oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
考虑不同库水耦合模式的拱坝振动特性分析
Dynamic Characteristic Analysis of Arch Dams with Different Forms of Reservoir Water Coupling
 [PDF]

张建伟,曹克磊,赵瑜,江琦,刘晓亮,暴振磊
- , 2016, DOI: 10.16450/j.cnki.issn.1004-6801.2016.06.023
Abstract: 为探讨不同库水模型对拱坝结构动力特性的影响,结合拉西瓦工程实例,分别建立附加质量模型与流固耦合(fluid solid interaction, 简称FSI)系统耦合模型进行动力特性分析,并将仿真结果与依据小波阈值 经验模态分解联合滤波的随机子空间(stochastic subspace identification,简称SSI)法辨识结果进行对比。结果表明:两种模型均可反映结构的振动特性,附加质量模型计算结果与辨识结果的频率误差为0.41%~7.55%;FSI系统耦合模型计算结果误差为0.09%~3.19%,且同阶次频率误差均比附加质量模型小,相邻阶次的频率间隔相对稳定,弥补了附加质量模型的模态缺失现象。FSI系统耦合模型在模拟阶数和精度方面都优于附加质量模型,能更全面、准确地反映坝体振动信息,可在拱坝结构动力特性分析中推广应用,亦可作为后续拱坝结构损伤诊断研究的基准有限元模型。
In order to study the influence of different reservoir water models on arch dam structural dynamic characteristics, an added masses model and fluid solid interaction(FSI) system model of a Laxiwa arch dam were set up. The results of finite element simulation were compared with the identification results of stochastic subspace identification (SSI) based on wavelet threshold combined with the empirical mode decomposition (EMD) filtering method. The comparison shows that the structural dynamic characteristics were reflected by both coupled models, and the frequency error margin for the added masses model calculation results to the identification results was 0.41%~7.55%, while that of the FSI system coupled model was 0.09%~3.19%. The FSI system model was superior to the added massed model with a smaller error at each frequency order. Additionally, the frequency space of contiguous order of the FSI system model was relatively stable. This study shows that the FSI system coupled model can reflect the arch dam vibration information comprehensively and accurately in terms of simulation order number and precision. The FSI system coupled model can be applied in the dynamic characteristics analysis of arch dam structure, and used as a reference of the finite element model in the research of diagnosing arch structural damage.
库水对高面板堆石坝动力反应的影响 Study of influence of reservoir water on dynamic response of high concrete face rockfill dams  [PDF]
岑威钧,张自齐,袁丽娜,陈亚南
- , 2015,
Abstract: 采用基于势流体理论的坝水流固耦合有限元分析方法,研究高面板堆石坝坝水动力耦合系统的动力反应特性,对库水模拟长度、上游坝坡坡度、两岸坡度和地震加速度等要素进行敏感性分析,探讨库水分布规律及对高面板堆石坝动力反应的影响.结果表明:由于库水的存在,坝体的自振频率有所降低;坝面动水压力中部大四周小,沿坝高大致呈抛物线分布,计算模型中"库水长度"取3倍坝高可满足精度要求;河谷几何特性对坝体动力反应有较为明显的影响;动水压力随上游坝坡坡度的减缓而变小,两岸岸坡和上游坝坡对大坝加速度反应的影响规律相似;地震峰值加速度对坝库耦合系统动力响应影响显著
Dynamics of suspended solids in Xiangxi Bay of Three Gorges Reservoir during spring algal bloom period.
三峡水库香溪河库湾春季水华期间悬浮物动态

