The Seismic Shear Demand in Ductile Cantilever Wall Systems and the EC8 Provisions     

A. Rutenberg  E. Nsieri 《Bulletin of Earthquake Engineering》2006,4(1):1-21

The seismic shear provisions of EC8 for ductile reinforced concrete walls, serving as the lateral load resisting system in multistorey building structures are re-examined. Two aspects are considered (1) single walls, or a system comprising a number of equal-length walls, (2) a resisting system comprising walls of different lengths. It is demonstrated, in light of recent parametric studies, that the EC8 provisions for walls in the medium- and high-ductility classes (DC-M and DC-H, respectively) are both in need of revision. Possible revisions of requirements and a design procedure for a wall system are presented.  相似文献   

太原冬季PM_2.5中有机碳和元素碳的变化特征   总被引：4，自引：2，他引：4       下载免费PDF全文

孟昭阳张怀德  蒋晓明颜鹏　王雁林伟立  张养梅王淑凤 《应用气象学报》2007,18(4):524-531

2005年12月—2006年2月在太原市区持续观测了气溶胶细粒子PM_2.5, 并应用Sunset碳分析仪进行了有机碳 (organic carbon, OC) 和元素碳 (elemental carbon, EC) 的测定。结果表明:太原冬季PM_2.5, OC和EC浓度均较高, 其中PM_2.5日平均浓度变化范围为25.4~419.0 μg/m3, 日平均浓度为193.4±102.3 μg/m3, OC平均浓度为28.9±14.8 μg/m3, EC平均浓度为4.8±2.2 μg/m3, OC/EC平均比值是7.0±3.9, 即太原市冬季PM_2.5和碳气溶胶污染严重。OC在PM _2.5中占18.6%, EC占2.9%, 这表明碳气溶胶是太原大气细粒子污染控制的关键组分。在太原市冬季, 采暖燃烧的煤是OC和EC的主要贡献源, 造成OC大大高于EC, 从而使OC/EC比值增大。各种气象条件对PM_2.5, OC, EC和OC/EC比值的变化都有不同程度的影响, 特别是大雾天气、相对湿度、风速和降雪是影响碳气溶胶浓度变化的重要因素。  相似文献   

基于球谐函数区域电离层模型建立   总被引：1，自引：0，他引：1  

陈尚登  岳东杰  李亚 《测绘工程》2015,(11):28-32

利用GPS双频观测数据建立高精度、准实时的区域电离层总电子含量(TEC)模型是电离层研究的一个重要手段。文中探讨IGS观测站数据结合4阶球谐函数建立区域电离层格网模型的方法,并对硬件延迟(DCB)和TEC建模结果的可靠性进行分析,结果表明,DCB解算精度在0.4ns以内,TEC内外精度优于1.4TECU(1TECU=1016电子数/m2)和1.5TECU,满足导航定位中电离层改正的需要。  相似文献   

多环芳烃对海洋浮游植物的生物毒性研究   总被引：19，自引：0，他引：19  

江玉  吴志宏  韩秀荣  张蕾  王修林 《海洋科学》2002,26(1):46-50

采用静态实验方法研究了4种（多环）芳烃对6种海洋浮游植物的生物急性毒性效应,并应用对数模型计算了其EC～（50）值。结果表明,根据对数模型计算的EC～（50）值与定义作图法所得结果较为一致,但在低浓度PAHs对浮游植物有促进作用时,其具有准确和合理的优点。其中甲苯、萘、2-甲基萘、菲的72h-EC～（50）分别为34.1～114mg/L,3.9～7.3mg/L,169～3.03mg/L,0.6～1.92mg/L。4种芳烃对6种浮游植物的生物急性毒性顺序为:小新月菱形藻>甲藻>三角褐指藻>中肋骨条藻>小球藻>亚心形扁藻。此外,4种芳烃的72h-EC～（50）与其相应的Kow值有较好的log-log相关性。  相似文献   

神经智能信息处理系统的研究现状及其在水文水资源中的应用展望   总被引：10，自引：1，他引：9       下载免费PDF全文

张翔  丁晶 《水科学进展》2000,11(1):105-110

从神经网络(NN),模糊系统(FS)和进化算法(EC)三者相结合的角度,介绍了神经智能信息处理系统的研究现状,讨论了该系统在水文水资源中的应用,并对其应用发展趋势进行了预测。  相似文献   

Integrative assessment of organotin contamination in a southern European estuarine system (Ria de Aveiro, NW Portugal): tracking temporal trends in order to evaluate the effectiveness of the EU ban   总被引：1，自引：0，他引：1  

Sousa A  Matsudaira C  Takahashi S  Tanabe S  Barroso C 《Marine pollution bulletin》2007,54(10):1645-1653

Organotin (OT) compounds have been used as biocide agents in antifouling paints since the mid 1960s and are now ubiquitous in the marine environment. Due to their high toxicity to non-target species they were banned from antifouling paints in the European Union in 2003 (2002/62/EC directive). The aim of the present work is to assess any obvious decline of the OT environmental levels at Ria de Aveiro (NW Portugal) after the ban. The organotins - monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPT), diphenyltin (DPT), triphenyltin (TPT), monoctyltin (MOT), dioctyltin (DOT) and trioctyltin (TOT) - were quantified in the gastropod Nassarius reticulatus, in the mussel Mytilus galloprovincialis and in sediments. Imposex (imposition of male characters on females of gonochorist gastropods) in N. reticulatus was additionally used as a biomarker of TBT pollution. Time comparisons show a slight decrease of imposex between 2003 and 2005 probably as a consequence of the EU ban, though in some cases this trend seems to have started earlier since 2000. The fraction of TBT relatively to its metabolites has been decreasing over the last years but still remains high suggesting that there are still recent inputs of this compound into the study area.  相似文献   

