土-地铁隧道动力相互作用模型试验分析

本文对土的动力特性本构模型以及土-结构的接触面模型进行了较详细的探讨,最后分别选用非线性等价粘弹性模型和Ramberg-Osgood模型。分析表明,在进行模型试验设计时,不仅材料要满足相似性原理,而且在设计边界条件和地震波输入时也应以上述模型为参照。通过对一圆形隧道的地震反应分析,表明拱顶处的最大动应力是圆形隧道出现裂痕的主要原因,进而分析了孔隙率对结构横向变形的影响,分析结果与实际工程情况较为吻合。本文的研究成果可为地铁隧道的抗震设计提供一定的参考意见。     

Analysis of the Relationship Between the Solar X-Ray Radiation Intensity and the D-Region Electron Density Using Satellite and Ground-Based Radio Data

Increases in the X-ray radiation that is emitted during a solar X-ray flare induce significant changes in the ionospheric D region. Because of the numerous complex processes in the ionosphere and the characteristics of the radiation and plasma, the causal-consequential relationship between the X-ray radiation and ionospheric parameters is not easily determined. In addition, modeling the ionospheric D-region plasma parameters is very difficult because of the lack of data for numerous time- and space-dependent physical quantities. In this article we first give a qualitative analysis of the relationship between the electron density and the recorded solar X-ray intensity. After this, we analyze the differences in the relationships between the D-region response and various X-ray radiation properties. The quantitative study is performed for data observed on 5 May 2010 in the time period between 11:40 UT?–?12:40 UT when the GOES 14 satellite detected a considerable X-ray intensity increase. Modeling the electron density is based on characteristics of the 23.4 kHz signal emitted in Germany and recorded by the receiver in Serbia.     

Catalogue of ${>}\,55$ MeV Wide-longitude Solar Proton Events Observed by SOHO,ACE, and the STEREOs at ≈1${\approx}\,1$ AU During 2009 – 2016

Based on energetic particle observations made at \({\approx}\,1\) AU, we present a catalogue of 46 wide-longitude (\({>}\,45^{\circ}\)) solar energetic particle (SEP) events detected at multiple locations during 2009?–?2016. The particle kinetic energies of interest were chosen as \({>}\,55\) MeV for protons and 0.18?–?0.31 MeV for electrons. We make use of proton data from the Solar and Heliospheric Observatory/Energetic and Relativistic Nuclei and Electron Experiment (SOHO/ERNE) and the Solar Terrestrial Relations Observatory/High Energy Telescopes (STEREO/HET), together with electron data from the Advanced Composition Explorer/Electron, Proton, and Alpha Monitor (ACE/EPAM) and the STEREO/Solar Electron and Proton Telescopes (SEPT). We consider soft X-ray data from the Geostationary Operational Environmental Satellites (GOES) and coronal mass ejection (CME) observations made with the SOHO/Large Angle and Spectrometric Coronagraph (LASCO) and STEREO/Coronagraphs 1 and 2 (COR1, COR2) to establish the probable associations between SEP events and the related solar phenomena. Event onset times and peak intensities are determined; velocity dispersion analysis (VDA) and time-shifting analysis (TSA) are performed for protons; TSA is performed for electrons. In our event sample, there is a tendency for the highest peak intensities to occur when the observer is magnetically connected to solar regions west of the flare. Our estimates for the mean event width, derived as the standard deviation of a Gaussian curve modelling the SEP intensities (protons \({\approx}\,44^{\circ}\), electrons \({\approx}\,50^{\circ}\)), largely agree with previous results for lower-energy SEPs. SEP release times with respect to event flares, as well as the event rise times, show no simple dependence on the observer’s connection angle, suggesting that the source region extent and dominant particle acceleration and transport mechanisms are important in defining these characteristics of an event. There is no marked difference between the speed distributions of the CMEs related to wide events and the CMEs related to all near-Earth SEP events of similar energy range from the same time period.     

Terrace pediments in Makhtesh Ramon,central Negev,Israel

Terrace pediments occupy approximately 30 per cent of the bottom of the Makhtesh Ramon erosional cirque in the central Negev Desert, Israel. River terraces and terrace pediments are genetically connected landforms, where each terrace pediment corresponds with a fluvial terrace of the same relative height. A pediment and river terrace constitute a geomorphic pair and should be regarded as chronometrically synchronous morphological elements. The formation of the terrace pediment staircases is controlled mainly by local base level changes. The present‐day configuration and overall morphology of Makhtesh Ramon formed in the early stages of its development by both stream erosion and subsequent pedimentation. Less significantly, modification by intermittent erosion alternating with periods of stability, resulted in deepening of the Makhtesh Ramon bottom. The present‐day stepped relief throughout the Makhtesh valley is, thus, a composite feature. The overall rate of terrace pediment formation in Makhtesh Ramon ranges from 0·05 to 0·10 mm a⁻¹. Copyright © 2000 John Wiley & Sons, Ltd.     

