Geochemical evidence of ions’ sources and influences of meteorological factors on hydrochemistry of glacier snow meltwater in the source region of the Yangtze River

The risk management of cascade reservoir systems (CRSs) is a major public challenge, and the establishment of risk criteria is critical to solving this iss     

UAV survey and numerical modeling of loess landslides: an example from Zaoling,southern Shanxi Province,China

Natural Hazards - This work attempted to reveal the geometric and kinematic characteristics of a loess landslide that occurred at Zaoling, southern Shanxi Province, China, on March 15, 2019. Based...     

Estimated mass and stiffness matrices of shear building from modal test data

A method that estimates mass and stiffness matrices of shear building from modal test data is presented in this paper. The method depends on only measurable points that are less in number than the total structural degrees of freedom, and on the first two orders of structural mode measured. So it is applicable to most of the general test. Based on this method modal data of unmeasurable points are estimated, then global mass and stiffness matrices of structure are obtained by using the first two orders of modal data. Taking advantage of iteration the optimum global mass and stiffness matrices are gained. Finally, an example is studied in this paper. Its result shows that this method is reliable. © 1998 John Wiley & Sons, Ltd.     

与时俱进勇于创新积极稳妥地推进土地登记代理工作

土地登记代理是土地市场中介服务内容的一部分,是土地市场发展的产物。土地登记政策性强,法定程序严密,权利人自己办理,往往因不了解相关政策法规和缺乏经验而大费周折,也给土地登记部门增加了压力和行政成本。再基于土地使用权变更频繁的新形势,土地登记代理应运而生。淄博市与时俱进,勇于创新,积极稳妥地推进土地登记代理工作,促进了土地市场的健康发展。     

2019年6月17日长宁MS6.0地震前地震活动和水位的加卸载响应比异常研究

加卸载响应比（LURR）方法是通过固体潮加卸载过程中的某一物理参数的响应差异探查区域应力场演化。本文将这一方法应用于2019年6月17日四川长宁M_S6.0地震,根据LURR时序演化探查震源区介质的应力状态变化,提取可能的震前异常信息。首先采用贝尼奥夫应变作为响应量计算LURR,通过固体潮在地震断层面的最优滑动方向上引起的库仑破坏应力变化来判断加载还是卸载,结果显示LURR值自2018年年初开始快速增加并在2018年年中达到峰值,此后异常持续至地震。在此基础上对该地区的大地形变和地下井水位资料进行了LURR分析,发现水富水平摆倾斜仪的东西和南北分量在LURR出现异常的同期发生明显偏转,而地震周边的地下井水位高值变化过程与长宁地震也有较好的对应关系。研究表明在长宁地震发生前,存在地震活动和地下水位的LURR异常,且异常时间与水富倾斜同步,暗示震源区介质存在明显的应力积累过程。     

太湖水体和沉积物细菌群落分布格局及其驱动因素

水体和沉积物是湖泊生态系统中迥异但又紧密相连的两类生境,栖息在这两类生境中的细菌在维持生态系统平衡和驱动元素循环中起着关键性作用。为了探究湖泊水体和沉积物细菌群落的分布格局,本文对太湖四个湖区水体和沉积物中细菌群落进行调查,基于高通量测序技术和统计分析手段,分析这两类生境中的细菌群落组成和多样性水平、分布特征及其驱动因素。结果表明:放线菌门(Actinobacteria)、变形菌门(Proteobacteria)和蓝细菌门(Cyanobacteria)是水体细菌群落中最主要的细菌门,而沉积物中Proteobacteria占据优势地位。在两类生境中,太湖西部区域细菌群落丰富度和独特性(LCBD)相对较高,各区域群落结构表现出显著性差异。对水体而言,电导率、pH值、PC1(重金属组成)和沉积物孔隙度是驱动细菌丰富度的重要因子,PC1、水温及pH值是影响细菌群落LCBD的重要因子,而细菌网络复杂性随pH值的增加而增加,且在高pH环境中占主导地位;对沉积物而言,其丰富度和LCBD的重要影响因子均是沉积物中总磷和锂,细菌网络复杂性随金属元素施加的环境压力增大而降低,但随总磷、磷酸盐和铵态氮浓度的...     

