地中海直布罗陀海峡附近内孤立波的地球物理特征          下载免费PDF全文

孙绍箐  张锟  宋海斌 《地球物理学报》2019,62(7):2622-2632

本文主要利用地震海洋学方法研究地中海直布罗陀海峡附近内孤立波的结构特征，此处内孤立波为第一模态下沉型，为中幅度和大幅度内孤立波，垂向振幅最大可达74.5 m，振幅随深度增加呈增大趋势，传播速度随振幅增大而增大，可以确定"真"最大振幅位置位于密跃层附近.由于类多普勒效应和孤立波与测量船之间存在夹角的原因，从地震剖面上得到的为视半高宽参数，需要进行校正后才能得到比较真实的半高宽参数，校正后半高宽最高可达到1721.8 m，但是校正后的半高宽与理论结果有些差距，这可能与内孤立波的发育稳定程度有关.随着内孤立波包不断向东运动，整体波宽变大，垂向速度变小.本文将地震海洋学方法拓展应用于地中海区域内孤立波分析，进一步证明了利用地震海洋学方法研究海水运动的可行性.  相似文献   

Study on multiple induced polarization parameters in groundwater exploration in Bashang poverty alleviation area of Heibei Province,China          下载免费PDF全文

LIU Zhi-yuan  TAN Ding  CHEN Zhi-bin  WEI Yun-fei  CHAI Quan  CHEN Xiao-hang 《地下水科学与工程》2020,8(3):274-280

The study examines a water exploration and poverty alleviation project in Guyuan county. The study analyzes correlations between aquifers and multiple induced polarization (IP) parameters, including resistivity, polarizability, deviation, half decay time, water-bearing factors, and Kc, a new parameter refined in this study. Based on the study, the well was placed accurately, and its maximum water inflow reached 30 m³/h. Kc value highlights the rate of change at early stages of IP secondary field. Kc value served as a quick indicator in this groundwater prospecting and is validated in practice. Progress has been made in finding new parameters in exploring water with IP method. Thanks to the project, local people have access to water and poverty alleviation has scored some achievements.  相似文献   

Study of Star/Galaxy Classification Based on the XGBoost Algorithm     

《Chinese Astronomy and Astrophysics》2019,43(4):539-548

Machine learning has achieved great success in many areas today. The lifting algorithm has a strong ability to adapt to various scenarios with a high accuracy, and has played a great role in many fields. But in astronomy, the application of lifting algorithms is still rare. In response to the low classification accuracy of the dark star/galaxy source set in the Sloan Digital Sky Survey (SDSS), a new research result of machine learning, eXtreme Gradient Boosting (XGBoost), has been introduced. The complete photometric data set is obtained from the SDSS-DR7, and divided into a bright source set and a dark source set according to the star magnitude. Firstly, the ten-fold cross-validation method is used for the bright source set and the dark source set respectively, and the XGBoost algorithm is used to establish the star/galaxy classification model. Then, the grid search and other methods are used to adjust the XGBoost parameters. Finally, based on the galaxy classification accuracy and other indicators, the classification results are analyzed, by comparing with the models of function tree (FT), Adaptive boosting (Adaboost), Random Forest (RF), Gradient Boosting Decision Tree (GBDT), Stacked Denoising AutoEncoders (SDAE), and Deep Belief Nets (DBN). The experimental results show that, the XGBoost improves the classification accuracy of galaxies in the dark source classification by nearly 10% as compared to the function tree algorithm, and improves the classification accuracy of sources with the darkest magnitudes in the dark source set by nearly 5% as compared to the function tree algorithm. Compared with other traditional machine learning algorithms and deep neural networks, the XGBoost also has different degrees of improvement.  相似文献   

Cotton canopy reflectance under variable solar zenith angles: Implications of use in evapotranspiration models     

Christopher M. U. Neale  Maria P. Gonzalez-Dugo  Angelica Serrano-Perez  Isidro Campos  Luciano Mateos 《水文研究》2021,35(6):e14162

Evapotranspiration (ET) is an important parameter in hydrologic processes and modelling. In agricultural watersheds with competing uses of fresh water including irrigated agriculture, estimating crop evapotranspiration (ET_c) accurately is critical for improving irrigation system and basin water management. The use of remote sensing-based basal crop coefficients is becoming a common method for estimating crop evapotranspiration for multiple crops over large areas. The Normalized Difference Vegetation Index (NDVI) and the Soil Adjusted Vegetation Index (SAVI), based on reflectance in the red and near-infrared bands, are commonly used for this purpose. In this paper, we examine the effects of row crop orientation and soil background darkening due to shading and soil surface wetness on these two vegetation indices through modelling, coupled with a field experiment where canopy reflectance of a cotton crop at different solar zenith angles, was measured with a portable radiometer. The results show that the NDVI is significantly more affected than the SAVI by background shading and soil surface wetness, especially in north–south oriented rows at higher latitudes and could lead to a potential overestimation of crop evapotranspiration and irrigation water demand if used for basal crop coefficient estimation. Relationships between the analysed vegetation indices and canopy biophysical parameters such as crop height, fraction of cover and leaf area index also were developed for both indices.  相似文献   

Relation of Velocity Distribution and Mass for DA White Dwarfstwo     

Xiao-bo Gong  Li-fang Li 《Chinese Astronomy and Astrophysics》2018,42(2):202-212

White dwarfs are the evolutionary endpoint of the low-and-medium mass stars. In the studies of white dwarfs, the mass of white dwarf is an important physical parameter. In this paper, we give an analysis about the velocity distribution of DA white dwarfs in the Sloan Digital Sky Survey (SDSS), and hope to find the relation between mass and velocity distribution of white dwarfs. We get the radial velocity and tangential velocity of every DA white dwarf according to their proper motion and spectral shift. Through analyzing the velocity distribution of DA white dwarfs, we find that the small-mass white dwarfs, which are produced from the single-star evolution channel, have a relatively large velocity dispersion.  相似文献   

