果表明:(1)在同期北半球和中亚地区气温显著增长的大背景下,努尔苏丹年平均气温并无显...     

Sources of organic matter for bacteria in sediments of Lake Rotsee,Switzerland

Determination of carbon sources and microbial activity in lake sediment is important for understanding organic carbon preservation and methane production. This study aimed to determine the organic carbon sources and microbial activity over the last 140 years in sediments of methanotrophic Lake Rotsee (Switzerland). We investigated phospholipid-derived fatty acid biomarkers and their stable carbon isotope signatures in the sediments of this eutrophic lake. Strong bacterial activity in the sediment deposited during the 1920s–1960s could account for the relatively low ratio of long-chain to short-chain fatty acid ((C24 + C26 + C28)/(C14 + C16 + C18), TAR_FA) values, which is consistent with low TOC/TN ratios in the sediment deposited during that interval. The carbon stable isotope records, both bulk and compound-specific, showed greater values at such times, although the offset between the bulk and fatty acids decreased. This implies that the microbial community residing at sediment depths deposited in the 1960s preferentially utilised the compounds derived from the enhanced surface-water productivity at that time. This observation contrasts with data from the depth intervals before and after, when a major portion of the labile organic matter was derived from methane-sourced production. In sediments deposited before ca. 1964, the overall very low fatty acid δ¹³C values suggest that labile carbon was primarily derived from methanotrophs.     

VS垂直摆倾斜仪常见异常现象的判断及维护

针对地震台站使用的VS垂直摆倾斜仪,对其典型的异常现象进行分析,并给出了维护方法.     

深度细粒度图像识别研究综述

细粒度图像分类是计算机视觉中一项基础且重要的工作,其目的在于区分难以辨别的对象类别（例如不同子类的鸟类、花或动物）.不同于传统的图像分类任务可以雇佣大量普通人标注,细粒度数据集通常需要专家级知识进行标注.除了视觉分类中常见的姿态、光照和视角变化因素之外,细粒度数据集具有更大的类间相似性和类内差异性,因此要求模型能够捕捉到细微的类间差异信息和类内公有信息.除此之外,不同类别的样本存在不同程度的获取难度,因此细粒度数据集通常在数据分布中表现出长尾的特性.综上所述,细粒度数据分布具有小型、非均匀和不易察觉的类间差异等特点,对强大的深度学习算法也提出了巨大的挑战.本文首先介绍了细粒度图像分类任务的特点与挑战,随后以局部特征与全局特征两个主要视角整理了目前的主流工作,并讨论了它们的优缺点.最后在常用数据集上比较了相关工作的性能表现,并进行了总结与展望.     

Geological characteristics and tectonic implications of the deformed granite in Lalong area in the southern margin of Gangdise

In the Gangdise magmatic arc develops an important ductile shear zone. In order to peer deeper into the genesis of the deformed granite and its deformation and properties, the authors studied the whole rock geochemistry, deformation structure and zircon U-Pb geochronology of the deformed granite in Lalong area in the southern margin of Gangdise. It is found that the deformed granite is distributed in nearly EW direction, the north side contacts with Mesozoic Mamuxia Formation along a fault,and the rest is covered by Quaternary system,after the geological profile measurement and field geological mapping of the deformed granite exposed in Lalong area in the southern margin of Gangdise.The main rock type is tonalite, belonging to high silica calc alkaline series. SiO₂ content ranges from 66.2% to 71.0%, with an average of 68.3%. The content of total alkali (Na₂O + K₂O) is higher,so is the content of Al₂O₃ and MgO.The content of light rare earth elements (∑LREE) is higher than that of heavy rare earth elements (∑HREE). Rb, Th and other large ion lithophile elements are enriched, while Ta, Zr, Nb and other high field-strength elements are depleted. Sr content is high, Y content is low, and Sr/Y value is 73.02~99.05. All shows that the rock has the adakitic rock characteristics. The LA-ICP-MS zircon U-Pb age of the deformed granite is (83.56±0.83) Ma, which is the late Cretaceous and represents the magmatic crystallization age.The deformed granite was mainly formed by partial melting of the thickened lower crust under the background of northward subduction and reduction of Neo-Tethys Ocean. During Miocene 28~13 Ma, the deformed granite underwent nearly EW trending left-lateral shear and northward slip ductile shear deformation.     

The Relationship between Phototropism and Plate Motion

<正>Objective Plant phototropism means that trees on the side directly exposed to sunlight generally grow faster than those on the opposite,and positive phototropism is easy to observe in crown and trunk.In this study,we chose the transverse section of tree trunk to observe.The definitive intensity of plant phototropism ranges regularly from strong to weak     

浅水湖泊底栖-敞水生境耦合对富营养化的响应与稳态转换机理:对湖泊修复的启示

浅水湖泊中的初级生产者主要由分布在底栖生境中的底栖植物和生活在敞水生境中的浮游植物组成.底栖植物主要包括维管束沉水植物和底栖藻类等,浮游植物则主要为浮游藻类.贫营养浅水湖泊湖水营养盐浓度低,透明度高,底栖植物因能直接从沉积物中获取营养盐,往往是浅水湖泊的优势初级生产者.随着外源营养盐负荷的增加,湖水中的营养盐浓度不断升高,浮游植物受到的营养盐限制作用减小,加上其在光照方面的竞争优势,逐步发展成为湖泊的优势初级生产者,湖泊逐步从底栖植物为优势的清水态转变为浮游植物为主的浑水态,即稳态转换.在稳态转换过程中,浅水湖泊生态系统结构与功能发生了一系列变化,本文综述了浅水湖泊沉积物性质和生物(浮游植物、底栖植物、底栖动物和鱼类等)群落结构的变化,分析了这些变化对底栖植物、浮游植物之间竞争优势和底栖-敞水生境间磷交换的影响,探讨了富营养化驱动的底栖-敞水生境耦合过程变化和稳态转换机理.了解浅水湖泊底栖-敞水生境耦合过程与稳态转换机理对富营养化浅水湖泊修复有重要意义.富营养化浅水湖泊修复实际就是重建其清水态,在制定修复目标时应该关注评价清水态的指标,如透明度、浮游植物生物量、底栖植物的覆盖度或优势度...     

基于湖泊沉积物多指标的水生植被长期演替过程的定量重建

水生植被是湖泊生态系统最重要的一种生态组份,了解其群落的结构与演化,是理解湖泊生态系统特征的必备条件,对揭示水生生态系统演替过程及驱动效应、水生生态系统的修复等具有重要意义。然而,除了有限的既往观测/文献记录外,重建历史时期的水生植被演替过程一直是第四纪地质、水环境变化研究的一个难点。文章在概述国内外目前已有的多种重建历史水生植被的研究方法的基础上,重点关注基于湖泊沉积物多指标,主要包括利用孢粉、植物残体、硅藻、生物标志化合物等指标的重建方法及研究进展;并以湖北省梁子湖一个岩芯上部21cm的沉积物为例,探讨了各种指标在重建该湖60年以来历史时期水生植被信息的优点及不足,就加强关键属种个体生态学/沉积代表性、古今生态学相结合、多指标相互验证等未来亟待加强的研究方向做一展望。