青海玛多7.4级地震桥梁工程震害特性分析

2021年5月22日青海果洛州玛多县发生7.4级地震,导致了显著的桥梁结构震害。本文基于现场调查,介绍了野马滩大桥、野马滩2号桥、黑河中桥、吾儿美岗大桥和雅娘黄河桥的典型震害特征。进一步结合地震断裂与桥位关系、地震台站的地震动记录与特性分析,初步分析了各桥的地震致灾要素和结构失效机理。野马滩大桥和野马滩2号桥整体划一的落梁震害可能系近断层法向的方向性效应所致;黑河中桥的结构轻微震害应系桥台的纵向约束作用,整个桥梁的纵向地震响应类似于整体式桥;吾儿美岗大桥结构南北方向的地震响应高于东西方向,同时减隔震支座与上、下部结构的有效锚固是发挥其减震耗能功效的必要保证;雅娘黄河桥未见水平方向地震作用所导致的显著震害特征,初步推断墩底的压溃破坏可能系震中竖向地震动所致。     

格尔木地磁Z分量静日变化特征与前兆异常分析

研究了格尔木地震台1996-2006年地磁模拟资料和2008-2011年的数字化资料,通过对台站磁静日低点时间、日变幅度、日变形态的分析,确认地磁z分量磁静日低点时间在地方时12时左右;日变幅月均值呈现明显的波浪式起伏变化,其年均值与太阳黑子数保持一致;地磁日变形态较为规则,有1个低点和2个高点;在前兆异常分析中,认为低点时间异常和日变形态双低点异常与周边强震具有一定的对应关系。     

中国主要沿海城市旅游竞争力定量研究

基②国内外对城市旅游竞争力研究的回顾和梳理,建立契合本研究的指标体系：以城市旅游基础设施、发展现状和生态环境竞争力作为二级指标,以25个与城市旅游竞争力相关指标作为三级指标。在此基础上,利用主成分分析与系统聚类分析方法测算各城市因子得分及排名,并对城市间、等级间、区域间优势和劣势做出比较分析。结果表明：①上海、杭州、广州旅游竞争力相对较强,南通、中山、东莞竞争力相对较弱,其中,城市经济体规模、环境污染程度及城市绿化水平对城市旅游综合竞争力影响较突出;②城市间旅游竞争力水平梯度化明显,抱团式合作发展、阶梯状搭配发展前景看好;③同一区域内城市合作优势大②竞争优势,可建立旅游合作试点区域。     

Regional dynamics of terrestrial vegetation productivity and climate feedbacks for territory of Ukraine

Climate change has the potential to affect terrestrial ecosystems and, thereby, the carbon cycle. Various vegetation biomes are likely to respond differently to changes in climatic factors. The purpose of this study was to analyse the trends of the terrestrial vegetation productivity and climate drivers on regional levels and relations between ones. The gross primary productivity from the global satellite-based terrestrial production efficiency model (PEM) MOD17 as the vegetation productivity indicator and meteorological data from the weather station network as climatic indicators were used. The analysis covered a period from 2000 to 2012. Correlation analysis was used to quantify the association between the vegetation productivity and climatic indicators for different growing seasons and landscape-climatic zones of Ukraine. The Mann–Kendall trend test was applied to take into account seasonal features. Multiple linear regression models for corresponding seasons and zones have been simulated using the principal component analysis. The results showed no detectable limiting effect of the climatic drivers on plant productivity for forest areas. The limiting effect of the temperature increasing and precipitation amount decreasing for the steppe zone and eastern forest-steppe subzone of Ukraine for summer was observed.     

