等离子体片离子与太阳风及地磁条件的关联研究

本文根据搭载于Cluster卫星的CIS/CODIF和RAPID仪器的观测数据,统计研究了等离子体片中的H+、O+离子在磁暴期间的时间变化特性,及其对太阳风条件的响应.观测结果表明：(1) 磁暴开始前,O+离子（0~40 keV）数密度保持在较低水平.随着磁暴的发展,O+数密度缓慢上升,其峰值出现在Dst极小值附近;H+离子(0~40 keV)数密度在磁暴开始之前的较短时间迅速增加并达到峰值,在磁暴开始之后迅速降低,并在整个主相和恢复相期间保持在相对较低水平.更高能量的离子则在磁暴开始后迅速增多,并在低能O+离子达到峰值之前达到峰值.因此我们推测磁暴初期从等离子体片注入环电流的主要是H+离子,主相后期O+离子可能扮演更为重要的角色.(2)在地磁活动时期,太阳风密度和动压强与等离子体片中的H+、O+数密度存在一定相关性.等离子体片中的H+离子对北向IMF Bz较为敏感,而IMF Bz南向条件下更有利于太阳风参数对等离子体片中O+数密度的影响.在地磁活动平静期,太阳风条件对等离子体片中的离子没有明显影响.     

煤层气地质工程一体化平台的建设构想

钻井液流变性是钻井液流动和变形的特性,对于携带与悬浮岩屑、提高钻进速度至关重要,准确掌握钻井液流变参数是保证井眼清洁与高效钻进的前提。提出一种基于卷积神经网络(Convolutional Neural Network,CNN)的钻井液流变参数智能识别方法,通过磁力搅拌产生稳定的钻井液流动图像,利用多种数据增强方法增加图像数量并建立数据库,增强模型的鲁棒性和泛化能力。优化AlexNet卷积神经网络算法,构建钻井液流变参数识别模型。将数据库划分为训练集：验证集：测试集=7：2：1,对训练集进行迭代训练并通过验证集调整参数获得最佳拟合模型。此外,运用混淆矩阵、卷积核可视化技术和类激活技术(Gradient-weighted Class Activation Mapping,Grad-CAM)对模型进行多方位评估。结果表明：(1)钻井液流变参数识别模型对钻井液塑性黏度测试的宏精确率为95.2%,宏召回率为94.7%,宏F₁值为0.95。(2)对钻井液表观黏度测试的宏精确率为91.6%,宏召回率为91.5%,宏F₁值为0.90。(3)利用卷积核可视化技术和Grad-CAM对特征提取进行可视化处理,发现钻井液波纹形状和大小会影响模型流变参数识别准确度。(4)室内测试结果表明,该模型的测试误差为±2 mPa·s,在设计允许范围以内,具有较高的识别精确度和稳定性。所提出的钻井液流变参数实时智能识别方法可为安全、快速和准确地进行钻井液流变性测试提供智能化技术思路。

     

湍流通量参数化方案的非迭代方法研究

基于Högström (1996) 和Beljaars et al.(1991) 的研究工作, 沿用Louis et al.(1982) 和Launiainen (1995) 的思路, 本文采用多元回归分析方法, 研发了一种采用非迭代方法的湍流通量参数化方案。该方案直接用整体理查森数、 空气动力学粗糙度长度和热力学粗糙度长度对稳定度参数进行参数化, 从而避免了通过循环迭代计算Monin－Obukhov长度。该方案不仅有效地节省了CPU计算时间, 而且其计算结果与迭代方案 (BHH方案) 的计算结果非常接近。     