青藏高原东南缘高山湖泊藻类响应气候变化和大气沉降的长期特征

高山湖泊远离人类活动直接影响,通常具有面积小、寡营养、食物网单一等特点,对气候变化和营养输入具有较高的敏感性。我国青藏高原东南缘地区氮沉降通量较高、增温幅度显著,已有研究显示该地区可能受湖泊类型、流域特征等影响存在差异性的湖泊响应模式。本研究选择该区域位于树线以下、具有不同水深的3个小型湖泊(盖公错纳、沃迪错、碧沽天池)开展沉积物调查和对比研究,通过钻孔样品测年、理化特征和藻类(硅藻群落、藻类色素)等多指标分析,结合区域气候定量重建和氮沉降等数据收集,评价了过去300年来藻类演替模式的异同特征及湖泊水深的调节作用。结果显示,3个湖泊中硅藻的优势物种与群落组成差异明显。深水型湖泊盖公错纳(最大水深39.4 m)的硅藻群落以浮游种为主(占比达82%),优势种为眼斑小环藻(Pantocsekiolla ocellata)、科曼小环藻(Pantocsekiella comensis);深水型湖泊沃迪错(最大水深20.7 m)的硅藻群落中浮游种和底栖种约各占50%,优势种为眼斑小环藻(Pantocsekiella ocellata)、连结脆杆藻(Saurosira construens);浅水湖...     

低周反复荷载下Q460钢材框架柱抗震性能分析

为了进一步完善Q460钢材在抗震设计规范中相关限值的要求,本文利用有限元软件ABAQUS,以轴压比、翼缘宽厚比、腹板高厚比和壁板宽厚比为变量,建立了共48根“工”字型框架柱和“箱”型框架柱,分析了其抗震性能。结果表明:翼缘宽厚比对框架柱的能量耗散系数影响较小;能量耗散系数随轴压比、腹板高厚比（“工”字型）和壁板宽厚比（“箱”型）增大而明显减小;框架柱的极限承载力随轴压比的减小及壁板宽厚比和翼缘宽厚比的增大而逐渐增大,当腹板高厚比接近规范限值时,承载力下降趋势明显增大。与采用Q235钢材的框架柱相比,Q460钢材框架柱的延性较小,仅为2左右;当采用Q460钢材时,“工”字型框架柱的极限位移角限值建议取为0.03,“箱”型框架柱的极限位移角限值建议取为0.032。规范中对翼缘宽厚比限值的规定偏于保守,其值最大可取至9。无论是“工”字型框架柱还是“箱”型框架柱,其腹板高厚比均不宜过大。Q460钢材框架柱的刚度退化率随轴压比的增大而增强,且翼缘宽厚比越大,腹板高厚比越小,柱的初始刚度越大,刚度退化程度越明显。     

Experimental seismic behavior of squat shear walls with precast concrete hollow moulds

This study proposes an innovative precast shear wall system, called an EVE precast hollow shear wall structure (EVE-PHSW). Precast panels in EVE-PHSW are simultaneously precast with vertical and horizontal holes. Noncontact lap splices of rebars are used in vertical joints connecting adjacent precast panels for automated prefabrication and easy in situ erection. The seismic behavior of EVE walls was examined through a series of tests on six wall specimens with aspect ratios of 1.0∼1.3. Test results showed that EVE wall specimens with inside cast-in situ concrete achieved the desired “strong bending and weak shear” and failed in shear mode. Common main diagonal cracks and brittle shear failure in squat cast-in situ walls were prevented. Inside cast-in situ concrete could significantly improve the shear strength and stiffness of EVE walls. The details of boundary elements (cast-in situ or prefabricated) and vertical joints (contiguous or spaced) had little effect on the global behavior of EVE walls. Noncontact lap splices in vertical joints could enable EVE walls to exhibit stable load-carrying capacity through extensive deformations. Evaluation on design codes revealed that both JGJ 3-2010 and ACI 318-14 provide conservative estimation of shear strength of EVE walls, and EVE walls achieved shear strength reserves comparative to cast-in situ walls. The recommended effective stiffness for cast-in situ walls in ASCE 41–17 appeared to be appropriate for EVE walls.