Electron Energy Spectra and e–e Bremsstrahlung from Anisotropic Electron Distributions in Extreme Solar Flares     

Oparin  I. D.  Charikov  Yu. E.  Ovchinnikova  E. P.  Shabalin  A. N. 《Geomagnetism and Aeronomy》2020,60(7):889-895

Geomagnetism and Aeronomy - We study the electron energy spectra of two powerful solar flares SOL2003-10-28T 1106:16 (GOES class X17.2) and SOL2002-07-23T 0018:16 (X4.8) analyzing the HXR and...  相似文献   

Evaluating the Diffuse Runoff from Urban Territories in the Volga Basin: Case Study of Rostov City     

Bolgov  M. V.  Zav’yalova  E. V.  Zaitseva  A. V.  Osipova  N. V. 《Water Resources》2020,47(5):673-681

Water Resources - The study is focused on examining and simulating the formation processes of the runoff and pollution export in the case of Rostov (Rostov Velikii), a town in the Volga basin. The...  相似文献   

结合变差纹理特征的极化SAR建筑物震害信息提取          下载免费PDF全文

肖修来  翟玮  郭晓  张皓然 《地震工程学报》2020,42(2):568-578

快速评估建筑物地震灾害信息对地震应急救援工作有着指导意义,而极化SAR具有全天候、全天时的特点,因此利用极化SAR图像提取震害信息已逐渐成为研究热点。虽然极化SAR具有丰富的极化信息,但其纹理信息不可忽略,尤其是完好的人工建筑物在图像上呈现规则的纹理特征,而倒塌建筑区域纹理分布杂乱,因此结合纹理信息也可以很好地提取建筑物信息。以2010年玉树地区的全极化SAR数据为研究对象,首先,利用Yamaguchi分解的体散射分量PV提取了SAR图像中的建筑物区域以及道路、水系等非建筑物信息,在此基础上,对相干散射矩阵T11分量中倒塌建筑物、完好建筑区域进行变差计算,根据变差曲线确定变程a后,再对建筑物区域采取窗口m*m(m=3*a)进行变差计算得到变差纹理信息,最后利用FCM算法对变差纹理信息分别提取完好建筑物和倒塌建筑物区域,为了对比分析,文章利用Yamaguchi分解的二次散射分量PD提取完好建筑物区域,与震后光学遥感图像对应样本点进行人工验证,得到完好建筑物的提取精度为80.18%,倒塌建筑物的提取精度为84.54%,道路水系的提取精度为77.58%。  相似文献   

Evaluation of Interactions Between Oilfield Chemicals and Reservoir Rocks     

Wuyep  E. O.  Oluyemi  G. F.  Yates  K.  Akisanya  A. R. 《Natural Resources Research》2020,29(2):1239-1258

Natural Resources Research - Sand failure and production occurs when the formation stress exceeds the strength of the formation, which is derived majorly from the natural material that cements the...  相似文献   

Structure-specific selection of earthquake ground motions for the reliable design and assessment of structures   总被引：1，自引：1，他引：0  

E. I. Katsanos  A. G. Sextos 《Bulletin of Earthquake Engineering》2018,16(2):583-611

A decision support process is presented to accommodate selecting and scaling of earthquake motions as required for the time domain analysis of structures. Code-compatible suites of seismic motions are provided being, at the same time, prequalified through a multi-criterion approach to induce response parameters with reduced variability. The latter is imperative to increase the reliability of the average response values, normally required for the code-prescribed design verification of structures. Structural attributes like the dynamic characteristics as well as criteria related to variability of seismic motions and their compliance with a target spectrum are quantified through a newly introduced index, δ _sv–sc , which aims to prioritize motions suites for response history analysis. To demonstrate the applicability of the procedure presented, the structural model of a multi-story building was subjected to numerous suites of motions that were highly ranked according to both the proposed approach (δ _sv–sc ) and the conventional one (δ _conv ), that is commonly used for earthquake records selection and scaling. The findings from numerous linear response history analyses reveal the superiority of the proposed multi-criterion approach, as it extensively reduces the intra-suite structural response variability and consequently, increases the reliability of the design values. The relation between the target reliability in assessing structural response and the size of the suite of motions selected was also investigated, further demonstrating the efficiency of the proposed selection procedure to achieve higher response reliability levels with smaller samples of ground motion.  相似文献   

Quantification of the amplitude variability of the ground motion in Argostoli,Greece. Variability of linear and non-linear structural response of a single degree of freedom system.     