A source study of PM in Saxony by Size-Segregated Characterisation     

H.?HerrmannEmail author  E.?Brüggemann  U.?Franck  T.?Gnauk  G.?L?schau  K.?Müller  A.?Plewka  G.?Spindler 《Journal of Atmospheric Chemistry》2006,55(2):103-130

Airborne particulate matter in Saxony (Germany) was investigated at three different sites (central urban, urban outskirts, rural) during a winter (1999/2000) and a summer (2000) campaign. PM was collected simultaneously at all three sites using five-stage Berner impactors. Besides size-segregated chemical particle characterisation and mass closure source apportionment of the particle components, especially of the carbonaceous fraction was an aim of the study. Source apportionment was performed exclusively on the basis of experimental data without support of models considering a set of basic assumptions and logical deductions. The derived simple equations permit to differentiate the carbonaceous fraction in traffic, domestic heating (winter) and biogenic (summer) contributions.The total carbon (TC) in the smallest particle size range (Dp_aer = 0.05-0.14μm) at the urban site, contributing 88% to the mass in that class, was completely attributed to traffic emissions. For the particle size range Dp_aer = 0.42-1.2 μm (50-60% of the total mass) TC was attributed to traffic (67%) and domestic heating (33%) in winter and to traffic (82%) and biogenic origin (18%) in summer.Size-segregated determination of alkanes revealed that these compounds were mainly of biogenic origin in summer and of anthropogenic origin in winter considering the carbon preference index (CPI_odd). Particulate PAHs found in winter samples originated mainly from domestic heating and not from traffic emissions.The method described cannot provide complete results, but the demonstrated source apportionment can be helpful to assess a given situation with regard to possible steps against the exceeding of the EU limit of the PM₁₀ mass concentration of 50 μg m⁻³.  相似文献   

埃玛图状态曲线和几个特殊指标的其他算法     

刘继东  郭玉凤  任楠  王卫国 《内蒙古气象》2011,(6):33-34,81

文章阐述了另外一种温度对数压力图(Emagram)制作方法,根据该方法对状态曲线以及对流有效位能(CAPE)、对流抑制能量(CIN)、自由对流高度(LFC)和平衡高度(EC)进行了计算。  相似文献   

沉积物粘土混浊水电导率与pH值相关性研究——以渤海湾西岸平原XZ、MD钻孔为例     

刘翀  方晶  王福  齐乌云  黎伟麒  刘志鹏 《第四纪研究》2015,35(2)

对渤海湾西岸平原XZ、MD钻孔样品的粘土混浊水电导率(以下简称EC)和pH测定值进行相关分析,结果显示EC与pH都呈高度负相关,两孔的相关系数分别为-0.830(P＜0.01)和-0.765(P＜0.01).整体上EC与pH呈反比特征.进一步根据EC测定值将两钻孔沉积物分为海相、海陆过渡相和陆相分带,并对各分带中的EC和pH作相关性分析,结果表明除XZ孔海相沉积带(Ⅰ带)相关性偏低(r=0.089,P＞ 0.05)外,其他各沉积带均显示较明显的负相关.但负相关性也有所不同,XZ孔海陆过渡相沉积带(Ⅱ带,r=-0.740,P＜0.01)负相关性最为明显;MD孔海陆过渡相沉积带(Ⅰ带,r=-0.434,P＜0.01)、XZ孔陆相沉积带(Ⅲ带,r=-0.403,P＜0.05)和MD孔陆相沉积带(Ⅱ带,r=-0.482,P＜0.05)也有较明显的负相关性.这表明沉积物EC与pH相关程度的差异,亦可在一定程度上反映出其沉积环境的不同.  相似文献   

WRF、EC和T639模式在福建沿海冬半年大风预报中的检验与应用     

曾瑾瑜  韩美  吴幸毓  林青  廖廓 《海洋科学》2015,39(7):75-85

基于福建省冬半年沿海和港湾岛屿自动站的逐时极大风观测资料和WRF(Weather Research and Forecast)、EC(European Centre for Medium-Range Weather Forecasts)细网格以及T639(TL639L60)三种模式预报的10 m 风场资料, 将模式预报的风向风速与观测资料进行对比检验, 结果表明: 福建省沿海冬半年大风的盛行风向以东北风为主, 大风的时空分布极为不均, 沿海风力的脉动性、跳跃性、局地性突出。从三种模式对风速风向的模拟效果来看, WRF 和EC 细网格的预报效果较好, 有可参考性, T639可参考性不高。对于风速, 模式预报结果相比实况极大风速偏小, 港湾岛屿代表站风速的平均绝对误差均小于沿海代表站, 预报平均误差由沿海向内陆逐渐减小, 由中部向南北逐渐减小。风向相比风速的预报效果要差, WRF 和EC 细网格的风向预报误差在45°～50°, 有一定的参考意义; 港湾岛屿代表站风向的平均绝对误差大于沿海代表站, 以浮标站的误差最大。当观测风速出现7 级及以上风速时, 若对大风进行分级检验, 则较低风速的预报平均绝对误差小于较高风速; 风向预报的平均绝对误差也大大降低, 且误差都在45°以内, 具有良好的参考性。  相似文献