XU Yao-yang,WANG Lan,HAN Xin-qin,CAI Qing-hua,
徐耀阳
,王岚,韩新芹,蔡庆华

应用生态学报 , 2009,
Abstract: 在三峡水库香溪河库湾春季藻类水华期间开展了水体悬浮物动态研究.调查结果表明:总悬浮物浓度的中位数是6.80 mg·L-1, 波动范围是0.66~134.92 mg·L-1,从河口到库尾入库点呈现逐渐递增的趋势;无机悬浮物空间格局与总悬浮物基本相似,而有机悬浮物空间格局与总悬浮物差异较大,与叶绿素a较为相似.回归分析表明:库湾中部水域叶绿素a与总悬浮物、有机悬浮物均有显著的线性关系,分别解释了总悬浮物、有机悬浮物总变异的66.7%~96.7% 和 58.9%~85.5%;在库湾两端(河口与库尾)叶绿素a与悬浮物参数均没有显著的线性关系.在库湾中部水域,有机悬浮物比无机悬浮物更能解释总悬浮物的变异;在库湾两端,无机悬浮物比有机悬浮物更能解释总悬浮物的变异.这意味着库湾中间水域总悬浮物的动态主要受有机悬浮物内源性生产的影响,而河口或库尾总悬浮物的动态主要受外源性的无机悬浮颗粒物输入的影响.
三峡水库支流库湾水体富营养化及水华机理研究进展 Mechanism of eutrophication and phytoplankton blooms in Three Gorges Reservoir,China:A research review  [PDF]
杨正健,俞焰,陈钊,马骏
- , 2017,
Abstract: 水体富营养化及水华问题已成为三峡水库蓄水以来最主要的水环境问题,弄清水华生消机理并提出有效防控措施已成为三峡水库运行管理的重要工作.结合国内外相关研究现状,分析了大坝建设诱导水华的主要机制,总结了三峡水库水华生消研究成果,阐述了藻类水华生消机理及影响因素.结果表明,三峡水库蓄水后支流库湾最大变化是产生了分层异重流,由分层异重流导致的水体分层是藻类水华暴发的主要诱因,"临界层理论"能够很好解释三峡水库支流库湾水华生消过程.鉴于三峡水库目前仍处于发育阶段,建议后期深入开展支流水华预测预报及其水库生态调度防控工作
Effects of Thermal Stratification on Spring Blooms in Xiangxi Bay of the Three Gorges Reservoir
水温分层对三峡水库香溪河库湾春季水华的影响

LIU Liu,LIU De-fu,XIAO Shang-bin,KONG Song,CHEN Yuan-yuan,FANG Xiao-feng,
刘流
,刘德富,肖尚斌,孔松,陈媛媛,方小凤

环境科学 , 2012,
Abstract: Frequent spring blooms have been observed in tributary bays of the Three Gorges Reservoir (TGR) since its initial filling. In order to identify the primary factor controlling spring blooms, a field monitoring plan was carried out in Xiangxi Bay, the largest tributary of TGR head area in spring 2010. The environmental factors such as water temperature, Secchi depth, underwater illumination and nutrients were monitored. The results showed that the sudden decrease of mixing depth resulting from the development of thermal stratification was the direct and primary contributor to the onset of spring blooms (Pearson correlation coefficient of the ratio of euphotic depth to mixing depth (Zeu/Zmix) and chlorophyll-a (Chl-a) is 0.934, P<0.01). The significant response of spring blooms to thermal stratification indicates that Critical Depth model can be applied to tributary bays of TGR, which will provide important references for the investigators and managers who are working on the prediction and control of algal blooms in the bays.
Spatiotemporal dynamics and related affecting factors of summer algal blooms in Xiangxi Bay of Three Gorges Reservoir.
三峡水库香溪河库湾夏季藻类水华的时空动态及其影响因素

王岚,蔡庆华,张敏,谭路,徐耀阳,孔令惠
应用生态学报 , 2009,
Abstract: 2008年6—8月,三峡水库香溪河库湾相继暴发蓝藻和绿藻水华.依据香溪河库湾夏季的每周监测,对研究区2次水华分别进行聚类和判别分析,研究了2次水华的时空动态及其影响因素.结果表明:研究区2次水华过程均可划分为无水华组、过渡组和水华组;2次水华的暴发对可溶性硅(DSi)、硝态氮与亚硝态氮(NO3--N+NO2--N)和磷酸盐(PO43--P)3种营养盐的吸收程度不同;蓝藻水华暴发期间的DSi、总氮/总磷(TN/TP)、DSi/TN和DSi/TP值均低于绿藻水华;判别蓝藻水华暴发的参数为叶绿素a(Chl a)、TN和PO43--P,而Chl a和DSi则是绿藻水华暴发的判别因子,将2次水华过程划分为水华组和无水华组的判别效果更好;判断蓝藻和绿藻水华暴发的叶绿素a临界浓度分别为40和20 μg·L-1.
Dolostone genesis of Huanglong Formation of Carboniferous in Linshui of eastern Sichuan-northern Chongqing area
川东邻水-渝北地区石炭系黄龙组白云岩成因

HU ZhongGui,ZHENG RongCai,WEN HuaGuo,CAI JiaLan,CHENG ShouChun,HU JiuZhen,LI GuiLi,
胡忠贵
,郑荣才,文华国,蔡家兰,陈守春,胡九珍,李瑰丽