地理信息图库一体更新方法

地图与DLG数据的更新方式之间既有区别又有联系,在研究DLG数据增量更新及地图与DLG数据一体化管理的基础上,提出一种地理信息图库一体更新方法,以地理实体为单位进行几何、属性和地图表达信息组织管理,获取DLG数据的增量信息并对增量信息进行地图表达得到符号图形增量信息。最后通过试验数据验证了该方法的有效性,且其具有易于计算机实现、效率高、可扩展性强、适于地图与DLG数据一体化更新等优点。     

Dissolved organic matter dynamics during the spring snowmelt at a boreal river valley mire complex in Northwest Russia

Boreal mire landscapes are rich in soil carbon and significantly contribute to the carbon input of aquatic ecosystems. They are composed of different mesoscale ecohydrological subunits, whose individual contributions to the water and carbon export of mire catchments are not well understood. The spring snowmelt period is the major hydrological event in the annual water cycle of the boreal regions and strongly influences the carbon flux between the terrestrial and aquatic systems. The aim of this study was (1) to provide a conceptual understanding of the spatial and temporal dynamics of the surface water chemistry along a swamp forest‐fen‐bog gradient during the snowmelt period, (2) to quantify the exported dissolved organic carbon (DOC) content in the runoff and (3) to identify the ecohydrological landscape unit that contributes most to DOC export during the snowmelt period in a heterogeneous mire complex in Northwest Russia. The highest DOC concentrations were detected in the swamp forest, and the lowest concentrations were observed at the treeless bog by the end of the snowmelt period (swamp forest: 37–43 mg l^?1, bog: 13–17 mg l^?1). During the spring snowmelt period, a significant amount (~1.7 g C m^?2) of DOC was transferred by the ~74 mm of runoff from the catchment into the river. Variability in the thawing periods led to differences in the relative contributions of each ecohydrological zone to the carbon export measured at a stream channel draining the studied part of the mire complex. An increased understanding of the variation in DOC concentrations and contributions from the mesoscale ecohydrological subunits to carbon export can help to predict the potential regional loss of DOC based on land cover type under climate change. Copyright © 2015 John Wiley & Sons, Ltd.     

Multi-proxy reconstruction of the Holocene vegetation and land use dynamics in the Julian Alps,north-west Slovenia

Small mountain lakes are natural archives for understanding long-term natural and anthropogenic impact on the environment. This study focused on long-term (last ca. 13 000 years) vegetation changes and sedimentary processes in the catchment area of Lake Planina pri jezeru (1430 m a.s.l.) by using mineralogical, geochemical and palynological methods. Palynological results suggest that regional vegetation between 12 900 and 11 700 cal a bp was a herbaceous–forest tundra (Pinus, Artemisia, Poaceae ). Climate warming at the beginning of the Holocene (ca. 11 700 cal a bp ) caused the transition from a wetland (Cyperaceae) to an eutrophic lake with alternating anoxic (pyrite) and oxic conditions (gypsum). In addition, the surrounding area became forested (Picea, Larix, Ulmus). Fagus expanded at 10 200 cal a bp and Abies at 8200 cal a bp. Between 7500 and 4300 cal a bp , human impact on the environment was barely noticeable and mostly limited to grazing. During 4300–430 cal a bp human impact became more evident and gradually increased. The greatest influence was observed from 430 cal a bp onwards, when excessive exploitation of the surrounding area (logging and grazing) severely eutrophicated the lake.     

Vertical Hydraulic Gradient Estimation in Clay Till,Using MiHPT Advanced Direct-Push Technology

The vertical transport of contaminants from source areas is employed in many risk assessment models and screening tools in order to estimate the contaminant mass discharge (CMD) into underlying aquifers. The key parameters for estimating CMD are the contaminant source area and concentration, and the vertical water flux, the latter of which depends on the vertical hydraulic conductivity and the vertical hydraulic gradient in the subsurface. This study focuses on advancing the use of the combined membrane interface probe hydraulic profiling tool (MiHPT) to investigate the vertical hydraulic gradient across a clay till overlying a sandy aquifer at a contaminated site in Denmark. Only the HPT is necessary for the estimate of vertical hydraulic gradient. The hydraulic head, clay till thickness, and resulting vertical hydraulic gradients found using the MiHPT compared well with observations from nearby nested wells. The parameter with the largest discrepancy was the thickness of the clay till. The advantage of the MiHPT is its relatively quick depth discrete access to information regarding subsurface permeability, vertical hydraulic gradients and contaminant distribution across a site. In this case study, performance of additional dissipationtests during the HPT log to acquire determination of the vertical hydraulic gradient increased the cost by 3% compared to standard HPT logs.     

南秦岭懒板凳岩体(西部)的年代学、地球化学及其地质意义

为查明南秦岭懒板凳岩体的成因类型和形成构造环境,探讨其地质意义,本文在岩石学研究的基础上对懒板凳岩体(西部)进行了年代学及地球化学研究。结果表明,该花岗岩形成于晚三叠世(205.6±2.4 Ma),属弱过铝质高钾钙碱性岩石;具右倾型稀土配分曲线样式,δEu=0.37～0.50;微量元素表现为Rb、Th、K等的富集和Sr、P、Ti等元素的亏损。Sr初始值较低((⁸⁷Sr/⁸⁶Sr)_i=0.70608～0.70665),ε_Nd(t)为-5.80～-4.65,二阶段模式年龄介于1365～1458 Ma之间。综合研究表明,懒板凳岩体(西部)为I型花岗岩,形成于秦岭造山带印支晚期的后碰撞环境,岩浆源区为中元古代的古老地壳物质,岩浆活动与岩体附近矽卡岩型钼矿化关系较密切。