E. Koufoudi  C. Cornou  S. Grange  F. Dufour  A. Imtiaz 《Bulletin of Earthquake Engineering》2018,16(9):3675-3685

The term “spatial variability of seismic ground motions” denotes the differences in the amplitude and phase content of seismic motions. The effect of such spatial variability on the structural response is still an open issue. In-situ experiments may be helpful in order to answer the questions regarding both the quantification of the spatial variability of the ground motion within the dimensions of a structure as well as the effect on its dynamic response. The goal of the present study is to quantify the variability of the seismic ground motion accelerations in the shallow sedimentary basin of Argostoli, Greece, and thereafter to identify its effect on the linear and non-linear elasto-plastic response of a single degree of freedom system in terms of spectral displacements. Around 400 earthquakes are used, recorded by the 21-element very dense seismological array deployed in Argostoli with inter-station spacing ranging from 5 to 160 meters. The seismic motion variability, evaluated in terms of spectral accelerations, is found to be significant and to increase with inter-station distance and frequency. Thereafter, the amplitude variability in terms of spectral displacements, which is indeed the linear response of a single degree of freedom (SDOF) system with various fundamental periods, is compared with the amplitude variability of a SDOF with non-linear elasto-plastic response. The variability of the maximum top displacement of the linear single degree of freedom system is estimated to be on average 12% with larger variabilities to be observed within two narrow frequency ranges (between 1.5 and 1.7 Hz and between 3 and 4 Hz). Such high variabilities are caused by locally edge-generated diffracted surface waves. The non-linear perfectly elasto-platic structural response of the SDOF system shows that although the variability has the same trends as in the case of linear response, it is almost constantly increased by 5%.  相似文献   

Cyclic testing of a full-scale two-storey reinforced precast concrete wall-slab-wall structure     

E. Brunesi  S. Peloso  R. Pinho  R. Nascimbene 《Bulletin of Earthquake Engineering》2018,16(11):5309-5339

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High‐temperature gold‐copper extraction with chloride flux in lava tubes of Tolbachik volcano (Kamchatka)     

Vadim S. Kamenetsky  Alexander Belousov  Victor V. Sharygin  Liudmila M. Zhitova  Kathy Ehrig  Michael E. Zelenski  Ilya Chaplygin  Marina A. Yudovskaya  Pavel N. Nesterenko  Sergey M. Zakharov 《地学学报》2019,31(6):511-517

Subvolcanic environments in supra‐subduction zones are renowned for hosting epithermal deposits that often contain electrum and native gold, including bonanza examples. This study examined mineral assemblages and processes occurring in shallow‐crust volcanic settings using recent eruption (2012–2013) of the basaltic Tolbachik volcano in the Kamchatka arc. The Tolbachik eruptive system is characterized by an extensive system of lava tubes. After cessation of magma input, the tubes maintained the flow of hot oxidized gases that episodically interacted with the lava surfaces and sulphate‐chloride precipitates from volcanic gases on these surfaces. The gas‐rock interaction had strong pyrometamorphic effects that resulted in the formation of molten salt, oxidized (tenorite, hematite, Cu‐rich magnesioferrite) and skarn‐like silicate mineral assemblages. By analogy with experimental studies, we propose that a combination of these processes was responsible for extraction of metals from the basaltic wall rocks and deposition of Cu‐, Fe‐ and Cu‐Fe‐oxides and native gold.  相似文献   

Propagation of Elastic Compressional Waves in a Porous-Fractured Medium Saturated with Immiscible Fluids     

Markov  M. G.  Markova  I. A.  Jarillo  G. F. Ronquillo  Pervago  E. V. 《Izvestiya Physics of the Solid Earth》2020,56(3):357-363

Izvestiya, Physics of the Solid Earth - The problem of calculating the reflection and transmission coefficients of elastic P-wave incident from a porous half-space onto a fluid-filled crack is...  相似文献   

Zooplankton Size Structure in the Kolsay Mountain Lakes (Kungei Alatau,Southeastern Kazakhstan) and Its Relationships with Environmental Factors     

Krupa  E. G.  Barinova  S. S.  Romanova  S. M. 《Water Resources》2019,46(3):403-414

Water Resources - The size structure of zooplankton in Kolsay Lakes was characterized with the use of the values of Clarke W-statistic, ?-Shannon–Weaver, and the average individual mass...  相似文献