北京城市化发展对大气边界层特性的影响

利用中国科学院大气物理研究所大气边界层物理与大气化学国家重点实验室的北京325 m气象塔1993年～2003年夏季 (7月～9月) 的观测资料, 统计分析了各年的风速与温度廓线分布特征。统计分析结果表明, 随着城市化的发展, 相对风速有逐年减小的趋势, 并且越靠近地面, 相对风速的减小越明显, 这反映了城市建筑对近地面层空气流动的摩擦作用。对风速廓线进行线性拟合得到风速随高度的垂直递增率, 发现无论是100 m以下的近地面层还是较高层, 风速的垂直递增率都随城市化发展存在逐年增大的趋势, 表明粗糙下垫面的影响已经向高层扩展。根据温度廓线计算了各年的温度垂直递减率, 发现其有增大的趋势, 这表明城市化发展对边界层热力结构同样有显著影响。本文还依据统计整理得到的近中性层结下的风速廓线资料, 利用莫宁-奥布霍夫相似理论计算了下垫面的空气动力学参数, 结果表明, 地表粗糙度、 零平面位移随着城市化发展皆有明显增加的趋势。同时, 分析了各空气动力学参数与平均风速及无量纲风速的关系。其中, 摩擦速度和平均风速二者基本成正相关, 且摩擦速度随平均风速的增大而增大的趋势越发明显。本文研究结果对研究城市化发展对区域大气边界层结构、 气候和环境影响有参考意义, 可为城市大气边界层模式和区域气候模式提供参数化依据。     

重力场中的大地奇异性问题

研究了大地奇异性对大地测量的影响及重力场在大地奇点附近的结构,揭示了奇异性的本质。     

A fast inversion method for ocean parameters based on dispersion curves with a single hydrophone

The dispersion characteristics of shallow water can be described by the dispersion curves, which contain substantial ocean parameter information. A fast ocean parameter inversion method based on dispersion curves with a single hydrophone is presented in this paper. The method is achieved through Bayesian theory. Several sets of dispersion curves extracted from measured data are used as the input function. The inversion is performed by matching a replica calculated with a dispersion formula. The bottom characteristics can be described by the bottom reflection phase shift parameter P. The propagation range and the depth can be inverted quickly when the seabed parameters are represented by on parameter P. The inversion results improve the inversion efficiency of the seabed parameters. Consequently, the inversion efficiency and accuracy are improved while the number of inversion parameters is decreased and the computational speed of replica is increased. The inversion results have lower error than the reference values, and the dispersion curves calculated with inversion parameters are also in good agreement with extracted curves from measured data; thus, the effectiveness of the inversion method is demonstrated.     

昆明盆地基底断裂地震勘探测线设计及施工参数试验分析

为了对昆明市活断层构造的深浅关系有更深入的了解,在浅层地震反射勘探的基础上,布设了一条东西向、横跨昆明盆地的中深层探测剖面KM4测线,通过对测线参数的试验与分析,确定了适合昆明盆地反射地震勘探的施工参数,采用该施工参数,开展了有效勘探深度为2～3 km的中深层反射地震勘探,确定了目标区隐伏活断层在盆地深部与盆地基底展布的异同及空间关系,探测到了昆明盆地深部断层的基本位置,确定了浅部断层与盆地基底断裂间的关系.对该测线的设计和参数采集试验分析,为城市和山区的活断层探测提供了宝贵的经验.     

水气两相流系统K-S-P模型参数反演的最优估计

应用渗流力学和参数反演辨识最优化理论,建立了水气两相流控制方程,给出了控制两相流系统K-S-P模型参数之间的本构关系,并对其中的相关参数进行数值反演辨识,得出待求参数的最优估计值。对不同质地土壤的实验测试值进行对比分析,其结果吻合较好,验证了模型的适定性和可靠性,解决了实验数据处理以及结果对初值的敏感性问题,并且该数值方法可通过多组初值参数进行数值实验,结合实验结果来满足实际工程的需求。这不仅对非饱和带内污染物传输、气藏工程试井计算、填埋气体的释放以及挥发性有机污染物的去污分析中两相流数值计算提供基础,而且对K-S-P本构关系之间参数的确定提供了可靠的理论依据。     

Using sediment rating parameters to evaluate the changes in sediment transport regimes in the middle Yellow River basin,China