岩石学报 , 2008,
Abstract: On the basis of analysing the rock structure and combined with the analysis of strontium isotopes and strontium concentration,the origin of dolomite reservoir in the Upper Carboniferous Huanglong Formation in Linshui of eastern Sichuan- northern Chongqing area is discussed and four kinds of origin types:the penecontemporaneous dolostone,the burial diagenetic dolostone,the fresh water dolomite of epidiagenesis and hydrothermal dolomite of late diagenetic stage have been recognized.The burial diagenetic dolos...
城市湖库蓝藻水华形成机理  [PDF]
王小艺,唐丽娜,刘载文,崔莉凤,许继平,赵晓平
化工学报 , 2012, DOI: 10.3969/j.issn.0438-1157.2012.05.024
Abstract: 水华防治是水环境污染治理的重点,而对水华形成机理的深入把握是解决这一问题的关键。在对城市湖库蓝藻水华形成过程深入分析的基础上,通过实验室模拟城市湖库蓝藻水华形成的整个过程,结合正交试验方法和粗糙集理论获取影响城市湖库蓝藻水华形成的关键因子——溶解氧、温度、光照、氮、磷,作为蓝藻水华形成机理建模的输入参量,以叶绿素a作为城市湖库蓝藻水华形成的表征指标,根据相互之间的作用机制构建了适合于描述城市湖库蓝藻水华形成过程的机理模型,同时通过改进的粒子群优化算法对机理模型中涉及的参数如蓝藻最大生长率、光半饱和常数、光系数、氨氮半饱和常数、溶解氧半饱和系数、蓝藻最大死亡率以及净损失率等进行非线性优化率定,提高了城市湖库蓝藻水华形成机理模型的适用性及有效性,为深入研究蓝藻水华形成机理提供一条有效途径。
东平湖沉积碳库效应与形成年代探讨
Discussion about the Effects and Forming Times of Carbon Reservoir of Lacustrine Sediments in Lake Dongping, North of China
 [PDF]

杨丽伟, 陈诗越
Advances in Geosciences (AG) , 2014, DOI: 10.12677/AG.2014.45038
Abstract:
本研究通过对山东省东平湖现生沉水植物、湖水、沉积岩芯样品的14C年代的测定,并将结果与210Pb测年结果进行对比研究,同时结合东平湖形成的历史过程与黄河洪水事件的分析,探讨了东平湖沉积物的碳库效应,初步确定了东平湖形成年代。研究表明:东平湖大致形成于公元516年前后,是黄河泛滥的产物;东平湖碳库效应随沉积层序有显著变化,其中湖泊多年平均硬水效应为484 a,沉积物碳库效应年龄一般为1000~2000 a,最高可达3700 a。这种沉积物碳库效应随沉积层序发生变化的原因与历史时期黄河泛滥、古济水、流域老碳以及人类活动等多种因素的复杂影响有关。由于东平湖沉积物碳库效应年龄随时间并非恒定,因此必须在仔细分析不同层序的沉积物的基础上,运用多种可能的方法测定沉积物年龄,并相互比较验证,以建立准确的年代框架,为该区古环境变迁信息解读提供可靠的年代基础。
We present here determine 14C ages of submerged aquatic plant (Potamogeton malaianus), lake water and sediments from Lake Dongping in Shandong province, China, comparing the result with the 210Pb dating and combining with the analysis of the formation of Lake Dongping and flood event of the Yellow River, to evaluate the reservoir age. It shows that the Lake Dongping formed in around 516 AD for the flood of the Yellow River, and reservoir effect of sediments does exist with the depth. The average annual hardwater effect age is 484 a. The reservoir ages of the lake sediments are changes between 1000 a and 2000 a, up to 3700 a. The reason for the reservoirs ages changing with the depth is related to the “old carbon” sediments carrying from the historical flood of the Yellow River, peleo-Jishui river, catchment and human activities. Due to the reservoir age of lacustrine sediments in Lake Dongping is temporally variable, it is necessary to carefully analyse the different lithologic characteristics of the sediment layers and use various possible methods to determine the age of sediments, in order to establish a precise chronological framework for a reliable age basis to interpret the paleoenvironmental changes in this area.
库水硼镁石结晶学的再研究  [PDF]
地质论评 , 1964,
Abstract: 库水硼镁石晶体的研究已由谢先德和郑绵平在地质学报第四十三卷第二期上发表了。库水硼镁石属于三斜晶系平行双面组。由于三斜晶系中无对称轴和对称面,故晶体定向的可能性较多,通常选择晶体的三个主要晶棱或晶带轴作为晶轴,其中最发育的晶带作直立的c轴。谢、郑文章中采用的库水硼镁石晶体的定向就是按照晶体的形态,即以二
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.