Seismic tests on reinforced concrete and steel frames retrofitted with dissipative braces     

F. J. Molina  S. Sorace  G. Terenzi  G. Magonette  B. Viaccoz 《地震工程与结构动力学》2004,33(15):1373-1394

Seismic tests have been conducted on two 3‐storey structures protected with pressurized fluid‐viscous spring damper devices. One of the structures was a reinforced concrete frame with clay elements in the slabs, while the other one was a steel frame with steel/concrete composite slabs. The spring dampers were installed through K bracing in between the floors. The tests were performed by means of the pseudodynamic method, which allowed the use of large and full‐size specimens, and by implementing a specific compensation strategy for the strain‐rate effect at the devices. The test results allowed the verification of the adequacy of the attachment system as well as the comparison of the behaviour of the unprotected buildings with several protected configurations, showing the benefits of the application of the devices and the characteristics of their performance. The response of the protected structures was always safer than that of the unprotected ones mainly due to a significant increase of equivalent damping. The increase in the damping ratio depends on the level of deformation. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

河流调整中的熵、熵产生和能耗率的变化   总被引：8，自引：0，他引：8       下载免费PDF全文

徐国宾  练继建 《水科学进展》2004,15(1):1-5

河流是一个真正的开放系统,而不是孤立系统或封闭系统。运用经典热力学和非平衡态热力学基本原理,分析研究了河流调整中的熵、熵产生和能耗率的变化。指出:熵和熵产生是两个不同的概念;最小熵产生原理等价于最小能耗率原理;冲积河流在调整过程中遵循最小熵产生原理或最小能耗率原理,而不是最大熵原理。  相似文献   

Estimate of Loading Rate for a TBM Machine Based on Measured Cutter Forces   总被引：1，自引：1，他引：1  

Z. X. Zhang 《Rock Mechanics and Rock Engineering》2004,37(3):239-248

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Oxidation of As-bearing gold ore—a comparison of batch and column experiments     

《Journal of Geochemical Exploration》2004,81(1-3):59-70

This study deals with the experimental determination of the rate of weathering and As release from Au-bearing sulfide ores of the Mokrsko-West deposit (Czech Republic). The elevated As contents in the ore and the possible As mobilisation must be taken into account due to the close proximity of the deposit to the Vltava River, a source of drinking water for Prague. Crushed and homogenized ore material was divided into four grain-size fractions showing uniform chemical and mineralogical composition and subjected to batch and column leaching experiments. The most important reactions controlling metal leaching include (i) oxidation of sulfides, (ii) carbonate equilibrium and (iii) precipitation of hydrated ferric oxides (HFO). Hydrated ferric oxides were found to be important sorbents of mobilized As. The highest concentration of As in the leachates was obtained from the 64–1000 μm fraction. The oxidation rate in the agitated batch experiment calculated on the basis of sulfate concentrations is an order of magnitude higher (3.8×10⁻⁹ to 4.4×10⁻⁸ mol SO₄²⁻ h⁻¹ g⁻¹) than in the static column experiment (9.6×10⁻¹⁰ to 7.4×10⁻⁹ mol SO₄²⁻ h⁻¹ g⁻¹). The higher oxidation rate of batch experiments is explained by abrasion of oxidation products (mainly HFO) and by further exposition of reaction surfaces of the sulfide grains.  相似文献   

川西亚高山三个森林群落的湿林冠蒸发速率     

杨万勤  王开运  肖玲 《山地学报》2004,22(5):598-605

于3个假说和林冠上方2m处的气象变量，采用Penman-Monteith组合模型估算了一个生长季节内川西亚高山林区分别以云杉(SF)、冷杉(FF)和白桦(BF)为优势树种的3个林分的湿林冠蒸发速率(Er)。研究结果表明，SF、FF和BF的湿林冠蒸发量(E)分别为44．51mm、88．51mm和57．8mm，分别占总降雨量的9．2％、16．6％和10．2％。与SF和BF相比，FF具有最高的月平均Er和蒸发比例。SF、FF和BF的平均Er分别为0．097mm／h(变化范围：0．028-0．487mm／h)、0．242mm／h(变化范围：0．068～0．711mm／h)和0．149mm／h(0．060～0．576mm／h)。最高和最低的月平均Er分别在6月(SF、FF和BF分别为0．120mm／h、0．317mm／h和0．169mm／h)和10月(SF、FF和BF分别为0．083mm／h、0．187mm／h和0．101mm／h)。8：00至16：00期间的平均点Er显著高于0：00至8：00以及16：00至0：00期间的平均Er。Er显著的日变化和月变化主要归因于林冠上方的太阳辐射、空气温度和相对湿度的变化。  相似文献   

