Analysis of RC slab–beam–column sub‐assemblages subjected to bidirectional lateral cyclic loading using a new 3D macroelement

An existing two‐dimensional macroelement for reinforced concrete beam–column joints is extended to a three‐dimensional macroelement. The three‐dimensional macroelement for beam–column joints consists of six rigid interface plates and uniaxial springs for concrete, steel, and bond–slip, which model the inside of a beam–column joint. The mechanical models for the materials and the stiffness equation for the springs are also presented. To validate the model, we used test results from three slab–beam–column sub‐assemblages subjected to bi‐lateral cyclic load. It is revealed that the new joint model is capable of capturing the strength of beam–column joints and the bidirectional interaction in joint shear response, including the concentration of damage in the beam–column joint, the pinching nature in hysteretic behavior, the stiffness degradation, and strength deterioration resulting from cyclic and bidirectional loading. Copyright © 2017 John Wiley & Sons, Ltd.     

黄河流域降水稳定同位素的云下二次蒸发效应

雨滴从云底降落到地面过程的云下二次蒸发现象会影响雨滴中的同位素比率,明确降水过程中稳定同位素的变化对研究流域水循环具有重要意义。基于全球降水同位素网络（GNIP）、相关文献同位素数据以及气象数据,首先建立局地大气水线（LMWL）定性分析了黄河流域云下二次蒸发与各气象要素间的关系,其次运用改进的Stewart模型定量计算了蒸发剩余比（f）和云底降水与地面降水的D-excess之差（Δd）。结果表明：（1） 黄河流域LMWL方程为：δ²H=7.01δ¹⁸O+1.25（n=293,R²=0.92）,斜率和截距相比GMWL均较小,说明雨滴在下落过程中受到云下二次蒸发的影响。其中0～10 mm的降雨事件对云下二次蒸发影响显著;气温越高,或者水汽压、相对湿度越小,云下二次蒸发越强烈。（2） 季节变化上,从春季到冬季, f和Δd逐渐增大,云下二次蒸发逐渐减小。空间变化上,蒙甘区、蒙中区、晋陕甘区和渭河区的西安,年际间云下二次蒸发变化较大,而青南区、祁连-青海湖区、渭河区的平凉、长武、华山和鲁淮区年际差异较小。（3） 降水中Δd和f之间的线性关系在不同气象要素范围内有不同的数值,由于不同区域各气象条件存在差异,因此在应用经验公式时需考虑研究区的具体气象条件。     

基态修正时空数据模型的扩展及在土地产权产籍系统中的实现

分析了几种有代表性的时空数据模型的特点和存在的局限性，对基态修正模型进行了扩展和改进，提出了建立区段快速索引和变粒度索引因子方法，以及采用历史库，过程库和现实库对时空过程和时空关系进行描述的思路，并在开发的商业化的土地产权籍管理系统中得到实现的。     

Geomorphological characteristics of small debris flows on Junior's Kop,Marion Island,maritime sub ‐ Antarctic

The geomorphological characteristics of small debris flows in a maritime sub‐Antarctic environment are described. The morphological and sedimentological characteristics of the debris flows are comparable to debris flows documented for other parts of the world; their initiation appears closely linked to the unusual environment in which they are found. Sediment supply is generated by diurnal frost heave of loamy sediment associated with Azorella selago. The debris flows are triggered by sediment mobilization upon saturation of the frost‐heaved surface gravel and overland flow over the low‐permeability and frost‐susceptible slope materials. Morphological effects of the flows are short‐lived due to obliteration by subsequent frost heave activity. Copyright © 2000 John Wiley & Sons, Ltd.     

地学信息基础数据库系统-GIS-dB3的基本结构

本文介绍了立足于微机和超级微机上的地学信息基础数据库管理系统的基本结构。它采用通用的中西文关系数据库dBASEⅢ编译语言,统一管理地学信息的质量、数量、时间、空间以及信息传输等5个方面的特性数据,以FORTRAN和BASCI编译等系统软件进行数据处理及图形的显示和绘出,即采用各系统软件所长组成了一个地学的基础系统。该系统的空间特性数据中的\     

副高对黄渤海夏季异常海温影响的数值试验

副热带高压是黄、渤海夏季异常海温的重要成因之一。根据该海区夏季的气候特点 ,构造了一个典型的副高天气过程 ,利用“近海异常海温数值预报模式”对海表层温度进行了数值试验。对该形势下引起黄、渤海夏季异常高温的各因子进行了定量分析 ,给出了副高中心及其附近两点由各因子引起的增温率变化。试验表明 ,副热带高压控制的天气情况下 ,短波辐射对该海区夏季异常高温的形成起主要作用 ,暖水辐聚的贡献占第二位。     