基于计算岩石物理方法的页岩储层弹性参数提取          下载免费PDF全文

霍志周  刘喜武  刘宇巍  张剑锋  高红伟  王劲松 《地球物理学报》2018,61(7):3019-3027

发展了应用数值计算方法获取页岩储层的速度、各向异性参数的计算岩石物理系列方法.该系列方法包括了大尺度精细地质模型数值建模、计算网格尺度的地球物理建模和地震波数值模拟提取岩石物理弹性参数.本文方法利用储层的统计数据而不是具体岩心的测量数据，可获得储层岩石物理弹性参数的变化规律.相比于基于岩心测试的岩石物理方法，本文方法可精细考虑实际储层的非均匀特征，可得到岩心测试难以求取的与尺寸效应高度相关的弹性参数，也避免了求取弹性参数变化规律时获取不同地质特征岩心的困难.本文发展了计算岩石物理方法，为计算岩石物理面临的大尺度地质建模和计算能力限制问题提供了有效的解决方案.文中以胜利罗家的页岩储层为例，求得了储层TOC含量从3%到21%变化情况下储层的P波、S波速度以及各向异性参数变化规律.  相似文献   

PS测井在机场隧道地基勘查中的应用          下载免费PDF全文

范伟顺 《山东国土资源》2018,34(1)

PS测井技术是地震勘探方法之一,也是一种简便、快速、准确的原位测试技术。该文介绍了单孔法PS测井的原理及其在铁路工程勘察中的应用,主要包括根据等效剪切波,进行建筑抗震场地类别划分,铁路工程抗震场地类别划分。根据岩土动力学参数,达到评价岩体质量和划分围岩类别目的,利用剪切波速法估算岩土的承载力基本值。通过青岛机场隧道场地的工程实例说明了PS测井技术在岩土工程勘察设计中的应用情况及应用效果。  相似文献   

设计反应谱标定方法的研究现状与讨论          下载免费PDF全文

蒋晓涵  薄景山    王竞  韩昕  郭晓云  赵培培  谭启迪 《世界地震工程》2018,34(4):038-48

设计反应谱及其标定方法的研究是工程抗震研究领域的基本问题之一。在现有研究成果的基础上，归纳和总结了设计反应谱及其标定方法的研究历史和现状；评述了研究进程中的若干节点问题；介绍了设计反应谱的标定原理和当前几种有代表性的设计反应谱的标定方法；分析了设计反应谱标定参数的影响因素。在此基础上，对设计反应谱及其标定方法研究中的强震资料积累问题、谱形状问题、标定参数的确定问题以及标定方法等问题进行了讨论并提出了改进和进一步研究的建议。  相似文献   

筋土界面特性宏细观分析试验仪器研制与应用     

易富  杜常博  王政宇  于犇 《煤田地质与勘探》2020,48(1):174-182

为了更全面地分析筋土界面相互作用特性，改制了一台可视加筋土界面特性宏细观分析的试验仪器，可开展不同土工合成材料与填料的直剪和拉拔试验；该仪器改进了试验箱的尺寸，可方便两种试验的对比分析，增加了图像摄录系统，可进行试验过程的细观分析。使用新研制仪器分别进行了土工合成材料（土工格栅和土工布）加筋尾矿砂的直剪和拉拔试验，试验结果表明:两种试验条件下，土工格栅与尾矿的界面参数（似黏聚力和似摩擦角）及似摩擦系数均比土工布与尾矿的界面参数和似摩擦系数大；直剪试验下筋材网孔的有无对筋-尾矿界面参数均有较大影响，拉拔试验下筋材网孔有无对筋-尾矿界面参数似黏聚力的影响较为显著，对似摩擦角的影响较小。随着宏观变量法向应力的增加，细观参数孔隙率减小，平均接触数增加，反映在宏观上的现象就是填料颗粒被压密，筋材需要克服的阻力增大。该试验仪器能够较好地分析筋土界面宏细观特性，获得关键技术指标以用于加筋结构的设计。   相似文献   

Physico-chemical,bacteriological and health hazard effect analysis of the water in Taladanda Canal,Paradip area,Odisha, India          下载免费PDF全文

Rabiranjan Prusty  Trinath Biswal 《地下水科学与工程》2020,8(4):338-348

The physico-chemical and bacteriological parameters of the water in Taladanda canal and associated water-borne diseases,from which the dwellers have suffered,were studied,by using statistical method. Overuse and the addition of the wastes with sources from urbane industrial sectors,as well as the decrease in water level have caused the canal water quality declined drastically and subsequently led to extensive eutrophication and bacterial contamination. According to the water sample analytical results,the water is lightly acidic with the pH value of 4.5~6.7. The measured indexes,such as total dissolved solid (TDS),electrical conductivity (EC),total suspended solid (TSS),Mn,Zn,Al,Fe,Cu,Cr,and Hg etc,mostly have very high concentrations which are higher than permissible limit,indicating that the canal water is completely unsuitable for human consumption. Furthermore,the biological analysis shows that the total coliform (TC) is in the range of 45.9~30.2 in per 100 mL water in April,30.5~25.3/100 mL in July and 52.9~35.4/100 mL in December,respectively. Similarly,fecal coliform (FC) ranges from 12.8 to 10.1,10.5~7.5 and 13.1~6.4 per 100 mL water in the months of April,July and December respectively. As a result,people who use the water have suffered from different water-borne diseases. On the basis of disease data derived from hospital observations in a period of three years,there had been 4 284 people affected by different water-borne diseases from 2016 to 2018.  相似文献