乌拉苔草光合速率日变化及日同化量   总被引：10，自引：0，他引：10  

徐惠风  刘兴土  徐克章 《湿地科学》2004,2(2):128-132

乌拉苔草沼泽是长白山沟谷湿地的重要类型 ,对其光合速率研究的结果表明 ,乌拉苔草光合速率日变化呈单峰曲线 ,最高峰出现在 1 0时 ,最大值是 1 8.0 7μmol(CO2 ) / (m2 ·s) ;与其该群落伴生的修氏苔草光合速率日变化出现“午休”现象。影响光合速率最大的环境因素是光量子通量密度和叶温 ,呈极显著的正相关 ,其他因素亦多呈正相关 ,环境因子综合影响了乌拉苔草的光合日进程。乌拉苔草光合作用的日总同化量为 1 896 0 1 .2 μmol(CO2 ) /m2 ,是光合能力较强的一种沼泽植物  相似文献   

长江三峡GPS处理结果和应变背景场   总被引：1，自引：0，他引：1  

杜瑞林  乔学军  杨少敏  王琪 《武汉大学学报(信息科学版)》2004,29(9):768-771

采用BerneseGPSSoftware 4 .2对长江三峡工程诱发地震监测系统GPS监测网络 1998～ 2 0 0 3年的 6期观测数据进行了处理 ,结果表明 ,三峡库区与华南块体的水平相对运动在 0～ 3mm/a(± 0 .1～± 2 .0mm/a) ;蓄水导致的垂直形变区域主要集中在茅坪 香溪 巴东库段 ,近岸点垂直沉降的量级在 10～ 35mm左右 ,最大峰值区域香溪约 35mm(± 8.6mm) ,垂直形变沿远离库中心方向迅速衰减。采用贝塞尔双三次样条函数模型拟合该地区的应变率 ,推算各类水平应变场 ,结果表明 ,蓄水前各种应变背景在 10 -9/a～ 10 -10 /a量级。作为构造稳定地区 ,三峡库区近期因蓄水导致大规模形变 ,从而诱发中强地震的可能性不大  相似文献   

Paleo-earthquake studies on the eastern section of the Kunlun fault   总被引：1，自引：0，他引：1  

李春峰  贺群禄  赵国光 《地震学报(英文版)》2005,18(1):64-71

Introduction East Kunlun active fault is one of the largest sinistral slip fault zones in northern Tibetan Pla-teau. The fault tails primarily after the ancient eastern Kunlun suture zone, which was reactivatedby the northward subduction of the Indian plate beneath the Eurasian plate. The western end of thefault starts near the western flank of the Buxedaban peak in Qinghai Province. The fault then ex-tends eastwards through the Kusai Lake, Xidatan, Dongdatan, Alag Lake, Tuosuo Lak…  相似文献   

Primary component analysis method and reduction of seismicity parameters     

王炜  马钦忠  林命周  吴耿锋  吴绍春 《地震学报(英文版)》2005,18(5):562-571

Introduction Data mining (SHAO and YU, 2003) is a new kind of technique developed with database and artificial intelligence in recent years, which processes the data in the database to abstract the im- plied and pre-unknown, but potentially useful information and knowledge from large amounts of incomplete, noisy, blurring and stochastic data. For data mining, data purging is an important link beforehand that includes eliminating noise, making up lost domain, and deleting ineffective data, as…  相似文献   

Photosynthesis-transpiration coupling model at canopy scale in terrestrial ecosystem   总被引：1，自引：0，他引：1  

REN Chuanyou  YU Guirui  WANG Qiufeng  Guan Dexin 《中国科学D辑(英文版)》2005,48(Z1)

At the hypothesis of big leaf, an ecosystem photosynthesis-transpiration coupling cycle model was established by the scaled SMPT-SB model from single leaf to canopy, and model parameterization methods were discussed. Through simulating the canopy light distribution, canopy internal conductance to CO2 can be scaled from single leaf to canopy by integrating to canopy using the relationship between single internal conductance and photosynthetic photon flux density. Using the data observed by eddy covariance method from the Changbai Mountains site of ChinaFLUX, the application of the model at the canopy scale was examined. Under no water stress, the simulated net ecosystem photosynthesis rate fitted with the observed data very well, the slope and R2 of the line regression equation of the observed and simulated values were 0.7977 and 0.8892, respectively (n = 752), and average absolute error was 3.78 μmol CO2 m-2s-1; the slope, R2 and average absolute error of transpiration rate were 0.7314, 0.4355 and 1.60mmol H2O m-2 s-1, respectively (n = 752). The relationship between canopy photosynthesis,transpiration and external environmental conditions was discussed by treating the canopy as a whole and neglecting the comprehensive feedback mechanism within canopy, and it was noted that the precipitation course affected the transpiration rate simulation badly. Compared to the models based on eco-physiological processes, the SMPT-SB model was simple and easy to be used. And it can be used as a basic carbon and water coupling model of soil-plant-atmosphere continuum.  相似文献