贵州印江朗溪岩溶槽谷龙洞湾泉流量衰减分析

文章对贵州省印江县朗溪隔槽式向斜岩溶槽谷轴面南东侧的龙洞湾岩溶泉流量衰减规律进行了分析,通过在泉口设置复合堰、安放水文气象自动监测仪,获取了该泉降雨量和相对水位的高时间分辨率监测数据,并采用水力学公式计算了泉流量,分析了降雨过后岩溶泉流量的动态特征,再利用分区间指数函数衰减方程确定了该泉所在含水介质的结构特征及亚储水量,结果发现:（1）龙洞湾泉流量峰值滞后时间受降雨过程特征影响较大,当降雨量大或前期有降雨影响时,滞后时间短;当降雨量小或前期无降雨影响时,滞后时间长;（2）强降雨后,龙洞湾泉流量的衰减可分为三个亚动态,且衰减系数的差异较大,第I亚动态和第II亚动态的衰减系数分别是第III亚动态的11倍和3倍,这表明其三重岩溶含水介质的特征明显;（3）龙洞湾泉的含水介质具有不均匀性,以管道流和裂隙流为主,岩溶发育强烈。      

基于变形理论的花岗岩地区地铁隧道围岩等级细分研究

目前施工阶段围岩等级细分研究是围岩分级研究的一个热点, 目的是为了解决当前围岩分级跨度大不能满足实际施工需要的困境。在地铁高速建设时代为更好指导地铁隧道顺利建设, 充分考虑城市地铁隧道建设特点, 以青岛地铁建设所处的典型花岗岩地层为工程地质背景, 利用数值模拟软件FLAC3D, 通过模拟不同岩体质量的围岩在浅地层不同埋深下的地表沉降情况对围岩稳定性进行评价, 基于不同围岩的稳定性差异将Ⅲ、Ⅳ、Ⅴ级围岩对应细分为2, 3, 3个亚级。并对分级方案做进一步分析认为影响围岩分级的主要因素为岩石强度和岩体完整性, 分级时应综合考虑两大因素。其中岩石强度为主导因素, 决定了围岩等级的大致范围。软岩由于具有显著流变特性不具有自稳能力, 施工时应做完备施工支护方案。     

浅谈地籍区与地籍子区的划分

本文以南京市建邺区为实验区,以街坊界线图为底图,结合地形图、权属图等数据浅述了地籍区与地籍子区划分的流程,对其中的划分原则和具体划分步骤进行了详细的阐述。最终的地籍区与地籍子区界线成果达到了较为满意的效果。     

青藏高原大气CH_(4)源汇及其浓度时空变化特征研究进展北大核心CSCD

Methane（CH4）is regarded as the second most important greenhouse gas after carbon dioxide（CO2）. Under the warming and wetting of the climate,the Qinghai-Tibet Plateau may become a potential carbon source. To achieve the 1. 5 ℃ and 2 ℃ temperature control targets of the Paris Agreement,it is necessary to accurately estimate the remaining carbon emission space in the future. Therefore,an accurate understanding of the source and sink functions,spatial-temporal changes and mechanisms of atmospheric CH4 in the Qinghai-Tibet Plateau is of great practical significance to predict and cope with warming and help the government make scientific deci⁃ sions on energy conservation and emission reduction. This paper summarizes the existing research progress from the following three aspects：observation method of atmospheric methane,source and sink of methane,and the spatial-temporal variation of the atmospheric CH4. The results show that the observations of atmospheric CH4 on the Qinghai-Tibet Plateau are mainly ground-based observations and satellite remote sensing,lacking space-based observations,and AIRS has the best data quality among satellite products;Methane of the Qinghai-Tibet Plateau is mainly from natural sources,the main sources are wetlands,lakes and animal livestock,geological ac⁃ tivities,vegetation and permafrost are the uncertain CH4 sources. The sink of CH4 is mainly tropospheric hydrox⁃ yl radical and alpine meadow;The seasonal distribution of CH4 on the Qinghai-Tibet Plateau has a single-peak in summer,which is synchronized with the seasonal pattern of the Asian summer monsoon;The average rising rate of CH4 concentration on the Qinghai-Tibet Plateau is about 5~8 ng·g-1·a-1,which is greater than that in the sur⁃ rounding areas;The high value of CH4 concentration near the surface of Qinghai-Tibet Plateau appears in the middle part,and decreases gradually from the ground to the tropopause,but the decrease in the east and north of the plateau is greater than that in the southwest. In the future,three dimensional continuous observation of atmo⁃ spheric CH4 should be strengthened,satellite inversion algorithm and source sink analytical model should also be improved. In addition,we need to accurately quantify the spatial-temporal change process of atmospheric CH4 in the Qinghai-Tibet Plateau and reveal its change mechanism to provide a scientific basis for the future efficient emission reduction policies. © 2023 Chinese Journal of General Practitioners. All rights reserved.