Application of Principal Component Analysis and Spectral Angle Mapper in the Mapping of Hydrothermal Alteration in the Jebal–Barez Area,Southeastern Iran

The southeastern part of the central Iranian Cenozoic magmatic belt contains many areas with copper mineralization. In an analysis of this region, we used the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Enhanced Thematic Mapper plus (ETM⁺) images to map the distribution of hydrothermally altered rocks, based on their mineral assemblages. The spectral measurements, based on the field samples and satellite‐image‐derived spectra, show dominantly Al–OH (sericite and clays) and Fe–O absorption features in the visible–near infrared to shortwave infrared regions of the spectrum. Silica–bearing rocks, as well as silicic alteration, show an intense Si–O vibrational feature in the thermal infrared wavelength region. We analyzed ASTER/ETM⁺ images, performed a directed principal component analysis, and used spectral angle mapper to map areas of hydrothermal alteration and iron oxide/hydroxide minerals. The individual principal component images compiled by directed principal component analysis reveal the distribution of individual alteration minerals such as sericite, kaolinite, chlorite, epidote, and quartz. The best results, in terms of mapping the distribution of alteration, were obtained using the spectral angle mapper method. The altered areas were then sampled and the samples subjected to X–ray diffraction analysis, spectral analysis, and thin sections were observed under a microscope. Field observations reveal that more than 98% of the known copper mineralization occurs within the interpreted alteration areas. The present results indicate the great potential of ASTER and ETM⁺ data for mapping the distribution of alteration and exploring for copper mineralization in areas with a similar climate and geological setting to those of the present study.     

西藏冈底斯地区斑岩铜矿识别的最佳多光谱遥感异常判据研究

文章应用多光谱遥感技术,对冈底斯斑岩铜矿带的实例(驱龙、甲玛、朱诺、冲江、夏玛日等矿床)进行了研究和总结,包括ASTER和ETM+数据技术特征、蚀变异常找矿的地质依据、蚀变异常提取的波谱前提、多光谱矿致遥感异常提取的常见技术方法、去干扰异常主分量门限化技术流程、冈底斯斑岩铜矿带找矿模型最佳遥感异常判据研究等.确定了ASTER主分量分析提取的羟基异常OHA6、OHA5同心套合异常可做为斑岩铜矿的最佳多光谱遥感异常判据,在从夏玛日至朱诺的13景共46万平方公里的ASTER提取异常中,依此判据圈定了冈底斯20处有潜能的斑岩铜矿异常.此外,还对夏玛日景遥感异常进行了解译,并提出了3处钻孔孔位建议.     

基于经验模态分解法与小波变换的长周期大地电磁信号去噪方法

针对大地电磁信号具有非线性、非平稳和非最小相位的特点,提出了一种基于经验模态分解法结合小波变换的联合信号去噪方式,将时间序列信号通过经验模态分解,利用连续均方误差准则确定原始信号能量转折点,进而再使用小波阈值去噪法对剩余固有模态函数分量进行去噪,最后重构出消噪信号。通过对实测信号处理前后结果的对比,表明了本方法能够有效地应用于信号时域去噪。     

黑龙江东宁金厂金矿土壤离子电导率异常特征、离子成份及找矿预测

为了解黑龙江东宁金厂金矿体土壤离子的电导率异常特征,查明金矿体中土壤离子电导率成分的离子组成以及不同种类离子的含量变化关系对电导率的贡献大小,初步探讨矿区土壤离子电导率异常的形成机理,本文对金厂金矿开展了土壤离子电导率测量,取得以下认识:(1)发现多个具有成矿远景的离子电导率异常区,经深部工程验证具有隐伏的金矿体;(2)组成土壤离子电导率异常的离子成分主要是HCO-3、SO2-4、Ca2+、Cl-、K+、Na+、F-、Mg2+、Mn2+等一套水可溶性离子,经过相关分析得出金矿电导率异常与各离子的相关系数为HCO-3>Ca2+>SO2-4>Cl->K+>Na+>F->Mg2+>Mn2+。     

基于含可变因子S变换的面波压制技术

在原始的地震记录中,压制面波可以提高地震信噪比.在S变换和广义S变换的基础上,提出了含可变因子的S变换,利用这种方法压制地震记录中的面波成份.首先将地震记录通过含可变因子的S变换变换到时频域,在时频域中压制面波的成份,再变换回时间域,其结果就是滤掉面波的地震信号.针对这一方法,提出了实施流程,并将其应用于实际资料中.其应用效果表明,该方法能有效地压制面波,并保留了地震记录的反射波记录,具有适应性强,效果好等特点.