Additional Horizontal Traces of Ground Reflections on Ionograms from the Interkosmos-19 Satellite in the Night Trough     

Karpachev  A. T.  Zhbankov  G. A. 《Geomagnetism and Aeronomy》2020,60(1):58-62

Geomagnetism and Aeronomy - Additional horizontal traces of ground reflections were observed in a studied series of high-latitude, Kp sounding ionograms from the Interkosmos-19 satellite. The...  相似文献   

Information–Modeling Complex for Assessing the Hydroenvironmental Conditions of Reservoirs     

Motovilov  Yu. G.  Golosov  S. D.  Datsenko  Yu. S.  Zverev  I. S.  Puklakov  V. V.  Fashchevskaya  T. B. 《Water Resources》2020,47(5):751-762

Water Resources - An Information–Modeling Complex has been developed for the information support of managerial decision making in the field of rational use, protection, and restoration of...  相似文献   

Daily salinity fluctuation alleviates salt stress on seedlings of the mangrove Bruguiera gymnorhiza     

Wenqing Wang  Li Xu  Siyang You  Chao Liu  Mao Wang 《水文研究》2020,34(11):2466-2476

Salinity is a vital factor that regulates leaf photosynthesis and growth of mangroves, and it frequently undergoes large seasonal and daily fluctuations creating a range of environments – oligohaline to hyperhaline. Here, we examined the hypotheses that mangroves benefit opportunistically from low salinity resulting from daily fluctuations and as such, mangroves under daily fluctuating salinity (FS) grow better than those under constant salinity (CS) conditions. We compared growth, salt accumulation, gas exchange, and chlorophyll fluorescence of leaves of mangrove Bruguiera gymnorhiza seedlings growing in freshwater (FW), CS (15 practical salinity units, PSU), and daily FS (0–30 PSU, average of 4.8 PSU) conditions. The traits of FS-treated leaves were measured in seedlings under 15 PSU. FS-treated seedlings had greater leaf biomass than those in other treatment groups. Moreover, leaf photosynthetic rate, capacity to regulate photoelectron uptake/transfer, and leaf succulence were significantly higher in FS than in CS treatment. However, leaf water-use efficiency showed the opposite trend. In addition to higher concentrations of Na⁺ and Cl⁻, FS-treated leaves accumulated more Ca²⁺ and K⁺. We concluded that daily FS can enhance water absorption, photosynthesis, and growth of leaves, as well as alter plant biomass allocation patterns, thereby positively affecting B. gymnorhiza. Mangroves that experience daily FS may increase their adaptability by reducing salt build-up and water deficits when their roots are temporally subjected to low salinity or FW and by absorbing sufficient amounts of Na⁺ and Cl⁻ for osmotic adjustment when their roots are subsequently exposed to saline water.  相似文献   

居住迁移对居民健康的影响研究进展述评     

程晗蓓  邹游  林赛南  李志刚 《地理科学进展》2020,39(7):1210-1223

进入城市时代以来,居住环境与居民健康的联系愈发密切,尤其在“流动性"增强的大背景下,居住迁移对居民健康的影响问题受到广泛关注。论文结合知识图谱分析和文献研究法,系统评述居住迁移影响居民健康问题的最新进展。研究发现：① 近15 a来,该领域的文献数量逐年增多,关注度持续上升;文献空间分布主要集中在发达国家,但不同地区的研究内容存在显著差异。② 主要研究对象由“同质性群体”向“异质性群体”转变,从“一般性群体”向“特殊群体”转变;研究方法由数理统计向混合研究、综合应用转变。③ 研究视角经历“人口迁移—个体健康”“居住迁移—环境—个体健康”与“迁居轨迹—环境演变—个体健康发展”等3个演变阶段。④ 近期研究重点有：迁居行为与儿童健康,迁居时空特征与身心健康,住房生涯与身心健康,邻里环境、累积剥夺与健康发展等。结合以上分析,提出如下建议：注重“整合性”分析;关注城市内部迁居行为和多次迁居轨迹对居民健康的影响;扩大迁居引发的“环境”因素(如居住隔离、社会分异、职住空间错位等)研究;更多关注迁居对二代流动人口儿童健康的影响,侧重对非正规居住空间如“城中村”等的研究。  相似文献   

Proactive Management of Ecosystem Services in Oil Sands Pre-mining Phase     

Omotehinse  A. O.  De Tomi  G.  Baninla  Yvette 《Natural Resources Research》2020,29(2):949-965

Natural Resources Research - Ecosystems and their services are essential to human well-being, but mining activities often cause adverse impacts on these services. Although impact of mining...  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   

A modified numerical model for moisture-salt transport in unsaturated sandy soil under evaporation     

Wei Wen  YuanMing Lai  ZheMin You 《寒旱区科学》2020,12(3):125-133

Soil salinization, caused by salt migration and accumulation underneath the soil surface, will corrode structures. To analyze the moisture-salt migration and salt precipitation in soil under evaporation conditions, a mathematical model consisting of a series of theoretical equations is briefly presented. The filling effect of precipitated salts on tortuosity factor and evaporation rate are taken into account in relevant equations. Besides, a transition equation to link the solute transport equation before and after salt precipitation is proposed. Meanwhile, a new relative humidity equation deduced from Pitzer ions model is used to modify the vapor transport flux equation. The results show that the calculated values are in good agreement with the published experimental data, especially for the simulation of volume water content and evaporation rate of Toyoura sand, which confirm the reliability and applicability of the proposed model.  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   

The 2014 Earthquake Model of the Middle East: seismogenic sources     

Laurentiu Danciu  Karin Şeşetyan  Mine Demircioglu  Levent Gülen  Mehdi Zare  Roberto Basili  Ata Elias  Shota Adamia  Nino Tsereteli  Hilal Yalçın  Murat Utkucu  Muhammad Asif Khan  Mohammad Sayab  Khaled Hessami  Andrea N. Rovida  Massimiliano Stucchi  Jean-Pierre Burg  Arkady Karakhanian  Hektor Babayan  Mher Avanesyan  Tahir Mammadli  Mahmood Al-Qaryouti  Doğan Kalafat  Otar Varazanashvili  Mustafa Erdik  Domenico Giardini 《Bulletin of Earthquake Engineering》2018,16(8):3465-3496

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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