This study analyses the changes in sediment transport regimes in the middle Yellow River basin (MYRB) using sediment rating parameters. Daily streamflow and suspended sediment concentration data were collected at 35 hydrological stations from the 1950s to 2016, which can be divided into three periods based on the type and intensity of human activities: the base stage before 1970, the restraining stage from 1971 to 1989, and the restoration stage after 2002. Data within each period were fitted by log‐linear sediment rating curves and the sediment rating parameters were utilized to analyse the spatial and temporal variations in sediment transport regimes. The results show that sediment rating parameters are indicative of sediment transport regimes. In the base stage and the restraining stage, the hydrological stations can be categorized into four groups based on their locations on the rating parameter plot. The stations with small drainage basins were characterized by the highest sediment transport regime, followed by those located in the coarse‐particle zone, the loess zone, and the mountainous/forest zone. In the restoration stage, the difference in sediment transport regimes between different geomorphic zones became less distinguishable than in previous stages. During the transition from the base stage to the restraining stage, sediment rating parameters showed no significant changes in sediment transport regimes in all four geomorphic groups. During the transition from the restraining stage to the restoration stage, significant changes were observed in the coarse‐particle zone and the mountain/forest zone, indicating that the revegetation programme and large reservoirs imposed a stronger influence on sediment transport regimes in these two zones than in the rest of the MYRB. This study provides theoretical support for evaluating sediment transport regimes with sediment rating parameters.     

BOOK REVIEWS

Books Reviewed in this article: Lob Trees in the Wilderness . Clifford and Isabel Ahlgren . Satellite Microwave Remote Sensing . T. D. Allan , ed. Sunbelt Cities: Politics and Growth Since World War II . Richard M. Bernard and Bradley R. Rice , eds. Legacy of Minneapolis: Preservation Amid Change . John R. Borchert , David Gebhard , David Lanegran , and Judith A. Martin . Bloomington, MN: Preparing a Historic Preservation Ordinance. Richard J. Roddewig . The Mountains of Northeastern Tasmania, A Study of Alpine Geomorphology . Nel Caine . Introductory Cartography . John Campbell . Englewood Cliffs, NJ: Changing Climate . Manual of Remote Sensing, Second Edition . 2 Vols. Robert N. Colwell , ed.-in-chief; David S. Simonett and John E. Estes , vol. eds. Remote Sensing in Meteorology, Oceanography and Hydrology . A. P. Cracknell , ed. Multidimensional Scaling . Mark L. Davison . Environmental Karst . Percy H. Dougherty , ed. The Urban Environment . Ian Douglas . Geomorphology of Europe . Clifford Embleton , ed. An Introduction to South Asia . B. H. Farmer . Great Geological Controversies . A. Hallam . Hazardous Waste Management: In Whose Backyard? Michalann Harthill , ed. Energy for Subsistence . Margaret Haswell . Perspective on Ratzel's Political Geography . James M. Hunter . Economic Deposits and their Tectonic Setting . Charles S. Hutchison . Energy Risk Assessment . Herbert Inhaber . Discovering the Vernacular Landscape . John Brinckerhoff Jackson . Climate and Energy Systems: A Review of Their Interactions . Jill Jäger . Dilemmas in Regional Policy . Antoni Kuklinski and J. G. Lambooy , eds. California Farmland: A History of Large Agricultural Landholdings . Ellen Liebman . The Spatial Organization of New Land Settlement in Latin America . Jacob O. Maos . Dark Continent: Africa as Seen by Americans . Michael McCarthy . Westport, CT: Climatology: An Introduction . John E. Oliver and John J. Hidore . Columbus, OH: The Geography of Warfare . Patrick O'Sullivan and Jesse W. Miller . The Expanding City. Essays in Honour of Professor Jean Gottmann . John Patten , ed. Scotland's Environment During the Last 30,000 Years . Robert J. Price . Integrated Urban Models . S. H. Putman . Development and the Environmental Crisis: Red or Green Alternatives? Michael Redclift .